WO2013002001A1 - Thermosetting adhesive sheet and flexible printed circuit board - Google Patents

Abstract

The purpose of the present invention is to provide a thermosetting adhesive sheet having a thermosetting adhesive agent layer which, after being cured, can achieve excellent adhesiveness and extremely high heat resistance after exposure to humidity and heat. This thermosetting adhesive sheet is characterized by having a thermosetting adhesive agent layer that has a glass transition point in the range from -50°C to 10°C inclusive and a glass transition point in the range from 20°C to 100°C inclusive.

Description

Thermosetting adhesive sheet and flexible printed circuit board

The present invention relates to a thermosetting adhesive sheet having a thermosetting adhesive layer. More specifically, the present invention relates to a thermosetting adhesive sheet that can be preferably used for a flexible printed circuit board or the like. The present invention also relates to a flexible printed circuit board having the thermosetting adhesive sheet.

In electronic devices, flexible printed circuit boards (sometimes referred to as “FPC”) are widely used. In such an FPC, (1) a process of manufacturing an FPC by bonding and laminating a conductive metal foil such as a copper foil or an aluminum foil on a heat-resistant substrate such as a polyimide substrate or a polyamide substrate, 2) An adhesive is used in the process of bonding the FPC to a reinforcing plate such as an aluminum plate, a stainless steel plate, or a polyimide plate.

A thermosetting adhesive containing a thermosetting resin such as a phenol resin or an epoxy resin is known as an adhesive used for bonding such an FPC. These thermosetting adhesives exhibit an adhesive force when, for example, the thermosetting resin contained in the adhesive is cured by heating at 150 ° C. or higher.

When a laminated body produced by bonding an adherend (FPC or the like) using the thermosetting adhesive is processed in a high temperature process such as a reflow process, the adhesive, moisture contained in the adherend, etc. As a result of evaporation of the adhesive, foaming (blowing) or lifting off of the adhesive may occur. Therefore, after solving the above problems, excellent adhesiveness and heat resistance after moist heat after curing (property that foaming and peeling off of the adhesive layer is less likely to occur even when processed under high temperature process after storage under high temperature and high humidity conditions. As a thermosetting adhesive sheet having a thermosetting adhesive layer capable of exhibiting a thermosetting adhesive layer formed from a thermosetting adhesive composition mainly composed of an acrylic polymer and further containing an etherified phenol resin. A thermosetting adhesive sheet having an agent layer is known (see Patent Document 1).

International Publication No. 2011/004710 Pamphlet

However, in recent years, there is a need for higher heat resistance after wet heat that does not cause foaming or peeling even under strict processing conditions (conditions for processing at high temperatures for a longer time) than conventional high-temperature processes such as a reflow process. It is becoming. In response to such a demand, even the above thermosetting adhesive sheet may have insufficient heat resistance after wet heat.

Therefore, an object of the present invention is to provide a thermosetting adhesive sheet having a thermosetting adhesive layer that can exhibit high adhesiveness (high adhesive strength) and extremely excellent heat resistance after moist heat after curing.

The phenomenon that the adhesive (adhesive layer) foams or floats off when stored in a high-temperature process after storage under high-temperature and high-humidity conditions is thought to be due to insufficient strength of the adhesive. When trying to improve the strength of the adhesive, there is a problem that the adhesion to the adherend is deteriorated and the adhesive force is reduced.

Therefore, as a result of intensive investigations by the inventor in order to solve the above problem, it is high after curing by having a specific region and a thermosetting adhesive layer having a glass transition point in each of other specific regions. The present invention was completed by finding that a thermosetting adhesive sheet having a thermosetting adhesive layer capable of exhibiting adhesiveness and excellent heat resistance after wet heat was obtained. Also, heat is generated from a thermosetting adhesive composition comprising an acrylic polymer composed of a specific monomer component and an acrylic polymer composed of another specific monomer component as a main component and further containing a thermosetting resin. It was found that by forming a curable adhesive layer, a thermosetting adhesive sheet having a thermosetting adhesive layer capable of exhibiting high adhesiveness and excellent heat resistance after wet heat after curing can be obtained.

That is, the present invention provides a thermosetting adhesive sheet characterized by having thermosetting adhesive layers having glass transition points at −50 ° C. or more and 10 ° C. or less and 20 ° C. or more and 100 ° C. or less, respectively.

The thermosetting adhesive layer is formed from a thermosetting adhesive composition containing the following acrylic polymer (X) and the following acrylic polymer (Y) as main components and containing a thermosetting resin (Z). It is preferable that the thermosetting adhesive layer is made. The acrylic polymer (X) is an acrylic polymer comprising, as an essential monomer component, a (meth) acrylic acid alkyl ester (a1) having a linear or branched alkyl group having 1 to 3 carbon atoms. In the acrylic polymer, the content of the alkyl (meth) acrylate (a1) is 50% by weight or more in the total amount (100% by weight) of monomer components constituting the acrylic polymer. In addition, the acrylic polymer (Y) is an acrylic polymer composed of (meth) acrylic acid alkyl ester (a2) having a linear or branched alkyl group having 4 to 12 carbon atoms as an essential monomer component. It is an acrylic polymer in which the content of the above (meth) acrylic acid alkyl ester (a2) in the total amount (100% by weight) of monomer components constituting the acrylic polymer is 50% by weight or more. .

The content of the acrylic polymer (Y) is preferably 1 to 100 parts by weight with respect to 100 parts by weight of the acrylic polymer (X).

The acrylic polymer (X) is preferably an acrylic polymer composed of the cyano group-containing monomer (b1) and the carboxyl group-containing monomer (c1) as essential monomer components.

The acrylic polymer (Y) is preferably an acrylic polymer composed of a cyano group-containing monomer (b2) and a carboxyl group-containing monomer (c2) as essential monomer components.

The thermosetting resin (Z) is preferably a phenol resin, and more preferably an etherified phenol resin.

The content of the thermosetting resin (Z) is preferably 1 to 40 parts by weight with respect to 100 parts by weight of the acrylic polymer (X).

The thermosetting adhesive sheet of the present invention is preferably a thermosetting adhesive sheet for flexible printed circuit boards.

Also, the present invention provides a flexible printed circuit board having the above thermosetting adhesive sheet.

The present invention also provides a thermosetting thermosetting adhesive sheet obtained by thermosetting the above thermosetting adhesive sheet.

The present invention also provides a flexible printed circuit board having the above-mentioned thermosetting thermosetting adhesive sheet.

The present invention also includes a thermosetting adhesive comprising a thermosetting adhesive composition containing a first acrylic polymer and a second acrylic polymer as main components and containing a thermosetting resin. There is provided a thermosetting adhesive sheet comprising a layer, wherein a monomer component constituting the first acrylic polymer is different from a monomer component constituting the second acrylic polymer.

Moreover, this invention was formed from the thermosetting adhesive composition which contains the following acrylic polymer (X) and the following acrylic polymer (Y) as a main component, and contains a thermosetting resin (Z). There is provided a thermosetting adhesive sheet having a thermosetting adhesive layer. The acrylic polymer (X) is an acrylic polymer comprising, as an essential monomer component, a (meth) acrylic acid alkyl ester (a1) having a linear or branched alkyl group having 1 to 3 carbon atoms. In the acrylic polymer, the content of the alkyl (meth) acrylate (a1) is 50% by weight or more in the total amount (100% by weight) of monomer components constituting the acrylic polymer. In addition, the acrylic polymer (Y) is an acrylic polymer composed of (meth) acrylic acid alkyl ester (a2) having a linear or branched alkyl group having 4 to 12 carbon atoms as an essential monomer component. It is an acrylic polymer in which the content of the above (meth) acrylic acid alkyl ester (a2) in the total amount (100% by weight) of monomer components constituting the acrylic polymer is 50% by weight or more. . The content of the acrylic polymer (Y) is preferably 1 to 100 parts by weight with respect to 100 parts by weight of the acrylic polymer (X). The acrylic polymer (X) is preferably an acrylic polymer composed of the cyano group-containing monomer (b1) and the carboxyl group-containing monomer (c1) as essential monomer components. The acrylic polymer (Y) is preferably an acrylic polymer composed of a cyano group-containing monomer (b2) and a carboxyl group-containing monomer (c2) as essential monomer components. The thermosetting resin (Z) is preferably a phenol resin, and more preferably an etherified phenol resin. The content of the thermosetting resin (Z) is preferably 1 to 40 parts by weight with respect to 100 parts by weight of the acrylic polymer (X). The thermosetting adhesive sheet of the present invention is preferably a thermosetting adhesive sheet for flexible printed circuit boards. Moreover, this invention provides the flexible printed circuit board which has said thermosetting type adhesive sheet. Moreover, this invention provides the thermosetting thermosetting adhesive sheet obtained by thermosetting said thermosetting adhesive sheet. Moreover, this invention provides the flexible printed circuit board which has said thermosetting thermosetting adhesive sheet.

The thermosetting adhesive sheet of the present invention has the above-described structural characteristics, so that after curing, the thermosetting adhesive layer can exhibit high adhesiveness and extremely excellent heat resistance after wet heat.

Hereinafter, embodiments of the present invention will be described in detail.

The present invention relates to a thermosetting adhesive sheet having at least one thermosetting adhesive layer having a glass transition point of −50 ° C. to 10 ° C. and 20 ° C. to 100 ° C., and an acrylic polymer (X ) And an acrylic polymer (Y) as a main component, and at least one thermosetting adhesive layer formed from a thermosetting adhesive composition containing a thermosetting resin (Z). Includes mold adhesive sheet.

In the present specification, the “thermosetting adhesive sheet having at least one thermosetting adhesive layer having a glass transition point at −50 ° C. or more and 10 ° C. or less and 20 ° C. or more and 100 ° C. or less” is referred to as “ Thermosetting adhesive sheet (S1), sometimes referred to as “thermosetting adhesive sheet (S1)”, containing “acrylic polymer (X) and acrylic polymer (Y) as main components and thermosetting resin (Z)” The “thermosetting adhesive sheet having at least one thermosetting adhesive layer formed from the mold adhesive composition” may be referred to as “thermosetting adhesive sheet (S2)”. The “thermosetting adhesive layer having a glass transition point at −50 ° C. to 10 ° C. and 20 ° C. to 100 ° C.” may be referred to as “thermosetting adhesive layer (L1)”. . The thermosetting adhesive composition forming the thermosetting adhesive layer (L1) may be referred to as “thermosetting adhesive composition (M1)”. Furthermore, the above-mentioned “thermosetting adhesive composition containing acrylic polymer (X) and acrylic polymer (Y) as main components and containing thermosetting resin (Z)” is referred to as “thermosetting adhesive”. A thermosetting adhesive that may be referred to as a “composition (M2)” and contains the above-mentioned “acrylic polymer (X) and acrylic polymer (Y) as main components and a thermosetting resin (Z)”. The “thermosetting adhesive layer formed from the composition” (that is, the thermosetting adhesive layer formed from the thermosetting adhesive composition (M2)) is referred to as “thermosetting adhesive layer (L2)”. Sometimes called.

In the present specification, the thermosetting adhesive sheet (S1) and the thermosetting adhesive sheet (S2) may be collectively referred to as “thermosetting adhesive sheet of the present invention”. The adhesive layer (L1) and the thermosetting adhesive layer (L2) may be collectively referred to as “the thermosetting adhesive layer of the present invention”. The “thermosetting adhesive sheet” includes the meaning of “thermosetting adhesive tape”. That is, the thermosetting adhesive sheet of the present invention may be a thermosetting adhesive tape having a tape-like form.

Moreover, in this specification, "it contains acrylic polymer (X) and acrylic polymer (Y) as a main component" means the total non volatile content (100 weight%) of a thermosetting adhesive composition (M2). It means that the total content (total content) of the content of acrylic polymer (X) and the content of acrylic polymer (Y) is 50% by weight or more.

