JP2023132499A - Adhesive composition, and laminate with adhesive layer - Google Patents

Abstract

To provide an adhesive composition which is excellent in handling property, obtains a cured film having a sufficiently high dielectric constant and flexibility, and is also excellent in adhesive force to an adherend, and a laminate with an adhesive layer using the adhesive composition.SOLUTION: An adhesive composition contains a carboxy group-containing styrenic elastomer (A), an epoxy resin (B), and a titanate compound (C), wherein in a total solid content, a content of the carboxy group-containing styrenic elastomer (A) is 6 mass% or more, and a dielectric constant of a cured product after curing reaction is 3.8 or more.SELECTED DRAWING: None

Description

The present invention relates to an adhesive composition and a laminate with an adhesive layer.

Capacitive sensors are used for touch sensors, fingerprint authentication, product inspection, etc. For example, in fingerprint authentication, a semiconductor sensor element is provided on a substrate, and the difference in capacitance that occurs depending on the distance between the minute unevenness of the fingerprint and the sensor element is detected. In such a capacitive sensor, the sensor element is generally sealed and protected by a sealing material, but this sealing material causes a decrease in the sensitivity of the sensor. In order to prevent the sensitivity of the sensor from decreasing, it has been proposed to mix a high dielectric inorganic filler into the encapsulant to increase the dielectric constant of the encapsulant (for example, Patent Document 1).
Various compositions are known as encapsulating materials for electronic components, and among them, curable epoxy adhesives are widely used.

Japanese Patent Application Publication No. 2018-141052

By combining an epoxy adhesive and a high dielectric inorganic filler, the resulting sealant (cured film) can exhibit a high dielectric constant and a high modulus of elasticity. However, the present inventors have investigated that these sealants have poor flexibility, may not exhibit sufficient adhesive strength (peel strength), and furthermore, the adhesive may not be able to be used in liquid form before it hardens. It has been found that the viscosity tends to increase and problems with handling are also likely to occur.

The present invention aims to provide an adhesive composition that has excellent handling properties, the obtained cured film exhibits a sufficiently high dielectric constant, the cured film also has flexibility, and has excellent adhesive strength to adherends. Take it as a challenge. Another object of the present invention is to provide a laminate with an adhesive layer using this adhesive composition.

The above problem of the present inventors is solved by the following means.
[1]
Including a carboxyl group-containing styrenic elastomer (A), an epoxy resin (B), and a titanic acid compound (C),
The content of the carboxy group-containing styrenic elastomer (A) in the total solid content is 6% by mass or more,
An adhesive composition having a dielectric constant of 3.8 or more after a curing reaction.
[2]
The adhesive composition according to [1], wherein the titanic acid compound (C) has a dielectric constant of 100 or more.
[3]
The adhesive according to [1] or [2], wherein the content of the titanic acid compound (C) is 70 to 1100 parts by mass based on 100 parts by mass of the carboxy group-containing styrenic elastomer (A). agent composition.
[4]
The adhesive composition according to any one of [1] to [3], wherein the titanate compound (C) is at least one of barium titanate, strontium titanate, and calcium titanate.
[5]
The adhesive composition according to any one of [1] to [4], which contains a silane coupling agent.
[6]
The adhesive composition according to any one of [1] to [5], wherein the carboxy group-containing styrenic elastomer (A) has an acid value of 0.1 to 35 mgKOH/g.
[7]
The carboxyl group-containing styrene elastomer (A) is a styrene-butadiene block copolymer, a styrene-ethylene propylene block copolymer, a styrene-butadiene-styrene block copolymer, a styrene-isoprene-styrene block copolymer, or a styrene block copolymer. - Any one of [1] to [6], which is a modified product of at least one of ethylene butylene-styrene block copolymer and styrene-ethylene propylene-styrene block copolymer with an unsaturated carboxylic acid compound The adhesive composition described in .
[8]
The adhesive composition according to any one of [1] to [7], wherein the epoxy resin (B) is a polyfunctional epoxy resin having an alicyclic skeleton.
[9]
Any one of [1] to [8], wherein the content of the epoxy resin (B) is 0.5 to 30 parts by mass based on 100 parts by mass of the carboxy group-containing styrenic elastomer (A). Adhesive composition according to one.
[10]
A laminate with an adhesive layer, comprising a base film and an adhesive layer made of the adhesive composition according to any one of [1] to [9].

In the present invention and this specification, a numerical range expressed using "~" means a range that includes the numerical values written before and after "~" as lower and upper limits. For example, when "A to B" is written, the numerical range is "A to B".

In the present invention and this specification, the term "adhesive layer" refers to a state before curing, a state in the B stage (that is, a state in which it is in a semi-cured state where a part has begun to harden, and where the curing further progresses by heating etc.) ), or a layer after a curing reaction has proceeded to sufficiently form a crosslinked structure. In addition, the term "cured product" or "cured film" refers to a product or film that has been cured by curing the adhesive composition to sufficiently form a crosslinked structure.

The adhesive composition of the present invention has excellent handling properties, the resulting cured film exhibits a sufficiently high dielectric constant, the cured film also has flexibility, and has excellent adhesive strength to adherends. In addition, in the laminate with an adhesive layer of the present invention, the cured film obtained by curing the adhesive layer exhibits a sufficiently high dielectric constant, and this cured film also has flexibility and has good adhesive strength to the adherend. Also excellent.

Preferred embodiments of the adhesive composition of the present invention will be described below, but the present invention is not limited to the following embodiments except as specified in the present invention.

[Adhesive composition]
The adhesive composition of the present invention contains a carboxyl group-containing styrenic elastomer (A), an epoxy resin (B), and a titanic acid compound (C), and the carboxyl group-containing styrenic elastomer ( The content of A) is 6% by mass or more, and the dielectric constant of the cured product after the curing reaction is 3.8 or more. Each component constituting the adhesive composition of the present invention will be explained in order.

<Carboxy group-containing styrenic elastomer (A)>
The adhesive composition of the present invention contains one or more carboxy group-containing styrenic elastomers as the carboxy group-containing styrenic elastomer (A). The carboxyl group-containing styrenic elastomer (A) is one of the base resins of the adhesive composition, and in addition to the adhesiveness and flexibility of the cured product, the interaction with the titanic acid compound (C) It is a component that effectively brings out the high dielectric properties of the titanic acid compound (C) as electrical properties of the adhesive composition. The carboxyl group-containing styrene elastomer (A) can be synthesized by a conventional method. Alternatively, commercially available products may be used. The carboxyl group-containing styrene elastomer (A) will be explained in more detail.

There are no particular limitations on the carboxyl group-containing styrenic elastomer (A) used in the present invention. A wide variety of compounds modified with acid compounds can be used. Examples of the conjugated diene compound include butadiene, isoprene, 1,3-pentadiene, and 2,3-dimethyl-1,3-butadiene. Examples of styrene compounds include styrene, t-butylstyrene, α-methylstyrene, p-methylstyrene, divinylbenzene, 1,1-diphenylstyrene, N,N-diethyl-p-aminoethylstyrene, and vinyltoluene. or p-tert-butylstyrene.

