TW201313868A - 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 DEG C to 10 DEG C inclusive and a glass transition point in the range from 20 DEG C to 100 DEG C inclusive.

Description

Thermoset type sheet and flexible printed circuit board

This invention relates to a thermoset backsheet having a thermoset adhesive layer. More specifically, it relates to a thermosetting adhesive sheet which can be preferably used in a flexible printed circuit board or the like. Further, it relates to a flexible printed circuit board having the heat-set adhesive sheet.

A flexible printed circuit board (sometimes referred to as "FPC" (Flexible Printed Circuit)) is widely used in electronic equipment. In the FPC, (1) a process of producing an FPC by 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, or (2) An adhesive is used in the process of adhering the FPC to a reinforcing plate such as an aluminum plate, a stainless steel plate, or a polyimide plate.

As a binder used in the subsequent step of such FPC, a thermosetting adhesive containing a thermosetting resin such as a phenol resin or an epoxy resin is known. These thermosetting adhesives are cured by, for example, heating at 150 ° C or higher, and the thermosetting resin contained in the adhesive is cured, thereby exerting an adhesive force.

When the layered body produced by using the above-mentioned thermosetting type adhesive followed by the adherend (FPC or the like) is treated in a high temperature step such as a reflow step, there is evaporation of water or the like contained in the adhesive or the adherend. The case of foaming (expansion) or swelling of the adhesive is produced. Therefore, as a solution to the above problems, it is possible to exhibit excellent adhesion and heat resistance after moist heat after curing (after storage under high temperature and high humidity conditions, it is not easy to cause foaming or bulging of the adhesive layer when it is treated by a high temperature step). Stripping characteristics) thermosetting adhesive The thermosetting type of the layer is known to have a thermosetting type of a thermosetting adhesive layer formed of a thermosetting adhesive composition comprising an acrylic polymer as a main component and further comprising an etherified phenol resin. Sheet (refer to Patent Document 1).

Prior technical literature Patent literature

Patent Document 1: International Publication No. 2011/004710

However, in recent years, there has been a gradual demand for higher foaming or bulging peeling even under the harsher processing conditions (the conditions for longer processing at high temperatures) than the high temperature steps such as the previous reflow step. Heat resistance after damp heat. In response to such a request, even in the case of the above-described thermosetting type of sheet, heat resistance may be insufficient after moist heat.

Accordingly, an object of the present invention is to provide a thermosetting back sheet having a thermosetting adhesive layer which exhibits high adhesion (high adhesion) and excellent heat resistance after damp heat after curing.

After storage under high temperature and high humidity conditions, the foaming or swelling of the adhesive (adhesive layer) occurs when the high temperature step is applied. The reason is that the strength of the adhesive is insufficient, but if the adhesive is hardened On the other hand, in order to increase the strength of the adhesive, there is a problem that the adhesion to the adherend is deteriorated and the adhesion is lowered.

Therefore, in order to solve the above problems, the inventors conducted intensive studies and found that by having a specific region and having a specific region A thermosetting adhesive sheet having a glass transition point, and a thermosetting adhesive sheet having a thermosetting adhesive layer capable of exhibiting high adhesion and excellent heat resistance after heat and humidity after curing, thereby completing the present invention . Further, it has been found that a thermosetting adhesive composition containing 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 is formed. The thermosetting adhesive layer is used to obtain a thermosetting adhesive sheet having a thermosetting adhesive layer which exhibits high adhesion after curing and extremely excellent heat resistance after damp heat.

That is, the present invention provides a thermosetting back sheet characterized by having a thermosetting adhesive layer having a glass transition point of -50 ° C or more and 10 ° C or less, and 20 ° C or more and 100 ° C or less.

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

The above acrylic acid based on 100 parts by weight of the above acrylic polymer (X) The content of the polymer (Y) is preferably from 1 to 100 parts by weight.

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

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

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

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

The thermosetting back sheet of the present invention is preferably a thermosetting back sheet for a flexible printed circuit board.

Further, the present invention provides a flexible printed circuit board having the above-described thermosetting type succeeding sheet.

Further, the present invention provides a heat-curable thermosetting back sheet which is obtained by thermally curing the above-mentioned thermosetting sheet.

Further, the present invention provides a flexible printed circuit board having the above-described heat-cured thermosetting back sheet.

Moreover, the present invention provides a thermosetting adhesive sheet comprising a thermosetting adhesive composition comprising a first acrylic polymer and a second acrylic polymer as a main component and comprising a thermosetting resin. The formed thermosetting adhesive layer has a monomer component constituting the first acrylic polymer and a monomer component constituting the second acrylic polymer.

Moreover, the present invention provides a thermosetting adhesive sheet comprising the following acrylic polymer (X) and the following acrylic polymer (Y) as a main component, and comprising a thermosetting resin (Z) A thermosetting adhesive layer formed by the thermosetting adhesive composition. The acrylic polymer (X) is an acrylic polymer obtained by using an alkyl (meth)acrylate (a1) having a linear or branched alkyl group having 1 to 3 carbon atoms as an essential monomer component. The content of the alkyl (meth)acrylate (a1) in the total amount (100% by weight) of the monomer components constituting the acrylic polymer is 50% by weight or more. Further, the acrylic polymer (Y) is an acrylic acid composed of an alkyl (meth)acrylate (a2) having a linear or branched alkyl group having 4 to 12 carbon atoms as an essential monomer component. The content of the (meth)acrylic acid alkyl ester (a2) in the total amount (100% by weight) of the monomer components constituting the acrylic polymer is 50% by weight or more. The content of the acrylic polymer (Y) is preferably from 1 to 100 parts by weight based on 100 parts by weight of the acrylic polymer (X). The acrylic polymer (X) is preferably an acrylic polymer comprising a cyano group-containing monomer (b1) and a carboxyl group-containing monomer (c1) as essential monomer components. The acrylic polymer (Y) is preferably an acrylic polymer comprising a cyano group-containing monomer (b2) and a carboxyl group-containing monomer (c2) as essential monomer components. The above thermosetting resin (Z) is preferably a phenol resin, more preferably an etherified phenol resin. The content of the thermosetting resin (Z) is preferably from 1 to 40 parts by weight based on 100 parts by weight of the acrylic polymer (X). The thermosetting back sheet of the present invention is preferably a thermosetting back sheet for a flexible printed circuit board. Further, the present invention provides a flexible printed circuit board having the above-described thermosetting type succeeding sheet. Further, the present invention provides a heat-curable thermosetting back sheet which is obtained by thermally curing the above-mentioned thermosetting sheet. Further, the present invention provides a flexible printed circuit board having the above-described heat-cured thermosetting back sheet.

The thermosetting adhesive sheet of the present invention has the above-described constitutional characteristics, and after curing, the thermosetting adhesive layer can exhibit high adhesion and excellent heat resistance after moist heat.

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

The present invention comprises a thermosetting back sheet having at least one layer of a thermosetting adhesive layer having a glass transition point of at least -50 ° C to 10 ° C and below 20 ° C and below 100 ° C, and having at least one layer containing A thermosetting adhesive sheet of a thermosetting adhesive layer formed of an acrylic polymer (X) and an acrylic polymer (Y) as a main component and a thermosetting adhesive composition containing a thermosetting resin (Z) .

Further, in the present specification, the above-mentioned "thermosetting type having at least one layer of a thermosetting adhesive layer having a glass transition point of -50 ° C or more and 10 ° C or less and 20 ° C or more and 100 ° C or less respectively may be followed. The sheet is referred to as a "thermosetting type sheet (S1)", and the above-mentioned "having at least one layer containing an acrylic polymer (X) and an acrylic polymer (Y) as a main component may contain thermosetting property. The thermosetting adhesive sheet of the thermosetting adhesive layer formed of the thermosetting adhesive composition of the resin (Z) is referred to as "thermosetting type sheet (S2)". In addition, the above may be "at -50 ° C or more and 10 ° C or less, and 20 ° C. The above-mentioned thermosetting type adhesive layer having a glass transition point of 100 ° C or less is referred to as "thermosetting type adhesive layer (L1)". Further, the thermosetting adhesive composition forming the above-described thermosetting adhesive layer (L1) may be referred to as "thermosetting adhesive composition (M1)". Further, the above-mentioned "thermosetting adhesive composition containing the acrylic polymer (X) and the acrylic polymer (Y) as a main component and containing the thermosetting resin (Z)" may be referred to as "thermosetting type". In the composition (M2), the above-mentioned "thermosetting adhesive composition containing the acrylic polymer (X) and the acrylic polymer (Y) as a main component and containing the thermosetting resin (Z) may be used. The formed thermosetting adhesive layer (i.e., the thermosetting adhesive layer formed of the thermosetting adhesive composition (M2)) is referred to as "thermosetting adhesive layer (L2)".

Further, in the present specification, the above-described thermosetting-type sheet (S1) and the above-mentioned thermosetting-type sheet (S2) may be collectively referred to as "the thermosetting sheet of the present invention", and the heat may be sometimes used. The solid adhesive layer (L1) and the above-described thermosetting adhesive layer (L2) are collectively referred to as "the thermosetting adhesive layer of the present invention". In addition, "thermoset type sheet" also includes the meaning of "heat-set type". That is, the thermosetting adhesive sheet of the present invention may be a thermosetting adhesive tape having a belt-like form.

In the present specification, the phrase "containing the acrylic polymer (X) and the acrylic polymer (Y) as a main component" means all the nonvolatile components of the thermosetting adhesive composition (M2) (100 weight) The total amount (total content) of the content of the acrylic polymer (X) and the content of the acrylic polymer (Y) in %) is 50% by weight or more.

The thermosetting adhesive layer (L1) is not particularly limited, and is preferably contained. a thermosetting adhesive layer formed of a thermosetting adhesive composition containing a thermosetting resin (Z) as a main component of the acrylic polymer (X) and the acrylic polymer (Y) (ie, the above-described thermosetting type) Agent layer (L2)). Therefore, the above-described thermosetting type succeeding sheet (S1) is preferably a thermosetting type succeeding sheet (S1) and a thermosetting type sheet (S2).

[Thermosetting adhesive composition (M1)]

The thermosetting adhesive composition (M1) is not particularly limited, and for example, it preferably contains an acrylic polymer, a rubber-based polymer, a vinyl alkane-based polymer, a polyoxymethylene-based polymer, or a polyester-based polymerization. A polymer such as a polyamine polymer, a urethane polymer, a fluorine polymer or an epoxy polymer is an essential component. The above polymer is more preferably an acrylic polymer. The thermosetting adhesive composition (M1) is not particularly limited, and preferably further contains a thermosetting resin. Further, in addition to the above polymer and 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 or additive) may be used alone or in combination of two or more.

