KR20230047163A - Reinforcing film, optical member and electronic member - Google Patents

Abstract

Provided is a reinforcing film that exhibits easy peelability in the initial stage of sticking to an adherend, can greatly increase the adhesive force thereafter, and has bending recovery and bending holding power. The reinforcing film includes an adhesive layer. The pressure-sensitive adhesive layer contains a polymer (A) and a polymer (B). The polymer (B) includes a monomer unit having a polyorganosiloxane backbone and a (meth)acrylic monomer unit. Further, the pressure-sensitive adhesive layer has a surface modulus of elasticity of 1 to 20 kPa at 23°C. In addition, the glass transition temperature T _B of the polymer (B) is -20°C to 5°C.

Description

Reinforcing film, optical member and electronic member

The present invention relates to a reinforcing film and an optical member and an electronic member to which the reinforcing film is bonded. This application claims priority based on Japanese Patent Application No. 2020-134188 filed on August 6, 2020, the entire content of the application is incorporated herein by reference.

The adhesive is in the form of an adhesive sheet, for the purpose of bonding between adherends or fixing articles to adherends, various uses such as portable electronic devices such as mobile phones, smartphones, tablet personal computers, and other electronic devices is widely used in For example, an adhesive sheet is used as a reinforcing material (reinforcing film) that imparts rigidity and impact resistance to an optical member or an electronic member constituting the device. Patent Documents 1 and 2 are cited as documents disclosing this type of prior art.

In recent years, portable electronic devices that can be bent or rounded have been attracting attention, and flexible devices (typically, image display devices such as organic EL and liquid crystal displays) incorporated in such electronic devices are fixed, etc. Development of usable adhesive sheets is progressing (Patent Documents 3 to 6).

On the other hand, when focusing on the performance of the adhesive, recently, a pressure-sensitive adhesive sheet that exhibits low adhesive strength in the initial stage of sticking to an adherend and can greatly increase the adhesive strength thereafter has been proposed (Patent Document 7). According to the PSA sheet having such characteristics, before the increase in the adhesive strength, it exhibits re-stickability (rework property) useful for suppressing yield reduction due to adhesion failure or damage to the PSA sheet, and after the increase in the adhesive strength, the PSA sheet It is possible to exhibit strong adhesiveness suitable for the original purpose of use.

Japanese Patent No. 6366199 Japanese Patent No. 6366200 Japanese Patent No. 6376271 Japanese Patent Application Publication No. 2016-108555 Japanese Patent Application Publication No. 2017-095657 Japanese Patent Application Publication No. 2017-095659 Japanese Patent No. 6373458

A reinforcing film may also be used for the flexible device. For example, in the manufacture of the above-mentioned flexible device, since many of the members constituting the device are thin, an adhesive sheet is applied as a reinforcing film to reinforce it, thereby preventing problems caused by deformation of the device or handling It is desirable to raise the castle. Since a flexible device can be repeatedly bent, bent, or bent, the reinforcing film used for the flexible device has a characteristic of recovering its normal shape even when repeatedly bent (bending recovery property), and also exhibits peeling, etc. It is required to have a characteristic (bending holding force) that does not cause the problem of. Since such a reinforcing film having bending recovery and bending holding power can be used for various applications including flexible devices, it is useful because the application range is limited.

For example, as proposed in Patent Document 7, even for an adhesive configured to exhibit low adhesive force at the initial stage of sticking and then greatly increase the adhesive force, when used as a reinforcing film, bending recovery and bending holding power It is desirable to have As one method of improving the bending holding force, for example, a method of appropriately setting the storage elastic modulus of the pressure-sensitive adhesive can be considered. However, in the pressure-sensitive adhesive designed to increase the adhesive force as described above, when the storage elastic modulus is changed, both the initial low adhesive force and the increased adhesive force are affected. In addition, considering the bending recovery in addition to the bending holding force, it is not easy to satisfy all of these characteristics. It is useful for practical use if the bending recovery and bending holding power can be improved with respect to the adhesive which shows low adhesive force at the initial stage of sticking and whose adhesive force greatly increases thereafter.

The present invention was created in view of the above circumstances, and exhibits easy peelability in the initial stage of sticking to an adherend, thereafter it is possible to greatly increase the adhesive force, and a reinforcing film having bending recovery and bending holding power. is intended to provide Another object of the present invention is to provide an optical member and an electronic member to which the reinforcing film is adhered.

According to this specification, the reinforcement film provided with the adhesive layer is provided. The pressure-sensitive adhesive layer contains a polymer (A) and a polymer (B). The polymer (B) includes a monomer unit having a polyorganosiloxane backbone and a (meth)acrylic monomer unit. Further, the pressure-sensitive adhesive layer has a surface modulus of elasticity of 1 to 20 kPa at 23°C. In addition, the glass transition temperature T _B of the polymer (B) is -20°C to 5°C.

According to the above configuration, since the pressure-sensitive adhesive layer contains the polymer (A) and the polymer (B) containing a monomer unit having a polyorganosiloxane backbone, it exhibits easy peelability in the initial stage of sticking to an adherend, and thereafter , it is possible to greatly increase the adhesive force. In addition, when the glass transition temperature (Tg) T _B of the polymer (B) is -20 ° C. or higher, the easy peelability at the initial stage of application tends to be excellent, and when the T _B is 5 ° C. or lower, the adhesive force increasing tendency tends to be excellent there is. In addition, the reinforcing film has bending recoverability and bending holding power. Specifically, a reinforcement film having a surface modulus of elasticity at 23°C (surface elasticity at 23°C) of the pressure-sensitive adhesive layer of 1 kPa or more exhibits the adhesive properties described above and has good bending recovery properties. In addition, since the 23 ° C. surface modulus of the pressure-sensitive adhesive layer is 20 kPa or less, it exhibits the above adhesive properties and has good bending holding power, so even when used in a manner that is repeatedly bent and bent, problems such as peeling are unlikely to occur. .

In some preferred embodiments of the technology disclosed herein (including a reinforcing film, an optical member, and an electronic member. The same applies hereinafter), the pressure-sensitive adhesive layer has a bulk modulus of elasticity G′ ₂₃ at 23° C. of 10 to 200 kPa. According to the adhesive which has bulk elasticity modulus _G'23 in this range, the adhesive force of an initial stage of sticking tends to fall into the suitable range excellent in easy peelability. In addition, it is excellent in processability, and generally tends to be easy to achieve both strain relaxation and bending recovery in the normal temperature range.

In some preferred embodiments, the pressure-sensitive adhesive layer has a bulk modulus of elasticity G' ₈₀ at 80°C of 5 to 100 kPa. An adhesive having a bulk modulus of elasticity G' ₈₀ within this range generally tends to achieve both bending recovery and bending holding power. For example, even when used under high temperature conditions of around 80°C, it may have elasticity suitable for bending recovery and adhesive holding force that realizes bending holding force.

In some preferred embodiments, the pressure-sensitive adhesive layer has a tanδ ₈₀ of 0.10 to 0.60 at 80°C. A pressure-sensitive adhesive having tanδ ₈₀ (loss modulus G" at ₈₀ °C/storage modulus G' ₈₀ at 80°C) of 0.10 or more tends to exhibit adhesive strength suitable for bending retention. In addition, when tanδ ₈₀ is 0.60 or less, , Plastic deformation of the pressure-sensitive adhesive is suppressed, and good bending recovery property is easily obtained.In addition, even when the reinforcing film is held in a bent state for a long time, it is easy to exhibit holding force (bending holding force) that does not cause peeling from the adherend. .

The polymer (A) is preferably an acrylic polymer. According to the pressure-sensitive adhesive layer comprising the polymer (A), which is an acrylic polymer, and the polymer (B) containing a monomer unit having a polyorganosiloxane backbone, the effect of the technique disclosed herein is preferably realized.

In some preferred embodiments, the content of the polymer (B) in the pressure-sensitive adhesive layer is 0.5 to 5 parts by weight based on 100 parts by weight of the polymer (A). When the amount of the polymer (B) relative to 100 parts by weight of the polymer (A) is 0.5 part by weight or more, easy peelability in the initial stage of sticking is easily obtained. By setting the amount of the polymer (B) to 5 parts by weight or less, it is easy to achieve the desired increase in adhesive force. In addition, by setting the usage amount of the polymer (B) within the above range, it is easy to realize good bending recovery and bending holding power.

In some preferred embodiments, the molar ratio ([NCO]/[OH]) of isocyanate groups and hydroxyl groups included in the pressure-sensitive adhesive layer is 0.002 to 0.03. A pressure-sensitive adhesive layer having the molar ratio ([NCO]/[OH]) of 0.002 or more tends to have excellent bending recovery properties and tends to have excellent processability. Further, by setting the molar ratio ([NCO]/[OH]) to 0.03 or less, it tends to be easy to achieve a suitable increase in adhesive strength. Also, in the pressure-sensitive adhesive layer, isocyanate groups and hydroxyl groups may exist in a state in which at least a part thereof is chemically bonded (crosslinked). The pressure-sensitive adhesive layer contains, for example, a crosslinking agent, and in this configuration, the isocyanate group is, for example, a part of the crosslinking agent, and the hydroxyl group may be, for example, a part of the polymer (A).

The reinforcing film disclosed herein is suitable as a reinforcing film that imparts rigidity and impact resistance to an optical member such as a polarizing plate or a wave plate during processing or conveyance. Therefore, according to the present specification, an optical member to which any of the reinforcing films disclosed herein is bonded is provided.

In addition, the reinforcing film disclosed herein is also suitable as a reinforcing film for electronic members of devices such as portable electronic devices, for example. Therefore, according to the present specification, an electronic member to which any of the reinforcing films disclosed herein is bonded is provided.

1 is a cross-sectional view schematically showing the configuration of a reinforcement film according to an embodiment.
Fig. 2 is a cross-sectional view schematically showing the configuration of a reinforcement film according to another embodiment.
Fig. 3 is a cross-sectional view schematically showing the configuration of a reinforcement film according to another embodiment.

Hereinafter, preferred embodiments of the present invention will be described. Matters other than matters specifically mentioned in this specification and necessary for the practice of the present invention can be understood by those skilled in the art based on the teachings for the practice of the invention described in this specification and common technical knowledge at the time of filing. The present invention can be implemented based on the content disclosed in this specification and common technical knowledge in the field.

Note that in the following drawings, the same reference numerals may be given to members/parts exhibiting the same action, and overlapping explanations may be omitted or simplified. In addition, the embodiments described in the drawings are modeled in order to clearly explain the present invention, and do not necessarily accurately represent the size or scale of products actually provided.

In addition, in this specification, "acrylic polymer" refers to a polymer containing a monomer unit derived from a (meth)acrylic monomer in a polymer structure, typically 50% by weight of a monomer unit derived from a (meth)acrylic monomer. It refers to a polymer containing an excess ratio. In addition, a (meth)acrylic monomer refers to a monomer having at least one (meth)acryloyl group in one molecule. Here, "(meth)acryloyl group" is the meaning which points out an acryloyl group and a methacryloyl group comprehensively. Therefore, the concept of the (meth)acrylic monomer here may include both a monomer having an acryloyl group (acrylic monomer) and a monomer having a methacryloyl group (methacrylic monomer). Similarly, in this specification, "(meth)acrylic acid" means acrylic acid and methacrylic acid, and "(meth)acrylate" comprehensively points out acrylate and methacrylate, respectively.

<Structure example of reinforcing film>

The reinforcing film disclosed herein has a form of an adhesive sheet having an adhesive face formed by an adhesive. The adhesive sheet used as a reinforcing film is comprised including the adhesive layer. The reinforcing film disclosed herein may be in the form of a pressure-sensitive adhesive sheet having a base material in which the pressure-sensitive adhesive layer is laminated on one side or both sides of a supporting base material, or may be in the form of an inorganic material pressure-sensitive adhesive sheet having no supporting base material.

In addition, in this specification, "reinforcement film" means the adhesive sheet (reinforcement adhesive film) used for reinforcement of a to-be-adhered body so that it may mention later. The reinforcing film is, for example, in the form of an inorganic adhesive sheet, and can be reinforced by attaching a support material or the like to one adhesive surface and then attaching the other adhesive surface to an adherend to be reinforced. It is not limited to the shape of the adhesive sheet. In this regard, it is understood as a concept in a broader sense than the later-described "reinforcement film" having the form of an adhesive sheet with a base material.

The structure of the reinforcement film concerning one embodiment is schematically shown in FIG. This reinforcing film 1 consists of a sheet-shaped support substrate 10 having a first surface 10A and a second surface 10B, and an adhesive layer 21 provided on the first surface 10A side. It is comprised as a single-sided adhesive sheet with a base material provided. The pressure-sensitive adhesive layer 21 is adhered to the first surface 10A side of the supporting substrate 10 . The reinforcing film 1 is used by sticking the adhesive layer 21 on the adherend. As shown in FIG. 1, the reinforcement film 1 before use (namely, before sticking to an adherend) has a surface (adhesive surface) 21A of the pressure-sensitive adhesive layer 21 at least the pressure-sensitive adhesive layer 21 ) may be a component of the reinforcing film 100 with a release liner in a form in which the side opposite to the release liner abuts against the release liner 31 serving as a release surface (release surface). As the release liner 31, for example, one configured so that the single side becomes a release surface by forming a release layer by a release treatment agent on one side of a sheet-like substrate (liner substrate) can be preferably used. Alternatively, the release liner 31 is omitted, and the adhesive surface 21A is formed by winding the reinforcing film 1 using the support substrate 10 in which the second surface 10B is a release surface ( 10) may be in a form (roll form) in contact with the second surface 10B. When sticking the reinforcing film 1 on an adherend, peeling the 2nd surface 10B of the peeling liner 31 or the support base material 10 from the adhesive surface 21A, and 21 A of exposed adhesive surfaces Press on the adherend.

2 schematically shows the structure of a reinforcing film according to another embodiment. This reinforcing film 2 includes a sheet-shaped support substrate 10 having a first surface 10A and a second surface 10B, an adhesive layer 21 provided on the first surface 10A side, , It is comprised as a double-sided adhesive sheet with a base material provided with the adhesive layer 22 provided on the 2nd surface 10B side. The pressure-sensitive adhesive layer (first pressure-sensitive adhesive layer) 21 is on the first surface 10A of the supporting base material 10, and the pressure-sensitive adhesive layer (second pressure-sensitive adhesive layer) 22 is on the second surface 10B of the supporting base material 10. , are attached to each other. The reinforcement film 2 is used by sticking the pressure-sensitive adhesive layers 21 and 22 to other locations of the adherend. The location where the pressure-sensitive adhesive layers 21 and 22 are affixed may be each location on another member or may be another location within a single member. As shown in FIG. 2, the reinforcing film 2 before use has a surface (first adhesive surface) 21A of the pressure-sensitive adhesive layer 21 and a surface (second adhesive surface) 22A of the pressure-sensitive adhesive layer 22. ) may be a component of the reinforcing film 200 with a release liner in a form in which at least the side opposite to the pressure-sensitive adhesive layers 21 and 22 is in contact with the release liners 31 and 32 serving as release surfaces, respectively. As the release liners 31 and 32, for example, those configured so that the single side becomes a release surface by forming a release layer by a release treatment agent on one side of a sheet-like substrate (liner substrate) can be preferably used. Alternatively, by omitting the release liner 32 and using the release liner 31 whose both surfaces are release surfaces, overlapping this and the reinforcing film 2 and winding them in a spiral winding, the second adhesive face 22A A reinforcing film with a release liner may be constituted in a form (roll form) in contact with the back surface of the release liner 31 .

3 schematically shows the structure of a reinforcing film according to yet another embodiment. This reinforcing film 3 is constituted as an inorganic double-sided pressure-sensitive adhesive sheet composed of an adhesive layer 21 . The reinforcing film 3 is on the first adhesive surface 21A constituted by one surface (first surface) of the pressure-sensitive adhesive layer 21 and the other surface (second surface) of the pressure-sensitive adhesive layer 21. The second adhesive surface 21B constituted by affixed to another part of the adherend is used. As shown in Fig. 3, the reinforcing film 3 before use has the first adhesive face 21A and the second adhesive face 21B at least at the side facing the adhesive layer 21 as a release face. It may be a component of the reinforcing film 300 with a peeling liner in a form in contact with the peeling liners 31 and 32. Alternatively, by omitting the release liner 32 and using the release liner 31 having both surfaces as release surfaces, overlapping this and the reinforcing film 3 and winding them in a spiral winding shape, the second adhesive face 21B is formed. A reinforcing film with a release liner may be constituted in a form (roll form) in contact with the back surface of the release liner 31 .

In addition, the reinforcing film may be in the form of a roll or a single sheet, or may be cut into an appropriate shape depending on the use or mode of use, or may be subjected to punching or the like. The pressure-sensitive adhesive layer in the technique disclosed herein is typically formed continuously, but is not limited to this, and may be formed in a regular or random pattern such as a dot shape or a stripe shape, for example.

<Adhesive layer>

The reinforcing film disclosed herein includes a polymer (A) and an adhesive layer containing a polymer (B). Such an adhesive layer may be formed from an adhesive composition containing a polymer (A) that is a complete or partial polymer of the monomer raw material A, and a polymer (B). The form of the pressure-sensitive adhesive composition is not particularly limited, and may be, for example, various forms such as solvent type, water dispersion type, hot melt type, active energy ray curing type (eg photocurable type).

(Surface modulus at 23°C)

The pressure-sensitive adhesive layer disclosed herein is characterized by having a surface elastic modulus at 23°C (23°C surface elastic modulus) of the surface (adhesive surface) in the range of 1 to 20 kPa. When the 23°C surface modulus is 1 kPa or more, it is possible to have good bending recovery while realizing adhesive properties based on the inclusion of the polymer (A) and the polymer (B). In addition, when the surface elastic modulus is 20 kPa or less, a good bending holding force can be exhibited while realizing the adhesive properties.

From the viewpoint of improving bending recovery, the 23°C surface modulus is preferably 2 kPa or more, more preferably 3 kPa or more, still more preferably 4 kPa or more (eg 5 kPa or more), and 8 kPa or more. It may be 10 kPa or more, or 12 kPa or more (for example, 14 kPa or more) may be sufficient. The higher the surface elastic modulus, the better the initial light peelability tends to be. Further, from the viewpoint of favorably exhibiting an increase in adhesive force while achieving both good bending recovery and bending holding power, the 23°C surface elasticity modulus is suitably 15 kPa or less, preferably 12 kPa or less, and more preferably 9 kPa or less. , More preferably, it is 7 kPa or less (for example, 6 kPa or less), and may be 4 kPa or less.

The 23°C surface modulus of elasticity of the pressure-sensitive adhesive layer is the type and characteristics (molecular weight, glass transition temperature, molecular structure, etc.) of polymer (A) and the type (chemical structure, etc.) and characteristics (molecular weight, glass transition temperature, etc.) of polymer (B) , It can be adjusted by the amount used, the type or amount of crosslinking agent, and the like. The 23° C. surface modulus of elasticity of the pressure-sensitive adhesive layer was measured by the method described in Examples below.

(23℃ bulk modulus G' ₂₃ )

The bulk modulus of elasticity G' ₂₃ at 23°C of the pressure-sensitive adhesive layer (bulk modulus of elasticity G' ₂₃ at 23°C) is appropriately set within a range that satisfies the range of the surface elastic modulus at 23°C, and is not limited to a specific range. In some embodiments, the 23°C bulk modulus G' ₂₃ of the pressure-sensitive adhesive layer is suitably 10 kPa or more. By making the said bulk elasticity modulus _G'23 more than a predetermined value, the adhesive force of an initial stage of sticking tends to become the suitable range excellent in easy peelability. In addition, it tends to be excellent in processability and generally excellent in bending recovery in a normal temperature range. The bulk modulus G' ₂₃ is preferably 15 kPa or more, more preferably 20 kPa or more, even more preferably 25 kPa or more, and particularly preferably 30 kPa or more. In some other aspects, the bulk modulus G' ₂₃ may be 50 kPa or more, 80 kPa or more, or 100 kPa or more.

