CN115996999A

CN115996999A - Adhesive composition

Info

Publication number: CN115996999A
Application number: CN202180045764.0A
Authority: CN
Inventors: 片桐航; 门间刊
Original assignee: Shin Etsu Polymer Co Ltd
Current assignee: Shin Etsu Polymer Co Ltd
Priority date: 2020-07-01
Filing date: 2021-06-22
Publication date: 2023-04-21
Also published as: TW202208577A; WO2022004476A1; TWI795825B; JPWO2022004476A1

Abstract

The invention provides an adhesive composition which has good electrical characteristics (dielectric characteristics) capable of coping with 5G, and also has good adhesion to a low dielectric substrate film with poor adhesion, and forms a low dielectric adhesive layer with heat resistance and chemical resistance (solvent resistance). The adhesive composition contains a styrene elastomer and an epoxy modified resin having a structure represented by the following formula (1).

(R ¹ 、R ² 、R ³ And R is ⁴ Each independently represents hydrogen or an organic group. Wherein R is ¹ And R is ² At least one of which is an organic group, and R ³ And R is ⁴ At least one of which is an organic group).

Description

Adhesive composition

Technical Field

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

Background

With miniaturization, weight saving, and the like of electronic devices, there is a growing demand for laminated bodies with adhesive layers for various applications such as bonding of electronic components.

In addition, a flexible printed circuit board (hereinafter, also referred to as FPC), which is one of electronic components, needs to process a large amount of data at high speed, and is dealing with high frequencies. The high frequency of FPC requires low dielectric characteristics of the constituent elements, and development of low dielectric base films and low dielectric adhesives is underway. In particular, in order to efficiently transmit signals having frequencies of 3.5GHz and 28GHz bands used in the fifth generation mobile communication system (hereinafter, also referred to as 5G), importance of a base film and an adhesive having small loss in the 28GHz millimeter wave band has been growing.

However, since the low-dielectric adhesive has low polarity of the main agent molecules, it is difficult to exhibit adhesion (adhesiveness) to other constituent elements associated with the base film and the electronic component, and in addition, the adhesion (adhesiveness) to the adhesive is also poor in some cases in the low-dielectric base film, and improvement of the adhesion is demanded.

Therefore, in order to satisfy high adhesion while having good electrical characteristics (low relative permittivity and low dielectric loss tangent), an adhesive composition containing a carboxyl group-containing styrene-based elastomer (a) and an epoxy resin (B) has been proposed, and a laminate comprising an adhesive layer containing the adhesive composition and a base film has been proposed (for example, see patent document 1).

Prior art literature

Patent literature

Patent document 1: international publication No. 2016/017473

Disclosure of Invention

(problem to be solved by the invention)

However, the low dielectric adhesive has few reactive groups in the main agent molecule, and thus has poor reactivity with the curing agent. Further, if an epoxy resin is used as a curing agent, there is a tendency that the dielectric loss tangent becomes high. Due to these factors, it is extremely difficult to achieve both curability, which affects adhesion, heat resistance, chemical resistance (solvent resistance), and low dielectric properties of the adhesive composition.

Accordingly, an object of the present invention is to provide an adhesive composition having good electrical characteristics (dielectric characteristics) capable of coping with 5G and also exhibiting good adhesion to a low dielectric base film having poor adhesion, and to provide a low dielectric adhesive layer having both heat resistance and chemical resistance (solvent resistance).

(means for solving the problems)

The present inventors have conducted intensive studies to solve the above problems, and as a result, 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.

The present invention includes the following means.

[1] An adhesive composition comprising a styrene-based elastomer and an epoxy-modified resin having a structure represented by the following formula (1).

(R ¹ 、R ² 、R ³ And R is ⁴ Each independently represents hydrogen or an organic group. Wherein R is ¹ And R is ² At least one of which is an organic group, and R ³ And R is ⁴ At least one of which is an organic group. )

[2] The adhesive composition according to [1], wherein the styrene-based elastomer is a carboxyl group-containing styrene-based elastomer.

[3] The adhesive composition according to [1], wherein the styrene-based elastomer is an amino group-containing styrene-based elastomer.

[4] The adhesive composition according to any one of [1] to [3], wherein the content of the epoxy-modified resin is 1 to 50 parts by mass based on 100 parts by mass of the adhesive composition.

[5] The adhesive composition according to any one of [1] to [4], wherein the epoxy equivalent of the epoxy-modified resin is 200g/eq. Or more and 20000g/eq. Or less.

[6] The adhesive composition according to any one of [1] to [5], wherein the epoxy-modified resin has a structure represented by the following formula (2).

(R ⁵ And R is ⁶ Each independently represents hydrogen or an alkyl group having 10 or less carbon atoms, and R in each formula (2) is represented by the formula (2) when a plurality of structures represented by the formula (2) are present in the epoxy-modified resin ⁵ Each of which may be the same or different, R in each formula (2) ⁶ Each of which may be the same or different. * Represents a bonding group. )

[7] The adhesive composition according to any one of [1] to [6], wherein the epoxy-modified resin contains an unsaturated bond other than an aromatic ring.

[8] The adhesive composition according to [7], wherein the epoxy-modified resin has a structure represented by the following formula (3).

(R ⁷ And R is ⁸ Each independently represents hydrogen or an alkyl group having 10 or less carbon atoms, and R in each formula (3) is represented by the formula (3) when a plurality of structures represented by the formula (3) are present in the epoxy-modified resin ⁷ Each of which may be the same or different, R in each formula (3) ⁸ Each of which may be the same or different. * Represents a bonding group. )

[9] The adhesive composition according to any one of [1] to [8], wherein the epoxy-modified resin has at least one of a structure represented by the following formula (4) and a structure represented by the following formula (5).

(R ⁹ And R is ¹⁰ Each independently represents hydrogen or an alkyl group having 10 or less carbon atoms, and R in each formula (4) is represented by the formula (4) when a plurality of structures represented by the formula (4) are present in the epoxy-modified resin ⁹ Each of which may be the same or different, R in each formula (4) ¹⁰ Each of which may be the same or different. * Represents a bonding group. )

(R ¹¹ And R is ¹² Each independently represents hydrogen or an alkyl group having 10 or less carbon atoms. In the case where a plurality of structures represented by the above formula (5) are present in the epoxy-modified resin, R in each formula (5) ¹¹ R in each formula (5) may be the same or different ¹² Each of which may be the same or different. * Represents a bonding group. )

[10]According to [6 ]]The adhesive composition according to (2) wherein R is ⁵ And R is ⁶ Are all hydrogen.

[11]According to [8]]The adhesive composition according to the above formula (3), wherein R is ⁷ And R is ⁸ Are all hydrogen.

[12]According to [ 9]]The adhesive composition according to (4) wherein R is ⁹ And R is ¹⁰ Are each hydrogen or R in the above formula (5) ¹¹ And R is ¹² Are all 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 30000 to 200000.

