Curable compound and resin composition containing the same

Abstract

To provide a curable polymer compound having high adhesiveness to a low-roughness copper foil, a low dielectric constant and dielectric loss tangent, a low linear expansion coefficient and excellent solubility in a low-boiling solvent.SOLUTION: (In the formula, X each independently represents a residue obtained by removing maleimide groups at both terminals of bismaleimide. Each Y independently represents a residue obtained by removing an amino group from an aliphatic diamine compound. Z each independently represents a hydrogen atom or a structure represented by the following formula (2). M is an average value of the number of repeating units and is in the range of 1 to 100. N represents an integer of 1 to 18. The present inventors have found that the above problems can be solved by a polymer compound represented by the following formula (I): SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a compound that can be easily formed into a film by casting a solution onto a substrate, that can undergo a thermal or photo-curing reaction when used in combination with a radical initiator, and that produces a cured product with excellent dielectric properties, adhesiveness, and heat resistance. [Background technology]

[0002] Phenoxy resin is a polymeric compound with a very high molecular weight obtained by polymerizing a difunctional epoxy resin and a difunctional phenolic compound. By adding this phenoxy resin, it is possible to form general epoxy resin compositions and radically polymerizable compositions into film form, and it is therefore used in a wide range of fields as an important component of film adhesives, particularly in the electrical and electronic fields where it is used for interlayer insulation layers in printed circuit boards and resin-coated copper foils. Although cured products of resin compositions containing added phenoxy resin have excellent adhesive properties and film-forming ability, they have low heat resistance and, moreover, high dielectric constants and dielectric dissipation factors (at a frequency of 1 GHz, the dielectric constant is about 3.5 and the dielectric dissipation factor is about 0.03), making them unsuitable for use in electronic devices, which have seen the recent increase in signal response speed. Polymeric fluorine compounds such as polytetrafluoroethane (PTFE) (Patent Document 1) and liquid crystal polymers (Patent Document 2) are generally known as resins with excellent dielectric properties, but these resins have extremely low compatibility with other resins and insufficient adhesive properties. Aromatic bismaleimides are known for their excellent heat resistance and dielectric properties. However, they generally have poor solvent solubility, dissolving only in high-boiling aprotic polar solvents such as NMP and DMF. This makes them difficult to use in electronic materials, which use low-boiling solvents such as toluene and methyl ethyl ketone. Furthermore, their cured products are generally rigid and inflexible, making them difficult to use in film applications. Patent Document 3 discloses a method for improving solvent solubility by subjecting aromatic bismaleimides to a Michael addition reaction with aliphatic diamines to achieve high molecular weight. However, this polymer composed of a bismaleimide compound and a diamine compound contains residual secondary amines in its structure. These secondary amines react with the maleimide groups at the molecular terminals, which can easily cause crosslinking and lead to gelation during the reaction. Patent Documents 4 and 5 disclose a method for improving stability by reacting the secondary amines produced after the reaction of bismaleimide with a diamine with acetic anhydride to acetylate them. However, the resins obtained using this method have an extremely high linear expansion coefficient when cured, making them unsuitable for applications such as electronic devices, which require high reliability. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2005-001274 [Patent Document 2] Japanese Patent Application Laid-Open No. 2014-060449 [Patent Document 3] Japanese Patent Application Laid-Open No. 2006-241300 [Patent Document 4] Patent No. 6948907 [Patent Document 5] Publication US8637611 Summary of the Invention [Problem to be solved by the invention]

[0004] The present invention has been made in view of the above points, and aims to provide a curable compound that has high adhesion to low-roughness copper foil, low dielectric constant and dielectric dissipation factor, low linear expansion coefficient, and excellent solubility in low-boiling point solvents such as toluene. [Means for solving the problem]

[0005] As a result of extensive investigations, the present inventors have found that the above problems can be solved by using a compound having a specific structure, and have thus completed the present invention. That is, the present invention is (1) The following formula (1)

[0006] [ka]

