KR20240070533A - Curable Adhesive Sheet - Google Patents

Abstract

A curable adhesive sheet having a curable adhesive layer capable of forming a cured product having a dielectric loss tangent of 0.01 or less at 23°C and 1 GHz, and a first release film and a second release film sandwiching both sides of the curable adhesive layer. , the first release film and the second release film have a resin film and a release layer formed on one surface of the resin film with a non-silicone-based release agent and in contact with the surface of the curable adhesive layer, and meet the following requirements ( A curable adhesive sheet that satisfies I) is provided.
· Requirement (I): The peeling force (R1) when peeling the first release film from the curable adhesive layer at a peeling angle of 180° and a peeling speed of 300 mm/min is 250 mN/50 mm or less.

Description

Curable Adhesive Sheet

The present invention relates to a curable adhesive sheet.

Recently, with the miniaturization and weight reduction of electronic devices, flexible printed wiring boards (FPCs) have been used as wiring members. FPC can be manufactured by, for example, etching the copper foil of a copper-clad laminate made by bonding copper foil to an insulating resin film such as polyimide to form an electric circuit.

In addition, for such FPC, a coverlay sheet having an insulating resin substrate and an adhesive layer is bonded to copper foil on which an electric circuit is formed to protect the electric circuit.

As an example of such a coverlay sheet, Patent Document 1 discloses a thermosetting adhesive layer made of an adhesive composition containing a predetermined amount of a styrene-based elastomer, a modified polyphenylene ether resin having a polymerizable group at the terminal, an epoxy resin, and an epoxy resin curing agent. An invention relating to a thermosetting adhesive sheet formed on a substrate is disclosed.

Japanese Patent Publication No. 2019-135280

However, in FPC, from the viewpoint of suppressing harmful effects such as malfunction of electronic devices, the mixing of foreign substances and the migration of contaminants are problems. For example, in the thermosetting adhesive sheet as described in Patent Document 1, a silicone-based release sheet having a layer made of a silicone-based release agent is often laminated on the thermosetting adhesive layer for the purpose of protecting the surface of the thermosetting adhesive layer. Silicone-based release sheets are widely used because they are easy to peel from the thermosetting adhesive layer during use and have excellent handling properties.

However, with the silicone-based release sheet, over time, the silicone (Si) component of the layer made of the silicone-based release agent transfers to the curable adhesive layer, and the silicone component in the curable adhesive layer transfers to the surface of the FPC, which is the adherend. There is a problem that it may be a factor such as malfunction of electronic devices.

Therefore, there is a demand for a curable adhesive sheet that suppresses contamination of the adherend and has excellent handling properties.

The present invention is a curable adhesive sheet having a curable adhesive layer capable of forming a cured product having a dielectric loss tangent of a predetermined value or less, and a first release film and a second release film sandwiching both surfaces of the curable adhesive layer, comprising: A release film and a second release film are formed on a resin film with a non-silicone release agent, have a release layer in contact with the surface of the curable adhesive layer, and peeling when the first release film is peeled from the curable adhesive layer. A curable adhesive sheet whose force is adjusted to a predetermined value or less is provided.

Specifically, one aspect provided by the present invention is as follows.

[1] A curable adhesive having a curable adhesive layer capable of forming a cured product having a dielectric loss tangent of 0.01 or less at 23°C and 1 GHz, and a first release film and a second release film sandwiching both sides of the curable adhesive layer. As an adhesive sheet,

The first release film and the second release film have a resin film and a release layer formed on one surface of the resin film with a non-silicone release agent and in contact with the surface of the curable adhesive layer,

A curable adhesive sheet that satisfies the following requirement (I).

· Requirement (I): The peeling force (R1) when peeling the first release film from the curable adhesive layer at a peeling angle of 180° and a peeling speed of 300 mm/min is 250 mN/50 mm or less.

[2] The curable adhesive sheet according to [1] above, which further satisfies the following requirement (II).

· Requirement (II): The peeling force (R1) is smaller than the peeling force (R2) when peeling the second release film from the curable adhesive layer at a peeling angle of 180° and a peeling speed of 300 mm/min.

[3] The curable adhesive sheet according to [2] above, which further satisfies the following requirement (IIa).

· Requirement (IIa): The ratio [(R1)/(R2)] of the peeling force (R1) and the peeling force (R2) is 0.97 or less.

[4] The curable adhesive sheet according to any one of [1] to [3] above, further satisfying the following requirement (III).

· Requirement (III): The peeling force (R2) when peeling the second peeling film from the curable adhesive layer at a peeling angle of 180° and a peeling speed of 300 mm/min is 300 mN/50 mm or less.

[5] The curable adhesive according to any one of [1] to [4] above, wherein the non-silicone-based release agent used in forming the release layer of at least one of the first release film and the second release film is an alkyd-based release agent. Sheet.

[6] The curable adhesive sheet according to any one of [1] to [5] above, wherein the curable adhesive layer is a layer formed of a curable adhesive composition containing a binder resin (A).

[7] The curable adhesive sheet according to [6] above, wherein the curable adhesive composition further contains polyphenylene ether resin (B).

[8] The curable adhesive sheet according to any one of [1] to [7] above, wherein the resin film (1) constituting the first release film is a colored resin film.

[9] The resin film (2) constituting the second release film has the curability according to any one of [1] to [8] above, and is visually distinguishable from the resin film (1) constituting the first release film. Adhesive sheet.

The curable adhesive sheet of a preferred embodiment of the present invention suppresses contamination of the adherend, has excellent handling properties as the peeling film can be easily removed during use, and is preferably applied as, for example, a coverlay sheet. can do.

Fig. 1 is a schematic cross-sectional view in the thickness direction of the adhesive sheet, showing an example of the configuration of the curable adhesive sheet of the present invention.

The numerical range described in this specification can arbitrarily combine upper and lower limits. For example, when the numerical range is described as “preferably 20 to 120, more preferably 40 to 90,” the range “20 to 90” or the range “40 to 120” are also described in this specification. Included in the numerical range. Also, for example, when the numerical range is described as “preferably 20 or more, more preferably 40 or more, and preferably 120 or less, more preferably 90 or less,” “20 to 90.” ” and the range “40 to 120” are also included in the numerical range described in this specification.

Additionally, as a numerical range described in this specification, for example, the description “60 to 100” means a range of “60 or more, 100 or less.”

In addition, in defining the upper and lower limits described in this specification, the numerical range of the lower limit to the upper limit can be defined by appropriately selecting from each option and arbitrarily combining them.

Additionally, the various requirements described as preferred embodiments described in this specification can be combined in multiple ways.

In this specification, for example, “(meth)acrylate” is used to represent both “acrylate” and “methacrylate”, and the same applies to other similar terms.

In this specification, the “active ingredient” of a curable adhesive composition means a component included in the curable adhesive composition excluding water or a diluting solvent of an organic solvent.

In this specification, the number average molecular weight (Mn) is a standard polystyrene conversion value measured by gel permeation chromatography (GPC), and is specifically a value measured based on the method described in the Examples.

In addition, in this specification, the thickness of each layer constituting the curable adhesive sheet is a value measured in accordance with JIS K7130 (1999), for example, using a static pressure thickness meter (Techlock Co., Ltd., product name “PG-02J”) 」) can be used to measure.

[Composition of curable adhesive sheet]

Fig. 1 is a schematic cross-sectional view in the thickness direction of the adhesive sheet, showing an example of the configuration of the curable adhesive sheet of the present invention.

As shown in FIG. 1, the curable adhesive sheet 1 of the present invention includes a curable adhesive layer 10, a first release film 21 sandwiching both sides of the curable adhesive layer 10, and a second peeling film 21. It has a film (22).

By curing the curable adhesive layer 10, a cured product having a dielectric loss tangent of 0.01 or less at 23°C and 1 GHz can be formed.

In addition, the first release film 21 includes a resin film 212 and a release layer 211 on one surface of the resin film 212 that is in contact with the surface 10a of the curable adhesive layer 10. have

Similarly, regarding the second release film 22, the resin film 222 and the release layer 221 on one surface of the resin film 222 are in contact with the surface 10b of the curable adhesive layer 10. ) has.

The release layers 211 and 221 of the first release film 21 and the second release film 22 are layers formed from a non-silicone release agent.

Since the release layers 211 and 221 are layers formed from a non-silicon-based release agent, the silicone (Si) component does not transfer to the surfaces 10a and 10b of the curable adhesive layer 10 that come into contact with them. Therefore, the curable adhesive sheet of the present invention can suppress contamination due to transfer of silicone components to the adherend.

However, the curable adhesive layer of the curable adhesive sheet of the present invention has a low dielectric loss tangent of 0.01 or less.

In general, a curable adhesive layer with a low dielectric loss tangent is often composed of a component without a polar group or a component with low polarity, and the surface polarity of the curable adhesive layer tends to be low. When using a silicone-based release film, when removing the release film after lamination on the surface of a curable adhesive layer with low polarity, peelability from the surface of the curable adhesive layer is rarely a problem.

However, when a release film having a release layer formed of a non-silicone release agent is used and the release film is laminated on the surface of a curable adhesive layer with low polarity, when the release film is removed from the surface of the curable adhesive layer, Problems with handling, such as difficulty in peeling due to insufficient peelability, arise.

In response to the problem of handling such that it is difficult to peel the release film from the surface of the curable adhesive layer, the curable adhesive sheet of the present invention is adjusted to satisfy the following requirement (I).

· Requirement (I): The peeling force (R1) when peeling the first release film from the curable adhesive layer at a peeling angle of 180° and a peeling speed of 300 mm/min is 250 mN/50 mm or less.

By satisfying the above requirement (I), at the time of use, the first release film can be easily peeled from the surface of the curable adhesive layer, and a curable adhesive sheet with excellent handling properties can be obtained.

In the curable adhesive sheet of one aspect of the present invention, the peeling force (R1) specified in the above requirement (I) is, from the above viewpoint, 250 mN/50 mm or less, but is preferably 200 mN/50 mm or less. Preferably it is 150 mN/50 mm or less, more preferably 110 mN/50 mm or less, even more preferably 90 mN/50 mm or less, and also preferably 5 mN/50 mm or more, more preferably 10 mN/50 mm or more, more preferably 20 mN/50 mm or more.

In addition, as a method of adjusting the peeling force (R1) to fall within the above range, the resin film constituting the first peeling film and the type of release agent forming the release agent layer are included in the curable adhesive composition forming the curable adhesive layer. It can be adjusted by appropriately setting the type and content of each component. In addition, specific adjustment methods are described in detail in the description of each configuration.

The curable adhesive sheet of one aspect of the present invention preferably satisfies the following requirement (II) in addition to the above requirement (I).

· Requirement (II): The peeling force (R1) is smaller than the peeling force (R2) when peeling the second release film from the curable adhesive layer at a peeling angle of 180° and a peeling speed of 300 mm/min.

By satisfying the above requirement (II), the first release film can be more easily peeled from the surface of the curable adhesive layer, and a curable adhesive sheet with better handling properties can be obtained.

From the above viewpoint, it is more preferable that the curable adhesive sheet of one aspect of the present invention further satisfies the following requirement (IIa) in addition to the above requirement (I).