The thermosetting adhesive composition (M1) is preferably a thermosetting adhesive composition containing an acrylic polymer as a main component and containing a thermosetting resin, more preferably a thermosetting adhesive composition (M2). In addition, the phrase "containing an acrylic polymer as a main component" means that the content of the acrylic polymer in all the nonvolatile components (100% by weight) of the thermosetting adhesive composition (M1) is 50% by weight or more. .

The acrylic polymer is not particularly limited, and it is preferred to form an alkyl (meth)acrylate having a linear or branched alkyl group as an essential monomer. An acrylic polymer composed (or formed) of a branch. The alkyl (meth)acrylate is not particularly limited, and is preferably, for example, an alkyl (meth)acrylate having 1 to 14 carbon atoms, more preferably an alkyl (meth)acrylate having 1 to 12 carbon atoms. Base ester. Among them, the (meth)acrylic acid alkyl ester exemplified as the following (meth)acrylic acid alkyl ester (a1) is exemplified as the following (meth)acrylic acid alkyl ester (a2) (A) Alkyl acrylate. The alkyl (meth)acrylate may be used singly or in combination of two or more.

The content (content ratio) of the alkyl (meth)acrylate in the monomer component constituting the acrylic polymer is not particularly limited, and is the total amount (100% by weight) of the monomer component constituting the acrylic polymer. 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.

The monomer component constituting the acrylic polymer is not particularly limited, and preferably contains a cyano group-containing monomer or a carboxyl group-containing monomer, and more preferably contains a cyano group-containing monomer and contains a carboxyl group. The monomer is more preferably a monomer component exemplified as the monomer component exemplified as the cyano group-containing monomer (b1) described below and which is carboxy group-containing monomer (c1). The above monomer components may be used singly or in combination of two or more. By using a monomer containing a cyano group, the strength (block strength) of the thermosetting adhesive layer (L1) can be improved, and heat resistance after moist heat can be improved, which is preferable. Further, it is preferable to prevent the thermosetting adhesive layer (L1) from becoming brittle. By using the above-mentioned monomer having a carboxyl group, the heat resistance and adhesion of the thermosetting back sheet (S1) after moist heat can be improved, which is preferable.

The content of the above cyano group-containing monomer is not particularly limited, and is relative to the constitution. The total amount of the monomer component (100% by weight) of the acrylic polymer is preferably 20 to 49.5% by weight, more preferably 24 to 40% by weight, still more preferably 26 to 35% by weight. When the content is 20% by weight or more, the heat resistance of the thermosetting sheet (S1) is further improved after moist heat, which is preferable. 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, and is preferably from 0.5 to 10% by weight, more preferably from 1 to 8% by weight, based on the total amount of the monomer component (100% by weight) constituting the acrylic polymer. More preferably, it is 2-6 weight%. When the content is 0.5% by weight or more, the heat-resistant subsequent sheet (S1) is improved in heat resistance and adhesion after moist heat, which is preferable. On the other hand, when 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, and examples thereof include a (meth)acrylic acid alkyl ester having a linear or branched alkyl group having 15 to 20 carbon atoms, and the following non-aromatic content. The alkyl (meth)acrylate of the ring, the following (meth)acrylic acid alkyl ester containing an aromatic ring, the following epoxy group-containing acrylic monomer, the following vinyl ester monomer, and The styrene monomer, the following hydroxyl group-containing monomer, the following (meth)acrylic alkoxyalkyl ester monomer, and the following (meth)acrylic acid aminoalkyl ester monomer; (N-substituted) guanamine-based monomer, the following olefin-based monomer, the following vinyl ether-based monomer, the following polyfunctional monomer, and the like.

The above acrylic polymer can be obtained by a known or customary polymerization method (example) It is prepared by 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 which are used in the polymerization of the acrylic polymer are not particularly limited, and may be appropriately selected from known or customary ones. More specifically, the polymerization initiators exemplified as the polymerization initiator, the emulsifier, and the chain transfer agent used in the polymerization of the acrylic polymer (X) described below are exemplified. A starter or a peroxide-based polymerization initiator, etc.), an emulsifier (an anionic emulsifier or a nonionic emulsifier, etc.), and a chain transfer agent. The polymerization initiator, the emulsifier, and the chain transfer agent may be used alone or in combination of two or more. The amount of the polymerization initiator to be used is not particularly limited, and can be appropriately selected from the range of the usual usage amount.

Further, in the solution polymerization, various usual solvents can be used. The solvent is not particularly limited, and examples thereof 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; and cyclohexane. An alicyclic hydrocarbon such as methylcyclohexane; an organic solvent such as a ketone such as methyl ethyl ketone or methyl isobutyl ketone. These solvents may be used singly or in combination of two or more.

The weight average molecular weight (Mw) of the acrylic polymer is not particularly limited, and the coating property of the thermosetting adhesive composition (M1) is improved, productivity is improved, or the thermosetting adhesive layer is improved (L1). The viewpoint of the strength and heat resistance after moist heat is preferably from 500,000 to 4,000,000, more preferably from 800,000 to 3.5 million, and further preferably from 1,000,000 to 3.2 million. The weight average molecular weight of the above acrylic polymer is limited by the type of polymerization initiator or chain transfer agent or In addition to the amount of use, temperature or time of polymerization, it is also possible to control by monomer concentration, monomer droplet acceleration, and the like.

The above weight average molecular weight can be measured by gel permeation chromatography (GPC, Gel Permeation Chromatography). More specifically, for example, it can be determined by the following measurement method of <GPC> in the same manner as the weight average molecular weight of the following acrylic polymer (X).

The above thermosetting resin is used to impart thermosetting properties. The thermosetting resin is not particularly limited, and a thermosetting resin which is cured by heating and which functions as a conventionally used thermosetting resin can be used. Among them, a thermosetting resin exemplified as the thermosetting resin (Z) described below is preferable, and an etherified phenol resin is more preferable. These thermosetting resins may be used singly or in combination of two or more.

The content of the acrylic polymer in the thermosetting adhesive composition (M1) is not particularly limited, and it is a thermosetting adhesive composition (M1) from the viewpoint of heat resistance after heat and heat and adhesion. All of the nonvolatile components (100% by weight) are 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, and is preferably 1 to 40 parts by weight based on 100 parts by weight of the acrylic polymer. More preferably, it is 5-20 parts by weight, and further preferably 10-15 parts by weight. By setting the content of the thermosetting resin to 1 part by weight or more, the thermosetting adhesive layer (L1) is improved in thermosetting property, which is preferable. Further, by setting it to 40 parts by weight or less, it is preferable that the adhesive does not bleed out at the time of high-temperature pressing.

The above thermosetting adhesive composition (M1) preferably contains a solvent. As above The solvent is not particularly limited, and examples thereof include esters such as ethyl acetate and n-butyl acetate; alcohols such as methanol, ethanol, butanol, propanol, and isopropanol; and aromatic hydrocarbons such as toluene and benzene; An aliphatic hydrocarbon such as n-hexane or n-heptane; an alicyclic hydrocarbon such as cyclohexane or methylcyclohexane; or an organic solvent such as a ketone such as methyl ethyl ketone or methyl isobutyl ketone. These solvents may be used singly or in combination of two or more. Furthermore, the above solvent also means the meaning of a dispersion medium.

In the above-mentioned thermosetting adhesive composition (M1), in addition to the above acrylic polymer and the above-mentioned thermosetting resin, an anti-aging agent may be contained as needed within the scope of the characteristics of the present invention, and the following thermosetting type may be followed. Filler (filler), colorant (pigment or dye, etc.) used in the agent composition (M2), ultraviolet absorber, antioxidant, crosslinking agent, adhesion-imparting agent, plasticizer, softener, surfactant Known additives such as antistatic agents. These additives may be used singly or in combination of two or more.

[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) may contain a solvent (solvent and/or dispersion medium) in addition to the acrylic polymer (X), the acrylic polymer (Y), and the thermosetting resin (Z). Contains additives. Each of the above components (acrylic polymer (X), acrylic polymer (Y), thermosetting resin (Z), solvent or additive) may be used alone or in combination of two or more.

(acrylic polymer (X))

The acrylic polymer (X) is composed (or formed) of an alkyl (meth)acrylate (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 above-mentioned "alkyl (meth)acrylate (a1) having a linear or branched alkyl group having 1 to 3 carbon atoms is sometimes referred to as "(meth)acrylic acid". C _1-3 alkyl ester (a1) or simply "alkyl (meth) acrylate (a1)". Further, "(meth)acrylic acid" means "acrylic acid" and/or "methacrylic acid" (one or both of "acrylic acid" and "methacrylic acid"), and the same applies hereinafter.

The acrylic polymer (X) preferably has a C _1-3 alkyl (meth) acrylate (a1), a cyano group-containing monomer (b1), and a carboxyl group-containing monomer (c1) as essential sheets. An acrylic polymer composed of a body component. The content of the C _1-3 alkyl (meth)acrylate (a1) in the total amount of the monomer components (100% by weight) constituting the acrylic polymer (X) is preferably 50 to 75% by weight. The content of the cyano group-containing monomer (b1) is preferably from 20 to 49.5% by weight, and the carboxyl group-containing monomer (c1) is preferably from 0.5 to 10% by weight. Further, as the monomer component constituting the acrylic polymer (X), the above-mentioned (meth)acrylic acid C _1-3 alkyl ester (a1), the cyano group-containing monomer (b1), and the carboxyl group-containing one may be used. A monomer component (other monomer component) other than the monomer (c1). The above acrylic polymer (X) may be used singly or in combination of two or more.

The acrylic polymer (X) is preferably an acrylic polymer (acrylic elastomer) which exhibits rubber elasticity (elastomerity).

The C _1-3 alkyl (meth)acrylate (a1) is not particularly limited, and examples thereof include methyl (meth)acrylate, ethyl (meth)acrylate, and propyl (meth)acrylate. , (meth) acrylate. Among them, ethyl acrylate is preferred. The C _1-3 alkyl (meth)acrylate (a1) may be used singly or in combination of two or more.

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

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. Among them, acrylonitrile is preferred. The cyano group-containing monomer (b1) may be used singly or in combination of two or more. By using the cyano group-containing monomer (b1), the strength (block strength) of the thermosetting adhesive layer (L2) can be improved, and the heat resistance after moist heat can be improved, which is preferable. Further, it is preferable to prevent the thermosetting adhesive layer (L2) from becoming brittle.

