Resin composition, prepreg, resin-attached film, resin-attached metal foil, metal-clad laminate, and wiring board

Abstract

One aspect of the present invention pertains to a resin composition comprising: a maleimide compound (A) having, per molecule, an indane structure and / or an arylene structure which is oriented and bonded to the meta position; a curing agent (B) having a carbon-carbon unsaturated bond in the molecule; and a styrene-based polymer (C) which is solid at 25°C and has an ethylene structural unit and a butylene structural unit in each molecule, the butylene structural unit comprising 50 mol% or more of the total of the ethylene structural units and the butylene structural units. The contained amount of the styrene-based polymer (C) is 12 mass% or more.

Description

Resin composition, prepreg, resin-coated film, resin-coated metal foil, metal-clad laminate, and wiring board

[0001] The present invention relates to a resin composition, a prepreg, a resin-coated film, a resin-coated metal foil, a metal-clad laminate, and a wiring board.

[0002] With the increase in information processing volume and the increase in information communication speed, various electronic devices are undergoing advances in packaging technologies, such as higher integration, higher wiring density, and multi-layering of the semiconductor devices installed therein. Furthermore, wiring boards used in various electronic devices are required to be high-frequency compatible, such as server boards for communication infrastructure equipment applications such as network equipment, servers, and AI (artificial intelligence) processors, and millimeter-wave radar boards for automotive applications. Substrate materials for forming the insulating layers of wiring boards used in various electronic devices are required to have low relative dielectric constants and dielectric loss tangents in order to increase signal transmission speeds and reduce signal transmission losses. Examples of substrate materials for forming the insulating layers of such wiring boards include resin compositions described in Patent Documents 1 and 2.

[0003] Patent Document 1 describes a resin composition containing a maleimide compound, an allyl group-containing benzoxazine compound, and a high molecular weight component such as a thermoplastic resin. Patent Document 1 discloses that a cured product can be obtained that has a small dielectric loss tangent value, excellent adhesion to conductive materials after environmental resistance testing, and improved brittleness.

[0004] Patent Document 2 describes a resin composition containing a maleimide compound having an indane structure in the molecule and a styrene-based polymer that is solid at 25° C. Patent Document 2 discloses that a cured product can be obtained that has low dielectric properties, excellent adhesion to metal foil, a high glass transition temperature, and in which increases in the relative dielectric constant and dielectric loss tangent due to temperature rise are sufficiently suppressed.

[0005] Wiring boards are also required to be free from warpage. Therefore, it is required that the insulating layer provided on the wiring board be prevented from warping. Therefore, a resin composition used as a substrate material for forming the insulating layer of a wiring board is required to produce a cured product with a low coefficient of thermal expansion.

[0006] JP 2020-158705 A International Publication No. 2022 / 054864

[0007] The present invention has been made in view of the above circumstances, and aims to provide a resin composition that can give a cured product with a low thermal expansion coefficient. Another aim of the present invention is to provide a prepreg, a resin-coated film, a resin-coated metal foil, a metal-clad laminate, and a wiring board that can be obtained using the resin composition.

[0008] One aspect of the present invention is a resin composition comprising: a maleimide compound (A) having, in the molecule, at least one of an indane structure and an arylene structure bonded in a meta-oriented manner; a curing agent (B) having, in the molecule, a carbon-carbon unsaturated bond; and a styrene-based polymer (C) that has, in the molecule, ethylene structural units and butylene structural units, wherein the butylene structural units account for 50 mol % or more of the total of the ethylene structural units and the butylene structural units, and is solid at 25°C, wherein the content of the styrene-based polymer (C) is 12 mass % or more.

[0009] These and other objects, features, and advantages of the present invention will become apparent from the following detailed description and the accompanying drawings.

[0010] Fig. 1 is a schematic cross-sectional view showing an example of a prepreg according to an embodiment of the present invention. Fig. 2 is a schematic cross-sectional view showing an example of a metal-clad laminate according to an embodiment of the present invention. Fig. 3 is a schematic cross-sectional view showing an example of a wiring board according to an embodiment of the present invention. Fig. 4 is a schematic cross-sectional view showing an example of a resin-coated metal foil according to an embodiment of the present invention. Fig. 5 is a schematic cross-sectional view showing an example of a resin-coated film according to an embodiment of the present invention.

[0011] Electronic devices, particularly small portable devices such as mobile communication terminals and notebook PCs, are rapidly becoming more multifunctional, high-performance, thin, and compact. Accordingly, wiring boards used in these products are also required to have finer conductor wiring, more multilayered conductor wiring layers, thinner designs, and improved mechanical properties. In particular, as wiring boards become thinner and larger, warping occurs in semiconductor packages mounting semiconductor chips on the wiring board, which increases the likelihood of mounting defects. To suppress warping in semiconductor packages mounting semiconductor chips on wiring boards, the insulating layer is required to have a low thermal expansion coefficient (thermal expansion rate). Therefore, substrate materials for forming the insulating layer of wiring boards are required to produce cured products with a low thermal expansion coefficient.

[0012] As a result of extensive investigations, the present inventors have found that the above-mentioned object of providing a resin composition that gives a cured product with a low coefficient of thermal expansion can be achieved by the present invention described below.

[0013] Hereinafter, embodiments of the present invention will be described, but the present invention is not limited to these.

[0014] [Resin Composition] A resin composition according to an embodiment of the present invention comprises a maleimide compound (A) having at least one of an indane structure and an arylene structure bonded in a meta-oriented manner in the molecule; a curing agent (B) having a carbon-carbon unsaturated bond in the molecule; and a styrene-based polymer (C) having ethylene structural units and butylene structural units in the molecule, the butylene structural units accounting for 50 mol% or more of the total of the ethylene structural units and the butylene structural units, the styrene-based polymer (C) being solid at 25°C, the content of the styrene-based polymer (C) being 12 mass% or more. By curing the resin composition, a cured product having a low thermal expansion coefficient is obtained. This is believed to be due to the fact that the inclusion of the styrene-based polymer (C) in a resin composition containing the maleimide compound (A) and the curing agent (B) can reduce the thermal expansion coefficient of the cured product obtained by curing the resin composition.

[0015] (Maleimide Compound (A)) As described above, the maleimide compound (A) has at least one of an indane structure and an arylene structure bonded in a meta-oriented manner in the molecule. Specifically, the maleimide compound (A) includes at least one selected from the group consisting of a maleimide compound (A1) having an indane structure in the molecule, a maleimide compound (A2) having an arylene structure bonded in a meta-oriented manner in the molecule, and a maleimide compound (A3) having an indane structure and an arylene structure bonded in a meta-oriented manner in the molecule.

[0016] (Maleimide Compound (A1) Having an Indane Structure in the Molecule) The maleimide compound (A1) is not particularly limited as long as it is a maleimide compound having an indane structure in the molecule. The maleimide compound (A1) has not only the indane structure but also a maleimide group in the molecule. Examples of the indane structure include an indane structure represented by the following formula (1). That is, specific examples of the maleimide compound (A1) include a maleimide compound (A1-1) having a structure represented by the following formula (1) in the molecule as the indane structure, and more specific examples include a maleimide compound (A1-1-1) represented by the following formula (4).

[0017] In formula (1), each Rb is independent. That is, each Rb may be the same group or different groups. For example, when r is 2 or 3, two or three Rb's bonded to the same benzene ring may be the same group or different groups. Rb represents an alkyl group having 1 to 10 carbon atoms, an alkyloxy group (alkoxy group) having 1 to 10 carbon atoms, an alkylthio group having 1 to 10 carbon atoms, an aryl group having 6 to 10 carbon atoms, an aryloxy group having 6 to 10 carbon atoms, an arylthio group having 6 to 10 carbon atoms, a cycloalkyl group having 3 to 10 carbon atoms, a halogen atom, a nitro group, a hydroxyl group, or a mercapto group (thiol group). r represents an integer of 0 to 3.

[0018] In formula (4), each Ra is independent. That is, each Ra may be the same group or different groups. For example, when q is 2 to 4, 2 to 4 Ra bonded to the same benzene ring may be the same group or different groups. Ra represents an alkyl group having 1 to 10 carbon atoms, an alkyloxy group having 1 to 10 carbon atoms, an alkylthio group having 1 to 10 carbon atoms, an aryl group having 6 to 10 carbon atoms, an aryloxy group having 6 to 10 carbon atoms, an arylthio group having 6 to 10 carbon atoms, a cycloalkyl group having 3 to 10 carbon atoms, a halogen atom, a nitro group, a hydroxyl group, or a mercapto group. Rb's are the same as Rb's in formula (1), and each independently represents an alkyl group having 1 to 10 carbon atoms, an alkyloxy group having 1 to 10 carbon atoms, an alkylthio group having 1 to 10 carbon atoms, an aryl group having 6 to 10 carbon atoms, an aryloxy group having 6 to 10 carbon atoms, an arylthio group having 6 to 10 carbon atoms, a cycloalkyl group having 3 to 10 carbon atoms, a halogen atom, a nitro group, a hydroxyl group, or a mercapto group. q represents 0 to 4. r represents 0 to 3. n represents 0.95 to 10.

[0019] r is the average value of the degree of substitution of Rb, and a smaller value is preferable, specifically 0. That is, in the benzene ring to which Rb can be bonded, a hydrogen atom is preferably bonded at the position to which Rb can be bonded. The maleimide compound (A1) having such an r is easy to synthesize. This is thought to be due to reduced steric hindrance and increased electron density in the aromatic ring. Furthermore, when r is 1 to 3, Rb is preferably at least one selected from the group consisting of an alkyl group having 1 to 4 carbon atoms, a cycloalkyl group having 3 to 6 carbon atoms, and an aryl group having 6 to 10 carbon atoms. Furthermore, Ra is preferably at least one selected from the group consisting of an alkyl group having 1 to 4 carbon atoms, a cycloalkyl group having 3 to 6 carbon atoms, and an aryl group having 6 to 10 carbon atoms. The alkyl group having 1 to 4 carbon atoms, a cycloalkyl group having 3 to 6 carbon atoms, and an aryl group having 6 to 10 carbon atoms improves solubility in solvents and suppresses a decrease in the reactivity of the maleimide group, resulting in a suitable cured product. This is thought to be due to a decrease in planarity in the vicinity of the maleimide group, a decrease in crystallinity, and the like.

[0020] Specific examples of the groups represented by Ra and Rb include the following groups.

[0021] The alkyl group having 1 to 10 carbon atoms is not particularly limited, and examples thereof include a methyl group, an ethyl group, a propyl group, a hexyl group, and a decyl group.

[0022] The alkyloxy group having 1 to 10 carbon atoms is not particularly limited, and examples thereof include a methyloxy group, an ethyloxy group, a propyloxy group, a hexyloxy group, and a decyloxy group.

[0023] The alkylthio group having 1 to 10 carbon atoms is not particularly limited, and examples thereof include a methylthio group, an ethylthio group, a propylthio group, a hexylthio group, and a decylthio group.

[0024] The aryl group having 6 to 10 carbon atoms is not particularly limited, and examples thereof include a phenyl group and a naphthyl group.

[0025] The aryloxy group having 6 to 10 carbon atoms is not particularly limited, and examples thereof include a phenyloxy group and a naphthyloxy group.

[0026] The arylthio group having 6 to 10 carbon atoms is not particularly limited, and examples thereof include a phenylthio group and a naphthylthio group.

[0027] The cycloalkyl group having 3 to 10 carbon atoms is not particularly limited, and examples thereof include a cyclopropyl group, a cyclobutyl group, a cyclohexyl group, and a cyclooctyl group.

[0028] Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.

[0029] q is the average value of the substitution degree of Ra, and is preferably 2 to 3, and more preferably 2. The maleimide compound (A1) having such a q is easy to synthesize. This is thought to be because, particularly when q is 2, steric hindrance is reduced and the electron density of the aromatic ring is increased.

[0030] n is the average number of repeats, and as described above, is 0.95 to 10, preferably 0.98 to 8, more preferably 1 to 7, and even more preferably 1.1 to 6. In the maleimide compound (A1-1) having an indane structure represented by formula (1) in the molecule and the maleimide compound (A1-1-1) represented by formula (4), the content of the maleimide compound in which n, the average number of repeats (degree of polymerization), is 0, is preferably 32 mass% or less based on the total amount of the maleimide compound (A1).