· Requirement (IIa): The ratio [(R1)/(R2)] of the peeling force (R1) and the peeling force (R2) is 0.97 or less.

The ratio [(R1)/(R2)] of the peel force (R1) and the peel force (R2) specified in the above requirement (IIa) allows the first release film to be more easily peeled from the surface of the curable adhesive layer. , from the viewpoint of producing a curable adhesive sheet with better handling properties, it is 0.97 or less, but is preferably 0.95 or less, more preferably 0.88 or less, and even more preferably 0.80 or less. The lower limit of the ratio [(R1)/(R2)] between the peel force (R1) and the peel force (R2) specified in the above requirement (IIa) is not particularly limited, but is preferably 0.2 or more, preferably 0.35. That's it.

In addition, the curable adhesive sheet of one aspect of the present invention preferably satisfies the following requirement (III) in addition to the above requirement (I), and in addition to the above requirements (I) and (II), it further satisfies the following requirement: It is more preferable to satisfy requirement (III), and in addition to the above requirements (I) and (IIa), it is more preferable to additionally satisfy the following requirement (III).

· Requirement (III): Peeling force (R2) is 300 mN/50 mm or less.

By satisfying the above requirement (III), after removing the first release film and attaching the exposed curable adhesive layer to the adherend, the second release film can also be easily peeled, thereby forming a curable adhesive sheet with excellent handling properties. You can.

In the curable adhesive sheet of one aspect of the present invention, the peeling force (R2) specified in the above requirement (III) is, from the above viewpoint, 300 mN/50 mm or less, but is preferably 250 mN/50 mm or less. Preferably it is 220 mN/50 mm or less, more preferably 150 mN/50 mm or less, even more preferably 110 mN/50 mm or less, and also preferably 20 mN/50 mm or more, more preferably 30 mN/50 mm or more, more preferably 40 mN/50 mm or more.

In addition, regarding the peeling force (R2), the type of the release agent that forms the resin film and the release agent layer constituting the second release film, and the type and content of each component contained in the curable adhesive composition that forms the curable adhesive layer. It can be adjusted by setting it appropriately. In addition, specific adjustment methods are described in detail in the description of each configuration.

In addition, in this specification, peeling force (R1) and (R2) mean values measured based on the method described in the Examples described later.

Hereinafter, each layer constituting the curable adhesive sheet of one aspect of the present invention and the forming material of the layer will be described.

[First release film, second release film]

The first release film and the second release film included in the curable adhesive sheet of one aspect of the present invention may have a structure including a resin film and a release layer formed of a non-silicone release agent.

Resin components contained in the resin film include, for example, polyester resins such as polyethylene terephthalate resin, polybutylene terephthalate resin, and polyethylene naphthalate resin, polyolefin resins such as polypropylene resin and polyethylene resin, Polycarbonate resin, and mixed resin using two or more types of these in combination, etc. can be mentioned.

In addition, the resin film may contain additives such as ultraviolet absorbers, antistatic agents, light stabilizers, antioxidants, resin stabilizers, fillers, and colorants (pigments, dyes, etc.) along with the resin component.

The resin film may be a colored resin film.

The colored resin film may be a foamed resin film in which a resin layer is foamed for coloring. Additionally, the foamed resin film is usually a colored resin film that is white and opaque. In addition, a resin film formed from a resin composition containing a filler along with a resin component also has reduced transparency due to scattering of light, resulting in a colored resin film.

Additionally, in order to color it in a desired color, it may be a colored resin film formed from a resin composition containing a desired colorant along with a resin component.

In the curable adhesive sheet of one aspect of the present invention, it is preferable that the resin film 1 constituting the first release film is a colored resin film from the viewpoint of providing a curable adhesive sheet with better handling properties.

By using the 1st peeling film comprised of a colored resin film, distinction from the 2nd peeling film becomes clear. For example, it is possible to prevent misuse by peeling off the second release film instead of peeling off the first release film during use, resulting in a curable adhesive sheet with better handling properties. Additionally, the colored resin film also includes a white resin film.

From the same viewpoint as above, it is preferable that the resin film 2 constituting the second peeling film is visually distinguishable from the resin film 1 constituting the first peeling film.

A method of enabling visual distinction is to make the resin film (1) a colored resin film and make the resin film (2) a colorless and transparent resin film, or to make the resin film (2) a colorless resin film (1). ) may be a method of using a transparent or opaque colored resin film of a different color from the above, and a method of making a mark visible to the naked eye on the surface of the resin film 2 may be used.

Among these, after peeling off the first release film and attaching the curable adhesive sheet to the adherend, it is easy to visually observe the state of the surface of the adherend through the second release film or to observe it by other optical means. , a method of making them visually distinguishable is by making the resin film (1) a colored resin film and making the resin film (2) a colorless and transparent resin film, or by using a transparent resin film of a different color from the resin film (1). Alternatively, a method using an opaque colored resin film is preferable, and a method using the resin film 2 as a colorless and transparent resin film is more preferable.

Non-silicone-based release agents that are forming materials for the release layer include, for example, rubber-based elastomer-based release agents such as olefin-based release agents, isoprene-based release agents, and butadiene-based release agents, long-chain alkyl-based release agents, alkyd-based release agents, and fluorine-based release agents. You can.

Among these, from the viewpoint of adjusting the peeling force (R1) and (R2) that satisfies the above requirements (I) to (III), the peeling layer used for forming at least one of the first peeling film and the second peeling film It is preferable that the non-silicone-based release agent is an alkyd-based release agent, and it is more preferable that the non-silicone-based release agent used in forming the release layers of both the first release film and the second release film is an alkyd-based release agent.

In the curable adhesive sheet of one aspect of the present invention, from the viewpoint of adjusting the peel force (R1) to a range that satisfies the above requirement (I), the thickness (T1) of the first release film is preferably 10 μm or more. , more preferably 20 μm or more, further preferably 30 μm or more, and preferably 200 μm or less, more preferably 100 μm or less, further preferably 70 μm or less, even more preferably 45 μm. It is as follows.

In the curable adhesive sheet of one aspect of the present invention, from the viewpoint of adjusting the peel force (R2) to a range that satisfies the above requirement (III), the thickness (T2) of the second release film is preferably 30 μm or more. , more preferably 35 μm or more, and preferably 270 μm or less, more preferably 210 μm or less, and even more preferably 140 μm or less.

Additionally, from the viewpoint of producing a curable adhesive sheet that satisfies the above requirements (II) and (IIa), the thickness (T2) of the second release film is preferably 47 μm or more, more preferably 55 μm or more, and even more preferably Typically, it is 65 ㎛ or more.

In the curable adhesive sheet of one aspect of the present invention, from the viewpoint of forming a curable adhesive sheet that satisfies the above requirements (II) and (IIa), the thickness of the first release film (T1) and the thickness of the second release film (T2) ) The ratio [(T1)/(T2)] is preferably 0.15 or more, more preferably 0.20 or more, further preferably 0.25 or more, and preferably 1.00 or less, more preferably 0.90 or less, More preferably, it is 0.80 or less.

[Curable adhesive layer]

The curable adhesive layer of the curable adhesive sheet of one aspect of the present invention can form a cured product having a dielectric loss tangent of 0.01 or less at 23°C and 1 GHz.

The dielectric loss tangent at 23°C and 1 GHz of the cured product that can be formed is 0.01 or less, but is preferably 0.005 or less, and more preferably 0.002 or less.

In addition, the dielectric loss tangent of the cured product at 23°C and 1 GHz is not particularly limited by the lower limit, but is preferably 0.00005 or more, more preferably 0.0001 or more.

In addition, in this specification, the dielectric loss tangent of the cured product means a value measured based on the method described in the Examples described later.

The method for curing the curable adhesive layer may be a thermal curing method or a photo curing method, and can be appropriately selected depending on the intended use. For example, when the curable adhesive sheet of one aspect of the present invention is used as a coverlay sheet to form a cured product for protecting a circuit board, a thermal curing method is preferable.

In the curable adhesive sheet of one aspect of the present invention, the thickness of the curable adhesive layer is preferably 3.0 μm or more, more preferably from the viewpoint of forming a cured product having a thickness sufficient to protect the circuit board. It is 5.0 ㎛ or more, more preferably 10 ㎛ or more, even more preferably 15 ㎛ or more, and preferably 60 ㎛ or less, more preferably 45 ㎛ or less.

The curable adhesive layer of the curable adhesive sheet of one aspect of the present invention can be formed from a curable adhesive composition containing binder resin (A) (hereinafter also referred to as “component (A)”).

The curable adhesive composition used in one aspect of the present invention has the viewpoint of forming a curable adhesive sheet adjusted to satisfy the above requirements (I) or (III), and forming a cured product with improved adhesive strength and low dielectric properties. From the viewpoint of forming a composition that can be used, it is preferable to further contain polyphenylene ether resin (B) (hereinafter also referred to as “component (B)”), and together with components (A) and (B), the terminal It is more preferable to further contain a polyfunctional compound (C) (hereinafter also referred to as “component (C)”) having two or more unsaturated hydrocarbon groups having a double bond.

In addition, the curable adhesive composition used in one aspect of the present invention includes a cationic polymerization initiator (D) (hereinafter also referred to as “component (D)”) and a crosslinking agent capable of reacting with the above reactive functional group of component (A) ( It is preferable to further contain one or more types selected from E) (hereinafter also referred to as “component (E)”) and silane coupling agent (F) (hereinafter also referred to as “component (F)”).

Additionally, the curable adhesive composition used in one aspect of the present invention may contain additives other than these components (A) to (F) to the extent that they do not impair the effects of the present invention.

In the curable adhesive composition used in one aspect of the present invention, from the viewpoint of forming a curable adhesive sheet adjusted to satisfy the above requirements (I) or (III), and a curable adhesive layer with improved adhesive strength and low dielectric properties, or From the viewpoint of forming a composition capable of forming the cured product, the total content of component (A) and component (B) is preferably 50% with respect to the total amount (100% by mass) of the active ingredients of the curable adhesive composition. mass% or more, more preferably 60 mass% or more, further preferably 70 mass% or more, even more preferably 75 mass% or more, and preferably 100 mass% or less, more preferably 99.90 mass%. Hereinafter, it may be more preferably 99.00 mass% or less, and even more preferably 95.00 mass% or less.

From the above viewpoint, in the curable adhesive composition used in one aspect of the present invention, the total content of component (A), component (B), component (C), and component (D) is an active ingredient of the curable adhesive composition. With respect to the total amount (100 mass%), it is preferably 60 mass% or more, more preferably 75 mass% or more, further preferably 90 mass% or more, and is usually 100 mass% or less, and is 99.70 mass%. % or less, or 90 mass% or less.

From the above viewpoint, in the curable adhesive composition used in one aspect of the present invention, the sum of component (A), component (B), component (C), component (D), component (E), and component (F) The content is preferably 60% by mass or more, more preferably 75% by mass or more, and still more preferably 90% by mass or more, based on the total amount (100% by mass) of the active ingredients of the curable adhesive composition. It is usually 100 mass% or less, and may be 99.70 mass% or less, or 90 mass% or less.

Hereinafter, details of each component contained in the curable adhesive composition used in one aspect of the present invention will be described.

