adhesive composition

Abstract

Provided is an adhesive composition that has superior electrical properties and is capable of forming an adhesive layer of superior tightness of bond (adhesiveness) when heat-cured, and that has superior tightness of bond (adhesiveness) even when cured at lower temperatures, and allows for improved workability.　The adhesive composition contains an amino-group-containing styrene-based elastomer, and an epoxy resin.

Description

[Technical Field]

[0001] The present invention relates to an adhesive composition, and more particularly to an adhesive composition that can be used for bonding electronic components and the like. [Background technology]

[0002] BACKGROUND ART As electronic devices become smaller and lighter, the adhesive applications for electronic components and the like are becoming more diverse, and the demand for laminates with adhesive layers is increasing. Furthermore, flexible printed circuit boards (hereinafter referred to as FPCs), which are one type of electronic component, are required to process large amounts of data at high speed, and progress is being made in supporting higher frequencies.Increasing the frequency of FPCs requires lower dielectric constant components, and low-dielectric substrate films and low-dielectric adhesives are being developed.

[0003] However, because low-dielectric adhesives have low molecular polarity, they are less likely to exhibit adhesion (bonding) with base films and other components related to electronic parts, and low-dielectric base films can also have poor adhesion (bonding) with adhesives, so there is a demand for improved adhesion. Therefore, in order to meet the demand for high adhesiveness while maintaining good electrical properties (low dielectric constant and low dielectric dissipation factor), a laminate has been proposed which uses an adhesive composition containing a carboxyl group-containing styrene-based elastomer (A) and an epoxy resin (B) and which comprises an adhesive layer made of the adhesive composition and a substrate film (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2016 / 017473 Summary of the Invention [Problem to be solved by the invention]

[0005] However, although the adhesive composition described in Patent Document 1 exhibits a certain degree of high adhesion (adhesion) after heat curing, there is still room for improvement in terms of improving adhesion (adhesion). In addition, low-dielectric adhesives have fewer highly polar reactive substituents to lower the dielectric constant. This means that the curing temperature cannot be lowered, the curing time is long, and workability is poor, limiting the equipment that can be used. From the perspective of practical application, there has been a need for an adhesive that can exhibit high adhesion (bonding) even when cured at a lower temperature and improve workability.

[0006] Therefore, an object of the present invention is to provide an adhesive composition that has excellent electrical properties and is capable of forming an adhesive layer that has excellent adhesion (adhesion) after heat curing, and that maintains excellent adhesion (adhesion) even when cured at a lower temperature, thereby improving workability. [Means for solving the problem]

[0007] As a result of extensive research into solving the above-mentioned problems, the present inventors have discovered that an adhesive composition containing an amino group-containing styrene-based elastomer and an epoxy resin not only exhibits high adhesion (adhesion) to a substrate film after heat curing, but also exhibits excellent adhesion (adhesion) even when cured at a lower temperature, has excellent workability, and can solve the above-mentioned problems, thereby completing the present invention.

[0008] The present invention includes the following aspects. [1] An adhesive composition containing an amino group-containing styrene-based elastomer and an epoxy resin. [2] The adhesive composition according to [1], wherein the content of the epoxy resin is 1 to 20 parts by mass per 100 parts by mass of the adhesive composition. [3] The adhesive composition according to [1] or [2], wherein the total nitrogen content in the amino group-containing styrene-based elastomer is 50 to 5000 ppm. [4] The adhesive composition according to any one of [1] to [3], wherein the softening point or melting point of the epoxy resin is 90° C. or lower. [5] The adhesive composition according to any one of [1] to [4], wherein the epoxy resin is a novolac epoxy resin. [6] The adhesive composition according to any one of [1] to [4], wherein the epoxy resin is a glycidylamine type epoxy resin. [7] The adhesive composition according to any one of [1] to [4], wherein the epoxy resin is an epoxy compound of a styrene-butadiene block copolymer. [8] An adhesive layer obtained by curing the adhesive composition according to any one of [1] to [7], wherein the adhesive layer has a relative dielectric constant of 3.5 or less and a dielectric loss tangent of 0.01 or less, measured at a frequency of 28 GHz. [9] A base film; A laminate comprising an adhesive layer made of the adhesive composition according to any one of [1] to [7], or the adhesive layer according to [8].

[10] The laminate according to [9], wherein the substrate film contains polyether ether ketone (PEEK) resin.

[11] A coverlay film with an adhesive layer comprising the laminate according to [9] or

[10] .

[12] A copper-clad laminate comprising the laminate according to [9] or

[10] .

[13] A printed wiring board comprising the laminate according to [9] or

[10] .

[14] A shielding film comprising the laminate according to [9] or

[10] .

[15] A printed wiring board with a shielding film, comprising the laminate according to [9] or

[10] . [Effects of the Invention]

[0009] According to the present invention, it is possible to provide an adhesive composition that has excellent electrical properties and is capable of forming an adhesive layer that has excellent adhesion (adhesion) after heat curing, and that maintains excellent adhesion (adhesion) even when cured at a lower temperature, thereby improving workability. DETAILED DESCRIPTION OF THE INVENTION

[0010] The adhesive composition of the present invention, a laminate including an adhesive layer made of the adhesive composition, and a component related to electronic components including the laminate will be described in detail below. However, the description of the constituent elements described below is an example of one embodiment of the present invention, and the present invention is not limited to these contents.

[0011] (Adhesive composition) The adhesive composition of the present invention contains an amino group-containing styrene-based elastomer and an epoxy resin. If necessary, the adhesive composition of the present invention may contain a styrene-based elastomer other than the amino group-containing styrene-based elastomer (e.g., a carboxy group-containing styrene-based elastomer). Furthermore, the adhesive composition of the present invention may contain other components if necessary.

[0012] <Amino group-containing styrene elastomer> The inclusion of an amino group-containing styrene elastomer in the adhesive composition improves the adhesive layer's adhesion, particularly to metals. Furthermore, because the amino group-containing styrene elastomer is reactive, the adhesive layer's heat resistance and chemical resistance are also improved by epoxy curing. The adhesive composition contains a styrene-based elastomer containing an amino group, so that the composition exhibits excellent adhesion (bonding properties) even when cured at a lower temperature. The amino group-containing styrene elastomer is an amine-modified copolymer of a conjugated diene compound and an aromatic vinyl compound, which is mainly composed of block and random structures, or a hydrogenated product thereof. Examples of aromatic vinyl compounds include styrene, t-butylstyrene, α-methylstyrene, divinylbenzene, 1,1-diphenylethylene, N,N-diethyl-p-aminoethylstyrene, vinyltoluene, etc. Examples of conjugated diene compounds include butadiene, isoprene, 1,3-pentadiene, 2,3-dimethyl-1,3-butadiene, etc.

