JP6935530B2 - Laminates and display devices containing them - Google Patents

Description

The present invention relates to a laminate and a display device including the laminate.

Korean Patent No. 10-2016-0053788 (Patent Document 1) and Korean Patent No. 10-2017-093610 (Patent Document 2) each include a laminate for a display device having a plurality of pressure-sensitive adhesive layers. Have been described.

Korean Patent No. 10-2016-0053788 Korean Patent No. 10-2017-093610

The pressure-sensitive adhesive layer used in this type of laminate is generally excellent in stress relaxation performance for relaxing external stress. However, when the laminate is bent at room temperature, air bubbles are often generated in the pressure-sensitive adhesive layer, so that it is required to improve the durability of the pressure-sensitive adhesive layer.

In view of the above circumstances, it is an object of the present invention to provide a laminate having improved durability by suppressing the generation of air bubbles in the pressure-sensitive adhesive layer and a display device containing the same.

The present invention provides the following laminate and a display device including the following.
[1] A front plate, a first pressure-sensitive adhesive layer formed by using the first pressure-sensitive adhesive composition, a polarizer layer, and a second pressure-sensitive adhesive layer formed by using the second pressure-sensitive adhesive composition. It is a laminated body including the back plate in this order.
The first pressure-sensitive adhesive reference layer is formed using the first pressure-sensitive adhesive composition so that the thickness of the first pressure-sensitive adhesive reference layer and the thickness of the second pressure-sensitive adhesive reference layer are the same, and the second pressure-sensitive adhesive is formed. When the second pressure-sensitive adhesive reference layer is formed using the agent composition, the first pressure-sensitive adhesive reference layer and the second pressure-sensitive adhesive reference layer are laminates that satisfy the relationship of the following formula (1).
ΔR1 ≤ ΔR2 (1)
[In equation (1), ΔR1 represents the value obtained by subtracting R1B from R1A.
ΔR2 represents the value obtained by subtracting R2B from R2A.
The R1A represents a first shear creep rate (% / μm), which is a shear creep value per 1 μm of thickness at 25 ° C. obtained for the first pressure-sensitive adhesive reference layer after performing a strain repeated addition test.
The R1B represents a second shear creep rate (% / μm), which is a shear creep value per 1 μm of thickness at 25 ° C. obtained with respect to the first pressure-sensitive adhesive reference layer before executing the strain repeated addition test.
The R2A indicates a third shear creep rate (% / μm), which is a shear creep value per 1 μm of thickness at 25 ° C. obtained for the second pressure-sensitive adhesive reference layer after performing a strain repeated addition test.
The R2B represents a fourth shear creep rate (% / μm), which is a shear creep value per 1 μm of thickness obtained at 25 ° C. with respect to the second pressure-sensitive adhesive reference layer before executing the strain repeated addition test. ]
[2] The laminate according to [1], wherein the second shear creep rate (% / μm) is 0.1 or more and 0.2 or less.
[3] The laminate according to [1] or [2], wherein at least one of the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer has a thickness of 20 μm or more and 50 μm or less.
[4] The laminate according to any one of [1] to [3], which has one or more retardation layers between the polarizer layer and the back plate.
[5] The laminate according to any one of [1] to [4], wherein the back plate is a touch sensor panel.
[6] A display device including the laminate according to any one of [1] to [5].
[7] The display device according to [6], which can be bent with the front plate side inside.

According to the present invention, it is possible to provide a laminate having improved durability by suppressing the generation of air bubbles in the pressure-sensitive adhesive layer and a display device containing the same.

It is the schematic sectional drawing which shows an example of the laminated body which concerns on this invention. It is the schematic sectional drawing which shows another example of the laminated body which concerns on this invention. It is sectional drawing which shows typically the manufacturing method about the laminated body which concerns on this invention.

Hereinafter, a laminated body according to one aspect of the present invention (hereinafter, also simply referred to as “laminated body”) will be described with reference to the drawings.

[Laminated body]
FIG. 1 shows a schematic cross-sectional view of the laminated body according to one aspect of the present invention. The laminate 100 is formed by using the front plate 101, the first pressure-sensitive adhesive layer 102 formed by using the first pressure-sensitive adhesive composition, the polarizer layer 103, and the second pressure-sensitive adhesive composition. The pressure-sensitive adhesive layer 104 and the back plate 105 are included in this order. Hereinafter, the first pressure-sensitive adhesive layer 102 and the second pressure-sensitive adhesive layer 104 may be collectively referred to as a “taste-sensitive adhesive layer”.

The thickness of the laminated body 100 is not particularly limited because it varies depending on the function required for the laminated body, the application of the laminated body, and the like, but is, for example, 30 μm or more and 1500 μm or less, preferably 40 μm or more and 1000 μm or less, and more preferably 50 μm or more. It is 500 μm or less.

The plan view shape of the laminated body 100 may be, for example, a rectangular shape, preferably a rectangular shape having a long side and a short side, and more preferably a rectangular shape. When the shape of the laminate 100 in the plane direction is rectangular, the length of the long side may be, for example, 10 mm or more and 1400 mm or less, preferably 50 mm or more and 600 mm or less. The length of the short side may be, for example, 5 mm or more and 800 mm or less, preferably 30 mm or more and 500 mm or less, and more preferably 50 mm or more and 300 mm or less. Each layer constituting the laminated body may have a corner portion R-processed, an end portion notched, or a perforated portion.

The laminated body 100 can be applied to, for example, a display device or the like. The display device is not particularly limited, and examples thereof include an organic electroluminescence (organic EL) display device, an inorganic electroluminescence (inorganic EL) display device, a liquid crystal display device, and an electroluminescent display device. The display device may have a touch panel function. Further, the display device to which the laminated body 100 is applied can be used as a flexible display capable of bending or winding. It is preferable that the display device can be bent with the front plate 101 side inside. However, the laminated body 100 may be able to be bent with the front plate 101 side facing outward.

[Adhesive layer (first adhesive layer formed by using the first adhesive composition and second adhesive layer formed by using the second adhesive composition)]
The laminate 100 includes a first pressure-sensitive adhesive layer 102 formed by using the first pressure-sensitive adhesive composition as described above, and a second pressure-sensitive adhesive layer 104 formed by using the second pressure-sensitive adhesive composition. .. In the laminate 100, between the first pressure-sensitive adhesive composition used for forming the first pressure-sensitive adhesive layer 102 and the second pressure-sensitive adhesive composition used for forming the second pressure-sensitive adhesive layer 104, The following relationships are built. That is, the first pressure-sensitive adhesive reference layer is formed using the first pressure-sensitive adhesive composition so that the thickness of the first pressure-sensitive adhesive reference layer and the thickness of the second pressure-sensitive adhesive reference layer are the same, and the second pressure-sensitive adhesive reference layer is formed. When the second pressure-sensitive adhesive reference layer is formed using the pressure-sensitive adhesive composition, the first pressure-sensitive adhesive reference layer and the second pressure-sensitive adhesive reference layer satisfy the relationship of the following formula (1). The thickness of the first pressure-sensitive adhesive reference layer and the thickness of the second pressure-sensitive adhesive reference layer can be, for example, 200 μm.
ΔR1 ≤ ΔR2 (1)
[In equation (1), ΔR1 represents the value obtained by subtracting R1B from R1A.
ΔR2 represents the value obtained by subtracting R2B from R2A.
R1A represents the first shear creep rate (% / μm), which is the shear creep value per 1 μm of thickness at 25 ° C. obtained for the first pressure-sensitive adhesive reference layer after performing the strain repeated addition test.
R1B represents the second shear creep rate (% / μm), which is the shear creep value per 1 μm of thickness at 25 ° C., which was obtained for the first pressure-sensitive adhesive reference layer before performing the strain repeated addition test.
R2A indicates a third shear creep rate (% / μm), which is a shear creep value per 1 μm of thickness at 25 ° C., which was obtained for the second pressure-sensitive adhesive reference layer after performing the strain repeated addition test.
R2B represents the fourth shear creep rate (% / μm), which is the shear creep value per 1 μm of thickness at 25 ° C., which was obtained for the second pressure-sensitive adhesive reference layer before the strain repeated addition test was performed. ].

The shear creep value (%) at 25 ° C., the first shear creep rate (% / μm) representing R1A, the second shear creep rate (% / μm) representing R1B, and the third shear creep rate (%) representing R2A. The fourth shear creep rate (% / μm) representing (/ μm) and R2B can be determined according to the measurement methods described in the columns of Examples described later, respectively.

In the laminated body 100, the first pressure-sensitive adhesive layer 102 and the second pressure-sensitive adhesive layer 104, which are the pressure-sensitive adhesive layers contained therein, are the first pressure-sensitive adhesive reference layer and the second pressure-sensitive adhesive reference layer that satisfy the relationship of the above formula (1). It is formed by using a first pressure-sensitive adhesive composition and a second pressure-sensitive adhesive composition that can form a layer. In this case, the laminated body 100 can improve the durability by suppressing the generation of air bubbles in the pressure-sensitive adhesive layer. In particular, when the laminated body 100 is bent with the front plate 101 side facing inward, the generation of air bubbles in the pressure-sensitive adhesive layer can be further suppressed. Therefore, the laminated body 100 is preferably used for a laminated body of a method (so-called in-folding method) in which the front plate side is turned inward and a display device including the laminated body 100. It is preferable that the first pressure-sensitive adhesive reference layer and the second pressure-sensitive adhesive reference layer satisfy the relationship of the formula (2) represented by ΔR1 <ΔR2.

A first pressure-sensitive adhesive composition and a second pressure-sensitive adhesive composition in which the first pressure-sensitive adhesive layer 102 and the second pressure-sensitive adhesive layer 104 can form a first pressure-sensitive adhesive reference layer and a second pressure-sensitive adhesive reference layer satisfying the relationship of the above formula (1). The reason why the above-mentioned effects are obtained when each of the pressure-sensitive adhesive compositions is formed is not clear in detail, but is considered to be due to the following mechanism. First, in the process of research by the present inventors, it was found that when the laminate is bent with the front plate side inside, air bubbles may be generated in the pressure-sensitive adhesive layer. In that case, it was clarified that most of the places where bubbles are generated are on the pressure-sensitive adhesive layer near the front plate side, that is, on the side of the first pressure-sensitive adhesive layer.

Here, when the first pressure-sensitive adhesive reference layer and the second pressure-sensitive adhesive reference layer satisfy the relationship of the above formula (1), the first pressure-sensitive adhesive composition is repeatedly strained as compared with the second pressure-sensitive adhesive composition. It means that the composition has the same or smaller changes in shear creep rate (% / μm) before and after the addition. Furthermore, the feature that the change in shear creep rate (% / μm) is small means that it is excellent in performance (that is, durability) that can maintain the properties peculiar to the pressure-sensitive adhesive layer against external stress. do. Therefore, the pressure-sensitive adhesive layer (first pressure-sensitive adhesive layer 102) formed by using the first pressure-sensitive adhesive composition is formed on the pressure-sensitive adhesive layer (second pressure-sensitive adhesive layer 104) formed by using the second pressure-sensitive adhesive composition. In comparison, it is considered that the durability against bending can be the same or better.

From the above, the present inventors have described a pressure-sensitive adhesive layer (first pressure-sensitive adhesive layer) formed by using a first pressure-sensitive adhesive composition having excellent durability against bending as a pressure-sensitive adhesive layer near the front plate side where bubbles frequently occur. 102) was placed. As a result, when the laminated body 100 was bent with the front plate 101 side inside, the laminated body 100 was reached, which could suppress the generation of air bubbles in the pressure-sensitive adhesive layer. Specifically, as shown in Examples described later, the laminate 100 has a mandrel (mandrel), which is a cylindrical jig having a diameter (φ) of more than 10 mm and a diameter of 15 mm or less, arranged inside the front plate 101 side. Even when the laminate 100 is bent along the mandrel, the generation of air bubbles in the pressure-sensitive adhesive layer can be suppressed (hereinafter, such performance is also referred to as "excellent in bending durability"). ..

As used herein, "bending" includes a form of bending in which a curved surface is formed at a bent portion. In the form of bending, the radius of curvature of the bent inner surface is not limited unless otherwise specified. Further, "bending" includes a form of refraction in which the refraction angle of the inner surface is larger than 0 degrees and less than 180 degrees unless otherwise specified, and the radius of curvature of the inner surface is close to zero, or the refraction angle of the inner surface is 0 degrees. Includes certain folding forms.

The values of ΔR1 and ΔR2 are preferably 0.01 to 4, more preferably 0.05 to 0.5, and even more preferably 0.05 to 0.2, respectively.