[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] An adhesive layer obtained by curing the adhesive composition according to any one of [1] to [18], wherein the adhesive layer has a relative dielectric constant of 3 or less and a dielectric loss tangent of 0.004 or less, which is measured at a frequency of 28 GHz.

[20] A laminate comprising a base film and the adhesive layer comprising the adhesive composition according to any one of [1] to [18] or the adhesive layer according to [19 ].

[21] The laminate according to [20], wherein the base film contains a Polyetheretherketone (PEEK) resin.

[22] A cover film with an adhesive layer comprising the laminate of [20] or [21 ].

[23] A copper-clad laminate comprising the laminate of [20] or [21 ].

[24] A printed wiring board comprising the laminate of [20] or [21 ].

[25] A shielding film comprising the laminate of [20] or [21 ].

[26] A printed wiring board with a shielding film comprising the laminate of [20] or [21 ].

(effects of the invention)

According to the present invention, an adhesive composition having good electrical characteristics (dielectric characteristics) capable of coping with 5G and also showing good adhesion to a low dielectric base film having poor adhesion can be provided, and a low dielectric adhesive layer having both heat resistance and chemical resistance (solvent resistance) can be formed.

Detailed Description

The adhesive composition of the present invention, the laminate including the adhesive layer containing the adhesive composition, and the constituent members related to the electronic component including the laminate will be described in detail below, and the description of constituent elements described below is an example of one embodiment of the present invention and is not limited to these.

(adhesive composition)

The adhesive composition of the present invention comprises a styrene-based elastomer and an epoxy-modified resin having a structure represented by the following formula (1).

The adhesive composition of the present invention may contain other components as required.

The adhesive composition of the present invention comprising a styrene-based elastomer and an epoxy-modified resin having a structure represented by the above formula (1) exhibits good adhesion even in the case of a low dielectric adhesive composition, and is excellent in heat resistance and chemical resistance (solvent resistance).

Styrene elastomer

The styrene-based elastomer 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.

The composition can be provided with good electrical characteristics (dielectric characteristics) because of the small number of bonding groups having high intramolecular polarity. In addition, the control of the molecular weight is easy compared with other kinds of elastomers, and the adhesive composition can be produced with stable properties.

Examples of the aromatic vinyl compound include styrene, t-butylstyrene, α -methylstyrene, divinylbenzene, 1-diphenylethylene, N-diethyl-p-aminoethylstyrene, and vinyltoluene. Examples of the conjugated diene compound include butadiene, isoprene, 1, 3-pentadiene, and 2, 3-dimethyl-1, 3-butadiene.

Specific examples of the styrene-based elastomer 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.

The styrene-based elastomer may be a modified styrene-based elastomer or an unmodified styrene-based elastomer, and is not particularly limited and may be selected according to the purpose. The component for imparting adhesion after curing is preferably a modified styrene-based elastomer such as a carboxyl group-containing styrene-based elastomer or an amino group-containing styrene-based elastomer described below, and the component for adjusting adhesion by lamination and elastic modulus at each temperature is preferably an unmodified styrene-based elastomer.

The styrene-based elastomer may be used alone or in combination of two or more. In particular, by using a modified styrene-based elastomer having excellent adhesion to the surface of an adherend and an unmodified styrene-based elastomer having an adjustable elastic modulus at each temperature of the adhesive composition in combination, high adhesion and fluidity control can be achieved.

Among the above copolymers, styrene-ethylene butylene-styrene block copolymers and styrene-ethylene propylene-styrene block copolymers are preferable from the viewpoint that the adhesive composition can be provided with adhesion, electrical characteristics (dielectric characteristics), and control of molecular structure are relatively easy and the characteristics of the adhesive composition can be easily adjusted. The mass ratio of styrene/ethylene butene in the styrene-ethylene butene-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, more preferably 20/80 to 40/60. If the mass ratio is within this range, an adhesive composition having excellent adhesive properties can be produced.

Styrene elastomer containing carboxyl group

The carboxyl group-containing styrene-based elastomer has high adhesion, can impart flexibility to the cured product, and is effective as a component imparting good electrical characteristics.

By including the carboxyl group-containing styrene-based elastomer in the adhesive composition, even in the case of an adherend such as a base film or a metal foil having good electrical characteristics and low polarity, the adhesive composition can sufficiently follow the surface of the adherend, and the carboxyl group having high polarity can exhibit adhesion, so that the adhesion of the adhesive layer is improved. Further, since the carboxyl group-containing styrene-based elastomer is reactive, the heat resistance and chemical resistance of the adhesive layer are also improved by epoxy curing.

In addition, by containing carboxyl groups, the dispersibility of the filler in the dispersion is improved.

The carboxyl group-containing styrene-based elastomer means: copolymers mainly composed of a block structure and a random structure of a conjugated diene compound and an aromatic vinyl compound, and hydrogenated products thereof modified with an unsaturated carboxylic acid.

Specific examples of the types of the aromatic vinyl compound and the conjugated diene compound and the styrene-based elastomer are as described in the column < styrene-based elastomer >.

The modification of the carboxyl group-containing styrene-based elastomer can be performed by copolymerizing an unsaturated carboxylic acid, for example, in the polymerization of the styrene-based elastomer. The heating and kneading of the styrene-based elastomer and the unsaturated carboxylic acid in the presence of the organic peroxide may be performed.

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 unsaturated carboxylic acid to be modified is preferably 0.1 to 10% by mass.

The acid value of the carboxyl group-containing styrene-based elastomer is preferably 0.1 to 25mgKOH/g, more preferably 0.5 to 23mgKOH/g. When the acid value is 0.1mgKOH/g or more, the adhesive composition is sufficiently cured, and good adhesion and heat resistance can be obtained. On the other hand, when the acid value is 30mgKOH/g or less, the cohesive force of the adhesive composition is suppressed, and therefore the adhesive property is excellent and the electric characteristics are also excellent.

The weight average molecular weight of the carboxyl group-containing styrene-based elastomer is preferably 1 to 50 ten thousand, more preferably 3 to 30 ten thousand, and even more preferably 5 to 20 ten thousand. When the weight average molecular weight is not less than the lower limit, excellent adhesion can be exhibited, and the coating property when the coating is performed by dissolving the polymer in a solvent can be also improved. If the weight average molecular weight is not more than the upper limit, compatibility with the epoxy resin becomes good.

The weight average molecular weight is a value obtained by converting the molecular weight obtained by gel permeation chromatography (hereinafter also referred to as "GPC") into polystyrene.

The content of the carboxyl group-containing styrene-based elastomer is preferably 15 to 90 parts by mass based on 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 produced.

Styrene elastomer containing amino group

By including the styrene-based elastomer containing an amino group in the adhesive composition, the amino group and the low dielectric constant substrate film exhibit strong interaction, so that the adhesive composition becomes highly reactive, and the adhesion of the adhesive layer is improved. Further, since the amino group-containing styrene-based elastomer is reactive, the heat resistance and chemical resistance of the adhesive layer are also improved by epoxy curing.

Since the amino group is contained, adhesion to a metal is improved.

