JP7434727B2 - Adhesive compositions, laminates and adhesive sheets - Google Patents

Description

The present invention relates to an adhesive composition, a laminate, and an adhesive sheet. More specifically, the present invention relates to an adhesive composition used for adhering a resin base material and a resin base material or a metal base material, and in particular, an adhesive composition having low dielectric properties such as a liquid crystal polymer (hereinafter abbreviated as "LCP"). The present invention relates to an adhesive composition used for adhesion to a base material.

In recent years, as the speed of transmission signals in printed wiring boards has increased, the frequency of signals has been increasing. Along with this, there is an increasing demand for flexible printed wiring boards (hereinafter abbreviated as "FPC") to have low dielectric properties (low dielectric constant, low dielectric loss tangent) in a high frequency region. In response to these demands, LCP, syndiotactic polystyrene (SPS), and polyphenylene sulfide (PPS), which have low dielectric properties, are being used as base films for FPCs instead of conventional polyimide (PI) and polyethylene terephthalate films. ) and other base films have been proposed.

However, since base films with low dielectric properties have low polarity, when conventional epoxy adhesives or acrylic adhesives are used, the adhesive strength is weak, resulting in poor adhesive strength for FPC members such as coverlay films and laminates. It was difficult to manufacture. Furthermore, epoxy adhesives and acrylic adhesives have a problem of not being excellent in low dielectric properties and impairing the dielectric properties of FPC.

On the other hand, polyolefin resins are known to have low dielectric properties. Therefore, an adhesive composition for FPC using a polyolefin resin has been proposed. For example, Patent Document 1 proposes a modified polyamide adhesive composition into which an olefin skeleton is introduced in order to improve the electrical properties of FPC. Further, Patent Document 2 proposes an adhesive and a coverlay for a flexible printed wiring board using an aromatic olefin oligomer type modifier and an epoxy resin.

Japanese Patent Application Publication No. 2007-284515 Japanese Patent Application Publication No. 2007-63306

However, the adhesive compositions described in Patent Documents 1 and 2 have a problem in that although they can obtain adhesive properties with polyimide films, it is difficult to obtain adhesive properties with base films having low dielectric properties such as LCP. be. Furthermore, the adhesive compositions described in Patent Documents 1 and 2 have a problem of poor dielectric properties.

Furthermore, when using an LCP base material, there is a method of melting the LCP without using an adhesive and bonding it with copper foil to produce a two-layer board. However, this method has problems in that it requires a device or machine for bonding at high temperatures, tends to wrinkle during processing, and reduces yield.

The present invention was made in view of the above-mentioned problems of the prior art, and provides an adhesive composition that has good adhesion to substrates such as LCP and has excellent low dielectric properties, and an adhesive composition using the same. The purpose of the present invention is to provide a laminate and an adhesive sheet.

As a result of intensive studies to solve the above problems, the inventors of the present invention have developed a method that contains a specific bismaleimide resin having a structure derived from dimer acid, and also contains an epoxy resin and an active ester curing agent. We have discovered that an adhesive composition containing a curing accelerator with a specific structure exhibits excellent low dielectric properties and has high adhesion to resin base materials with low dielectric properties such as LCP. The invention was completed.

［式（１）中、Ｒ^１はダイマー酸に由来する２価の炭化水素基を示し、Ｑは置換又は非置換の炭素数１～１００の脂肪族基、置換又は非置換の芳香族基、或いは、置換又は非置換のヘテロ芳香族基を示し、ｎは０～１００の整数を示す。］
［２］上記（Ｂ）成分の含有量が、上記（Ａ）成分、上記（Ｂ）成分及び上記（Ｃ）成分の総量を１００質量部として２．０～３０．０質量部である、上記［１］に記載の接着剤組成物。
［３］上記（Ｃ）成分の含有量が、上記（Ａ）成分、上記（Ｂ）成分及び上記（Ｃ）成分の総量を１００質量部として２．０～３５．０質量部である、上記［１］又は［２］に記載の接着剤組成物。
［４］上記（Ｄ）成分の含有量が、上記（Ａ）成分、上記（Ｂ）成分及び上記（Ｃ）成分の総量１００質量部に対して０．１～５．０質量部である、上記［１］～［３］のいずれかに記載の接着剤組成物。
［５］樹脂基材と、樹脂基材又は金属基材との接着に用いられる、上記［１］～［４］のいずれかに記載の接着剤組成物。
［６］基材と、該基材上に上記［１］～［５］のいずれかに記載の接着剤組成物を用いて形成された接着剤層と、を備える積層体。
［７］上記［１］～［５］のいずれかに記載の接着剤組成物によって接着された、樹脂基材と、樹脂基材又は金属基材とを備える積層体。
［８］上記［６］又は［７］に記載の積層体を備える接着シート。 That is, the present invention provides the following inventions.
[1] Contains (A) a bismaleimide resin represented by the following general formula (1), (B) an epoxy resin, (C) an active ester curing agent, and (D) a curing accelerator, An adhesive composition in which the component (D) contains at least one selected from the group consisting of imidazole compounds, amine compounds, and peroxide compounds.

[In formula (1), R ¹ represents a divalent hydrocarbon group derived from a dimer acid, Q is a substituted or unsubstituted aliphatic group having 1 to 100 carbon atoms, a substituted or unsubstituted aromatic group, Alternatively, it represents a substituted or unsubstituted heteroaromatic group, and n represents an integer of 0 to 100. ]
[2] The content of component (B) is 2.0 to 30.0 parts by mass based on 100 parts by mass of the total amount of component (A), component (B), and component (C). The adhesive composition according to [1].
[3] The content of the component (C) is 2.0 to 35.0 parts by mass based on 100 parts by mass of the total amount of the component (A), the component (B), and the component (C). The adhesive composition according to [1] or [2].
[4] The content of the component (D) is 0.1 to 5.0 parts by mass based on 100 parts by mass of the total amount of the component (A), the component (B), and the component (C). The adhesive composition according to any one of [1] to [3] above.
[5] The adhesive composition according to any one of [1] to [4] above, which is used for bonding a resin base material and a resin base material or a metal base material.
[6] A laminate comprising a base material and an adhesive layer formed on the base material using the adhesive composition according to any one of [1] to [5] above.
[7] A laminate comprising a resin base material and a resin base material or a metal base material adhered by the adhesive composition according to any one of [1] to [5] above.
[8] An adhesive sheet comprising the laminate according to [6] or [7] above.