The first shear creep ratio R1A (% / μm) is preferably 0.05 to 1.0, and more preferably 0.2 to 0.5. The second shear creep ratio R1B (% / μm) is preferably 0.01 to 0.3, and more preferably 0.05 to 0.2. The third shear creep ratio R2A (% / μm) is preferably 0.05 to 1.0, and more preferably 0.2 to 0.5. The fourth shear creep ratio R2B (% / μm) is preferably 0.01 to 0.3, and more preferably 0.05 to 0.2.

In the laminated body 100, the second shear creep rate (% / μm) is more preferably 0.1 or more and 0.2 or less. In this case, since the first pressure-sensitive adhesive layer 102 is a pressure-sensitive adhesive layer having not only excellent flexibility and durability but also appropriate hardness, it is possible to impart excellent surface hardness to the laminate 100. Specifically, as shown in Examples described later, when a load of 100 g is applied to the surface of the front plate 101 of the laminated body 100 using a pencil having a core hardness of 6B, the surface is subjected to a load of 100 g. The formed recess marks can be eliminated in less than one hour (hereinafter, such performance is also referred to as "excellent in" surface hardness ").

The gel fraction of the pressure-sensitive adhesive layer can be 40-90% and may be 50-80%. The gel fraction of the pressure-sensitive adhesive layer is measured by the method described in Examples below.

Further, in the laminated body 100, at least one of the first pressure-sensitive adhesive layer 102 and the second pressure-sensitive adhesive layer 104 preferably has a thickness of 20 μm or more and 50 μm or less.

Here, as a method for preparing the first pressure-sensitive adhesive composition and the second pressure-sensitive adhesive composition constituting the first pressure-sensitive adhesive reference layer and the second pressure-sensitive adhesive reference layer satisfying the relationship of the above formula (1), these are used. For example, a method of forming the pressure-sensitive adhesive composition A described later, changing the type of the monomer constituting the (meth) acrylic polymer A described later, adjusting the molecular weight of the (meth) acrylic polymer A, etc. Can be mentioned. Hereinafter, the pressure-sensitive adhesive composition A will be specifically described.

<Adhesive composition A>
Although the composition of the first pressure-sensitive adhesive layer 102 and the composition of the second pressure-sensitive adhesive layer 104 are different from each other, a pressure-sensitive adhesive composition containing a (meth) acrylic polymer in one form thereof (hereinafter referred to as “pressure-sensitive adhesive composition”). It can also be formed from). The pressure-sensitive adhesive composition A may be an active energy ray-curable type or a thermosetting type. As used herein, the term "(meth) acrylic polymer" refers to at least one selected from the group consisting of acrylic polymers and methacrylic polymers. The same applies to other terms with "(meta)". When both the first pressure-sensitive adhesive composition and the second pressure-sensitive adhesive composition contain a (meth) acrylic polymer, the (meth) acrylic polymer may be the same or different. Hereinafter, the (meth) acrylic polymer contained in the pressure-sensitive adhesive composition A is also referred to as “(meth) acrylic polymer A”.

(Active energy ray-curable pressure-sensitive adhesive composition)
When the pressure-sensitive adhesive composition A is an active energy ray-curable pressure-sensitive adhesive composition, the (meth) acrylic polymer A contained in the pressure-sensitive adhesive composition A has a structural unit derived from a monomer having a reactive functional group. Preferably, it is 1% by mass or less based on the total mass of the polymer. Examples of the reactive functional group include a hydroxyl group, a carboxyl group, an amino group, an amide group and an epoxy group. As a result, the flexibility of the pressure-sensitive adhesive layer is improved, and it tends to be easy to suppress the generation of bubbles in the pressure-sensitive adhesive layer at room temperature. In the (meth) acrylic polymer A, the structural unit derived from the monomer having a reactive functional group is more preferably 0.01% by mass based on the total mass of the polymer from the viewpoint of suppressing the generation of bubbles at the time of bending. More preferably, it does not have a structural unit derived from a monomer having a reactive functional group, and even more preferably it does not have a hydroxyl group, a carboxyl group, an amino group, an amide group and an epoxy group.

The (meth) acrylic polymer A can contain a structural unit derived from a (meth) acrylic monomer having a linear or branched chain-like alkyl group having 1 to 24 carbon atoms. The (meth) acrylic monomer having a linear or branched chain-shaped alkyl group having 1 or more and 24 or less carbon atoms may be, for example, a (meth) acrylic acid alkyl ester, and an example thereof is (meth). ) Butyl acrylate, methyl (meth) acrylate, ethyl (meth) acrylate, hexyl (meth) acrylate, octyl (meth) acrylate, lauryl (meth) acrylate, isooctyl (meth) acrylate, (meth) Examples thereof include isodecyl acrylate, 2-ethylhexyl (meth) acrylate, and isobornyl (meth) acrylate. The (meth) acrylic polymer A may be a polymer or a copolymer containing one or more of the above (meth) acrylic acid alkyl esters as monomers. The content of the (meth) acrylic polymer A in the pressure-sensitive adhesive composition A may be, for example, 50% by mass or more and 100% by mass or less, preferably 80% by mass or less, based on 100 parts by mass of the solid content of the pressure-sensitive adhesive composition A. It is by mass% or more and 99.5% by mass or less, and more preferably 90% by mass or more and 99% by mass or less.

The weight average molecular weight (Mw) of the (meth) acrylic polymer A may be, for example, 100,000 or more and 2 million or less, and preferably 500,000 or more and 1.5 million or less from the viewpoint of suppressing air bubbles at the time of bending. The weight average molecular weight in the present specification can be determined based on a standard polystyrene-equivalent value measured by a gel permeation chromatography (GPC) method, as described in the column of Examples described later.

The pressure-sensitive adhesive composition A may contain one or more (meth) acrylic polymers A. Further, the pressure-sensitive adhesive composition A may contain only the (meth) acrylic polymer A as a constituent component thereof, or may further contain a cross-linking agent. The cross-linking agent is a divalent or higher metal ion that forms a carboxylic acid metal salt with a carboxyl group; a polyamine compound that forms an amide bond with a carboxyl group; poly. Examples thereof include epoxy compounds or polyols that form an ester bond with a carboxyl group; polyisocyanate compounds that form an amide bond with a carboxyl group, and the like. Of these, polyisocyanate compounds are preferable. When the pressure-sensitive adhesive composition A contains a cross-linking agent, the content of the cross-linking agent may be, for example, 5 parts by mass or less, preferably 3 parts by mass or less, based on 100 parts by mass of the (meth) acrylic polymer A. It is preferably 1 part by mass or less, more preferably 0.5 part by mass or less. The pressure-sensitive adhesive composition A may not contain a cross-linking agent.

The active energy ray-curable pressure-sensitive adhesive composition has a property of being cured by being irradiated with active energy rays such as ultraviolet rays or electron beams, and has adhesiveness even before irradiation with active energy rays. This is a pressure-sensitive adhesive composition having the property of being able to adhere to an adherend such as, etc., and being cured by irradiation with active energy rays to adjust the adhesion force and the like. The active energy ray-curable pressure-sensitive adhesive composition is preferably an ultraviolet-curable type.

When the pressure-sensitive adhesive composition A is an active energy ray-curable pressure-sensitive adhesive composition, the pressure-sensitive adhesive composition A can further contain an active energy ray-polymerizable compound, a photopolymerization initiator, a photosensitizer, and the like. ..

The active energy ray-polymerizable compound is, for example, a (meth) acrylate monomer having at least one (meth) acryloyloxy group in the molecule; obtained by reacting two or more kinds of functional group-containing compounds, and at least in the molecule. Examples thereof include (meth) acrylic compounds such as (meth) acryloyloxy group-containing compounds such as (meth) acrylate oligomers having two (meth) acryloyloxy groups. The pressure-sensitive adhesive composition A can contain an active energy ray-polymerizable compound in an amount of 0.1 part by mass or more and 10 parts by mass or less with respect to 100 parts by mass of the solid content of the pressure-sensitive adhesive composition A.

Examples of the photopolymerization initiator include benzophenone, benzyl dimethyl ketal, 1-hydroxycyclohexyl ketone and the like. When the pressure-sensitive adhesive composition A contains a photopolymerization initiator, it can contain one kind or two or more kinds. When the pressure-sensitive adhesive composition A contains a photopolymerization initiator, the total content thereof may be, for example, 0.01 part by mass or more and 1.0 part by mass or less with respect to 100 parts by mass of the solid content of the pressure-sensitive adhesive composition A. ..

The pressure-sensitive adhesive composition A contains fine particles, beads (resin beads, glass beads, etc.), glass fibers, resins other than the base polymer, a pressure-sensitive adhesive, and a filler (metal powder or other inorganic substances) for imparting light scattering properties. Additives such as powders), antioxidants, UV absorbers, dyes, pigments, colorants, antifoaming agents, corrosion inhibitors and the like can be included. The pressure-sensitive adhesive composition A preferably does not contain an organic solvent from the viewpoint of preventing the problem of deterioration of durability due to the residual solvent.

When the pressure-sensitive adhesive layer is formed from the pressure-sensitive adhesive composition A, the pressure-sensitive adhesive layer can be formed by applying the pressure-sensitive adhesive composition A on a substrate. When the active energy ray-curable pressure-sensitive adhesive composition is used, the formed pressure-sensitive adhesive layer can be irradiated with active energy rays to obtain a cured product having a desired degree of curing.

(Thermosetting adhesive composition)
When the pressure-sensitive adhesive composition A is a heat-curable pressure-sensitive adhesive composition, the (meth) acrylic polymer A is a (meth) acrylic having an alkyl group having 2 to 20 carbon atoms as a monomer unit constituting the polymer. It is preferable to contain an acid alkyl ester and a monomer having a reactive functional group in the molecule (reactive functional group-containing monomer). When the pressure-sensitive adhesive composition A is a thermosetting pressure-sensitive adhesive composition, it preferably further contains a heat-crosslinking agent.

The (meth) acrylic polymer A can exhibit preferable tackiness by containing a (meth) acrylic acid alkyl ester having an alkyl group having 2 to 20 carbon atoms as a monomer unit constituting the polymer. can. The (meth) acrylic acid alkyl ester having an alkyl group having 2 to 20 carbon atoms is, for example, a homopolymer having a glass transition temperature (Tg) of −40 ° C. or lower (hereinafter, may be referred to as “low Tg alkyl acrylate”). It is preferable to include it. By containing the low Tg alkyl acrylate as a constituent monomer unit, the flexibility of the pressure-sensitive adhesive layer is improved, and the generation of bubbles at the time of bending can be more easily suppressed. The glass transition temperature (Tg) of the (meth) acrylic polymer A can be determined by using a conventionally known method such as differential thermal analysis (DTA).

Examples of the low Tg alkyl acrylate include n-butyl acrylate (Tg-54 ° C.), n-octyl acrylate (Tg-65 ° C.), isooctyl acrylate (Tg-58 ° C.), and 2-ethylhexyl acrylate (Tg). -70 ° C), isononyl acrylate (Tg-58 ° C), isodecyl acrylate (Tg-60 ° C), isodecyl methacrylate (Tg-41 ° C), n-lauryl methacrylate (Tg-65 ° C), tridecyl acrylate (Tg-55 ° C.), tridecyl methacrylate (-40 ° C.) and the like are preferably mentioned. Among them, as the low Tg alkyl acrylate, the Tg of the homopolymer is more preferably −45 ° C. or lower, and particularly preferably −50 ° C. or lower. Specifically, n-butyl acrylate and 2-ethylhexyl acrylate are particularly preferable. These may be used alone or in combination of two or more.

The (meth) acrylic polymer A preferably contains a low Tg alkyl acrylate as a lower limit of 85% by mass or more, more preferably 90% by mass or more, as a monomer unit constituting the polymer. It is more preferable to contain it in an amount of mass% or more.

Further, the (meth) acrylic polymer A preferably contains the above-mentioned low Tg alkyl acrylate as a monomer unit constituting the polymer in an upper limit of 99.9% by mass or less, and preferably 99.5% by mass or less. Is more preferable, and it is further preferable that the content is 99% by mass or less. By containing 99.9% by mass or less of the low Tg alkyl acrylate, a suitable amount of other monomer components (particularly reactive functional group-containing monomer) can be introduced into the (meth) acrylic polymer A.

The (meth) acrylic polymer A is a monomer having a glass transition temperature (Tg) of more than 0 ° C. as a homopolymer (hereinafter, may be referred to as “hard monomer”) from the viewpoint of further exerting the effect of the present invention. It is preferable to reduce the content as much as possible. Specifically, the (meth) acrylic polymer A preferably has a hard monomer content of 15% by mass or less as an upper limit as a monomer unit constituting the polymer, and is preferably 10% by mass or less. More preferably, it is more preferably 5% by mass or less. This hard monomer also includes a reactive functional group-containing monomer described later.