The carboxyl group-containing styrenic elastomer (A) can be obtained, for example, by copolymerizing an unsaturated carboxylic acid compound during polymerization of the styrene elastomer. Alternatively, the styrene elastomer can be graft-modified by heating and kneading the styrene elastomer and an unsaturated carboxylic acid compound in the presence of an organic peroxide.
Examples of the unsaturated carboxylic acid compound include acrylic acid, methacrylic acid, maleic acid, itaconic acid, fumaric acid, maleic anhydride, itaconic anhydride, and fumaric anhydride. That is, in the present invention, "containing a carboxy group" includes all forms containing a carboxy group, a form containing a carboxylic acid anhydride group, and a form containing both a carboxyl group and a carboxylic acid anhydride group. It is.
The proportion of the structure derived from the unsaturated carboxylic acid compound in the carboxyl group-containing styrenic elastomer (A) is preferably 0.1 to 10% by mass.

The acid value of the carboxyl group-containing styrene elastomer (A) is preferably 0.1 to 35 mgKOH/g, and 0.1 to 32 mgKOH/g from the viewpoint of curing reactivity, adhesiveness, heat resistance, and electrical properties. It is more preferably 0.1 to 25 mgKOH/g, even more preferably 0.5 to 23 mgKOH/g. The above-mentioned "acid value" means the number of mg of KOH required to neutralize the acid present in 1 g of the carboxyl group-containing styrene elastomer (A).
In the present invention, the acid value of the carboxyl group-containing styrenic elastomer (A) means a value measured according to JIS K 0070:1992.

The weight average molecular weight of the carboxyl group-containing styrenic elastomer (A) is preferably 10,000 to 500,000, more preferably 30,000 to 300,000, and even more preferably 50,000 to 200,000. When the weight average molecular weight is within the above range, the adhesive composition can exhibit excellent adhesive properties and electrical properties. The above-mentioned "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.

Specific examples of the styrene elastomer (A) include styrene-butadiene block copolymer, styrene-ethylene propylene block copolymer, styrene-butadiene-styrene block copolymer, and styrene-isoprene block copolymer. Examples include styrene block copolymer, styrene-ethylenebutylene-styrene block copolymer, and styrene-ethylenepropylene-styrene block copolymer. Modified products of these styrenic elastomers with unsaturated carboxylic acid compounds can be used as the carboxy group-containing styrene elastomer (A). These carboxyl group-containing styrene elastomers (A) may be used alone or in combination of two or more. Among the above copolymers, from the viewpoint of adhesiveness and electrical properties, at least one of styrene-ethylenebutylene-styrene block copolymers and styrene-ethylenepropylene-styrene block copolymers is modified with an unsaturated carboxylic acid compound. Preferably.
Mass ratio of styrene component and ethylene butylene component in the above styrene-ethylene butylene-styrene block copolymer (styrene component/ethylene butylene component), and styrene component and ethylene propylene component in the styrene-ethylene propylene-styrene block copolymer The mass ratio (styrene component/ethylene propylene component) is preferably 10/90 to 50/50, more preferably 20/80 to 40/60, from the viewpoint of further improving adhesiveness.

The content of the carboxy group-containing styrene elastomer (A) is 6% by mass or more, preferably 6 to 75% by mass, and more preferably content in the total solid content of the adhesive composition (components excluding the solvent). Listed in order of amount, they are 7 to 70% by weight, 10 to 65% by weight, 12 to 60% by weight, and 15 to 55% by weight.

<Epoxy resin (B)>
The adhesive composition of the present invention contains one or more epoxy resins as the epoxy resin (B). The epoxy resin (B) plays the role of a crosslinking agent that cures the carboxyl group-containing styrenic elastomer (A). There is no particular restriction on the type of epoxy resin (B), and epoxy resins used in epoxy adhesives can be widely used.

Examples of epoxy resin (B) are:
Bisphenol A type epoxy resin, bisphenol F type epoxy resin, or hydrogenated products thereof;
Orthophthalic 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, sebacate acid diglycidyl ester , or glycidyl ester-based epoxy resin such as trimellitic acid triglycidyl ester;
Ethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, 1,4-butanediol diglycidyl ether, 1,6-hexanediol diglycidyl ether, trimethylolpropane triglycidyl ether, pentaerythritol tetraglycidyl ether, tetraphenyl glycidyl ether ether , triphenylglycidyl ether ethane, polyglycidyl ether of sorbitol, or polyglycidyl ether of polyglycerol;
Glycidylamine-based epoxy resins such as triglycidyl isocyanurate or tetraglycidyldiaminodiphenylmethane;
Linear aliphatic epoxy resins such as epoxidized polybutadiene or epoxidized soybean oil;
Examples of the epoxy resin (B) include novolak epoxy resins such as phenol novolac epoxy resins, o-cresol novolac epoxy resins, or bisphenol A novolac epoxy resins;
etc., but are not limited to these.

Examples of the epoxy resin (B) include brominated bisphenol A epoxy resin, phosphorus-containing epoxy resin, dicyclopentadiene skeleton-containing epoxy resin, naphthalene skeleton-containing epoxy resin, anthracene-type epoxy resin, and tert-butylcatechol-type epoxy resin. , triphenylmethane type epoxy resin, tetraphenylethane type epoxy resin, biphenyl type epoxy resin, bisphenol S type epoxy resin, etc. can also be used.

If an epoxy resin (B) having two or more epoxy groups in one molecule (herein sometimes referred to as a "multifunctional epoxy resin") is used, it may be difficult to combine with the carboxyl group-containing styrene elastomer. A sufficient crosslinked structure can be formed through the reaction, and high heat resistance can be expressed.

The above epoxy resins may be used alone or in combination of two or more.
Among the above epoxy resins, epoxy resins without glycidylamino groups are preferred from the viewpoint of improving the storage stability of the laminate with an adhesive layer. Moreover, since an adhesive composition with excellent electrical properties can be obtained, an epoxy resin having an alicyclic skeleton is preferable, and an epoxy resin having a dicyclopentadiene skeleton is particularly preferable. Moreover, since an adhesive composition having excellent electrical properties and heat resistance can be obtained, a polyfunctional epoxy resin having an alicyclic skeleton is preferable, and a polyfunctional epoxy resin having a dicyclopentadiene skeleton is particularly preferable.

The content of the epoxy resin (B) contained in the adhesive composition of the present invention is 0.5 to 30 parts by mass based on 100 parts by mass of the carboxyl group-containing styrenic elastomer (A) from the viewpoint of crosslinking point density and heat resistance. It is preferably 1 to 25 parts by weight, even more preferably 1.5 to 20 parts by weight, and particularly preferably 2 to 15 parts by weight.

<Titanic acid compound (C)>
The adhesive composition of the present invention contains one or more titanic acid compounds as the titanic acid compound (C). The titanic acid compound (C) is an inorganic filler contained in particulate form in the adhesive composition of the present invention. Examples of the titanate compound (C) include barium titanate, strontium titanate, calcium titanate, magnesium titanate, neodymium titanate, bismuth titanate, lead titanate, nickel titanate, zinc titanate, and zirconate titanate. Examples include barium, lead zirconate titanate, and at least one of barium titanate, strontium titanate, and calcium titanate is preferred.

