Adhesive composition

Abstract

The present invention provides an adhesive composition for forming a low-dielectric adhesive layer that has both heat resistance and chemical resistance (solvent resistance), the adhesive composition exhibiting satisfactory bonding properties, with respect to a low-dielectric base material film having poor bonding properties, while having satisfactory electrical properties (dielectric properties) capable of handling 5G.　Said adhesive composition contains a styrene-based elastomer and an epoxy-modified resin having a structure represented by formula (1) below. (R1, R2, R3, and R4 are each independently hydrogen or an organic group. Note that at least one of R1 and R2 is an organic group, and at least one of R3 and R4 is an organic group.)

Description

Technical Field

[0001] The present invention relates to an adhesive composition. Specifically, it relates to an adhesive composition that can be used for adhesive applications such as electronic components.

Background Art

[0002] With the miniaturization and weight reduction of electronic devices, etc., the adhesive applications for electronic components, etc. have diversified, and the demand for laminates with an adhesive layer has been increasing. In addition, in a flexible printed wiring board (hereinafter also referred to as FPC), which is one of the electronic components, it is necessary to process a large amount of data at high speed, and the response to high frequencies is progressing. For the high-frequencyization of FPC, it is necessary to reduce the dielectric constant of the components, and the development of a base film with a low dielectric constant and an adhesive with a low dielectric constant has been carried out. In particular, in order to efficiently transmit signals having frequencies in the 3.5 GHz and 28 GHz bands used in the fifth-generation mobile communication system (hereinafter also referred to as 5G), the importance of a base film and an adhesive having small losses even in the 28 GHz millimeter-wave band has been increasing.

[0003] However, since the polarities of the main component molecules of a low-dielectric adhesive are low, it is difficult to exhibit adhesion (adhesive property) to a base film or other components related to electronic components, and similarly, a low-dielectric base film may also have poor adhesion (adhesive property) to the adhesive, and improvement of adhesion is required. Therefore, in order to respond to high adhesion while having good electrical characteristics (low relative permittivity and low dielectric tangent), an adhesive composition containing a carboxy group-containing styrene-based elastomer (A) and an epoxy resin (B) is used, and a laminate composed of an adhesive layer made of the adhesive composition and a base film has been proposed (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, since the low-dielectric adhesive has few reactive groups in the main component molecules, its reactivity with the curing agent is poor. Furthermore, when an epoxy resin is used as the curing agent, the dielectric tangent tends to increase. Due to these factors, it is extremely difficult to achieve both curability, which affects the adhesion, heat resistance, and chemical (solvent resistance) of the adhesive composition, and low dielectric properties.

[0006] Therefore, an object of the present invention is to provide an adhesive composition for forming a low-dielectric adhesive layer that has good electrical properties (dielectric properties) compatible with 5G, exhibits good adhesion to a low-dielectric base film with poor adhesion, and has both heat resistance and chemical (solvent resistance) properties.

Means for Solving the Problems

[0007] As a result of intensive research to solve the above problems, the present inventors have found that an adhesive composition containing a styrene-based elastomer and a specific epoxy-modified resin can solve the above problems, and have completed the present invention.

[0008] The present invention includes the following aspects. [1] An adhesive composition containing a styrene-based elastomer and an epoxy-modified resin having a structure represented by the following formula (1).

Chemical formula

Chemical formula

Chemical formula

[10] The adhesive composition according to [6], wherein both R 5 and R 6 in the formula (2) are hydrogen.

[11] The adhesive composition according to [8], wherein both R 7 and R 8 in the formula (3) are hydrogen.

[12] The adhesive composition according to [9], wherein both R 9 and R 10 in the formula (4) are hydrogen, or both R 11 and R 12 in the formula (5) are hydrogen.

[13] The adhesive composition according to any one of [1] to

[12] , wherein the epoxy-modified resin is an epoxy-modified elastomer obtained by modifying an unsaturated bond-containing elastomer with a peroxide.

[14] The adhesive composition according to any one of [1] to

[13] , wherein the epoxy-modified resin is a styrene-based elastomer.

[15] The adhesive composition according to any one of [1] to

[14] , wherein the weight average molecular weight (Mw) of the epoxy-modified resin is 30,000 or more and 200,000 or less.

[16] The adhesive composition according to any one of [1] to

[15] , wherein the adhesive composition contains a filler.

[17] The adhesive composition according to any one of [1] to

[16] , wherein the adhesive composition contains a radical polymerization initiator.

[18] The adhesive composition according to any one of [1] to

[17] , wherein the adhesive composition contains an organic peroxide.

[19] For the adhesive layer obtained by curing the adhesive composition according to any one of [1] to

[18] , the relative permittivity of the adhesive layer measured at a frequency of 28 GHz is 3 or less, and the dielectric loss tangent is 0.004 or less. Adhesive layer.

[20] A base film, [1] An adhesive layer composed of the adhesive composition according to any one of [1] to

[18] , or the adhesive layer according to

[19] , and a laminate having the same.

[21] The laminate according to

[20] , wherein the base film contains a polyether ether ketone (PEEK) resin.

[22] A coverlay film with an adhesive layer containing the laminate according to

[20] or

[21] .

[23] A copper-clad laminate containing the laminate according to

[20] or

[21] .

[24] A printed wiring board containing the laminate according to

[20] or

[21] .

[25] A shield film containing the laminate according to

[20] or

[21] .

[26] A printed wiring board with a shield containing the laminate according to

[20] or

[21] .

Advantages of the Invention

[0009] According to the present invention, there can be provided an adhesive composition for forming a low dielectric adhesive layer that has good electrical characteristics (dielectric characteristics) compatible with 5G, exhibits good adhesion even to a low dielectric base film with poor adhesion, and has heat resistance and chemical (solvent) resistance.

Embodiment for Carrying Out the Invention

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

[0011] (Adhesive Composition) The adhesive composition of the present invention contains a styrene-based elastomer and an epoxy-modified resin having a structure represented by the following formula (1).

[0012]

Chemical Formula

[0013] <Styrene-based Elastomer> Styrene-based elastomers are copolymers mainly composed of block and random structures of conjugated diene compounds and aromatic vinyl compounds, as well as their hydrogenated products. There are few highly polar bonding groups in the molecule, and good electrical properties (dielectric properties) can be imparted to the composition. Also, compared with other types of elastomers, it is an advantage that the molecular weight can be easily controlled and the properties of the adhesive composition can be stably produced. Examples of aromatic vinyl compounds include styrene, t-butylstyrene, α-methylstyrene, divinylbenzene, 1,1-diphenylethylene, N,N-diethyl-p-aminoethylstyrene, vinyltoluene, etc. Examples of conjugated diene compounds include butadiene, isoprene, 1,3-pentadiene, 2,3-dimethyl-1,3-butadiene, etc. 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, etc.