Although the said thermosetting type adhesive bond layer (L1) is not specifically limited, The thermosetting which contains acrylic polymer (X) and acrylic polymer (Y) as a main component, and contains a thermosetting resin (Z). It is preferably a thermosetting adhesive layer (that is, the thermosetting adhesive layer (L2)) formed from a mold adhesive composition. Therefore, the thermosetting adhesive sheet (S1) is preferably a thermosetting adhesive sheet (S1) and a thermosetting adhesive sheet (S2).

[Thermosetting adhesive composition (M1)]
The thermosetting adhesive composition (M1) is not particularly limited, and examples thereof include acrylic polymers, rubber polymers, vinyl alkyl ether polymers, silicone polymers, polyester polymers, polyamide polymers, urethane polymers, It is preferable to contain a polymer such as a fluorine polymer or an epoxy polymer as an essential component. Among these polymers, an acrylic polymer is more preferable. Although the said thermosetting type adhesive composition (M1) is not specifically limited, Furthermore, it is preferable to contain a thermosetting resin. In addition to the polymer and the thermosetting resin, a solvent (solvent and / or dispersion medium) may be contained, and an additive may be contained. Each of the above components (polymer, thermosetting resin, solvent and additive) can be used alone or in combination of two or more.

The thermosetting adhesive composition (M1) preferably contains an acrylic polymer as a main component, and is preferably a thermosetting adhesive composition containing a thermosetting resin, more preferably thermosetting. This is a mold adhesive composition (M2). “Containing acrylic polymer as a main component” means that the content of acrylic polymer in the total nonvolatile content (100 wt%) of the thermosetting adhesive composition (M1) is 50 wt% or more. Means that.

The acrylic polymer is not particularly limited, but is preferably an acrylic polymer configured (or formed) with a (meth) acrylic acid alkyl ester having a linear or branched alkyl group as an essential monomer component. . The (meth) acrylic acid alkyl ester is not particularly limited. For example, a (meth) acrylic acid alkyl ester having 1 to 14 carbon atoms is preferable, and an alkyl (meth) acrylate having 1 to 12 carbon atoms is more preferable. Ester. Especially, the (meth) acrylic acid alkyl ester illustrated as the (meth) acrylic acid alkyl ester (a1) mentioned later and the (meth) acrylic acid alkyl ester exemplified as the acrylic acid alkyl ester (a2) mentioned later are preferable. The said (meth) acrylic-acid alkylester can be used individually or in combination of 2 or more types.

The content (content ratio) of the (meth) acrylic acid alkyl ester in the monomer component constituting the acrylic polymer is not particularly limited, but is based on the total amount (100% by weight) of the monomer component constituting the acrylic polymer. Thus, it is preferably 50% by weight or more, more preferably 50 to 75% by weight, still more preferably 55 to 75% by weight, still more preferably 60 to 72% by weight.

Although it does not specifically limit as a monomer component which comprises the said acrylic polymer, Furthermore, it is preferable to contain a cyano group containing monomer and a carboxyl group containing monomer, More preferably, a cyano group containing monomer and a carboxyl group containing monomer are included. More preferably, it contains a monomer component exemplified as a cyano group-containing monomer (b1) described later and a monomer component exemplified as a carboxyl group-containing monomer (c1) described later. The said monomer component can be used individually or in combination of 2 or more types. It is preferable to use a cyano group-containing monomer because the strength (bulk strength) of the thermosetting adhesive layer (L1) can be improved and the heat resistance after wet heat can be improved. Moreover, since it can prevent that a thermosetting type adhesive bond layer (L1) becomes weak, it is preferable. It is preferable to use the carboxyl group-containing monomer because the heat resistance after wet heat and the adhesive strength of the thermosetting adhesive sheet (S1) can be improved.

The content of the cyano group-containing monomer is not particularly limited, but is preferably 20 to 49.5% by weight, more preferably 24 to 40%, based on the total amount of monomer components (100% by weight) constituting the acrylic polymer. % By weight, more preferably 26 to 35% by weight. It is preferable that the content is 20% by weight or more because the heat resistance after wet heat of the thermosetting adhesive sheet (S1) is further improved. On the other hand, when the content exceeds 49.5% by weight, the flexibility of the thermosetting adhesive layer (L1) may be lowered.

The content of the carboxyl group-containing monomer is not particularly limited, but is preferably 0.5 to 10% by weight, more preferably 1 to 8%, based on the total amount of monomer components (100% by weight) constituting the acrylic polymer. % By weight, more preferably 2 to 6% by weight. It is preferable that the content is 0.5% by weight or more because the heat resistance after wet heat and the adhesive force of the thermosetting adhesive sheet (S1) are improved. On the other hand, if the content exceeds 10% by weight, the flexibility of the thermosetting adhesive layer (L1) may be lowered.

The monomer component constituting the acrylic polymer may further contain another copolymerizable monomer. The other copolymerizable monomer is not particularly limited. For example, a (meth) acrylic acid alkyl ester having a linear or branched alkyl group having 15 to 20 carbon atoms, non-aromaticity described later. Ring-containing (meth) acrylic acid alkyl ester, aromatic ring-containing (meth) acrylic acid alkyl ester described later, epoxy group-containing acrylic monomer described later, vinyl ester monomer described later, styrene monomer described later, hydroxyl described later Group-containing monomers, (meth) acrylic acid alkoxyalkyl monomers described later, (meth) acrylic acid aminoalkyl monomers described below, (N-substituted) amide monomers described below, olefin monomers described below, vinyl ether monomers described below And polyfunctional monomers described later.

The acrylic polymer can be prepared by a known or conventional polymerization method (for example, a solution polymerization method, an emulsion polymerization method, a suspension polymerization method, a bulk polymerization method, or a polymerization method by ultraviolet irradiation).

In addition, the polymerization initiator, the emulsifier, the chain transfer agent and the like that are used as necessary in the polymerization of the acrylic polymer are not particularly limited, and can be appropriately selected from known or commonly used ones. More specifically, the polymerization initiators (azo polymerization initiators and peroxides) exemplified as polymerization initiators, emulsifiers, and chain transfer agents used as necessary in the polymerization of the acrylic polymer (X) described later. Oxide-based polymerization initiators), emulsifiers (such as anionic emulsifiers and nonionic emulsifiers), and chain transfer agents. The said polymerization initiator, an emulsifier, and a chain transfer agent can be used individually or in combination of 2 types or more, respectively. The usage-amount of the said polymerization initiator is not specifically limited, It can select suitably from the range of a normal usage-amount.

In solution polymerization, various common solvents can be used. The solvent is not particularly limited. For example, esters such as ethyl acetate and n-butyl acetate; aromatic hydrocarbons such as toluene and benzene; aliphatic hydrocarbons such as n-hexane and n-heptane; Examples include alicyclic hydrocarbons such as cyclohexane and methylcyclohexane; organic solvents such as ketones such as methyl ethyl ketone and methyl isobutyl ketone. The said solvent can be used individually or in combination of 2 or more types.

Although the weight average molecular weight (Mw) of the acrylic polymer is not particularly limited, a viewpoint of improving productivity by improving the coating property of the thermosetting adhesive composition (M1), a thermosetting adhesive layer ( From the viewpoint of improving the strength of L1) and improving heat resistance after wet heat, 500,000 to 4,000,000 is preferable, more preferably 800,000 to 3,500,000, still more preferably 1,000,000 to 3,200,000. The weight average molecular weight of the acrylic polymer can be controlled by the monomer concentration, the monomer dropping rate, etc., in addition to the type and amount of polymerization initiator and chain transfer agent, the temperature and time during polymerization.

The above weight average molecular weight can be measured by gel permeation chromatograph (GPC). More specifically, for example, it can be determined by measuring by <GPC measurement method> described later, similarly to the weight average molecular weight of the acrylic polymer (X) described later.

The thermosetting resin is used for imparting thermosetting properties. It does not specifically limit as said thermosetting resin, The well-known and usual thermosetting resin which hardens | cures by heating and exhibits an adhesive effect can be used. Especially, the thermosetting resin illustrated as the thermosetting resin (Z) mentioned later is preferable, More preferably, it is etherified phenol resin. The said thermosetting resin can be used individually or in combination of 2 or more types.

The content of the acrylic polymer in the thermosetting adhesive composition (M1) is not particularly limited, but from the viewpoint of achieving both heat resistance after wet heat and adhesive strength, the thermosetting adhesive composition (M1). The total non-volatile content (100% by weight) is preferably 50% by weight or more, more preferably 70 to 99% by weight, still more preferably 80 to 95% by weight.

In the thermosetting adhesive composition (M1), the content (content ratio, blending ratio) of the thermosetting resin is not particularly limited, but is 1 to 40 with respect to 100 parts by weight of the acrylic polymer. Part by weight is preferred, more preferably 5 to 20 parts by weight, still more preferably 10 to 15 parts by weight. By setting the content of the thermosetting resin to 1 part by weight or more, it is preferable because the thermosetting of the thermosetting adhesive layer (L1) is improved. Moreover, it is preferable to make it 40 parts by weight or less because the adhesive does not protrude during high-temperature pressing.

The thermosetting adhesive composition (M1) preferably contains a solvent. Examples of the solvent include, but are not limited to, esters such as ethyl acetate and n-butyl acetate; alcohols such as methanol, ethanol, butanol, propanol, and isopropanol; aromatic hydrocarbons such as toluene and benzene; n Organic solvents such as aliphatic hydrocarbons such as hexane and n-heptane; alicyclic hydrocarbons such as cyclohexane and methylcyclohexane; ketones such as methyl ethyl ketone and methyl isobutyl ketone. The said solvent can be used individually or in combination of 2 or more types. Note that the solvent includes the meaning of a dispersion medium.

In the thermosetting adhesive composition (M1), in addition to the acrylic polymer and the thermosetting resin, an anti-aging agent and a thermosetting adhesive composition (M2) described later are used as necessary. Known additives such as fillers (fillers), colorants (pigments and dyes), UV absorbers, antioxidants, crosslinking agents, tackifiers, plasticizers, softeners, surfactants and antistatic agents However, it may be contained within a range not impairing the characteristics of the present invention. The said additive can be used individually or in combination of 2 or more types.

[Thermosetting adhesive composition (M2)]
The thermosetting adhesive composition (M2) contains an acrylic polymer (X), an acrylic polymer (Y), and a thermosetting resin (Z) as essential components. The thermosetting adhesive composition (M2) contains a solvent (solvent and / or dispersion medium) in addition to the acrylic polymer (X), the acrylic polymer (Y), and the thermosetting resin (Z). And may contain additives. Each of the above components (acrylic polymer (X), acrylic polymer (Y), thermosetting resin (Z), solvent or additive) can be used alone or in combination of two or more.

(Acrylic polymer (X))
The acrylic polymer (X) is composed (or formed) with the (meth) acrylic acid alkyl ester (a1) having a linear or branched alkyl group having 1 to 3 carbon atoms as an essential monomer component. Acrylic polymer. In the present specification, the “(meth) acrylic acid alkyl ester (a1) having a linear or branched alkyl group having 1 to 3 carbon atoms” is referred to as “(meth) acrylic acid C _{1. -3} alkyl ester (a1) "or simply" (meth) acrylic acid alkyl ester (a1) ". “(Meth) acryl” means “acryl” and / or “methacryl” (one or both of “acryl” and “methacryl”), and the same applies to the following.

The acrylic polymer (X) is an acrylic polymer composed of (meth) acrylic acid C _1-3 alkyl ester (a1), cyano group-containing monomer (b1) and carboxyl group-containing monomer (c1) as essential monomer components. A polymer is preferred. Among them, the content of (meth) acrylic acid C _1-3 alkyl ester (a1) in the total amount (100% by weight) of monomer components constituting the acrylic polymer (X) is 50 to 75% by weight, and contains a cyano group The content of the monomer (b1) is preferably 20 to 49.5% by weight, and the content of the carboxyl group-containing monomer (c1) is preferably 0.5 to 10% by weight. The monomer component constituting the acrylic polymer (X) is a monomer other than the (meth) acrylic acid C _1-3 alkyl ester (a1), the cyano group-containing monomer (b1), and the carboxyl group-containing monomer (c1). Components (other monomer components) may be used. The said acrylic polymer (X) can be used individually or in combination of 2 or more types.