In the adhesive composition of the present invention, the content of the titanic acid compound (C) is equal to the content of the carboxy group-containing styrenic elastomer (A), considering not only high dielectricity and good adhesiveness but also coatability. The content is preferably 70 to 1100 parts by mass per 100 parts by mass, and the more preferred contents are 80 to 1000 parts by mass, 100 to 900 parts by mass, and 120 to 800 parts by mass. 150 to 700 parts by mass.

The dielectric constant (ε) of the titanate compound (C) can be estimated from the dielectric properties of a sintered body obtained by heating and firing the titanate compound (C), for example. The dielectric properties of the sintered body are measured by the following procedure. After preparing a paste-like composition by mixing the titanic acid compound (C) with polyvinyl alcohol and water, it is filled into a pellet molding machine and dried to obtain a pellet-like solid. By heating and firing the pellet-like solid to, for example, about 900 to 1200°C, the binder resin is decomposed and removed, and the titanic acid compound (C) is sintered to obtain sintered pellets. . Upper and lower electrodes are formed on this sintered pellet, and the capacitance is measured according to JIS K 6911:2006. Calculate the dielectric constant (ε) from the capacitance and the dimensions of the sintered pellet.

The dielectric constant (ε) (measurement frequency: 1 MHz) of the titanic acid compound (C) is preferably 100 or more, more preferably 120 or more, and even more preferably 150 or more. The upper limit of the dielectric constant (ε) of the titanate compound (C) is not particularly limited, and is usually 15,000 or less.

The adhesive composition according to the present invention contains a combination of a carboxyl group-containing styrenic elastomer (A), an epoxy resin (B), and a titanic acid compound (C), and also contains a carboxyl group-containing styrenic elastomer (A). ) by controlling the content above a specific amount, the increase in liquid viscosity of the adhesive composition is suppressed, resulting in excellent handling properties. It exhibits strong adhesion to the body and can also achieve a higher dielectric constant. Furthermore, the flexibility of the cured film can be ensured, making it possible to apply it to flexible devices.

By containing the carboxy group-containing styrene elastomer as a base resin, the adhesive composition of the present invention not only improves adhesiveness and flexibility of the cured product, but also improves the titanic acid compound (C) by interaction with the titanic acid compound (C). The high dielectric properties of compound (C) can be effectively brought out as electrical properties of the adhesive composition. The reason for this is not clear, but due to the polarity of the structure (carboxy group) unique to carboxy group-containing styrenic elastomers, titanic acid compounds have a high dielectric constant and small particle size. This is thought to be due to the fact that it can be uniformly dispersed in this state.

<Curing accelerator>
The adhesive composition of the present invention preferably contains a curing accelerator. The curing accelerator is used for the purpose of accelerating the reaction between the carboxyl group-containing styrene elastomer (A) and the epoxy resin (B). Examples of the curing accelerator include tertiary amine curing accelerators, tertiary amine salt curing accelerators, imidazole curing accelerators, and the like.
Examples of the tertiary amine curing accelerator include benzyldimethylamine, 2-(dimethylaminomethyl)phenol, 2,4,6-tris(dimethylaminomethyl)phenol, tetramethylguanidine, triethanolamine, N, Examples include N'-dimethylpiperazine, triethylenediamine, and 1,8-diazabicyclo[5.4.0]undecene.
Examples of the tertiary amine salt curing accelerator include formate, octylate, p-toluenesulfonate, o-phthalate, phenol salt or 1,8-diazabicyclo[5.4.0]undecene. phenol novolac resin salt,
Further examples include formate, octylate, p-toluenesulfonate, o-phthalate, phenol salt, or phenol novolac resin salt of 1,5-diazabicyclo[4.3.0]nonene.
Examples of imidazole-based curing accelerators include 2-methylimidazole, 2-undecylimidazole, 2-heptadecyl imidazole, 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'-undecylimidazolyl-(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- Examples include phenyl-4,5-dihydroxymethylimidazole and 2-phenyl-4-methyl-5-hydroxymethylimidazole. The above-mentioned curing accelerators may be used alone or in combination of two or more.

The content of the curing accelerator may be appropriately set depending on the type of curing accelerator. The content of the curing accelerator is preferably 0.01 to 1.0 parts by mass, more preferably 0.03 to 0.5 parts by mass, per 100 parts by mass of the carboxyl group-containing styrenic elastomer (A). More preferably 0.05 to 0.4 parts by mass. When the content of the curing accelerator is within the above range, it has excellent adhesiveness and heat resistance.

<Coupling agent>
The adhesive composition of the present invention preferably contains a coupling agent. As the above coupling agent,
Vinyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, p-styryltrimethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, 3-acryloxypropyltrimethoxysilane, N-2-(aminoethyl)-3 - Silanes such as aminopropylmethyldimethoxysilane, 3-ureidopropyltriethoxysilane, 3-mercaptopropylmethyldimethoxysilane, bis(triethoxysilylpropyl)tetrasulfide, 3-isocyanatepropyltriethoxysilane, or imidazolesilane system coupling agent;
titanate coupling agent, aluminate coupling agent, or zirconium coupling agent;
etc.
The above-mentioned coupling agents may be used alone or in combination of two or more.

The content of the coupling agent is preferably 0.2 to 3.0 parts by mass, and preferably 0.5 to 2.0 parts by mass, based on 100 parts by mass of the carboxy group-containing styrene elastomer (A). Parts by mass are more preferable.

<Characteristics of adhesive composition>
In the adhesive composition according to the present invention, the dielectric constant of the cured product after the curing reaction is 3.8 or more, preferably 4.0 or more, more preferably 6.0 or more, and still more preferably 8 .0 or more, particularly preferably 10.0 or more. The upper limit of the dielectric constant is not particularly limited, but is usually 100.0 or less, may be 80.0 or less, may be 60.0 or less, or may be 40.0 or less. good.
In the present invention, the dielectric constant of the cured product of the adhesive composition refers to the dielectric constant in the range of 3.8 to 80 measured by the dielectric resonator method (SPDR method) at a temperature of 23°C and a frequency of 10 GHz. means the value given. However, this measurement method is not applicable depending on the measurement frequency, dielectric constant, and dielectric loss tangent when the dielectric constant exceeds 80.

The peel strength of the cured product of the adhesive composition according to the present invention is preferably 9.0 N/cm or more, more preferably 10.0 N/cm or more. Peel strength can be determined by the method described in the "Examples" section below.

The liquid viscosity of the adhesive composition according to the present invention is preferably 300 to 60,000 mPa·s, more preferably 500 to 50,000 mPa·s, even more preferably 1,000 to 45,000 mPa·s, and even more preferably 1,500 to 45,000 mPa·s. Particularly preferred is 40,000 mPa·s. Liquid viscosity can be determined by the method described in the "Examples" section below.

The elastic modulus of the cured product of the adhesive composition according to the present invention is preferably 0.02 to 2.00 GPa, more preferably 0.04 to 1.80 GPa, and 0.06 to 1.50 GPa. More preferably, it is 0.08 to 1.20 GPa, particularly preferably 0.08 to 1.20 GPa. The elastic modulus (tensile test) can be determined by the method described in the "Examples" section below.

