Multifunctional vinyl aromatic copolymer, method for producing the same, and curable resin composition and cured product thereof

Abstract

Provided is a novel multifunctional vinyl aromatic copolymer that improves reactivity, enables formation of a cured product or molded product that improves uniformity and mechanical properties in the cured product, and a production method therefor. The multifunctional vinyl aromatic copolymer, which is a multifunctional vinyl aromatic copolymer having structural units from a divinyl aromatic compound (a), structural units from an ester group-containing vinyl aromatic compound (b) represented by the following formula (1), and a monovinyl aromatic compound (c), is characterized by having a number average molecular weight of 300 to 100,000, a molecular weight distribution (Mw / Mn) represented by the ratio of weight average molecular weight to number average molecular weight of 100 or less, and being soluble in a solvent. In the formula, Ar 1 , Ar 2 Each independently is an aromatic ring group of either one of a benzene ring or a naphthalene ring, the aromatic rings including an ester group having 1 to 15 carbon atoms as a substituent in either or both of Ar 1 and Ar 2 .

Description

Technical Field

[0001] This invention relates to novel multifunctional vinyl aromatic copolymers and their manufacturing methods, as well as curable resin compositions containing the copolymers. Background Technology

[0002] With the increase in information and communication volume in recent years, high-frequency information and communication has become prevalent. In order to achieve better electrical characteristics, especially to reduce transmission loss in high-frequency bands, electrical insulation materials with low dielectric constant and low dielectric loss tangent are needed.

[0003] Conventional thermosetting resins such as phenolic resins, epoxy resins, and polyimide resins have been used in printed wiring boards. While these resins possess a variety of properties in a balanced manner, their dielectric properties in the high-frequency region are insufficient. As a novel material addressing this problem, resin compositions comprising a free radical polymerizable compound and an epoxy resin have been disclosed (Patent Documents 1 and 2).

[0004] However, the resin compositions containing epoxy resin and free radical polymerizable compounds disclosed in Patent Documents 1 and 2 form two types of 3D networks in the cured product because each undergoes a crosslinking reaction independently. Therefore, phase separation occurs in the cured product, and sufficient crosslinking density is not achieved, making it difficult to exhibit high mechanical properties. Thus, there is a problem of not increasing the amount of vinyl resin with excellent dielectric properties in the formulation.

[0005] Patent Document 3 discloses a polyfunctional vinyl aromatic copolymer having structural units derived from divinyl aromatic compounds as a free radical polymerizable compound. This polyfunctional vinyl aromatic copolymer, due to its own polymerizable double bonds, forms a cured product with a high glass transition temperature upon curing. Therefore, this cured product or polyfunctional vinyl aromatic copolymer can be considered a polymer or precursor with excellent heat resistance. Furthermore, when this polyfunctional vinyl aromatic copolymer is copolymerized with other free radical polymerizable monomers to form a cured product, this cured product also becomes a polymer with excellent heat resistance. However, this copolymer is a compound that only possesses free radical polymerizable properties and does not react with epoxy resins.

[0006] Existing technical documents

[0007] Patent documents

[0008] Patent Document 1: Japanese Patent No. 7263069

[0009] Patent Document 2: Japanese Patent Application Publication No. 2015-48458

[0010] Patent Document 3: International Publication No. 2018 / 181842 Summary of the Invention

[0011] This invention investigates compositions of vinyl resins, particularly epoxy resins, and vinyl resins, with the aim of providing novel multifunctional vinyl aromatic copolymers and methods for their manufacture that can improve reactivity and form cured products or molded articles with improved uniformity and mechanical properties.

[0012] In order to solve the above-mentioned problems, the inventors conducted in-depth research and found that: in a resin composition of a novel polyfunctional vinyl aromatic copolymer with specific active ester groups and epoxy resin, reactivity can be improved, the uniformity of the cured product can be increased, and excellent mechanical properties can be achieved, thus completing the present invention.

[0013] That is, the present invention is a multifunctional vinyl aromatic copolymer, which is a multifunctional vinyl aromatic copolymer obtained by using 2 mol% or more but less than 95 mol% of a divinyl aromatic compound (a), 2 mol% or more but less than 93 mol% of a vinyl aromatic compound containing an ester group represented by the following formula (1) (b), and 5 mol% or more but less than 96 mol% of structural units from a monovinyl aromatic compound (c), characterized in that the copolymer contains a structural unit from the divinyl aromatic compound (a) represented by the following formula (a1), a structural unit from the vinyl aromatic compound (b) containing an ester group represented by the following formula (b1), has a number average molecular weight of 300 to 100,000, a molecular weight distribution (Mw / Mn) expressed as the ratio of weight average molecular weight to number average molecular weight of 100 or less, and is soluble in a solvent.

[0014]

[0015] In the formula, Ar 1 Ar 2 Each is an aromatic ring group that is independently either a benzene ring or a naphthalene ring, and these aromatic rings are in Ar 1 and Ar 2 Both or either of them contain an ester group with 1 to 15 carbon atoms as a substituent, and may have an alkyl group with 1 to 10 carbon atoms, an alkoxy group with 1 to 10 carbon atoms, an aryl group with 6 to 11 carbon atoms, an aralkyl group with 7 to 12 carbon atoms, an aroxy group with 6 to 11 carbon atoms, or an aralkoxy group with 7 to 12 carbon atoms as a substituent. R 1 It is a divalent group that is directly bonded or selected from hydrocarbon groups with 1 to 20 carbon atoms, -CO-, -O-, -S-, -SO2-, and -C(CF3)2-. n is 0 to 1.

[0016]

[0017] In the formula, R 2 It represents aromatic hydrocarbon groups with 6 to 30 carbon atoms.

[0018]

[0019] In the formula, Ar 1 Ar 2 R 1 The symbols , n and are synonyms with those in equation (1).

[0020] The present invention relates to a method for manufacturing a multifunctional vinyl aromatic copolymer, which is a method for polymerizing a divinyl aromatic compound (a), a vinyl aromatic compound containing an ester group represented by formula (1) (b), and a monovinyl aromatic compound (c) in the presence of a Lewis acid catalyst to manufacture a multifunctional vinyl aromatic copolymer. The method is characterized in that, relative to the sum of (a), (b), and (c), 2 mol% or more but less than 95 mol% of the divinyl aromatic compound (a), 2 mol% or more but less than 93 mol% of the vinyl aromatic compound containing an ester group represented by formula (1) below, and 5 mol% or more but less than 96 mol% of the monovinyl aromatic compound (c) are used, and polymerized at a temperature of -20 to 120°C.

[0021] In the manufacturing method, the Lewis acid catalyst (f) is preferably a metal fluoride or its complex.

[0022] Furthermore, the present invention is a curable resin composition, characterized in that it contains a multifunctional vinyl aromatic copolymer and a free radical polymerization initiator.

[0023] Also a curable resin composition, characterized by containing a polyfunctional vinyl aromatic copolymer and an epoxy resin. The epoxy resin preferably has two or more epoxy groups per molecule.

[0024] In the case of the multifunctional vinyl aromatic copolymer of the present invention, the active ester group and epoxy group contained in the structural unit represented by formula (b1) of the vinyl aromatic compound (b) containing ester group represented by formula (1) can undergo crosslinking reaction, and further, can also undergo crosslinking reaction caused by free radical polymerization of vinyl groups. Therefore, the uniformity and mechanical properties of the cured multifunctional vinyl aromatic copolymer of the present invention are improved. Attached Figure Description

[0025] Figure 1 The image shows the IR spectrum of the multifunctional vinyl aromatic copolymer of Example 1.

[0026] Figure 2 This is a GPC diagram of the multifunctional vinyl aromatic copolymer of Example 1. Detailed Implementation

[0027] The multifunctional vinyl aromatic copolymer of the present invention contains structural units from divinyl aromatic compounds (a), and contains structural units from vinyl aromatic compounds (b) containing ester groups represented by formula (1), and contains structural units from monovinyl aromatic compounds (c).

[0028] The number-average molecular weight Mn is 300 to 100,000, and the molecular weight distribution (Mw / Mn), expressed by the ratio of weight-average molecular weight Mw to number-average molecular weight Mn, is less than 100. It is soluble in solvents.

[0029] The structural units referred to in this specification include repeating units present in the main chain of the copolymer and units or terminal groups present at the ends or side chains.

[0030] The vinyl group constituting formula (a1) from divinyl aromatic compound (a) acts as a crosslinking component, contributing to the heat resistance of the multifunctional vinyl aromatic copolymer. On the other hand, it is believed that the structural units of vinyl aromatic compound (b) and monovinyl aromatic compound (c) containing ester groups represented by formula (1) are generally polymerized by 1,2 addition reaction of vinyl groups, so the vinyl group is not left behind and therefore does not act as a crosslinking component with vinyl groups.