The acrylic polymer (X) is preferably an acrylic polymer (acrylic elastomer) that exhibits rubber elasticity (elastomeric properties).

The (meth) acrylic acid C _1-3 alkyl ester (a1) is not particularly limited, and examples thereof include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, and (meth) acrylic. And isopropyl acid. Of these, ethyl acrylate is preferred. The (meth) acrylic acid C _1-3 alkyl ester (a1) can be used alone or in combination of two or more.

The content (content ratio) of the (meth) acrylic acid C _1-3 alkyl ester (a1) in the monomer component constituting the acrylic polymer (X) is the total amount of the monomer component constituting the acrylic polymer (X) ( 100% by weight) to 50% by weight or more, preferably 50 to 75% by weight, more preferably 55 to 75% by weight, and still more preferably 60 to 72% by weight. When the content is 50% by weight or more, the acrylic polymer (X) becomes a relatively hard polymer, improves the strength (bulk strength) of the thermosetting adhesive layer (L2), and improves heat resistance after wet heat. Can be improved.

The cyano group-containing monomer (b1) is a monomer having a cyano group and is not particularly limited, and examples thereof include acrylonitrile and methacrylonitrile. Of these, acrylonitrile is preferred. The said cyano group containing monomer (b1) can be used individually or in combination of 2 or more types. Use of the cyano group-containing monomer (b1) is preferable because the strength (bulk strength) of the thermosetting adhesive layer (L2) can be improved and the heat resistance after wet heat can be improved. Moreover, since it can prevent that a thermosetting adhesive bond layer (L2) becomes weak, it is preferable.

The content of the cyano group-containing monomer (b1) in the monomer component constituting the acrylic polymer (X) is 20 to 49 with respect to the total amount (100% by weight) of the monomer component constituting the acrylic polymer (X). 0.5 wt% is preferable, more preferably 24 to 40 wt%, and still more preferably 26 to 35 wt%. It is preferable that the content is 20% by weight or more because the heat resistance after wet heat of the thermosetting adhesive sheet (S2) is further improved. On the other hand, if the content exceeds 49.5% by weight, the flexibility of the thermosetting adhesive layer may be lowered.

The carboxyl group-containing monomer (c1) is a monomer having a carboxyl group and is not particularly limited, and examples thereof include acrylic acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid, and crotonic acid. In addition, acid anhydrides of these carboxyl group-containing monomers (for example, acid anhydride group-containing monomers such as maleic anhydride and itaconic anhydride) are also included in the carboxyl group-containing monomers. Among these, acrylic acid, methacrylic acid, and itaconic acid are preferable, and acrylic acid is particularly preferable. The said carboxyl group-containing monomer (c1) can be used individually or in combination of 2 or more types. It is preferable to use the carboxyl group-containing monomer (c1) because the heat resistance and adhesive strength after wet heat of the thermosetting adhesive sheet (S2) can be improved.

The content of the carboxyl group-containing monomer (c1) in the monomer component constituting the acrylic polymer (X) is 0.5% relative to the total amount (100% by weight) of the monomer component constituting the acrylic polymer (X). It is preferably ˜10% by weight, more preferably 1 to 8% by weight, still more preferably 2 to 6% by weight. When the content is 0.5% by weight or more, the heat resistance after wet heat and the adhesive force of the thermosetting adhesive sheet (S2) are improved, which is preferable. On the other hand, if the content exceeds 10% by weight, the flexibility of the thermosetting adhesive layer may be lowered.

As the monomer component constituting the acrylic polymer (X), in addition to the (meth) acrylic acid C _1-3 alkyl ester (a1), the cyano group-containing monomer (b1) and the carboxyl group-containing monomer (c1), other The monomer component (copolymerizable monomer) may be used. The said other monomer component (copolymerizable monomer) can be used individually or in combination of 2 or more types. Examples of the other monomer component (copolymerizable monomer) include n-butyl (meth) acrylate, isobutyl (meth) acrylate, s-butyl (meth) acrylate, t-butyl (meth) acrylate, Pentyl (meth) acrylate, isopentyl (meth) acrylate, hexyl (meth) acrylate, heptyl (meth) acrylate, octyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, isooctyl (meth) acrylate , Nonyl (meth) acrylate, isononyl (meth) acrylate, decyl (meth) acrylate, isodecyl (meth) acrylate, undecyl (meth) acrylate, dodecyl (meth) acrylate, tridecyl (meth) acrylate, Tetradecyl (meth) acrylate, pentadecyl (meth) acrylate, (meth) a Linear or branched alkyl groups having 4 to 20 carbon atoms, such as hexadecyl silylate, heptadecyl (meth) acrylate, octadecyl (meth) acrylate, nonadecyl (meth) acrylate, eicosyl (meth) acrylate (Meth) acrylic acid alkyl ester ((meth) acrylic acid C _4-20 alkyl ester); (meth) acrylic acid cycloalkyl ester [(meth) acrylic acid cyclohexyl etc.] and (meth) acrylic acid isobornyl etc. Aromatic ring-containing (meth) acrylic acid ester; (meth) acrylic acid aryl ester [(meth) acrylic acid phenyl etc.], (meth) acrylic acid aryloxyalkyl ester [(meth) acrylic acid phenoxyethyl etc.], ( (Meth) acrylic acid arylalkyl ester [(meth) acrylic Aromatic ring-containing (meth) acrylic acid esters such as acid benzyl esters]; Epoxy group-containing acrylic monomers such as glycidyl (meth) acrylate and methyl glycidyl (meth) acrylate; vinyl acetate, vinyl propionate, etc. Vinyl ester monomers; styrene monomers such as styrene and α-methylstyrene; hydroxyl group-containing monomers such as hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, and hydroxybutyl (meth) acrylate; (meth) (Meth) acrylic acid alkoxyalkyl monomers such as methoxyethyl acrylate and ethoxyethyl (meth) acrylate; aminoethyl (meth) acrylate, N, N-dimethylaminoethyl (meth) acrylate, (meth) acrylic acid such as t-butylaminoethyl (Meth) acrylic aminoalkyl monomers; (N-substituted) amides such as (meth) acrylic acid amide, N, N-dimethyl (meth) acrylamide, N-butyl (meth) acrylamide, N-hydroxy (meth) acrylamide, etc. Monomers; Olefin monomers such as ethylene, propylene, isoprene and butadiene; Vinyl ether monomers such as methyl vinyl ether.

The other monomer components (copolymerizable monomers) include hexanediol di (meth) acrylate, butanediol di (meth) acrylate, (poly) ethylene glycol di (meth) acrylate, (poly) propylene glycol di ( (Meth) acrylate, neopentyl glycol di (meth) acrylate, pentaerythritol di (meth) acrylate, glycerin di (meth) acrylate, trimethylolpropane tri (meth) acrylate, pentaerythritol tri (meth) acrylate, dipentaerythritol hexa ( Polyfunctional monomers such as (meth) acrylate and divinylbenzene can also be used.

In other words, the acrylic polymer (X) comprises a structural unit derived from the (meth) acrylic acid C _1-3 alkyl ester (a1), a structural unit derived from the cyano group-containing monomer (b1), and a carboxyl group-containing monomer ( It is preferable that it is an acrylic polymer containing at least the structural unit derived from c1). Each structural unit may be one kind or two or more kinds. The content of the structural unit derived from the (meth) acrylic acid C _1-3 alkyl ester (a1) in the acrylic polymer (X) (100% by weight) is preferably 50% by weight or more, more preferably 50 to 50%. It is 75% by weight, more preferably 55 to 75% by weight, and most preferably 60 to 72% by weight. The content of the structural unit derived from the cyano group-containing monomer (b1) is preferably 20 to 49.5% by weight, more preferably 24 to 40% by weight, and still more preferably 26 to 35% by weight. The content of the structural unit derived from the carboxyl group-containing monomer (c1) is preferably 0.5 to 10% by weight, more preferably 1 to 8% by weight, still more preferably 2 to 6% by weight.

The acrylic polymer (X) can be prepared by a known or conventional polymerization method (for example, a solution polymerization method, an emulsion polymerization method, a suspension polymerization method, a bulk polymerization method, a polymerization method by ultraviolet irradiation, etc.).

In addition, the polymerization initiator, the emulsifier, the chain transfer agent and the like that are used as necessary in the polymerization of the acrylic polymer (X) are not particularly limited, and can be appropriately selected from known or commonly used ones. . More specifically, examples of the polymerization initiator include 2,2′-azobisisobutyronitrile, 2,2′-azobis (4-methoxy-2,4-dimethylvaleronitrile), 2,2 '-Azobis (2,4-dimethylvaleronitrile), 2,2'-azobis (2-methylbutyronitrile), 1,1'-azobis (cyclohexane-1-carbonitrile), 2,2'-azobis ( 2,4,4-trimethylpentane), dimethyl-2,2'-azobis (2-methylpropionate), 2,2'-azobis {2- [1- (2-hydroxyethyl) -2-imidazoline- Azo polymerization initiators such as 2-yl] propane} dihydrochloride; benzoyl peroxide, t-butyl hydroperoxide, di-t-butyl peroxide, t-butyl peroxide Peroxides such as xylbenzoate, dicumyl peroxide, 1,1-bis (t-butylperoxy) -3,3,5-trimethylcyclohexane, 1,1-bis (t-butylperoxy) cyclododecane A polymerization initiator etc. are mentioned. The said polymerization initiator can be used individually or in combination of 2 or more types. The usage-amount of the said polymerization initiator is not specifically limited, It can select suitably from the range of a normal usage-amount.

Examples of the chain transfer agent include 1-dodecanethiol, tert-lauryl mercaptan, sec-lauryl mercaptan, 2-mercaptoethanol, glycidyl mercaptan, mercaptoacetic acid, 2-ethylhexyl thioglycolate, and 2,3-dimercapto-1- Examples include propanol and α-methylstyrene dimer. Examples of the emulsifier include anionic emulsifiers such as sodium lauryl sulfate, ammonium lauryl sulfate, sodium dodecylbenzenesulfonate, sodium polyoxyethylene alkyl ether sulfate, ammonium polyoxyethylene alkyl phenyl ether sulfate, sodium polyoxyethylene alkyl phenyl ether sulfate; polyoxy Nonionic emulsifiers such as ethylene alkyl ether and polyoxyethylene alkyl phenyl ether are listed. The chain transfer agent and the emulsifier can be used alone or in combination of two or more.

In solution polymerization, various common solvents can be used. Examples of the solvent include esters such as ethyl acetate and n-butyl acetate; aromatic hydrocarbons such as toluene and benzene; aliphatic hydrocarbons such as n-hexane and n-heptane; cyclohexane and methylcyclohexane Organic solvents such as ketones such as methyl ethyl ketone and methyl isobutyl ketone. The said solvent can be used individually or in combination of 2 or more types.

The weight average molecular weight (Mw) of the acrylic polymer (X) is not particularly limited, but the viewpoint of improving the productivity of the thermosetting adhesive composition (M2) and improving the productivity, and thermosetting adhesion. From the viewpoint of improving the strength of the agent layer (L2) and improving the heat resistance after wet heat, it is preferably 500,000 to 4,000,000, more preferably 800,000 to 3,500,000, still more preferably 1,000,000 to 3,200,000. The weight average molecular weight of the acrylic polymer (X) can be controlled by the monomer concentration, the monomer dropping rate, etc., in addition to the type and amount of polymerization initiator and chain transfer agent, the temperature and time during polymerization.

