CN114555744A

CN114555744A - Adhesive composition and adhesive sheet

Info

Publication number: CN114555744A
Application number: CN202080075276.XA
Authority: CN
Inventors: 西嶋健太; 山崎俊弥
Original assignee: Lintec Corp
Current assignee: Lintec Corp
Priority date: 2019-10-30
Filing date: 2020-09-29
Publication date: 2022-05-27
Anticipated expiration: 2040-09-29
Also published as: TW202124646A; CN114555744B; KR20220089694A; JPWO2021085009A1; WO2021085009A1

Abstract

The present invention relates to an adhesive composition containing the following components (A) and (B); and an adhesive sheet having an adhesive layer formed using the adhesive composition. The adhesive composition provides a cured product having low dielectric characteristics in a high-frequency region and excellent adhesive strength. (A) The components: a modified polyolefin resin; (B) the components: a compound having a polyphenylene ether skeleton and a crosslinkable functional group.

Description

Adhesive composition and adhesive sheet

Technical Field

The present invention relates to an adhesive composition for imparting a cured product having low dielectric characteristics and excellent adhesive strength in a high-frequency region; and an adhesive sheet having an adhesive layer formed using the adhesive composition. In the present specification, the high frequency region refers to a region of 300MHz to 300 GHz.

Background

In recent years, with the miniaturization and weight reduction of electronic devices, flexible printed wiring boards (FPCs) have been increasingly used as wiring members.

The FPC can be obtained by, for example, etching a copper foil of a copper clad laminate obtained by laminating a copper foil on an insulating resin film such as polyimide to form a circuit (electric circuit).

In general, a cover film having an insulating resin base material and an adhesive layer is bonded to a copper foil on which a circuit is formed to protect the circuit.

Accordingly, in recent years, with respect to communication devices such as smartphones, electric signals have become higher in frequency to process data of larger capacity.

However, since an electric signal in a high frequency range is easily converted into heat, when the electric signal is increased in frequency, transmission loss tends to increase.

In order to transmit an electric signal in a high frequency region at a high speed and suppress transmission loss, dielectric characteristics (reduction in dielectric constant and reduction in dielectric loss tangent) of an insulator (a base material, an adhesive, or the like) constituting a wiring member are improved.

In order to further reduce the transmission loss, flattening of the surface of the copper foil and use of a substrate that is difficult to adhere have also been studied, and to cope with this, an adhesive having more excellent adhesion has also been developed.

Patent document 1 describes a laminate with an adhesive layer, which is a laminate with an adhesive layer comprising a base film and an adhesive layer (located on at least one surface of the base film), wherein the adhesive layer is composed of a specific adhesive composition.

Patent document 1 also describes: the laminate with an adhesive layer is excellent in adhesion to a base film or a copper foil, electrical properties (low dielectric constant, low dielectric loss tangent), and the like.

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open publication No. 2018-150541.

Disclosure of Invention

Problems to be solved by the invention

A cured product of the adhesive composition described in patent document 1 has sufficient adhesive strength and low dielectric properties (in the present specification, "having low dielectric properties" means "having low dielectric constant and low dielectric loss tangent").

However, in order to cope with further increase in frequency of electric signals expected in the future, an adhesive composition which gives a cured product having further excellent low dielectric characteristics and adhesive strength in a high frequency range is desired.

The present invention has been made in view of the above circumstances, and an object thereof is to provide: an adhesive composition for imparting a cured product having low dielectric characteristics and excellent adhesive strength in a high-frequency region; and an adhesive sheet having an adhesive layer formed using the adhesive composition.

Means for solving the problems

The present inventors have conducted intensive studies on an adhesive composition in order to solve the above problems. As a result, they found that: the present inventors have completed the present invention by providing an adhesive composition containing a modified polyolefin resin and a polyphenylene ether resin having a reactive group to a cured product having low dielectric characteristics and excellent adhesive strength in a high frequency region.

Accordingly, the present invention provides the adhesive compositions of [1] to [7] and the adhesive sheet of [8 ].

[1] An adhesive composition comprising the following components (A) and (B):

(A) the components: a modified polyolefin resin;

(B) the components: polyphenylene ether resins having reactive groups.

[2] [1] the adhesive composition according to any one of the preceding claims, wherein the modified polyolefin resin is contained in an amount of more than 50% by mass based on the total amount of active ingredients in the adhesive composition.

[3] [1] the adhesive composition according to [1] or [2], wherein the reactive group of the polyphenylene ether resin having a reactive group is a group having an ethylenically unsaturated bond.

[4] The adhesive composition according to any one of [1] to [3], further comprising the following component (C),

(C) the components: a compound having an alicyclic skeleton and a cyclic ether group.

[5] [4] the adhesive composition according to any one of the preceding claims, wherein the content of the compound having an alicyclic skeleton and a cyclic ether group is 10% by mass or less based on the total amount of active ingredients in the adhesive composition.

[6] [4] the adhesive composition according to [5], wherein at least 1 of the compounds having an alicyclic skeleton and a cyclic ether group is a compound that is liquid at 25 ℃, and the content of the compound having an alicyclic skeleton and a cyclic ether group that is liquid at 25 ℃ is 10% by mass or less of the total amount of active ingredients of the adhesive composition.

[7] The adhesive composition according to any one of [1] to [6], further comprising the following component (D),

(D) the components: and (3) a curing agent.

[8] [7] the adhesive composition according to any one of [1] or [2], wherein the curing agent contains a cationic polymerization initiator.

[9] The adhesive composition according to any one of [1] to [8], further comprising the following component (E),

(E) the components: a silane coupling agent.

[10] An adhesive sheet having an adhesive layer formed using the adhesive composition according to any one of [1] to [9 ].

Effects of the invention

According to the present invention, there is provided an adhesive composition for imparting a cured product having low dielectric characteristics and excellent adhesive strength in a high-frequency region; and an adhesive sheet having an adhesive layer formed using the adhesive composition.

Detailed Description

Hereinafter, the present invention will be described in detail by dividing it into 1) an adhesive composition and 2) an adhesive sheet.