Examples of the hard monomer include methyl acrylate (Tg10 ° C.), methyl methacrylate (Tg105 ° C.), ethyl methacrylate (Tg65 ° C.), n-butyl methacrylate (Tg20 ° C.), isobutyl methacrylate (Tg48 ° C.), and the like. T-butyl methacrylate (Tg 107 ° C), n-stearyl acrylate (Tg 30 ° C), n-stearyl methacrylate (Tg 38 ° C), cyclohexyl acrylate (Tg 15 ° C), cyclohexyl methacrylate (Tg 66 ° C), phenoxyethyl acrylate (Tg 5 ° C), phenoxyethyl methacrylate (Tg 54 ° C), benzyl methacrylate (Tg 54 ° C), isobornyl acrylate (Tg 94 ° C), isobornyl methacrylate (Tg 180 ° C), acryloylmorpholin (Tg 145 ° C), adamantyl acrylate (Tg115 ° C). ℃), adamantyl methacrylate (Tg141 ℃), acrylic acid (Tg105 ℃), dimethylacrylamide (Tg89 ℃), acrylamide (Tg165 ℃) and other acrylic monomers, vinyl acetate (Tg32 ℃), styrene (Tg80 ℃) and the like. Can be mentioned.

The (meth) acrylic polymer A contains a reactive functional group-containing monomer as a monomer unit constituting the polymer, and thus the heat described later is passed through the reactive functional group derived from the reactive functional group-containing monomer. Reacts with cross-linking agents. As a result, a crosslinked structure (three-dimensional network structure) is formed as a whole, and a pressure-sensitive adhesive having a desired cohesive force can be obtained.

Examples of the reactive functional group-containing monomer contained in the (meth) acrylic polymer A as a monomer unit constituting the polymer include a monomer having a hydroxyl group in the molecule (monomer containing a hydroxyl group) and a monomer having a carboxy group in the molecule. (Carboxy group-containing monomer), a monomer having an amino group in the molecule (amino group-containing monomer), and the like are preferably mentioned. Of these, hydroxyl group-containing monomers are particularly preferable because many of them have a glass transition temperature (Tg) of 0 ° C. or lower.

Examples of the hydroxyl group-containing monomer include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, and (meth). ) (Meta) Acrylic acid hydroxyalkyl esters such as 3-hydroxybutyl acrylate and 4-hydroxybutyl (meth) acrylic acid can be mentioned. Among them, 2-hydroxyethyl acrylate is obtained from the viewpoints of glass transition temperature (Tg), reactivity of the hydroxyl group in the obtained (meth) acrylic polymer A with a thermal cross-linking agent, and copolymerizability with other monomers. , 2-Hydroxypropyl acrylate, 3-hydroxypropyl acrylate, and 4-hydroxybutyl acrylate are preferred. These may be used alone or in combination of two or more.

Examples of the carboxy group-containing monomer include ethylenically unsaturated carboxylic acids such as acrylic acid, methacrylic acid, crotonic acid, maleic acid, itaconic acid, and citraconic acid. These may be used alone or in combination of two or more.

Examples of the amino group-containing monomer include aminoethyl (meth) acrylate and n-butylaminoethyl (meth) acrylate. These may be used alone or in combination of two or more.

The (meth) acrylic polymer A preferably contains a reactive functional group-containing monomer as a lower limit value of 0.1% by mass or more, particularly 0.5% by mass or more, as a monomer unit constituting the polymer. It is preferable that the content is 1% by mass or more. The (meth) acrylic polymer A preferably contains the above-mentioned reactive functional group-containing monomer as an upper limit of 10% by mass or less, particularly preferably 8% by mass or less, and further contains 5% by mass or less. Is preferable. This tends to make it easier to suppress the generation of bubbles during bending.

The (meth) acrylic polymer A may not contain a carboxy group-containing monomer, particularly acrylic acid, which is also a hard monomer, as a monomer unit constituting the polymer. Since the carboxy group is an acid component, a transparent conductive film such as tin-doped indium oxide (ITO), a metal film, or a metal that causes a problem due to the acid on the object to which the pressure-sensitive adhesive is applied because the carboxy group-containing monomer is not contained. Even when a mesh or the like is present, it is possible to suppress those defects (corrosion, change in resistance value, etc.) due to acid.

If desired, the (meth) acrylic polymer A may contain other monomers as the monomer unit constituting the polymer. As the other monomer, a monomer containing no reactive functional group is preferable so as not to interfere with the action of the reactive functional group-containing monomer. Examples of the other monomers include (meth) acrylic acid alkoxyalkyl esters such as methoxyethyl (meth) acrylate and ethoxyethyl (meth) acrylate, as well as a glass transition temperature (Tg) of -40 as a homopolymer. Examples thereof include a monomer having a temperature of more than 0 ° C. and a temperature of 0 ° C. or lower (hereinafter, may be referred to as “medium Tg alkyl acrylate”). Examples of the medium Tg alkyl acrylate include ethyl acrylate (Tg-20 ° C.), isobutyl acrylate (Tg-26 ° C.), 2-ethylhexyl methacrylate (Tg-10 ° C.), and n-lauryl acrylate (Tg-23 ° C.). ° C.), isostearyl acrylate (Tg-18 ° C.) and the like. These may be used alone or in combination of two or more.

The polymerization mode of the (meth) acrylic polymer A may be a random copolymer or a block copolymer.

The lower limit of the weight average molecular weight of the (meth) acrylic polymer A is preferably 200,000 or more, particularly preferably 300,000 or more, and further preferably 400,000 or more. When the lower limit of the weight average molecular weight of the (meth) acrylic polymer A is equal to or higher than the above, problems such as seepage of the adhesive are suppressed. The weight average molecular weight in the present specification can be determined based on a standard polystyrene-equivalent value measured by a gel permeation chromatography (GPC) method, as described in the column of Examples described later.

The upper limit of the weight average molecular weight of the (meth) acrylic polymer A is preferably 2 million or less, particularly preferably 1.5 million or less, and further preferably 1.3 million or less. When the upper limit of the weight average molecular weight of the (meth) acrylic acid ester polymer (A) is not more than the above, the flexibility of the pressure-sensitive adhesive layer can be ensured, and the effect of the present invention can be easily exerted. ..

In the pressure-sensitive adhesive composition A, one type of (meth) acrylic polymer A may be used alone, or two or more types may be used in combination.

When the pressure-sensitive adhesive composition A containing the heat-crosslinking agent is heated, the heat-crosslinking agent crosslinks the (meth) acrylic polymer A to form a three-dimensional network structure. As a result, the cohesive force can be improved while ensuring the flexibility of the pressure-sensitive adhesive, and when applied to the laminated body, it is possible to obtain a hardness capable of improving the surface hardness of the laminated body.

The thermal cross-linking agent may be any one that reacts with the reactive group of the (meth) acrylic polymer A. For example, an isocyanate-based cross-linking agent, an epoxy-based cross-linking agent, an amine-based cross-linking agent, a melamine-based cross-linking agent, and the like. Examples thereof include an aziridine-based cross-linking agent, a hydrazine-based cross-linking agent, an aldehyde-based cross-linking agent, an oxazoline-based cross-linking agent, a metal alkoxide-based cross-linking agent, a metal chelate-based cross-linking agent, a metal salt-based cross-linking agent, and an ammonium salt-based cross-linking agent. Among the above, when the reactive group of the (meth) acrylic polymer A is a hydroxyl group, it is preferable to use an isocyanate-based cross-linking agent having excellent reactivity with the hydroxyl group. The thermal cross-linking agent may be used alone or in combination of two or more.

The isocyanate-based cross-linking agent contains at least a polyisocyanate compound. Examples of the polyisocyanate compound include aromatic polyisocyanates such as tolylene diisocyanate, diphenylmethane diisocyanate, and xylylene diisocyanate, aliphatic polyisocyanates such as hexamethylene diisocyanate, isophorone diisocyanates, and alicyclic polyisocyanates such as hydrogenated diphenylmethane diisocyanate. , And their biurets, isocyanurates, and adducts, which are reactants with low molecular weight active hydrogen-containing compounds such as ethylene glycol, propylene glycol, neopentyl glycol, trimethylolpropane, and castor oil. Of these, trimethylolpropane-modified aromatic polyisocyanates, particularly trimethylolpropane-modified tolylene diisocyanate and trimethylolpropane-modified xylylene diisocyanate, are preferable from the viewpoint of reactivity with hydroxyl groups.

Examples of the epoxy-based cross-linking agent include 1,3-bis (N, N-diglycidylaminomethyl) cyclohexane, N, N, N', N'-tetraglycidyl-m-xylylene diamine, and ethylene glycol diglycidyl ether. , 1,6-Hexanediol diglycidyl ether, trimethylpropan diglycidyl ether, diglycidyl aniline, diglycidyl amine and the like.

The content of the heat-crosslinking agent in the pressure-sensitive adhesive composition A is preferably 0.01% by mass or more, preferably 0.05% by mass or more, based on 100% by mass of the (meth) acrylic polymer A. More preferably, it is 0.1% by mass or more. Further, the content is preferably 1% by mass or less, more preferably 0.8% by mass or less, and further preferably 0.5% by mass or less. When the content of the thermal cross-linking agent is in the above range, it is possible to more easily obtain an appropriate hardness by improving the cohesive force.

The pressure-sensitive adhesive composition A preferably contains the above-mentioned silane coupling agent. As a result, the obtained pressure-sensitive adhesive layer has improved adhesion to each member in the laminated body as an adherend, and has more excellent durability against bending.

The silane coupling (SC) agent is preferably an organosilicon compound having at least one alkoxysilyl group in the molecule, which has good compatibility with the (meth) acrylic polymer A and has light transmittance. ..

Examples of the silane coupling agent include polymerizable unsaturated group-containing silicon compounds such as vinyltrimethoxysilane, vinyltriethoxysilane, and methacrypropyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, and 2- (3). , 4-Epoxycyclohexyl) Silicon compounds having an epoxy structure such as ethyltrimethoxysilane, mercapto group-containing silicon compounds such as 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 3-mercaptopropyldimethoxymethylsilane, Amino group-containing silicon compounds such as 3-aminopropyltrimethoxysilane, N- (2-aminoethyl) -3-aminopropyltrimethoxysilane, N- (2-aminoethyl) -3-aminopropylmethyldimethoxysilane, 3 -Chloropropyltrimethoxysilane, 3-isocyanuppropyltriethoxysilane, or at least one of them and an alkyl group-containing silicon compound such as methyltriethoxysilane, ethyltriethoxysilane, methyltrimethoxysilane, ethyltrimethoxysilane. Examples thereof include condensates. These may be used individually by 1 type, and may be used in combination of 2 or more type.

The content of the silane coupling agent in the pressure-sensitive adhesive composition A is preferably 0.01% by mass or more, preferably 0.05% by mass or more, based on 100% by mass of the (meth) acrylic polymer A. Is more preferable, and 0.1% by mass or more is further preferable. Further, the content is preferably 1% by mass or less, more preferably 0.5% by mass or less, and further preferably 0.3% by mass or less. When the content of the silane coupling agent is in the above range, the adhesion to each member in the laminated body can be further improved.

The various additives described above can be added to the pressure-sensitive adhesive composition A, if desired. In the present specification, the polymerization solvent and the diluting solvent are not included in the additives constituting the pressure-sensitive adhesive composition A.

The (meth) acrylic polymer A can be produced by polymerizing a mixture of monomers constituting the polymer by a usual radical polymerization method. The polymerization of the (meth) acrylic polymer A is preferably carried out by a solution polymerization method using a polymerization initiator, if desired. Examples of the polymerization solvent include ethyl acetate, n-butyl acetate, isobutyl acetate, toluene, acetone, hexane, methyl ethyl ketone and the like, and two or more of them may be used in combination.

Examples of the polymerization initiator include azo compounds and organic peroxides, and two or more of them may be used in combination. Examples of the azo compound include 2,2'-azobisisobutyronitrile, 2,2'-azobis (2-methylbutyronitrile), 1,1'-azobis (cyclohexane1-carbonitrile), and 2 , 2'-azobis (2,4-dimethylvaleronitrile), 2,2'-azobis (2,4-dimethyl-4-methoxyvaleronitrile), dimethyl 2,2'-azobis (2-methylpropionate) , 4,4'-azobis (4-cyanovaleric acid), 2,2'-azobis (2-hydroxymethylpropionitrile), 2,2'-azobis [2- (2-imidazolin-2-yl)) Propane] and the like.