According to the present invention, it is possible to provide an adhesive composition that has good adhesion to a base material such as LCP and also has excellent low dielectric properties, and a laminate and adhesive sheet using the same.

Hereinafter, the present invention will be explained in detail based on its preferred embodiments.

[Adhesive composition]
The adhesive composition of the present embodiment includes (A) a bismaleimide resin represented by general formula (1) (hereinafter also referred to as "(A) component"), and (B) an epoxy resin (hereinafter referred to as "(B) component"). ), (C) an active ester curing agent (hereinafter also referred to as "(C) component"), and (D) a curing accelerator (hereinafter also referred to as "(D) component"). contains. Furthermore, in the adhesive composition of the present embodiment, the component (D) includes at least one type of curing accelerator selected from the group consisting of imidazole compounds, amine compounds, and peroxide compounds. Furthermore, the adhesive composition of this embodiment may contain (E) an organic solvent (hereinafter also referred to as "component (E)").

<(A) Component: Bismaleimide resin>
(A) Bismaleimide resin is a compound represented by the following general formula (1), and is produced by reacting dimer diamine, which is a diamine derived from dimer acid, tetracarboxylic dianhydride, and maleic anhydride. Obtainable.

式（１）中、Ｒ^１はダイマー酸に由来する２価の炭化水素基を示し、Ｑは置換又は非置換の炭素数１～１００の脂肪族基、置換又は非置換の芳香族基、或いは、置換又は非置換のヘテロ芳香族基を示し、ｎは０～１００の整数を示す。式（１）中のＱは、ＬＣＰ等の低誘電特性を有する樹脂基材に対するより優れた接着性、及び、より優れた低誘電特性を得る観点から、非置換の芳香族基であることが好ましい。また、式（１）中のｎは、ＬＣＰ等の低誘電特性を有する樹脂基材に対するより優れた接着性、及び、より優れた低誘電特性を得る観点から、５～３０の整数であることが好ましい。

In formula (1), R ¹ represents a divalent hydrocarbon group derived from dimer acid, and Q represents a substituted or unsubstituted aliphatic group having 1 to 100 carbon atoms, a substituted or unsubstituted aromatic group, or , represents a substituted or unsubstituted heteroaromatic group, and n represents an integer of 0 to 100. Q in formula (1) is preferably an unsubstituted aromatic group from the viewpoint of obtaining better adhesion to a resin base material having low dielectric properties such as LCP and better low dielectric properties. preferable. Further, n in formula (1) should be an integer of 5 to 30 from the viewpoint of obtaining better adhesion to a resin base material having low dielectric properties such as LCP and better low dielectric properties. is preferred.

Dimer diamine is a compound derived from dimer acid, which is a dimer of unsaturated fatty acids such as oleic acid, as described in, for example, JP-A-9-12712. In the present embodiment, known dimer diamines can be used without particular limitation, but those represented by the following general formula (3) and/or general formula (4) are preferred, for example.

In formulas (3) and (4), p, q, r and s each represent an integer of 1 or more selected so that p+q=6 to 17 and r+s=8 to 19, and are integers of 1 to 12. There may be. Furthermore, in formulas (3) and (4), the bond shown by a broken line means a carbon-carbon single bond or a carbon-carbon double bond. However, when the bond shown by the broken line is a carbon-carbon double bond, formulas (3) and (4) calculate the number of hydrogen atoms bonded to each carbon atom constituting the carbon-carbon double bond using the formula The structure is obtained by subtracting one from the numbers shown in (3) and (4).

The dimer diamine is used to improve the organic solvent solubility of the resulting bismaleimide resin, as well as the heat resistance, heat-resistant adhesion, and low viscosity of the adhesive composition when the bismaleimide resin is used as a material for the adhesive composition. From this point of view, compounds represented by the above general formula (4) are preferred, and compounds represented by the following formula (4-1) are particularly preferred.

Examples of commercially available dimer diamines include PRIAMINE 1075 and PRIAMINE 1074 (both manufactured by Croda Japan Co., Ltd.).

Examples of the tetracarboxylic dianhydride include pyromellitic anhydride; 1,2,3,4-cyclobutanetetracarboxylic dianhydride; 1,4,5,8-naphthalenetetracarboxylic dianhydride; 3, 4,9,10-perylenetetracarboxylic dianhydride; bicyclo(2.2.2)oct-7-ene-2,3,5,6-tetracarboxylic dianhydride; diethylenetriaminepentaacetic dianhydride; Ethylenediaminetetraacetic dianhydride; 3,3',4,4'-benzophenonetetracarboxylic dianhydride; 3,3',4,4'-biphenyltetracarboxylic dianhydride; 4,4'-oxydianhydride Phthalix anhydride; 3,3',4,4'-diphenylsulfonetetracarboxylic dianhydride; 2,2'-bis(3,4-dicarboxyphenyl)hexafluoropropane dianhydride; 4,4' -Bisphenol A Diphthalic anhydride; 5-(2,5-dioxytetrahydro)-3-methyl-3-cyclohexene-1,2-dicarboxylic anhydride; Ethylene glycol bis(trimellitic anhydride); Hydroquinone diphthal Acid anhydride; allyl nadic anhydride; 2-octen-1-ylsuccinic anhydride; 1,2,3,6-tetrahydrophthalic anhydride; 3,4,5,6-tetrahydro Examples include phthalic anhydride. Among these, pyromellitic anhydride is preferred from the viewpoint of heat resistance. These can be used alone or in combination of two or more.