[0031] The maleimide compound (A1) preferably has a molecular weight distribution (Mw / Mn) measured by gel permeation chromatography (GPC) of 1 to 4, more preferably 1.1 to 3.8, even more preferably 1.2 to 3.6, and particularly preferably 1.3 to 3.4. The molecular weight distribution is measured by gel permeation chromatography (GPC).

[0032] As the maleimide compound (A1), a commercially available product may be used, for example, the solid content of NE-X-9470S manufactured by DIC Corporation.

[0033] (Maleimide Compound (A2) Having an Arylene Structure in the Molecule That is Oriented to a Meta Position) The maleimide compound (A2) is not particularly limited as long as it is a maleimide compound that has an arylene structure in the molecule that is Oriented to a meta position. The maleimide compound (A2) has not only the arylene structure but also a maleimide group in the molecule. Examples of the arylene structure include an arylene structure in which a structure containing a maleimide group is bonded to the meta position (an arylene structure in which a structure containing a maleimide group is substituted at the meta position). The arylene structure is an arylene group that is oriented to a meta position, such as a group represented by the following formula (5). Examples of the arylene structure include m-arylene groups such as an m-phenylene group and an m-naphthylene group, and more specifically, a group represented by the following formula (5).

[0034] Examples of the maleimide compound (A2) include a maleimide compound (A2-1) represented by the following formula (2), and more specifically, a maleimide compound (A2-1-2) represented by the following formula (6):

[0035] In formula (2), Ar represents an arylene group bonded in a meta orientation. Ａ , R Ｂ , R Ｃ , and R Ｄ are independent of each other. That is, R Ａ , R Ｂ , R Ｃ , and R Ｄ may be the same group or different groups. Ａ , R Ｂ , R Ｃ , and R Ｄ represents a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, or a phenyl group, and is preferably a hydrogen atom. Ｅ and RＦ are independent of each other. That is, R Ｅ and R Ｆ may be the same group or different groups. Ｅ and R Ｆ represents an aliphatic hydrocarbon group. s represents 1 to 5.

[0036] The arylene group is not particularly limited as long as it is an arylene group oriented and bonded at the meta position, and examples thereof include m-arylene groups such as an m-phenylene group and an m-naphthylene group, and more specific examples thereof include groups represented by the formula (5).

[0037] Examples of the alkyl group having 1 to 5 carbon atoms include a methyl group, an ethyl group, a propyl group, an isopropyl group, an n-butyl group, a sec-butyl group, an isobutyl group, a tert-butyl group, a pentyl group, and a neopentyl group.

[0038] The aliphatic hydrocarbon group is a divalent group and may be acyclic or cyclic. Examples of the aliphatic hydrocarbon group include alkylene groups, more specifically methylene groups, methylmethylene groups, and dimethylmethylene groups. Among these, the dimethylmethylene group is preferred.

[0039] In the maleimide compound (A2-1) represented by the formula (2), the repeating number s is preferably 1 to 5. This s is the average value of the repeating number (degree of polymerization).

[0040] In formula (6), s represents 1 to 5. This s is the same as s in formula (2) and is the average value of the number of repetitions (degree of polymerization).

[0041] The maleimide compound (A2-1) represented by the formula (2) and the maleimide compound (A2-1-1) represented by the formula (6) may contain a monofunctional compound where s is 0, or a polyfunctional compound such as a heptafunctional or octafunctional compound where s is 6 or more, as long as s, which is the average value of the repeating number (degree of polymerization), is 1 to 5.

[0042] As the maleimide compound (A2), a commercially available product may be used, for example, the solid content of MIR-5000-60T manufactured by Nippon Kayaku Co., Ltd.

[0043] As the maleimide compound (A2), the maleimide compounds exemplified above may be used alone or in combination of two or more. For example, as the maleimide compound (A2), the maleimide compound (A2-1) represented by formula (2) may be used alone, or two or more maleimide compounds (A2-1) represented by formula (2) may be used in combination. When two or more maleimide compounds (A2-1) represented by formula (2) are used in combination, for example, a maleimide compound (A1) represented by formula (2) other than the maleimide compound (A2-1-1) represented by formula (6) may be used in combination with the maleimide compound (A2-1-1) represented by formula (6).

[0044] (Maleimide Compound (A3) Having an Indane Structure and an Arylene Structure Bonded at the Meta Position in the Molecule) The maleimide compound (A3) is not particularly limited as long as it is a maleimide compound having an indane structure and an arylene structure bonded at the meta position in the molecule. The maleimide compound (A3) has not only the arylene structure and the indane structure but also a maleimide group in the molecule. The indane structure is the same as the indane structure in the maleimide compound (A1), and the arylene structure is the same as the arylene structure bonded at the meta position in the maleimide compound (A2). Specific examples of the maleimide compound (A3) include maleimide compounds represented by the following formulas (7) to (9).

[0045] In formula (7), n represents 0.95 to 10.

[0046] In formula (8), n represents 0.95 to 10.

[0047] In formula (9), n represents 0.95 to 10.

[0048] As the maleimide compound (A), these may be used alone or in combination of two or more. The content of the maleimide compound (A1) is preferably 40 to 100 parts by mass, more preferably 50 to 100 parts by mass, per 100 parts by mass of the maleimide compound (A). The content of the maleimide compound (A2) is preferably 40 to 100 parts by mass, more preferably 50 to 100 parts by mass, per 100 parts by mass of the maleimide compound (A). The content of the maleimide compound (A3) is preferably 40 to 100 parts by mass, more preferably 50 to 100 parts by mass, per 100 parts by mass of the maleimide compound (A).

[0049] (Curing Agent (B)) The curing agent (B) is not particularly limited as long as it is a curing agent having a carbon-carbon unsaturated bond in the molecule. For example, it may be a compound different from the maleimide compound (A) that can react with the maleimide compound (A) to cure the resin composition. Specific examples of the curing agent (B) include a benzoxazine compound (B1) having an alkenyl group in the molecule, a hydrocarbon compound (B2) having a carbon-carbon unsaturated double bond in the molecule, a polybutadiene compound (B3) having an epoxy group in the molecule, and other curing agents (B4) [curing agents (B4) having a carbon-carbon unsaturated bond in the molecule other than the benzoxazine compound (B1), the hydrocarbon compound (B2), and the polybutadiene compound (B3) having an epoxy group in the molecule]. As the curing agent (B), these may be used alone or in combination of two or more.

[0050] (Benzoxazine Compound (B1) Having an Alkenyl Group in the Molecule) The benzoxazine compound (B1) is not particularly limited as long as it is a benzoxazine compound having an alkenyl group in the molecule. The benzoxazine compound (B1) has not only an alkenyl group but also a benzoxazine group in the molecule. The alkenyl group is not particularly limited, and examples thereof include alkenyl groups having 2 to 6 carbon atoms. Specific examples of the alkenyl group include vinyl groups, allyl groups, propenyl groups, and butenyl groups. Of these, allyl groups and propenyl groups are preferred, and allyl groups are more preferred. The curing agent (B) is preferably a benzoxazine compound having an allyl group in the molecule. Examples of the benzoxazine group include a benzoxazine group represented by the following formula (10) and a benzoxazine group represented by the following formula (11). Examples of the benzoxazine compound (B1) include not only a benzoxazine compound (B1-1) having a benzoxazine group represented by the following formula (10) in the molecule, and a benzoxazine compound (B1-2) having a benzoxazine group represented by the following formula (11) in the molecule, but also a benzoxazine compound (B1-3) having a benzoxazine group represented by the following formula (10) and a benzoxazine group represented by the following formula (11) in the molecule.

[0051] In formula (10), R １ represents an allyl group, and a represents 1 to 4. a represents R １ is an average value of the degree of substitution of 1 to 4, and is preferably 1.

[0052] In formula (11), R ２ represents an allyl group.

[0053] Specific examples of the benzoxazine compound (B1) include the benzoxazine compound (B1-1) represented by the following formula (12):

[0054] In formula (12), R ３ and R ４represents an allyl group; Y represents an alkylene group; b and c each independently represent 1 to 4;

[0055] The alkylene group is not particularly limited and examples thereof include a methylene group, an ethylene group, a propylene group, a butylene group, a pentylene group, a hexylene group, a heptylene group, an octane group, an icosane group, and a hexatriacontane group. Among these, a methylene group is preferred.

[0056] b is R ３ is the average value of the degree of substitution of R ４ is an average value of the degree of substitution of 1 to 4, and is preferably 1.

[0057] As the benzoxazine compound (B1), a commercially available product may be used, for example, ALPd manufactured by Shikoku Chemicals Corporation.

[0058] As the benzoxazine compound (B1), the benzoxazine compounds exemplified above may be used alone or in combination of two or more.

[0059] (Hydrocarbon Compound (B2) Having a Carbon-Carbon Unsaturated Double Bond in the Molecule) The hydrocarbon compound (B2) is not particularly limited as long as it is a hydrocarbon compound having a carbon-carbon unsaturated double bond in the molecule. The carbon-carbon unsaturated group is not particularly limited, and examples thereof include alkenyl groups. Examples of the alkenyl group include alkenyl groups having 2 to 6 carbon atoms, and specific examples include vinyl groups, allyl groups, propenyl groups, and butenyl groups. Among these, allyl groups and propenyl groups are preferred. Examples of the hydrocarbon compound (B2) include divinylbenzenes such as o-divinylbenzene, m-divinylbenzene, and p-divinylbenzene; hydrocarbon compounds (B2-1) represented by the following formula (3); and hydrocarbon compounds (B2-2) represented by the following formula (14).

[0060] In formula (3), X represents a hydrocarbon group having 6 or more carbon atoms and containing at least one selected from an aromatic cyclic group and an aliphatic cyclic group, and m represents 1 to 10.

[0061] The aromatic cyclic group is not particularly limited, but examples thereof include a phenylene group, a xylylene group, a naphthylene group, a tolylene group, and a biphenylene group. The aliphatic cyclic group is not particularly limited, but examples thereof include a group containing an indane structure and a group containing a cycloolefin structure. Among these, X is preferably the aromatic cyclic group, and more preferably a xylylene group. The number of carbon atoms in the hydrocarbon group is not particularly limited as long as it is 6 or more, but is preferably 6 to 20. More specific examples of the hydrocarbon compound (B2-1) include a hydrocarbon compound (B2-1-1) represented by the following formula (13):

[0062] In formula (13), m represents 1 to 10.

[0063] In formula (14), e represents 1 to 20.

[0064] In the hydrocarbon compound (B2-2), e is preferably 1 to 20, more preferably 1 to 12, and even more preferably 1 to 6. Specific examples of the hydrocarbon compound (B2-2) include a compound represented by the formula (14) in which e is 1 [bis-(4-vinylphenyl)methane (BVPM)], a compound represented by the formula (14) in which e is 2 [1,2-bis(vinylphenyl)ethane (BVPE)], and a compound represented by the formula (14) in which e is 6 [1,6-bis(4-vinylphenyl)hexane (BVPH)].

[0065] Of the above examples of the hydrocarbon compound (B2), the hydrocarbon compound (B2-1) represented by the formula (3) is preferred, and the hydrocarbon compound (B2-1-1) represented by the formula (13) is more preferred.

[0066] (Polybutadiene Compound (B3) Having Epoxy Groups in the Molecule) The polybutadiene compound (B3) having epoxy groups in the molecule is not particularly limited, and examples thereof include epoxidized polybutadiene, i.e., a compound in which epoxy groups have been introduced into the molecule by epoxidizing at least a portion of the carbon-carbon double bonds contained in polybutadiene, and a compound in which both terminals of polybutadiene have been glycidyl etherified. The epoxidation is carried out, for example, by adding one oxygen atom to the carbon-carbon double bond contained in polybutadiene (polybutadiene before epoxidation) using an epoxidizing agent to form a three-membered ring epoxy group. A compound in which both terminals of polybutadiene have been glycidyl etherified can be obtained by adding epichlorohydrin to polybutadiene having hydroxyl groups at both terminals.

[0067] The polybutadiene (before epoxidation) may have a stereostructure of carbon-carbon double bonds of any of cis-1,4, trans-1,4, cis-1,2, and trans-1,2, and the ratio thereof is not particularly limited.

[0068] The epoxidizing agent is not particularly limited as long as it can epoxidize the carbon-carbon double bonds contained in polybutadiene, and examples of the epoxidizing agent include percarboxylic acids such as peracetic acid, performic acid, perbenzoic acid, trifluoroperacetic acid, and perpropionic acid, organic hydroperoxides such as t-butyl hydroperoxide and cumene hydroperoxide, and hydrogen peroxide.

