Curable polymer compound and resin composition containing same

Abstract

Provided is a polymer compound represented by formula (1), which has sufficient flexibility that can be made thin as much as possible, has high adhesiveness to low-roughness copper foils, and has a low dielectric constant and a low dielectric loss tangent. A polymer compound represented by formula (1) # imgabs0 # (In the formula, each R1 independently represents a hydrogen atom or an alkyl group, but 50 mol% or more of R1 is an alkyl group. And R2 and R3 each independently represent a hydrogen atom or a methyl group. And m and n are average values of the number of repeating units and each independently represents a real number in the range of 1 to 2,000).

Description

Technical Field

[0001] The present invention relates to a polymer compound and a resin composition containing the polymer compound. The polymer compound can be easily formed into a film shape by casting a solution onto a substrate, and can undergo a thermal or photo-curing reaction when used in combination with a radical initiator, and the cured product thereof has excellent dielectric properties, bonding properties, and heat resistance. Background Art

[0002] Phenoxy resin is a very high molecular weight polymer compound obtained by polymerizing a bifunctional epoxy resin and a bifunctional phenol compound. By adding this phenoxy resin, since a general epoxy resin composition or a radically polymerizable composition can be formed into a film shape, it is used as an important component of a film-like adhesive in a wide range of fields, and is particularly used in the interlayer insulating layer of a printed wiring board or a resin-coated copper foil in the electric power / electronic field.

[0003] In fact, although the cured product of the resin composition added with phenoxy resin has excellent bonding properties and film-forming ability, due to its low heat resistance and high dielectric constant and dielectric loss tangent (dielectric constant of about 3.5 and dielectric loss tangent of about 0.03 at a frequency of 1 GHz), it cannot be used in electronic machine applications where the signal reaction speed has been increased in recent years. Resins with excellent dielectric properties are generally known, such as high molecular weight fluorine compounds such as polytetrafluoroethylene (PTFE) (Patent Document 1) or liquid crystal polymers (Patent Document 2), but the compatibility of these resins with other resins is extremely low, and the bonding properties are also insufficient. Although Patent Document 3 describes a polymer compound obtained by esterifying the aliphatic hydroxyl group in a random copolymer of a monomer having one ethylenically unsaturated group in an amount of 70% by weight or less and a (meth)acrylate having one or more aliphatic hydroxyl groups in an amount of 30% by weight or more with a monomer having one or more ethylenically unsaturated groups and one carboxyl group, as a result of supplementary tests by the present inventors, the cured product of the polymer compound obtained from the structural formula in this document has a dielectric loss tangent of about 0.005 at 10 GHz, and does not sufficiently satisfy the low dielectric properties required for current high-frequency circuit board applications.

[0004] [Prior Art Documents]

[0005] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2005-001274

[0007] [Patent Document 2] Japanese Patent Application Laid-Open No. 2014-060449

[0008] [Patent Document 3] Japanese Patent Application Laid-Open No. 10-017812. Summary of the Invention

[0009] (Problems to be Solved by the Invention)

[0010] The present invention has been made in view of the above points, and an object of the present invention is to provide a polymer compound having sufficient flexibility to be made as thin as possible, high adhesion to a low-roughness copper foil, low dielectric constant and low dielectric loss tangent, and high heat resistance.

[0011] (Means for Solving the Problems)

[0012] As a result of intensive studies by the present inventors, it has been found that the above problems can be solved by using a resin composition containing a polymer compound having a specific structure, and the following invention has been completed.

[0013] (1) A polymer compound represented by the following formula (1),

[0014]

[0015] (In the formula, each R1 independently represents a hydrogen atom or an alkyl group, provided that 50 mol% or more of R1 is an alkyl group. R2 and R3 each independently represent a hydrogen atom or a methyl group. m and n are the average values of the number of repeating units and each independently represents a real number in the range of 1 to 2,000);

[0016] (2) A resin composition containing the polymer compound according to the above (1) and a radical polymerization initiator;

[0017] (3) The resin composition according to the above (2), further containing a compound having a radical-reactive group;

[0018] (4) A film-like adhesive containing the resin composition according to the above (2) or (3); and

[0019] (5) A cured product which is a cured product of the resin composition according to the above (2) or (3).

[0020] (Effects of the Invention)

[0021] The resin composition of the present invention containing a polymer compound and a radical initiator can form a cured product by applying heat or light energy, and the cured product has excellent dielectric properties, adhesion and heat resistance. Detailed Description of the Invention

[0022] The embodiments of the present invention will be described below.

[0023] The above polymer compound has the following formula (1).

