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

Abstract

One aspect of the present invention uses a resin composition containing a maleimide compound (A) having an arylene structure oriented and bonded to the meta position in the molecule thereof and a styrene polymer which is solid at 25℃.

Description

[Technical Field]

[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. [Background technology]

[0002] As the amount of information processed increases in various electronic devices, advances in packaging technologies, such as higher integration of semiconductor devices, higher density wiring, and multi-layering, are being made. Furthermore, wiring boards used in various electronic devices are required to be high-frequency compatible, such as millimeter-wave radar boards for automotive applications. Substrate materials for constituting the insulating layers of wiring boards used in various electronic devices are required to have low relative permittivity and dielectric loss tangent in order to increase signal transmission speed and reduce loss during signal transmission. Examples of such substrate materials include resin compositions containing polyphenylene ether.

[0003] An example of such a resin composition containing polyphenylene ether is the resin composition described in Patent Document 1. Patent Document 1 describes a polyphenylene ether resin having an SP value of 9 (cal / cm 3 ) 1 / 2 The following elastomers have a weight average molecular weight of 80,000 or more, are solid at 25°C, and have an SP value of 9 (cal / cm 3 ) 1 / 2 The following describes a resin composition containing an elastomer that has a weight-average molecular weight of 40,000 or less and is liquid at 25° C. Patent Document 1 discloses that it is possible to provide a resin composition that is easy to handle in the process of laminating other laminates to form a laminate, is resistant to warping and cracking, and further has properties such as heat resistance after moisture absorption, peel strength, electrical properties, dimensional stability, and moldability that make it suitable for highly multilayered, high-frequency printed wiring boards.

[0004] Metal-clad laminates and resin-coated metal foils used in manufacturing wiring boards and the like have not only an insulating layer but also a metal foil on the insulating layer. Similarly, wiring boards also have not only an insulating layer but also wiring on the insulating layer. Examples of the wiring include wiring derived from the metal foil provided on the metal-clad laminates and the like.

[0005] In recent years, small portable devices, particularly mobile communication terminals and notebook PCs, have rapidly become more multifunctional, high-performance, thin, and compact. Accordingly, wiring boards used in these products are also required to have finer conductor wiring, more multi-layered conductor wiring layers, thinner wiring, and higher performance in terms of mechanical properties. Therefore, since wiring boards are required to prevent even finer wiring from peeling off from the insulating layer, high adhesion between the wiring and the insulating layer is even more important. Therefore, metal-clad laminates and resin-coated metal foils are required to have high adhesion between the metal foil and the insulating layer, and substrate materials for constituting the insulating layer of wiring boards are required to produce cured products with excellent adhesion to the metal foil.

[0006] Wiring boards used in various electronic devices are required to be resistant to changes in the external environment. For example, to enable use of the wiring board in high-temperature environments, the insulating layer of the wiring board is required to maintain low dielectric properties even at relatively high temperatures. Therefore, substrate materials for forming the insulating layer of a wiring board are required to produce a cured product that sufficiently suppresses increases in the relative dielectric constant and dielectric loss tangent due to temperature rise. It is also required that the insulating layer provided on the wiring board does not deform even in relatively high-temperature environments. A high glass transition temperature of the insulating layer suppresses this deformation, so substrate materials for forming the insulating layer of a wiring board are required to have a high glass transition temperature. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Laid-Open No. 2018-131519 Summary of the Invention

[0008] 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 having low dielectric properties, excellent adhesion to metal foil, a high glass transition temperature, and sufficient suppression of increases in relative dielectric constant and dielectric loss tangent due to temperature rise. 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.

[0009] One aspect of the present invention is a resin composition containing a maleimide compound (A) having an arylene structure in the molecule oriented at the meta position and bonded thereto, and a styrene-based polymer that is solid at 25°C. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a schematic cross-sectional view showing an example of a prepreg according to an embodiment of the present invention. [Figure 2] FIG. 2 is a schematic cross-sectional view showing an example of a metal-clad laminate according to an embodiment of the present invention. [Figure 3] FIG. 3 is a schematic cross-sectional view showing an example of a wiring board according to an embodiment of the present invention. [Figure 4] 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. [Figure 5] FIG. 5 is a schematic cross-sectional view showing an example of a resin-coated film according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0011] As a result of extensive investigations, the present inventors have found that the above object can be achieved by the present invention described below.

[0012] Hereinafter, embodiments of the present invention will be described, but the present invention is not limited to these.

[0013] [Resin composition] The resin composition according to this embodiment is a resin composition containing a maleimide compound (A) having in its molecule an arylene structure oriented and bonded at the meta position, and a styrene-based polymer that is solid at 25° C. By curing a resin composition having such a configuration, 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.

[0014] First, it is believed that the resin composition can be suitably cured by curing the styrene-based polymer together with the maleimide compound (A), and a cured product having low dielectric properties, high adhesion to metal foil, and a high glass transition temperature can be obtained. Furthermore, it is believed that the use of the maleimide compound (A) can sufficiently suppress increases in the dielectric constant and dielectric loss tangent of the cured product obtained by curing the resin composition due to temperature rise. Based on these findings, it is believed that the resin composition can provide a cured product having low dielectric properties, excellent adhesion to metal foil, a high glass transition temperature, and in which increases in the dielectric constant and dielectric loss tangent due to temperature rise are sufficiently suppressed.