[0013] The method for amine-modifying a styrene-based elastomer is not particularly limited, and any known method can be used. Examples of such methods include a method of amine-modifying a (hydrogenated) block copolymer by polymerizing it using a polymerization initiator having an amino group, a method of amine-modifying a (hydrogenated) copolymer by using an unsaturated monomer having an amino group as a raw material for copolymerization, and a method of amine-modifying a styrene-based elastomer containing a carboxy group by reacting it with an amine modifier having two or more amino groups to form an amide structure or an imide structure.

[0014] The weight-average molecular weight of the amino group-containing styrene elastomer is preferably 10,000 to 500,000, more preferably 30,000 to 300,000, and even more preferably 50,000 to 200,000. If the weight-average molecular weight is equal to or greater than the lower limit, excellent adhesive properties can be exhibited, and the coatability when dissolved in a solvent and coated also improves. If the weight-average molecular weight is equal to or less than the upper limit, compatibility with epoxy resins improves. The weight average molecular weight is a value obtained by converting the molecular weight measured by gel permeation chromatography (hereinafter also referred to as "GPC") into polystyrene equivalent.

[0015] Specific examples of styrene-based elastomers containing an amino group include styrene-butadiene block copolymers, styrene-ethylene propylene block copolymers, styrene-butadiene-styrene block copolymers, styrene-isoprene-styrene block copolymers, styrene-ethylenebutylene-styrene block copolymers, and styrene-ethylenepropylene-styrene block copolymers that have been amine-modified using a compound having an amino group. These amino group-containing styrene elastomers may be used alone or in combination of two or more. Among the above copolymers, styrene-ethylenebutylene-styrene block copolymers and styrene-ethylenepropylene-styrene block copolymers are preferred from the viewpoints of adhesiveness and electrical properties. Furthermore, the mass ratio of styrene / ethylenebutylene in the styrene-ethylenebutylene-styrene block copolymer and the mass ratio of styrene / ethylenepropylene in the styrene-ethylenepropylene-styrene block copolymer are preferably 10 / 90 to 50 / 50, and more preferably 20 / 80 to 40 / 60. When the mass ratios are within these ranges, an adhesive composition with excellent adhesive properties can be obtained.

[0016] The content of the amino group-containing styrene elastomer is preferably 25.0 to 99.0 parts by mass per 100 parts by mass of the solid content of the adhesive composition. If the content is within this range, the adhesive composition will have excellent adhesive properties.

[0017] From the viewpoint of ensuring a low dielectric constant and adhesiveness (bonding properties) of the adhesive composition, the total nitrogen content in the amino group-containing styrene elastomer is preferably 50 to 5000 ppm, more preferably 200 to 3000 ppm. When the total nitrogen content is equal to or greater than the above lower limit, excellent adhesiveness can be achieved. When the total nitrogen content is equal to or less than the above upper limit, excellent electrical properties can be achieved. The total nitrogen content in the amino group-containing styrene elastomer can be determined, for example, using a trace nitrogen analyzer ND-100 (manufactured by Mitsubishi Chemical Corporation) in accordance with JIS-K2609.

[0018] <Epoxy resin> The epoxy resin is a component that reacts with the amino groups in the amino-group-containing styrene elastomer, thereby imparting high adhesiveness to adherends and heat resistance to the cured adhesive.

[0019] Examples of epoxy resins include bisphenol A type epoxy resins, bisphenol F type epoxy resins, and hydrogenated versions thereof; glycidyl ester-based epoxy resins such as phthalic acid diglycidyl ester, isophthalic acid diglycidyl ester, terephthalic acid diglycidyl ester, p-hydroxybenzoic acid diglycidyl ester, tetrahydrophthalic acid diglycidyl ester, succinic acid diglycidyl ester, adipic acid diglycidyl ester, sebacic acid diglycidyl ester, and trimellitic acid triglycidyl ester; ethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, 1,4-butanediol diglycidyl ether, and the like. Examples of epoxy resins that can be used include, but are not limited to, glycidyl ether-based epoxy resins such as glycidyl ether, 1,6-hexanediol diglycidyl ether, trimethylolpropane triglycidyl ether, pentaerythritol tetraglycidyl ether, tetraphenylglycidyl ether ethane, triphenylglycidyl ether ethane, sorbitol polyglycidyl ether, and polyglycerol polyglycidyl ether; glycidyl amine-based epoxy resins such as triglycidyl isocyanurate and tetraglycidyldiaminodiphenylmethane; and linear aliphatic epoxy resins such as epoxidized polybutadiene and epoxidized soybean oil. Additionally, novolac-type epoxy resins such as xylene structure-containing novolac epoxy resins, naphthol novolac-type epoxy resins, phenol novolac epoxy resins, o-cresol novolac epoxy resins, and bisphenol A novolac epoxy resins can also be used.

[0020] Further, examples of epoxy resins that can be used include brominated bisphenol A type epoxy resins, phosphorus-containing epoxy resins, fluorine-containing epoxy resins, dicyclopentadiene skeleton-containing epoxy resins, naphthalene skeleton-containing epoxy resins, anthracene type epoxy resins, tertiary butylcatechol type epoxy resins, triphenylmethane type epoxy resins, tetraphenylethane type epoxy resins, biphenyl type epoxy resins, bisphenol S type epoxy resins, etc. These epoxy resins may be used alone or in combination of two or more. Among the above epoxy resins, epoxy resins without hydroxyl groups are preferred because they provide adhesive compositions with excellent electrical properties and have good compatibility with styrene-based elastomers. In particular, novolac epoxy resins and epoxy resins such as those shown in the following structures are more preferred because they have a moderately flexible backbone, making the cured product less susceptible to brittle fracture, improving the stability of the performance of the cured product of the adhesive composition over long-term use, and also improving heat resistance due to their high number of functional groups.