In some embodiments, the 23°C bulk modulus G' ₂₃ of the pressure-sensitive adhesive layer is suitably 200 kPa or less. The pressure-sensitive adhesive having the bulk modulus G' ₂₃ of a predetermined value or less generally tends to be excellent in strain relief in a normal temperature range and tends to exhibit an increase in adhesive strength. The bulk modulus G' ₂₃ is preferably 150 kPa or less, more preferably 90 kPa or less. In some preferred embodiments, the bulk modulus G′ ₂₃ may be 60 kPa or less, or 40 kPa or less (for example, 35 kPa or less).

(80℃ bulk modulus G' ₈₀ )

The bulk modulus of elasticity G' ₈₀ at 80°C of the pressure-sensitive adhesive layer (bulk modulus of elasticity G' ₈₀ at 80°C) is appropriately set within a range satisfying the range of the surface elasticity at 23°C, and is not limited to a specific range. In some embodiments, the 80°C bulk modulus G' ₈₀ of the pressure-sensitive adhesive layer is preferably 5 kPa or more. By setting the bulk elastic modulus G' ₈₀ to a predetermined value or more, the bending recovery property tends to be generally improved, and even when used under high-temperature conditions, it can have elasticity suitable for bending recovery. In some preferred aspects, the bulk modulus G' ₈₀ may be 7 kPa or more, 9 kPa or more, or 10 kPa or more. In some other aspects, the said bulk modulus G' ₈₀ may be 15 kPa or more, 30 kPa or more, or 50 kPa or more.

In some embodiments, the 80°C bulk modulus G' ₈₀ of the pressure-sensitive adhesive layer is suitably 100 kPa or less. By restricting the bulk modulus G' ₈₀ to a predetermined value or less, it is generally easy to obtain a good bending holding force, and to achieve both bending recovery and bending holding force. For example, in various environments including high-temperature conditions, it may have elasticity suitable for bending recovery and adhesive holding force that realizes bending holding force. The bulk modulus G' ₈₀ is preferably 90 kPa or less, more preferably 60 kPa or less. In some embodiments, the bulk modulus G′ ₈₀ may be 20 kPa or less, 16 kPa or less, or 14 kPa or less (eg 12 kPa or less).

(80℃ tanδ ₈₀ )

The tanδ ₈₀ (80°C tanδ ₈₀ ) of the pressure-sensitive adhesive layer at 80°C is appropriately set within a range that satisfies the range of the surface elastic modulus at 23°C, and is not limited to a specific range. In some embodiments, the 80°C tanδ ₈₀ of the pressure-sensitive adhesive layer is preferably 0.10 or more. As the tan δ ₈₀ is higher, the pressure-sensitive adhesive tends to exhibit adhesive strength suitable for bending. The tan δ ₈₀ is preferably 0.20 or more. In some preferred embodiments, the tan δ ₈₀ may be 0.30 or more, 0.40 or more, or 0.45 or more.

In some embodiments, the 80°C tanδ ₈₀ of the pressure-sensitive adhesive layer is preferably 0.60 or less. When the tan δ ₈₀ is 0.60 or less, plastic deformation of the pressure-sensitive adhesive is suppressed, and good bending recovery property is easily obtained. In addition, even when the reinforcing film is held in a bent state for a long time, it is easy to exhibit a holding force that does not cause peeling from the adherend. In addition, the increase in adhesive strength tends to fall within a suitable range. The 80°C tan δ ₈₀ may be 0.55 or less. In some other embodiments, the 80°C tan δ ₈₀ may be 0.50 or less, or 0.35 or less.

The 23°C bulk modulus G' ₂₃ , 80°C bulk modulus G' ₈₀ and 80°C tanδ ₈₀ of the pressure-sensitive adhesive layer depend on the type and characteristics of the polymer (A) (molecular weight, glass transition temperature, molecular structure, etc.) and that of the polymer (B). It can be controlled by the type (chemical structure, etc.), characteristics (molecular weight, glass transition temperature, etc.), amount used, type and amount of crosslinking agent, etc. The 23°C bulk modulus G' ₂₃ , the 80°C bulk elastic modulus G' ₈₀ , and the 80°C tanδ ₈₀ of the pressure-sensitive adhesive layer are measured by the methods described in Examples described later.

(Polymer (A))

As the polymer (A), rubber in the room temperature region, such as acrylic polymers, rubber polymers, polyester polymers, urethane polymers, polyether polymers, silicone polymers, polyamide polymers, fluorine polymers, etc. known in the field of pressure-sensitive adhesives One type or two or more types of various polymers exhibiting elasticity can be used. In the reinforcing film disclosed herein, the polymer (A) is typically the main component of the polymer component contained in the pressure-sensitive adhesive layer, that is, a component occupying more than 50% by weight, for example, 75% by weight or more of the polymer component. It may be a component that occupies. In some embodiments, the polymer (A) is a component occupying more than 50% by weight of the entire pressure-sensitive adhesive layer, may be a component occupying 70% by weight or more, may be a component occupying 80% by weight or more, or 90% by weight or more It may be a component occupying 95% by weight or more (for example, 97% by weight or more).

The glass transition temperature T _A of the polymer (A) is not particularly limited, and can be selected so as to obtain desirable characteristics in the reinforcing film disclosed herein. In some embodiments, a polymer (A) having a T _A of less than 0°C can be preferably employed. Since the adhesive containing such a polymer (A) exhibits appropriate fluidity (for example, the mobility of polymer chains contained in the adhesive), realization of a reinforcing film in which the adhesive force increases to a predetermined value or more by heating. suitable for The reinforcing film disclosed herein can preferably be implemented using a polymer (A) having a T _A of less than -10°C, less than -20°C, less than -30°C, or less than -35°C. In some embodiments, T _A may be less than -40°C or less than -50°C. In some preferred embodiments, T _A is -55°C or lower, more preferably -58°C or lower, even more preferably -62°C or lower, and may be -65°C or lower (eg -66°C or lower). The lower limit of T _A is not particularly limited. From the viewpoint of easy availability of the material and improvement of the cohesive force of the pressure-sensitive adhesive layer, usually, a polymer (A) having a T _A of -80°C or higher and -70°C or higher can be preferably employed. In some embodiments, T _A may be, for example, -63°C or higher, -55°C or higher, -50°C or higher, or -45°C or higher.

Here, in this specification, the glass transition temperature (Tg) of a polymer (for example, the glass transition temperature of a polymer (A) or a polymer (B) described later) is a nominal value described in literature or catalogs, or a corresponding value. It refers to the Tg calculated by the Fox formula based on the composition of the monomer raw material used in the preparation of the polymer. As described below, the Fox formula is a relational expression between the Tg of the copolymer and the glass transition temperature Tgi of a homopolymer obtained by homopolymerization of each of the monomers constituting the copolymer.

1/Tg = Σ (Wi/Tgi)

In the Fox equation, Tg is the glass transition temperature of the copolymer (unit: K), Wi is the weight fraction of monomer i in the copolymer (copolymerization ratio by weight), and Tgi is the glass transition of the homopolymer of monomer i Indicates the transition temperature (unit: K). When the target polymer related to Tg specification is a homopolymer, the Tg of the homopolymer and the Tg of the target polymer coincide.

As the glass transition temperature of the homopolymer used for calculation of Tg, the value described in known materials shall be used. Specifically, numerical values are illustrated in "Polymer Handbook" (3rd edition, John Wiley & Sons, Inc., 1989). For a monomer for which a plurality of types of values are described in the above Polymer Handbook, the highest value is adopted.

As the glass transition temperature of a homopolymer of a monomer not described in the above Polymer Handbook, a value obtained by the following measuring method shall be used.

Specifically, 100 parts by weight of monomer, 0.2 part by weight of 2,2'-azobisisobutyronitrile and 200 parts by weight of ethyl acetate as a polymerization solvent were added to a reactor equipped with a thermometer, stirrer, nitrogen inlet pipe and reflux condenser. and stirred for 1 hour while passing nitrogen gas. After removing oxygen in the polymerization system in this way, the temperature is raised to 63°C and reacted for 10 hours. Next, it cools to room temperature and obtains a homopolymer solution with a solid content concentration of 33% by weight. Next, this homopolymer solution was cast-coated on a release liner and dried to prepare a test sample (sheet-shaped homopolymer) having a thickness of about 2 mm. This test sample was punched into a disk shape with a diameter of 7.9 mm, sandwiched between parallel plates, and subjected to shear deformation at a frequency of 1 Hz using a viscoelasticity tester (manufactured by TA Instruments Japan, model name "ARES"), while giving a temperature range of -70 ° C. Viscoelasticity is measured by shear mode at a heating rate of 5 °C/min to 150 °C, and the temperature corresponding to the peak top temperature of tan δ is taken as the Tg of the homopolymer.

Although not particularly limited, the weight average molecular weight (Mw) of the polymer (A) is usually preferably approximately 20×10 ⁴ or higher. According to the polymer (A) of such Mw, it is easy to obtain an adhesive exhibiting good cohesiveness. From the viewpoint of obtaining a higher cohesive force, in some preferred embodiments, the Mw of the polymer (A) may be, for example, 30 × 10 ⁴ or more, 40 × 10 ⁴ or more, or 50 × 10 ⁴ or more, It may be 60×10 ⁴ or more, or 80×10 ⁴ or more. In addition, the Mw of the polymer (A) is usually preferably approximately 500×10 ⁴ or less. Since the polymer (A) of such a Mw tends to form an adhesive exhibiting appropriate fluidity (movement of the polymer chain), it is suitable for realization of a reinforcing film having low adhesive force at the initial stage of adhesion and a large increase in adhesive force. It is preferable also from the viewpoint of improving the compatibility with the polymer (B) that the Mw of the polymer (A) is not too high. In some preferred embodiments, the Mw of polymer (A) may be, for example, 250×10 ⁴ or less, 200×10 ⁴ or less, 150×10 ⁴ or less, 100×10 ⁴ or less, or 70 ×10 ⁴ or less may be sufficient.

In this specification, the Mw of the polymer (A) and the polymer (B) described later can be calculated in terms of polystyrene by gel permeation chromatography (GPC). More specifically, Mw can be measured in accordance with the methods and conditions described in Examples to be described later.

As the polymer (A) in the reinforcing film disclosed herein, an acrylic polymer can be preferably employed. When an acrylic polymer is used as the polymer (A), good compatibility with the polymer (B) tends to be easily obtained. The good compatibility of the polymer (A) and the polymer (B) is preferable because it can contribute to the reduction of the initial adhesive force and the improvement of the adhesive force after heating through the improvement of the mobility of the polymer (B) in the adhesive layer. In addition, an acrylic polymer having a high degree of freedom in molecular design is suitable as an adhesive material capable of improving adhesive properties, bending recovery and bending holding power in a well-balanced manner.

The acrylic polymer is, for example, a polymer containing 50% by weight or more of a monomer unit derived from an alkyl (meth)acrylate, that is, 50% by weight or more of the total amount of the monomer component (monomer raw material A) for preparing the acrylic polymer It may be a polymer that is a (meth)acrylic acid alkyl ester. As the (meth)acrylic acid alkyl ester, a (meth)acrylic acid alkyl ester having a linear or branched alkyl group having 1 to 20 carbon atoms (ie, C _1-20 ) can be preferably used. From the viewpoint of easy balancing of properties, the ratio of C _1-20 alkyl ester of (meth)acrylic acid in the monomer raw material A may be, for example, 50% by weight or more, or 60% by weight or more. In some preferred embodiments, the proportion of (meth)acrylic acid C _1-20 alkyl ester in the monomer raw material A is 70% by weight or more, more preferably 80% by weight or more, still more preferably 85% by weight or more, particularly preferably is 90% by weight or more. By using an acrylic polymer having such a monomer composition, it is easy to obtain an adhesive that achieves both an increase in adhesive strength, bending recovery and bending holding power in a well-balanced manner. The proportion of the (meth)acrylic acid C _1-20 alkyl ester in the monomer raw material A may be, for example, 99.9% by weight or less, 98% by weight or less, or 95% by weight or less. In some embodiments, the proportion of (meth)acrylic acid C _1-20 alkyl ester in the monomer raw material A may be, for example, 90% by weight or less, 85% by weight or less, or 80% by weight or less.

Non-limiting examples of the (meth)acrylic acid C _1-20 alkyl ester include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, Isobutyl (meth)acrylate, s-butyl (meth)acrylate, t-butyl (meth)acrylate, pentyl (meth)acrylate, isopentyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate, (meth)acrylate ) Octyl acrylate, 2-ethylhexyl (meth)acrylate, isooctyl (meth)acrylate, nonyl (meth)acrylate, isononyl (meth)acrylate, decyl (meth)acrylate, isodecyl (meth)acrylate, (meth) Undecyl acrylate, dodecyl (meth)acrylate, tridecyl (meth)acrylate, tetradecyl (meth)acrylate, pentadecyl (meth)acrylate, hexadecyl (meth)acrylate, heptadecyl (meth)acrylate, (meth)acrylic acid stearyl, isostearyl (meth)acrylate, nonadecyl (meth)acrylate, eicosyl (meth)acrylate, and the like.

Among these, at least a (meth)acrylic acid C _1-18 alkyl ester is preferably used, and at least a (meth)acrylic acid C _1-14 alkyl ester is more preferably used. In some embodiments, the acrylic polymer is a monomer of at least one selected from (meth)acrylic acid C _4-12 alkyl esters (preferably acrylic acid C _4-10 alkyl esters, for example, acrylic acid C _6-10 alkyl esters). It can be contained as a unit. For example, an acrylic polymer containing one or both of n-butyl (BA) acrylate and 2-ethylhexyl (2EHA) acrylate is preferred, and an acrylic polymer containing at least 2EHA is particularly preferred.

In some preferred embodiments, the proportion of acrylic acid C _6-10 alkyl ester (preferably acrylic acid C _8-9 alkyl ester, typically 2EHA) in the monomer raw material A for preparing the acrylic polymer is 70% by weight or more, More preferably, it is 80 wt% or more, still more preferably 85 wt% or more, and particularly preferably 90 wt% or more. Acrylic polymers of such a monomer composition are particularly suitable for realizing the effect of the technique disclosed herein. In addition, the proportion of C _6-10 alkyl ester of acrylic acid (preferably C _8-9 alkyl ester of acrylic acid, typically 2EHA) in the monomer raw material A may be, for example, 99.9% by weight or less, and the initial low adhesive strength and bending From the standpoint of recoverability or the like, it may be 98% by weight or less, or 95% by weight or less.

In some preferred embodiments, among the monomer raw materials A for preparing acrylic polymers, (meth)acrylic acid C _1-3 alkyl esters (eg (meth)acrylic acid C ₁ alkyl esters, typically methyl methacrylate ( It is preferred that the proportion of MMA)) is limited. (Meth)acrylic acid C _1-3 alkyl ester (for example, (meth)acrylic acid C ₁ alkyl ester, typically MMA) tends to have a relatively high Tg, so an adhesive comprising an acrylic polymer using the above monomer component , the cohesiveness tends to increase. By limiting the amount of (meth)acrylic acid C _1-3 alkyl ester used, the cohesive force of the pressure-sensitive adhesive is appropriately reduced, and the elastic modulus (typically, the surface elastic modulus) suitable for coexistence of flexural holding force and increase in adhesive force can be preferably realized. From such a viewpoint, the proportion of (meth)acrylic acid C _1-3 alkyl ester (for example, (meth)acrylic acid C ₁ alkyl ester, typically MMA) in the monomer raw material A is 8% by weight or less. It is suitable, Preferably it is 6 weight% or less, More preferably, it is 3 weight% or less, Still more preferably, it is 1 weight% or less (for example, 0 to 0.3 weight%).

The monomer raw material A may contain other monomers (copolymerizable monomers) that can be copolymerized with the (meth)acrylic acid alkyl ester as necessary along with the (meth)acrylic acid alkyl ester as the main component. As the copolymerizable monomer, a monomer having a polar group (for example, a carboxyl group, a hydroxyl group, a nitrogen atom-containing ring, etc.) can be suitably used. A monomer having a polar group may be useful for introducing a crosslinking point into the acrylic polymer or increasing the cohesive force of the acrylic polymer. A copolymerizable monomer can be used individually by 1 type or in combination of 2 or more types.

Non-limiting specific examples of the copolymerizable monomer include the following.

Hydroxyl group-containing monomers: For example, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, (meth)acrylate ) 4-hydroxybutyl acrylate, (meth)acrylate 6-hydroxyhexyl, (meth)acrylate 8-hydroxyoctyl, (meth)acrylate 10-hydroxydecyl, (meth)acrylate 12-hydroxylauryl, ( Hydroxyalkyl (meth)acrylates, such as 4-hydroxymethylcyclohexyl)methyl (meth)acrylate, etc.

Monomers having nitrogen atom-containing rings: e.g., N-vinyl-2-pyrrolidone, N-methylvinylpyrrolidone, N-vinylpyridine, N-vinylpiperidone, N-vinylpyrimidine, N-vinyl Piperazine, N-vinylpyrazine, N-vinylpyrrole, N-vinylimidazole, N-vinyloxazole, N-(meth)acryloyl-2-pyrrolidone, N-(meth)acryloylpiperi Dean, N-(meth)acryloylpyrrolidine, N-(meth)acryloylmorpholine, N-vinylmorpholine, N-vinyl-3-morpholinone, N-vinyl-2-caprolactam, N -Vinyl-1,3-oxazin-2-one, N-vinyl-3,5-morpholindione, N-vinylpyrazole, N-vinylisoxazole, N-vinylthiazole, N-vinylisothiazole , N-vinylpyridazine, etc.;

For example, N-(meth)acryloyloxymethylenesuccinimide, N-(meth)acryloyl-6-oxyhexamethylenesuccinimide, N-(meth)acryloyl-8-oxyhexamethylene monomers having a succinimide skeleton such as succinimide;

For example, maleimides, such as N-cyclohexyl maleimide, N-isopropyl maleimide, N-lauryl maleimide, and N-phenyl maleimide; and,

For example, N-methyl itaconimide, N-ethyl itaconimide, N-butyl itaconimide, N-octyl itaconimide, N-2-ethylhexyl itaconimide, N-cyclo Itaconimides, such as hexyl itaconimide and N-lauryl itaconimide;

Carboxy group-containing monomers: For example, acrylic acid, methacrylic acid, carboxyethyl acrylate, carboxypentyl acrylate, itaconic acid, maleic acid, fumaric acid, crotonic acid, isocrotonic acid and the like.

Monomers containing acid anhydride groups: eg maleic anhydride, itaconic anhydride.

Epoxy group-containing monomers: For example, epoxy group-containing acrylates such as glycidyl (meth)acrylate and 2-ethylglycidyl ether (meth)acrylate, allyl glycidyl ether, glycidyl (meth)acrylate, etc. .

Cyano group-containing monomers: eg, acrylonitrile, methacrylonitrile and the like.

Isocyanate group-containing monomers: For example, 2-isocyanatoethyl (meth)acrylate and the like.