(A) The weight average molecular weight of the bismaleimide resin is preferably 3,000 to 70,000 from the viewpoint of obtaining better adhesion to resin substrates having low dielectric properties such as LCP and better low dielectric properties. It is preferably from 5,000 to 50,000, even more preferably from 7,000 to 30,000.

(A) A commercially available compound can also be used as the bismaleimide resin, and specifically, for example, DESIGNER MOLECURES Inc. BMI-3000 (synthesized from dimer diamine, pyromellitic dianhydride, and maleic anhydride), BMI-1500, BMI-1700, BMI-5000, and the like manufactured by the company can be suitably used.

<(B) component: epoxy resin>
(B) Epoxy resins are not particularly limited, but from the viewpoint of adhesion to base materials such as LCP, epoxy resins having a bisphenol A skeleton, epoxy resins having a bisphenol F skeleton, polyfunctional epoxy resins having a novolac skeleton, Biphenyl type epoxy resin etc. are preferred.

Examples of the epoxy resin having a bisphenol A skeleton and the epoxy resin having a bisphenol F skeleton include compounds represented by the following general formula (2). The epoxy resin having a bisphenol A skeleton and the epoxy resin having a bisphenol F skeleton must be an epoxy resin represented by the following general formula (2-1) from the viewpoint of obtaining better adhesion to a base material such as LCP. is preferred.

式（２）及び式（２－１）中、Ｒ^２は水素原子又はメチル基を示し、Ｒ^３は２価の有機基を示し、ｍは０～３０の整数を示す。式（２）及び式（２－１）中のｍは、ＬＣＰ等の低誘電特性を有する樹脂基材に対するより優れた接着性、及び、より優れた低誘電特性を得る観点から、０～１０の整数であることが好ましい。式（２）のＲ^３としては、置換又は非置換のアルキレン基、置換又は非置換のアルキレンオキシド基、置換又は非置換の芳香族基等が挙げられる。Ｒ^３が置換又は非置換のアルキレン基、或いは、置換又は非置換のアルキレンオキシド基である場合、エポキシ樹脂に低弾性を付与することができる。

In formula (2) and formula (2-1), R ² represents a hydrogen atom or a methyl group, R ³ represents a divalent organic group, and m represents an integer of 0 to 30. m in formula (2) and formula (2-1) is 0 to 10 from the viewpoint of obtaining better adhesion to a resin base material having low dielectric properties such as LCP and better low dielectric properties. is preferably an integer of . Examples of R ³ in formula (2) include a substituted or unsubstituted alkylene group, a substituted or unsubstituted alkylene oxide group, and a substituted or unsubstituted aromatic group. When R ³ is a substituted or unsubstituted alkylene group or a substituted or unsubstituted alkylene oxide group, low elasticity can be imparted to the epoxy resin.

Examples of the polyfunctional epoxy resin having a novolak skeleton include compounds having a structural unit represented by the following general formula (5) or (6), such as novolac-type epoxy resin, naphthalene skeleton-modified novolac-type epoxy resin, biphenyl novolak. Type epoxy resins, cresol novolac type epoxy resins, and the like. The number of epoxy groups in the polyfunctional epoxy resin having a novolak skeleton is preferably 3 or more, more preferably 5 or more. From the viewpoint of low dielectric properties, A in the following general formula (5) is preferably an unsubstituted aromatic group such as a naphthalene skeleton or a biphenyl skeleton.

式（５）及び式（６）中、Ｒ^４は水素原子又はメチル基を示し、Ａは置換又は非置換の炭素数１～３０の脂肪族基、置換又は非置換の芳香族基、或いは、置換又は非置換のヘテロ芳香族基を有する２価の有機基を示し、ｘ及びｙは各々独立に１以上の整数を示す。ｘが２以上である場合、複数存在するＲ^４は同一でも異なっていてもよい。ｙが２以上である場合、複数存在するＡは同一でも異なっていてもよい。

In formulas (5) and (6), R ⁴ represents a hydrogen atom or a methyl group, and A is a substituted or unsubstituted aliphatic group having 1 to 30 carbon atoms, a substituted or unsubstituted aromatic group, or It represents a divalent organic group having a substituted or unsubstituted heteroaromatic group, and x and y each independently represent an integer of 1 or more. When x is 2 or more, a plurality of R ^4s may be the same or different. When y is 2 or more, multiple A's may be the same or different.

The biphenyl-type epoxy resin is not particularly limited as long as it has a biphenyl skeleton, but for example, an epoxy resin represented by the following general formula (7) is preferable.

In formula (7), R ⁸ represents a hydrogen atom, an alkyl group having 1 to 12 carbon atoms, or an aromatic group having 4 to 18 carbon atoms, each of which may be the same or different, and t is an average value. , indicates a number from 0 to 10. From the viewpoint of compatibility with component (A), the value of t is preferably 3 or less, more preferably 1 or less.

The content of the epoxy resin (B) is preferably 2.0 to 30.0 parts by mass, based on the total amount of components (A), (B), and (C) being 100 parts by mass. The amount is more preferably 0 to 15.0 parts by weight, and particularly preferably 5.0 to 10.0 parts by weight. When the content of component (B) is 2.0 parts by mass or more, better adhesive strength with the LCP base material tends to be obtained, and when it is 30.0 parts by mass or less, better adhesive strength with the LCP base material is easily obtained. There is a tendency for dielectric properties to be easily obtained.

<Component (C): Active ester curing agent>
(C) The active ester curing agent itself is a compound that participates in the curing reaction, and by using it, it is possible to obtain the effect of lowering the dielectric properties.

The active ester curing agent is not particularly limited, but from the viewpoint of obtaining the effect of lower dielectric properties more fully, phenol esters, thiophenol esters, N-hydroxyamine esters, esters of heterocyclic hydroxy compounds, etc. A compound having one or more ester groups with high reaction activity in one molecule is preferably used. More specific examples of active ester curing agents include "EPICLON HPC8000-65T," "EPICLON HPC8000-L-65MT," and "EPICLON HPC8150-60T" (all product names manufactured by DIC Corporation). It will be done. These can be used alone or in combination of two or more.