[0021] [ka] (R is a structure containing methylene-aryl-methylene or a structure containing an aliphatic hydrocarbon structure having 6 or more carbon atoms, and examples of aryl include benzene, xylene, naphthalene, and biphenyl, while examples of aliphatic hydrocarbon include hexane, dimethylcyclohexane, and dicyclopentadiene.) Specific examples of novolac epoxy resins include Mitsubishi Chemical's "YX7700" (xylene structure-containing novolac epoxy resin), Nippon Kayaku's "NC7000L" (naphthol novolac epoxy resin), Nippon Steel Chemical & Material's "ESN485" (naphthol novolac epoxy resin), DIC's "N-690" (cresol novolac epoxy resin), and DIC's "N-695" (cresol novolac epoxy resin). Epoxy compounds of styrene-butadiene block copolymers are more preferred. Epoxy compounds of styrene-butadiene block copolymers can accelerate the reaction rate and increase crosslink density by involving unsaturated bonds in addition to aromatic rings such as olefin skeletons and vinyl groups in the reaction of the epoxy structure, resulting in improved heat resistance and chemical resistance even at low blend amounts. In addition, the epoxy compound of styrene-butadiene block copolymer has a large molecular weight and contains epoxy groups, so it acts as a dispersant and further improves the dispersibility of the inorganic filler. As the epoxy compound of styrene-butadiene block copolymer, commercially available epoxy compounds can be used, such as CELLOXIDE 2021P, CELLOXIDE 2081, CELLOXIDE 2000 (manufactured by Daicel Corporation), EPOLEAD GT401, EPOLEAD PB3600, EPOLEAD PB4700 (manufactured by Daicel Corporation), EPOKEFRIEND AT501, and EPOKEFRIEND CT310 (manufactured by Daicel Corporation).

[0022] Furthermore, epoxy resins containing amino groups can improve workability by shortening the curing time and lowering the curing temperature due to the catalytic action of the amino groups. In addition, the inclusion of amine groups improves adhesion to metal layers. In particular, it is more preferable that the epoxy resin is a glycidylamine-type epoxy resin. Glycidylamine-type epoxy resins are multifunctional, allowing them to cure in small amounts, and because they contain amines in their molecular skeleton, they have good compatibility with amino-group-containing styrene-based elastomers and also have a reaction-accelerating effect. Furthermore, because they contain amine groups, they can improve adhesion to metal layers. Specific examples of glycidylamine-type epoxy resins include tetraglycidyldiaminodiphenylmethane, such as "jER604" manufactured by Mitsubishi Chemical Corporation, "Sumiepoxy ELM434" manufactured by Sumitomo Chemical Co., Ltd., "Araldite MY720," "Araldite MY721," "Araldite MY9512," "Araldite MY9612," "Araldite MY9634," and "Araldite MY9663" manufactured by Huntsman Advanced Materials, Inc., and "TETRAD-X" and "TETRAD-C" manufactured by Mitsubishi Gas Chemical Company, Inc.

[0023] The epoxy resin used in the present invention preferably has two or more epoxy groups in one molecule. This is because a crosslinked structure is formed by reaction with the amino group-containing styrene elastomer, thereby exhibiting high heat resistance. Furthermore, when an epoxy resin with two or more epoxy groups is used, the degree of crosslinking with the amino group-containing styrene elastomer is sufficient, resulting in sufficient heat resistance.

[0024] The content of the epoxy resin is preferably 1 to 20 parts by mass per 100 parts by mass of the solid content of the adhesive composition. If the content of the epoxy resin is equal to or greater than the lower limit, the adhesive composition will cure sufficiently and good heat resistance and chemical resistance can be ensured. On the other hand, if the content of the epoxy resin is too high, adhesion will decrease, so if the content is equal to or less than the upper limit, good adhesion can be ensured.

[0025] The softening point or melting point of the epoxy resin is preferably 90°C or lower. When the softening point or melting point of the epoxy resin is 90°C or lower, the glass transition point of the adhesive composition can be lowered, the elastic modulus of the adhesive composition at high temperatures before curing can be lowered, and the elastic modulus of the adhesive composition at room temperature after curing can be increased. In addition, it is preferable that the epoxy resin is molten at the reaction temperature because the reaction is faster.

[0026] <Carboxy group-containing styrene elastomer> As described above, the adhesive composition of the present invention may contain a styrene-based elastomer other than the amino group-containing styrene-based elastomer, if necessary. Examples of styrene elastomers other than the amino group-containing styrene elastomer include carboxy group-containing styrene elastomers.

[0027] Carboxy group-containing styrene elastomers are effective as a component that imparts electrical properties in addition to adhesive properties and flexibility to the cured product. The adhesive composition contains a carboxyl group-containing styrene elastomer, which improves the adhesiveness of the adhesive layer. Furthermore, because the carboxyl group-containing styrene elastomer is reactive, the adhesive layer also improves its heat resistance and chemical resistance upon epoxy curing. The carboxyl group-containing styrene elastomer is a copolymer mainly consisting of block and random structures of a conjugated diene compound and an aromatic vinyl compound, or a hydrogenated product thereof modified with an unsaturated carboxylic acid. The conjugated diene compound and aromatic vinyl compound are as described above in the section <Styrenic elastomer containing amino group>.

[0028] The modification of a carboxyl group-containing styrene elastomer can be carried out, for example, by copolymerizing an unsaturated carboxylic acid during polymerization of the styrene elastomer, or by heating and kneading the styrene elastomer and the unsaturated carboxylic acid in the presence of an organic peroxide. Examples of the unsaturated carboxylic acid include acrylic acid, methacrylic acid, maleic acid, itaconic acid, fumaric acid, maleic anhydride, and itaconic anhydride. The amount of modification with the unsaturated carboxylic acid is preferably 0.1 to 10% by mass. The acid value of the carboxyl group-containing styrene elastomer is preferably 0.1 to 25 mgKOH / g, more preferably 0.5 to 23 mgKOH / g. When this acid value is 0.1 mgKOH / g or more, the adhesive composition cures sufficiently, and good adhesion and heat resistance are obtained. On the other hand, when the acid value is 25 mgKOH / g or less, excellent adhesive strength and electrical properties are obtained.

[0029] The weight-average molecular weight of the carboxyl group-containing styrene elastomer is preferably 10,000 to 500,000, more preferably 30,000 to 300,000, and even more preferably 50,000 to 200,000. If the weight-average molecular weight is equal to or greater than the lower limit, excellent adhesiveness can be exhibited, and the coatability when dissolved in a solvent and applied is also improved. If the weight-average molecular weight is equal to or less than the upper limit, compatibility with epoxy resins is improved.