Amide group-containing monomers: eg (meth)acrylamide; N,N-dimethyl(meth)acrylamide, N,N-diethyl(meth)acrylamide, N,N-dipropyl(meth)acrylamide, N,N-diisopropyl(meth)acrylamide, N, N,N-dialkyl (meth)acrylamides such as N-di(n-butyl)(meth)acrylamide and N,N-di(t-butyl)(meth)acrylamide; N-alkyl (meth)acrylamides such as N-ethyl (meth)acrylamide, N-isopropyl (meth)acrylamide, N-butyl (meth)acrylamide, and N-n-butyl (meth)acrylamide; N-vinyl carboxylic acid amides such as N-vinylacetamide; A monomer having a hydroxyl group and an amide group, such as N-(2-hydroxyethyl)(meth)acrylamide, N-(2-hydroxypropyl)(meth)acrylamide, N-(1-hydroxypropyl)( Meth)acrylamide, N-(3-hydroxypropyl)(meth)acrylamide, N-(2-hydroxybutyl)(meth)acrylamide, N-(3-hydroxybutyl)(meth)acrylamide, N-hydroxyalkyl (meth)acrylamides such as N-(4-hydroxybutyl)(meth)acrylamide; A monomer having an alkoxy group and an amide group, for example, N-alkoxyalkyl (meth)acrylamide such as N-methoxymethyl (meth)acrylamide, N-methoxyethyl (meth)acrylamide, and N-butoxymethyl (meth)acrylamide ) acrylamide; In addition, N,N-dimethylaminopropyl (meth)acrylamide and the like.

Aminoalkyl (meth)acrylates: For example, aminoethyl (meth)acrylate, N,N-dimethylaminoethyl (meth)acrylate, N,N-diethylaminoethyl (meth)acrylate, t- (meth)acrylate Butylaminoethyl.

Alkoxy group-containing monomers: For example, 2-methoxyethyl (meth)acrylate, 3-methoxypropyl (meth)acrylate, 2-ethoxyethyl (meth)acrylate, propoxyethyl (meth)acrylate, (meth) alkoxyalkyl (meth)acrylates such as butoxyethyl acrylate and ethoxypropyl (meth)acrylate; (meth)acrylate alkoxyalkylene glycols such as methoxyethylene glycol (meth)acrylate and methoxypolypropylene glycol (meth)acrylate.

Monomers containing sulfonic acid groups or phosphoric acid groups: For example, styrenesulfonic acid, allylsulfonic acid, sodium vinylsulfonate, 2-(meth)acrylamide-2-methylpropanesulfonic acid, (meth)acrylamidopropanesulfonic acid, sulfopropyl (meth) ) Acrylates, (meth)acryloyloxynaphthalenesulfonic acid, 2-hydroxyethylacryloylphosphate, etc.

(meth)acrylic acid ester having an alicyclic hydrocarbon group: For example, cyclopentyl (meth)acrylate, cyclohexyl (meth)acrylate, isobornyl (meth)acrylate, dicyclopentanyl (meth)acrylate and the like.

(meth)acrylic acid ester having an aromatic hydrocarbon group: For example, phenyl (meth)acrylate, phenoxyethyl (meth)acrylate, benzyl (meth)acrylate and the like.

Vinyl ethers: For example, vinyl alkyl ethers such as methyl vinyl ether and ethyl vinyl ether.

Vinyl esters: For example, vinyl acetate, vinyl propionate, etc.

Aromatic vinyl compounds: For example, styrene, α-methylstyrene, vinyltoluene and the like.

Olefins: For example, ethylene, butadiene, isoprene, isobutylene, etc.

In addition, heterocyclic-containing (meth)acrylates such as tetrahydrofurfuryl (meth)acrylate, halogen atom-containing (meth)acrylates such as vinyl chloride and fluorine atom-containing (meth)acrylates, and silicone (meth)acrylates silicon atom-containing (meth)acrylates such as the like, (meth)acrylic acid esters obtained from terpene compound derivative alcohols, and the like.

When such a copolymerizable monomer is used, the amount used is not particularly limited, but it is usually appropriate to set it as 0.01% by weight or more of the monomer raw material A. From the viewpoint of better exhibiting the effect of using the copolymerizable monomer, the amount of the copolymerizable monomer may be 0.1% by weight or more, or 1% by weight or more of the monomer raw material A. In some preferred embodiments, the content of the copolymerizable monomer in the monomer raw material A is 3% by weight or more, more preferably 5% by weight or more, still more preferably 7% by weight or more (eg 8% by weight or more). As the amount of the copolymerizable monomer increases, the cohesiveness increases and the bending recovery tends to improve. In addition, the usage amount of the copolymerizable monomer can be 50% by weight or less of the monomer raw material A, and it is preferable to be 30% by weight or less. Thereby, it is possible to prevent the cohesive force of the pressure-sensitive adhesive from being too high, and to improve the tackiness at room temperature (25°C). In some preferred embodiments, the amount of the copolymerizable monomer used is 20% by weight or less of the monomer raw material A, more preferably 15% by weight or less (for example, 12% by weight or less), and may be 10% by weight or less. By limiting the amount of the copolymerizable monomer used, the cohesive force of the pressure-sensitive adhesive is reduced, the elastic modulus (typically, the surface elastic modulus) is within a suitable range, and excellent bending holding power is easily obtained, and an increase in adhesive force is easy to be realized.

In some embodiments, the monomer source A may include a monomer having a nitrogen atom-containing ring. By using a monomer having a nitrogen atom-containing ring, the adhesive force after heating can be suitably improved by adjusting the cohesive force and polarity of the pressure-sensitive adhesive. By including a monomer having a nitrogen atom-containing ring in the monomer raw material A, compatibility between the polymer (A) formed from the monomer raw material A and the polymer (B) tends to be improved. Thereby, it becomes easy to obtain the reinforcing film which can raise adhesive force large by heating.

The monomers having a nitrogen atom-containing ring can be appropriately selected from the above examples and used singly or in combination of two or more. In some embodiments, the monomer raw material A contains, as a monomer having a nitrogen atom-containing ring, at least one monomer selected from the group consisting of N-vinyl cyclic amides and cyclic amides having a (meth)acryloyl group. it is desirable

Specific examples of the N-vinyl cyclic amide include N-vinyl-2-pyrrolidone, N-vinyl-2-piperidone, N-vinyl-3-morpholinone, N-vinyl-2-caprolactam, and N-vinyl -1,3-oxazin-2-one, N-vinyl-3,5-morpholinedione, etc. are mentioned. Particularly preferred are N-vinyl-2-pyrrolidone and N-vinyl-2-caprolactam.

Specific examples of the cyclic amide having a (meth)acryloyl group include N-(meth)acryloyl-2-pyrrolidone, N-(meth)acryloylpiperidine, and N-(meth)acryloylpyrrolidine. , N-(meth)acryloylmorpholine, etc. are mentioned. As a suitable example, N-acryloylmorpholine (ACMO) is mentioned.

The amount of the monomer having a nitrogen atom-containing ring is not particularly limited, and is usually suitably 40% by weight or less, 30% by weight or less, or 20% by weight or less of the monomer raw material A, or 10% by weight or less. It is good also as weight% or less. In some preferred embodiments, from the viewpoint of lowering the cohesive force and lowering the elastic modulus (typically, the surface elastic modulus), the content of the monomer having a nitrogen atom-containing ring in the monomer raw material A is 7% by weight or less, more preferably 5% by weight % or less, more preferably 3% by weight or less (for example, 1.5% by weight or less). The amount of the monomer having a nitrogen atom-containing ring is usually suitably 0.01% by weight or more (preferably 0.1% by weight or more, for example 0.5% by weight or more) of the monomer raw material A. From the viewpoint of obtaining appropriate cohesive force and elastic modulus, in some embodiments, the amount of the monomer having a nitrogen atom-containing ring may be 0.8% by weight or more, or 1.0% by weight or more of the monomer raw material A.

In some preferred embodiments, the monomer raw material A contains a hydroxyl group-containing monomer. By using the hydroxyl group-containing monomer, the cohesive force and polarity of the pressure-sensitive adhesive, as well as the elastic modulus (typically the surface elastic modulus) can be adjusted, and the effect of the technique disclosed herein can be preferably realized. In addition, the hydroxyl group-containing monomer provides a reaction point with a crosslinking agent (for example, an isocyanate-based crosslinking agent) described later, and can increase the cohesive force of the pressure-sensitive adhesive through a crosslinking reaction.

As the hydroxyl group-containing monomer, 2-hydroxyethyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, N-(2-hydroxyethyl) (meth)acrylamide, etc. can be used suitably. Preferred examples thereof include 2-hydroxyethyl acrylate (HEA), 4-hydroxybutyl acrylate (4HBA), and N-(2-hydroxyethyl)acrylamide (HEAA). From the viewpoint of obtaining cohesive force suitable for bending recovery and bending holding power, 4HBA is particularly preferred.

The amount of the hydroxyl group-containing monomer used is not particularly limited, and is usually suitably 40% by weight or less, 30% by weight or less, or 20% by weight or less of the monomer raw material A. In some preferred embodiments, from the viewpoint of reducing the cohesive force and thus the elastic modulus (typically the surface elastic modulus), the content of the hydroxyl group-containing monomer in the monomer raw material A is 15% by weight or less, more preferably 12% by weight or less ( For example, 10% by weight or less). By limiting the amount of the hydroxyl group-containing monomer used, the mobility of the polymer (B) in the pressure-sensitive adhesive layer is improved, and it is easy to realize an increase in adhesive force. In some other aspects, the content of the hydroxyl group-containing monomer may be 5% by weight or less of the monomer raw material A. In addition, it is appropriate that the amount of the hydroxyl group-containing monomer used is 0.01% by weight or more (preferably 0.1% by weight or more, for example 0.5% by weight or more) of the monomer raw material A. From the viewpoint of obtaining appropriate cohesive force and elastic modulus, in some preferred embodiments, the amount of the hydroxyl group-containing monomer used is 1% by weight or more of the monomer raw material A, more preferably 3% by weight or more, still more preferably 5% by weight or more, Especially preferably, it is 7 weight% or more (for example, 8 weight% or more).

In some embodiments, as the copolymerizable monomer, a monomer having a nitrogen atom-containing ring and a hydroxyl group-containing monomer may be used in combination. In this case, the total amount of the monomer having a nitrogen atom-containing ring and the monomer containing a hydroxyl group can be, for example, 0.1% by weight or more of the monomer raw material A, preferably 1% by weight or more, more preferably 3% by weight or more. , More preferably 5% by weight or more, particularly preferably 7% by weight or more (for example, 9% by weight or more), may be 10% by weight or more, may be 15% by weight or more, may be 20% by weight or more It may be good, and it is good also as 25 weight% or more. In addition, the total amount of the monomer having a nitrogen atom-containing ring and the monomer containing a hydroxyl group can be, for example, 50% by weight or less, preferably 30% by weight or less, of the monomer raw material A. In some preferred embodiments, the total amount of the monomer having a nitrogen atom-containing ring and the monomer containing a hydroxyl group is 20% by weight or less, more preferably 15% by weight or less (for example, 12% by weight or less) of the monomer raw material A.

Monomer raw material A is nitrogen In the aspect comprising a combination of a monomer having an atom-containing ring and a hydroxyl group-containing monomer, the content of the monomer having a nitrogen atom-containing ring in the monomer raw material A (W _N ) and the content of the hydroxyl group-containing monomer (W _OH ) The relationship (based on weight) is not particularly limited. W _N /W _OH may be, for example, 0.01 or more, usually 0.05 or more is suitable, 0.10 or more may be sufficient, and 0.12 or more may be sufficient as it. Further, W _N /W _OH may be, for example, 10 or less, and usually 1 or less is appropriate, preferably 0.50 or less, 0.30 or less, 0.20 or less, or 0.15 or less.

In some aspects, the monomer raw material A does not contain a monomer (monomer S1) having a polyorganosiloxane skeleton preferably used as a component of the monomer raw material B described later, or the content of the monomer is 10% of the monomer raw material A It is preferable that it is less than % by weight (more preferably less than 5% by weight, for example less than 2% by weight). According to the monomer raw material A of such a composition, the reinforcing film which satisfies the reworkability of an initial stage and the strong adhesiveness after an adhesive force increase suitably can be implement|achieved suitably. For the same reason, in some other aspects, the monomer raw material A does not contain monomer S1, or when it contains monomer S1, its content (by weight) is lower than the content of monomer S1 in monomer raw material B desirable.

The method for obtaining the polymer (A) is not particularly limited, and various polymerization methods such as solution polymerization method, emulsion polymerization method, bulk polymerization method, suspension polymerization method, and photopolymerization method can be appropriately employed. In some embodiments, solution polymerization may be preferably employed. The polymerization temperature in solution polymerization can be appropriately selected according to the types of monomers and solvents used, the type of polymerization initiator, etc., and is, for example, about 20°C to 170°C (typically about 40°C to 140°C). can do.

The initiator used for polymerization can be appropriately selected from conventionally known thermal polymerization initiators, photopolymerization initiators, and the like, depending on the polymerization method. A polymerization initiator can be used individually by 1 type or in combination of 2 or more types.

As the thermal polymerization initiator, for example, an azo polymerization initiator (eg, 2,2'-azobisisobutyronitrile, 2,2'-azobis-2-methylbutyronitrile, 2,2'-azo Bis(2-methylpropionic acid)dimethyl, 4,4'-azobis-4-cyanovaleric acid, azobisisovaleronitrile, 2,2'-azobis(2-amidinopropane) dihydrochloride, 2 ,2'-azobis[2-(5-methyl-2-imidazolin-2-yl)propane]dihydrochloride, 2,2'-azobis(2-methylpropionamidine) disulfate, 2, 2'-azobis(N,N'-dimethyleneisobutylamidine)dihydrochloride, etc.); persulfates such as potassium persulfate; peroxide polymerization initiators (for example, dibenzoyl peroxide, t-butyl permaleate, lauroyl peroxide, etc.); A redox type polymerization initiator etc. are mentioned. The amount of the thermal polymerization initiator used is not particularly limited, but is, for example, 0.01 to 5 parts by weight, preferably 0.05 parts by weight, based on 100 parts by weight of the monomer component (monomer raw material A) used in the preparation of the polymer (A). It can be set as an amount within the range of parts by weight to 3 parts by weight.

The photopolymerization initiator is not particularly limited, but examples thereof include benzoin ether photopolymerization initiators, acetophenone photopolymerization initiators, α-ketol photopolymerization initiators, aromatic sulfonyl chloride photopolymerization initiators, photoactive oxime photopolymerization initiators, and benzoin photopolymerization initiators. A photopolymerization initiator, a benzyl-based photopolymerization initiator, a benzophenone-based photopolymerization initiator, a ketal-based photopolymerization initiator, a thioxanthone-based photopolymerization initiator, an acylphosphine oxide-based photopolymerization initiator, and the like can be used. The amount of the photopolymerization initiator used is not particularly limited, but may be, for example, 0.01 part by weight to 5 parts by weight, preferably 0.05 part by weight to 3 parts by weight, based on 100 parts by weight of the monomer raw material A.

In some embodiments, the polymer (A) is in the form of a partially polymerized product (polymer syrup) obtained by polymerizing a part of the monomer component by irradiating ultraviolet (UV) light to a mixture in which a polymerization initiator is blended with the monomer raw material A as described above. , It may be included in the pressure-sensitive adhesive composition for forming the pressure-sensitive adhesive layer. Polymerization may be completed by applying the pressure-sensitive adhesive composition including the polymer syrup to a predetermined coating material and irradiating ultraviolet rays. That is, the polymer syrup can be regarded as a precursor of polymer (A). The pressure-sensitive adhesive layer disclosed herein may be formed using, for example, a pressure-sensitive adhesive composition containing the polymer syrup and polymer (B).

(Polymer (B))

The polymer (B) in the technique disclosed herein is a polymer of a monomer having a polyorganosiloxane skeleton (hereinafter also referred to as "monomer S1") and a monomer component (monomer raw material B) containing a (meth)acrylic monomer. am. Polymer (B) can be said to be a copolymer of monomer S1 and a (meth)acrylic monomer. Polymer (B) can be used individually by 1 type or in combination of 2 or more types. Polymer (B) suppresses the initial adhesive force to the adherend due to the low polarity and mobility of the polyorganosiloxane structure derived from the monomer S1, and also increases the adhesive force to the adherend by heating. It can function as a rise retardant. It does not specifically limit as monomer S1, Any monomer containing a polyorganosiloxane skeleton can be used. Monomer S1 promotes uneven distribution of the polymer (B) on the surface of the pressure-sensitive adhesive layer in the reinforcing film before use (before sticking to an adherend) by virtue of the low polarity derived from its structure, and easy peelability at the initial stage of bonding (Low adhesiveness) is expressed. As monomer S1, one of a structure having a polymerizable reactive group at one end can be preferably used. According to the configuration including the monomer S1 unit and the (meth)acrylic monomer unit, a polymer (B) having a polyorganosiloxane skeleton in the side chain is formed. The polymer (B) having such a structure tends to have a low initial adhesive force and a high adhesive force after heating due to the mobility and ease of movement of the side chain. In some embodiments, as the monomer S1, one having a polymerizable reactive group at one end and not having a functional group that causes a crosslinking reaction with the polymer (A) at the other end can be preferably employed. The polymer (B) obtained by copolymerization of monomer S1 having such a structure tends to have low initial adhesive force and high adhesive force after heating due to the mobility of the polyorganosiloxane structure derived from monomer S1.

As monomer S1, a compound represented by the following general formula (1) or (2) can be used, for example. More specifically, X-22-174ASX, X-22-2426, X-22-2475, KF-2012 etc. are mentioned as one-end reactive silicone oil made by Shin-Etsu Chemical Co., Ltd. Monomer S1 can be used individually by 1 type or in combination of 2 or more types.

Here, in the general formulas (1) and (2), R ³ is hydrogen or methyl, R ⁴ is a methyl group or a monovalent organic group, and m and n are integers greater than or equal to 0.

The functional group equivalent of monomer S1 can employ an appropriate value within a range in which a desired effect is exhibited using the monomer S1, and is not limited to a specific range. From the viewpoint of sufficiently suppressing the initial adhesive force, the functional group equivalent is, for example, 100 g/mol or more or 200 g/mol or more, suitably 300 g/mol or more (eg 500 g/mol or more), and 800 g/mol or more It is preferable, and it is more preferable that it is 1500 g/mol or more. In a particularly preferred embodiment, from the viewpoint of coexistence of low adhesiveness in the initial stage of application and adhesive strength increase after heating, the functional group equivalent is 2000 g / mol or more, and particularly preferably 2500 g / mol or more, even if it is 3000 g / mol or more It may be 4000 g/mol or more, or 5000 g/mol or more. In some other embodiments, the functional group equivalent may be 9000 g/mol or more, 12000 g/mol or more, or 15000 g/mol or more. In the functional group equivalent of monomer S1, the functional group means a polymerizable functional group (for example, an ethylenically unsaturated group such as a (meth)acryloyl group, a vinyl group, or an allyl group).

From the standpoint of sufficiently increasing the adhesive force, the functional group equivalent is suitably, for example, 30000 g/mol or less, may be 20000 g/mol or less, may be less than 15000 g/mol, or may be less than 10000 g/mol. In some preferred embodiments, the functional group equivalent of monomer S1 is 7000 g/mol or less, more preferably 5500 g/mol or less, even more preferably 4500 g/mol or less, 4200 g/mol or less, or even 3500 g/mol or less. do. When the functional group equivalent of the monomer S1 is within the above range, the compatibility in the pressure-sensitive adhesive layer (for example, compatibility with the base polymer) tends to be good, and the polyorganosiloxane backbone (chain) of the polymer (B) The mobility of the polymer (B) is good, and the mobility of the polymer (B) is easily controlled within an appropriate range, making it easy to realize an adhesive layer that achieves both initial low adhesiveness and increased adhesive force after heating.