The content of the cyano group-containing monomer (b1) constituting the monomer component of the acrylic polymer (X) is preferably the total amount (100% by weight) of the monomer component constituting the acrylic polymer (X). It is 20 to 49.5% by weight, more preferably 24 to 40% by weight, still more preferably 26 to 35% by weight. When the content is 20% by weight or more, the heat resistance of the thermosetting sheet (S2) is further improved after moist heat, which is preferable. On the other hand, when 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, and cis. Butenedioic acid, fumaric acid, crotonic acid, and the like. Further, the acid anhydride of the carboxyl group-containing monomer (for example, an acid anhydride group-containing monomer such as maleic anhydride or itaconic anhydride) is also included in the monomer having a carboxyl group. Among them, acrylic acid, methacrylic acid, itaconic acid, and preferably acrylic acid are preferable. The carboxyl group-containing monomer (c1) may be used singly or in combination of two or more. By using the carboxyl group-containing monomer (c1), heat resistance and adhesion of the thermosetting sheet (S2) after moist heat can be improved, which is preferable.

The content of the carboxyl group-containing monomer (c1) in the monomer component constituting the acrylic polymer (X) is preferably the total amount (100% by weight) of the monomer component constituting the acrylic polymer (X). It is 0.5 to 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 of the thermosetting sheet (S2) after heat-heating and the adhesion are improved, which is preferable. On the other hand, when the content exceeds 10% by weight, the flexibility of the thermosetting adhesive layer may be lowered.

The monomer component constituting the acrylic polymer (X), in addition to the above (meth)acrylic acid C _1-3 alkyl ester (a1), a cyano group-containing monomer (b1), and a carboxyl group-containing monomer (c1) Other monomer components (copolymerizable monomers) may also be used. The above other monomer components (copolymerizable monomers) may be used singly or in combination of two or more. Examples of the other monomer component (copolymerizable monomer) include n-butyl (meth)acrylate, isobutyl (meth)acrylate, and second butyl (meth)acrylate, and (methyl). Tert-butyl acrylate, amyl (meth)acrylate, isoamyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate, octyl (meth)acrylate, (methyl) ) 2-ethylhexyl acrylate, isooctyl (meth) acrylate, decyl (meth) acrylate, isodecyl (meth) acrylate, decyl (meth) acrylate, isophthalic acid (meth) acrylate Ester, undecyl (meth)acrylate, dodecyl (meth)acrylate, tridecyl (meth)acrylate, tetradecyl (meth)acrylate, pentadecyl (meth)acrylate Esters, cetyl (meth) acrylate, heptadecyl (meth) acrylate, octadecyl (meth) acrylate, pentadecanyl (meth) acrylate, eicosyl (meth) acrylate An alkyl (meth)acrylate having a linear or branched alkyl group having 4 to 20 carbon atoms (C _4-20 alkyl (meth)acrylate); a cycloalkyl (meth)acrylate; Ester [cyclohexyl (meth) acrylate] or (a) ) Acrylate (meth)acrylate containing a non-aromatic ring such as an ester; aryl (meth)acrylate [phenyl (meth)acrylate], aryloxyalkyl (meth)acrylate [(methyl) (phenoxyethyl acrylate, etc.), arylalkyl (meth) acrylate [benzyl methacrylate], etc. (meth) acrylate containing an aromatic ring; (meth) acrylate shrinkage An epoxy group-containing acrylic monomer such as glyceride or methyl glycidyl (meth)acrylate; a vinyl ester monomer such as vinyl acetate or vinyl propionate; and benzene such as styrene or α-methylstyrene; a vinyl monomer; a hydroxyl group-containing monomer such as hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate or hydroxybutyl (meth)acrylate; methoxyethyl (meth)acrylate; (meth)acrylic acid alkoxyalkyl ester monomer such as ethoxyethyl acrylate; aminoethyl (meth) acrylate, N, N-dimethylamino (meth) acrylate (meth)acrylic acid aminoalkyl ester monomer such as ester, tert-butylaminoethyl (meth)acrylate; (meth) acrylamide, N, N-dimethyl (meth) propylene Indoleamine, N-butyl (methyl (N-substituted) guanamine monomer such as acrylamide or N-hydroxy(methyl) acrylamide; olefin monomer such as ethylene, propylene, isoprene or butadiene; methyl vinyl ether, etc. A vinyl ether monomer or the like.

Further, as the other monomer component (copolymerizable monomer), hexanediol di(meth)acrylate, butanediol di(meth)acrylate, or (poly)ethylene glycol di(a) may be used. Acrylate, (poly)propylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, pentaerythritol di(meth)acrylate, glycerol di(meth)acrylate, trishydroxyl A polyfunctional monomer such as propane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, dipentaerythritol hexa(meth)acrylate or divinylbenzene.

In other words, the acrylic polymer (X) preferably contains at least a structural unit derived from a C _1-3 alkyl (meth)acrylate (a1), a structural unit derived from a monomer (b1) containing a cyano group, And an acrylic polymer derived from a structural unit of a monomer (c1) having a carboxyl group. Each of the structural units may be one type or two or more types. The content of the structural unit derived from the C _1-3 alkyl (meth)acrylate (a1) in the acrylic polymer (X) (100% by weight) is preferably 50% by weight or more, more preferably 50 to 75. The weight % is further preferably 55 to 75% by weight, most preferably 60 to 72% by weight. The content of the structural unit derived from the cyano group-containing monomer (b1) is preferably from 20 to 49.5% by weight, more preferably from 24 to 40% by weight, still more preferably from 26 to 35% by weight. The content of the structural unit derived from the carboxyl group-containing monomer (c1) is preferably from 0.5 to 10% by weight, more preferably from 1 to 8% by weight, still more preferably from 2 to 6% by weight.

The above acrylic polymer (X) can be produced 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, etc.).

Furthermore, the polymerization of the acrylic polymer (X) is required as needed. The starting agent, the emulsifier, the chain transfer agent and the like are not particularly limited, and can be appropriately selected from known or used. More specifically, examples of the polymerization initiator include 2,2'-azobisisobutyronitrile and 2,2'-azobis(4-methoxy-2,4-dimethyl Valeronitrile), 2,2'-azobis(2,4-dimethylvaleronitrile), 2,2'-azobis(2-methylbutyronitrile), 1,1'-azobis ( Cyclohexane-1-carbonitrile), 2,2'-azobis(2,4,4-trimethylpentane), 2,2'-azobis(2-methylpropionic acid) Azo-based polymerization initiator such as ester, 2,2'-azobis{2-[1-(2-hydroxyethyl)-2-imidazolin-2-yl]propane} dihydrochloride; peroxidation Benzoquinone, tert-butyl hydroperoxide, di-tert-butyl peroxide, tert-butyl peroxybenzoate, dicumyl peroxide, 1,1-bis(t-butylperoxy a peroxide-based polymerization initiator such as -3,3,5-trimethylcyclohexane or 1,1-bis(t-butylperoxy)cyclododecane. These polymerization initiators may be used singly or in combination of two or more. The amount of the polymerization initiator to be used is not particularly limited, and can be appropriately selected from the range of the usual usage amount.

Examples of the chain transfer agent include 1-dodecanethiol, third lauryl mercaptan, second lauryl mercaptan, 2-mercaptoethanol, glycidyl mercaptan, mercaptoacetic acid, and thioglycolic acid. 2-ethylhexyl ester, 2,3-dimercapto-1-propanol, α-methylstyrene dimer, and the like. Examples of the emulsifier include sodium lauryl sulfate, ammonium lauryl sulfate, sodium dodecylbenzenesulfonate, sodium polyoxyethylene alkyl ether sulfate, ammonium polyoxyethylene alkyl phenyl ether sulfate, and polyoxyethylene alkyl group. An anionic emulsifier such as sodium phenyl ether sulfate; a nonionic emulsifier such as polyoxyethylene alkyl ether or polyoxyethylene alkyl phenyl ether. The chain transfer agent and the above emulsifier may be used alone or in combination of two or more.

Further, in the solution polymerization, various usual solvents can be used. As above 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; and cyclohexane and methylcyclohexane. An alicyclic hydrocarbon; an organic solvent such as a ketone such as methyl ethyl ketone or methyl isobutyl ketone. These solvents may be used singly or in combination of two or more.

The weight average molecular weight (Mw) of the acrylic polymer (X) is not particularly limited, and the coating property of the thermosetting adhesive composition (M2) is improved, the productivity is improved, or the thermosetting adhesive is improved. The viewpoint of the strength of the layer (L2) and the heat resistance after moist heat is preferably from 500,000 to 4,000,000, more preferably from 800,000 to 3.5 million, and still more preferably from 1,000,000 to 3.2 million. The weight average molecular weight of the acrylic polymer (X) is controlled by the type of the polymerization initiator or the chain transfer agent or the amount thereof used, the temperature or time during polymerization, and the monomer concentration and the monomer droplet. Acceleration, etc. are controlled.

The above weight average molecular weight can be measured by gel permeation chromatography (GPC). More specifically, it can be determined, for example, by measurement using the following <GPC measurement method>.

<Measurement method of GPC> (Preparation of samples)

The acrylic polymer to be measured was dissolved in a solution, and a 0.1% THF (Tetrahydrofuran, tetrahydrofuran) solution of the acrylic polymer was prepared and allowed to stand for 1 day, and then filtered using a 0.45 μm membrane filter to obtain The filtrate was used as a sample, and GPC measurement was performed under the following measurement conditions.

(measurement conditions)

GPC device: HLC-8320GPC (manufactured by Tosoh Co., Ltd.)

Pipe column: TSKgel GMH-H(S) (manufactured by Tosoh Corporation)

Column size: 7.8 mm I.D.×300 mm

Column temperature: 40 ° C

Lysate: 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 an alkyl (meth)acrylate (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-mentioned "alkyl (meth)acrylate (a2) having a linear or branched alkyl group having 4 to 12 carbon atoms" may be referred to as "(meth)acrylic acid. C _4-12 alkyl ester (a2)" or simply "alkyl (meth) acrylate (a2)".

The acrylic polymer (Y) preferably has a C _4-12 alkyl (meth)acrylate (a2), a cyano group-containing monomer (b2), and a carboxyl group-containing monomer (c2) as essential sheets. An acrylic polymer composed of a body component. The content of the C _4-12 alkyl (meth)acrylate (a2) in the total amount of the monomer components (100% by weight) constituting the acrylic polymer (Y) is preferably 50 to 75% by weight. The content of the cyano group-containing monomer (b2) is preferably from 20 to 49.5% by weight, and the carboxyl group-containing monomer (c2) is preferably from 0.5 to 10% by weight. Further, as the monomer component constituting the acrylic polymer (Y), the above-mentioned (meth)acrylic acid C _4-12 alkyl ester (a2), a cyano group-containing monomer (b2), and a carboxyl group-containing one may be used. A monomer component (other monomer component) other than the monomer (c2). The above acrylic polymer (Y) may be used singly or in combination of two or more.