＜Component (A): Binder resin＞

The curable adhesive composition used in one aspect of the present invention preferably contains binder resin (A). By containing the binder resin (A), the composition becomes excellent in adhesive strength when used as a cured product and can form a curable adhesive layer with good shape stability.

Binder resin (A) may be used individually, or two or more types may be used together.

In the curable adhesive composition used in one aspect of the present invention, the content of component (A) is preferably 35% by mass or more, more preferably 35% by mass or more, based on the total amount (100% by mass) of the active ingredients of the curable adhesive composition. Preferably it is 45 mass% or more, more preferably 55 mass% or more, and preferably 90 mass% or less, more preferably 80 mass% or less, and even more preferably 75 mass% or less.

The number average molecular weight (Mn) of the binder resin (A) used in one aspect of the present invention is preferably set to a composition capable of forming a curable adhesive layer with improved film forming properties and good shape stability. is 10,000 or more, more preferably 25,000 or more, and still more preferably 35,000 or more, and when the composition is in the form of a solution, the composition has good solubility with the diluting solvent of component (A) and has excellent applicability. From the viewpoint, it is preferably 150,000 or less, more preferably 100,000 or less, and even more preferably 70,000 or less.

Examples of the binder resin (A) include polyolefin-based resin, phenoxy-based resin, polyimide-based resin, polyamidoimide-based resin, polyvinyl butyral-based resin, polycarbonate-based resin, and styrene-based resin.

Among these, the binder resin (A) used in one aspect of the present invention is a polyolefin-based composition from the viewpoint of forming a composition capable of forming a cured product with excellent dielectric properties in a high frequency region (for example, 1 GHz or more). It is preferable that it contains resin.

The polyolefin-based resin may be a polymer having structural units derived from olefin-based monomers, and may be a polymer composed only of structural units derived from olefin-based monomers, or may include structural units derived from olefin-based monomers and a monomer that can be copolymerized with olefin-based monomers. It may be a copolymer having structural units derived from .

The olefinic monomer constituting the polyolefin resin includes α-olefins having 2 or more carbon atoms, preferably α-olefins having 2 to 8 carbon atoms, and ethylene, propylene, 1-butene, isobutylene, and 1-hexene. At least one type selected from ethylene and propylene is more preferable.

These olefinic monomers may be used individually, or two or more types may be used together.

In addition, examples of monomers that constitute the polyolefin resin and can be copolymerized with olefin monomers include vinyl acetate, (meth)acrylic acid ester, and styrene. These monomers may be used individually, or two or more types may be used together.

The polyolefin resin used in one aspect of the present invention specifically includes very low density polyethylene (VLDPE), low density polyethylene (LDPE), medium density polyethylene (MDPE), high density polyethylene (HDPE), linear low density polyethylene, and polyethylene. Propylene (PP), ethylene-propylene copolymer, olefin elastomer (TPO), ethylene-vinyl acetate copolymer (EVA), ethylene-(meth)acrylic acid copolymer, ethylene-(meth)acrylic acid ester copolymer, etc. there is.

The binder resin (A) used in one aspect of the present invention is a composition capable of forming a curable adhesive layer with improved film forming properties and good shape stability, and provides a cured product with improved low dielectric properties. From the viewpoint of forming a composition that can be formed and reducing the peeling force when peeling the first release film or the second release film from the curable adhesive layer, it is preferable to include a binder resin having a reactive functional group, and the reactive functional group It is more preferable to contain at least one type selected from a polyolefin resin having a and a styrene resin having a reactive functional group, and it is more preferable to contain at least a polyolefin resin (A1) having a reactive functional group.

In the curable adhesive composition used in one aspect of the present invention, the content ratio of polyolefin resin (A1) is included in the curable adhesive composition from the viewpoint of forming a composition capable of forming a cured product with more excellent low dielectric properties. It is preferably 50 to 100 mass%, more preferably 70 to 100 mass%, and still more preferably 85 to 100 mass%, based on the total amount (100 mass%) of component (A).

Examples of the reactive functional group that the binder resin (A) has include a carboxyl group, a group having a carboxylic acid anhydride structure, a group having a carboxylic acid ester structure, a hydroxyl group, an epoxy group, an amide group, an ammonium group, a nitrile group, an amino group, Examples include an imide group, an isocyanate group, an acetyl group, a thiol group, a sulfone group, a phosphonic group, a nitro group, a halogen atom, and an alkoxysilyl group.

The reactive functional group that the binder resin (A) has may be composed of one type alone or in a combination of two or more types.

Among these, the reactive functional group that the binder resin (A) has is a carboxy group, a group having a carboxylic acid anhydride structure, an epoxy group, an amide group, an ammonium group, a nitrile group, an amino group, an imide group, an isocyanate group, an acetyl group, a thiol group, and an ether. A group selected from the group consisting of a group, a thioether group, a sulfone group, a phosphone group, a nitro group, a urethane group, a halogen atom, and an alkoxysilyl group is preferred, from the viewpoint of forming a composition capable of forming a cured product with superior adhesive strength, and From the viewpoint of lowering the peeling force when peeling the first release film or the second release film from the curable adhesive layer, a group selected from a carboxyl group and a group having a carboxylic acid anhydride structure is more preferable, and the adhesive strength is also low. From the viewpoint of creating a composition capable of forming a cured product with better dielectric properties, a group having a carboxylic acid anhydride structure is more preferable.

The binder resin (A) used in one aspect of the present invention may be a modified resin obtained by modifying the resin forming the main chain using a denaturing agent to introduce the above-mentioned reactive functional groups.

Specific modified resins include, for example, acid-modified resins into which acid groups are introduced and resins into which hydroxyl groups are introduced, from the viewpoint of forming a composition capable of forming a cured product with superior adhesive strength, and a first release film. Alternatively, from the viewpoint of lowering the peeling force when peeling the second release film from the curable adhesive layer, an acid-modified resin into which an acid group is introduced is preferable, and can form a cured product that has better adhesive strength and low dielectric properties. From the viewpoint of creating a composition with an acid anhydride structure, an acid anhydride-modified resin into which an acid anhydride structure is introduced is more preferable.

Acid-modified resin or acid anhydride-modified resin (hereinafter also referred to as “unsaturated carboxylic acid, etc.”) is, for example, formed by reacting an unsaturated carboxylic acid, etc. with a resin that becomes the main chain to form a carboxyl group or carboxylic acid anhydride structure. It is obtained by introducing and modifying the graft.

There is no particular limitation on the method of introducing unsaturated carboxylic acid, etc. into the resin. For example, in the presence of a radical generator such as organic peroxides or azonitrile, the resin and unsaturated carboxylic acid, etc. are mixed at a temperature equal to or higher than the melting point of the resin. A method of reacting by heating and melting, or a method of dissolving the resin and unsaturated carboxylic acid in an organic solvent and then reacting by heating and stirring in the presence of a radical generator, can be mentioned.

Examples of unsaturated carboxylic acids include maleic acid, fumaric acid, itaconic acid, citraconic acid, glutaconic acid, tetrahydrophthalic acid, and aconitic acid.

Unsaturated carboxylic acid anhydrides include, for example, maleic anhydride, itaconic anhydride, glutaconic anhydride, citraconic anhydride, aconitic anhydride, norbornedicarboxylic anhydride, tetrahydrophthalic anhydride, etc. I can hear it.

These may be used individually, or two or more types may be used together.

Among these, maleic anhydride is preferable from the viewpoint of forming a composition that can form a cured product with superior adhesive strength and low dielectric properties.

The amount of unsaturated carboxylic acid added to react with the resin is preferably 0.1 to 5 parts by mass per 100 parts by mass of the resin from the viewpoint of forming a composition capable of forming a cured product with superior adhesive strength and low dielectric properties. , More preferably 0.2 to 3 parts by mass, Still more preferably 0.2 to 1 parts by mass.

<Component (B): polyphenylene ether resin>

The curable adhesive composition used in one aspect of the present invention is capable of forming a cured product with improved adhesive strength and low dielectric properties from the viewpoint of forming a curable adhesive sheet adjusted to satisfy the above requirements (I) or (III). From the viewpoint of providing a stable composition, it is preferable to contain polyphenylene ether resin (B).

In addition, polyphenylene ether resin (B) may be used individually, or two or more types may be used together.

In the curable adhesive composition used in one aspect of the present invention, the content of component (B) is preferably 5 parts by mass or more, more preferably 12 parts by mass, based on 100 parts by mass of the total amount of component (A). More preferably, it is 17 parts by mass or more, and is also preferably 80 parts by mass or less, more preferably 60 parts by mass or less, and even more preferably 40 parts by mass or less.

One aspect of the present invention from the viewpoint of providing a curable adhesive sheet adjusted to satisfy the above requirements (I) or (III), and from the viewpoint of providing a composition capable of forming a cured product with improved adhesive strength and low dielectric properties. The number average molecular weight (Mn) of the polyphenylene ether resin (B) used is preferably 1500 or more, more preferably 1700 or more, and still more preferably 1900 or more, and the composition is in the form of a solution. In this case, from the viewpoint of improving the solubility of component (B) with the diluting solvent and creating a composition with excellent applicability, it is preferably 7000 or less, more preferably 5500 or less, and still more preferably 4000 or less.

The polyphenylene ether resin (B) used in one aspect of the present invention may be a resin having a structural unit represented by at least one of the following general formulas (b-i) and (b-ii) in the main chain.

[Formula 1]

In the general formula (bi) or formula (b-ii), R ^a1 and R ^a2 are each independently a halogen atom (fluorine atom, chlorine atom, bromine atom, or iodine atom), an alkyl group having 1 to 6 carbon atoms, or a phenyl group, preferably an alkyl group with 1 to 6 carbon atoms, more preferably an alkyl group with 1 to 4 carbon atoms, even more preferably an alkyl group with 1 to 3 carbon atoms, even more preferably a methyl group or an ethyl group, and particularly preferably a methyl group. do.

Additionally, alkyl groups having 1 to 6 carbon atoms that can be selected as R ^a1 and R ^a2 include, for example, methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, t-butyl group, s- Butyl group, isobutyl group, n-pentyl group, n-hexyl group, etc. are mentioned.

m1 and m2 are each independently an integer of 0 to 4, preferably an integer of 0 to 3, more preferably an integer of 0 to 2, and even more preferably 2.

From the viewpoint of providing a curable adhesive sheet adjusted to satisfy the above requirements (I) or (III), and a composition capable of forming a cured product with improved adhesive strength while maintaining good low dielectric properties, the present invention The polyphenylene ether resin (B) used in one aspect of is preferably a resin having a skeleton represented by the following formula (b-1) as the main chain.

[Formula 2]

In the general formula (b-1), R ^a1 and R ^a2 , and m1 and m2 are the same as the definitions in the general formula (bi) or (b-ii), and the preferred group type and numerical range are The same is true for .

X is a divalent organic group, and at least one hydrogen atom of the organic group may be substituted with a substituent.

p1 and p2 are each independently an integer of 0 or more, and p1 + p2 is an integer of 1 or more.

* indicates the bonding position with the terminal group.