[0030] Specific examples of carboxy group-containing styrene-based elastomers include those obtained by modifying styrene-butadiene block copolymers, styrene-ethylene propylene block copolymers, styrene-butadiene-styrene block copolymers, styrene-isoprene-styrene block copolymers, styrene-ethylenebutylene-styrene block copolymers, and styrene-ethylenepropylene-styrene block copolymers with unsaturated carboxylic acids. These carboxyl group-containing styrene elastomers may be used alone or in combination of two or more. Among the above copolymers, styrene-ethylenebutylene-styrene block copolymers and styrene-ethylenepropylene-styrene block copolymers are preferred from the viewpoints of adhesiveness and electrical properties. Furthermore, the mass ratio of styrene / ethylenebutylene in the styrene-ethylenebutylene-styrene block copolymer and the mass ratio of styrene / ethylenepropylene in the styrene-ethylenepropylene-styrene block copolymer are preferably 10 / 90 to 50 / 50, and more preferably 20 / 80 to 40 / 60. When the mass ratios are within these ranges, an adhesive composition with excellent adhesive properties can be obtained.

[0031] <Other ingredients> In addition to the above-mentioned amino group-containing styrene-based elastomer and epoxy resin, and optionally the carboxy group-containing styrene-based elastomer, the adhesive composition may contain other thermoplastic resins other than these styrene-based elastomers, tackifiers, flame retardants, curing agents, curing accelerators, coupling agents, heat aging inhibitors, leveling agents, antifoaming agents, inorganic fillers, pigments, solvents, and the like, to the extent that the functionality of the adhesive composition is not affected.

[0032] Among the other components, examples of the other thermoplastic resins include phenoxy resins, polyamide resins, polyester resins, polycarbonate resins, polyphenylene oxide resins, polyurethane resins, polyacetal resins, polyethylene-based resins, polypropylene-based resins, polyvinyl-based resins, etc. These thermoplastic resins may be used alone or in combination of two or more.

[0033] Examples of the tackifier include coumarone-indene resins, terpene resins, terpene-phenol resins, rosin resins, pt-butylphenol-acetylene resins, phenol-formaldehyde resins, xylene-formaldehyde resins, petroleum-based hydrocarbon resins, hydrogenated hydrocarbon resins, turpentine-based resins, etc. These tackifiers may be used alone or in combination of two or more.

[0034] The flame retardant may be either an organic flame retardant or an inorganic flame retardant. Examples of organic flame retardants include phosphorus-based flame retardants such as melamine phosphate, melamine polyphosphate, guanidine phosphate, guanidine polyphosphate, ammonium phosphate, ammonium polyphosphate, ammonium amido phosphate, ammonium amido polyphosphate, carbamate phosphate, carbamate polyphosphate, aluminum trisdiethylphosphinate, aluminum trismethylethylphosphinate, aluminum trisdiphenylphosphinate, zinc bisdiethylphosphinate, zinc bismethylethylphosphinate, zinc bisdiphenylphosphinate, titanyl bisdiethylphosphinate, titanium tetrakisdiethylphosphinate, titanyl bismethylethylphosphinate, titanium tetrakismethylethylphosphinate, titanyl bisdiphenylphosphinate, and titanium tetrakisdiphenylphosphinate; nitrogen-based flame retardants such as triazine-based compounds such as melamine, melam, and melamine cyanurate, cyanuric acid compounds, isocyanuric acid compounds, triazole-based compounds, tetrazole compounds, diazo compounds, and urea; and silicon-based flame retardants such as silicone compounds and silane compounds. Examples of inorganic flame retardants include metal hydroxides such as aluminum hydroxide, magnesium hydroxide, zirconium hydroxide, barium hydroxide, and calcium hydroxide; metal oxides such as tin oxide, aluminum oxide, magnesium oxide, zirconium oxide, zinc oxide, molybdenum oxide, and nickel oxide; zinc carbonate, magnesium carbonate, barium carbonate, zinc borate, and hydrated glass. Two or more of these flame retardants can be used in combination.

[0035] Examples of the curing agent include, but are not limited to, amine-based curing agents and acid anhydride-based curing agents. Examples of the amine-based curing agent include melamine resins such as methylated melamine resin, butylated melamine resin, and benzoguanamine resin, dicyandiamide, and 4,4'-diphenyldiaminosulfone. Examples of the acid anhydride include aromatic acid anhydrides and aliphatic acid anhydrides. These curing agents may be used alone or in combination of two or more. The content of the curing agent is preferably 0.05 to 100 parts by mass, and more preferably 5 to 70 parts by mass, relative to 100 parts by mass of the adhesive composition.

[0036] The curing accelerator is used for the purpose of accelerating the reaction between an amino group-containing styrene-based elastomer and an epoxy resin, or the reaction between epoxy resins themselves, and examples of the curing accelerator that can be used include tertiary amine-based curing accelerators, tertiary amine salt-based curing accelerators, and imidazole-based curing accelerators.

[0037] Examples of tertiary amine curing accelerators include benzyldimethylamine, 2-(dimethylaminomethyl)phenol, 2,4,6-tris(dimethylaminomethyl)phenol, tetramethylguanidine, triethanolamine, N,N'-dimethylpiperazine, triethylenediamine, and 1,8-diazabicyclo[5.4.0]undecene.

[0038] Examples of the tertiary amine salt curing accelerator include formate, octylate, p-toluenesulfonate, o-phthalate, phenolate, and phenol novolac resin salt of 1,8-diazabicyclo[5.4.0]undecene; and formate, octylate, p-toluenesulfonate, o-phthalate, phenolate, and phenol novolac resin salt of 1,5-diazabicyclo[4.3.0]nonene.

[0039] Imidazole-based curing accelerators include 2-methylimidazole, 2-undecylimidazole, 2-heptadecylimidazole, 1,2-dimethylimidazole, 2-methyl-4-ethylimidazole, 2-phenylimidazole, 2-phenyl-4-methylimidazole, 1-benzyl-2-methylimidazole, 1-benzyl-2-phenylimidazole, 2,4-diamino-6-[2'-methylimidazolyl-(1')]ethyl-s-triazine, 2,4-diamino-6-[2' 2,4-diamino-6-[2'-ethyl-4'-methylimidazolyl-(1')]ethyl-s-triazine, 2,4-diamino-6-[2'-ethyl-4'-methylimidazolyl-(1')]ethyl-s-triazine, 2,4-diamino-6-[2'-methylimidazolyl-(1')]ethyl-s-triazine isocyanuric acid adduct, 2-phenylimidazole isocyanuric acid adduct, 2-phenyl-4,5-dihydroxymethylimidazole, 2-phenyl-4-methyl-5-hydroxymethylimidazole, etc. These curing accelerators may be used alone or in combination of two or more.