The amino group-containing styrene-based elastomer is a copolymer mainly composed of a block and random structure of a conjugated diene compound and an aromatic vinyl compound, and is obtained by amine-modifying the hydrogenated product.

The method for amine-modifying the styrene-based elastomer is not particularly limited, and known methods can be used, and examples thereof include: a method of performing amine modification 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 copolymerization raw material; an amine modification method in which an amine modifier having 2 or more amino groups is reacted with a styrene elastomer containing a carboxyl group to form an amide structure or an imide structure, thereby performing amine modification.

The weight average molecular weight of the amino group-containing styrene-based elastomer is preferably 1 to 50 ten thousand, more preferably 3 to 30 ten thousand, and even more preferably 5 to 20 ten thousand. When the weight average molecular weight is not less than the lower limit, excellent adhesion can be exhibited, and the coating property when the coating is performed by dissolving the polymer in a solvent can be also improved. If the weight average molecular weight is not more than the upper limit, compatibility with the epoxy resin becomes good.

The content of the amino group-containing styrene-based elastomer is preferably 15 to 90 parts by mass based on 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 produced.

By mixing the unmodified styrene-based elastomer and the modified styrene-based elastomer, it is possible to control the hardness, the MFR, and the resin flow while maintaining the adhesiveness.

From the viewpoint of ensuring low relative permittivity and adhesion (adhesiveness) of the adhesive composition, the total nitrogen content in the amino group-containing styrene-based elastomer is preferably 50 to 5000ppm, more preferably 200 to 3000ppm. If the total nitrogen content is not less than the lower limit, excellent adhesion can be exhibited. If the total nitrogen content is not more than the upper limit, the electrical characteristics are excellent.

The total nitrogen content in the amino group-containing styrene-based elastomer can be determined by using a micro nitrogen analyzer ND-100 (manufactured by Mitsubishi chemical Co., ltd.) according to JIS-K2609.

< epoxy modified resin >

The epoxy modified resin having the structure represented by the above formula (1) is effective as a component that exhibits high adhesion to an adherend and heat resistance of an adhesive cured product, compared with a usual epoxy resin, because the epoxy structure reacts with carboxyl groups in the above carboxyl group-containing styrene-based elastomer, amino groups in the above amino group-containing styrene-based elastomer, or reacts rapidly by self-polymerization.

A preferable embodiment of the epoxy modified resin is an epoxy modified resin having a structure represented by the following formula (2).

(R ⁵ And R is ⁶ Each independently represents hydrogen or an alkyl group having 10 or less carbon atoms. In the case where a plurality of structures represented by the above formula (2) are present in the epoxy-modified resin, R in each formula (2) ⁵ Each of which may be the same or different, R in each formula (2) ⁶ Each of which may be the same or different. * Represents a bonding group. )

In the above formula (2), R is from the viewpoint of reducing steric hindrance around the epoxy group and allowing the reaction to proceed sufficiently ⁵ And R is ⁶ More preferably hydrogen.

The epoxy-modified resin is preferably an epoxy-modified resin containing an unsaturated bond other than an aromatic ring such as an olefin skeleton or a vinyl group. By introducing an unsaturated bond other than an aromatic ring such as an olefin skeleton or a vinyl group into a reaction related to an epoxy group, the reaction rate can be accelerated and the crosslinking density can be improved. As a result, heat resistance and chemical resistance can be improved even with a small amount of the additive. As will be described later, the unsaturated bonds other than the aromatic ring are crosslinked by radical polymerization, and thus the crosslinking density of the epoxy modified resin can be increased, and heat resistance and chemical resistance can be improved.

A preferable embodiment of the epoxy modified resin is an epoxy modified resin having a structure represented by the following formula (3).

(R ⁷ And R is ⁸ Each independently represents hydrogen or an alkyl group having 10 or less carbon atoms. In the case where a plurality of structures represented by the above formula (3) are present in the epoxy-modified resin, R in each formula (3) ⁷ Each of which may be the same or different, R in each formula (3) ⁸ Each of which may be the same or different. * Represents a bonding group. )

In the above formula (3), R ⁷ And R is ⁸ More preferably hydrogen.

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

A preferable embodiment of the epoxy-modified resin is an epoxy-modified resin having at least one of the structure represented by the following formula (4) and the structure represented by the following formula (5). It is also preferable to have both the structure represented by the following formula (4) and the structure represented by the following formula (5).

/>

(R ⁹ And R is ¹⁰ Each independently represents hydrogen or an alkyl group having 10 or less carbon atoms. In the case where a plurality of structures represented by the above formula (4) are present in the epoxy-modified resin, R in each formula (4) ⁹ Each of which may be the same or different, R in each formula (4) ¹⁰ Each of which may be the same or different. * Represents a bonding group. )

In the above formula (4), R ⁹ And R is ¹⁰ More preferably hydrogen.

In the above formula (5), R ¹¹ And R is ¹² More preferably hydrogen.

The epoxy-modified resin is preferably an epoxy-modified resin having at least one of the structure 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 structure represented by the above formula (2), the structure represented by the above formula (4) and the structure represented by the above formula (5).

The epoxy modified resin is also preferably one having at least one of the structures represented by the above formula (1), the above formula (2), the above formula (3), the above formula (4) and the above formula (5).

The epoxy-modified resin is preferably an epoxy-modified organic compound obtained by modifying an organic compound having an unsaturated bond. By modifying an organic compound having an unsaturated bond, the structure represented by the above formula (1) and the unsaturated bond coexist in the molecule by the modification ratio, and thus, the effect of unsaturated bonds other than aromatic rings such as an olefin skeleton and vinyl groups can be easily imparted to the reaction of the epoxy structure.

Here, a method of modifying an organic compound having an unsaturated bond into an epoxy-modified organic compound is effective in a reaction of forming an epoxy skeleton by a peroxide. Examples of the peroxide to be 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 can maintain adhesion when the laminate is bent, without deteriorating heat resistance and chemical resistance, by suppressing a decrease in toughness of the cured product caused by epoxy curing.

The epoxy-modified resin is preferably a styrene elastomer.

In the epoxy modified resin having the structure represented by the above formula (1) or the above formula (2), it is preferable that the epoxy modified resin has a structural unit of styrene in addition to the structures represented by the above formulas (3) to (5).

This is because 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, and thus, when the both are mixed, the compatibility can be improved, and the reaction with the carboxyl group in the carboxyl group-containing styrene-based elastomer and the amino group in the amino group-containing styrene-based elastomer can be efficiently performed.

Examples of the epoxy-modified resin include alicyclic epoxy compounds having an alicyclic epoxy group such as epoxycyclohexane, epoxypolybutadiene, 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 coexist in the molecule, and thus an effect of giving an unsaturated bond other than an aromatic ring such as an olefin skeleton or a vinyl group to the reaction of the epoxy structure is easily imparted.

As the epoxy-modified resin, commercially available epoxy compounds can be used, and examples thereof include Celloxide 2021P, celloxide 2081, celloxide 2000 (manufactured by Daicel corporation), epole GT401, epole PB3600, epole PB4700 (manufactured by Daicel corporation), epofmil AT501, epofmil CT310 (manufactured by Daicel corporation).