[0007] (In the formula, X's each independently represent a residue obtained by removing the maleimide groups at both ends of a bismaleimide. Y's each independently represent a residue obtained by removing the amino group of an aliphatic diamine compound. Z's each independently represent a hydrogen atom or a group represented by the following formula (2):

[0008] [ka]

[0009] wherein m is the average number of repeating units and is in the range of 1 to 100; and n is an integer of 1 to 18. (2) A resin composition containing the compound according to the preceding item (1) and a radical initiator. (3) The resin composition according to the above item (2), which contains a radical-reactive monomer having one or more functional groups in one molecule. (4) The resin composition according to the above item (2), which contains a radical reactive polymer having two or more functional groups in one molecule. (5) A film-like adhesive containing the resin composition according to any one of (2) to (4) above. (6) A cured product of the resin composition according to any one of the preceding items (2) to (4), or a cured product of the film-like adhesive according to the preceding item (5). Regarding. [Effects of the Invention]

[0010] The compound of the present invention and a resin composition containing the compound can provide a curable compound that has high adhesion to low-roughness copper foil, low dielectric constant and dielectric dissipation factor, low linear expansion coefficient, and excellent solubility in low-boiling point solvents such as toluene. DETAILED DESCRIPTION OF THE INVENTION

[0011] As a result of extensive investigations, the present inventors have found that the above-mentioned problems can be solved by a compound obtainable by reacting a secondary amine present in a copolymer obtained by reacting a bismaleimide with an aliphatic diamine with a molecule containing a long-chain alkyl group and an isocyanate group in one molecule, and have completed the present invention.

[0012] The compound of the present invention is represented by the following formula (1).

[0013] [ka]

[0014] In the formula (1), X's each independently represent a residue obtained by removing the maleimide groups at both ends of a bismaleimide. Y's each independently represent a residue obtained by removing the amino group of an aliphatic diamine compound. Z's each independently represent a hydrogen atom or a group represented by the following formula (2):

[0015] [ka]

[0016] m is the average number of repeating units and is in the range of 1 to 100. n is an integer of 1 to 18.

[0017] The bismaleimide used in the present invention may be either aromatic or aliphatic. Examples of such bismaleimides include N,N'-tetramethylene bismaleimide, 2,2-bis[4-(4-maleimidophenoxy)phenyl]propane bisphenol A bis(4-maleimidophenyl ether), N,N'-ethylene bismaleimide, N,N'-1,4-phenylene bismaleimide, N,N'-hexamethylene bismaleimide, N,N'-1,3-phenylene bismaleimide, 4,4'-bismaleimide diphenylethane, 3,3'-dimethyl-5,5'-diethyl-4,4'-diphenylmethane bismaleimide, 3,3'-,5,5'-tetramethyl-4,4'-diphenylmethane bismaleimide, 3,3'-,5,5'-tetraisopropyl-4,4'-diphenylmethane bismaleimide, dimer diamine bismaleimide, etc. The bismaleimide is preferably an aromatic bismaleimide. Bismaleimides are obtained by maleimidating the amino groups of aromatic or aliphatic diamines. X represents the residue of the bismaleimide after removing the maleimide groups from both ends.

[0018] Specific examples of aliphatic diamines include 1,2-diaminoethane, 1,3-diaminopropane, 1,4-diaminobutane, hexamethylenediamine, 1,8-diaminooctane, 1,10-diaminodecane, 1,12-diaminododecane, 4,4'-methylenebiscyclohexanediamine, 1,2-cyclohexanediamine, 1,3-cyclohexanediamine, 1,4-cyclohexanediamine, 1,3-bis(aminomethyl)cyclohexane, 1,4-bis(aminomethyl)cyclohexane, isophoronediamine, norbornenediamine, and dimer diamine, among others. Dimer diamines with 36 carbon atoms are particularly preferred. Dimer diamines include those that retain the double bonds derived from the unsaturated fatty acid raw material and those that are hydrogenated. Hydrogenated dimer diamines are preferred to prevent deterioration of dielectric properties due to oxidation of the double bonds. Y in formula (1) above is the residue moiety obtained by removing both terminal amino groups from an aromatic diamine.

