Polyfunctional vinyl aromatic copolymer having syndiotactic structure, curable resin composition, and cured product

Abstract

Provided is a novel polyfunctional vinyl aromatic copolymer having a syndiotactic structure, which can yield a cured product or molded body having improved dielectric properties, solubility, workability, compatibility, heat resistance, wet heat-resistant reliability and heat resistance.　The polyfunctional vinyl aromatic copolymer: contains not less than 2 mol% and less than 95 mol% of a repeating unit (a) derived from a divinyl aromatic compound (A) represented by general formula (1); and contains not less than 5 mol% and less than 98 mol% of a repeating unit (b) derived from a monovinyl aromatic compound (B) represented by general formula (2). The polyfunctional vinyl aromatic copolymer is characterized in that: the tacticity of a C1 carbon in a phenyl group that constitutes components (A) and (B), as determined by 13C-NMR, is 30% or more in terms of racemic pentad fraction; an unsaturated hydrocarbon group represented by formula (a1) is contained at a quantity of not less than 2 mol% and less than 95 mol% relative to the total amount of units (a) and (b); the number average molecular weight (Mn) is 500-30,000; the molecular weight distribution (Mw / Mn), which is represented by the ratio of weight average molecular weight and number average molecular weight, is 20.0 or less; and the copolymer is soluble in solvents.

Description

Polyfunctional vinyl aromatic copolymer having syndiotactic structure, curable resin composition, and cured product

[0001] The present invention relates to a multifunctional vinyl aromatic copolymer.

[0002] With the recent increase in the volume of information and communications, high-frequency information and communications have become increasingly common. To achieve better electrical properties, particularly to reduce transmission loss in high-frequency bands, electrical insulating materials with low dielectric constants and low dielectric dissipation factors, especially those with minimal change in dielectric properties after water absorption, are required. Furthermore, printed circuit boards and electronic components using these insulating materials are exposed to high-temperature solder reflow during assembly, so materials with high heat resistance, i.e., high glass transition temperatures, are desirable. Recently, environmental concerns have led to the use of lead-free solders with high melting points, which has led to an increased demand for more heat-resistant electrical insulating materials. To meet these demands, curable resins using vinyl compounds with various chemical structures have been proposed.

[0003] As such a cured resin, for example, Patent Document 1 discloses a polyfunctional vinyl aromatic copolymer containing structural units derived from a divinyl aromatic compound, styrene, and a monovinyl aromatic compound other than styrene, and containing a specific terminal group.

[0004] The polyfunctional vinyl aromatic copolymer disclosed in Document 1 itself has polymerizable double bonds, and therefore, when cured, gives a cured product having a high glass transition temperature.

[0005] However, it cannot be said that they are sufficient in terms of the high level of dielectric properties required in the field of cutting-edge technology, and in terms of resistance to heat discoloration and heat resistance when used continuously at high temperatures.

[0006] Patent Document 2 discloses a styrene copolymer with a syndiotactic structure. However, because styrene is used exclusively as the styrene monomer, the resulting copolymer has poor solvent solubility and does not satisfy the required properties for insulating materials in cutting-edge electrical and electronic fields.

[0007] WO2018 / 181842 JP 1-95112 Publication

[0008] An object of the present invention is to provide a novel polyfunctional vinyl aromatic copolymer having a syndiotactic structure, which has high dielectric properties, heat resistance, good solvent solubility, and moldability.

[0009] The present invention relates to a compound represented by the following general formula (1): The copolymer contains 2 mol % or more and less than 95 mol % of repeating units (a) derived from a divinylaromatic compound (A) represented by the following general formula (2): In the formula, R1 represents a hydrocarbon group having 1 to 30 carbon atoms, a halogen atom, or a substituent containing at least one of an oxygen atom, a nitrogen atom, a sulfur atom, a phosphorus atom, a selenium atom, a silicon atom, and a tin atom, and m represents an integer of 0 to 5. However, when m is plural, each R1 may be the same or different. A polyfunctional vinyl aromatic copolymer containing 5 mol % or more and less than 98 mol % of repeating units (b) derived from a monovinyl aromatic compound (B) represented by the formula: １ The tacticity of carbon １３ The content of the unsaturated hydrocarbon group represented by the following formula (a1) is 2 mol % or more and less than 95 mol % based on the total of (a) and (b), and the content of the unsaturated hydrocarbon group represented by the following formula (a1) is 30 mol % or more based on the total of (a) and (b), In the formula, R2 represents an aromatic hydrocarbon group having 6 to 30 carbon atoms. The polyfunctional vinyl aromatic copolymer has a number average molecular weight (Mn) of 500 to 30,000, a molecular weight distribution (Mw / Mn) expressed as the ratio of the weight average molecular weight to the number average molecular weight of 20.0 or less, and is soluble in a solvent.

[0010] The present invention provides a catalyst component (C) comprising at least one transition metal compound selected from compounds represented by the following general formula (3) or (4): ３ aR ４ bR ５ cX １ ４－（ａ＋ｂ＋ｃ） (3) MR ３ dR ４ eX １3-(d+e) (4) In the formula, R3, R4, and R5 each represent a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 20 carbon atoms, an alkylaryl group, an arylalkyl group, an acyloxy group having 1 to 20 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, a thioalkoxy group having 1 to 20 carbon atoms, a thioaryloxy group having 6 to 20 carbon atoms, a cyclopentadienyl group, a substituted cyclopentadienyl group, an indenyl group, a substituted indenyl group, a fluorenyl group, or a substituted fluorenyl group. M represents a transition metal selected from the group consisting of titanium (Ti), zirconium (Zr), and hafnium (Hf). X represents a substituted fluorenyl group. 1 represents a halogen atom. R3, R4, and R5 may be the same or different. Furthermore, a, b, and c each represent an integer of 0 to 4, and d and e each represent an integer of 0 to 3. The co-catalyst component (D) is a divinyl aromatic compound (A) represented by general formula (1) in the presence of a reaction product with at least one compound selected from the group consisting of compounds represented by the following (d) to (g): (d) an organoaluminum oxy compound, (e) an ionic compound capable of reacting with the transition metal compound to produce a cationic transition metal compound, (f) a Lewis acid compound capable of reacting with the transition metal compound to produce a cationic transition metal compound, and (g) an organometallic compound of a metal of Groups 1, 2, and 13 of the Periodic Table. a monovinyl aromatic compound (B) represented by general formula (2), Polymerization occurs at a temperature of 100°C or less, and the C of the phenyl groups constituting (A) and (B) is １ The tacticity of carbon １３ The present invention provides a method for producing a polyfunctional vinyl aromatic copolymer, characterized by obtaining a polyfunctional vinyl aromatic copolymer having a racemic pentad content of 30% or more as determined by C-NMR.

[0011] The present invention relates to a curable resin composition containing a polyfunctional vinyl aromatic copolymer, or a cured product thereof. The present invention also relates to a curable composite material comprising the curable resin composition and a substrate, a laminate having a layer of the cured composite material and a metal foil layer, a resin-coated metal foil having a film formed from the curable resin composition on one side of the metal foil, or a varnish for circuit board materials comprising the curable resin composition dissolved in an organic solvent.

[0012] The cured product obtained from the material containing the polyfunctional vinyl aromatic copolymer having a syndiotactic structure of the present invention has improved heat resistance, compatibility, dielectric properties, wet heat reliability, and heat resistance. According to the production method of the present invention, the polyfunctional vinyl aromatic copolymer having a syndiotactic structure can be produced with high efficiency.

[0013] The polyfunctional vinyl aromatic copolymer of the present invention is represented by the general formula (1) The copolymer contains 2 mol % or more and less than 95 mol % of repeating units (a) derived from a divinylaromatic compound (A) represented by the general formula (2): The copolymer contains 5 mol % or more and less than 98 mol % of repeating units (b) derived from a monovinyl aromatic compound (B) represented by the following formula: In formula (1) and formula (2), R1 represents a hydrocarbon group having 1 to 30 carbon atoms, a halogen atom, or a substituent containing at least one of an oxygen atom, a nitrogen atom, a sulfur atom, a phosphorus atom, a selenium atom, a silicon atom, and a tin atom, and m represents an integer of 0 to 5. However, when m is plural, each R1 may be the same or different. In formula (2), m is preferably 1 or more.

[0014] The polyfunctional vinyl aromatic copolymer of the present invention is a copolymer of C １ The tacticity of carbon １３ The compound has a racemic pentad content of 30% or more as determined by C-NMR and contains an unsaturated hydrocarbon group represented by the following formula (a1): In the formula, R2 represents an aromatic hydrocarbon group having 6 to 30 carbon atoms. The number average molecular weight Mn is 500 to 30,000, the molecular weight distribution (Mw / Mn) represented by the ratio of the weight average molecular weight Mw to the number average molecular weight Mn is 20.0 or less, and the polymer is soluble in solvents such as toluene, xylene, or tetrahydrofuran.

[0015] The polyfunctional vinyl aromatic copolymer of the present invention is soluble in common hydrocarbon solvents such as toluene and xylene, which are also used in the production process of copper-clad laminates. The structural unit referred to in this specification includes repeating units present in the main chain of the copolymer and units or terminal groups present in the terminal or side chain.

[0016] The repeating unit (a) derived from the divinylaromatic compound (A) represented by general formula (1) is contained in an amount of 2 mol % or more and less than 95 mol % of the sum of (a) and (b). (a) can have multiple structures, such as those in which only one vinyl group derived from (A) has reacted or those in which two vinyl groups have reacted. Of these, it is preferable that the repeating unit (a) contains 2 to 80 mol % of the structure represented by formula (a1) in which only one vinyl group has reacted. This is more preferably 5 to 70 mol %, even more preferably 10 to 60%, and even more preferably 15 to 50%. By containing 2 mol % or more and less than 95 mol %, the resulting resin has a low dielectric tangent, high toughness, and excellent heat resistance. It also has excellent compatibility with other resins. When formed into a resin composition, it also has excellent moist heat resistance, heat resistance, and moldability. On the other hand, if it is contained in an amount of less than 2 mol %, heat resistance tends to decrease, and if it is contained in an amount of 95 mol % or more, interlayer peel strength tends to decrease when formed into a laminate.

[0017] The vinyl group constituting the unsaturated hydrocarbon represented by formula (a1) derived from the divinylaromatic compound (A) represented by general formula (1) acts as a crosslinking component and contributes to the development of heat resistance of the polyfunctional vinyl aromatic copolymer.

[0018] On the other hand, the repeating unit (b) derived from the monovinyl aromatic compound (B) does not have a vinyl group because polymerization is generally believed to proceed via a 1,2-addition reaction of (B). In other words, (b) does not function as a crosslinking component. However, despite its highly syndiotactic structure, it contributes to the development of good solvent solubility.