<Other ingredients>
In addition to the above-mentioned components, the adhesive composition includes thermoplastic resins other than the carboxy group-containing styrene elastomer (A), tackifiers, flame retardants, curing agents, heat aging inhibitors, and leveling agents. , an antifoaming agent, a filler different from the titanic acid compound (C), a pigment, a solvent, etc. can be contained to the extent that they do not affect the functions of the adhesive composition.

Examples of the other thermoplastic resins include phenoxy resin, polyamide resin, polyester resin, polycarbonate resin, polyphenylene oxide resin, polyurethane resin, polyacetal resin, polyethylene resin (polyethylene compound), polypropylene resin (polypropylene compound), or Examples include polyvinyl resin (polyvinyl compound). These thermoplastic resins may be used alone or in combination of two or more.

Examples of the tackifier include coumaron-indene resin, terpene resin, terpene-phenol resin, rosin resin, pt-butylphenol-acetylene resin, phenol-formaldehyde resin, xylene-formaldehyde resin, petroleum hydrocarbon resin, Examples include hydrogenated hydrocarbon resins and turpentine resins (turpentine compounds). These tackifiers may be used alone or in combination of two or more.

The flame retardant may be either an organic flame retardant or an inorganic flame retardant. Examples of organic flame retardants include:
Melamine phosphate, melamine polyphosphate, guanidine phosphate, guanidine polyphosphate, ammonium phosphate, ammonium polyphosphate, ammonium phosphate amide, ammonium polyphosphate amide, phosphate carbamate, polyphosphate carbamate, tris-diethyl phosphinate aluminum, tris-methyl Aluminum ethylphosphinate, aluminum trisdiphenylphosphinate, zinc bisdiethylphosphinate, zinc bismethylethylphosphinate, zinc bisdiphenylphosphinate, titanyl bisdiethylphosphinate, titanium tetrakisdiethylphosphinate, titanyl bismethylethylphosphinate, tetrakis Phosphorous flame retardants such as titanium methylethylphosphinate, titanyl bisdiphenylphosphinate, or titanium tetrakisdiphenylphosphinate;
Triazine compounds such as melamine, melam, and melamine cyanurate;
Nitrogen-based flame retardants such as cyanuric acid compounds, isocyanuric acid compounds, triazole compounds, tetrazole compounds, diazo compounds, or urea;
Silicon-based flame retardants such as silicone compounds or silane compounds;
etc.
In addition, examples of inorganic flame retardants include:
Metal hydroxides such as aluminum hydroxide, magnesium hydroxide, zirconium hydroxide, barium hydroxide, or calcium hydroxide;
Metal oxides such as tin oxide, aluminum oxide, magnesium oxide, zirconium oxide, zinc oxide, molybdenum oxide, or nickel oxide;
Zinc carbonate, magnesium carbonate, barium carbonate, zinc borate, or hydrated glass;
etc.
Two or more types of the above-mentioned flame retardants can be used in combination.

Examples of the curing agent include, but are not limited to, amine curing agents and acid anhydride curing agents.
Examples of the amine curing agent include polyamine, melamine resin, dicyandiamide, and 4,4'-diphenyldiaminosulfone. Examples of the melamine resin include methylated melamine resin, butylated melamine resin, and benzoguanamine resin.
Furthermore, examples of the acid anhydride include aromatic acid anhydrides and aliphatic acid anhydrides.
The above-mentioned curing agents may be used alone or in combination of two or more.

The heat aging inhibitors include 2,6-di-tert-butyl-4-methylphenol, n-octadecyl-3-(3',5'-di-tert-butyl-4'-hydroxyphenyl)propione, -tetrakis[methylene-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate]methane, pentaerythritoltetrakis[3-(3,5-di-tert-butyl-4- phenolic antioxidants such as hydroxyphenol or triethylene glycol-bis[3-(3-t-butyl-5-methyl-4-hydroxyphenyl)propionate;
In addition, sulfur-based antioxidants such as dilauryl-3,3'-thiodipropionate or dimyristyl-3,3'-dithiopropionate,
Further examples include phosphorus-based antioxidants such as trisnonylphenyl phosphite and tris(2,4-di-tert-butylphenyl) phosphite.
The above-mentioned heat aging inhibitors may be used alone or in combination of two or more.

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

The adhesive composition can be produced by mixing the carboxyl group-containing styrenic elastomer (A), the epoxy resin (B), the titanic acid compound (C), and other components. The mixing method is not particularly limited as long as the adhesive composition is uniform. Since the adhesive composition is preferably used in the form of a solution or dispersion, a solvent is also usually 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, or diacetone alcohol;
Also, ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, methyl amyl ketone, cyclohexanone, or isophorone;
Furthermore, aromatic hydrocarbons such as toluene, xylene, ethylbenzene, or mesitylene,
In addition, esters such as methyl acetate, ethyl acetate, ethylene glycol monomethyl ether acetate, or 3-methoxybutyl acetate;
Also, aliphatic hydrocarbons such as hexane, heptane, cyclohexane, or methylcyclohexane;
etc.
The above-mentioned 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, coating onto the base film and forming the adhesive layer can be performed smoothly, and the adhesive layer can be formed with a desired thickness. can be obtained easily.

When the adhesive composition contains a solvent, the solid content concentration is preferably in the range of 20 to 80% by mass, more preferably in the range of 30 to 70% by mass, from the viewpoint of workability including formation of the adhesive layer. be.

[Laminated body with adhesive layer]
The laminate with an adhesive layer according to the present invention includes an adhesive layer made of the adhesive composition described above, and a base film in contact with at least one surface of the adhesive layer.

One embodiment of the adhesive layer-equipped laminate according to the present invention is a coverlay film. A coverlay film has an adhesive layer formed on at least one surface of a base film.

When the laminate with an adhesive layer is a coverlay film, examples of the base film include polyimide film, polyetheretherketone film, polyphenylene sulfide film, aramid film, polyethylene naphthalate film, and liquid crystal polymer film. Among these, polyimide films, polyethylene naphthalate films, and liquid crystal polymer films are preferred from the viewpoint of adhesiveness and electrical properties.

Such base films are commercially available, and polyimide films include "Kapton (registered trademark)" manufactured by DuPont-Toray Co., Ltd., "Xenomax (registered trademark)" manufactured by Toyobo Co., Ltd., and Ube Industries (trademark). "Upilex (registered trademark)-S" manufactured by Co., Ltd., "Apical (registered trademark)" manufactured by Kaneka Corporation, etc. can be used.
As for the polyethylene naphthalate film, Teonex (registered trademark) manufactured by Teijin DuPont Films Ltd. or the like can be used.
Furthermore, as for the liquid crystal polymer film, "Vexter (registered trademark)" manufactured by Kuraray Co., Ltd., "BIAC (registered trademark)" manufactured by Primatec Co., Ltd., etc. can be used. The base film can also be used by forming the corresponding resin into a film having a desired thickness.