The weight average molecular weight (Mw) of the epoxy modified resin is preferably 30000 or more, more preferably 50000 or more. When the weight average molecular weight is 30000 or more, softening of the adhesive composition can be suppressed, and resin flow during thermocompression bonding can be prevented. When the weight average molecular weight is 50000 or more, the flexibility of the epoxy modified resin is improved, and the toughness of the cured product is improved. The weight average molecular weight (Mw) of the epoxy modified resin is preferably 200000 or less, more preferably 160000 or less. If the weight average molecular weight is 200000 or less, the compatibility with the styrene-based elastomer is further improved. If the weight average molecular weight is 160000 or less, the elastic modulus of the adhesive composition can be reduced, and the adhesive composition can follow the shape of an adherend.

The content of the epoxy-modified resin is preferably 0.5 parts by mass or more, more preferably 1 part by mass or more, and still more preferably 2 parts by mass or more, based on 100 parts by mass of the resin composition. When the content of the epoxy-modified resin is 0.5 parts by mass or more, the epoxy-modified resin can be cured with the modified styrene-based elastomer, and the adhesiveness can be 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 undergo a crosslinking reaction, and good chemical resistance can be ensured. The content of the epoxy-modified resin is preferably 50 parts by mass or less, more preferably 25 parts by mass or less, and even more preferably 15 parts by mass or less, based on 100 parts by mass of the resin composition. When the content of the epoxy-modified resin is 50 parts by mass or less, both low dielectric strength and heat resistance and chemical resistance can be achieved. When the content of the epoxy-modified resin is 25 parts by mass or less, the flexibility of the cured adhesive composition can be ensured and the adhesion can be improved. If the content of the epoxy-modified resin is 15 parts by mass or less, the dielectric properties can be further reduced.

The epoxy equivalent of the epoxy-modified resin is preferably 200g/eq. Or more, more preferably 350g/eq. Or more, and still more preferably 900g/eq. Or more. If the epoxy equivalent of the epoxy-modified resin is 200g/eq. Or more, the epoxy skeleton in the epoxy-modified resin is not excessively dense, the reaction with the modified elastomer proceeds, and the adhesive composition forms a Matrix (Matrix), whereby the heat resistance and chemical resistance are improved. If the epoxy equivalent of the epoxy modified resin is 350g/eq. Or more, the content of the epoxy skeleton is reduced relative to the blending amount of the epoxy modified resin, and the electrical characteristics are improved. When the epoxy equivalent of the epoxy-modified resin is 900g/eq or more, the adhesive composition becomes soft and the adhesion is improved. The epoxy equivalent of the epoxy-modified resin is preferably 20000g/eq. Or less, more preferably 16000g/eq. Or less, and still more preferably 10000g/eq. Or less. When the epoxy equivalent of the epoxy-modified resin is 20000g/eq or less, the adhesive composition can be cured by epoxy, and the adhesion is improved. When the epoxy equivalent of the epoxy-modified resin is 16000g/eq or less, the crosslinking density of the cured adhesive composition increases, and the heat resistance and chemical resistance are improved. If the epoxy equivalent of the epoxy-modified resin is 10000g/eq. Or less, the epoxy-modified resin can form a Matrix (Matrix) with the modified elastomer even if the blending amount of the epoxy-modified resin is small, and therefore heat resistance and chemical resistance can be maintained and electrical characteristics can be improved.

Other ingredients

The adhesive composition of the present invention may contain other resin components in addition to the styrene-based elastomer and the epoxy-modified resin. As the other resin component, for example, other thermoplastic resins other than the styrene-based elastomer may be contained to such an extent that the functions of the adhesive composition are not affected.

Examples of the other thermoplastic resin include phenoxy resin, polyamide resin, bismaleimide resin, polyester resin, polycarbonate resin, polyphenylene ether resin, polyurethane resin, polyacetal resin, polyethylene resin, polypropylene resin, and polyethylene resin. These thermoplastic resins may be used alone or in combination of 2 or more.

The adhesive composition of the present invention may contain, in addition to other resin components, a filler, a radical polymerization initiator, a tackifier, a flame retardant, a curing agent, a curing accelerator, a coupling agent, a heat aging resistant agent, a leveling agent, a defoaming agent, an inorganic filler, a pigment, a solvent, and the like to such an extent that the functions of the adhesive composition are not impaired.

Filler >)

The adhesive composition of the present invention preferably contains a filler.

The filler according to the present invention is preferably an inorganic filler from the viewpoint of controlling heat resistance and mechanical properties of the adhesive composition, and the inorganic filler is preferably a silicon-based inorganic filler or boron nitride from the viewpoint of electrical properties. Further, as the silicon-based inorganic filler, for example, mica and talc which are capable of controlling the mechanical properties of the adhesive composition even in a small amount and are excellent in electric characteristics are preferable.

In addition, the filler according to the present invention is preferably an organic filler from the viewpoints of dispersibility and brittleness, and the organic filler is preferably a styrene-based spherical filler from the viewpoint of electrical characteristics, and more preferably a styrene-based hollow filler.

These may be used alone or in combination of 1 or more than 2.

The content of the filler contained in the adhesive composition of the present invention is preferably 0.5 to 25 parts by volume relative to 100 parts by volume of the resin composition, and more preferably 1 to 15 parts by volume relative to 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, and from the viewpoints of the Coefficient of Thermal Expansion (CTE) and film strength, the non-spherical inorganic filler is preferable. The shape of the non-spherical inorganic filler may be any three-dimensional shape other than spherical (substantially spherical), and examples thereof include plate-like, scale-like, columnar, chain-like, fibrous, and the like. Among them, from the viewpoints of Coefficient of Thermal Expansion (CTE) and film strength, plate-like or scale-like inorganic fillers are preferable, and plate-like inorganic fillers are more preferable.

Radical polymerization initiator

The adhesive composition of the present invention preferably contains a radical polymerization initiator.

The unsaturated bond other than the aromatic ring such as the olefin skeleton or vinyl group can crosslink the resin component even in radical polymerization, and can further improve the adhesion (adhesiveness), heat resistance, and chemical resistance of the adhesive layer.

The type of the radical polymerization initiator is not particularly limited and may be appropriately selected according to the purpose, and examples thereof include peroxides capable of crosslinking at the same temperature as the epoxy curing, photopolymerization initiators capable of crosslinking in advance without curing the epoxy, and the like.

In the radical polymerizable initiator, an organic peroxide is used as a more preferable embodiment. By containing the organic peroxide, the crosslinking density of the adhesive composition can be increased without containing a functional group having a high polarity, and the adhesiveness (adhesiveness), heat resistance, and chemical resistance of the adhesive layer can be further improved.

Examples of the organic peroxide include benzoyl peroxide, lauroyl peroxide, t-butyl peroxypivalate, t-butyl peroxyethylhexanoate, 1' -bis- (t-butylperoxy) cyclohexane, t-amyl peroxy-2-ethylhexanoate, and t-hexyl peroxy-2-ethylhexanoate.