[0014] Styrene-based elastomers, whether modified or unmodified, are not particularly limited and can be selected according to the purpose. As components for imparting adhesion after curing, modified styrene-based elastomers such as styrene-based elastomers containing a carboxy group and styrene-based elastomers containing an amino group described below are preferred. As components for adjusting the adhesion by lamination and the elastic modulus at each temperature, unmodified styrene-based elastomers are preferred.

[0015] A styrenic elastomer may be used alone or in combination of two or more. In particular, by using a modified styrenic elastomer with good surface adhesion to the adherend and an unmodified styrenic elastomer whose elastic modulus can be adjusted for each temperature of the adhesive composition in combination, high adhesion and control of fluidity can be achieved. Among the above copolymers, from the viewpoints that adhesiveness and electrical properties (dielectric properties) can be imparted to the adhesive composition, the control of the molecular structure is relatively simple, and the properties of the adhesive composition can be easily adjusted, styrene-ethylene-butylene-styrene block copolymer and styrene-ethylene-propylene-styrene block copolymer are preferable. Further, 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.

[0016] <<Styrenic elastomer containing a carboxy group>> The styrenic elastomer containing a carboxy group has high adhesiveness, can impart flexibility to the cured product, and is effective as a component that gives good electrical properties. Since the adhesive composition contains a styrenic elastomer containing a carboxy group, even for an adherend such as a base film or a metal foil having good electrical properties and low polarity, the flexible adhesive composition can sufficiently follow the surface of the adherend, so that the highly polar carboxy group can exhibit adhesiveness, and the adhesiveness of the adhesive layer is improved. Further, since the styrenic elastomer containing a carboxy group is reactive, the heat resistance and chemical resistance of the adhesive layer are also improved by epoxy curing. In addition, since it contains a carboxy group, the dispersibility of the filler in the dispersion is improved. The styrene-based elastomer containing a carboxy group is a copolymer mainly having a block and random structure of a conjugated diene compound and an aromatic vinyl compound, and a hydrogenated product thereof, which is modified with an unsaturated carboxylic acid. As for the types of the aromatic vinyl compound and the conjugated diene compound and specific examples of the styrene-based elastomer, they are as described in the column of <styrene-based elastomer> above.

[0017] The modification of the styrene-based elastomer containing a carboxy group can be carried out, for example, by copolymerizing an unsaturated carboxylic acid during the polymerization of the styrene-based elastomer. Also, it can be carried out by heating and kneading the styrene-based elastomer and the unsaturated carboxylic acid in the presence of an organic peroxide. Examples of the unsaturated carboxylic acid include acrylic acid, methacrylic acid, maleic acid, itaconic acid, fumaric acid, maleic anhydride, itaconic anhydride, and the like. The amount of modification with the unsaturated carboxylic acid is preferably 0.1 to 10% by mass. The acid value of the styrene-based elastomer containing a carboxy group is preferably 0.1 to 25 mgKOH / g, and more preferably 0.5 to 23 mgKOH / g. When the acid value is 0.1 mgKOH / g or more, the curing of the adhesive composition is sufficient, and good adhesiveness and heat resistance can be obtained. On the other hand, when the acid value is 30 mgKOH / g or less, the cohesive force of the adhesive composition is suppressed, so it has excellent tackiness and also excellent electrical properties.

[0018] Also, the weight average molecular weight of the styrene-based elastomer containing a carboxy group is preferably 10,000 to 500,000, more preferably 30,000 to 300,000, and still more preferably 50,000 to 200,000. If the weight average molecular weight is above the above lower limit, excellent adhesiveness can be exhibited, and the coatability when dissolved in a solvent and coated is also improved. If the weight average molecular weight is below the above upper limit, the compatibility with the epoxy resin is improved. 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.

[0019] The content of the styrene-based elastomer containing a carboxy group is preferably 15 to 90 parts by mass with respect to 100 parts by mass of the solid content of the adhesive composition. If the content is within this range, an adhesive composition having excellent adhesive properties can be obtained.

[0020] <<Styrene-based elastomer containing an amino group>> The fact that the styrene-based elastomer containing an amino group is contained in the adhesive composition causes the amino group to exhibit a strong interaction with the low-dielectric substrate film, increases the reactivity of the adhesive composition, and improves the adhesion of the adhesive layer. In addition, since the styrene-based elastomer containing an amino group is reactive, the heat resistance and chemical resistance of the adhesive layer are also improved by epoxy curing. Since it contains an amino group, the adhesion to metal is improved. The styrene-based elastomer containing an amino group is a copolymer mainly composed of a block and random structure of a conjugated diene compound and an aromatic vinyl compound, and a hydrogenated product thereof, which is amine-modified. The types of the aromatic vinyl compound and the conjugated diene compound and specific examples of the styrene-based elastomer are as described in the column of <Styrene-based elastomer> above.

[0021] The method for amine-modifying the styrene-based elastomer is not particularly limited, and a known method can be used. For example, a method of amine-modifying by polymerizing a (hydrogenated) block copolymer using a polymerization initiator having an amino group, a method of amine-modifying a (hydrogenated) copolymer by using an unsaturated monomer having an amino group as a raw material for copolymerization, a method of reacting an amine modifier having two or more amino groups with a styrene-based elastomer containing a carboxy group, and forming an amide structure or an imide structure to perform amine modification, etc. can be mentioned.

[0022] Moreover, the weight average molecular weight of the styrene-based elastomer containing an amino group is preferably from 10,000 to 500,000, more preferably from 30,000 to 300,000, and even more preferably from 50,000 to 200,000. If the weight average molecular weight is at least the above lower limit, excellent adhesiveness can be exhibited, and the coatability when dissolved in a solvent and applied is also improved. If the weight average molecular weight is at most the above upper limit, the compatibility with the epoxy resin is improved.

[0023] The content of the styrene-based elastomer containing an amino group is preferably from 15 to 90 parts by mass with respect to 100 parts by mass of the solid content of the adhesive composition. If the content is within this range, an adhesive composition having excellent adhesive properties can be obtained.

[0024] By mixing an unmodified styrene-based elastomer and a modified styrene-based elastomer, it is possible to adjust the hardness, control the MFR, and suppress the resin flow while maintaining the adhesiveness.

[0025] From the viewpoint of ensuring the low relative dielectric constant and the adhesion (adhesiveness) of the adhesive composition, the total nitrogen content in the styrene-based elastomer containing an amino group is preferably from 50 to 5000 ppm, and more preferably from 200 to 3000 ppm. If the total nitrogen content is at least the above lower limit, excellent adhesion can be exhibited. If the total nitrogen content is at most the above upper limit, excellent electrical properties can be obtained. The total nitrogen content in the styrene-based elastomer containing an amino group can be determined in accordance with JIS-K2609 using a trace nitrogen analyzer ND-100 type (manufactured by Mitsubishi Chemical Corporation).

[0026] <Epoxy-modified resin> The epoxy-modified resin having the structure represented by the above formula (1) has a faster reaction rate with the epoxy group and the carboxyl group in the styrene-based elastomer containing a carboxyl group or the amino group in the styrene-based elastomer containing an amino group, or a self-polymerization reaction rate as compared with a normal epoxy resin, and is effective as a component for exhibiting high adhesiveness to an adherend and heat resistance of a cured product of the adhesive.