Here, "functional group equivalent" means the weight of the main skeleton (for example, polydimethylsiloxane) bonded per functional group. Regarding the notational unit g/mol, it is converted to 1 mol of the functional group. The functional group equivalent of monomer S1 can be calculated, for example, from the spectral intensity of ¹ H-NMR (proton NMR) based on nuclear magnetic resonance (NMR). Calculation of the functional group equivalent (g/mol) of monomer S1 based on the spectrum intensity of ^{1 H-NMR is based on a general structural analysis method that affects 1 H} -NMR spectrum analysis, and, if necessary, Japanese Patent No. 5951153 This can be done by referring to the description of

In addition, when using two or more types of monomers from which functional group equivalents differ as monomer S1, an arithmetic average value can be used as a functional group equivalent of monomer S1. That is, the functional group equivalent of monomer S1 containing n types of monomers (monomer S1 ₁ , monomer S1 ₂ ... monomer S1 _n ) with different functional group equivalents can be calculated by the following formula.

Functional group equivalent of monomer S1 (g/mol) = (functional group equivalent of monomer S1 ₁ × compounding amount of monomer S1 ₁ + functional group equivalent of monomer S1 ₂ × compounding amount of monomer S1 ₂ + … + functional group equivalent of monomer S1 _n × monomer S1 _n compounding amount)/(blending amount of monomer S1 ₁ + compounding amount of monomer S1 ₂ + ... + compounding amount of monomer S1 _n )

The content of the monomer S1 can be an appropriate value within a range in which desired effects are exhibited using the monomer S1, and is not limited to a specific range. From the viewpoint of sufficiently suppressing the initial adhesive force, in some embodiments, the content of the monomer S1 in the total amount of the monomer component (monomer raw material B) for preparing the polymer (B) may be, for example, 5% by weight or more, and the adhesive force From the viewpoint of exhibiting the effect as a rise retardant better, it is preferably 10% by weight or more, more preferably 12% by weight or more, still more preferably 15% by weight or more, particularly preferably 18% by weight or more, It is good also as 20 weight% or more. Further, the content of the monomer S1 in the monomer raw material B may be, for example, 80% by weight or less, suitably 60% by weight or less, preferably 50% by weight or less, from the viewpoint of polymerization reactivity or compatibility, It is more preferably 40% by weight or less, and even more preferably 30% by weight or less. By setting the polymerization ratio of monomer S1 within a suitable range, an increase in adhesive force can be suitably expressed.

The monomer raw material B contains, in addition to monomer S1, a (meth)acrylic monomer copolymerizable with monomer S1. By using one or two or more (meth)acrylic monomers, the mobility of the polymer (B) in the pressure-sensitive adhesive layer can be suitably adjusted. In addition, it may be helpful to improve the compatibility of polymer (B) and polymer (A). Since the polymer (B) containing the (meth)acrylic monomer unit is compatible with the acrylic polymer, the initial adhesive strength is reduced and the adhesive strength after heating is improved by improving the mobility of the polymer (B) in the pressure-sensitive adhesive layer. is easy to realize.

In the polymer (B) used in the technology disclosed herein, the composition of the (meth)acrylic monomer contained in the monomer raw material B is such that the glass transition temperature T _B of the polymer (B) is -20°C to 5°C. can be set appropriately in The glass transition temperature T _B1 based on the composition of the (meth)acrylic monomer is also appropriately set within a range satisfying the above T _B , and is not limited to a specific range. Typically, T _B1 is preferably set higher than the glass transition temperature T _A of the polymer (A). T _B1 can be set to be higher than 0°C, for example. Here, the glass transition temperature T _B1 based on the composition of the (meth)acrylic monomer is determined by Fox's formula based on the composition of only the (meth)acrylic monomer among the monomer components used in the preparation of the polymer (B). say Tg. T _B1 is the homopolymer glass transition temperature of each (meth)acrylic monomer and the corresponding It can be calculated from the weight fraction of each (meth)acrylic monomer in the total amount of the (meth)acrylic monomer. According to the polymer (B) having a relatively high glass transition temperature T _B1 (typically higher than 0°C), the initial adhesive strength tends to be suppressed. Further, according to the polymer (B) having a relatively high glass transition temperature T _B1 (typically higher than 0°C), a reinforcing film with a large adhesive strength increase ratio is easily obtained.

In some preferred embodiments, T _B1 is 10°C or higher, more preferably 30°C or higher, still more preferably 40°C or higher, and may be 45°C or higher. When T _B1 is high, the adhesive force at the initial stage of sticking tends to be better suppressed in general. This is because, according to the polymer (B) having T _B1 equal to or higher than a predetermined temperature, the improvement in the mobility and mobility of the polyorganosiloxane structural part accompanying the temperature rise to room temperature or a temperature range to a certain degree higher than room temperature is achieved in the polymer (B). It is thought that this is because it is effectively suppressed by the contained monomer unit derived from the (meth)acrylic monomer, and the low tackiness due to the presence of the polyorganosiloxane structure portion can be better maintained. From the viewpoint of maintaining the low tackiness at the initial stage of sticking more stably, in some embodiments, T _B1 may be, for example, 50°C or higher, 55°C or higher, or 60°C or higher. Further, T _B1 may be, for example, 120°C or less, or 100°C or less. When T _B1 is lowered, the increase in adhesive force by heating tends to be facilitated. In some preferred embodiments, T _B1 is, for example, 90 °C or less, more preferably 70 °C or less, even more preferably 60 °C or less, particularly preferably 55 °C or less (eg 50 °C or less) .

From the viewpoint of making it easy to exhibit the effect by appropriately setting T _B1 , the total amount of monomer S1 and (meth)acrylic monomers in all monomer components for preparing polymer (B) is, for example, 50% by weight or more It may be 70% by weight or more, may be 85% by weight or more, may be 90% by weight or more, may be 95% by weight or more, or may be substantially 100% by weight.

The glass transition temperature T _B of the polymer (B) used in the technique disclosed herein is within the range of -20°C to 5°C. When T _B of the polymer (B) is 5° C. or lower, the mobility (typically, thermal sensitivity) of the polymer (B) is improved, and the adhesive force can be greatly increased. In some preferred embodiments, the T _B of the polymer (B) may be less than 0°C, -5°C or less, or -10°C or less. In addition, when T _B is -20°C or higher, the polymer (B) unevenly distributed on the surface side of the pressure-sensitive adhesive layer at the time of sticking to the adherend contributes to a decrease in initial adhesive force, and there is a tendency for easy peelability at the initial stage of sticking. In some preferred embodiments, T _B of the polymer (B) may be -15°C or higher. By setting T _B to an appropriate range, the easy peelability at the initial stage of sticking and the increase in adhesive force after heating can be controlled within a preferable range.

In some embodiments, the composition of the monomer components for preparing polymer (B) can be set such that T _B1 is higher than T _B , that is, T _B1 -T _B is greater than 0°C. According to such a composition, the effect of adjusting the mobility of the polymer (B) can be suitably exhibited by the composition of the (meth)acrylic monomer included in the monomer component. T _B1 -T _B may be, for example, about 40°C to 100°C, or about 50°C to 90°C. In some preferred embodiments, T _B1 -T _B is 45°C or higher, more preferably 50°C or higher, still more preferably 55°C or higher (eg 58°C or higher). Further, from the viewpoint of appropriately expressing the effect of containing the polymer (B), T _B1 -T _B is preferably 80°C or lower, more preferably 70°C or lower, still more preferably 65°C or lower (for example 62 ° C or less).

From the viewpoint of making it easy to control the mobility of the polymer (B) in the pressure-sensitive adhesive layer, in some embodiments, the composition of the monomer component for preparing the polymer (B) is related to the glass transition temperature T _A of the polymer (A) In , T _B can be set to be higher than T _A by 20°C or more, that is, T _B -T _A can be set to be 20°C or more. In some preferred embodiments, T _B -T _A is, for example, 30°C or higher, more preferably 40°C or higher, even more preferably 50°C or higher, may be 60°C or higher, or may be 70°C or higher. Further, from the viewpoint of increasing the adhesive force, T _B -T _A may be, for example, 130°C or less, or 120°C or less, preferably 100°C or less, more preferably 80°C or less, still more preferably 65°C or less. °C or lower, may be 55 °C or lower, or may be 45 °C or lower.

Examples of the (meth)acrylic monomer that can be used for the monomer raw material B include (meth)acrylic acid alkyl esters. "Alkyl" here refers to a chain (including straight-chain and branched-chain) alkyl (group), and does not contain an alicyclic hydrocarbon group described later. For example, as the (meth)acrylic acid alkyl ester that can be used for the polymer (A), one or two or more of the monomers exemplified above can be used as the constituent of the monomer raw material B. In some preferred embodiments, the monomer raw material B is (meth)acrylic acid C _4-12 alkyl ester (preferably (meth)acrylic acid C _4-10 alkyl ester, for example (meth)acrylic acid C _6-10 alkyl ester ) may contain at least one of them. In some other aspects, the monomer raw material B is at least one of methacrylic acid C _1-18 alkyl esters (preferably methacrylic acid C _1-14 alkyl esters, for example, methacrylic acid C _1-10 alkyl esters). may contain species. The monomer raw material B may include, for example, one or two or more selected from MMA, n-butyl methacrylate (nBMA), and 2-ethylhexyl methacrylate (2EHMA) as a (meth)acrylic monomer. there is.

Other examples of the above (meth)acrylic monomers include (meth)acrylic acid esters having an alicyclic hydrocarbon group. For example, cyclopentyl (meth) acrylate, cyclohexyl (meth) acrylate, isobornyl (meth) acrylate, dicyclopentanyl (meth) acrylate, 1-adamantyl (meth) acrylate, etc. can be used In some embodiments, the monomer raw material B may contain at least one selected from dicyclopentanyl methacrylate, isobornyl methacrylate and cyclohexyl methacrylate as a (meth)acrylic monomer.

The content of the alkyl (meth)acrylic acid ester and the (meth)acrylic acid ester having an alicyclic hydrocarbon group in the monomer raw material B may be, for example, 10% by weight or more and 95% by weight or less, and 20% by weight or more and 95% by weight. It may be below, 30 weight% or more and 90 weight% or less may be sufficient, 40 weight% or more and 90 weight% or less may be sufficient, and 50 weight% or more and 85 weight% or less may be sufficient. From the viewpoint of the ease of increasing the adhesive force by heating, the use of a (meth)acrylic acid alkyl ester may be advantageous. In some embodiments, the content of (meth)acrylic acid ester having an alicyclic hydrocarbon group may be less than 50% by weight, less than 30% by weight, less than 15% by weight, or less than 10% by weight of the monomer raw material B. , may be less than 5% by weight. It is not necessary to use a (meth)acrylic acid ester having an alicyclic hydrocarbon group.

In some preferred embodiments, the (meth)acrylic monomer, which is a component of the monomer raw material B, may include a monomer M2 having a homopolymer Tg of 50°C or higher. In the polymer (B), by copolymerizing the monomer S1 and the monomer M2, the mobility and mobility of the polyorganosiloxane structural portion accompanying the temperature rise are appropriately controlled, and the initial easy peelability (reworkability) and the increase in adhesive force after heating It is easy to realize the compatibility of In some embodiments, the homopolymer Tg of the monomer M2 may be 60°C or higher, 70°C or higher, 80°C or higher, or 90°C or higher. The upper limit of the Tg of the homopolymer of the monomer M2 is not particularly limited, but is usually preferably 200°C or less from the viewpoint of the ease of synthesis of the polymer (B). In some embodiments, the homopolymer Tg of monomer M2 may be, for example, 180°C or less, 150°C or less, or 120°C or less.

As the monomer M2, among the (meth)acrylic monomers exemplified above, those whose homopolymer Tg satisfies the conditions can be used. For example, one or two or more monomers selected from the group consisting of (meth)acrylic acid alkyl esters and (meth)acrylic acid esters having an alicyclic hydrocarbon group can be used. As the (meth)acrylic acid alkyl ester, a methacrylic acid alkyl ester in which the number of carbon atoms in the alkyl group is in the range of 1 to 4 is preferably employable.

In the aspect in which the monomer raw material B contains the monomer M2, the content of the monomer M2 may be, for example, 5% by weight or more, 10% by weight or more, 15% by weight or more, or 20% by weight of the monomer raw material B. It may be greater than or equal to 25% by weight or greater than or equal to 30% by weight. In some embodiments, the content of the monomer M2 may be 35% by weight or more, 40% by weight or more, 45% by weight or more, 50% by weight or more, or 55% by weight or more of the monomer raw material B. . The content of the monomer M2 may be, for example, 90% by weight or less, usually suitably 80% by weight or less, preferably 75% by weight or less, 70% by weight or less, or 65% by weight or less. . In some preferred embodiments, the content of monomer M2 is 60% by weight or less (eg 50% by weight or less, typically 42% by weight or less). In the polymer (B), the copolymerization ratio of the monomer M2 of Tg50 ° C. or higher is limited to a predetermined value or less, so that the adhesive force increase after heating can be preferably realized based on the mobility of the polymer (B) around 50 ° C. . From the same point of view, the content of the monomer M2 in the monomer raw material B may be 35% by weight or less, 25% by weight or less, or 15% by weight or less (for example, 5% by weight or less).

The content of the monomer M2 is, for example, an aspect in which the monomer M2 includes one or two or more monomers selected from the group consisting of (meth)acrylic acid alkyl esters and (meth)acrylic acid esters having the alicyclic hydrocarbon group, In an embodiment in which the monomer M2 includes one or two or more monomers selected from (meth)acrylic acid alkyl esters (eg, methacrylic acid alkyl esters), it can be preferably applied. As one suitable example of this embodiment, an embodiment in which the monomer M2 includes MMA may be mentioned.

In some embodiments, the (meth)acrylic monomer may contain monomer M3 having a homopolymer Tg of less than 50°C (typically -20°C or more and less than 50°C). By use of monomer M3, it becomes easy to obtain the film for reinforcement which makes adhesive force and cohesive force compatible with a well-balanced after adhesive force increase. It is preferable to use monomer M3 in combination with monomer M2 from the viewpoint of making it easy to exert such an effect.

As the monomer M3, among the (meth)acrylic monomers exemplified above, those whose homopolymer Tg satisfies the conditions can be used. For example, one or two or more monomers selected from the group consisting of (meth)acrylic acid alkyl esters can be used.

In the aspect in which the monomer raw material B contains the monomer M3, the content of the monomer M3 may be, for example, 5% by weight or more, 10% by weight or more, 15% by weight or more, or 20% by weight of the monomer raw material B. It may be greater than or equal to 25% by weight, greater than or equal to 30% by weight, or greater than or equal to 35% by weight. In addition, the content of the monomer M3 is usually suitably 70% by weight or less, 60% by weight or less, or 50% by weight or less of the monomer raw material B. The content of the monomer M3 may be suitably applied in an embodiment in which the monomer M3 is composed of one or two or more monomers selected from (meth)acrylic acid alkyl esters (eg, methacrylic acid alkyl esters), for example. .

In some aspects of the reinforcing film disclosed herein, it is preferable that the content of a monomer having a homopolymer Tg higher than 170°C in the monomer raw material B is 30% by weight or less. Here, in the present specification, the content of a monomer is X weight% or less is a concept including an aspect in which the content of the monomer is 0 wt%, that is, an aspect that does not substantially contain the monomer, unless otherwise specified. In addition, not containing substantially means that the said monomer is not used at least intentionally. If the copolymerization ratio of the monomer having a homopolymer Tg higher than 170°C increases, the mobility of the polymer (B) tends to be insufficient, and it may be difficult to increase the adhesive force by heating to a temperature range higher than 50°C. there is.

In some embodiments, the monomer raw material B preferably contains at least MMA as a (meth)acrylic monomer. According to the polymer (B) in which MMA was copolymerized, it is easy to obtain a reinforcing film having high adhesive strength after heating. The ratio of MMA to the total amount of (meth)acrylic monomers contained in the monomer raw material B may be, for example, 5% by weight or more, 10% by weight or more, 20% by weight or more, or 30% by weight or more. , 40% by weight or more may be sufficient. In addition, the ratio of MMA to the total amount of monomer raw material B is usually 95% by weight or less, and in some preferred embodiments, the ratio of MMA to the total amount of monomer raw material B is 75% from the viewpoint of increasing the adhesive strength after heating. It may be 65% by weight or less, 60% by weight or less, or 55% by weight or less (for example, 50% by weight or less).

As other examples of the monomers that can be included together with the monomer S1 as the monomer unit constituting the polymer (B), the carboxyl group-containing monomers, acid anhydride group-containing monomers, and hydroxyl group-containing monomers exemplified above as monomers that can be used for the polymer (A) , an epoxy group-containing monomer, a cyano group-containing monomer, an isocyanate group-containing monomer, an amide group-containing monomer, a monomer having a nitrogen atom-containing ring (N-vinyl cyclic amide, a cyclic amide having a (meth)acryloyl group, and a succinimide skeleton) monomers, maleimides, itaconimides, etc.), (meth)acrylic acid aminoalkyls, vinyl esters, vinyl ethers, olefins, (meth)acrylic acid esters having an aromatic hydrocarbon group, and heterocycle-containing (meth)acrylic acid and (meth)acrylic acid esters obtained from alcohols derived from terpene compound derivatives.

As another example of a monomer that can be included together with the monomer S1 as a monomer unit constituting the polymer (B), ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth) Oxyalkylene di(meth)acrylates such as acrylate, polyethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, dipropylene glycol di(meth)acrylate, and tripropylene glycol di(meth)acrylate ; A monomer having a polyoxyalkylene skeleton, for example, having a polymerizable functional group such as a (meth)acryloyl group, a vinyl group, or an allyl group at one end of a polyoxyalkylene chain such as polyethylene glycol or polypropylene glycol, and the other end Polymerizable polyoxyalkylene ether which has an ether structure (alkyl ether, aryl ether, arylalkyl ether, etc.) at the terminal; alkoxyalkyl (meth)acrylates such as methoxyethyl (meth)acrylate, ethoxyethyl (meth)acrylate, propoxyethyl (meth)acrylate, butoxyethyl (meth)acrylate, and ethoxypropyl (meth)acrylate; salts such as alkali metal (meth)acrylate; polyhydric (meth)acrylates such as trimethylolpropane tri(meth)acrylic acid ester; halogenated vinyl compounds such as vinylidene chloride and 2-chloroethyl (meth)acrylate; oxazoline group-containing monomers such as 2-vinyl-2-oxazoline, 2-vinyl-5-methyl-2-oxazoline, and 2-isopropenyl-2-oxazoline; aziridine group-containing monomers such as (meth)acryloyl aziridine and (meth)acryloyl-2-aziridinylethyl; hydroxyl group-containing vinyl monomers such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, and adducts of lactones and 2-hydroxyethyl (meth)acrylate; fluorine-containing vinyl monomers such as fluorine-substituted (meth)acrylic acid alkyl esters; reactive halogen-containing vinyl monomers such as 2-chloroethyl vinyl ether and monochlorovinyl acetate; Organosilicon-containing vinyl monomers such as vinyltrimethoxysilane, γ-(meth)acryloxypropyltrimethoxysilane, allyltrimethoxysilane, trimethoxysilylpropylallylamine, 2-methoxyethoxytrimethoxysilane ; In addition, macromonomers having a radically polymerizable vinyl group at the end of a monomer obtained by polymerizing a vinyl group; etc. can be mentioned. These can be copolymerized with monomer S1 individually by 1 type or in combination of 2 or more types.

In some embodiments, as the polymer (B), one having no functional group that causes a crosslinking reaction with the polymer (A) can be preferably employed. In other words, the polymer (B) is preferably contained in the pressure-sensitive adhesive layer in a form that is not chemically bonded to the polymer (A). The pressure-sensitive adhesive layer containing the polymer (B) in such a form has good mobility of the polymer (B) during heating, and is suitable for improving the adhesive force increasing ratio. The functional group causing the crosslinking reaction with the polymer (A) may vary depending on the type of functional group possessed by the polymer (A), but may be, for example, an epoxy group, an isocyanate group, a carboxy group, an alkoxysilyl group, an amino group, or the like.