The weight average molecular weight can be measured by gel permeation chromatograph (GPC). More specifically, it can be determined by, for example, the following <GPC measurement method>.
<GPC measurement method>
(Sample preparation)
The acrylic polymer to be measured is dissolved in the eluent to prepare a 0.1% THF solution of the acrylic polymer, left for 1 day, and then filtered through a 0.45 μm membrane filter. As a sample, GPC measurement is performed under the following measurement conditions.
(Measurement condition)
GPC device: HLC-8320GPC (manufactured by Tosoh Corporation)
Column: TSKgel GMH-H (S) (manufactured by Tosoh Corporation)
Column size: 7.8 mm I.D. D. × 300mm
Column temperature: 40 ° C
Eluent: THF (tetrahydrofuran)
Flow rate: 0.5 ml / min
Inlet pressure: 4.6 MPa
Injection volume: 100 μl
Detector: Differential refractometer Standard sample: Polystyrene Data processing device: GPC-8020 (manufactured by Tosoh Corporation)

(Acrylic polymer (Y))
The acrylic polymer (Y) is composed (or formed) of (meth) acrylic acid alkyl ester (a2) having a linear or branched alkyl group having 4 to 12 carbon atoms as an essential monomer component. Acrylic polymer. In the present specification, the above “(meth) acrylic acid alkyl ester (a2) having a linear or branched alkyl group having 4 to 12 carbon atoms” is referred to as “(meth) acrylic acid C _{4. -12} alkyl ester (a2) "or simply" (meth) acrylic acid alkyl ester (a2) ".

The acrylic polymer (Y) is an acrylic polymer comprising (meth) acrylic acid C _4-12 alkyl ester (a2), a cyano group-containing monomer (b2) and a carboxyl group-containing monomer (c2) as essential monomer components. A polymer is preferred. Among them, the content of (meth) acrylic acid C _4-12 alkyl ester (a2) in the total amount (100% by weight) of the monomer component constituting the acrylic polymer (Y) is 50 to 75% by weight, and the cyano group is contained. The content of the monomer (b2) is preferably 20 to 49.5% by weight, and the content of the carboxyl group-containing monomer (c2) is preferably 0.5 to 10% by weight. The monomer component constituting the acrylic polymer (Y) includes monomers other than the (meth) acrylic acid C _4-12 alkyl ester (a2), the cyano group-containing monomer (b2), and the carboxyl group-containing monomer (c2). Components (other monomer components) may be used. The said acrylic polymer (Y) can be used individually or in combination of 2 or more types.

The acrylic polymer (Y) is preferably an acrylic polymer (acrylic elastomer) that exhibits rubber elasticity (elastomeric properties).

The (meth) acrylic acid C _4-12 alkyl ester (a2) is not particularly limited. For example, n-butyl (meth) acrylate, isobutyl (meth) acrylate, s-butyl (meth) acrylate, T-butyl (meth) acrylate, pentyl (meth) acrylate, isopentyl (meth) acrylate, hexyl (meth) acrylate, heptyl (meth) acrylate, octyl (meth) acrylate, (meth) acrylic acid 2 -Ethylhexyl, isooctyl (meth) acrylate, nonyl (meth) acrylate, isononyl (meth) acrylate, decyl (meth) acrylate, isodecyl (meth) acrylate, undecyl (meth) acrylate, (meth) acrylic acid Examples include dodecyl. Among them, (meth) acrylic acid alkyl ester having a linear or branched alkyl group having 4 to 8 carbon atoms ((meth) acrylic acid C _4-8 alkyl ester) is preferable, and n-butyl acrylate is preferable. Particularly preferred. The (meth) acrylic acid C _4-12 alkyl ester (a2) can be used alone or in combination of two or more.

The content of the (meth) acrylic acid C _4-12 alkyl ester (a2) in the monomer component constituting the acrylic polymer (Y) is the total amount (100% by weight) of the monomer component constituting the acrylic polymer (Y). Is 50 to 75% by weight, preferably 50 to 75% by weight, more preferably 55 to 75% by weight, and still more preferably 60 to 72% by weight. When the content is 50% by weight or more, the acrylic polymer (Y) becomes a relatively soft polymer, the thermosetting adhesive layer (L2) is prevented from becoming too hard, and the adhesive force is improved. Can do.

The cyano group-containing monomer (b2) is a monomer having a cyano group and is not particularly limited, and examples thereof include acrylonitrile and methacrylonitrile. Of these, acrylonitrile is preferred. The said cyano group containing monomer (b2) can be used individually or in combination of 2 or more types. Use of the cyano group-containing monomer (b2) is preferable because the strength (bulk strength) of the thermosetting adhesive layer (L2) can be improved and the heat resistance after wet heat can be improved. Moreover, since it can prevent that a thermosetting adhesive bond layer (L2) becomes weak, it is preferable.

The content of the cyano group-containing monomer (b2) in the monomer component constituting the acrylic polymer (Y) is 20 to 49 with respect to the total amount (100% by weight) of the monomer component constituting the acrylic polymer (Y). 0.5 wt% is preferable, more preferably 24 to 40 wt%, and still more preferably 26 to 35 wt%. The content of 20% by weight or more is preferable because the heat resistance after wet heat of the thermosetting adhesive sheet (S2) is improved. On the other hand, if the content exceeds 49.5% by weight, the flexibility of the thermosetting adhesive layer may be lowered.

The carboxyl group-containing monomer (c2) is a monomer having a carboxyl group and is not particularly limited, and examples thereof include acrylic acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid, and crotonic acid. In addition, acid anhydrides of these carboxyl group-containing monomers (for example, acid anhydride group-containing monomers such as maleic anhydride and itaconic anhydride) are also included in the carboxyl group-containing monomers. Among these, acrylic acid, methacrylic acid, and itaconic acid are preferable, and acrylic acid is particularly preferable. The said carboxyl group-containing monomer (c2) can be used individually or in combination of 2 or more types. It is preferable to use the carboxyl group-containing monomer (c2) because the heat resistance and adhesive strength after wet heat of the thermosetting adhesive sheet (S2) can be improved.

The content of the carboxyl group-containing monomer (c2) in the monomer component constituting the acrylic polymer (Y) is 0.5% relative to the total amount (100% by weight) of the monomer component constituting the acrylic polymer (Y). It is preferably ˜10% by weight, more preferably 1 to 8% by weight, still more preferably 2 to 6% by weight. When the content is 0.5% by weight or more, the heat resistance after wet heat and the adhesive force of the thermosetting adhesive sheet (S2) are improved, which is preferable. On the other hand, if the content exceeds 10% by weight, the flexibility of the thermosetting adhesive layer may be lowered.

As the monomer component constituting the acrylic polymer (Y), in addition to the (meth) acrylic acid C _4-12 alkyl ester (a2), the cyano group-containing monomer (b2) and the carboxyl group-containing monomer (c2), other The monomer component (copolymerizable monomer) may be used. The said other monomer component (copolymerizable monomer) can be used individually or in combination of 2 or more types. Examples of the other monomer component (copolymerizable monomer) include, for example, 1 to 1 carbon atoms such as methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, isopropyl (meth) acrylate, and the like. (Meth) acrylic acid alkyl ester ((meth) acrylic acid C _1-3 alkyl ester) having a linear or branched alkyl group which is ₃ ; (meth) acrylic acid tridecyl, (meth) acrylic acid tetradecyl, ( Carbon number of 13 to 20 such as pentadecyl (meth) acrylate, hexadecyl (meth) acrylate, heptadecyl (meth) acrylate, octadecyl (meth) acrylate, nonadecyl (meth) acrylate, eicosyl (meth) acrylate, etc. (Meth) acrylic acid alkyl ester ((meth) acrylate) having a linear or branched alkyl group Rylic acid C _13-20 alkyl ester) and the like.

Furthermore, as said other monomer component (copolymerizable monomer), non-aromatic ring containing (exemplified as another monomer component (copolymerizable monomer) in the monomer component which comprises acrylic polymer (X) ( (Meth) acrylic acid ester; aromatic ring-containing (meth) acrylic acid ester; epoxy group-containing acrylic monomer; vinyl ester monomer; styrene monomer; hydroxyl group-containing monomer; (meth) acrylic acid alkoxyalkyl monomer; (Meth) aminoalkyl acrylate monomers; (N-substituted) amide monomers; olefin monomers; vinyl ether monomers;

In other words, the acrylic polymer (Y) includes a structural unit derived from the (meth) acrylic acid C _4-12 alkyl ester (a2), a structural unit derived from the cyano group-containing monomer (b2), and a carboxyl group-containing monomer ( An acrylic polymer containing at least the structural unit derived from c2) is preferred. Each structural unit may be one kind or two or more kinds. The content of the structural unit derived from the (meth) acrylic acid C _4-12 alkyl ester (a2) in the acrylic polymer (Y) (100% by weight) is preferably 50% by weight or more, more preferably 50 to 50%. It is 75% by weight, more preferably 55 to 75% by weight, and most preferably 60 to 72% by weight. The content of the structural unit derived from the cyano group-containing monomer (b2) is preferably 20 to 49.5% by weight, more preferably 24 to 40% by weight, and still more preferably 26 to 35% by weight. The content of the structural unit derived from the carboxyl group-containing monomer (c2) is preferably 0.5 to 10% by weight, more preferably 1 to 8% by weight, still more preferably 2 to 6% by weight.

The acrylic polymer (Y) can be prepared by a known or conventional polymerization method (for example, a solution polymerization method, an emulsion polymerization method, a suspension polymerization method, a bulk polymerization method, a polymerization method by ultraviolet irradiation, or the like).

In addition, the polymerization initiator, the emulsifier, the chain transfer agent and the like that are used as necessary in the polymerization of the acrylic polymer (Y) are not particularly limited, and can be appropriately selected from known or commonly used ones. . More specifically, polymerization initiators (azo polymerization initiators and peroxides) exemplified as a polymerization initiator, an emulsifier, and a chain transfer agent that are used as necessary when polymerizing the acrylic polymer (X). And polymerization initiators), emulsifiers (such as anionic emulsifiers and nonionic emulsifiers), and chain transfer agents. The said polymerization initiator, an emulsifier, and a chain transfer agent can be used individually or in combination of 2 types or more, respectively. The usage-amount of the said polymerization initiator is not specifically limited, It can select suitably from the range of a normal usage-amount.

In solution polymerization, various common solvents can be used. Examples of the solvent include esters such as ethyl acetate and n-butyl acetate; aromatic hydrocarbons such as toluene and benzene; aliphatic hydrocarbons such as n-hexane and n-heptane; cyclohexane and methylcyclohexane Organic solvents such as ketones such as methyl ethyl ketone and methyl isobutyl ketone. The said solvent can be used individually or in combination of 2 or more types.

The weight average molecular weight (Mw) of the acrylic polymer (Y) is not particularly limited, but the viewpoint of improving the productivity of the thermosetting adhesive composition (M2) and improving the productivity, and thermosetting adhesion. From the viewpoint of improving the strength of the agent layer (L2) and improving the heat resistance after wet heat, 500,000 to 2,000,000 is preferable, more preferably 600,000 to 1,800,000, still more preferably 600,000 to 1,500,000, and still more preferably 80 10,000 to 1.2 million. The weight average molecular weight of the acrylic polymer (Y) can be controlled by the monomer concentration, the monomer dropping rate, etc., in addition to the type and amount of polymerization initiator and chain transfer agent, the temperature and time during polymerization.

The above weight average molecular weight can be measured by gel permeation chromatograph (GPC). More specifically, for example, as with the weight average molecular weight of the acrylic polymer (X), it can be determined by measuring by the above-described <GPC measurement method>.

(Thermosetting resin (Z))
The thermosetting resin (Z) is not particularly limited, and a known and commonly used thermosetting resin that is cured by heating and exhibits an adhesive action can be used. The thermosetting resin (Z) is used for imparting thermosetting properties. Examples of the thermosetting resin (Z) include phenol resin, amino resin, unsaturated polyester resin, epoxy resin, polyurethane resin, silicone resin, thermosetting polyimide resin, and the like. Especially, the said thermosetting resin (Z) has a preferable phenol resin and / or an epoxy resin, More preferably, it is a phenol resin. The said thermosetting resin (Z) can be used individually or in combination of 2 or more types.

