TWI858283B - Adhesive composition - Google Patents

Abstract

The present invention provides an adhesive composition which can prevent resin flow during hot pressing by controlling mechanical properties, and can form an adhesive layer showing good electrical properties and good adhesion. The adhesive composition contains at least a resin composition containing a styrene-based elastomer and an inorganic filler, wherein the content of the inorganic filler is 1 to 180 parts by mass relative to 100 parts by mass of the resin composition, and the inorganic filler has a plate-like or scale-like shape, and the relative dielectric constant of the adhesive layer formed by curing the adhesive composition at a frequency of 28 GHz is less than 3.5, and the dielectric tangent of the adhesive layer at a frequency of 28 GHz is less than 0.005.

Description

Adhesive composition

The present invention relates to an adhesive composition. More specifically, it relates to an adhesive composition that can be used for bonding electronic parts and the like.

As electronic equipment becomes smaller and lighter, the bonding uses of electronic parts and the like become more diverse, and the demand for laminates with adhesive layers increases. In addition, flexible printed wiring boards (hereinafter also referred to as FPCs), which are a type of electronic parts, need to process large amounts of data at high speed, and methods to cope with high frequencies have been developed. With the practical application of 5G, it is predicted that communication speeds will increase and frequencies will increase, and the realization of excellent low transmission loss and stability of large-capacity communications will be sought. In response to this, the development of low-dielectric materials in FPCs and the development of adhesives that constitute adhesive layers are currently underway.

In order to have both good electrical properties and high adhesion, a laminate has been proposed, which uses an adhesive composition containing a carboxyl-containing styrene-based elastomer (A) and an epoxy resin (B), and is composed of an adhesive layer and a substrate film composed of the adhesive composition (for example, refer to patent document 1). [Prior art document] [Patent document]

[Patent Document 1] International Publication No. 2016/017473

(The problem to be solved)

The manufacturing process of printed wiring boards includes a hot press step, but if the mechanical properties of the adhesive are poor, it may not be possible to bond with the preset thickness and size. For example, the adhesive may flow during hot press because the adhesive is soft, or deform during hot press because the thermal expansion coefficient (CTE) is large. When inorganic fillers are added to prevent the resin from flowing, the electrical properties of the adhesive layer may deteriorate, or the adhesion of the adhesive layer may decrease. Therefore, it is hoped to provide a laminate with an adhesive layer that can prevent the resin from flowing during hot pressing by controlling the mechanical properties, exhibit good electrical properties, and have good adhesion between the adhesive layer and the substrate film.

The purpose of the present invention is to provide an adhesive composition that can prevent the resin from flowing during hot pressing by controlling the mechanical properties, and can form an adhesive layer that exhibits good electrical properties and good adhesion. (Method for solving the problem)

The inventors of this case have made great efforts to study and find that the above-mentioned problems can be solved by adding specific inorganic fillers to styrene-based elastomers, thus completing the present invention.

The present invention includes the following aspects. (1) An adhesive composition comprising at least a resin composition containing a styrene-based elastomer and an inorganic filler, wherein the content of the inorganic filler is 1 to 180 parts by mass relative to 100 parts by mass of the resin composition, the inorganic filler has a plate-like or scaly shape, and the relative dielectric constant of the adhesive layer formed by curing the adhesive composition at a frequency of 28 GHz is less than 3.5, and the dielectric tangent of the adhesive layer at a frequency of 28 GHz is less than 0.005. (2) An adhesive composition as described in (1), wherein the aspect ratio of the inorganic filler is less than 5 to 500. (3) The adhesive composition of (1) or (2), wherein the average particle size of the inorganic filler is 3.0 μm or less. (4) The adhesive composition of any one of (1) to (3), wherein the inorganic filler contains at least any one of a silicon-based inorganic filler and boron nitride. (5) The adhesive composition of any one of (1) to (4), wherein the silicon-based inorganic filler contains at least any one of mica and talc. (6) The adhesive composition of any one of (1) to (5), wherein the styrene-based elastomer is a styrene-based elastomer containing a carboxyl group. (7) The adhesive composition of any one of (1) to (5), wherein the styrene-based elastomer is an amine-based elastomer. (8) An adhesive composition as described in any one of (1) to (7), wherein the resin composition contains an epoxy resin. (9) An adhesive composition as described in (8), wherein the content of the epoxy resin is 1 to 25 parts by weight relative to 100 parts by weight of the resin composition. (10) An adhesive composition as described in any one of (1) to (9), wherein the storage elastic modulus of the adhesive layer of the adhesive composition before curing at 150°C is greater than 1.0E+5Pa. (11) An adhesive composition as described in any one of (1) to (10), wherein the coefficient of thermal expansion (CTE) of the adhesive layer formed by curing the adhesive composition is 500 ppm/K or less. (12) A laminate comprising: a substrate film, and an adhesive layer formed by the adhesive composition as described in any one of (1) to (10). (13) A laminate as described in (12), wherein the substrate film contains polyetheretherketone (PEEK) resin. (14) A coating film with an adhesive layer, comprising the laminate as described in (12) or (13). (15) A copper-clad laminate comprising a laminate as described in (12) or (13). (16) A printed wiring board comprising a laminate as described in (12) or (13). (17) A shielding film comprising a laminate as described in (12) or (13). (18) A printed wiring board with a shielding film comprising a laminate as described in (12) or (13). (Effect of the invention)

According to the present invention, an adhesive composition can be provided, which can prevent the resin from flowing during heat pressing by controlling the mechanical properties, and can form an adhesive layer having good electrical properties and good adhesion.

The following is a detailed description of the adhesive composition of the present invention, a laminate containing an adhesive layer composed of the adhesive composition, and components related to electronic components containing the laminate, but the description of the constituent elements recorded below is an example of an implementation of the present invention and is not limited to such contents.

(Adhesive composition) The adhesive composition of the present invention contains at least: a resin composition containing a styrene elastomer, and an inorganic filler. The inorganic filler contained in the adhesive composition of the present invention has a plate-like or scaly shape. The content of the inorganic filler contained in the adhesive composition of the present invention is 1 to 180 parts by mass relative to 100 parts by mass of the resin composition. The relative dielectric constant of the adhesive layer formed by curing the adhesive composition of the present invention at a frequency of 28 GHz is 3.5 or less, and the dielectric tangent of the adhesive layer at a frequency of 28 GHz is 0.005 or less. In addition to the resin composition and the inorganic filler, the adhesive composition may contain other components as needed.

<Resin composition> The resin composition of the present invention contains at least a styrene-based elastomer. Among the styrene-based elastomer, it is preferred to contain a carboxyl-containing styrene-based elastomer and an amine-containing styrene-based elastomer. The resin composition may contain an epoxy resin. The resin composition may also contain other resin components other than the styrene-based elastomer and the epoxy resin as needed.