[0024]

[0025] (In the formula, R1 independently represents a hydrogen atom or an alkyl group, provided that more than 50 mol% of R1 is an alkyl group. R2 and R3 each independently represent a hydrogen atom or a methyl group. m and n are the average values of the number of repeating units and each independently represents a real number in the range of 1 to 2,000)

[0026] In the above formula (1), R1 represents a hydrogen atom or an alkyl group. In the polymer compound, a hydrogen atom and an alkyl group can coexist, but when they coexist, more than 50 mol% of R1 is an alkyl group. More preferably, it is 60 mol% or more, and still more preferably, it is 70 mol% or more. Here, R1 is determined according to the selection of the raw material monomer containing the R1 moiety. When using a plurality of raw material monomers containing the R1 moiety, the polymer compound of formula (1) will have a plurality of substituents as R1. Therefore, "more than 50 mol% of R1 is an alkyl group" means that more than 50% of R1 in the polymer compound of formula (1) is an alkyl group. In addition, the alkyl group that can be used as R1 is not particularly limited, for example, a linear or branched alkyl group having 1 to 30 carbon atoms.

[0027] R2 and R3 each independently represent a hydrogen atom or a methyl group. The ratio of the presence of a hydrogen atom and a methyl group is not particularly limited.

[0028] m and n are real numbers in the range of 1 to 2,000. However, when m and n are within this range, the number average molecular weight of the polymer compound of formula (1) will become a desired value.

[0029] The polymer compound represented by formula (1) is: a hydrochloride elimination condensate of a hydroxyl group of a random copolymer of a (meth)acrylic acid hydroxybenzene ester and a styrene-based compound, and a (meth)acryloyl chloride group, or a dehydration condensate of a hydroxyl group of the aforementioned random copolymer and (meth)acrylic acid.

[0030] The random copolymer as an intermediate raw material in the production of the polymer compound of formula (1) will be described. Specific examples of the (meth)acrylic acid hydroxybenzene ester as a raw material of the random copolymer include 4-hydroxybenzyl methacrylate, 2-hydroxybenzyl methacrylate, 3-hydroxybenzyl methacrylate, 4-hydroxybenzyl acrylate, 2-hydroxybenzyl acrylate, and 3-hydroxybenzyl acrylate, etc. More preferably, it is 4-hydroxybenzyl methacrylate.

[0031] In addition, in this specification, the description of "(meth)acrylate" means both "acrylate and methacrylate".

[0032] Styrenes as raw materials for the random copolymer mean alkylstyrenes and styrene. In the case of examples of alkylstyrenes, it is more preferably that the alkyl moiety is an alkyl group having 1 to 30 carbon atoms. Specific examples may include p-methylstyrene, m-methylstyrene, o-methylstyrene, p-tert-butylstyrene, etc. These can be used alone, as a mixture, or as a mixture with styrene having no alkyl group. However, when used in combination with styrene having no alkyl group, 50 mol% or more of the total moles of styrenes is alkylstyrene.

[0033] The following formula (2) is the structural formula of a random copolymer of a hydroxy phenyl (meth)acrylate and an alkylstyrene (and styrene). R1, R2, m, and n in formula (2) represent the same meanings as R1, R2, m, and n in formula (1). That is, the high molecular compound shown by formula (1) of the present invention (a high molecular compound having the structure shown by formula (1)) is a high molecular compound using the random copolymer shown by the following formula (2) as an intermediate raw material.

[0034]

[0035] The method for the copolymerization reaction of a hydroxy phenyl (meth)acrylate and styrenes (alkylstyrenes and styrene) is not particularly limited as long as it is a publicly known method. Examples may include bulk polymerization, solution polymerization, emulsion polymerization, and suspension polymerization, etc.

[0036] As for the solvents that can be used for solution polymerization, examples may include toluene, xylene, methyl ethyl ketone, methyl isobutyl ketone, cyclopentanone, cyclohexanone, anisole, propylene glycol monomethyl ether acetate, N-methylpyrrolidone, N,N-dimethylformamide, and γ-butyrolactone, etc. In emulsion polymerization and suspension polymerization, water and a surfactant are usually used, and the copolymerization reaction is carried out in water in a state where the raw material components are emulsified or suspended.

[0037] The polymerization reaction can be any of radical polymerization, cationic polymerization, and anionic polymerization. In radical polymerization, it is more preferably to use a radical polymerization initiator. Specific examples of radical polymerization initiators may include 2,2'-azobisisobutyronitrile, 2,2'-azobis(2-methylbutyronitrile), 2,2'-azobis(2,4-dimethylvaleronitrile), 1,1'-azobis(cyclohexane-1-carbonitrile), 2,2'-azobis[2-(2-imidazolin-2-yl)propane] dihydrochloride, hydrogen peroxide, di-tert-butyl peroxide, lauroyl peroxide, dicumyl peroxide, and benzoyl peroxide, etc.