The above-mentioned phenol resin is not particularly limited, and known and commonly used phenol resins can be used. For example, a resol type phenol resin, a novolac type phenol resin, various modified phenol resins (for example, alkyl modified phenol resin etc.), etc. are mentioned. The said phenol resin can be used individually or in combination of 2 or more types. As the phenol resin, an etherified phenol resin is particularly preferable. Since the etherified phenol resin is excellent in reactivity at the time of heat curing, when the etherified phenol resin is used as the thermosetting resin (Z), the effect of improving the adhesive strength and the heat resistance after wet heat is particularly excellent.

The etherified phenol resin is a phenol resin in which a part of the methylol group (methylol group in the phenol resin) of the phenol resin is etherified. That is, it is a phenol resin having at least a non-etherified methylol group and an etherified methylol group.

Furthermore, the etherified phenol resin is preferably an alkyl etherified phenol resin, which is a phenol resin in which a part of the methylol group of the phenol resin is etherified with an alkyl group. Examples of the alkyl group include methyl, ethyl, propyl, isopropyl, n-butyl, isobutyl, s-butyl, t-butyl, pentyl, isopentyl, hexyl, heptyl, Octyl group, 2-ethylhexyl group, isooctyl group, nonyl group, isononyl group, decyl group, isodecyl group, undecyl group, dodecyl group, tridecyl group, tetradecyl group, pentadecyl group, hexadecyl group, heptadecyl group, octadecyl group, nonadecyl group, Examples thereof include an alkyl group having 1 to 20 carbon atoms such as an eicosyl group. Of these, a methyl group, an ethyl group, and an n-butyl group are preferable, and an n-butyl group is more preferable.

In the etherified phenolic resin, the phenolic resin serving as a skeleton is not particularly limited. Examples of the etherified phenol resin include an etherified novolac type phenol resin, an etherified resol type phenol resin, and an etherified cresol resin. Among these, etherified cresol resins are preferable, and butyl etherified cresol resins (cresol resins in which a part of the methylol group is butyl etherified) are more preferable. The etherified phenol resins can be used alone or in combination of two or more.

The ratio of the etherified methylol group in the etherified phenol resin is, for example, the ratio of the etherified methylol group to the total (100 mol%) of the etherified methylol group and the non-etherified methylol group. The ratio is preferably 50 mol% or more (50 mol% or more and less than 100 mol%), more preferably 70 mol% or more. If the ratio of the etherified methylol group is less than 50 mol%, the reaction of the etherified phenol resin at room temperature may be accelerated, or the reactivity during heat curing may be reduced.

As the etherified phenol resin, a commercially available etherified phenol resin can also be used. For example, the trade name “Sumilite Resin PR-55317” (Sumitomo Bakelite Co., Ltd., butyl etherified cresol resin, etherified And a product name “CKS-3898” (Butyl etherified cresol resin, manufactured by Showa Denko KK) and the like can be used.

(Contents of components in thermosetting adhesive composition (M2))
The total amount (total content) of the acrylic polymer (X) content and the acrylic polymer (Y) content in the thermosetting adhesive composition (M2) is the heat resistance and adhesive strength after wet heat. From the viewpoint of coexistence of the above, it is 50% by weight or more, preferably 70 to 99% by weight, more preferably 80 to 95% with respect to the total nonvolatile content (100% by weight) of the thermosetting adhesive composition (M2) % By weight, more preferably 85 to 95% by weight.

In the thermosetting adhesive composition (M2), the content (content ratio, blending ratio) of the acrylic polymer (Y) is 1 to 100 parts by weight with respect to 100 parts by weight of the acrylic polymer (X). It is preferably 2 to 45 parts by weight, more preferably 4 to 25 parts by weight, and most preferably 5 to 20 parts by weight. By setting the content of the acrylic polymer (Y) to 1 part by weight or more, the adhesive force of the thermosetting adhesive sheet (S2) is improved and the heat resistance after wet heat is also improved, which is preferable. Moreover, it is preferable to make it 100 parts by weight or less because the strength of the thermosetting adhesive layer (L2) is improved and the heat resistance after wet heat of the thermosetting adhesive sheet (S2) is improved.

In the thermosetting adhesive composition (M2), the content (content ratio, blending ratio) of the thermosetting resin (Z) is 1 to 40 weights with respect to 100 weight parts of the acrylic polymer (X). Parts, preferably 5 to 20 parts by weight, more preferably 10 to 15 parts by weight. It is preferable to set the content of the thermosetting resin (Z) to 1 part by weight or more because the thermosetting property of the thermosetting adhesive layer (L2) is improved. Moreover, it is preferable to make it 40 parts by weight or less because the adhesive does not protrude during high-temperature pressing. In particular, it is preferable that the content of the etherified phenol resin with respect to 100 parts by weight of the acrylic polymer (X) satisfies the above range.

(Solvent, additive)
The thermosetting adhesive composition (M2) preferably contains a solvent. Examples of the solvent include esters such as ethyl acetate and n-butyl acetate; alcohols such as methanol, ethanol, butanol, propanol and isopropanol; aromatic hydrocarbons such as toluene and benzene; n-hexane and n- Examples include aliphatic hydrocarbons such as heptane; alicyclic hydrocarbons such as cyclohexane and methylcyclohexane; and organic solvents such as ketones such as methyl ethyl ketone and methyl isobutyl ketone. The said solvent can be used individually or in combination of 2 or more types. Note that the solvent includes the meaning of a dispersion medium.

In addition to the acrylic polymer (X), the acrylic polymer (Y), and the thermosetting resin (Z), the thermosetting adhesive composition (M2) may include an anti-aging agent, a filler ( Fillers), colorants (such as pigments and dyes), UV absorbers, antioxidants, crosslinking agents, tackifiers, plasticizers, softeners, surfactants, antistatic agents, and other known additives are used in the present invention. It may be included within a range that does not impair the characteristics. The said additive can be used individually or in combination of 2 or more types.

The filler (filler) is not particularly limited, and known and commonly used organic fillers and inorganic fillers can be used. Especially, a silica filler and a copper filler are preferable from the viewpoint of improving the strength of the thermosetting adhesive layer (L2) and further improving the heat resistance after wet heat of the thermosetting adhesive sheet (S2). The said filler can be used individually or in combination of 2 or more types.

In particular, the thermosetting adhesive composition (M2) comprises (meth) acrylic acid C _1-3 alkyl ester (a1), cyano group-containing monomer (b1) and carboxyl group-containing monomer (c1) as essential monomer components. And (meth) acrylic acid C _4-12 alkyl ester (a2), cyano group-containing monomer (b2) and carboxyl group-containing monomer (c2) as essential monomer components It is preferable to contain the made acrylic polymer (Y) as a main component. Furthermore, it is preferable to contain an etherified phenol resin.

The thermosetting adhesive composition (M2) includes, for example, an acrylic polymer (X), an acrylic polymer (Y), and a thermosetting resin (Z) (particularly an etherified phenol resin), as necessary. It can be prepared by mixing various additives. The acrylic polymer (X), acrylic polymer (Y), and thermosetting resin (Z) are dissolved in a solvent to form a solution, or dispersed in a dispersion medium to form a dispersion. It can also be used for the preparation of a thermosetting adhesive composition (M2).

[Thermosetting adhesive layer of the present invention (L1, L2)]
In the case of the thermosetting adhesive layer (L1), the thermosetting adhesive layer of the present invention is a thermosetting adhesive layer formed from the thermosetting adhesive composition (M1). In the case of the mold adhesive layer (L2), it is a thermosetting adhesive layer formed from the thermosetting adhesive composition (M2). The thermosetting adhesive layer of the present invention may have either a single layer or multiple layers.

The thickness of the thermosetting adhesive layer of the present invention is not particularly limited, but is preferably 5 to 100 μm, more preferably 10 to 50 μm, and particularly preferably 20 to 40 μm. It is preferable that the thickness is 5 μm or more because the adhesive force is improved. On the other hand, when the thickness exceeds 100 μm, the adhesive may protrude during high temperature pressing.

The thermosetting adhesive layer (L1) has at least one glass transition point in a temperature range of −50 ° C. to 10 ° C. and a temperature range of 20 ° C. to 100 ° C., respectively. The thermosetting adhesive layer (L1) may have a glass transition point in addition to the above temperature range as long as the effects of the present invention are not impaired. The glass transition point that the thermosetting adhesive layer (L1) has at −50 ° C. to 10 ° C. is “Tg _A ”, and the glass transition point that the thermosetting adhesive layer (L1) has at 20 ° C. to 100 ° C. The point may be referred to as “Tg _B ”. Each of Tg _A and Tg _B may be one or two or more.

The thermosetting adhesive layer (L1) has the Tg _{A in the range} of −50 ° C. to 10 ° C., preferably −30 ° C. to 10 ° C., more preferably −10 ° C. to 10 ° C. It is preferable to have the above Tg _A at −50 ° C. or higher because heat resistance after wet heat is not lowered. On the other hand, it is preferable to have the above Tg _A at 10 ° C. or lower because the adhesive force is improved.

The thermosetting adhesive layer (L1) has the Tg _B at 20 ° C. or higher and 100 ° C. or lower, preferably 20 ° C. or higher and 30 ° C. or lower, more preferably 20 ° C. or higher and 40 ° C. or lower. It is preferable to have the above Tg _B at 20 ° C. or higher because heat resistance after wet heat is improved. On the other hand, it is preferable to have the above Tg _B at 100 ° C. or lower because it is prevented from becoming too hard and the adhesive strength is not reduced.

In this specification, a glass transition point can be measured based on JISK7121, for example. Specifically, it is measured by the following <Method for Measuring Glass Transition Point>.
<Measuring method of glass transition point>
A thermosetting adhesive layer is collected from the thermosetting adhesive sheet and used as a glass transition point measurement sample. An endothermic curve of the sample is obtained by performing differential scanning calorimetry (DSC) using the sample. In the differential scanning calorimetry, an endothermic curve is obtained by increasing the temperature from −50 ° C. to 100 ° C. at a temperature increase rate of 10 ° C./min in a nitrogen atmosphere. The intermediate point of the bending point obtained from the endothermic curve is defined as the glass transition point. Of the obtained glass transition points, the glass transition point of −50 ° C. to 10 ° C. is referred to as “Tg _A ”, and the glass transition point of 20 ° C. to 100 ° C. is referred to as “Tg _B ”.

The gel fraction of the thermosetting adhesive layer of the present invention (before curing) is not particularly limited, but is less than 70% (% by weight) from the viewpoint of flexibility of the thermosetting adhesive layer of the present invention (for example, 0% or more and less than 70%), preferably less than 60%, more preferably less than 50%. The gel fraction can be obtained as methyl ethyl ketone insoluble matter. Specifically, the weight fraction (unit: weight) of the insoluble matter after immersion in methyl ethyl ketone for 7 days at room temperature (23 ° C.). %). It is preferable that the gel fraction is less than 70% because the flexibility of the thermosetting adhesive layer of the present invention is improved and the adhesive force is improved.