[0019] The tacticity of the C1 carbon of the phenyl group constituting (A) and (B) is １３The racemic pentad content measured by C-NMR is 30% or more. This gives the polyfunctional vinyl aromatic copolymer of the present invention a highly syndiotactic structure. The content is preferably 60% or more, more preferably 70% or more, and even more preferably 85% or more.

[0020] The number average molecular weight (Mn) of the polyfunctional vinyl aromatic copolymer is preferably 500 to 30,000, more preferably 700 to 25,000, and even more preferably 1,000 to 20,000. If Mn is less than 500, the amount of monofunctional copolymer component contained in the polyfunctional vinyl aromatic copolymer increases, and the heat resistance of the cured product tends to decrease. On the other hand, if Mn exceeds 30,000, gel is generated and the viscosity increases, and therefore moldability tends to decrease.

[0021] The molecular weight distribution (Mw / Mn), which is the ratio of the weight average molecular weight (Mw) to the number average molecular weight (Mn), is 20.0 or less, preferably 15.0 or less, more preferably 1.5 to 10.0, and even more preferably 2.0 to 7.0. If Mw / Mn exceeds 20.0, the processability of the solvent-soluble curable aromatic vinyl copolymer having a syndiotactic structure deteriorates and gel tends to form.

[0022] The polyfunctional vinyl aromatic polymer of the present invention is also soluble in common hydrocarbon solvents such as toluene and xylene, which are also used in the manufacturing process of copper-clad laminates. In order to be a solvent-soluble polyfunctional copolymer, it is necessary that some of the vinyl groups of divinylbenzene remain uncrosslinked and maintain an appropriate degree of branching. "Soluble in a solvent" means that 5 g or more of the soluble polyfunctional vinyl aromatic copolymer can be dissolved in 100 g of solvent.

[0023] Next, the method for producing the polyfunctional vinyl aromatic copolymer having a syndiotactic structure of the present invention will be described.

[0024] In the production method of the present invention, the catalyst component (C) is a compound represented by the general formula (3) and (4): ３ aR ４ bR ５ cX １ ４－（ａ＋ｂ＋ｃ）(3) MR ３ dR ４ eX １ 3-(d+e) (4) and at least one compound selected from the following (d) to (g): (D) an organoaluminum oxy compound, (e) an ionic compound capable of reacting with the transition metal compound to produce a cationic transition metal compound, (f) a Lewis acid compound capable of reacting with the transition metal compound to produce a cationic transition metal compound, and (g) an organometallic compound of a metal of Groups 1, 2, and 13 of the Periodic Table. A divinyl aromatic compound (A) and a monovinyl aromatic compound (B) are polymerized at a temperature of 100° C. or lower in the presence of the catalyst component. The transition metal compound (C) acts as a catalyst, and the compounds (D) of (d) to (g) act as co-catalysts. In the transition metal compound (C) represented by the general formula (3) or (4), R3, R4, and R5 each represent a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 20 carbon atoms, an alkylaryl group, an arylalkyl group, an acyloxy group having 1 to 20 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, a thioalkoxy group having 1 to 20 carbon atoms, a thioaryloxy group having 6 to 20 carbon atoms, a cyclopentadienyl group, a substituted cyclopentadienyl group, an indenyl group, a substituted indenyl group, a fluorenyl group, or a substituted fluorenyl group. M represents a transition metal selected from the group consisting of titanium (Ti), zirconium (Zr), and hafnium (Hf). X represents a transition metal selected from the group consisting of titanium (Ti), zirconium (Zr), and hafnium (Hf). 1 represents a halogen atom. 3 , R 4 , and R 5 may be the same or different. Furthermore, a, b, and c each represent an integer of 0 to 4, and d and e each represent an integer of 0 to 3.

[0025] The divinyl aromatic compound (A) represented by the general formula (1) plays a role in forming a branched structure to impart polyfunctionality, and also plays a role as a crosslinking component to impart heat resistance when the resulting polyfunctional vinyl aromatic copolymer is heat-cured.

[0026] Examples of the divinylaromatic compound (A) represented by general formula (1) are not limited as long as they are aromatic compounds having two vinyl groups, but preferred examples include divinylbenzene (including each positional isomer or a mixture thereof), divinylnaphthalene (including each positional isomer or a mixture thereof), and divinylbiphenyl (including each positional isomer or a mixture thereof). These compounds may be each positional isomer or a mixture thereof. These compounds may be used alone or in combination of two or more. From the viewpoint of moldability, divinylbenzene (m-isomer, p-isomer, or a mixture of these positional isomers) is more preferred.

[0027] The monovinyl aromatic compound (B) represented by the general formula (2) serves as a monomer component to impart low dielectric properties, solvent solubility and heat resistance to the polyfunctional vinyl aromatic copolymer.

[0028] Examples of the monovinyl aromatic compound (B) are not limited as long as they are monovinyl aromatic compounds represented by general formula (2), but include nuclear alkyl-substituted vinyl aromatic compounds such as styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, o,p-dimethylstyrene, o-ethylvinylbenzene, m-ethylvinylbenzene, and p-ethylvinylbenzene, as well as compounds having a substituent containing one or more of a halogen atom, an oxygen atom, a nitrogen atom, a sulfur atom, a phosphorus atom, a selenium atom, a silicon atom, and a tin atom. Preferred are styrene, methylstyrene, ethylvinylbenzene, ethylvinylbiphenyl, and ethylvinylnaphthalene. Positional isomers of these compounds or mixtures thereof may also be used. From the viewpoints of dielectric properties and cost, more preferred are styrene, methylstyrene, or ethylvinylbenzene (m-isomer, p-isomer, or a mixture of positional isomers thereof).

[0029] In addition to the divinyl aromatic compound (A) and the monovinyl aromatic compound (B), other monomer components (E) such as trivinyl aromatic compounds, trivinyl aliphatic compounds, divinyl aliphatic compounds, and monovinyl aliphatic compounds can be used to introduce structural units (e) derived from (E) into the soluble polyfunctional vinyl aromatic copolymer, as long as the effects of the present invention are not impaired.

[0030] The other monomer component (E) is not limited, but preferred examples include 1,3,5-trivinylbenzene, 1,3,5-trivinylnaphthalene, 1,2,4-trivinylcyclohexane, ethylene glycol diacrylate, butadiene, 1,4-butanediol divinyl ether, cyclohexanedimethanol divinyl ether, diethylene glycol divinyl ether, and triallyl isocyanurate. These can be used alone or in combination of two or more. The other monomer component (E) preferably accounts for less than 30 mol% of the total of all monomer components, i.e., the total of (A), (B), and (E). In other words, the molar fraction of the repeating unit (e) derived from (E) preferably accounts for less than 30 mol% of the total of repeating units in the polyfunctional vinyl aromatic copolymer, i.e., the total of (a), (b), and (e).

[0031] If necessary, a hydroxyl group-containing vinyl compound (F) other than (A), (B), and (E), such as hydroxyethyl (meth)acrylate or hydroxypropyl (meth)acrylate, can be used to introduce structural units (f) derived from (F) into the polyfunctional vinyl aromatic copolymer. The hydroxyl group-containing vinyl compound (F) preferably accounts for less than 10 mol% of the total of all monomer components, i.e., the total of (A), (B), (E), and (F). Less than 5 mol% is particularly preferred. In other words, the molar fraction of the repeating unit (e) derived from (E) in the total of the repeating units in the polyfunctional vinyl aromatic copolymer, i.e., the total of (a), (b), (e), and (f), is preferably less than 10 mol%.

[0032] The proportions of the main monomer components used are, based on the total of (A) and (B), 2 mol % or more but less than 95 mol % of (A) and 5 mol % or more but less than 98 mol % of (B), and (A) and (B) are polymerized at a temperature of 100° C. or less. (A) is preferably 5 to 80 mol %, more preferably 7 to 70 mol %, and even more preferably 10 to 60 mol %, and (B) is preferably 95 to 20 mol %, more preferably 93 to 30 mol %, and particularly preferably 90 to 40 mol %.

[0033] The catalyst component (C) is represented by the following general formulas (3) and (4): ３ aR ４ bR ５ cX １ ４－（ａ＋ｂ＋ｃ） (3) MR ３ dR ４ eX １ At least one transition metal compound selected from compounds represented by the formula (3-(d+e) (4) is used. Among these transition metal compounds, titanium compounds are most preferably used in terms of polymerization activity. More preferred titanium compounds include mono(cyclopentadienyl)titanium compounds, mono(indenyl)titanium compounds, and mono(fluorenyl)titanium compounds represented by the formula (5). TiR ４ XYZ (5) In the formula, R4 represents a cyclopentadienyl group, a substituted cyclopentadienyl group, an indenyl group, a substituted indenyl group, a fluorenyl group, or the like, and X, Y, and Z each independently represent a hydrogen atom, an alkyl group having 1 to 12 carbon atoms, an alkoxy group having 1 to 12 carbon atoms, a thioalkoxy group having 1 to 20 carbon atoms, an aryl group having 6 to 20 carbon atoms, an aryloxy group having 6 to 20 carbon atoms, a thioaryloxy group having 6 to 20 carbon atoms, an arylalkyl group having 6 to 20 carbon atoms, or a halogen atom.

[0034] The substituted cyclopentadienyl group represented by R4 is, for example, a cyclopentadienyl group substituted with one or more alkyl groups having 1 to 6 carbon atoms, specifically a methylcyclopentadienyl group; a 1,3-dimethylcyclopentadienyl group; a 1,2,4-trimethylcyclopentadienyl group; a 1,2,3,4-tetramethylcyclopentadienyl group; a trimethylsilylcyclopentadienyl group; a 1,3-di(trimethylsilyl)cyclopentadienyl group; a tertiary butylcyclopentadienyl group; a 1,3-di(tertiary butyl)cyclopentadienyl group; a pentamethylcyclopentadienyl group, etc.

[0035] X, Y, and Z each independently represent a hydrogen atom, an alkyl group having 1 to 12 carbon atoms (specifically, a methyl group, an ethyl group, a propyl group, an n-butyl group, an isobutyl group, an amyl group, an isoamyl group, an octyl group, a 2-ethylhexyl group, etc.), an alkoxy group having 1 to 12 carbon atoms (specifically, a methoxy group, an ethoxy group, a propoxy group, a butoxy group, an amyloxy group, a hexyloxy group, an octyloxy group, a 2-ethylhexyloxy group, etc.), a thioalkoxy group having 1 to 20 carbon atoms (specifically, a thiomethoxy group, etc.), an aryl group having 6 to 20 carbon atoms (specifically, a phenyl group, a naphthyl group, etc.), an aryloxy group having 6 to 20 carbon atoms (specifically, a phenoxy group, etc.), a thioaryloxy group having 6 to 20 carbon atoms (specifically, a thiophenol group, etc.), an arylalkyl group having 6 to 20 carbon atoms (specifically, a benzyl group), or a halogen atom (specifically, a chlorine, bromine, iodine, or fluorine).