As a method for manufacturing a coverlay film, for example, a resin varnish containing the above-mentioned adhesive composition and a solvent is applied to the surface of a base film such as a polyimide film to form a resin varnish layer, and then this resin varnish is applied. By removing the solvent from the layer, a coverlay film with an adhesive layer formed thereon can be produced.
The drying temperature when removing the solvent is preferably 40 to 250°C, more preferably 70 to 170°C. Drying is performed by passing the laminate coated with the adhesive composition through a furnace that performs hot air drying, far-infrared heating, high-frequency induction heating, and the like.
Note that, if necessary, a releasable film may be laminated on the surface of the adhesive layer for storage and the like. As the above-mentioned release film, usual ones such as polyethylene terephthalate film, polyethylene film, polypropylene film, silicone release-treated paper, polyolefin resin coated paper, polymethylpentene (TPX) film, fluororesin film, etc. are used.

Another embodiment of the laminate with an adhesive layer includes a bonding sheet. The bonding sheet also has the adhesive layer formed on the surface of a base film, but a releasable film is used as the base film. Further, the bonding sheet may have an adhesive layer between two releasable films. When using the bonding sheet, peel off the release film. As the releasable film, the same ones as mentioned above can be used.

Such release films are also commercially available, such as "Lumirror (registered trademark)" manufactured by Toray Film Kako Co., Ltd., "Toyobo Ester (registered trademark) film" manufactured by Toyobo Co., Ltd., and "Lumirror (registered trademark)" manufactured by Toyobo Co., Ltd. Afflex (registered trademark)" or "Opulan (registered trademark)" manufactured by Mitsui Chemicals Tohcello Co., Ltd. can be used.

As a method for manufacturing a bonding sheet, for example, there is a method in which a resin varnish containing the adhesive composition and a solvent is applied to the surface of a releasable film, and then dried in the same manner as in the case of the coverlay film.

The thickness of the base film is preferably 5 to 100 μm, more preferably 5 to 50 μm, and even more preferably 5 to 30 μm, in order to reduce the thickness of the laminate with the adhesive layer.

The thickness of the adhesive layer is preferably 5 to 100 μm, more preferably 10 to 70 μm, even more preferably 10 to 50 μm.
The thickness of the base film and adhesive layer is selected depending on the application, but the base film tends to be thinner in order to improve electrical properties. In general, when the thickness of the base film is thin and the thickness of the adhesive layer is thick, the laminate with an adhesive layer tends to warp and the workability decreases, but the laminate with an adhesive layer of the present invention Even when the base film is thin and the adhesive layer is thick, the laminate hardly warps. In the laminate with an adhesive layer of the present invention, the ratio (D1/D2) between the thickness (D1) of the adhesive layer and the thickness (D2) of the base film is preferably 1 to 10. It is preferably 1 to 5 or less. Furthermore, it is preferable that the thickness of the adhesive layer is thicker than the thickness of the base film.

Another embodiment of the laminate with an adhesive layer includes a copper-clad laminate. A copper-clad laminate is a laminate in which a polyimide film as a base film and copper foil are bonded together using the adhesive layer. That is, a copper-clad laminate is a laminate composed of a base film, an adhesive layer, and a copper foil in this order. In the copper-clad laminate, the adhesive layer and the copper foil may be formed on both sides of the base film. That is, the copper-clad laminate may be a laminate that sequentially includes an adhesive layer and copper foil on one side and the other side of a base film. Since the adhesive composition of the present invention has excellent adhesion to articles containing copper, the copper-clad laminate has excellent stability as an integrated product. The adhesive layer included in the copper-clad laminate of the present invention may be made of a cured material or may be made of an uncured material.
The thickness of the adhesive layer in the copper-clad laminate is preferably 5 to 45 μm, more preferably 10 to 35 μm.

As a method for producing a copper-clad laminate, for example, the adhesive layer of the coverlay film and the copper foil are brought into surface contact, heat lamination is performed at 80 to 150°C, and the adhesive layer is further hardened by after-curing. method can be applied. After-cure conditions can be, for example, 100 to 200°C and 30 minutes to 4 hours. In addition, the said copper foil is not specifically limited, Electrolytic copper foil, rolled copper foil, etc. can be used.

[Article with adhesive layer]
The article with an adhesive layer according to the present invention is an article provided with an adhesive layer made of the above adhesive composition. A preferred embodiment of the present invention is an electromagnetic shielding material including an adhesive layer. This makes it possible to prevent malfunctions of electronic equipment due to electromagnetic wave noise and leakage of confidential information due to interception of communication radio waves. As a method for manufacturing the electromagnetic shielding material of the present invention, for example, a method of bonding a highly dielectric bonding sheet provided with an adhesive layer and a shielding material can be applied.
The thickness of the adhesive layer in the electromagnetic shielding material is preferably 5 to 100 μm, more preferably 10 to 70 μm.

Other embodiments of the article with an adhesive layer include an antenna substrate, a capacitor, a capacitance type sensor, a piezoelectric film speaker, etc., which are provided with an adhesive layer made of the above-mentioned adhesive composition.

The present invention will be described in more detail based on Examples, but the present invention is not limited thereto. In addition, in the following, "parts" and "%" are based on mass unless otherwise specified.

[Preparation of adhesive composition]
<Example 1>
100 parts by mass of carboxyl group-containing styrene elastomer a (trade name: Tuftec M1913 (maleic acid-modified styrene-ethylenebutylene-styrene block copolymer), manufactured by Asahi Kasei Chemicals Co., Ltd., acid value: 10 mgKOH/g), dicyclo 4.5 parts by mass of a pentadiene skeleton-containing epoxy resin (trade name: HP-7200, manufactured by DIC Corporation), and 0.14 parts of an imidazole-based curing accelerator (trade name: CUREZOL C11Z, manufactured by Shikoku Kasei Kogyo Co., Ltd.). Parts by mass, 1.01 parts by mass of an epoxysilane coupling agent (trade name: SH-6040, manufactured by DuPont-Toray Specialty Materials), barium titanate (trade name: BT-05, Sakai Chemical Industry Co., Ltd.) ), dielectric constant: 4590) was added to 354 parts by mass of a mixed solvent of methyl ethyl ketone/toluene = 4.6/33.4 (mass ratio) and mixed to prepare an adhesive composition. did.

<Example 2>
An adhesive composition was prepared in the same manner as in Example 1, except that the amount of barium titanate added was changed to 176 parts by mass.

<Example 3>
An adhesive composition was prepared in the same manner as in Example 1 except that the amount of barium titanate added was changed to 302 parts by mass.

<Example 4>
An adhesive composition was prepared in the same manner as in Example 1, except that the amount of barium titanate was changed to 471 parts by mass.

<Example 5>
An adhesive composition was prepared in the same manner as in Example 1, except that the amount of barium titanate was changed to 704 parts by mass.

<Example 6>
An adhesive composition was prepared in the same manner as in Example 1, except that the amount of barium titanate was changed to 1057 parts by mass.