＜＜Styrene-based elastomer＞＞ Styrene-based elastomers do not contain highly polar bonding groups, so they have excellent electrical properties. They are resins that can adjust flexibility and adhesion due to the cohesive force due to the interaction between styrene structures and the ease of adjusting molecular weight. In addition, the dispersibility and adhesion of inorganic fillers can be improved by modification. Styrene-based elastomers refer to copolymers with block and random structures of conjugated diene compounds and aromatic vinyl compounds as the main components, and their hydrogenates. Aromatic vinyl compounds, such as styrene, tert-butyl styrene, α-methyl styrene, divinylbenzene, 1,1-diphenylethylene, N,N-diethyl-p-aminoethyl styrene, vinyl toluene, etc. In addition, covalent diene compounds, such as butadiene, isoprene, 1,3-pentadiene, 2,3-dimethyl-1,3-butadiene, etc. Specific examples of styrene-based elastomers include styrene-butadiene block copolymers, styrene-ethylene propylene block copolymers, styrene-butadiene-styrene block copolymers, styrene-isoprene-styrene block copolymers, styrene-ethylene butylene-styrene block copolymers, and styrene-ethylene propylene-styrene block copolymers.

Only one of the styrene-based elastomers may be used, or two or more of them may be used in combination. Among the above copolymers, styrene-ethylene butylene-styrene block copolymers and styrene-ethylene propylene-styrene block copolymers are preferred from the viewpoints of adhesion and electrical properties. In addition, the mass ratio of styrene/ethylene butylene in the styrene-ethylene butylene-styrene block copolymer and the mass ratio of styrene/ethylene propylene in the styrene-ethylene propylene-styrene block copolymer are preferably 10/90 to 50/50, and more preferably 20/80 to 40/60. If the mass ratio is within this range, an adhesive composition having excellent adhesive properties can be obtained.

The content of the styrene elastomer is preferably 10.0 parts by mass to 99.0 parts by mass based on 100 parts by mass of the solid content of the resin composition.

＜＜＜Carboxyl-containing styrene elastomer＞＞＞ Carboxyl-containing styrene elastomer has high adhesion and can give flexibility to the cured product, and is effective as a component that provides good electrical properties. By containing carboxyl-containing styrene elastomer in the adhesive composition, the electrical properties are good, and even for low-polarity substrate films, metal foils and other adherends, the soft adhesive composition can fully adhere to the surface of the adherend, thereby allowing the highly polar carboxyl groups to exhibit adhesion, thereby improving the adhesion of the adhesive layer. In addition, carboxyl-containing styrene elastomers are reactive, so by epoxy curing, the heat resistance and chemical resistance of the adhesive layer are also improved. In addition, by containing carboxyl groups, the dispersibility of inorganic fillers in the dispersion is improved. Carboxyl-containing styrene elastomers are copolymers mainly composed of blocks and random structures of covalent diene compounds and aromatic vinyl compounds, and their hydrides modified with unsaturated carboxylic acids. The types of aromatic vinyl compounds and covalent diene compounds, and specific examples of styrene elastomers are as described in the above column <<Styrene elastomers>>.

The modification of the carboxyl-containing styrene elastomer can be carried out, for example, by copolymerizing an unsaturated carboxylic acid during the polymerization of the styrene elastomer. Alternatively, the modification can be carried out by heating and kneading the styrene elastomer and the unsaturated carboxylic acid in the presence of an organic peroxide. Examples of unsaturated carboxylic acids include acrylic acid, methacrylic acid, maleic acid, itaconic acid, fumaric acid, maleic anhydride, itaconic anhydride, and the like. The modification amount using the unsaturated carboxylic acid is preferably 0.1 to 10% by mass. The acid value of the carboxyl-containing styrene elastomer is preferably 0.1 to 30 mgKOH/g, more preferably 0.5 to 25 mgKOH/g, and even more preferably 0.5 to 5 mgKOH/g. If the acid value is 0.1 mgKOH/g or more, the dispersibility of the inorganic filler becomes good. If the acid value is above 0.5 mgKOH/g, the adhesive composition is sufficiently cured, and good adhesion and heat resistance can be obtained. On the other hand, if the acid value is below 30 mgKOH/g, the cohesion of the adhesive composition is suppressed, so the adhesion is excellent and the electrical properties are also excellent. If the acid value is below 5 mgKOH/g, the adhesion with the PEEK substrate is improved.

In addition, the weight average molecular weight of the carboxyl-containing styrene elastomer is preferably 10,000 to 500,000, more preferably 300,000 to 300,000, and more preferably 500,000 to 200,000. If the weight average molecular weight is above the lower limit, it can exhibit excellent adhesion, and the coating property when dissolved in a solvent and coated becomes good. If the weight average molecular weight is below the upper limit, the compatibility with the epoxy resin becomes good. If the weight average molecular weight is within the above range, the mechanical properties can be controlled to an appropriate range, and the prevention of resin flow and the dispersibility of the inorganic filler in the dispersion can be taken into account. 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.

The content of the carboxyl-containing styrene elastomer is preferably 10.0 to 99.0 parts by mass relative to 100 parts by mass of the solid component of the resin composition. If the content is within the above range, it can become an adhesive composition with excellent bonding properties. It is even better to be 20 to 49 parts by mass relative to 100 parts by mass of the solid component of the resin composition. If the content is within the above range, the mechanical properties can be controlled within an appropriate range, and both the prevention of resin flow and the dispersibility of the inorganic filler in the dispersion can be taken into account.

＜＜＜Amino-containing styrene elastomer＞＞＞ By containing an amine-containing styrene elastomer in the adhesive composition, the reactivity is improved and the adhesion of the adhesive layer is improved. In addition, since the amine-containing styrene elastomer is reactive, the heat resistance and chemical resistance of the adhesive layer are also improved by epoxy curing. Because it contains an amine group, the adhesion to metal is improved. In addition, because it contains an amine group, the reactivity with epoxy resin is high, and it can be cured before the resin flows out, which can effectively prevent the resin from flowing. Amine-containing styrene elastomer refers to a copolymer mainly composed of a block and random structure of a conjugated diene compound and an aromatic vinyl compound, and its hydrogenated product is modified with amine. The types of aromatic vinyl compounds and covalent diene compounds, and specific examples of styrene-based elastomers are as described in the above column "Styrene-based elastomers".

The method for amine-modifying the styrene-based elastomer is not particularly limited, and a known method may be used, for example: a method of amine-modifying a (hydrogenated) block copolymer by polymerizing it using a polymerization initiator having an amine group; a method of amine-modifying a (hydrogenated) copolymer by using an unsaturated monomer having an amine group as a copolymerization raw material; a method of amine-modifying a carboxyl-containing styrene-based elastomer and an amine modifier having two or more amine groups to react and form an amide structure or an imide structure, etc.

In addition, the weight average molecular weight of the amino-containing styrene elastomer is preferably 10,000 to 500,000, more preferably 300,000 to 300,000, and more preferably 500,000 to 200,000. If the weight average molecular weight is above the lower limit, it can exhibit excellent adhesion, and the coating property will also be improved when dissolved in a solvent and coated. If the weight average molecular weight is below the upper limit, the compatibility with the epoxy resin becomes good. If the weight average molecular weight is within the above range, the mechanical properties can be controlled to an appropriate range, and both the prevention of resin flow and the dispersibility of the inorganic filler in the dispersion can be taken into account.

The content of the amino-containing styrene elastomer is preferably 10.0-99.0 parts by weight relative to 100 parts by weight of the solid content of the resin composition. It is even more preferably 20-49 parts by weight relative to 100 parts by weight of the solid content of the resin composition. If the content is 10.0-99.0 parts by weight, it can become an adhesive composition with excellent bonding properties. If the content is 20-49 parts by weight, the mechanical properties can be controlled within an appropriate range, and both the prevention of resin flow and the dispersibility of the inorganic filler in the dispersion can be taken into account.