[0036] Specific examples of the titanium compound represented by the general formula (5) include cyclopentadienyltrimethyltitanium; cyclopentadienyltriethyltitanium; cyclopentadienyltripropyltitanium; cyclopentadienyltributyltitanium; methylcyclopentadienyltrimethyltitanium; 1,2-dimethylcyclopentadienyltrimethyltitanium; 1,2,4-trimethylcyclopentadienyltrimethyltitanium; 1,2,3,4-tetramethylcyclopentadienyltrimethyltitanium; pentamethylcyclopentadienyltrimethyltitanium; pentamethylcyclopentadienyltriethyltitanium; pentamethylcyclopentadienyltripropyltitanium; pentamethylcyclopentadienyltributyltitanium; cyclopentadienylmethyltitanium dichloride; cyclopentadienyl Pentamethylcyclopentadienylethyl titanium dichloride; Pentamethylcyclopentadienylmethyl titanium dichloride; Pentamethylcyclopentadienylethyl titanium dichloride; Cyclopentadienyldimethyl titanium monochloride; Cyclopentadienyldiethyl titanium monochloride; Cyclopentadienyl titanium trimethoxide; Cyclopentadienyl titanium triethoxide; Cyclopentadienyl titanium tripropoxide; Cyclopentadienyl titanium triphenoxide; Pentamethylcyclopentadienyl titanium trimethoxide; Pentamethylcyclopentadienyl titanium triethoxide; Pentamethylcyclopentadienyl titanium tripropoxide; Pentamethylcyclopentadienyl titanium tributoxide; Pentamethylcyclopentadienyl titanium triphenoxide; Cyclopentadienyl titanium trichloride; Pentamethylcyclopentadienyl titanium trichloride; Cyclopentadienyl methoxytitanium dichloride; Cyclopentadienyl dimethoxytitanium chloride; Pentamethylcyclopentadienyl methoxytitanium dichloride; Cyclopentadienyl tribenzyl titanium; Pentamethylcyclopentadienyl methyldiethoxytitanium; Indenyl titanium trichloride; Indenyl titanium trimethoxide; Indenyl titanium triethoxide; Indenyl trimethyltitanium; Indenyl tribenzyl titanium; Pentamethylcyclopentadienyl titanium trithiomethoxide;pentamethylcyclopentadienyl titanium trithiophenoxide;

[0037] As the titanium compound, a condensed titanium compound represented by the general formula (6) may be used. In the formula, R6 and R7 each represent a halogen atom, an alkoxy group or an acyloxy group having 1 to 20 carbon atoms, and k represents an integer of 2 to 20. Typical examples of the trivalent titanium compound represented by general formula (6) include titanium trihalides such as titanium trichloride, and cyclopentadienyltitanium compounds such as cyclopentadienyltitanium dichloride, as well as compounds obtained by reducing tetravalent titanium compounds. These trivalent titanium compounds may also be used in the form of complexes with esters, ethers, etc.

[0038] Zirconium compounds as transition metal compounds include tetrabenzylzirconium, zirconium tetraethoxide, zirconium tetrabutoxide, bisindenylzirconium dichloride, triisopropoxyzirconium chloride, zirconium benzyl dichloride, and tributoxyzirconium chloride. Hafnium compounds include tetrabenzylhafnium, hafnium tetraethoxide, and hafnium tetrabutoxide. Vanadium compounds include vanadyl bisacetylacetonate, vanadyl triacetylacetonate, triethoxyvanadyl, and tripropoxyvanadyl. Among these transition metal compounds, titanium compounds are particularly suitable. Titanium compounds may also be used in the form of complexes with esters, ethers, or the like.

[0039] The transition metal compound of component (A) is a transition metal compound having two ligands with conjugated π electrons, for example, at least one compound selected from the group consisting of transition metal compounds represented by general formula (7): １ R ８ R ９ R １０ R １１(7) In the formula, M1 represents titanium, zirconium, or hafnium, R8 and R9 each represent a cyclopentadienyl group, a substituted cyclopentadienyl group, an indenyl group, or a fluorenyl group, and R10 and R11 each represent a hydrogen atom, a halogen atom, a hydrocarbon group having 1 to 20 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, an amino group, or a thioalkoxy group having 1 to 20 carbon atoms, provided that R8 and R9 may be crosslinked by a hydrocarbon group having 1 to 5 carbon atoms, an alkylsilyl group having 1 to 20 carbon atoms and 1 to 5 silicon atoms, or a germanium-containing hydrocarbon group having 1 to 20 carbon atoms and 1 to 5 germanium atoms.

[0040] In the general formula (7), R8 and R9 each represent a cyclopentadienyl group, a substituted cyclopentadienyl group (specifically, a methylcyclopentadienyl group; a 1,3-dimethylcyclopentadienyl group; a 1,2,4-trimethylcyclopentadienyl group; a 1,2,3,4-tetramethylcyclopentadienyl group; a pentamethylcyclopentadienyl group; a trimethylsilylcyclopentadienyl group; a 1,3-di(trimethylsilyl)cyclopentadienyl group; a 1,2,4 1,3-di(tert-butyl)cyclopentadienyl group; 1,2,4-tri(tert-butyl)cyclopentadienyl group, etc.), indenyl group, substituted indenyl group (specifically, methylindenyl group, dimethylindenyl group, trimethylindenyl group, etc.), fluorenyl group, or substituted fluorenyl group (for example, methylfluorenyl group). R8 and R9 may be bridged by an alkylidene group having 1 to 5 carbon atoms (specifically, methine group, ethylidene group, propylidene group, dimethylcarbyl group, etc.) or an alkylsilyl group having 1 to 20 carbon atoms and 1 to 5 silicon atoms (specifically, dimethylsilyl group, diethylsilyl group, dibenzylsilyl group, etc.).

[0041] More specifically, R10 and R11 each independently represent a hydrogen atom, an alkyl group having 1 to 20 carbon atoms (e.g., methyl, ethyl, propyl, n-butyl, isobutyl, amyl, isoamyl, octyl, or 2-ethylhexyl), an aryl group having 6 to 20 carbon atoms (specifically, phenyl or naphthyl), an arylalkyl group having 7 to 20 carbon atoms (specifically, benzyl), an alkoxy group having 1 to 20 carbon atoms (specifically, methoxy, ethoxy, propoxy, butoxy, amyloxy, hexyloxy, octyloxy, or 2-ethylhexyloxy), an aryloxy group having 6 to 20 carbon atoms (specifically, phenoxy), or an amino group or a thioalkoxy group having 1 to 20 carbon atoms.

[0042] Specific examples of the transition metal compound represented by the general formula (7) include biscyclopentadienyltitanium dimethyl; biscyclopentadienyltitanium diethyl; biscyclopentadienyltitanium dipropyl; biscyclopentadienyltitanium dibutyl; bis(methylcyclopentadienyl)titanium dimethyl; bis(tert-butylcyclopentadienyl)titanium dimethyl; bis(1,3-dimethylcyclopentadienyl)titanium dimethyl; bis(1,3-ditert-butylcyclopentadienyl)titanium dimethyl; bis(1,2,4-trimethylcyclopentadienyl)titanium dimethyl; Bis(1,2,3,4-tetramethylcyclopentadienyl)titanium dimethyl; Bis(cyclopentadienyl)titanium dimethyl; Bis(trimethylsilylcyclopentadienyl)titanium dimethyl; Bis(1,3-di(trimethylsilyl)cyclopentadienyl)titanium dimethyl; Bis(1,2,4-tri((trimethylsilyl)cyclopentadienyl)titanium dimethyl; Bisindenyltitanium dimethyl; Bisfluorenyltitanium dimethyl; Methylenebiscyclopentadienyltitanium dimethyl; Ethylidenebiscyclopentadienyl Titanium dimethyl; Methylenebis(2,3,4,5-tetramethylcyclopentadienyl)titanium dimethyl; Ethylidenebis(2,3,4,5-tetramethylcyclopentadienyl)titanium dimethyl; Dimethylsilylbis(2,3,4,5-tetramethylcyclopentadienyl)titanium dimethyl; Methylenebisindenyltitanium dimethyl; Ethylidenebisindenyltitanium dimethyl; Dimethylsilylbisindenyltitanium dimethyl; Methylenebisfluorenyltitanium dimethyl; Ethylidenebisfluorenyltitanium dimethyl; Dimethylsilylbisfluorenyl Titanium dimethyl; Methylene(tert-butylcyclopentadienyl)(cyclopentadienyl)titanium dimethyl; Methylene(cyclopentadienyl)(indenyl)titanium dimethyl; Ethylidene(cyclopentadienyl)(indenyl)titanium dimethyl; Dimethylsilyl(cyclopentadienyl)(indenyl)titanium dimethyl; Methylene(cyclopentadienyl)(fluorenyl)titanium dimethyl; Ethylidene(cyclopentadienyl)(fluorenyl)titanium dimethyl; Dimethylsilyl(cyclopentadienyl)(fluorenyl)titanium dimethyl;Methylene(indenyl)(fluorenyl)titanium dimethyl; Ethylidene(indenyl)(fluorenyl)titanium dimethyl; Dimethylsilyl(indenyl)(fluorenyl)titanium dimethyl; Biscyclopentadienyltitanium dibenzyl; Bis(tert-butylcyclopentadienyl)titanium dibenzyl; Bis(methylcyclopentadienyl)titanium dibenzyl; Bis(1,3-dimethylcyclopentadienyl)titanium dibenzyl; Bis(1,2,4-trimethylcyclopentadienyl)titanium dibenzyl; Bis(1,2,3,4-tetramethylcyclopentadienyl)titanium dibenzyl Bis(1,3-di(trimethylsilyl)cyclopentadienyl)titanium dibenzyl; Bis(1,3-di(trimethylsilyl)cyclopentadienyl)titanium dibenzyl; Bis(1,2,4-tri(trimethylsilyl)cyclopentadienyl)titanium dibenzyl; Bis(indenyl)titanium dibenzyl; Bisfluorenyltitanium dibenzyl; Methylenebiscyclopentadienyltitanium dibenzyl; Ethylidenebiscyclopentadienyltitanium dibenzyl; Methylenebis(2,3,4,5-tetramethylcyclopentadienyl)titanium dibenzyl; Ethylidenebis(2,3,4,5-tetramethylcyclopentadienyl)titanium dibenzyl; Dimethylsilylbis(2,3,4,5-tetramethylcyclopentadienyl)titanium dibenzyl; Methylenebisindenyltitanium dibenzyl; Ethylidenebisindenyltitanium dibenzyl; Dimethylsilylbisindenyltitanium dibenzyl; Methylenebisfluorenyltitanium dibenzyl; Ethylidenebisfluorenyltitanium dibenzyl; Dimethylsilylbisfluor Fluorenyl titanium dibenzyl; Methylene(cyclopentadienyl)(indenyl)titanium dibenzyl; Ethylidene(cyclopentadienyl)(indenyl)titanium dibenzyl; Dimethylsilyl(cyclopentadienyl)(indenyl)titanium dibenzyl; Methylene(cyclopentadienyl)(fluorenyl)titanium dibenzyl; Ethylidene(cyclopentadienyl)(fluorenyl)titanium dibenzyl; Dimethylsilyl(cyclopentadienyl)(fluorenyl)titanium dibenzyl; Methylene(indenyl)(fluorenyl)titanium dibenzyl;Ethylidene(indenyl)(fluorenyl)titanium dibenzyl; Dimethylsilyl(indenyl)(fluorenyl)titanium dibenzyl; Biscyclopentadienyltitanium dimethoxide; Biscyclopentadienyltitanium diethoxide; Biscyclopentadienyltitanium dipropoxide; Biscyclopentadienyltitanium dibutoxide; Biscyclopentadienyltitanium diphenoxide; Bis(methylcyclopentadienyl)titanium dimethoxide; Bis(1,3-dimethylcyclopentadienyl)titanium dimethoxide; Bis(1,2,4-trimethylcyclopentadienyl) Bis(1,2,3,4-trimethylcyclopentadienyl)titanium dimethoxide; Bis(1,2,3,4-tetramethylcyclopentadienyl)titanium dimethoxide; Bispentamethylcyclopentadienyltitanium dimethoxide; Bis(trimethylsilylcyclopentadienyl)titanium dimethoxide; Bis(1,3-di(trimethylsilyl)cyclopentadienyl)titanium dimethoxide; Bis(1,2,4-tri(trimethylsilyl)cyclopentadienyl)titanium dimethoxide; Bisindenyltitanium dimethoxide; Bisfluorenyltitanium dimethoxide; Methylenebiscyclopentadienyl Dimethylsilylbis(2,3,4,5-tetramethylcyclopentadienyl)titanium dimethoxide; Methylenebis(2,3,4,5-tetramethylcyclopentadienyl)titanium dimethoxide; Ethylidenebis(2,3,4,5-tetramethylcyclopentadienyl)titanium dimethoxide; Dimethylsilylbis(2,3,4,5-tetramethylcyclopentadienyl)titanium dimethoxide; Methylenebisindenyltitanium dimethoxide; Methylenebis(methylindenyl)titanium dimethoxide; Ethylidenebisindenyltitanium dimethoxide; Dimethylsilylbis(isopropyl) Indenyl titanium dimethoxide; Methylene bisfluorenyl titanium dimethoxide; Methylene bis(methylfluorenyl) titanium dimethoxide; Ethylidene bisfluorenyl titanium dimethoxide; Dimethylsilyl bisfluorenyl titanium dimethoxide; Methylene(cyclopentadienyl)(indenyl) titanium dimethoxide; Ethylidene(cyclopentadienyl)(indenyl) titanium dimethoxide; Dimethylsilyl(cyclopentadienyl)(indenyl) titanium dimethoxide; Methylene(cyclopentadienyl)(fluorenyl) titanium dimethoxide;Examples include ethylidene(cyclopentadienyl)(fluorenyl)titanium dimethoxide; dimethylsilyl(cyclopentadienyl)(fluorenyl)titanium dimethoxide; methylene(indenyl)(fluorenyl)titanium dimethoxide; ethylidene(indenyl)(fluorenyl)titanium dimethoxide; dimethylsilyl(indenyl)(fluorenyl)titanium dimethoxide;