Examples of the organic peroxide include benzoyl peroxide, t-butylperbenzoate, cumenehydroperoxide, diisopropylperoxydicarbonate, di-n-propylperoxydicarbonate, and di (2-ethoxyethyl) peroxy. Examples thereof include dicarbonate, t-butylperoxyneodecanoate, t-butylperoxyvivarate, (3,5,5-trimethylhexanoyl) peroxide, dipropionyl peroxide, diacetyl peroxide and the like.

In the above polymerization step, the weight average molecular weight of the obtained polymer can be adjusted by adding a chain transfer agent such as 2-mercaptoethanol.

Once the (meth) acrylic polymer A is obtained, a thermal cross-linking agent, a silane coupling agent and, if desired, an additive and a diluting solvent are added to the solution of the (meth) acrylic polymer A and mixed thoroughly. A solvent-diluted pressure-sensitive adhesive composition A (coating solution) can be obtained. The pressure-sensitive adhesive composition A can be produced by a known method, for example, by collectively mixing each component using a mixer or the like. Further, the first pressure-sensitive adhesive composition and the second pressure-sensitive adhesive composition can be prepared from the pressure-sensitive adhesive composition A thus obtained.

If any of the above components is used in solid form, or if precipitation occurs when mixed with other components in an undiluted state, the component may be dissolved alone in a diluting solvent in advance. It may be diluted and then mixed with other ingredients.

Examples of the diluting solvent include aliphatic hydrocarbons such as hexane, heptane and cyclohexane, aromatic hydrocarbons such as toluene and xylene, halogenated hydrocarbons such as methylene chloride and ethylene chloride, methanol, ethanol, propanol and butanol. Alcohols such as 1-methoxy-2-propanol, ketones such as acetone, methyl ethyl ketone, 2-pentanone, isophorone and cyclohexanone, esters such as ethyl acetate and butyl acetate, and cellosolve solvents such as ethyl cellosolve are used.

The concentration and viscosity of the pressure-sensitive adhesive composition A (coating solution) prepared in this manner may be any range as long as it can be coated, and is not particularly limited and can be appropriately selected depending on the situation. For example, the concentration of the pressure-sensitive adhesive composition A can be adjusted to be 10 to 60% by mass in the solution. When obtaining the coating solution, the addition of a diluting solvent or the like is not a necessary condition, and if the pressure-sensitive adhesive composition A has a coatable viscosity or the like, the diluting solvent may not be added. In this case, the pressure-sensitive adhesive composition A becomes a coating solution using the polymerization solvent of the (meth) acrylic polymer A as it is as a diluting solvent.

The pressure-sensitive adhesive layer can be obtained by cross-linking the pressure-sensitive adhesive composition A. Crosslinking of the pressure-sensitive adhesive composition A can be performed by heat treatment. The heat treatment can also serve as a drying treatment for volatilizing the diluting solvent or the like from the coating film of the pressure-sensitive adhesive composition A applied to the desired object.

The heating temperature in the heat treatment is preferably 50 to 150 ° C, more preferably 70 to 120 ° C. The heating time in the heat treatment is preferably 10 seconds to 10 minutes, more preferably 50 seconds to 2 minutes.

After the heat treatment, if necessary, a curing period of about 1 to 2 weeks can be provided at room temperature (for example, 23 ° C., 50% RH). If this curing period is required, an adhesive layer can be formed after the curing period has elapsed. When the curing period is not required, the pressure-sensitive adhesive layer can be formed after the above-mentioned heat treatment is completed.

By the above heat treatment (and curing), the (meth) acrylic polymer A is sufficiently cross-linked via the cross-linking agent to form a cross-linked structure, whereby the pressure-sensitive adhesive layers (first pressure-sensitive adhesive layer 102 and the second pressure-sensitive adhesive layer 102 and the second) are formed. The pressure-sensitive adhesive layer 104) can be obtained.

<Adhesive sheet>
The pressure-sensitive adhesive sheet can include a pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition A. The pressure-sensitive adhesive layer can be formed by applying the pressure-sensitive adhesive composition A onto a substrate. When an active energy ray-curable pressure-sensitive adhesive composition is used as the pressure-sensitive adhesive composition A, the formed pressure-sensitive adhesive layer can be irradiated with active energy rays to obtain a cured product having a desired degree of curing. When a thermosetting pressure-sensitive adhesive composition is used as the pressure-sensitive adhesive composition, the formed pressure-sensitive adhesive layer can be heat-treated (and cured) to obtain a cured product having a desired degree of curing.

The base material may be a release film that has been subjected to a mold release treatment. The pressure-sensitive adhesive sheet can be produced by applying the pressure-sensitive adhesive composition A on a release film to form a pressure-sensitive adhesive layer in the form of a sheet, and then adhering another release film on the pressure-sensitive adhesive layer. can.

As a method of applying the coating liquid of the pressure-sensitive adhesive composition A, for example, a bar coating method, a knife coating method, a roll coating method, a blade coating method, a die coating method, a gravure coating method and the like can be used.

[Front plate]
The material and thickness of the front plate 101 are not limited as long as it is a plate-like body capable of transmitting light, and the front plate 101 may be composed of only one layer or may be composed of two or more layers. Examples thereof include a resin plate-like body (for example, a resin plate, a resin sheet, a resin film, etc.), a glass plate-like body (for example, a glass plate, a glass film, etc.), and a touch sensor panel described later. The front plate can constitute the outermost surface of the display device.

The thickness of the front plate 101 may be, for example, 10 μm or more and 1000 μm or less, preferably 20 μm or more and 500 μm or less, and more preferably 30 μm or more and 300 μm or less. In the present invention, the thickness of each layer can be measured according to the thickness measuring method described in Examples described later.

When the front plate 101 is a resin plate-like body, the resin plate-like body is not limited as long as it can transmit light. Examples of the resin constituting the resin plate such as a resin film include triacetyl cellulose, acetyl cellulose butyrate, ethylene-vinyl acetate copolymer, propionyl cellulose, butyryl cellulose, acetyl propionyl cellulose, polyester, and polystyrene. Polyamide, polyetherimide, poly (meth) acrylic, polyimide, polyether sulfone, polysulfone, polyethylene, polypropylene, polymethylpentene, polyvinyl chloride, polyvinylidene chloride, polyvinyl alcohol, polyvinyl acetal, polyether ketone, polyether ether ketone , Polyether sulfone, polymethyl methacrylate, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polycarbonate, polyamideimide and the like. These polymers can be used alone or in admixture of two or more. From the viewpoint of improving strength and transparency, a resin film formed of a polymer such as polyimide, polyamide, or polyamideimide is preferable.

From the viewpoint of hardness, the front plate 101 is preferably a film in which a hard coat layer is provided on at least one surface of the base film. As the base film, a film made of the above resin can be used. The hard coat layer may be formed on one surface of the base film or may be formed on both surfaces. By providing the hard coat layer, a resin film having improved hardness and scratchability can be obtained. The hard coat layer is, for example, a cured layer of an ultraviolet curable resin. Examples of the ultraviolet curable resin include acrylic resin, silicone resin, polyester resin, urethane resin, amide resin, epoxy resin and the like. The hard coat layer may contain additives to improve strength. Additives are not limited and include inorganic fine particles, organic fine particles, or mixtures thereof.

When the front plate 101 is a glass plate, tempered glass for a display is preferably used as the glass plate. The thickness of the glass plate may be, for example, 10 μm or more and 1000 μm or less, and may be 50 μm or more and 500 μm or less. By using the glass plate, the front plate 101 having excellent mechanical strength and surface hardness can be constructed.

When the laminate 100 is used in a display device, the front plate 101 not only has a function of protecting the front surface (screen) of the display device (function as a window film), but also has a function as a touch sensor and a blue light cut function. , It may have a viewing angle adjusting function or the like.

[First adhesive layer]
The first pressure-sensitive adhesive layer 102 is a layer that is interposed between the front plate 101 and the polarizer layer 103 and adheres them to each other. It may be a treated layer. The first pressure-sensitive adhesive layer 102 can be a pressure-sensitive adhesive layer arranged at a position closest to the front surface plate 101 among the pressure-sensitive adhesive layers constituting the laminated body 100. Here, the "adhesive" as used herein is also referred to as a pressure-sensitive adhesive. Further, in the present specification, the “adhesive” refers to an adhesive other than an adhesive (pressure sensitive adhesive), and is clearly distinguished from the adhesive. The first pressure-sensitive adhesive layer 102 may be one layer or may be composed of two or more layers, but is preferably one layer.

The first pressure-sensitive adhesive layer 102 is formed by using the first pressure-sensitive adhesive composition as described above. The first pressure-sensitive adhesive composition can be formed by using the pressure-sensitive adhesive composition A as described above. The first pressure-sensitive adhesive layer 102 uses the above-mentioned first pressure-sensitive adhesive composition to form a first pressure-sensitive adhesive reference layer so that the thickness of the first pressure-sensitive adhesive reference layer and the thickness of the second pressure-sensitive adhesive reference layer are the same. When the second pressure-sensitive adhesive reference layer is formed by forming and using the second pressure-sensitive adhesive composition described later, the first pressure-sensitive adhesive reference layer and the second pressure-sensitive adhesive reference layer are represented by the formula (ΔR1 ≦ ΔR2). Satisfy the relationship of 1). The thickness of the first pressure-sensitive adhesive reference layer and the thickness of the second pressure-sensitive adhesive reference layer can be, for example, 200 μm. It is preferable that the first pressure-sensitive adhesive reference layer and the second pressure-sensitive adhesive reference layer satisfy the relationship of the formula (2) represented by ΔR1 <ΔR2. The first pressure-sensitive adhesive composition is not limited to the pressure-sensitive adhesive composition A as long as it satisfies the above formula (1) in relation to the second pressure-sensitive adhesive composition, and can be formed directly from any pressure-sensitive adhesive composition. Alternatively, it can be formed by using a pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer formed by using any pressure-sensitive adhesive composition. However, the first pressure-sensitive adhesive composition is preferably formed from the above-mentioned pressure-sensitive adhesive composition A, or is formed by using a pressure-sensitive adhesive sheet formed by applying the above-mentioned pressure-sensitive adhesive composition A on a substrate. Is also preferable.

That is, the first pressure-sensitive adhesive layer 102 includes the composition and compounding components of the first pressure-sensitive adhesive composition, the type of the first pressure-sensitive adhesive composition (active energy ray-curable type, heat-curable type, etc.), and the first pressure-sensitive adhesive. Regarding the additives that can be blended in the composition, the method for producing the first pressure-sensitive adhesive layer, the thickness of the first pressure-sensitive adhesive layer, and the like, the above-mentioned [Adhesive layer (first pressure-sensitive adhesive formed by using the first pressure-sensitive adhesive composition) The layer and the second pressure-sensitive adhesive layer formed by using the second pressure-sensitive adhesive composition)] can be as described in the column.

In the laminated body 100, at least one of the first pressure-sensitive adhesive layer 102 and the second pressure-sensitive adhesive layer 104 preferably has a thickness of 20 μm or more and 50 μm or less. Therefore, the thickness of the first pressure-sensitive adhesive layer 102 can be, for example, 3 μm or more and 100 μm or less, preferably 5 μm or more and 50 μm or less, and may be 20 μm or more. The thickness of the first pressure-sensitive adhesive layer 102 is most preferably 20 μm or more and 50 μm or less.

[Polarizer layer]
Examples of the polarizer layer 103 include a stretched film or a stretched layer on which a dichroic dye is adsorbed, a layer obtained by applying and curing a composition containing a dichroic dye and a polymerizable compound, and the like. As the dichroic dye, specifically, iodine or a dichroic organic dye is used. For dichroic organic dyes, C.I. I. Included are dichroic direct dyes made of disuazo compounds such as DIRECT RED 39 and dichroic direct dyes made of compounds such as trisazo and tetrakisazo.

The polarizer layer formed by applying and curing a composition containing a dichroic dye and a polymerizable compound includes a composition containing a dichroic dye having a liquid crystal property or a composition containing a dichroic dye and a polymerizable liquid crystal. Examples thereof include a polarizer layer containing a cured product of a polymerizable liquid crystal compound, such as a layer obtained by applying and curing an object. A polarizer layer obtained by applying and curing a composition containing a dichroic dye and a polymerizable compound is preferable because there is no limitation in the bending direction as compared with a stretched film or a stretched layer on which a dichroic dye is adsorbed.

In the laminated body 100, the polarizer layer 103 can function as a circular polarizing plate, for example, by combining with a retardation layer described later.