<Example 7>
Carboxy group-containing styrenic elastomer a was replaced with carboxyl group-containing styrenic elastomer b (trade name: Tuftec M1911 (maleic acid modified styrene-ethylenebutylene-styrene block copolymer), manufactured by Asahi Kasei Chemicals Co., Ltd., acid value: 2.0 mgKOH An adhesive composition was prepared in the same manner as in Example 1, except that the amount of barium titanate was changed to 471 parts by mass.

<Example 8>
The same procedure as in Example 1 was carried out, except that 78.2 parts by mass of barium titanate was changed to 377 parts by mass of strontium titanate (trade name: ST-A, manufactured by Fuji Titanium Industry Co., Ltd., dielectric constant: 300). , an adhesive composition was prepared.

<Example 9>
Same as Example 1 except that 78.2 parts by mass of barium titanate was changed to 322 parts by mass of calcium titanate (trade name: CT-3, manufactured by Kyoritsu Materials Co., Ltd., dielectric constant: 180), An adhesive composition was prepared.

<Example 10>
An adhesive composition was prepared in the same manner as in Example 4, except that the amount of the dicyclopentadiene skeleton-containing epoxy resin was changed to 1 part by mass.

<Example 11>
An adhesive composition was prepared in the same manner as in Example 4, except that the amount of the dicyclopentadiene skeleton-containing epoxy resin was changed to 25 parts by mass.

<Comparative example 1>
100 parts by mass of epoxy resin (trade name: Epicote 828, manufactured by Mitsubishi Chemical Corporation), 25 parts by mass of diethylene glycol diglycidyl ether (trade name: SR-2EGS, manufactured by Sakamoto Pharmaceutical Co., Ltd.), modified aliphatic polyamine (Product name: Fujicure FXJ-8074-D, manufactured by T&K TOKA Co., Ltd.) at 48.5 parts by mass, and aminopropyltriethoxysilane (Product name: A-1100, manufactured by Nisso Sangyo Co., Ltd.) at 1.5 parts by mass. 97.2 parts by mass of barium titanate (trade name: BT-05, manufactured by Sakai Chemical Industry Co., Ltd.) were mixed to prepare an adhesive composition.

<Comparative example 2>
100 parts by mass of epoxy resin (trade name: Epicoat 807, manufactured by Mitsubishi Chemical Corporation), 19 parts by mass of m-phenylenediamine (trade name: Epicure Z, manufactured by Mitsubishi Chemical Corporation), epoxy silane coupling agent. (Product name: KBM-402, manufactured by Shin-Etsu Chemical Co., Ltd.) 1.84 parts by mass, and titanate coupling agent (Product name: KR-46B, manufactured by Ajinomoto Fine Techno Co., Ltd.) 0.79 parts by mass. , barium titanate (trade name: BT-05, manufactured by Sakai Chemical Industry Co., Ltd.) were mixed in an amount of 426 parts by mass to prepare an adhesive composition.

<Comparative example 3>
100 parts by mass of acid-modified polyolefin resin (trade name: AUROREN 500S, manufactured by Nippon Paper Industries Co., Ltd.), 0.1 part by mass of dioctyltin dilaurate (manufactured by Kishida Chemical Co., Ltd.), hexamethylene diisocyanate (trade name: Duranate). TKA-100, manufactured by Asahi Kasei Corporation) was 10 parts by mass, barium titanate (trade name: BT-05, manufactured by Sakai Chemical Industries, Ltd.) was 78.2 parts by mass, and methyl ethyl ketone/toluene = 3.7/ 1 (mass ratio) and mixed with 567 parts by mass of a mixed solvent to prepare an adhesive composition.

<Comparative example 4>
100 parts by mass of acrylic polymer (trade name: UH-2041, manufactured by Toagosei Co., Ltd.), 0.1 part by mass of dioctyltin dilaurate (manufactured by Kishida Chemical Co., Ltd.), and hexamethylene diisocyanate (trade name: Duranate AE-). 700-100, manufactured by Asahi Kasei Co., Ltd.) and 66.7 parts by mass of barium titanate (trade name: BT-05, manufactured by Sakai Chemical Industry Co., Ltd.) were mixed to prepare an adhesive composition. did.

<Comparative example 5>
An adhesive composition was prepared in the same manner as in Example 1, except that 141 parts by mass of silica (trade name: Excelica SE-1, manufactured by Tokuyama Corporation) was added in place of 78.2 parts by mass of barium titanate. Prepared.

<Comparative example 6>
An adhesive composition was prepared in the same manner as in Example 1, except that 181 parts by mass of boron nitride (trade name: PCTP-2, manufactured by Saint-Gobain Co., Ltd.) was added in place of 78.2 parts by mass of barium titanate. Prepared.

<Comparative example 7>
An adhesive composition was prepared in the same manner as in Example 1, except that the amount of barium titanate was changed to 33.4 parts by mass.

<Comparative example 8>
An adhesive composition was prepared in the same manner as in Example 1, except that the amount of barium titanate was changed to 1644 parts by mass.

<Comparative example 9>
An adhesive composition was prepared in the same manner as in Example 1 except that barium titanate was not added.

[Evaluation method]
<Method for measuring acid value of carboxyl group-containing styrenic elastomer>
1 g of a styrene elastomer containing a carboxyl group was dissolved in 30 ml of toluene, and an automatic titrator "AT-510" manufactured by Kyoto Electronics Industry Co., Ltd. connected to a burette "APB-510-20B" manufactured by the same company was used. Potentiometric titration was performed using a 0.01 mol/L benzyl alcoholic KOH solution as a titration reagent, and the number of mg of KOH per 1 g of the carboxyl group-containing styrene elastomer was calculated.

<Method for measuring molecular weight of carboxyl group-containing styrenic elastomer>
Equipment: Alliance 2695 (manufactured by Waters)
Column: TSKgel SuperMultiporeHZ-H 2 pieces, TSKgel SuperHZ2500 2 pieces, (manufactured by Tosoh Corporation)
Column temperature: 40℃
Eluent: Tetrahydrofuran 0.35ml/min Detector: RI (differential refractive index detector)
The molecular weight measured by GPC was converted based on the molecular weight of polystyrene.

<Measurement method of dielectric constant>
(Cured products of adhesive compositions prepared in Examples 1 to 11 and Comparative Examples 5 to 9)
A release polyethylene terephthalate film with a thickness of 38 μm was prepared, and an adhesive composition was roll-coated on one surface thereof. Next, this coated film was left in an oven and dried at 90° C. for 3 minutes to form a film (adhesive layer) with a thickness of 50 μm. Next, this film was placed in an oven and heat-treated at 180° C. for 30 minutes. By this heat treatment, the curing reaction (crosslinking reaction) of the coating sufficiently proceeds. Thereafter, the release film was peeled off to prepare a test piece (50 x 50 mm).
The dielectric constant (ε) was measured using a network analyzer 85071E-300 (manufactured by Agilent Technologies) by a split post dielectric resonator method (SPDR method) at a temperature of 23° C. and a frequency of 10 GHz.