It is thought that the active ester curing agent reacts with the epoxy resin (B) as shown in the following formula (I) during the curing reaction. Hydroxyl groups are not generated in the reaction between the active ester curing agent (C) and the epoxy resin (B), and even if a side reaction occurs, hydroxyl groups are difficult to generate, resulting in poor dielectric properties. It is believed that this can be achieved.

式中、Ｒ^１１、Ｒ^１２及びＲ^１３はそれぞれ独立に、１価の有機基を示すが、本発明の効果がより十分に得られることから、芳香環を有する１価の有機基であってもよい。

In the formula, R ¹¹ , R ¹² and R ¹³ each independently represent a monovalent organic group, but since the effects of the present invention can be more fully obtained, R 11 , R 12 and R 13 each independently represent a monovalent organic group having an aromatic ring. Good too.

The content of the active ester curing agent (C) is preferably 2.0 to 35.0 parts by mass, based on the total amount of components (A), (B), and (C) being 100 parts by mass. , more preferably 3.0 to 20.0 parts by weight, particularly preferably 5.0 to 15.0 parts by weight. When the content of component (C) is 2.0 parts by mass or more, better low dielectric properties tend to be obtained, and when the content is 35.0 parts by mass or less, better properties with the LCP base material tend to be obtained. There is a tendency for adhesive strength to be easily obtained.

<(D) Component: Curing accelerator>
(D) The curing accelerator includes at least one selected from the group consisting of imidazole compounds, amine compounds, and peroxide compounds. (D) The curing accelerator may consist only of the above-mentioned specific curing accelerator, or may further contain other curing accelerators other than the above-mentioned specific curing accelerator.

Examples of imidazole compounds include 1-(2-cyanoethyl)-2-phenylimidazole, 1,2-dimethylimidazole, 2-ethyl-4-methylimidazole, 2-methylimidazole, 2-ethylimidazole, 2,4 -Dimethylimidazole, 2-undecylimidazole, 2-heptadecylimidazole, 2-phenylimidazole, 2-phenyl-4-methylimidazole, 1-benzyl-2-methylimidazole, 2-phenyl-4,5-dihydroxymethylimidazole , 2-phenyl-4-methyl-5-hydroxymethylimidazole, 1-vinyl-2-methylimidazole, 1-propyl-2-methylimidazole, 2-isopropylimidazole, 1-cyanomethyl-2-methyl-imidazole, 1- Examples include cyanoethyl-2-ethyl-4-methylimidazole, 1-cyanoethyl-2-undecylimidazole, and 1-cyanoethyl-2-phenylimidazole. Among these, imidazole compounds include 1-(2-cyanoethyl)-2-phenylimidazole, 1,2-dimethylimidazole, 2-methylimidazole, 2-phenylimidazole, 2-undecylimidazole, and 2-ethyl -4-methylimidazole is preferred. Use of these compounds provides the advantage that the reaction of the bismaleimide resin (A) is further promoted and the heat resistance of the resulting cured product is improved. In addition, as imidazole compounds, 1-(2-cyanoethyl)-2-phenylimidazole and 1,2-dimethyl Imidazole is preferred, and 1-(2-cyanoethyl)-2-phenylimidazole is more preferred. These can be used alone or in combination of two or more.

Examples of amine compounds include triethylamine, dimethylbenzylamine, triethylenediamine, tripropylamine, tributylamine, dimethylethanolamine, triethanolamine, 4-aminopyridine, 2-aminopyridine, N,N-dimethyl-4- Examples include aminopyridine, 4-diethylaminopyridine, 2-hydroxypyridine, 2-methoxypyridine, and 4-methoxypyridine.

Peroxide compounds include dicumyl peroxide, diisopropylbenzene hydroperoxide, t-butylcumyl peroxide, benzoyl peroxide, dilauryl peroxide, cumene hydroperoxide, t-butyl hydroperoxide, 1,1 -Bis(t-butylperoxy)-3,5,5-trimethylcyclohexane, 1,1-bis(t-butylperoxy)-cyclohexane, cyclohexanone peroxide, t-butylperoxybenzoate, t-butylperoxy Examples include isobutyrate, t-butylperoxy-3,5,5-trimethylhexanoate, t-butylperoxy-2-ethylhexanoate, cumylperoxyoctoate and the like.

Other curing accelerators other than the above-mentioned specific curing accelerators include phosphorus curing accelerators. Examples of the phosphorus curing accelerator include phosphine compounds such as primary phosphines such as alkylphosphine and phenylphosphine, secondary phosphines such as dialkylphosphine and diphenylphosphine, and tertiary phosphines such as trialkylphosphine and triphenylphosphine. , and phosphonium salt compounds.

The adhesive composition of the present embodiment may contain the above-mentioned phosphorus-based curing accelerator, but the content is preferably small and does not need to contain the phosphorus-based curing accelerator. The present inventors have found that when a phosphorus-based curing accelerator and (C) an active ester-based curing agent are used together, the adhesiveness to a substrate such as LCP may be reduced. The present inventors speculate as follows about the reason. That is, in order to improve adhesion, (B) epoxy resin and (C) active ester curing agent, which contribute to adhesion, react with (A) bismaleimide resin, which is the base resin, and are incorporated into the main chain. It is considered necessary. The reactivity of each component varies depending on the type of curing accelerator, and when a phosphorus curing accelerator is used, (B) epoxy resin and (C) active ester curing agent, (A) bismaleimide resin It is thought that it is difficult to incorporate into the main chain and it is difficult to improve adhesiveness. On the other hand, when at least one type of curing accelerator selected from the group consisting of imidazole compounds, amine compounds, and peroxide compounds is used, (B) epoxy resin and (C) active ester curing It is considered that the agent is likely to be incorporated into the main chain of the bismaleimide resin (A), and the adhesiveness is likely to be improved.