1) Adhesive composition

The adhesive composition of the present invention contains the following components (a) and (B):

(A) the components: a modified polyolefin resin;

(B) the components: polyphenylene ether resins having reactive groups.

[ (A) ingredient: modified polyolefin resin

The adhesive composition of the present invention contains a modified polyolefin resin as the component (a).

The modified polyolefin resin is an olefin resin having functional groups introduced therein, which is obtained by modifying an olefin resin as a precursor with a modifier.

Since the modified polyolefin resin has a polyolefin skeleton, a cured product of the adhesive composition of the present invention containing the modified polyolefin resin has low dielectric characteristics.

Further, since the modified polyolefin resin has a functional group, a cured product of the adhesive composition of the present invention containing the modified polyolefin resin is excellent in adhesive strength.

The olefin-based resin is a polymer containing a repeating unit derived from an olefin-based monomer. The olefin-based resin may be a polymer composed only of a repeating unit derived from an olefin-based monomer, or may be a polymer composed of a repeating unit derived from an olefin-based monomer and a repeating unit derived from a monomer copolymerizable with the olefin-based monomer. The olefin-based resin is preferably a polymer composed only of repeating units derived from an olefin-based monomer, from the viewpoint of easily obtaining a cured product having excellent low dielectric characteristics.

The olefin monomer is preferably one having 2 to 8 carbon atomsα-an olefin, more preferably ethylene, propylene, 1-butene, isobutene, or 1-hexene, further preferably ethylene or propylene. These olefinic monomers may be used alone in 1 kind, or in combination of 2 or more kinds.

Examples of the monomer copolymerizable with the olefinic monomer include: vinyl acetate, (meth) acrylates, styrene, and the like. Here, "(meth) acrylic" means acrylic or methacrylic (hereinafter, the same applies).

These monomers copolymerizable with the olefin-based monomer may be used alone in 1 kind, or in combination with 2 or more kinds.

Examples of the olefin-based resin include: very Low Density Polyethylene (VLDPE), Low Density Polyethylene (LDPE), Medium Density Polyethylene (MDPE), High Density Polyethylene (HDPE), linear low density polyethylene, polypropylene (PP), ethylene-propylene copolymer, olefin elastomer (TPO), ethylene-vinyl acetate copolymer (EVA), ethylene- (meth) acrylic acid copolymer, ethylene- (meth) acrylate copolymer, and the like.

The modifier used for modification treatment of the olefin-based resin is a compound having a functional group in the molecule.

Examples of the functional group include: carboxyl groups, carboxylic anhydride groups, carboxylic ester groups, hydroxyl groups, epoxy groups, amide groups, ammonium groups, nitrile groups, amino groups, imide groups, isocyanate groups, acetyl groups, thiol groups, ether groups, thioether groups, sulfone groups, phosphine groups, nitro groups, urethane groups, alkoxysilyl groups, silanol groups, halogen atoms and the like. The compound having a functional group may have 2 or more functional groups in the molecule.

The modified polyolefin resin may be used alone in 1 kind, or in combination of 2 or more kinds.

The number average molecular weight (Mw) of the modified polyolefin resin is preferably 10,000 to 150,000, more preferably 30,000 to 100,000.

The number average molecular weight (Mw) of the modified polyolefin resin can be determined as a standard polystyrene equivalent value by Gel Permeation Chromatography (GPC) using Tetrahydrofuran (THF) as a solvent.

The content of the modified polyolefin resin is preferably more than 50% by mass, more preferably more than 50% by mass and 90% by mass or less, and further preferably 55% by mass or more and 85% by mass or less, of the total amount of the active ingredients of the adhesive composition.

When the content of the modified polyolefin resin is more than 50% by mass of the total amount of the active ingredients of the adhesive composition, the adhesive composition can be easily obtained which gives a cured product having low dielectric characteristics in a high frequency range and excellent adhesive strength.

In the present specification, the "active ingredient" refers to a component other than a solvent among components constituting the adhesive composition.

The modified polyolefin resin is preferably an acid-modified polyolefin resin from the viewpoint of forming a cured product having more excellent adhesive strength.

The acid-modified polyolefin resin is a resin obtained by graft-modifying an olefin resin with an acid or an acid anhydride. Examples thereof include: a resin obtained by introducing a carboxyl group or a carboxylic anhydride group (graft modification) by reacting an unsaturated carboxylic acid or an unsaturated carboxylic anhydride (hereinafter, sometimes referred to as "unsaturated carboxylic acid or the like") with an olefin resin.

Examples of the unsaturated carboxylic acid to be reacted with the olefin resin include: unsaturated carboxylic acids such as maleic acid, fumaric acid, itaconic acid, citraconic acid, glutaric acid, tetrahydrophthalic acid, and aconitic acid; unsaturated carboxylic acid anhydrides such as maleic anhydride, itaconic anhydride, glutaric anhydride, citraconic anhydride, aconitic anhydride, norbomene dicarboxylic anhydride and tetrahydrophthalic anhydride.

These can be used alone in 1 kind, or in combination of 2 or more. Among these, maleic anhydride is preferable because a cured product having more excellent adhesive strength can be easily obtained.

The amount of the unsaturated carboxylic acid or the like to be reacted with the olefin-based resin is preferably 0.1 to 5 parts by mass, more preferably 0.2 to 3 parts by mass, and still more preferably 0.2 to 1 part by mass, based on 100 parts by mass of the olefin-based resin. By curing the adhesive composition containing the acid-modified polyolefin resin thus obtained, a cured product having more excellent adhesive strength can be formed.

The method for introducing the unsaturated carboxylic acid unit or the unsaturated carboxylic acid anhydride unit into the olefin-based resin is not particularly limited. Examples thereof include: a method of reacting an olefin resin with an unsaturated carboxylic acid or the like by heating and melting the olefin resin to a temperature higher than the melting point of the olefin resin in the presence of a radical generator such as an organic peroxide or azonitrile; or a method in which an olefin resin and an unsaturated carboxylic acid are dissolved in an organic solvent, and then the mixture is heated and stirred in the presence of a radical generator to react the mixture, thereby graft-copolymerizing an unsaturated carboxylic acid and the like with an olefin resin.