The acrylic polymer (Y) is preferably an acrylic polymer (acrylic elastomer) which exhibits rubber elasticity (elastomerity).

The C _4-12 alkyl (meth)acrylate (a2) is not particularly limited, and examples thereof include n-butyl (meth)acrylate, isobutyl (meth)acrylate, and (meth)acrylic acid. Second butyl ester, tert-butyl (meth)acrylate, amyl (meth)acrylate, isoamyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate, (A) Octyl acrylate, 2-ethylhexyl (meth)acrylate, isooctyl (meth)acrylate, decyl (meth)acrylate, isodecyl (meth)acrylate, bismuth (meth)acrylate An ester, isodecyl (meth)acrylate, undecyl (meth)acrylate, dodecyl (meth)acrylate, and the like. Among them, an alkyl (meth)acrylate (C _4-8 alkyl (meth)acrylate) having a linear or branched alkyl group having 4 to 8 carbon atoms is preferred, and acrylic acid is preferred. Butyl ester. The above-mentioned (meth)acrylic acid C _4-12 alkyl ester (a2) may be used alone or in combination of two or more.

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

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. Among them, acrylonitrile is preferred. The cyano group-containing monomer (b2) may be used singly or in combination of two or more. By using the cyano group-containing monomer (b2), the strength (block strength) of the thermosetting adhesive layer (L2) can be improved, and heat resistance after moist heat can be improved, which is preferable. Further, it is preferable to prevent the thermosetting adhesive layer (L2) from becoming brittle.

The content of the cyano group-containing monomer (b2) constituting the monomer component of the acrylic polymer (Y) is preferably the total amount (100% by weight) of the monomer component constituting the acrylic polymer (Y). It is 20 to 49.5% by weight, more preferably 24 to 40% by weight, still more preferably 26 to 35% by weight. When the content is 20% by weight or more, the heat-resistant adhesive sheet (S2) is preferably heat-resistant after moist heat, which is preferable. On the other hand, when 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 butene. Acid, etc. Further, the acid anhydride of the carboxyl group-containing monomer (for example, an acid anhydride group-containing monomer such as maleic anhydride or itaconic anhydride) is also included in the monomer having a carboxyl group. Among them, acrylic acid, methacrylic acid, itaconic acid, and preferably acrylic acid are preferable. The carboxyl group-containing monomer (c2) may be used singly or in combination of two or more. By using The carboxyl group-containing monomer (c2) is preferred because it improves the heat resistance and adhesion of the thermosetting sheet (S2) after moist heat.

The content of the carboxyl group-containing monomer (c2) in the monomer component constituting the acrylic polymer (Y) is preferably the total amount (100% by weight) of the monomer component constituting the acrylic polymer (Y). It is 0.5 to 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 of the thermosetting sheet (S2) after heat-heating and the adhesion are improved, which is preferable. On the other hand, when the content exceeds 10% by weight, the flexibility of the thermosetting adhesive layer may be lowered.

The monomer component constituting the acrylic polymer (Y) is the C _4-12 alkyl (meth)acrylate (a2), the cyano group-containing monomer (b2), and the carboxyl group-containing monomer (c2). Other monomer components (copolymerizable monomers) may also be used. The above other monomer components (copolymerizable monomers) may be used singly or in combination of two or more. Examples of the other monomer component (copolymerizable monomer) include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, and isopropyl (meth)acrylate. An alkyl (meth)acrylate having a linear or branched alkyl group having 1 to 3 carbon atoms (C _1-3 alkyl (meth)acrylate); tridecyl (meth)acrylate , tetradecyl (meth)acrylate, pentadecyl (meth)acrylate, cetyl (meth)acrylate, heptadecyl (meth)acrylate, octadecyl (meth)acrylate And a (meth)acrylic acid alkyl ester having a linear or branched alkyl group having 13 to 20 carbon atoms, such as hexadecyl (meth)acrylate or eicosyl (meth)acrylate ((methyl) ) C _13-20 alkyl acrylate) and the like.

Further, as the other monomer component (copolymerizable monomer), A non-aromatic ring-containing (meth) acrylate exemplified as the other monomer component (copolymerizable monomer) constituting the monomer component of the acrylic polymer (X); containing an aromatic ring (meth) acrylate; epoxy group-containing acrylic monomer; vinyl ester monomer; styrene monomer; hydroxyl group-containing monomer; (meth)acrylic acid alkoxyalkyl ester monomer; (meth)acrylic acid aminoalkyl ester monomer; (N-substituted) guanamine monomer; olefin monomer; vinyl ether monomer; polyfunctional monomer.

In other words, the acrylic polymer (Y) preferably contains at least a structural unit derived from a C _4-12 alkyl (meth)acrylate (a2), a structural unit derived from a monomer (b2) containing a cyano group, And an acrylic polymer derived from a structural unit of a monomer (c2) having a carboxyl group. Each of the structural units may be one type or two or more types. The content of the structural unit derived from the C _4-12 alkyl (meth)acrylate (a2) in the acrylic polymer (Y) (100% by weight) is preferably 50% by weight or more, more preferably 50 to 75%. The weight % is further preferably 55 to 75% by weight, most preferably 60 to 72% by weight. The content of the structural unit derived from the cyano group-containing monomer (b2) is preferably from 20 to 49.5% by weight, more preferably from 24 to 40% by weight, still more preferably from 26 to 35% by weight. The content of the structural unit derived from the carboxyl group-containing monomer (c2) is preferably from 0.5 to 10% by weight, more preferably from 1 to 8% by weight, still more preferably from 2 to 6% by weight.

The above acrylic polymer (Y) can be produced 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, etc.).

Further, the polymerization initiator, the emulsifier, the chain transfer agent, and the like to be used in the polymerization of the acrylic polymer (Y) are not particularly limited, and can be known from the above. Use it appropriately or among the idiots. More specifically, a polymerization initiator (azo-based polymerization initiator) exemplified as a polymerization initiator, an emulsifier, and a chain transfer agent used in the polymerization of the acrylic polymer (X), respectively, may be mentioned. Or a peroxide-based polymerization initiator, etc.), an emulsifier (anionic emulsifier or a nonionic emulsifier, etc.), and a chain transfer agent. The polymerization initiator, the emulsifier, and the chain transfer agent may be used alone or in combination of two or more. The amount of the polymerization initiator to be used is not particularly limited, and can be appropriately selected from the range of the usual usage amount.

Further, in the solution polymerization, various usual 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; and cyclohexane and methylcyclohexane. An alicyclic hydrocarbon; an organic solvent such as a ketone such as methyl ethyl ketone or methyl isobutyl ketone. These solvents may be used singly or in combination of two or more.

The weight average molecular weight (Mw) of the acrylic polymer (Y) is not particularly limited, and the coatability of the thermosetting adhesive composition (M2) is improved, the productivity is improved, or the thermosetting adhesive is improved. The viewpoint of the strength of the layer (L2) and the heat resistance after moist heat is preferably from 500,000 to 2,000,000, more preferably from 600,000 to 1.8 million, and further preferably from 600,000 to 1,500,000, and more preferably 80. Ten thousand to 1.2 million. The weight average molecular weight of the acrylic polymer (Y) can be controlled by the type of the polymerization initiator or the chain transfer agent or the amount thereof used, the temperature or time of polymerization, or by the monomer concentration or monomer drop. Acceleration, etc. are controlled.

The above weight average molecular weight can be carried out by gel permeation chromatography (GPC) Determination. More specifically, it can be determined, for example, by measuring the above-mentioned <GPC measurement method> in the same manner as the weight average molecular weight of the acrylic polymer (X).

(thermosetting resin (Z))

The thermosetting resin (Z) is not particularly limited, and a thermosetting resin which is cured by heating and which functions as a conventionally used thermosetting resin can be used. The thermosetting resin (Z) is used to impart thermosetting properties. Examples of the thermosetting resin (Z) include a phenol resin, an amine resin, an unsaturated polyester resin, an epoxy resin, a polyurethane resin, a polyoxyxylene resin, and a thermosetting polyimide resin. Among them, the thermosetting resin (Z) is preferably a phenol resin and/or an epoxy resin, more preferably a phenol resin. These thermosetting resins (Z) may be used singly or in combination of two or more.

The phenol resin is not particularly limited, and a conventionally known phenol resin can be used. For example, a novolac type phenol resin, a novolac type phenol resin, or various modified phenol resins (for example, an alkyl-modified phenol resin), etc. are mentioned. These phenol resins may be used singly or in combination of two or more. As the above 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 an etherified phenol resin is used as the thermosetting resin (Z), the effect of improving the heat resistance after the heat and the heat is particularly excellent.

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

Further, the etherified phenol resin is preferably a phenol resin in which a part of a methylol group of the phenol resin is etherified with an alkyl group, that is, an alkyl etherified phenol resin. As Examples of the above alkyl group include a methyl group, an ethyl group, a propyl group, an isopropyl group, a n-butyl group, an isobutyl group, a second butyl group, a tert-butyl group, a pentyl group, an isopentyl group, a hexyl group, and a heptyl group. , octyl, 2-ethylhexyl, isooctyl, decyl, isodecyl, decyl, isodecyl, undecyl, dodecyl, tridecyl, tetradecyl, fifteen An alkyl group having 1 to 20 carbon atoms such as an alkyl group, a hexadecyl group, a heptadecyl group, an octadecyl group, a nonadecyl group or an eicosyl group Among them, a methyl group, an ethyl group, and an n-butyl group are preferred, and an n-butyl group is more preferred.

In the etherified phenol resin, the phenol resin to be a skeleton is not particularly limited. Examples of the etherified phenol resin include an etherified novolac type phenol resin, an etherified novolak type phenol resin, and an etherified cresol resin. Among them, an etherified cresol resin is preferred, and a butylated ether cresol resin (a cresol resin in which one part of the methylol group is butyl etherified) is more preferred. These etherified phenol resins may be used singly or in combination of two or more.

The ratio of the etherified methylol group in the above etherified phenol resin, for example, relative to the total of the etherified methylol group and the unetherified methylol group (100 mol%), etherified The proportion of the hydroxymethyl group is preferably 50 mol% or more (50 mol% or more and less than 100 mol%), more preferably 70 mol% or more. If the proportion of the etherified methylol group is less than 50 mol%, the reaction of the etherified phenol resin at normal temperature may be promoted, or the reactivity at the time of heat curing may be lowered.

As the etherified phenol resin, a commercially available etherified phenol resin can be used. For example, the product name "SUMILITE RESIN PR-55317" (butylated cresy resin manufactured by SUMITOMO BAKELITE Co., Ltd., etherified hydroxyl group) can be used. Methyl ratio: 90% by mole), trade name "CKS-3898" (butyl ether cresol resin manufactured by Showa Denko Co., Ltd.).