(D) At least one curing accelerator selected from the group consisting of imidazole compounds, amine compounds, and peroxide compounds in the curing accelerator, since the adhesion to substrates such as LCP is more likely to be improved. The content of (D) is preferably 80 to 100% by mass, more preferably 90 to 100% by mass, and even more preferably 95 to 100% by mass, based on the total amount of the curing accelerator (D). .

In addition, since the adhesion to substrates such as LCP is more likely to be improved, the content of the phosphorus-based curing accelerator in the curing accelerator (D) should be 0 to 20% based on the total amount of the curing accelerator (D). It is preferably 0 to 10% by weight, even more preferably 0 to 5% by weight.

(D) The content of the curing accelerator is not particularly limited, but from the viewpoint of further improving the adhesion to the base material such as LCP and the heat resistance of the obtained cured product, the bismaleimide resin of the component (A) The amount is preferably 0.1 to 5.0 parts by weight, preferably 1.0 to 3.0 parts by weight, based on 100 parts by weight of the total amount of the epoxy resin (B) and the active ester curing agent (C). It is more preferable that

<(E) component: organic solvent>
The adhesive composition of this embodiment can further contain (E) an organic solvent. The organic solvent used in this embodiment is not particularly limited as long as it dissolves (A) bismaleimide resin, (B) epoxy resin, (C) active ester curing agent, and (D) curing accelerator. (E) Specific examples of organic solvents include aromatic hydrocarbons such as benzene, toluene, xylene, and mesitylene; aliphatic hydrocarbons such as hexane, heptane, octane, and decane; cyclohexane, cyclohexene, methylcyclohexane, and ethylcyclo Alicyclic hydrocarbons such as hexane; halogenated hydrocarbons such as trichlorethylene, dichloroethylene, chlorobenzene, and chloroform; alcohols such as methanol, ethanol, isopropyl alcohol, butanol, pentanol, hexanol, propanediol, and phenol Solvents; ketone solvents such as acetone, methyl isobutyl ketone, methyl ethyl ketone, pentanone, hexanone, cyclohexanone, isophorone, acetophenone; cellosolves such as methyl cellosolve, ethyl cellosolve; methyl acetate, ethyl acetate, butyl acetate, methyl propionate, Ester solvents such as butyl formate; ethylene glycol mono-n-butyl ether, ethylene glycol mono-iso-butyl ether, ethylene glycol mono-tert-butyl ether, diethylene glycol mono-n-butyl ether, diethylene glycol mono-iso-butyl ether, triethylene glycol mono-n-butyl ether, tetra Glycol ether solvents such as ethylene glycol mono-n-butyl ether can be used. These can be used alone or in combination of two or more. In a preferred embodiment, aromatic hydrocarbons are used, and among them, toluene or xylene is preferably used.

The adhesive composition of this embodiment is prepared according to a generally employed method. Examples of the preparation method include methods such as melt mixing, powder mixing, and solution mixing. In addition, in this case, ingredients other than the essential components of this embodiment, such as inorganic fillers, mold release agents, flame retardants, ion trapping agents, antioxidants, adhesion promoters, low stress agents, coloring agents, coupling agents, etc. Agents and the like may be added within a range that does not impair the effects of the present invention.

<Inorganic filler>
The inorganic filler is added to reduce the coefficient of thermal expansion and improve moisture resistance reliability of the adhesive composition.
Examples of the inorganic filler include silicas such as fused silica, crystalline silica, and cristobalite, alumina, silicon nitride, aluminum nitride, boron nitride, titanium oxide, glass fiber, and magnesium oxide. The average particle size and shape of these inorganic fillers can be selected depending on the application. Among them, spherical alumina, spherical fused silica, glass fiber, etc. are preferable.

<Release agent>
A mold release agent is added to improve mold releasability from a mold. Examples of the mold release agent include carnauba wax, rice wax, candelilla wax, polyethylene, polyethylene oxide, polypropylene, montanic acid, montanic acid and saturated alcohol, 2-(2-hydroxyethylamino)ethanol, ethylene glycol, and glycerin. All known ester compounds such as montan wax, stearic acid, stearic ester, and stearic acid amide can be used.

<Flame retardant>
Flame retardants are added to impart flame retardancy. All known flame retardants can be used and are not particularly limited. Examples of the flame retardant include phosphazene compounds, silicone compounds, talc supported on zinc molybdate, zinc oxide supported on zinc molybdate, aluminum hydroxide, magnesium hydroxide, molybdenum oxide, and the like.

<Ion trapping agent>
The ion trap agent is added to trap ionic impurities contained in the liquid adhesive composition and prevent thermal deterioration and moisture absorption deterioration. All known ion trapping agents can be used and are not particularly limited. Examples of the ion trapping agent include hydrotalcites, bismuth hydroxide compounds, and rare earth oxides.

[Laminated body]
The laminate of this embodiment is one in which an adhesive composition is laminated on a base material (two-layer laminate of base material/adhesive layer), or one in which a base material is further laminated (base material/adhesive layer). /3-layer laminate of base material). Here, the adhesive layer refers to a layer of the adhesive composition after applying the adhesive composition of the present embodiment to a base material and drying it. The laminate of this embodiment can be obtained by applying the adhesive composition of this embodiment to various base materials, drying, and further laminating other base materials in accordance with a conventional method.

<Base material>
In this embodiment, the base material is not particularly limited as long as it can form an adhesive layer by coating and drying the adhesive composition of this embodiment, but it is a resin base material such as a film-like resin. , metal substrates such as metal plates and metal foils, and papers.

Examples of the material of the resin base material include polyester resin, polyamide resin, polyimide resin, polyamideimide resin, liquid crystal polymer, polyphenylene sulfide, syndiotactic polystyrene, polyolefin resin, and fluorine resin. Preferably, the resin base material is a film-like resin (hereinafter also referred to as "base film layer").