Examples of the tackifier include coumarone-indene resins, terpene-phenol resins, rosin resins, p-tert-butylphenol-acetylene resins, phenol-formaldehyde resins, xylene-formaldehyde resins, petroleum hydrocarbon resins, hydrogenated hydrocarbon resins, and turpentine resins. These tackifiers may be used alone or in combination of 2 or more.

The flame retardant may be any of an organic flame retardant and an inorganic flame retardant. Examples of the organic flame retardant include phosphorus flame retardants such as melamine phosphate, melamine polyphosphate, guanidine phosphate, guanidine polyphosphate, ammonium phosphate, ammonium polyphosphate, ammonium amide phosphate, ammonium polyphosphate, urethane phosphate, urethane polyphosphate, aluminum tris (diethyl) phosphinate, aluminum trimethylethyl phosphinate, aluminum tris (diphenyl) phosphinate, zinc bis (diethyl) phosphinate, zinc bis (methylethyl) phosphinate, zinc bis (diphenyl) phosphinate, titanyl bis (diethyl) phosphinate, titanium tetrakis (diethyl) phosphinate, titanium bis (methylethyl) phosphinate, titanium tetrakis (methylethyl) phosphinate, titanium bis (diphenyl) phosphinate; triazine compounds such as melamine, melem, and melamine cyanurate; nitrogen-based flame retardants such as cyanuric acid compounds, isocyanuric acid compounds, triazole-based compounds, tetrazole compounds, diazo compounds, and urea; and silicon-based flame retardants such as organosilicon 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; zinc carbonate, magnesium carbonate, barium carbonate, zinc borate, hydrated glass, and the like. These flame retardants may be used in combination of 2 or more.

Examples of the curing agent include an amine-based curing agent and an acid anhydride-based curing agent, but are not limited thereto. Examples of the amine-based curing agent include melamine resins such as methylated melamine resins, butylated melamine resins and benzoguanamine resins, dicyandiamide, 4' -diphenyldiamino sulfone and the like. The acid anhydride includes an aromatic acid anhydride and an aliphatic acid anhydride. These curing agents may be used alone or in combination of 2 or more.

The curing accelerator is used, for example, for the purpose of accelerating the reaction of a styrene-based elastomer, particularly a modified styrene-based elastomer, with an epoxy resin, and a tertiary amine-based curing accelerator, a tertiary amine salt-based curing accelerator, an imidazole-based curing accelerator, and the like can be used.

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

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

Examples of the imidazole-based curing accelerator include 2-methylimidazole, 2-undecylimidazole, 2-heptadecylimidazole, 1, 2-dimethylimidazole, 2-methyl-4-ethylimidazole, 2-phenylimidazole, 2-phenyl-4-methylimidazole, 1-benzyl-2-phenylimidazole, 2, 4-diamino-6- [2' -methylimidazole- (1 ') ] ethyl-s-triazine, 2, 4-diamino-6- [2' -undecylimidazole- (1 ') ] ethyl-s-triazine, 2, 4-diamino-6- [2' -ethyl-4 ' -methylimidazole- (1 ') ] ethyl-s-triazine, 2, 4-diamino-6- [2' -methylimidazole- (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 2 or more.

Further, examples of the coupling agent include silane coupling agents such as vinyltrimethoxysilane, 3-glycidoxypropyl trimethoxysilane, p-styryl trimethoxysilane, 3-methacryloxypropyl methyl dimethoxy silane, 3-acryloxypropyl trimethoxysilane, N-2- (aminoethyl) -3-aminopropyl methyl dimethoxy silane, 3-ureidopropyl triethoxy silane, 3-mercaptopropyl methyl dimethoxy silane, bis (triethoxysilylpropyl) tetrasulfide, 3-isocyanatopropyl triethoxy silane, and imidazole silane; a titanate-based coupling agent; an aluminate coupling agent; zirconium-based coupling agents, and the like. These may be used alone or in combination of 2 or more.

Examples of the heat aging resistant agent include phenol antioxidants such as 2, 6-di-t-butyl-4-methylphenol, n-octadecyl-3- (3 ',5' -di-t-butyl-4 ' -hydroxyphenyl) propionate, tetrakis [ methylene-3- (3, 5-di-t-butyl-4-hydroxyphenyl) propionate ] methane, pentaerythritol tetrakis [3- (3, 5-di-t-butyl-4-hydroxyphenyl), triethylene glycol-bis [3- (3-t-butyl-5-methyl-4-hydroxyphenyl) propionate ], sulfur antioxidants such as dilauryl-3, 3' -thiodipropionate and dimyristoyl-3, 3' -dithiopropionate, and phosphorus antioxidants such as trisnonylphenylphosphite and tris (2, 4-di-t-butylphenyl) phosphite.

Examples of the inorganic filler include powders containing titanium oxide, aluminum oxide, zinc oxide, carbon black, silica, copper, silver, and the like. These may be used alone or in combination of 2 or more.

(adhesive layer)

The adhesive layer according to the present invention contains the adhesive composition according to the present invention.

The adhesive composition forming the adhesive layer is capable of curing.

The curing method is not particularly limited and may be appropriately selected according to the purpose, and examples thereof include heat curing.

The thickness of the adhesive layer is not particularly limited and can be appropriately selected depending on the purpose, and is, for example, preferably 3 to 100. Mu.m, more preferably 3 to 50. Mu.m, and still more preferably 5 to 30. Mu.m.

Method for producing adhesive layer

The adhesive layer can be produced by forming the adhesive composition into a film.

The adhesive composition can be produced by mixing a resin composition comprising a styrene-based elastomer and an epoxy-modified resin having a structure represented by the formula (1), 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 dispersion, and therefore, a solvent is also generally used.

Examples of the solvent include 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; ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, methyl amyl ketone, cyclohexanone, isophorone, and the like; 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; aliphatic hydrocarbons such as hexane, heptane, cyclohexane and methylcyclohexane. These solvents may be used alone or in combination of 2 or more.

If the adhesive composition is a solvent-containing solution or dispersion (resin varnish), the application to the base film and the formation of the adhesive layer can be smoothly performed, and an adhesive layer having a desired thickness can be easily obtained.

When the adhesive composition contains a solvent, the solid content concentration is preferably in the range of 3 to 80 mass%, more preferably 10 to 50 mass%, from the viewpoint of workability in forming the adhesive layer. If the solid content concentration is 80 mass% or less, the viscosity of the solution is moderate, and uniform coating is easy.

As a more specific embodiment of the method for producing an adhesive layer, a resin varnish layer is formed by applying a resin varnish containing the adhesive composition and a solvent to the surface of a base film, and then the solvent is removed from the resin varnish layer, whereby a B-stage adhesive layer can be formed. The "B-stage" state of the adhesive layer means a state in which the adhesive composition is uncured or partially cured, and the curing of the adhesive composition is further performed by heating or the like.

