WO2022210672A1

WO2022210672A1 - Adhesive sheet

Info

Publication number: WO2022210672A1
Application number: PCT/JP2022/015342
Authority: WO
Inventors: 健太西嶋; 幹広樫尾
Original assignee: リンテック株式会社
Priority date: 2021-03-30
Filing date: 2022-03-29
Publication date: 2022-10-06
Also published as: JPWO2022210672A1; CN117098822A; TW202300607A; KR20230161422A

Abstract

Provided is an adhesive sheet including a curable adhesive layer, wherein the curable adhesive layer is one formed from a starting material composition comprising a binder resin (A) having a reactive functional group and a crosslinking agent (B) capable of reacting with the (A) ingredient, the (B) ingredient being contained in an amount of 0.1 mass% or larger with respect to the sum of all the active ingredients of the starting material composition. The curable adhesive layer has a gel content of 10 mass% or higher.

Description

Adhesive sheet

The present invention relates to an adhesive sheet having a curable adhesive layer that does not easily contaminate the surroundings when subjected to heat treatment such as hot press treatment.

In recent years, curable adhesives are sometimes used as materials for forming insulating resin layers, sealant layers, adhesive members, etc. of electronic devices.

For example, Patent Document 1 discloses a thermosetting adhesive sheet containing an epoxy resin, wherein the cured product of the thermosetting adhesive sheet has a storage elastic modulus (x1) of 1 GPa or more at 25°C and a temperature of 100°C. describes a thermosetting adhesive sheet having a storage modulus (x2) of 1 GPa or more. In addition, this document states that the thermosetting adhesive sheet described in the same document can effectively suppress minute deformation and displacement of an adherend at high temperatures, and can be repeatedly minutely deformed as an adherend. It is also described that even when used to fix an adherend, it is less likely to cause peeling over time.

Japanese Patent Application Laid-Open No. 2017-110128

When using an adhesive composition, heat treatment is usually performed on the coating film of the adhesive composition. In such a case, depending on the processing conditions, the adhesive component may ooze out and cause contamination of the surroundings.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an adhesive sheet having a curable adhesive layer that does not easily contaminate the surroundings when subjected to heat treatment such as hot press treatment.

The inventors diligently studied to solve the above problems. As a result, for an adhesive sheet having a curable adhesive layer, a raw material composition for the curable adhesive layer containing a predetermined component was used, and the gel fraction of the curable adhesive layer was within a predetermined range. The inventors have found that the adjustment can suppress the exudation of the adhesive component during heat treatment and prevent contamination of the surroundings, leading to the completion of the present invention.

Thus, according to the present invention, the following adhesive sheets [1] to [14] are provided.
[1] An adhesive sheet having a curable adhesive layer,
The raw material composition of the curable adhesive layer contains the following components (A) and (B), and the amount of component (B) is 0.1 mass based on the total amount of active ingredients in the raw material composition. % or more,
The adhesive sheet, wherein the curable adhesive layer has a gel fraction of 10% by mass or more.
(A) component: binder resin having a reactive functional group (B) component: cross-linking agent capable of reacting with component (A) [2] described in [1], wherein component (A) is a polyolefin resin adhesive sheet.
[3] The adhesive sheet of [1] or [2], wherein the component (A) is an acid-modified resin.
[4] The adhesive sheet according to any one of [1] to [3], wherein the component (B) is a compound having an isocyanurate skeleton.
[5] The adhesive sheet according to any one of [1] to [4], wherein the component (B) is a compound having two or more isocyanate groups.
[6] The adhesive sheet according to any one of [1] to [5], wherein the curable adhesive layer is a layer formed from a raw material composition further containing component (C) below.
Component (C): A non-aromatic curable compound that is liquid at 25° C. [7] Component (C) is a compound having two or more hydrocarbon groups with double bonds at their terminals [6] Adhesive sheet as described.
[8] The adhesive sheet according to any one of [1] to [7], wherein the curable adhesive layer is a layer formed from a raw material composition further containing component (D) below.
(D) component: polyphenylene ether resin having a reactive functional group [9] The curable adhesive layer is a layer formed from a raw material composition further containing the following component (E) [1] to [ 8] The adhesive sheet according to any one of the above items.
(E) component: cationic polymerization initiator [10] The adhesive sheet according to any one of [1] to [9], wherein the curable adhesive layer has a dielectric loss tangent at 23° C. and a frequency of 1 GHz of less than 0.005. .
[11] The adhesive sheet according to any one of [1] to [10], wherein the curable adhesive layer has a dielectric constant of 3.00 or less at 23° C. and a frequency of 1 GHz.
[12] Any one of [1] to [11], wherein the curable adhesive layer gives a cured product having a gel fraction of 50% by mass or more after curing at 160° C. for 1 hour. Adhesive sheet described in .
[13] The adhesive sheet according to any one of [1] to [12], which is used for electronic devices.
[14] The adhesive sheet according to any one of [1] to [12], which is used for a coverlay film.

According to the present invention, an adhesive sheet having a curable adhesive layer that hardly contaminates the surroundings when subjected to heat treatment such as hot press treatment is provided.

FIG. 2 is a schematic diagram (plan view) of a part of a laminate used when evaluating the exudation of an adhesive component. FIG. 2 is a schematic diagram showing a cross section taken along line AA of FIG. 1;

For the numerical ranges described herein, the upper and lower limits can be combined arbitrarily. For example, when the numerical range is described as "preferably 30 to 100, more preferably 40 to 80", the range of "30 to 80" and the range of "40 to 100" are also described in this specification. included in the specified numerical range. Further, for example, when the numerical range is described as "preferably 30 or more, more preferably 40 or more, and preferably 100 or less, more preferably 80 or less", "30 to 80" Ranges and ranges from "40 to 100" are also included in the numerical ranges described herein.
Also, as a numerical range described in this specification, for example, the description of "60 to 100" means a range of "60 or more and 100 or less".
Furthermore, in the definition of the upper limit value and the lower limit value described in this specification, it is possible to define the numerical range from the lower limit value to the upper limit value by appropriately selecting from each option and combining them arbitrarily.
In addition, various requirements described as preferred embodiments described herein can be combined.

In the present specification, the number average molecular weight (Mn) can be obtained as a standard polystyrene conversion value by performing gel permeation chromatography (GPC) using tetrahydrofuran (THF) as a solvent. can be measured by
(Example of measurement conditions)
・ Gel permeation chromatograph device: manufactured by Tosoh Corporation, product name “HLC-8020”
・ Column: "TSK guard column HXL-L", "TSK gel G2500HXL", "TSK gel G2000HXL" and "TSK gel G1000HXL" sequentially connected (all manufactured by Tosoh Corporation)
・Column temperature: 40°C
・Developing solvent: tetrahydrofuran ・Flow rate: 1.0 mL/min

The adhesive sheet of the present invention is an adhesive sheet having a curable adhesive layer, wherein the raw material composition of the curable adhesive layer contains the following components (A) and (B), and ( The adhesive sheet contains component B) in an amount of 0.1% by mass or more relative to the total amount of active ingredients in the raw material composition, and the curable adhesive layer has a gel fraction of 10% by mass or more. .
(A) component: a binder resin having a reactive functional group (B) component: a cross-linking agent capable of reacting with the (A) component A component other than a solvent.

<<Raw material composition of curable adhesive layer>>
The raw material composition for the curable adhesive layer constituting the adhesive sheet of the present invention contains the above components (A) and (B), and the content of component (B) is the total amount of active ingredients in the raw material composition. is adjusted to 0.1% by mass or more.

Since the cross-linking agent (B) is a compound that can react with the binder resin (A), the binder resin (A) and the cross-linking agent are formed in the coating film (curable adhesive layer) obtained by applying the raw material composition. (B) can be reacted to build a crosslinked structure within the curable adhesive layer.
As will be described later, by utilizing this reaction, a curable adhesive layer having a gel fraction of 10% by mass or more can be efficiently formed.
In this specification, the cross-linking reaction involving the binder resin (A) and the cross-linking agent (B) may be referred to as "curing reaction (I)".

The raw material composition may contain a curable component other than the binder resin (A) and the cross-linking agent (B) (hereinafter sometimes referred to as "curable component (X)").