[0038] Based on a total of 100 parts by mass of the raw material components of the random copolymer, the blending amount of the radical polymerization initiator is usually 0.001 to 5 parts by mass. The polymerization temperature is usually 50 to 250 °C, more preferably 60 to 200 °C, and the polymerization time is usually 0.5 to 30 hours, more preferably 1 to 20 hours. In order to prevent polymerization inhibition caused by oxygen in the air, it is more preferable to carry out the radical polymerization reaction in a nitrogen environment. In addition, living radical polymerization using a radical such as a TEMPO reagent or living radical polymerization using a RAFT reagent can also be carried out in combination with the polymerization initiator.

[0039] Specific examples of the cationic polymerization initiator include inorganic acids such as sulfuric acid and hydrochloric acid, organic acids such as CF3COOH and CCl3COOH, and superacids such as CF3SO3H and HClO4. In addition, specific examples of the anionic polymerization initiator include butyllithium, Na-naphthalene complex, alkali metals, alkyllithium compounds, sodium amide, Grignard reagent, and sodium alkoxide. However, since there is a concern that the ionic initiator used for cationic polymerization or anionic polymerization will remain in the random copolymer after the polymerization reaction and have an adverse effect on the dielectric properties or insulation, the synthesis of the random copolymer as an intermediate raw material of the high molecular compound of the present invention is more preferably carried out by radical polymerization.

[0040] Based on a total of 100 parts by mass of the raw material components of the random copolymer, the blending amount of the cationic polymerization initiator or the anionic polymerization initiator is usually 0.01 to 5 parts by mass. The polymerization temperature is usually 40 to 150 °C, more preferably 50 to 120 °C, and the polymerization time is usually 0.5 to 20 hours, more preferably 1 to 15 hours.

[0041] The number average molecular weight of the random copolymer as an intermediate raw material of the high molecular compound of formula (1) is usually 3,000 to 300,000, more preferably 5,000 to 200,000.

[0042] In order to obtain a copolymer with a number average molecular weight within the above range, it is more preferable to adjust the amount of the initiator used in the synthesis of the random copolymer to an appropriate amount. Since the amount of the initiator required to obtain a random copolymer with a number average molecular weight within the above range also depends on the type of (meth)acrylate having a phenolic hydroxyl group or the amount of (meth)acrylate having a hydroxyl group and alkylstyrene (and styrene) used in the copolymerization reaction, it cannot be generalized. However, it is generally known that if the amount of the initiator is reduced, a random copolymer with a large molecular weight will be obtained, and the blending amount of the initiator that can obtain a random copolymer with a desired molecular weight can be selected as long as it is within the above blending amount range.

[0043] When synthesizing a random copolymer as an intermediate raw material for the polymer compound of formula (1), the use ratio of hydroxyphenyl (meth)acrylate to alkylstyrene (and styrene) is not particularly limited, but the amount (mass) of alkylstyrene (and styrene) used is usually 4 to 99.7 times, more preferably 4.5 to 99.5 times, the mass of hydroxyphenyl (meth)acrylate. By setting the use ratio of hydroxyphenyl (meth)acrylate to alkylstyrene (and styrene) as raw materials for the random copolymer within the aforementioned range, a polymer compound can be obtained whose cured product exhibits excellent dielectric properties (low dielectric constant and low dielectric loss tangent).

[0044] The polymer compound of formula (1) is obtained by a dehydrochlorination reaction of the phenolic hydroxyl group (this phenolic hydroxyl group corresponds to the phenolic hydroxyl group possessed by hydroxyphenyl (meth)acrylate as a raw material) possessed by the aforementioned random copolymer and the acyl chloride group possessed by (meth)acryloyl chloride, or a dehydration condensation reaction of the phenolic hydroxyl group possessed by the aforementioned random copolymer and (meth)acrylic acid.

[0045] When synthesizing the polymer compound of formula (1), the use ratio of the random copolymer to (meth)acryloyl chloride or (meth)acrylic acid is not particularly limited, but when (meth)acryloyl chloride or (meth)acrylic acid is in excess or deficiency relative to the phenolic hydroxyl group possessed by the random copolymer, since unreacted and remaining (meth)acryloyl chloride or (meth)acrylic acid in the polymer compound of formula (1), or phenolic hydroxyl groups that have not reacted with (meth)acryloyl chloride or (meth)acrylic acid and remain may have an adverse effect on various properties of the cured product, it is more preferable to use 1 equivalent of (meth)acryloyl chloride or (meth)acrylic acid relative to the phenolic hydroxyl group possessed by the random copolymer.