The method of applying the resin varnish to the base film is not particularly limited, and may be appropriately selected according to the purpose, and examples thereof include a spray coating method, a spin coating method, a dipping method, a roll coating method, a doctor blade method, a blade coating method, a curtain coating method, a slit coating method, a screen printing method, an ink jet method, and a dispensing method.

The adhesive layer in the B-stage state may be further heated to form a cured adhesive layer.

< Properties of adhesive layer >

The adhesive layer obtained by curing the adhesive composition of the present invention preferably has a relative dielectric constant (εr) of 3 or less, more preferably 2.7 or less at a frequency of 28 GHz. The dielectric loss tangent (tan delta) of the adhesive layer at a frequency of 28GHz is preferably 0.004 or less, more preferably 0.0025 or less, and still more preferably 0.002 or less.

If the relative dielectric constant is 3 or less and the dielectric loss tangent is 0.004 or less, the flexible printed circuit board can be used for high-frequency FPC-related products having strict requirements on electrical characteristics. Further, if the relative dielectric constant is 2.7 or less and the dielectric loss tangent is 0.0025 or less, the electric characteristics expected for the constituent elements of the 5G high-frequency FPC-related product can be satisfied, and the electric characteristics equivalent to LCP can be obtained, and the 5G high-frequency FPC-related product having strict requirements for electric characteristics can be suitably used. Further, if the dielectric loss tangent is 0.002 or less, a high-frequency FPC-related product with further improved transmission characteristics can be manufactured.

[ relative permittivity and dielectric loss tangent ]

The relative dielectric constant and dielectric loss tangent of the adhesive layer can be measured 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) at a temperature of 23℃and a frequency of 28 GHz.

(laminate)

The laminate of the present invention comprises a base film and the adhesive layer on at least one surface of the base film.

Substrate 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 cover film or a Copper Clad Laminate (CCL), a polyimide film, a polyether ether ketone film, a polyphenylene sulfide film, an aromatic polyamide film, a polyethylene naphthalate film, a liquid crystal polymer film, or the like can be given. Among them, polyimide films, polyetheretherketone (PEEK) films, polyethylene naphthalate films, and liquid crystal polymer films are preferable from the viewpoints of adhesiveness and electric characteristics.

In addition, when the laminate of the present invention is used as a bonding sheet, the base film needs to be a release film, and examples thereof include polyethylene terephthalate film, polyethylene film, polypropylene film, silicone release paper, polyolefin resin coated paper, TPX (polymethylpentene) film, and fluorine-based resin film.

When the laminate of the present invention is used as a shielding film, the base film is required to be a film having electromagnetic wave shielding ability, and examples thereof include a laminate of a protective insulating layer and a metal foil.

(cover film)

A preferable embodiment of the laminate of the present invention is a cover film.

In the case of manufacturing FPC, in order to protect the wiring portion, a laminate having an adhesive layer called "cover film" is generally used. The cover film includes an insulating resin layer and an adhesive layer formed on the surface thereof.

For example, the cover film has the adhesive layer formed on at least one surface of the base film, and is a laminate in which it is generally difficult to peel off the base film and the adhesive layer.

The thickness of the base film contained in the cover film is preferably 5 to 100. Mu.m, more preferably 5 to 50. Mu.m, still more preferably 5 to 30. Mu.m. If the thickness of the base material film is not more than the upper limit, the cover film can be thinned. If the thickness of the base film is not less than the lower limit, the design of the printed wiring board becomes easy and handling is also facilitated.

As a method for producing a cover film, for example, a resin varnish layer is formed by applying a resin varnish containing the adhesive composition and a solvent to the surface of the base film, and then the solvent is removed from the resin varnish layer, whereby a cover film having an adhesive layer in a B-stage state formed can be produced.

The drying temperature at the time of removing the solvent is preferably 40 to 250 ℃, more preferably 70 to 170 ℃.

The drying is performed by passing the laminate coated with the adhesive composition through a furnace in which hot air drying, far infrared ray heating, high frequency induction heating, and the like are performed.

If necessary, a release film may be laminated on the surface of the adhesive layer for storage or the like. As the release film, a known film such as a polyethylene terephthalate film, a polyethylene film, a polypropylene film, a silicone release paper, a polyolefin resin coated paper, a TPX film, a fluorine-based resin film, or the like can be used.

The cover film of the present invention uses the adhesive composition of the present invention having a low dielectric constant, and therefore enables high-speed transfer of electronic devices and is excellent in adhesion stability to electronic devices.

(adhesive sheet)

In a preferred embodiment of the laminate of the present invention, an adhesive sheet is used.

The adhesive sheet has the adhesive layer formed on the surface of a release film (base film). The adhesive sheet may be in the form of an adhesive layer between two release films. When the adhesive sheet is used, the release film is peeled off and used. The releasable film may be the same as the film described in the column above (cover film).

The thickness of the base film contained in the adhesive sheet is preferably 5 to 100. Mu.m, more preferably 25 to 75. Mu.m, and still more preferably 38 to 50. Mu.m. If the thickness of the base film is within the above range, the adhesive sheet can be easily manufactured and can be handled.

As a method of manufacturing the adhesive sheet, for example, there are: a method of applying a resin varnish containing the adhesive composition and a solvent to the surface of the release film and drying the same as in the case of the cover film.

The adhesive sheet according to the present invention uses the adhesive composition of the present invention having low dielectric properties, and therefore, can be transported at high speed in electronic devices, and is excellent in adhesion stability to electronic devices.

(copper clad laminate (CCL))

A preferable embodiment of the laminate according to the present invention is a copper-clad laminate obtained by laminating copper foil on the adhesive layer of the laminate according to the present invention.

The copper-clad laminate is formed by bonding copper foil to the laminate, for example, in this order of the base film, the adhesive layer, and the copper foil. The adhesive layer and the copper foil may be formed on both surfaces of the base film.

The adhesive composition used in the present invention is excellent in adhesion to copper-containing articles.

The copper-clad laminate according to the present invention uses the adhesive composition of the present invention having low dielectric properties, and therefore enables high-speed transportation of electronic devices, and is excellent in adhesion stability.

As a method of manufacturing the copper-clad laminate, for example, the following methods are included: the adhesive layer of the laminate is brought into contact with the copper foil surface, heat laminated at 80 to 200 ℃, and then the adhesive layer is cured by post-curing. The post-curing conditions can be set to, for example, 100 to 200℃for 30 minutes to 4 hours under an inert gas atmosphere. The copper foil is not particularly limited, and electrolytic copper foil, rolled copper foil, or the like can be used.

(printed wiring board)

A preferred embodiment of the laminate according to the present invention is a printed wiring board in which copper wiring is bonded to the adhesive layer of the laminate according to the present invention.

The printed wiring board is obtained by forming an electronic circuit on the copper-clad laminate.

The printed wiring board is constituted by bonding the base film and the copper wiring using the laminate, and by sequentially forming the base film, the adhesive layer, and the copper wiring. The adhesive layer and the copper wiring may be formed on both surfaces of the base film.