[0031] With regard to the structural unit (b1) of the vinyl aromatic compound (b) containing the ester group represented by formula (1), the active ester group acts as a crosslinking component by reacting with the epoxy group, thus improving reactivity in the resin composition with epoxy resin, which helps to improve the uniformity and mechanical properties in the cured product.

[0032]

[0033] The structural units from the monovinyl aromatic compound (c) do not function as crosslinking components with vinyl and epoxy groups, but are used to adjust to any active ester equivalent and vinyl equivalent, which helps to exhibit molding processability.

[0034] The structural unit from divinyl aromatic compound (a) contains more than 2 mol% and less than 95 mol% relative to the sum of the structural units from (a), (b) and (c). The structural unit from divinyl aromatic compound (a) can be a single-reaction structure with two vinyl groups, a two-reaction structure, or other structures.

[0035] Preferably, it contains 2 to 80 mol% of a repeating unit formed by reacting only one vinyl group, represented by formula (a1). More preferably, it contains 5 to 70 mol%, further preferably 10 to 60%, and particularly preferably 15 to 50%. By containing 2 to 80 mol%, it exhibits a low dielectric loss tangent, high toughness, excellent heat resistance, and excellent compatibility with other resins. In addition, when formulated into a resin composition, it exhibits excellent resistance to damp heat, resistance to heat oxidation degradation, and processability. If it is less than 2 mol%, the heat resistance tends to decrease; if it exceeds 80 mol%, the interlaminar peel strength tends to decrease when forming a laminate.

[0036]

[0037] The structural units of the vinyl aromatic compound (b) containing ester groups, represented by formula (1), contain more than 2 mol% and less than 93 mol% relative to the sum of the structural units from (a), (b), and (c). More preferably, 5 to 80 mol%, even more preferably 5 to 70 mol%, and particularly preferably 5 to 60 mol%. If less than 2 mol%, sufficient crosslinking density is not easily obtained in the resin composition with epoxy resin, and mechanical properties are not improved. If more than 93 mol%, the interlaminar peel strength tends to decrease when forming a laminate. The structural units of the vinyl aromatic compound (b) containing ester groups, represented by formula (1), are substantially all structural units represented by formula (b1).

[0038] The structural unit from the monovinyl aromatic compound (c) contains 5 mol% or more but less than 96 mol% relative to the sum of the structural units from (a), (b), and (c). Preferably, it is 10% to 80%, more preferably 15% to 70%. If the molar fraction of the structural units from (b) and (c) is less than 0.05, the molding processability is insufficient; if (c) exceeds 98%, the heat resistance of the cured product is insufficient.

[0039] The active ester equivalent (g / eq) of the multifunctional vinyl aromatic copolymer is preferably 150 to 6000, more preferably 200 to 5000, further preferably 250 to 4000, and particularly preferably 250 to 3000.

[0040] The vinyl equivalent (g / eq) of the multifunctional vinyl aromatic copolymer is preferably 200 to 5000, more preferably 250 to 4000, further preferably 300 to 3000, and particularly preferably 350 to 1500.

[0041] The number-average molecular weight (Mn: the number-average molecular weight converted from standard polystyrene as determined by gel permeation chromatography) of the multifunctional vinyl aromatic copolymer is preferably 300 to 100,000, more preferably 400 to 50,000, and even more preferably 500 to 10,000. If Mn is less than 300, the amount of monofunctional copolymer components contained in the multifunctional vinyl aromatic copolymer increases, and therefore the heat resistance of the cured product tends to decrease. In addition, if Mn exceeds 100,000, gelation is easily formed, and the viscosity increases, thus the processability tends to decrease.

[0042] The molecular weight distribution (Mw / Mn), expressed as the ratio of weight-average molecular weight (Mw: weight-average molecular weight converted from standard polystyrene determined by gel permeation chromatography) to Mn, is 100.0 or less, preferably 50.0 or less, more preferably 1.5 to 30.0, and most preferably 2.0 to 20.0. If Mw / Mn exceeds 100.0, the processing characteristics of the polyfunctional vinyl aromatic copolymer tend to deteriorate, and gelation tends to occur.

[0043] The multifunctional vinyl aromatic copolymer is soluble in solvents. In particular, it is soluble in organic solvents such as toluene, xylene, tetrahydrofuran, dichloroethane, or chloroform, and preferably in any of these solvents. For it to be a solvent-soluble multifunctional copolymer, a suitable degree of crosslinking is required, where a portion of the vinyl group of divinylbenzene remains uncrosslinked. Here, "solvent-soluble" means that, relative to 100g of solvent, the multifunctional vinyl aromatic copolymer dissolves at least 5g, more preferably at least 30g, and particularly preferably at least 50g.

[0044] Next, the method for manufacturing the multifunctional vinyl aromatic copolymer of the present invention will be described.

[0045] The method for manufacturing the multifunctional vinyl aromatic copolymer of the present invention is to polymerize a vinyl aromatic compound (a), a vinyl aromatic compound (b) represented by formula (1), and a monovinyl aromatic compound (c) in the presence of a Lewis acid catalyst to manufacture the multifunctional vinyl aromatic copolymer.

[0046] In this process, relative to the sum of (a), (b) and (c), more than 2 mol% and less than 95 mol% of divinyl aromatic compound (a), more than 2 mol% and less than 93 mol% of vinyl aromatic compound (b) represented by formula (1), and more than 5 mol% and less than 96 mol% of monovinyl aromatic compound (c) are used, and polymerization is carried out at a temperature of -20 to 120°C.

[0047] Divinyl aromatic compound (a) plays a role in forming a branched structure and becoming multifunctional, while also acting as a crosslinking component to exhibit heat resistance when the resulting multifunctional vinyl aromatic copolymer is thermocured.

[0048] As an example of a divinyl aromatic compound (a), there is no limitation as long as it is an aromatic compound having two vinyl groups; divinylbenzene (containing isomers at each position or mixtures thereof), divinylnaphthalene (containing isomers at each position or mixtures thereof), and divinylbiphenyl (containing isomers at each position or mixtures thereof) are preferred. Furthermore, these can be used alone or in combination of two or more. From the viewpoint of molding processability, divinylbenzene (meta-, para-, or mixtures of isomers thereof) is more preferred.

[0049] In the case of the vinyl aromatic compound (b) containing ester groups represented by formula (1), when the obtained multifunctional vinyl aromatic copolymer is thermocured together with epoxy resin, the active ester groups react with the epoxy groups to increase the crosslinking density, thereby playing a role in improving mechanical properties.

[0050]

[0051] The vinyl aromatic compounds (b) containing ester groups represented by formula (1) are each independently an aromatic ring group of either a benzene ring or a naphthalene ring, wherein the aromatic ring contains an ester group consisting of Ar-OC(=O)-R6 or Ar-C(=O)-O-R7 as a substituent in either Ar1 or Ar2. R6 represents a hydrocarbon group having 1 to 15 carbon atoms, and from the viewpoint of achieving a resin composition with excellent curing reaction with epoxy resin, the hydrocarbon group has a carbon number in the range of 1 to 15, preferably an alkyl group having 1 to 6 carbon atoms or an aryl group having 6 to 14 carbon atoms, more preferably an alkyl group having 1 to 3 carbon atoms or an aryl group having 6 to 10 carbon atoms. R7 is an aryl group having 6 to 14 carbon atoms, preferably an aryl group having 6 to 10 carbon atoms.

[0052] Ar1 or Ar2 may contain alkyl groups with 1 to 10 carbon atoms, alkoxy groups with 1 to 10 carbon atoms, aryl groups with 6 to 11 carbon atoms, aralkyl groups with 7 to 12 carbon atoms, aroxy groups with 6 to 11 carbon atoms, or aralkoxy groups with 7 to 12 carbon atoms as substituents.

[0053] R1 is a divalent group directly bonded to or selected from hydrocarbon groups having 1 to 20 carbon atoms, -CO-, -O-, -S-, -SO2-, and -C(CF3)2-.

[0054] n is 0 or 1.

[0055] Examples of vinyl aromatic compounds (b) represented by formula (1) include 4-acetoxystyrene, 3-acetoxystyrene, 3,4-diacetoxystyrene, monoacetoxymonovinylnaphthalene, diacetoxymonovinylnaphthalene, 4-vinylphenylbenzoate, 4-acetoxy-4'-vinylbiphenyl, 4-vinylphenyl naphthoate, 3-vinylphenyl naphthoate, 4-vinylphenyl anthracene, 3-vinylphenyl anthracene, 4-vinylbenzoate, 4-vinylphenyl naphthoate, etc.

[0056] Styrene containing ester groups, represented by the following formula (1a), is particularly preferred.