[0046] The reaction of the random copolymer with (meth)acryloyl chloride can be carried out by adding (meth)acryloyl chloride under stirring in an organic solvent solution of the random copolymer. The organic solvent that can be used here is not particularly limited as long as it can dissolve the random copolymer and (meth)acryloyl chloride. When synthesizing the random copolymer as an intermediate raw material in the solvent, the random copolymer solution after the polymerization reaction can be directly used. The concentration of the random copolymer solution supplied for the reaction with (meth)acryloyl chloride is usually 10 to 90% by mass, more preferably 20 to 80% by mass. In addition, the reaction temperature is usually 30 to 120 °C, more preferably 40 to 110 °C, and the reaction time is usually 0.5 to 4 hours, more preferably 1 to 3 hours.

[0047] Since the reaction of the random copolymer with (meth)acryloyl chloride is a hydrochloric acid elimination reaction, in order to capture the generated hydrochloric acid to further promote the reaction, it is more preferable to add a tertiary amine such as triethylamine or pyridine to the reaction solution in advance. The usage amount of the tertiary amine is more preferably equimolar to 4-fold molar to (meth)acryloyl chloride, and more preferably equimolar to 3-fold molar. Since the hydrochloric acid generated during the reaction precipitates as the hydrochloride salt of the amine, it can be removed by filtration after the reaction. In addition, the excess tertiary amine can be distilled out of the system under reduced pressure by heating after filtration.

[0048] Examples of the reaction of the random copolymer with (meth)acrylic acid include the esterification reactions publicly known in the past, such as a method of heating and stirring the random copolymer and (meth)acrylic acid in the presence of a catalyst. Since the reaction of the random copolymer with (meth)acrylic acid is a dehydration reaction, it is more preferably carried out while distilling out water azeotropically from the reaction system. Therefore, it is more preferable to use solvents such as toluene, xylene, ethyl acetate, butyl acetate, and methyl isobutyl ketone that are not completely miscible with water to carry out the reaction. The usage amount of the solvent is more preferably an amount such that the concentration of the raw material components of the high molecular compound of formula (1) becomes 20 to 80% by mass.

[0049] Examples of the catalyst used in the esterification reaction include acidic catalysts such as sulfuric acid, methanesulfonic acid, and p-toluenesulfonic acid. With respect to the total mass of the raw material components of the high molecular compound of formula (1) and the solvent used in the reaction, etc., the usage amount is more preferably 0.1 to 5% by mass. The reaction temperature is usually 50 to 150 °C, more preferably 60 to 140 °C, and the reaction time is usually 0.5 to 4 hours, more preferably 1 to 3 hours.

[0050] In addition, when storing the high molecular compound of formula (1), in order to prevent the polymerization reaction between (meth)acryloyloxy groups in the high molecular compound of formula (1), it is more preferable to add a small amount of a polymerization inhibitor to the solution of the high molecular compound of formula (1) after the synthesis reaction is completed. Specific examples of the polymerization inhibitor include hydroquinone, p-methoxyphenol, methylhydroquinone, di-tert-butylhydroxytoluene, tert-butylhydroquinone, 2-tert-butyl-1,4-benzoquinone, 1,4-benzoquinone, 1,1-diphenyl-2-picrylhydrazyl radical, 6-tert-butyl-2,4-xylenol, 4-tert-butylcatechol, 2,6-di-tert-butylphenol, 2,6-di-tert-butyl-p-cresol, and phenothiazine (phenothiazine), etc.

[0051] The number-average molecular weight of the polymer compound of formula (1) obtained in such a manner preferably ranges from 11,000 to 300,000, more preferably from 15,000 to 200,000. When the molecular weight is less than the foregoing range, the adhesion to the low-roughness copper foil becomes low, and when it is greater than the foregoing range, the viscosity becomes high, making coating and the like difficult.

[0052] In addition, the number-average molecular weight in this specification means a value calculated by conversion to polystyrene based on the measurement results of GPC.

[0053] In this specification, the resin composition contains the polymer compound of formula (1) and a radical initiator. The radical initiator can be a thermal radical initiator or a photo radical initiator.