[0043] Zirconium compounds include ethylidenebiscyclopentadienylzirconium dimethoxide, dimethylsilylbiscyclopentadienylzirconium dimethoxide, and the like. Hafnium compounds include ethylidenebiscyclopentadienylhafnium dimethoxide, dimethylsilylbiscyclopentadienylhafnium dimethoxide, and the like. Among these, titanium compounds are particularly preferred. In addition to these combinations, bidentate complexes such as 2,2'-thiobis(4-methyl-6-t-butylphenyl)titanium diisopropoxide and 2,2'-thiobis(4-methyl-6-t-butylphenyl)titanium dimethoxide may also be used. Among these transition metal compounds, transition metal compounds having one π ligand, such as those represented by general formula (7), are particularly preferred.

[0044] In the polymerization catalyst used in the present invention, the transition metal compound (C) may be used alone or in combination of two or more. The component (D) contains a co-catalyst obtained from at least one selected from the following (a) to (d): (a) an organoaluminum oxy-compound; (b) an ionic compound capable of reacting with the transition metal compound to produce a cationic transition metal compound; (c) a Lewis acid compound capable of reacting with the transition metal compound to produce a cationic transition metal compound; and (d) an organometallic compound of a metal from Groups 1, 2, and 13 of the Periodic Table.

[0045] The organoaluminum oxy compound (a) is preferably a linear or cyclic polymer represented by the following general formula (8), which is a so-called aluminoxane: (-Al(R １２ )O-)n (8) In the formula, R12 is a hydrocarbon group having 1 to 10 carbon atoms, and R12 is a halogen atom and / or R１３ It may be substituted with an O group. Specific examples of R12 or R13 include alkyl groups such as methyl, ethyl, propyl, and isobutyl, with a methyl group being preferred. n represents the degree of polymerization, and is preferably 5 or more, more preferably 10 to 100, and most preferably 10 to 50. If the degree of polymerization n is less than 5, the polymerization activity decreases, which is undesirable, and if it is greater than 100, problems such as a decrease in polymerization activity and difficulty in demineralization treatment occur, which are undesirable.

[0046] Examples of the ionic compound (b) capable of reacting with the transition metal compound represented by general formula (3) or (4) to form a cationic transition metal compound include a non-coordinating anion and a cation. Examples of the non-coordinating anion include tetra(phenyl)borate, tetra(fluorophenyl)borate, tetrakis(difluorophenyl)borate, tetrakis(trifluorophenyl)borate, tetrakis(tetrafluorophenyl)borate, tetrakis(pentafluorophenyl)borate, tetrakis(tetrafluoromethylphenyl)borate, tetra(triyl)borate, tetra(oxyyl)borate, triphenylpentafluorophenylborate, and tris(pentafluorophenyl)phenylborate.

[0047] Among the non-coordinating anions, tetrakis(pentafluorophenyl)borate is particularly preferred. Specific examples include triphenylcarbenium tetrakis(pentafluorophenyl)borate; 4,4',4"-tri(methoxyphenyl)carbenium tetrakis(pentafluorophenyl)borate; tri(toluoyl)carbenium tetrakis(pentafluorophenyl)borate; 4,4',4"-tri(chlorophenyl)carbenium tetrakis(pentafluorophenyl)borate; triphenylsilyl tetrakis(pentafluorophenyl)borate; trimethoxysilyl tetrakis(pentafluorophenyl)borate; tri(thioisopropyl)silyl tetrakis(pentafluorophenyl)borate; trimethylsilyl tetrakis(pentafluorophenyl)borate; 4,4',4"-tri(methoxyphenyl)silyl tetrakis(pentafluorophenyl)borate; tri(toluoyl)silyl tetrakis(pentafluorophenyl)borate; 4,4',4"-tri(chlorophenyl)silyl tetrakis(pentafluorophenyl)borate, and the like.

[0048] Examples of the cation include a) carbonium cation, b) oxonium cation, c) ammonium cation, d) phosphonium cation, and e) ferrocenium cation having a transition metal. Specific examples of a) carbonium cation include tri-substituted carbonium cations such as triphenylcarbonium cation and tri-substituted phenylcarbonium cation. Specific examples of tri-substituted phenylcarbonium cation include tri(methylphenyl)carbonium cation and tri(dimethylphenyl)carbonium cation. Specific examples of b) oxonium cation include hydroxonium cation OH ３ ＋ , methyloxonium cation CH ３ OH ２ ＋ alkyloxonium cations such as dimethyloxonium cations (CH ３ ) ２ OH ＋dialkyloxonium cations such as trimethyloxonium cations (CH ３ ) ３ O ＋ , triethyloxonium cation (C ２ H ５ ) ３ O ＋ and the like. c) Specific examples of ammonium cations include trialkylammonium cations such as trimethylammonium cation, triethylammonium cation, tripropylammonium cation, and tributylammonium cation; N,N-dialkylanilinium cations such as N,N-diethylanilinium cation and N,N-2,4,6-pentamethylanilinium cation; and dialkylammonium cations such as di(i-propyl)ammonium cation and dicyclohexylammonium cation. d) Specific examples of phosphonium cations include triarylphosphonium cations such as triphenylphosphonium cation, tri(methylphenyl)phosphonium cation, and tri(dimethylphenyl)phosphonium cation.

[0049] The ionic compound (b) can be a combination of any of the non-coordinating anions and cations listed above. Among these, ionic compounds such as triphenylcarbonium tetra(pentafluorophenyl)borate, N,N-dimethylanilinium tetra(pentafluorophenyl)borate, and 1,1'-dimethylferrocenium tetra(pentafluorophenyl)borate are particularly preferred.

[0050] Specific examples of the Lewis acid compound (c) capable of reacting with the transition metal compound represented by the general formula (3) or (4) to produce a cationic transition metal compound include tris(pentafluorophenyl)boron, tris(monofluorophenyl)boron, tris(difluorophenyl)boron, and triphenylboron.

[0051] The organometallic compounds (d) of element metals of Groups 1, 2 and 13 of the Periodic Table include not only organometallic compounds in the strict sense, but also organometallic halide compounds and organometallic hydride compounds of element metals of Groups 1, 2 and 13 of the Periodic Table. Here, the element metals of Groups 1, 2 and 13 of the Periodic Table include the following: Element metals of Periodic Table 1: Li and Na Element metals of Periodic Table 2: Mg and Be Element metals of Periodic Table 13: Al and B Of these, preferred element metals are Li, Mg and Al, and particularly preferred is Al.

[0052] Examples of the organometallic compound (d) include methyllithium, butyllithium, phenyllithium, dibutylmagnesium, trimethylaluminum, triethylaluminum, triisobutylaluminum, trihexylaluminum, and trioctylaluminum, with trialkylaluminum being preferred. Examples of the organometallic halide compound (d) include ethylmagnesium chloride, butylmagnesium chloride, dimethylaluminum chloride, diethylaluminum chloride, sesquiethylaluminum chloride, and ethylaluminum dichloride. Examples of the hydrogenated organometallic compound (d) include diethylaluminum hydride and sesquiethylaluminum hydride.

[0053] In the present invention, the above co-catalysts (a) to (d) may be used alone or in combination. Preferred co-catalysts are (a) alone, (c) alone, and combinations of (a) and (d), (b) and (d), and (c) and (d). Particularly preferred is the combination of (c) and (d).

[0054] In the production method of the present invention, the catalyst component used is a reaction product of catalyst component (C) and co-catalyst component (D), but other catalyst components may be added within a range that does not impair the effects of the present invention. The blending ratio of components (C) and (D) in the catalyst of the present invention varies depending on the monomer components and polymerization conditions, etc., and is adjusted appropriately, but it is usually desirable that the molar ratio of catalyst component (C) to co-catalyst component (D) be within the following range.