[0057]

[0058] In formula (1a), R6 represents a hydrocarbon group with 1 to 15 carbon atoms, and R4 represents an alkyl group with 1 to 10 carbon atoms, an alkoxy group with 1 to 10 carbon atoms, an aryl group with 6 to 11 carbon atoms, an aralkyl group with 7 to 12 carbon atoms, an aryloxy group with 6 to 11 carbon atoms, or an arylalkoxy group with 7 to 12 carbon atoms. m represents 1 to 3, and n represents 0 to 3.

[0059] Monovinyl aromatic compounds are monovinyl aromatic compounds other than those containing ester groups represented by formula (1) (c). They play a role in imparting low dielectric properties and resistance to heat and oxidation degradation to multifunctional vinyl aromatic copolymers, while also introducing vinyl groups at the ends of multifunctional vinyl aromatic copolymers.

[0060] Examples of monovinyl aromatic compounds (c) are not limited to any aromatic compound having one vinyl group, and examples include vinyl aromatic compounds such as styrene, vinylnaphthalene, and vinyl biphenyl; nucleoalkyl-substituted vinyl aromatic compounds such as o-methylstyrene, m-methylstyrene, p-methylstyrene, o, p-dimethylstyrene, o-ethylvinylbenzene, m-ethylvinylbenzene, and p-ethylvinylbenzene. These can be used alone or in combination of two or more.

[0061] Preferably, styrene is preferred from the perspective of preventing gelation of polyfunctional vinyl aromatic copolymers, improving solvent solubility and processability, low cost, and ease of acquisition. Furthermore, from the viewpoint of improving solvent solubility, processability, and dielectric properties, ethyl vinylbenzene (comprising isomers at various positions or mixtures thereof), ethyl vinylbiphenyl (comprising isomers at various positions or mixtures thereof), and ethyl vinylnaphthalene (comprising isomers at various positions or mixtures thereof) are preferred. More preferably, from the viewpoint of dielectric properties and cost, styrene and ethyl vinylbenzene (meta-, para-, or mixtures of isomers thereof) are preferred.

[0062] Without impairing the effects of the present invention, in addition to divinyl aromatic compounds (a), vinyl aromatic compounds containing ester groups represented by the above formula (1) (b), and monovinyl aromatic compounds (c), other monomeric components (d) such as trivinyl aromatic compounds, trivinyl aliphatic compounds, divinyl aliphatic compounds, and monovinyl aliphatic compounds can be used to introduce structural units from other monomeric components (d) into the multifunctional vinyl aromatic copolymer.

[0063] Other monomeric components (d) include, for example, 1,3,5-trivinylbenzene, 1,3,5-trivinylnaphthalene, 1,2,4-trivinylcyclohexane, ethylene glycol diacrylate, butadiene, 1,4-butanediol divinyl ether, cyclohexanediethanol divinyl ether, diethylene glycol divinyl ether, and triallyl isocyanurate. These can be used alone or in combination of two or more.

[0064] The molar fraction of the other monomeric component (d) relative to the sum of all monomeric components (a), (b), (c) and (d) is preferably less than 30 mol%. That is, the molar fraction of the repeating unit from the other monomeric component (d) relative to the sum of the structural units from all monomeric components (a), (b), (c) and (d) constituting the copolymer is preferably less than 30 mol.

[0065] If needed, other monomers such as hydroxyl-containing vinyl compounds (e) such as hydroxyethyl (meth)acrylate and hydroxypropyl (meth)acrylate can be used to introduce structural units from (e) into multifunctional vinyl aromatic copolymers.

[0066] The molar fraction of the hydroxyl-containing vinyl compound (e) relative to the sum of all monomer components (a), (b), (c), (d), and (e) is preferably less than 10 mol%, more preferably less than 5 mol%. That is, the molar fraction of the structural unit (e) from the hydroxyl-containing vinyl compound (e) relative to the sum of the structural units in the polyfunctional vinyl aromatic copolymer is preferably less than 10 mol%.

[0067] With regard to the proportions of the necessary monomer components (a), (b) and (c), relative to the sum of (a), (b) and (c), 2 mol% or more but less than 95 mol% of divinyl aromatic compound (a), 2 mol% or more but less than 93 mol% of vinyl aromatic compound (b) containing ester group represented by formula (1), and a total of 5 mol% or more but less than 96 mol% of monovinyl aromatic compound (c) are used, and these monomer components (a), (b) and (c) are polymerized at a temperature of -20 to 120°C.

[0068] The preferred amount of the divinyl aromatic compound (a) is 5 to 80 mol%, more preferably 7 to 70 mol%, and even more preferably 10 to 60 mol%.

[0069] The amount of the vinyl aromatic compound (b) containing an ester group represented by formula (1) is preferably 2 to 80 mol%, more preferably 5 to 70 mol%, and even more preferably 5 to 60 mol%.

[0070] The total amount of the monovinyl aromatic compound (c) is preferably 5 to 90 mol%, more preferably 10 to 80 mol%, and particularly preferably 15 to 70 mol%.

[0071] Lewis acid catalysts (f) can be used without particular restriction as long as they are compounds composed of metal ions (acids) and ligands (bases) and can accept electron pairs. From the viewpoint of the thermal decomposition resistance of the obtained polyfunctional vinyl aromatic copolymers, metal fluorides or their complexes are preferred, particularly 2- to 6-valent metal fluorides or their complexes of B, Al, Ga, In, Si, Ge, Sn, Pb, Sb, Bi, Ti, W, Zn, Fe, and V. These catalysts can be used alone or in combination of two or more. From the viewpoint of controlling the molecular weight and molecular weight distribution of the obtained polyfunctional vinyl aromatic copolymers and their polymerization activity, boron trifluoride ether complexes are most preferred. Among the ethers used as ether complexes are diethyl ether, dimethyl ether, etc.

[0072] The Lewis acid catalyst (f) can be used in the range of 0.001 to 100 mol relative to the total of 100 mol of all monomer components, more preferably 0.01 to 50 mol. Most preferably, it is 0.1 to 20 mol. If it exceeds 100 mol, the polymerization rate increases excessively, making it difficult to control the molecular weight distribution. Conversely, if it is less than 0.001 mol, the polymerization rate decreases excessively, leading to increased costs and making it unsuitable for industrial implementation.

[0073] In the method for manufacturing the multifunctional vinyl aromatic copolymer of the present invention, one or more Lewis base compounds may be used as cocatalysts (g). Specific examples of Lewis base compounds include ester compounds such as propyl acetate, thioester compounds such as methyl mercaptopropionic acid, ketone compounds such as methyl ethyl ketone, amine compounds such as methylamine, ether compounds such as diethyl ether, thioether compounds such as diethyl sulfide, or phosphine compounds such as tripropylphosphine.

[0074] Among these, compounds selected from ester compounds, ketone compounds, and ether compounds are preferred from the perspective of synergistic action with Lewis acid catalyst (f) and the ability to easily control the polymerization rate and the molecular weight distribution of the polymer. One or more Lewis base compounds can be used.

[0075] In polymerization reactions, Lewis base compounds coordinate with Lewis acid catalysts (f) that act as counter anions, thereby controlling the interaction between the carbocations (active species) and counter anions, and thus regulating the relative reaction frequencies among monomers (a), (b), and (c), which also function as chain transfer agents. Typically, the addition of Lewis base compounds enhances the interaction between the carbocations (active species) and counter anions, thus inhibiting excessive insertion reactions in monomers (a), (b), and (c), facilitating chain transfer reactions following insertion reactions in monomers (a), (b), and (c), and making molecular weight control easier.

[0076] Besides Lewis base compounds, compounds containing hydroxyl groups can also be listed as cocatalysts. It is believed that hydroxyl-containing cocatalysts, during polymerization reactions, react with a Lewis acid catalyst (f) to generate a carbocation as the active species, which then reacts with the vinyl groups of monomers (a), (b), and (c) to carry out the polymerization reaction. Hydroxyl-containing cocatalysts can be used alone or in combination with Lewis base compounds.

[0077] As a cocatalyst containing hydroxyl groups, specifically, alcohol compounds represented by the following formula (2) can be listed as cocatalysts, such as aromatic compounds like 1-phenylethanol, 2-phenyl-2-propanol, 2-propanol, and hydrocarbon compounds like tert-butanol.

[0078]

[0079] In the formula, R3 and R4 each independently represent an alkyl group with 1 to 6 carbon atoms, or an aromatic hydrocarbon group with 6 to 30 carbon atoms. R5 represents hydrogen, an alkyl group with 1 to 6 carbon atoms, or an aromatic hydrocarbon group with 6 to 30 carbon atoms.

[0080] Among these, from the perspective of synergistic effect with Lewis acid catalyst (f) and easy control of polymerization rate and polymer molecular weight distribution, it is preferable to use one or more compounds selected from aromatic compounds. One or more of these hydroxyl-containing co-catalysts can be used.