[0054] Examples of the more preferred thermal radical initiators include peroxides such as benzoyl peroxide, cumene hydroperoxide, 2,5-dimethylhexane-2,5-dihydroperoxide, 2,5-dimethyl-2,5-di(tert-butylperoxy)-3-hexyne, di-tert-butyl peroxide, tert-butyl cumyl peroxide, α,α-bis(tert-butylperoxy-m-isopropyl)benzene, 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane, dicumyl peroxide, di-tert-butyl isophthalate peroxide, tert-butyl benzoate peroxide, 2,2-bis(tert-butylperoxy)butane, 2,2-bis(tert-butylperoxy)octane, 2,5-dimethyl-2,5-di(benzoylperoxy)hexane, bis(trimethylsilyl) peroxide, and trimethylsilyl triphenylsilyl peroxide.

[0055] Examples of the more preferred photo radical initiators include benzoin and its alkyl ethers such as benzoin, benzoin methyl ether, and benzoin ethyl ether; acetophenones such as acetophenone, 2,2-dimethoxy-2-phenylacetophenone, and 1,1-dichloroacetophenone; anthraquinones such as 2-methylanthraquinone, 2-pentylanthraquinone, 2-tert-butylanthraquinone, and 1-chloroanthraquinone; thioxanthones such as 2,4-dimethylthioxanthone, 2,4-diisopropylthioxanthone, and 2-chlorothioxanthone; ketals such as acetophenone dimethyl ketal and benzyl dimethyl ketal; benzophenones such as benzophenone; 2-methyl-1-[4-(methylthio)phenyl]-2- morpholinyl-propan-1-one, 2-benzyl-2-dimethylamino-1-(4- morpholinylphenyl)-1-butanone; acylphosphine oxides and xanthones, etc.

[0056] With respect to 100 parts by mass in total of the resin components such as the polymer compound of formula (1) and the free-radical-reactive monomers of any of the components described later, the content of the free-radical initiator in the resin composition is usually 0.1 to 10 parts by mass, more preferably 0.1 to 8 parts by mass.

[0057] A compound having a free-radical-reactive group can be used in combination with the resin composition. The compound having a free-radical-reactive group that can be used in combination with the resin composition of the present invention can be either a free-radical-reactive monomer having a number-average molecular weight of less than 1,000 or a free-radical-reactive polymer having a number-average molecular weight of 1,000 or more, or both can be used in combination.

[0058] Specific examples of the radical-reactive monomer having a radical-reactive group include acenaphthylene, N-phenylmaleimide, N-vinyl-2-pyrrolidone (Methyl pyrrolidone), ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, triethylene glycol dimethacrylate, 1,4-butanediol dimethacrylate, neopentyl glycol dimethacrylate, 1,6-hexanediol dimethacrylate, 1,9-nonanediol dimethacrylate, glycerol dimethacrylate, 2-hydroxy-3-(acryloyloxypropyl) methacrylate, ethylene oxide adduct methacrylate of bisphenol A, trimethylolpropane trimethacrylate, tricyclodecane dimethanol dimethacrylate, glycerol dimethacrylate, trimethylolpropane trimethacrylate, epoxidized isocyanuric acid triacrylate, ε-caprolactone-modified tris(2-acryloyloxyethyl) isocyanurate, pentaerythritol triacrylate, di(trimethylolpropane) tetraacrylate, epoxidized pentaerythritol tetraacrylate, pentaerythritol tetraacrylate, dipentaerythritol polyacrylate, dipentaerythritol hexaacrylate, triallyl isocyanurate, triallyl cyanurate, divinylbenzene, isophthalic acid divinyl ester, N-phenyl-maleimide, N-phenyl-methylmaleimide, N-phenyl-chloromaleimide, N-(p-chlorophenyl)-maleimide (N-p-chlorophenyl-maleimide), N-p-methoxyphenyl-maleimide, N-p-methylphenyl-maleimide, N-p-nitrophenyl-maleimide, N-p-phenoxyphenyl-maleimide, N-p-phenylaminophenyl-maleimide, N-p-phenoxycarbonylphenyl-maleimide, 1-maleimide-4-acetoxysuccinimide-benzene, 4-maleimide-4'-acetoxysuccinimide-diphenylmethane, 4-maleimide-4'-acetoxysuccinimide-diphenyl ether, 4-maleimide-4'-acetamide-diphenyl ether, 2-maleimide-6-acetamide-pyridine, 4-maleimide-4'-acetamide-diphenylmethane and N-p-phenylcarbonylphenyl-maleimide N-ethylmaleimide, N-2,6-dimethylphenylmaleimide, N-cyclohexylmaleimide, N-2,3-dimethylphenylmaleimide, dimethylphenylmaleimide, 2,6-xylene maleimide and 4,4'-bismaleimide diphenylmethane, etc., but those having a maleimide group as a functional group are more preferred.