As the acid-modified polyolefin resin, commercially available products can also be used. Examples of commercially available products include: admer (registered trademark) (manufactured by mitsui Chemical company), Unistole (registered trademark) (manufactured by mitsui Chemical company), BondyRam (manufactured by Polyram), orevac (registered trademark) (manufactured by ARKEMA company), Modic (registered trademark) (manufactured by mitsubishi Chemical company), and the like.

[ (B) ingredient: polyphenylene ether resin having reactive group ]

The adhesive composition of the present invention contains a polyphenylene ether resin having a reactive group as the component (B) (hereinafter, may be referred to as "polyphenylene ether resin (B)").

The polyphenylene ether resin is a resin having a polyphenylene skeleton in the main chain.

The polyphenylene skeleton is a compound having a repeating unit represented by the following formula,

[ chemical formula 1]

Or a skeleton having a repeating unit in which a hydrogen atom in the above formula is substituted.

The polyphenylene ether resin (B) is a compound having a polyphenylene ether skeleton and a reactive group.

Since the polyphenylene ether resin (B) has a polyphenylene ether skeleton, a cured product of the adhesive composition of the present invention containing the polyphenylene ether resin (B) has low dielectric characteristics.

Further, since the polyphenylene ether resin (B) has a reactive group, a cured product of the adhesive composition of the present invention containing the polyphenylene ether resin (B) is excellent in heat resistance.

Examples of the polyphenylene ether skeleton in the polyphenylene ether resin (B) include: a polyphenylene ether skeleton represented by the following formula (1).

[ chemical formula 2]

In the formula (1), X is a 2-valent group represented by the following formula (2) or formula (3), Y is a 2-valent group represented by the following formula (4), a and b are integers of 0-100, and at least one of a and b is more than 1. Denotes a bond (hereinafter, the same applies).

[ chemical formula 3]

In the formula (2), R¹～R⁸Each independently represents a hydrogen atom, a halogen atom, an alkyl group having 6 or less carbon atoms, or a phenyl group, and preferably a hydrogen atom or a methyl group.

[ chemical formula 4]

In the formula (3), R⁹～R¹⁶Each independently represents a hydrogen atom, a halogen atom, an alkyl group having 6 or less carbon atoms, or a phenyl group, and preferably a hydrogen atom or a methyl group. A represents a linear, branched or cyclic 2-valent hydrocarbon group having 20 or less carbon atoms.

[ chemical formula 5]

In the formula (4), R¹⁷～R²⁰Each independently represents a hydrogen atom, a halogen atom, an alkyl group having 6 or less carbon atoms, or a phenyl group, and preferably a hydrogen atom or a methyl group.

Examples of the polyphenylene ether skeleton in the polyphenylene ether resin (B) include: a polyphenylene ether skeleton represented by the following formula (5).

[ chemical formula 6]

Examples of the reactive group in the polyphenylene ether resin (B) include: groups having an ethylenically unsaturated bond such as vinyl, allyl, acryloyl, methacryloyl, cyclopentenyl, vinylbenzyl, and vinylnaphthyl; an epoxy group; hydroxyl groups, and the like.

Among these, the reactive group is preferably a group having an ethylenically unsaturated bond, and more preferably a vinylbenzyl group, from the viewpoint of easily obtaining a cured product having low dielectric characteristics.

The polyphenylene ether resin (B) is preferably a resin having reactive groups at both ends of the polyphenylene ether skeleton, from the viewpoint of easily obtaining a cured product having low dielectric characteristics.

The polyphenylene ether resin (B) can be obtained by introducing a reactive group into the terminal after the formation of the polyphenylene ether skeleton.

For example, the polyphenylene ether resin (B) having vinylbenzyl groups as reactive groups at both terminals can be obtained by reacting a bifunctional phenol compound with a monofunctional phenol compound to obtain a polymer having phenolic hydroxyl groups at both terminals, and then vinylbenzyl-etherifying the phenolic hydroxyl groups at the terminals using 4- (chloromethyl) styrene.

Examples of the polyphenylene ether resin (B) include: a polyphenylene ether resin represented by the following formula (6).

[ chemical formula 7]

As the polyphenylene ether resin (B), commercially available products can also be used. Examples of commercially available products include: "OPE-2 St (modified polyphenylene ether resin having vinylbenzyl groups at both ends)," OPE-2Gly (modified polyphenylene ether resin having epoxy groups at both ends), "OPE-2 EA (modified polyphenylene ether resin having acryloyl groups at both ends, manufactured by Mitsubishi GAS chemical corporation, supra)," Noryl SA9000 (modified polyphenylene ether resin having methacryloyl groups at both ends, manufactured by SABIC corporation), and the like.

The polyphenylene ether resin (B) preferably has a weight average molecular weight (Mw) of 500 to 5,000, more preferably 500 to 3,000.

The weight average molecular weight (Mw) of the polyphenylene ether resin (B) can be determined as a standard polystyrene equivalent by Gel Permeation Chromatography (GPC) using Tetrahydrofuran (THF) as a solvent.

Polyphenylene ether resin (B) may be used alone in 1 kind, or in combination of 2 or more kinds.

The content of the polyphenylene ether resin (B) is preferably 1% by mass or more, more preferably 10 to 50% by mass, and further preferably 15 to 40% by mass, based on the total amount of the active ingredients of the adhesive composition.

By setting the content of the polyphenylene ether resin (B) to 1 mass% or more in the total amount of the active ingredients of the adhesive composition, a cured product having low dielectric characteristics can be easily obtained.

[ (C) ingredient: compound having alicyclic skeleton and cyclic ether group ]

The adhesive composition of the present invention may contain a compound having an alicyclic skeleton and a cyclic ether group as the component (C).