[0040] When the adhesive composition contains a curing accelerator, the content of the curing accelerator is preferably 0.05 to 10 parts by mass, and more preferably 0.1 to 5 parts by mass, per 100 parts by mass of the adhesive composition. When the content of the curing accelerator is within the above range, the reaction between the amino group-containing styrene-based elastomer and the epoxy resin can proceed easily, making it easier to ensure adhesion and heat resistance.

[0041] Examples of the coupling agent include silane-based coupling agents such as vinyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, p-styryltrimethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, 3-acryloxypropyltrimethoxysilane, N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, 3-ureidopropyltriethoxysilane, 3-mercaptopropylmethyldimethoxysilane, bis(triethoxysilylpropyl)tetrasulfide, 3-isocyanatopropyltriethoxysilane, and imidazole silane; titanate-based coupling agents; aluminate-based coupling agents; and zirconium-based coupling agents. These may be used alone or in combination of two or more.

[0042] Examples of the heat aging inhibitor include 2,6-di-tert-butyl-4-methylphenol, n-octadecyl-3-(3',5'-di-tert-butyl-4'-hydroxyphenyl)propionate, tetrakis[methylene-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate]methane, pentaerythritol tetrakis[3-(3,5-di-t-butyl-4-hydroxyphenol], triethylene glycol-bis[3 Examples of antioxidants include phenol-based antioxidants such as 3-(3-t-butyl-5-methyl-4-hydroxyphenyl)propionate, sulfur-based antioxidants such as dilauryl-3,3'-thiodipropionate and dimyristyl-3,3'-dithiopropionate, and phosphorus-based antioxidants such as trisnonylphenyl phosphite and tris(2,4-di-tert-butylphenyl)phosphite. These antioxidants may be used alone or in combination of two or more.

[0043] Examples of the inorganic filler include powders of titanium oxide, aluminum oxide, zinc oxide, carbon black, silica, talc, copper, silver, etc. These may be used alone or in combination of two or more.

[0044] (adhesive layer) The adhesive layer of the present invention comprises the adhesive composition of the present invention. The adhesive composition that forms the adhesive layer is allowed to cure. The curing method is not particularly limited and can be appropriately selected depending on the purpose, and examples thereof include thermal curing. The thickness of the adhesive layer is not particularly limited and can be appropriately selected depending on the purpose, but is preferably 3 to 100 μm, more preferably 5 to 70 μm, and even more preferably 10 to 50 μm.

[0045] <Method of manufacturing adhesive layer> An adhesive layer can be produced by forming the adhesive composition into a film. The adhesive composition can be produced by mixing an amino group-containing styrene-based elastomer, an epoxy resin, and another elastomer (an elastomer other than an amino group-containing styrene-based elastomer), other components, and the like. The mixing method is not particularly limited as long as the adhesive composition is homogeneous. Since the adhesive composition is preferably used in the form of a solution or dispersion, a solvent is usually also used. Examples of solvents include alcohols such as methanol, ethanol, isopropyl alcohol, n-propyl alcohol, isobutyl alcohol, n-butyl alcohol, benzyl alcohol, ethylene glycol monomethyl ether, propylene glycol monomethyl ether, diethylene glycol monomethyl ether, and diacetone alcohol; ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, methyl amyl ketone, cyclohexanone, and isophorone; aromatic hydrocarbons such as toluene, xylene, ethylbenzene, and mesitylene; esters such as methyl acetate, ethyl acetate, ethylene glycol monomethyl ether acetate, and 3-methoxybutyl acetate; and aliphatic hydrocarbons such as hexane, heptane, cyclohexane, and methylcyclohexane. These solvents may be used alone or in combination of two or more. When the adhesive composition is a solution or dispersion (resin varnish) containing a solvent, it can be smoothly applied to a substrate film and an adhesive layer can be formed, and an adhesive layer of the desired thickness can be easily obtained. When the adhesive composition contains a solvent, the solid content is preferably 3 to 80% by mass, more preferably 10 to 50% by mass, from the viewpoint of workability including the formation of the adhesive layer. When the solid content is 80% by mass or less, the viscosity of the solution is appropriate, and uniform application is easy. In a more specific embodiment of the method for producing an adhesive layer, a resin varnish containing the adhesive composition and a solvent is applied to the surface of a substrate film to form a resin varnish layer, and then the solvent is removed from the resin varnish layer to form a B-stage adhesive layer. Here, the B-stage adhesive layer refers to an adhesive composition in an uncured state or a semi-cured state in which a portion of the adhesive composition has begun to cure, and refers to a state in which the curing of the adhesive composition progresses further by heating or the like. Here, the method for applying the resin varnish onto the substrate film is not particularly limited and can be appropriately selected depending on the purpose, and examples thereof include spraying, spin coating, dipping, roll coating, blade coating, doctor roll method, doctor blade method, curtain coating, slit coating, screen printing, inkjet method, and dispensing method. The adhesive layer in the B-stage state can be further subjected to heating or the like to form a cured adhesive layer.

[0046] <Characteristics of the adhesive layer>

[0047] The adhesive layer formed from the adhesive composition of the present invention has excellent adhesion (adhesion strength, also referred to as peel strength in the present invention) (N / cm) between the adherend and the substrate film after curing. As will be shown in the examples below, for example, when the peel force (N / cm) is measured during the after-cure step at 150°C after a lamination step at 120°C, excellent results are obtained. Here, the laminating step refers to a heating step in which the heating time is short in order to temporarily fix the adhesive layer to the adherend. Furthermore, an adhesive layer formed from the adhesive composition of the present invention exhibits excellent adhesive strength (also referred to as adhesive strength or peel strength) even when cured at a lower temperature. As shown in the examples below, for example, when a lamination process is performed at 120°C and then the peel strength (N / cm) is measured during an after-cure process at 120°C, an excellent peel strength is observed, close to the peel strength (N / cm) during an after-cure process at 150°C.

[0048] [Peel force (N / cm)] The peel strength is measured by cutting the adhesive laminate after curing at 120°C or 150°C into 25 mm wide test specimens, and measuring the peel strength when peeling the electrolytic copper foil from the adhesive-backed base film fixed to the support at a peel speed of 0.3 m / min and a peel angle of 180° in accordance with JIS Z0237:2009 (Test method for adhesive tapes and adhesive sheets).