[0059] These radical-reactive monomers may be used alone or in combination of two or more.

[0060] By using a radical-reactive monomer in combination with the resin composition, the reactivity of the resin composition or the heat resistance of the cured product can be improved.

[0061] With respect to the high molecular compound of formula (1), the content of the radical-reactive monomer in the resin composition is usually 50% by mass or less, and more preferably 2 to 40% by mass.

[0062] Specific examples of the radical-reactive polymer having a radical-reactive group include polyphenylene ether having methacryloyl groups at both ends represented by the following formula (3) (product name SA-9000, manufactured by SABIC), polyphenylene ether having styryl groups modified at both ends represented by the following formula (4) (product name OPE-2St, manufactured by Mitsubishi Gas Chemical Company, Inc.), polyfunctional styrene resin represented by the following formula (5) (product name STR, manufactured by Nippon Kayaku Co., Ltd.), and styrene / butadiene copolymer. In addition, n and p in formulas (3) to (5) are average values of the number of repetitions, usually 2 to 100, and more preferably 4 to 80.

[0063] The number average molecular weight of the radical-reactive polymer represented by any one of formulas (3) to (5) is more preferably 1,000 to 3,000. In addition, it is also a more preferred aspect to use a radical-reactive monomer represented by any one of formulas (3) to (5) and having a number average molecular weight of 500 or more and less than 1,000 in the resin composition of the present invention.

[0064] By using a radical-reactive polymer in combination with the resin composition, the reactivity of the resin composition of the present invention or the heat resistance of the cured product can be improved.

[0065] With respect to the high molecular compound represented by formula (1), the content of the radical-reactive polymer in the resin composition is usually 80% by mass or less, and more preferably 5 to 70% by mass.

[0066]

[0067] An organic solvent may be contained in the resin composition. Specific examples of the organic solvent include aromatic solvents such as toluene and xylene, ether solvents such as diethylene glycol dimethyl ether, diethylene glycol diethyl ether, propylene glycol, propylene glycol monomethyl ether, propylene glycol monomethyl ether monoacetate, and propylene glycol monobutyl ether, ketone solvents such as methyl ethyl ketone, methyl isobutyl ketone, cyclopentanone, and cyclohexanone, lactones such as γ-butyrolactone and γ-valerolactone, amide solvents such as N-methylpyrrolidone (Methyl pyrrolidone) (NMP), N,N-dimethylformamide (DMF), N,N-dimethylacetamide, and N,N-dimethylimidazolidinone, sulfones such as tetramethylene sulfone, etc. The content of the organic solvent in the resin composition is usually 90% by mass or less in the resin composition, and more preferably 30 to 80% by mass.

[0068] A polymerization inhibitor may be used in combination in the resin composition to improve the storage stability. There is no particular limitation on the polymerization inhibitor that can be used in combination as long as it is generally publicly known. Examples thereof include quinones such as hydroquinone, methyl hydroquinone, p-benzoquinone, chloranil, and trimethylquinone, or aromatic diols, di-tert-butylhydroxytoluene, etc.

[0069] For the purpose of imparting desired properties according to its use, the resin composition can be used by blending a filler or an additive in an amount within a range that does not impair the original properties. The filler can be fibrous or powdery, and examples thereof include silica, carbon black, alumina, talc, mica, glass beads, glass hollow spheres, etc.

[0070] A flame retardant compound, an additive, etc. may also be used in combination in the resin composition. There is no particular limitation as long as these are generally used. For example, among the flame retardant compounds, bromine compounds such as 4,4-dibromobiphenyl, phosphate esters, melamine phosphate, phosphorus-containing epoxy resins, nitrogen compounds such as melamine or benzoguanamine, compounds containing a pyrazine ring, silicon-based compounds, etc. Among the additives, a UV absorber, an antioxidant, a photoinitiator, a fluorescent brightener, a photosensitizer, a dye, a pigment, a tackifier, a lubricant, an antifoaming agent, a dispersant, a leveling agent, a gloss agent, etc. can also be appropriately combined and used as desired.

[0071] The resin composition can be used by coating or impregnating various substrates. For example, when using a thermal radical initiator, it can be used as an interlayer insulating layer of a multilayer printed circuit board by coating on a PET film, as a cover film by coating on a polyimide film, and as a copper foil with resin by coating on a copper foil and drying it. In addition, by impregnating glass cloth, glass paper, carbon fiber, various non-woven fabrics, etc., it can be used as a prepreg for a printed wiring board or CFRP. Furthermore, by using a photo radical initiator, it can also be used as various photoresists.