The curable component (X) may be a compound that participates in the curing reaction (I) or a compound that does not participate in the curing reaction (I).
The curable component (X) can be used for the curing reaction (I) because the curing reaction can be reliably performed a plurality of times and the oozing of the adhesive component in the curable adhesive layer can be suppressed more reliably. Non-participating compounds are preferred.
That is, when the curable component (X) is a compound that participates in the curing reaction (I), a step of constructing a crosslinked structure in the curable adhesive layer to produce the adhesive sheet of the present invention, and Since the curing reaction (I) is required in both steps of the process of more firmly bonding two adherends using a sheet, curing initiated to build a crosslinked structure within the curable adhesive layer It is necessary to temporarily stop the reaction (I) in the middle, and it is necessary to control the curing reaction (I) to a high degree.
On the other hand, when the curable component (X) is a compound that does not participate in the curing reaction (I), even if the curing reaction (I) is substantially completed, the adhesive layer will still have the curability derived from the curable component (X). Therefore, it is possible to carry out a step of bonding two adherends more strongly by utilizing this curability. Thus, by using the raw material composition containing the curable component (X) that does not participate in the curing reaction (I), the adhesive sheet of the present invention can be efficiently produced without highly controlling the curing reaction (I). can be manufactured well.

In this specification, the curing reaction involving the curable component (X) that does not participate in the curing reaction (I) is sometimes referred to as "curing reaction (II)".

The curable component (X) includes the following components (C), (D) and (F).
Component (C): Non-aromatic curable compound that is liquid at 25° C. Component (D): Polyphenylene ether resin having a reactive functional group Component (F): Silane coupling agent

When the curing reaction (I) or curing reaction (II) is a cationic polymerization reaction, the raw material composition used in one aspect of the present invention may further contain the following component (E).
Component (E): Cationic polymerization initiator Further, the raw material composition used in one embodiment of the present invention further contains components other than the above components (A) to (F) within a range that does not impair the effects of the present invention. may contain.

In the raw material composition used in one aspect of the present invention, the total content of the components (A) and (B) is 40% by mass or more with respect to the total amount (100% by mass) of the active ingredients in the raw material composition, 50% by mass or more, 60% by mass or more, 65% by mass or more, or 70% by mass or more, and 100% by mass or less, 99% by mass or less, 95% by mass or less, 90% by mass or less, and 85% by mass or less , or 80% by mass or less.

In the raw material composition used in one aspect of the present invention, the total content of components (A) to (E) is 45% by mass or more with respect to the total amount (100% by mass) of the active ingredients in the raw material composition, 55% by mass or more, 65% by mass or more, 75% by mass or more, 80% by mass or more, 85% by mass or more, 90% by mass or more, or 95% by mass or more, and 100% by mass or less, 99.9 % by mass or less, or 99.8% by mass or less.

In the raw material composition used in one aspect of the present invention, the total content of components (A) to (F) is 45 to 100% by mass with respect to the total amount (100% by mass) of the active ingredients in the raw material composition. , 55% by mass or more, 65% by mass or more, 75% by mass or more, 80% by mass or more, 85% by mass or more, 90% by mass or more, or 95% by mass or more, and 100% by mass or less, 99. It may be 9% by mass or less, or 99.8% by mass or less.

[(A) component: binder resin having a reactive functional group]
A raw material composition (hereinafter, sometimes simply referred to as "raw material composition"), which is a material for forming a curable adhesive layer, contains, as component (A), a binder resin having a reactive functional group (hereinafter, " It may be described as "binder resin (A)").
By using the raw material composition containing the binder resin (A), it becomes easier to form a curable adhesive layer that does not easily stain the surroundings when subjected to heat treatment such as hot press treatment.
Binder resin (A) can be used individually by 1 type or in combination of 2 or more types.

The number average molecular weight (Mn) of the binder resin (A) is not particularly limited. 000 or more, preferably 10,000 to 150,000, more preferably 10,000 to 100,000.
The number average molecular weight (Mn) of the binder resin (A) can be obtained as a standard polystyrene conversion value by performing gel permeation chromatography (GPC) using tetrahydrofuran (THF) as a solvent, and specific measurement The conditions are as described above.

The content of the binder resin (A) contained in the raw material composition (the total amount of these when containing two or more binder resins (A)) is based on the total amount (100% by mass) of the active ingredients in the raw material composition. is preferably 50% by mass or more, more preferably 60% by mass or more, still more preferably 65% by mass or more, and is preferably 95% by mass or less, more preferably 90% by mass or less, and still more preferably 85% by mass. 80% by mass or less, and more preferably 80% by mass or less.
When the content of the binder resin (A) is 50% by mass or more, it becomes easier to form a curable adhesive layer that does not easily stain the surroundings when subjected to heat treatment such as hot press treatment.
When the content of the binder resin (A) is 95% by mass or less, excellent curing with low dielectric properties (in this specification, "low dielectric properties" means "low dielectric constant and low dielectric loss tangent") This facilitates the formation of a flexible adhesive layer.

Examples of the binder resin (A) include polyolefin-based resins, phenoxy-based resins, polyimide-based resins, polyamideimide-based resins, polyvinyl butyral-based resins, and polycarbonate-based resins.
Among these, polyolefin-based resins are preferable as the binder resin (A). When the binder resin (A) is a polyolefin resin, a curable adhesive layer with excellent low dielectric properties can be easily formed.

In the case of a raw material composition in which the component (A) is a polyolefin resin, the raw material composition may contain other binder resins than the polyolefin resin as other components.
In the raw material composition, the content of the other binder resin is preferably 0 to 50 parts by mass, more preferably 0 to 30 parts by mass, and still more preferably 0 to 10 parts by mass with respect to 100 parts by mass of the total polyolefin resin. parts by weight, more preferably 0 to 5 parts by weight.

A polyolefin resin is a polymer containing repeating units derived from an olefin monomer. The polyolefin resin may be a polymer consisting only of repeating units derived from an olefinic monomer, or a repeating unit derived from an olefinic monomer and a monomer copolymerizable with the olefinic monomer. It may be a polymer composed of repeating units derived from

The olefinic monomer is preferably an α-olefin having 2 to 8 carbon atoms, more preferably ethylene, propylene, 1-butene, isobutylene, or 1-hexene, and still more preferably ethylene or propylene. These olefinic monomers can be used singly or in combination of two or more.
Examples of monomers copolymerizable with olefinic monomers include vinyl acetate, (meth)acrylic acid esters, and styrene. Here, "(meth)acrylic acid" means acrylic acid or methacrylic acid (same below).
These "monomers copolymerizable with olefinic monomers" can be used singly or in combination of two or more.

Polyolefin resins include very low density polyethylene (VLDPE), low density polyethylene (LDPE), medium density polyethylene (MDPE), high density polyethylene (HDPE), linear low density polyethylene, polypropylene (PP), ethylene-propylene Copolymers, olefinic elastomers (TPO), ethylene-vinyl acetate copolymers (EVA), ethylene-(meth)acrylic acid copolymers, ethylene-(meth)acrylic acid ester copolymers, and the like.

Reactive functional groups contained in the binder resin (A) include a carboxy group, a carboxylic acid anhydride group, a carboxylic acid ester group, a hydroxyl group, an epoxy group, an amide group, an ammonium group, a nitrile group, an amino group, an imide group, and an isocyanate group. group, acetyl group, thiol group, ether group, thioether group, sulfone group, phosphon group, nitro group, urethane group, halogen atom, alkoxysilyl and the like.

Binder resin (A) is preferably a modified resin. The modified resin is a resin into which a reactive functional group is introduced, which is obtained by modifying a resin as a precursor using a modifying agent.
A modifier used for modifying the binder resin is a compound having a reactive functional group in the molecule. Reactive functional groups include those previously described.

Examples of modified resins include resins into which acid groups have been introduced (acid-modified resins) and resins into which hydroxyl groups have been introduced, and acid-modified resins are preferred. Among the acid-modified resins, resins into which an acid anhydride structure is introduced are preferable.
By using an acid-modified resin as the component (A), a curable adhesive layer with excellent low dielectric properties can be easily formed. Furthermore, by using a resin into which an acid anhydride structure is introduced as the acid-modified resin, there is a tendency that the pot life of the raw material composition can be easily maintained for a long time.