By mixing unmodified styrene elastomer with modified styrene elastomer, it is possible to adjust hardness and control MFR while maintaining adhesion.

＜＜Epoxy resin＞＞ Epoxy resin is a component that reacts with the carboxyl group in the above-mentioned carboxyl group-containing styrene elastomer and the amine group in the above-mentioned amine group-containing styrene elastomer, and exhibits a high degree of adhesion to the adherend and heat resistance of the cured adhesive.

Epoxy resins, for example, bisphenol A epoxy resins, bisphenol F epoxy resins, or hydrogenated versions thereof; epoxy resins based on propylene glycol, ethylene glycol, propylene glycol, 1,4-dihydro-1,4-dihydro-1,4-dihydro-1,4-dihydro-1,4-dihydro-1,4-dihydro-1,4-dihydro-1,4-dihydro-1,4-dihydro-1,4-dihydro-1,4-dihydro-1,4-dihydro-1,4-dihydro-1,4-dihydro-1,4-dihydro-1,4-dihydro-1,4-dihydro-1,4-dihydro-1,4-dihydro-1,4-dihydro-1,4-dihydro-1,4-dihydro-1,4-dihydro-1,4-dihydro-1,4-dihydro-1,4-dihydro-1,4-dihydro-1,4-dihydro-1,4-dihydro-1,4-dihydro-1,4-dihydro-1,4-dihydro-1,4-dihydro-1 - Butanediol diglycidyl ether, 1,6-hexanediol diglycidyl ether, trihydroxymethylpropane triglycidyl ether, pentaerythritol tetraglycidyl ether, tetraphenylglycidyl ether ethane, triphenylglycidyl ether ethane, polyglycidyl ether of sorbitol, polyglycidyl ether of polyglycerol and other glycidyl ether-based epoxy resins; triglycidyl isocyanurate, tetraglycidyl diaminodiphenylmethane and other glycidyl amine-based epoxy resins; epoxidized polybutadiene, epoxidized soybean oil and other linear aliphatic epoxy resins, etc., but not limited to these. In addition, novolac epoxy resins such as novolac epoxy resins containing a xylene structure, naphthol novolac epoxy resins, phenol novolac epoxy resins, o-cresol novolac epoxy resins, and bisphenol A novolac epoxy resins can be used.

In addition, epoxy resins such as 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, tert-butylcatechol-type epoxy resins, triphenylmethane-type epoxy resins, tetraphenylethane-type epoxy resins, biphenyl-type epoxy resins, bisphenol S-type epoxy resins, etc. can be used. Only one of these epoxy resins can be used, or two or more can be used in combination. Among the above epoxy resins, epoxy resins without hydroxyl groups are preferred from the viewpoint of obtaining adhesive compositions with excellent electrical properties and good compatibility with styrene-based elastomers. In particular, novolac epoxy resins and epoxy resins with the following structures are epoxy resins with moderately soft skeletons, and the cured products are not prone to brittle failure. The cured products of adhesive compositions have good stability in performance for long-term use, and the functional groups are also high, so the heat resistance is also improved, which is more ideal. Epoxy compounds of styrene-butadiene block copolymers are more preferred. The epoxy compounds of styrene-butadiene block copolymers can promote the reaction speed and increase the crosslinking density because they have unsaturated bonds such as olefin skeletons and vinyl groups in addition to aromatic rings in the reaction of the epoxy structure. As a result, even a small amount of blending can still improve heat resistance and chemical resistance. In addition, the epoxy compounds of styrene-butadiene block copolymers, due to their large molecular weight and epoxy groups, can act like dispersants and make the inorganic filler more dispersible. The epoxy compound of the styrene-butadiene block copolymer can also use commercially available epoxy compounds, such as: CELLOXIDE 2021P, CELLOXIDE 2081, CELLOXIDE 2000 (manufactured by Da Cellulose Corporation), EPOLEAD GT401, EPOLEAD PB3600, EPOLEAD PB4700 (manufactured by Da Cellulose Corporation), EPOFRIEND AT501, EPOFRIEND CT310 (manufactured by Da Cellulose Corporation).

[Chemistry 1] R is a structure containing a methylene-aryl-methylene group or a structure containing an aliphatic hydrocarbon structure having 6 or more carbon atoms. Examples of the aryl group include benzene, xylene, naphthalene, biphenyl, etc., and examples of the aliphatic hydrocarbon include hexane, dimethylcyclohexane, dicyclopentadiene, etc. Specific examples of novolac-type epoxy resins include: "YX7700" manufactured by Mitsubishi Chemical Corporation (a novolac-type epoxy resin containing a xylene structure), "NC7000L" manufactured by Nippon Kayaku Co., Ltd. (a naphthol novolac-type epoxy resin), "ESN485" manufactured by Nippon Steel Chemical & Materials Co., Ltd. (a naphthol novolac-type epoxy resin), "N-690" manufactured by DIC Corporation (a cresol novolac-type epoxy resin), and "N-695" manufactured by DIC Corporation (a cresol novolac-type epoxy resin).

In addition, epoxy resins with amino groups can shorten the curing time or lower the curing temperature due to the catalytic effect of the amino groups, so the workability is improved. In addition, because it contains amino groups, the adhesion with the metal layer is improved. In particular, if the epoxy resin is a glycidylamine type epoxy resin, it is more ideal. Glycidylamine type epoxy resin is multifunctional, so it can be cured with a small amount. Because the molecular skeleton contains amines, it has good compatibility with styrene elastomers containing amino groups and has a reaction-promoting effect. In addition, because it contains amino groups, the adhesion with the metal layer is improved. Specific examples of epoxy resins of the epoxy propylamine type include, for example, tetraethylene glycol diamino diphenylmethane, "jER604" manufactured by Mitsubishi Chemical Co., Ltd., "SUMIEPOXY ELM434" manufactured by Sumitomo Chemical Co., Ltd., "ARALDITE MY720", "ARALDITE MY721", "ARALDITE MY9512", "ARALDITE MY9612", "ARALDITE MY9634", "ARALDITE MY9663" manufactured by Huntsman Advanced Materials Co., Ltd., "TETRAD-X", "TETRAD-C" manufactured by Mitsubishi Gas Chemical Co., Ltd., etc.

The epoxy resin used in the present invention preferably has two or more epoxy groups in one molecule. The reason is that it can form a cross-linked structure when reacting with a carboxyl-containing styrene elastomer, thereby exhibiting high heat resistance. In addition, when an epoxy resin having two or more epoxy groups is used, the degree of cross-linking with a carboxyl-containing styrene elastomer is sufficient, and sufficient heat resistance can be obtained.

The content of the epoxy resin is preferably 1 to 25 parts by weight relative to 100 parts by weight of the resin composition. If the content of the epoxy resin is above the lower limit, the adhesive composition will be sufficiently hardened, and good heat resistance and chemical resistance can be ensured. On the other hand, if the content of the epoxy resin is too high, the adhesion will decrease, so if it is below the upper limit, good adhesion can be ensured.

The softening point or melting point of the epoxy resin is preferably below 90°C. If the softening point or melting point of the epoxy resin is below 90°C, the glass transition point of the adhesive composition decreases, the elastic modulus of the adhesive composition before curing in the high temperature range decreases, and the elastic modulus of the adhesive composition after curing in the normal temperature range (room temperature) can be improved. In addition, it is more ideal if the epoxy resin is dissolved at the reaction temperature because the reaction is fast.