[0069] The polybutadiene compound having an epoxy group in its molecule preferably has an oxirane oxygen concentration of 1 to 10% by mass, more preferably 5 to 9% by mass. If the oxirane oxygen concentration is too low, the effect of adding the polybutadiene compound having an epoxy group in its molecule, i.e., the effect of improving the adhesion of the cured resin composition to metal foil, tends to be insufficient. On the other hand, if the oxirane oxygen concentration is too high, the epoxy groups tend to become too numerous, which tends to deteriorate the low dielectric properties. By using the polybutadiene compound having an epoxy group in its molecule whose oxirane oxygen concentration is within the above range, a resin composition can be obtained that, when cured, results in a cured product with low dielectric properties and high adhesion to metal foil.

[0070] The concentration of oxirane oxygen is an index of the content of epoxy groups contained in the polybutadiene compound having epoxy groups in the molecule, and can be measured, for example, by a hydrogen bromide-glacial acetic acid solution method.

[0071] (Other Curing Agent (B4)) The other curing agent (B4) is not particularly limited as long as it is a curing agent having a carbon-carbon unsaturated bond in the molecule other than the benzoxazine compound (B1), the hydrocarbon compound (B2), and the polybutadiene compound (B3) having an epoxy group in the molecule. Examples of the other curing agent (B4) include polyphenylene ether compounds, methacrylate compounds, acrylate compounds, vinyl compounds, and allyl compounds, each of which has a carbon-carbon unsaturated double bond in the molecule.

[0072] The polyphenylene ether compound is not particularly limited as long as it is a polyphenylene ether compound having a carbon-carbon unsaturated double bond in the molecule. Examples of the polyphenylene ether compound include polyphenylene ether compounds having a carbon-carbon unsaturated double bond at a terminal, and more specifically, polyphenylene ether compounds having a substituent having a carbon-carbon unsaturated double bond at a molecular terminal, such as modified polyphenylene ether compounds whose terminals are modified with a substituent having a carbon-carbon unsaturated double bond. Examples of the substituent having a carbon-carbon unsaturated double bond include a vinylbenzyl group (ethenylbenzyl group), an acryloyl group, and a methacryloyl group.

[0073] The methacrylate compound is a compound having a methacryloyl group in the molecule, and examples thereof include monofunctional methacrylate compounds having one methacryloyl group in the molecule and polyfunctional methacrylate compounds having two or more methacryloyl groups in the molecule. Examples of the monofunctional methacrylate compound include methyl methacrylate, ethyl methacrylate, propyl methacrylate, and butyl methacrylate. Examples of the polyfunctional methacrylate compound include dimethacrylate compounds such as tricyclodecane dimethanol dimethacrylate (DCP).

[0074] The acrylate compound is a compound having an acryloyl group in the molecule, and examples thereof include monofunctional acrylate compounds having one acryloyl group in the molecule and polyfunctional acrylate compounds having two or more acryloyl groups in the molecule. Examples of the monofunctional acrylate compound include methyl acrylate, ethyl acrylate, propyl acrylate, and butyl acrylate. Examples of the polyfunctional acrylate compound include diacrylate compounds such as tricyclodecane dimethanol diacrylate.

[0075] The vinyl compound is a compound having a vinyl group in the molecule, and examples thereof include monofunctional vinyl compounds (monovinyl compounds) having one vinyl group in the molecule, and polyfunctional vinyl compounds having two or more vinyl groups in the molecule. Examples of the monofunctional vinyl compound include vinylbenzene compounds having a skeleton containing a phosphorus atom in the molecule, such as 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO).

[0076] The allyl compound is a compound having an allyl group in the molecule, and examples thereof include triallyl isocyanurate compounds such as triallyl isocyanurate (TAIC), diallyl bisphenol compounds, and diallyl phthalate (DAP).

[0077] As the curing agent (B), the curing agents exemplified above may be used alone or in combination of two or more kinds.

[0078] (Styrene-Based Polymer (C)) The styrene-based polymer (C) is not particularly limited as long as it has an ethylene structural unit and a butylene structural unit in its molecule, the butylene structural unit accounts for 50 mol% or more of the total of the ethylene structural units and the butylene structural units, and is a solid styrene-based polymer at 25°C. Examples of the styrene-based polymer (C) include styrene-based polymers that have the ethylene structural unit and the butylene structural unit in their molecule as described above, are solid at 25°C, and can be used as a resin contained in a resin composition used to form an insulating layer provided in a metal-clad laminate, a wiring board, or the like. The resin composition used to form an insulating layer provided in a metal-clad laminate, a wiring board, or the like may be a resin composition used to form a resin layer provided in a resin-coated film, a resin-coated metal foil, or the like, or may be a resin composition contained in a prepreg. The content of the butylene structural unit is 50 mol% or more, preferably 50 to 80 mol%, and more preferably 60 to 75 mol%, of the total of the ethylene structural unit and the butylene structural unit. When the content of the butylene structural unit is within the above range, the effect of the styrene-based polymer (C), i.e., the effect of reducing the thermal expansion coefficient of the cured product of the resin composition, can be more suitably exhibited. Examples of the styrene-based polymer (C) include a styrene-based polymer further containing a structural unit derived from a monomer containing styrene in the molecule.

[0079] Examples of the styrene-based copolymer include copolymers obtained by copolymerizing one or more of the styrene-containing monomers (styrene-based monomers) with one or more other monomers copolymerizable with the styrene-based monomer. The styrene-based copolymer may be a random copolymer or a block copolymer. Examples of the block copolymer include a binary copolymer of a structural unit (repeating unit) derived from the styrene-based monomer and a structural unit (repeating unit) derived from the other copolymerizable monomer, and a terpolymer of a structural unit (repeating unit) derived from the styrene-based monomer, a structural unit (repeating unit) derived from the other copolymerizable monomer, and a structural unit (repeating unit) derived from the styrene-based monomer. The styrene-based polymer (C) may be a hydrogenated styrene-based copolymer obtained by hydrogenating the styrene-based copolymer. Preferably, the styrene-based polymer (C) is at least partially hydrogenated. By including an at least partially hydrogenated styrene-based polymer, a resin composition can be obtained that exhibits a low dielectric loss tangent and thermal expansion coefficient and exhibits excellent toughness as a cured product.

[0080] The styrene-based monomer is not particularly limited, but examples thereof include styrene, styrene derivatives, styrene in which some of the hydrogen atoms on the benzene ring have been substituted with alkyl groups, styrene in which some of the hydrogen atoms on the vinyl group have been substituted with alkyl groups, vinyltoluene, α-methylstyrene, butylstyrene, dimethylstyrene, isopropenyltoluene, etc. These styrene-based monomers may be used alone or in combination of two or more.

[0081] The structural unit derived from the styrene-based monomer is not particularly limited, and examples thereof include a structural unit (repeating unit) represented by the following formula (15): That is, examples of the styrene-based polymer (C) include a polymer having a structural unit represented by the following formula (15) in the molecule:

[0082] In formula (15), R ５ ~R ７ each independently represents a hydrogen atom or an alkyl group, and R ８represents any group selected from the group consisting of a hydrogen atom, an alkyl group, an alkenyl group, and an isopropenyl group. The alkyl group is not particularly limited, and is preferably, for example, an alkyl group having 1 to 18 carbon atoms, and more preferably an alkyl group having 1 to 10 carbon atoms. Specific examples include a methyl group, an ethyl group, a propyl group, a hexyl group, and a decyl group. The alkenyl group is preferably an alkenyl group having 1 to 10 carbon atoms.

[0083] The styrene-based polymer (C) preferably contains at least one structural unit represented by the formula (15), and may contain a combination of two or more different structural units represented by the formula (15). The styrene-based polymer (C) may also contain a combination of a structural unit represented by the formula (15) and a structural unit other than the structural unit represented by the formula (15).

[0084] The content of the structural units derived from the styrene-containing monomer is preferably 20% by mass or less, and more preferably 5 to 20% by mass, relative to the styrene-based polymer (C). When the content of the structural units derived from the styrene-containing monomer is within the above range, the effect of the styrene-based polymer (C), i.e., the effect of reducing the thermal expansion coefficient of the cured product of the resin composition, can be more suitably exhibited. This is thought to be due to the following. When the content of the structural units derived from the styrene-containing monomer is too high, it is thought that the reduction in the thermal expansion coefficient of the cured product of the resin composition cannot be sufficiently exhibited. Therefore, when the content of the structural units derived from the styrene-containing monomer is within the above range, it is thought that the effect of the styrene-based polymer (C) can be suitably exhibited. Furthermore, the content of the structural units derived from the styrene-containing monomer is preferably 20% by mass or less relative to the styrene-based polymer (C). However, if the content of the structural units derived from the styrene-containing monomer is too small, the ethylene structural units and the butylene structures become too large, making it difficult to obtain the effects of the styrene-based polymer (C). From this point of view, the content is more preferably 5% by mass or more.

[0085] The ethylene structural unit is not particularly limited, and examples thereof include those having an ethylene structure among the structural units (repeating units) derived from the other copolymerizable monomers. The ethylene structural unit is a structure derived from a 1,4-bond of a conjugated diene monomer (conjugated dienes), and the atom or group bonded to the carbon of the -C-C- bond of the main chain is a hydrogen atom or a methyl group. Specific examples of the conjugated diene monomer include 1,3-butadiene, 2-methyl-1,3-butadiene (isoprene), 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene, 2-methyl-1,3-pentadiene, 1,3-hexadiene, and 1,3-cyclohexadiene. Therefore, specific examples of the ethylene structural unit include structural units having an ethylene structure among the structural units derived from the conjugated dienes, and more specific examples include structural units having an ethylene structure (1,4-addition structural units) among structural units (repeating units) derived from 1,3-butadiene. Examples of the ethylene structural unit include structural units represented by the following formula (16): ９ ~R １２ a structural unit in which all of R are hydrogen atoms or methyl groups; a structural unit represented by the following formula (17): １３ ~R ２０ In the structural unit in which all of R are hydrogen atoms or methyl groups, and in the structural unit represented by the following formula (18), ２１ ~R ２６ are all hydrogen atoms or methyl groups. More specific examples of the ethylene structural unit include structural units represented by the following formula (22) and formulas (29) to (32):

[0086] The butylene structural unit is not particularly limited, and examples thereof include those having a butylene structure among the structural units (repeating units) derived from the other copolymerizable monomers. The butylene structural unit is at least one of a structure derived from a 1,2-bond of a conjugated diene monomer (conjugated dienes) and a structure derived from a 3,4-bond of a conjugated diene monomer (conjugated dienes), and at least one of the atoms or groups bonded to the carbon of the -C-C- bond of the main chain is a side chain having two or more carbon atoms. Therefore, specific examples of the butylene structural unit include structural units having a butylene structure among the structural units derived from the conjugated dienes, and more specific examples include structural units having a butylene structure (at least one of a 1,2-addition structural unit and a 3,4-addition structural unit) among the structural units (repeating units) derived from 1,3-butadiene. The butylene structural unit may be, for example, a hydrogenated structural unit. The butylene structural unit may be, for example, a structural unit represented by the following formula (16): ９ ~R １２ At least one of the structural units is a side chain having two or more carbon atoms, and among the structural units represented by the following formula (17), R １３ ~R ２０ At least one of the structural units is a structural unit having a side chain with two or more carbon atoms, and the structural unit represented by the following formula (18) is R ２１ ~R ２６ At least one of the structural units is a side chain having two or more carbon atoms. More specific examples of the ethylene structural unit include structural units represented by the following formulas (23) to (28).

[0087] The styrene-based polymer (C) contains, in its molecule, a first structural unit (ethylene structural unit) derived from a 1,4-bond of a conjugated diene monomer, and at least one second structural unit (butylene structural unit) derived from a 1,2-bond of a conjugated diene monomer or a 3,4-bond of a conjugated diene monomer, and the second structural unit accounts for 50 mol % or more of the total of the first structural unit and the second structural unit.