[0081] Regarding the cocatalyst (g), when using a Lewis base compound, the amount is preferably 0.1 to 1000 moles, more preferably 1.0 to 500 moles, and particularly preferably 10 to 200 moles, relative to a total of 100 moles of all monomer components. When using a cocatalyst containing hydroxyl groups, the amount is preferably 0.1 to 1000 moles, more preferably 0.5 to 500 moles, and particularly preferably 1 to 200 moles, relative to a total of 100 moles of all monomer components.

[0082] If the polymerization rate is maintained within the above range, the selectivity of the reaction between monomers is improved while maintaining an appropriate polymerization rate, resulting in excellent productivity. At the same time, excessive increase or decrease in molecular weight is suppressed, resulting in a multifunctional vinyl aromatic copolymer with excellent molding and processability.

[0083] In terms of polymerization reactions, for example, a polymerization raw material containing a mixture of monomers is subjected to cationic copolymerization at a temperature of -20 to 120°C to obtain a copolymer.

[0084] Solvents can be added as needed. Organic solvents, which are compounds that substantially do not hinder cationic polymerization, can be used to dissolve the Lewis acid catalyst (f), co-catalyst (g), monomer components, and the resulting polyfunctional vinyl aromatic copolymer to form a homogeneous solution with a dielectric constant in the range of 2 to 15. These solvents can be used alone or in combination of two or more. If the dielectric constant of the solvent is less than 2, the molecular weight distribution becomes broad, which is therefore undesirable; if it exceeds 15, the polymerization rate decreases.

[0085] From the viewpoint of balancing polymerization activity and solubility, toluene, xylene, n-hexane, cyclohexane, methylcyclohexane, or ethylcyclohexane are particularly preferred as organic solvents. Regarding the amount of solvent used, considering the viscosity of the resulting polymerization solution and ease of heat removal, the concentration of the copolymer in the polymerization solution at the end of polymerization is determined to be 1–90 wt%, preferably 10–80 wt%, and particularly preferably 20–70 wt%. When the concentration is less than 1 wt%, the polymerization efficiency is low, leading to increased costs; if it exceeds 90 wt%, the molecular weight and molecular weight distribution of the resulting polyfunctional vinyl aromatic copolymer increase, resulting in reduced processability.

[0086] In the production of multifunctional vinyl aromatic copolymers, monomers (a), (b), and (c) must be polymerized at a temperature of -20 to 120°C. Preferably, the temperature is 0 to 110°C. Particularly preferred is 30 to 90°C. If the polymerization temperature exceeds 120°C, the selectivity of the reaction decreases, resulting in problems such as increased molecular weight distribution and gel formation. If polymerization is carried out at temperatures below -20°C, the catalytic activity is significantly reduced, thus requiring the addition of a large amount of catalyst.

[0087] There are no particular limitations on the method for recovering the polyfunctional vinyl aromatic copolymer after the polymerization reaction has stopped. Commonly used methods such as heating concentration, stripping, and precipitation with unsuitable solvents can be used.

[0088] Next, the curable resin composition of the present invention will be described.

[0089] The curable resin composition of the present invention contains the polyfunctional vinyl aromatic copolymer of the present invention (including the polyfunctional vinyl aromatic copolymer obtained by the manufacturing method of the present invention) and a free radical polymerization initiator (h) (also called a free radical polymerization catalyst). The free radical polymerization initiator can promote the crosslinking reaction of unsaturated groups and can effectively adjust the curing time and curing temperature.

[0090] As a free radical polymerization initiator (h), a known substance is used. Representative examples include benzoyl peroxide, cumene hydroperoxide, 2,5-dimethylhexane-2,5-dihydroperoxide, 2,5-dimethyl-2,5-di(tert-butylperoxy)hexyne-3, di-tert-butyl peroxide, tert-butylcumyl peroxide, α,α'-bis(tert-butylperoxy-m-isopropyl)benzene, 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane, dicumyl peroxide, di-tert-butylperoxyisophthalate, tert-butylperoxybenzoate, 2,2-bis(tert-butylperoxy)butane, 2,2-bis(tert-butylperoxy)octane, 2,5-dimethyl-2,5-di(benzoylperoxy)hexane, di(trimethylsilyl)peroxide, trimethylsilyltriphenylsilyl peroxide, etc., but are not limited to these. Additionally, although not a peroxide, 2,3-dimethyl-2,3-diphenylbutane can also be used as a free radical polymerization initiator (h). However, it is not limited to these examples. Among these, α,α'-bis(tert-butylperoxy-m-isopropyl)benzene is preferred. α,α'-bis(tert-butylperoxy-m-isopropyl)benzene has a relatively high reaction initiation temperature. Therefore, it can suppress the promotion of curing reactions at times when curing is not required, such as when the prepreg material is drying, and can suppress the decrease in the shelf life of the curable resin composition of the present invention. Furthermore, α,α'-bis(tert-butylperoxy-m-isopropyl)benzene has low volatility, so it does not volatilize during the drying and storage of the prepreg material, and has good stability. In addition, the free radical polymerization initiator (h) can be used alone or in combination of two or more.

[0091] The amount of the free radical polymerization initiator (h) in the formulation is preferably in the range of 0.01 to 10 parts by weight relative to 100 parts by weight of the multifunctional vinyl aromatic copolymer, and more preferably in the range of 0.1 to 8 parts by weight. If it is within this range, the curing reaction will not be hindered, and the reaction will proceed well.

[0092] Furthermore, the curable resin composition of the present invention is also a resin composition comprising the polyfunctional vinyl aromatic copolymer and epoxy resin of the present invention.

[0093] Epoxy resins are preferably epoxy resins having two or more epoxy groups within their molecules. Examples include bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, bisphenol AF type epoxy resin, bisphenol Z type epoxy resin, bisphenol fluorene type epoxy resin, diphenyl sulfide type epoxy resin, diphenyl ether type epoxy resin, naphthalene type epoxy resin, hydroquinone type epoxy resin, resorcinol type epoxy resin, phenolic varnish type epoxy resin, cresol phenolic varnish type epoxy resin, and alkylphenolic varnish type epoxy resin. Epoxy resins include various types such as styrene-phenolic varnish epoxy resins, bisphenolic varnish epoxy resins, naphthol-phenolic varnish epoxy resins, phenolic alkyl epoxy resins, β-naphtholic alkyl epoxy resins, naphthyldiolic alkyl epoxy resins, α-naphtholic alkyl epoxy resins, biphenylic alkylphenol epoxy resins, biphenyl epoxy resins, triphenylmethane epoxy resins, dicyclopentadiene epoxy resins, alkylene glycol epoxy resins, and aliphatic cyclic epoxy resins.

[0094] The resin composition comprising the multifunctional vinyl aromatic copolymer and epoxy resin of the present invention may further comprise a free radical polymerization initiator for the purpose of promoting the crosslinking reaction of unsaturated groups. Examples of free radical polymerization initiators include the substances described above.

[0095] The resin composition comprising the multifunctional vinyl aromatic copolymer and epoxy resin of the present invention may further comprise an organic base. By comprising an organic base, the curing reaction with the epoxy group can be promoted, and the curing time and curing temperature can be effectively adjusted. As the organic base, it is preferable to use one or more of conventionally known amine curing accelerators, organophosphorus curing accelerators, and imidazole curing accelerators as curing accelerators for epoxy resins.

[0096] When a resin composition comprising the multifunctional vinyl aromatic copolymer and epoxy resin of the present invention contains a free radical polymerization initiator, the amount of the free radical polymerization initiator is preferably in the range of 0.01 to 10 parts by weight relative to 100 parts by weight of the resin component in the resin composition, and more preferably in the range of 0.05 to 8 parts by weight.

[0097] When the resin composition comprising the multifunctional vinyl aromatic copolymer and epoxy resin of the present invention contains an organic base, the amount of the organic base is preferably in the range of 0.01 to 10 parts by weight, more preferably in the range of 0.1 to 8 parts by weight, relative to 100 parts by weight of the resin component in the resin composition.

[0098] In resin compositions comprising the multifunctional vinyl aromatic copolymer of the present invention and epoxy resin, curing agents for epoxy resin can be formulated in addition to the multifunctional vinyl aromatic copolymer of the present invention. There are no particular limitations on the curing agent for epoxy resin; generally, any substance known as an epoxy resin curing agent can be used. From the viewpoint of improving heat resistance, preferred curing agents include phenolic curing agents, amide curing agents, imidazole curing agents, and reactive ester curing agents. These curing agents can be used individually or in combination of two or more.