Specifically, the gel fraction (ratio of methyl ethyl ketone insoluble matter) can be measured and calculated by, for example, the following <Method for measuring gel fraction>.
<Method for measuring gel fraction>
About 0.1 g of the thermosetting adhesive layer of the present invention is sampled from the thermosetting adhesive sheet of the present invention to obtain a thermosetting adhesive layer for gel fraction measurement. After wrapping the thermosetting adhesive layer for measuring the gel fraction in a porous tetrafluoroethylene sheet (trade name “NTF1122”, manufactured by Nitto Denko Corporation) having pores having an average pore diameter of 0.2 μm, It is bound with a thread, the weight at that time is measured, and this weight is defined as the weight before immersion. The weight before immersion is the total weight of the thermosetting adhesive layer, the tetrafluoroethylene sheet, and the kite string. Further, the total weight of the tetrafluoroethylene sheet and the kite string is also measured, and this weight is defined as the wrapping weight.
Next, the above thermosetting adhesive layer wrapped with a tetrafluoroethylene sheet and tied with a kite string (referred to as “sample”) is placed in a 50 mL container filled with methyl ethyl ketone and 1 at room temperature (23 ° C.). Leave for a week (7 days). Thereafter, the sample (after methyl ethyl ketone treatment) is taken out from the container, transferred to an aluminum cup, dried in a dryer at 130 ° C. for 2 hours to remove methyl ethyl ketone, the weight is measured, and the weight is immersed in the weight. And
Then, the gel fraction is calculated from the following formula.
Gel fraction (% by weight) = (AB) / (CB) × 100
(In the above formula, A is the weight after immersion, B is the weight of the bag, and C is the weight before immersion.)

The gel fraction difference after storage for 7 days at 40 ° C. of the thermosetting adhesive layer (before curing) of the present invention (hereinafter sometimes simply referred to as “gel fraction difference”) is not particularly limited, but is 15% (% By weight) or less is preferable, and more preferably 13% or less. The upper limit of the gel fraction difference is not particularly limited and is, for example, 100%. The gel fraction difference of 15% or less is preferable because of excellent long-term storage stability.

The gel fraction difference is calculated from the following equation.
Gel fraction difference (% by weight) = (Gel fraction after storage at 40 ° C. for 7 days (% by weight))
-(Gel fraction (% by weight) of the thermosetting adhesive layer of the present invention (before curing))
The gel fraction after storage at 40 ° C. for 7 days is specifically the heat collected from the thermosetting adhesive sheet after storing the thermosetting adhesive sheet of the present invention at 40 ° C. for 7 days. The curable adhesive layer (before curing) can be measured and calculated in the same manner as in the above <Method for measuring gel fraction>, with “the thermosetting adhesive layer for measuring the gel fraction”.

The gel fraction after the curing treatment at 150 ° C. for 1 hour of the thermosetting adhesive layer of the present invention is not particularly limited, but is preferably 90% (% by weight) or more, more preferably 92% or more, and still more preferably 96. % Or more. The upper limit of the gel fraction after the curing treatment at 150 ° C. for 1 hour of the thermosetting adhesive layer of the present invention is not particularly limited and is, for example, 100%. When the gel fraction is 90% or more, the curing treatment of the thermosetting adhesive layer of the present invention can be rapidly and sufficiently advanced, and the adhesiveness after curing and the heat resistance after wet heat are preferable. When the gel fraction is less than 90%, the curing reaction at 150 ° C. for 1 hour does not proceed sufficiently, and the adhesive strength after curing and the heat resistance after wet heat may be insufficient. Furthermore, since a high curing temperature and a long curing time are required, the cost may increase.

The gel fraction of the thermosetting adhesive layer after the curing treatment at 150 ° C. for 1 hour is specifically determined by heating the thermosetting adhesive sheet of the present invention at 150 ° C. for 1 hour, for example. The thermosetting adhesive layer (thermosetting adhesive layer after curing) taken from the thermosetting adhesive sheet after the treatment was used as a “thermosetting adhesive layer for gel fraction measurement” as described above. It can be measured and calculated in the same manner as in <Method for measuring gel fraction>.

[Thermosetting adhesive sheet of the present invention]
The thermosetting adhesive sheet of the present invention has at least one thermosetting adhesive layer of the present invention. The thermosetting adhesive sheet of the present invention may have a substrate, a thermosetting adhesive layer other than the thermosetting adhesive layer of the present invention, and the like in addition to the thermosetting adhesive layer of the present invention. Good. The thermosetting adhesive sheet (S1) has at least one thermosetting adhesive layer (L1), and besides the thermosetting adhesive layer (L1), a base material, a thermosetting adhesive layer (L1) May have a thermosetting adhesive layer other than). The thermosetting adhesive sheet (S2) has at least one thermosetting adhesive layer (L2). In addition to the thermosetting adhesive layer (L2), the base material, the thermosetting adhesive layer It may have a thermosetting adhesive layer other than (L2). The thermosetting adhesive sheet of the present invention may have other layers (for example, an intermediate layer, an undercoat layer, etc.) as long as the effects of the present invention are not impaired. As for the layers other than the thermosetting adhesive layer (L1) or the layers other than the thermosetting adhesive layer (L2), only one layer may be provided, or two or more layers may be provided.

The thermosetting adhesive sheet of the present invention may be a single-sided adhesive sheet in which only one surface of the sheet is the adhesive layer surface (adhesive surface) (that is, the thermosetting adhesive layer surface of the present invention). And the double-sided adhesive sheet whose both surfaces of this sheet | seat are an adhesive bond layer surface (adhesion surface) may be sufficient. Although the thermosetting adhesive sheet of the present invention is not particularly limited, it is preferably a double-sided adhesive sheet from the viewpoint of being used for bonding articles (adherents) to each other, and more preferably, both surfaces of the sheet are It is a double-sided adhesive sheet that is the surface of a thermosetting adhesive layer.

The thermosetting adhesive sheet of the present invention may be a thermosetting adhesive sheet having a base material (thermosetting adhesive sheet with a base material), or a thermosetting adhesive sheet having no base material (base material). Less thermosetting adhesive sheet). As the thermosetting adhesive sheet of the present invention, for example, (1) a thermosetting adhesive sheet (baseless thermosetting adhesive sheet) comprising only the thermosetting adhesive layer of the present invention, (2) a base material Thermosetting adhesive sheet (thermosetting adhesive sheet with substrate) having the thermosetting adhesive layer of the present invention on at least one side (both sides or one side) (for example, at least one side of the substrate) A thermosetting adhesive sheet having a thermosetting adhesive layer (L1) on both sides (single side) or a thermosetting adhesive layer (L2) on at least one side (both sides or one side) of the substrate. A thermosetting adhesive sheet). As the thermosetting adhesive sheet of the present invention, a substrate-less thermosetting adhesive sheet is preferable, and only the thermosetting adhesive layer of the present invention having the above-described configuration (1) is preferable from the viewpoint of ease of manufacture. A substrate-less thermosetting adhesive sheet made of is preferable. The “base material” does not include a release liner (separator) that is peeled off when the thermosetting adhesive sheet is used.

In addition, when the thermosetting adhesive sheet of the present invention is a thermosetting adhesive sheet with a substrate, the thermosetting adhesive layer of the present invention may be provided on at least one surface side of the substrate. On the side of the substrate opposite to the side where the thermosetting adhesive layer of the present invention is provided, a thermosetting adhesive layer other than the thermosetting adhesive layer of the present invention, or a thermosetting adhesive A known adhesive layer [for example, a pressure-sensitive adhesive layer (pressure-sensitive adhesive layer) or the like] other than the layer may be provided.

The substrate is not particularly limited. For example, a paper-based substrate such as paper; a fiber-based substrate such as cloth, nonwoven fabric, or net; a metal-based substrate such as metal foil or metal plate; Plastic base materials such as films and sheets made of resin, polyester resin, polyvinyl chloride resin, vinyl acetate resin, polyamide resin, polyimide resin, polyether ether ketone (PEEK), polyphenylene sulfide (PPS), etc. Rubber base materials such as rubber sheets; foam-based base materials such as foam sheets, and laminates thereof (particularly laminates of plastic base materials and other base materials, and laminates of plastic films (or sheets)) An appropriate sheet-like material such as a body can be used.

The thickness of the substrate is not particularly limited, but is preferably 10 to 500 μm, more preferably 12 to 200 μm, and still more preferably 15 to 100 μm. In addition, the base material may have a single layer form or may have a multiple layer form. Further, the substrate may be subjected to various treatments such as back treatment, antistatic treatment, and undercoating treatment as necessary.

The thermosetting adhesive sheet of the present invention may have, for example, a form wound in a roll shape or a form in which sheets are laminated. That is, the thermosetting adhesive sheet of the present invention can have forms such as a sheet form and a tape form. In addition, when the thermosetting adhesive sheet of the present invention has a form wound in a roll shape, for example, a release treatment in which the thermosetting adhesive layer is formed on the back side of the release liner or the base material The form wound by the roll shape in the state protected by the layer may be sufficient.

The surface of the adhesive layer (for example, the thermosetting adhesive layer of the present invention) in the thermosetting adhesive sheet of the present invention may be protected by a release liner (separator). The release liner is not particularly limited, and can be appropriately selected from known release liners. As the release liner, for example, a release liner in which the surface of a base material (liner base material) such as paper or plastic film is treated with silicon, or the surface of a base material (liner base material) such as paper or plastic film is a polyolefin. A release liner laminated with a resin is preferable. The polyolefin resin is not particularly limited, but a polyethylene resin is preferable.

The thermosetting adhesive sheet of the present invention can be produced according to a known or commonly used method for producing an adhesive sheet. For example, when the thermosetting adhesive sheet of the present invention is a substrate-less thermosetting adhesive sheet, the thermosetting adhesive composition (M1) or the thermosetting adhesive composition (M2) is formed on the release surface of the release liner. ) Is applied so that the thickness after drying becomes a predetermined thickness, and the thermosetting adhesive layer of the present invention is formed by a method of drying to produce the thermosetting adhesive sheet of the present invention. it can.
When the thermosetting adhesive sheet of the present invention is a thermosetting adhesive sheet with a substrate, after the thermosetting adhesive layer of the present invention is formed on the release surface of the release liner, the heat The thermosetting adhesive sheet of the present invention can be produced by a method of transferring the curable adhesive layer onto the surface of the substrate. Further, the thermosetting adhesive composition (M1) or the thermosetting adhesive composition (M2) is applied on the surface of the base material so that the thickness after drying becomes a predetermined thickness, and is dried. The thermosetting adhesive layer of the present invention can be formed by the method to produce the thermosetting adhesive sheet of the present invention.

In the application of the thermosetting adhesive composition (M1) or the thermosetting adhesive composition (M2), a conventional coater (for example, gravure roll coater, reverse roll coater, kiss roll coater, dip roll) A coater, a bar coater, a knife coater, a spray roll coater, etc.) can be used.

The thermosetting adhesive sheet of the present invention and the thermosetting adhesive layer of the present invention can exhibit an excellent adhesive force by causing a curing reaction to proceed (thermosetting) by heating. The thermosetting adhesive sheet of the present invention is heated to cure (thermoset) the thermosetting adhesive layer of the present invention, whereby an adhesive sheet having a strong adhesive force (thermoset thermosetting adhesive sheet) ) Is obtained. The curing conditions (heating conditions) are not particularly limited, but it is preferable to heat at a temperature of 100 ° C. or higher (eg, 100 to 200 ° C.) for 30 minutes or longer (eg, 30 to 360 minutes), more preferably 150 It is 60 minutes or more (for example, 60 to 360 minutes) at a temperature of at least 0 ° C (for example, 150 to 200 ° C).

In the thermosetting adhesive sheet (S1), the thermosetting adhesive layer (L1) has Tg _A and Tg _{B so} that it has a strength at which foaming is not confirmed even when solder dipping at 260 ° C. after humidification. And adhesion can be imparted.
The thermosetting adhesive layer (L1) has a glass transition point of 20 ° C. or more and 100 ° C. or less, and therefore is exposed to extremely severe temperature conditions such as high temperature and long-time processing conditions after bonding. Even in such a case, foaming of the adhesive layer is suppressed, and extremely excellent heat resistance after wet heat is exhibited.
In addition, since it has a glass transition point between −50 ° C. and 10 ° C., it also has a certain degree of flexibility. ) Can also be compatible. Furthermore, even when exposed to very severe temperature conditions after bonding, the adhesive layer is prevented from being lifted off and exhibits extremely excellent heat resistance after wet heat.