(Cured product of adhesive composition prepared in Comparative Examples 1 and 2)
A release polyethylene terephthalate film with a thickness of 38 μm was prepared, and an adhesive composition was roll-coated on one surface thereof. Next, this coated film was left in an oven and dried at 90° C. for 3 minutes to form a film (adhesive layer) with a thickness of 50 μm. Next, this film was placed in an oven and heat-treated at 130° C. for 5 minutes. By this heat treatment, the curing reaction (crosslinking reaction) of the coating sufficiently proceeds. Thereafter, the release film was peeled off to prepare a test piece (50 x 50 mm).
The dielectric constant (ε) was measured using the same apparatus as above and under the same conditions as above.

(Cured product of adhesive composition prepared in Comparative Example 3)
A release polyethylene terephthalate film with a thickness of 38 μm was prepared, and an adhesive composition was roll-coated on one surface thereof. Next, this coated film was left in an oven and dried at 90° C. for 3 minutes to form a film (adhesive layer) with a thickness of 50 μm. Next, this film was left in an oven and cured at 40° C. for one day. Through this curing, the curing reaction (crosslinking reaction) of the coating sufficiently proceeds. Thereafter, the release film was peeled off to prepare a test piece (50 x 50 mm).
The dielectric constant (ε) was measured using the same apparatus as above and under the same conditions as above.

(Cured product of adhesive composition prepared in Comparative Example 4)
A release polyethylene terephthalate film with a thickness of 38 μm was prepared, and an adhesive composition was roll-coated on one surface thereof. Next, this coated film was left in an oven and dried at 90° C. for 3 minutes to form a film (adhesive layer) with a thickness of 50 μm. Next, this film was placed in an oven and heat-treated at 80° C. for 1 hour. By this heat treatment, the curing reaction (crosslinking reaction) of the coating sufficiently proceeds. Thereafter, the release film was peeled off to prepare a test piece (50 x 50 mm).
The dielectric constant (ε) was measured using the same apparatus as above and under the same conditions as above.

(Titanic acid compound (C))
After preparing a paste composition by mixing a titanic acid compound with polyvinyl alcohol and water, it was filled into a pellet molding machine and dried to obtain a pellet-shaped solid. The solid pellets were heated and fired to about 900 to 1200° C. to decompose and remove the binder resin, and the titanic acid compound (C) was sintered to obtain sintered pellets. Upper and lower electrodes were formed on this sintered pellet, and the capacitance was measured according to JIS K 6911:2006. The dielectric constant was calculated from the capacitance and the dimensions of the sintered pellet.

<Method for measuring peel strength>
(Cured products of adhesive compositions prepared in Examples 1 to 11 and Comparative Examples 5 to 9)
A rolled copper foil having a thickness of 35 μm was prepared, and the adhesive composition was roll-coated on the surface thereof. Next, this coated film was left in an oven and dried at 90° C. for 3 minutes to form a 50 μm thick film (adhesive layer) to obtain a copper foil with an adhesive layer. Thereafter, a copper-clad laminate with a polyimide layer having a thickness of 57 μm was stacked so that the polyimide layer side was in surface contact with the surface of the adhesive layer of the copper foil with an adhesive layer, and the temperature was 120°C and the pressure was 0.5 MPa. Laminated.
Next, this laminate (copper-clad laminate with polyimide/adhesive layer/copper foil) was heat-pressed at a temperature of 180° C. and a pressure of 3 MPa for 30 minutes to obtain a substrate for peel strength evaluation. This evaluation substrate was cut to prepare adhesive test pieces of a predetermined size. In order to evaluate the adhesion, the 90° peel strength (N/cm) was measured when the rolled copper foil was peeled off from the adhesive test piece at a temperature of 23°C and a tensile speed of 50 mm/min in accordance with JIS C 6481:2015. was measured. The width of the adhesive test piece during measurement was 10 mm.

(Cured product of adhesive composition prepared in Comparative Examples 1 and 2)
A rolled copper foil having a thickness of 35 μm was prepared, and the adhesive composition was roll-coated on the surface thereof. Next, this coated film was left in an oven and dried at 90° C. for 3 minutes to form a 50 μm thick film (adhesive layer) to obtain a copper foil with an adhesive layer. Thereafter, a copper-clad laminate with a polyimide layer having a thickness of 57 μm was stacked so that the polyimide layer side was in surface contact with the surface of the adhesive layer of the copper foil with an adhesive layer, and the temperature was 120°C and the pressure was 0.5 MPa. Laminated.
Next, this laminate (copper-clad laminate with polyimide/adhesive layer/copper foil) was heat-pressed for 3 minutes at a temperature of 130° C. and a pressure of 3 MPa to obtain a substrate for peel strength evaluation. This evaluation substrate was cut to prepare adhesive test pieces of a predetermined size. In order to evaluate the adhesion, the 90° peel strength (N/cm) was measured when the rolled copper foil was peeled off from the adhesive test piece at a temperature of 23°C and a tensile speed of 50 mm/min in accordance with JIS C 6481:2015. was measured. The width of the adhesive test piece during measurement was 10 mm.

(Cured product of adhesive composition prepared in Comparative Example 3)
A rolled copper foil having a thickness of 35 μm was prepared, and the adhesive composition was roll-coated on the surface thereof. Next, this coated film was left in an oven and dried at 90° C. for 3 minutes to form a 50 μm thick film (adhesive layer) to obtain a copper foil with an adhesive layer. Thereafter, a copper-clad laminate with a polyimide layer having a thickness of 57 μm was stacked so that the polyimide layer side was in surface contact with the surface of the adhesive layer of the copper foil with an adhesive layer, and the temperature was 80°C, the pressure was 0.4 MPa, and the speed was Lamination was performed at a speed of 0.5 m/min. Next, this film was left in an oven and cured for one day at 40°C to obtain a substrate for evaluation of peel strength. This evaluation substrate was cut to prepare adhesive test pieces of a predetermined size. In order to evaluate the adhesion, the 90° peel strength (N/cm) was measured when the rolled copper foil was peeled off from the adhesive test piece at a temperature of 23°C and a tensile speed of 50 mm/min in accordance with JIS C 6481:2015. was measured. The width of the adhesive test piece during measurement was 10 mm.

(Cured product of adhesive composition prepared in Comparative Example 4)
A rolled copper foil having a thickness of 35 μm was prepared, and the adhesive composition was roll-coated on the surface thereof. Next, this coated film was left in an oven and dried at 90° C. for 3 minutes to form a 50 μm thick film (adhesive layer) to obtain a copper foil with an adhesive layer. Thereafter, a copper-clad laminate with a polyimide layer having a thickness of 57 μm was stacked so that the polyimide layer side was in surface contact with the surface of the adhesive layer of the copper foil with an adhesive layer, and the temperature was 80°C, the pressure was 0.4 MPa, and the speed was Lamination was performed at a speed of 0.5 m/min. Next, this film was left in an oven and heat-treated at 80° C. for 1 hour to obtain a substrate for evaluation of peel strength. This evaluation board was cut to prepare adhesive test pieces of a predetermined size. In order to evaluate the adhesion, the 90° peel strength (N/cm) was measured when the rolled copper foil was peeled off from the adhesive test piece at a temperature of 23°C and a tensile speed of 50 mm/min in accordance with JIS C 6481:2015. was measured. The width of the adhesive test piece during measurement was 10 mm.