(content of the component contained in the thermosetting adhesive composition (M2))

The total amount (total content) of the content of the acrylic polymer (X) in the thermosetting adhesive composition (M2) and the content of the acrylic polymer (Y) is both heat resistance and adhesion after moist heat From the viewpoint of the non-volatile content (100% by weight) of the thermosetting adhesive composition (M2), it is 50% by weight or more, preferably 70 to 99% by weight, more preferably 80 to 95% by weight. %, further preferably from 85 to 95% by weight.

In the above-mentioned thermosetting type adhesive composition (M2), the content (content ratio, blending ratio) of the acrylic polymer (Y) is preferably from 1 to 100 with respect to 100 parts by weight of the acrylic polymer (X). The parts by weight are more preferably 2 to 45 parts by weight, still more preferably 4 to 25 parts by weight, most preferably 5 to 20 parts by weight. When the content of the acrylic polymer (Y) is 1 part by weight or more, the adhesion of the thermosetting sheet (S2) is improved, and the heat resistance after moist heat is also improved, which is preferable. In addition, when the amount is 100 parts by weight or less, the strength of the thermosetting adhesive layer (L2) is increased, and the heat-resistant adhesive sheet (S2) is improved in heat resistance after moist heat, which is preferable.

In the above-mentioned thermosetting adhesive composition (M2), the content (content ratio, blending ratio) of the thermosetting resin (Z) is preferably from 1 to 40 parts by weight based on 100 parts by weight of the acrylic polymer (X). More preferably, it is 5-20 parts by weight, and further preferably 10-15 parts by weight. By setting the content of the thermosetting resin (Z) to 1 part by weight or more, the thermosetting adhesive layer (L2) is improved in thermosetting property, which is preferable. Moreover, it is set to 40 parts by weight or less at a high temperature. The adhesive does not bleed out when pressed, and is therefore preferred. It is particularly preferable that the content of the etherified phenol resin is in the above range with respect to 100 parts by weight of the acrylic polymer (X).

(solvent, additive)

The above 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; and n-hexane. An aliphatic hydrocarbon such as heptane; an alicyclic hydrocarbon such as cyclohexane or methylcyclohexane; or an organic solvent such as a ketone such as methyl ethyl ketone or methyl isobutyl ketone. These solvents may be used singly or in combination of two or more. Furthermore, the above solvent also means 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 optionally be inferior to the characteristics of the present invention. Contains: anti-aging agent, filler (filler), colorant (pigment or dye, etc.), UV absorber, antioxidant, crosslinker, adhesion promoter, plasticizer, softener, surfactant, antistatic A known additive such as a agent. These additives may be used singly or in combination of two or more.

The filler (filler) is not particularly limited, and a conventionally known organic filler or inorganic filler can be used. Among them, from the viewpoint of improving the strength of the thermosetting adhesive layer (L2) and further improving the heat resistance of the thermosetting adhesive sheet (S2) after moist heat, a cerium oxide filler or a copper filler is preferable. These fillers may be used alone or in combination of two or more.

The thermosetting adhesive composition (M2) preferably contains the following components as a main component: a C _1-3 alkyl (meth)acrylate (a1), a cyano group-containing monomer (b1), and a carboxyl group. The monomer (c1) is an essential acrylic acid polymer (X); and the (meth)acrylic acid C _4-12 alkyl ester (a2) and the cyano group-containing monomer (b2) And an acrylic polymer (Y) comprising a carboxyl group-containing monomer (c2) as an essential monomer component. It is preferred to further contain an etherified phenol resin.

The above-mentioned thermosetting adhesive composition (M2) can be, for example, an acrylic polymer (X), an acrylic polymer (Y), and a thermosetting resin (Z) (especially an etherified phenol resin), and optionally Various additives and the like are prepared by mixing. Further, the acrylic polymer (X), the acrylic polymer (Y), and the thermosetting resin (Z) may be dissolved in a solvent to be in a solution state or dispersed in a dispersion medium. It is used in the state of a dispersion to prepare a thermosetting adhesive composition (M2).

[The thermosetting adhesive layer (L1, L2) of the present invention]

The thermosetting adhesive layer of the present invention is a thermosetting adhesive layer formed of a thermosetting adhesive composition (M1) in the case of a thermosetting adhesive layer (L1), and is thermosetting. In the case of the subsequent layer (L2), it is a thermosetting type of adhesive layer formed of the thermosetting adhesive composition (M2). The thermosetting adhesive layer of the present invention may have any form of a single layer or a plurality of 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, still more preferably 20 to 40 μm. It is preferable that the thickness is 5 μm or more and the force is increased. On the other hand, in the case where the above thickness exceeds 100 μm, there is a case where the adhesive oozes at the time of high temperature pressing.

The thermosetting adhesive layer (L1) has at least one glass transition point in a temperature range of -50 ° C or more and 10 ° C or less and a temperature range of 20 ° C or more and 100 ° C or less. The thermosetting adhesive layer (L1) may also have a glass transition point outside the above temperature range within the range in which the effects of the present invention are not impaired. Further, the glass transition point of the thermosetting adhesive layer (L1) at -50 ° C to 10 ° C may be referred to as "Tg _A ", and the thermosetting adhesive layer (L1 ) may be at 20 ° C or higher. The glass transition point which is below 100 ° C is called "Tg _B ". Tg _A and Tg _B may each be only one or two or more.

The thermosetting adhesive layer (L1) has the above Tg _A at -50 ° C or more and 10 ° C or less, preferably -30 ° C or more and 10 ° C or less, more preferably -10 ° C or more and 10 ° C or less. It is preferred because it has the above Tg _A at -50 ° C or higher and does not lower the heat resistance after moist heat. On the other hand, since the above Tg _{A is present} at 10 ° C or lower, the force is increased, which is preferable.

The thermosetting adhesive layer (L1) has the above Tg _B at 20 ° C or more and 100 ° C or less, preferably 20 ° C or more and 30 ° C or less, more preferably 20 ° C or more and 40 ° C or less. Since the above Tg _{B is} contained at 20 ° C or higher, the heat resistance after moist heat is improved, which is preferable. On the other hand, since it has the above Tg _B at 100 ° C or less, it is preferable to prevent it from becoming too hard and to reduce the adhesion.

In the present specification, the glass transition point can be measured, for example, in accordance with JIS K 7121. Specifically, the measurement is carried out by the following <Method for Measuring Glass Transition Point>.

<Method for Measuring Glass Transfer Point>

A thermosetting adhesive layer was taken from the thermosetting adhesive sheet as a sample for glass transition point measurement. Using the above sample, Differential Scanning Calorimetry (DSC) was performed, whereby the endothermic curve of the above sample was obtained. Further, the above-described differential scanning calorimetry was carried out by heating from -50 ° C to 100 ° C at a temperature increase rate of 10 ° C / min under a nitrogen atmosphere to obtain an endothermic curve. The intermediate point of the critical point obtained by the above endothermic curve is set as the glass transition point. The glass transition point of -50 ° C or more and 10 ° C or less in the obtained glass transition point is "Tg _A ", and the glass transition point of 20 ° C or more and 100 ° C or less is set to "Tg _B ".

The gel fraction of the thermosetting adhesive layer (before curing) of the present invention is not particularly limited, and from the viewpoint of the flexibility of the thermosetting adhesive layer of the present invention, it is preferably less than 70% by weight. %) (for example, 0% or more and less than 70%), more preferably less than 60%, and even more preferably less than 50%. The gel fraction can be determined by insoluble methyl ethyl ketone, specifically, the insoluble fraction after immersion in room temperature (23 ° C) for 7 days in methyl ethyl ketone relative to the pre-impregnation. The weight fraction (unit: weight %) of the sample was determined. Since the above gel fraction is less than 70%, the flexibility of the thermosetting adhesive layer of the present invention is improved, and the force is then increased, which is preferable.

Specifically, the gel fraction (the ratio of the methyl ethyl ketone insoluble fraction) can be calculated, for example, by the following measurement method of the gel fraction.

<Method for measuring gel fraction>

About 0.1 g of the thermosetting adhesive layer of the present invention was collected from the thermosetting back sheet of the present invention as a thermosetting adhesive layer for gel fraction measurement. The porous tetrafluoroethylene sheet (trade name "NTF1122", manufactured by Nitto Denko Co., Ltd.) having a pore diameter of 0.2 μm is used in a porous thermosetting adhesive layer for measurement of the gel fraction. Bundling the kite line and measuring the weight at this time The amount is set to the weight before impregnation. Further, the pre-impregnation weight 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 line was also measured in advance, and the weight was defined as the weight of the bag.

Then, the above-mentioned thermosetting adhesive layer is wrapped with a sheet of tetrafluoroethylene and bundled with a kite string (referred to as "sample") into a 50 mL container filled with methyl ethyl ketone. It was allowed to stand at room temperature (23 ° C) for 1 week (7 days). Thereafter, the sample was taken out from the container (after methyl ethyl ketone treatment), transferred to an aluminum cup, and dried in a drier at 130 ° C for 2 hours to remove the methyl ethyl ketone, and then the weight was measured. The weight is set to the weight after immersion.

Then, the gel fraction was calculated from the following formula.

Gel fraction (% by weight) = (A-B) / (C-B) × 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 of the thermosetting adhesive layer of the present invention (before curing) at a temperature of 40 ° C for 7 days is not particularly limited, and is preferably 15%. (% by weight) or less, 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 fraction difference is preferably 15% or less, and is excellent in long-term storage stability.

The gel fraction difference is calculated by the following formula.

Gel fraction difference (% by weight) = (40 ° C gel fraction after storage for 7 days (% by weight)) - (The gel fraction of the thermosetting adhesive layer (before curing) of the present invention (% by weight) ))

Further, the gel fraction after the above-mentioned storage at 40 ° C for 7 days, specifically, for example, a thermosetting adhesive sheet after the heat-curable adhesive sheet of the present invention is stored at 40 ° C for 7 days. The collected thermosetting adhesive layer (before curing) was measured as "the thermosetting adhesive layer for measuring the gel fraction", and was measured in the same manner as in the above-mentioned "method for measuring gel fraction".

The gel fraction of the thermosetting adhesive layer of the present invention after curing at 150 ° C for 1 hour is not particularly limited, but is preferably 90% by weight or more, more preferably 92% or more, and still more preferably More than 96%. The upper limit of the gel fraction of the thermosetting adhesive layer of the present invention after curing at 150 ° C for 1 hour is not particularly limited and is, for example, 100%. By the gel fraction of 90% or more, the curing treatment of the thermosetting adhesive layer of the present invention can be quickly and sufficiently carried out, and the adhesion after curing and the heat resistance after moist heat are more excellent, which is preferable. When the gel fraction is less than 90%, the curing reaction is not sufficiently performed in the curing treatment at 150 ° C for 1 hour, and the heat resistance after the curing force or the heat after the heat is insufficient, in order to sufficiently follow it. A higher curing temperature or a longer curing time is required, so there is a case where the cost becomes high.