The compound having an alicyclic skeleton and a cyclic ether group (hereinafter, sometimes referred to as "cyclic ether group-containing compound (C)") is a compound having an alicyclic skeleton in a molecule and having at least 1, preferably 2 or more cyclic ether groups in a molecule.

Since the cyclic ether group-containing compound (C) has a cyclic ether group, a cured product of the adhesive composition containing the cyclic ether group-containing compound (C) has excellent adhesive strength.

The number of cyclic ether groups in the molecule of the cyclic ether group-containing compound (C) is preferably 2 to 6, more preferably 2 to 4, and still more preferably 2. By using a compound having 2 cyclic ether groups as the cyclic ether group-containing compound (C), curing shrinkage of the curable adhesive layer can be suppressed even when the compound (C) exhibits curability and the amount of the cyclic ether group-containing compound (C) to be added is large. Therefore, for example, when the adhesive composition is used for bonding a plate-like member such as a circuit board, warpage of the plate-like member can be reduced.

The molecular weight of the cyclic ether group-containing compound (C) is usually 100 to 5,000, preferably 200 to 3,000.

The cyclic ether equivalent of the cyclic ether group-containing compound (C) is preferably 50g/eq or more and 1000g/eq or less, more preferably 100g/eq or more and 800g/eq or less.

By curing the adhesive composition containing the cyclic ether group-containing compound (C) having the cyclic ether equivalent in the above range, a cured product having more excellent adhesive strength can be formed more efficiently.

The cyclic ether equivalent in the present invention means a value obtained by dividing the molecular weight by the number of cyclic ether groups.

Examples of the cyclic ether group include: an oxirane group (epoxy group), an oxetanyl group (oxetanyl group), a tetrahydrofuranyl group, a tetrahydropyranyl group, and the like.

Among these, as the cyclic ether group, an ethylene oxide group is preferable.

In the present specification, the oxirane group includes a group having an oxirane structure such as a glycidyl group, a glycidyl ether group, and an epoxycyclohexyl group.

Examples of the cyclic ether group-containing compound (C) include: a polyglycidyl ether compound of a polyhydric alcohol having at least 1 or more alicyclic structures, or a cycloolefin oxide compound such as a cyclohexene oxide or cyclopentene oxide-containing compound obtained by epoxidizing a cyclohexene ring-or cyclopentene ring-containing compound with an oxidizing agent.

Representative examples of the cyclic ether group-containing compound (C) include: hydrogenated bisphenol A diglycidyl ether, 3, 4-epoxycyclohexylmethyl-3, 4-epoxycyclohexanecarboxylate, 3, 4-epoxy-1-methylcyclohexyl-3, 4-epoxy-1-methylcyclohexanecarboxylate, 6-methyl-3, 4-epoxycyclohexylmethyl-6-methyl-3, 4-epoxycyclohexanecarboxylate, 3, 4-epoxy-3-methylcyclohexylmethyl-3, 4-epoxy-3-methylcyclohexanecarboxylate, 3, 4-epoxy-5-methylcyclohexylmethyl-3, 4-epoxy-5-methylcyclohexanecarboxylate, bis (3, 4-epoxycyclohexylmethyl) adipate, bis (3, 4-epoxycyclohexylmethyl) phthalate, bis (3, 4-epoxycyclohexyl) phthalate, bis (2-epoxycyclohexyl) phthalate, bis (3, 4-epoxycyclohexyl) phthalate, 4-epoxycyclohexyl-methyl-and (3, 4-epoxycyclohexyl) phthalate, 3, 4-epoxy-6-methylcyclohexaneformate, methylenebis (3, 4-epoxycyclohexane), propane-2, 2-diyl-bis (3, 4-cycloOxycyclohexane), 2-bis (3, 4-epoxycyclohexyl) propane, dicyclopentadiene diepoxide, ethylene bis (3, 4-epoxycyclohexane carboxylate), dioctyl epoxyhexahydrophthalate, di-2-ethylhexyl epoxyhexahydrophthalate, 1-epoxyethyl-3, 4-epoxycyclohexane, 1, 2-epoxy-2-epoxyethylcyclohexane, ethylene-propylene-diene monomer, ethylene-propylene-diene monomer, ethylene-propylene-diene monomer, ethylene-diene monomer, ethylene-diene monomer, bis (3, ethylene-2, ethylene-diene monomer, ethylene-2, bis (3, ethylene-2, bis (3, epoxy-2-epoxycyclohexane, epoxy,αPinene oxide, limonene dioxide, and the like.

Further, as the cyclic ether group-containing compound (C), commercially available products can be used. Examples of commercially available products include: celloxide 2021P, Celloxide 2081, Celloxide 2000, and Celloxide 8010 (manufactured by Daicel corporation, supra); eplight 4000 (manufactured by Kyoeisha chemical Co.); YX8000 and YX8034 (manufactured by Mitsubishi Chemical Co., Ltd.); adeka Resin EP-4088S, Adeka Resin EP-4088L, Adeka Resin EP-4080E (manufactured by ADEKA Co., Ltd.).

The cyclic ether group-containing compound (C) may be used alone in 1 kind or in combination of 2 or more kinds.

When the adhesive composition of the present invention contains the cyclic ether group-containing compound (C), the content of the cyclic ether group-containing compound (C) is preferably 1% by mass or more, more preferably 2 to 15% by mass, based on the total amount of the active ingredients of the adhesive composition.

When the content of the cyclic ether group-containing compound (C) is 1 mass% or more based on the total amount of the active ingredients in the adhesive composition, the adhesive composition can be easily provided with tackiness and has excellent adhesiveness, and a cured product having more excellent adhesive strength can be easily obtained.

In addition, the content of the cyclic ether group-containing compound (C) is preferably 10% by mass or less, more preferably 2 to 10% by mass, in the total amount of the active ingredients of the adhesive composition, from the viewpoint of easily obtaining a cured product having low dielectric characteristics.

At least 1 of the cyclic ether group-containing compounds (C) is preferably a compound which is liquid at 25 ℃.