[0099] From the viewpoint of improving both low dielectric constant and low dielectric loss tangent, preferred curing agents include reactive ester-based curing agents. Examples of preferred curing agents include phenolic esters, thiophenolic esters, N-hydroxyamine esters, and heterocyclic hydroxyl esters, which are compounds having two or more highly reactive ester groups per molecule. Phenolic esters that react carboxylic acid compounds with aromatic compounds having phenolic hydroxyl groups are more preferred. Specifically, examples of carboxylic acid compounds include benzoic acid, acetic acid, succinic acid, maleic acid, itaconic acid, phthalic acid, isophthalic acid, terephthalic acid, and pyromellitic acid.

[0100] Examples of aromatic compounds with phenolic hydroxyl groups include catechol, 1,5-dihydroxynaphthalene, 1,6-dihydroxynaphthalene, 2,6-dihydroxynaphthalene, dihydroxybenzophenone, trihydroxybenzophenone, tetrahydroxybenzophenone, phloroglucinol, pyroglucinol, dicyclopentadienyldiphenol, and phenolic varnish.

[0101] In the curable resin composition, known curable reactive resins or thermoplastic resins can be further compounded. As curable reactive resins, in addition to thermosetting resins, there are resins or compounds that copolymerize with polyfunctional vinyl aromatic copolymers to form cured resins. Examples include vinyl ester resins, polyvinyl benzyl resins, unsaturated polyester resins, curable vinyl resins, curable polyphenylene ether resins, maleimide resins, polycyanate resins, phenolic resins, and one or more vinyl compounds having one or more polymerizable unsaturated hydrocarbon groups in their molecules.

[0102] Examples of thermoplastic resins include, for example, polystyrene, polyphenylene ether resin, polyetherimide resin, polyethersulfone resin, PPS resin, polycyclopentadiene resin, polycycloolefin resin, phenoxy resin, etc.; known thermoplastic elastomers include, for example, styrene-ethylene-propylene copolymer, styrene-ethylene-butene copolymer, styrene-butadiene copolymer, styrene-isoprene copolymer, hydrogenated styrene-butadiene copolymer, hydrogenated styrene-isoprene copolymer, etc.; or rubbers, such as polybutadiene and polyisoprene.

[0103] From the viewpoint of dielectric properties, heat resistance, adhesion, and compatibility with polyfunctional vinyl aromatic copolymers, the following are preferably examples of curable reactive resins: polyvinyl benzyl resin, curable vinyl resin, curable polyphenylene ether resin, and one or more vinyl compounds having one or more polymerizable unsaturated hydrocarbon groups in their molecules. As thermoplastic resins, polystyrene, polyphenylene ether resin, styrene-ethylene-propylene copolymer, styrene-ethylene-butene copolymer, styrene-butadiene copolymer, styrene-isoprene copolymer, hydrogenated styrene-butadiene copolymer, and hydrogenated styrene-isoprene copolymer. More preferably, as curable reactive resins, polyvinyl benzyl resin, curable polyphenylene ether resin, epoxy resin, and one or more vinyl compounds having one or more polymerizable unsaturated hydrocarbon groups in their molecules are examples. As thermoplastic resins (j), polyphenylene ether resin and hydrogenated styrene-butadiene copolymer are examples.

[0104] When the curable reactive resin is a curable polyphenylene ether-based resin, a modified polyphenylene ether compound having a curable terminal functional group is more preferred. A modified polyphenylene ether compound containing an unsaturated hydrocarbon group is even more preferred. This refers to a modified polyphenylene ether compound whose terminal modification is performed using a substituent having a carbon-carbon unsaturated double bond. Most preferably, the substituent having the aforementioned carbon-carbon unsaturated double bond is a modified polyphenylene ether compound having a curable terminal functional group selected from vinylbenzyl, vinyl, acrylate, and methacrylate substituents.

[0105] There is no particular limitation on the average number of unsaturated hydrocarbon groups (terminal functional groups) per molecule of a modified polyphenylene ether compound containing unsaturated hydrocarbon groups at the ends. Preferably, from the viewpoint of balancing the heat resistance of the cured product and the storage stability and flowability of the cured resin composition, 1 to 5 is preferred, more preferably 1 to 3, and even more preferably 1.5 to 3.

[0106] There is no particular limitation on the Mn content of the cured polyphenylene ether resin, but it is preferably 500 to 7000, more preferably 800 to 5000, and most preferably 1000 to 3000. It should be noted that the Mn content can be any value determined by a common molecular weight determination method, such as the value determined by gel permeation chromatography (GPC).

[0107] If the Mn of the curable polyphenylene ether resin is within such a range, the cured product of the resulting curable resin composition exhibits higher toughness and moldability. This is because if the number-average molecular weight of the curable polyphenylene ether resin is within such a range, the relatively low molecular weight maintains toughness while improving flowability. With conventional polyphenylene ethers, the use of such low molecular weight polyphenylene ethers tends to reduce the heat resistance and toughness of the cured product. However, since the curable polyphenylene ether resin has polymerizable unsaturated double bonds at the ends, crosslinking can be appropriately achieved by copolymerizing or curing with a vinyl-based curable resin such as the copolymer of the present invention, resulting in a cured product with sufficiently high heat resistance and toughness. Therefore, it is possible to obtain a cured product with excellent heat resistance and toughness from the resulting curable resin composition.

[0108] The curable reactive resin is not particularly limited to one or more vinyl compounds (id) having one or more polymerizable unsaturated hydrocarbon groups in the molecule. That is, (id) is any substance that can be cross-linked and cured by reacting with the polyfunctional vinyl aromatic copolymer of the present invention. More preferably, the polymerizable unsaturated hydrocarbon group is a carbon-carbon unsaturated double bond, and more preferably, it is a compound having two or more carbon-carbon unsaturated double bonds in the molecule.

[0109] The vinyl compounds used as curable reactive resins preferably have a weight-average molecular weight (Mw) of 100 to 5000, more preferably 100 to 4000, and even more preferably 100 to 3000. If Mw is less than 100, it is possible that the id (mw) will easily volatilize from the compounding system of the curable resin composition. In addition, if Mw exceeds 5000, the viscosity of the varnish of the curable resin composition and the melt viscosity during heat molding may increase excessively. Therefore, if the Mw (mw) is within such a range, a curable resin composition with excellent heat resistance of the cured product is obtained. This is believed to be because cross-linking can be appropriately formed through the reaction of the polyfunctional vinyl aromatic copolymer with (mw). Here, Mw is only required to be a value determined by a general molecular weight determination method, specifically, a value determined by gel permeation chromatography (GPC), etc.

[0110] The average number of carbon-carbon unsaturated double bonds per molecule of vinyl compounds used as curable reactive resins (the number of terminal double bonds) varies depending on Mw, and is preferably 1 to 20, more preferably 2 to 18. If the number of terminal double bonds is too small, it tends to be difficult to obtain sufficient heat resistance as a cured product. On the other hand, if the number of terminal double bonds is too large, the reactivity will be excessively increased, which may lead to adverse conditions such as reduced shelf life of the cured resin composition or reduced flowability of the cured resin composition.

[0111] Examples of vinyl compounds (id) used as curable reactive resins include triallenyl isocyanurate compounds such as triallenyl isocyanurate (TAIC), polyfunctional methacrylate compounds having two or more methacryloyl groups in their molecules, polyfunctional acrylate compounds having two or more acryloyl groups in their molecules, vinyl compounds (polyfunctional vinyl compounds) such as polybutadiene having two or more vinyl groups in their molecules, and vinyl benzyl compounds such as styrene and divinylbenzene having vinyl benzyl groups in their molecules. Among these, compounds having two or more carbon-carbon double bonds in their molecules are preferred. Specifically, examples include triallenyl isocyanurate compounds, polyfunctional acrylate compounds, polyfunctional methacrylate compounds, polyfunctional vinyl compounds, and divinylbenzene compounds. Using these compounds is considered to more effectively form crosslinks through the curing reaction, further improving the heat resistance of the cured resin composition. These compounds can be used alone or in combination of two or more. Compounds having one carbon-carbon unsaturated double bond in their molecules can be used in combination. Compounds that have one carbon-carbon unsaturated double bond in their molecule include compounds that have one vinyl group (monovinyl compounds), etc.

[0112] The content of the multifunctional vinyl aromatic copolymer is preferably 30 to 90 parts by mass, more preferably 50 to 90 parts by mass, relative to the total of 100 parts by mass of the multifunctional vinyl aromatic copolymer and the vinyl compound (id) as a curable reactive resin. The content of the vinyl compound (id) as a curable reactive resin is preferably 10 to 70 parts by mass, more preferably 10 to 50 parts by mass, relative to the total of 100 parts by mass of the multifunctional vinyl aromatic copolymer and (id). That is, the content ratio of the multifunctional vinyl aromatic copolymer to the vinyl compound (id) as a curable reactive resin, expressed as a mass ratio, is preferably 90:10 to 30:70, more preferably 90:10 to 50:50. If the above-mentioned ratio is satisfied, it becomes a curable resin composition with superior heat resistance and flame retardancy of the cured product. This is believed to be because the curing reaction between the multifunctional vinyl aromatic copolymer and the vinyl compound (id) as a curable reactive resin proceeds suitably.