[0027] Preferable embodiments of the epoxy-modified resin include epoxy-modified resins having a structure represented by the following formula (2).

[0028]

Chemical formula

[0029] The epoxy-modified resin preferably contains an unsaturated bond other than an aromatic ring such as an olefin skeleton or a vinyl group. By incorporating an unsaturated bond other than an aromatic ring such as an olefin skeleton or a vinyl group into the reaction involving the epoxy group, the reaction rate can be accelerated and the crosslink density can be increased. As a result, heat resistance and chemical resistance can be improved even with a small blending amount. Further, as described later, an unsaturated bond other than an aromatic ring can be crosslinked by radical polymerization to increase the crosslink density of the epoxy-modified resin and improve heat resistance and chemical resistance.

[0030] Preferable embodiments of the epoxy-modified resin include epoxy-modified resins having a structure represented by the following formula (3).

[0031]

Chemical formula

[0032] The epoxy-modified resin is preferably an epoxy-modified resin having the structure represented by the above formula (1) and the structure represented by the above formula (3), and more preferably an epoxy-modified resin having the structure represented by the above formula (2) and the structure represented by the above formula (3).

[0033] Preferred embodiments of the epoxy-modified resin include an epoxy-modified resin having at least one of the structures represented by the following formula (4) and the following formula (5). It is also preferable when having both the structures represented by the following formula (4) and the following formula (5).

[0034]

Chemical formula

[0035]

Chemical formula

[0036] It is preferable that the epoxy-modified resin is an epoxy-modified resin having at least one of the structures represented by the above formula (1), the structure represented by the above formula (4), and the structure represented by the above formula (5), and more preferably an epoxy-modified resin having at least one of the structures represented by the above formula (2), the structure represented by the above formula (4), and the structure represented by the above formula (5). Also, an epoxy-modified resin having at least one of the structures represented by the above formula (1) or the above formula (2), the structure represented by the above formula (3), and further at least one of the structures represented by the above formula (4) and the structure represented by the above formula (5) is also preferable.

[0037] Further, the epoxy-modified resin is preferably an epoxy-modified organic compound obtained by modifying an organic compound containing an unsaturated bond. By modifying an organic compound containing an unsaturated bond, it is possible to coexist the structure represented by the above formula (1) and the unsaturated bond in the molecule depending on the modification rate, and it is easy to impart the effect of an unsaturated bond other than an aromatic ring such as an olefin skeleton or a vinyl group to the reaction of the epoxy structure. Here, as a method for modifying an organic compound containing an unsaturated bond into an epoxy-modified organic compound, a reaction for forming an epoxy skeleton with a peroxide is effective. Examples of the peroxide used include percarboxylic acid compounds such as performic acid, peracetic acid, and perpropionic acid. The epoxy-modified resin is preferably an epoxy-modified elastomer obtained by modifying an elastomer containing an unsaturated bond. The epoxy-modified elastomer can impart flexibility to the cured product, and by suppressing the decrease in toughness of the cured product due to epoxy curing, the adhesion when the laminate is bent can be maintained without reducing the heat resistance and chemical resistance.

[0038] Furthermore, the epoxy-modified resin is preferably a styrene-based elastomer. In the epoxy-modified resin having the structure represented by the above formula (1) or the above formula (2), in addition to the structures represented by the above formulas (3) to (5), it is also preferable to have a structural unit of styrene. When the epoxy-modified resin is also a styrene-based elastomer together with the styrene-based elastomer contained in the adhesive resin composition of the present invention, the compatibility is improved when the two are mixed, and the reaction with the carboxy group in the styrene-based elastomer containing the carboxy group and the amino group in the styrene-based elastomer containing the amino group can proceed efficiently.

[0039] Examples of the epoxy-modified resin include alicyclic epoxy compounds having an alicyclic epoxy group such as epoxycyclohexane, epoxidized polybutadiene, and epoxy compounds of styrene-butadiene block copolymers. Among them, an epoxy compound of a styrene-butadiene block copolymer is more preferable. Since the styrene-butadiene block copolymer contains an unsaturated bond, the structure represented by the above formula (1) and the unsaturated bond can coexist in the molecule, and it is easy to impart the effect of unsaturated bonds other than aromatic rings such as olefin skeletons and vinyl groups to the reaction of the epoxy structure. As the epoxy-modified resin, commercially available epoxy compounds can also be used. For example, Celoxide 2021P, Celoxide 2081, Celoxide 2000 (manufactured by Daicel Corporation), Epolead GT401, Epolead PB3600, Epolead PB4700 (manufactured by Daicel Corporation), Epofrend AT501, and Epofrend CT310 (manufactured by Daicel Corporation).

[0040] The weight average molecular weight (Mw) of the epoxy-modified resin is preferably 30,000 or more, and more preferably 50,000 or more. If the weight average molecular weight is 30,000 or more, softening of the adhesive composition can be suppressed, and resin flow during heat pressure bonding can be prevented. If the weight average molecular weight is 50,000 or more, the flexibility of the epoxy-modified resin is improved, and the toughness of the cured product is improved. Further, the weight average molecular weight (Mw) of the epoxy-modified resin is preferably 200,000 or less, and more preferably 160,000 or less. If the weight average molecular weight is 200,000 or less, the compatibility with the styrene-based elastomer is further improved. If the weight average molecular weight is 160,000 or less, the elastic modulus of the adhesive composition can be lowered, and it can follow the shape of the adherend.

[0041] The content of the above epoxy-modified resin is preferably 0.5 parts by mass or more, more preferably 1 part by mass or more, and further preferably 2 parts by mass or more with respect to 100 parts by mass of the resin composition. If the content of the above epoxy-modified resin is 0.5 parts by mass or more, epoxy curing with the modified styrene-based elastomer is possible, and the adhesiveness is improved. If the content of the epoxy-modified resin is 1 part by mass or more, the adhesive composition is sufficiently cured, and good heat resistance can be ensured. If the content of the epoxy-modified resin is 2 parts by mass or more, the adhesive composition can further proceed with the crosslinking reaction, and good chemical resistance can be ensured. Further, the content of the epoxy-modified resin is preferably 50 parts by mass or less, more preferably 25 parts by mass or less, and further preferably 15 parts by mass or less with respect to 100 parts by mass of the resin composition. If the content of the above epoxy-modified resin is 50 parts by mass or less, it is possible to achieve both low dielectric properties and heat resistance and chemical resistance. If the content of the above epoxy-modified resin is 25 parts by mass or less, the flexibility of the cured adhesive composition can be ensured, and the adhesion is improved. If the content of the above epoxy-modified resin is 15 parts by mass or less, further low dielectric properties can be achieved.