<Polarizer layer that is a stretched film or stretched layer>
The polarizer layer, which is a stretched film on which a dichroic dye is adsorbed, is usually bicolorized by a step of uniaxially stretching the polyvinyl alcohol-based resin film and dyeing the polyvinyl alcohol-based resin film with the dichroic dye. It can be produced through a step of adsorbing a dye, a step of treating a polyvinyl alcohol-based resin film on which a dichroic dye is adsorbed with an aqueous boric acid solution, and a step of washing with water after the treatment with the aqueous boric acid solution. The thickness of the polarizer layer 103 is, for example, 2 μm or more and 40 μm or less. The thickness of the polarizer layer 103 may be 5 μm or more, 20 μm or less, further 15 μm or less, and further 10 μm or less.

The polyvinyl alcohol-based resin is obtained by saponifying a polyvinyl acetate-based resin. As the polyvinyl acetate-based resin, in addition to polyvinyl acetate which is a homopolymer of vinyl acetate, a copolymer of vinyl acetate and another monomer copolymerizable therewith is used. Examples of other monomers copolymerizable with vinyl acetate include unsaturated carboxylic acids, olefins, vinyl ethers, unsaturated sulfonic acids, and (meth) acrylamides having an ammonium group.

The degree of saponification of the polyvinyl alcohol-based resin is usually about 85 mol% or more and 100 mol% or less, preferably 98 mol% or more. The polyvinyl alcohol-based resin may be modified, and for example, polyvinyl formal or polyvinyl acetal modified with aldehydes can be used. The degree of polymerization of the polyvinyl alcohol-based resin is usually 1000 or more and 10000 or less, preferably 1500 or more and 5000 or less.

The polarizer layer, which is a stretched layer on which a dichroic dye is adsorbed, is usually a step of applying a coating liquid containing the above-mentioned polyvinyl alcohol-based resin on a base film, a step of uniaxially stretching the obtained laminated film, and uniaxial. A step of dyeing a polyvinyl alcohol-based resin layer of a stretched laminated film with a dichroic dye to adsorb the dichroic dye to form a polarizer layer, and a film on which the dichroic dye is adsorbed is boric acid. It can be produced through a step of treating with an aqueous solution and a step of washing with water after treatment with an aqueous boric acid solution. In the polarizing layer, which is a stretched layer on which the dichroic dye is adsorbed, the base film may be peeled off from the polarizing layer, if necessary. The material and thickness of the base film may be the same as the material and thickness of the thermoplastic resin film described later.

The stretched film or the polarizer layer, which is a stretched layer, may be incorporated into the laminate in a form in which a thermoplastic resin film is bonded to one side or both sides thereof. This thermoplastic resin film can function as a protective film for the polarizer layer 103 or a retardation film. The thermoplastic resin film is, for example, a polyolefin resin such as a chain polyolefin resin (polypropylene resin, etc.), a cyclic polyolefin resin (norbornen resin, etc.); a cellulose resin such as triacetyl cellulose; polyethylene terephthalate, polyethylene na. It can be a film composed of a polyester resin such as phthalate or polybutylene terephthalate; a polycarbonate resin; a (meth) acrylic resin; or a mixture thereof.

The thermoplastic resin film may or may not have a phase difference. From the viewpoint of thinning, the thickness of the thermoplastic resin film is usually 300 μm or less, preferably 200 μm or less, more preferably 100 μm or less, still more preferably 80 μm or less, still more preferably 60 μm or less. be. The thickness of the thermoplastic resin film is usually 5 μm or more, preferably 20 μm or more. The thermoplastic resin film can be attached to the polarizer layer 103 by using, for example, an adhesive layer.

<Polarizer layer formed by applying and curing a composition containing a dichroic dye and a polymerizable compound>
The polarizer layer formed by applying and curing a composition containing a dichroic dye and a polymerizable compound includes a composition containing a dichroic dye having a liquid crystal property or a dichroic dye and a polymerizable liquid crystal. Examples thereof include a polarizer layer containing a cured product of a polymerizable liquid crystal compound, such as a layer obtained by applying a composition containing the above to a substrate film and curing the composition.

In the polarizer layer formed by applying and curing the composition containing the dichroic dye and the polymerizable compound, the base film may be peeled off from the polarizer layer, if necessary. The material and thickness of the base film may be the same as the material and thickness of the thermoplastic resin film described above. The polarizer layer may include an alignment film. The alignment film may be peeled off.

The polarizer layer formed by applying and curing a composition containing a dichroic dye and a polymerizable compound may be incorporated into an optical laminate in the form of a thermoplastic resin film bonded to one or both sides thereof. .. As the thermoplastic resin film, the same one as the thermoplastic resin film that can be used for the stretched film or the polarizer layer that is the stretched layer can be used. The thermoplastic resin film can be bonded to the polarizer layer by using, for example, an adhesive layer.

The polarizer layer formed by applying and curing a composition containing a dichroic dye and a polymerizable compound may have an overcoat (OC) layer formed as a protective layer on one side or both sides thereof. Examples of the OC layer include a cured layer such as a photocurable resin or a water-soluble polymer. Examples of the photocurable resin include (meth) acrylic resin, urethane resin, (meth) acrylic urethane resin, epoxy resin, silicone resin and the like. Examples of the water-soluble polymer include poly (meth) acrylamide-based polymers; polyvinyl alcohol, ethylene-vinyl alcohol copolymer, ethylene-vinyl acetate copolymer, (meth) acrylic acid or its anhydride-vinyl alcohol co-weight. Examples thereof include vinyl alcohol-based polymers such as coalescence; carboxyvinyl-based polymers; polyvinylpyrrolidone; starches; sodium alginate; polyethylene oxide-based polymers. The thickness of the OC layer is preferably 20 μm or less, more preferably 15 μm or less, further preferably 10 μm or less, 5 μm or less, and 0.05 μm or more. It may be 0.5 μm or more.

The thickness of the polarizer layer obtained by applying and curing the composition containing the dichroic dye and the polymerizable compound is usually 10 μm or less, preferably 0.5 μm or more and 8 μm or less, and more preferably 1 μm or more and 5 μm or less. Is.

[Second adhesive layer]
The second pressure-sensitive adhesive layer 104 is a pressure-sensitive adhesive layer arranged between the polarizer layer 103 and the back plate 105. The second pressure-sensitive adhesive layer can be a pressure-sensitive adhesive layer arranged at a position closest to the back plate 105 among the pressure-sensitive adhesive layers constituting the laminated body 100. The second pressure-sensitive adhesive layer 104 may be one layer or may be composed of two or more layers, but is preferably one layer.

The second pressure-sensitive adhesive layer 104 is formed by using the second pressure-sensitive adhesive composition as described above. The second pressure-sensitive adhesive composition can be formed by using the pressure-sensitive adhesive composition A as described above. The second pressure-sensitive adhesive layer 104 uses the above-mentioned second pressure-sensitive adhesive composition so that the thickness of the first pressure-sensitive adhesive reference layer and the thickness of the second pressure-sensitive adhesive reference layer are the same. When the first pressure-sensitive adhesive reference layer is formed using the above-mentioned first pressure-sensitive adhesive composition, the first pressure-sensitive adhesive reference layer and the second pressure-sensitive adhesive reference layer are represented by the formula ΔR1 ≦ ΔR2. Satisfy the relationship of (1). The thickness of the first pressure-sensitive adhesive reference layer and the thickness of the second pressure-sensitive adhesive reference layer can be, for example, 200 μm. It is preferable that the first pressure-sensitive adhesive reference layer and the second pressure-sensitive adhesive reference layer satisfy the relationship of the formula (2) represented by ΔR1 <ΔR2. The second pressure-sensitive adhesive composition is not limited to the pressure-sensitive adhesive composition A as long as it satisfies the above formula (1) in relation to the first pressure-sensitive adhesive composition, and can be formed directly from any pressure-sensitive adhesive composition. Alternatively, it can be formed by using a pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer formed by using any pressure-sensitive adhesive composition. However, the second pressure-sensitive adhesive composition is preferably formed from the above-mentioned pressure-sensitive adhesive composition A, or is formed by using a pressure-sensitive adhesive sheet formed by applying the above-mentioned pressure-sensitive adhesive composition A on a substrate. Is also preferable.

That is, although the composition of the second pressure-sensitive adhesive layer 104 is different from that of the first pressure-sensitive adhesive layer 102, it is common in that it is preferably formed from the pressure-sensitive adhesive composition A. Therefore, the second pressure-sensitive adhesive layer 104 includes the composition and compounding components of the second pressure-sensitive adhesive composition, the type of the second pressure-sensitive adhesive composition (whether or not it is an active energy ray-curable type or a heat-curable type, etc.). ), Additives that can be blended in the second pressure-sensitive adhesive composition, the method for producing the second pressure-sensitive adhesive layer, the thickness of the second pressure-sensitive adhesive layer, and the like. The first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer formed by using the second pressure-sensitive adhesive composition)] can be as described in the column.

In the laminated body 100, at least one of the first pressure-sensitive adhesive layer 102 and the second pressure-sensitive adhesive layer 104 preferably has a thickness of 20 μm or more and 50 μm or less. Therefore, the thickness of the second pressure-sensitive adhesive layer 104 can be, for example, 3 μm or more and 100 μm or less, preferably 5 μm or more and 50 μm or less, and may be 20 μm or more. The thickness of the second pressure-sensitive adhesive layer 104 is most preferably 20 μm or more and 50 μm or less.

[Back plate]
As the back plate 105, a plate-like body capable of transmitting light, a component used in a normal display device, or the like can be used.

The thickness of the back plate 105 may be, for example, 5 μm or more and 2000 μm or less, preferably 10 μm or more and 1000 μm or less, and more preferably 15 μm or more and 500 μm or less.

The plate-like body used for the back plate 105 may be composed of only one layer, may be composed of two or more layers, and an example of the plate-like body described in the front plate 101 may be used. can.

Examples of the components used in the ordinary display device used for the back plate 105 include a separator, a touch sensor panel, an organic EL display element, and the like. The stacking order of the components in the display device is, for example, front plate / circular polarizing plate / separator, front plate / circular polarizing plate / organic EL display device, front plate / circular polarizing plate / touch sensor panel / organic EL display element, front. Examples thereof include a face plate / touch sensor panel / circular polarizing plate / organic EL display element. The back plate 105 is preferably a touch sensor panel.

(Touch sensor panel)
As the touch sensor panel, as long as it is a sensor that can detect the touched position, the detection method is not limited, and the resistance film method, the capacitance coupling method, the optical sensor method, the ultrasonic method, and the electromagnetic induction coupling are used. A touch sensor panel of a method, a surface acoustic wave method, or the like is exemplified. Since the cost is low, a touch sensor panel of a resistance film type or a capacitance coupling type is preferably used.

An example of a resistance film type touch sensor panel is a pair of substrates facing each other, an insulating spacer sandwiched between the pair of substrates, and a transparent film provided as a resistance film on the inner front surface of each substrate. It is composed of a conductive film and a touch position detection circuit. In an image display device provided with a resistance film type touch sensor panel, when the surface of the front plate is touched, the opposing resistance films are short-circuited and a current flows through the resistance film. The touch position detection circuit detects the change in voltage at this time, and the touched position is detected.

An example of a capacitance coupling type touch sensor panel is composed of a substrate, a transparent electrode for position detection provided on the entire surface of the substrate, and a touch position detection circuit. In an image display device provided with a capacitance coupling type touch sensor panel, when the surface of the front plate is touched, the transparent electrode is grounded via the capacitance of the human body at the touched point. The touch position detection circuit detects the grounding of the transparent electrode, and the touched position is detected.

The thickness of the touch sensor panel may be, for example, 5 μm or more and 2000 μm or less, and may be 5 μm or more and 100 μm or less.

[Phase difference layer]
The laminate 100 can have one or more retardation layers between the polarizer layer 103 and the back plate 105. The retardation layer is formed through a first pressure-sensitive adhesive layer 102, a second pressure-sensitive adhesive layer 104, or a layer composed of a pressure-sensitive adhesive or an adhesive other than these layers (hereinafter, also referred to as a bonding layer). (Including other retardation layers.) Can be laminated on top.

Examples of the retardation layer include a positive A plate such as a λ / 4 plate and a λ / 2 plate, a positive C plate, and the like. The retardation layer may be, for example, a retardation film that can be formed from the above-mentioned thermoplastic resin film, or contains a layer obtained by curing a polymerizable liquid crystal compound, that is, a cured product of the polymerizable liquid crystal compound. It may be a layer, but the latter is preferable. The thickness of the retardation film may be the same as the thickness of the above-mentioned thermoplastic resin film. The thickness of the retardation layer obtained by curing the polymerizable liquid crystal compound is, for example, 0.1 μm or more and 10 μm or less, preferably 0.5 μm or more and 8 μm or less, and more preferably 1 μm or more and 6 μm or less.