[0113] In the curable resin composition of the present invention, a known flame retardant (k) can be incorporated. Using the flame retardant (k) further improves the flame retardancy of the cured resin composition. There is no particular limitation on the flame retardant (k). Specifically, in the field of using halogenated flame retardants such as bromine-based flame retardants, ethylene bis(pentabromobenzene), ethylene bis(tetrabromoimide), decabromodiphenyl ether, and tetradecylbromodiphenoxybenzene with melting points of 300°C or higher are preferred. It is believed that by using halogenated flame retardants, the release of halogens at high temperatures can be suppressed, thereby preventing a decrease in heat resistance.

[0114] In fields requiring halogen-free properties, phosphate ester-based flame retardants, phosphazene-based flame retardants, and phosphinate-based flame retardants can be cited. Specific examples of phosphate ester-based flame retardants include condensed phosphate esters of di(dimethyl)phosphate. Specific examples of phosphazene-based flame retardants include phenoxyphosphazene. Specific examples of phosphinate-based flame retardants include, for example, metal salts of dialkylphosphinate aluminum salts. Each of the illustrated flame retardants can be used alone, or two or more can be used in combination.

[0115] In the curable resin composition of the present invention, a known filler (l) can be incorporated. Examples of fillers (l) include those added to improve the heat resistance and flame retardancy of the cured resin composition, and there are no particular limitations. By containing filler (l), heat resistance, flame retardancy, etc., can be further improved. Specifically, examples include silica such as spherical silica, alumina, titanium dioxide, and metal oxides such as mica, metal hydroxides such as aluminum hydroxide and magnesium hydroxide, talc, aluminum borate, barium sulfate, and calcium carbonate. Among these, silica, mica, and talc are preferred, and spherical silica is more preferred. One of these can be used alone, or two or more can be used in combination. It can be used directly, or a substance surface-treated with a silane coupling agent such as an epoxy silane type or an amino silane type can be used. From the viewpoint of reactivity with the free radical polymerization initiator (h), vinyl silane, methacryloxysilane, acryloyloxysilane, and styryloxysilane silane coupling agents are preferred as the silane coupling agent. This improves the adhesion strength to the metal foil and the interlayer adhesion strength between resins. The silane coupling agent can be added by integral blending without pre-treating the filler (l).

[0116] The content of filler (l) is preferably 10 to 200 parts by mass relative to the total of 100 parts by mass of the monomer and other organic components and the flame retardant, and more preferably 30 to 150 parts by mass.

[0117] The curable resin composition of the present invention may further contain additives other than flame retardants and fillers. Examples of additives include defoamers such as silicone-based defoamers and acrylate-based defoamers, heat stabilizers, antistatic agents, ultraviolet absorbers, dyes, pigments, lubricants, wetting and dispersing agents, etc.

[0118] Regarding the curable resin composition of the present invention, when manufacturing a prepreg, it can be prepared in a varnish-like form for the purpose of impregnating a substrate (fibrous substrate) used to form the prepreg or for the purpose of making a circuit board material for forming a circuit board.

[0119] The resin varnish contains a multifunctional vinyl aromatic copolymer, a free radical polymerization initiator (h), and a solvent. Depending on preference, it may also contain a curable reactive resin, a thermoplastic resin, a flame retardant, fillers, and other additives. This resin varnish is suitable for use as a varnish for circuit board materials. Specific applications of circuit board materials include printed wiring boards, printed circuit boards, flexible printed wiring boards, multilayer wiring boards, etc.

[0120] Resin varnishes are prepared, for example, as described below.

[0121] First, components that are soluble in an organic solvent, such as the multifunctional vinyl aromatic copolymer and the curable reactive resin (i), are added to an organic solvent and dissolved. Heating may be performed at this time, if necessary. Then, components that are insoluble in the organic solvent, such as inorganic fillers, are added as needed, and the mixture is dispersed using a ball mill, bead mill, planetary mixer, roller mill, etc., to prepare a varnish-like curable resin composition. The organic solvent used herein is not particularly limited as long as it dissolves the multifunctional vinyl aromatic copolymer, (i), etc., and does not hinder the curing reaction. Examples 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. One or more of these solvents may be used. From the viewpoint of dielectric properties, aromatic hydrocarbons such as benzene, toluene, and xylene are preferred.

[0122] When preparing the resin varnish, the amount of organic solvent used relative to 100% by weight of the curable resin composition of the present invention is preferably 5 to 900% by weight, more preferably 10 to 700% by weight, and particularly preferably 20 to 500% by weight. It should be noted that when the curable resin composition of the present invention is an organic solvent solution such as a resin varnish, the amount of organic solvent is not included in the calculation of the composition.

[0123] The cured product obtained by curing the curable resin composition of the present invention can be used as a molded article, laminate, casting, adhesive, coating, or film. For example, the cured product of a semiconductor sealing material is a casting or molded article. As a method to obtain a cured product for this purpose, the cured product can be obtained by casting the curable resin composition, molding it using a transfer molding machine, injection molding machine, etc., and then heating it at 80 to 230°C for 0.5 to 10 hours. The cured product of a varnish for circuit boards is a laminate. As a method to obtain this cured product, the prepreg material can be obtained by impregnating a substrate such as glass fiber, carbon fiber, polyester fiber, polyamide fiber, alumina fiber, or paper with the varnish for circuit boards, heating and drying it, and then laminating it individually or with a metal foil such as copper foil and hot-pressing it.

[0124] By mixing inorganic high dielectric powders such as barium titanate or inorganic magnetic materials such as ferrites into curable resin compositions or resin varnishes, they become superior materials for electronic components, especially high-frequency electronic components.

[0125] The curable resin composition of the present invention, like the curable composite material described later, can be bonded to metal foil (meaning including metal plates, hereinafter the same).

[0126] Next, the curable composite material of the curable resin composition of the present invention and its cured body will be described. In the curable composite material using the curable resin composition of the present invention, a base material is added to improve mechanical strength and increase dimensional stability.

[0127] As such a base material, known materials are used, such as various types of glass cloth, asbestos cloth, metal fiber cloth and other synthetic or natural inorganic fiber cloth, woven or nonwoven fabrics made of liquid crystal fibers such as fully aromatic polyamide fibers, fully aromatic polyester fibers, and polybenzoxazole fibers, woven or nonwoven fabrics made of synthetic fibers such as polyvinyl alcohol fibers, polyester fibers, and acrylonitrile fibers, natural fiber cloths such as cotton cloth, linen cloth, and felt, carbon fiber cloth, kraft paper, cotton paper, paper-glass fiber blended paper and other natural cellulose-based cloths, etc., either individually or in combination of two or more.

[0128] Regarding the proportion of the substrate in the curable composite material, it is preferably 5 to 90 wt%, more preferably 10 to 80 wt%, and even more preferably 20 to 70 wt%. If the substrate content is less than 5 wt%, the dimensional stability and strength of the composite material after curing are insufficient; if the substrate content is more than 90 wt%, the dielectric properties of the composite material are poor and it is not preferred.

[0129] In the curable composite material of the present invention, a coupling agent can be used as needed to improve the adhesion at the interface between the resin and the substrate. Common coupling agents such as silane coupling agents, titanate coupling agents, aluminum-based coupling agents, and zircoaluminate coupling agents can be used.

[0130] As a method for manufacturing the curable composite material of the present invention, for example, a method can be described in which the curable resin composition of the present invention and other components as needed are uniformly dissolved or dispersed in the above-mentioned aromatic, ketone, or other solvents or mixtures thereof, impregnated into a substrate, and then dried. Impregnation is performed by impregnation, coating, or the like. Impregnation can also be repeated multiple times as needed. In this case, multiple solutions with different compositions and concentrations can be used for repeated impregnation to ultimately adjust to the desired resin composition and resin amount.

[0131] The curable composite material of the present invention is cured by means of heating or other methods to obtain a cured composite material. There are no particular limitations on its manufacturing method; for example, multiple layers of the curable composite material can be overlapped, and the layers can be bonded together under heat and pressure while simultaneously undergoing thermal curing to obtain a cured composite material of the desired thickness. Alternatively, a cured composite material that has been bonded and cured once can be combined with a curable composite material to obtain a cured composite material with a new layer structure. Lamination and curing are usually performed simultaneously using hot pressing or similar methods, but they can also be performed separately. That is, the uncured or semi-cured composite material obtained by pre-lamination can be cured by heat treatment or other methods.