[0088] In the formula (16), R ９~R １２ are each independently any group selected from the group consisting of a hydrogen atom, an alkyl group, an alkenyl group, and an isopropenyl group. The alkyl group is not particularly limited, and is preferably, for example, an alkyl group having 1 to 18 carbon atoms, more preferably an alkyl group having 1 to 10 carbon atoms. Specific examples include a methyl group, an ethyl group, a propyl group, a hexyl group, and a decyl group. The alkenyl group is preferably an alkenyl group having 1 to 10 carbon atoms. Among the structural units represented by formula (16), the ethylene structural unit is ９ ~R １２ are each independently a hydrogen atom or a methyl group. ９ ~R １２ At least one of the groups represents a side chain having two or more carbon atoms, specifically, any group selected from the group consisting of an alkyl group, an alkenyl group, and an isopropenyl group having two or more carbon atoms.

[0089] In the formula (17), R １３ ~R ２０ are each independently any group selected from the group consisting of a hydrogen atom, an alkyl group, an alkenyl group, and an isopropenyl group. The alkyl group is not particularly limited, and is preferably, for example, an alkyl group having 1 to 18 carbon atoms, more preferably an alkyl group having 1 to 10 carbon atoms. Specific examples include a methyl group, an ethyl group, a propyl group, a hexyl group, and a decyl group. The alkenyl group is preferably an alkenyl group having 1 to 10 carbon atoms. Among the structural units represented by formula (17), the ethylene structural unit is preferably an alkenyl group having 1 to 10 carbon atoms, １３ ~R ２０ are each independently a hydrogen atom or a methyl group. １３ ~R ２０ At least one of the groups represents a side chain having two or more carbon atoms, specifically, any group selected from the group consisting of an alkyl group, an alkenyl group, and an isopropenyl group having two or more carbon atoms.

[0090] In the formula (18), R ２１ ~R ２６are each independently any group selected from the group consisting of a hydrogen atom, an alkyl group, an alkenyl group, and an isopropenyl group. The alkyl group is not particularly limited, and is preferably, for example, an alkyl group having 1 to 18 carbon atoms, more preferably an alkyl group having 1 to 10 carbon atoms. Specific examples include a methyl group, an ethyl group, a propyl group, a hexyl group, and a decyl group. The alkenyl group is preferably an alkenyl group having 1 to 10 carbon atoms. Among the structural units represented by formula (18), the ethylene structural unit is ２１ ~R ２６ are each independently a hydrogen atom or a methyl group. ２１ ~R ２６ At least one of the groups represents a side chain having two or more carbon atoms, specifically, any group selected from the group consisting of an alkyl group, an alkenyl group, and an isopropenyl group having two or more carbon atoms.

[0091] More specifically, the structural unit represented by the formula (15) includes structural units represented by the following formulas (19) to (21). The structural unit represented by the formula (15) may also be a structure in which the structural units represented by the following formulas (19) to (21) are respectively repeated.

[0092]

[0093]

[0094] More specifically, the structural unit represented by the formula (16) includes structural units represented by the following formulas (22) to (28). The structural unit represented by the formula (16) may also be a structure in which the structural units represented by the following formulas (22) to (28) are respectively repeated.

[0095]

[0096]

[0097]

[0098]

[0099]

[0100]

[0101] More specifically, the structural unit represented by the formula (17) includes structural units represented by the following formulas (29) and (30). The structural unit represented by the formula (17) may also be a structure in which structural units represented by the following formulas (31) and (32) are respectively repeated. The structural unit represented by the formula (17) may be one of these alone or a combination of two or more different types.

[0102]

[0103] More specifically, examples of the structural unit represented by formula (18) include structural units represented by the following formulas (31) and (32). The structural unit represented by formula (18) may also be a structure in which the structural units represented by formula (31) and formula (32) are respectively repeated. The structural unit represented by formula (18) may be one of these alone or a combination of two or more different types.

[0104]

[0105] The styrene polymer (C) may contain a structural unit derived from another copolymerizable monomer other than the ethylene structural unit and the butylene structural unit as the structural unit (repeating unit) derived from the other copolymerizable monomer. Examples of such another copolymerizable monomer include, but are not limited to, olefins such as α-pinene, β-pinene, and dipentene, and non-conjugated dienes such as 1,4-hexadiene and 3-methyl-1,4-hexadiene.

[0106] Examples of the styrene-based polymer (C) include methylstyrene (ethylene / butylene) methylstyrene copolymer, methylstyrene (ethylene-ethylene / propylene) methylstyrene copolymer, styrene-isoprene copolymer, styrene-isoprene styrene copolymer, styrene (ethylene / butylene) styrene copolymer, styrene (ethylene-ethylene / propylene) styrene copolymer, styrene-butadiene styrene copolymer, and styrene (butadiene / butylene) styrene copolymer. The styrene-based polymer (C) may be a styrene-based polymer in which at least a portion of the styrene-based copolymer is hydrogenated. The styrene-based polymer (C) is preferably a styrene-based polymer in which at least a portion of the styrene-based polymer is acid-modified, and more preferably a styrene-based polymer in which at least a portion of the styrene-based polymer is acid-modified with maleic anhydride. The use of such an acid-modified styrene-based polymer can increase the glass transition temperature. This is thought to be due to the increased compatibility of the styrene-based polymer (C) with the maleimide compound (A). Furthermore, the acid value of the styrene-based polymer (C) may be 2 mg CH ３ ONa / g or more, and 2 to 10 mg CH ３ Specifically, the styrene polymer (C) has an acid value of 2 mg CH ３ It is preferable that the styrene polymer is acid-modified with maleic anhydride so that the acid value is 2 to 10 mg CH ３It is more preferable that the styrene-based polymer (C) is acid-modified with maleic anhydride so as to have an acid value of ONa / g. When the acid value of the styrene-based polymer (C) is within the above range, the effect of the styrene-based polymer (C), i.e., the effect of reducing the thermal expansion coefficient of the cured product of the resin composition, can be more suitably exhibited. More specifically, the effect of reducing the thermal expansion coefficient in a high temperature range (e.g., 210 to 260°C) can be more suitably exhibited. This is thought to be due to the increased compatibility of the styrene-based polymer (C) with the maleimide compound (A). Therefore, even if the content of structural units derived from the styrene-containing monomer is relatively low, for example, 5 to 20 mass%, the effect of reducing the thermal expansion coefficient of the cured product of the resin composition can be more suitably exhibited. Here, the acid value refers to the amount of sodium methoxide (CH ) required to neutralize the free acid in 1 g of sample. ３ ONa) (mg).

[0107] The styrene polymer (C) preferably has a weight-average molecular weight of 10,000 to 300,000, more preferably 10,000 to 200,000. If the molecular weight is too low, the glass transition temperature of the cured product of the resin composition tends to decrease, and the heat resistance tends to decrease. If the molecular weight is too high, the viscosity of the resin composition when made into a varnish or during heat molding tends to become too high. The weight-average molecular weight may be measured by a general molecular weight measurement method, and specific examples include values ​​measured using gel permeation chromatography (GPC).

[0108] As the styrene-based polymer (C), the above-exemplified styrene-based polymers may be used alone or in combination of two or more.

[0109] (Maleimide Compound (D)) The resin composition may contain a maleimide compound (D) other than the maleimide compound (A). The maleimide compound (D) is not particularly limited as long as it is a maleimide compound other than the maleimide compound (A1), the maleimide compound (A2), and the maleimide compound (A3). The maleimide compound (D) is a maleimide compound that has a maleimide group in the molecule and does not have either the arylene structure oriented and bonded at the meta position or the indane structure in the molecule. Examples of the maleimide compound (D) include maleimide compounds having one or more maleimide groups in the molecule, and modified maleimide compounds. Examples of the maleimide compound (D) include phenylmaleimide compounds such as 4,4'-diphenylmethane bismaleimide, phenylmethane maleimide, m-phenylene bismaleimide, bisphenol A diphenyl ether bismaleimide, 3,3'-dimethyl-5,5'-diethyl-4,4'-diphenylmethane bismaleimide, 4-methyl-1,3-phenylene bismaleimide, and biphenylaralkyl polymaleimide compounds, as well as N-alkyl bismaleimide compounds having an aliphatic skeleton. Examples of the modified maleimide compound include modified maleimide compounds in which a portion of the molecule is modified with an amine compound, and modified maleimide compounds in which a portion of the molecule is modified with a silicone compound. As the maleimide compound (D), commercially available products may be used. For example, the solid content of MIR-3000-70MT manufactured by Nippon Kayaku Co., Ltd., BMI-2300, BMI-4000, and BMI-5100 manufactured by Daiwa Kasei Kogyo Co., Ltd., BMI, BMI-70, and BMI-80 manufactured by K.I. Kasei Co., Ltd., and BMI-689, BMI-1500, BMI-3000J, and BMI-5000 manufactured by Designer Molecules Inc. may be used.

[0110] (Inorganic Filler (E)) The resin composition may contain an inorganic filler (E) as needed, as long as the effects of the present invention are not impaired. Furthermore, it is preferable to contain the inorganic filler (E) in order to improve the heat resistance, etc., of the cured product of the resin composition. The inorganic filler (E) is not particularly limited as long as it is an inorganic filler that can be used as an inorganic filler contained in a resin composition. Examples of the inorganic filler (E) include metal oxide fillers, metal hydroxide fillers, molybdate fillers, nitride fillers, titanate fillers, magnesium carbonate fillers such as anhydrous magnesium carbonate fillers, calcium carbonate fillers, quartz glass fillers, talc fillers, aluminum borate fillers, and barium sulfate fillers. Examples of the metal oxide fillers include silica fillers, alumina fillers, titanium oxide fillers, magnesium oxide fillers, and mica fillers. Examples of the silica fillers include crushed silica, spherical silica such as fused spherical silica, and silica particles. Examples of the metal hydroxide filler include magnesium hydroxide filler and aluminum hydroxide filler. Examples of the molybdate filler include zinc molybdate filler, calcium molybdate filler, and magnesium molybdate filler. Examples of the nitride filler include aluminum nitride filler and boron nitride filler. Examples of the titanate filler include barium titanate filler, strontium titanate filler, calcium titanate filler, and aluminum titanate filler. Among these, metal hydroxide fillers such as silica filler, magnesium hydroxide filler, and aluminum hydroxide filler, aluminum oxide filler, boron nitride filler, strontium titanate filler, calcium titanate filler, and zinc molybdate filler are preferred, with silica filler being more preferred. The inorganic fillers may be used alone or in combination of two or more.When two or more kinds of the inorganic fillers are used in combination, a silica filler may be used in combination with one or more inorganic fillers other than the silica filler, and a silica filler and a zinc molybdate filler are preferably used in combination. In addition, the inorganic filler may be, for example, a talc filler carrying molybdate in the molybdate filler.

[0111] The inorganic filler (E) may be a surface-treated or untreated inorganic filler. Examples of the surface treatment include treatment with a silane coupling agent.

[0112] The silane coupling agent is not particularly limited, and examples thereof include silane coupling agents having at least one functional group selected from the group consisting of vinyl group, styryl group, methacryloyl group, acryloyl group, phenylamino group, isocyanurate group, ureido group, mercapto group, isocyanate group, epoxy group, and acid anhydride group. That is, the silane coupling agent has at least one reactive functional group selected from vinyl group, styryl group, methacryloyl group, acryloyl group, phenylamino group, isocyanurate group, ureido group, mercapto group, isocyanate group, epoxy group, and acid anhydride group, and further includes compounds having a hydrolyzable group such as a methoxy group or an ethoxy group.

[0113] Examples of the silane coupling agent include those having a vinyl group, such as vinyltriethoxysilane and vinyltrimethoxysilane. Examples of the silane coupling agent include those having a styryl group, such as p-styryltrimethoxysilane and p-styryltriethoxysilane. Examples of the silane coupling agent include those having a methacryloyl group, such as 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropyltriethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, and 3-methacryloxypropylethyldiethoxysilane. Examples of the silane coupling agent include those having an acryloyl group, such as 3-acryloxypropyltrimethoxysilane and 3-acryloxypropyltriethoxysilane. Examples of the silane coupling agent include those having a phenylamino group, such as N-phenyl-3-aminopropyltrimethoxysilane and N-phenyl-3-aminopropyltriethoxysilane.

[0114] The average particle size of the inorganic filler (E) is not particularly limited, and is preferably 0.05 to 10 μm, and more preferably 0.1 to 8 μm. Here, the average particle size refers to the volume average particle size. The volume average particle size can be measured, for example, by a laser diffraction method.