<Method for measuring coatability (liquid viscosity)>
The liquid viscosity of the adhesive composition was measured using a TVE-20H type viscometer (salt water/flat plate method, manufactured by Toki Sangyo Co., Ltd.), which is an E type viscometer (cone plate type viscometer), under the following conditions. It was measured. If the liquid viscosity was 60,000 mPa·s or less, it was judged that the coating properties were good.
-Measurement condition-
Cone shape: angle 3° x R9.7', radius 20mm
Temperature: 25℃±0.5℃

<Method of measuring flexibility>
(Tensile test)
A test piece was prepared in the same manner as in the measurement of the electrical properties (permittivity) described above, and using "Autograph AG-Xplus" manufactured by Shimadzu Corporation, the distance between the jigs was 40 mm, the distance between the gauge lines was 20 mm, and the tension was measured. Tensile tests were conducted at a speed of 5 mm/min and at 23°C. Distortion was measured in real time using a camera. The strain from the origin to the yield point was divided into 10 parts, and the slope of the tangent in each section was calculated using the least squares method to calculate the tensile modulus.
(bending test)
Based on the bending resistance test (cylindrical mandrel method) based on JIS K5600-5-1:2018, the test piece was prepared in the same manner as the above tensile test, and the test piece was wound around a steel rod with a diameter of 2 mm. Visual observation was made to see if cracking occurred. Those in which no cracks were observed were evaluated as "○", and those in which cracks were observed were evaluated as "x".

<Moisture heat resistance test>
An adhesive test piece prepared in the same manner as the adhesive test piece prepared in the above-mentioned "peel strength" measurement was placed in a constant temperature and humidity chamber at 85°C and 85%, and stored for 2000 hours (moist heat treatment). The peel strength after the moist heat treatment was measured in the same manner as in the measurement method for "Peel strength". The retention rate of peel strength ((N2/N1) x 100) was calculated from the peel strength (N1) of the adhesive test piece before moisture resistance treatment and the peel strength (N2) after moist heat treatment and was evaluated by applying it to the following criteria.
○: Peel strength retention rate is 80% or more △: Peel strength retention rate is 60% or more and less than 80% ×: Peel strength retention rate is less than 60%

The compositions of the adhesive compositions according to Examples 1 to 11 and Comparative Examples 1 to 9 are shown in Tables 1 and 2, and the adhesive compositions or cured products thereof according to Examples 1 to 11 and Comparative Examples 1 to 9 were tested. The results are shown in Table 3.

(Note to Table 1)
・Numbers in the table: parts by mass

(Note to Table 2)
Numerical values in the table: parts by mass "Dioctyltin dilaurate" has been omitted from Table 2.

(Note to Table 3)
The "-" in Comparative Example 1 means that the adhesive composition solidified 15 minutes after being applied, and the coating properties (liquid viscosity) could not be measured.

In Comparative Example 5, which did not contain a titanic acid compound as a filler but contained silica particles, the dielectric constant of the cured product could not be increased to the desired level. The same applies to Comparative Example 6 in which boron nitride was blended as a filler and Comparative Example 9 in which no filler was blended.
Further, even if a titanic acid compound is blended as a filler, if the amount thereof is small, the dielectric constant of the cured product cannot be increased to a desired level (Comparative Example 7). On the other hand, if the amount of the titanic acid compound is too large, the liquid viscosity increases, resulting in poor handling properties and poor peel strength of the cured product (Comparative Example 8).
In addition, even if the desired amount of titanic acid compound is blended as a filler, the base resin (matrix resin) does not contain a carboxy group-containing styrene elastomer, the base resin is only an epoxy resin, and the system is reacted with a curing agent. In some cases, the curing reaction proceeded too quickly, resulting in significantly poor handling properties, and the resulting cured product was hard and poor in flexibility. (Comparative Examples 1 and 2).
In addition, if the base resin is composed of a polyolefin resin having a reactive group instead of using an epoxy resin as the base resin, and a curing reaction is caused by reacting these with polyisocyanate, even if a titanic acid compound is blended. It was not possible to increase the dielectric constant and peel strength to desired levels, and the peel strength was also inferior to Example 1, which contained the same amount of barium titanate (Comparative Example 3).
Similarly, if the base resin is composed of an acrylic polymer without using an epoxy resin as the base resin, and a curing reaction is caused by reacting these with polyisocyanate, the desired dielectric constant can be obtained even if a titanate compound is blended. Moreover, the peel strength was poor, and the peel strength after moist heat treatment was also poor (Comparative Example 4).
In contrast, all of the adhesive compositions specified in the present invention have excellent handling properties, and the resulting cured product fully brings out the high dielectric properties of the titanate compound, exhibits a high dielectric constant, and is flexible. It also had excellent adhesive strength to adherends, and this adhesive strength was resistant to decrease even by moist heat treatment (Examples 1 to 11). Furthermore, from the above results, the adhesive composition of the present invention does not exhibit peel strength sufficient to function as an adhesive even when the dielectric constant is greatly increased by adding barium titanate to a large amount of about 1000 parts by mass. It can be seen that the coatability and flexibility are also good (Example 6).

Claims (10)

Including a carboxyl group-containing styrenic elastomer (A), an epoxy resin (B), and a titanic acid compound (C),
The content of the carboxy group-containing styrenic elastomer (A) in the total solid content is 6% by mass or more,
An adhesive composition having a dielectric constant of 3.8 or more after a curing reaction. The adhesive composition according to claim 1, wherein the titanic acid compound (C) has a dielectric constant of 100 or more. The adhesive composition according to claim 1 or 2, wherein the content of the titanic acid compound (C) is 70 to 1100 parts by mass based on 100 parts by mass of the carboxy group-containing styrenic elastomer (A). thing. The adhesive composition according to any one of claims 1 to 3, wherein the titanate compound (C) is at least one of barium titanate, strontium titanate, and calcium titanate. The adhesive composition according to any one of claims 1 to 4, containing a silane coupling agent. The adhesive composition according to any one of claims 1 to 5, wherein the carboxy group-containing styrenic elastomer (A) has an acid value of 0.1 to 35 mgKOH/g. The carboxyl group-containing styrene elastomer (A) is a styrene-butadiene block copolymer, a styrene-ethylene propylene block copolymer, a styrene-butadiene-styrene block copolymer, a styrene-isoprene-styrene block copolymer, or a styrene block copolymer. - A modified product of at least one of an ethylene butylene-styrene block copolymer and a styrene-ethylene propylene-styrene block copolymer with an unsaturated carboxylic acid compound, according to any one of claims 1 to 6. adhesive composition. The adhesive composition according to any one of claims 1 to 7, wherein the epoxy resin (B) is a polyfunctional epoxy resin having an alicyclic skeleton. Any one of claims 1 to 8, wherein the content of the epoxy resin (B) is 0.5 to 30 parts by mass based on 100 parts by mass of the carboxyl group-containing styrenic elastomer (A). The adhesive composition described in . A laminate with an adhesive layer comprising a base film and an adhesive layer made of the adhesive composition according to any one of claims 1 to 9.