"liquid at 25" means that it has fluidity at 25 ℃. The viscosity of the cyclic ether group-containing compound (B) is preferably 2 to 10000mPa as measured with an E-type viscometer at 25 ℃ and 1.0 rpm.

As described above, the adhesive composition of the present invention contains the polyphenylene ether resin (B). Since polyphenylene ether resin (B) has a relatively rigid molecular structure, an adhesive composition containing polyphenylene ether resin (B) tends to have poor coatability or poor adhesiveness.

In this regard, by including the cyclic ether group-containing compound (C) which is liquid at 25 ℃, in the adhesive composition, coatability, adhesiveness, or tackiness can be effectively improved.

When the adhesive composition contains the cyclic ether group-containing compound (C) which is liquid at 25 ℃, the content thereof is preferably 15% by mass or less, more preferably 2 to 10% by mass, of the total amount of the active ingredients of the adhesive composition. From the viewpoint of improving the sticking suitability when the adhesive composition of the present invention is used as an adhesive layer, the content of the cyclic ether group-containing compound (C) is preferably 3 to 10% by mass of the total amount of the active ingredients of the adhesive composition.

By setting the content of the cyclic ether group-containing compound (C) which is liquid at 25 ℃ to 15 mass% or less in the total amount of the active ingredients of the adhesive composition, a cured product having low dielectric characteristics can be easily obtained.

The curable adhesive layer may contain a compound having a cyclic ether group other than the cyclic ether group-containing compound (C), that is, a compound having no alicyclic skeleton but having a cyclic ether group, but the amount thereof to be used is preferably reduced in order to further reduce the dielectric constant and dielectric loss tangent of a cured product of the adhesive composition. From such a viewpoint, the mass ratio of the cyclic ether group-containing compound (C) to the mass of the cyclic ether group-containing compound contained in the adhesive composition is preferably 90 mass% or more, and more preferably 95 mass% or more.

[ (D) ingredient: curing agent ]

The adhesive composition of the present invention may contain a curing agent as the component (D).

An adhesive composition containing a curing agent is preferable because the curing reaction proceeds more efficiently.

The curing agent is not particularly limited as long as it is a curing agent that initiates a curing reaction. From the viewpoint of efficiently reacting the polyphenylene ether resin (B) with the cyclic ether group-containing compound (C) and easily obtaining a cured product having a high elastic modulus, it is preferable to use a cationic polymerization initiator as the curing agent. From the viewpoint of excellent stability over time and productivity, it is preferable to use a curing agent that initiates a curing reaction by heating as the curing agent.

Examples of the curing agent that initiates the curing reaction by heating include: a thermal cationic polymerization initiator, or a thermally reactive curing agent other than the thermal cationic polymerization initiator. When a thermal cationic polymerization initiator is used, the polyphenylene ether resin (B) and the cyclic ether group-containing compound (C) are likely to flow due to heating in the thermosetting step. As a result, the reactive functional groups are more likely to associate and the reaction proceeds more efficiently than in the case of photo cation polymerization, which is preferable.

The thermal cationic polymerization initiator is a compound capable of generating a cationic species that initiates polymerization by heating.

Examples of the thermal cationic polymerization initiator include: sulfonium salts, quaternary ammonium salts, phosphonium salts, diazonium salts, iodonium salts, and the like.

Examples of sulfonium salts include: triphenylsulfonium tetrafluoroborate, triphenylsulfonium hexafluoroantimonate, triphenylsulfonium hexafluoroarsenate, tris (4-methoxyphenyl) sulfonium hexafluoroarsenate, diphenyl (4-phenylthiophenyl) sulfonium hexafluoroarsenate, and the like.

As the sulfonium salt, commercially available ones can also be used. Examples of commercially available products include: adeka Opton SP-150, Adeka Opton SP-170, Adeka Opton CP-66, Adeka Opton CP-77 (manufactured by ADEKA Co., Ltd.), San-Aid SI-60L, San-Aid SI-80L, San-Aid SI-100L, San-Aid SI-B2A, San-Aid SI-B3 (manufactured by Sanxin chemical Co., Ltd.), CYRACURE UVI-6974, CYRACURE UVI-6990 (manufactured by Union Carbide Co., Ltd.), UVI-508, UVI-509 (manufactured by General Electric Co., Ltd.), FC-508, FC-509 (manufactured by Minnesota Mining & Manufacturing Co., Ltd.), CD-1010, CD-1011 (manufactured by Sartomer Co., Ltd.), CI series products (manufactured by Nippon Dada Co., Ltd.), and the like.

Examples of the quaternary ammonium salt include: tetrabutylammonium tetrafluoroborate, tetrabutylammonium hexafluorophosphate, tetrabutylammonium hydrogensulfate, tetraethylammonium tetrafluoroborate, tetraethylammonium p-toluenesulfonate, N-dimethyl-N-benzylanilinium hexafluoroantimonate, N-dimethyl-N-benzylanilinium tetrafluoroborate, N-dimethyl-N-benzylpyridinium hexafluoroantimonate, N-diethyl-N-benzyltrifluoromethanesulfonate, N-dimethyl-N- (4-methoxybenzyl) pyridinium hexafluoroantimonate, N-diethyl-N- (4-methoxybenzyl) toluidinium hexafluoroantimonate and the like.

Examples of the phosphonium salt include: ethyltriphenylphosphonium hexafluoroantimonate, tetrabutylphosphonium hexafluoroantimonate, and the like.

Examples of the diazonium salt include: AMERICURE (manufactured by American Can corporation), ULTRASET (manufactured by ADEKA corporation), and the like.

Examples of the iodonium salt include: diphenyliodonium hexafluoroarsenate, bis (4-chlorophenyl) iodonium hexafluoroarsenate, bis (4-bromophenyl) iodonium hexafluoroarsenate, phenyl (4-methoxyphenyl) iodonium hexafluoroarsenate, and the like. Further, as a commercially available product, there can be used: UV-9310C (Toshiba Silicones Co., Ltd.), Photonitiator 2074 (Rhone-Poulenc Co., Ltd.), UVE series products (General Electric Co., Ltd.), FC series products (Minnesota Mining & Manufacturing Co., Ltd.), and the like.