Examples of the divalent hydrocarbon group that can be selected as Examples include alkylene groups, cycloalkenylene groups having 3 to 10 ring carbon atoms, phenylene groups, biphenylene groups, terphenylene groups, naphthylene groups, and groups formed by combining two or more of these groups.

In addition, the alkylene group, oxyalkylene group, and alkenylene group may be straight chain or branched chain.

In addition, the alkylene group, oxyalkylene group, and alkenylene group may have a substituent selected from a halogen atom, a phenyl group, a biphenyl group, a terphenyl group, a naphthyl group, and a cycloalkyl group having 3 to 10 carbon atoms.

Additionally, the cycloalkylene group, cycloalkenylene group, phenylene group, biphenylene group, terphenylene group, and naphthylene group include a halogen atom, an alkyl group with 1 to 6 carbon atoms, an oxyalkyl group with 1 to 6 carbon atoms, and 1 carbon atom. It may have a substituent selected from alkenyl groups of -6.

Among these, from the viewpoint of forming a composition that can form a curable adhesive sheet adjusted to satisfy the above requirements (I) or (III) and a cured product with further improved adhesive strength, It is preferable to use the group represented by -2).

[Formula 3]

In the general formula (b-2), R ^b1 and R ^b2 are each independently a halogen atom (fluorine atom, chlorine atom, bromine atom, or iodine atom), an alkyl group having 1 to 6 carbon atoms, or a C 1 to 6 alkyl group. It is an oxyalkyl group or an alkenyl group with 1 to 6 carbon atoms, preferably an alkyl group with 1 to 6 carbon atoms, more preferably an alkyl group with 1 to 4 carbon atoms, even more preferably an alkyl group with 1 to 3 carbon atoms, and a methyl group or an ethyl group. Even more preferred, a methyl group is particularly preferred.

Additionally, alkyl groups having 1 to 6 carbon atoms that can be selected as R ^b1 and R ^b2 include, for example, methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, t-butyl group, s- Butyl group, isobutyl group, n-pentyl group, n-hexyl group, etc. are mentioned.

n1 and n2 are each independently an integer of 0 to 4, preferably an integer of 0 to 3, more preferably an integer of 1 to 3, and even more preferably 3.

In the general formula (b-2), A is a single bond or a divalent hydrocarbon group.

Examples of the divalent hydrocarbon group that can be selected as A include an alkylene group with 1 to 20 carbon atoms, an oxyalkylene group with 1 to 20 carbon atoms, an alkenylene group with 1 to 20 carbon atoms, and a cyclo group with 3 to 10 ring carbon atoms. An alkylene group or a cycloalkenylene group having 3 to 10 ring carbon atoms can be mentioned.

In addition, the alkylene group, oxyalkylene group, and alkenylene group may be straight chain or branched chain.

Additionally, the hydrocarbon group selected as A may have a substituent selected from a halogen atom, an alkyl group with 1 to 6 carbon atoms, an oxyalkyl group with 1 to 6 carbon atoms, and an alkenyl group with 1 to 6 carbon atoms.

Among these, from the viewpoint of forming a composition that can form a curable adhesive sheet adjusted to satisfy the above requirements (I) or (III) and a cured product with further improved adhesive strength, A is a single bond or a carbon number. It is preferable that it is an alkylene group of 1-20 atoms, and it is more preferable that it is a single bond.

Polyphenyl used in one aspect of the present invention from the viewpoint of forming a curable adhesive sheet adjusted to satisfy the above requirements (I) or (III) and a composition capable of forming a cured product with further improved adhesive strength. The lene ether resin (B) is more preferably a resin having a skeleton represented by the following formula (b-3) as the main chain.

[Formula 4]

In the general formula (b-3), R ^a1 and R ^a2 are the same as those defined in the general formula (bi) or (b-ii), and the preferred group type and numerical range are also the same.

In addition, R ^b1 and R ^b2 are the same as the definitions in the above general formula (b-2), and the preferred types of groups and numerical ranges are also the same.

p1 and p2 are each independently an integer of 0 or more, and p1 + p2 is an integer of 1 or more.

* indicates the bonding position with the terminal group.

In addition, R ^a1 , R ^a2 , R ^b1 , and R ^b2 in the general formula (b-3) are each independently preferably an alkyl group having 1 to 6 carbon atoms, and more preferably an alkyl group having 1 to 4 carbon atoms. , an alkyl group having 1 to 3 carbon atoms is more preferable, a methyl group or an ethyl group is still more preferable, and a methyl group is particularly preferable.

The polyphenylene ether resin (B) used in one aspect of the present invention is a curable adhesive sheet adjusted to satisfy the above requirements (I) or (III), and has low dielectric properties, crosslinking properties, and heat resistance. From the viewpoint of providing a composition capable of forming an improved cured product, it is preferable that it is a polyphenylene ether resin having a vinyl group.

The vinyl group contained in the polyphenylene ether resin (B) may be one that forms part of a hydrocarbon-based substituent, such as a vinylbenzyl group or a vinylnaphthyl group. That is, the polyphenylene ether resin (B) is formed by bonding a vinyl group or a vinyl group-containing hydrocarbon group to the polyphenylene ether skeleton.

One aspect of the present invention from the viewpoint of providing a curable adhesive sheet adjusted to satisfy the above requirements (I) or (III), and a composition capable of forming a cured product with excellent low dielectric properties, crosslinking properties, and heat resistance. The polyphenylene ether resin (B) used is preferably a resin having a vinyl group or a vinyl group-containing hydrocarbon group at both ends of the main chain.

The polyphenylene ether resin (B), which has a vinyl group or a vinyl group-containing hydrocarbon group at both ends of the main chain, forms a polyphenylene ether skeleton that becomes the main chain, and then has a vinyl group or a vinyl group-containing hydrocarbon group at both ends. This can be achieved by introducing

Specifically, a difunctional phenol compound and a monofunctional phenol compound are reacted to obtain a polymer having phenolic hydroxyl groups at both ends, and then the terminal phenolic hydroxyl groups are vinylbenzyl etherified using 4-(chloromethyl)styrene. , a polyphenylene ether resin (B) having vinylbenzyl groups at both ends of the polyphenylene ether skeleton can be obtained.

The polyphenylene ether resin (B) used in one aspect of the present invention is preferably a compound represented by the following general formula (b-4).

[Formula 5]

p1 and p2 are each independently an integer of 0 or more, and p1 + p2 is an integer of 1 or more.

As the polyphenylene ether resin (B) used in one aspect of the present invention, a commercially available product may be used. Commercially available products include, for example, OPE-2St (a compound represented by the general formula (b-4) above) manufactured by Mitsubishi Gas Chemical Co., Ltd.

<Component (C): Multifunctional compound>

The curable adhesive composition used in one aspect of the present invention preferably contains a polyfunctional compound (C) having two or more unsaturated hydrocarbon groups having a double bond at the terminal. In addition, the polyfunctional compound (C) in the present invention excludes compounds corresponding to component (A) and component (B).

By using a composition containing the polyfunctional compound (C) together with the polyphenylene ether resin (B) described above, a cured product with improved low dielectric properties and adhesive strength in a good balance can be formed. In particular, since the polyfunctional compound (C) has two or more unsaturated hydrocarbon groups, a crosslinked structure is formed in the resulting cured product, thereby forming a cured product with further improved adhesive strength.

In addition, the polyfunctional compound (C) may be used individually, or two or more types may be used together.

In the curable adhesive composition used in one aspect of the present invention, the content of component (C) is such that the composition can form a cured product with excellent low dielectric properties, based on 100 parts by mass of the total amount of component (A). From the viewpoint of producing a curable adhesive sheet with improved sticking properties, the content of component (C) is preferably 10 parts by mass or more, more preferably 15 parts by mass or more, and even more preferably 20 parts by mass or more. As the peel force (R1) and (R2) increase, the peel force (R1) and the peel force (R2) tend to increase, so from the viewpoint of adjusting the curable adhesive sheet to satisfy the above requirements (I) or (III), preferably 80 parts by mass. Below, more preferably 60 parts by mass or less, further preferably 40 parts by mass or less.

In the curable adhesive composition used in one aspect of the present invention, from the viewpoint of forming a composition capable of forming a cured product with improved low dielectric properties, adhesive strength, and heat resistance in a good balance, component (B) and component (C) ) The content ratio [(B)/(C)] is a mass ratio, preferably 15/85 or more, more preferably 30/70 or more, and preferably 85/15 or less, more preferably It is less than 70/30.

In the curable adhesive composition used in one aspect of the present invention, the total content of component (B) and component (C) satisfies the above requirements (I) or (III) with respect to 100 parts by mass of the total amount of component (A). From the viewpoint of providing a curable adhesive sheet adjusted to satisfy Preferably it is 75 parts by mass or less, more preferably 65 parts by mass or less, and preferably 15 parts by mass or more, more preferably 25 parts by mass or more, and even more preferably 35 parts by mass or more.

The number of carbon atoms of each unsaturated hydrocarbon group in the polyfunctional compound (C) used in one aspect of the present invention is preferably 2 to 7, more preferably 2 to 4, and still more preferably 2 to 3. am.

In addition, the unsaturated hydrocarbon group includes, for example, vinyl group, allyl group, 3-butenyl group, 4-pentenyl group, 5-hexenyl group, isopropenyl group, 1-methyl-2-propenyl group, and vinylbenzyl group. , vinyl naphthyl group, etc.

Among these, it is preferable that the unsaturated hydrocarbon group of the polyfunctional compound (C) is an allyl group.

The number of unsaturated hydrocarbon groups in the polyfunctional compound (C) used in one aspect of the present invention is 2 or more, but the cross-linked structure is moderately coarse and the composition can form a cured product with suppressed occurrence of cracks. From the viewpoint of and from the viewpoint of forming a composition that can suppress curing shrinkage in the adhesion process from the curable adhesive layer to the cured product and reduce warpage of the plate-shaped member such as the circuit board that is the adherend, preferably 2 to 4, More preferably, it is 2 to 3, and even more preferably, it is 2.

From the viewpoint of forming a composition capable of forming a cured product with improved low dielectric properties and adhesive strength in a better balance, the polyfunctional compound (C) used in one aspect of the present invention has two or more unsaturated hydrocarbon groups and Together, it is preferable that it is a polyfunctional compound that further has a saturated hydrocarbon group.

From the above viewpoint, the number of saturated hydrocarbon groups in the polyfunctional compound (C) used in one aspect of the present invention is preferably 1 to 4, more preferably 1 to 2, and still more preferably 1.

Examples of the saturated hydrocarbon group include an alkyl group and an alkyl group substituted with an alkoxy group.

Examples of the alkyl group include methyl, ethyl, n-propyl, isopropyl, n-butyl, t-butyl, s-butyl, isobutyl, n-pentyl, and n-hexyl. , n-heptyl group, n-octyl group, n-nonyl group, n-decyl group, n-undecyl group, n-dodecyl group, n-tridecyl group, n-tetradecyl group, n-pentadecyl group, etc. I can hear it.

The carbon number of the alkyl group is preferably 1 to 20, more preferably 4 to 18, further preferably 6 to 16, and even more preferably 8 to 15.

Examples of the alkyl group substituted with the alkoxy group include methoxymethyl group, ethoxymethyl group, 2-methoxyethoxymethyl group, and benzyloxymethyl group.