[0132] The curing, or molding and curing of the curable resin composition or curable composite material of the present invention can preferably be carried out at a temperature of 80 to 300°C and a pressure of 0.1 to 1000 kg / cm². 2 The time range is 1 minute to 10 hours; the preferred temperature is 150 to 250°C; and the pressure is 1 to 500 kg / cm². 2 The duration can range from 1 minute to 5 hours.

[0133] 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 foils include copper foil and aluminum foil. The thickness is not particularly limited, but is in the range of 3 to 200 μm, more preferably 3 to 105 μm.

[0134] As a method for manufacturing the laminate of the present invention, for example, a method can be described by laminating a curable composite material obtained from the curable resin composition and the substrate of the present invention, as described above, with a metal foil in layers conforming to the intended purpose, bonding the layers together under heat and pressure, and simultaneously thermally curing. In the laminate of the curable resin composition of the present invention, the curable composite material and the metal foil are laminated in arbitrary layers. The metal foil can be used as a surface layer or as an intermediate layer. The lamination and curing can be repeated multiple times to achieve multilayering.

[0135] Adhesives can also be used in bonding with metal foils. Examples of adhesives include epoxy, acrylic, phenolic, and cyanoacrylate adhesives, but are not specifically limited to these.

[0136] The lamination and curing can be carried out under the same conditions as the manufacturing of the cured composite material of the present invention.

[0137] By molding the curable resin composition of the present invention into a film, it is possible to produce a film, which is one form of the curable resin composition of the present invention. The thickness is not particularly limited, but is preferably in the range of 3 to 200 μm, more preferably in the range of 5 to 105 μm.

[0138] There are no particular limitations on the method for manufacturing the film of the present invention. For example, methods include uniformly dissolving or dispersing the curable resin composition in an aromatic, ketone, or other solvent or a mixture thereof, coating it onto a resin film such as a PET film, and then drying it. The coating can be repeated multiple times as needed. In this case, multiple solutions with different compositions and concentrations can be used for repeated coating to ultimately adjust to the desired resin composition and amount.

[0139] The resin-containing metal foil of the present invention is composed of the curable resin composition of the present invention and a metal foil. Examples of metal foils include copper foil and aluminum foil.

[0140] There is no particular limitation on its thickness, but it is preferably in the range of 3 to 200 μm, and more preferably in the range of 5 to 105 μm.

[0141] The method for manufacturing the resin-coated metal foil of the present invention is not particularly limited. For example, a method can be described by uniformly dissolving or dispersing the curable resin composition in an aromatic, ketone, or other solvent or a mixture thereof, coating it onto the metal foil, and then drying it. The coating can be repeated multiple times as needed. In this case, multiple solutions with different compositions and concentrations can be used to repeatedly coat the metal foil, ultimately adjusting it to the desired resin composition and amount.

[0142] The multifunctional vinyl aromatic copolymers of this invention can be processed into molding materials, sheets, or films, and can be used in the electrical industry, aerospace / spacecraft industry, automotive industry, and other fields to meet the requirements of low dielectric constant, low water absorption, and high heat resistance as low dielectric materials, insulating materials, heat-resistant materials, structural materials, etc. In particular, they can be used as single-sided, double-sided, and multilayer printed circuit boards, flexible printed circuit boards, and multilayer boards.

[0143] It can be applied to semiconductor-related materials or optical materials, and further to coatings, photosensitive materials, adhesives, wastewater treatment agents, heavy metal traps, ion exchange resins, antistatic agents, antioxidants, antifogging agents, rust inhibitors, anti-staining agents, bactericides, insecticides, medical materials, coagulants, surfactants, lubricants, binders for solid fuels, conductive treatment agents, resin modified materials, asphalt modified material plasticizers, sintering binders, etc.

[0144] The curable resin composition of this invention exhibits high dielectric properties (low dielectric constant, low dielectric loss tangent) even after severe thermal exposure, and forms a cured product with high adhesion reliability even under harsh environments. Furthermore, the resin has excellent flowability, low linear expansion, and excellent wiring embedding flatness. Therefore, in recent years, as a dielectric material, insulating material, heat-resistant material, structural material, etc., it can provide cured molded products without molding defects such as warping, to meet the strong demand for miniaturization and thinning in the electrical / electronics industry, aerospace industry, and other fields. Moreover, due to its excellent wiring embedding flatness and adhesion to dissimilar materials, it is possible to achieve a curable resin composition, cured product, or material containing it with excellent reliability.

[0145] Example

[0146] Secondly, the present invention will be described using examples, but the present invention is not limited to these examples. All parts in the examples are parts by weight.

[0147] It should be noted that the physical property measurements in the examples were performed using the methods shown below.

[0148] 1) Weight-average molecular weight

[0149] The determination was performed using GPC. Specifically, an apparatus consisting of columns (TSKgel SuperH-H, SuperH2000, SuperHM-H, SuperHM-H, all manufactured by Tosoh Corporation) connected in series within an HLC8320 GPC (manufactured by Tosoh Corporation) was used, with the column temperature set to 40°C. Tetrahydrofuran (THF) was used as the eluent at a flow rate of 1 mL / min, and a differential refractive index detector was used. For the sample being measured, 0.1 g of the solid component was dissolved in 10 mL of THF and filtered through a 0.45 μm microfilter. Mw was calculated from the calibration curve obtained using standard polyethylene oxides (manufactured by Tosoh Corporation, SE-2, SE-5, SE-8, SE-15, SE-30, SE-70, SE-150).

[0150] 2) The structure of the polymer

[0151] The presence or absence of the structure of formula (b1) was determined by 13C-NMR and 1H-NMR analysis using a JNM-LA600 nuclear magnetic resonance spectrometer manufactured by NEC. Chloroform-d1 was used as the solvent, and the resonance line of tetramethylsilane was used as the internal standard.

[0152] 3) Active ester equivalent

[0153] The determination was performed according to JIS K0070 standard. Specifically, the sample was dissolved in THF, reacted with 0.5 mol / L potassium hydroxide ethanol solution, and then neutralized and titrated with 0.5 mol / L hydrochloric acid using phenolphthalein as an indicator to determine the ester value.

[0154] 4) Vinyl equivalent

[0155] The determination was performed according to JIS K0070 standard. Specifically, the sample was reacted with Wijs solution (iodine monochloride solution) and placed in the dark. Then, excess iodine chloride was reduced to iodine, and the iodine content was titrated with sodium thiosulfate to calculate the iodine value. The iodine value was then converted to vinyl equivalent.

[0156] 5) Tanδ in dynamic viscoelasticity measurement

[0157] Test specimens (60mm long × 10mm wide) were prepared from cured resin molded to a thickness of 2mm. Dynamic viscoelasticity was measured using a dynamic viscoelasticity measuring device (DMA7100, Hitachi High-Tech Corporation) at a frequency of 10Hz, a heating rate of 5℃ / min, and a temperature range of 20℃ to 250℃. The peak temperature of the obtained Tanδ was recorded. In cases where multiple peaks were observed, the temperature of each peak was recorded.

[0158] 6) Bending properties of cured products

[0159] Cured resin with a thickness of 2 mm was processed into test pieces (100 mm long × 10 mm wide). The bending characteristics of the resin test pieces were measured using a universal testing machine (Shimadzu AGS-X, manufactured by Shimadzu Corporation) equipped with a 1000 N load sensor. The bending modulus and stress at the failure point of the test pieces were measured using a 3-point bending fixture at an environment of 23°C and 50% RH.

[0160] 7) Haze measurement of cured products

[0161] The cured resin, which was molded with a thickness of 0.7 mm, was processed into a size of 50 mm × 50 mm, and the haze value was measured using a spectrophotometer (CM-5 manufactured by Konica Minolta).

[0162] Example 1

[0163] 0.60 mol (78 g) of divinylbenzene

[0164]

[0165] 0.35 mol (46 g) of ethyl vinylbenzene

[0166]

[0167] 1.75 mol of styrene (182 g)

[0168]

[0169] 0.30 mol (49 g) of 4-acetoxystyrene

[0170]

[0171] 0.12 mol (15 g) of 1-phenylethanol, 250 g of toluene, and 7.9 g of the diethyl ether complex of boron trifluoride as a catalyst were added to a 1.0 L reactor and reacted at 40 °C for 6 hours. After stopping the polymerization with an aqueous solution of methanol and sodium bicarbonate, the oil layer was washed three times with pure water and then volatilized under reduced pressure at 40 °C to obtain copolymer 1.

[0172] For copolymer 1 obtained in Example 1, NMR analysis confirmed that it possesses the structural unit represented by formula (b1). Furthermore, the active ester equivalent and vinyl equivalent were determined, resulting in an active ester equivalent of 1015 g / eq. and a vinyl equivalent of 623 g / eq. for copolymer 1 obtained in Example 1. The IR spectra of the copolymer are shown in [Figure / Graphics]. Figure 1 The GPC diagram is shown in Figure 2 .