Examples of the thermally reactive curing agent other than the thermal cationic polymerization initiator include: amine compounds such as benzylmethylamine and 2,4, 6-tris-dimethylaminomethylphenol; imidazole compounds such as 2-methylimidazole, 2-ethyl-4-methylimidazole and 2-heptadecylimidazole; lewis acids such as boron trifluoride/monoethylamine complex and boron trifluoride/piperazine complex.

The curing agent can be used alone in 1 kind, or in combination of 2 or more kinds.

When the adhesive composition of the present invention contains a curing agent, the content of the curing agent is preferably 1 to 10 parts by mass, more preferably 2 to 9 parts by mass, and still more preferably 3 to 8 parts by mass, per 100 parts by mass of the cyclic ether group-containing compound (C).

[ (E) ingredient: silane coupling agent

The adhesive composition of the present invention may contain a silane coupling agent as the component (E).

By using a silane coupling agent, a cured product having more excellent adhesive strength can be easily obtained.

As the silane coupling agent, known silane coupling agents can be used. Among them, an organosilicon compound having at least 1 alkoxysilyl group in the molecule is preferable.

Examples of the silane coupling agent include: silane coupling agents having a (meth) acryloyl group such as 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, 3-methacryloxypropyltriethoxysilane, and 3-acryloxypropyltrimethoxysilane;

silane coupling agents having a vinyl group such as vinyltrimethoxysilane, vinyltriethoxysilane, dimethoxymethylvinylsilane, diethoxymethylvinylsilane, trichloroethylsilane, and vinyltris (2-methoxyethoxy) silane;

silane coupling agents having an epoxy group such as 2- (3, 4-epoxycyclohexyl) ethyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-glycidoxypropyltriethoxysilane, and 8-glycidoxypropyloctyltrimethoxysilane;

styrene-based silane coupling agents such as p-styryltrimethoxysilane and p-styryltriethoxysilane;

silane coupling agents having an amino group such as N- (2-aminoethyl) -3-aminopropylmethyldimethoxysilane, N- (2-aminoethyl) -3-aminopropyltrimethoxysilane, N- (2-aminoethyl) -3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-triethoxysilyl-N- (1, 3-dimethyl/butylene) propylamine, N-phenyl-3-aminopropyltrimethoxysilane, and hydrochloride of N- (vinylbenzyl) -2-aminoethyl-3-aminopropyltrimethoxysilane;

silane coupling agents having a ureido group such as 3-ureidopropyltrimethoxysilane and 3-ureidopropyltriethoxysilane;

silane coupling agents having a halogen atom such as 3-chloropropyltrimethoxysilane and 3-chloropropyltriethoxysilane;

silane coupling agents having a mercapto group such as 3-mercaptopropylmethyldimethoxysilane and 3-mercaptopropyltrimethoxysilane;

silane coupling agents having a sulfide group such as bis (trimethoxysilylpropyl) tetrasulfide and bis (triethoxysilylpropyl) tetrasulfide;

silane coupling agents having an isocyanate group such as 3-isocyanatopropyltrimethoxysilane and 3-isocyanatopropyltriethoxysilane;

silane coupling agents having allyl groups such as allyl trichlorosilane, allyl triethoxysilane, and allyl trimethoxysilane;

and silane coupling agents having a hydroxyl group such as 3-hydroxypropyltrimethoxysilane and 3-hydroxypropyltriethoxysilane.

These silane coupling agents may be used alone in 1 kind, or in combination with 2 or more kinds.

When the adhesive composition of the present invention contains a silane coupling agent, the content of the silane coupling agent is preferably 0.01 to 5% by mass, and more preferably 0.05 to 1% by mass, based on the total amount of the active ingredients of the adhesive composition.

[ solvent ]

The adhesive composition of the present invention may contain a solvent.

Examples of the solvent include: aromatic hydrocarbon solvents such as benzene and toluene; ester solvents such as ethyl acetate and butyl acetate; ketone solvents such as acetone, methyl ethyl ketone, and methyl isobutyl ketone; aliphatic hydrocarbon solvents such as n-pentane, n-hexane, and n-heptane; alicyclic hydrocarbon solvents such as cyclopentane, cyclohexane, and methylcyclohexane.

These solvents may be used alone in 1 kind, or in combination of 2 or more kinds.

When the adhesive composition of the present invention contains a solvent, the content of the solvent may be determined as appropriate in consideration of coatability and the like.

[ other ingredients ]

The adhesive composition of the present invention may contain other components within a range not to impair the effects of the present invention.

Examples of other components include: additives such as ultraviolet absorbers, antistatic agents, light stabilizers, antioxidants, resin stabilizers, fillers, pigments, extenders, and softeners.

These can be used alone in 1 kind, or in combination of 2 or more.

When the adhesive composition of the present invention contains these additives, the content thereof may be determined as appropriate according to the purpose.

[ adhesive composition ]

The adhesive composition of the present invention can be prepared by appropriately mixing and stirring the components (a) and (B) and any other components according to a conventional method.

The cured product of the adhesive composition of the present invention has low dielectric characteristics in a high frequency region.

The specific dielectric constant of a cured product of the adhesive composition at 23 ℃ and a frequency of 1GHz (hereinafter, the specific dielectric constant may be referred to as "specific dielectric constant: (α) ") is preferably 2.66 or less, more preferably 2.50 or less, and particularly preferably 2.45 or less.

Contrast dielectric constant: (α) The lower limit of (b) is not particularly limited, but is usually 2.00 or more.

Can form a specific dielectric constant ofα) The adhesive composition is a cured product of 2.66 or less, and is suitable for use as an adhesive for flexible printed wiring board assembly.

Specific dielectric constant: (α) The measurement sample of (a) is not particularly limited as long as it is a sample in which the adhesive composition is sufficiently cured.