[0072] Interlayer insulating layer covering films, resin-coated copper foils, prepregs, etc. can be formed into hardened products by heating and pressing with a hot press or the like.

[0073] (Example)

[0074] The present invention will be described in more detail below through examples and comparative examples. In addition, the present invention is not limited to these examples. In addition, in the examples, "parts" and "%" respectively mean "parts by mass" and "% by mass" unless otherwise specified.

[0075] Example 1 (Synthesis of Polymer Compound 1)

[0076] (Step 1) Synthesis of the random copolymer (random copolymer 1) represented by the following formula (6)

[0077] Into a flask equipped with a thermometer, a condenser, a nitrogen inlet tube, and a stirrer, 98.4 parts of 4-methylstyrene, 1.6 parts of 4-hydroxyphenyl methacrylate, 0.05 parts of azobisisobutyronitrile, and 50 parts of toluene were added, and the temperature was raised to 120 °C under a nitrogen atmosphere and reacted for 6 hours to obtain a toluene solution of the random copolymer 1 represented by the following formula (6). After analyzing a part of this solution by gas chromatography, as a result, no unreacted 4-hydroxyphenyl methacrylate remained. After heating a part of the toluene solution under reduced pressure to remove the solvent and unreacted 4-methylstyrene, the obtained amount of the random copolymer 1 calculated based on the dry mass as the solid content was 60.5 parts. Considering that the unreacted 4-methylstyrene was originally 37.9 parts, the obtained random copolymer 1 was a copolymer of 58.9 parts of 4-methylstyrene and 1.6 parts of 4-hydroxyphenyl methacrylate. In addition, the number average molecular weight of the sample supplied for the measurement of the dry mass was 39,000, and the weight average molecular weight was 161,000. The values of n and m in formula (6) were calculated to be 322 and 6, respectively, from the copolymerization ratio of 4-methylstyrene and 4-hydroxyphenyl methacrylate and the number average molecular weight.

[0078]

[0079] (Step 2) Synthesis of the polymer compound (polymer compound 1) represented by the following formula (7)

[0080] After distilling off unreacted 4-methylstyrene together with toluene from the toluene solution of the random copolymer 1 obtained in Step 1 under heating and reduced pressure, 150 parts of toluene was added to obtain a toluene solution of the random copolymer 1. 1.18 parts of triethylamine and 0.94 parts of methacryloyl chloride were added to this solution, and the reaction was carried out at 70 °C for 1 hour with stirring. By dropping the reaction solution into a large excess of methanol, the high molecular weight substance was precipitated and filtered, and then dried under reduced pressure to obtain 55.2 parts of the high molecular compound (high molecular compound 1) represented by the following formula (7). The number average molecular weight of the obtained high molecular compound 1 was 41,000, and the weight average molecular weight was 172,000.

[0081]

[0082] Comparative Example 1 (Synthesis of High Molecular Compound 2)

[0083] (Step 3) Synthesis of the random copolymer (random copolymer 2) represented by the following formula (8)

[0084] Except for changing 4-methylstyrene to styrene in the same molar amount, a toluene solution of copolymer 2 represented by the following formula (8) was obtained in the same manner as in Step 1. After analyzing a part of this solution by gas chromatography, it was found that no unreacted 4-hydroxyphenyl methacrylate remained. After heating a part of the aforementioned toluene solution under reduced pressure to remove the solvent and unreacted styrene, the obtained amount of the random copolymer 2 calculated based on the dry mass as the solid content was 59.5 parts. Considering that the originally unreacted styrene was 40.5 parts, the obtained random copolymer 2 was a copolymer of 57.9 parts of styrene and 1.6 parts of 4-hydroxyphenyl methacrylate. In addition, the number average molecular weight of the sample supplied for the measurement of the aforementioned dry mass was 35,000, and the weight average molecular weight was 155,000. The values of n and m in formula (5) were calculated to be 328 and 5, respectively, from the copolymerization ratio of styrene and 4-hydroxyphenyl methacrylate and the number average molecular weight.

[0085]

[0086] (Step 4) Synthesis of the comparative high molecular compound (high molecular compound 2) represented by the following formula (9)

[0087] Except for changing the toluene solution of the random copolymer 1 obtained in Step 1 to the toluene solution of the random copolymer 2 obtained in Step 3, 53.2 parts of the comparative high molecular compound (high molecular compound 2) represented by the following formula (9) was obtained in the same manner as in Step 2. The number average molecular weight of the obtained high molecular compound 2 was 39,000, and the weight average molecular weight was 162,000.