In the case of a raw material composition in which the component (A) is an acid-modified resin, the raw material composition may contain, as other components, a binder resin other than the acid-modified resin.
In the raw material composition, the content of the other binder resin is preferably 0 to 50 parts by mass, more preferably 0 to 30 parts by mass, and still more preferably 0 to 10 parts by mass with respect to 100 parts by mass of the total amount of the acid-modified resin. parts by weight, more preferably 0 to 5 parts by weight.

As the acid-modified resin, for example, a resin is reacted with an unsaturated carboxylic acid or an unsaturated carboxylic anhydride (hereinafter sometimes referred to as "unsaturated carboxylic acid or the like") to form a carboxy group or a carboxylic anhydride group. is introduced (graft modification).

Unsaturated carboxylic acids to be reacted with the resin include unsaturated carboxylic acids such as maleic acid, fumaric acid, itaconic acid, citraconic acid, glutaconic acid, tetrahydrophthalic acid, and aconitic acid; maleic anhydride, itaconic anhydride, and glutaconic anhydride. acids, unsaturated carboxylic anhydrides such as citraconic anhydride, aconitic anhydride, norbornene dicarboxylic anhydride, and tetrahydrophthalic anhydride;
These can be used individually by 1 type or in combination of 2 or more types. Among these, maleic anhydride is preferable because it facilitates the formation of a curable adhesive layer that gives a cured product with higher adhesive strength.

The amount of the unsaturated carboxylic acid or the like to be reacted with the resin is preferably 0.1 to 5 parts by mass, more preferably 0.2 to 3 parts by mass, and still more preferably 0.2 to 1 part by mass with respect to 100 parts by mass of the resin. part by mass. By using the acid-modified resin obtained in this manner, it becomes easier to form a curable adhesive layer that gives a cured product with higher adhesive strength.

The method of introducing unsaturated carboxylic acid units or unsaturated carboxylic anhydride units into the resin is not particularly limited. For example, in the presence of a radical generator such as organic peroxides or azonitriles, a resin and an unsaturated carboxylic acid, etc., a method of heating and melting above the melting point of the resin to react, or a method of reacting the resin and the unsaturated carboxylic acid. After dissolving an acid or the like in an organic solvent, the resin is graft-copolymerized with an unsaturated carboxylic acid or the like by heating and stirring in the presence of a radical generator.

As the binder resin (A), a modified polyolefin resin is preferable, and an acid-modified polyolefin resin is more preferable. By using an acid-modified polyolefin resin as the binder resin (A), it becomes easier to form a curable adhesive layer with excellent low dielectric properties and low staining properties.

A modified polyolefin resin is a polyolefin resin into which a reactive functional group has been introduced, obtained by modifying a polyolefin resin as a precursor using a modifier.

In the case of a raw material composition in which the component (A) is an acid-modified polyolefin-based resin, the raw material composition may contain other binder resins other than the acid-modified polyolefin-based resin as other components.
In the raw material composition, the content of the other binder resin is preferably 0 to 50 parts by mass, more preferably 0 to 30 parts by mass, and still more preferably 0 parts by mass with respect to 100 parts by mass of the total amount of the acid-modified polyolefin resin. to 10 parts by weight, more preferably 0 to 5 parts by weight.

[Component (B): Crosslinking agent capable of reacting with component (A)]
The raw material composition contains, as the component (B), a cross-linking agent capable of reacting with the component (A) (hereinafter sometimes referred to as "cross-linking agent (B)").
By using the raw material composition containing the cross-linking agent (B), it becomes easier to form a curable adhesive layer that does not easily stain the surroundings when subjected to heat treatment such as hot press treatment.
In addition, a crosslinking agent (B) can be used individually by 1 type or in combination of 2 or more types.

The molecular weight of the cross-linking agent (B) is preferably 1000 or less, more preferably 800 or less, even more preferably 700 or less, even more preferably 600 or less, and particularly preferably 500 or less.
When the molecular weight of the cross-linking agent (B) is 1000 or less, the collision probability of the reaction with the component (A) increases, making it easier to form a cross-linked structure, and when subjected to heat treatment such as hot press treatment, the surroundings The raw material composition can easily form a curable adhesive layer that is difficult to stain.
Although there is no particular lower limit for the molecular weight of the cross-linking agent (B), it is usually 100 or more, preferably 200 or more.
The molecular weight of the cross-linking agent (B) is a formula weight determined from the structural formula of the compound used as the cross-linking agent (B).

The content of the cross-linking agent (B) (the total amount of these when two or more cross-linking agents (B) are included) is 0.1 mass with respect to the total amount (100 mass%) of the active ingredients in the raw material composition % or more, preferably 0.2 mass % or more, more preferably 0.3 mass % or more, still more preferably 0.5 mass % or more, even more preferably 0.7 mass % or more, particularly preferably 0.7 mass % or more. It is 9% by mass or more, preferably 5% by mass or less, more preferably 4% by mass or less, still more preferably 3% by mass or less, and even more preferably 2% by mass or less.
The content of the cross-linking agent (B) is 0.1% by mass or more with respect to the total amount of active ingredients in the raw material composition, so that it has curability that does not easily stain the surroundings when subjected to heat treatment such as hot press treatment. An adhesive layer is easily formed.
Further, when the content of the cross-linking agent (B) is 5% by mass or less with respect to the total amount of active ingredients in the raw material composition, a curable adhesive layer having excellent low dielectric properties can be easily formed.

The content of the cross-linking agent (B) (the total amount of these when two or more cross-linking agents (B) are included) is preferably 0.1 part by mass or more, more preferably 100 parts by mass of component (A) 0.3 parts by mass or more, more preferably 0.5 parts by mass or more, still more preferably 0.8 parts by mass or more, particularly preferably 1.2 parts by mass or more, and preferably 10 parts by mass or less, more It is preferably 7 parts by mass or less, more preferably 5 parts by mass or less, and even more preferably 3 parts by mass or less.

Cross-linking agent (B) is a compound capable of reacting with component (A). Therefore, as the cross-linking agent (B), it is necessary to appropriately select one having a reactive group or a reactive site that is reactive with the reactive functional group in the binder resin (A).
For example, as the cross-linking agent (B), an isocyanate-based cross-linking agent, an epoxy-based cross-linking agent, a metal chelate-based cross-linking agent, an aziridine-based cross-linking agent, or the like can be used. Among these, one or more selected from isocyanate-based cross-linking agents, epoxy-based cross-linking agents, and metal chelate-based cross-linking agents are preferable from the viewpoint of storage stability.
Further, in one aspect of the present invention, for example, when the binder resin (A) is an acid-modified resin and the reactive functional group in the binder resin (A) is a carboxy group or a carboxylic anhydride group, a cross-linking agent ( B) is preferably one or more selected from isocyanate-based cross-linking agents, epoxy-based cross-linking agents, and metal chelate-based cross-linking agents.

An isocyanate-based cross-linking agent is a compound having two or more isocyanate groups in the molecule.
Examples of isocyanate cross-linking agents include 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, hydrogenated tolylene diisocyanate, hydrogenated xylene diisocyanate, 1,5-pentamethylene diisocyanate, and 1,6-hexamethylene. Diisocyanate, diphenylmethane-4,4-diisocyanate, isophorone diisocyanate, 1,3-bis(isocyanatomethyl)cyclohexane, tetramethylxylylene diisocyanate, 1,5-naphthalene diisocyanate, triphenylmethane triisocyanate, and polyisocyanate compounds thereof and adducts of polyol compounds such as trimethylolpropane, burettes and isocyanurates of these polyisocyanate compounds, and the like.

An epoxy-based cross-linking agent is a compound having two or more epoxy groups in its molecule.
Epoxy crosslinking agents include 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, diglycidylamine and the like.

A metal chelate-based cross-linking agent is a chelate compound having metal ions functioning as cross-linking points.
As metal chelate-based cross-linking agents, for example, metal chelate compounds whose metal ions are aluminum ions, zirconium ions, titanium ions, zinc ions, iron ions, tin ions, and the like can be used. Among these, aluminum chelate compounds are preferred.

Examples of aluminum chelate compounds include aluminum tris(acetylacetonate), acetylacetonate aluminum bis(ethylacetoacetate), diisopropoxyaluminum monooleyl acetoacetate, monoisopropoxyaluminum bisoleyl acetoacetate, and the like.