For example, when the adhesive composition has curability, the specific dielectric constant is (α) The cured adhesive is used as a measurement sample. When the measured adhesive composition has recommended curing conditions, a cured adhesive material cured under the recommended conditions is used as the specific dielectric constant: (α) The measurement sample of (1). In the case where the adhesive composition does not recommend curing conditions or is unknown, the adhesive composition may be cured under curing conditions of, for example, 160 ℃ for 1 hourAs a specific dielectric constant: (α) The measurement sample of (1).

Specific dielectric constant: (α) The measurement can be carried out according to the method described in examples.

The dielectric loss tangent of a cured product of the adhesive composition at 23 ℃ and a frequency of 1GHz (hereinafter, this dielectric loss tangent may be referred to as "dielectric loss tangent: (β) ") is preferably 0.0100 or less, more preferably 0.0075 or less, and still more preferably 0.0050 or less.

For dielectric loss tangent of (β) The lower limit of (b) is not particularly limited, but is usually 0.0001 or more.

Can form a dielectric loss tangent ofβ) An adhesive composition which is a cured product of 0.0100 or less and is suitable for use as an adhesive for flexible printed wiring board assembly.

Dielectric loss tangent of (β) The measurement can be carried out according to the method described in examples.

The cured product of the adhesive composition of the present invention has excellent adhesive strength.

When the peel adhesion strength is measured by the method described in examples, it is usually 8N/cm or more. The upper limit is not particularly limited, but is usually 50N/cm or less.

The adhesive composition of the present invention is suitable for use as an adhesive for flexible printed wiring board assembly. Examples of the adhesive for use in the connection of flexible printed wiring boards include: an adhesive composition for forming an adhesive layer constituting an adhesive film or a cover film having a copper foil.

2) Adhesive sheet

The adhesive sheet of the present invention is an adhesive sheet having an adhesive layer formed using the adhesive composition of the present invention.

The thickness of the adhesive layer is not particularly limited, and is usually 1 to 50μm, preferably 1 to 25μm, more preferably 5 to 25μAnd m is selected. The adhesive layer having a thickness within the above range is suitable for use as a material for forming a flexible printed wiring board-related product.

The thickness of the adhesive layer can be measured using a known thickness meter in accordance with JIS K7130 (1999).

The adhesive sheet of the present invention may have a base material in addition to the adhesive layer.

As the substrate, a resin film is generally available.

Examples of the resin component of the resin film include: polyimide, polyamide, polyamideimide, polyphenylene oxide, polyether ketone, polyether ether ketone, polyolefin, polyester, polycarbonate, polysulfone, polyether sulfone, polyphenylene sulfide, polyarylate, acrylic resin, cycloolefin polymer, aromatic polymer, polyurethane polymer, liquid crystal polymer film, and the like.

The thickness of the base material is not particularly limited, but is preferably 10 to 500μm, more preferably 10 to 300μm, more preferably 15 to 200μm。

The adhesive sheet of the present invention may have a release sheet in addition to the adhesive layer.

The release sheet functions as a protective sheet for the adhesive layer before the adhesive sheet is used. In the case where the adhesive sheet does not have a base material, the release sheet functions as a support in the production process of the adhesive sheet.

When the adhesive sheet of the present invention is used, the release sheet is usually peeled off and removed.

As the release sheet, a conventionally known release sheet can be used. Examples thereof include: a release sheet having a release layer subjected to a release treatment with a release agent on a release sheet base material.

Examples of the base material for the release sheet include: paper substrates such as cellophane, coated paper, high-quality paper, and the like; laminated paper obtained by laminating thermoplastic resin such as polyethylene on these paper substrates; and plastic films such as polyethylene terephthalate resins, polybutylene terephthalate resins, polyethylene naphthalate resins, polypropylene resins, and polyethylene resins.

Examples of the release agent include: silicone resins, olefin resins, isoprene resins, butadiene resins, and other rubber elastomers, long-chain alkyl resins, alkyd resins, fluorine resins, and the like.

The thickness of the release sheet is not particularly limited, but is usually 20 to 250μAnd m is about.

When the adhesive sheet of the present invention has a release sheet, the adhesive layer may have 1 release sheet and 2 release sheets in total on both sides of the adhesive layer, or may have a release sheet only on one side of the adhesive layer.

The method for producing the adhesive sheet is not particularly limited. For example, a casting method may be used to manufacture the adhesive sheet.

In the case of producing an adhesive sheet by a casting method, the adhesive composition of the present invention is applied to a substrate or a release-treated release layer surface of a release sheet by a known method, and the resulting coating film is dried, whereby an adhesive sheet can be produced.

Examples of the method of applying the adhesive composition include: spin coating, spray coating, bar coating, knife coating, roll coating, blade coating, die coating, gravure coating, and the like.

Examples of the method for drying the coating film include: conventionally known drying methods such as hot air drying, hot roll drying, and infrared ray irradiation.

The coating film is dried at 80 to 150 ℃ for 30 seconds to 5 minutes, for example.

When the adhesive layer is thermosetting, the adhesive layer is cured by heating the adhesive layer.

The conditions for thermally curing the adhesive layer are not particularly limited.

The heating temperature is usually 80 to 200 ℃ and preferably 90 to 150 ℃.

The heating time is usually 30 minutes to 12 hours, preferably 1 to 6 hours.

The cured product of the adhesive layer of the present invention has low dielectric characteristics in a high-frequency region and has excellent adhesive strength.

Therefore, the cured product of the adhesive layer of the present invention is preferably used as an adhesive cured layer constituting a flexible printed wiring board.

Examples

The present invention will be described in more detail below with reference to examples. However, the present invention is not limited to the following examples.