[0115] (Content) The content of the styrene polymer (C) is 12% by mass or more, preferably 12 to 40% by mass, more preferably 12 to 30% by mass, and even more preferably 12 to 25% by mass, based on the total of the maleimide compound (A), the curing agent (B), and the styrene polymer (C), based on the resin composition. The content of the styrene polymer (C) is preferably 20 to 60% by mass, more preferably 30 to 55% by mass, based on the total of the maleimide compound (A), the curing agent (B), and the styrene polymer (C).

[0116] The content of the maleimide compound (A) is preferably 20 to 50 mass %, and more preferably 25 to 45 mass %, based on the total of the maleimide compound (A), the curing agent (B), and the styrene-based polymer (C).

[0117] The content of the curing agent (B) is preferably 5 to 40 mass %, and more preferably 5 to 30 mass %, based on the total amount of the maleimide compound (A), the curing agent (B), and the styrene-based polymer (C).

[0118] By incorporating the maleimide compound (A), the radical polymerizable compound (B), and the styrene-based polymer (C) so that their contents fall within the above ranges, a resin composition can be obtained that forms a cured product with a lower thermal expansion coefficient.

[0119] As described above, the resin composition may contain the maleimide compound (D). When the resin composition contains the maleimide compound (D), the total content of the maleimide compound (A) and the maleimide compound (D) is preferably 20 to 60 mass %, and more preferably 30 to 55 mass %, based on the total of the maleimide compound (A), the curing agent (B), the styrene-based polymer (C), and the maleimide compound (D).

[0120] As described above, the resin composition may contain the inorganic filler (E). When the resin composition contains the inorganic filler (E), the content of the inorganic filler (E) is preferably 100 to 300 parts by mass, more preferably 100 to 250 parts by mass, per 100 parts by mass of the organic components (other than the inorganic filler (E) in the resin composition). Furthermore, the content of the inorganic filler (E) is preferably 100 to 300 parts by mass, more preferably 100 to 250 parts by mass, per 100 parts by mass of the total of the maleimide compound (A), the curing agent (B), and the styrene-based polymer (C). The inclusion of the inorganic filler is preferable in terms of increasing the glass transition temperature and storage modulus of the resin composition.

[0121] (Other Components) The resin composition may contain components (other components) other than the maleimide compound (A), the curing agent (B), and the styrene-based polymer (C), as long as the effects of the present invention are not impaired. As described above, the resin composition may contain the maleimide compound (D) and the inorganic filler (E) as the other components. In addition to the maleimide compound (D) and the inorganic filler (E), examples of the other components include organic components other than the maleimide compound (A), the curing agent (B), the styrene-based polymer (C), and the maleimide compound (D), flame retardants, reaction initiators, curing accelerators, catalysts, polymerization retarders, polymerization inhibitors, dispersants, leveling agents, coupling agents, antifoaming agents, antioxidants, heat stabilizers, antistatic agents, UV absorbers, dyes and pigments, and additives such as lubricants.

[0122] As described above, the resin composition according to this embodiment may contain an organic component other than the maleimide compound (A), the curing agent (B), the styrene-based polymer (C), and the maleimide compound (D). The organic component may be, for example, a compound that reacts with or does not react with at least one of the maleimide compound (A), the curing agent (B), and the styrene-based polymer (C). Specific examples of the organic component include oxazine compounds other than the oxazine compound (B1) (other oxazine compounds), epoxy compounds, cyanate ester compounds, and active ester compounds.

[0123] The other oxazine compound is not particularly limited as long as it has an oxazine group in the molecule and is an oxazine compound other than the oxazine compound (B1). Examples of the other oxazine compound include a benzoxazine compound having a phenolphthalein structure in the molecule (phenolphthalein-type benzoxazine compound), a bisphenol F-type benzoxazine compound, and a diaminodiphenylmethane (DDM)-type benzoxazine compound. More specific examples of the other oxazine compound include 3,3'-(methylene-1,4-diphenylene)bis(3,4-dihydro-2H-1,3-benzoxazine) (P-d-type benzoxazine compound) and 2,2-bis(3,4-dihydro-2H-3-phenyl-1,3-benzoxazine)methane (F-a-type benzoxazine compound).

[0124] The epoxy compound is a compound having an epoxy group in the molecule, and specific examples thereof include bisphenol-type epoxy compounds such as bisphenol A-type epoxy compounds, phenol novolac-type epoxy compounds, cresol novolac-type epoxy compounds, dicyclopentadiene-type epoxy compounds, bisphenol A novolac-type epoxy compounds, biphenyl aralkyl-type epoxy compounds, polybutadiene compounds having an epoxy group in the molecule, and naphthalene ring-containing epoxy compounds. The epoxy compound also includes epoxy resins, which are polymers of the above-mentioned epoxy compounds.

[0125] The cyanate ester compound is a compound having a cyanate group in the molecule, and examples thereof include 2,2-bis(4-cyanatephenyl)propane, bis(3,5-dimethyl-4-cyanatephenyl)methane, and 2,2-bis(4-cyanatephenyl)ethane.

[0126] The active ester compound is a compound having an ester group with high reactivity in the molecule, and examples thereof include benzenecarboxylic acid active ester, benzenedicarboxylic acid active ester, benzenetricarboxylic acid active ester, benzenetetracarboxylic acid active ester, naphthalenecarboxylic acid active ester, naphthalenedicarboxylic acid active ester, naphthalenetricarboxylic acid active ester, naphthalenetetracarboxylic acid active ester, fluorenecarboxylic acid active ester, fluorenedicarboxylic acid active ester, fluorenetricarboxylic acid active ester, and fluorenetetracarboxylic acid active ester.

[0127] As described above, the resin composition according to this embodiment may contain a flame retardant. By including a flame retardant, the flame retardancy of the cured resin composition can be improved. The flame retardant is not particularly limited. Specifically, in fields where halogen-based flame retardants such as bromine-based flame retardants are used, for example, ethylene dipentabromobenzene, ethylene bistetrabromoimide, decabromodiphenyl oxide, tetradecabromodiphenoxybenzene, and bromostyrene-based compounds that react with the polymerizable compounds, which have melting points of 300°C or higher, are preferred. It is believed that the use of a halogen-based flame retardant can suppress halogen elimination at high temperatures and thus suppress a decrease in heat resistance. Furthermore, in fields where halogen-free materials are required, phosphorus-containing flame retardants (phosphorus-based flame retardants) are sometimes used. The phosphorus-based flame retardant is not particularly limited, but examples thereof include phosphate ester-based flame retardants, phosphazene-based flame retardants, bisdiphenylphosphine oxide-based flame retardants, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO)-based flame retardants, and phosphinate-based flame retardants. Specific examples of phosphate ester-based flame retardants include condensed phosphate esters of dixylenyl phosphate. Specific examples of phosphazene-based flame retardants include phenoxyphosphazene. Specific examples of bisdiphenylphosphine oxide-based flame retardants include xylylenebisdiphenylphosphine oxide. Specific examples of DOPO-based flame retardants include hydrocarbons having two DOPO groups in the molecule (DOPO derivative compounds) and DOPO having a reactive functional group. Specific examples of phosphinate-based flame retardants include metal phosphinates of aluminum dialkylphosphinates. As the flame retardant, each of the exemplified flame retardants may be used alone or in combination of two or more kinds.

[0128] As described above, the resin composition according to this embodiment may contain a reaction initiator. The reaction initiator is not particularly limited as long as it can accelerate the curing reaction of the resin composition, and examples thereof include peroxides and organic azo compounds. Examples of peroxides include α,α'-di(t-butylperoxy)diisopropylbenzene (PBP), 2,5-dimethyl-2,5-di(t-butylperoxy)-3-hexyne, and benzoyl peroxide. Examples of organic azo compounds include azobisisobutyronitrile. If necessary, a metal carboxylate or the like can be used in combination. This further accelerates the curing reaction. Among these, α,α'-di(t-butylperoxy)diisopropylbenzene is preferred. Because α,α'-di(t-butylperoxy)diisopropylbenzene has a relatively high reaction initiation temperature, it can suppress acceleration of the curing reaction when curing is not required, such as during prepreg drying, thereby suppressing deterioration in the shelf life of the resin composition. Furthermore, since α,α'-di(t-butylperoxy)diisopropylbenzene has low volatility, it does not volatilize during drying or storage of the prepreg, and has good stability. The reaction initiators may be used alone or in combination of two or more.

[0129] As described above, the resin composition according to this embodiment may contain a curing accelerator. The curing accelerator is not particularly limited as long as it can accelerate the curing reaction of the resin composition. Specific examples of the curing accelerator include imidazoles and their derivatives, organophosphorus compounds, amines such as secondary amines and tertiary amines, quaternary ammonium salts, organoboron compounds, and metal soaps. Examples of the imidazoles include 2-ethyl-4-methylimidazole (2E4MZ), 2-methylimidazole, 2-phenyl-4-methylimidazole, 2-phenylimidazole, and 1-benzyl-2-methylimidazole. Examples of the organophosphorus compounds include triphenylphosphine, diphenylphosphine, phenylphosphine, tributylphosphine, and trimethylphosphine. Examples of the amines include dimethylbenzylamine, triethylenediamine, triethanolamine, and 1,8-diaza-bicyclo(5,4,0)undecene-7 (DBU). Examples of the quaternary ammonium salts include tetrabutylammonium bromide. Examples of the organoboron compounds include tetraphenylboron salts such as 2-ethyl-4-methylimidazole tetraphenylborate, and tetra-substituted phosphonium tetra-substituted borates such as tetraphenylphosphonium ethyltriphenylborate. The metal soap refers to a fatty acid metal salt, and may be either a linear fatty acid metal salt or a cyclic fatty acid metal salt. Specific examples of the metal soap include linear fatty acid metal salts and cyclic fatty acid metal salts having 6 to 10 carbon atoms. More specifically, examples of the curing accelerator include aliphatic metal salts composed of linear fatty acids such as stearic acid, lauric acid, ricinoleic acid, and octylic acid, or cyclic fatty acids such as naphthenic acid, and metals such as lithium, magnesium, calcium, barium, copper, and zinc. For example, zinc octylate is included. The curing accelerators may be used alone or in combination of two or more.

[0130] As described above, the resin composition according to this embodiment may contain a silane coupling agent. The silane coupling agent may be contained in the resin composition, or may be contained as a silane coupling agent that has been surface-treated in advance on an inorganic filler contained in the resin composition. Among these, the silane coupling agent is preferably contained as a silane coupling agent that has been surface-treated in advance on an inorganic filler, and it is more preferable to contain the silane coupling agent in advance on an inorganic filler in this way, and further to contain the silane coupling agent in the resin composition. In addition, in the case of a prepreg, the prepreg may contain the silane coupling agent that has been surface-treated in advance on a fibrous substrate. Examples of the silane coupling agent include the same silane coupling agents as those used when surface-treating the inorganic filler described above.

[0131] The resin composition according to the present embodiment is a resin composition that can produce a cured product with a low coefficient of thermal expansion, and therefore, wiring boards having an insulating layer formed using the resin composition according to the present embodiment are less likely to warp.

[0132] (Uses) The resin composition is used to produce a prepreg, as described below, and to form a resin layer provided in a resin-coated metal foil or a resin-coated film, and an insulating layer provided in a metal-clad laminate or a wiring board.

[0133] (Production Method) The method for producing the resin composition is not particularly limited, and examples thereof include a method of mixing the maleimide compound (A), the curing agent (B), the styrene-based polymer (C), and, if necessary, components other than the maleimide compound (A), the curing agent (B), and the styrene-based polymer (C) so as to achieve a predetermined content. In addition, in the case of obtaining a varnish-like composition containing an organic solvent, the method described below can be used.

[0134] By using the resin composition according to this embodiment, a prepreg, a metal-clad laminate, a wiring board, a resin-coated metal foil, and a resin-coated film can be obtained as follows.

[0135] [Prepreg] FIG. 1 is a schematic cross-sectional view showing an example of a prepreg 1 according to an embodiment of the present invention.

[0136] 1, the prepreg 1 according to this embodiment comprises the resin composition or a semi-cured product of the resin composition 2, and a fibrous base material 3. This prepreg 1 comprises the resin composition or a semi-cured product of the resin composition 2, and the fibrous base material 3 present in the resin composition or the semi-cured product of the resin composition 2.