The carbon number of the alkyl group substituted with the alkoxy group is preferably 2 to 15, more preferably 2 to 12, and still more preferably 3 to 10.

The polyfunctional compound (C) used in one aspect of the present invention preferably contains the polyfunctional compound (C1) having two unsaturated hydrocarbon groups.

As described above, the composition containing the polyfunctional compound (C1) having two unsaturated hydrocarbon groups forms a cured product in which the occurrence of cracks is suppressed and the warping of plate-shaped members such as circuit boards as adherends is reduced. In addition to being able to form a cured product with further improved low dielectric properties and adhesive strength, it can be a composition capable of forming a cured product.

From the above viewpoint, the polyfunctional compound (C1) is more preferably a polyfunctional compound having two unsaturated hydrocarbon groups and at least one saturated hydrocarbon group.

From the above viewpoint, in the curable adhesive composition used in one aspect of the present invention, the content ratio of the polyfunctional compound (C1) is relative to the total amount (100% by mass) of component (C) contained in the curable adhesive composition. , preferably 50 to 100 mass%, more preferably 70 to 100 mass%, further preferably 80 to 100 mass%, and even more preferably 90 to 100 mass%.

The polyfunctional compound (C) used in one aspect of the present invention is preferably a polyfunctional compound having a heterocyclic skeleton. By including a polyfunctional compound having a heterocyclic skeleton, a composition can be used to form a cured product with further improved low dielectric properties and adhesive strength.

Specific heterocyclic skeletons include isocyanurate skeleton and glycoluryl skeleton.

Polyfunctional compounds (C) used in one aspect of the present invention include compounds having an isocyanurate skeleton represented by the following general formula (c-1), and compounds having a glycoluril skeleton represented by the following general formula (c-2). Compounds may be mentioned.

[Formula 6]

In the general formula (c-1), R ¹¹ to R ¹³ are each independently an unsaturated hydrocarbon group or a saturated hydrocarbon group having a double bond at the terminal, and at least two of R ¹¹ to R ¹³ are the above-described groups. It is an unsaturated hydrocarbon group.

Moreover, in the general formula (c-2), R ²¹ to R ²⁶ each independently represent a hydrogen atom, an unsaturated hydrocarbon group having a double bond at the terminal, or a saturated hydrocarbon group, and at least one of R ²¹ to R ²⁶ Two are the unsaturated hydrocarbon groups mentioned above.

Specific examples of unsaturated hydrocarbon groups and saturated hydrocarbon groups that can be selected as R ¹¹ to R ¹³ and R ²¹ to R ²⁶ are as described above, and the preferred range of carbon numbers is also as described above.

It can be a composition that can form a cured product with suppressed crack generation and reduced warping of plate-shaped members such as circuit boards as adherends, and can also form a cured product with further improved low dielectric properties and adhesive strength. From the viewpoint of forming a composition, the multifunctional compound (C) used in one aspect of the present invention preferably contains a compound having an isocyanurate skeleton represented by the above general formula (c-1), and the following general formula: It is more preferable to include compound (C11) having an isocyanurate skeleton represented by formula (c-11).

[Formula 7]

In the general formula (c-11), R ^a is a saturated hydrocarbon group, and specific examples are as described above.

Among these, it is preferable that R ^a is an alkyl group. The carbon number of the alkyl group is preferably 1 to 20, more preferably 4 to 18, further preferably 6 to 16, and even more preferably 8 to 15.

From the above viewpoint, in the curable adhesive composition used in one aspect of the present invention, the content ratio of compound (C11) is preferable with respect to the total amount (100% by mass) of component (C) contained in the curable adhesive composition. It is preferably 50 to 100 mass%, more preferably 70 to 100 mass%, further preferably 80 to 100 mass%, and even more preferably 90 to 100 mass%.

In addition, the polyfunctional compound (C) used in one aspect of the present invention may be a commercially available product.

Specific commercial products include, for example, L-DAIC (product name, manufactured by Shikoku Chemicals Co., Ltd., a compound represented by the general formula (c-11) above), TAIC (registered trademark) (product name, manufactured by Mitsubishi Chemical Co., Ltd., the above general formula) Examples include compounds in (c-1) in which R ¹¹ to R ¹³ are allyl groups) and TA-G (product name, manufactured by Shikoku Chemical Industry Co., Ltd., a compound represented by the above general formula (c-2)).

The molecular weight (formula weight) of the polyfunctional compound (C) used in one aspect of the present invention is such that the molecular weight of component (C) is low from the viewpoint of making the composition easy to form a cured product with desired physical properties. Since the peel force (R1) and the peel force (R2) tend to increase as the number increases, from the viewpoint of adjusting the curable adhesive sheet to satisfy the above requirements (I) or (III), it is preferably 200 or more. Preferably it is 230 or more, more preferably 270 or more, and from the viewpoint of making the composition easy to form a curable adhesive layer that is easy to stick at room temperature, preferably 1000 or less, more preferably 800 or less, even more preferably is less than 500.

The boiling point of the multifunctional compound (C) used in one aspect of the present invention is preferably 175 to 350°C, more preferably 200 to 300°C.

Moreover, the 5% weight loss temperature of the polyfunctional compound (C) used in one aspect of the present invention is preferably 175 to 350°C, more preferably 200 to 300°C.

In addition, from the viewpoint of forming a composition capable of forming a cured product with excellent low dielectric properties and forming a curable adhesive layer that is easy to stick at room temperature, the multifunctional compound used in one aspect of the present invention ( C) is preferably a compound that is liquid at 25°C.

In addition, in this specification, “a compound that is liquid at 25°C” refers to a compound that has fluidity at 25°C, and specifically, the viscosity measured at 25°C and 1.0 rpm using an E-type viscometer is 2. It refers to a compound that is ~ 10000 mPa·s.

<Component (D): Cationic polymerization initiator>

The curable adhesive composition used in one aspect of the present invention preferably further contains a cationic polymerization initiator (D).

By using a curable adhesive composition containing a cationic polymerization initiator (D), the polymerization reaction of component (B) and component (C) can sufficiently proceed, and the storage stability of the curable adhesive layer formed can be improved.

In addition, the cationic polymerization initiator (D) may be used individually, or 2 or more types may be used together.

In the curable adhesive composition used in one aspect of the present invention, the content of component (D) is the polymerization of component (B) and component (C) relative to 100 parts by mass of the total amount of component (B) and component (C). From the viewpoint of allowing the reaction to proceed sufficiently and forming a composition capable of forming a curable adhesive layer with improved storage stability, the amount is preferably 0.01 part by mass or more, more preferably 0.05 part by mass or more, and even more preferably 0.10 part by mass or more. , more preferably 0.15 parts by mass or more, further preferably 0.20 parts by mass or more, even more preferably 0.25 parts by mass or more, particularly preferably 0.30 parts by mass or more, and more preferably 6.0 parts by mass or less. Preferably 5.0 parts by mass or less, more preferably 3.0 parts by mass or less, even more preferably 2.0 parts by mass or less, even more preferably 1.5 parts by mass or less, even more preferably 1.0 parts by mass or less, particularly preferably 0.70 parts by mass or less. It is less than part by mass.

The cationic polymerization initiator (D) used in one aspect of the present invention may be a thermal cationic polymerization initiator or a photo cationic polymerization initiator. However, from the viewpoint that polymerization can be performed in a simple process, the thermal cationic polymerization initiator is used. is desirable.

The thermal cationic polymerization initiator used in one aspect of the present invention is a compound capable of generating a cationic species that initiates polymerization by heating, for example, sulfonium salt, quaternary ammonium salt, phosphonium salt, diazo. nium salts, iodonium salts, etc. may be mentioned.

These thermal cationic polymerization initiators may be used individually or may be used in combination of two or more types.

Sulfonium salts include, for example, triphenylsulfonium tetrafluoroborate, triphenylsulfonium hexafluoroantimonate, triphenylsulfonium hexafluoroarcinate, and tris(4-methoxyphenyl)sulfonium. Hexafluoroarcinate, diphenyl (4-phenylthiophenyl) sulfonium hexafluoroarcinate, etc. are mentioned.

Additionally, commercial products can be used as the sulfonium salt, for example, Adeka Opton SP-150, Adeka Opton SP-170, Adeka Opton CP-66, and Adeka Opton CP-77 (above, manufactured by ADEKA Co., Ltd.) , San Aid SI-60L, San Aid SI-80L, San Aid SI-100L, San Aid SI-B2A, San Aid SI-B3 (manufactured by Sanshin Chemical Industry Co., Ltd.), CYRACURE UVI-6974, CYRACURE UVI-6990 ( (above, manufactured by Union Carbide), UVI-508, UVI-509 (above, manufactured by General Electric Company), FC-508, FC-509 (above, manufactured by Minnesota Mining & Manufacturing Company), CD-1010 , CD-1011 (manufactured by Sartomer Co., Ltd.), and CI series products (manufactured by Nippon Soda Co., Ltd.).

Quaternary ammonium salts include, for example, tetrabutylammonium tetrafluoroborate, tetrabutylammonium hexafluorophosphate, tetrabutylammonium hydrogen sulfate, tetraethylammonium tetrafluoroborate, and tetraethylammonium p-toluenesulfonate. , N,N-dimethyl-N-benzylanilinium hexafluoroantimonate, N,N-dimethyl-N-benzylanilinium tetrafluoroborate, N,N-dimethyl-N-benzylpyridinium hexafluoroantimonate Monate, N,N-diethyl-N-benzyltrifluoromethanesulfonate, N,N-dimethyl-N-(4-methoxybenzyl)pyridiniumhexafluoroantimonate, N,N-diethyl -N-(4-methoxybenzyl)toluidinium hexafluoroantimonate, etc. are mentioned.

Examples of phosphonium salts include ethyltriphenylphosphonium hexafluoroantimonate and tetrabutylphosphonium hexafluoroantimonate.

Examples of diazonium salts include AMERICURE (manufactured by American Can Co., Ltd.), ULTRASET (manufactured by Adeka Co., Ltd.), and the like.

Iodonium salts include, for example, diphenyliodonium hexafluoroarsinate, bis(4-chlorophenyl)iodonium hexafluoroarsinate, and bis(4-bromophenyl)iodonium. Hexafluoroarcinate, phenyl (4-methoxyphenyl) iodonium hexafluoroarcinate, etc. are mentioned.

Additionally, commercially available iodonium salts can be used, such as UV-9310C (manufactured by Toshiba Silicone Co., Ltd.), Photoinitiator2074 (manufactured by Rhone Poulenc), UVE series products (manufactured by General Electric), and FC series. products (manufactured by Minnesota Mining & Manufacturing Company), etc.

When the curable adhesive composition of one aspect of the present invention contains a cationic polymerization initiator (D), at least a part of the cationic polymerization initiator (D) is the peak of the exothermic peak obtained by performing differential scanning calorimetry under the following conditions. A high-temperature reactive thermal cationic polymerization initiator having a top temperature exceeding 120°C may be used.