Mw of the polymer (B) is not particularly limited. Mw of the polymer (B) may be, for example, 1000 or more, or 5000 or more. In some preferred embodiments, the Mw of the polymer (B) is 10,000 or more, more preferably 12,000 or more, may be 15,000 or more, may be 20,000 or more, may be 22,000 or more, from the viewpoint of suitably exhibiting an increase in adhesive strength after heating. It may be 25,000 or more. In some other aspects, the Mw of the polymer (B) may be 30,000 or more, 50,000 or more, or 70,000 or more. The upper limit of Mw of the polymer (B) is, for example, 500,000 or less, 350,000 or less, 200,000 or less, or 150,000 or less. From the viewpoint of adjusting the compatibility and mobility in the pressure-sensitive adhesive layer to an appropriate range and suitably expressing the low-adhesion property in the initial stage of sticking, in some preferred embodiments, the Mw of the polymer (B) is 100,000 or less, and more It is preferably 80,000 or less, more preferably 60,000 or less, particularly preferably 40,000 or less (for example, 30,000 or less), 25,000 or less, or even 20,000 or less. By setting the Mw of the polymer (B) in an appropriate range, it is easy to obtain a pressure-sensitive adhesive excellent in coexistence of easy peelability in the initial stage of sticking and adhesive force increasing property.

In some preferred embodiments, the Mw of polymer (B) is preferably lower than the Mw of polymer (A). Thereby, it becomes easy to implement|achieve the film for reinforcement which makes favorable reworkability in the initial stage of sticking and the adhesive force raise after heating compatible. In some embodiments, the Mw of polymer (B) may be, for example, 0.8 times or less, 0.75 times or less, 0.5 times or less, or 0.3 times or less of the Mw of polymer (A). In some preferred embodiments, the ratio of Mw _B of polymer (B) to Mw _A of polymer (A) (Mw _B /Mw _A ) is 0.3 or less, more preferably 0.2 or less, still more preferably 0.1 or less; Especially preferably, it is 0.06 or less (for example, 0.05 or less). The ratio (Mw _B /Mw _A ) is, for example, preferably 0.010 or more, preferably 0.020 or more, more preferably 0.03 or more, still more preferably 0.04 or more. By setting the Mw of polymer (A) and the Mw of polymer (B) in appropriate ranges, the effect of the technique disclosed herein can be better realized. In some other embodiments, the Mw of the polymer (B) may be 0.03 times or less (for example, 0.02 times or less) of the Mw of the polymer (A).

The polymer (B) can be produced, for example, by polymerizing the above-mentioned monomers by a known method such as solution polymerization, emulsion polymerization, bulk polymerization, suspension polymerization, or photopolymerization.

In order to adjust the molecular weight of polymer (B), a chain transfer agent can be used as needed. Examples of the chain transfer agent to be used include compounds having a mercapto group such as octyl mercaptan, lauryl mercaptan, t-nonyl mercaptan, t-dodecyl mercaptan, mercaptoethanol, and α-thioglycerol; Thioglycolic acid, methyl thioglycolate, ethyl thioglycolate, propyl thioglycolate, butyl thioglycolate, t-butyl thioglycolate, 2-ethylhexyl thioglycolate, octyl thioglycolate, isooctyl thioglycolate, thioglycolic acid esters such as decyl thioglycolate, dodecyl thioglycolate, thioglycolic acid ester of ethylene glycol, thioglycolic acid ester of neopentyl glycol, and thioglycolic acid ester of pentaerythritol; α-methylstyrene dimer; etc. can be mentioned.

The amount of the chain transfer agent used is not particularly limited, but is usually 0.05 part by weight to 20 parts by weight, preferably 0.1 part by weight to 15 parts by weight, more preferably 0.2 part by weight to 100 parts by weight of the monomer. Contains 10 parts by weight. By adjusting the addition amount of the chain transfer agent in this way, a polymer (B) having a suitable molecular weight can be obtained. A chain transfer agent can be used individually by 1 type or in combination of 2 or more types.

As a means for adjusting the molecular weight of the polymer (B), conventionally known various means including the use of the chain transfer agent can be used alone or in appropriate combination. The same applies to the molecular weight of the polymer (A). Non-limiting examples of such means include selection of polymerization method, selection of type or amount of polymerization initiator, selection of polymerization temperature, selection of type or amount of polymerization solvent in solution polymerization method, selection of amount in photopolymerization method selection of light irradiation intensity; and the like. A person skilled in the art can understand how to obtain a polymer having a desired molecular weight based on the description of the present specification including specific examples to be described later and the common technical knowledge at the time of filing the present application.

In the reinforcing film disclosed herein, the amount of polymer (B) used per 100 parts by weight of polymer (A) can be, for example, 0.1 part by weight or more, resulting in a higher effect (preferably, adhesion 0.5 parts by weight or more is preferable, 1 part by weight or more is more preferable, 1.5 parts by weight or more is still more preferable, and it is good also as 2 parts by weight or more from the viewpoint of obtaining initial light peelability). In some embodiments, from the viewpoint of improving reworkability, etc., the amount of the polymer (B) used can be, for example, 3 parts by weight or more, 4 parts by weight or more, or 5 parts by weight or more. . The amount of polymer (B) used per 100 parts by weight of polymer (A) may be, for example, 75 parts by weight or less, 30 parts by weight or less, 10 parts by weight or less, or 8 parts by weight or less. do. From the viewpoint of suitably realizing the desired increase in adhesive strength, in some preferred embodiments, the amount of the polymer (B) relative to 100 parts by weight of the polymer (A) is 5 parts by weight or less, more preferably 4 parts by weight or less. , More preferably 3 parts by weight or less, particularly preferably 2.5 parts by weight or less. In some other preferred embodiments, the amount of polymer (B) used per 100 parts by weight of polymer (A) is 1.5 parts by weight or less (for example, 1.2 parts by weight or less). By setting the usage amount of the polymer (B) within the above range, it is easy to realize good bending recovery and bending holding power. Moreover, the easy peeling property of the initial stage of sticking and the adhesive force increasing property can be made compatible more well.

The pressure-sensitive adhesive layer may contain polymers (arbitrary polymers) other than the polymer (A) and the polymer (B) as needed within a range that does not significantly impair the performance of the reinforcing film disclosed herein. The amount of such an arbitrary polymer used is usually suitably 20% by weight or less, 15% by weight or less, or 10% by weight or less of the total polymer components included in the pressure-sensitive adhesive layer. In some embodiments, the amount of the optional polymer used may be 5% by weight or less, 3% by weight or less, or 1% by weight or less of the total amount of the polymer component. It may be a pressure-sensitive adhesive layer that does not substantially contain polymers other than the polymer (A) and the polymer (B).

(crosslinking agent)

A crosslinking agent may be used in the pressure-sensitive adhesive layer as needed for the purpose of adjusting the cohesive force or the like. As the crosslinking agent, a crosslinking agent known in the field of pressure-sensitive adhesives can be used, and examples thereof include an epoxy crosslinking agent, an isocyanate crosslinking agent, a silicone crosslinking agent, an oxazoline crosslinking agent, an aziridine crosslinking agent, a silane crosslinking agent, an alkyl etherified melamine crosslinking agent, A metal chelate type crosslinking agent etc. are mentioned. An isocyanate-type crosslinking agent, an epoxy-type crosslinking agent, and a metal chelate-type crosslinking agent can be suitably used. As a crosslinking agent that satisfies both bending recovery and bending holding power, an isocyanate-based crosslinking agent can be preferably used. A crosslinking agent can be used individually by 1 type or in combination of 2 or more types.

As the isocyanate-based crosslinking agent, polyfunctional isocyanates (referring to compounds having an average of two or more isocyanate groups per molecule, including those having an isocyanurate structure) can be preferably used. An isocyanate type crosslinking agent can be used individually by 1 type or in combination of 2 or more types.

Examples of polyfunctional isocyanates include aliphatic polyisocyanates, alicyclic polyisocyanates, and aromatic polyisocyanates.

Specific examples of aliphatic polyisocyanates include 1,2-ethylene diisocyanate; tetramethylene diisocyanates such as 1,2-tetramethylene diisocyanate, 1,3-tetramethylene diisocyanate, and 1,4-tetramethylene diisocyanate; 1,2-hexamethylene diisocyanate, 1,3-hexamethylene diisocyanate, 1,4-hexamethylene diisocyanate, 1,5-hexamethylene diisocyanate, 1,6-hexamethylene diisocyanate, 2,5-hexa hexamethylene diisocyanates such as methylene diisocyanate; 2-methyl-1,5-pentane diisocyanate, 3-methyl-1,5-pentane diisocyanate, and lysine diisocyanate.

Specific examples of alicyclic polyisocyanates include isophorone diisocyanate; cyclohexyl diisocyanates such as 1,2-cyclohexyl diisocyanate, 1,3-cyclohexyl diisocyanate, and 1,4-cyclohexyl diisocyanate; cyclopentyl diisocyanates such as 1,2-cyclopentyl diisocyanate and 1,3-cyclopentyl diisocyanate; Hydrogenated xylylene diisocyanate, hydrogenated tolylene diisocyanate, hydrogenated diphenylmethane diisocyanate, hydrogenated tetramethylxylene diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, etc. are mentioned.

As specific examples of aromatic polyisocyanates, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 4,4'-diphenylmethane diisocyanate, 2,4'-diphenylmethane diisocyanate, 2,2' -Diphenylmethane diisocyanate, 4,4'-diphenyl ether diisocyanate, 2-nitrodiphenyl-4,4'-diisocyanate, 2,2'-diphenylpropane-4,4'-diisocyanate, 3 ,3'-dimethyldiphenylmethane-4,4'-diisocyanate, 4,4'-diphenylpropane diisocyanate, m-phenylene diisocyanate, p-phenylene diisocyanate, naphthylene-1,4-diisocyanate, Naphthylene-1,5-diisocyanate, 3,3'-dimethoxydiphenyl-4,4'-diisocyanate, xylylene-1,4-diisocyanate, xylylene-1,3-diisocyanate, etc. can be heard

As a preferable polyfunctional isocyanate, the polyfunctional isocyanate which has 3 or more isocyanate groups on average per molecule is illustrated. Such trifunctional or higher than trifunctional isocyanate is a multimer (for example, a dimer or trimer), a derivative (for example, an addition reaction product of a polyhydric alcohol and two or more molecules of polyfunctional isocyanate), polymers and the like. For example, a dimer or trimer of diphenylmethane diisocyanate, an isocyanurate compound of hexamethylene diisocyanate (a trimer adduct of an isocyanurate structure), a reaction product of trimethylolpropane and tolylene diisocyanate, Reaction product of trimethylolpropane and hexamethylene diisocyanate, trimethylolpropane adduct of xylylene diisocyanate, trimethylolpropane adduct of isophorone diisocyanate, trimethylolpropane adduct of hexamethylene diisocyanate, polymethylene polyphenylisocyanate , polyether polyisocyanates, polyester polyisocyanates, and polyfunctional isocyanates such as polyisocyanates polyisocyanates polyfunctionalized with adducts of these and various polyols, isocyanurate bonds, biuret bonds, allophanate bonds, and the like.

Commercially available products of the polyfunctional isocyanate include "Duranate TPA-100", a trade name manufactured by Asahi Kasei Chemicals, "Coronate L", "Coronate HL", "Coronate HK" and "Coronate TPA-100" manufactured by Tosoh Corporation. Nate HX", the same "Coronate (2096)", the trade name "Takenate D110N" made by Mitsui Chemicals, the same "Takenate D120N", the same "Takenate D140N", the same "Takenate D160N", etc. are mentioned. .

As the epoxy crosslinking agent, bisphenol A, epichlorohydrin type epoxy resin, ethylene glycidyl ether, polyethylene glycol diglycidyl ether, glycerin diglycidyl ether, glycerin triglycidyl ether, 1,6-hexanediol Glycidyl ether, trimethylolpropane triglycidyl ether, diglycidylaniline, diamineglycidylamine, N,N,N',N'-tetraglycidyl-m-xylylenediamine and 1,3 -Bis(N,N-diglycidylaminomethyl)cyclohexane etc. are mentioned. These can be used individually by 1 type or in combination of 2 or more types.

As a metal chelate compound, aluminum, iron, tin, titanium, nickel etc. are mentioned as a metal component, Acetylene, methyl acetoacetate, ethyl lactate, etc. are mentioned as a chelate component. These can be used individually by 1 type or in combination of 2 or more types.

The usage amount in the case of using a crosslinking agent is not particularly limited, and may be, for example, an amount exceeding 0 parts by weight with respect to 100 parts by weight of the polymer (A). The amount of the crosslinking agent can be, for example, 0.01 part by weight or more, preferably 0.05 part by weight or more, based on 100 parts by weight of the polymer (A). An increase in the amount of the crosslinking agent tends to suppress the adhesive force at the initial stage of application and improve the reworkability. It tends to have excellent bending recovery and workability. In some embodiments, the amount of the crosslinking agent used per 100 parts by weight of the polymer (A) may be 0.1 parts by weight or more, 0.5 parts by weight or more, or 0.8 parts by weight or more. On the other hand, from the viewpoint of appropriately permitting the mobility of the polymer (B) and obtaining an increase in the adhesive strength after heating, the amount of the crosslinking agent per 100 parts by weight of the polymer (A) is usually suitably 15 parts by weight or less, and 10 parts by weight It may be 5 parts or less, or 5 parts by weight or less.

The technology disclosed herein can be preferably carried out in an aspect using at least an isocyanate-based crosslinking agent as a crosslinking agent. From the viewpoint of achieving both good reworkability at the initial stage of application and increase in adhesive strength after heating, in some embodiments, the amount of isocyanate-based crosslinking agent relative to 100 parts by weight of polymer (A) is, for example, 0.01 part by weight or more, It is preferably 0.05 parts by weight or more, more preferably 0.07 parts by weight or more, and may be 0.10 parts by weight or more, or 0.15 parts by weight or more (for example, 0.20 parts by weight or more). By increasing the amount of isocyanate-based crosslinking agent used, appropriate cohesive force and elastic modulus are obtained, and there is a tendency for bending recovery and workability to be excellent. The amount of isocyanate-based crosslinking agent used per 100 parts by weight of the polymer (A) can be, for example, 5 parts by weight or less, preferably less than 1.0 parts by weight, more preferably less than 0.5 parts by weight, still more preferably. is less than 0.3 parts by weight, particularly preferably less than 0.2 parts by weight (for example, 0.15 parts by weight or less). As a result, the cohesive force of the pressure-sensitive adhesive and thus the modulus of elasticity (typically, the modulus of elasticity of the surface) are appropriately lowered, and a good bending holding force is obtained, and an increase in the adhesive force after heating is also easily obtained.

Although not particularly limited, when an isocyanate-based crosslinking agent is used in a configuration in which the pressure-sensitive adhesive layer contains a hydroxyl group-containing monomer as a monomer unit, the molar ratio of isocyanate groups and hydroxyl groups contained in the pressure-sensitive adhesive layer ([NCO] / [OH]), For example, it can be set to 0.001 or more. Thus, by increasing the amount of the isocyanate-based crosslinking agent relative to the hydroxyl group-containing monomer, the elastic modulus (typically, the surface elastic modulus) of the pressure-sensitive adhesive tends to be within a suitable range, and the bending recovery property tends to be improved. Also, processability tends to be excellent. In some preferred embodiments, the molar ratio ([NCO]/[OH]) is 0.002 or more, more preferably 0.004 or more, still more preferably 0.006 or more (eg 0.007 or more), may be 0.010 or more, 0.020 or more may be sufficient, and 0.030 or more may be sufficient. In addition, the said molar ratio ([NCO]/[OH]) can be 1.0 or less, for example, and may be 0.10 or less. By limiting the molar ratio to a predetermined value or less, a crosslinked structure suitable for greatly increasing the adhesive force after heating with respect to the adhesive force in the initial stage of attachment can be preferably formed. In some preferred embodiments, the molar ratio ([NCO]/[OH]) is 0.030 or less, more preferably 0.015 or less, even more preferably 0.012 or less (eg 0.009 or less), and may be 0.005 or less. Also, in the pressure-sensitive adhesive layer, isocyanate groups and hydroxyl groups may exist in a state in which at least some of them are chemically bonded (crosslinked). More specifically, the isocyanate group may exist in a chemically bonded (crosslinked) state with the hydroxyl group. Meanwhile, a part of the hydroxyl group may be chemically bonded to the isocyanate group, and the other part may exist in a state in which it is not chemically bonded (crosslinked) to the isocyanate group.

In some preferred embodiments, the pressure sensitive adhesive layer includes a catalyst. The catalyst may be added for the purpose of accelerating the curing of the pressure-sensitive adhesive layer during formation of the pressure-sensitive adhesive layer, typically, for the purpose of more effectively advancing any of the above-described crosslinking reactions. Therefore, the said catalyst is also called a curing catalyst or a crosslinking catalyst. By adding a catalyst, initial curing is accelerated, and side reactions that cause bubbles on the surface of the pressure-sensitive adhesive layer can be suppressed. Examples of the catalyst include organometallic compounds such as iron-based catalysts, tin-based catalysts, titanium-based catalysts, zirconium-based catalysts, lead-based catalysts, cobalt-based catalysts, and zinc-based catalysts, tertiary amine compounds, and the like. These can be used individually by 1 type or in combination of 2 or more types. Especially, from the balance of a reaction rate and a pot life, an iron-type catalyst and a tin-type catalyst are preferable, and an iron-type catalyst is especially preferable.

As an iron-type catalyst, iron acetylacetonate, iron 2-ethylhexanoate, etc. are mentioned, for example. An iron-type catalyst can be used individually by 1 type or in combination of 2 or more types.

Examples of the tin catalyst include dibutyltin dichloride, dibutyltin oxide, dibutyltin dibromide, dibutyltin maleate, dibutyltin dilaurate, dibutyltin diacetate, dibutyltin sulfide, Tributyltin methoxide, tributyltin acetate, triethyltin ethoxide, tributyltin ethoxide, dioctyltin oxide, dioctyltindilaurate, tributyltin chloride, tributyltintrichloroacetate, 2 -Ethyl hexanoate tin etc. are mentioned. Tin-type catalysts can be used individually by 1 type or in combination of 2 or more types.

The amount of the catalyst used is not particularly limited, and can be, for example, 0.0001 part by weight or more, preferably 0.001 part by weight or more, more preferably 0.003 part by weight or more, based on 100 parts by weight of the polymer (A). More preferably, it is 0.006 parts by weight or more, and particularly preferably 0.008 parts by weight or more. By using an appropriate amount of the catalyst, the generation of air bubbles from the pressure-sensitive adhesive layer is suppressed, and a smooth pressure-sensitive adhesive surface is easily obtained. The amount of catalyst used per 100 parts by weight of the polymer (A) can be, for example, 1 part by weight or less, and may be 0.1 part by weight or less. In some preferred embodiments, the amount of the catalyst used per 100 parts by weight of the polymer (A) is 0.03 parts by weight or less, more preferably 0.02 parts by weight or less, still more preferably 0.01 parts by weight or less, and may be 0.005 parts by weight or less. . By appropriately limiting the content of the catalyst with respect to 100 parts by weight of the polymer (A), it is easy to realize a suitable increase in adhesive strength.