For example, a cover film is attached to a surface having a wiring portion via an adhesive layer by hot pressing or the like, thereby manufacturing a printed wiring board.

The printed wiring board according to the present invention uses the adhesive composition of the present invention having low dielectric properties, and therefore can be transported at high speed in electronic devices, and is excellent in adhesion stability.

As a method of manufacturing the printed wiring board according to the present invention, for example, the following methods are included: the adhesive layer of the laminate is brought into contact with the copper wiring, heat laminated at 80 to 200 ℃, and then post-cured to cure the adhesive layer. The post-curing conditions can be set to, for example, 100 to 200℃for 30 minutes to 4 hours. The shape of the copper wiring is not particularly limited, and an appropriate shape may be selected as desired.

(shielding film)

A preferred embodiment of the laminate according to the present invention includes a shielding film.

The shielding film is a film for shielding various electronic devices, such as a computer, a mobile phone, and an analysis device, from electromagnetic wave noise that may cause malfunction. Also known as electromagnetic wave shielding films.

The electromagnetic wave shielding film is formed by laminating an insulating resin layer, a metal layer, and an adhesive layer according to the present invention in this order, for example.

The shielding film according to the present invention uses the adhesive composition of the present invention having low dielectric properties, and therefore, can be transported at high speed in an electronic device, and is excellent in adhesion stability to the electronic device.

(printed wiring board with shielding film)

A preferred embodiment of the laminate according to the present invention is a printed wiring board with a shielding film.

The printed wiring board with shielding film is formed by sticking the electromagnetic wave shielding film on the printed wiring board with printed wiring on at least one side of the substrate.

The printed wiring board with a shielding film includes, for example, a printed wiring board, an insulating film adjacent to a surface of the printed wiring on the side where the printed wiring board is provided, and the electromagnetic wave shielding film.

The printed wiring board with a shielding film according to the present invention uses the adhesive composition of the present invention having a low dielectric property, and thus can be transported at a high speed in an electronic device, and is excellent in adhesion stability.

[ example ]

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

(carboxyl group-containing styrene elastomer)

A product name "Tuftecm1911" (maleic acid-modified styrene-ethylene butylene-styrene block copolymer) manufactured by Asahi Kabushiki Kaisha was used. The acid value of the copolymer was 2mgKOH/g, the styrene/ethylene butene ratio was 30/70, and the weight average molecular weight was 69000.

(carboxyl group-containing styrene elastomer)

A product name "Tuftecm1913" (maleic acid-modified styrene-ethylene butylene-styrene block copolymer) manufactured by Asahi Kabushiki Kaisha was used. The acid value of the copolymer was 10mgKOH/g, the styrene/ethylene butene ratio was 30/70, and the weight-average molecular weight was 67000.

(carboxyl group-containing styrene elastomer)

A product name "KratonFG1901" (maleic acid-modified styrene-ethylene butylene-styrene block copolymer) manufactured by Kraton corporation was used. The acid value of the copolymer was 19mgKOH/g, the styrene/ethylene butene ratio was 30/70, and the weight average molecular weight was 81000.

(styrene-based elastomer containing no carboxyl group)

Trade name "Tuftec P1500" (hydrogenated styrene-based elastomer) manufactured by Asahi Kabushiki Kaisha was used. The acid value of the copolymer was 0mgKOH/g, the styrene/ethylene butene ratio was 30/70, and the weight-average molecular weight was 67000.

(unmodified styrene-based elastomer)

A trade name "Kraton G1651" (styrene-ethylene butylene-styrene block copolymer) manufactured by Kraton corporation was used. The acid value of the copolymer was 0mgKOH/g, the styrene/ethylene butene ratio was 33/67, and the weight-average molecular weight was 136700.

(amino group-containing styrene elastomer)

A trade name "Tuftecnp 10" (amine modified styrene-ethylene butylene-styrene copolymer) manufactured by Asahi Kabushiki Kaisha was used. The copolymer had a styrene/ethylene butene ratio of 30/70 and a weight average molecular weight of 78000. The total nitrogen content in the copolymer was 430ppm (. Mu.g/g).

(epoxy-modified resin)

The trade name "epofribindat 501" (epoxide of styrene-butadiene block copolymer) manufactured by Daicel corporation was used. The copolymer had a styrene/ethylene butene ratio of 40/60, a weight average molecular weight of 92000 and an epoxy equivalent of 1055g/eq.

(epoxy-modified resin)

The trade name "epofrindct 310" (epoxide of styrene-butadiene block copolymer) manufactured by Daicel corporation was used. The copolymer had a styrene/ethylene butene ratio of 40/60, a weight average molecular weight of 93000 and an epoxy equivalent of 2125g/eq.

(epoxy resin)

As the epoxy resin, a novolak type epoxy resin, trade name "YX7700" (softening point 65 ℃ C.) manufactured by Mitsubishi chemical corporation was used. The epoxy equivalent is 270g/eq.

(epoxy resin)

As the epoxy resin, the trade name "HP-7200" (epoxy resin, softening point 56-66 ℃ C.) manufactured by DIC Co., ltd.) which is a novolak type epoxy resin was used. The epoxy equivalent is 259g/eq.

(PERBUTYL E)

As the organic peroxide, a peroxyester manufactured by Nikko Co., ltd., trade name "PERBUTYL E" was used.

(MK-100DS)

A mica having an average particle diameter of 3 μm manufactured by Kagaku Co., ltd., namely, trade name "MK-100DS" was used.

(UHP-S2)

A scale-like boron nitride having an average particle diameter of 0.7 μm manufactured by Showa Denko K.K., trade name "UHP-S2" was used.

(OP935)

A flame retardant manufactured by Clariant Chemicals corporation, namely, the trade name "OP935" was used.

(solvent)

A mixed solvent containing toluene and methyl ethyl ketone was used (mass ratio=90:10).

(substrate film)

As the base film, "Shin-Etsu Sepla Film PEEK" (polyether ether ketone, thickness 50 μm) manufactured by believed polymer Co was used.

(electrolytic copper foil)

As the electrolytic copper foil, "TQ-M7-VSP" manufactured by Mitsui Metal mining (electrolytic copper foil, thickness 12 μm, gloss Rz1.27 μm, gloss Ra0.197 μm, gloss Rsm12.95 μm) was used. The surface roughness of the glossy surface was measured by using a laser microscope to determine a roughness curve, and based on JISB0601 according to the roughness curve: 2013 (ISO 4287:1997 Amd.1:2009).

(mold release film)

As the release film, NP75SA (silicone release PET film, 75 μm) manufactured by PANAC corporation was used.

(determination of nitrogen content)

The total nitrogen content in the amino group-containing styrene-based elastomer used in the examples was determined by the following method.

< measurement method >)

The sample was obtained by using a micro nitrogen analyzer ND-100 (Mitsubishi chemical Co., ltd.) according to JIS-K2609.

Example 1

The components constituting the adhesive layer shown in table 1 were contained in the proportions shown in table 1, and these components were dissolved in a solvent to prepare a resin varnish having a solid content of 20 mass%.