＜＜Other resin components＞＞ In addition to the above-mentioned styrene elastomer and the epoxy resin contained appropriately, the resin composition may contain other thermoplastic resins other than styrene elastomers to the extent that the functions of the adhesive composition are not affected.

The above-mentioned other thermoplastic resins include, for example, phenoxy resins, polyamide resins, polyester resins, polycarbonate resins, polyphenylene ether resins, polyurethane resins, polyacetal resins, polyethylene resins, polypropylene resins, and polyvinyl resins. These thermoplastic resins may be used alone or in combination of two or more.

<Inorganic filler> The inorganic filler has a plate-like or scaly shape. The content of the inorganic filler contained in the adhesive composition of the present invention is 1 to 180 parts by mass relative to 100 parts by mass of the resin composition. It is more ideal if the content of the inorganic filler is 30 to 175 parts by mass relative to 100 parts by mass of the resin composition. If the content of the inorganic filler is within the above range, the mechanical properties can be controlled to a suitable range, and both the prevention of resin flow and good adhesion can be taken into account.

If the inorganic filler of the present invention has a plate-like or scaly shape, there is no special restriction on the type, and it can be appropriately selected according to the purpose. For example, from the perspective of heat resistance and dielectric properties, silicon-based inorganic fillers and boron nitride are preferred. Moreover, among silicon-based inorganic fillers, natural mica, synthetic mica, and natural talc are preferred from the perspective of aspect ratio, and synthetic mica is preferred from the perspective of water absorption. They can be used alone or in combination of two or more. In the present invention, an inorganic filler of a specific shape and a specific amount is contained in the adhesive composition, and an adhesive layer is formed by the adhesive composition. The obtained adhesive layer can prevent the resin from flowing during hot pressing, and becomes an adhesive layer with good electrical properties and good adhesion.

The average particle size of the inorganic filler of the present invention is preferably 3.0 μm or less. The average particle size of the inorganic filler can be calculated by, for example, laser scattering method. In addition, the aspect ratio of the inorganic filler is preferably 5 or more and 500 or less in view of the coefficient of thermal expansion (CTE) and film strength.

[Determination of aspect ratio] For the aspect ratio of inorganic fillers, for example, a scanning electron microscope (SEM) or a transmission electron microscope (TEM) can be used to observe and obtain the aspect ratio from the average of the measured values. For example, for the aspect ratio of inorganic fillers present in a thin film (layer), the thin film can be embedded with epoxy resin, and then the thin film cross section can be ion-polished using an ion polishing device to obtain a sample for cross-section observation. The cross section of the obtained sample can be observed using a scanning electron microscope (SEM) or a transmission electron microscope (TEM), and the aspect ratio can be obtained from the average of the measured values of the length and thickness in the plane direction of the inorganic filler.

The content of inorganic filler in the film is preferably 1~50 volume %. The content of inorganic filler in the film is more ideally 2~30 volume %. If the content of inorganic filler is above the above lower limit, the resin of the adhesive layer can be prevented from flowing. If the content of inorganic filler is below 50 volume %, the dispersibility and heat resistance of inorganic filler will be better. If the content of inorganic filler is below 30 volume %, good adhesion can be ensured.

<Other ingredients> In addition to the above-mentioned styrene elastomer and inorganic filler, the adhesive composition may contain, for example, adhesives, flame retardants, hardeners, hardening accelerators, coupling agents, heat aging inhibitors, leveling agents, defoaming agents, pigments, and solvents as other ingredients to the extent that they do not affect the functions of the adhesive composition.

The above-mentioned adhesives include, for example, coumarone-indene resins, terpene resins, terpene-phenolic resins, rosin resins, p-tert-butylphenol-acetylene resins, phenol-formaldehyde resins, xylene-formaldehyde resins, petroleum hydrocarbon resins, hydrogenated hydrocarbon resins, turpentine resins, etc. These adhesives may be used alone or in combination of two or more.

The flame retardant may contain any of an organic flame retardant and an inorganic flame retardant. Organic flame retardants include, for example, melamine phosphate, melamine polyphosphate, guanidine phosphate, guanidine polyphosphate, ammonium phosphate, ammonium polyphosphate, ammonium phosphate amide, ammonium polyphosphate amide, phosphocarbamate, polyphosphocarbamate, aluminum tris(diethylphosphinate), aluminum tris(methylethylphosphinate), aluminum tris(diphenylphosphinate), zinc bis(diethylphosphinate), zinc bis(methylethylphosphinate), zinc bis(diphenylphosphinate), titanium bis(diethylphosphinate), tetrakis(tetrakis(diethylphosphinate), and tetrakis(tetrakis(diphenylphosphinate). Phosphorus-based flame retardants such as titanium (diethylphosphinate), titanium bis(methylethylphosphinate), titanium tetrakis(methylethylphosphinate), titanium bis(diphenylphosphinate), titanium tetrakis(diphenylphosphinate); nitrogen-based flame retardants such as melamine, melam, melamine cyanurate, cyanuric acid compounds, isocyanuric acid compounds, triazole compounds, tetrazole compounds, diazo compounds, urea, etc.; silicon-based flame retardants such as polysiloxane compounds and silane compounds, etc. 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 may be used in combination.

The above-mentioned hardeners include, but are not limited to, amine hardeners, acid anhydride hardeners, etc. Amine hardeners include, for example, methylated melamine resins, butylated melamine resins, benzoguanamine resins, melamine resins, dicyandiamide, 4,4'-diphenyldiamine, etc. Acid anhydrides include aromatic acid anhydrides and aliphatic acid anhydrides. These hardeners can be used alone or in combination of two or more. The content of the hardener is preferably 0.5 to 100 parts by mass, and more preferably 5 to 70 parts by mass, relative to 100 parts by mass of the adhesive composition.

The above-mentioned curing accelerator is used to promote the reaction between carboxyl-containing styrene elastomer and epoxy resin. Tertiary amine curing accelerator, tertiary amine salt curing accelerator and imidazole curing accelerator can be used. By adding the above-mentioned curing accelerator, the reaction can be carried out quickly, and the resin can be cured before it flows out, which can effectively prevent the resin from flowing.

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

Examples of the tertiary amine salt-based hardening accelerator include 1,8-diazobicyclo[5.4.0]undecene formate, octanoate, p-toluenesulfonate, phthalate, phenol salt or phenol novolac resin salt, 1,5-diazobicyclo[4.3.0]nonene formate, octanoate, p-toluenesulfonate, phthalate, phenol salt or phenol novolac resin salt, etc.

Imidazole hardening 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'-undecyl- 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.

When the adhesive composition contains a hardening accelerator, the content of the hardening accelerator is preferably 0.05 to 10 parts by mass, and more preferably 0.1 to 5 parts by mass, relative to 100 parts by mass of the adhesive composition. If the content of the hardening accelerator is within the above range, the reaction between the styrene elastomer and the epoxy resin and the reaction between the epoxy resins are easy to proceed, and it is easy to ensure adhesion and heat resistance.

In addition, the coupling agent may include silane-based coupling agents such as vinyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, p-phenylenetrimethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, 3-acryloxypropyltrimethoxysilane, N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, 3-ureidopropyltriethoxysilane, 3-butylpropylmethyldimethoxysilane, bis(triethoxysilyl)tetrasulfide, 3-isocyanatopropyltriethoxysilane, and imidazole silane; titanium-based coupling agents; aluminum-based coupling agents; zirconium-based coupling agents, and the like. They can be used individually or in combination of 2 or more.