(Differential scanning calorimetry conditions)

A mixture consisting of 0.1 part by mass of the cationic polymerization initiator to be measured, 100 parts by mass of bisphenol A diglycidyl ether, and 0.1 part by mass of γ-butyrolactone was used as a measurement sample, and the temperature was from 30°C to 300°C. Differential scanning calorimetry is performed at a temperature increase rate of 10°C/min to measure the peak temperature of the exothermic peak.

Commercially available high-temperature reactive thermal cationic polymerization initiators include, for example, San-Aid SI-B3, San-Aid SI-B4, San-Aid SI-B5, and San-Aid SI-150 (all manufactured by Sanshin Chemical Industry Co., Ltd.). You can.

<Reactive curing agents other than the cationic polymerization initiator (D)>

The curable adhesive composition used in one aspect of the present invention contains a cationic polymerization initiator instead of or together with the cationic polymerization initiator (D), to the extent that the effect of the present invention is not impaired. It may contain a reactive hardener other than (D).

In the curable adhesive composition used in one aspect of the present invention, the content of the other reactive curing agent is 0 to 90 parts by mass, 0 to 50 parts by mass, or 0 to 40 parts by mass, based on 100 parts by mass of the total amount of component (D). parts, 0 to 30 parts by mass, 0 to 20 parts by mass, 0 to 10 parts by mass, 0 to 5.0 parts by mass, 0 to 2.0 parts by mass, 0 to 1.0 parts by mass, 0 to 0.10 parts by mass, 0 to 0.010 parts by mass, Alternatively, it may be 0 to 0.0010 parts by mass.

On the other hand, when the curable adhesive composition of one aspect of the present invention does not contain the cationic polymerization initiator (D), the content of the other reactive curing agent is, with respect to 100 parts by mass of the total amount of component (B) and component (C), It may be 0.01 parts by mass or more, 0.05 parts by mass or more, 0.10 parts by mass or more, 0.15 parts by mass or more, 0.20 parts by mass or more, 0.25 parts by mass or more, or 0.30 parts by mass or more, or 6.0 parts by mass or less, 5.0 parts by mass or less. , it may be 3.0 parts by mass or less, 2.0 parts by mass or less, 1.5 parts by mass or less, 1.0 parts by mass or less, or 0.70 parts by mass or less.

Examples of reactive curing agents other than the cationic polymerization initiator (D) include amine compounds such as benzylmethylamine and 2,4,6-trisdimethylaminomethylphenol; Imidazole compounds such as 2-methylimidazole, 2-ethyl-4-methylimidazole, and 2-heptadecylimidazole; Lewis acids such as boron trifluoride/monoethylamine complex and boron trifluoride/piperazine complex; Peroxides such as di(t-butylperoxy)diisopropylbenzene; etc. can be mentioned.

＜Component (E): Cross-linking agent＞

When the curable adhesive composition used in one aspect of the present invention contains a binder resin having a reactive functional group as component (A), it is preferable to further contain a crosslinking agent (E) capable of reacting with the reactive functional group.

By using a composition that further contains a crosslinking agent (E) in addition to the component (A), a curable adhesive layer with a high effect of suppressing the seepage of the adhesive component can be formed. In other words, in the process of forming a curable adhesive layer from a coating film formed from a curable adhesive composition, a crosslinking structure is formed within the coating film by reacting with the above-mentioned reactive functional group of the crosslinking agent (E) and the binder resin (A), and it fluidizes even when heated. A hard-to-cure adhesive layer can be formed. As a result, in the adhesion process of attaching the formed curable adhesive layer to an adherend such as a circuit board and curing it to bond it to the adherend, the phenomenon of adhesive components oozing out from the edges becomes more difficult to occur. Also, from the viewpoint of producing a curable adhesive sheet adjusted to satisfy the above requirements (I) and (III), it is preferable to use a composition containing a crosslinking agent (E).

In addition, the crosslinking agent (E) may be used individually, or two or more types may be used together.

In the curable adhesive composition used in one aspect of the present invention, the content of component (E) is preferably 0.01 part by mass or more, more preferably 0.03 part by mass, based on 100 parts by mass of the total amount of component (A). or more, more preferably 0.05 parts by mass or more, more preferably 0.07 parts by mass or more, even more preferably 0.10 parts by mass or more, even more preferably 0.15 parts by mass or more, even more preferably 0.20 parts by mass or more. Preferably it is 0.25 parts by mass or more, particularly preferably 0.30 parts by mass or more, and preferably 10.0 parts by mass or less, more preferably 8.0 parts by mass or less, more preferably 6.0 parts by mass or less, and more preferably 5.0 parts by mass or less. Parts by mass or less, more preferably 4.0 parts by mass or less, more preferably 3.0 parts by mass or less, even more preferably 2.5 parts by mass or less, even more preferably 2.0 parts by mass or less, particularly preferably 1.5 parts by mass or less. .

The molecular weight of the cross-linking agent (E) used in one aspect of the present invention increases the probability of reaction with component (A), makes it easy to form a cross-linked structure, and forms a curable adhesive layer with a higher effect of suppressing exudation of the adhesive component. From the viewpoint of forming a composition that can be used, it is preferably 1000 or less, more preferably 800 or less, even more preferably 700 or less, even more preferably 600 or less, especially preferably 500 or less, and the curable adhesive layer. By heating in the drying process to form, the cross-linking agent (E) is adjusted to remain in the curable adhesive layer, and from the viewpoint of creating a composition that can exhibit the effect of adding the cross-linking agent (E), preferably 100 or more, more preferably 150 or more, further preferably 200 or more, even more preferably 250 or more, especially preferably 300 or more.

The crosslinking agent (E) used in one aspect of the present invention is appropriately selected depending on the type of reactive functional group possessed by component (A), for example, an isocyanate-based crosslinking agent, an epoxy-based crosslinking agent, a metal chelate-based crosslinking agent, and an aziridine-based crosslinking agent. etc. can be mentioned.

Among these, from the viewpoint of storage stability, the crosslinking agent (E) used in one aspect of the present invention is preferably at least one selected from an isocyanate-based crosslinking agent, an epoxy-based crosslinking agent, and a metal chelate-based crosslinking agent.

Moreover, from the viewpoint of forming a composition capable of forming a cured product with further improved low dielectric properties, the crosslinking agent (E) used in one aspect of the present invention is preferably a crosslinking agent having an isocyanurate skeleton.

The isocyanate-based crosslinking agent is preferably a compound having two or more isocyanate groups in the molecule, for example, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, hydrogenated tolylene diisocyanate, hydrogenated xylene diisocyanate, 1,5 -Pentamethylene diisocyanate, 1,6-hexamethylene diisocyanate, diphenylmethane-4,4-diisocyanate, isophorone diisocyanate, 1,3-bis(isocyanatomethyl)cyclohexane, tetramethylxylylenedi Isocyanate, 1,5-naphthalene diisocyanate, triphenylmethane triisocyanate, adduct forms of these polyisocyanate compounds and polyol compounds such as trimethylolpropane, biuret forms and isocyanurate forms of these polyisocyanate compounds, etc. there is.

The epoxy-based crosslinking agent is preferably a compound having two or more epoxy groups in the molecule, for example, 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane, N,N,N',N' -Tetraglycidyl-m-xylylenediamine, ethylene glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, trimethylolpropane diglycidyl ether, diglycidylaniline, diglycy. Dillamine, etc. can be mentioned.

Examples of the metal chelate-based crosslinking agent include chelate compounds having metal ions that function as crosslinking points. Examples of the metal ion include aluminum ions, zirconium ions, titanium ions, zinc ions, iron ions, and tin ions.

Among these, the metal chelate-based crosslinking agent is preferably an aluminum chelate compound, for example, aluminum tris(acetylacetonato), acetylacetonatoaluminum bis(ethylacetoacetate), diisopropoxy aluminum monooleyl acetoacetate, Monoisopropoxy aluminum bisoleyl acetoacetate, etc. can be mentioned.

Among these, from the viewpoint of providing a composition capable of forming a curable adhesive layer with a higher effect of suppressing the seepage of adhesive components, as well as forming a cured product with further improved low dielectric properties, the present invention The crosslinking agent (E) used in one aspect is preferably an isocyanate-based crosslinking agent, more preferably the isocyanurate form of a polyisocyanate compound, and the isocyanurate form of 1,5-pentamethylene diisocyanate [1,3, 5-tris(5-isocyanatepentyl)-1,3,5-triazine-2,4,6-trione], and isocyanurate form of 1,6-hexamethylene diisocyanate [1,3,5 -Tris(6-isocyanatehexyl)-1,3,5-triazine-2,4,6-trione] is more preferable.

＜Component (F): Silane coupling agent＞

The curable adhesive composition used in one aspect of the present invention preferably further contains a silane coupling agent (F).

By using a composition containing a silane coupling agent, a cured product with further improved adhesive strength can be formed.

In addition, the silane coupling agent (F) may be used individually, or two or more types may be used together.

In the curable adhesive composition used in one aspect of the present invention, the content of component (F) is preferably 0.001 part by mass or more, more preferably 0.005 part by mass, based on 100 parts by mass of the total amount of component (A). or more, more preferably 0.01 parts by mass or more, more preferably 0.03 parts by mass or more, even more preferably 0.05 parts by mass or more, even more preferably 0.07 parts by mass or more, even more preferably 0.10 parts by mass or more. Preferably it is 0.12 parts by mass or more, particularly preferably 0.15 parts by mass or more, and preferably 6.0 parts by mass or less, more preferably 5.0 parts by mass or less, more preferably 4.0 parts by mass or less, and more preferably 3.0 parts by mass or less. Parts by mass or less, more preferably 2.0 parts by mass or less, more preferably 1.5 parts by mass or less, even more preferably 1.0 parts by mass or less, even more preferably 0.80 parts by mass or less, particularly preferably 0.60 parts by mass or less. .

The silane coupling agent (F) used in one aspect of the present invention is preferably an organosilicon compound having at least one alkoxysilyl group in the molecule.

Specific silane coupling agents include, for example, 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, and 3-methacryloxypropyl. Silane coupling agents having a (meth)acryloyl group such as triethoxysilane and 3-acryloxypropyltrimethoxysilane; Silane coupling agents having a vinyl group such as vinyltrimethoxysilane, vinyltriethoxysilane, dimethoxymethylvinylsilane, diethoxymethylvinylsilane, trichlorovinylsilane, and vinyltris(2-methoxyethoxy)silane; 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-glycidoxypropyltriethoxysilane, Silane coupling agents having an epoxy group such as 8-glycidoxyoctyltrimethoxysilane; Silane coupling agents having a styryl group such as p-styryltrimethoxysilane and p-styryltriethoxysilane; N-(2-aminoethyl)-3-aminopropylmethyldimethoxysilane, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, N-(2-aminoethyl)-3-aminopropyltri Ethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-triethoxysilyl-N-(1,3-dimethyl·butylidene)propylamine, N-phenyl-3 -Silane coupling agents having an amino group such as aminopropyltrimethoxysilane and hydrochloride salt of N-(vinylbenzyl)-2-aminoethyl-3-aminopropyltrimethoxysilane; Silane coupling agents having a ureido group such as 3-ureidopropyltrimethoxysilane and 3-ureidopropyltriethoxysilane; Silane coupling agents having halogen atoms such as 3-chloropropyltrimethoxysilane and 3-chloropropyltriethoxysilane; Silane coupling agents having a mercapto group such as 3-mercaptopropylmethyldimethoxysilane and 3-mercaptopropyltrimethoxysilane; Silane coupling agents having a sulfide group such as bis(trimethoxysilylpropyl)tetrasulfide and bis(triethoxysilylpropyl)tetrasulfide; Silane coupling agents having an isocyanate group such as 3-isocyanate propyltrimethoxysilane and 3-isocyanate propyltriethoxysilane; Silane coupling agents having an allyl group such as allyltrichlorosilane, allyltriethoxysilane, and allyltrimethoxysilane; Silane coupling agents having hydroxyl groups such as 3-hydroxypropyltrimethoxysilane and 3-hydroxypropyltriethoxysilane; etc. can be mentioned.