Although not particularly limited, when a catalyst is used in a configuration in which the pressure-sensitive adhesive layer contains a hydroxyl group-containing monomer as a monomer unit, the amount of the catalyst used is the molar ratio between the catalyst and the hydroxyl group contained in the pressure-sensitive adhesive layer ([catalyst]/[OH] ) is, for example, 1.0 × 10 ^-6 or more, preferably 1.0 × 10 ^-5 or more, more preferably 1.0 × 10 ^-4 or more, still more preferably 2.0 × 10 ^-4 above, particularly preferably at least 3.0 × 10 ^-4 . By using an appropriate amount of the catalyst, the generation of air bubbles from the pressure-sensitive adhesive layer is suppressed, and a smooth pressure-sensitive adhesive surface is easily obtained. The molar ratio ([catalyst]/[OH]) can be, for example, 5.0 × 10 ^-2 or less, and may be 5.0 × 10 ^-3 or less. In some preferred embodiments, the molar ratio ([catalyst]/[OH]) is 3.0×10 ⁻³ or less, more preferably 1.0×10 ⁻³ or less, still more preferably 5.0×10 ⁻⁴ or less, and 3.0 It may be 10 ^-4 or less. By limiting the content of the catalyst appropriately, it is easy to realize a suitable increase in adhesive force.

(tackifying resin)

Tackifying resin can be included in an adhesive layer as needed. The tackifying resin is not particularly limited, but examples thereof include rosin-based tackifying resins, terpene-based tackifying resins, phenol-based tackifying resins, hydrocarbon-based tackifying resins, ketone-based tackifying resins, and polyamide-based tackifying resins. , epoxy-based tackifying resins, elastomer-based tackifying resins, and the like. Tackifying resin can be used individually by 1 type or in combination of 2 or more types.

The content of the tackifying resin is not particularly limited, and can be set so that appropriate adhesion performance is exhibited according to the purpose or use. The content of the tackifying resin relative to 100 parts by weight of the polymer (A) (when two or more kinds of tackifying resins are included, the total amount thereof) can be, for example, about 5 to 500 parts by weight. In addition, the technology disclosed herein can be preferably implemented in an aspect in which the amount of tackifying resin is limited. For example, the content of the tackifying resin relative to 100 parts by weight of the polymer (A) can be less than 20 parts by weight, may be less than 10 parts by weight, may be less than 3 parts by weight, or may be less than 1 part by weight (0 parts by weight). part to less than 1 part by weight), and in some embodiments, the pressure-sensitive adhesive layer is substantially free of tackifying resin.

In addition, the pressure-sensitive adhesive layer in the technique disclosed herein is a leveling agent, a plasticizer, a softener, a colorant (dyes, pigments, etc.), a filler, an antistatic agent, an antiaging agent, to the extent that the effects of the present invention are not significantly hindered. , Known additives that can be used for an adhesive, such as a ultraviolet absorber, an antioxidant, a light stabilizer, and an antiseptic, may be included as needed.

The pressure-sensitive adhesive layer constituting the reinforcing film disclosed herein may be a cured layer of the pressure-sensitive adhesive composition. That is, the pressure-sensitive adhesive layer can be formed by applying (for example, coating) a pressure-sensitive adhesive composition such as a water dispersion type, solvent type, photocurable type, or hot melt type to an appropriate surface and then appropriately performing a curing treatment. When two or more types of curing treatments (drying, crosslinking, polymerization, cooling, etc.) are performed, these can be performed simultaneously or in multiple stages. In an adhesive composition using a partially polymerized monomer material (polymer syrup), a final copolymerization reaction is typically performed as the curing treatment. That is, the partially polymerized product is subjected to a further copolymerization reaction to form a complete polymerized product. For example, if it is a photocurable adhesive composition, light irradiation is performed. If necessary, curing treatment such as crosslinking and drying may be performed. For example, what is necessary is just to perform photocuring after drying, when it is necessary to dry with a photocurable adhesive composition. In the pressure-sensitive adhesive composition using a completely polymerized product, typically, as the curing treatment, treatment such as drying (drying by heating) or crosslinking is performed as necessary.

Application of the pressure-sensitive adhesive composition can be performed using a conventional coater such as a gravure roll coater, a reverse roll coater, a kiss roll coater, a dip roll coater, a bar coater, a knife coater, or a spray coater, for example.

The thickness of the pressure-sensitive adhesive layer is not particularly limited, and may be, for example, 6 μm or more. In some embodiments, the thickness of the pressure-sensitive adhesive layer may be 8 μm or more, 10 μm or more, 15 μm or more, 20 μm or more, or more than 20 μm. As the thickness of the pressure-sensitive adhesive layer increases, the adhesive force after heating tends to increase. In some embodiments, the thickness of the pressure-sensitive adhesive layer may be, for example, 300 μm or less, 200 μm or less, 150 μm or less, 100 μm or less, 70 μm or less, or 50 μm or less. , and may be 40 μm or less. The fact that the thickness of the pressure-sensitive adhesive layer is not too large can be advantageous from the viewpoint of reducing the thickness of the reinforcing film or preventing cohesive failure of the pressure-sensitive adhesive layer. A reinforcing film having a pressure-sensitive adhesive layer having a thickness within the above-mentioned range can be a well-balanced adhesive property such as adhesive strength, bending recovery property, and bending holding power. In addition, in the case of a reinforcing film having a first pressure-sensitive adhesive layer and a second pressure-sensitive adhesive layer on the first and second surfaces of the substrate, the thickness of the pressure-sensitive adhesive layer described above may be applied to at least the thickness of the first pressure-sensitive adhesive layer. The thickness of the second pressure-sensitive adhesive layer may also be selected within the same range. In the case of an inorganic reinforcing film, the thickness of the reinforcing film coincides with the thickness of the pressure-sensitive adhesive layer.

<Support Substrate>

The reinforcing film according to some embodiments may be in the form of an adhesive sheet with a substrate having an adhesive layer on one side or both sides of the supporting substrate. The material of the supporting substrate is not particularly limited and can be appropriately selected according to the purpose of use of the reinforcing film or the mode of use. Non-limiting examples of substrates that can be used include resin films such as plastic films; foam sheets including foams such as polyurethane foam, polyethylene foam, and polychloroprene foam; woven fabrics and non-woven fabrics of various fibrous materials (natural fibers such as hemp and cotton, synthetic fibers such as polyester and vinylon, and semi-synthetic fibers such as acetate) alone or blended; papers such as Japanese paper, fine paper, kraft paper, and crepe paper; metal foils such as aluminum foil and copper foil; etc. can be mentioned. A base material having a structure in which these are compounded may be used. Examples of such a composite substrate include, for example, a substrate having a structure in which metal foil and the aforementioned plastic film are laminated, and a plastic substrate reinforced with inorganic fibers such as glass cloth.

As the substrate of the reinforcing film disclosed herein, various film substrates can be preferably used. The film substrate may be a porous substrate, such as a foam film or a non-woven fabric sheet, or a non-porous substrate, or a substrate having a structure in which a porous layer and a non-porous layer are laminated. In some embodiments, as the film substrate, a resin film capable of independently maintaining its shape (self-supporting or independent) can be preferably used as a base film. Here, the "resin film" has a non-porous structure and typically means a resin film substantially free of air bubbles (voidless). Therefore, the resin film is a concept different from a foam film or a nonwoven fabric. As the resin film, one capable of independently maintaining its shape (self-supporting or independent) can be preferably used. The resin film may have a single-layer structure or a multilayer structure of two or more layers (for example, a three-layer structure).

As the resin material constituting the resin film, for example, polyester, polyolefin, nylon 6, nylon 66, polyamide (PA) such as partially aromatic polyamide, polyimide (PI), polyamideimide (PAI), polyether Ether ketone (PEEK), polyether sulfone (PES), polyphenylene sulfide (PPS), polycarbonate (PC), polyurethane (PU), ethylene-vinyl acetate copolymer (EVA), polytetrafluoroethylene Resins, such as fluorine resins, such as (PTFE), acrylic resins, polyacrylates, polystyrene, polyvinyl chloride, and polyvinylidene chloride, can be used. The resin film may be formed using a resin material containing one type of these resins alone, or may be formed using a resin material in which two or more types are blended. The resin film may be unstretched or stretched (for example, uniaxial stretching or biaxial stretching).

Preferred examples of the resin material constituting the resin film include polyimide-based resins, polyester-based resins, PPS resins, and polyolefin-based resins. Here, the polyimide-based resin refers to a resin containing polyimide in a proportion exceeding 50% by weight. Similarly, polyester-based resin refers to a resin containing polyester in a proportion exceeding 50% by weight, PPS resin refers to a resin containing PPS in a proportion exceeding 50% by weight, and polyolefin-based resin refers to a polyolefin It refers to a resin contained in a proportion exceeding 50% by weight.

Specific examples of the polyester-based resin include polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyethylene naphthalate (PEN), and polybutylene naphthalate.

As polyolefin resin, 1 type of polyolefin can be used individually or in combination of 2 or more types of polyolefin. The polyolefin may be, for example, an α-olefin homopolymer, a copolymer of two or more kinds of α-olefins, a copolymer of one or two or more kinds of α-olefins and other vinyl monomers, and the like. Specific examples include polyethylene (PE), polypropylene (PP), poly-1-butene, poly-4-methyl-1-pentene, ethylene-propylene copolymers such as ethylene propylene rubber (EPR), and ethylene-propylene-butene copolymers. polymers, ethylene-butene copolymers, ethylene-vinyl alcohol copolymers, ethylene-ethyl acrylate copolymers, and the like. Both low density (LD) polyolefins and high density (HD) polyolefins may be used. Examples of the polyolefin resin film include a non-oriented polypropylene (CPP) film, a biaxially oriented polypropylene (OPP) film, a low density polyethylene (LDPE) film, a linear low density polyethylene (LLDPE) film, a medium density polyethylene (MDPE) film, and a high density polyethylene film. A polyethylene (HDPE) film, a polyethylene (PE) film obtained by blending two or more types of polyethylene (PE), and a PP/PE blend film obtained by blending polypropylene (PP) and polyethylene (PE).

Specific examples of the resin film that can be preferably used as a base film of the reinforcing film disclosed herein include a PI film, a PET film, a PEN film, a PPS film, a PEEK film, a CPP film, and an OPP film.

In the resin film, known additives such as light stabilizers, antioxidants, antistatic agents, colorants (dyes, pigments, etc.), fillers, slip agents, and antiblocking agents are necessary as long as the effects of the present invention are not significantly impaired. can be combined according to The blending amount of the additive is not particularly limited and can be appropriately set according to the purpose or the like.

The manufacturing method of a resin film is not specifically limited. For example, conventionally known general resin film forming methods such as extrusion molding, inflation molding, T-die cast molding, and calender roll molding can be appropriately employed.

The substrate may be substantially composed of such a base film. Alternatively, the substrate may include an auxiliary layer in addition to the base film. Examples of the auxiliary layer include an optical property adjustment layer (e.g., a coloring layer, an antireflection layer), a printed layer for imparting a desired appearance to the base material, a laminate layer, an antistatic layer, an undercoat layer, and a surface treatment layer such as a release layer. can be heard

The thickness of the substrate is not particularly limited, and can be selected according to the purpose of use of the reinforcing film, the mode of use, and the like. The thickness of the substrate may be, for example, 1000 μm or less. In some embodiments, from the viewpoint of handleability and processability of the reinforcing film, the thickness of the substrate may be, for example, 500 μm or less, 300 μm or less, 250 μm or less, or 200 μm or less. From the viewpoint of miniaturization or weight reduction of products to which the reinforcing film is applied, in some embodiments, the thickness of the substrate may be, for example, 160 μm or less, 130 μm or less, 100 μm or less, or 90 μm or less. 80 μm or less, 60 μm or less, 50 μm or less, 25 μm or less, 10 μm or less, or 5 μm or less. When the thickness of the substrate is reduced, the flexibility of the reinforcing film and the followability to the surface shape of the adherend tend to be improved. Further, from the viewpoint of handleability and workability, the thickness of the substrate may be, for example, 2 μm or more, 5 μm or more, 10 μm or more, 20 μm or more, 25 μm or more, or more than 25 μm. may be In some embodiments, the thickness of the substrate may be, for example, 30 μm or greater, 35 μm or greater, 55 μm or greater, 70 μm or greater, 75 μm or greater, 90 μm or greater, 120 μm or greater It may be more than μm. For example, in the reinforcing film, a substrate having a thickness of 30 μm or more can be preferably employed.

On the first surface of the substrate, if necessary, a conventionally known surface treatment such as corona discharge treatment, plasma treatment, ultraviolet irradiation treatment, acid treatment, alkali treatment, formation of an undercoat layer by application of a primer (primer), etc. may be carried out. Such surface treatment may be a treatment for improving anchoring properties of the pressure-sensitive adhesive layer to the base material. For example, in a reinforcing film provided with a base material containing a resin film as a base film, a base material subjected to such an anchoring property improvement treatment can be preferably employed. The above surface treatment can be applied alone or in combination. The composition of the primer used for forming the undercoat layer is not particularly limited, and can be appropriately selected from known ones. The thickness of the undercoating layer is not particularly limited, but is usually about 0.01 μm to 1 μm, preferably about 0.1 μm to 1 μm. Other treatments that can be applied to the first surface of the substrate as necessary include antistatic layer formation treatment, colored layer formation treatment, printing treatment, and the like.

When the reinforcing film disclosed herein is in the form of a single-sided pressure-sensitive adhesive sheet having an adhesive layer only on the first surface of the substrate, a conventionally known surface such as peeling treatment or antistatic treatment is applied to the second surface of the substrate, if necessary. Processing may be performed. For example, by surface-treating the back surface of the base material with a release agent (typically, forming a release layer using the release agent), the rewinding force of the reinforcing film wound in a roll shape can be reduced. As the peeling agent, a silicone-based peeling agent, a long-chain alkyl-based peeling agent, an olefin-based peeling agent, a fluorine-based peeling agent, a fatty acid amide-based peeling agent, molybdenum sulfide, silica powder, or the like can be used. In addition, corona discharge treatment, plasma treatment, ultraviolet irradiation treatment, acid treatment, alkali treatment, etc. may be performed on the second surface of the base material for the purpose of improving printability, reducing light reflectivity, and improving overlapping properties. In the case of the double-sided pressure-sensitive adhesive sheet, the second side of the substrate may be subjected to the same surface treatment as exemplified above as the surface treatment that can be applied to the first side of the substrate, if necessary. In addition, the surface treatment given to the 1st surface of a base material and the surface treatment given to the 2nd surface may be the same or different.

<Characteristics of Reinforcing Film>

It is preferable that the initial adhesive strength N ₂₃ measured after the reinforcing film disclosed herein is bonded to a stainless steel sheet and maintained at 23° C. for 30 minutes is limited to a predetermined value or less. In some embodiments, the adhesion N ₂₃ is, for example, preferably less than 500 gf/25 mm, more preferably less than 400 gf/25 mm, still more preferably less than 300 gf/25 mm, and particularly preferably less than 250 gf/25 mm. It is below (for example, 200 gf/25 mm or less), and 150 gf/25 mm or less may be sufficient. A low adhesive force N ₂₃ is preferable from the viewpoint of reworkability. The lower limit of the adhesive force N ₂₃ is not particularly limited, and may be, for example, 1 gf/25 mm or more. From the standpoint of affixing workability to adherends, prevention of misalignment before the increase in adhesive strength, etc., the adhesive force N ₂₃ is usually preferably 10 gf/25 mm or more. From the viewpoint of improving the adhesive force after heating, etc., in some embodiments, the adhesive force N ₂₃ may be, for example, 20 gf/25 mm or more, 50 gf/25 mm or more, 80 gf/25 mm or more, or 100 gf/25 mm or more. It may be mm or more (for example, 150 gf/25 mm or more).

Adhesion N ₂₃ [gf / 25 mm] is obtained after bonding to a stainless steel (SUS) plate as an adherend and leaving it for 30 minutes in an environment of 23 ° C. and 50% RH, and then in the same environment (ie, at 23 ° C.) , Peel angle of 180 degrees, under the conditions of a tensile speed of 300 mm / min, it is understood by measuring the 180 ° peel adhesive force. As the adherend, a SUS304BA board is used. In the measurement, if necessary, an appropriate bonding material (for example, a PET film having a thickness of about 25 µm) may be affixed to the reinforcing film to be measured for reinforcement. More specifically, the adhesive force N ₂₃ can be measured according to the method for measuring the initial adhesive force described in Examples described later.

The reinforcing film disclosed herein increases adhesive strength by heating, and, for example, adhesive strength N ₆₀ of 300 gf/25 mm or more, that is, bonded to a stainless steel sheet and held at 60° C. for 60 minutes, then measured at 23° C. It may indicate adhesion. In some embodiments, the adhesion N ₆₀ is greater than 400 gf/25 mm, preferably greater than 500 gf/25 mm. After the reinforcing film that satisfies this characteristic is affixed to an adherend, the adhesive force increases to a predetermined value or more by heating. According to the technique disclosed herein, it is possible to obtain strong adhesion by heating. In some preferred aspects, the adhesive force N ₆₀ is 600 gf/25 mm or more, more preferably 700 gf/25 mm or more, may be 800 gf/25 mm or more, or may be 900 gf/25 mm or more. The upper limit of the adhesive force N ₆₀ is not particularly limited. From the viewpoint of ease of manufacture or economic efficiency of the reinforcing film, in some embodiments, the adhesive force N ₆₀ may be, for example, 3000 gf/25 mm or less, 1500 gf/25 mm or less, or 1000 gf/25 mm or less.

Adhesion force N ₆₀ [gf / 25 mm] is bonded to a SUS plate as an adherend, held in an environment of 60 ° C. for 60 minutes, and then left in an environment of 23 ° C. and 50% RH for 30 minutes. In the same environment, It is understood by measuring the 180° peel adhesive force under conditions of a peel angle of 180 degrees and a tensile speed of 300 mm/min. As the adherend, a SUS304BA board is used similarly to the adhesive strength N ₂₃ . In the measurement, if necessary, an appropriate bonding material (for example, a PET film having a thickness of about 25 µm) may be affixed to the reinforcing film to be measured for reinforcement. More specifically, the adhesive force N ₆₀ can be measured according to the method for measuring the adhesive force after heating described in Examples described later.

The ratio of the adhesive force N ₆₀ [gf / 25 mm] to the adhesive force N ₂₃ [gf / 25 mm], that is, the adhesive strength increase ratio N ₆₀ /N ₂₃ is not particularly limited, and in some embodiments, N ₆₀ /N ₂₃ is suitably 1.5 or more, preferably 2.0 or more, more preferably 2.5 or more, still more preferably 3.0 or more (eg 3.5 or more), may be more than 5.0 (eg more than 7.0). According to the reinforcement|reinforcement film with large _N60 / _N23 , favorable reworkability is shown in the initial stage of sticking, and adhesive force can be raised greatly by subsequent heating etc. The upper limit of N ₆₀ /N ₂₃ is not particularly limited, and is usually 100 or less, and may be 30 or less, 15 or less, or 10 or less from the viewpoint of ease of manufacture of the reinforcing film or economical efficiency. In some embodiments, N ₆₀ /N ₂₃ may be, for example, 5 or less, 3 or less, or 2 or less.