Examples of the heat aging inhibitor include phenolic oxidation inhibitors such as 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-tert-butyl-4-hydroxyphenol)], and triethylene glycol-bis[3-(3-tert-butyl-5-methyl-4-hydroxyphenyl) propionate]; sulfur-based oxidation inhibitors such as dilauryl-3,3'-dithiodipropionate and dimyristyl-3,3'-dithiopropionate; phosphorus-based oxidation inhibitors such as tris-nonylphenyl phosphite and tris-(2,4-di-tert-butylphenyl) phosphite; and the like. These can be used individually or in combination of two or more.

<Characteristics of the adhesive layer composed of the adhesive composition> The adhesive layer composed of the adhesive composition of the present invention is formed by filming the adhesive composition and curing it. The curing method is not particularly limited and can be appropriately selected according to the purpose, such as thermal curing. The thickness of the adhesive layer is not particularly limited and can be appropriately selected according to the purpose. For example, from the perspective of thin filmization, 3~100μm is preferred, 5~70μm is more preferred to ensure the sealing force, and 10~50μm is more ideal to more accurately control the resin flow.

The relative dielectric constant (εr) of the adhesive layer formed by curing the adhesive composition of the present invention at a frequency of 28 GHz is 3.5 or less, and the dielectric tangent (tanδ) of the adhesive layer at a frequency of 28 GHz is 0.005 or less. Furthermore, it is more ideal that the relative dielectric constant is 3.2 or less and the dielectric tangent is 0.002 or less. If the relative dielectric constant is 3.5 or less and the dielectric tangent is 0.005 or less, it can be applied even to FPC-related products with strict requirements on electrical properties. If the relative dielectric constant is 3.2 or less and the dielectric tangent is 0.002 or less, attenuation can be further reduced even during high-frequency transmission.

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

For the storage elastic modulus of the adhesive layer at 25°C after the adhesive composition of the present invention is cured, it is preferably 1.0E+8Pa or more from the perspective of the close adhesion when the laminate is stacked. In addition, the storage elastic modulus of the adhesive layer at 25°C after the adhesive composition is cured is preferably 1.0E+9Pa or less. If the storage elastic modulus is within the above range, the close adhesion when the laminate is stacked can be maintained. For the storage elastic modulus of the adhesive layer at 150°C before the adhesive composition of the present invention is cured, it is preferably 1.0E+5Pa or more and 1.0E+8Pa or less from the perspective of the close adhesion. In addition, considering the adhesion to the adherend surface, 1.0E+5Pa to 1.0E+7Pa is better, and considering the resin flow, 1.0E+6Pa to 1.0E+7Pa is even better. If the storage elastic modulus is within the above range, the mechanical properties can be controlled during heat pressing, and both resin flow and adhesion can be taken into account, so it is ideal.

[Storage elastic modulus (Pa)] The storage elastic modulus of the adhesive layer can be obtained by, for example, preparing an adhesive film with a thickness of 100 μm for a sample composed of an adhesive layer, and measuring it using a viscoelasticity measuring device (RSA-G2 manufactured by TA Instruments, at a measuring frequency of 1 Hz and a heating rate of 5°C/min in accordance with JIS K7244.

The thermal expansion coefficient (CTE) of the adhesive layer formed by curing the adhesive composition of the present invention is preferably 500ppm/K or less. If the thermal expansion coefficient is below the above value, the deformation during heat pressing is small, which is more ideal. The thermal expansion coefficient is measured, for example, by using a thermomechanical analyzer [manufactured by Hitachi HitechScience: SII//SS7100] in a tensile mode, with a load of 50mN and a heating rate of 5℃/min., from 25℃ to 250℃, and measuring the temperature change of the size, and calculating the linear expansion coefficient from the slope of the range of 25℃ to 125℃.

<Method for producing adhesive layer> The adhesive layer can be produced by forming the above-mentioned adhesive composition into a film. The above-mentioned adhesive composition can be produced by mixing a resin composition containing at least a styrene-based elastomer, an inorganic filler, and other resin components and other components as required. The mixing method is not particularly limited as long as the adhesive composition becomes uniform. The adhesive composition is preferably used in the form of a solution or a dispersion, so a solvent is usually used. Solvents, such as: alcohols such as methanol, ethanol, isopropanol, n-propanol, isobutanol, n-butanol, benzyl alcohol, ethylene glycol monomethyl ether, propylene glycol monomethyl ether, diethylene glycol monomethyl ether, diacetone alcohol, etc.; ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, methyl amyl ketone, cyclohexanone, isophorone, etc.; aromatic hydrocarbons such as toluene, xylene, ethylbenzene, mesitylene, etc.; esters such as methyl acetate, ethyl acetate, ethylene glycol monomethyl ether acetate, 3-methoxybutyl acetate, etc.; aliphatic hydrocarbons such as hexane, heptane, cyclohexane, methylcyclohexane, etc. These solvents may be used alone or in combination of two or more. If the adhesive composition is a solution or dispersion (resin varnish) containing a solvent, the coating of the substrate film and the formation of the adhesive layer can be carried out smoothly, and the adhesive layer of the expected thickness can be easily obtained. When the adhesive composition contains a solvent, the solid content concentration is preferably 3 to 80% by mass, and more preferably 10 to 50% by mass, taking into account the workability of the formation of the adhesive layer. If the solid content concentration is less than 80% by mass, the viscosity of the solution is appropriate and it is easy to apply evenly. A more specific implementation of the method for manufacturing the adhesive layer is to apply a resin varnish containing the above-mentioned adhesive composition and a solvent on the surface of the base film, and after forming the resin varnish layer, remove the solvent from the resin varnish layer to form a B-stage adhesive layer. Here, the adhesive layer is in the B-stage state, which means that the adhesive composition is in an uncured state or a semi-cured state where a part of the adhesive composition begins to cure, and the curing of the adhesive composition will further proceed by heating, etc. Here, the method of applying the resin varnish on the substrate film is not particularly limited and can be appropriately selected according to the purpose, such as spray coating, spin coating, dip coating, roller coating, knife coating, scraper roller method, scraper blade method, curtain coating, slit coating, screen printing, inkjet method, glue dispensing method, etc. The above-mentioned B-stage adhesive layer can be further heated to form a hardened adhesive layer.

(Laminate) The laminate of the present invention comprises: a substrate film, and the above-mentioned adhesive layer on at least one surface of the substrate film.

<Base film> The base film used in the present invention can be selected from the purpose of the laminate. For example, when the laminate is used as a surface coating film or a copper-clad laminate (CCL), polyimide film, polyetheretherketone film, polyphenylene sulfide film, aromatic polyamide film, polyethylene naphthalate film, and liquid crystal polymer film can be listed. Among them, polyimide film, polyetheretherketone (PEEK) film, polyethylene naphthalate film, and liquid crystal polymer film are preferred from the perspective of adhesion and electrical properties.

Furthermore, when the laminate of the present invention is used as an adhesive sheet, the base film needs to 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 resin film.

When the laminate of the present invention is used as a shielding film, the base film must be a film with electromagnetic wave shielding capability, such as a laminate of a protective insulating layer and a metal foil.