[ Compounds used in examples or comparative examples ]

Seeding modified polyolefin resin (a 1): acid modificationαOlefin polymers [ manufactured by mitsui chemical company, trade name: unistole H-200, number average molecular weight: 47,000]

Seed polyphenylene ether resin (B1): vinylbenzyl-modified polyphenylene ether [ product name, manufactured by mitsubishi GAS chemical corporation: OPE-2St 1200, number average molecular weight: 1200]

Seed polyphenylene ether resin (B2): vinylbenzyl-modified polyphenylene ether [ product name, manufactured by mitsubishi GAS chemical corporation: OPE-2St 2200, number average molecular weight: 2200]

Seeding of cyclic ether group-containing compound (C1): hydrogenated bisphenol a epoxy resin [ product name: YX8000, epoxy equivalent: 205g/eq, liquid at 25 ℃

Seeding of cyclic ether group-containing compound (C2): hydrogenated bisphenol a epoxy resin [ product name: YX8034, epoxy equivalent: 270g/eq liquid at 25%

Seeding and curing agent (D1): thermal cationic polymerization initiator [ trade name: San-Aid SI-B3

Seeding of silane coupling agent (E1): 8-glycidoxy octyltrimethoxysilane [ trade name: KBM 4803)

[ example 1]

An adhesive composition was prepared by dissolving 100 parts by mass of a modified polyolefin resin (a1), 50 parts by mass of a polyphenylene ether resin (B1), 3 parts by mass of a cyclic ether group-containing compound (C1), 0.15 parts by mass of a curing agent (D1), and 0.2 parts by mass of a silane coupling agent (E1) in toluene.

The adhesive composition was applied to the release-treated surface of a release sheet (No. 1 release sheet, product name: SP-PET752150 manufactured by Lintec Co., Ltd.), and the obtained coating film was dried at 100 ℃ for 2 minutes to give a coating film having a thickness of 15μm, an adhesive layer. A release-treated surface of another 1-piece release sheet (No. 2 release sheet, product name: SP-PET381130, manufactured by Lintec) was bonded to the adhesive layer to obtain an adhesive sheet.

Examples 2 to 16 and comparative example 1

Adhesive compositions and adhesive sheets were obtained in the same manner as in example 1, except that the kinds and amounts of the respective active ingredients constituting the adhesive compositions were changed to those shown in tables 1 and 2.

The following tests were performed on the adhesive sheets obtained in examples 1 to 16 and comparative example 1. The results are shown in tables 1 and 2.

[ specific dielectric constant, dielectric loss tangent ]

A plurality of the adhesive sheets obtained in examples and comparative examples were laminated by a thermal laminator heated to 100 ℃ so that the total thickness of the adhesive layers of the adhesive sheets was 1mm, to obtain a laminate having a structure of a release sheet/adhesive layer/release sheet with a thickness of 1 mm. The laminate was heated at 160 ℃ for 1 hour to cure the adhesive layer having a thickness of 1mm, and then the release sheets on both sides were peeled off to obtain a sample for measurement.

The specific dielectric constant and the dielectric loss tangent at 23 ℃ and 1GHz were measured with respect to the obtained measurement sample using an RF impedance/Material Analyzer (manufactured by Keysight, E4991A). In the examples or comparative examples, 1GHz was used as an example of the high frequency region.

[ adhesive Strength ]

A release sheet obtained by releasing 1 of the adhesive sheets obtained in examples or comparative examples. The exposed adhesive layer and the copper foil were bonded together at a temperature of 100 ℃ using a thermal laminator. Then, a sample obtained by bonding the copper foil and the adhesive layer with a release sheet was processed into 10mm × 100 mm.

Next, the remaining release sheet was peeled off, and the exposed adhesive layer and the polyimide film were bonded to each other at a temperature of 100 ℃ using a laminator, to obtain a laminate having a layer structure of copper foil/adhesive layer/polyimide film.

The laminate was thermally cured by hot pressing for 1 hour under conditions of 160 ℃ and 5MPa to obtain a sample for measurement.

The peel adhesion strength of the obtained measurement sample was measured under the conditions of a peel angle of 90 ℃ and a peel speed of 50 mm/min using a precision universal tester (product name: Autograph AG-IS, manufactured by Shimadzu corporation). The peeling test was performed by peeling the copper foil while stretching the copper foil in a direction of 90 ° with respect to the sample for measurement.

[ Table 1]

[ Table 2]

The following results are shown in tables 1 and 2.

The cured products of the adhesive compositions obtained in examples 1 to 16 had low dielectric properties in a high frequency range and sufficient adhesive strength.

In particular, the cured products of the adhesive compositions obtained in examples 1 to 16 had low dielectric loss tangent, and thus the wiring members for high-frequency signal transmission formed using the adhesive compositions obtained in examples 1 to 16 had low transmission loss.

Claims

1. An adhesive composition comprising the following components (A) and (B):

(A) the components: a modified polyolefin resin;

(B) the components: polyphenylene ether resins having reactive groups.

2. The adhesive composition according to claim 1, wherein the content of the modified polyolefin resin is more than 50% by mass in the total amount of the active ingredients of the adhesive composition.

3. The adhesive composition according to claim 1 or 2, wherein the reactive group of the polyphenylene ether resin having a reactive group is a group having an ethylenically unsaturated bond.

4. The adhesive composition according to any one of claims 1 to 3, further comprising the following component (C),

5. The adhesive composition according to claim 4, wherein the content of the compound having an alicyclic skeleton and a cyclic ether group is 10% by mass or less in the total amount of the active ingredients of the adhesive composition.

6. The adhesive composition according to claim 4 or 5, wherein at least 1 of the compounds having an alicyclic skeleton and a cyclic ether group is a compound that is liquid at 25 ℃, and the content of the compound having an alicyclic skeleton and a cyclic ether group that is liquid at 25 ℃ is 10% by mass or less of the total amount of the active ingredients of the adhesive composition.

7. The adhesive composition according to any one of claims 1 to 6, further comprising a component (D),

(D) the components: and (3) a curing agent.

8. The adhesive composition of claim 7, wherein the curing agent comprises a cationic polymerization initiator.

9. The adhesive composition according to any one of claims 1 to 8, further comprising a component (E),

(E) the components: a silane coupling agent.

10. An adhesive sheet comprising an adhesive layer formed using the adhesive composition according to any one of claims 1 to 9.