As the metal base material, any conventionally known conductive material that can be used for circuit boards can be used. Examples of materials include various metals such as SUS, copper, aluminum, iron, steel, zinc, and nickel, as well as their alloys, plated products, and metals treated with other metals such as zinc or chromium compounds. . The metal base material is preferably a metal foil, more preferably a copper foil. The thickness of the metal foil is not particularly limited, but is preferably 1 μm or more, more preferably 3 μm or more, and even more preferably 10 μm or more. Further, the thickness of the metal foil is preferably 50 μm or less, more preferably 30 μm or less, and still more preferably 20 μm or less. If the thickness is too thin, it may be difficult to obtain sufficient electrical performance of the circuit. On the other hand, if the thickness is too thick, processing efficiency during circuit production may be reduced. Metal foil is usually provided in the form of a roll, but there are no particular limitations on the form of the metal foil used when manufacturing a printed wiring board as described below. When using a ribbon-shaped metal foil, its length is not particularly limited. Furthermore, the width is not particularly limited, but it is preferably about 250 to 500 cm.

Examples of paper include high-quality paper, kraft paper, roll paper, glassine paper, and the like. Moreover, glass epoxy etc. can be illustrated as a composite material.

From the viewpoint of adhesive strength and durability with the adhesive composition, the base material may include polyester resin, polyamide resin, polyimide resin, polyamideimide resin, liquid crystal polymer, polyphenylene sulfide, syndiotactic polystyrene, polyolefin resin, Fluororesin, SUS steel plate, copper foil, aluminum foil, or glass epoxy is preferred.

<Adhesive sheet>
The adhesive sheet of this embodiment includes the above-mentioned laminate, and is, for example, one in which the above-mentioned laminate and a release base material are laminated with an adhesive composition interposed therebetween. Specific structural aspects include laminate (base material/adhesive layer)/mold release base material, laminate (base material/adhesive layer/base material)/adhesive layer/mold release base material, or mold release Examples include base material/adhesive layer/laminate (base material/adhesive layer/base material)/adhesive layer/release base material. By laminating the release base material, it functions as a protective layer for the adhesive layer that constitutes the adhesive sheet. Further, by using a release base material, it is possible to release the release base material from the adhesive sheet and further transfer the adhesive layer to another base material.

The adhesive sheet of this embodiment can be obtained by applying the adhesive composition of this embodiment to various laminates and drying it according to a conventional method. In addition, by attaching a release base material to the adhesive layer after drying, it becomes possible to wind up the laminate without causing set-off to the base material that makes up the laminate. Since it is protected, it has excellent storage stability and is easy to use.
Further, by applying an adhesive composition to a release base material, drying it, and then attaching another release base material as necessary, it becomes possible to transfer the adhesive layer itself to another base material.

<Release base material>
The release base material is not particularly limited, but for example, paper such as high-quality paper, kraft paper, roll paper, glassine paper, etc., with a coating layer of a filler such as clay, polyethylene, or polypropylene on both sides. Examples include those in which a silicone-based, fluorine-based, or alkyd-based mold release agent is applied on each coating layer. Also included are various olefin films alone such as polyethylene, polypropylene, ethylene-α-olefin copolymer, propylene-α-olefin copolymer, and films made of polyethylene terephthalate and the like coated with the above mold release agent. For reasons such as the release force between the release base material and the adhesive layer and the adverse effects of silicone on electrical properties, we use high-quality paper with a polypropylene filling treatment on both sides and then use an alkyd release agent on top of that. Alternatively, it is preferable to use an alkyd mold release agent on polyethylene terephthalate.

In this embodiment, the method for coating the adhesive composition on the base material is not particularly limited, but examples include a comma coater, a reverse roll coater, and the like. Alternatively, if necessary, an adhesive layer can be provided directly or by a transfer method on the rolled copper foil or polyimide film that is the constituent material of the printed wiring board. The thickness of the adhesive layer after drying may be changed as necessary, but is preferably in the range of 5 to 200 μm. If the thickness of the adhesive layer is less than 5 μm, the adhesive strength may be insufficient. If the thickness is 200 μm or more, drying may be insufficient and a large amount of residual solvent may be present, which poses a problem that blisters may occur during pressing for manufacturing printed wiring boards. The drying conditions are not particularly limited, but the residual solvent rate after drying is preferably 1% by mass or less. If it exceeds 1% by mass, there is a problem in that the residual solvent foams during pressing in the production of printed wiring boards, which tends to cause blisters.

<Printed wiring board>
The printed wiring board in this embodiment includes, as a component, a laminate formed from metal foil and a resin base material forming a conductor circuit. The printed wiring board can be manufactured, for example, using a metal-clad laminate by a conventionally known method such as a subtractive method. The printed wiring board in this embodiment is a so-called flexible circuit board (FPC) in which a conductor circuit formed of metal foil is partially or entirely covered with a cover film or screen printing ink as necessary. , flat cables, circuit boards for tape automated bonding (TAB), etc.

The printed wiring board of this embodiment can have any laminated structure that can be adopted as a printed wiring board. For example, it can be a printed wiring board composed of four layers: a base film layer, a metal foil layer, an adhesive layer, and a cover film layer. Further, for example, a printed wiring board can be made up of five layers: a base film layer, an adhesive layer, a metal foil layer, an adhesive layer, and a cover film layer.

Furthermore, if necessary, it is also possible to have a structure in which two or three or more of the above printed wiring boards are laminated.

The adhesive composition of this embodiment can be suitably used for each adhesive layer of a printed wiring board. In particular, when the adhesive composition of this embodiment is used as an adhesive, it has high adhesion not only to conventional polyimide, polyester film, and copper foil that constitute printed wiring boards, but also to low polarity resin base materials such as LCP. However, it is possible to obtain solder reflow resistance, and the adhesive layer itself has excellent low dielectric properties. Therefore, it is suitable as an adhesive composition for use in coverlay films, laminates, resin-coated copper foils, and bonding sheets.

In the printed wiring board of this embodiment, any resin film conventionally used as a base material for printed wiring boards can be used as the base film. Examples of the resin for the base film include polyester resin, polyamide resin, polyimide resin, polyamideimide resin, liquid crystal polymer, polyphenylene sulfide, syndiotactic polystyrene, polyolefin resin, and fluorine resin. The adhesive composition of this embodiment has excellent adhesion particularly to low polar base materials such as liquid crystal polymer, polyphenylene sulfide, syndiotactic polystyrene, and polyolefin resin.