In the thermosetting adhesive sheet (S2), when the thermosetting adhesive composition (M2) contains the acrylic polymer (X), the thermosetting adhesive layer (L2) formed from the composition is contained. ) Is an adhesive layer having high strength (bulk strength). Thereby, even if it is a case where it is exposed to very severe temperature conditions such as high temperature and long-time processing conditions after bonding, foaming of the adhesive layer is suppressed, and the thermosetting adhesive sheet (S2) Excellent heat resistance after wet heat.
In addition, since the thermosetting adhesive composition (M2) contains the acrylic polymer (Y), the thermosetting adhesive layer (L2) formed from the composition has a certain degree of flexibility. Therefore, it is possible to prevent a decrease in adhesive force due to being too hard and to achieve a high adhesive force (adhesiveness). Furthermore, even when exposed to very severe temperature conditions after bonding, the adhesive layer is prevented from being lifted off, and the thermosetting adhesive sheet (S2) exhibits extremely excellent heat resistance after wet heat. To do.
When an etherified phenol resin is used as the thermosetting resin (Z), the adhesive strength of the thermosetting adhesive layer (L2) and the heat resistance after wet heat are particularly improved. This is preferable because it is possible to achieve both properties at an extremely high level.

In addition, the said thermosetting type adhesive sheet (S2) can satisfy | fill the effect of this invention irrespective of whether it is a thermosetting type adhesive sheet (S1).

The thermosetting adhesive sheet of the present invention can exhibit high adhesive strength and particularly excellent heat resistance after wet heat after being cured by heating. Therefore, the thermosetting adhesive sheet of the present invention is used for applications requiring excellent heat resistance after moist heat that does not cause foaming or floating even when firmly bonded and processed under extremely severe temperature conditions after bonding. Etc. can be preferably used. Specifically, the thermosetting adhesive sheet of the present invention can be preferably used for bonding on a flexible printed circuit board (FPC), for example. That is, the thermosetting adhesive sheet of the present invention is preferably an FPC thermosetting adhesive sheet. Note that the adhesion in the FPC means, for example, adhesion when the FPC is manufactured or adhesion when the FPC is bonded to the reinforcing plate.

The FPC often passes through a high temperature reflow process before being incorporated into the final product, and the thermosetting adhesive sheet used is required to be free from foaming and peeling off after passing through the reflow process. Particularly in such FPC applications, “heat resistance after wet heat” is regarded as important from the viewpoint of reliability. The “heat resistance after wet heat” refers to a laminate produced by bonding an adherend using a thermosetting adhesive sheet under high temperature and high humidity (for example, temperature 40 to 60 ° C., humidity 60 to 95). In the case of processing under severe temperature conditions (for example, at a temperature of 250 to 270 ° C. for 1 to 3 minutes) after storage in an environment of% RH, the above thermosetting adhesive sheet (thermosetting adhesive layer) It means the characteristic that foaming and peeling are hard to occur. The thermosetting adhesive sheet of the present invention can be used as a highly reliable thermosetting adhesive sheet, particularly in FPC applications, because it can exhibit excellent post-wet heat resistance as well as high adhesive strength after thermosetting. can do.

As another embodiment, the present invention provides a heat formed from a thermosetting adhesive composition containing a first acrylic polymer and a second acrylic polymer as main components and a thermosetting resin. A thermosetting adhesive sheet having a curable adhesive layer, wherein the monomer component constituting the first acrylic polymer and the monomer component constituting the second acrylic polymer are different (hereinafter, It may be referred to as “the thermosetting adhesive sheet of another embodiment”. The total amount (total content) of the content of the first acrylic polymer and the content of the second acrylic polymer in the total nonvolatile content (100% by weight) of the thermosetting adhesive composition is 50% by weight. % Or more.

The first acrylic polymer and the second acrylic polymer in the thermosetting adhesive sheet of the other embodiment are not particularly limited, and each of them is configured with a known and common acrylic monomer as an essential monomer component. Acrylic polymer. Among them, an acrylic polymer composed of (meth) acrylic acid alkyl ester having a linear or branched alkyl group having 1 to 12 carbon atoms, a cyano group-containing monomer, and a carboxyl group-containing monomer as essential monomer components. It is preferable that Furthermore, monomer components (other monomer components) other than the above monomers may be used.

The monomer component constituting the first acrylic polymer is different from the monomer component constituting the second acrylic polymer. That is, it is necessary that the monomer component constituting the first acrylic polymer and the monomer component constituting the second acrylic polymer do not completely match (all the monomer components match). Thereby, the strength and flexibility of the thermosetting adhesive layer of the thermosetting adhesive sheet of another embodiment can be made compatible, and high adhesive strength and excellent heat resistance after wet heat can be made compatible.

[Flexible printed circuit board (FPC)]
By producing an FPC using the thermosetting adhesive sheet of the present invention, or by bonding the FPC to a reinforcing plate using the thermosetting adhesive sheet of the present invention, the thermosetting adhesive sheet of the present invention is obtained. An FPC having the same can be obtained.

In the FPC having the thermosetting adhesive sheet of the present invention, an FPC having a thermosetting adhesive sheet having a strong adhesive force (having a thermosetting thermosetting adhesive sheet) is obtained by thermosetting the adhesive sheet. FPC) can be obtained. The curing conditions in the above thermosetting are not particularly limited, but it is preferable to heat at a temperature of 100 ° C. or higher (for example, 100 to 200 ° C.) for 30 minutes or longer (for example, 30 to 360 minutes), more preferably. The temperature is 150 ° C. or higher (for example, 150 to 200 ° C.) for 60 minutes or longer (for example, 60 to 360 minutes).

Hereinafter, the present invention will be described in more detail based on examples, but the present invention is not limited to these examples.

Table 1 shows the type of acrylic polymer, monomer composition, weight average molecular weight (Mw) and content (mixing amount) in the thermosetting adhesive composition, and thermosetting resin in Examples and Comparative Examples. The kind (etherified phenol resin etc.) and the content (blending amount) in the thermosetting adhesive composition are shown. In Table 1, the monomer composition of the acrylic polymer was represented by the content (% by weight) of each monomer in the total amount (100% by weight) of monomer components constituting the acrylic polymer. Moreover, content of an acrylic polymer and a thermosetting resin was represented by content (weight part) as a non volatile matter.

Example 1
(Preparation of acrylic polymer (X1))
In a reactor equipped with a cooling tube, a nitrogen introducing tube, a thermometer and a stirrer, 2,2′-azobis {2- [1- (2-hydroxyethyl) -2-imidazolin-2-yl] propane} dihydrochloride (Product name “VA-060”, manufactured by Wako Pure Chemical Industries, Ltd.) (Polymerization initiator) 0.279 g and ion-exchanged water 100 g were added and stirred for 1 hour while introducing nitrogen gas. This was kept at 60 ° C., where 65 parts by weight of ethyl acrylate (ethyl acrylate) (EA), 30 parts by weight of acrylonitrile (AN), 5 parts by weight of acrylic acid (AA), 1-dodecanethiol (chain transfer agent) 0 .04 parts by weight and 2 parts by weight of polyoxyethylene lauryl ether sodium sulfate (emulsifier) added to 41 parts by weight of ion exchange water and emulsified (emulsion of monomer raw material) 400 g were gradually added dropwise over 3 hours, The emulsion polymerization reaction was allowed to proceed. After completion of dropping of the monomer raw material emulsion, the mixture was further aged by maintaining the same temperature for 3 hours. The aqueous dispersion (emulsion) of the acrylic polymer thus polymerized was dried to obtain acrylic polymer (X1) (weight average molecular weight 1,500,000).

(Preparation of acrylic polymer (Y1))
In a reactor equipped with a cooling tube, a nitrogen introducing tube, a thermometer and a stirrer, 2,2′-azobis {2- [1- (2-hydroxyethyl) -2-imidazolin-2-yl] propane} dihydrochloride (Product name “VA-060”, manufactured by Wako Pure Chemical Industries, Ltd.) (Polymerization initiator) 0.279 g and ion-exchanged water 100 g were added and stirred for 1 hour while introducing nitrogen gas. This was kept at 60 ° C., where butyl acrylate (n-butyl acrylate) (BA) 66 parts by weight, acrylonitrile (AN) 29 parts by weight, acrylic acid (AA) 5 parts by weight, 1-dodecanethiol (chain transfer agent) ) 400 g of 0.04 parts by weight and 2 parts by weight of polyoxyethylene lauryl ether sodium sulfate (emulsifier) added to 41 parts by weight of ion-exchanged water and emulsified (monomer raw material emulsion) are gradually added dropwise over 3 hours. The emulsion polymerization reaction was allowed to proceed. After completion of dropping of the monomer raw material emulsion, the mixture was further aged by maintaining the same temperature for 3 hours. The aqueous dispersion (emulsion) of the acrylic polymer thus polymerized was dried to obtain an acrylic polymer (Y1) (weight average molecular weight 1 million).

(Preparation of thermosetting adhesive composition)
Acrylic polymer (X1) [Copolymer composed of 65% by weight of ethyl acrylate (EA), 30% by weight of acrylonitrile (AN), 5% by weight of acrylic acid (AA) as monomer components]: 100 parts by weight and the above Acrylic polymer (Y1) [copolymer comprising 66% by weight of butyl acrylate (BA), 29% by weight of acrylonitrile (AN), 5% by weight of acrylic acid (AA) as monomer components]: 3 parts by weight are dissolved A butanol solution in which 12 parts by weight (non-volatile content) of a trade name “CKS-3898” (manufactured by Showa Denko KK) as an etherified phenol resin (Z1): 12 parts by weight (nonvolatile content) was mixed and stirred. A curable adhesive composition (solution) was prepared.
That is, in the thermosetting adhesive composition, 100 parts by weight of the acrylic polymer (X1), 3 parts by weight of the acrylic polymer (Y1), and an etherified phenol resin (thermosetting resin) (Z1) are contained. 12 parts by weight are included. The total content of the acrylic polymer (X1) and the acrylic polymer (Y1) in the total nonvolatile content (100% by weight) of the thermosetting adhesive composition is 90% by weight.

(Preparation of thermosetting adhesive sheet)
The thermosetting adhesive composition is applied to the release surface of the release liner so that the thickness after drying is 25 μm, and dried at 100 ° C. for 3 minutes to form a thermosetting adhesive layer (thickness 25 μm). Thus, a thermosetting adhesive sheet (a baseless thermosetting adhesive sheet consisting only of a thermosetting adhesive layer) was obtained.

Examples 2-4
As shown in Table 1, the content of the acrylic polymer (Y1) and the content of the etherified phenol resin (Z1) were changed, and the thermosetting adhesive composition and the thermosetting were performed in the same manner as in Example 1. A mold adhesive sheet was obtained.

Examples 5-8
(Preparation of acrylic polymer (X2))
An acrylic polymer was prepared in the same manner as in the preparation of the acrylic polymer (X1) of Example 1, except that the amount of the polymerization initiator (trade name “VA-060”) was changed from 0.279 g to 0.140 g. (X2) (weight average molecular weight 3 million) was obtained.
(Preparation of thermosetting adhesive composition, preparation of thermosetting adhesive sheet)
As shown in Table 1, acrylic polymer (X2) was used instead of acrylic polymer (X1), and the content of acrylic polymer (Y1) and the content of etherified phenol resin (Z1) were changed. In the same manner as in Example 1, a thermosetting adhesive composition and a thermosetting adhesive sheet were obtained.

Comparative Example 1
As shown in Table 1, a thermosetting adhesive composition and a thermosetting adhesive sheet were obtained in the same manner as in Example 1 without using the acrylic polymer (Y1).

Comparative Example 2
As shown in Table 1, the acrylic polymer (Y1) was not used, and the acrylic polymer (X2) was used instead of the acrylic polymer (X1). An agent composition and a thermosetting adhesive sheet were obtained.