In addition, the adhesive strength after heating of the reinforcing film disclosed herein represents one characteristic of the reinforcing film, and does not limit the usage mode of the reinforcing film. In other words, the use mode of the reinforcing film disclosed herein is not limited to the mode of heating at 60°C for 60 minutes, and is, for example, in the room temperature range (usually 20°C to 30°C, typically 23°C). °C to 25 °C) or higher can also be used in an aspect in which no particular treatment is performed. Also in such a mode of use, the adhesive strength increases over a long period of time, and strong bonding can be realized. In addition, the reinforcing film disclosed herein can promote an increase in adhesive force by performing heat treatment at a temperature higher than 30 ° C. (for example, about 50 to 70 ° C.) or higher than 60 ° C. at any timing after sticking. . The heating temperature in this heat treatment is not particularly limited, and can be set in consideration of workability, economy, and heat resistance of the base material of the reinforcing film or adherend. The heating temperature may be, for example, less than 150°C, 120°C or less, 100°C or less, 80°C or less, or 70°C or less. The heating temperature may be, for example, 40°C or higher, 45°C or higher, 50°C or higher, 55°C or higher, 60°C or higher, or 70°C or higher, may be 80°C or higher, or 100°C or higher. do. The heating time is not particularly limited, and may be, for example, 3 hours or less, 1 hour or less, 30 minutes or less, or 10 minutes or less. In addition, the heating time may be, for example, 1 minute or longer, 15 minutes or longer, 30 minutes or longer, or 1 hour or longer. Alternatively, a heat treatment for a longer period of time may be performed as long as the reinforcing film or adherend does not undergo significant thermal deterioration. In addition, the heat treatment may be performed at one time or may be divided into a plurality of times.

<Reinforcing film with substrate>

When the reinforcing film disclosed herein is in the form of an adhesive sheet with a substrate, the thickness of the reinforcing film may be, for example, 1000 μm or less, 600 μm or less, 350 μm or less, or 250 μm or less. do. From the viewpoint of miniaturization, weight reduction, and thinning of products to which the reinforcing film is applied, in some embodiments, the thickness of the reinforcing film may be, for example, 200 μm or less, 175 μm or less, or 140 μm or less. , 120 μm or less may be sufficient, and 100 μm or less (for example, less than 100 μm) may be sufficient. In addition, the thickness of the reinforcing film may be, for example, 5 μm or more, 10 μm or more, 15 μm or more, 20 μm or more, 25 μm or more, or 30 μm or more, from the viewpoint of handleability or the like. It may be more than μm. In some embodiments, the thickness of the reinforcing film may be, for example, 50 μm or more, 60 μm or more, 80 μm or more, 100 μm or more, or 120 μm or more. The upper limit of the thickness of the reinforcing film is not particularly limited.

In addition, the thickness of a reinforcing film means the thickness of the part affixed to the to-be-adhered body. For example, in the reinforcement film 1 of the structure shown in FIG. 1, it points out the thickness from the adhesive surface 21A of the reinforcement film 1 to the 2nd surface 10B of the base material 10, and it is a peeling liner The thickness of (31) is not included.

The reinforcing film disclosed herein may be suitably implemented in an aspect in which the thickness Ts of the supporting substrate is greater than the thickness Ta of the pressure-sensitive adhesive layer, that is, an aspect in which Ts/Ta is greater than 1, for example. Although not particularly limited, Ts/Ta may be, for example, 1.1 or more, 1.2 or more, 1.5 or more, or 1.7 or more. For example, by increasing Ts/Ta, even if the film for reinforcement is reduced in thickness, favorable effects tend to be more likely to be exhibited. In some embodiments, Ts/Ta may be 2 or more (eg greater than 2), 2.5 or more, or 2.8 or more. Also, Ts/Ta may be, for example, 50 or less, or 20 or less. Ts/Ta may be, for example, 10 or less, 8 or less, or 5 or less from the viewpoint of making it easy to exert high adhesive force after heating even if the reinforcing film is reduced in thickness.

It is preferable that the said adhesive layer adheres to the support base material. Adhesion here means that, in a reinforcing film whose adhesive strength has increased after sticking to an adherend, the adhesive layer is to such an extent that peeling does not occur at the interface between the adhesive layer and the supporting base material at the time of peeling of the reinforcing film from the adherend. It means showing sufficient anchoring property with respect to a support base material. According to the reinforcement film with a base material in which the adhesive layer is adhered to the supporting base material, the adherend and the supporting base material can be firmly integrated. As a preferred example of the reinforcement film in which the pressure-sensitive adhesive layer is adhered to the substrate, a reinforcement film in which peeling (anchoring destruction) between the pressure-sensitive adhesive layer and the supporting substrate does not occur when the adhesive force is measured after heating described above can be cited. there is. A reinforcing film in which anchoring destruction does not occur upon measurement of adhesive force after heating is a suitable example corresponding to a reinforcing film in which an adhesive layer is adhered to a base material.

The method for the reinforcement film disclosed herein includes, for example, bringing a liquid pressure-sensitive adhesive composition into contact with a first surface of a substrate, and forming a pressure-sensitive adhesive layer by curing the pressure-sensitive adhesive composition on the first surface, in this order. It can be preferably prepared by Curing of the pressure-sensitive adhesive composition may be accompanied by one or more of drying, crosslinking, polymerization, and cooling of the pressure-sensitive adhesive composition. Thus, according to the method of curing the liquid pressure-sensitive adhesive composition on the first surface of the substrate to form the pressure-sensitive adhesive layer, the method of disposing the pressure-sensitive adhesive layer on the first surface of the substrate by bonding the pressure-sensitive adhesive layer after curing to the first surface of the substrate In comparison, the anchoring property of the pressure-sensitive adhesive layer to the base material can be improved. Using this, it is possible to suitably manufacture a reinforcing film in which the pressure-sensitive adhesive layer is adhered to the base material.

In some embodiments, as a method of bringing the liquid pressure-sensitive adhesive composition into contact with the first surface of the substrate, a method of directly applying the pressure-sensitive adhesive composition to the first surface of the substrate may be employed. By bringing the first surface (adhesive surface) of the pressure-sensitive adhesive layer cured on the first surface of the base material into contact with the release surface, the second surface of the pressure-sensitive adhesive layer adheres to the first surface of the base material, and the first surface of the pressure-sensitive adhesive layer A reinforcing film having a configuration in which the surface is in contact with the peeling surface can be obtained. As the peeling surface, the surface of a peeling liner, the back surface of a base material subjected to peeling treatment, and the like can be used.

In addition, for example, in the case of a photocurable pressure-sensitive adhesive composition using a partial polymerization of monomer raw materials (polymer syrup), for example, after applying the pressure-sensitive adhesive composition to the release surface, the first surface of the substrate is covered with the applied pressure-sensitive adhesive composition In this way, the first surface of the substrate is brought into contact with the uncured pressure-sensitive adhesive composition, and in that state, the pressure-sensitive adhesive composition sandwiched between the first surface of the substrate and the peeling surface is irradiated with light to cure, thereby forming an adhesive layer.

In addition, the method illustrated above does not limit the manufacturing method of the reinforcement film disclosed here. In the case of manufacturing the reinforcing film disclosed herein, an appropriate method capable of adhering the pressure-sensitive adhesive layer to the first surface of the base material may be used alone or in combination of two or more. Examples of such a method include a method of forming a pressure-sensitive adhesive layer by curing the liquid pressure-sensitive adhesive composition on the first surface of the substrate as described above, or surface treatment to improve the anchoring property of the pressure-sensitive adhesive layer on the first surface of the substrate. how to do it, etc. For example, when the anchoring property of the pressure-sensitive adhesive layer to the base material can be sufficiently improved by a method such as providing an undercoating layer on the first surface of the base material, bonding the pressure-sensitive adhesive layer after curing to the first surface of the base material. You may manufacture the film for reinforcement by the method. In addition, the anchoring property of the pressure-sensitive adhesive layer to the substrate can be improved also by selecting the material of the substrate or the composition of the pressure-sensitive adhesive. In addition, by applying a temperature higher than room temperature to the reinforcing film having the pressure-sensitive adhesive layer on the first surface of the base material, the anchoring property of the pressure-sensitive adhesive layer to the base material can be improved. The temperature applied to improve anchoring properties may be, for example, about 35°C to 80°C, about 40°C to 70°C or higher, or about 45°C to 60°C.

The reinforcing film disclosed herein is a pressure-sensitive adhesive sheet having a first pressure-sensitive adhesive layer provided on the first surface of a substrate and a second pressure-sensitive adhesive layer provided on the second surface of the substrate (ie, a pressure-sensitive adhesive sheet with a double-sided adhesive substrate) In the case of the shape, the 1st adhesive layer and the 2nd adhesive layer may have the same structure, and may have different structures. When the configurations of the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer are different, the difference may be, for example, a difference in composition or a difference in structure (thickness, surface roughness, formation range, formation pattern, etc.). For example, the second pressure-sensitive adhesive layer may be a pressure-sensitive adhesive layer containing no polymer (B). In addition, the surface elastic modulus at 23 degreeC of the surface of the 2nd adhesive layer (2nd adhesive surface) may be outside the range of 1-20 kPa (for example, more than 20 kPa), and may be 30 kPa or more.

<Reinforcing film with release liner>

The reinforcing film disclosed herein may take the form of an adhesive product in which the surface (adhesive surface) of the pressure-sensitive adhesive layer is brought into contact with the release surface of the release liner. Therefore, according to this specification, a reinforcing film with a peeling liner can be provided which includes any of the reinforcing films disclosed herein and a peeling liner having a peeling surface in contact with the adhesive surface of the reinforcing film.

The thickness of the release liner is not particularly limited, but is usually about 5 µm to 200 µm. When the thickness of the peeling liner is within the above range, it is preferable because bonding workability to the pressure-sensitive adhesive layer and peeling workability from the pressure-sensitive adhesive layer are excellent. In some embodiments, the release liner may have a thickness of, for example, 10 μm or more, 20 μm or more, 30 μm or more, or 40 μm or more. In addition, the thickness of the peeling liner may be, for example, 100 µm or less, or 80 µm or less, from the viewpoint of facilitating peeling from the pressure-sensitive adhesive layer. The release liner may be subjected to a known antistatic treatment such as coating type, kneading type, vapor deposition type, etc., as needed.

The release liner is not particularly limited, and examples thereof include a release liner having a release layer on the surface of a liner substrate such as a resin film or paper (which may be paper laminated with a resin such as polyethylene) or a fluorine-based polymer (polyethylene). A release liner comprising a resin film formed of a low-adhesive material such as tetrafluoroethylene or the like) or a polyolefin-based resin (polyethylene, polypropylene, or the like) can be used. In terms of surface smoothness, a release liner having a release layer on the surface of a resin film as a liner base material or a release liner made of a resin film formed of a low-adhesive material can be preferably employed. The resin film is not particularly limited as long as it can protect the pressure-sensitive adhesive layer, and examples include polyethylene film, polypropylene film, polybutene film, polybutadiene film, polymethylpentene film, polyvinyl chloride film, and vinyl chloride air. A composite film, a polyester film (PET film, PBT film, etc.), a polyurethane film, an ethylene-vinyl acetate copolymer film, etc. are mentioned. For the formation of the release layer, known release agents such as silicone-based release agents, long-chain alkyl-based release agents, olefin-based release agents, fluorine-based release agents, fatty acid amide-based release agents, molybdenum sulfide, and silica powder can be used. there is. The use of a silicone-based release treatment agent is particularly preferred.

The thickness of the release layer is not particularly limited, but is usually about 0.01 μm to 1 μm, and preferably about 0.1 μm to 1 μm. The method for forming the release layer is not particularly limited, and a known method depending on the type of release treatment agent to be used and the like can be appropriately employed.

<Use>

Since the reinforcing film provided by this specification can exhibit good reworkability in the initial stage of being bonded to an adherend, for example, it contributes to suppression of yield reduction and improvement in quality of products containing the reinforcing film. can do. And after sticking the said reinforcing film to a to-be-adhered body, adhesive force can be raised large by aging or heating. For example, a reinforcing film can be firmly adhered to an adherend by heating at an appropriate timing after sticking to an adherend. Taking advantage of such characteristics, the reinforcing film disclosed herein can be preferably used for the purpose of reinforcing members included in various products in various fields.

The reinforcing film disclosed herein is, for example, in the form of a pressure-sensitive adhesive sheet with a base material in which an adhesive layer is formed on at least a first surface of a film-shaped base material having a first surface and a second surface, and is adhered to an adherend to It can be preferably used as a reinforcing film reinforcing the complex. In such a reinforcing film, as the film base material, one containing a resin film as a base film can be preferably used. Further, from the viewpoint of enhancing the reinforcing performance, the pressure-sensitive adhesive layer is preferably adhered to the first surface of the film-like substrate.

For example, in optical members used in optical products and electronic members used in electronic products, a high degree of integration, size reduction, and thinning are progressing, and a plurality of thin optical members/electronic members having different linear expansion coefficients and thicknesses are in progress. can be layered. Appropriate rigidity can be provided to the said optical member/electronic member by attaching the said reinforcement film to such a member. Thereby, in a manufacturing process and/or a product after manufacture, curl and curvature resulting from stress that may occur between a plurality of members having different linear expansion coefficients and thicknesses can be suppressed.

In addition, in the manufacturing process of optical products/electronic products, in the aspect of performing shape processing such as cutting processing on a thin optical member/electronic member as described above, by attaching a reinforcing film to the member and processing, The accompanying local stress concentration on the optical member/electronic member can be alleviated, and risks such as cracks, cracks, peeling of laminated members, and the like can be reduced. Attaching and handling a reinforcing member to an optical member/electronic member is helpful in relieving local stress concentration during transport, stacking, rotation, etc. of the member, and suppressing bending or curvature due to the member's own weight. It can be.

In addition, when devices such as optical products or electronic products including the reinforcing film are used by consumers in the market, when the device is dropped, placed under a heavy object, or when a flying object collides, Even when unintentional stress is applied, the stress applied to the device can be alleviated by including the reinforcing film in the device. Therefore, by including the reinforcing film in the device, durability of the device can be improved.

In addition, the reinforcing film disclosed herein can be suitably used, for example, in an aspect of being affixed to members constituting various portable devices (portable devices). Here, "carrying" is not sufficient simply to be able to carry, and is considered to mean having a level of portability that can be carried relatively easily by an individual (standard adult). In addition, examples of the mobile device referred to herein include mobile phones, smartphones, tablet personal computers, notebook computers, various wearable devices, digital cameras, digital video cameras, sound devices (portable music players, IC recorders, etc.), calculators (electronic desktop calculators, etc.), portable game devices, electronic dictionaries, electronic notebooks, electronic books, vehicle-mounted information devices, portable radios, portable TVs, portable printers, portable scanners, portable modems, etc., as well as mechanical wristwatches and flashlights. Watches, flashlights, hand mirrors, etc. may be included. Examples of the member constituting the portable electronic device may include an optical film or a display panel used in an image display device such as a thin layer display such as a liquid crystal display or a film display. The reinforcing film disclosed herein can be suitably used also in an aspect attached to various members in automobiles, home appliances, and the like.

In addition, since the reinforcing film disclosed herein has bending recovery properties and bending holding power, its features are utilized and bendable elements (for example, flexible devices such as flexible displays. Also referred to as rollable devices and foldable devices) can be detached) can be preferably used in an aspect attached to a member constituting a device equipped with. As such a device, for example, various types of portable devices (portable devices) described above are exemplified. Examples of the member constituting the portable electronic device may include an optical film or a display panel used in an image display device such as a liquid crystal display or an organic EL (electroluminescence) display. The reinforcing film disclosed herein can be preferably used for reinforcing a member constituting the device (typically, an image display device called a flexible device or a foldable device, etc.) in such a portable electronic device. there is.

In addition, the reinforcing film disclosed herein reinforces the optical member used as a component of, for example, a liquid crystal display panel, a plasma display panel (PDP), an organic EL display, etc. during manufacture and transport. suitable for use It is useful as a reinforcing film applied to optical members such as polarizing plates (polarizing films) for liquid crystal display panels, wave plates, retardation plates, optical compensation films, brightness enhancing films, light diffusion sheets, and reflective sheets.

In addition, the use of the reinforcing film disclosed herein is not particularly limited, and can be used for various applications aimed at imparting rigidity or impact resistance. The reinforcing film disclosed herein can be preferably used for flexible device applications as described above, and can also be used for other applications that do not include flexible devices. The fact that the reinforcing film has bending recovery and bending holding power means that the application range of the reinforcing film is less limited, and its practical advantages are great.

Example

Some embodiments of the present invention will be described below, but it is not intended to limit the present invention to those shown in these specific examples. In addition, "part" and "%" in the following description are based on weight unless otherwise specified.

[Synthesis of Polymer (A)]

(Synthesis Example A1)

90.2 parts of 2-ethylhexyl acrylate (2EHA), 8.6 parts of 4-hydroxybutyl acrylate (4HBA), N-acryloylmorpholine ( ACMO) 1.2 parts, 2,2'-azobisisobutyronitrile (AIBN) 0.2 parts as a polymerization initiator, and ethyl acetate as a polymerization solvent were introduced, nitrogen gas was introduced while gently stirring, the liquid temperature in the flask was 65 A polymerization reaction was performed for 6 hours while maintaining at around °C to prepare an acrylic polymer A1 solution having a polymer concentration of 35%. The weight average molecular weight (Mw) of acrylic polymer A1 was 540,000.

(Synthesis Example A2)

A solution of acrylic polymer A2 was obtained by carrying out solution polymerization in the same manner as in Synthesis Example A1 except that the monomer composition was changed to 2EHA/4HBA/ACMO/butyl acrylate (BA) = 86.1 parts/9.7 parts/1.8 parts/2.4 parts.

(Synthesis Example A3)

A solution of acrylic polymer A3 was obtained by performing solution polymerization in the same manner as in Synthesis Example A1 except that the monomer composition was changed to BA/4HBA=96 parts/4 parts.

(Synthesis Example A4)

The monomer composition was changed to 2EHA / 2-hydroxyethyl acrylate (HEA) / methyl methacrylate (MMA) / N-vinyl-2-pyrrolidone (NVP) = 65 parts / 15 parts / 7 parts / 13 parts Other than that, a solution of acrylic polymer A4 was obtained by solution polymerization in the same manner as in Synthesis Example A1.

[Synthesis of Polymer (B)]

(Synthesis Example B1)

101.15 parts of ethyl acetate, 40 parts of MMA, n-butyl methacrylate ((nBMA) 20 parts, 2-ethylhexyl methacrylate (2EHMA) 20 parts, polyorganosiloxane skeleton-containing methacrylic acid having a functional group equivalent of 900 g/mol Late monomer (trade name: X-22-174ASX, manufactured by Shin-Etsu Chemical Co., Ltd.) 8.7 parts, polyorganosiloxane backbone-containing methacrylate monomer having a functional group equivalent of 4600 g/mol (trade name: KF-2012, manufactured by Shin-Etsu Chemical Co., Ltd.) 11.3 parts and 0.8 parts of thioglycerol as a chain transfer agent were put into a four-necked flask equipped with a stirring blade, a thermometer, a nitrogen gas inlet tube, a condenser and a dropping funnel, and stirred at 70 ° C. under a nitrogen atmosphere for 30 minutes, As a thermal polymerization initiator, 0.2 part of AIBN was introduced and reacted at 70 ° C. for 3 hours. Subsequently, after stirring at 80 ° C. for 30 minutes, 0.1 part of AIBN was further added and reacted at 80 ° C. for 2 hours. Thereafter, 0.05 part of AIBN was added. It was further added and reacted at 80° C. for 2 hours to obtain polymer B1. The obtained polymer B1 had a Mw of 20000 and a Tg (T _B ) of -13.8° C.

(Synthesis Examples B2 to B6)

Polymers B2 to B6 were prepared in the same manner as in the preparation of polymer B1, except that the composition of the monomer components was changed as shown in Table 1. The Tg (T _B ) of each polymer was -8.4°C for polymer B2, -7.2°C for polymer B3, -0.6°C for polymer B4, -25.1°C for polymer B5, and 9.4°C for polymer B6. In Table 1, MMA is methyl methacrylate (Tg105 ℃), nBMA is n-butyl methacrylate (Tg20 ℃), 2EHMA is 2-ethylhexyl methacrylate (Tg-10 ℃), iBMA is iso Butyl methacrylate (Tg48 ℃), CHMA is cyclohexyl methacrylate (Tg66 ℃), X-22-174ASX is a methacrylate monomer containing a polyorganosiloxane skeleton (trade name: X-22-174ASX, Shin-Etsu Kaga) Ku Kogyo Co., Ltd., functional group equivalent weight 900 g / mol), KF-2012 represents a polyorganosiloxane backbone-containing methacrylate monomer (trade name: KF-2012, Shin-Etsu Chemical Co., Ltd., functional group equivalent weight 4600 g / mol), respectively.