<Cover film>
As the cover film, any insulating film conventionally known as an insulating film for printed wiring boards can be used. For example, manufactured from various polymers such as polyimide, polyester, polyphenylene sulfide, polyether sulfone, polyether ether ketone, aramid, polycarbonate, polyarylate, polyimide, polyamideimide, liquid crystal polymer, polyphenylene sulfide, syndiotactic polystyrene, polyolefin resin, etc. film is available. More preferred are polyimide films or liquid crystal polymer films.

EXAMPLES Hereinafter, the present invention will be described in more detail based on Examples and Comparative Examples, but the present invention is not limited to the following Examples.

[Physical property evaluation method]
<Weight average molecular weight (Mw)>
The weight average molecular weight (Mw) was measured by GPC (gel permeation chromatography). A sample of maleimide resin dissolved in tetrahydrofuran (THF) to a concentration of 3% by mass was heated to 30°C using columns (GL-R420 (manufactured by Hitachi High-Tech Fielding Co., Ltd.) x 1, GL-R430 (manufactured by Hitachi High-Tech Fielding Co., Ltd.) 50 μL was injected into 1 bottle (manufactured by Hitachi High-Tech Fielding Co., Ltd.) and 1 bottle of GL-R440 (manufactured by Hitachi High-Tech Fielding Co., Ltd.), and measurements were performed at a flow rate of 1.6 mL/min using THF as the developing solvent. Ta. The detector used was an L-3350 RI detector (manufactured by Hitachi, Ltd.), and the weight average molecular weight (Mw ) was converted.

<Preparation of resin film>
Using an applicator, the adhesive compositions obtained in the Examples and Comparative Examples described below were applied onto Purex (registered trademark) A31 (polyester film, manufactured by Teijin DuPont Ltd., trade name) to a thickness after drying. The resin film was coated to a thickness of 65 μm and dried in an oven at 130° C. for 10 minutes.

<Adhesive strength>
A resin film from which Purex A31 has been peeled off, a glass plate with a thickness of 0.7 mm, and an LCP film with a thickness of 75 μm (manufactured by Kuraray Co., Ltd., product name "Vexter") are laminated so that the resin film is in the middle. Then, thermocompression bonding was carried out using a hot press at 200° C., 2 MPa, and 1 hour to obtain a laminate in which a glass plate, a cured resin film, and an LCP film were laminated in this order. The adhesive strength was measured by peeling off the LCP film of the obtained laminate. The peel strength was measured using a 90° peel measuring machine (manufactured by Yamaden Co., Ltd., trade name "RHEONER II CREEP METER RE2-3305B") at room temperature and a tensile speed of 5 mm/s. In addition, the peeling position (peeling mode) during peeling was observed.

<Permittivity and dielectric loss tangent>
A resin film from which Purex A31 was peeled off and two pieces of copper foil (product name "F2WS-18", manufactured by Furukawa Electric Co., Ltd.) were laminated so that the roughened surface of the copper foil faced the resin film, A copper foil laminate in which copper foil, a cured resin film, and copper foil were laminated in this order was obtained by thermocompression bonding using a hot press at 200° C., 2 MPa, and 1 hour. The copper foils on both sides of the obtained copper foil laminate were removed by etching, and after drying at 130° C. for 30 minutes, a 5 cm x 5 cm test piece was prepared. The dielectric constant and dielectric loss tangent were measured using the E4980A Precision LCR Meter manufactured by Agilent Technologies at a frequency of 2 MHz, and the Vector Network Analyzer 8364B manufactured by Agilent Technologies at a frequency of 10 GHz. carried out. In this example and comparative example, the dielectric constant tends to be a slightly lower value when measured at a frequency of 2 MHz, and the dielectric loss tangent tends to be a slightly lower value when measured at a frequency of 10 GHz. No major changes were observed in the values. Therefore, except for some examples, measurements of dielectric constant and dielectric loss tangent were performed at either a frequency of 2 MHz or a frequency of 10 GHz.

[Synthesis of bismaleimide resin]
<Synthesis example 1>
In a 1 L flask equipped with a condenser, nitrogen inlet tube, thermocouple, and stirrer, 60.8 parts by mass of pyromellitic dianhydride (manufactured by Daicel Corporation) and 400 parts by mass of mesitylene (manufactured by Toyo Gosei Co., Ltd.) were added. 4 parts by mass, and 90.7 parts by mass of ethanol (manufactured by Wako Pure Chemical Industries, Ltd.). After the addition, the temperature was raised to 80° C., kept warm for 0.5 hours, and 201.3 parts by mass of dimer diamine (trade name “PRIAMINE 1075”, manufactured by Croda Japan Co., Ltd.) was added dropwise. After dropping, 4.3 parts by mass of methanesulfonic acid (manufactured by Wako Pure Chemical Industries, Ltd.) was added. Thereafter, the temperature was raised to 165° C., and a dehydration ring-closing reaction was performed at 165° C. for 1 hour to remove water and ethanol from the reaction solution to obtain an intermediate polyimide resin. Subsequently, the obtained polyimide resin was cooled to 80°C, 27.3 parts by mass of maleic anhydride (manufactured by Fuso Chemical Industries, Ltd.) was added, the temperature was raised to 160°C, and a dehydration ring-closing reaction was carried out at 160°C for 2 hours. The water in the reaction solution was removed to obtain a bismaleimide resin.

The obtained bismaleimide resin was placed in a separatory funnel, 1000 parts by mass of pure water was added, the separatory funnel was shaken, and the mixture was allowed to stand still. After standing still, an aqueous layer and an organic layer were separated, and only the organic layer was collected. The collected organic layer was placed in a 1 L glass container equipped with a condenser, nitrogen inlet tube, thermocouple, stirrer, and vacuum pump, heated to 88-93°C, water removed, and then heated to 150°C. The temperature was raised and the solvent was removed for 1 hour under a reduced pressure of 0.1 MPa from atmospheric pressure to obtain a bismaleimide resin (A-1) (weight average molecular weight 16,000) as component (A).