Further, the gel fraction of the thermosetting adhesive layer after curing at 150 ° C for 1 hour, specifically, for example, heating the thermosetting adhesive sheet of the present invention at 150 ° C for 1 hour. The thermosetting adhesive layer (cured thermosetting adhesive layer) collected by the thermosetting adhesive sheet after the curing treatment is used as a "thermosetting adhesive layer for gel fraction measurement", and The above <Method for Measuring Gel Fraction Ratio> was measured in the same manner and calculated.

[The thermosetting adhesive sheet of the present invention]

The thermosetting adhesive sheet of the present invention has at least one layer of the thermosetting type of the present invention Then the agent layer. The thermosetting adhesive sheet of the present invention may have, in addition to the thermosetting adhesive layer of the present invention, a base material, a thermosetting adhesive layer other than the thermosetting adhesive layer of the present invention, and the like. The thermosetting adhesive sheet (S1) has at least one thermosetting adhesive layer (L1), and may have a substrate, a thermosetting adhesive layer (L1) in addition to the thermosetting adhesive layer (L1). A thermosetting adhesive layer other than the other. Further, the thermosetting adhesive sheet (s2) has at least one thermosetting adhesive layer (L2), and may have a substrate and a thermosetting adhesive layer in addition to the thermosetting adhesive layer (L2). A thermosetting adhesive layer other than (L2). Further, the thermosetting back sheet of the present invention may have other layers (e.g., an intermediate layer, an undercoat layer, etc.) within the range not impairing the effects of the present invention. The layer other than the thermosetting adhesive layer (L1) or the layer other than the thermosetting adhesive layer (L2) may be provided in only one layer or two or more layers.

The thermosetting adhesive sheet of the present invention may be a single-sided adhesive sheet in which only one side of the sheet is the surface of the adhesive layer (the surface of the adhesive) (ie, the surface of the thermosetting adhesive layer of the present invention), or Both sides of the sheet are double-sided sheets of the surface of the adhesive layer (adhesive surface). The thermosetting adhesive sheet of the present invention is not particularly limited, and is preferably a double-sided back sheet, more preferably a double sheet, from the viewpoint of bonding the articles (attached bodies) to each other. The face is a double-sided backing sheet of the surface of the thermosetting adhesive layer.

The thermosetting adhesive sheet of the present invention may be a thermosetting adhesive sheet having a substrate (a thermosetting adhesive sheet with a substrate attached thereto) or a thermosetting adhesive sheet having no substrate ( Substrate-free thermoset type sheet). As the thermosetting back sheet of the present invention, for example, (1) a thermosetting back sheet comprising only the thermosetting adhesive layer of the present invention (a substrate-free thermosetting back sheet), (2) a thermosetting back sheet having a thermosetting adhesive layer of the present invention on at least one side (double-sided side or single-sided side) of the substrate (a thermosetting adhesive sheet with a substrate attached) For example, a thermosetting adhesive sheet having a thermosetting adhesive layer (L1) on at least one side (double-sided side or single-sided side) of the substrate, on at least one side of the substrate (double-sided side or single-sided side) a thermosetting type sheet having a thermosetting adhesive layer (L2) and the like. The thermosetting adhesive sheet of the present invention is preferably a substrate-free thermosetting adhesive sheet, and it is preferable that the composition of the above (1) includes only the present invention in terms of ease of manufacture. A substrate-free, thermoset-free sheet of the inventive thermoset adhesive layer. Further, the above "substrate" does not include a release liner (separator) which is peeled off when the thermosetting type sheet is used.

Furthermore, in the case where the thermosetting adhesive sheet of the present invention is a thermosetting adhesive sheet to which a substrate is attached, the thermosetting adhesive layer of the present invention may be provided on at least one side of the substrate. . The heat-resistant adhesive layer other than the thermosetting adhesive layer of the present invention or the thermosetting adhesive layer may be provided on the side of the substrate opposite to the side on which the thermosetting adhesive layer of the present invention is provided. A known adhesive layer [for example, an adhesive layer (pressure-sensitive adhesive layer) or the like].

The substrate is not particularly limited, and examples thereof include a paper base material such as paper; a fiber base material such as a cloth, a nonwoven fabric, or a mesh; a metal base material such as a metal foil or a metal plate; and various resins ( Polyolefin-based resin, polyester-based resin, polyvinyl chloride-based resin, vinyl acetate-based resin, polyamine-based resin, polyimide-based resin, polyetheretherketone (PEEK, Polyetheretherketone), polyphenylene sulfide ( PPS, Polyphenylene sulfide, etc.), such as a plastic substrate such as a film or a sheet; a rubber-based substrate such as a rubber sheet; a foamed substrate such as a foamed sheet; or a laminate (especially a plastic) Substrate and other bases A suitable sheet material such as a laminate of materials or a laminate of plastic films (or sheets).

The thickness of the substrate is not particularly limited, but is preferably 10 to 500 μm, more preferably 12 to 200 μm, still more preferably 15 to 100 μm. Further, the substrate may have a single layer form or a multilayer form. Further, various treatments such as back treatment, antistatic treatment, and primer treatment may be applied to the substrate as needed.

The thermosetting back sheet of the present invention may be in the form of a roll wound form or a laminated sheet. That is, the thermosetting back sheet of the present invention may have a form such as a sheet shape or a belt shape. Further, in the case where the thermosetting adhesive sheet of the present invention has a form of winding into a roll shape, for example, the heat-resistant adhesive layer may be subjected to a release treatment by a release liner or a back side formed on the substrate. In the state of layer protection, it is wound into a roll shape.

The surface of the adhesive layer (e.g., the thermosetting adhesive layer of the present invention) in the thermosetting adhesive sheet of the present invention can be protected by a release liner (separator). The release liner is not particularly limited, and a known release liner can be appropriately selected. As the release liner, for example, a release liner obtained by subjecting a surface of a substrate (pad substrate) such as a paper or a plastic film to a polysiloxane treatment, or a substrate such as a paper or a plastic film (patch) is preferable. A release liner in which the surface of the substrate is laminated with a polyolefin resin. The polyolefin resin is not particularly limited, and is preferably a polyethylene resin.

The thermosetting back sheet of the present invention can be produced in accordance with a known or conventional method of producing a sheet. For example, when the thermosetting adhesive sheet of the present invention is a substrate-free thermosetting adhesive sheet, it can be peeled off by the release liner. Coating the thermosetting adhesive composition (M1) or the thermosetting adhesive composition (M2) in such a manner that the thickness after drying becomes a specific thickness, and drying it to form the thermosetting of the present invention The adhesive layer of the type is used to form the thermosetting back sheet of the present invention.

In the case where the thermosetting adhesive sheet of the present invention is a thermosetting adhesive sheet to which a substrate is attached, the thermosetting adhesive layer of the present invention is formed on the release surface of the release liner in the same manner as described above. The thermosetting adhesive layer is transferred onto the surface of the substrate, and the thermosetting adhesive sheet of the present invention can be produced by this method. Further, the thermosetting adhesive composition (M1) or the thermosetting adhesive composition (M2) may be applied and dried by the thickness of the substrate after drying to a specific thickness. The method of forming the thermosetting adhesive layer of the present invention produces the thermosetting back sheet of the present invention.

Further, in the coating of the thermosetting adhesive composition (M1) or the coating of the thermosetting adhesive composition (M2), a conventional coating machine (for example, a gravure roll coater, a counter) may be used. Roll coater, contact roll coater, dip roll coater, bar coater, knife coater, spray roll coater, etc.).

The thermosetting adhesive sheet of the present invention and the thermosetting adhesive layer of the present invention are subjected to a curing reaction (heat curing) by heating, thereby exhibiting an excellent adhesion. The heat-curable adhesive layer of the present invention is cured (thermally cured) by heating the thermosetting adhesive sheet of the present invention to obtain a heat-resistant heat-resistant adhesive sheet having a firm adhesive force. material). The curing conditions (heating conditions) are not particularly limited, but are preferably heated 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 150 ° C or higher (for example, Heating at a temperature of 150~200 ° C) for more than 60 minutes (for example 60~360 minutes).

In the thermosetting adhesive sheet (S1), the thermosetting adhesive layer (L1) has Tg _A and Tg _B , whereby the strength of foaming is not confirmed even after soldering at 260 ° C after humidification. And can give the adhesion.

The thermosetting adhesive layer (L1) has a glass transition point of 20 ° C or more and 100 ° C or less, and can be used under very severe temperature conditions such as high temperature and long-term processing conditions after the subsequent exposure. The foaming of the adhesive layer is suppressed, and excellent heat resistance after moist heat is exhibited.

Moreover, since it has a glass transition point of -50 ° C or more and 10 ° C or less, it also has a certain degree of flexibility, so that it is possible to prevent a decrease in the adhesion force caused by becoming too hard, and also have a high adhesion force (adhesion). . Further, even when exposed to a very severe temperature condition, the delamination and peeling of the adhesive layer can be suppressed, and excellent heat resistance after moist heat can be exhibited.

In the thermosetting adhesive sheet (S2), the thermosetting adhesive composition (M2) contains the acrylic polymer (X), and the thermosetting adhesive layer (L2) formed from the composition ) is an adhesive layer having a high strength (block strength). Thereby, even in the case of exposure to a very high temperature condition such as high temperature and long-term processing conditions, foaming of the adhesive layer can be suppressed, and the thermosetting type sheet (S2) is excellent. Heat resistance after damp heat.

Further, the thermosetting adhesive composition (M2) contains the acrylic polymer (Y), and the thermosetting adhesive layer (L2) formed of the composition also has a certain degree of flexibility. Therefore, it is possible to prevent a decrease in the adhesion force caused by becoming too hard, and also to have a high adhesion force (adhesion). Furthermore, even if it is connected When it is exposed to a very severe temperature condition, the delamination and peeling of the adhesive layer can be suppressed, and the thermosetting-type sheet (S2) exhibits extremely excellent heat resistance after moist heat.

Further, when an etherified phenol resin is used as the thermosetting resin (Z), the adhesion of the thermosetting adhesive layer (L2) and the heat resistance after moist heat are particularly improved, so that the bonding force and the moist heat can be combined at an extremely high level. Post heat resistance is therefore preferred.

Furthermore, the effect of the present invention can be satisfied regardless of whether or not the above-described thermosetting type sheet (S2) is a thermosetting type sheet (S1).