In one aspect of the present invention, the cross-linking agent (B) is preferably a compound having an isocyanurate skeleton, more preferably a compound having an isocyanurate skeleton and two or more isocyanate groups.
When the cross-linking agent (B) is a compound having an isocyanurate skeleton, a curable adhesive layer with excellent low dielectric properties can be easily formed.
In the case of a raw material composition in which the component (B) is a compound having an isocyanurate skeleton, the raw material composition may contain, as another component, a cross-linking agent other than the compound having an isocyanurate skeleton. good.
In the raw material composition, the content of the other cross-linking agent is preferably 0 to 100 parts by mass, more preferably 0 to 50 parts by mass, and still more preferably 100 parts by mass of the total amount of the compound having an isocyanurate skeleton. 0 to 30 parts by weight, more preferably 0 to 10 parts by weight, particularly preferably 0 to 5 parts by weight.

In one aspect of the present invention, the cross-linking agent (B) is preferably an isocyanate-based cross-linking agent, which is a compound having two or more isocyanate groups, since a curable adhesive layer having excellent low dielectric properties is easily formed. The isocyanurate of the compound is more preferable, and the isocyanurate of 1,5-pentamethylene diisocyanate [1,3,5-tris(5-isocyanatopentyl)-1,3,5-triazine-2,4,6-trione ] or an isocyanurate of 1,6-hexamethylene diisocyanate [1,3,5-tris(6-isocyanatohexyl)-1,3,5-triazine-2,4,6-trione] is more preferable.
In the case of a raw material composition in which the component (B) is an isocyanate-based cross-linking agent, the raw material composition may contain other cross-linking agents other than the isocyanate-based cross-linking agent as other components.
In the raw material composition, the content of the other cross-linking agent is preferably 0 to 100 parts by mass, more preferably 0 to 50 parts by mass, and still more preferably 0 parts by mass with respect to 100 parts by mass of the total amount of the isocyanate-based cross-linking agent. to 30 parts by mass, more preferably 0 to 10 parts by mass, and particularly preferably 0 to 5 parts by mass.

In one aspect of the present invention, the cross-linking agent (B) is preferably an epoxy-based cross-linking agent, since a curable adhesive layer that does not easily contaminate the surroundings is easily formed when subjected to heat treatment such as hot press treatment. .
In the case of a raw material composition in which the component (B) is an epoxy-based cross-linking agent, the raw material composition may contain other cross-linking agents other than the epoxy-based cross-linking agent as other components.
In the raw material composition, the content of the other cross-linking agent is preferably 0 to 100 parts by mass, more preferably 0 to 50 parts by mass, and still more preferably 0 to 100 parts by mass, with respect to 100 parts by mass of the total epoxy cross-linking agent. 30 parts by weight, more preferably 0 to 10 parts by weight, particularly preferably 0 to 5 parts by weight.

Since the cross-linking agent (B) is a compound that can react with the binder resin (A), the binder resin (A) and the cross-linking agent are formed in the coating film (curable adhesive layer) obtained by applying the raw material composition. (B) can be reacted to build a crosslinked structure within the curable adhesive layer.
As will be described later, by utilizing this reaction, a curable adhesive layer having a gel fraction of 10% by mass or more can be efficiently formed, and when subjected to heat treatment such as heat press treatment, the surrounding area can be A curable adhesive layer that is difficult to stain is easily formed.

[Component (C): non-aromatic curable compound that is liquid at 25°C]
Component (C) is a non-aromatic curable compound that is liquid at 25° C. (hereinafter sometimes referred to as “curable compound (C)”).
Curable compound (C) can be used individually by 1 type or in combination of 2 or more types.

The curable compound (C) is a curable compound. Therefore, if the curable compound (C) is the curable component (X) that does not participate in the curing reaction (I), the curable adhesive layer containing this curable compound (C) will not participate in the curing reaction (II). It has curability derived from

The curable compound (C) is a compound that is liquid at 25°C. Therefore, when the curable compound (C) is the curable component (X) that does not participate in the curing reaction (I), the curable adhesive layer containing this curable compound (C) exhibits good wettability during lamination. It has spreadability and is excellent in lamination aptitude.
"Liquid at 25°C" means having fluidity at 25°C. For example, a compound that is liquid at 25° C. is a compound with a viscosity of 2 to 10000 mPa·s measured at 25° C. and 1.0 rpm using an E-type viscometer.

The curable compound (C) is a non-aromatic compound. A non-aromatic compound means a compound without an aromatic ring. Since the curable compound (C) is a non-aromatic compound, the curable adhesive layer containing the curable compound (C) tends to have excellent low dielectric properties.

The curable compound (C) is preferably a compound having a heterocyclic skeleton. When the curable compound (C) is a compound having a heterocyclic skeleton, it becomes easier to form a curable adhesive layer that gives a cured product with excellent adhesive strength and low dielectric properties.
(C) When the raw material composition is a compound having a heterocyclic skeleton, the raw material composition may contain, as other components, a curable compound other than the compound having the heterocyclic skeleton. good.
In the raw material composition, the content of the other curable compound is preferably 0 to 50 parts by mass, more preferably 0 to 30 parts by mass, and more preferably 0 to 30 parts by mass, relative to 100 parts by mass of the total amount of the compound having a heterocyclic skeleton. It is preferably 0 to 10 parts by weight, and more preferably 0 to 5 parts by weight.
The heterocyclic skeleton includes an isocyanurate skeleton and a glycoluril skeleton.
The heterocyclic skeleton preferably has an n-fold rotation axis as a symmetry element. A curable adhesive layer containing such a curable compound (C) having a heterocyclic skeleton tends to have excellent low dielectric properties.

The molecular weight of the curable compound (C) is preferably 1,000 or less, more preferably 800 or less, still more preferably 650 or less, and even more preferably 500 or less.
Curable compounds with a molecular weight of 1,000 or less tend to meet the requirement of being liquid at 25°C.
Moreover, the molecular weight of the curable compound (C) is preferably 100 or more, more preferably 200 or more, and even more preferably 275 or more.
The curable compound (C) having a molecular weight of 100 or more is difficult to volatilize even when heat treatment is performed when forming the curable adhesive layer or when using the curable adhesive layer. By adding a curable compound (C) having a high molecular weight to the layer, it becomes easier to obtain a cured product having the desired physical properties.

As the curable compound (C), for example, a compound having two or more hydrocarbon groups having double bonds at the terminals (hereinafter, this compound may be referred to as "curable compound (C')"). mentioned.
By using the curable compound (C′) as the curable compound (C), it becomes easier to form a curable adhesive layer that gives a cured product with excellent low dielectric properties.
When the raw material composition in which the component (C) is the curable compound (C'), the raw material composition contains, as another component, a curable compound other than the curable compound (C'). You may
In the raw material composition, the content of the other curable compound is preferably 0 to 50 parts by mass, more preferably 0 to 30 parts by mass, with respect to 100 parts by mass of the total amount of the curable compound (C'), More preferably 0 to 10 parts by mass, and even more preferably 0 to 5 parts by mass.

The number of carbon atoms in the hydrocarbon group having a double bond at the end contained in the curable compound (C') is preferably 2-10, more preferably 2-5.
Hydrocarbon groups having a double bond at the end include vinyl group, allyl group, 3-butenyl group, 4-pentenyl group, 5-hexenyl group, isopropenyl group, 1-methyl-2-propenyl group and vinylbenzyl group. , a vinyl naphthyl group, and the like. Among these, an allyl group is preferred.

The number of hydrocarbon groups having a double bond at the terminal contained in the curable compound (C') is two or more. When the number of hydrocarbon groups having a double bond at the terminal is 2 or more, it becomes easier to form a curable adhesive layer that gives a cured product with excellent adhesive strength and heat resistance.
In addition, when the crosslinked structure formed in the cured product is moderately sparse, the occurrence of cracks in the cured product tends to be suppressed. Therefore, the number of hydrocarbon groups having a double bond at the end is preferably 2-4, more preferably 2.

Examples of the curable compound (C') include a curable compound (C') having an isocyanurate skeleton and a curable compound (C') having a glycoluril skeleton.
Examples of the curable compound (C') having an isocyanurate skeleton include compounds represented by the following formula (1) or (2).