[0042] The epoxy equivalent weight of the above epoxy-modified resin is preferably 200 g / eq. or more, more preferably 350 g / eq. or more, and even more preferably 900 g / eq. or more. If the epoxy equivalent weight of the epoxy-modified resin is 200 g / eq. or more, the epoxy skeleton is not too dense in the epoxy-modified resin, the reaction with the modified elastomer proceeds, and the adhesive composition forms a matrix, thereby improving heat resistance and chemical resistance. If the epoxy equivalent weight of the epoxy-modified resin is 350 g / eq. or more, the content of the epoxy skeleton relative to the blending amount of the epoxy-modified resin decreases, and the electrical properties are improved. If the epoxy equivalent weight of the epoxy-modified resin is 900 g / eq. or more, the adhesive composition becomes flexible and the adhesion is improved. Further, the epoxy equivalent weight of the epoxy-modified resin is preferably 20,000 g / eq. or less, more preferably 16,000 g / eq. or less, and even more preferably 10,000 g / eq. or less. If the epoxy equivalent weight of the epoxy-modified resin is 20,000 g / eq. or less, the epoxy curing of the adhesive composition becomes possible and the adhesion is improved. If the epoxy equivalent weight of the epoxy-modified resin is 16,000 g / eq. or less, the crosslink density of the cured adhesive composition increases, and the heat resistance and chemical resistance are improved. If the epoxy equivalent weight of the epoxy-modified resin is 10,000 g / eq. or less, even if the blending amount of the epoxy-modified resin is small, a matrix can be formed with the modified elastomer, so that the electrical properties can be improved while maintaining the heat resistance and chemical resistance.

[0043] <Other Components> In addition to the above-mentioned styrene-based elastomer and epoxy-modified resin, the adhesive composition of the present invention can contain other resin components. As the other resin components, for example, other thermoplastic resins other than the styrene-based elastomer can be contained to such an extent that they do not affect the function of the adhesive composition.

[0044] Examples of the above-mentioned other thermoplastic resins include phenoxy resins, polyamide resins, bismaleimide resins, polyester resins, polycarbonate resins, polyphenylene oxide resins, polyurethane resins, polyacetal resins, polyethylene-based resins, polypropylene-based resins, polyvinyl-based resins, and the like. These thermoplastic resins may be used alone or in combination of two or more.

[0045] Furthermore, in addition to other resin components, the adhesive composition of the present invention may contain fillers, radical polymerization initiators, tackifiers, flame retardants, curing agents, curing accelerators, coupling agents, heat stabilizers, leveling agents, defoaming agents, inorganic fillers, pigments, solvents, etc. to such an extent that they do not affect the functions of the adhesive composition.

[0046] <<Filler>> The adhesive composition of the present invention preferably contains a filler. As the filler according to the present invention, for example, from the viewpoints of heat resistance and control of mechanical properties of the adhesive composition, inorganic fillers are preferred. As the inorganic fillers, from the viewpoint of electrical properties, silicon-based inorganic fillers and boron nitride are preferred. Further, as the silicon-based inorganic fillers, for example, mica and talc, which can control the mechanical physical properties of the adhesive composition even in a small amount and are also excellent in electrical properties, are preferred. Also, as the filler according to the present invention, for example, from the viewpoints of dispersibility and brittleness, organic fillers are preferred. As the organic fillers, from the viewpoint of electrical properties, styrene-based spherical fillers are preferred, and styrene-based hollow fillers are more preferred. These may be used alone or in combination of two or more. The content of the filler contained in the adhesive composition of the present invention is preferably 0.5 to 25 parts by volume, more preferably 1 to 15 parts by volume, based on 100 parts by volume of the resin composition. The shape of the filler is not particularly limited and can be appropriately selected according to the purpose. For example, the inorganic filler may be a spherical inorganic filler or a non-spherical inorganic filler, but from the viewpoints of the coefficient of thermal expansion (CTE) and film strength, a non-spherical inorganic filler is preferred. The shape of the non-spherical inorganic filler may be any three-dimensional shape other than spherical (substantially perfect spherical), and examples include plate-like, scaly, columnar, chain-like, fibrous, and the like. Among them, from the viewpoints of the coefficient of thermal expansion (CTE) and film strength, plate-like and scaly inorganic fillers are preferred, and plate-like inorganic fillers are more preferred.

[0047] <<Radical polymerization initiator>> The adhesive composition of the present invention preferably contains a radical polymerization initiator. Unsaturated bonds other than aromatic rings such as the aforementioned olefin skeleton and vinyl group can be crosslinked by radical polymerization, and the adhesion (adhesiveness), heat resistance, and chemical resistance of the adhesive layer can be further improved. The type of the radical polymerization initiator is not particularly limited and can be appropriately selected according to the purpose. For example, peroxides capable of crosslinking at a temperature equivalent to epoxy curing, photoinitiators capable of pre-crosslinking without promoting epoxy curing, and the like can be mentioned.

[0048] Among the radical polymerizable initiators, more preferred embodiments include, for example, organic peroxides. By containing an organic peroxide, the crosslinking density of the adhesive composition can be improved without containing highly polar functional groups, and the adhesion (adhesiveness), heat resistance, and chemical resistance of the adhesive layer can be further improved. Examples of the organic peroxide include organic peroxides such as benzoyl peroxide, lauroyl peroxide, t-butylperoxy pivalate, t-butyl peroxyethylhexanoate, 1,1'-bis-(t-butylperoxy) cyclohexane, t-amyl peroxy-2-ethylhexanoate, and t-hexyl peroxy-2-ethylhexanoate.

[0049] Examples of the above-mentioned tackifier include coumarone-indene resin, terpene resin, terpene-phenol resin, rosin resin, p-t-butylphenol-acetylene resin, phenol-formaldehyde resin, xylene-formaldehyde resin, petroleum hydrocarbon resin, hydrogenated hydrocarbon resin, and terpin resin. These tackifiers may be used alone or in combination of two or more.

[0050] The above-mentioned flame retardant may be either an organic flame retardant or an inorganic flame retardant. Examples of the organic flame retardant include phosphorus-based flame retardants such as melamine phosphate, polymelamine phosphate, guanidine phosphate, polyguanidine phosphate, ammonium phosphate, polyammonium phosphate, amide ammonium phosphate, polyamide ammonium phosphate, carbamate phosphate, polycarbamate phosphate, aluminum tris(diethylphosphate), aluminum tris(methylethylphosphate), aluminum tris(diphenylphosphate), zinc bis(diethylphosphate), zinc bis(methylethylphosphate), zinc bis(diphenylphosphate), titanyl bis(diethylphosphate), titanium tetrakis(diethylphosphate), titanyl bis(methylethylphosphate), titanium tetrakis(methylethylphosphate), titanyl bis(diphenylphosphate), and titanium tetrakis(diphenylphosphate); nitrogen-based flame retardants such as triazine compounds such as melamine, melam, and melamine cyanurate, cyanuric acid compounds, isocyanuric acid compounds, triazole compounds, tetrazole compounds, diazo compounds, and urea; and silicon-based flame retardants such as silicone compounds and silane compounds. Examples of the inorganic flame retardant 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; and zinc carbonate, magnesium carbonate, barium carbonate, zinc borate, and hydrated glass. These flame retardants can be used in combination of two or more.