[0015] (Maleimide compound (A)) The maleimide compound (A) is not particularly limited as long as it has an arylene structure in the molecule that is oriented and bonded at the meta position. Examples of the arylene structure that is oriented and bonded at the meta position include an arylene structure in which a structure containing a maleimide group is bonded at the meta position (an arylene structure in which a structure containing a maleimide group is substituted at the meta position). The arylene structure that is oriented and bonded at the meta position is an arylene group that is oriented and bonded at the meta position, such as a group represented by the following formula (3). Examples of the arylene structure that is oriented and bonded at the meta position include m-arylene groups such as m-phenylene and m-naphthylene groups, and more specifically, examples include a group represented by the following formula (3).

[0016] [ka]

[0017] Examples of the maleimide compound (A) include a maleimide compound (A1) represented by the following formula (1), and more specifically, a maleimide compound (A2) represented by the following formula (2).

[0018] [ka] In formula (1), Ar1 represents an arylene group bonded in a meta-position. 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 R F 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.

[0019] 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 specifically, examples thereof include groups represented by the formula (3).

[0020] 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.

[0021] 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.

[0022] In the maleimide compound (A1) represented by the formula (1), the repeating number s is preferably 1 to 5. This s is the average value of the repeating number (degree of polymerization).

[0023] [ka] In formula (2), s represents 1 to 5. This s is the same as s in formula (1) and is the average value of the number of repetitions (degree of polymerization).

[0024] The maleimide compound (A1) represented by the formula (1) and the maleimide compound (A2) represented by the formula (2) may contain a monofunctional compound where s is 0, or a polyfunctional compound such as a heptafunctional compound or an 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.

[0025] As the maleimide compound (A), a commercially available product may be used, for example, the solid content in MIR-5000-60T manufactured by Nippon Kayaku Co., Ltd.

[0026] As the maleimide compound (A), the maleimide compounds exemplified above may be used alone or in combination of two or more. For example, as the maleimide compound (A), the maleimide compound (A1) represented by formula (1) may be used alone, or two or more types of the maleimide compound (A1) represented by formula (1) may be used in combination. When two or more types of the maleimide compound (A1) represented by formula (1) are used in combination, for example, a maleimide compound (A1) represented by formula (1) other than the maleimide compound (A2) represented by formula (2) may be used in combination with the maleimide compound (A2) represented by formula (2).

[0027] (styrene polymer) The styrene polymer is not particularly limited as long as it is a styrene polymer that is solid at 25°C. Examples of the styrene polymer include a styrene polymer that is 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, etc. The resin composition used to form an insulating layer provided in a metal-clad laminate, a wiring board, etc. may be a resin composition used to form a resin layer provided in a resin-coated film, a resin-coated metal foil, etc., or a resin composition contained in a prepreg. Since the styrene polymer is solid at 25°C, it can improve adhesion to metal foil.

[0028] The styrene-based polymer may be, for example, a polymer obtained by polymerizing a monomer containing a styrene-based monomer, and may be a styrene-based copolymer. Examples of the styrene-based copolymer include copolymers obtained by copolymerizing one or more of the 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, as long as it has a structure derived from the styrene-based monomer in its molecule. Examples of the block copolymer include a binary copolymer of a structure (repeating unit) derived from the styrene-based monomer and the other copolymerizable monomer (repeating unit), and a terpolymer of a structure (repeating unit) derived from the styrene-based monomer, the other copolymerizable monomer (repeating unit), and a structure (repeating unit) derived from the styrene-based monomer. The styrene-based polymer may be a hydrogenated styrene-based copolymer obtained by hydrogenating the styrene-based copolymer.

[0029] 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, and isopropenyltoluene. The styrene-based monomer may be used alone or in combination of two or more. The copolymerizable other monomer is not particularly limited, but examples thereof include olefins such as α-pinene, β-pinene, and dipentene, non-conjugated dienes such as 1,4-hexadiene and 3-methyl-1,4-hexadiene, and conjugated dienes such as 1,3-butadiene and 2-methyl-1,3-butadiene (isoprene). The copolymerizable other monomer may be used alone or in combination of two or more.

[0030] The styrene-based polymer can be a wide variety of conventionally known polymers and is not particularly limited. For example, a polymer having a structural unit represented by the following formula (4) (a structure derived from the styrene-based monomer) in the molecule can be used.

[0031] [ka] In formula (4), R1 to R3 each independently represent a hydrogen atom or an alkyl group, and R4 represents 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.

[0032] The styrene polymer preferably contains at least one structural unit represented by the formula (4), and may contain two or more different structural units in combination. The styrene polymer may also contain a structure in which the structural unit represented by the formula (4) is repeated.

[0033] The styrene-based polymer may have, in addition to the structural unit represented by formula (4), at least one of structural units represented by the following formulas (5), (6), and (7), and structures in which the structural units represented by the following formulas (5), (6), and (7) are repeated, as structural units derived from other monomers copolymerizable with the styrene-based monomer.