[0055] The molar ratio of aluminum in the (d) organoaluminum oxy-compound to the (A) transition metal compound is typically 1 to 1,000,000, preferably 10 to 50,000, and more preferably 100 to 5,000. The molar ratio of the (e) ionic compound to the (A) transition metal compound is typically 0.01 to 100, preferably 0.1 to 10. The molar ratio of the (f) Lewis acid compound to the (A) transition metal compound is typically 0.01 to 100, preferably 0.1 to 10. When a Lewis acid compound is used as a cocatalyst component, it is preferable to use an organometallic compound of a metal from Groups 1, 2, and 13 of the Periodic Table in combination with the compound. When a (g) organometallic compound is used, the molar ratio of the (g) organometallic compound to the (A) transition metal compound is typically 0.1 to 10,000, preferably 1 to 1,000. A ratio outside the above range is undesirable because polymerization activity decreases.

[0056] In the present invention, the monomer components may be polymerized using a metal hydride compound in combination with an organometallic compound, organometallic halide compound, or organometallic hydride compound of a metal of Groups 1, 2, and 13 of the Periodic Table. Examples of the metal hydride compound include NaH, LiH, CaH, LiAlH, and NaBH. Examples of the organometallic compound, organometallic halide compound, and organometallic hydride compound of a main element metal of Groups 1, 2, and 13 of the Periodic Table are those described above.

[0057] In the present invention, the catalyst component (C) of the transition metal compound represented by general formula (3) or (4) can be used alone, or the catalyst component and at least one promoter component (D) can be supported on a carrier. Examples of the carrier include inorganic compounds and organic polymer compounds. Preferred inorganic compounds include inorganic oxides, inorganic chlorides, and inorganic hydroxides, and may contain small amounts of carbonates and sulfates. Preferred inorganic oxides include silica, alumina, magnesia, titania, zirconia, and calcia, as well as inorganic chlorides such as magnesium chloride. The inorganic compound should have an average particle size of 5 to 150 μm and a specific surface area of ​​2 to 800 m. 2 / g porous fine particles are preferred, and can be used after heat treatment at, for example, 100 to 800°C.

[0058] The organic polymer compound (g) used as the co-catalyst is preferably one having an aromatic ring, a substituted aromatic ring, or a functional group such as a hydroxyl group, a carboxyl group, an ester group, or a halogen atom in its side chain. Specific examples of the organic polymer compound include α-olefin homopolymers and α-olefin copolymers having functional groups obtained by chemically modifying polymers containing units such as ethylene, propylene, or butene; polymers containing units such as acrylic acid, methacrylic acid, vinyl chloride, vinyl alcohol, styrene, or divinylbenzene; and chemically modified products thereof. The organic polymer compound is preferably spherical fine particles with an average particle size of 5 to 250 μm. Supporting the transition metal compound catalyst and the co-catalyst on a carrier prevents contamination of the polymerization reactor due to the catalyst adhering to the carrier.

[0059] The polyfunctional vinyl aromatic copolymer of the present invention can be obtained, for example, by polymerizing monomer components, a catalyst, a cocatalyst, and the like as follows.

[0060] (I) Co-catalyst component (D) is pre-contacted with the monomer component, and then further contacted with catalyst component (C) to carry out polymerization. (II) Co-catalyst component (C), co-catalyst component (D), and a small amount of monomer component are pre-contacted, and then further contacted with the monomer component to carry out polymerization. (III) Co-catalyst component (C) is pre-contacted with co-catalyst component (D), and then further contacted with the monomer component to carry out polymerization. (IV) Co-catalyst component (C) is pre-contacted with the monomer component, and then further contacted with co-catalyst component (D) to carry out polymerization. (V) Co-catalyst component (C) and co-catalyst component (D) are mixed, contacted with a support, and the resulting supported catalyst is contacted with the monomer component to carry out polymerization. (VI) Co-catalyst component (C) is pre-contacted with a support, and then further contacted with co-catalyst component (D), and the resulting supported catalyst is contacted with the monomer component to carry out polymerization. (VII) After the cocatalyst component (D) is brought into contact with the support, it is further brought into contact with the catalyst component (C), and the resulting supported catalyst is brought into contact with the monomer component to carry out polymerization.

[0061] Among methods (I) to (VII), methods (I), (II), (III), and (IV) are preferred from the viewpoints of improving initiator efficiency and polymerization activity and further narrowing the molecular weight distribution of the resulting polymer. Methods (II) and (III) are more preferred. Particularly preferred are methods (II) and (III) in which catalyst component (C) and co-catalyst component (D) are pre-contacted for 0.001 to 300 minutes before contacting with the monomer components and carrying out polymerization. This method allows for highly efficient production of a polyfunctional vinyl aromatic copolymer having a syndiotactic structure and a narrow molecular weight distribution (Mw / Mn), which is the ratio of weight average molecular weight (Mw) to number average molecular weight (Mn).

[0062] The catalyst component (C) and the co-catalyst component (D) can be used in either a solution or a slurry state, but a solution state is preferred to obtain higher polymerization activity. The solvent used to prepare the solution or slurry is a hydrocarbon solvent such as butane, pentane, hexane, heptane, octane, cyclohexane, mineral oil, benzene, toluene, or xylene, or a halogenated hydrocarbon solvent such as chloroform, methylene chloride, dichloroethane, or chlorobenzene. Preferred solvents are aromatic hydrocarbons such as toluene or benzene. Two or more solvents may be used in combination.

[0063] The polymerization temperature is usually 100°C or lower, preferably 80°C or lower, and more preferably 0 to 60°C. If the polymerization temperature is higher than 100°C, an insoluble gel is likely to form. Typical polymerization times are 10 seconds to 36 hours, preferably 1 minute to 20 hours, and more preferably 5 minutes to 10 hours. The optimum time required to produce the desired polymer varies depending on the temperature, solvent, and polymerization conditions used.

[0064] The polymerization can be carried out at subatmospheric or superatmospheric pressures, even at reduced pressures where the lowest components of the polymerization mixture vaporize. Pressures near atmospheric pressure are preferred. Polymerization is typically carried out by solution polymerization in an inert solvent, slurry polymerization, or bulk polymerization using a monomer as a diluent. Solution or bulk polymerization is preferred.

[0065] Inert solvents used in the polymerization include aliphatic, cycloaliphatic, aromatic, and halogenated aromatic hydrocarbons, as well as mixtures thereof. Preferred inert solvents are C4 to C26 alkanes, particularly branched alkanes, toluene, ethylbenzene, and mixtures thereof. A solvent appropriate for providing a monomer concentration of 2 to 100% by weight is used. The polymerization reaction may be carried out by adding a small amount of polar compounds, such as ethers such as anisole, diphenyl ether, ethyl ether, diglyme, tetrahydrofuran, and dioxane, and amines such as triethylamine and tetramethylethylenediamine, as long as the effects of the present invention are not impaired.

[0066] To adjust the molecular weight of the polymer, a chain transfer agent can be added within a range that does not impair the effects of the present invention. As the chain transfer agent, arenes such as 1,2-butadiene, cyclic dienes such as cyclooctadiene, or hydrogen are preferably used. The polymerization reaction is usually terminated by adding a polymerization terminator to the polymerization system when a predetermined conversion rate is reached. As the polymerization terminator, for example, alcohols such as methanol, ethanol, propanol, butanol, and isobutanol are used. These may also contain acids such as hydrochloric acid. After the polymerization reaction has been terminated, the method for recovering the polymer is not particularly limited, and for example, steam stripping, precipitation in a poor solvent, etc. may be used.

[0067] The polyfunctional vinyl aromatic copolymer obtained by this production method contains 2 mol % or more but less than 95 mol % of repeating units (a) derived from (A) and 5 mol % or more but less than 98 mol % of repeating units (b) derived from monovinyl aromatic compound (B), and contains an unsaturated hydrocarbon group represented by the general formula (a1). The copolymer has an Mn of 500 to 30,000, a molecular weight distribution of 20.0 or less, and is soluble in toluene, xylene, and tetrahydrofuran. The copolymer has a syndiotactic structure in which the tacticity of the C1 carbon of the phenyl group constituting the divinyl aromatic compound (A) and the monovinyl aromatic compound (B) is 30% or more in racemic pentads as determined by C-NMR. A syndiotactic structure with a tacticity of 60% or more, more preferably 70% or more, even more preferably 85% or more, and particularly preferably 95% or more is preferred.

[0068] Next, the curable resin composition of the present invention will be described. The curable resin composition of the present invention contains a polyfunctional vinyl aromatic copolymer and a radical polymerization initiator (radical polymerization catalyst). For example, the curable resin composition of the present invention is cured by a crosslinking reaction caused by heating or the like, as described below, and the radical polymerization initiator is contained for the purpose of lowering the reaction temperature during the crosslinking reaction or promoting the crosslinking reaction of unsaturated groups.

[0069] Known substances can be used as the radical polymerization initiator (h). Typical examples include 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-butyl peroxides such as ethyl peroxybenzoate, 2,2-bis(t-butylperoxy)butane, 2,2-bis(t-butylperoxy)octane, 2,5-dimethyl-2,5-di(benzoylperoxy)hexane, di(trimethylsilyl)peroxide, and trimethylsilyltriphenylsilylperoxide; 2-phenylazo-4-methoxy-2,4-dimethylvaleronitrile, 1-[(1-cyano-1-methylethyl)azo]formamide, and 1,1'-azobis(cyclohexane-1-carbonitrile); 2,2'-Azobis(2-methylbutyronitrile), 2,2'-azobisisobutyronitrile, 2,2'-azobis(2,4-dimethylvaleronitrile), 2,2'-azobis(2,4-dimethyl-4-methoxyvaleronitrile), 2,2'-azobis(2-methylpropionamidine) dihydrochloride, 2,2'-azobis(2-methyl-N-phenylpropionamidine) dihydrochloride, 2,2'-azobis[N-(4-chlorophenyl)-2-methylpropionamidine]dihydrochloride, 2,2'- Azobis[N-(4-hydrophenyl)-2-methylpropionamidine]dihydrochloride, 2,2'-azobis[2-methyl-N-(phenylmethyl)propionamidine]dihydrochloride, 2,2'-azobis[2-methyl-N-(2-propenyl)propionamidine]dihydrochloride, 2,2'-azobis[N-(2-hydroxyethyl)-2-methylpropionamidine]dihydrochloride, 2,2'-azobis[2-(5-methyl-2-imidazolin-2-yl)propane]dihydrochloride, 2,2'-Azobis[2-(2-imidazolin-2-yl)propane]dihydrochloride, 2,2'-Azobis[2-(4,5,6,7-tetrahydro-1H-1,3-diazepin-2-yl)propane]dihydrochloride, 2,2'-Azobis[2-(3,4,5,6-tetrahydropyrimidin-2-yl)propane]dihydrochloride, 2,2'-Azobis [2-(5-hydroxy-3,4,5,6-tetrahydropyrimidin-2-yl)propane]dihydrochloride, 2,2'-azobis{2-[1-(2-hydroxyethyl)-2-imidazolin-2-yl]propane}dihydrochloride, 2,2'-azobis[2-(2-imidazolin-2-yl)propane], 2,2'-azobis{2-methyl-N-[1, Examples of azo compounds include, but are not limited to, 2,2'-azobis{2-methyl-N-[1,1-bis(hydroxymethyl)ethyl]propionamide}, 2,2'-azobis[2-methyl-N-(2-hydroxyethyl)propionamide], 2,2'-azobis(2-methylpropionamide), 2,2'-azobis(2,4,4-trimethylpentane), 2,2'-azobis(2-methylpropane), dimethyl-2,2-azobis(2-methylpropionate), 4,4'-azobis(4-cyanopentanoic acid), 2,2'-azobis[2-(hydroxymethyl)propionitrile], and 2,2'-azobis(tert-butane). Although not a peroxide, 2,3-dimethyl-2,3-diphenylbutane can also be used as (h). These may be used alone or in combination of two or more. Among these, α,α'-bis(t-butylperoxy-m-isopropyl)benzene and 2,2'-azobis(2,4,4-trimethylpentane) are preferably used. α,α'-bis(t-butylperoxy-m-isopropyl)benzene and 2,2'-azobis(2,4,4-trimethylpentane) have a relatively high reaction initiation temperature and excellent storage stability.