[0051] Examples of the above-mentioned curing agent include, but are not limited to, amine-based curing agents and acid anhydride-based curing agents. Examples of the amine-based curing agent include melamine resins such as methylated melamine resin, butylated melamine resin, and benzoguanamine resin, dicyandiamide, 4,4'-diphenyldiaminosulfone, and the like. Examples of the acid anhydride include aromatic acid anhydrides and aliphatic acid anhydrides. These curing agents may be used alone or in combination of two or more.

[0052] The above-mentioned curing accelerator is used, for example, for the purpose of accelerating the reaction between a styrene-based elastomer, particularly a modified styrene-based elastomer, and an epoxy resin, and a tertiary amine-based curing accelerator, a tertiary amine salt-based curing accelerator, an imidazole-based curing accelerator, etc. can be used.

[0053] Examples of the tertiary amine-based curing accelerator include benzyldimethylamine, 2-(dimethylaminomethyl)phenol, 2,4,6-tris(dimethylaminomethyl)phenol, tetramethylguanidine, triethanolamine, N,N'-dimethylpiperazine, triethylenediamine, 1,8-diazabicyclo[5.4.0]undecene, and the like.

[0054] Examples of the tertiary amine salt-based curing accelerator include formate, octylate, p-toluenesulfonate, o-phthalate, phenolate or phenol novolak resin salt of 1,8-diazabicyclo[5.4.0]undecene, and formate, octylate, p-toluenesulfonate, o-phthalate, phenolate or phenol novolak resin salt of 1,5-diazabicyclo[4.3.0]nonene, and the like.

[0055] Examples of imidazole-based curing accelerators include 2-methylimidazole, 2-undecylimidazole, 2-heptadecylimidazole, 1,2-dimethylimidazole, 2-methyl-4-ethylimidazole, 2-phenylimidazole, 2-phenyl-4-methylimidazole, 1-benzyl-2-methylimidazole, 1-benzyl-2-phenylimidazole, 2,4-diamino-6-[2'-methylimidazolyl-(1')]ethyl-s-triazine, 2,4-diamino-6-[2'-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 isocyanurate adduct, 2-phenylimidazole isocyanurate adduct, 2-phenyl-4,5-dihydroxymethylimidazole, 2-phenyl-4-methyl-5-hydroxymethylimidazole, and the like. These curing accelerators may be used alone or in combination of two or more.

[0056] Examples of the coupling agent include silane coupling agents such as vinyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, p-styryltrimethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, 3-acryloxypropyltrimethoxysilane, N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, 3-ureidopropyltriethoxysilane, 3-mercaptopropylmethyldimethoxysilane, bis(triethoxysilylpropyl)tetrasulfide, 3-isocyanatopropyltriethoxysilane, imidazole silane; titanate-based coupling agents; aluminate-based coupling agents; zirconium-based coupling agents and the like. These may be used alone or in combination of two or more.

[0057] Examples of the above heat aging inhibitors include phenolic antioxidants 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-t-butyl-4-hydroxyphenol), triethylene glycol-bis[3-(3-t-butyl-5-methyl-4-hydroxyphenyl)propionate]; sulfur-based antioxidants such as dilauryl 3,3’-thiodipropionate and dimyristyl 3,3’-dithiopropionate; and phosphorus-based antioxidants such as trisnonylphenyl phosphite and tris(2,4-di-tert-butylphenyl)phosphite. These may be used alone or in combination of two or more.

[0058] Examples of the above inorganic fillers include powders composed of titanium oxide, aluminum oxide, zinc oxide, carbon black, silica, copper, silver, and the like. These may be used alone or in combination of two or more.

[0059] (Adhesive layer) The adhesive layer according to the present invention is composed of the above adhesive composition of the present invention. The adhesive composition for forming the adhesive layer can be cured. The curing method is not particularly limited and can be appropriately selected according to the purpose. For example, heat curing and the like can be mentioned. The thickness of the adhesive layer is not particularly limited and can be appropriately selected according to the purpose. For example, it is preferably 3 to 100 μm, more preferably 3 to 50 μm, and even more preferably 5 to 30 μm.

[0060] <Manufacturing method of adhesive layer> The adhesive layer can be manufactured by forming a film of the above adhesive composition. The above adhesive composition can be produced by mixing a resin composition containing a styrene-based elastomer and an epoxy-modified resin having the structure represented by the above formula (1), and further mixing other components as necessary. The mixing method is not particularly limited as long as the adhesive composition becomes uniform. Since the adhesive composition is preferably used in the form of a solution or dispersion, a solvent is usually also used. Examples of the solvent include alcohols such as methanol, ethanol, isopropyl alcohol, n-propyl alcohol, isobutyl alcohol, n-butyl alcohol, benzyl alcohol, ethylene glycol monomethyl ether, propylene glycol monomethyl ether, diethylene glycol monomethyl ether, and diacetone alcohol; ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, methyl amyl ketone, cyclohexanone, and isophorone; aromatic hydrocarbons such as toluene, xylene, ethylbenzene, and mesitylene; esters such as methyl acetate, ethyl acetate, butyl acetate, ethylene glycol monomethyl ether acetate, and 3-methoxybutyl acetate; and aliphatic hydrocarbons such as hexane, heptane, cyclohexane, and methylcyclohexane. These solvents may be used alone or in combination of two or more. When the adhesive composition is a solution or dispersion (resin varnish) containing a solvent, coating on the base film and formation of the adhesive layer can be carried out smoothly, and an adhesive layer with a desired thickness can be easily obtained. When the adhesive composition contains a solvent, from the viewpoint of workability including the formation of the adhesive layer, the solid content concentration is preferably in the range of 3 to 80% by mass, more preferably 10 to 50% by mass. When the solid content concentration is 80% by mass or less, the viscosity of the solution is appropriate and it is easy to coat uniformly. As a more specific embodiment of the method for manufacturing the adhesive layer, a resin varnish containing the above adhesive composition and a solvent is applied to the surface of a base film to form a resin varnish layer, and then the solvent is removed from the resin varnish layer, whereby a B-stage adhesive layer can be formed. Here, the adhesive layer being in the B-stage means that the adhesive composition is in an uncured state or a semi-cured state in which a part has started to cure, and it refers to a state in which the curing of the adhesive composition further proceeds by heating or the like. Here, the method for applying the resin varnish onto the base film is not particularly limited and can be appropriately selected according to the purpose. For example, spray method, spin coating method, dip method, roll coating method, blade coating method, doctor roll method, doctor blade method, curtain coating method, slit coating method, screen printing method, inkjet method, dispensing method, etc. can be mentioned. The above B-stage adhesive layer can be further heated or the like to form a cured adhesive layer.