(Surface coating film) One of the ideal implementation forms of the laminate of the present invention is a surface coating film. When manufacturing FPC, in order to protect the wiring part, a laminate having an adhesive layer called a "surface coating film" is usually used. This surface coating film has: an insulating resin layer and an adhesive layer formed on its surface. For example: the surface coating film is a laminate in which the above-mentioned adhesive layer is formed on at least one surface of the above-mentioned base film, and the base film and the adhesive layer are generally difficult to peel off. The thickness of the base film contained in the surface coating film is preferably 5~100μm, more preferably 5~50μm, and more preferably 5~30μm. If the thickness of the base film is below the upper limit, the surface coating film can be thinned. If the thickness of the base film is above the lower limit, the printed wiring board can be easily designed and the operability is also good. The method of manufacturing the surface coating film, for example: after applying the resin varnish containing the above-mentioned adhesive composition and the solvent on the surface of the above-mentioned base film to form a resin varnish layer, the solvent is removed from the resin varnish layer to manufacture a surface coating film having formed a B-stage adhesive layer. The drying temperature when removing the solvent is preferably 40~250℃, and more preferably 70~170℃. Drying can be performed by passing the laminated body coated with the adhesive composition through a furnace that has been subjected to hot air drying, far infrared heating, and high-frequency induction heating. In addition, if necessary, a release film can be laminated on the surface of the adhesive layer for preservation. The release film can use known products such as polyethylene terephthalate film, polyethylene film, polypropylene film, silicone release paper, polyolefin resin coated paper, TPX film, fluorine resin film, etc. The surface coating film of the present invention uses the low-dielectric adhesive composition of the present invention, so high-speed transmission of electronic equipment can be carried out, and the bonding stability with the electronic equipment is also excellent.

(Adhesive sheet) One of the ideal embodiments of the laminate of the present invention is an adhesive sheet. The adhesive sheet is a sheet having the above-mentioned adhesive layer formed on the surface of a release film (base film). In addition, the adhesive sheet may be a sheet having an adhesive layer between two release films. When using the adhesive sheet, the release film is peeled off before use. The release film may be the same as that described in the above-mentioned (surface coating film) field. The thickness of the base film contained in the adhesive sheet is preferably 5 to 100 μm, more preferably 25 to 75 μm, and more preferably 38 to 50 μm. If the thickness of the base film is within the above-mentioned range, the adhesive sheet is easy to manufacture and has good operability. The method of manufacturing the adhesive sheet includes, for example, coating a resin varnish containing the above-mentioned adhesive composition and a solvent on the surface of a release film, and then performing the same process as the above-mentioned surface coating film and drying. The adhesive sheet of the present invention uses the low-dielectric adhesive composition of the present invention, so high-speed transmission of electronic equipment is possible, and the bonding stability with the electronic equipment is also excellent.

(Copper-clad laminate (CCL)) One ideal embodiment of the laminate of the present invention is to laminate copper foil to an adhesive layer in the laminate of the present invention to form a copper-clad laminate. The copper-clad laminate is formed by laminating copper foil using the laminate, for example, in the order of a substrate film, an adhesive layer, and a copper foil. In addition, an adhesive layer and a copper foil may be formed on both sides of the substrate film. The adhesive composition used in the present invention also has excellent adhesion to copper-containing articles. The copper-clad laminate of the present invention uses the low-dielectric adhesive composition of the present invention, so high-speed transmission of electronic equipment is possible and the bonding stability is excellent.

The method of manufacturing the copper-clad laminate includes, for example, bringing the adhesive layer of the laminate into surface contact with the copper foil, performing heat lamination at 80°C to 150°C, and then curing the adhesive layer by post-curing. The post-curing conditions may be, for example, 100°C to 200°C for 30 minutes to 4 hours in an inert gas environment. The copper foil is not particularly limited, and electrolytic copper foil, rolled copper foil, etc. may be used.

(Printed wiring board) One ideal embodiment of the laminate of the present invention is a printed wiring board formed by bonding copper wiring to an adhesive layer in the laminate of the present invention. The printed wiring board can be obtained by forming an electronic circuit on the above-mentioned copper-clad laminate. The printed wiring board is formed in the order of a base film, an adhesive layer and copper wiring by using the above-mentioned laminate. In addition, an adhesive layer and copper wiring can be formed on both sides of the base film. For example, a printed wiring board can be manufactured by bonding a surface coating film to a surface having a wiring portion via an adhesive layer by using hot pressing, etc. The printed wiring board of the present invention uses the low-dielectric adhesive composition of the present invention, so high-speed transmission of electronic equipment is possible, and the bonding stability with the electronic equipment is also excellent. The method of manufacturing the printed wiring board of the present invention includes, for example, making the adhesive layer of the above-mentioned laminated body contact with the copper wiring, performing heat lamination at 80°C~150°C, and then curing the adhesive layer by post-curing. The post-curing conditions can be, for example, 30 minutes to 4 hours at 100°C~200°C. The shape of the above-mentioned copper wiring is not particularly limited, and an appropriate shape can be selected according to needs.

(Shielding film) One of the ideal implementation forms of the laminate of the present invention is a shielding film. The shielding film is a film used to shield various electronic devices in order to cut off electromagnetic wave noise that may affect various electronic devices such as computers, mobile phones, and analytical equipment and become the cause of malfunction. It is also called an electromagnetic wave shielding film. The electromagnetic wave shielding film is formed by stacking, for example, an insulating resin layer, a metal layer, and an 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, so high-speed transmission of electronic devices is possible, and the bonding stability with the electronic devices is also excellent.

(Printed wiring board with shielding film) One of the ideal embodiments of the laminate of the present invention is a printed wiring board with shielding film. The printed wiring board with shielding film is a printed wiring board having a printed circuit on at least one side of a substrate, to which the above-mentioned electromagnetic wave shielding film is attached. The printed wiring board with shielding film, for example, comprises: a printed wiring board; an insulating film adjacent to the side of the printed wiring board having the printed circuit; and the above-mentioned electromagnetic wave shielding film. The printed wiring board with shielding film of the present invention uses the low-dielectric adhesive composition of the present invention, so that high-speed transmission of electronic equipment is possible, and further the bonding stability with the electronic equipment is also excellent. [Example]

The following examples are given to further describe the present invention, but the scope of the present invention is not limited to these examples. In addition, in the following, unless otherwise specified, parts and % are based on mass.