[0070] The amount of the radical polymerization initiator (h) to be added is in the range of 0.01 to 10 parts by weight, preferably 0.1 to 8 parts by weight, per 100 parts by weight of the polyfunctional vinyl aromatic copolymer. Within this range, the curing reaction proceeds smoothly without being inhibited.

[0071] The curable resin composition can contain a known curable reactive resin or thermoplastic resin (j). Examples of curable reactive resins include thermosetting resins and resins or compounds that copolymerize with a soluble polyfunctional vinyl aromatic copolymer to produce a cured resin. Examples include vinyl ester resins, polyvinylbenzyl resins, unsaturated polyester resins, curable vinyl resins, polyphenylene ether resins, maleimide resins, epoxy resins, polycyanate resins, phenolic resins, and one or more vinyl compounds having one or more polymerizable unsaturated hydrocarbon groups in the molecule. Examples of thermoplastic resins include polystyrene, polyphenylene ether resin, polyetherimide resin, polyethersulfone resin, PPS resin, polycyclopentadiene resin, polycycloolefin resin, etc., known thermoplastic elastomers such as styrene-ethylene-propylene copolymer, styrene-ethylene-butylene copolymer, styrene-butadiene copolymer, styrene-isoprene copolymer, hydrogenated styrene-butadiene copolymer, hydrogenated styrene-isoprene copolymer, etc., and rubbers such as polybutadiene and polyisoprene. The amount of the curable reactive resin or thermoplastic resin to be blended can be in the range of 10 to 90 parts by weight per 100 parts by weight of the total of the curable reactive resin and the polyfunctional vinyl aromatic copolymer, but is preferably less than 50 parts by weight, more preferably less than 30 parts by weight, and even more preferably less than 10 parts by weight.

[0072] The curable resin composition of the present invention may also contain a known flame retardant, which can be selected from a wide range of halogen-based flame retardants such as bromine-based flame retardants, and halogen-free flame retardants such as phosphate-based flame retardants, phosphazene-based flame retardants, and phosphinate-based flame retardants.

[0073] The curable resin composition of the present invention can be blended with a known filler. Specific examples include silica such as spherical silica, metal oxides such as alumina, titanium oxide, and mica, metal hydroxides such as aluminum hydroxide and magnesium hydroxide, talc, aluminum borate, barium sulfate, and calcium carbonate. These fillers may be used as they are, or may be surface-treated with a silane coupling agent such as an epoxy silane or amino silane. The filler content is, for example, 10 to 200 parts by mass per 100 parts by mass of the organic component.

[0074] The curable resin composition of the present invention may further contain other additives, such as antifoaming agents such as silicone-based antifoaming agents and acrylate-based antifoaming agents, heat stabilizers, antistatic agents, ultraviolet absorbers, dyes and pigments, lubricants, and dispersants such as wetting and dispersing agents.

[0075] When producing a prepreg, the curable resin composition of the present invention can be prepared into a varnish form to be used as a resin varnish for the purpose of impregnating a substrate (fibrous substrate) for forming a prepreg, or for the purpose of using the composition as a circuit board material for forming a circuit board.

[0076] The resin varnish is prepared by dissolving a polyfunctional vinyl aromatic copolymer in an organic solvent. Examples of organic solvents include ketones such as acetone, methyl ethyl ketone, and methyl isobutyl ketone; esters such as ethyl acetate, propyl acetate, and butyl acetate; polar solvents such as dimethylacetamide and dimethylformamide; and aromatic hydrocarbon solvents such as toluene and xylene. These solvents can be used alone or in combination. From the viewpoint of dielectric properties, aromatic hydrocarbons such as benzene, toluene, and xylene are preferred. The amount of organic solvent used in preparing the resin varnish is preferably 5 to 900% by weight based on 100% by weight of the curable resin composition of the present invention.

[0077] The cured product obtained by curing the curable resin composition of the present invention can be used as a molded product, laminate, cast product, adhesive, coating, or film. For example, a cured product of a semiconductor encapsulating material is a cast product or molded product. A cured product for such applications can be obtained by casting the curable resin composition or molding it using a transfer molding machine, injection molding machine, or the like, and then heating it at 80 to 230°C for 0.5 to 10 hours. A cured product of a circuit board varnish is a laminate. This cured product can be obtained by impregnating a substrate such as glass fiber, carbon fiber, polyester fiber, polyamide fiber, alumina fiber, or paper with the varnish, heating and drying the substrate to obtain a prepreg, which can then be laminated alone or with a metal foil such as copper foil and hot-press molded.

[0078] By incorporating an inorganic high dielectric powder such as barium titanate or an inorganic magnetic material such as ferrite into a curable resin composition or resin varnish, the composition becomes an excellent material for electronic parts, particularly for high frequency electronic parts.

[0079] The curable composite material of the present invention includes a substrate to enhance mechanical strength and dimensional stability. Known substrates can be used, including, for example, various glass fabrics such as roving cloth, cloth, chopped mat, and surfacing mat, asbestos cloth, metal fiber fabric, and other synthetic or natural inorganic fiber fabrics; woven or nonwoven fabrics obtained from liquid crystal fibers such as wholly aromatic polyamide fiber, wholly aromatic polyester fiber, and polybenzozal fiber; woven or nonwoven fabrics obtained from synthetic fibers such as polyvinyl alcohol fiber, polyester fiber, and acrylic fiber; natural fiber fabrics such as cotton cloth, linen cloth, and felt; carbon fiber cloth; and natural cellulose fabrics such as kraft paper, cotton paper, and paper-glass fiber blend paper. These fabrics and papers can be used alone or in combination of two or more.

[0080] The proportion of the substrate in the curable composite material is 5 to 90% by weight, preferably 10 to 80% by weight, and more preferably 20 to 70% by weight.

[0081] The curing, or molding and curing, of the curable resin composition or curable composite material of the present invention may be carried out, for example, at a temperature of 80 to 300°C and a pressure of 0.1 to 1000 kg / cm. ２ , time ranges from 1 minute to 10 hours, more preferably, temperature is 150 to 250°C, pressure is 1 to 500 kg / cm ２ The time can be in the range of 1 minute to 5 hours.

[0082] The laminate of the present invention is composed of a layer of the cured composite material of the present invention and a layer of metal foil. Examples of metal foil include copper foil, stainless steel foil, titanium foil, and aluminum foil. The thickness of the metal foil is not particularly limited, but is in the range of 3 to 200 μm, and more preferably 3 to 100 μm.

[0083] The curable resin composition of the present invention can also be formed into a film, and the thickness thereof is also in the range of, for example, 3 to 200 μm, more preferably 5 to 100 μm.

[0084] The polyfunctional vinyl aromatic copolymer of the present invention can be processed into molding materials, sheets, or films, and can be used as low-dielectric materials, insulating materials, heat-resistant materials, structural materials, etc., which satisfy properties such as low dielectric constant, low water absorption, and high heat resistance in fields such as the electrical industry, the aerospace and aircraft industry, and the automobile industry. It can be used particularly as single-sided, double-sided, and multilayer printed circuit boards, flexible printed circuit boards, build-up boards, etc. Furthermore, it can be used in semiconductor-related materials or optical materials, as well as paints, photosensitive materials, adhesives, sewage treatment agents, heavy metal scavengers, ion exchange resins, antistatic agents, antioxidants, antifogging agents, rust inhibitors, stain-resistant agents, fungicides, insect repellents, medical materials, flocculants, surfactants, lubricants, binders for solid fuels, conductive treatment agents, resin modifiers, asphalt modifier plasticizers, sintering binders, etc.

[0085] The curable resin composition of the present invention retains high dielectric properties (low dielectric constant and low dielectric dissipation factor) even after severe heat history, and gives a cured product with high adhesion reliability even under severe environments. It also has excellent resin fluidity, low linear expansion, and excellent wiring embedding flatness.

[0086] The present invention will now be described with reference to examples, but is not limited to these examples. All parts in the examples are by weight. Measurements of softening temperature and other properties in the examples were carried out by sample preparation and measurement according to the methods described below.

[0087] 1) Molecular weight and molecular weight distribution of polymer The molecular weight and molecular weight distribution of the soluble polyfunctional aromatic copolymer were measured using GPC (HLC-8120GPC, manufactured by Tosoh Corporation) with tetrahydrofuran as the solvent, a flow rate of 1.0 ml / min, a column temperature of 38°C, and a calibration curve based on monodisperse polystyrene. 2) Polymer structure The molecular weight and molecular weight distribution of the soluble polyfunctional aromatic copolymer were measured using a JNM-LA600 nuclear magnetic resonance spectrometer manufactured by JEOL Ltd. １３ C-NMR and １ The results were determined by H-NMR analysis. １ The resonance line of tetramethylsilane was used as an internal standard. 3) Analysis of end groups The end groups were calculated as follows: １３ C-NMR and １ The amount of the specific structural unit introduced at the terminal was calculated from the data on the total amount of each structural unit introduced into the copolymer obtained by GC analysis in addition to the H-NMR measurement results, and the number of terminal groups of the specific structural unit contained in one molecule of the polyfunctional vinyl aromatic copolymer was calculated from the amount of the specific structural unit introduced at the terminal and the number average molecular weight obtained by the above GPC measurement.