[0019] The dimer diamine is a compound in which two carboxy groups of a dimer acid, which is a dimer of an unsaturated fatty acid such as oleic acid, are converted to primary amino groups. Non-limiting general formulas of dimer diamines are shown below (in each formula, m+n is preferably 6 to 17, and p+q is preferably 8 to 19, and the dashed lines represent carbon-carbon single bonds or carbon-carbon double bonds).

[0020] [ka]

[0021] The intermediate of the compound of the present invention is represented by the following formula (4), and can be obtained by subjecting bismaleimide to Michael addition with an aliphatic diamine.

[0022] [ka] (In the formula, X and Y have the same meanings as in formula (1).)

[0023] It is preferable to use a solvent in the Michael addition reaction, and examples of usable solvents include toluene, xylene, methyl ethyl ketone, methyl isobutyl ketone, cyclopentanone, cyclohexanone, propylene glycol monomethyl ether acetate, propylene glycol monomethyl ether, etc. The amount of solvent used is preferably 10 to 300% based on the solid content, and more preferably 20 to 200%.

[0024] The molar ratio of bismaleimide to aliphatic diamine is preferably 1:0.98 to 1:0.4, and particularly preferably 1:0.96 to 1:0.5. A reaction catalyst need not be used. The reaction temperature is usually 50 to 150°C, preferably 60 to 140°C, and the reaction time is usually 0.5 to 30 hours, preferably 1 to 20 hours. The reaction can be terminated when the molecular weight measured by GPC (gel permeation chromatography) no longer increases from a certain value. The solvent used in the reaction may be distilled off under reduced pressure with heating, or may be used as is as a solvent for the resin composition varnish.

[0025] The number average molecular weight of the compound intermediate of the present invention is usually 1,000 to 100,000, preferably 1,500 to 80,000. To obtain a copolymer having a number average molecular weight within the above range, the raw material components may be charged in the above-mentioned ratio. Note that the molecular weight in this specification refers to a value calculated in polystyrene equivalent based on the results of GPC measurement. The compound of the present invention is preferably a polymer compound.

[0026] The compound can be obtained by reacting a secondary amine present in the copolymer with an isocyanate group in a compound represented by the following formula (5).

[0027] [ka] (wherein n represents an integer of 1 to 18).

[0028] Examples of the compound represented by formula (5) include methyl isocyanate, ethyl isocyanate, propyl isocyanate, butyl isocyanate, pentyl isocyanate, hexyl isocyanate, heptyl isocyanate, octyl isocyanate, nonyl isocyanate, decyl isocyanate, undecyl isocyanate, dodecyl isocyanate, tridecyl isocyanate, tetradecyl isocyanate, pentadecyl isocyanate, hexadecyl isocyanate, heptadecyl isocyanate, and octadecyl isocyanate. From the viewpoint of electrical properties, however, compounds having 10 or more carbon atoms are particularly preferred.

[0029] The ratio of the intermediate represented by formula (2) to the compound represented by formula (5) is preferably 0.1 to 1 mole, more preferably 0.2 to 1 mole, of the compound represented by formula (6) per equivalent of the secondary amino group in the copolymer. The reaction temperature is preferably 10 to 120°C, and the reaction time is preferably 30 minutes to 5 hours.

[0030] The resin composition of the present invention contains the compound of the present invention and a radical initiator, and can be cured by using the radical initiator in combination with heat or light energy. Preferred thermal radical initiators include peroxides such as benzoyl peroxide, cumene hydroperoxide, 2,5-dimethylhexane-2,5-dihydroperoxide, 2,5-dimethyl-2,5-di(t-butylperoxy)hexyne-3, di-t-butyl peroxide, t-butylcumyl peroxide, α,α-bis(t-butylperoxy-m-isopropyl)benzene, 2,5-dimethyl-2,5-di(t-butylperoxy)hexane, dicumyl peroxide, di-t-butylperoxyisophthalate, t-butylperoxybenzoate, 2,2-bis(t-butylperoxy)butane, 2,2-bis(t-butylperoxy)octane, 2,5-dimethyl-2,5-di(benzoylperoxy)hexane, di(trimethylsilyl)peroxide, and trimethylsilyltriphenylsilyl peroxide.