In formula (1), R ¹ and R ² each independently represent a hydrocarbon group having a double bond at the end; R ³ is a saturated hydrocarbon group having 1 to 15 carbon atoms; represents an alkoxy group-substituted alkyl group.
In formula (2), R ⁴ to R ⁶ each independently represent a hydrocarbon group having a double bond at its end.

The hydrocarbon groups having a double bond at the end represented by R ¹ , R ² , R ⁴ , R ⁵ and R ⁶ are as explained above.

The saturated hydrocarbon group represented by R ³ has 1 to 15 carbon atoms, preferably 5 to 15 carbon atoms, and more preferably 8 to 15 carbon atoms. Examples of saturated hydrocarbon groups represented by R ³ include 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, 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. is mentioned.

The alkoxy group-substituted alkyl group represented by R ³ has 2 to 15 carbon atoms, preferably 2 to 12 carbon atoms, and more preferably 3 to 10 carbon atoms. The alkoxy-substituted alkyl group represented by R ³ includes methoxymethyl group, ethoxymethyl group, 2-methoxyethoxymethyl group, benzyloxymethyl group and the like.

Examples of the curable compound (C') having a glycoluril skeleton include compounds represented by the following formula (3).

In formula (3), R ⁷ to R ¹⁰ each independently represent a hydrocarbon group having 1 to 15 carbon atoms, at least two of which are hydrocarbon groups having double bonds at their ends. R ¹¹ and R ¹² each represent a hydrogen atom or a saturated hydrocarbon group having 1 to 15 carbon atoms.

Among these, a compound having an isocyanurate skeleton is preferable as the curable compound (C′), since a cured product having an appropriate crosslink density and excellent low dielectric properties can be easily obtained. A compound represented by is more preferable, and a compound represented by the following formula is even more preferable.

In the formula, R represents a saturated hydrocarbon group having 5 to 15 carbon atoms, preferably a saturated hydrocarbon group having 8 to 15 carbon atoms.

When the raw material composition contains a curable compound (C), the content of the curable compound (C) (when two or more curable compounds (C) are included, the total amount of these) is It is preferably 5% by mass or more, more preferably 7% by mass or more, still more preferably 8.5% by mass or more, and preferably 25% by mass or less with respect to the total amount (100% by mass) of the active ingredient. , more preferably 20% by mass or less, and still more preferably 15% by mass or less.
When the content of the curable compound (C) is 5% by mass or more based on the total amount of active ingredients in the raw material composition, a curable adhesive layer that provides a cured product with excellent adhesive strength is easily formed.
When the content of the curable compound (C) is 25% by mass or less based on the total amount of active ingredients in the raw material composition, a curable adhesive layer that provides a cured product with excellent low dielectric properties can be easily formed.

When the raw material composition used in one aspect of the present invention contains the curable compound (C), the content of the curable compound (C) (two or more curable compounds (C ) is preferably 3 parts by mass or more, more preferably 5 parts by mass or more, still more preferably 7 parts by mass or more, still more preferably 10 parts by mass or more, and preferably It is 30 parts by mass or less, more preferably 25 parts by mass or less, still more preferably 20 parts by mass or less, and even more preferably 16 parts by mass or less.

[(D) component: polyphenylene ether resin having a reactive functional group]
Component (D) is a polyphenylene ether resin having a reactive functional group (hereinafter sometimes referred to as "polyphenylene ether resin (D)").
A polyphenylene ether resin is a resin having a polyphenylene skeleton in its main chain.
A polyphenylene skeleton refers to a skeleton having a repeating unit represented by the following formula or a repeating unit in which hydrogen atoms in the above formula are substituted.

Polyphenylene ether resin (D) is a compound having a polyphenylene ether skeleton and a reactive functional group.
Since the polyphenylene ether resin (D) has a polyphenylene ether skeleton, the curable adhesive layer containing the polyphenylene ether resin (D) is excellent in low dielectric properties.
Moreover, since the polyphenylene ether resin (D) has a reactive functional group, the cured product of the curable adhesive layer containing the polyphenylene ether resin (D) has excellent heat resistance.
Polyphenylene ether resin (D) can be used individually by 1 type or in combination of 2 or more types.

Examples of the polyphenylene ether skeleton in the polyphenylene ether resin (D) include those represented by the following formula (4).

In formula (4), X is a divalent group represented by the following formula (5) or formula (6), and each Y is independently a divalent group represented by the following formula (7) is a group, a and b are integers of 0 to 100, and at least one of a and b is 1 or more. * represents a bond (same below).

In formula (5), R ¹³ to R ²⁰ each independently represent a hydrogen atom, a halogen atom, an alkyl group having 6 or less carbon atoms, or a phenyl group, preferably a hydrogen atom or a methyl group.

In formula (6), R ²¹ to R ²⁸ each independently represent a hydrogen atom, a halogen atom, an alkyl group having 6 or less carbon atoms, or a phenyl group, preferably a hydrogen atom or a methyl group. A represents a linear, branched or cyclic divalent hydrocarbon group having 20 or less carbon atoms.

In formula (7), R ²⁹ to R ³² each independently represent a hydrogen atom, a halogen atom, an alkyl group having 6 or less carbon atoms, or a phenyl group, preferably a hydrogen atom or a methyl group.

Examples of the polyphenylene ether skeleton in the polyphenylene ether resin (D) include those represented by the following formula (8).

(a and b are integers from 0 to 100, and at least one of a and b is 1 or more.)

Examples of reactive functional groups in the polyphenylene ether resin (D) include groups having an ethylenically unsaturated bond such as vinyl, allyl, acryloyl, methacryloyl, cyclopentenyl, vinylbenzyl, and vinylnaphthyl; group; hydroxyl group; and the like.
Among these, the reactive functional group is preferably a group having an ethylenically unsaturated bond, more preferably a vinylbenzyl group, since a cured product having excellent low dielectric properties can be easily obtained.

As the polyphenylene ether resin (D), a resin having a reactive functional group at both ends of the polyphenylene ether skeleton is preferable because a cured product having excellent low dielectric properties can be easily obtained.
(D) When the raw material composition is a resin having a reactive functional group at both ends of the polyphenylene ether skeleton, the raw material composition contains, as another component, reactive functional groups at both ends of the polyphenylene ether skeleton. A polyphenylene ether resin other than the resin having a group may be contained.
In the raw material composition, the content of the other polyphenylene ether resin is preferably 0 to 50 parts by mass, more preferably 100 parts by mass of the total amount of the resin having reactive functional groups at both ends of the polyphenylene ether skeleton. is 0 to 30 parts by mass, more preferably 0 to 10 parts by mass, and even more preferably 0 to 5 parts by mass.

The polyphenylene ether resin (D) can be obtained by forming a polyphenylene ether skeleton and then introducing a reactive functional group to the terminal.
For example, a polyphenylene ether resin (D) having vinylbenzyl groups at both ends as reactive functional groups was reacted with a bifunctional phenol compound and a monofunctional phenol compound to obtain a polymer having phenolic hydroxyl groups at both ends. Then, it can be obtained by vinylbenzyl etherifying the terminal phenolic hydroxyl group using 4-(chloromethyl)styrene.

Examples of the polyphenylene ether resin (D) include compounds represented by the following formula (9).

(In the above formula, a and b are integers of 0 to 100, and at least one of a and b is 1 or more.)

(D) When the raw material composition is a compound represented by the above formula (9), the raw material composition contains, as another component, a polyphenylene other than the compound represented by the above formula (9) It may contain an ether resin.
In the raw material composition, the content of the other polyphenylene ether resin is preferably 0 to 50 parts by mass, more preferably 0 to 30 parts by mass, with respect to 100 parts by mass of the total amount of the compound represented by the above formula (9). parts, more preferably 0 to 10 parts by weight, and even more preferably 0 to 5 parts by weight.

The number average molecular weight (Mn) of the polyphenylene ether resin (D) is preferably 500 to 5,000, more preferably 500 to 3,000, still more preferably 700 to 2,500, still more preferably 1,000 to 2. , 000.
The number average molecular weight (Mn) of the polyphenylene ether resin (D) is obtained by gel permeation chromatography (GPC) using tetrahydrofuran (THF) as a solvent, and can be obtained as a standard polystyrene conversion value, and specific measurement conditions is as described above.