[0137] In this embodiment, the semi-cured product refers to a resin composition that has been partially cured to the extent that it can be further cured. That is, the semi-cured product refers to a resin composition that has been semi-cured (B-staged). For example, when a resin composition is heated, the viscosity initially gradually decreases, and then curing begins, and the viscosity gradually increases. In such a case, the semi-cured state may refer to a state between when the viscosity starts to increase and when the composition is completely cured.

[0138] The prepreg obtained using the resin composition according to this embodiment may comprise a semi-cured product of the resin composition as described above, or may comprise the uncured resin composition itself. That is, it may be a prepreg comprising a semi-cured product of the resin composition (the resin composition in B stage) and a fibrous base material, or a prepreg comprising the resin composition before curing (the resin composition in A stage) and a fibrous base material. Furthermore, the resin composition or the semi-cured product of the resin composition may be the resin composition that has been dried or heat-dried.

[0139] When producing the prepreg, the resin composition 2 is often prepared in a varnish form and used to impregnate the fibrous base material 3, which is a base material for forming the prepreg. That is, the resin composition 2 is usually often a resin varnish prepared in a varnish form. Such a varnish-like resin composition (resin varnish) is prepared, for example, as follows.

[0140] First, each component that is soluble in an organic solvent is added to the organic solvent and dissolved. Heating may be performed as necessary. Then, components that are insoluble in the organic solvent are added as needed, and the mixture is dispersed using a ball mill, bead mill, planetary mixer, roll mill, or the like until a predetermined dispersion state is achieved, thereby preparing a varnish-like resin composition. The organic solvent used here is not particularly limited as long as it dissolves the organic components and resin components in the resin composition and does not inhibit the curing reaction. Specific examples include toluene and methyl ethyl ketone (MEK).

[0141] Specific examples of the fibrous substrate include glass cloth, aramid cloth, polyester cloth, glass nonwoven fabric, aramid nonwoven fabric, polyester nonwoven fabric, pulp paper, and linter paper. Glass cloth can be used to obtain a laminate with excellent mechanical strength, and flattened glass cloth is particularly preferred. A specific example of the flattening process is a method in which glass cloth is continuously pressed with a press roll at an appropriate pressure to compress the yarns flat. The thickness of commonly used fibrous substrates is, for example, 0.01 mm or more and 0.3 mm or less. The glass fibers constituting the glass cloth are not particularly limited, and examples include Q glass, NE glass, E glass, S glass, T glass, L glass, and L2 glass. The surface of the fibrous substrate may be treated with a silane coupling agent. The silane coupling agent is not particularly limited, but examples thereof include silane coupling agents having at least one group selected from the group consisting of a vinyl group, an acryloyl group, a methacryloyl group, a styryl group, an amino group, and an epoxy group in the molecule.

[0142] The method for producing the prepreg is not particularly limited as long as it can produce the prepreg. Specifically, when producing the prepreg, the resin composition according to the present embodiment is often prepared in the form of a varnish, as described above, and used as a resin varnish.

[0143] Specific examples of methods for producing the prepreg 1 include a method in which the resin composition 2, for example, a resin composition 2 prepared in a varnish form, is impregnated into a fibrous substrate 3, followed by drying. The resin composition 2 is impregnated into the fibrous substrate 3 by immersion, coating, or the like. Impregnation can be repeated multiple times as necessary. In this case, by repeating the impregnation using multiple resin compositions with different compositions and concentrations, it is also possible to adjust the final composition and impregnation amount to the desired one.

[0144] The fibrous substrate 3 impregnated with the resin composition (resin varnish) 2 is heated under desired conditions, for example, at 40°C to 180°C for 1 minute to 10 minutes. This heating process results in a prepreg 1 in an uncured (A-stage) or semi-cured (B-stage) state. The heating process also volatilizes the organic solvent from the resin varnish, reducing or eliminating the organic solvent.

[0145] [Metal-clad laminate] FIG. 2 is a schematic cross-sectional view showing an example of a metal-clad laminate 11 according to an embodiment of the present invention.

[0146] As shown in FIG. 2 , the metal-clad laminate 11 according to this embodiment includes an insulating layer 12 containing a cured product of the resin composition and a metal foil 13 disposed on the insulating layer 12. Examples of the metal-clad laminate 11 include a metal-clad laminate composed of an insulating layer 12 containing a cured product of the prepreg 1 shown in FIG. 1 and a metal foil 13 laminated together with the insulating layer 12. The insulating layer 12 may be composed of a cured product of the resin composition or a cured product of the prepreg. The thickness of the metal foil 13 varies depending on the performance required of the final wiring board and is not particularly limited. The thickness of the metal foil 13 can be appropriately set depending on the desired purpose, and is preferably, for example, 0.2 to 70 μm. Examples of the metal foil 13 include copper foil and aluminum foil. When the metal foil is thin, it may be a carrier-attached copper foil equipped with a release layer and a carrier to improve handling.

[0147] The method for producing the metal-clad laminate 11 is not particularly limited as long as it can produce the metal-clad laminate 11. Specifically, a method for producing the metal-clad laminate 11 using the prepreg 1 can be used. Examples of such a method include stacking one or more prepregs 1, placing a metal foil 13 such as copper foil on both sides or one side of the prepreg 1, and then heat-pressing and molding the metal foil 13 and the prepreg 1 to form an integrated laminate, thereby producing a double-sided or single-sided metal foil-clad laminate 11. That is, the metal-clad laminate 11 can be obtained by laminating the metal foil 13 on the prepreg 1 and then heat-pressing and molding the laminate. The heat-pressing conditions can be appropriately set depending on the thickness of the metal-clad laminate 11, the type of resin composition contained in the prepreg 1, and the like. For example, the temperature can be 170 to 230°C, the pressure can be 2 to 7 MPa, and the time can be 60 to 150 minutes. The metal-clad laminate can also be produced without using a prepreg. For example, a method may be used in which a varnish-like resin composition is applied onto a metal foil to form a layer containing the resin composition on the metal foil, and then the layer is heated and pressed.

[0148] [Wiring Board] FIG. 3 is a schematic cross-sectional view showing an example of a wiring board 21 according to an embodiment of the present invention.

[0149] As shown in Fig. 3, wiring board 21 according to this embodiment has insulating layer 12 containing a cured product of the resin composition, and wiring 14 provided on insulating layer 12. Examples of wiring board 21 include a wiring board configured from insulating layer 12 used by curing prepreg 1 shown in Fig. 1, and wiring 14 laminated together with insulating layer 12 and formed by partially removing metal foil 13. Furthermore, insulating layer 12 may be made of a cured product of the resin composition, or may be made of a cured product of the prepreg.

[0150] The method for manufacturing the wiring board 21 is not particularly limited as long as the wiring board 21 can be manufactured. Specific examples include a method of manufacturing the wiring board 21 using the prepreg 1. Examples of this method include a method of manufacturing the wiring board 21 in which wiring is provided as a circuit on the surface of the insulating layer 12 by etching the metal foil 13 on the surface of the metal-clad laminate 11 manufactured as described above. That is, the wiring board 21 is obtained by forming a circuit by partially removing the metal foil 13 on the surface of the metal-clad laminate 11. In addition to the above methods, examples of the method for forming a circuit include circuit formation by a semi-additive process (SAP) or a modified semi-additive process (MSAP).

[0151] [Resin-Coated Metal Foil] FIG. 4 is a schematic cross-sectional view showing an example of a resin-coated metal foil 31 according to this embodiment.

[0152] As shown in Fig. 4, the resin-coated metal foil 31 according to this embodiment comprises a resin layer 32 containing the resin composition or a semi-cured product of the resin composition, and a metal foil 13. The resin-coated metal foil 31 has the metal foil 13 on the surface of the resin layer 32. That is, the resin-coated metal foil 31 comprises the resin layer 32 and the metal foil 13 laminated together with the resin layer 32. The resin-coated metal foil 31 may also comprise another layer between the resin layer 32 and the metal foil 13.

[0153] The resin layer 32 may contain a semi-cured product of the resin composition as described above, or may contain the uncured resin composition. That is, the resin-coated metal foil 31 may comprise a resin layer containing a semi-cured product of the resin composition (the resin composition in B-stage) and a metal foil, or a resin layer containing the resin composition before curing (the resin composition in A-stage) and a metal foil. The resin layer may contain the resin composition or a semi-cured product of the resin composition, and may or may not contain a fibrous substrate. The resin composition or the semi-cured product of the resin composition may be the resin composition that has been dried or heat-dried. The fibrous substrate may be the same as the fibrous substrate of a prepreg.

[0154] The metal foil may be any metal foil used in a metal-clad laminate or a resin-coated metal foil, and examples of the metal foil include copper foil and aluminum foil.

[0155] The resin-coated metal foil 31 may be provided with a cover film or the like as necessary. By providing a cover film, it is possible to prevent the inclusion of foreign matter, etc. The cover film is not particularly limited, but examples thereof include polyolefin films, polyester films, polymethylpentene films, and films formed by providing these films with a release agent layer.

[0156] The method for producing the resin-coated metal foil 31 is not particularly limited as long as the resin-coated metal foil 31 can be produced. Examples of the method for producing the resin-coated metal foil 31 include a method of applying the varnish-like resin composition (resin varnish) to the metal foil 13 and heating the applied resin composition. The varnish-like resin composition is applied to the metal foil 13 using, for example, a bar coater. The applied resin composition is heated, for example, at 40°C or higher and 180°C or lower for 0.1 minutes or longer and 10 minutes or shorter. The heated resin composition is formed on the metal foil 13 as an uncured resin layer 32. The heating volatilizes the organic solvent from the resin varnish, thereby reducing or removing the organic solvent.

[0157] [Resin-Coated Film] FIG. 5 is a schematic cross-sectional view showing an example of a resin-coated film 41 according to this embodiment.

[0158] 5 , the resin-coated film 41 according to this embodiment includes a resin layer 42 containing the resin composition or a semi-cured product of the resin composition, and a support film 43. The resin-coated film 41 includes the resin layer 42 and the support film 43 laminated together with the resin layer 42. The resin-coated film 41 may also include another layer between the resin layer 42 and the support film 43.

[0159] The resin layer 42 may contain a semi-cured product of the resin composition as described above, or may contain the uncured resin composition. That is, the resin-coated film 41 may comprise a resin layer containing a semi-cured product of the resin composition (the resin composition in B-stage) and a support film, or a resin-coated film comprising a resin layer containing the resin composition before curing (the resin composition in A-stage) and a support film. The resin layer may contain the resin composition or a semi-cured product of the resin composition, and may or may not contain a fibrous substrate. The resin composition or the semi-cured product of the resin composition may be obtained by drying or heat-drying the resin composition. The fibrous substrate may be the same as the fibrous substrate of a prepreg.

[0160] Any support film used for a resin-coated film can be used without limitation as the support film 43. Examples of the support film include electrically insulating films such as polyester film, polyethylene terephthalate (PET) film, polyimide film, polyparabanic acid film, polyether ether ketone film, polyphenylene sulfide film, polyamide film, polycarbonate film, and polyarylate film.

[0161] The resin-coated film 41 may be provided with a cover film or the like as necessary. By providing a cover film, it is possible to prevent the inclusion of foreign matter, etc. The cover film is not particularly limited, but examples thereof include a polyolefin film, a polyester film, and a polymethylpentene film.

[0162] The support film and the cover film may be subjected to surface treatment such as matte treatment, corona treatment, release treatment, and roughening treatment, if necessary.

[0163] The method for producing the resin-coated film 41 is not particularly limited as long as it can produce the resin-coated film 41. Examples of methods for producing the resin-coated film 41 include a method in which the varnish-like resin composition (resin varnish) is applied to a support film 43 and heated. The varnish-like resin composition is applied to the support film 43 using, for example, a bar coater. The applied resin composition is heated, for example, at 40°C or higher and 180°C or lower for 0.1 minutes or longer and 10 minutes or shorter. The heated resin composition is formed on the support film 43 as an uncured resin layer 42. The heating volatilizes the organic solvent from the resin varnish, thereby reducing or removing the organic solvent.