[0061] [Properties of the Adhesive Layer] The relative permittivity (εr) of the adhesive layer formed by curing the adhesive composition of the present invention at a frequency of 28 GHz is preferably 3 or less, more preferably 2.7 or less. The dielectric loss tangent (tanδ) of the adhesive layer at a frequency of 28 GHz is preferably 0.004 or less, more preferably 0.0025 or less, and even more preferably 0.002 or less. If the relative permittivity is 3 or less and the dielectric loss tangent is 0.004 or less, it can also be used for high-frequency FPC-related products with strict electrical property requirements. Also, if the relative permittivity is 2.7 or less and the dielectric loss tangent is 0.0025 or less, the electrical properties expected of the components of 5G-compatible high-frequency FPC-related products can be satisfied, resulting in electrical properties equivalent to those of LCP, and it can also be suitably used for 5G high-frequency FPC-related products with strict electrical property requirements. Furthermore, if the dielectric loss tangent is 0.002 or less, high-frequency FPC-related products with further improved transmission characteristics can be manufactured.

[0062] [Relative Permittivity and Dielectric Loss Tangent] The relative permittivity and dielectric tangent of the adhesive layer can be measured under the conditions of a temperature of 23°C and a frequency of 28 GHz by the open resonator method using a network analyzer MS46122B (manufactured by Anritsu Corporation) and an open resonator Fabry-Perot DPS-03 (manufactured by KEYCOM Corporation).

[0063] (Laminate) The laminate of the present invention includes a base film and the adhesive layer on at least one surface of the base film.

[0064] <Base film> The base film used in the present invention can be selected according to the use of the laminate. For example, when the laminate is used as a coverlay film or a copper-clad laminate (CCL), a polyimide film, a polyether ether ketone film, a polyphenylene sulfide film, an aramid film, a polyethylene naphthalate film, a liquid crystal polymer film, etc. can be mentioned. Among these, from the viewpoints of adhesiveness and electrical properties, a polyimide film, a polyether ether ketone (PEEK) film, a polyethylene naphthalate film, and a liquid crystal polymer film are preferable.

[0065] When the laminate of the present invention is used as a bonding sheet, the base film needs to be a release film. For example, a polyethylene terephthalate film, a polyethylene film, a polypropylene film, a silicone release-treated paper, a polyolefin resin-coated paper, a TPX (polymethylpentene) film, a fluororesin film, etc. can be mentioned.

[0066] When the laminate of the present invention is used as a shielding film, the base film needs to be a film having electromagnetic wave shielding ability. For example, a laminate of a protective insulating layer and a metal foil, etc. can be mentioned.

[0067] (Coverlay film) As a preferred embodiment of the laminate according to the present invention, a coverlay film can be mentioned. When manufacturing an FPC, in order to protect the wiring portion, a laminate having an adhesive layer generally called a "coverlay film" is usually used. This coverlay film includes an insulating resin layer and an adhesive layer formed on the surface thereof. For example, in the coverlay film, the adhesive layer is formed on at least one surface of the base film, and it is a laminate in which it is generally difficult to peel the base film and the adhesive layer. The thickness of the base film included in the coverlay film is preferably 5 to 100 μm, more preferably 5 to 50 μm, and even more preferably 5 to 30 μm. If the thickness of the base film is below the above upper limit, the coverlay film can be made thinner. If the thickness of the base film is above the above lower limit, the design of the printed wiring board can be facilitated and the handling is also good. As a method for manufacturing the coverlay film, for example, after applying a resin varnish containing the above adhesive composition and solvent to the surface of the above base film to form a resin varnish layer, a coverlay film in which a B-stage adhesive layer is formed can be manufactured by removing the solvent from the resin varnish layer. The drying temperature when removing the solvent is preferably 40 to 250 °C, and more preferably 70 to 170 °C. Drying is performed by passing the laminate coated with the adhesive composition through a furnace where hot air drying, far-infrared heating, high-frequency induction heating, etc. are performed. In addition, if necessary, a release film may be laminated on the surface of the adhesive layer for storage or the like. As the release film, known ones such as polyethylene terephthalate film, polyethylene film, polypropylene film, silicone release-treated paper, polyolefin resin-coated paper, TPX film, and fluororesin film are used. Since the coverlay film according to the present invention uses the low-dielectric adhesive composition of the present invention, high-speed transmission of electronic devices is possible, and furthermore, the adhesive stability with electronic devices is also excellent.

[0068] (Bonding Sheet) As a preferred embodiment of the laminate according to the present invention, a bonding sheet can be mentioned. The bonding sheet is one in which the above adhesive layer is formed on the surface of a release film (base film). Further, the bonding sheet may be in a form having an adhesive layer between two release films. When using the bonding sheet, the release film is peeled off and used. As the release film, the same one as described in the above (coverlay film) column can be used. The thickness of the base film included in the bonding sheet is preferably 5 to 100 μm, more preferably 25 to 75 μm, and even more preferably 38 to 50 μm. If the thickness of the base film is within the above range, the production of the bonding sheet is easy and the handling is good. As a method for manufacturing the bonding sheet, for example, there is a method of applying a resin varnish containing the above adhesive composition and a solvent to the surface of a release film and drying it in the same manner as in the case of the above coverlay film. Since the bonding sheet according to the present invention uses the low-dielectric adhesive composition of the present invention, high-speed transmission of electronic devices is possible, and the bonding stability with electronic devices is also excellent.

[0069] (Copper-clad laminate (CCL)) As a preferred embodiment of the laminate according to the present invention, a copper-clad laminate obtained by laminating a copper foil on the adhesive layer in the laminate of the present invention can be mentioned. In the copper-clad laminate, a copper foil is laminated using the above laminate. For example, it is composed of a base film, an adhesive layer, and a copper foil in this order. Note that the adhesive layer and the copper foil may be formed on both sides of the base film. The adhesive composition used in the present invention also has excellent adhesiveness to articles containing copper. Since the copper-clad laminate according to the present invention uses the low-dielectric adhesive composition of the present invention, it enables high-speed transmission of electronic devices and has excellent bonding stability.

[0070] As a method for manufacturing a copper-clad laminate, for example, there is a method in which the adhesive layer of the laminate and the copper foil are brought into surface contact, heat lamination is performed at 80°C to 200°C, and the adhesive layer is further cured by post-cure. The post-cure conditions can be, for example, 100°C to 200°C for 30 minutes to 4 hours in an atmosphere of an inert gas. The copper foil is not particularly limited, and an electrolytic copper foil, a rolled copper foil, etc. can be used.