When the raw material composition contains a polyphenylene ether resin (D), the content of the polyphenylene ether resin (D) (when two or more (D) components are included, the total amount of these) is the active ingredient of the raw material composition The total amount (100% by mass) of preferably 1% by mass or more, more preferably 5% by mass or more, still more preferably 10% by mass or more, still more preferably 15% by mass or more, and preferably 30% by mass % by mass or less, more preferably 25% by mass or less.
When the content of the polyphenylene ether resin (D) is 1% by mass or more based on the total amount of active ingredients in the raw material composition, a curable adhesive layer that provides a cured product with excellent low dielectric properties is easily formed.
When the content of the polyphenylene ether resin (D) is 30% by mass or less in the total amount of active ingredients in the raw material composition, a curable adhesive layer with excellent sticking properties is easily formed.

When the raw material composition used in one aspect of the present invention contains the polyphenylene ether resin (D), the content of the polyphenylene ether resin (D) with respect to 100 parts by mass of the component (A) (two or more (D) components The total amount of these when included) is preferably 5 parts by mass or more, more preferably 10 parts by mass or more, still more preferably 15 parts by mass or more, still more preferably 20 parts by mass or more, and preferably 50 parts by mass parts or less, more preferably 40 parts by mass or less, even more preferably 35 parts by mass or less, still more preferably 30 parts by mass or less.

[(F) component: silane coupling agent]
The raw material composition may contain a silane coupling agent (F) as a curable component (X).
The silane coupling agents (F) can be used singly or in combination of two or more.

A known silane coupling agent can be used as the silane coupling agent (F). Among them, organosilicon compounds having at least one alkoxysilyl group in the molecule are preferred.
Silane coupling agents (F) include 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, 3-methacryloxypropyltriethoxysilane, 3-acryloxypropyl Silane coupling agents having a (meth)acryloyl group such as roxypropyltrimethoxysilane;
Silane coupling agents having a vinyl group such as vinyltrimethoxysilane, vinyltriethoxysilane, dimethoxymethylvinylsilane, diethoxymethylvinylsilane, trichlorovinylsilane, vinyltris(2-methoxyethoxy)silane;
2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-glycidoxypropyltriethoxysilane, 8-glycid Silane coupling agents having an epoxy group such as xyoctyltrimethoxysilane;
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-aminopropyltriethoxysilane , 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-triethoxysilyl-N-(1,3-dimethylbutylidene)propylamine, N-phenyl-3-aminopropyltrimethoxysilane, N - Silane coupling agents having an amino group such as hydrochloride of (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-isocyanatopropyltrimethoxysilane and 3-isocyanatopropyltriethoxysilane;
Silane coupling agents having an allyl group such as allyltrichlorosilane, allyltriethoxysilane, allyltrimethoxysilane;
silane coupling agents having a hydroxyl group such as 3-hydroxypropyltrimethoxysilane and 3-hydroxypropyltriethoxysilane;

When the raw material composition contains a silane coupling agent (F), the content of the silane coupling agent (F) (when two or more silane coupling agents (F) are included, the total amount of these) is the raw material It is preferably 0.01% by mass or more, more preferably 0.05% by mass or more, still more preferably 0.08% by mass or more, and preferably is 5% by mass or less, more preferably 3% by mass or less, still more preferably 1% by mass or less, and even more preferably 0.5% by mass or less.
The content of the silane coupling agent (F) is 0.01% by mass or more in the total amount of active ingredients in the raw material composition, so that the curable adhesive layer gives a cured product having excellent adhesion after a high temperature and high humidity test. becomes easier to form.
When the content of the silane coupling agent (F) is 5% by mass or less in the total amount of active ingredients in the raw material composition, a curable adhesive layer that gives a cured product with excellent adhesion after a high-temperature and high-humidity test is formed. easier to be

When the raw material composition used in one aspect of the present invention contains the silane coupling agent (F), the content of the silane coupling agent (F) with respect to 100 parts by mass of the component (A) (two or more silane coupling The total amount of these when the agent (F) is included is preferably 0.01 parts by mass or more, more preferably 0.05 parts by mass or more, still more preferably 0.1 parts by mass or more, and even more preferably 0.1 part by mass or more. It is 15 parts by mass or more, preferably 3 parts by mass or less, more preferably 1 part by mass or less, still more preferably 0.7 parts by mass or less, and even more preferably 0.5 parts by mass or less.

[(E) component: cationic polymerization initiator]
The raw material composition may contain a cationic polymerization initiator as the (E) component.
When the curing reaction (I) or the curing reaction (II) is a cationic polymerization reaction, adding a cationic polymerization initiator to the raw material composition allows these curing reactions to proceed efficiently.
A cationic polymerization initiator can be used individually by 1 type or in combination of 2 or more types.
Examples of the cationic polymerization initiator (E) include thermal cationic polymerization initiators and photocationic polymerization initiators, and preferred are thermal cationic polymerization initiators that can be polymerized by a simple process.

Thermal cationic polymerization initiators are compounds that can generate cationic species that initiate polymerization upon heating.
Thermal cationic polymerization initiators include sulfonium salts, quaternary ammonium salts, phosphonium salts, diazonium salts, iodonium salts and the like.

Sulfonium salts include triphenylsulfonium tetrafluoroborate, triphenylsulfonium hexafluoroantimonate, triphenylsulfonium hexafluoroalcinate, tris(4-methoxyphenyl)sulfonium hexafluoroalcinate, and diphenyl(4-phenylthiophenyl)sulfonium. hexafluoroalcinate and the like.

The quaternary ammonium salts include tetrabutylammonium tetrafluoroborate, tetrabutylammonium hexafluorophosphate, tetrabutylammonium hydrogensulfate, tetraethylammonium tetrafluoroborate, tetraethylammonium p-toluenesulfonate, N,N-dimethyl-N- benzylanilinium hexafluoroantimonate, N,N-dimethyl-N-benzylanilinium tetrafluoroborate, N,N-dimethyl-N-benzylpyridinium hexafluoroantimonate, N,N-diethyl-N-benzyltrifluoromethanesulfonate , N,N-dimethyl-N-(4-methoxybenzyl)pyridinium hexafluoroantimonate, N,N-diethyl-N-(4-methoxybenzyl)toluidinium hexafluoroantimonate, and the like.

Phosphonium salts include ethyltriphenylphosphonium hexafluoroantimonate, tetrabutylphosphonium hexafluoroantimonate, and the like.

Examples of iodonium salts include diphenyliodonium hexafluoroarsinate, bis(4-chlorophenyl)iodonium hexafluoroarsinate, bis(4-bromophenyl)iodonium hexafluoroarsinate, phenyl(4-methoxyphenyl)iodonium hexafluoroarsinate, and the like. are mentioned.

When the raw material composition contains the cationic polymerization initiator (E), the content of the cationic polymerization initiator (E) (when two or more (E) components are included, the total amount of these) is the cationic polymerizable compound is preferably 0.01 parts by mass or more, more preferably 0.05 parts by mass or more, still more preferably 0.1 parts by mass or more, and more More preferably 0.2 parts by mass or more, preferably 6 parts by mass or less, more preferably 5 parts by mass or less, and even more preferably 4 parts by mass or less.
When the content of the cationic polymerization initiator is 0.01 parts by mass or more, it becomes easier to prevent a decrease in reactivity.
When the content of the cationic polymerization initiator is 6 parts by mass or less, it becomes easy to suppress corrosion of the adherend.

〔solvent〕
The raw material composition may contain a solvent and be in the form of a solution.
Examples of solvents include aromatic hydrocarbon solvents such as benzene and toluene; ester solvents such as ethyl acetate and butyl acetate; ketone solvents such as acetone, methyl ethyl ketone and methyl isobutyl ketone; aliphatic hydrocarbon solvents such as heptane; alicyclic hydrocarbon solvents such as cyclopentane, cyclohexane, and methylcyclohexane; and the like.
These solvents can be used singly or in combination of two or more.
When the raw material composition contains a solvent, the content of the solvent can be appropriately determined in consideration of coatability and the like.

[Other ingredients]
The raw material composition may contain components (other components) other than those described above as long as the effects of the present invention are not impaired.
Other components include additives such as UV absorbers, antistatic agents, light stabilizers, antioxidants, resin stabilizers, fillers, pigments, extenders and softeners.
These can be used individually by 1 type or in combination of 2 or more types.
When the raw material composition contains these additives, the content thereof can be appropriately determined according to the purpose.