Comparative Example 3
As shown in Table 1, the acrylic polymer (X1) was not used, and the content of the acrylic polymer (Y1) was changed, and in the same manner as in Example 1, the thermosetting adhesive composition and the heat A curable adhesive sheet was obtained.

Comparative Example 4
(Preparation of acrylic polymer (Y2))
The amount of butyl acrylate (n-butyl acrylate) (BA) is 66 to 64 parts by weight, the amount of acrylonitrile (AN) is 29 to 34 parts by weight, and the amount of acrylic acid (AA) is 5 parts by weight. An acrylic polymer (Y2) was obtained in the same manner as in the preparation method of the acrylic polymer (Y1) of Example 1, except that the amount was changed to 2 parts by weight.
(Preparation of thermosetting adhesive composition)
Acrylic polymer (Y2) [copolymer comprising 64% by weight of butyl acrylate (BA), 34% by weight of acrylonitrile (AN) and 2% by weight of acrylic acid (AA) as monomer components]: 100 parts by weight dissolved A methanol solution in which 10 parts by weight (non-volatile content) of product name “PR-51283” (manufactured by Sumitomo Bakelite Co., Ltd.) as a resol type phenol resin (Z2) was dissolved in the ethyl acetate solution was mixed and stirred. A thermosetting adhesive composition (solution) was prepared.
That is, the thermosetting adhesive composition contains 100 parts by weight of the acrylic polymer (Y2) and 10 parts by weight of the thermosetting resin (Z2). The content of the acrylic polymer (Y2) in the total nonvolatile content (100% by weight) of the thermosetting adhesive composition is 90% by weight.

(Preparation of thermosetting adhesive sheet)
In the same manner as in Example 1, a thermosetting adhesive composition and a thermosetting adhesive sheet were obtained.

(Evaluation)
For each thermosetting adhesive sheet obtained in Examples and Comparative Examples, each adhesive strength after curing of the thermosetting adhesive layer, after wet heat heat resistance, glass transition temperature (Tg _A, Tg _B), and the following It measured or evaluated by the measuring method or the evaluation method. Moreover, the gel fraction of the thermosetting adhesive layer of the present invention (before thermosetting), the gel fraction difference after storage at 40 ° C. for 7 days, and the gel fraction after 1 hour curing at 150 ° C. are described above. It measured by the evaluation method.

(1) Measuring method of adhesive force About the thermosetting type adhesive layer after hardening in each thermosetting type adhesive sheet obtained in the examples and comparative examples, the adhesive strength (N / cm) at 23 ° C was determined by the following method. It was measured.
A flexible printed circuit board (FPC; size: width 5 cm × length 8 cm, thickness 0.2 mm) and a thermosetting adhesive sheet were laminated at 130 ° C. and then cut to 1 cm width (the thermosetting adhesive sheet is an FPC). (It is laminated on the entire surface of one side of the material (surface material: polyimide)). This was laminated to a stainless steel plate (SUS304BA plate) (SUS; size: length 5 cm × width 5 cm, thickness 0.4 mm) at 130 ° C. using a laminator, and then thermocompression bonded at 160 ° C. and 2 MPa for 90 seconds (pressing) ) And pasted. Furthermore, the specimen was prepared by curing (heat curing) at 150 ° C. for 1 hour.

Using the tensile tester (equipment trade name “TCM-1kNB”, manufactured by Minebea Co., Ltd.), the above test specimen was 90 ° peel adhesive (tensile speed: 50 mm / min, 23 ° C.) by pulling the FPC side. , 50% RH; N / cm).
The measurement results are shown in the column of “Adhesive strength (N / cm) SUS” in Table 1.

Further, in the above measurement, a 90 ° peel adhesive force was similarly measured using a polyimide plate (PI; size: length 5 cm × width 5 cm, thickness 0.13 mm) instead of the stainless steel plate. The measurement results are shown in the column of “Adhesive strength (N / cm) PI” in Table 1.

(2) Evaluation method of heat resistance after wet heat (260 ° C solder dip after humidification)
About the thermosetting adhesive layer after hardening in each thermosetting adhesive sheet obtained in Examples and Comparative Examples, the heat resistance after wet heat was evaluated.
A copper-clad laminate (CCL; polyimide / copper laminate, size: width 5 cm × length 8 cm, thickness 45 μm) and a thermosetting adhesive sheet were laminated at 130 ° C. and then cut to 1 cm width (thermosetting). The mold adhesive sheet is laminated on the entire CCL polyimide surface). This was laminated to a stainless steel plate (SUS304BA plate) (SUS; size: length 5 cm × width 5 cm, thickness 0.4 mm) at 130 ° C. using a laminator, and then thermocompression-bonded (pressed at 160 ° C., 2 MPa for 90 seconds) ) And pasted. Furthermore, the specimen was prepared by curing (heat curing) at 150 ° C. for 1 hour.
The test specimen was allowed to stand for 24 hours under humidified conditions (temperature: 60 ° C., humidity: 90% RH), and then the surface on the stainless steel plate side of the specimen was dipped (immersed) in a 260 ° C. solder bath. )

The heat-curing adhesive sheet (thermosetting adhesive layer) in the test specimen was lifted and peeled off and visually observed for foaming, and the heat resistance after wet heat was evaluated according to the following criteria. The evaluation results are shown in the column of “heat resistance after wet heat SUS” in Table 1.
Excellent heat resistance after wet heat (（): Floating off the thermosetting adhesive layer and no foaming was confirmed.
Good heat resistance after moist heat (O): Only a small amount of floating and peeling was confirmed only at the end of the applied part.
Although heat resistance is slightly inferior after wet heat, it can be used (△): The foamed part was lifted off at the end of the affixed part and part other than the end, and foaming was confirmed.
Heat resistance after wet heat is inferior (x): The thermosetting adhesive layer was lifted off on the entire surface, and foaming was confirmed.

Also, in the above evaluation, heat resistance after wet heat was similarly evaluated using a polyimide plate (PI; size: length 5 cm × width 5 cm, thickness 0.13 mm) instead of the stainless steel plate. The evaluation results are shown in the column of “heat resistance after wet heat PI” in Table 1.

(3) Measuring method of glass transition point (glass transition temperature) About the thermosetting adhesive layer in each thermosetting type adhesive sheet obtained by the Example and the comparative example, a glass transition point (degreeC) was measured with the following method. did.
About 2 mg of the thermosetting adhesive layer was weighed out of the thermosetting adhesive sheet, used as a sample for measuring the glass transition point, and used for DSC measurement. The sample was placed in an aluminum cylindrical cell having a diameter of 5 mm and a depth of 2 mm, covered with a lid, and sealed. An empty aluminum cylindrical cell was prepared as a reference sample. Using a differential scanning calorimeter (trade name “Q2000”, manufactured by TA Instruments), the temperature was raised from −50 ° C. to 100 ° C. at a rate of 10 ° C./min in a nitrogen atmosphere (nitrogen flow rate: 50 ml / min). Thereafter, the sample was rapidly cooled to −50 ° C., and the endothermic curve of the sample was measured when the temperature was raised again in the range of −50 ° C. to 100 ° C. at a rate of 10 ° C./min.
The intermediate point of the bending point in the obtained endothermic curve was taken as the glass transition point. Of the obtained glass transition points, the glass transition point of −50 ° C. or more and 10 ° C. or less is “Tg _A ”, the glass transition point of 20 ° C. or more and 100 ° C. or less is “Tg _B ”, and Tg _A and Tg _B is shown in the “Tg _A ” column and the “Tg _B ” column of Table 1.

As is apparent from Table 1, the thermosetting adhesive sheet of the present invention has high adhesive strength after curing and excellent adhesiveness, and further, when humidified and subjected to treatment under extremely severe temperature conditions of 260 ° C. solder dip. Also has high heat resistance after wet heat.
On the other hand, when the thermosetting adhesive layer does not have a glass transition point at −50 ° C. or more and 10 ° C. or less (in the thermosetting adhesive composition forming the thermosetting adhesive layer, the acrylic polymer (Y) (Comparative Examples 1 and 2), the thermosetting adhesive layer became too hard and the adhesive strength was reduced. Furthermore, after the humidification, the 260 ° C. solder dipping treatment caused floating and foaming at the interface between the thermosetting adhesive layer and the adherend, and the heat resistance after wet heat was poor. When the thermosetting adhesive layer does not have a glass transition point at 20 ° C. or more and 100 ° C. or less (in the thermosetting adhesive composition forming the thermosetting adhesive layer, the acrylic polymer (X) (When not included) (Comparative Examples 3 and 4), the bulk strength of the thermosetting adhesive layer is lowered, and after humidification, foaming occurs in the thermosetting adhesive layer by the treatment of 260 ° C. solder dipping. The post-heat resistance was poor.

The thermosetting adhesive sheet of the present invention is used for applications that require excellent heat resistance after moist heat that does not cause foaming or peeling even when firmly bonded and processed under extremely severe temperature conditions after bonding. It can be preferably used. Specifically, the thermosetting adhesive sheet of the present invention can be preferably used for bonding on a flexible printed circuit board (FPC), for example.

Claims (13)

A thermosetting adhesive sheet having a thermosetting adhesive layer having a glass transition point at −50 ° C. to 10 ° C. and 20 ° C. to 100 ° C., respectively. From the thermosetting adhesive composition in which the thermosetting adhesive layer contains the following acrylic polymer (X) and the following acrylic polymer (Y) as main components and contains a thermosetting resin (Z). The thermosetting adhesive sheet according to claim 1, which is a formed thermosetting adhesive layer.
Acrylic polymer (X): An acrylic polymer composed of (meth) acrylic acid alkyl ester (a1) having a linear or branched alkyl group having 1 to 3 carbon atoms as an essential monomer component. An acrylic polymer in which the content of the alkyl (meth) acrylate (a1) is 50% by weight or more in the total amount (100% by weight) of monomer components constituting the acrylic polymer. Acrylic polymer (Y) Acrylic polymer comprising, as an essential monomer component, a (meth) acrylic acid alkyl ester (a2) having a linear or branched alkyl group having 4 to 12 carbon atoms, the acrylic polymer The content of the alkyl (meth) acrylate (a2) in the total amount (100% by weight) of monomer components constituting Acrylic polymer of 0% by weight or more The thermosetting adhesive sheet according to claim 2, wherein the content of the acrylic polymer (Y) is 1 to 100 parts by weight with respect to 100 parts by weight of the acrylic polymer (X). The thermosetting according to claim 2 or 3, wherein the acrylic polymer (X) is an acrylic polymer further comprising a cyano group-containing monomer (b1) and a carboxyl group-containing monomer (c1) as essential monomer components. Mold adhesive sheet. The acrylic polymer (Y) is an acrylic polymer further comprising a cyano group-containing monomer (b2) and a carboxyl group-containing monomer (c2) as essential monomer components. The thermosetting adhesive sheet according to 1. The thermosetting adhesive sheet according to any one of claims 2 to 5, wherein the thermosetting resin (Z) is a phenol resin. The thermosetting adhesive sheet according to claim 6, wherein the phenol resin is an etherified phenol resin. The thermosetting type according to any one of claims 2 to 7, wherein the content of the thermosetting resin (Z) is 1 to 40 parts by weight with respect to 100 parts by weight of the acrylic polymer (X). Adhesive sheet. The thermosetting adhesive sheet according to any one of claims 1 to 8, which is a thermosetting adhesive sheet for flexible printed circuit boards. A flexible printed circuit board comprising the thermosetting adhesive sheet according to claim 9. A thermoset thermosetting adhesive sheet obtained by thermosetting the thermosetting adhesive sheet according to any one of claims 1 to 9. A flexible printed circuit board comprising the thermosetting thermosetting adhesive sheet according to claim 11. A thermosetting adhesive layer formed from a thermosetting adhesive composition containing the first acrylic polymer and the second acrylic polymer as main components and containing a thermosetting resin; A thermosetting adhesive sheet, wherein a monomer component constituting the first acrylic polymer is different from a monomer component constituting the second acrylic polymer.