[0173] Example 2

[0174] 0.60 mol (78.1 g) of divinylbenzene, 0.35 mol (46.3 g) of ethylvinylbenzene, 1.75 mol (182.3 g) of styrene, 0.30 mol (48.7 g) of 4-acetoxystyrene, 307 g of propyl acetate, 0.17 g of water, and 8.5 g of the diethyl ether complex of boron trifluoride were added to a 1.0 L reactor and reacted at 70 °C for 8 hours. After stopping the polymerization solution with an aqueous solution of methanol and sodium bicarbonate, the oil layer was washed three times with pure water, and the mixture was devolatiled under reduced pressure at 40 °C to obtain copolymer 2.

[0175] Examples 3-5

[0176] Following the same feeding amounts (parts) of each raw material as shown in Table 1, copolymers 3, 4, and 5 were obtained by performing the same operation as in Example 1.

[0177] Comparative Example 1

[0178] Following the feed amounts (parts) of each raw material shown in Table 1, except that 4-acetoxystyrene was not used, the same operation as in Example 1 was performed to obtain copolymer 6.

[0179] For the copolymers obtained in Examples 1-5 and Comparative Example 1, various physical properties were measured, and the results are shown in Table 1.

[0180] Table 1

[0181]

[0182] Secondly, regarding the cured product with epoxy resin, examples will be described, and the components used are as follows.

[0183] [Epoxy Resin]

[0184] Epoxy resin: A mixture of bisphenol A type epoxy resin and bisphenol F type epoxy resin (ZX-1059, manufactured by Nippon Steel Chemical Materials Co., Ltd., epoxy equivalent 166 g / eq.)

[0185] [Synthesis Example 1: Reactive Ester Curing Agent]

[0186] In a reaction apparatus equipped with a stirrer, thermometer, nitrogen inlet ring, dropping funnel, and condenser, 165 parts of phenolized dicyclopentadiene (J-DPP-85, manufactured by JFE Chemical Co., Ltd., hydroxyl equivalent 165), 144 parts of 1-naphthol, 203 parts of isophthaloyl chloride, 10 parts of tetra-n-butylammonium bromide, and 1280 parts of toluene were charged and heated to 50°C to dissolve. While maintaining the system temperature below 60°C, 400 parts of a 20% sodium hydroxide aqueous solution were added dropwise over 3 hours, followed by stirring at this temperature for another 4 hours. The reaction mixture was allowed to stand and separated, and the aqueous layer was removed. This process was repeated until the pH of the aqueous layer reached 7. Then, the water was removed by reflux dehydration to obtain an active ester resin in a toluene solution state with 65% non-volatile components. The active ester equivalent calculated from the feed amount was 220 g / eq.

[0187] [peroxide]

[0188] α,α'-Bis(2-tert-butylperoxyisopropyl)benzene (manufactured by Nippon Oil Co., Ltd., Perbutyl P)

[0189] [catalyst]

[0190] N,N'-Dimethylaminopyridine (manufactured by Tokyo Chemical Industry Co., Ltd., DMAP)

[0191] Example 6

[0192] 23.3 parts of copolymer 1 obtained in Example 1, 10 parts of epoxy resin ZX-1059, 13.3 parts of active ester curing agent obtained in Synthesis Example 1, 0.1 parts of perbutyl P peroxide, and 0.1 parts of catalyst DMAP were mixed and then diluted with toluene to a non-volatile content of 50% to obtain a resin composition. This was then coated onto a PET film to a thickness of 150 μm and dried at 130°C for 15 minutes using a dryer. The resulting dried powder was pressed for 90 minutes under a vacuum of 0.5 kPa, a heating temperature of 220°C, and a pressing pressure of 2 MPa to obtain a cured product with a thickness of 2 mm. It should be noted that 2 mm spacers were used to adjust the thickness. The dynamic viscoelasticity (Tanδ), haze value, and mechanical strength (flexural failure point stress) of the obtained cured product were measured, and the results are shown in Table 2.

[0193] Examples 7-12, Comparative Examples 2-4

[0194] Using the combinations shown in Table 2, the same operation as in Example 6 was performed to obtain a cured product. The dynamic viscoelasticity (Tanδ), haze value, and mechanical strength (bending failure point stress) of the obtained cured product were measured, and the results are shown in Table 2.

[0195] Table 2

[0196]

[0197] According to the embodiments, in the cured product of the resin composition comprising the multifunctional vinyl aromatic copolymer and epoxy resin of the present invention, a Tanδ peak was found and the haze value was also reduced. Therefore, it can be seen that the uniformity and reactivity in the cured product are improved by the crosslinking reaction with epoxy resin, thereby improving the mechanical strength.

[0198] Industrial availability

[0199] The multifunctional vinyl aromatic copolymers of the present invention can be used as electrical insulation materials for high-speed communication equipment, especially for printed wiring boards.

Claims

1. A multifunctional vinyl aromatic copolymer, comprising 2 mol% or more but less than 95 mol% of a divinyl aromatic compound (a), 2 mol% or more but less than 93 mol% of a vinyl aromatic compound containing an ester group represented by formula (1) (b), and 5 mol% or more but less than 96 mol% of a monovinyl aromatic compound (c), characterized in that, The copolymer contains structural units from a divinyl aromatic compound (a) represented by formula (a1) below, and structural units from a vinyl aromatic compound (b) containing ester groups represented by formula (b1) below, with a number-average molecular weight of 300 to 100,000, a molecular weight distribution (Mw / Mn) expressed as the ratio of weight-average molecular weight to number-average molecular weight of less than 100, and is soluble in solvents. In the formula, Ar 1 Ar 2 Each is an aromatic ring group that is independently either a benzene ring or a naphthalene ring, and these aromatic rings are in Ar 1 and Ar 2 Both or either of them contain an ester group with 1 to 15 carbon atoms as a substituent, and may have an alkyl group with 1 to 10 carbon atoms, an alkoxy group with 1 to 10 carbon atoms, an aryl group with 6 to 11 carbon atoms, an aralkyl group with 7 to 12 carbon atoms, an aryloxy group with 6 to 11 carbon atoms, or an arylalkoxy group with 7 to 12 carbon atoms as a substituent, R 1 It is a divalent group that is directly bonded or selected from hydrocarbon groups with 1 to 20 carbon atoms, -CO-, -O-, -S-, -SO2-, and -C(CF3)2-, where n is 0 to 1. In the formula, R 2 This refers to aromatic hydrocarbon groups with 6 to 30 carbon atoms. In the formula, Ar 1 Ar 2 R 1 The symbols , n and are synonyms in equation (1).

2. The multifunctional vinyl aromatic copolymer according to claim 1, wherein, The active ester equivalent is 150–6000 g / eq., and the vinyl equivalent is 200–5000 g / eq.

3. A curable resin composition, characterized in that, It contains the multifunctional vinyl aromatic copolymer according to claim 1 and a free radical polymerization initiator.

4. A resin composition comprising the multifunctional vinyl aromatic copolymer and epoxy resin according to claim 1.

5. A curable resin composition, characterized in that, It contains the multifunctional vinyl aromatic copolymer, curable reactive resin or thermoplastic resin as described in claim 1, or flame retardant or filler.

6. A cured product obtained by curing the curable resin composition according to any one of claims 3 to 5.

7. The method for manufacturing a multifunctional vinyl aromatic copolymer according to claim 1, comprising polymerizing a divinyl aromatic compound (a), a vinyl aromatic compound containing an ester group represented by formula (1) (b), and a monovinyl aromatic compound (c) in the presence of a Lewis acid catalyst (f) and a co-catalyst (g) to manufacture a multifunctional vinyl aromatic copolymer, characterized in that, Relative to the sum of (a), (b) and (c), polymerize at a temperature of -20 to 120°C using more than 2 mol% and less than 95 mol% of divinyl aromatic compound (a), more than 2 mol% and less than 93 mol% of vinyl aromatic compound containing ester group represented by formula (1) (b), and more than 5 mol% and less than 96 mol% of monovinyl aromatic compound (c).

8. The method for manufacturing the multifunctional vinyl aromatic copolymer according to claim 7, wherein, Lewis acid catalyst (f) is a metal fluoride or its complex.

9. The method for manufacturing the multifunctional vinyl aromatic copolymer according to claim 7, wherein, The cocatalyst is one or more compounds selected from ester compounds, ketone compounds, ether compounds, and compounds represented by the following formula (2). In the formula, R 3 R 4 Each group independently represents an alkyl group having 1 to 6 carbon atoms, or an aromatic hydrocarbon group having 6 to 30 carbon atoms. R 5 It represents hydrogen, an alkyl group having 1 to 6 carbon atoms, or an aromatic hydrocarbon group having 6 to 30 carbon atoms.

Images