[0049] The adhesive layer of the present invention obtained by curing the adhesive composition preferably has a relative dielectric constant (εr) of 3.5 or less and a dielectric loss tangent (tanδ) of 0.01 or less, measured at a frequency of 28 GHz. If the relative dielectric constant is 3.5 or less and the dielectric loss tangent is 0.01 or less, the material can be suitably used in FPC-related products, which have strict requirements for electrical properties.

[0050] [Dielectric constant and dielectric loss tangent] The relative dielectric constant and dielectric tangent of the adhesive layer can be measured using the open resonator method at a temperature of 23°C and a frequency of 28 GHz using a network analyzer MS46122B (manufactured by Anritsu) and an open resonator Fabry-Perot DPS-03 (manufactured by KEYCOM).

[0051] (Laminate) The laminate of the present invention comprises a substrate film and the above-described adhesive layer on at least one surface of the substrate film.

[0052] <Base film> The substrate film used in the present invention can be selected depending on the application of the laminate. For example, when the laminate is used as a coverlay film or a copper-clad laminate (CCL), examples of the substrate film include polyimide film, polyether ether ketone film, polyphenylene sulfide film, aramid film, polyethylene naphthalate film, and liquid crystal polymer film. Among these, polyimide film, polyether ether ketone (PEEK) film, polyethylene naphthalate film, and liquid crystal polymer film are preferred from the viewpoints of adhesiveness and electrical properties.

[0053] Furthermore, when the laminate of the present invention is used as a bonding sheet, the base film must be a release film, such as polyethylene terephthalate film, polyethylene film, polypropylene film, silicone release-treated paper, polyolefin resin-coated paper, TPX (polymethylpentene) film, and fluorine-based resin film.

[0054] When the laminate of the present invention is used as a shielding film, the substrate film must be a film having electromagnetic wave shielding properties, and examples thereof include a laminate of a protective insulating layer and a metal foil.

[0055] (Coverlay film) A preferred embodiment of the laminate according to the present invention is a coverlay film. When manufacturing FPCs, a laminate with an adhesive layer called a "coverlay film" is usually used to protect the wiring. This coverlay film has an insulating resin layer and an adhesive layer formed on its surface. For example, a coverlay film is a laminate in which the adhesive layer is formed on at least one surface of the base film, and peeling of the base film and the adhesive layer is generally difficult. The thickness of the base film included in the coverlay film is preferably 5 to 100 μm, more preferably 5 to 50 μm, and even more preferably 5 to 30 μm. If the thickness of the base film is equal to or less than the upper limit, the coverlay film can be made thinner. If the thickness of the base film is equal to or more than the lower limit, the printed wiring board can be easily designed and handled. As a method for producing a coverlay film, for example, a resin varnish containing the adhesive composition and a solvent is applied to the surface of the base film to form a resin varnish layer, and then the solvent is removed from the resin varnish layer, thereby producing a coverlay film having a B-stage adhesive layer formed thereon. The drying temperature when removing the solvent is preferably 40 to 250°C, more preferably 70 to 170°C. Drying is carried out by passing the laminate coated with the adhesive composition through a furnace in which hot air drying, far infrared heating, high frequency induction heating, or the like is performed. If necessary, a release film may be laminated on the surface of the adhesive layer for storage, etc. As the release film, known films such as polyethylene terephthalate film, polyethylene film, polypropylene film, silicone release-treated paper, polyolefin resin-coated paper, TPX film, and fluorine-based resin film can be used. The coverlay film according to the present invention uses the low-dielectric adhesive composition of the present invention, which enables high-speed transmission in electronic devices and also provides excellent adhesion stability to electronic devices.

[0056] (Bonding sheet) A preferred embodiment of the laminate according to the present invention is a bonding sheet. The bonding sheet is one in which the above-mentioned adhesive layer is formed on the surface of a release film (substrate film). The bonding sheet may also be in a form in which the adhesive layer is provided between two release films. When using the bonding sheet, the release film is peeled off. The release film may be the same as that described above in the (coverlay film) section. The thickness of the substrate film included in the bonding sheet is preferably 5 to 100 μm, more preferably 25 to 75 μm, and even more preferably 38 to 50 μm. If the thickness of the substrate film is within the above range, the bonding sheet is easy to manufacture and easy to handle. A bonding sheet can be produced, for example, by applying a resin varnish containing the adhesive composition and a solvent to the surface of a release film and drying it in the same manner as in the case of the coverlay film. The bonding sheet according to the present invention uses the low-dielectric adhesive composition of the present invention, which enables high-speed transmission in electronic devices and also provides excellent adhesive stability to electronic devices.

[0057] (Copper-clad laminate (CCL)) A preferred embodiment of the laminate according to the present invention is a copper-clad laminate obtained by laminating a copper foil to the adhesive layer in the laminate according to the present invention. A copper-clad laminate is formed by laminating a copper foil to the above-mentioned laminate, and is composed of, for example, a base film, an adhesive layer, and a copper foil in this order. The adhesive layer and the copper foil may be formed on both sides of the base film. The adhesive composition used in the present invention also has excellent adhesion to articles containing copper. The copper-clad laminate of the present invention uses the low-dielectric adhesive composition of the present invention, and therefore enables high-speed transmission in electronic devices and has excellent adhesive stability.

[0058] A method for producing a copper-clad laminate includes, for example, bringing the adhesive layer of the laminate and copper foil into surface contact, performing thermal lamination at 80°C to 150°C, and then curing the adhesive layer by after-curing. The after-curing conditions can be, for example, 100°C to 200°C in an inert gas atmosphere for 30 minutes to 4 hours. The copper foil is not particularly limited, and electrolytic copper foil, rolled copper foil, etc. can be used.

[0059] (Printed wiring board) A preferred embodiment of the laminate of the present invention is a printed wiring board obtained by laminating copper wiring to the adhesive layer in the laminate of the present invention. A printed wiring board can be obtained by forming an electronic circuit on the copper-clad laminate. The printed wiring board is formed by bonding a base film and copper wiring using the laminate, and is composed of the base film, adhesive layer, and copper wiring in that order. The adhesive layer and copper wiring may be formed on both sides of the base film. For example, a printed wiring board is manufactured by using a heat press or the like to attach a coverlay film via an adhesive layer to a surface having wiring portions. The printed wiring board according to the present invention uses the low-dielectric adhesive composition of the present invention, and therefore enables high-speed transmission in electronic devices and has excellent adhesive stability. The printed wiring board according to the present invention can be produced, for example, by contacting the adhesive layer of the laminate with copper wiring, performing thermal lamination at 80°C to 150°C, and then curing the adhesive layer by after-curing. The after-curing conditions can be, for example, 100°C to 200°C and 30 minutes to 4 hours. The shape of the copper wiring is not particularly limited, and may be selected as desired.