[0164] The resin composition according to this embodiment is a resin composition that yields a cured product with a low thermal expansion coefficient. That is, when the resin composition is cured, it yields a cured product with a low thermal expansion coefficient. Therefore, a prepreg including the resin composition or a semi-cured product of the resin composition is a prepreg that yields a cured product with a low thermal expansion coefficient. A resin-coated metal foil and a resin-coated film that include a resin layer containing the resin composition or a semi-cured product of the resin composition are resin-coated metal foils and resin-coated films that include a resin layer that yields an insulating layer containing a cured product with a low thermal expansion coefficient. A metal-clad laminate and a wiring board that include an insulating layer containing a cured product of the resin composition are metal-clad laminates and wiring boards that include an insulating layer containing a cured product with a low thermal expansion coefficient. The prepreg, the resin-coated metal foil, the resin-coated film, and the metal-clad laminate can be suitably used to manufacture a wiring board that includes an insulating layer containing a cured product with a low thermal expansion coefficient. The prepreg, the resin-coated metal foil, the resin-coated film, and the metal-clad laminate can also be used, for example, to manufacture a multilayer wiring board. In the case of the resin-coated film, for example, a multilayer wiring board can be produced by laminating it on a wiring board and then peeling off the support film, or by laminating it on a wiring board after peeling off the support film. In the case of the resin-coated metal foil, for example, a multilayer wiring board can be produced by laminating it on a wiring board. In this way, by using the resin-coated film and the resin-coated metal foil, etc., a multilayer wiring board having an insulating layer containing a cured material with a low thermal expansion coefficient can be produced. A wiring board obtained using the prepreg, the resin-coated metal foil, the resin-coated film, and the metal-clad laminate can be produced having an insulating layer containing a cured material with a low thermal expansion coefficient.

[0165] As described above, this specification discloses various aspects of the technology, the main technologies of which are summarized below.

[0166] A resin composition according to a first aspect of the present invention comprises: a maleimide compound (A) having, in the molecule, at least one of an indane structure and an arylene structure bonded and oriented at a meta position; a curing agent (B) having, in the molecule, a carbon-carbon unsaturated bond; and a styrene-based polymer (C) which has, in the molecule, ethylene structural units and butylene structural units, wherein the butylene structural units account for 50 mol % or more of the total of the ethylene structural units and the butylene structural units, and is solid at 25°C, wherein the content of the styrene-based polymer (C) is 12 mass % or more.

[0167] A resin composition according to a second aspect of the present invention is the resin composition according to the first aspect of the present invention, wherein the styrene-based polymer (C) contains 20 mass% or less of structural units derived from a monomer containing styrene.

[0168] A resin composition related to a third aspect of the present invention is the resin composition related to the first or second aspect of the present invention, further comprising a maleimide compound (D) other than the maleimide compound (A).

[0169] A resin composition according to a fourth aspect of the present invention is the resin composition according to any one of the first to third aspects of the present invention, wherein the content of the styrene polymer (C) is 20 to 60 mass % with respect to the total of the maleimide compound (A), the curing agent (B), and the styrene polymer (C).

[0170] A resin composition according to a fifth aspect of the present invention is the resin composition according to any one of the first to fourth aspects of the present invention, wherein the content of the maleimide compound (A) is 20 to 50 mass % with respect to the total of the maleimide compound (A), the curing agent (B), and the styrene-based polymer (C).

[0171] A resin composition according to a sixth aspect of the present invention is the resin composition according to any one of the first to fifth aspects of the present invention, wherein the content of the curing agent (B) is 5 to 40 mass % with respect to the total of the maleimide compound (A), the curing agent (B), and the styrene-based polymer (C).

[0172] A resin composition according to a seventh aspect of the present invention is the resin composition according to any one of the first to sixth aspects of the present invention, wherein the acid value of the styrene polymer (C) is 2 mg CH ３ The resin composition has a viscosity of ONa / g or more.

[0173] A resin composition according to an eighth aspect of the present invention is the resin composition according to any one of the first to seventh aspects of the present invention, wherein the maleimide compound (A) comprises a maleimide compound (A1-1) having, in the molecule, a structure represented by formula (1) as the indane structure.

[0174] A resin composition according to a ninth aspect of the present invention is the resin composition according to any one of the first to seventh aspects of the present invention, wherein the maleimide compound (A) comprises a maleimide compound (A2-1) represented by formula (2).

[0175] A resin composition according to a tenth aspect of the present invention is the resin composition according to any one of the first to ninth aspects of the present invention, wherein the curing agent (B) comprises at least one selected from the group consisting of a benzoxazine compound (B1) having an alkenyl group in the molecule, a hydrocarbon compound (B2) having a carbon-carbon unsaturated double bond in the molecule, and a polybutadiene compound (B3) having an epoxy group in the molecule.

[0176] A resin composition according to an eleventh aspect of the present invention is the resin composition according to the tenth aspect of the present invention, wherein the hydrocarbon compound (B2) comprises a hydrocarbon compound (B-2) represented by the formula (3).

[0177] A resin composition according to a twelfth aspect of the present invention is the resin composition according to any one of the first to eleventh aspects of the present invention, further comprising an inorganic filler (E).

[0178] A prepreg according to a thirteenth aspect of the present invention is a prepreg comprising the resin composition according to any one of the first to twelfth aspects of the present invention or a semi-cured product of the resin composition, and a fibrous base material.

[0179] The resin-coated film according to the fourteenth aspect of the present invention is a resin-coated film comprising a resin layer containing the resin composition according to any one of the first to twelfth aspects of the present invention or a semi-cured product of the resin composition, and a support film.

[0180] A resin-coated metal foil according to a fifteenth aspect of the present invention is a resin-coated metal foil comprising a resin layer containing the resin composition according to any one of the first to twelfth aspects of the present invention or a semi-cured product of the resin composition, and a metal foil.

[0181] A metal-clad laminate according to a sixteenth aspect of the present invention is a metal-clad laminate comprising an insulating layer containing a cured product of the resin composition according to any one of the first to twelfth aspects of the present invention, and a metal foil.

[0182] A metal-clad laminate according to a seventeenth aspect of the present invention is a metal-clad laminate comprising an insulating layer containing a cured product of the prepreg according to the thirteenth aspect of the present invention and a metal foil.

[0183] A wiring board according to an eighteenth aspect of the present invention is a wiring board comprising an insulating layer containing a cured product of the resin composition according to any one of the first to twelfth aspects of the present invention, and wiring.

[0184] A wiring board according to a nineteenth aspect of the present invention is a wiring board comprising an insulating layer containing a cured product of the prepreg according to the thirteenth aspect of the present invention and wiring.

[0185] According to the present invention, there is provided a resin composition that can give a cured product having a low coefficient of thermal expansion. Furthermore, according to the present invention, there are provided a prepreg, a resin-coated film, a resin-coated metal foil, a metal-clad laminate, and a wiring board that can be obtained using the resin composition.

[0186] The present invention will be explained in more detail below with reference to examples, but the scope of the present invention is not limited to these examples.

[0187] Examples 1 to 5 and Comparative Examples 1 to 6 In these examples, each component used in preparing the resin composition will be described.

[0188] (Maleimide Compound (A)) Maleimide Compound 1: A maleimide compound having an arylene structure substituted at the meta position in the molecule (solid content in MIR-5000-60T (a toluene solution of a maleimide compound) manufactured by Nippon Kayaku Co., Ltd., a maleimide compound represented by the above formula (6), maleimide equivalent: 260 g / mol) Maleimide Compound 2: A maleimide compound having an indane structure and an arylene structure oriented and bonded at the meta position in the molecule (solid content in NE-X-9470S manufactured by DIC Corporation, a maleimide compound represented by the above formula (7))

[0189] (Curing Agent (B)) Hydrocarbon Compound: A hydrocarbon compound represented by the formula (13) above.

[0190] Specifically, it is a hydrocarbon compound synthesized as follows.

[0191] Synthesis Example 1 296 parts by mass of 2-bromoethylbenzene (manufactured by Tokyo Chemical Industry Co., Ltd.), 70 parts by mass of α,α'-dichloro-p-xylene (manufactured by Tokyo Chemical Industry Co., Ltd.), and 18.4 parts by mass of methanesulfonic acid (manufactured by Tokyo Chemical Industry Co., Ltd.) were charged into a flask equipped with a thermometer, a condenser, and a stirrer, and the mixture was reacted at 130°C for 8 hours. After the reaction, the mixture was allowed to cool, and the reaction solution obtained by the reaction was neutralized with an aqueous sodium hydroxide solution, extracted with 1200 parts by mass of toluene, and the organic layer was washed five times with 100 parts by mass of water. The solvent and excess 2-bromoethylbenzene were distilled off under heating and reduced pressure, yielding 160 parts by mass of an olefin compound precursor (BEB-1) having a 2-bromoethylbenzene structure as a liquid resin (Mn: 538, Mw: 649). The repeating unit d was 1.7. Furthermore, the resulting compound １ H-NMR chart (DMSO-d ６ ), signals derived from bromoethyl groups were observed at 2.95-3.15 ppm and 3.60-3.75 ppm.

[0192] (Synthesis Example 2) Next, 22 parts by mass of BEB-1 obtained in Synthesis Example 1, 50 parts by mass of toluene, 150 parts by mass of dimethyl sulfoxide, 15 parts by mass of water, and 5.4 parts by mass of sodium hydroxide were added to a flask equipped with a thermometer, a condenser, and a stirrer, and the mixture was reacted at 40°C for 5 hours. After the reaction, the mixture was allowed to cool, and then 100 parts by mass of toluene was added, and the organic layer was washed five times with 100 parts by mass of water. The solvent was distilled off under heating and reduced pressure, yielding 13 parts by mass of a liquid olefin compound having a styrene structure as a functional group (Mn: 432, Mw: 575). The repeating unit d was 1.7. In addition, the obtained compound １ H-NMR data (DMSO-d ６ ), signals derived from vinyl groups were observed at 5.10-5.30 ppm, 5.50-5.85 ppm, and 6.60-6.80 ppm.

[0193] The resulting compound (liquid olefin compound) was the hydrocarbon compound represented by the formula (13).

[0194] The weight average molecular weight (Mw) and number average molecular weight (Mn) used in Synthesis Example 1 and Synthesis Example 2 were values ​​determined by the following analytical method.

[0195] (Analysis Method) Calculation was performed in terms of polystyrene using a polystyrene standard solution.

[0196] GPC: DGU-20A3R, LC-20AD, SIL-20AHT, RID-20A, SPD-20A, CTO-2, CBM-20A (all manufactured by Shimadzu Corporation) Column: Shodex KF-603, KF-602x2, KF-601x2) Eluent: Tetrahydrofuran Flow rate: 0.5 ml / min. Column temperature: 40°C Detection: RI (differential refractometer) Benzoxazine compound: A benzoxazine compound having an allyl group in the molecule (represented by the formula (12) above, R ３ and R ４is an allyl group, X is a methylene group, and b and c are each 1, a benzoxazine compound, ALPd manufactured by Shikoku Chemical Industry Co., Ltd.) Epoxidized polybutadiene: a polybutadiene compound having an epoxy group in the molecule (JP-100 manufactured by Nippon Soda Co., Ltd., an epoxidized polybutadiene in which an epoxy group has been introduced by oxidizing the vinyl group of 1,2-polybutadiene, oxirane oxygen concentration: 7.7% by mass)

[0197] (Styrene-based polymer (C)) C5025: a styrene-based polymer acid-modified with maleic anhydride (C5025 manufactured by Asahi Kasei Corporation, molar ratio of ethylene structural units to the butylene structure (ethylene structural units: butylene structure) = 27:73, structural units derived from monomers including styrene: 12% by mass, weight average molecular weight Mw: 160,000, acid value: 4 mg CH ３ ONa / g, solid at 25°C) H1221: styrene-based polymer (Tuftec H1221 manufactured by Asahi Kasei Corporation, molar ratio of ethylene structural units to the butylene structure (ethylene structural units:butylene structure) = 23:77, structural units derived from monomers including styrene 12% by mass, acid value 0.03 mg CH ３ ONa / g or less (below detection limit), weight average molecular weight Mw 150,000, solid at 25°C)

[0198] (Styrene-based polymers other than styrene-based polymer (C)) H1041: styrene-based polymer (Tuftec H1041 manufactured by Asahi Kasei Corporation, molar ratio of ethylene structural units to the butylene structure (ethylene structural units:butylene structure) = 65:35, structural units derived from monomers including styrene 28% by mass, weight average molecular weight Mw 75,000, solid at 25°C) S1609: styrene-based polymer (S1609 manufactured by Asahi Kasei Corporation, molar ratio of ethylene structural units to the butylene structure (ethylene structural units:butylene structure) = 75:25, structural units derived from monomers including styrene 66% by mass, weight average molecular weight Mw 220,000, solid at 25°C) P1500: styrene-based polymer (Tuftec P1500 manufactured by Asahi Kasei Corporation, molar ratio of ethylene structural units to the butylene structure (ethylene structural units:butylene structure) = 62:38, structural units derived from monomers including styrene 29% by mass, weight average molecular weight Mw 72,000, solid at 25°C) M1913: styrene-based polymer acid-modified with maleic anhydride (Tuftec M1913 manufactured by Asahi Kasei Corporation, molar ratio of ethylene structural units to the butylene structure (ethylene structural units:butylene structure) = 64:36, structural units derived from monomers including styrene 30% by mass, weight average molecular weight Mw 42,000, acid value 10 mg CH ３ ONa / g, solid at 25°C)

[0199] (Maleimide Compound (D)) Maleimide Compound 3: 3,3'-dimethyl-5,5'-diethyl-4,4'-diphenylmethane bismaleimide (BMI-5100 manufactured by Daiwa Chemical Industry Co., Ltd., bismaleimide compound, maleimide equivalent weight 221 g / mol)

[0200] (Reaction initiator) PBP: α,α'-di(t-butylperoxy)diisopropylbenzene (PBP) (Perbutyl P manufactured by NOF Corporation)

[0201] (Curing accelerator) 2E4MZ: 2-ethyl-4-methylimidazole (2E4MZ) (2E4MZ manufactured by Shikoku Chemicals Corporation)

[0202] (Inorganic filler) Silica: silica particles surface-treated with a silane coupling agent having a phenylamino group in the molecule (SC2500-SXJ manufactured by Admatechs Co., Ltd.) Zinc molybdate: zinc molybdate filler (Z4SX-A1 manufactured by Admatechs Co., Ltd.)