The retardation layer formed by curing the polymerizable liquid crystal compound can be formed by applying a composition containing the polymerizable liquid crystal compound to a base film and curing the composition. An orientation layer may be formed between the base film and the coating layer. The material and thickness of the base film may be the same as the material and thickness of the thermoplastic resin film described above. The retardation layer formed by curing the polymerizable liquid crystal compound may be incorporated into the laminate 100 in the form of having an alignment layer and / or a base film. The back plate 105 may be a base film to which the above composition is applied.

[Lated layer]
The bonding layer is a layer arranged between the first pressure-sensitive adhesive layer 102 and the second pressure-sensitive adhesive layer 104, and is a layer composed of a pressure-sensitive adhesive or an adhesive. The pressure-sensitive adhesive constituting the bonding layer may be the same pressure-sensitive adhesive as exemplified for the pressure-sensitive adhesive composition constituting the first pressure-sensitive adhesive layer 102 and the second pressure-sensitive adhesive layer 104, or other pressure-sensitive adhesives. For example, it may be a (meth) acrylic pressure-sensitive adhesive, a styrene-based pressure-sensitive adhesive, a silicone-based pressure-sensitive adhesive, a rubber-based pressure-sensitive adhesive, a urethane-based pressure-sensitive adhesive, a polyester-based pressure-sensitive adhesive, an epoxy-based copolymer pressure-sensitive adhesive, or the like.

As the adhesive constituting the bonded layer, for example, one or two or more of water-based adhesives, active energy ray-curable adhesives, adhesives and the like can be combined to form the adhesive. Examples of the water-based adhesive include a polyvinyl alcohol-based resin aqueous solution, a water-based two-component urethane-based emulsion adhesive, and the like. The active energy ray-curable adhesive is an adhesive that cures by irradiating with active energy rays such as ultraviolet rays, and includes, for example, a polymerizable compound and a photopolymerizable initiator, a photoreactive resin, and the like. Examples thereof include those containing a binder resin and a photoreactive cross-linking agent. Examples of the polymerizable compound include photopolymerizable monomers such as a photocurable epoxy monomer, a photocurable acrylic monomer, and a photocurable urethane monomer, and oligomers derived from these monomers. Examples of the photopolymerization initiator include substances that generate active species such as neutral radicals, anion radicals, and cationic radicals by irradiating with active energy rays such as ultraviolet rays.

The thickness of the bonded layer may be, for example, 1 μm or more, preferably 1 μm or more and 25 μm or less, more preferably 2 μm or more and 15 μm or less, and further preferably 2.5 μm or more and 5 μm or less.

As shown in FIG. 2, for example, the laminate 200 according to another aspect of the present invention includes a front plate 101, a first pressure-sensitive adhesive layer 102, a polarizer layer 103, a second pressure-sensitive adhesive layer 104, and a back plate 105. , The bonded layer 108, the first retardation layer 106, the bonding layer 109, and the second retardation layer 107 can be further provided.

[Manufacturing method of laminated body]
The laminates 100 and 200 can be manufactured by a method including a step of laminating the layers constituting the laminates 100 and 200 via an adhesive layer or an adhesive layer. When the layers are bonded to each other via the pressure-sensitive adhesive layer or the adhesive layer, one or both of the bonded surfaces may be subjected to a surface activation treatment such as a corona treatment for the purpose of improving the adhesion. preferable.

The polarizer layer 103 can be formed directly on the thermoplastic resin film or the base film, and the thermoplastic resin film or the base film may be incorporated into the laminates 100 and 200, or may be incorporated into the laminates 100 and 200. It does not have to be separated from the polarizer layer 103 to become a component of the laminate.

<Display device>
The display device according to one aspect of the present invention includes the above-mentioned laminates 100 and 200. The display device is not particularly limited, and examples thereof include an image display device such as an organic EL display device, an inorganic EL display device, a liquid crystal display device, and an electroluminescent display device. The display device may have a touch panel function. Since the laminated bodies 100 and 200 have improved durability by suppressing the generation of air bubbles in the pressure-sensitive adhesive layer, they are suitable for a flexible display device capable of bending or bending.

In the display device, the laminated bodies 100 and 200 are arranged on the visible side of the display element of the display device with the front plate facing the outside (the side opposite to the display element side, that is, the visual recognition side). It is preferable that the display device can be bent with the front plate 101 side of the laminated bodies 100 and 200 inside.

The display device according to the present invention can be used as a mobile device such as a smartphone or tablet, a television, a digital photo frame, an electronic signboard, a measuring instrument, an instrument, an office device, a medical device, a computer device, or the like.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to these examples. When the terms "%" and "parts" are used in the present examples, these terms mean mass% and parts by mass unless otherwise specified.

[Measuring method]
The measurement method and calculation method of each physical property value (weight average molecular weight, each physical property of the pressure-sensitive adhesive layer, etc.) used in this example are as follows.

<Measurement of weight average molecular weight (Mw)>
The weight average molecular weight (Mw) of the (meth) acrylic polymer A was determined by the following size exclusion chromatography (SEC) using tetrahydrofuran as the mobile phase as the polystyrene-equivalent number average molecular weight (Mn).

Specifically, the (meth) acrylic polymer A to be measured was dissolved in tetrahydrofuran at a concentration of about 0.05% by mass, and 10 μL was injected into SEC. The mobile phase was flowed at a flow rate of 1.0 mL / min. PLgel MIXED-B (manufactured by Polymer Laboratories) was used as a column. A UV-VIS detector (trade name: Agilent GPC) was used as the detector.

<Layer thickness>
The measurement was performed using a contact type film thickness measuring device (“MS-5C” manufactured by Nikon Corporation). However, the polarizer layer and the alignment film were measured using a laser microscope (“OLS3000” manufactured by Olympus Corporation).

<Repeated strain addition test>
The strain repeated addition test was performed by using a viscoelasticity measuring device (MCR-301, Antonio Par). The specific test method is as follows. First, a first pressure-sensitive adhesive reference layer is formed using the first pressure-sensitive adhesive composition so that the thickness of the first pressure-sensitive adhesive reference layer and the thickness of the second pressure-sensitive adhesive reference layer are the same, and the second pressure-sensitive adhesive composition. A second pressure-sensitive adhesive reference layer was formed using the material. Specifically, the adhesive sheet (adhesive sheet A11, adhesive sheet A12, etc.) on which the adhesive layer described later is formed is cut into a width of 20 mm × a length of 20 mm, the release film is peeled off, and eight sheets are laminated to obtain a thickness. A 200 μm pressure-sensitive adhesive reference layer (first pressure-sensitive adhesive reference layer and second pressure-sensitive adhesive reference layer) was formed. Next, this pressure-sensitive adhesive reference layer was bonded to a glass plate. Further, under the conditions of a temperature of 25 ° C., a Normal Force Free, and a frequency of 2 Hz in a state where the pressure-sensitive adhesive reference layer on the glass plate is adhered to the measuring chip in the above device, the Strin (strain) of 0% and 1000%. Repeated strain addition test by repeatedly adding (unit is "%") and advancing for 1000 seconds (thus, 0% and 1000% Normal (strain) is repeatedly added to the adhesive sheet for 1000 seconds). Was executed.

<Shear creep value and shear creep rate>
For the first pressure-sensitive adhesive reference layer and the second pressure-sensitive adhesive reference layer before the strain repeated addition test is executed, and for the first pressure-sensitive adhesive reference layer and the second pressure-sensitive adhesive reference layer after the strain repeated addition test is performed. , The shear creep value (unit: "%") at 25 ° C. was determined using the following methods. That is, the shear creep value at 25 ° C. was determined by measuring using the above-mentioned viscoelasticity measuring device (MCR-301, Antonio Par). Specifically, the temperature of the pressure-sensitive adhesive reference layer on the glass plate before the repeated strain addition test or after the repeated strain addition test is adhered to the measuring chip in the apparatus. The shear creep value at that time was determined by allowing 1200 seconds to elapse under the conditions of 25 ° C., Normal Force 1N, and Torque 1200 μNm.

Further, each value obtained as a shear creep value before and after executing the strain repeated addition test was divided by the thickness (200 μm) of the first pressure-sensitive adhesive reference layer or the second pressure-sensitive adhesive reference layer. As a result, the first shear creep rate (R1A, unit is "% / μm", the same applies hereinafter), which is the shear creep value per 1 μm of the thickness with respect to the first pressure-sensitive adhesive reference layer after the strain repetition addition test is performed, and the strain repetition. The second shear creep rate (R1B), which is the shear creep value per 1 μm of thickness with respect to the first pressure-sensitive adhesive reference layer before the addition test is performed, and the thickness of 1 μm with respect to the second pressure-sensitive adhesive reference layer after the strain repeated addition test is performed. The third shear creep rate (R2A), which is the shear creep value per unit, and the fourth first shear creep rate (R2A), which is the shear creep value per 1 μm in thickness with respect to the second pressure-sensitive adhesive reference layer before performing the strain repeated addition test. R2B) was calculated. Subsequently, the second shear creep rate was subtracted from the first shear creep rate, and the fourth shear creep rate was subtracted from the third shear creep rate, so that the subtracted values were obtained as ΔR1 and ΔR2, respectively.

<Gel fraction of adhesive layer>
The gel fraction of the pressure-sensitive adhesive layer (the pressure-sensitive adhesive layer A11 and the pressure-sensitive adhesive layer A12) was measured according to the following (I) to (V).
(I) A pressure-sensitive adhesive layer having an area of about 8 cm × about 8 cm and a metal mesh (the mass thereof is Wm) made of SUS304 having an area of about 10 cm × about 10 cm are bonded together.
(II) Weigh the mass of the laminate obtained in (I) above, set the mass to Ws, then fold it four times so as to wrap the adhesive layer, staple it with a stapler, and then weigh it. , Let the mass be Wb.
(III) The mesh stapled in (II) above is placed in a glass container, 60 mL of ethyl acetate is added and immersed, and then the glass container is stored at room temperature for 3 days.
(IV) The mesh of (III) above was taken out from the glass container, dried at 120 ° C. for 24 hours, and then weighed to give a mass of Wa.
(V) The pressure-sensitive adhesive layer by substituting the above-mentioned weighed mass into the formula of gel fraction (mass%) = [{Wa- (Wb-Ws) -Wm} / (Ws-Wm)] × 100. The gel fraction of was calculated.

[Manufacturing of adhesive sheet]
[1] Production of Adhesive Sheet A11 (1) Preparation of (Meta) Acrylic Polymer A In a reaction vessel equipped with a cooling tube, a nitrogen introduction tube, a thermometer and a stirrer, 81.8 parts by mass of acetone and butyl acrylate 98. A mixed solution of 6 parts by mass, 1.0 part by mass of 2-hydroxyethyl acrylate and 0.4 parts by mass of acrylic acid was charged, and the internal temperature was 55 ° C. while replacing the air in the container with nitrogen gas to make it oxygen-free. I raised it to. Then, a total amount of a solution prepared by dissolving 0.14 parts by mass of azobisisobutyronitrile (polymerization initiator) in 10 parts by mass of acetone was added. Internal temperature while continuously adding acetone into the reaction vessel at an addition rate of 17.3 parts by mass / hr so that the concentration of the acrylic resin excluding the monomer becomes 35% by mass 1 hour after the addition of the polymerization initiator. The temperature was kept at 54 to 56 ° C. for 12 hours, and finally acetone was added to adjust the concentration of the acrylic resin to 20% by mass. The obtained acrylic resin had a polystyrene-equivalent weight average molecular weight Mw of 1270000 by GPC. This is referred to as (meth) acrylic polymer A. The structural unit derived from 2-hydroxyethyl acrylate, which is a hydroxyl group-containing unsaturated monomer in the (meth) acrylic polymer A, is 1% by mass, and is derived from acrylic acid, which is a carboxyl group-containing unsaturated monomer. The structural unit to be used is 0.4% by mass.

(2) Preparation of Adhesive Composition A11 100 parts by mass (solid content conversion value; the same applies hereinafter) of the (meth) acrylic polymer A obtained in the above step and polyisocyanate as a thermal cross-linking agent B (manufactured by Tosoh Corporation, Co., Ltd.) Product name "Coronate L") and 3-glycidoxypropyltrimethoxysilane (manufactured by Shinetsu Chemical Industry Co., Ltd., product name "KBM403") as a silane coupling agent C are mixed, stirred well and diluted with methyl ethyl ketone. A coating solution of the pressure-sensitive adhesive composition A11 was obtained. Table 1 shows each formulation (solid content conversion value) of the pressure-sensitive adhesive composition A11 when the (meth) acrylic polymer is 100 parts by mass (solid content conversion value). The abbreviation "BA" in Table 1 represents n-butyl acrylate, "2EHA" represents 2-ethylhexyl acrylate, and "AA" represents acrylate. The Tg (° C.) of these BA, 2EHA and AA was determined by differential thermal analysis (DTA).