[0088] 4) Glass transition temperature (Tg) of the cured product A solution of a polyfunctional vinyl aromatic copolymer dissolved in toluene was uniformly applied to a glass substrate so that the thickness after drying was 20 μm, and the coating was heated for 30 minutes over a 90-minute period using a hot plate and dried. The resin film obtained together with the glass substrate was placed in a TMA (thermomechanical analyzer) and heated to 220°C at a heating rate of 10°C / min under a nitrogen stream, and then further heated at 220°C for 20 minutes to remove the remaining solvent and harden the polyfunctional vinyl aromatic copolymer. After the glass substrate was allowed to cool to room temperature, an analytical probe was brought into contact with the sample in the TMA measuring device, and a scan measurement was performed from 30°C to 360°C at a heating rate of 10°C / min under a nitrogen stream, and the softening temperature was determined by the tangent method. 5) Heat Resistance Evaluation and Measurement of Heat Discoloration Resistance The heat resistance of the soluble polyfunctional vinyl aromatic copolymer was evaluated by placing the sample in a TGA (thermobalance) measuring device and scanning it from 30 ° C. to 400 ° C. at a heating rate of 10 ° C. / min under a nitrogen stream. The weight loss at 350 ° C. was measured as an index of heat resistance. To measure heat discoloration resistance, 6.0 g of soluble polyfunctional vinyl aromatic copolymer, 4.0 g of benzyl methacrylate, and 0.02 g of t-butylperoxy-2-ethylhexanoate (manufactured by NOF Corporation, Perbutyl O) were mixed and heated to 200 ° C. for 1 hour under a nitrogen stream to obtain a cured product. The amount of discoloration of the obtained cured product was visually confirmed, and the heat discoloration resistance was evaluated by classifying the product as follows: ○: no heat discoloration, △: pale yellow, ×: yellow. 6) Measurement of Compatibility The compatibility of the soluble polyfunctional vinyl aromatic copolymer with an epoxy resin was measured by dissolving 5.0 g of a sample in 10 g of methyl ethyl ketone (MEK) with 3.0 g of an epoxy resin (liquid bisphenol A type epoxy resin: Epicoat 828 manufactured by Japan Epoxy Resins Co., Ltd.) and 2.0 g of a phenol resin (melamine skeleton type phenolic resin: PS-6492 manufactured by Gun-ei Chemical Industry Co., Ltd.), and the transparency of the dissolved sample was visually confirmed and classified as ○: transparent, △: semi-transparent, ×: opaque or not soluble, thereby evaluating the compatibility.

[0089] Example 1: A polymerization reaction was carried out under a nitrogen atmosphere using a dried, nitrogen-purged, 500 ml three-necked glass flask. 298.6 ml of toluene and 2.0 mmol of trioctylaluminum were charged into a 500 ml three-necked glass flask, and aging was carried out at room temperature for 10 minutes. 1.0 mmol of (trimethyl)pentamethylcyclopentadienyltitanium was then charged, followed by 1.0 mmol of tris(pentafluorophenyl)boron, and aging was carried out at room temperature for 10 minutes. The flask was then kept at a constant temperature of 20°C. 0.0303 mol (3.58 g) of p-methylstyrene and 0.0303 mol (3.58 g) of methylstyrene were added. Divinylbenzene 0.0121 mol (1.58 g), Ethylvinylbenzene 0.0005 mol (0.04 g) A toluene solution containing the compound was added and the polymerization reaction was carried out at 20°C for 60 minutes. A small amount of methanol was added to terminate the polymerization reaction, and the polymerization solution was poured into a large amount of acidic methanol to precipitate the polymer. The obtained polymer was washed, filtered, dried, and weighed to obtain 6.35 g of Copolymer A (yield: 82.3 wt%).

[0090] The resulting copolymer A had a weight average molecular weight (Mw) of 12,900, a number average molecular weight (Mn) of 5,460 and a molecular weight distribution (Mw / Mn) of 2.36. １３ The syndiotacticity determined by C-NMR measurement was 95% or more in racemic pentad form. １３ C-NMR and １H-NMR analysis revealed that Copolymer A contained 28.2 mol% (30.2 wt%) of structural units derived from divinylbenzene, a total of 1.25 mol% (1.34 wt%) of structural units derived from ethylvinylbenzene, and 57.4 mol% (52.7 wt%) of structural units derived from 4-methylstyrene (including terminal structural units). The content of structural units derived from divinylbenzene with residual vinyl groups in Copolymer A was 70.5 mol% (68.5 wt%). TMA analysis of the cured product showed no clear Tg, and the softening temperature was 300°C or higher. TGA analysis showed a weight loss of 1.07 wt% at 350°C, a thermal discoloration resistance of good, and compatibility with epoxy resins of good. Copolymer A was soluble in toluene, xylene, and THF (100 g or more of Copolymer A dissolved in 100 g of each solvent), and no gel formation was observed.

[0091] Comparative Example 1 Divinylbenzene 3.0 mol (390.6 g), ethylvinylbenzene 1.8 mol (229.4 g), styrene 10.2 mol (1066.3 g), 15.0 mol (1532.0 g) of n-propyl acetate was charged into a 5.0 L reactor, and 600 mmol of a boron trifluoride diethyl ether complex was added at 70°C, followed by a reaction for 4 hours. The polymerization solution was terminated with an aqueous sodium bicarbonate solution, and the oil layer was washed three times with pure water. The mixture was then subjected to devolatilization under reduced pressure at 60°C, and the copolymer was recovered. The obtained copolymer was weighed, and it was confirmed that 896.7 g of copolymer B was obtained.

[0092] The copolymer B thus obtained had an Mn of 2,980, an Mw of 41,300, and an Mw / Mn of 13.9. １３ C-NMR and １H-NMR analysis revealed that Copolymer B contained 30.4 mol% (33.1 wt%) of structural units derived from divinylbenzene, a total of 12.2 mol% (14.2 wt%) of structural units derived from ethylvinylbenzene, and 57.4 mol% (52.7 wt%) of structural units derived from styrene (including terminal structural units). The content of structural units derived from divinylbenzene with residual vinyl groups in Copolymer B was 23.9 mol% (25.9 wt%) (including terminal structural units). TMA analysis of the cured product showed no clear Tg, and the softening temperature was 300°C or higher. TGA analysis showed a weight loss of 1.83 wt% at 350°C, a thermal discoloration resistance of good, and compatibility with epoxy resins of good. Copolymer B was soluble in toluene, xylene, and THF (100 g or more of Copolymer B dissolved in 100 g of each solvent), and no gel formation was observed.

[0093] Comparative Example 2: 180 ml of toluene and 1.5 mmol of methylaluminoxane (based on aluminum atoms) were added to a 1.4 L reactor equipped with a stirrer, followed by 0.15 mmol of tetraethoxytitanium. The resulting solution was heated to 50°C, and 142.5 ml of styrene and a mixture of 66.1 wt% divinylbenzene-containing monomers (a mixture of m- and p-divinylbenzenes) and 7.5 ml of a mixture of 33.9 wt% ethyl sterenes (m- and p-divinylbenzenes) were added. The reaction was continued for 2 hours. Methanol was then added to terminate the reaction. A mixture of hydrochloric acid and methanol was then added to decompose the catalyst components. The yield of the resulting styrene copolymer C was 42.8 g. Furthermore, this styrene copolymer was washed with methyl ethyl ketone (containing 2 wt% p-tert-butylcatechol) at 50°C for 2 hours, revealing that 99% of the copolymer was insoluble. When this methyl ethyl ketone-insoluble styrene copolymer C was dissolved in chloroform, it was partially dissolved, and the chloroform-soluble component was separated to obtain a chloroform solution of styrene copolymer C. This chloroform-soluble styrene copolymer had a weight-average molecular weight of 360,000, a number-average molecular weight of 110,000, and a melting point of 240°C. The styrene copolymer C was a heat-reactive styrene copolymer C having a syndiotactic structure,１３ C-NMR and １ H-NMR analysis revealed that Copolymer C contained 3.95 mol% (4.89 wt%) of structural units derived from divinylbenzene, a total of 0.18 mol% (0.22 wt%) of structural units derived from ethylvinylbenzene, and 95.9 mol% (94.9 wt%) of structural units derived from styrene (including terminal structural units). The content of structural units derived from divinylbenzene with residual vinyl groups contained in Copolymer C was 1.38 mol% (1.71 wt%). TMA measurement of the cured product showed no clear Tg, and the softening temperature was 300°C or higher. TGA measurement showed a weight loss of 2.83 wt% at 350°C and a thermal discoloration resistance of ○. On the other hand, compatibility with epoxy resins was rated ×. Copolymer C was insoluble in toluene, xylene, and THF (100 g or more of Copolymer C dissolved in 100 g of each solvent), and due to the high solvent-insoluble content, gel formation was not confirmed.

[0094] Using the copolymers A to C obtained in Example 1 and Comparative Examples 1 and 2, the varnishes of the curable resin compositions using these resins and the properties of the cured products were evaluated according to the following test methods.

[0095] 7) Solution Viscosity The viscosity of the varnish solution of the curable resin composition was measured using an E-type viscometer at a measurement temperature of 25°C. 8) Flexural Strength and Flexural Elongation at Break The test specimens used for the bending test were prepared by placing the varnish of the curable resin composition on the lower mold of a vacuum press molding machine, and then devolatilizing the solvent under heating and vacuum. The upper mold was then placed on the molded piece, and the piece was heated and pressed under vacuum, and held at 200°C for 1 hour to form a 1.0 mm thick plate. Test specimens measuring 5.0 mm wide, 1.0 mm thick, and 120 mm long were prepared from the molded plate, and a bending test was performed. The flexural strength and flexural elongation at break of the prepared test specimens were measured using a universal testing machine. The flexural strength and flexural elongation at break were evaluated as follows: ○ for values ​​less than ±10% of the measured value of the reference formulation, ◎ for values ​​10% or greater, △ for values ​​in the range of -10 to -20%, and × for values ​​less than -20%. 9) Linear expansion coefficient and glass transition temperature The test specimens used for the linear expansion coefficient and glass transition temperature tests were prepared by placing a varnish of the curable resin composition on a flat mold below a vacuum press molding machine, and then heating and degassing the solvent under vacuum. Then, a 0.2 mm spacer was sandwiched between the upper mold and the molded plate, and the upper mold was placed under vacuum. The heat press was performed under vacuum and held at 200 ° C. for 1 hour to form a 0.2 mm thick plate. A test specimen measuring 3.0 mm wide, 0.2 mm thick, and 40 mm long was prepared from the molded plate. The specimen was placed only on the upper chuck of a TMA (thermomechanical analyzer) and heated to 220 ° C. at a heating rate of 10 ° C. / min under a nitrogen stream. Further heat treatment at 220 ° C. for 20 minutes removed the remaining solvent and eliminated molding strain in the test specimen. After allowing the TMA to cool to room temperature, the lower side of the test piece in the TMA measuring device was also set on the analysis probe, and a scan measurement was performed from 30°C to 360°C at a heating rate of 10°C / min under a nitrogen stream, and the linear expansion coefficient was calculated from the dimensional change from 0 to 40°C. The glass transition temperature was measured by setting the above test piece in a DMA (dynamic mechanical analyzer) measuring device and scanning from 30°C to 320°C at a heating rate of 3°C / min under a nitrogen stream, and Tg was determined from the peak top of the tan δ curve.