[0203] [Preparation Method] First, the components other than the inorganic filler were added to a mixed solvent of toluene and methyl ethyl ketone (MEK) (mass ratio of approximately 2:1) so that the solids concentration was 40 to 50 mass% in the composition (parts by mass) shown in Table 1, and mixed. The resulting mixture was stirred for 60 minutes. Thereafter, if an inorganic filler was included, the inorganic filler was added to the resulting mixture in the composition (parts by mass) shown in Table 1, and dispersed using a bead mill. In this way, a varnish-like resin composition (varnish) was obtained.

[0204] Next, a prepreg was obtained as follows.

[0205] The resulting varnish was impregnated into a fibrous substrate (glass cloth: #2118 type T-glass manufactured by Nitto Boseki Co., Ltd.) and then heated and dried at 130°C for 3 minutes to produce a prepreg. The content of the components that constitute the resin by the curing reaction (resin content) relative to the prepreg was adjusted to approximately 43 mass%. Furthermore, the thickness after curing was adjusted to 103 μm.

[0206] An evaluation substrate (metal-clad laminate) was obtained as follows.

[0207] Twelve sheets of the obtained prepreg were stacked, and 12 μm thick copper foil (3EC-VLP manufactured by Mitsui Mining & Smelting Co., Ltd.) was placed on both sides. This was used as a pressure body, and heated to a temperature of 220°C at a temperature increase rate of 3°C / min, and then heated and pressed at 220°C for 120 minutes under a pressure of 3 MPa, to obtain an evaluation substrate (metal-clad laminate) with copper foil bonded to both sides and a resin layer thickness of approximately 1236 μm.

[0208] The evaluation substrate prepared as described above was evaluated by the following method.

[0209] [Glass Transition Temperature (Tg)] An unclad plate obtained by removing the copper foil from the evaluation substrate (metal-clad laminate) by etching was used as a test piece, and the Tg of the cured resin composition was measured using a viscoelasticity spectrometer "DMS6100" manufactured by Seiko Instruments Inc. At this time, dynamic viscoelasticity measurement (DMA) was performed with a bending module at a frequency of 10 Hz, and the temperature at which tan δ showed a maximum when the temperature was raised from room temperature to 340°C at a heating rate of 5°C / min was taken as Tg (°C). If the measured glass transition temperature was 270°C or higher, it was judged to be "passed."

[0210] [Storage Modulus] The storage modulus at 30°C was also measured by dynamic mechanical analysis (DMA) when measuring the glass transition temperature.

[0211] [Thermal expansion coefficient (50-100 ° C)] An unclad plate obtained by etching the copper foil from the evaluation substrate (metal-clad laminate) was used as a test specimen. The thermal expansion coefficient in the plane direction (tensile direction, Y direction) of the evaluation substrate at a temperature below the glass transition temperature of the cured resin composition was measured by the TMA method (thermo-mechanical analysis). Specifically, a TMA device ("TMA6000" manufactured by SII NanoTechnology Inc.) was used for the measurement in compression mode. In order to eliminate the influence of thermal distortion of the test specimen, the test specimen was pulled in the Y direction with a load of 10 g, and the temperature was raised from 30 ° C to 320 ° C at a heating rate of 10 ° C / min, and then cooled to room temperature. Then, the test specimen was pulled in the Y direction with a load of 10 g, and the temperature was raised from 30 ° C to 320 ° C at a heating rate of 10 ° C / min. A temperature displacement chart was obtained during this heating period. The average thermal expansion coefficient from 50 to 100°C was calculated from the temperature change chart obtained at this time. The lower this average thermal expansion coefficient (Y-CTE 50-100°C), the better the result, and in this test, a value of 4.0 ppm / °C or less was judged to be "pass."

[0212] [Copper Foil Peel Strength] The metal foil (copper foil) was peeled off from the evaluation substrate (metal-clad laminate), and the peel strength at this time was measured in accordance with JIS C 6481 (1996). Specifically, the copper foil was peeled off from the evaluation substrate at a rate of 50 mm / min using a tensile tester, and the peel strength at this time (N / mm) was measured.

[0213] The results of the above evaluations are shown in Table 1 together with the formulations of the resin compositions.

[0214] In Table 1, ">310" in the glass transition temperature column indicates that the temperature is greater than 310°C. When the average thermal expansion coefficient (Y-CTE 50-100°C) is 4.0 ppm / °C or less, the average thermal expansion coefficient from 210 to 260°C (Y-CTE 50-260°C) and the average thermal expansion coefficient from 50 to 260°C (Y-CTE 50-260°C) were calculated from the temperature variation chart for reference. The results are also shown in Table 1.

[0215] As can be seen from Table 1, when the resin compositions (Examples 1 to 5) contained the maleimide compound (A), the curing agent (B), and 12% by mass or more of the styrene-based polymer (C), a resin composition was obtained that gave a cured product with a low coefficient of thermal expansion, compared to the cases where the styrene-based polymer (C) was not contained (Comparative Examples 1, 2, 4, and 6) and the cases where the styrene-based polymer (C) was contained but its content was as low as less than 12% by mass (Comparative Examples 3 and 5).

[0216] The styrene polymer (C) has an acid value of 2 mg CH ３ A styrene polymer having an acid value of 2 mg CH ３ When a styrene-based polymer acid-modified with maleic anhydride so as to have a thermal expansion coefficient of ONa / g or more was used (Example 1 and Examples 3 to 5), the thermal expansion coefficient was lower even in the high temperature range (210 to 260°C) than when a non-acid-modified styrene-based polymer was used (Example 2). Note that when an inorganic filler was included (Examples 1 and 2), the storage modulus was higher than when no inorganic filler was included (Examples 3 to 5).

[0217] This application is based on Japanese Patent Application No. 2024-014384 filed on February 1, 2024, the contents of which are incorporated herein by reference.

[0218] In order to express the present invention, the present invention has been properly and sufficiently described through the embodiments in the above, but it should be recognized that those skilled in the art can easily change and / or improve the above-mentioned embodiments. Therefore, unless the changes or improvements made by those skilled in the art are at a level that causes departure from the scope of the claims described in the claims, such changes or improvements are interpreted as being included in the scope of the claims.

[0219] According to the present invention, there is provided a resin composition that can give a cured product having a low coefficient of thermal expansion. Also, according to the present invention, there are provided a prepreg, a resin-coated film, a resin-coated metal foil, a metal-clad laminate, and a wiring board that can be obtained using the resin composition.

Claims

1. A resin composition comprising: (A) a maleimide compound having, in the molecule, at least one of an indane structure and an arylene structure bonded in a meta-oriented manner; (B) a curing agent having, in the molecule, a carbon-carbon unsaturated bond; and (C) a styrene-based polymer having, in the molecule, ethylene structural units and butylene structural units, the butylene structural units accounting for 50 mol % or more of the total of the ethylene structural units and the butylene structural units, and being solid at 25°C, wherein the content of the styrene-based polymer (C) is 12 mass % or more.

2. The resin composition according to claim 1, wherein the styrene polymer (C) contains 20% by mass or less of structural units derived from a monomer containing styrene.

3. The resin composition according to claim 1, further comprising a maleimide compound (D) other than the maleimide compound (A).

4. The resin composition according to claim 1, wherein the content of the styrene polymer (C) is 20 to 60 mass% based on the total of the maleimide compound (A), the curing agent (B), and the styrene polymer (C).

5. The resin composition according to claim 1, wherein the content of the maleimide compound (A) is 20 to 50 mass % based on the total of the maleimide compound (A), the curing agent (B), and the styrene-based polymer (C).

6. The resin composition according to claim 1, wherein the content of the curing agent (B) is 5 to 40 mass % based on the total of the maleimide compound (A), the curing agent (B), and the styrene-based polymer (C).

7. The acid value of the styrene polymer (C) is 2 mg CH ３ The resin composition according to claim 1, wherein the viscosity is 1000kJ / g or more.

8. The resin composition according to claim 1, wherein the maleimide compound (A) comprises a maleimide compound (A1-1) having, as the indane structure, a structure represented by the following formula (1) in the molecule: [In formula (1), each Rb independently represents an alkyl group having 1 to 10 carbon atoms, an alkyloxy group having 1 to 10 carbon atoms, an alkylthio group having 1 to 10 carbon atoms, an aryl group having 6 to 10 carbon atoms, an aryloxy group having 6 to 10 carbon atoms, an arylthio group having 6 to 10 carbon atoms, a cycloalkyl group having 3 to 10 carbon atoms, a halogen atom, a hydroxyl group, or a mercapto group, and r represents 0 to 3.] 9. The resin composition according to claim 1, wherein the maleimide compound (A) includes a maleimide compound (A2-1) represented by the following formula (2): [In formula (2), Ar represents an arylene group bonded in a meta-position, and R Ａ , R Ｂ , R Ｃ , and R Ｄ each independently represents a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, or a phenyl group; R Ｅ , and R Ｆ each independently represents an aliphatic hydrocarbon group, and s represents 1 to 5.

10. The resin composition according to claim 1, wherein the curing agent (B) comprises at least one compound selected from the group consisting of a benzoxazine compound (B1) having an alkenyl group in the molecule, a hydrocarbon compound (B2) having a carbon-carbon unsaturated double bond in the molecule, and a polybutadiene compound (B3) having an epoxy group in the molecule.

11. The resin composition according to claim 10, wherein the hydrocarbon compound (B2) includes a hydrocarbon compound (B2-1) represented by the following formula (3): [In formula (3), X represents a hydrocarbon group having 6 or more carbon atoms and containing at least one selected from an aromatic cyclic group and an aliphatic cyclic group, and m represents 1 to 10.] 12. The resin composition according to claim 1, further comprising an inorganic filler (E).

13. A prepreg comprising the resin composition according to any one of claims 1 to 12 or a semi-cured product of said resin composition and a fibrous base material.

14. A resin-coated film comprising a resin layer containing the resin composition according to any one of claims 1 to 12 or a semi-cured product of said resin composition, and a support film.

15. A resin-coated metal foil comprising a resin layer containing the resin composition according to any one of claims 1 to 12 or a semi-cured product of said resin composition, and a metal foil.

16. A metal-clad laminate comprising an insulating layer containing a cured product of the resin composition according to any one of claims 1 to 12 and a metal foil.

17. A metal-clad laminate comprising an insulating layer containing a cured product of the prepreg according to claim 13 and a metal foil.

18. A wiring board comprising an insulating layer containing a cured product of the resin composition according to any one of claims 1 to 12, and wiring.

19. A wiring board comprising an insulating layer containing the cured product of the prepreg according to claim 13 and wiring.

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