＜Cyclic ether compound＞

The curable adhesive composition used in one aspect of the present invention may be a composition further containing a cyclic ether compound.

The cyclic ether compound is any compound having a cyclic ether group.

Examples of the cyclic ether group include oxirane group (epoxy group), oxetane group (oxetanyl group), tetrahydrofuryl group, and tetrahydropyranyl group.

In addition, in this specification, the oxirane group includes a group having an oxirane structure such as a glycidyl group, a glycidyl ether group, and an epoxycyclohexyl group.

In addition, the cyclic ether compound may be used individually, or two or more types may be used together.

While the composition containing the cyclic ether compound has the characteristic of being able to form a cured product with excellent adhesive strength, the cured product has a large relative dielectric constant and dielectric loss tangent, and the above-mentioned component (B) or ( It contains component C) and tends to have poorer low dielectric properties than a composition that does not contain a cyclic ether compound.

In the curable adhesive composition used in one aspect of the present invention, the content of the cyclic ether compound is less than 5.0 mass%, less than 3.0 mass%, based on the total amount (100 mass%) of the active ingredients of the curable adhesive composition. It may be less than 1.0 mass%, less than 0.50 mass%, less than 0.10 mass%, less than 0.010 mass%, less than 0.0010 mass%, less than 0.00010 mass%, or less than 0.000010 mass%.

Moreover, in the curable adhesive composition used in one aspect of the present invention, the content of the cyclic ether compound is 5.0 parts by mass with respect to 100 parts by mass of the total amount of components (A) to (C) contained in the curable adhesive composition. It may be less than, less than 3.0 parts by mass, less than 1.0 parts by mass, less than 0.50 parts by mass, less than 0.10 parts by mass, less than 0.010 parts by mass, less than 0.0010 parts by mass, less than 0.00010 parts by mass, or less than 0.000010 parts by mass.

＜Inorganic filler＞

The curable adhesive composition used in one aspect of the present invention may be a composition that further contains an inorganic filler, or may be a composition that does not contain an inorganic filler.

Inorganic fillers include, for example, silica, alumina, talc, aluminum hydroxide, magnesium hydroxide, titanium oxide, mica, aluminum borate, barium sulfate, boron nitride, forsterite, zinc oxide, magnesium oxide, calcium carbonate, etc. You can.

These inorganic fillers may be used individually, or two or more types may be used together.

However, in the curable adhesive composition used in one aspect of the present invention, the smaller the content of the inorganic filler, the more preferable it is.

In the curable adhesive composition used in one aspect of the present invention, the content of the inorganic filler is 0 to 30% by mass, 0 to 20% by mass, based on the total amount (100% by mass) of the active ingredients of the curable adhesive composition. It may be 0 to 10 mass%, 0 to 5.0 mass%, 0 to 2.0 mass%, 0 to 1.0 mass%, 0 to 0.1 mass%, 0 to 0.01 mass%, or 0 to 0.001 mass%.

Moreover, in the curable adhesive composition used in one aspect of the present invention, the content of the inorganic filler is less than 50 parts by mass with respect to 100 parts by mass of the total amount of components (A) to (C) contained in the curable adhesive composition, It may be less than 30 parts by mass, less than 10 parts by mass, less than 5.0 parts by mass, less than 1.0 parts by mass, less than 0.1 parts by mass, less than 0.01 parts by mass, less than 0.001 parts by mass, or less than 0.0001 parts by mass.

＜Other additives＞

The curable adhesive composition used in one aspect of the present invention may contain additives other than the components described above as long as they do not interfere with the effects of the present invention.

Other additives include, for example, ultraviolet absorbers, antistatic agents, light stabilizers, antioxidants, resin stabilizers, pigments, extenders, softeners, etc.

These additives may be used individually, or two or more types may be used together.

Additionally, the content of these additives can be appropriately set depending on the type of additive.

For example, the content of each additive is 0.001 to 30 parts by mass, 0.005 to 20 parts by mass, 0.01 to 10 parts by mass, or 0.03 parts by mass, based on 100 parts by mass of the total amount of component (A) contained in the curable adhesive composition. It may be ~5 parts by mass.

＜Active ingredients of liquid＞

The curable adhesive composition used in one aspect of the present invention preferably contains an active ingredient that is liquid at 25°C. By using a composition containing a liquid active ingredient, the sticking properties of the formed curable adhesive layer can be improved.

In the curable adhesive composition used in one aspect of the present invention, the content of the active ingredient that is liquid at 25°C is the curable adhesive layer with excellent sticking properties relative to the total amount (100% by mass) of the active ingredient of the curable adhesive composition. From the viewpoint of forming a composition, the content of the active ingredient is preferably 7.0 mass% or more, more preferably 10 mass% or more, and still more preferably 12 mass% or more, and is liquid at 25°C. As the amount increases, the peel force (R1) and the peel force (R2) tend to increase, so from the viewpoint of adjusting the curable adhesive sheet to satisfy the above requirements (I) or (III), preferably 50% by mass. Below, more preferably 35 mass% or less, further preferably 25 mass% or less.

In addition, it is used in one aspect of the present invention from the viewpoint of forming a composition that can form a curable adhesive layer with excellent sticking properties and also forming a cured product with improved low dielectric properties and adhesive strength. At least one active ingredient that is liquid at 25°C contained in the curable adhesive composition is preferably a polyfunctional compound (C).

In the curable adhesive composition used in one aspect of the present invention, the content ratio of the polyfunctional compound (C) relative to the total amount (100 mass%) of the active ingredient that is liquid at 25°C is preferably 70 mass% or more. , more preferably 80 mass% or more, further preferably 85 mass% or more, and usually 100 mass% or less, preferably 99.0 mass% or less, more preferably 98.0 mass% or less.

＜Dilution Solvent＞

The curable adhesive composition used in one aspect of the present invention may be in the form of a solution by further adding a diluting solvent.

Examples of the diluting solvent used in one aspect of the present invention include aromatic hydrocarbon-based solvents such as benzene and toluene; Ester solvents such as ethyl acetate and butyl acetate; Ketone-based solvents such as acetone, methyl ethyl ketone, and methyl isobutyl ketone; Aliphatic hydrocarbon-based solvents such as n-pentane, n-hexane, and n-heptane; Alicyclic hydrocarbon-based solvents such as cyclopentane, cyclohexane, and methylcyclohexane; etc. can be mentioned.

These diluting solvents may be used individually, or two or more types may be used together.

Additionally, these diluting solvents may be the same solvents used during the synthesis of components (A) and (B), or may be one or more solvents other than the solvents used during the synthesis of components (A) and (B). You may add .

When the curable adhesive composition used in one aspect of the present invention is in the form of a solution, the active ingredient concentration of the curable adhesive composition is appropriately set to achieve the desired viscosity in consideration of applicability, etc., but the total amount of the curable adhesive composition ( 100 mass%), preferably 3.0 mass% or more, more preferably 10 mass% or more, and preferably 70 mass% or less, more preferably 50 mass% or less.

[Method for manufacturing curable adhesive sheet]

As a method for producing the curable adhesive sheet of one aspect of the present invention, it can be produced by applying the above-mentioned curable adhesive composition on the release layer of the first release film or the second release film by a known application method.

Additionally, from the viewpoint of improving applicability to a release film, it is preferable to dilute the curable adhesive composition with a diluting solvent to form a solution.

Methods for applying the curable adhesive composition include, for example, spin coat method, spray coat method, bar coat method, knife coat method, roll coat method, blade coat method, die coat method, gravure coat method, etc. .

After applying the curable adhesive composition to form a coating film, it is preferable to perform a drying treatment.

Drying treatment methods include, for example, hot air drying, hot roll drying, and infrared irradiation.

The drying conditions for the formed coating film are preferably dried by heating at a temperature of 80°C to 150°C for 30 seconds to 5 minutes (preferably 40 seconds to 3 minutes, more preferably 45 seconds to 2 minutes). . Through this drying process, a curable adhesive layer can be formed on the peeling layer of the first peeling film or the second peeling film. Additionally, the curable adhesive sheet of one embodiment of the present invention can be obtained by laminating another release film on the exposed surface of the formed curable adhesive layer. Additionally, from the viewpoint of making it easier to obtain a curable adhesive sheet that satisfies requirement (II), a curable adhesive composition is applied to the second release film, and the first release film is laminated on the exposed surface of the formed curable adhesive layer. It is desirable to do so.

In addition, when the curable adhesive composition used to form the curable adhesive layer contains a crosslinking agent (E), a seasoning process is carried out for a certain period of time (for example, about 1 to 14 days) to complete the crosslinking reaction. It is advisable to go through it.

[Method of using curable adhesive sheet, method of manufacturing circuit board with cured product formed]

The cured product obtained by curing the curable adhesive layer of the curable adhesive sheet of one aspect of the present invention has high adhesive strength and is also excellent in low dielectric properties in the high frequency region.

Therefore, the curable adhesive sheet of one aspect of the present invention is preferably used when forming a member in a device requiring low dielectric properties, and is particularly preferably used as a coverlay sheet to protect a circuit board.

Examples of circuit boards include flexible printed circuit boards (FPC).

In addition, since the curable adhesive layer of the curable adhesive sheet of one aspect of the present invention has the above characteristics, the present invention can also provide the following [1] and [2].

[1] Adhesion in which the curable adhesive layer of the curable adhesive sheet of one embodiment of the present invention described above is bonded to a circuit board, the curable adhesive layer is cured to form a cured product, and the cured product is bonded to the circuit board. A method of using a curable adhesive sheet having a process.

[2] Adhesion in which the curable adhesive layer of the curable adhesive sheet of one embodiment of the present invention described above is bonded to a circuit board, the curable adhesive layer is cured to form a cured product, and the cured product is bonded to the circuit board. A method of manufacturing a circuit board with a cured product formed thereon, comprising a process.

In [1] and [2] above, the method of curing the curable adhesive layer to form a cured product can be adjusted depending on the type of reactive curing agent such as component (D), and may be a thermal curing method or a photo curing method. , is selected depending on the type of component contained in the curable adhesive composition, which is the forming material of the curable adhesive layer. However, thermal curing method is preferable.

The heating temperature when performing thermal curing is preferably 80 to 200°C, more preferably 90 to 190°C, and even more preferably 100 to 180°C, and the heating time is preferably 10 minutes to 12 hours. , more preferably 30 minutes to 6 hours, and even more preferably 40 minutes to 3 hours.