(3) Production of Adhesive Sheet A11 The coating solution of the adhesive composition A11 is applied to the peeling surface of the first release film (manufactured by Lintec Corporation, product name "SP-PET752150") with a knife coater. Formed an object. A coating layer was formed by heat-treating the coated material at 90 ° C. for 1 minute. Next, the coating layer on the first release film and the second release film (manufactured by Lintec Co., Ltd., product name "SP-PET382120") are attached so that the release-treated surface of the second release film is in contact with the coating layer. The pressure-sensitive adhesive sheet A11 having a pressure-sensitive adhesive layer having a thickness of 25 μm formed by using the pressure-sensitive adhesive composition A11 by curing under the conditions of 23 ° C. and 50% RH for 7 days, that is, the first release film / A pressure-sensitive adhesive sheet A11 having a structure of a pressure-sensitive adhesive layer (thickness: 25 μm) / a second release film was produced. In this embodiment, the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet A11 is also referred to as the pressure-sensitive adhesive layer A11.

[2] Production of Adhesive Sheet A12 (1) Preparation of (Meta) Acrylic Polymer A The (meth) acrylic polymer A used for the production of the pressure-sensitive adhesive sheet A11 was prepared.

(2) Preparation of Adhesive Composition A12 With respect to 100 parts by mass of the (meth) acrylic polymer A, the amount of Coronate L, which is a heat-crosslinking agent, is as shown in Table 1, but the pressure-sensitive adhesive composition A11 is prepared. By using the same preparation method, a coating solution of the pressure-sensitive adhesive composition A12 was obtained.

(3) Production of Adhesive Sheet A12 The pressure-sensitive adhesive sheet A12 was produced by using the coating solution of the pressure-sensitive adhesive composition A12 in the same manner as in the production process of the pressure-sensitive adhesive sheet A11. In this embodiment, the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet A12 is also referred to as the pressure-sensitive adhesive layer A12.

Table 1 shows each formulation (solid content conversion value) of the pressure-sensitive adhesive composition A12 when the (meth) acrylic polymer is 100 parts by mass (solid content conversion value). Table 1 also shows the gel fraction values of the pressure-sensitive adhesive composition A11 and the pressure-sensitive adhesive composition A12 obtained by the above method.

Further, OCA8146-02 and CEF3004 (both manufactured by 3M, Inc. of the United States) were prepared as commercially available adhesive sheets.

[3] Production of Adhesive Sheet B11 (1) Preparation of (Meta) Acrylic Polymer B1 A reaction vessel equipped with a cooling device in which nitrogen gas is circulated is prepared so that the temperature can be easily controlled. The monomer mixture shown in Table 2 was charged into this reaction vessel. Nitrogen gas was parsed for 1 hour to remove oxygen. After maintaining the temperature at 60 ° C. and uniformly mixing the monomer mixture, the photopolymerization initiator shown in Table 2 was added. After that, the mixture was stirred and irradiated with ultraviolet rays (10 mW) from a UV lamp to produce a (meth) acrylic polymer B1. As the photopolymerization initiator, I-651 (manufactured by BASF) and I-184 (manufactured by BASF) were used. The weight average molecular weight (Mw) of the (meth) acrylic polymer B1 is 700,000.

(2) Preparation of Adhesive Composition B11 The contents of the above (meth) acrylic polymer B1, the active energy ray-polymerizable compound, and the photopolymerization initiator are mixed so as to be in the ratios shown in Table 3. The pressure-sensitive adhesive composition B11 was produced. I-184 (manufactured by BASF) was used as the photopolymerization initiator. The gel fraction of the pressure-sensitive adhesive composition B11 was 72%.

(3) Production of Adhesive Sheet B11 The above-mentioned pressure-sensitive adhesive composition B11 was applied onto a release film that had been subjected to a silicon mold release treatment so as to have a thickness of 25 μm. After further laminating a release film on the coating film, an adhesive sheet B11 was prepared by irradiating with ^{ultraviolet rays (integrated light amount 400 mJ / cm 2} , illuminance 1.8 mW / cm ^{2, UVV standard).} In this embodiment, the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet B11 is also referred to as a pressure-sensitive adhesive layer B11.

[4] Production of Adhesive Sheet B21 (1) Preparation of (Meta) Acrylic Polymer B2 A reaction vessel equipped with a cooling device in which nitrogen gas is circulated is prepared so that the temperature can be easily controlled. The monomer mixture shown in Table 2 was charged into this reaction vessel. Nitrogen gas was parsed for 1 hour to remove oxygen. After maintaining the temperature at 60 ° C. and uniformly mixing the monomer mixture, the photopolymerization initiator shown in Table 2 was added. After that, the mixture was stirred and irradiated with ultraviolet rays (10 mW) from a UV lamp to produce a (meth) acrylic polymer B2. The weight average molecular weight (Mw) of the (meth) acrylic polymer B2 is 700,000.

(2) Preparation of Adhesive Composition B21 The contents of the (meth) acrylic polymer B2, the active energy ray-polymerizable compound, and the photopolymerization initiator are mixed so as to be in the ratios shown in Table 3. The pressure-sensitive adhesive composition B21 was produced. The gel fraction of the pressure-sensitive adhesive composition B21 was 70%.

(3) Production of Adhesive Sheet B21 The above-mentioned pressure-sensitive adhesive composition B21 was applied onto a release film that had been subjected to a silicon mold release treatment so as to have a thickness of 25 μm. After further laminating a release film on the coating film, an adhesive sheet B21 was prepared by irradiating with ^{ultraviolet rays (integrated light amount 400 mJ / cm 2} , illuminance 1.8 mW / cm ^{2, UVV standard).} In this embodiment, the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet B21 is also referred to as a pressure-sensitive adhesive layer B21.

The abbreviation "LA" in Table 2 represents lauryl acrylate, "BA" represents n-butyl acrylate, "2-PHA" represents 2-propyl heptyl acrylate, and "C22A". Represents behenyl acrylate and "ODA" represents octyldecyl acrylate.

The abbreviation "IDA" in Table 3 represents isodecyl acrylate, and "IBOA" represents isobornyl acrylate.

For each of the above-mentioned pressure-sensitive adhesive sheets, a pressure-sensitive adhesive reference layer having a thickness of 200 μm was prepared according to the above-mentioned method, and before the strain repetition addition test was performed for each pressure-sensitive adhesive reference layer, and the strain repetition addition test was performed. The shear creep value (%) and the difference in shear creep rate (% / μm) after the execution were determined. The results are shown in Table 4. Table 4 also shows the numerical values of the shear creep rate (% / μm) before performing the strain repeated addition test in each pressure-sensitive adhesive reference layer.

[Manufacturing of laminate]
[Front plate (window film)]
As a front plate, a polyimide film (thickness 50 μm) having a hard coat layer (thickness 10 μm) on one side was prepared.

[Polarizer layer]
1. 1. Material preparation The following materials were prepared.

1) TAC film with a thickness of 25 μm 2) Composition for forming an alignment film <Polymer 1>
A polymer 1 having a photoreactive group consisting of the following structural units was prepared.

A solution in which polymer 1 was dissolved in cyclopentanone at a concentration of 5% by mass was prepared as a composition for forming an alignment film [hereinafter, also referred to as composition (D-1)].

3) Composition for forming a polarizer layer <Polymerizable liquid crystal compound>
As the polymerizable liquid crystal compound, the polymerizable liquid crystal compound represented by the formula (1-1) [hereinafter, also referred to as compound (1-1)] and the polymerizable liquid crystal compound represented by the formula (1-2) [hereinafter, Compound (1-2)] was prepared.

Compound (1-1) and compound (1-2) are described in Lub et al. Recl. Trav. Chim. It was synthesized by the method described in Pays-Bas, 115, 321-328 (1996).

<Dichroic pigment>
As the dichroic dye, the azo dye described in Examples of Japanese Patent Application Laid-Open No. 2013-101328 represented by the following formulas (2-1a), (2-1b) and (2-3a) was prepared.

The composition for forming a polarizer layer [hereinafter, also referred to as composition (A-1)] has 75 parts by mass of compound (1-1), 25 parts by mass of compound (1-2), and the above formula as a bicolor dye. 2.5 parts by mass of each of the azo dyes represented by (2-1a), (2-1b) and (2-3a), 2-dimethylamino-2-benzyl-1- (4-morpholinophenyl) as a polymerization initiator ) Butan-1-one (Irgacure 369, manufactured by BASF Japan) 6 parts by mass, and 1.2 parts by mass of a polyacrylate compound (BYK-361N, manufactured by BYK-Chemie) as a leveling agent, 400 parts by mass of toluene as a solvent. And the resulting mixture was prepared by stirring at 80 ° C. for 1 hour.

4) Composition for forming a protective layer (OC layer) The composition for forming a protective layer (OC layer) [hereinafter, also referred to as composition (E-1)] is water: 100 parts by mass, polyvinyl alcohol resin powder (Co., Ltd.). ) Made by Kuraray, average degree of polymerization 18000, trade name: KL-318): 3 parts by mass, polyamide epoxy resin (crosslinking agent, manufactured by Sumika Chemtex Co., Ltd., trade name: SR650 (30)): 1.5 parts by mass Was prepared by mixing.

2. Production method 1) The composition for forming an alignment film was coated on the TAC film side as follows. That is, first, the TAC film side was subjected to the corona treatment once. The conditions for corona treatment were an output of 0.3 kW and a processing speed of 3 m / min. Then, the composition (D-1) obtained as described above was applied onto the TAC by the bar coating method, and dried by heating in a drying oven at 80 ° C. for 1 minute. The obtained dry film was subjected to polarized UV irradiation treatment to form a first alignment film (AL1). In the polarized UV treatment, the light emitted from the UV irradiation device (SPOT CURE SP-7; manufactured by Ushio, Inc.) is transmitted through a wire grid (UIS-27132 ##, manufactured by Ushio, Inc.) to have a wavelength of 365 nm. The test was performed under the condition that the integrated light amount measured in 1 was 100 mJ / cm ^2. The thickness of the first alignment film (AL1) was 100 nm.

2) The composition for forming a polarizer layer was coated on the alignment film side as follows. That is, first, the composition (A-1) was applied onto the first alignment film (AL1) by the bar coating method, heated and dried in a drying oven at 120 ° C. for 1 minute, and then cooled to room temperature. A polarizer layer (pol) was formed by irradiating the dry film with ultraviolet rays at an integrated light intensity of 1200 mJ / cm ^{2 (365 nm standard) using the above UV irradiation device.} The thickness of the obtained polarizer layer (pol) was measured with a laser microscope (OLS3000 manufactured by Olympus Corporation) and found to be 1.8 μm. In this way, a laminate made of "TAC / AL1 / pol" was obtained.

3) The composition for forming a protective layer (OC layer) was coated on the polarizer layer side as follows. That is, the composition (E-1) is applied onto the polarizer layer (pol) by a bar coating method, coated so that the thickness after drying is 1.0 μm, and the temperature is 80 ° C. for 3 minutes. It was dry. In this way, a laminate made of "TAC film / cPL (AL1 + pol + protective layer)" was obtained.

[Phase difference layer]
1. 1. Material preparation The following materials were prepared.

1) PET film having a thickness of 100 μm 2) Composition for forming an alignment film A solution prepared by dissolving the above-mentioned polymer 1 in cyclopentanone at a concentration of 5% by mass is used as a composition for forming an alignment film (composition (D-1)). Got ready.

3) Composition for forming a retardation layer The composition (B-1) was obtained by mixing the components shown below and stirring the obtained mixture at 80 ° C. for 1 hour.

Compound b-1 represented by the following formula: 80 parts by mass

Compound b-2: 20 parts by mass represented by the following formula

Polymerization initiator (Irgacure 369, 2-dimethylamino-2-benzyl-1- (4-morpholinophenyl) butane-1-one, manufactured by BASF Japan Ltd.): 6 parts by mass leveling agent (BYK-361N, polyacrylate compound, BYK) -Chemie): 0.1 parts by mass Solvent (cyclopentanone): 400 parts by mass.