[Example 1]
In a 500 ml four-neck flask equipped with a stirrer, 80 parts by mass of the maleimide resin (A-1) obtained in Synthesis Example 1 and epoxy resin (trade name "YX-4000", manufactured by Mitsubishi Chemical Corporation) were added. 9 parts by mass and 100 parts by mass of toluene were added, and the mixture was stirred at 60°C for 1 hour. 11 parts by mass of an active ester curing agent (trade name "HPC-8000-65T", manufactured by DIC Corporation) was added to the obtained solution, and the mixture was stirred at 60° C. for 0.5 hour. Further, 2 parts by mass of a curing accelerator (trade name "2PZCN", manufactured by Shikoku Kasei Co., Ltd.) was added to the obtained solution, and the mixture was stirred at 60° C. for 3 hours to obtain an adhesive composition. Table 1 shows the blending amount of each component and the physical property evaluation results. In Table 1, the amounts of components (A) to (E) indicate parts by mass.

[Examples 2 to 12, Comparative Examples 1 to 2]
Example 1 except that the type and amount of one or more of the components of the bismaleimide resin, epoxy resin, active ester curing agent, and curing accelerator were changed to those shown in Table 1 or Table 2. In the same manner, adhesive compositions of Examples 2 to 12 and Comparative Examples 1 to 2 were obtained. Tables 1 and 2 show the blending amount of each component and the physical property evaluation results. Note that in Tables 1 and 2, the amounts of components (A) to (E) indicate parts by mass. Further, details of components (A) to (E) are as follows.

(A) Component: Bismaleimide resin (A-1) Bismaleimide resin of Synthesis Example 1 (weight average molecular weight 16,000)

(B) Component: Epoxy resin (B-1) Biphenyl type epoxy resin: YX-4000 (manufactured by Mitsubishi Chemical Corporation)
(B-2) Bisphenol F type epoxy resin: YDF-8170C (manufactured by Nippon Steel & Sumikin Chemical Co., Ltd.)

(C) Component: Active ester curing agent (C-1) HPC-8000-65T (manufactured by DIC Corporation)
(C-2) HPC-8000L-65MT (manufactured by DIC Corporation)

(D) Component: Curing accelerator (D-1) 1-(2-cyanoethyl)-2-phenylimidazole: 2PZCN (manufactured by Shikoku Kasei Co., Ltd.)
(D-2) 2-ethyl-4-methyl-imidazole: 2E4MZ (manufactured by Fuji Film Wako Pure Chemical Industries, Ltd.)
(D-3) 1,2-dimethylimidazole: 1,2-DMZ (manufactured by Shikoku Kasei Co., Ltd.)
(D-4) Dimethylbenzylamine: DMBA (manufactured by Fuji Film Wako Pure Chemical Industries, Ltd.)
(D-5) Triethylamine: TEA (manufactured by Fuji Film Wako Pure Chemical Industries, Ltd.)
(D-6) Dicumyl peroxide: DCP (manufactured by NOF Corporation)
(D-7) Tetrabutylphosphonium-1,2-cyclohexyldicarboxylic acid (cation species: anion species = 1:1): TBP-3S (manufactured by Hokuko Chemical Co., Ltd.)

As is clear from the results shown in Tables 1 and 2, the adhesive composition (Example) containing the specific bismaleimide resin of the present invention, epoxy resin, active ester curing agent, and curing accelerator, It was confirmed that it exhibited high adhesive strength with LCP. In particular, a comparison was made between the case where component (D) contained an imidazole compound, an amine compound, and a peroxide compound (Example), and the case where component (D) contained a phosphorus compound (Comparative Example 1). It was confirmed that the adhesive strength could be dramatically improved. Furthermore, it was confirmed that the adhesive composition (Example) of the present invention has a low dielectric constant and a low dielectric loss tangent, and is excellent in low dielectric properties.

The present invention provides an adhesive composition that has high adhesion to a low polarity resin base material such as LCP, which has a low dielectric property superior to that of conventional polyimide, and also has excellent low dielectric properties, and a laminate bonded using the adhesive composition. and an adhesive sheet can be obtained. Due to the above properties, the adhesive composition of the present invention is useful for flexible printed wiring board applications, particularly for FPC applications that require low dielectric properties (low dielectric constant, low dielectric loss tangent) in a high frequency region.

Claims (6)

(A) contains a bismaleimide resin represented by the following general formula (1), (B) an epoxy resin, (C) an active ester curing agent, and (D) a curing accelerator,
The component (D) contains at least one selected from the group consisting of imidazole compounds, amine compounds, and peroxide compounds,
The content of the component (B) is 2.0 to 15.0 parts by mass, based on 100 parts by mass of the total amount of the component (A), the component (B), and the component (C),
An adhesive composition in which the content of the component (C) is 2.0 to 20.0 parts by mass based on 100 parts by mass of the total amount of the component (A), the component (B), and the component (C). .

[In formula (1), R ¹ represents a divalent hydrocarbon group derived from a dimer acid, Q is a substituted or unsubstituted aliphatic group having 1 to 100 carbon atoms, a substituted or unsubstituted aromatic group, Alternatively, it represents a substituted or unsubstituted heteroaromatic group, and n represents an integer of 0 to 100. ] Claim 1, wherein the content of the component (D) is 0.1 to 5.0 parts by mass based on 100 parts by mass of the total amount of the component (A), the component (B), and the component (C). The adhesive composition described in . The adhesive composition according to claim 1 or 2, which is used for adhesion between a resin base material and a resin base material or a metal base material. A laminate comprising a base material and an adhesive layer formed on the base material using the adhesive composition according to any one of claims 1 to 3. A laminate comprising a resin base material and a resin base material or a metal base material adhered by the adhesive composition according to any one of claims 1 to 3. An adhesive sheet comprising the laminate according to claim 4 or 5.