Additionally, when performing heat curing, it is preferable to perform heat pressing. The pressure when performing hot pressing is preferably 0.1 to 10 MPa, more preferably 0.5 to 8.0 MPa, and even more preferably 1.0 to 5.0 MPa.

In addition, when curing the curable adhesive layer by a photocuring method, a cured product can be obtained by irradiating the curable adhesive layer with energy rays such as ultraviolet rays.

Example

Hereinafter, the present invention will be described in more detail through examples. However, the present invention is not limited in any way to the following examples.

In addition, each physical property value is a value measured by the method shown below.

[Number average molecular weight (Mn)]

Measurements were made under the following conditions using a gel permeation chromatograph (manufactured by Tosoh Corporation, product name “HLC-8320 GPC”), and the values measured in standard polystyrene conversion were used.

(Measuring conditions)

· Column: 「TSK gel guard column super H-H」, 「TSK gel super HM-H」, 「TSK gel super HM-H」 and 「TSK gel super H2000」 connected in sequence (all manufactured by Tosoh Corporation)

· Column temperature: 40℃

· Development solvent: tetrahydrofuran

· Flow rate: 1.0 mL/min

[Peel force (R1)]

The curable adhesive sheet to be measured was cut into a size of 150 m long x 50 mm wide to prepare a test sample.

Then, one adhesive surface of the double-sided tape is attached to the surface opposite to the surface in contact with the curable adhesive layer of the second release film in the test sample, and the other adhesive surface of the double-sided tape is overlapped on the surface of the metal plate, It was compressed.

Next, in an environment of a temperature of 23°C and a relative humidity of 50%, the first peeling film to be measured for peeling force was separated from a metal plate using a precision universal testing machine (manufactured by Shimadzu Corporation, product name “Autograph AG-IS”). The value measured when peeling from a test sample fixed in the condition of a peeling angle of 180° and a peeling speed of 300 mm/min was taken as “peel force (R1).”

[Peel force (R2)]

The first release film is removed from the curable adhesive sheet to be measured, and the exposed adhesive surface is superimposed on the surface of a polyimide film (Kapton 100H, manufactured by Toray DuPont Co., Ltd.) with a thickness of 25 μm, using a thermal laminator. Compressed at 100°C. Next, the curable adhesive sheet was cut together with the polyimide film into a size of 150 m in length x 50 mm in width to prepare a test sample. One adhesive side of the double-sided tape was attached to the side of the polyimide film of the test sample opposite to the side on which the curable adhesive layer was laminated, and the other adhesive side of the double-sided tape was overlapped on the surface of the metal plate and pressed. . For this test sample, a peeling test was performed in the same manner as the measurement of the peeling force (R1) above. That is, in an environment with a temperature of 23°C and a relative humidity of 50%, the second peeling film, which is the object of peeling force measurement, is peeled off at a peeling angle of 180° from a test sample fixed to a metal plate using the precision universal testing machine. The value measured when peeling was performed under conditions of a speed of 300 mm/min was taken as “peel force (R2).”

Preparation Examples 1 to 2

(1) Preparation of curable adhesive composition

The components shown in Table 1 were mixed in the amounts (active ingredient ratios) shown in Table 1 and dissolved in toluene to prepare curable adhesive compositions (1) to (2) to obtain a predetermined active ingredient concentration.

Details of each component used in preparing the curable adhesive compositions (1) to (2) are as follows.

＜Component (A): Binder resin＞

· “Modified polyolefin”: A solution containing a maleic anhydride modified α-olefin polymer (solid at 25°C) with Mn = 47,000 (manufactured by Mitsui Chemicals Co., Ltd., product name “Unistol H-200”).

<Component (B): polyphenylene ether resin>

“Polyphenylene ether resin (b1)”: a solution containing vinylbenzyl-modified polyphenylene ether (compound represented by the above general formula (b-4), solid at 25°C) with Mn = 2,200 (Mitsubishi Gas Chemical Co., Ltd. Manufactured, product name “OPE-2St 2200”).

“Polyphenylene ether resin (b2)”: a solution containing vinylbenzyl-modified polyphenylene ether (a compound represented by the general formula (b-4) above, solid at 25°C) with Mn = 1,200 (Mitsubishi Gas Chemical Co., Ltd. Manufactured, product name “OPE-2St 1200”).

<Component (C): Multifunctional compound>

- “Multifunctional compound”: A compound having an isocyanurate skeleton in which R ^a in the general formula (c-11) is an alkyl group having 8 to 15 carbon atoms. Manufactured by Shikoku Chemical Industry Co., Ltd., product name “L-DAIC”, molecular weight = 377.27, liquid at 25°C.

<Component (D): Cationic polymerization initiator>

· “Thermal cationic polymerization initiator”: Thermal cationic polymerization initiator (manufactured by Sanshin Chemical Co., Ltd., product name “San-Aid SI-B3”), solid at 25°C.

＜Component (E): Cross-linking agent＞

・"Isocyanate-based crosslinking agent": 1,3,5-tris(pentyl 5-isocyanate)-1,3,5-triazine-2,4,6-trione (manufactured by Mitsui Chemicals Co., Ltd., product name "Stavio D-" 370N"), molecular weight = 462, liquid at 25℃.

＜Component (F): Silane coupling agent＞

· “Silane coupling agent”: 8-glycidoxyoctyltrimethoxysilane (Shin-Etsu Chemical Co., Ltd., product name “KBM4803”), liquid at 25°C.

Examples 1 to 2, Comparative Examples 1 to 2

The curable adhesive composition used as the forming material for the release film and curable adhesive layer used in the following examples and comparative examples is as follows.

＜First release film＞

· Non-silicone release film (1): Product name “PC38 AL-5”, manufactured by Lintech Co., Ltd., a non-silicone release film having a release layer formed with an alkyd release agent on a polyethylene terephthalate (PET) film made white by foaming, Thickness: 38 ㎛.

＜Second release film＞

· Non-silicone release film (2): Product name “SP-PET50 AL-5”, manufactured by Lintech Co., Ltd., non-silicone release film having a release layer formed with an alkyd release agent on a colorless PET film, thickness: 50 μm.

· Non-silicone release film (3): Product name “SP-PET75 AL-5”, manufactured by Lintech Co., Ltd., non-silicone release film having a release layer formed with an alkyd release agent on a colorless PET film, thickness: 75 μm.

<Material for forming curable adhesive layer>

· Curable adhesive composition (1): Curable adhesive composition (1) prepared with the composition shown in Table 1 in Production Example 1.

· Curable adhesive composition (2): Curable adhesive composition (2) prepared with the composition shown in Table 1 in Production Example 2.

The curable adhesive composition shown in Table 1 was applied on the peeling layer of the second peeling film shown in Table 2 to form a coating film, and the coating film was dried to form a curable adhesive layer with a thickness of 25 μm.

Furthermore, the exposed surface of the formed curable adhesive layer and the peeling layer of the first peeling film shown in Table 2 were bonded together to prepare a curable adhesive sheet.

Using the prepared curable adhesive sheet, peel force (R1) and (R2) were measured by the method described above. The results are as shown in Table 2.

Moreover, based on the following evaluation method, the dielectric loss tangent of the cured product formed by curing the curable adhesive layer and the peelability of the first release film were evaluated. These results are also shown in Table 2.

[Dielectric loss tangent of hardened product]

A plurality of manufactured curable adhesive sheets are prepared, a plurality of curable adhesive layers are overlapped to form a curable adhesive layer with a thickness of about 1 mm, and a second release film/curable adhesive layer with a thickness of about 1 mm/first release film is formed. A laminate formed by laminating in this order was obtained.

Then, this laminate was heated at 160°C for 1 hour to cure the curable adhesive layer to obtain a cured product, and the cured product obtained by removing the first release film and the second release film was used as a sample for measurement.

For the obtained measurement sample, the dielectric loss tangent of the cured product at 23°C and 1 GHz was measured using an RF Impedance Material Analyzer (manufactured by Keysight Technologies, Inc., product name “E4991A”). Additionally, in this specification, 1 GHz is adopted as an example of the high frequency region.

[Evaluation of the peelability of the first release film]

The ease of peeling when only the first release film was attempted to be peeled from the manufactured curable adhesive sheet was evaluated based on the following criteria.

· A: The first release film could be peeled off very easily, and there was no problem in handling at all.

· F: When an attempt was made to peel the first release film, one or more retries occurred, and there was a problem in handleability.

From Table 2, compared to Comparative Examples 1 and 2, the curable adhesive sheets manufactured in Examples 1 and 2 were easier to peel from the first release film, resulting in excellent handling properties. In addition, since the curable adhesive sheets manufactured in Examples 1 and 2 use a non-silicone-based release agent, the silicone component does not migrate to the adherend, so contamination of the adherend can be suppressed.

1: Curable adhesive sheet
10: Curable adhesive layer
10a, 10b: surface
21: first release film
211: peeling layer
212: Resin film
22: second release film
221: peeling layer
222: Resin film

Claims (9)

A curable adhesive sheet having a curable adhesive layer capable of forming a cured product having a dielectric loss tangent of 0.01 or less at 23°C and 1 GHz, and a first release film and a second release film sandwiching both sides of the curable adhesive layer. ,
The first release film and the second release film have a resin film and a release layer formed on one surface of the resin film with a non-silicone release agent and in contact with the surface of the curable adhesive layer,
A curable adhesive sheet that satisfies the following requirement (I).
· Requirement (I): The peeling force (R1) when peeling the first release film from the curable adhesive layer at a peeling angle of 180° and a peeling speed of 300 mm/min is 250 mN/50 mm or less. According to claim 1,
Additionally, a curable adhesive sheet that satisfies the following requirement (II).
· Requirement (II): The peeling force (R1) is smaller than the peeling force (R2) when peeling the second release film from the curable adhesive layer at a peeling angle of 180° and a peeling speed of 300 mm/min. According to claim 2,
Additionally, a curable adhesive sheet that satisfies the following requirement (IIa).
· Requirement (IIa): The ratio [(R1)/(R2)] of the peeling force (R1) and the peeling force (R2) is 0.97 or less. The method according to any one of claims 1 to 3,
Additionally, a curable adhesive sheet that satisfies the following requirement (III).
· Requirement (III): The peeling force (R2) when peeling the second peeling film from the curable adhesive layer at a peeling angle of 180° and a peeling speed of 300 mm/min is 300 mN/50 mm or less. The method according to any one of claims 1 to 4,
A curable adhesive sheet wherein the non-silicone-based release agent used to form the release layer of at least one of the first release film and the second release film is an alkyd-based release agent. The method according to any one of claims 1 to 5,
A curable adhesive sheet, wherein the curable adhesive layer is a layer formed of a curable adhesive composition containing a binder resin (A). According to claim 6,
A curable adhesive sheet in which the curable adhesive composition further contains polyphenylene ether resin (B). The method according to any one of claims 1 to 7,
A curable adhesive sheet wherein the resin film (1) constituting the first release film is a colored resin film. The method according to any one of claims 1 to 8,
A curable adhesive sheet in which the resin film (2) constituting the second release film is visually distinguishable from the resin film (1) constituting the first release film.

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