[0060] (Shielding film) A preferred embodiment of the laminate according to the present invention is a shielding film. Shielding film is a film used to shield various electronic devices, such as computers, mobile phones, and analytical equipment, in order to cut out electromagnetic noise that can affect these devices and cause them to malfunction. It is also called electromagnetic wave shielding film. The electromagnetic wave shielding film is formed by laminating, for example, an insulating resin layer, a metal layer, and the adhesive layer of the present invention in this order. The shielding film of the present invention uses the low-dielectric adhesive composition of the present invention, which enables high-speed transmission in electronic devices and also provides excellent adhesion stability to electronic devices.

[0061] (Printed wiring board with shielding film) A preferred embodiment of the laminate according to the present invention is a printed wiring board with a shielding film. A printed wiring board with a shielding film is a printed wiring board having a printed circuit provided on at least one surface of the substrate, and the electromagnetic wave shielding film is attached to the printed wiring board. A printed wiring board with a shielding film includes, for example, a printed wiring board, an insulating film adjacent to the surface of the printed wiring board on which the printed circuit is provided, and the electromagnetic wave shielding film. The printed wiring board with a shielding film according to the present invention uses the low-dielectric adhesive composition of the present invention, and therefore enables high-speed transmission in electronic devices and has excellent adhesive stability. [Example]

[0062] The present invention will be described in further detail below with reference to examples, but the scope of the present invention is not limited to these examples. In the following, parts and percentages are by weight unless otherwise specified.

[0063] (Amino group-containing styrene elastomer) The product used was "Tuftec MP10" (amine-modified styrene-ethylene-butylene-styrene copolymer) manufactured by Asahi Kasei Corporation. The styrene / ethylene-butylene ratio of this copolymer was 30 / 70, and the weight-average molecular weight was 78,000. The total nitrogen content in this copolymer was 426 ppm. (Amino group-containing styrene elastomer) The product used was "Tuftec MPLH-01" (amine-modified styrene-ethylene-butylene-styrene copolymer) manufactured by Asahi Kasei Corporation. The styrene / ethylene-butylene ratio of this copolymer was 20 / 80, and the weight-average molecular weight was 100,000. The total nitrogen content in this copolymer was 432 ppm. (Amino group-containing styrene elastomer) The product used was "Tuftec MPHF-02" (amine-modified styrene-ethylene-butylene-styrene copolymer) manufactured by Asahi Kasei Corporation. The styrene / ethylene-butylene ratio of this copolymer was 30 / 70, and the weight-average molecular weight was 68,000. The total nitrogen content in this copolymer was 496 ppm. (Carboxylic group-containing styrene elastomer) We used "Tuftec M1911" (maleic acid-modified styrene-ethylene butylene-styrene block copolymer) manufactured by Asahi Kasei Corporation. The copolymer had an acid value of 2 mg KOH / g, a styrene / ethylene butylene ratio of 30 / 70, and a weight-average molecular weight of 69,000. (Carboxylic group-containing styrene elastomer) We used "Tuftec M1913" (maleic acid-modified styrene-ethylene butylene-styrene block copolymer) manufactured by Asahi Kasei Corporation. The copolymer had an acid value of 10 mg KOH / g, a styrene / ethylene butylene ratio of 30 / 70, and a weight-average molecular weight of 67,000. (styrene elastomer) Kraton G1651 (styrene-ethylenebutylene-styrene block copolymer) manufactured by Kraton was used. The copolymer had an acid value of 0 mgKOH / g, a styrene / ethylenebutylene ratio of 33 / 67, and a weight-average molecular weight of 136,700. (epoxy resin) As the epoxy resin, a novolac type epoxy resin, trade name "YX7700" (softening point 65°C) manufactured by Mitsubishi Chemical Corporation, was used. (epoxy resin) As the epoxy resin, a glycidylamine type epoxy resin, trade name "jER604" (liquid epoxy) manufactured by Mitsubishi Chemical Corporation, was used. (epoxy resin) The epoxy resin used was "jER1031S" (softening point 92°C) manufactured by Mitsubishi Chemical Corporation. (epoxy resin) The epoxy resin used was "Epofriend CT310" (epoxidized styrene-butadiene block copolymer) manufactured by Daicel Corporation. The styrene / ethylene-butylene ratio of this copolymer was 40 / 60, the weight-average molecular weight was 93,000, and the epoxy equivalent was 2125 g / eq. (solvent) A mixed solvent of toluene and methyl ethyl ketone (mass ratio = 90:10) was used. (Base film) As the substrate film, "Shin-Etsu Sepla Film PEEK" (polyether ether ketone, thickness 50 μm) manufactured by Shin-Etsu Polymer Co., Ltd. was used. (electrolytic copper foil) The electrolytic copper foil used was "TQ-M7-VSP" manufactured by Mitsui Mining & Smelting Co., Ltd. (electrolytic copper foil, thickness 12 μm, shiny side Rz 1.27 μm, shiny side Ra 0.197 μm, shiny side Rsm 12.95 μm). The surface roughness of the shiny side was measured using a laser microscope and calculated from the roughness curve in accordance with JIS B 0601:2013 (ISO 4287:1997 Amd.1:2009). (Release film) As the release film, NP75SA (silicone release PET film, 50 μm) manufactured by Panac Corporation was used.

[0064] (Nitrogen content measurement) The total amount of nitrogen contained in the amino group-containing styrene elastomer used in the examples was determined by the following method. <Measurement method> The nitrogen concentration was measured using a trace nitrogen analyzer ND-100 (manufactured by Mitsubishi Chemical Corporation) in accordance with JIS-K2609.

[0065] Example 1 <150℃ curing process> The components constituting the adhesive layer shown in Table 1 were contained in the proportions shown in Table 1, and these components were dissolved in a solvent to prepare a resin varnish with a solid content concentration of 20 mass %. The surface of the substrate film was subjected to a corona treatment. The resin varnish was applied to the surface of a substrate film, dried in an oven at 110°C for 4 minutes, and the toluene was volatilized to form an adhesive layer, resulting in an adhesive-attached substrate film. The adhesive layer of the adhesive laminate was placed in contact with the shiny side of the electrolytic copper foil, and thermal lamination was performed at 120°C to obtain a pre-cured adhesive laminate. The pre-cured adhesive laminate was further after-cured at 150°C for 60 minutes to cure the adhesive layer, resulting in a cured adhesive laminate. The peel strength (N / cm) between the electrolytic copper foil and the base film of the adhesive laminate of Example 1 after curing at 150°C was measured.