The surface of the base film is subjected to corona treatment.

The resin varnish was applied to the surface of a base film, and dried in an oven at 110 ℃ for 4 minutes to volatilize toluene, thereby forming an adhesive layer, and an adhesive-equipped base film was obtained. The adhesive layer of the adhesive laminate was overlapped with the glossy surface of the electrolytic copper foil, and heat-laminated at 120 ℃. The adhesive layer is cured by post-curing the adhesive laminate before curing, and the cured adhesive laminate is obtained.

The adhesion force (N/cm) between the electrolytic copper foil and the base film of the adhesive laminate after curing in example 1 was measured.

[ adhesion force (N/cm) ]

The adhesion force was measured by cutting the cured adhesive laminate to prepare a test body having a width of 25mm, and measuring the peel strength when the electrolytic copper foil was peeled from the adhesive-carrying base film fixed to the support under the conditions of a peeling speed of 0.3 m/min and a peeling angle of 180 ° in accordance with JIS Z0237:2009 (adhesive tape/adhesive sheet test method).

The relative dielectric constant and dielectric loss tangent at a frequency of 28GHz were also measured for the adhesive layer in the cured adhesive laminate of example 1.

[ relative permittivity and dielectric loss tangent ]

The relative dielectric constant and dielectric loss tangent of the adhesive layer were measured 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) at a temperature of 23℃and a frequency of 28 GHz. The sample was measured, and a resin varnish was roll-coated on a release film, and then the film with the coating film was left to stand in an oven and dried at 110℃for 4 minutes to form an adhesive layer (thickness: 50 μm) in a B-stage state. Then, the adhesive layers were thermally laminated at 120℃so that the adhesive surfaces were in contact with each other, to form an adhesive film (thickness 100 μm) before curing. The pre-cured adhesive film (thickness 100 μm) was left to stand in an oven, and heat-curing treatment was performed at 150℃for 60 minutes to prepare a post-cured adhesive film (100 mm. Times.100 mm). The release film was peeled from the cured adhesive film, and the relative dielectric constant and dielectric loss tangent of the adhesive layer were measured.

The heat resistance of the adhesive layer in the laminate of example 1 was evaluated by a solder heat resistance test.

[ Heat resistance test of solder ]

The solder heat resistance test was carried out by floating the cured adhesive laminate in a solder bath at 288℃for 10 seconds X3 times on the base film, and it was confirmed that the adhesive layer was abnormal in appearance such as swelling and peeling.

The heat resistance of the laminate was evaluated by the following evaluation criteria.

No abnormality (no dissolution).

No abnormality was finally observed, but softening of the adhesive layer was observed in the test.

Delta was not peeled off, but softening of the adhesive layer and formation of a "speckle pattern" was observed.

And (5) stripping.

The measurement results are shown in Table 3.

Example 2 to example 15

In example 1, laminates of examples 2 to 15 were produced in the same manner as in example 1, except that the types and the amounts of components constituting the adhesive layer were changed as shown in table 1.

The laminate thus produced was evaluated in the same manner as in example 1.

The results are shown in Table 3.

Comparative examples 1 to 11

Laminates of comparative examples 1 to 11 were produced in the same manner as in example 1 except that the types and the amounts of components constituting the adhesive layer were changed as shown in table 2 in example 1.

The laminate thus produced was evaluated in the same manner as in example 1.

The results are shown in Table 4.

TABLE 1

TABLE 2

TABLE 3

TABLE 4

As shown in examples, the adhesive layer containing the adhesive composition of the present invention shows good electrical characteristics (dielectric characteristics) that can cope with 5G, and is excellent in adhesion, heat resistance, and solvent resistance.

Industrial applicability

The laminate having the adhesive layer containing the adhesive composition of the present invention can be suitably used for the production of FPC-related products for electronic devices such as smart phones, mobile phones, optical assemblies, digital cameras, game machines, notebook computers, medical appliances, and the like.

Claims

1. An adhesive composition comprising a styrene-based elastomer and an epoxy-modified resin having a structure represented by the following formula (1),

in formula (1), R ¹ 、R ² 、R ³ And R is ⁴ Each independently represents hydrogen or hasA radical, wherein R ¹ And R is ² At least one of which is an organic group, and R ³ And R is ⁴ At least one of which is an organic group.

2. The adhesive composition according to claim 1, wherein the styrene-based elastomer is a carboxyl group-containing styrene-based elastomer.

3. The adhesive composition according to claim 1, wherein the styrene-based elastomer is an amino group-containing styrene-based elastomer.

4. The adhesive composition according to any one of claims 1 to 3, wherein the content of the epoxy-modified resin is 1 to 50 parts by mass relative to 100 parts by mass of the adhesive composition.

5. The adhesive composition according to any one of claims 1 to 4, wherein the epoxy modified resin has an epoxy equivalent of 200g/eq. Or more and 20000g/eq. Or less.

6. The adhesive composition according to any one of claims 1 to 5, wherein the epoxy-modified resin has a structure represented by the following formula (2),

in formula (2), R ⁵ And R is ⁶ Each independently represents hydrogen or an alkyl group having 10 or less carbon atoms, and when a plurality of structures represented by the above formula (2) are present in the epoxy-modified resin, R in each formula (2) ⁵ Each identical or different, R in each formula (2) ⁶ Each identical or different, represents a bonding group.

7. The adhesive composition according to any one of claims 1 to 6, wherein the epoxy-modified resin contains an unsaturated bond other than an aromatic ring.

8. The adhesive composition according to claim 7, wherein the epoxy-modified resin has a structure represented by the following formula (3),

in formula (3), R ⁷ And R is ⁸ Each independently represents hydrogen or an alkyl group having 10 or less carbon atoms, and when a plurality of structures represented by the above formula (3) are present in the epoxy-modified resin, R in each formula (3) ⁷ Each identical or different, R in each formula (3) ⁸ Each identical or different, represents a bonding group.

9. The adhesive composition according to claim 6, wherein R in the formula (2) ⁵ And R is ⁶ Are all hydrogen.

10. The adhesive composition according to any one of claims 1 to 9, wherein the epoxy modified resin is a styrene-based elastomer.

11. The adhesive composition according to any one of claims 1 to 10, wherein the weight average molecular weight Mw of the epoxy modified resin is 30000 to 200000.

12. The adhesive composition according to any one of claims 1 to 11, wherein the adhesive composition contains a radical polymerization initiator.

13. An adhesive layer obtained by curing the adhesive composition according to any one of claims 1 to 12, wherein the adhesive layer has a relative dielectric constant of 3 or less and a dielectric loss tangent of 0.004 or less, as measured at a frequency of 28 GHz.

14. A laminate, characterized by comprising:

a base material film; and

an adhesive layer comprising the adhesive composition according to any one of claims 1 to 12, or an adhesive layer according to claim 13.

15. The laminate of claim 14, wherein the substrate film comprises a polyetheretherketone PEEK resin.