The heat-curable pressure-sensitive adhesive sheet of the present invention exhibits high adhesion and particularly excellent heat resistance after moist heat after curing by heating. Therefore, the thermosetting adhesive sheet of the present invention can be preferably used for a case where it is required to be firmly adhered to, and even if it is subjected to treatment under extremely severe temperature conditions, it does not cause foaming or embossing, etc. Excellent use of heat resistance after damp heat. Specifically, the thermosetting back sheet of the present invention can be preferably used, for example, in a flexible printed circuit board (FPC). That is, the thermosetting back sheet of the present invention is preferably a thermosetting back sheet for FPC. In addition, the following in the FPC means, for example, the next step in the production of the FPC or the subsequent attachment of the FPC to the reinforcing plate.

Most of the FPC will undergo a high temperature reflow step until it is incorporated into the final product, thereby requiring that the thermoset backsheet used will not cause foaming or embossing after the reflow step. In such FPC use, in particular, from the viewpoint of reliability, it is considered to be "heat resistance after damp heat". Furthermore, the above-mentioned "heat resistance after damp heat" means that even if heat is to be used The solid-formed sheet is then stored in a laminate made of the adherend under high temperature and high humidity (for example, at a temperature of 40 to 60 ° C and a humidity of 60 to 95% RH), and then subjected to severe temperature conditions (for example, a temperature of 250 °). When the treatment is carried out at 270 ° C for 1 to 3 minutes, the characteristics of foaming or bulging peeling on the above-mentioned thermosetting type sheet (thermosetting type adhesive layer) are not easily obtained. The thermosetting back sheet of the present invention can exhibit a high adhesion after heat curing, and can exhibit extremely excellent heat resistance after moist heat, and thus can be used as a high-reliability thermosetting back sheet especially in FPC applications.

The present invention may be characterized in that it has a thermosetting type formed by a thermosetting adhesive composition containing a first acrylic polymer and a second acrylic polymer as a main component and containing a thermosetting resin. a heat-curing adhesive sheet constituting a monomer component of the first acrylic polymer and a monomer component constituting the second acrylic polymer (hereinafter referred to as "thermothermal curing of other embodiments" Type followed by sheet"). The total amount (total content) of the content of the first acrylic polymer and the content of the second acrylic polymer in all the nonvolatile components (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 secondary sheet of the above-described other embodiment are not particularly limited, and each of the conventionally known acrylic monomers is an essential monomer component. Acrylic polymer. Among them, an alkyl (meth)acrylate having a linear or branched alkyl group having 1 to 12 carbon atoms, a monomer having a cyano group, and a monomer having a carboxyl group are preferably used as an essential monomer component. The acrylic polymer is composed. Further, it is also possible to use a monomer component other than the above monomers (other monomers are formed Minute).

The monomer component constituting the first acrylic polymer is different from the monomer component constituting the second acrylic polymer. That is, the monomer component constituting the first acrylic polymer does not have to completely match the monomer component constituting the second acrylic polymer (all monomer components are identical). Thereby, the thermosetting adhesive layer of the thermosetting adhesive sheet of the other embodiment can have both strength and flexibility, and has both high adhesion and excellent heat resistance after damp heat.

[Flexible Printed Circuit Board (FPC)]

The FPC having the thermosetting back sheet of the present invention can be obtained by fabricating an FPC using the thermosetting back sheet of the present invention or by bonding the FPC to the reinforcing sheet using the thermosetting back sheet of the present invention.

In the FPC having the thermosetting back sheet of the present invention, by thermally curing the back sheet, an FPC having a heat-curing adhesive sheet having a firm adhesive force can be obtained (having heat of heat curing) Solid type followed by sheet FPC). The curing conditions in the thermal curing are not particularly limited, but it is preferably heated 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 150 ° C or higher. Heat at a temperature (for example, 150 to 200 ° C) for 60 minutes or more (for example, 60 to 360 minutes).

[Examples]

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

Table 1 shows the types, monomer compositions, weight average molecular weight (Mw) of the acrylic polymer in the examples and the comparative examples, and the content (adjusted amount) in the thermosetting adhesive composition, and a thermosetting resin ( Etherified phenol resin, etc.) The kind and content (adjusted amount) in the thermosetting adhesive composition. In addition, in Table 1, the monomer composition of the acrylic polymer is represented by the content (% by weight) of each monomer in the total amount (100% by weight) of the monomer components constituting the acrylic polymer. Moreover, the content of the acrylic polymer and the thermosetting resin is represented by the content (parts by weight) of the nonvolatile component.

Example 1 (Preparation of acrylic polymer (X1))

In a reactor equipped with a cooling tube, a nitrogen inlet tube, a thermometer and a stirrer, 2,2'-azobis{2-[1-(2-hydroxyethyl)-2-imidazolin-2-yl]propane was charged. } Dihydrochloride (trade name "VA-060", manufactured by Wako Pure Chemical Industries, Ltd.) (polymerization initiator) 0.279 g, 100 g of ion-exchanged water, and stirred while introducing nitrogen gas for 1 hour. This was kept at 60 ° C, and 65 parts by weight of Acrylic acid ethyl ester (EA, Ethyl acrylate), 30 parts by weight of acrylonitrile (AN, Acrylonitrile), and acrylic acid (AA) were slowly added dropwise over 3 hours. , Acrylic acid) 5 parts by weight, 0.04 parts by weight of 1-dodecanethiol (chain transfer agent) and 2 parts by weight of polyoxyethylene sodium lauryl ether sulfate (emulsifier) were added to 41 parts by weight of ion-exchanged water and emulsified. The emulsion (the emulsion of the monomer raw material) was 400 g, and the emulsion polymerization reaction was carried out. After the dropwise addition of the emulsion of the monomer raw material, the mixture was further aged at the same temperature for 3 hours to be aged. An aqueous dispersion (emulsion) of the acrylic polymer thus polymerized was dried to obtain an acrylic polymer (X1) (weight average molecular weight: 1.5 million).

(Preparation of acrylic polymer (Y1))

For reactors with cooling tubes, nitrogen inlet tubes, thermometers and mixers Into the 2,2-azobis{2-[1-(2-hydroxyethyl)-2-imidazolin-2-yl]propane} dihydrochloride (trade name "VA-060", and pure light 0.279 g of a polymerization initiator (manufactured by Pharmaceutical Industries, Ltd.) and 100 g of ion-exchanged water were stirred for 1 hour while introducing nitrogen gas. This was kept at 60 ° C, and 66 parts by weight of butyl acrylate (n-Butyl Acrylate) (BA, n-Butyl Acrylate), 29 parts by weight of acrylonitrile (AN), acrylic acid (AA) was slowly added dropwise over 3 hours. 5 parts by weight, 0.04 parts by weight of 1-dodecanethiol (chain transfer agent), and 2 parts by weight of polyoxyethylene sodium lauryl ether sulfate (emulsifier) are added to 41 parts by weight of ion-exchanged water and emulsified ( The emulsion of the monomer raw material) was 400 g, and the emulsion polymerization reaction was carried out. After the dropwise addition of the emulsion of the monomer raw material, the mixture was further aged at the same temperature for 3 hours to be aged. An aqueous dispersion (emulsion) of the acrylic polymer thus polymerized was dried to obtain an acrylic polymer (Y1) (weight average molecular weight: 1,000,000).

(Preparation of thermosetting adhesive composition)

The copolymer of the above acrylic polymer (X1) [65% by weight of ethyl acrylate (EA), 30% by weight of acrylonitrile (AN), and 5% by weight of acrylic acid (AA) as a monomer component is dissolved] 100 parts by weight and the above acrylic polymer (Y1) [copolymerized with butyl acrylate (BA) 66% by weight, acrylonitrile (AN) 29% by weight, and acrylic acid (AA) 5% by weight as a monomer component) In an ethyl acetate solution of 3 parts by weight, the product name "CKS-3898" (manufactured by Showa Denko Co., Ltd.) as an etherified phenol resin (Z1) was mixed and dissolved: 12 parts by weight (nonvolatile matter) The butanol solution was stirred and a thermosetting adhesive composition (solution) was prepared.

That is, the acrylic polymer is contained in the thermosetting adhesive composition. (X1) 100 parts by weight, 3 parts by weight of the acrylic polymer (Y1), and 12 parts by weight of an etherified phenol resin (thermosetting resin) (Z1). The total amount of the acrylic polymer (X1) and the content of the acrylic polymer (Y1) in all the nonvolatile components (100% by weight) of the thermosetting adhesive composition was 90% by weight.

(The manufacture of thermosetting type sheets)

The thermosetting adhesive composition was applied to a release surface of a release liner so as to have a thickness of 25 μm after drying, and dried at 100 ° C for 3 minutes to form a thermosetting adhesive layer (thickness 25 μm). And obtaining a thermosetting back sheet (substrate-free thermosetting sheet comprising only a thermosetting type of adhesive layer).

Example 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 a thermosetting adhesive composition and a thermosetting adhesive sheet were obtained in the same manner as in Example 1. .

Example 5~8 (Preparation of acrylic polymer (X2))

An acrylic polymer was obtained in the same manner as in the production method 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).

(Preparation of thermosetting adhesive composition, thermosetting type and subsequent sheet production)

As shown in Table 1, the acrylic polymer (X2) was used instead of the acrylic polymer (X1), and the content of the acrylic polymer (Y1) and the content of the etherified phenol resin (Z1) were changed, in the same manner as in Example 1. The same way to obtain thermoset type The composition of the composition and the thermoset type of the sheet.

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 except that the acrylic polymer (Y1) was not used.

Comparative example 2

As shown in Table 1, a thermosetting adhesive composition was obtained in the same manner as in Example 1 except that the acrylic polymer (Y1) was not used, and the acrylic polymer (X2) was used instead of the acrylic polymer (X1). And a thermosetting type of sheet.

Comparative example 3

As shown in Table 1, the thermosetting adhesive composition and the thermosetting adhesive sheet were obtained in the same manner as in Example 1 except that the acrylic polymer (X1) was not used and the content of the acrylic polymer (Y1) was changed. material.

Comparative example 4 (Preparation of acrylic polymer (Y2))

The amount of butyl acrylate (n-butyl acrylate) (BA) was changed from 66 parts by weight to 64 parts by weight, and the amount of acrylonitrile (AN) was changed from 29 parts by weight to 34 parts by weight, and the amount of acrylic acid (AA) was used. An acrylic polymer (Y2) was obtained in the same manner as in the production method of the acrylic polymer (Y1) of Example 1, except that the amount of the acrylic polymer (Y1) was changed from 5 parts by weight to 2 parts by weight.