[0071] (Printed Wiring Board) As a preferred embodiment of the laminate according to the present invention, there is a printed wiring board formed by laminating copper wiring on the adhesive layer in the laminate of the present invention. The printed wiring board can be obtained by forming an electronic circuit on the above copper-clad laminate. The printed wiring board uses the above laminate, and a base film and copper wiring are laminated, and are configured in the order of the base film, the adhesive layer, and the copper wiring. Note that the adhesive layer and the copper wiring may be formed on both sides of the base film. For example, a printed wiring board is manufactured by using thermal pressing or the like to attach a coverlay film via an adhesive layer to the surface having the wiring portion. Since the printed wiring board according to the present invention uses the low-dielectric adhesive composition of the present invention, it enables high-speed transmission of electronic devices and has excellent adhesion stability. As a method for manufacturing the printed wiring board according to the present invention, for example, there is a method in which the adhesive layer of the laminate and the copper wiring are brought into contact, heat lamination is performed at 80°C to 200°C, and the adhesive layer is further cured by post-cure. The post-cure conditions can be, for example, 100°C to 200°C for 30 minutes to 4 hours. The shape of the copper wiring is not particularly limited, and an appropriate shape etc. can be selected as desired.

[0072] (Shield Film) As a preferred embodiment of the laminate according to the present invention, there is a shield film. The shielding film is a film for shielding various electronic devices such as computers, mobile phones, and analytical devices in order to cut off electromagnetic wave noise that affects the devices and causes malfunction. It is also called an electromagnetic wave shielding film. The electromagnetic wave shielding film is formed by laminating, for example, an insulating resin layer, a metal layer, and an adhesive layer according to the present invention in this order. Since the shielding film according to the present invention uses the low-dielectric adhesive composition of the present invention, high-speed transmission of electronic devices is possible, and furthermore, the adhesion stability to electronic devices is excellent.

[0073] (Printed wiring board with shielding film) As a preferred embodiment of the laminate according to the present invention, a printed wiring board with a shielding film can be mentioned. The printed wiring board with a shielding film is one in which the electromagnetic wave shielding film is attached on a printed wiring board provided with a printed circuit on at least one side of a substrate. The printed wiring board with a shielding film has, for example, a printed wiring board, an insulating film adjacent to the surface of the printed wiring board on which the printed circuit is provided, and the electromagnetic wave shielding film. Since the printed wiring board with a shielding film according to the present invention uses the low-dielectric adhesive composition of the present invention, it enables high-speed transmission of electronic devices and has excellent adhesion stability.

Examples

[0074] The present invention will be described in more detail with reference to the following examples, but the scope of the present invention is not limited to these examples. In the following, parts and % are based on mass unless otherwise specified.

[0075] (Styrene-based elastomer containing a carboxy group) The product name "Tuftec M1911" (maleic acid-modified styrene-ethylene-butylene-styrene block copolymer) manufactured by Asahi Kasei Corporation was used. 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. (Styrene-based elastomer containing carboxyl groups) The product name "Tuftec M1913" (maleic acid-modified styrene-ethylene-butylene-styrene block copolymer) manufactured by Asahi Kasei Corporation was used. 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. (Styrene-based elastomer containing carboxyl groups) The product name "Clayton FG1901" (maleic acid-modified styrene-ethylene-butylene-styrene block copolymer) manufactured by Clayton Corporation was used. The acid value of this copolymer is 19 mgKOH / g, the styrene / ethylene-butylene ratio is 30 / 70, and the weight-average molecular weight is 81,000. (Styrene-based elastomer not containing carboxyl groups) The product name "Tuftec P1500" (hydrogenated styrene-based elastomer) manufactured by Asahi Kasei Corporation was used. 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. (Unmodified styrene-based elastomer) The product name "Clayton G1651" (styrene-ethylene-butylene-styrene block copolymer) manufactured by Clayton Corporation was used. The acid value of this copolymer is 0 mgKOH / g, the styrene / ethylene-butylene ratio is 33 / 67, and the weight-average molecular weight is 136,700. (Styrene-based elastomer containing amino groups) The product name "Tuftec MP10" (amine-modified styrene-ethylene-butylene-styrene copolymer) manufactured by Asahi Kasei Corporation was used. The styrene / ethylene-butylene ratio of this copolymer was 30 / 70, and the weight-average molecular weight was 78,000. The total nitrogen content contained in this copolymer was 430 ppm (μg / g). (Epoxy-modified resin) The product name "Epofriend AT501" (epoxidized styrene-butadiene block copolymer) manufactured by Daicel Corporation was used. The styrene / ethylene-butylene ratio of this copolymer was 40 / 60, the weight-average molecular weight was 92,000, and the epoxy equivalent was 1055 g / eq. (Epoxy-modified resin) The product name "Epofriend CT310" (epoxidized styrene-butadiene block copolymer) manufactured by Daicel Corporation was used. The styrene / ethylene-butylene ratio of this copolymer was 40 / 60, the weight-average molecular weight was 93,000, and the epoxy equivalent was 2125 g / eq. (Epoxy resin) As the epoxy resin, the product name "YX7700" (softening point 65°C) manufactured by Mitsubishi Chemical Corporation, which is a novolac-type epoxy resin, was used. The epoxy equivalent was 270 g / eq. (Epoxy resin) As the epoxy resin, the product name "HP-7200" (epoxy resin, softening point 56 - 66°C) manufactured by DIC Corporation, which is a novolac-type epoxy resin, was used. The epoxy equivalent was 259 g / eq. (Perbutyl E) As the organic peroxide, the product name "Perbutyl E", which is a peroxyester manufactured by NOF Corporation, was used. (MK-100DS) The product name "MK-100DS", which is mica with an average particle diameter of 3 μm manufactured by Katakura Koppu Agri Co., Ltd., was used. (UHP-S2) The product name "UHP-S2", which is flaky boron nitride with an average particle diameter of 0.7 μm manufactured by Showa Denko K.K., was used. (OP935) The flame retardant "OP935" manufactured by Clariant Chemicals Co., Ltd. was used. (Solvent) A mixed solvent (mass ratio = 90:10) consisting of toluene and methyl ethyl ketone was used. (Base film) As the base film, "Shin-Etsu Sepla Film PEEK" (polyether ether ketone, thickness 50 μm) manufactured by Shin-Etsu Polymer Co., Ltd. was used. (Electrolytic copper foil) As the electrolytic copper foil, "TQ-M7-VSP" (electrolytic copper foil, thickness 12 μm, glossy surface Rz 1.27 μm, glossy surface Ra 0.197 μm, glossy surface Rsm 12.95 μm) manufactured by Mitsui Mining & Smelting Co., Ltd. was used. The surface roughness of the glossy surface was measured by measuring the roughness curve using a laser microscope, and the value was obtained based on JIS B 0601:2013 (ISO 4287:1997 Amd.1:2009). (Release film) As the release film, NP75SA (silicone release PET film, 75 μm) manufactured by Panac Co., Ltd. was used.

[0076] (Measurement of nitrogen content) The total nitrogen content contained in the above styrene-based elastomer containing an amino group used in the examples was determined by the following method. (Measurement method) It was determined according to JIS-K2609 using a trace nitrogen analyzer ND-100 type (manufactured by Mitsubishi Chemical Corporation).