[Method for producing raw material composition]
The raw material composition can be prepared by appropriately mixing and stirring the binder resin (A), the cross-linking agent (B), and other optional components according to a conventional method.

<<Curable adhesive layer>>
The curable adhesive layer constituting the adhesive sheet of the present invention is a layer formed using the raw material composition.

For example, a curable adhesive layer can be formed by applying the raw material composition onto a process sheet or a protective sheet, drying the resulting coating film, and allowing the curing reaction (I) to proceed. .

Examples of methods for applying the raw material composition include spin coating, spray coating, bar coating, knife coating, roll coating, blade coating, die coating, and gravure coating.

Methods for drying the coating film include conventionally known drying methods such as hot air drying, hot roll drying, and infrared irradiation.
The conditions for drying the coating film are, for example, 80 to 150° C. for 30 seconds to 5 minutes.

When the curing reaction (I) is a reaction initiated by heat, the drying treatment of the coating film and the curing reaction (I) can be combined.
For example, the reactive functional group in the binder resin (A) is a carboxy group or a carboxylic anhydride group, and the cross-linking agent (B) is an isocyanate-based cross-linking agent, an epoxy-based cross-linking agent, a metal chelate-based cross-linking agent, or the like. In this case, by heating the coating film to about 100° C., the drying treatment and the curing reaction (I) can be performed simultaneously, and the curable adhesive layer can be efficiently formed.

The thickness of the curable adhesive layer is usually 1 μm or more, preferably 5 μm or more.
The thickness of the curable adhesive layer is usually 50 µm or less, preferably 25 µm or less.
When the thickness of the curable adhesive layer is 1 μm or more, it is easy to follow a step, and it is easy to obtain adhesiveness.
When the thickness of the curable adhesive layer is 50 μm or less, the rigidity is not excessively increased, and flexibility is easily obtained.

The gel fraction of the curable adhesive layer is 10% by mass or more, preferably 15% by mass or more, more preferably 20% by mass or more, and particularly preferably 25% by mass or more.
The gel fraction of the curable adhesive layer is usually 70% by mass or less, preferably 60% by mass or less, and more preferably less than 50% by mass.
A curable adhesive layer having a gel fraction of 10% by mass or more has a sufficiently formed crosslinked structure as a curable adhesive layer. Therefore, even if such a curable adhesive layer is subjected to heat treatment such as hot press treatment, a large amount of the adhesive component does not ooze out, and contamination of the surroundings is suppressed.
When the gel fraction of the curable adhesive layer is 70% by mass or less, a curable adhesive layer having excellent curability and adhesion to an adherend can be easily formed.
The gel fraction of the curable adhesive layer can be calculated by performing an experiment in which the curable adhesive layer is immersed in toluene at 23° C. for 168 hours, as described in Examples.

The curable adhesive layer preferably has low dielectric properties. A curable adhesive layer having low dielectric properties is preferably used as a material for forming adhesive members, protective members, insulating members, and the like in electronic devices.

The dielectric loss tangent of the curable adhesive layer at 23° C. and a frequency of 1 GHz is preferably less than 0.0050, more preferably 0.0030 or less, more preferably 0.0020 or less, still more preferably 0.0015 or less. , more preferably 0.0012 or less, still more preferably 0.0010 or less, and particularly preferably 0.0008 or less. Although there is no particular lower limit for the dielectric loss tangent under these conditions, it is usually 0.0001 or more.

The dielectric constant of the curable adhesive layer at 23°C and a frequency of 1 GHz is preferably 3.00 or less, more preferably 2.75 or less, and still more preferably 2.50 or less. Although there is no particular lower limit for the dielectric constant under these conditions, it is usually 2.00 or more.

The curable adhesive layer is a curable layer.
As described above, the raw material composition of the curable adhesive layer includes, as the curing reaction, one having only the curing reaction (I) [raw material composition (α)], and as the curing reaction, the curing reaction (I ) and curing reaction (II) [raw material composition (β)].
The "curability" of the curable adhesive layer formed using the raw material composition (α) is determined by the reaction between the unreacted binder resin (A) and the cross-linking agent (B) in the curable adhesive layer (i.e. , curing reaction (I)).
On the other hand, the "curability" of the curable adhesive layer formed using the raw material composition (β) is usually due to both curing reaction (I) and curing reaction (II), or curing It is due only to reaction (II).

The curing conditions for the curable adhesive layer can be appropriately determined according to the curable component contained in the curable adhesive layer.
For example, when the curable adhesive layer is a thermosetting adhesive layer containing the components (C) and (D) as curable components, heating the curable adhesive layer causes the curable The curing reaction of the adhesive layer can proceed efficiently.
The heating temperature for this curable adhesive layer is usually 140°C or higher, preferably 150 to 180°C.
The heating time for this curable adhesive layer is usually 0.5 to 3 hours, preferably 1 to 2 hours.

In the cured product formed by curing the curable adhesive layer, more crosslinked structures are usually formed than in the curable adhesive layer. Therefore, the gel fraction of the cured product is usually larger than the gel fraction of the curable adhesive layer.
When the cured product of the curable adhesive layer functions as an adhesive member, a protective member, an insulating member, or the like, the cured product preferably undergoes a sufficient curing reaction.
The gel fraction of the cured product in such a state is preferably 50% by mass or more, more preferably 55% by mass or more.
Although there is no particular upper limit for the gel fraction of the cured product in which the curing reaction has sufficiently progressed, it is usually 95% by mass or less, preferably 90% by mass or less.
The gel fraction of the cured product can be determined by a method similar to the method for calculating the gel fraction of the curable adhesive layer.

Since it is suitable as a material for forming adhesive members, protective members, insulating members, etc., it gives a cured product with a gel fraction of 50% by mass or more after curing at 160° C. for 1 hour as a curable adhesive layer. things are preferred.

《Adhesive sheet》
The adhesive sheet of the present invention has the curable adhesive layer.
The adhesive sheet of the present invention may have a protective sheet or the like on one side or both sides for protection during storage or transportation.

The adhesive sheet of the present invention is suitably used as an adhesive sheet for electronic devices.
Examples of electronic devices include communication devices such as smartphones and tablet terminals.
For example, the curable adhesive layer that constitutes the adhesive sheet of the present invention can be used to adhere various parts in an electronic device, or to form a protective material or insulating material for circuits in an electronic device.

The adhesive sheet of the present invention is suitably used as an adhesive sheet for coverlay films. A coverlay film is, for example, a laminated film used to protect the surface of a flexible printed wiring board, and usually has an insulating resin layer and an adhesive layer.
For example, a coverlay film can be produced by thermocompression bonding a curable adhesive layer constituting the adhesive sheet of the present invention with an insulating resin film.

The present invention will be described in more detail below with reference to examples. However, the present invention is by no means limited to the following examples.

[Compounds used in Examples or Comparative Examples]
- Binder resin (A1): maleic anhydride-modified α-olefin polymer [manufactured by Mitsui Chemicals, trade name: UNISTOL H-200, number average molecular weight: 47,000]
Isocyanate-based cross-linking agent (B1): 1,3,5-tris(5-isocyanatopentyl)-1,3,5-triazine-2,4,6-trione [manufactured by Mitsui Chemicals, Inc., trade name: Stabio D-370N, molecular weight: 462]
Epoxy-based cross-linking agent (B2): 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane, [manufactured by Mitsubishi Gas Chemical Company, Inc., trade name: TETRAD-C, molecular weight: 362]
- Metal chelate-based cross-linking agent (B3): aluminum tris (acetylacetonate) [manufactured by Soken Chemical Co., Ltd., trade name: M-5A, molecular weight: 324]
Curable compound (C1): a compound having an isocyanurate skeleton and two allyl groups [manufactured by Shikoku Kasei Kogyo Co., Ltd., trade name: L-DAIC]
- Polyphenylene ether resin (D1): vinylbenzyl-modified polyphenylene ether [manufactured by Mitsubishi Gas Chemical Company, trade name: OPE-2St 1200, number average molecular weight: 1200]
- Cationic polymerization initiator (E1): Thermal cationic polymerization initiator [manufactured by Sanshin Chemical Industry Co., Ltd., product name: San-Aid SI-B3]
- Silane coupling agent (F1): 8-glycidoxyoctyltrimethoxysilane [manufactured by Shin-Etsu Chemical Co., Ltd., trade name: KBM4803]

[Example 1]
Binder resin (A1) 100 parts by mass, isocyanate cross-linking agent (B1) 0.5 parts by mass, curable compound (C1) 12.5 parts by mass, polyphenylene ether resin (D1) 25 parts by mass, cationic polymerization initiator (E1) 0.12 parts by mass and 0.2 parts by mass of the silane coupling agent (F1) were dissolved in toluene to prepare a raw material composition.
The obtained raw material composition is applied on the release-treated surface of a release sheet (first release sheet, product name: SP-PET752150, manufactured by Lintec Corporation) to form a coating film, and the resulting coating film is C. for 2 minutes to form a curable adhesive layer with a thickness of 15 .mu.m. On the exposed surface of this curable adhesive layer, another release sheet (second release sheet, product name: SP-PET381130, manufactured by Lintec Corporation) is laminated to obtain an adhesive sheet. rice field.