2. Production method 1) The composition for forming an alignment film was coated on the PET film as follows. That is, a polyethylene terephthalate film (PET) having a thickness of 100 μm was prepared as a base material, the composition (D-1) was applied onto the film by a bar coating method, and the film was heated and dried in a drying oven at 80 ° C. for 1 minute. The obtained dry film was subjected to polarized UV irradiation treatment to form a second alignment film (AL2). The polarized UV treatment was carried out under the condition that the integrated light amount measured at a wavelength of 365 nm was 100 mJ / cm ^{2 using the above UV irradiation device.} The polarization direction of the polarized UV was set to 45 ° with respect to the absorption axis of the polarizer layer. In this way, a laminate composed of "base material (PET) / second alignment film (AL2)" was obtained.

2) The composition for forming a retardation layer was coated on the alignment film side of the PET film as follows. That is, the composition (B-1) is applied on the second alignment film (AL2) of the laminate composed of the above "base material (PET) / second alignment film (AL2)" by the bar coating method, and the temperature is 120 ° C. After heating and drying in a drying oven for 1 minute, the mixture was cooled to room temperature. A retardation layer was formed by irradiating the obtained dry film with ultraviolet rays having an integrated light intensity of 1000 mJ / cm ^{2 (365 nm standard) using the above UV irradiation device.} The thickness of the obtained retardation layer was measured with a laser microscope (OLS3000 manufactured by Olympus Corporation) and found to be 2.0 μm. The retardation layer was a λ / 4 plate (QWP) showing a retardation value of λ / 4 in the in-plane direction. In this way, a laminate composed of "base material (PET) / retardation portion (AL2 + QWP)" was obtained.

[Common adhesive sheet]
1) Polymerization of Acrylic Resin The following components were reacted at 55 ° C. with stirring in a nitrogen atmosphere to obtain an acrylic resin.
Butyl acrylate: 70 parts by mass Methyl acrylate: 20 parts by mass Acrylic acid: 2.0 parts by mass Radical polymerization initiator (2,2'-azobisisobutyronitrile): 0.2 parts by mass.

2) Preparation of pressure-sensitive adhesive composition The following components were mixed to obtain a pressure-sensitive adhesive composition.
Acrylic resin: 100 parts by mass Crossing agent (“Coronate L” manufactured by Tosoh Corporation): 1.0 parts by mass Silane coupling agent (“X-12-981” manufactured by Shin-Etsu Chemical Co., Ltd.): 0.5 parts by mass.

The pressure-sensitive adhesive composition was prepared by adding ethyl acetate so that the total solid content concentration was 10% by mass.

3) Manufacture of Common Adhesive Sheet After the adhesive composition prepared as described above is dried on the release-treated surface of the release-treated polyethylene terephthalate film (heavy separator, thickness 38 μm) using an applicator. A coating layer was obtained by coating so as to have a thickness of 5 μm. This coating layer was dried at 100 ° C. for 1 minute to obtain a film having an adhesive layer. Then, another polyethylene terephthalate film (light separator, thickness 38 μm) that had been released from the mold was attached onto the exposed surface of the pressure-sensitive adhesive layer. Then, it was cured for 7 days under the conditions of a temperature of 23 ° C. and a relative humidity of 50% RH to obtain a common pressure-sensitive adhesive sheet having a layer structure of a light separator / common pressure-sensitive adhesive layer / heavy separator.

[Back plate]
As a back plate, a PET film having a thickness of 100 μm was prepared.

[Example 1]
Laminates were manufactured by the procedure shown in FIGS. 3 (a) to 3 (e). First, as shown in FIG. 3A, the above-mentioned polarizer layer 410 [TAC film 301 / cPL ((AL1 + pol) 302 / OC layer 303)] and the above-mentioned common adhesive sheet 420 (light separator 304 / common adhesive layer). 305 / heavy separator 306) was prepared. By applying corona treatment (output 0.3 kW, processing speed 3 m / min) to the OC layer 303 side of the polarizer layer 410 and the surface from which the light separator 304 of the common adhesive sheet 420 has been peeled off, they are bonded together. The first laminated body precursor 430 shown in FIG. 3 (b) was obtained. Further, as shown in FIG. 3 (b), the above-mentioned retardation layer 440 [base material (PET) 308 / retardation portion (AL2 + QWP) 307] was prepared.

Next, the surface from which the retardation portion 307 side of the retardation layer 440 and the heavy separator 306 of the first laminated body precursor 430 were peeled off was subjected to corona treatment (output 0.3 kW, processing speed 3 m / min), and then subjected to corona treatment (output 0.3 kW, processing speed 3 m / min). By laminating, the second laminated body precursor 450 shown in FIG. 3C was obtained. Then, as shown in FIG. 3C, the pressure-sensitive adhesive sheet A12 was prepared as the pressure-sensitive adhesive sheet 460 (first release film 309 / adhesive layer 310 / second release film 311). The pressure-sensitive adhesive layer 310 of the pressure-sensitive adhesive sheet 460 corresponds to the second pressure-sensitive adhesive layer.

Corona treatment (output 0.3 kW, processing speed 3 m / min) was applied to the surface from which the base material (PET) 308 of the second laminate precursor 450 was peeled off and the surface from which the first release film 309 of the adhesive sheet 460 was peeled off. After the application, the third laminated body precursor 470 shown in FIG. 3D was obtained by laminating. Further, the adhesive sheet A11 was prepared as the adhesive sheet 490 (first release film 314 / adhesive layer 315 / second release film 316), and the surface from which the first release film 314 was peeled and the above-mentioned front plate 480 (polyimide) were prepared. The fourth laminated body shown in FIG. 3D is formed by applying corona treatment (output 0.3 kW, processing speed 3 m / min) to the polyimide film 313 side of the film 313 / hard coat layer 312) and then laminating them. A precursor 500 was obtained. The pressure-sensitive adhesive layer 315 of the pressure-sensitive adhesive sheet 490 corresponds to the first pressure-sensitive adhesive layer.

Subsequently, the surface from which the second release film 316 of the fourth laminated body precursor 500 was peeled off and the TAC301 side of the third laminated body precursor 470 were subjected to corona treatment (output 0.3 kW, processing speed 3 m / min). After that, the sixth laminated body precursor 300 shown in FIG. 3 (e) was obtained by laminating. Finally, the second release film 311 was peeled off in the sixth laminated body precursor 300, and the peeled surface and one surface of the PET film having a thickness of 100 μm prepared as the back plate were subjected to corona treatment (output 0.3 kW, The laminate of Example 1 was obtained by laminating after applying a treatment speed of 3 m / min). The laminate of Example 1 has a thickness of 240 μm and a shape of 190 mm in length × 150 mm in width.

[Examples 2 to 5, Comparative Examples 1 to 2]
By applying the same manufacturing method as the laminate of Example 1 except that the pressure-sensitive adhesive sheet having the pressure-sensitive adhesive layer shown in Table 5 was used instead of the pressure-sensitive adhesive sheets A11 and A12 used in Example 1, Examples Laminates of Nos. 2 to 5 and Comparative Examples 1 and 2 were produced.

Table 5 lists the types of pressure-sensitive adhesive compositions used to form the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer with respect to the laminates of Examples 1 to 5 and Comparative Examples 1 and 2. .. Examples 1 to 5 satisfy the relationship of ΔR1 ≦ ΔR2, and Comparative Examples 1 and 2 have a relationship of ΔR1> ΔR2.

Further, the laminated bodies of Examples 1 to 5 and Comparative Examples 1 and 2 were subjected to a bending durability test and a surface hardness test by the method described later. The results are shown in Table 6.

<Bending durability test (mandrel test)>
A test piece having a length of 100 mm and a width of 10 mm was cut out from the laminated body of each Example and each Comparative Example using a super cutter. For this test piece, a bending resistance tester (cylindrical mandrel method) manufactured by TP Giken Co., Ltd. was used, and the test piece was placed on a cylindrical mandrel (cylindrical mandrel method) so that the front plate of the test piece (laminated body) was on the inside. A bending durability test (mandrel test) was performed in which the test piece was bent along the length direction at a temperature of 25 ° C. by wrapping it around the mandrel). As a result, the minimum diameter of the mandrel that does not generate air bubbles in the pressure-sensitive adhesive layer of the test piece (laminated body) was determined, and ranked based on the following criteria. In the bending durability test, it can be evaluated that the smaller the value of this minimum diameter, the better the bending durability of the pressure-sensitive adhesive layer.
A: Bubbles were generated in the adhesive layer when wrapped around a mandrel with a diameter (φ) of 10 mm or less. Bubbles were generated in the pressure-sensitive adhesive layer when wrapped around the mandrel of D: Bubbles were generated in the pressure-sensitive adhesive layer when wound around the mandrel exceeding φ20 mm.

<Surface hardness test>
A pencil hardness tester (PHT, manufactured by SUKBO SCIENCE) was used to apply a load of 100 g to the surface of the front plate of the laminate of each example and each comparative example at a temperature of 25 ° C. A concave mark was formed on the above surface with a pencil (manufactured by Mitsubishi Pencil Co., Ltd., core hardness is 6B). In this case, the surface hardness of the laminates of each Example and each Comparative Example was evaluated by determining the time until the recess marks disappeared and ranking them based on the following criteria. In this surface hardness test, it can be evaluated that the shorter the time until the recess marks disappear, the better the surface hardness.
A: Recess marks disappeared in less than 30 minutes B: Recess marks disappeared in 30 minutes or more and less than 60 minutes C: Recess marks disappeared in 60 minutes or more and less than 90 minutes D: Recess marks disappeared even after 90 minutes passed Did not disappear.

According to the above, Examples 1 to 5 satisfy the relationship of ΔR1 ≦ ΔR2 and are superior in evaluation of bending durability and surface hardness to Comparative Examples 1 and 2 having a relationship of ΔR1> ΔR2.

100, 200 laminate, 101 front plate, 102 first adhesive layer, 103 polarizer layer, 104 second adhesive layer, 105 back plate, 106 first retardation layer, 107 second retardation layer, 108, 109 Laminated layer.

Claims (5)

A front plate, a first pressure-sensitive adhesive layer formed using the first pressure-sensitive adhesive composition, a polarizer layer, a second pressure-sensitive adhesive layer formed using the second pressure-sensitive adhesive composition, and a back plate. In this order,
A laminate having one or more retardation layers between the polarizer layer and the back plate.
The laminated body is a laminated body of a type in which the front plate side is turned inward and bent.
The front plate includes a resin plate-like body or a glass plate-like body, and constitutes the outermost surface of the display device.
The back plate is a touch sensor panel or an organic EL display element.
Both the first pressure-sensitive adhesive composition and the second pressure-sensitive adhesive composition are pressure-sensitive adhesive compositions containing a (meth) acrylic polymer.
The (meth) acrylic polymer has a monomer content of a homopolymer having a glass transition temperature (Tg) of more than 0 ° C. of 5% by mass or less, and a weight average molecular weight of 400,000 or more and 1.3 million or less.
The first pressure-sensitive adhesive reference layer is formed using the first pressure-sensitive adhesive composition so that the thickness of the first pressure-sensitive adhesive reference layer and the thickness of the second pressure-sensitive adhesive reference layer are the same, and the second pressure-sensitive adhesive is formed. When the second pressure-sensitive adhesive reference layer is formed using the agent composition, the first pressure-sensitive adhesive reference layer and the second pressure-sensitive adhesive reference layer are laminates that satisfy the relationship of the following formula (1).
ΔR1 ≤ ΔR2 (1)
[In equation (1), ΔR1 represents the value obtained by subtracting R1B from R1A.
ΔR2 represents the value obtained by subtracting R2B from R2A.
The R1A represents a first shear creep rate (% / μm), which is a shear creep value per 1 μm of thickness at 25 ° C. obtained for the first pressure-sensitive adhesive reference layer after performing a strain repeated addition test.
The R1B represents a second shear creep rate (% / μm), which is a shear creep value per 1 μm of thickness at 25 ° C. obtained with respect to the first pressure-sensitive adhesive reference layer before executing the strain repeated addition test.
The R2A indicates a third shear creep rate (% / μm), which is a shear creep value per 1 μm of thickness at 25 ° C. obtained for the second pressure-sensitive adhesive reference layer after performing a strain repeated addition test.
The R2B represents a fourth shear creep rate (% / μm), which is a shear creep value per 1 μm of thickness obtained at 25 ° C. with respect to the second pressure-sensitive adhesive reference layer before executing the strain repeated addition test. ] The laminate according to claim 1, wherein the second shear creep rate (% / μm) is 0.1 or more and 0.2 or less. The laminate according to claim 1 or 2, wherein at least one of the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer has a thickness of 20 μm or more and 50 μm or less. A display device including the laminate according to any one of claims 1 to 3. The display device according to claim 4, wherein the display device can be bent with the front plate side inside.

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