[0031] Examples of preferred photoradical 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-amylanthraquinone, 2-t-butylanthraquinone, and 1-chloroanthraquinone; thioxanthones such as 2,4-dimethylthioxanthone, 2,4-diisopropylthioxanthone, and 2-chlorothioxanthone; acetophenone dimethyl ketal, benzoin, and acetophenone dimethyl ketal; ketals such as diethyl dimethyl ketal; benzophenones such as benzophenone; 2-methyl-1-[4-(methylthio)phenyl]-2-morpholino-propan-1-one and 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butanone-1; acylphosphine oxides and xanthones; oxime esters such as 1,2-octanedione, 1-[4-(phenylthio)phenyl]-, 2-(o-benzoyloxime), ethanone, 1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazol-3-yl]-, 1-(o-acetyloxime).

[0032] The content of the radical initiator in the resin composition is usually 0.1 to 10 parts by mass, preferably 0.1 to 8 parts by mass, per 100 parts by mass of the compound and resin components such as the optional radical reactive monomer described below.

[0033] The resin composition may contain a radical reactive monomer. The use of a radical reactive monomer in combination can improve the reactivity of the resin composition and the heat resistance of the cured product. The radical reactive monomer is preferably one having one or more functional groups, and specific examples thereof include acenaphthylene, ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, triethylene glycol dimethacrylate, 1,4-butanediol dimethacrylate, neopentyl glycol dimethacrylate, 1,6-hexanediol dimethacrylate, 1,9-Nonanediol dimethacrylate, glycerin dimethacrylate, 2-hydroxy-3-acryloyloxypropyl methacrylate, ethylene oxide adduct methacrylate of bisphenol A, trimethylolpropane trimethacrylate, tricyclodecane dimethanol dimethacrylate, glycerin dimethacrylate, trimethylolpropane trimethacrylate, ethoxylated isocyanuric acid triacrylate, ε-caprolactone-modified tris-(2-acryloxyethyl)isocyanurate, pentaerythritol triacrylate, ditrimethylolpropane tetraacrylate, ethoxylated pentaerythritol tetraacrylate, pentaerythritol tetraacrylate, dipentaerythritol polyacrylate, dipentaerythritol hexaacrylate, triallyl isocyanurate, triallyl cyanurate, divinylbenzene, divinyl isophthalate, N-phenyl-maleimide, N-phenyl-methylmaleimide, N-phenyl-chloromaleimide Np-chlorophenyl-maleimide, Np-methoxyphenyl-maleimide, Np-methylphenyl-maleimide, Np-nitrophenyl-maleimide, Np-phenoxyphenyl-maleimide, Np-phenylaminophenyl-maleimide, Np-phenoxycarbonylphenyl-maleimide, 1-maleimido-4-acetoxysuccinimide-benzene, 4-maleimido-4'-acetoxysuccinimide-diphenylmethane, 4-maleimido-4'-acetoxysuccinimide- Examples of suitable maleimide compounds include diphenyl ether, 4-maleimide-4'-acetamido-diphenyl ether, 2-maleimide-6-acetamido-pyridine, 4-maleimide-4'-acetamido-diphenylmethane, Np-phenylcarbonylphenyl-maleimide, N-ethylmaleimide, N-2,6-xylylmaleimide, N-cyclohexylmaleimide, N-2,3-xylylmaleimide, xylylmaleimide, 2,6-xylenemaleimide, and 4,4'-bismaleimidediphenylmethane. These radical reactive monomers may be used alone or in combination of two or more.

[0034] The resin composition may contain a radical reactive polymer in combination. By using a radical reactive polymer in combination, it is possible to improve the adhesiveness of the resin composition and the heat resistance of the cured product. The radical reactive polymer is preferably one having two or more functional groups, and specific examples thereof include a copolymer of styrene and butadiene, a modified polyphenylene ether resin, an imide-extended bismaleimide, or a polymer represented by the following formula (6):

[0035] [ka]

[0036] (wherein m is the average number of repeating units and each m is independently in the range of 1 to 20).