[0066] <120℃ curing process> Using the same adhesive composition as in the above <150°C curing step> (containing the components constituting the adhesive layer shown in Table 1 in the proportions shown in Table 1), these components were dissolved in a solvent to prepare a resin varnish. The resin varnish was applied to the surface of a substrate film, dried in an oven at 110°C for 4 minutes, and the toluene was volatilized to form an adhesive layer, resulting in an adhesive-attached substrate film. The adhesive layer of the adhesive laminate was placed in contact with the shiny side of the electrolytic copper foil, and thermal lamination was performed at 120°C to obtain a pre-cured adhesive laminate. The pre-cured adhesive laminate was further after-cured at 120°C for 30 minutes to cure the adhesive layer, resulting in a cured adhesive laminate. The peel strength (N / cm) between the electrolytic copper foil and the base film of the adhesive laminate of Example 1 after curing at 120°C was measured.

[0067] [Peel force (N / cm)] The peel strength was measured by cutting the adhesive laminate after curing at 120°C or 150°C into 25 mm wide test specimens, and in accordance with JIS Z0237:2009 (Test methods for adhesive tapes and adhesive sheets), peel strength was measured when peeling the electrolytic copper foil from the adhesive-attached substrate film fixed to the support at a peel speed of 0.3 m / min and a peel angle of 180°.

[0068] Furthermore, the relative dielectric constant and dielectric loss tangent at a frequency of 28 GHz of the adhesive layer in the laminate of Example 1 were also measured.

[0069] [Dielectric constant and dielectric loss tangent] The dielectric constant and dielectric loss tangent of the adhesive layer were measured using an open-type resonator (open-type resonator) with a network analyzer MS46122B (manufactured by Anritsu) and a Fabry-Perot DPS-03 (manufactured by KEYCOM) at a temperature of 23°C and a frequency of 28 GHz. The measurement sample was prepared by roll-coating a resin varnish onto a release film. The coated film was then placed in an oven and dried at 110°C for 4 minutes to form a B-stage adhesive layer (50 μm thick). The adhesive layers were then thermally laminated at 120°C so that the adhesive surfaces were in contact with each other to form a pre-cured adhesive film (100 μm thick). This pre-cured adhesive film (100 μm thick) was then placed in an oven and heat-cured at 150°C for 60 minutes to produce a cured adhesive film (100 mm x 100 mm). After curing, the release film was peeled off from the adhesive film, and the relative dielectric constant and dielectric loss tangent of the adhesive layer were measured.

[0070] [Acid resistance] The cured adhesive laminate of Example 1 was cut into 30×30 mm test pieces, which were then immersed in a 10% aqueous sulfuric acid solution for 3 hours to perform an acid resistance test. The acid resistance of the copper clad laminate (CCL) having the adhesive layer of the present invention was evaluated according to the following evaluation criteria. A: No peeling occurs. Excellent acid resistance. B: Some peeling is observed at the corners. Acid resistance is good. Peeling is also observed on edge C. Acid resistance is poor.

[0071] [Base resistance] The cured adhesive laminate of Example 1 was cut into 30 x 30 mm test pieces, which were then immersed in a 10% aqueous sodium hydroxide solution for 3 hours to perform a base resistance test. The base resistance of the copper clad laminate (CCL) having the adhesive layer of the present invention was evaluated according to the following evaluation criteria. A: No peeling occurs. Excellent base resistance. Some peeling is observed at corner B. Base resistance is good. Peeling is also observed on side C. Base resistance is poor.

[0072] The measurement results are shown in Table 1.

[0073] Example 2 , Example 4, Reference Examples 5-6, Example 7- Example 10) Example 2 was prepared in the same manner as Example 1, except that the types and amounts of the components constituting the adhesive layer in Example 1 were changed as shown in Table 1. , Example 4, Reference Examples 5-6, Example 7- A laminate of Example 10 was prepared. The laminate thus produced was evaluated in the same manner as in Example 1. The results are shown in Table 1.

[0074] (Comparative Examples 1 to 4) Laminates of Comparative Examples 1 to 4 were prepared in the same manner as in Example 1, except that the types and amounts of components constituting the adhesive layer were changed as shown in Table 1. The laminate thus produced was evaluated in the same manner as in Example 1. The results are shown in Table 1.

[0075] [Table 1]

[0076] This application claims priority from Japanese Patent Application No. 2019-231643, filed on December 23, 2019, and incorporates the entire contents of that Japanese patent application by reference. [Industrial Applicability]

[0077] Laminates having an adhesive layer made of the adhesive composition of the present invention can be suitably used in the production of FPC-related products for electronic devices such as smartphones, mobile phones, optical modules, digital cameras, game consoles, laptops, and medical devices.

Claims

1. An adhesive layer comprising an adhesive composition, The adhesive composition comprises: The composition contains an amino group-containing styrene-based elastomer and an epoxy resin, The weight average molecular weight of the amino group-containing styrene elastomer is 50,000 to 200,000, The epoxy resin has a softening point or melting point of 90°C or less, the epoxy resin is a novolac epoxy resin or a styrene-butadiene block copolymer epoxy compound; the content of the amino group-containing styrene-based elastomer is 25.0 to 99.0 parts by mass per 100 parts by mass of the solid content of the adhesive composition; the content of the epoxy resin is 1 to 20 parts by mass per 100 parts by mass of the solid content of the adhesive composition, The adhesive layer has a relative dielectric constant of 3.5 or less and a dielectric loss tangent of 0.01 or less at a frequency of 28 GHz, as measured on a cured adhesive film obtained by heat-curing the adhesive layer at 150°C for 60 minutes.

2. 2. The adhesive layer according to claim 1, wherein the total nitrogen content in the amino group-containing styrene-based elastomer is 50 to 5,000 ppm.

3. A base film; A laminate comprising the adhesive layer according to any one of claims 1 to 2.

4. The laminate according to claim 3 , wherein the substrate film contains a polyether ether ketone (PEEK) resin.

5. A coverlay film with an adhesive layer, comprising the laminate according to claim 3 or 4.

6. A copper clad laminate comprising the laminate according to claim 3 or 4.

7. A printed wiring board comprising the laminate according to claim 3 or 4.

8. A shielding film comprising the laminate according to claim 3 or 4.

9. A printed wiring board with a shielding film, comprising the laminate according to claim 3 or 4.

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