[0077] (Example 1) Each component constituting the adhesive layer shown in Table 1 was contained in the ratio shown in Table 1, and these components were dissolved in a solvent to prepare a resin varnish having a solid content concentration of 20% by mass. The surface of the base film was subjected to corona treatment. The resin varnish was applied to the surface of the base film and dried in an oven at 110°C for 4 minutes to volatilize toluene, thereby forming an adhesive layer and obtaining a base film with an adhesive. The adhesive layer of the adhesive laminate was overlapped so as to contact the glossy surface of the electrolytic copper foil, and thermal lamination was performed at 120°C to obtain a pre-cured adhesive laminate. The pre-cured adhesive laminate was subjected to after-cure to cure the adhesive layer and obtain a post-cured adhesive laminate. The adhesive strength (N / cm) between the electrolytic copper foil and the base film of the post-cured adhesive laminate of Example 1 was measured.

[0078] [Adhesive strength (N / cm)] The adhesive strength was measured by cutting the post-cured adhesive laminate into a test piece with a width of 25 mm, and in accordance with JIS Z0237:2009 (Adhesive Tape and Adhesive Sheet Test Method), measuring the peel strength when peeling the electrolytic copper foil from the base film with an adhesive fixed to the support at a peel rate of 0.3 m / min and a peel angle of 180°.

[0079] Regarding the adhesive layer in the post-cured adhesive laminate of Example 1, the relative permittivity and dielectric loss tangent at a frequency of 28 GHz were also measured.

[0080] [Relative permittivity and dielectric loss tangent] The relative permittivity and dielectric loss tangent of the adhesive layer were measured by the open resonator method under the conditions of a temperature of 23°C and a frequency of 28 GHz using a network analyzer MS46122B (manufactured by Anritsu Corporation) and an open resonator Fabry-Perot DPS-03 (manufactured by KEYCOM Corporation). The measurement sample was prepared by roll-coating the resin varnish on a release film, and then leaving the film with the coating film in an oven and drying it at 110°C for 4 minutes to form a B-stage adhesive layer (thickness 50 μm). Next, this adhesive layer was thermally laminated at 120°C so that the adhesive surfaces were in contact with each other to form a pre-cured adhesive film (thickness 100 μm). This pre-cured adhesive film (thickness 100 μm) was left in an oven and heat-cured at 150°C for 60 minutes to produce a post-cured adhesive film (100 mm × 100 mm). The release film was peeled off from the post-cured adhesive film to measure the relative permittivity and dielectric loss tangent of the adhesive layer.

[0081] The heat resistance of the adhesive layer in the laminate of Example 1 was evaluated by a solder heat resistance test.

[0082] [Solder heat resistance test] In the solder heat resistance test, with the substrate film surface facing up, the cured adhesive laminate was floated in a solder bath at 288°C for 10 seconds × 3 times, and appearance abnormalities such as swelling and peeling of the adhesive layer were confirmed. The heat resistance of the laminate was evaluated according to the following evaluation criteria. ◎ No abnormality (no dissolution). ○ There is no final abnormality, but softening of the adhesive layer is observed during the test. △ It has not peeled off, but softening of the adhesive layer is observed and a "stain pattern" has formed. × It has peeled off.

[0083] Each measurement result is shown in Table 3.

[0084] (Examples 2 to 15) In Example 1, except that the types and blending amounts of the components constituting the adhesive layer were changed as shown in Table 1, laminates of Examples 2 to 15 were produced in the same manner as in Example 1. The produced laminates were evaluated in the same manner as in Example 1. The results are shown in Table 3.

[0085] (Comparative Examples 1 to 11) In Example 1, except that the types and blending amounts of the components constituting the adhesive layer were changed as shown in Table 2, laminates of Comparative Examples 1 to 11 were produced in the same manner as in Example 1. The produced laminates were evaluated in the same manner as in Example 1. The results are shown in Table 4.

[0086]

Table 1

[0087]

Table 2

[0088]

Table 3

[0089]

Table 4

Industrial Applicability

[0090] The laminate having the adhesive layer made of the adhesive composition of the present invention can be suitably used for the production of FPC-related products for electronic devices such as smartphones, mobile phones, optical modules, digital cameras, game machines, notebook computers, and medical devices.

Claims

Claim 1: An adhesive composition containing a styrene-based elastomer containing an amino group and an epoxy-modified resin, wherein the content of the epoxy-modified resin is 0.5 to 50 parts by mass with respect to 100 parts by mass of the adhesive composition, the epoxy-modified resin has a structure represented by the following formula (2) and a structure represented by the following formula (3), the epoxy-modified resin is any one selected from alicyclic epoxy compounds, epoxidized polybutadiene, and epoxy compounds of styrene-butadiene block copolymers, the epoxy equivalent of the epoxy-modified resin is 200 g / eq. or more and 20,000 g / eq. or less, an adhesive composition. 【Chemical 1】 (R5 and R6 each independently represent hydrogen or an alkyl group having 10 or less carbon atoms. When a plurality of structures represented by the formula (2) exist in the epoxy-modified resin, R5 in each formula (2) may be the same or different, and R6 in each formula (2) may be the same or different. * represents a bonding group.) [Chemical 2] (R7 and R8 each independently represent hydrogen or an alkyl group having 10 or less carbon atoms. When a plurality of structures represented by the formula (3) exist in the epoxy-modified resin, R7 in each formula (3) may be the same or different, and R8 in each formula (3) may be the same or different. * represents a bonding group.)

2. The adhesive composition according to claim 1, wherein the content of the epoxy-modified resin is 1 to 50 parts by mass with respect to 100 parts by mass of the adhesive composition.

3. R in the formula (2) above ５ and R ６ are both hydrogen, the adhesive composition according to claim 1.

4. The adhesive composition according to claim 1, wherein the epoxy-modified resin is an epoxy compound of a styrene-butadiene block copolymer.

5. The adhesive composition according to claim 1, wherein the epoxy-modified resin further has a structure represented by the following formula (5). [Chemical Formula 3] (R11 and R12 each independently represent hydrogen or an alkyl group having 10 or less carbon atoms. When a plurality of structures represented by the formula (5) exist in the epoxy-modified resin, R11 in each formula (5) may be the same or different, and R12 in each formula (5) may be the same or different. * represents a bonding group.)

6. The adhesive composition according to claim 1, wherein the epoxy-modified resin has a weight average molecular weight (Mw) of 30,000 or more and 200,000 or less.

7. The adhesive composition according to claim 1, wherein the adhesive composition contains a radical polymerization initiator.

8. For the adhesive layer formed by curing the adhesive composition according to any one of claims 1 to 7, the relative permittivity of the adhesive layer measured at a frequency of 28 GHz is 3 or less, and the dielectric loss tangent is 0.004 or less. Adhesive layer.

9. A base film, A laminate having an adhesive layer made of the adhesive composition according to any one of claims 1 to 7, or the adhesive layer according to claim 8.

10. The laminate according to claim 9, wherein the base film contains a polyether ether ketone (PEEK) resin.

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