[0037] The styrene-butadiene copolymer may be a random copolymer (commonly known as SBR) or a block copolymer. It may also be a block copolymer in which the butadiene-derived double bonds in the block copolymer are hydrogenated to form saturated hydrocarbons (commonly known as SEBS resin). The ratio of styrene to butadiene in the polymer is typically 10:90 to 90:10. The number average molecular weight is typically 1,000 to 100,000. Specific examples of SBR products include Ricon 100, Ricon 181, and Ricon 184 from Cray Valley, while specific examples of SEBS resin products include the Tuftec series from Asahi Kasei Corporation and the G Polymer series from Kraton.

[0038] A preferred example of the modified polyphenylene ether resin is one having a methacryloyl group, an acryloyl group, or a vinyl group at both ends of the molecule and a number average molecular weight of 1000 to 10000. A specific example is a polyphenylene ether resin having a methacryloyl group at both ends and a number average molecular weight of about 1700, represented by the following formula (7):

[0039] [ka] or a compound represented by the following formula (8) having vinyl groups at both ends and a number average molecular weight of about 1200 or 2200 (product name SA9000 manufactured by SABIC Japan LLC).

[0040] [ka]

[0041] (product name OPE-2St 1200 or OPE-2St 2200, manufactured by Mitsubishi Gas Chemical Co., Inc.)

[0042] The imide-extended bismaleimide resin used in the present invention can be obtained by a known method, such as that described in Japanese Patent Publication No. 5328006. Specifically, the resin can be obtained by carrying out a dehydration condensation reaction of an aliphatic diamine and an aromatic or aliphatic tetracarboxylic dianhydride in an organic solvent using an acid catalyst in a molar ratio such that the aliphatic diamine is in excess, followed by dehydration condensation of amino groups present at the polymer terminals with maleic anhydride, and then removing the catalyst by washing with water.

[0043] Specific examples of aliphatic diamines include 1,10-diaminodecane; 1,12-diaminododecane; dimer diamine; 1,2-diamino-2-methylpropane; 1,2-diaminocyclohexane; 1,2-diaminopropane; 1,3-diaminopropane; 1,4-diaminobutane; 1,5-diaminopentane; 1,7-diaminoheptane; 1,8-diaminomenthane; 1,8-diaminooctane; 1,9-diaminononane; 3,3'-diamino-N-methyldipropylamine; diaminomaleonitrile; 1,3-diaminopentane; and 9,10-diaminophenanthrene, with dimer diamine being particularly preferred.

[0044] Specific examples of aromatic or aliphatic tetracarboxylic dianhydrides 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'-oxydiphthalic anhydride, 3,3',4,4'-diphenylsulfonetetracarboxylic dianhydride, 2,2'-bis(3,4-dicarboxyphenyl)hexafluoropropane dianhydride, and 4,4'-bisphenol A. Diphthalic anhydride, 5-(2,5-dioxytetrahydro)-3-methyl-3-cyclohexene-1,2-dicarboxylic anhydride, ethylene glycol bis(trimellitic anhydride), hydroquinone diphthalic anhydride, 1,2,3,4-cyclobutanetetracarboxylic dianhydride (CBDA), 1,2-dimethyl-1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,2,3,4-tetramethyl-1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,2,3,4-cyclopentanetetracarboxylic dianhydride, 1,2,4,5-cyclohexanetetracarboxylic dianhydride, 1,1'-bicyclohexane-3,3',4,4'-tetracarboxylic dianhydride Examples of suitable dianhydrides include tetracarboxylic acid-3,4:3',4'-dianhydride, 4-(2,5-dioxotetrahydrofuran-3-yl)-1,2,3,4-tetrahydronaphthalene-1,2-dicarboxylic acid anhydride, 5-(2,5-dioxotetrahydrofuryl)-3-methyl-3-cyclohexene-1,2-dicarboxylic acid dianhydride, bicyclo[2.2.2]oct-7-ene-2,3,5,6-tetracarboxylic acid dianhydride, 2,3,4,5-tetrahydrofuran tetracarboxylic acid dianhydride, and 3,5,6-tricarboxy-2-norbornane acetic acid dianhydride, with pyromellitic anhydride and 1,2,4,5-cyclohexane tetracarboxylic acid dianhydride being particularly preferred. A specific product name is BMI-3000 from Designer Molecules, Inc.