[Examples 2 to 5, Comparative Example 1]
A raw material composition was prepared and an adhesive sheet was obtained in the same manner as in Example 1, except that the amounts or types of the components were changed to those shown in Table 1.

[Gel Fraction of Curable Adhesive Layer]
After cutting the adhesive sheet obtained in Examples or Comparative Examples into a size of 80 mm long×80 mm wide, both release sheets were peeled off to obtain a curable adhesive layer. Next, the resulting curable adhesive layer was wrapped in a pre-weighed polyester mesh (mesh size 200) to prepare a test sample. After the test sample was allowed to stand in an environment with a temperature of 23° C. and a relative humidity of 50% for 24 hours, the mass of the test sample was weighed with a precision balance. Based on the obtained measured value, the mass (M1) of the curable adhesive layer before immersion was calculated.
Next, the test sample was immersed in 0.2 L of toluene at room temperature (23° C.) for 168 hours. After the immersion, the test sample was taken out, dried in an oven at 100°C for 2 hours, and then allowed to stand for 24 hours in an environment with a temperature of 23°C and a relative humidity of 50%. The mass of the test sample after drying was weighed with a precision balance. Based on the measured values obtained, the mass (M2) of the curable adhesive layer after immersion and drying was calculated.
From the value of M1 and the value of M2, the gel fraction of the curable adhesive layer was calculated by the following formula.
・Gel fraction (% by mass) = (M2/M1) x 100

[Gel fraction of cured product]
The adhesive sheets obtained in Examples or Comparative Examples were cut into a size of 80 mm long×80 mm wide, and then heated in an oven at 160° C. for 1 hour. Using the cured product obtained by peeling off the release sheet, the gel fraction of the cured product was calculated in the same manner as described above.

[Evaluation of component exudation]
One release sheet of the adhesive sheet obtained in Examples or Comparative Examples was peeled off, and the exposed curable adhesive layer was covered with a polyimide film (manufactured by DuPont-Toray, Kapton, thickness 25 μm) at 100° C. using a heat laminator. to obtain a laminate having a structure of release sheet/curable adhesive layer/polyimide film. Then, the release sheet of this laminate is peeled off, and the exposed curable adhesive layer is pressed against copper foil at 100° C. using a heat laminator to laminate a structure of copper foil/curable adhesive layer/polyimide film. got a body Since the copper foil has a larger area than the other two layers, when the adhesive component of the curable adhesive layer seeps out, it adheres to the copper foil.
This laminate was subjected to a heat press treatment under conditions of 171° C. and 1.38 MPa for 20 minutes.
After cooling, the length of the most exuded adhesive component from the adhesive layer (cured product) in plan view [the length (μm) of the portion indicated by X in FIG. 1] was measured using a digital microscope. . The results are shown in Table 1. In addition, FIG. 1 is a schematic plan view of the laminated body used for evaluating the exudation of the adhesive component in the examples after being subjected to a heat press treatment. As shown in FIG. 1, a part of the adhesive layer (cured material) sandwiched between the copper foil 1 and the polyimide film 3 of the laminate oozes out and is deposited on the copper foil 1 by the heat press treatment. The exuded adhesive component 2 may adhere. At this time, as shown in FIG. 1, the maximum value X of the distance between the oozing adhesive component 2 and the polyimide film 3 when viewed from the top is defined as "the oozing length of the adhesive component", and is shown in Table 1. described.

[Dielectric constant, dielectric loss tangent]
After stacking a plurality of curable adhesive layers of the adhesive sheets obtained in Examples or Comparative Examples so as to have a thickness of about 1 mm, a heat laminator is used to perform fusion bonding at 100 ° C., and a release sheet / about A laminate of the structure curable adhesive layer/release sheet with a thickness of 1 mm was obtained. The release sheets on both sides of this laminate were peeled off to obtain a sample for measurement.
The dielectric constant and dielectric loss tangent at 23° C. and 1 GHz were measured using an RF impedance material analyzer (manufactured by Keysight Technologies, E4991A) for the obtained measurement sample. In this specification, the high frequency region refers to the region of 300 MHz to 300 GHz, but in this embodiment, 1 GHz is used as an example of the high frequency region. The results are shown in Table 1.

The curable adhesive layers of the adhesive sheets obtained in Examples 1 to 5 all have high gel fraction values. Therefore, even if these curable adhesive layers are subjected to heat press treatment under the conditions of 171° C., 1.38 MPa, and 20 minutes, the amount of the adhesive components oozing out is small.
On the other hand, the curable adhesive layer of the adhesive sheet of Comparative Example 1 has a low gel fraction value. For this reason, if the heat press treatment is performed on this curable adhesive layer under the same conditions, the amount of the adhesive component oozing out is large.
Moreover, the curable adhesive layers of the adhesive sheets obtained in Examples 1 to 5 are excellent in low dielectric properties.

1: Copper foil 2: Exuded adhesive component 3: Polyimide film

Claims

An adhesive sheet having a curable adhesive layer,
The raw material composition of the curable adhesive layer contains the following components (A) and (B), and the amount of component (B) is 0.1 mass based on the total amount of active ingredients in the raw material composition. % or more,
The adhesive sheet, wherein the curable adhesive layer has a gel fraction of 10% by mass or more.
(A) component: binder resin having a reactive functional group (B) component: cross-linking agent capable of reacting with component (A)
The adhesive sheet according to claim 1, wherein the component (A) is a polyolefin resin.
The adhesive sheet according to claim 1 or 2, wherein the component (A) is an acid-modified resin.
The adhesive sheet according to any one of claims 1 to 3, wherein the component (B) is a compound having an isocyanurate skeleton.
The adhesive sheet according to any one of claims 1 to 4, wherein the component (B) is a compound having two or more isocyanate groups.
The adhesive sheet according to any one of claims 1 to 5, wherein the curable adhesive layer is a layer formed from a raw material composition further containing component (C) below.
Component (C): A non-aromatic curable compound that is liquid at 25°C
The adhesive sheet according to claim 6, wherein the component (C) is a compound having two or more hydrocarbon groups with double bonds at their ends.
The adhesive sheet according to any one of claims 1 to 7, wherein the curable adhesive layer is a layer formed from a raw material composition further containing component (D) below.
(D) component: polyphenylene ether resin having a reactive functional group
The adhesive sheet according to any one of claims 1 to 8, wherein the curable adhesive layer is a layer formed from a raw material composition further containing component (E) below.
(E) component: cationic polymerization initiator
The adhesive sheet according to any one of claims 1 to 9, wherein the curable adhesive layer has a dielectric loss tangent of less than 0.005 at 23°C and a frequency of 1 GHz.
The adhesive sheet according to any one of claims 1 to 10, wherein the curable adhesive layer has a dielectric constant of 3.00 or less at 23°C and a frequency of 1 GHz.
The adhesive sheet according to any one of claims 1 to 11, wherein the curable adhesive layer gives a cured product having a gel fraction of 50% by mass or more after curing at 160°C for 1 hour. .
The adhesive sheet according to any one of claims 1 to 12, which is used for electronic devices.
The adhesive sheet according to any one of claims 1 to 12, which is used for a coverlay film.