Table 1 shows the compositions of the monomer components used for preparing the polymers B1 to B6 and the Tg (T _B ) of the polymers B1 to B6.

In addition, Mw of each polymer mentioned above was measured under the following conditions using a GPC apparatus (HLC-8220GPC, manufactured by Tosoh Corporation), and was determined by polystyrene conversion.

[GPC conditions]

ㆍSample concentration: 0.2wt% (tetrahydrofuran (THF) solution)

ㆍSample Injection Amount: 10μl

ㆍEluent: THF

ㆍFlow rate: 0.6㎖/min

ㆍMeasurement temperature: 40℃

ㆍColumn:

sample column; TSKguardcolumn SuperHZ-H (1 pc)+TSKgel SuperHZM-H (2 pcs)

reference column; TSKgel SuperH-RC (1 piece)

ㆍDetector: Differential Refractometer (RI)

[Production of Reinforcing Film]

<Example 1>

Add 100 parts of acrylic polymer A1, 2.0 parts of polymer B1, and 0.10 part of isocyanate compound C1 (trade name "Coronate HX", manufactured by Tosoh Corporation) as a crosslinking agent in terms of solid content, and dilute with ethyl acetate so that the total solid content is 30% Thus, an acrylic pressure-sensitive adhesive solution according to this example was obtained.

A release liner made of a polyester resin having a thickness of 75 μm (trade name “Diafoil MRF75”, manufactured by Mitsubishi Chemical Corporation) having one side treated with silicon was prepared, and the acrylic adhesive solution obtained above was applied to the siliconized side, By drying under conditions of 1 minute at °C, a pressure-sensitive adhesive layer having a thickness of 25 μm was formed.

Next, a polyimide base material (trade name "Upilex 50S", manufactured by Ube Industries, Ltd.) having a thickness of 50 µm was bonded to the surface of the obtained pressure-sensitive adhesive layer to obtain a reinforcing film according to this example. This reinforcing film has a pressure-sensitive adhesive layer on one side of a base material, and has a form of a pressure-sensitive adhesive sheet with a release liner in which a release surface of a release liner is in contact with the adhesive surface.

Further, for the reinforcing film of this example, the molar ratio ([NCO]/[OH]) was calculated from the amount of OH (the number of moles of hydroxyl groups in the acrylic polymer A1) and the amount of NCO (the number of moles of isocyanate groups in the isocyanate compound) in the pressure-sensitive adhesive layer. , which was 0.008.

<Examples 2 to 3>

Instead of Polymer B1, polymer B2 (Example 2) and Polymer B3 (Example 3) were used, but the same procedure as in Example 1 was performed to obtain an acrylic pressure-sensitive adhesive solution according to each example. Except for using each of these acrylic pressure-sensitive adhesive solutions, it was carried out similarly to preparation of the reinforcement film concerning Example 1, and the reinforcement film concerning each example was produced.

<Examples 4 to 7>

As shown in Table 2, the amount of isocyanate compound C1 used was 0.015 part (Example 4), 0.05 part (Example 5), 0.20 part (Example 6), 0.60 part in terms of solid content with respect to 100 parts of acrylic polymer A1. Except having changed to (Example 7), it carried out similarly to Example 1, and obtained the acrylic adhesive solution concerning each case. Except for using each of these acrylic pressure-sensitive adhesive solutions, it was carried out similarly to preparation of the reinforcement film concerning Example 1, and the reinforcement film concerning each example was produced.

<Examples 8 to 10>

As shown in Table 2, the amount of polymer B1 used was changed to 1.0 part (Example 8), 3.0 part (Example 9), and 6.0 part (Example 10) with respect to 100 parts of acrylic polymer A1. It carried out similarly to 1, and the acrylic adhesive solution concerning each case was obtained. Except for using each of these acrylic pressure-sensitive adhesive solutions, it was carried out similarly to preparation of the reinforcement film concerning Example 1, and the reinforcement film concerning each example was produced.

<Example 11>

An acrylic adhesive solution according to this example was obtained in the same manner as in Example 1 except that acrylic polymer A2 was used instead of acrylic polymer A1. A reinforcement film according to this example was produced in the same manner as in the preparation of the reinforcement film according to Example 1 except that the obtained acrylic pressure-sensitive adhesive solution was used.

<Example 12>

Example except that acrylic polymer A3 was used instead of acrylic polymer A1, and 0.07 part of isocyanate compound C2 (trade name "Takenate D110N", manufactured by Mitsui Chemicals, Inc.) was used as a crosslinking agent in terms of solid content with respect to 100 parts of acrylic polymer A3. In the same manner as in 1, an acrylic pressure-sensitive adhesive solution according to this example was obtained. A reinforcement film according to this example was produced in the same manner as in the preparation of the reinforcement film according to Example 1 except that the obtained acrylic pressure-sensitive adhesive solution was used.

<Example 13>

As shown in Table 2, the amount of isocyanate compound C2 used was changed to 0.09 part in terms of solid content with respect to 100 parts of acrylic polymer A3, and the acrylic adhesive solution according to this example was obtained in the same manner as in Example 12. A reinforcement film according to this example was produced in the same manner as in the preparation of the reinforcement film according to Example 1 except that the obtained acrylic pressure-sensitive adhesive solution was used.

<Comparative Examples 1 to 2>

Except for using Polymer B5 (Comparative Example 1) and Polymer B6 (Comparative Example 2) instead of Polymer B1, acrylic adhesive solutions related to each example were obtained in the same manner as in Example 1. Except for using each of these acrylic pressure-sensitive adhesive solutions, it was carried out similarly to preparation of the reinforcement film concerning Example 1, and the reinforcement film concerning each example was produced.

<Comparative Example 3>

Example except that acrylic polymer A4 was used instead of acrylic polymer A1, and 0.50 part of isocyanate compound C2 (trade name "Takenate D110N", manufactured by Mitsui Chemicals, Inc.) was used as a crosslinking agent in terms of solid content with respect to 100 parts of acrylic polymer A4. In the same manner as in 1, an acrylic pressure-sensitive adhesive solution according to this example was obtained. A reinforcement film according to this example was produced in the same manner as in the preparation of the reinforcement film according to Example 1 except that the obtained acrylic pressure-sensitive adhesive solution was used.

<Comparative Examples 4 to 5>

As shown in Table 2, the amount of isocyanate compound C2 used was changed to 1.10 parts (Comparative Example 4) and 2.50 parts (Comparative Example 5) in terms of solid content with respect to 100 parts of acrylic polymer A4. , The acrylic pressure-sensitive adhesive solution for each case was obtained. Except for using each of these acrylic pressure-sensitive adhesive solutions, it was carried out similarly to preparation of the reinforcement film concerning Example 1, and the reinforcement film concerning each example was produced.

<Example 14>

Except having used polymer B4 instead of polymer B1, it carried out similarly to Example 1, and obtained the acrylic adhesive solution concerning this example. A reinforcement film according to this example was produced in the same manner as in the preparation of the reinforcement film according to Example 1 except that the obtained acrylic pressure-sensitive adhesive solution was used.

<evaluation>

[Surface elastic modulus]

About the reinforcing film concerning each case, aging was performed at 50 degreeC for 1 day, and the surface elastic modulus was measured. The release liner protecting the adhesive surface is peeled off, and an indenter is pushed into the surface of the adhesive layer to a depth of 6 μm using a nanoindenter device (Triboindenter manufactured by Hysitron Inc.). The maximum load (Pmax) [GPa/mm ² ] was obtained. To this, the expression:

Surface hardness [㎬]=Pmax/A

, the surface hardness was calculated, converted into [kPa] units, and recorded as the surface elastic modulus at 23°C (surface elastic modulus at 23°C). Measurement conditions are as follows. In addition, in the said formula, A is the contact projected area [ ^mm2 ] of an indenter.

(Measuring conditions)

Indenter approach speed: 5 μm/s

Maximum displacement: 6㎛

Indentation speed: 5 μm/s

Subtraction speed: 5 μm/s

Used indenter: Conical (spherical indenter: curvature radius 10㎛)

Measurement method: single indentation measurement

Measurement temperature: room temperature (23 ° C)

[Bulk modulus G' and tanδ]

A release liner R1 made of a polyester resin having a thickness of 75 μm and having one side treated with silicon was prepared (trade name “Diafoil MRF75”, manufactured by Mitsubishi Chemical Corporation), and the acrylic adhesive solution according to each example was applied to the siliconized side. , by drying under conditions of 130 ° C. for 1 minute, a pressure-sensitive adhesive layer having a thickness of 25 μm was formed. Next, release liner R2 (trade name "Diafoil MRE75", manufactured by Mitsubishi Chemical Corporation) made of a polyester resin having a thickness of 75 μm subjected to silicone treatment on one side was applied to the surface of the obtained pressure-sensitive adhesive layer, so that the silicone-treated surface was on the pressure-sensitive adhesive layer side. and coated, and aged at 50°C for 1 day.

Only the obtained pressure-sensitive adhesive layer was taken out and laminated to a thickness of about 1 mm, and this was punched out to φ 8 mm to prepare a cylindrical pellet, which was used as a sample for measurement.

The measurement sample was fixed to a jig of a φ8 mm parallel plate, and the storage modulus G', loss modulus G" and loss tangent tanδ were measured under the following conditions by a dynamic viscoelasticity measuring device ("ARES" manufactured by TA Instruments). Measured, storage modulus G' ₂₃ [㎪] at 23 ° C, storage modulus G' ₈₀ [㎪] at 80 ° C, and tanδ (loss modulus G at 80 ° C) storage at ₈₀ / 80 ° C Elastic modulus G' ₈₀ ) was obtained.

・Measurement Mode: Shear Mode

Temperature range: -70°C to 200°C

・Temperature increase rate: 5℃/min

・Frequency: 1Hz

Further, the storage modulus G' corresponds to a portion that is stored as elastic energy when the material is deformed, and is an index indicating the degree of hardness. The loss elastic modulus G" corresponds to the portion of energy lost due to internal friction or the like when the material is deformed, and indicates the degree of viscosity.

[Initial Adhesion]

About the reinforcing film concerning each case, aging was performed at 50 degreeC for 1 day, and what cut to the peeling liner width 25mm x length 140mm was made into the measurement sample. The release liner was peeled off from the measurement sample to expose the adhesive surface, and a 2 kg hand roller was reciprocated once to compress the stainless steel plate (SUS304BA plate) as an adherend. After the measurement sample pressed against the adherend in this way was left at an environmental temperature of 23° C. for 30 minutes, a tensile tester (manufactured by Shimadzu Corporation, trade name “Autograph AG-Xplus HS 6000 mm/min high-speed model (AG- 50NX plus)"), under the conditions of a peeling angle of 180 degrees and a peeling speed (tensile speed) of 300 mm/min, the load when the reinforcing film was peeled from the adherend was measured, and the average load at the time of measurement was measured. was recorded as the initial tack [gf/25 mm].

[Adhesion after heating]

About the reinforcing film concerning each case, it carried out similarly to the said initial adhesive force measurement, prepared the measurement sample, and crimped|bonded to the adherend. Then, the measurement sample pressed against the adherend was heated for 60 minutes at an environmental temperature of 60°C. After that, it was allowed to stand for 30 minutes at an environmental temperature of 23 ° C., and peeling was performed using a tensile tester (manufactured by Shimadzu Corporation, trade name “Autograph AG-Xplus HS 6000 mm/min high-speed model (AG-50NX plus)”) Under conditions of an angle of 180 degrees and a peeling speed (tensile speed) of 300 mm/min, the load when the reinforcing film was peeled off from the adherend was measured, and the average load at the time of measurement was measured as adhesive strength after heating [gf/25 mm]. recorded as

[Bending retention test]

The reinforcing film according to each case was aged at 50°C for one day, then the release liner was peeled off, and a polyimide base material having a thickness of 25 μm (trade name “Upilex 25S” manufactured by Ube Kosan Co., Ltd.) was applied to the exposed adhesive surface. ) were bonded and heated at 60°C for 60 minutes to bring them into close contact. Next, the obtained measurement sample (laminated body) was fixed with the 25 μm substrate side inside, bent so as to be φ 6 mm, and heated at 80° C. for 15 hours. And, after leaving it at room temperature (23 ° C.) and confirming that it has sufficiently cooled, the measurement sample is released from the bending state, and within 10 minutes from release, using a protractor, the bending of the measurement sample bent The angle [°] was measured to evaluate bending recovery. In addition, the bending angle is the opening angle of the measurement sample (the angle on the side where the measurement sample is opened from the bent state), and the closer to 180 °, the better the bending recovery, and the closer the bending angle is to 0 °, the better the bending recovery It falls.

Subsequently, as evaluation of the bending holding force, the presence or absence of "peeling" in the bent portion of the measurement sample was visually confirmed, the case where "peeling" was not observed was evaluated as "○", and the case where "peeling" was observed was evaluated. It was evaluated as "x".

Table 2 shows the evaluation results of the reinforcing films of Examples 1 to 13 and Comparative Examples 1 to 5. In Table 2, the outline of the composition of the adhesive layer concerning each case is also shown together.

Table 3 shows the evaluation results of the bending recovery and recovery holding power of the reinforcing film according to Example 14 together with the outline of Example 14 (composition and characteristics of the pressure-sensitive adhesive layer).

As shown in Table 2, the pressure-sensitive adhesives according to Examples 1 to 13 contained polymer (A) and polymer (B), and the Tg of the polymer (B) was within the range of -20 ° C to 5 ° C. . The reinforcing films related to these examples better compatible the low initial adhesive force and the increase in adhesive force after heating, compared to Comparative Examples 1 and 2 in which the Tg of the polymer (B) was outside the range of -20 ° C to 5 ° C. Further, the reinforcing films according to Examples 1 to 13 had a 23°C surface elastic modulus of the pressure-sensitive adhesive layer in the range of 1 to 20 kPa, and had good bending recovery and bending holding power. On the other hand, in Comparative Examples 3 to 5 in which the 23°C surface modulus was out of the range of 1 to 20 kPa, peeling was observed in the bending holding test.

More specifically, from the comparison with Examples 1 to 3, the higher the Tg of the polymer (B) in the range of -20 ° C to 5 ° C, the lower the initial adhesive force while realizing the adhesive force increase after heating, and the initial easy peelability There was a tendency for this to improve. On the other hand, in Comparative Example 1 in which the Tg of the polymer (B) was less than -20°C, the initial adhesive force was high and the easy peelability was poor. Further, in Comparative Example 2 in which the Tg of the polymer (B) was more than 5°C, the increase in adhesive force after heating was small. In addition, from the comparison of Examples 4 to 7, the higher the 23 ° C. surface modulus of the pressure-sensitive adhesive layer was in the range of 1 to 20 kPa, the bending recovery tended to improve, and the initial adhesive force and the adhesive force after heating tended to decrease. . Examples 5 to 7 were superior in bending recovery properties to Example 4, the 23°C surface modulus was 2 kPa or more, and the tanδ ₈₀ at 80°C was in the range of 0.10 to 0.60. Further, in Example 7, both the surface modulus and the bulk modulus became high values, resulting in a relatively low increase in adhesive force after heating compared to Examples 4 to 6. In Examples 4 to 6, no difference was found in the 23°C bulk modulus G' ₂₃ of the pressure-sensitive adhesive layer. In addition, the 80 degreeC bulk modulus _G'80 in Examples 1-3 and 5 was the same. Regarding Examples 1 to 7, it can be said that the 23°C surface modulus had a higher correlation with the bending recovery than the bulk modulus. Further, in Examples 1 to 7, the molar ratio of isocyanate groups and hydroxyl groups in the pressure-sensitive adhesive layers of Examples 1 to 3 and 5 to 6 in which the initial adhesive force, the adhesive force after heating, the bending recovery and the bending holding force were improved in a more balanced manner ( [NCO]/[OH]) was in the range of 0.002 to 0.03.

In addition, from the comparison of Examples 8 to 10, it was confirmed that the adhesive strength decreased as the amount of polymer (B) increased. In Examples 8 to 9 in which the amount of polymer (B) used was within the range of 0.5 to 5 parts per 100 parts of polymer (A), the initial adhesive force was less than 400 gf/25 mm and the adhesive force after heating was 500 gf/25 mm or more. , The easy peelability at the initial stage of attachment and the increase in adhesive strength after heating were more compatible. In addition, as the amount of polymer (B) used increased, the 23°C surface elastic modulus increased and the bending recovery tended to decrease. In addition, from the results of Examples 11 to 13, it was confirmed that the desired effect was achieved even if the type of polymer (A) or crosslinking agent type of the pressure-sensitive adhesive was changed.

Further, as shown in Table 3, even in Example 14 using the polymer (B) having a surface modulus of elasticity at 23°C of the pressure-sensitive adhesive layer in the range of 1 to 20 kPa and a Tg of -1.6°C, bending recovery and bending It was confirmed that the holding force was compatible. Although not shown in particular in the table, the reinforcing film according to Example 14 had an initial adhesive force of less than 400 gf/25 mm (specifically, less than 200 gf/25 mm), and an increase in adhesive force after heating (adhesive force increase ratio N ₆₀ /N ₂₃ ) is 7 (times), and the effect of the technique disclosed herein was realized.

As mentioned above, although the specific example of this invention was demonstrated in detail, these are only examples and do not limit the claim. The technology described in the claims includes various modifications and changes of the specific examples exemplified above.

1, 2, 3: reinforcement film
10: supporting substrate
10A: first side
10B: second side
21: pressure-sensitive adhesive layer (first pressure-sensitive adhesive layer)
21A: adhesive surface (first adhesive surface)
21B: adhesive surface (second adhesive surface)
22: pressure-sensitive adhesive layer (second pressure-sensitive adhesive layer)
22A: adhesive surface (second adhesive surface)
31, 32: release liner
100, 200, 300: Reinforcing film with release liner

Claims (7)

A reinforcing film having an adhesive layer,
The pressure-sensitive adhesive layer includes a polymer (A) and a polymer (B),
The polymer (B) includes a monomer unit having a polyorganosiloxane skeleton and a (meth)acrylic monomer unit,
The pressure-sensitive adhesive layer has a surface modulus of elasticity of 1 to 20 kPa at 23 ° C,
The glass transition temperature T _B of the polymer (B) is -20 ° C to 5 ° C, a reinforcing film. According to claim 1,
The pressure-sensitive adhesive layer has a bulk modulus of elasticity G' ₂₃ at 23 ° C. of 10 to 200 kPa, a bulk modulus of elasticity G' ₈₀ at 80 ° C. of 5 to 100 kPa, and tan δ ₈₀ at 80 ° C. of 0.10 to 0.60, reinforcement film. According to claim 1 or 2,
The polymer (A) is an acrylic polymer, a reinforcing film. According to any one of claims 1 to 3,
The content of the polymer (B) in the pressure-sensitive adhesive layer is 0.5 to 5 parts by weight based on 100 parts by weight of the polymer (A). According to any one of claims 1 to 4,
The molar ratio ([NCO]/[OH]) of the isocyanate group and the hydroxyl group included in the pressure-sensitive adhesive layer is 0.002 to 0.03, a reinforcing film. The optical member to which the reinforcing film according to any one of claims 1 to 5 was bonded. An electronic member to which the reinforcing film according to any one of claims 1 to 5 is bonded.

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