[0088]

[0089] Example 2 (Preparation of Resin Composition)

[0090] Resin composition 1 was obtained by adding 0.05 part of dicumyl peroxide as a radical initiator to 10 parts of a 25% solution prepared by dissolving 2.5 parts of the polymer compound 1 of the present invention obtained in Example 1 in toluene and mixing uniformly.

[0091] Example 3 (Preparation of Resin Composition)

[0092] Resin composition 2 of the present invention was obtained by adding 0.05 part of dicumyl peroxide as a radical initiator to 10 parts of a 25% solution prepared by dissolving 2.375 parts of the polymer compound 1 obtained in Example 1 and 0.125 part of bis(3-ethyl-5-methyl-4-maleimidophenyl)methane in toluene and mixing uniformly.

[0093] Comparative Example 2 (Preparation of Comparative Resin Composition)

[0094] Comparative resin composition 3 was obtained in the same manner as in Example 2, except that the polymer compound 1 obtained in Example 1 was changed to the polymer compound 2 obtained in Comparative Example 1.

[0095] (Evaluation of Dielectric Properties and Heat Resistance of Hardened Products of Resin Compositions)

[0096] Using an applicator, resin compositions 1, 2, and 3 obtained in Example 2, Example 3, and Comparative Example 2 were respectively coated on the mirror surface of a copper foil with a thickness of 18 μm to a thickness of 280 μm, and dried at 90°C for 10 minutes to remove the solvent, thereby obtaining a copper foil having a film-like adhesive containing each resin composition. After heat-hardening the film-like adhesive on the obtained copper foil at 180°C for 1 hour using a vacuum heater, the copper foil was removed by immersion in an etching solution, and hardened products of film-like adhesives with a thickness of 70 μm that could be used for film treatment were respectively obtained. For the dielectric constant and dielectric loss tangent at 10 GHz of the hardened products obtained above, a network analyzer 8719ET (manufactured by Agilent Technologies) was used to measure by the cavity resonance method. The results are shown in Table 1. In addition, for the same specimens, a TMA (thermomechanical measuring device) was used to measure the glass transition temperature and the linear expansion coefficients (α1, α2). The results are shown in Table 1.

[0097] (Evaluation of Bonding Strength of Hardened Products of Resin Compositions)

[0098] Using an applicator, the resin compositions 1, 2, and 3 obtained in Examples 2 and 3 and Comparative Example 2 were respectively coated on the matte surface of a low-roughness copper foil for high frequency (CF-T4X-SV: manufactured by Fukuda Metal Foil & Powder Co., Ltd.) with a thickness of 12 μm to a thickness of 50 μm, and dried by heating at 90°C for 10 minutes to obtain copper foils having a film-like binder containing each resin composition. The matte surface of the same copper foil as described above was laminated on the binder surface of the obtained resin-attached copper foil, and then heat-cured at a pressure of 3 MPa for 1 hour under vacuum pressure, and the 90° peel strength (bonding strength) between the copper foils was measured using Autograph AGX-50 (manufactured by Shimadzu Corporation). The results are shown in Table 1.

[0099] [Table 1] Evaluation Results of Hardened Products of Resin Compositions

[0100] Resin composition Resin composition 1 Resin composition 2 Resin composition 3 Dielectric constant (10 GHz) 2.50 2.42 2.45 Dielectric loss tangent (10 GHz) 0.00070 0.00067 0.00110 Glass transition temperature (°C) 110 125 108 α1 (ppm / °C) 72 65 75 α2 (ppm / °C) 125 115 1260 Bonding strength (N / mm) 0.60 0.55 0.60

[0101] As described above, when the high molecular compound of formula (1) is cured using a radical initiator, a flexible film is formed, showing more excellent dielectric properties, heat resistance, and bonding properties.

Claims

1. A polymer compound represented by the following formula (1), wherein R1 each independently represents a hydrogen atom or an alkyl group, provided that 50 mol% or more of R1 is an alkyl group; R2 and R3 each independently represent a hydrogen atom or a methyl group; m and n are the average values of the number of repeating units and each independently represents a real number in the range of 1 to 2,000.

2. A resin composition comprising the polymer compound according to claim 1 and a radical polymerization initiator.

3. The resin composition according to claim 2, further comprising a compound having a radical reactive group.

4. A film-like adhesive comprising the resin composition according to claim 2 or 3.

5. A cured product which is a cured product of the resin composition according to claim 2 or 3.

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