(Carboxyl-containing styrene elastomer) Used the product name "TUFTEC M1913" (maleic acid-modified styrene-ethylene butylene-styrene block copolymer) manufactured by Asahi Kasei Corporation. The acid value of this copolymer is 10 mgKOH/g, the styrene/ethylene butylene ratio is 30/70, and the weight average molecular weight is 67,000. (Carboxyl-containing styrene elastomer) Used the product name "TUFTEC M1911" (maleic acid-modified styrene-ethylene butylene-styrene block copolymer) manufactured by Asahi Kasei Corporation. The acid value of this copolymer is 2 mgKOH/g, the styrene/ethylene butylene ratio is 30/70, and the weight average molecular weight is 69,000. (Carboxyl-free styrene elastomer) Used the product name "TUFTEC P1500" (hydrogenated styrene elastomer) manufactured by Asahi Kasei Corporation. The acid value of this copolymer is 0 mgKOH/g, the styrene/ethylene butylene ratio is 30/70, and the weight average molecular weight is 67,000. (Amino-containing styrene elastomer) The product name "TUFTEC MP10" (amine-modified hydrogenated styrene-butadiene copolymer (amine-modified styrene-ethylene butylene-styrene copolymer) manufactured by Asahi Kasei Corporation was used. The styrene ratio of this copolymer is 30, and the weight average molecular weight is 78,000. (Epoxy resin) The product name "HP-7200" (epoxy resin, softening point 56-66°C) manufactured by DIC Corporation was used. (Epoxy resin) The product name "EPOFRIEND CT310" (epoxide of styrene-butadiene block copolymer) manufactured by Daicell Corporation was used. The copolymer has a styrene/ethylene butene ratio of 40/60, a weight average molecular weight of 93,000, and an epoxy equivalent of 2125 g/eq. (Solvent) A mixed solvent consisting of toluene and methyl ethyl ketone (mass ratio = 90:10) was used. (Base film) "Shin-Etsu Sepla Film PEEK" (polyetheretherketone, thickness 50μm) manufactured by Shin-Etsu Polymer Co., Ltd. was used as the base film. (Electrolytic copper foil) "TQ-M7-VSP" (electrolytic copper foil, thickness 12μm, glossy surface Rz 1.27μm, glossy surface Ra 0.197μm, glossy surface Rsm 12.95μm) manufactured by Mitsui Mining and Co., Ltd. was used as the electrolytic copper foil. The surface roughness of the glossy surface is the value obtained from the roughness curve measured using a laser microscope in accordance with JIS B0601: 2013 (ISO 4287: 1997 Amd. 1: 2009). (Release film) NP75SA (polysilicone release PET film, 75 μm) manufactured by PANAC was used as the release film. (Filler) The fillers listed below were used as the fillers. MK-100DS MICROMICA (mica) (made by Katakura & Co-op Agri) aspect ratio 27.5 UHP-S2 hexagonal boron nitride (made by Showa Denko) aspect ratio 6 MX-300 acrylic particles (made by Soken Chemical) SQ-C8 silica (made by Admatechs) MC6000 melamine isocyanurate (made by Nissan Chemical)

(Example 1) The components constituting the resin composition shown in Table 1 are contained in the proportions shown in Table 1, and a resin composition is prepared. Then, the components constituting the adhesive layer shown in Table 2 are contained in the proportions shown in Table 2, and these components are dissolved in a solvent to prepare a resin varnish having a solid component concentration of 20 mass%. The shape and average particle size of the filler used are shown in Table 2. The surface of the substrate film is subjected to a corona treatment. The resin varnish is applied to the surface of the substrate film and dried in an oven at 110°C for 4 minutes to volatilize toluene to form an adhesive layer, thereby obtaining a substrate film with an adhesive. The adhesive layer of the adhesive laminate is laminated in such a way that it contacts the glossy surface of the electrolytic copper foil, and heat lamination is performed at 120°C to obtain a pre-cured adhesive laminate. The pre-cured adhesive laminate is pressed at 180°C and 3MPa for 3 minutes, and then post-cured at 180°C for 30 minutes to cure the adhesive layer and obtain a post-cured adhesive laminate. The adhesion (N/cm) between the electrolytic copper foil and the substrate film of the post-cured adhesive laminate of Example 1 is measured.

[Adhesion (N/cm)] For adhesion, the cured adhesive layer was cut into a test piece with a width of 25 mm. According to JIS Z0237:2009 (Testing methods for adhesive tapes and adhesive sheets), the peeling speed was 0.3 m/min and the peeling angle was 180°. The peeling strength was measured when the electrolytic copper foil was peeled off from the base film with adhesive fixed on the support to measure the adhesion.

Furthermore, the storage elastic modulus (Pa) at 25°C after curing and at 150°C before curing was also measured.

[Storage elastic modulus (Pa)] The storage elastic modulus of the adhesive layer is measured by making a 100μm thick adhesive film for a sample composed of an adhesive layer using a viscoelasticity measuring device (RSA-G2 manufactured by TA Instruments, with a measurement frequency of 1Hz and a heating rate of 5℃/min in accordance with JIS K7244 was used for the measurement. The test sample was coated with a resin varnish roll on a release film, and then the coated film was placed in an oven and dried at 110°C for 4 minutes to form a B-stage adhesive layer (50μm thick). The adhesive layer was then thermally laminated at 120°C with the bonding surfaces in contact with each other to form a pre-curing adhesive film (100μm thick) to produce a pre-curing adhesive film (100mm×100mm). The release film was peeled off from the adhesive film, and the storage elastic modulus (Pa) of the pre-curing adhesive layer was measured. In addition, the uncured adhesive film (thickness 100μm) was placed in an oven and heat-cured at 150℃ for 60 minutes to produce a cured adhesive film (100mm×100mm). The release film was peeled off from the adhesive film, and the storage elastic modulus (Pa) of the cured adhesive layer was measured.

The relative dielectric constant and dielectric tangent of the adhesive layer in the cured adhesive stack of Example 1 were also measured at a frequency of 28 GHz.

[Relative dielectric constant and dielectric tangent] The relative dielectric constant and dielectric tangent of the adhesive layer can be measured by 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). The test sample is a resin varnish roll applied to a release film, and then the film with the film is placed in an oven and dried at 110°C for 4 minutes to form a B-stage adhesive layer (thickness 50μm). This adhesive layer is then thermally laminated at 120°C with the bonding surfaces in contact with each other to form a pre-cured adhesive film (thickness 100μm). The uncured adhesive film (thickness 100μm) was placed in an oven and heated and cured at 150℃ for 60 minutes to obtain a cured adhesive film (100mm×100mm). The release film was peeled off from the cured adhesive film, and the relative dielectric constant and dielectric tangent of the adhesive layer were measured.

The thermal expansion coefficient (CTE) of the adhesive layer in the adhesive stack after curing in Example 1 was also measured at 30-50°C.

[Thermal expansion coefficient (CTE)] The thermal expansion coefficient is measured, for example, by using a thermomechanical analyzer [manufactured by Hitachi Hitech Science: SII//SS7100] in a tensile mode, with a load of 50 mN and a heating rate of 5°C/min., from 25°C to 250°C, and measuring the temperature change of the dimensions, and calculating the linear expansion coefficient from the slope in the range of 30°C to 50°C.

A solder heat resistance test was performed on the cured adhesive stack of Example 1.

[Solder heat resistance test] The solder heat resistance test is to float the cured adhesive layer in a 288°C solder bath for 10 seconds x 3 times with the substrate film facing up to check whether the adhesive layer has any appearance abnormalities such as swelling or peeling. The heat resistance of the laminate is evaluated according to the following evaluation criteria. ◎ No abnormality (no dissolution). ○ No abnormality in the end, but softening of the adhesive layer was observed during the test. △ No peeling, but the adhesive layer softened and "spots" appeared. × Peeling.

For the laminate of Example 1, a resin flow test of the adhesive layer during the manufacture of the laminate was performed.

[Resin flow test] The resin flow test is to cut the base film with adhesive into a size of 30mm×90mm, and use a belt punch to punch 3 holes with a diameter of 5mm. The adhesive layer of the base film with adhesive and the glossy surface of the electrolytic copper foil are overlapped in contact, and heat-laminated at 150℃. Pressed at 180℃ and 3MPa for 3 minutes, the length of the resin overflowing from the copper foil at 12 points is measured with a microscope [made by KEYENCE, product name: DIGITAL MICROSCOPE VHX-500, lens magnification: 300 times] (4 points×3 points), and the average value is recorded.