[0045] The resin composition may contain an organic solvent. 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 (NMP), N,N-dimethylformamide (DMF), N,N-dimethylacetamide, and N,N-dimethylimidazolidinone, and sulfones such as tetramethylene sulfone. The content of the organic solvent in the resin composition of the present invention is typically 90% by mass or less, preferably 30 to 80% by mass.

[0046] The resin composition may contain a polymerization inhibitor in order to improve storage stability. The polymerization inhibitor that can be used in combination is not particularly limited as long as it is a commonly known polymerization inhibitor, and examples thereof include quinones such as hydroquinone, methylhydroquinone, p-benzoquinone, chloranil, and trimethylquinone, aromatic diols, and di-t-butylhydroxytoluene.

[0047] The resin composition may be blended with fillers and additives in amounts that do not impair the inherent performance, in order to impart desired performance depending on the application. The fillers may be fibrous or powdery, and examples of such fillers include silica, carbon black, alumina, talc, mica, glass beads, and glass hollow spheres.

[0048] The resin composition may also contain flame-retardant compounds, additives, and the like. These may be any commonly used compounds without any particular limitations. Examples of flame-retardant compounds include bromine compounds such as 4,4-dibromobiphenyl, phosphate esters, melamine phosphate, phosphorus-containing epoxy resins, nitrogen compounds such as melamine and benzoguanamine, oxazine ring-containing compounds, and silicon-based compounds. Additives include ultraviolet absorbers, antioxidants, photopolymerization initiators, fluorescent brighteners, photosensitizers, dyes, pigments, thickeners, lubricants, antifoaming agents, dispersants, leveling agents, gloss agents, and the like, which may be used in appropriate combinations as desired.

[0049] The resin composition can be applied to or impregnated into various substrates. For example, when a thermal radical initiator is used, it can be applied to PET film to form an interlayer insulating layer for multilayer printed circuit boards, to polyimide film to form a coverlay, or to copper foil to form resin-coated copper foil by applying and drying it. It can also be used as a printed wiring board or a CFRP prepreg by impregnating glass cloth, glass paper, carbon fiber, various nonwoven fabrics, etc. Furthermore, it can be used as a resist for various purposes by using a photoradical initiator.

[0050] Interlayer insulating layers, coverlays, resin-coated copper foils, prepregs, etc. can be made into cured products by heating and pressurizing them using a hot press or the like. [Example]

[0051] The present invention will be described in more detail below with reference to examples and comparative examples, but the present invention is not limited to these examples.

[0052] Example 1 (Synthesis of Compounds of the Present Invention) A flask equipped with a thermometer, a condenser, a nitrogen gas inlet tube, and a stirrer was charged with 22.10 parts (0.05 mol) of 3,3'-dimethyl-5,5'-diethyl-4,4'-diphenylmethane bismaleimide (product name: BMI-70, manufactured by K.I. Chemical Co., Ltd.), 21.64 parts (0.04 mol) of dimer diamine (product name: Priamine 1074, manufactured by Croda), and 45 parts of toluene, and the mixture was reacted at 100°C for 6 hours to obtain a toluene solution of copolymer 1 represented by the following formula (9).

[0053] [ka]

[0054] The number average molecular weight of this copolymer was 3,700 and the weight average molecular weight was 26,000. From the number average molecular weight, the value of n in formula (1) was calculated to be 3.3. To a toluene solution of this copolymer, 23.68 parts (0.08 mol) of octadecyl isocyanate was added, and the mixture was reacted at 100°C for 2 hours. By adjusting the amount of toluene, 168 parts of a 40% toluene solution of the compound of the present invention represented by the following formula (10) was obtained.