(Preparation of thermosetting adhesive composition)

The above-mentioned acrylic polymer (Y2) [copolymer composed of 64% by weight of butyl acrylate (BA), 34% by weight of acrylonitrile (AN), and 2% by weight of acrylic acid (AA) as a monomer component was dissolved: 100 parts by weight of acetic acid B In the ester solution, a methanol solution obtained by dissolving, as a resol-type phenol resin (Z2), the product name "PR-51283" (manufactured by SUMITOMO BAKELITE Co., Ltd.): 10 parts by weight (nonvolatile matter) was stirred and stirred. A thermosetting adhesive composition (solution) was prepared.

That is, 100 parts by weight of the acrylic polymer (Y2) and 10 parts by weight of the thermosetting resin (Z2) are contained in the thermosetting adhesive composition. The content of the acrylic polymer (Y2) in all the nonvolatile components (100% by weight) of the thermosetting adhesive composition was 90% by weight.

(The manufacture of thermosetting type sheets)

A thermosetting adhesive composition and a thermosetting adhesive sheet were obtained in the same manner as in Example 1.

(Evaluation)

For each of the thermosetting adhesive sheets obtained in the examples and the comparative examples, the adhesion force after curing of the thermosetting adhesive layer, heat resistance after moist heat, and glass were measured or evaluated by the following measurement methods or evaluation methods, respectively. Transfer point (Tg _A , Tg _B ). Further, the gel fraction of the thermosetting adhesive layer of the present invention (before heat curing), the difference in gel fraction after storage at 40 ° C for 7 days, and the gel fraction after curing at 150 ° C for 1 hour are borrowed. The measurement was carried out by the above evaluation method.

(1) Method of measuring the force

The adhesion force (N/cm) at 23 ° C was measured by the following method for the cured thermosetting adhesive layers in the respective heat-set adhesive sheets obtained in the examples and the comparative examples.

Laminated flexible printed circuit board (FPC, size: width 5 cm × length 8 cm, thickness 0.2 mm) at 130 ° C, and after heat-sealing the sheet, cut The width is 1 cm (the thermosetting type is then laminated on the single side of the FPC (the material of the surface: polyimine)). It was laminated on 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 pressed at 2 MPa at 160 ° C (pressing) ) 90 seconds to attach to the stainless steel plate. Further, curing (heat curing) was carried out at 150 ° C for 1 hour to prepare a test piece.

With respect to the above test body, a 90° peeling force (tensile speed: 50) was measured by a method of pulling the FPC side using a tensile tester (product name "TCM-1kNB", manufactured by Minebea Co., Ltd.). Mm/min, 23 ° C, 50% RH, N/cm).

In addition, the measurement result is shown in the "adhesion force (N/cm) SUS" column of Table 1.

Further, in the above measurement, a polyimide plate (PI (Polyimide, size: 5 cm × width 5 cm, thickness: 0.13 mm) was used instead of the stainless steel plate, and the 90° peeling adhesion force was measured in the same manner. The measurement results are shown in the column "Bottom force (N/cm) PI" in Table 1.

(2) Evaluation method of heat resistance after moist heat (260 ° C solder immersion after humidification)

The heat resistance after the moist heat was evaluated for the cured thermosetting adhesive layers in the respective thermosetting back sheets obtained in the examples and the comparative examples.

Laminated copper foil laminate (CCL (Copper Clad Laminate), polyimide/copper laminate, size: width 5 cm × length 8 cm, thickness 45 μm) at 130 ° C, and after heat-bonding of the sheet Cut to a width of 1 cm (the thermoset type is then laminated to the entire surface of the polyacrylamide surface of CCL). After laminating it 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, 2 at 160 ° C The MPa was pressed (pressed) for 90 seconds to be attached to a stainless steel plate. Further, curing was carried out at 150 ° C for 1 hour (heat curing) to prepare a test body.

After the test body was allowed to stand under humidification (temperature: 60 ° C, humidity: 90% RH) for 24 hours, the surface of the stainless steel plate side of the test piece was dipped in a solder bath at 260 ° C for 3 minutes. .

The heat-resistant adhesive sheet (thermosetting adhesive layer) in the test piece was visually observed for the state of bulging peeling and foaming, and the heat resistance after moist heat was evaluated according to the following criteria. In addition, the evaluation result is shown in the column of "heat-resistant heat-resistant SUS" of Table 1.

Excellent heat resistance after moist heat (?): No peeling and foaming were observed in the thermosetting adhesive layer.

Good heat resistance after moist heat (○): Only a small amount of bulging peeling and foaming were confirmed at the end portion of the attached portion.

After heat and humidity, the heat resistance is slightly inferior, but it can be used (Δ): the end portion of the attached portion and the portion other than the end portion are confirmed to be peeled off and foamed.

Heat resistance after wet heat was poor (x): ridge peeling and foaming were confirmed on the entire surface of the thermosetting adhesive layer.

Further, in the above evaluation, a polyimide plate (PI: size: length: 5 cm × width: 5 cm, thickness: 0.13 mm) was used instead of the stainless steel plate, and the heat resistance after moist heat was evaluated in the same manner. The evaluation results are shown in the column "Heat heat after heat resistance PI" in Table 1.

(3) Method for measuring glass transfer point (glass transition temperature)

The glass transition point (° C.) was measured by the following method for the thermosetting adhesive layers in the respective thermosetting back sheets obtained in the examples and the comparative examples.

A thermosetting adhesive layer of about 2 mg was taken from the thermoset type sheet to be used as a sample for glass transition point measurement for DSC measurement. The above sample was placed in an aluminum cylindrical cell having a diameter of 5 mm and a depth of 2 mm, and the lid was closed and sealed. An empty aluminum cylindrical groove 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 under a nitrogen atmosphere (nitrogen flow rate: 50 ml / min), and quenched. The endothermic curve of the above sample when the temperature was raised again at a rate of 10 ° C/min from -50 ° C to 100 ° C was measured at -50 ° C.

The intermediate point of the critical point in the obtained endothermic curve is taken as the glass transition point. The glass transition point of -50 ° C or more and 10 ° C or less in the obtained glass transition point is "Tg _A ", and the glass transition point of 20 ° C or more and 100 ° C or less is set to "Tg _B ", and Tg _A and Tg _{B are used.} It is shown in the "Tg _A " column and the "Tg _B " column in Table 1.

From Table 1, it is understood that the heat-curable pressure-sensitive adhesive sheet of the present invention has a high adhesive force after curing, and is excellent in adhesion, and further, even in the case of performing very severe temperature conditions of solder immersion at 260 ° C after humidification. At the same time, it also has high heat and heat resistance.

On the other hand, in the case where the thermosetting adhesive layer does not have a glass transition point at -50 ° C or more and 10 ° C or less (the acrylic polymer is not contained in the thermosetting adhesive composition forming the thermosetting adhesive layer) In the case of (Y) (Comparative Examples 1 and 2), the thermosetting adhesive layer became too hard, and the force was lowered. Further, by the solder immersion treatment at 260 ° C after humidification, delamination peeling or foaming occurs at the interface between the thermosetting adhesive layer and the adherend, and heat resistance after damp heat is inferior. Further, in the case where the thermosetting adhesive layer does not have a glass transition point at 20 ° C or more and 100 ° C or less (the acrylic polymer (X) is not contained in the thermosetting adhesive composition forming the thermosetting adhesive layer) In the case of (Comparative Examples 3 and 4), the strength of the block of the thermosetting adhesive layer was lowered, and foaming, heat and humidity in the thermosetting adhesive layer was caused by the treatment of solder immersion at 260 ° C after humidification. After heat resistance is poor.

Industrial availability

The thermosetting back sheet of the present invention can be preferably used for the case where it is required to be firmly adhered to, and even if it is subjected to treatment under extremely severe temperature conditions, it does not cause foaming or swelling and the like. Use of heat resistance after damp heat, etc. Specifically, the thermosetting back sheet of the present invention can be preferably used, for example, in a flexible printed circuit board (FPC).

Claims (13)

A thermosetting adhesive sheet characterized by having a thermosetting adhesive layer having a glass transition point of from -50 ° C to 10 ° C and from 20 ° C to 100 ° C. The thermosetting adhesive sheet according to claim 1, wherein the thermosetting adhesive layer contains a secondary polymer (X) and an acrylic polymer (Y) described below as a main component and contains a thermosetting resin. A thermosetting adhesive layer formed of the thermosetting adhesive composition of (Z), an acrylic polymer (X): a linear or branched alkyl group having a carbon number of 1 to 3 (A) The alkyl acrylate (a1) is an acrylic polymer composed of an essential monomer component, and constitutes the above (meth)acrylic acid in the total amount (100% by weight) of the monomer component of the acrylic polymer. The content of the base ester (a1) is 50% by weight or more; the acrylic polymer (Y): an alkyl (meth)acrylate having a linear or branched alkyl group having 4 to 12 carbon atoms (a2) An acrylic polymer composed of an essential monomer component, and the content of the alkyl (meth)acrylate (a2) in the total amount (100% by weight) of the monomer components constituting the acrylic polymer is 50% by weight or more. The thermosetting back sheet according to claim 2, wherein the content of the acrylic polymer (Y) is from 1 to 100 parts by weight based on 100 parts by weight of the acrylic polymer (X). The heat-set adhesive sheet according to claim 2 or 3, wherein the acrylic polymer (X) further comprises a cyano group-containing monomer (b1) and a carboxyl group-containing monomer (c1) as essential monomer components. The acrylic polymer is composed. The thermosetting adhesive sheet according to claim 2 or 3, wherein the acrylic polymer (Y) further comprises a cyano group-containing monomer (b2) and a carboxyl group-containing monomer (c2) as essential monomer components. The acrylic polymer is composed. A heat-set type sheet according to claim 2 or 3, wherein the above-mentioned thermosetting resin (Z) is a phenol resin. A heat-set type sheet according to claim 6, wherein the phenol resin is an etherified phenol resin. The thermosetting adhesive sheet according to claim 2 or 3, wherein the thermosetting resin (Z) is contained in an amount of from 1 to 40 parts by weight based on 100 parts by weight of the acrylic polymer (X). The thermosetting adhesive sheet according to any one of claims 1 to 3, which is a thermosetting adhesive sheet for a flexible printed circuit board. A flexible printed circuit board having the thermoset type following sheet of claim 9. A heat-cured heat-curing adhesive sheet obtained by thermally curing a heat-set type sheet according to any one of claims 1 to 3. A flexible printed circuit board having a thermally cured heat-curing adhesive sheet as claimed in claim 11. A thermosetting adhesive sheet characterized by having a thermosetting type formed of a thermosetting adhesive composition containing a first acrylic polymer and a second acrylic polymer as a main component and containing a thermosetting resin. Next, the monomer layer of the first acrylic polymer is different from the monomer component constituting the second acrylic polymer.