[0096] 10) Dielectric constant and dielectric loss tangent In accordance with JIS C2565, the dielectric constant and dielectric loss tangent at 18 GHz were measured using a cavity resonator dielectric constant measuring device manufactured by AET Corporation after drying and then storing the cured product plate specimens in a room at 23°C and 50% humidity for 24 hours. The cured product plate specimens were then left at 85°C and 85% relative humidity for 2 weeks, after which the dielectric constant and dielectric loss tangent were measured. The dielectric constant and dielectric loss tangent were also measured after a moist heat resistance test. To confirm the high-temperature heat resistance of the material, the cured product plate specimens were left at 140°C in an air atmosphere for 168 hours, after which the dielectric constant and dielectric loss tangent were measured. The dielectric constant and dielectric loss tangent were also measured after a high-temperature heat resistance test.

[0097] 11) Copper foil peel strength A glass cloth (E glass, basis weight 71 g / m) was applied to a varnish of a thermosetting resin composition. ２ ) to perform impregnation, and then dried in an air oven at 80°C for 10 minutes. The resin content (R.C.) of the resulting prepreg was adjusted to 50 wt%. Using this prepreg, multiple sheets of the above curable composite material were stacked as needed to achieve a molded thickness of approximately 0.6 mm to 1.0 mm. 18 μm-thick copper foil (product name F2-WS copper foil, Rz: 2.0 μm, Ra: 0.3 μm) was placed on both sides of the stack, and the stack was molded and cured using a vacuum press molding machine to obtain a laminate for evaluation. The curing conditions were a temperature increase of 3°C / min, a pressure of 3 MPa, and a holding time of 60 minutes at 200°C, yielding a cured laminate as a copper-clad laminate for evaluation. A test piece 20 mm wide and 100 mm long was cut out from the obtained cured laminate, and a 10 mm wide parallel cut was made on the copper foil surface. The copper foil was then continuously peeled off in a direction 90° to the surface at a speed of 50 mm / min. The stress at this time was measured using a tensile tester, and the minimum stress value was recorded as the copper foil peel strength (in accordance with JIS C 6481). The copper foil peel strength test after the moist heat resistance test was performed by leaving the test piece at 85°C and a relative humidity of 85% for 2 weeks, and then measuring the strength in the same manner as above.

[0098] 12) Moldability: Using the copper-clad laminate for evaluation formed in the previous section, a core material was prepared by patterning it into a grid-like shape with a line width (L) of 0.5 mm and a line spacing (S) of 1.0 mm (L / S = 0.5 / 1.0 mm). This core material was blackened, and then a prepreg was laminated on top of it and secondary molded to prepare an evaluation laminate substrate with an inner layer of a grid pattern. The evaluation laminate substrate was then checked for defects such as voids due to insufficient fluidity of the resin varnish. The evaluation laminate substrate was then immersed in boiling water for 4 hours and then immersed in a solder bath at 280°C. A sample that showed no voids and no defects such as swelling, delamination, or measling (white spots) after immersion in the solder bath was evaluated as "Good," a sample that showed no defects but warpage was evaluated as "Good," and a sample that showed no defects was evaluated as "Poor," and a sample that showed no defects was evaluated as "Poor."

[0099] Example 2: 20 g of Copolymer-A obtained in Example 1, 0.1 g of 2,2'-azobis(2,4,4-trimethylpentane) as a polymerization initiator, and 0.04 g of AO-60 as a curing accelerator and antioxidant were dissolved in 8.6 g of toluene to obtain a curable resin composition (Varnish A). The prepared Varnish A was dropped onto the lower mold, and the solvent was devolatilized at 130°C under reduced pressure. The mold was then assembled and the mixture was subjected to a vacuum press at 200°C and 3 MPa for 1 hour to thermally cure. The resulting 0.2 mm-thick cured plate specimens were subjected to measurements of various properties, including the dielectric constant and dielectric loss tangent at 18 GHz. The cured plate specimens were left at 85°C and 85% relative humidity for two weeks, after which the dielectric constant and dielectric loss tangent were measured. The dielectric constant and dielectric loss tangent were also measured after a moist heat resistance test. The results of these measurements are shown in Table 1.

[0100] Comparative Examples 3 and 4 Curable resin compositions (varnishes) were obtained in the same manner as in Example 2, except that the formulations shown in Table 1 were used. Flat test pieces of the cured products were prepared in the same manner as in Example 2, and tests and evaluations were carried out for the same items as in Example 2. The results obtained from these tests are shown in Table 1.

[0101] In the tables, the solid content in the solution viscosity is 25% in Table 1. ND in the glass transition temperature indicates Tg-less. Dielectric constant 85 and dielectric dissipation factor 85 are the dielectric constant and dielectric dissipation factor after 2 weeks of storage at 85°C and 85 RH, respectively. Dielectric constant 140 and dielectric dissipation factor 140 are the dielectric constant and dielectric dissipation factor after 168 hours of storage at 140°C in air. Dielectric dissipation factor change rate 1 indicates humidity and heat resistance, and dielectric dissipation factor change rate 2 indicates heat resistance. In Tables 2 to 5, copper foil peel strength 85 is the measurement value after 2 weeks of storage at 85°C and 85 RH.

[0102]

[0103] The polyfunctional vinyl aromatic copolymer of the present invention can be processed into a molding material, sheet, or film, and is useful as a low dielectric material, insulating material, heat-resistant material, structural material, etc. that can satisfy properties such as low dielectric constant, low water absorption, and high heat resistance in fields such as the electrical industry, the aerospace and aircraft industry, and the automobile industry.

Claims

1. The following general formula (1) The copolymer contains 2 mol % or more and less than 95 mol % of repeating units (a) derived from a divinylaromatic compound (A) represented by the following general formula (2): In the formula, R1 represents a hydrocarbon group having 1 to 30 carbon atoms, a halogen atom, or a substituent containing at least one of an oxygen atom, a nitrogen atom, a sulfur atom, a phosphorus atom, a selenium atom, a silicon atom, and a tin atom, and m represents an integer of 0 to 5. However, when m is plural, each R1 may be the same or different. A polyfunctional vinyl aromatic copolymer containing 5 mol % or more and less than 98 mol % of repeating units (b) derived from a monovinyl aromatic compound (B) represented by the formula: １ The tacticity of carbon １３ The content of the unsaturated hydrocarbon group represented by the following formula (a1) is 2 mol % or more and less than 95 mol % based on the total of (a) and (b), and the content of the unsaturated hydrocarbon group represented by the following formula (a1) is 30 mol % or more based on the total of (a) and (b), In the formula, R2 represents an aromatic hydrocarbon group having 6 to 30 carbon atoms. The polyfunctional vinyl aromatic copolymer has a number average molecular weight (Mn) of 500 to 30,000, a molecular weight distribution (Mw / Mn) expressed as the ratio of the weight average molecular weight to the number average molecular weight of 20.0 or less, and is soluble in a solvent.

2. As the catalyst component (C), at least one transition metal compound selected from compounds represented by the following general formula (3) or (4), and MR ３ aR ４ bR ５ cX １ ４－（ａ＋ｂ＋ｃ） (3) MR ３ dR ４ eX １ 3-(d+e) (4) In the formula, R3, R4, and R5 each represent a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 20 carbon atoms, an alkylaryl group, an arylalkyl group, an acyloxy group having 1 to 20 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, a thioalkoxy group having 1 to 20 carbon atoms, a thioaryloxy group having 6 to 20 carbon atoms, a cyclopentadienyl group, a substituted cyclopentadienyl group, an indenyl group, a substituted indenyl group, a fluorenyl group, or a substituted fluorenyl group. M represents a transition metal selected from the group consisting of titanium (Ti), zirconium (Zr), and hafnium (Hf), and X1 represents a halogen atom. R3, R4, and R5 may be the same or different. Furthermore, a, b, and c each represent an integer from 0 to 4, and d and e each represent an integer from 0 to 3. a co-catalyst component (D) comprising a divinylaromatic compound (A) represented by the following general formula (1), in the presence of a reaction product with at least one compound selected from the group consisting of compounds represented by the following (d) to (g): (d) an organoaluminum oxy compound, (e) an ionic compound capable of reacting with the transition metal compound to produce a cationic transition metal compound, (f) a Lewis acid compound capable of reacting with the transition metal compound to produce a cationic transition metal compound, and (g) an organometallic compound of an element metal of Groups 1, 2, and 13 of the Periodic Table; and a monovinyl aromatic compound (B) represented by the following general formula (2): (In the formula, R1 represents a hydrocarbon group having 1 to 30 carbon atoms, a halogen atom, or a substituent containing at least one of an oxygen atom, a nitrogen atom, a sulfur atom, a phosphorus atom, a selenium atom, a silicon atom, and a tin atom, and m represents an integer of 0 to 5. However, when m is plural, each R １ may be the same or different.) Polymerization occurs at a temperature of 100°C or less, and C of the phenyl groups constituting (A) and (B) is １ The tacticity of carbon １３ A method for producing a polyfunctional vinyl aromatic copolymer, characterized by obtaining a polyfunctional vinyl aromatic copolymer having a racemic pentad content of 30% or more as determined by C-NMR.

3. A curable resin composition comprising the polyfunctional vinyl aromatic copolymer according to claim 1 and a radical polymerization initiator (h).

4. A curable resin composition comprising the polyfunctional vinyl aromatic copolymer according to claim 1 and a curable reactive resin (i) or a thermoplastic resin (j).

5. The curable resin composition according to claim 4, wherein the curable reactive resin (i) is a modified polyphenylene ether compound (ia) terminally modified with a substituent having a carbon-carbon unsaturated double bond, one or more epoxy resins (ib) selected from the group consisting of epoxy resins having two or more epoxy groups in one molecule, or one or more vinyl compounds (id) having one or more unsaturated hydrocarbon groups in the molecule.

6. A curable resin composition comprising the curable resin composition according to claim 3, further comprising a flame retardant (k) and / or a filler (l).

7. A cured product obtained by curing the curable resin composition according to any one of claims 3 to 6.

8. A curable composite material comprising the curable resin composition according to any one of claims 3 to 6 and a substrate, characterized in that the substrate is contained in an amount of 5 to 90% by weight.

9. A cured composite material obtained by curing the curable composite material according to claim 8.

10. A laminate comprising a layer of the cured composite material of claim 9 and a metal foil layer.

11. A resin-coated metal foil having a film formed from the curable resin composition according to any one of claims 3 to 6 on one side of the metal foil.

12. A varnish for circuit board materials, obtained by dissolving the curable resin composition according to any one of claims 3 to 6 in an organic solvent.

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