[0055] [ka]

[0056] Comparative Example 1 (Synthesis of a Comparative Compound) The reaction was carried out in the same manner as in Example 1 to obtain Copolymer 1 represented by the formula (9), and then 8.16 parts (0.08 mol) of acetic anhydride was added and the reaction was continued for another hour at 60°C. 45 parts of toluene was added to the reaction solution to dilute it, and then 45 parts of pure water was added, and the by-product acetic acid was removed by stirring and washing with water. After repeated washing with water until the aqueous layer became neutral, the toluene solution was concentrated to obtain 118 parts of a 40% toluene solution of a comparative compound represented by the following formula (11).

[0057] [ka]

[0058] Example 2 and Comparative Example 2 (Preparation of Resin Composition) 0.05 parts of dicumyl peroxide as a radical initiator was added to 10 parts of a toluene solution of the compounds obtained in Example 1 and Comparative Example 1, and the mixture was mixed uniformly to obtain a resin composition of the present invention (Example 2) and a comparative resin composition (Comparative Example 2).

[0059] (Evaluation of dielectric properties and heat resistance of cured resin compositions) The resin compositions obtained in Example 2 and Comparative Example 2 were each applied to a thickness of 280 μm onto the mirror-like surface of 18 μm-thick copper foil using an applicator, and then heated at 90°C for 10 minutes to dry off the solvent. The film-like adhesive on the copper foil obtained above was heat-cured in a vacuum oven at 180°C for 1 hour, and then immersed in an etching solution to remove the copper foil. The film-like adhesive made from the resin composition of the present invention yielded a cured product with a thickness of 70 μm that could be handled as a film, and the dielectric properties were evaluated using the cured product. The dielectric properties were evaluated by measuring the dielectric constant and dielectric loss tangent at 10 GHz using a network analyzer 8719ET (Agilent Technologies) using a cavity resonance method. The glass transition temperature and linear expansion coefficient (α1) of the test specimens were also determined using a thermomechanical analyzer (TMA). The results are shown in Table 1.

[0060] (Evaluation of adhesive strength of cured resin composition) The resin compositions obtained in Example 2 and Comparative Example 2 were applied to a 50 μm thickness on the matte side of a 12 μm thick, low-roughness copper foil for high frequency applications (CF-T4X-SV, manufactured by Fukuda Metal Foil & Powder Co., Ltd.) using an applicator, and the coating was heated at 90°C for 10 minutes to dry off the solvent, yielding a copper foil bearing a film-like adhesive comprising the resin composition of the present invention. The matte side of the same copper foil was then placed on top of the adhesive side of the copper foil obtained above, and the resulting foil was heated and cured in a vacuum press at a pressure of 3 MPa for 1 hour. The 90°C peel strength (adhesion strength) between the copper foils was then measured using an Autograph AGX-50 (manufactured by Shimadzu Corporation). The results are shown in Table 1.

[0061] [Table 1]

[0062] As described above, the polymer compound and composition of the present invention, when cured using a radical initiator, formed a flexible film and exhibited excellent dielectric properties, adhesiveness, and heat resistance. It was also shown that the polymer compound and composition had sufficient flexibility to be formed into a film.

Claims

1. The following formula (1) 【Chemistry 1】 (In the formula, X's each independently represent a residue obtained by removing the maleimide groups at both ends of a bismaleimide. Y's each independently represent a residue obtained by removing the amino group of an aliphatic diamine compound. Z's each independently represent a hydrogen atom or a group represented by the following formula (2): 【Chemistry 2】 m is the average number of repeating units and is in the range of 1 to 100; and n is an integer of 1 to 18.

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

3. The resin composition according to claim 2, which contains a radical reactive monomer having one or more functional groups in one molecule.

4. The resin composition according to claim 2, which contains a radical reactive polymer having two or more functional groups in one molecule.

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

6. A cured product of the resin composition according to claim 3 or 4, or the film-like adhesive according to claim 5.

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