The test results are shown in Table 3.

(Example 2 to Example 11) The types and blending amounts of the components constituting the adhesive layer in Example 1 were changed as shown in Tables 1 and 2, and the laminates of Example 2 to Example 11 were prepared in the same manner as in Example 1. The prepared laminates were evaluated in the same manner as in Example 1. The results are shown in Table 3.

(Comparative Example 1 to Comparative Example 8) The types and blending amounts of the components constituting the adhesive layer in Example 1 were changed as shown in Tables 1 and 2. The same procedures as in Example 1 were followed to prepare the laminates of Comparative Example 1 to Comparative Example 8. The prepared laminates were evaluated in the same manner as in Example 1. The results are shown in Table 3.

[Table 1] Components of resin composition (by mass) Resin No. M1913 M1911 MP10 P1500 HP-7200 CT310 A 94.3 5.7 B 90.9 9.1 C 47.5 47.5 5 D 47.5 47.5 5 E 47.5 47.5 5 F 95 5

[Table 2] Adhesive composition (mass) Volume (vol/%) Filler shape Average particle size of filler (μm) Resin No. Resin content Filler Type Addition amount Embodiment 1 A 100 MK-100DS 74 20 Scales 2.9 Embodiment 2 A 100 UHP-S2 61 20 Scales 0.7 Embodiment 3 B 100 MK-100DS 71 20 Scales 2.9 Embodiment 4 B 100 UHP-S2 59 20 Scales 0.7 Embodiment 5 C 100 MK-100DS 78 20 Scales 2.9 Embodiment 6 C 100 UHP-S2 65 20 Scales 0.7 Embodiment 7 C 100 MK-100DS 174 45 Scales 2.9 Embodiment 8 C 100 UHP-S2 147 45 Scales 0.7 Embodiment 9 D 100 MK-100DS 78 20 Scales 2.9 Embodiment 10 E 100 MK-100DS 78 20 Scales 2.9 Embodiment 11 F 100 UHP-S2 65 20 Scales 0.7 Comparison Example 1 A 100 - - - - - Comparison Example 2 B 100 SQ-C8 57 20 ball 2.6 Comparison Example 3 C 100 - - - - - Comparison Example 4 A 100 SQ-C8 59 20 ball 2.6 Comparison Example 5 A 100 MC6000 41 20 Amorphous 2.0 Comparative Example 6 B 100 - - - - - Comparison Example 7 B 100 MC6000 39 20 Amorphous 2.0 Comparative Example 8 B 100 MX-300 31 20 ball 3.0

[Table 3] The sealing force of the laminate (N/cm) Relative dielectric constant of adhesive layer at 28 GHz Dielectric tangent of adhesive layer at 28 GHz Storage elastic modulus of the adhesive layer at 25℃ after curing (Pa) Storage elastic modulus of uncured adhesive layer at 150℃ (Pa) Thermal expansion coefficient (CTE) of adhesive layer at 30-50℃ Solder heat resistance test of laminated body Resin flow of laminate (µm) Embodiment 1 7.6 3.0 0.0034 3.E+08 6.E+06 97 ○ 52 Embodiment 2 7.3 3.1 0.0040 5.E+08 3.E+06 130 〇 65 Embodiment 3 7.0 3.0 0.0050 1.E+08 3.E+05 238 ○ 66 Embodiment 4 6.9 3.0 0.0049 2.E+08 5.E+05 192 ○ 62 Embodiment 5 8.0 2.9 0.0013 9.E+07 5.E+05 95 ◎ 141 Embodiment 6 8.3 2.9 0.0011 6.E+07 3.E+05 127 ◎ 156 Embodiment 7 6.8 3.3 0.0014 9.E+08 7.E+07 75 ○ 43 Embodiment 8 7.0 3.5 0.0014 4.E+08 1.E+07 121 ○ 34 Embodiment 9 7.7 3.0 0.0015 9.E+07 5.E+05 100 ○ 145 Embodiment 10 8.1 2.9 0.0013 1.E+08 5.E+05 94 ○ 142 Embodiment 11 6.0 2.8 0.0014 1.E+08 5.E+05 220 ○ 165 Comparison Example 1 9.3 2.4 0.0042 1.E+08 2.E+05 179 ○ 335 Comparison Example 2 6.0 2.8 0.0052 1.E+08 1.E+05 240 ○ 188 Comparison Example 3 8.6 2.4 0.0011 3.E+07 2.E+04 177 ○ 304 Comparison Example 4 5.4 2.5 0.0037 3.E+08 7.E+05 80 ○ 68 Comparison Example 5 8.7 2.9 0.0193 4.E+08 1.E+06 90 ○ 76 Comparison Example 6 8.5 2.5 0.0063 5.E+07 3.E+04 539 ○ 236 Comparative Example 7 6.8 2.5 0.0186 2.E+08 2.E+05 263 ○ 65 Comparative Example 8 7.5 2.5 0.0054 1.E+08 2.E+05 290 ○ 93 As shown in the examples, the adhesive layer composed of the adhesive composition of the present invention can prevent the resin from flowing during hot pressing by controlling the mechanical properties, exhibit good electrical properties, and also have excellent adhesion. [Industrial Applicability]

The laminate having the adhesive layer composed of the adhesive composition of the present invention is suitable for manufacturing FPC-related products for electronic equipment such as smart phones, mobile phones, optical modules, digital cameras, game consoles, notebook computers, medical devices, etc.

Claims (12)

An adhesive composition contains at least a resin composition containing a modified styrene elastomer and an inorganic filler, wherein the content of the inorganic filler is 1 to 180 parts by mass relative to 100 parts by mass of the resin composition, the inorganic filler has a plate-like or scale-like shape, and the relative dielectric constant of the adhesive layer formed by curing the adhesive composition at a frequency of 28 GHz is less than 3.5, the dielectric tangent of the adhesive layer at a frequency of 28 GHz is less than 0.005, and the storage elastic modulus of the adhesive layer before curing of the adhesive composition at 150°C is greater than 1.0E+5Pa and less than 1.0E+8Pa. As in the adhesive composition of claim 1, the aspect ratio of the inorganic filler is 5 to 500. As in the adhesive composition of claim 1, wherein the average particle size of the inorganic filler is less than 3.0 μm. As in claim 1, the adhesive composition, wherein the inorganic filler contains at least one of a silicon-based inorganic filler and boron nitride. As in claim 4, the adhesive composition, wherein the silicon-based inorganic filler contains at least one of mica and talc. As in the adhesive composition of claim 1, wherein the modified styrene elastomer is a carboxyl-containing styrene elastomer. As in the adhesive composition of claim 1, wherein the modified styrene-based elastomer is an amino-containing styrene-based elastomer. As in claim 1, the adhesive composition, wherein the resin composition contains epoxy resin. As in claim 8, the content of the epoxy resin is 1 to 25 parts by weight relative to 100 parts by weight of the resin composition. A laminated body comprising: a substrate film, and an adhesive layer composed of an adhesive composition as described in any one of claims 1 to 9. As in claim 10, the laminate, wherein the substrate film contains polyetheretherketone (PEEK) resin. A printed wiring board comprising a laminate as claimed in claim 10 or 11.