[0034] [ka]

[0035] [ka]

[0036] [ka]

[0037] In the formula (5), the formula (6) and the formula (7), R5 to R 22 are each independently a 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.

[0038] The styrene polymer preferably contains at least one structural unit represented by the formula (5), the formula (6), or the formula (7), and may contain two or more different structural units in combination. The styrene polymer may also have at least one structure in which the structural units represented by the formula (5), the formula (6), or the formula (7) are repeated.

[0039] More specifically, examples of the structural unit represented by formula (4) include structural units represented by the following formulas (8) to (10). The structural unit represented by formula (4) may also be a structure in which the structural units represented by formulas (8) to (10) are respectively repeated. The structural unit represented by formula (4) may be one of these alone or a combination of two or more different types.

[0040] [ka]

[0041] [ka]

[0042] [ka]

[0043] More specifically, the structural unit represented by the formula (5) includes structural units represented by the following formulas (11) to (17). The structural unit represented by the formula (5) may also be a structure in which the structural units represented by the following formulas (11) to (17) are respectively repeated. The structural unit represented by the formula (5) may be one of these alone or a combination of two or more different types.

[0044] [ka]

[0045] [ka]

[0046] [ka]

[0047] [ka]

[0048] [ka]

[0049] [ka]

[0050] [ka]

[0051] More specifically, the structural unit represented by the formula (6) includes structural units represented by the following formulas (18) and (19). The structural unit represented by the formula (6) may also be a structure in which the structural units represented by the following formulas (18) and (19) are respectively repeated. The structural unit represented by the formula (6) may be one of these alone or a combination of two or more different types.

[0052] [ka]

[0053] [ka]

[0054] More specifically, the structural unit represented by the formula (7) includes structural units represented by the following formulas (20) and (21). The structural unit represented by the formula (7) may also be a structure in which the structural units represented by the following formulas (20) and (21) are respectively repeated. The structural unit represented by the formula (7) may be one of these alone or a combination of two or more different types.

[0055] [ka]

[0056] [ka]

[0057] Preferred examples of the styrene-based copolymer include polymers or copolymers obtained by polymerizing or copolymerizing one or more styrene-based monomers such as styrene, vinyltoluene, α-methylstyrene, isopropenyltoluene, divinylbenzene, and allylstyrene. More specific examples of the styrene-based copolymer include methylstyrene (ethylene / butylene) methylstyrene block copolymer, methylstyrene (ethylene-ethylene / propylene) methylstyrene block copolymer, styrene-isoprene block copolymer, styrene-isoprene styrene block copolymer, styrene (ethylene / butylene) styrene copolymer, styrene (ethylene-ethylene / propylene) styrene block copolymer, styrene-butadiene styrene block copolymer, styrene (butadiene / butylene) styrene block copolymer, and styrene-isobutylene styrene block copolymer. Examples of the hydrogenated styrene-based block copolymer include hydrogenated products of the styrene-based block copolymers. More specific examples of the hydrogenated styrene-based block copolymer include hydrogenated methylstyrene (ethylene / butylene) methylstyrene block copolymer, hydrogenated methylstyrene (ethylene-ethylene / propylene) methylstyrene block copolymer, hydrogenated styrene isoprene block copolymer, hydrogenated styrene isoprene styrene block copolymer, hydrogenated styrene (ethylene / butylene) styrene block copolymer, and hydrogenated styrene (ethylene-ethylene / propylene) styrene block copolymer.

[0058] As the styrene-based polymer, the above-exemplified styrene-based polymers may be used alone or in combination of two or more kinds.

[0059] The styrene polymer preferably has a weight-average molecular weight of 1,000 to 300,000, more preferably 1,200 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 when heat-molded 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).

[0060] As the styrene-based polymer, commercially available products may be used, such as V9827, V9461, 2002, and 7125F manufactured by Kuraray Co., Ltd., FTR2140 and FTR6125 manufactured by Mitsui Chemicals, Inc., and H1041 manufactured by Asahi Kasei Corporation.

[0061] (organic ingredients) The resin composition according to the present embodiment may contain, as necessary, an organic component other than the maleimide compound (A) and the styrene-based polymer, as long as the effects of the present invention are not impaired. Here, the organic component may or may not react with at least one of the maleimide compound (A) and the styrene-based polymer. Examples of the organic component include a maleimide compound (B) other than the maleimide compound (A), an epoxy compound, a methacrylate compound, an acrylate compound, a vinyl compound, a cyanate ester compound, an active ester compound, and an allyl compound.

[0062] The maleimide compound (B) is a maleimide compound having a maleimide group in the molecule and not having an arylene structure bonded in a meta-oriented manner in the molecule. Examples of the maleimide compound (B) include a maleimide compound having one or more maleimide groups in the molecule and a modified maleimide compound. The maleimide compound (B) is not particularly limited as long as it is a maleimide compound having one or more maleimide groups in the molecule and not having an arylene structure bonded in a meta-oriented manner in the molecule. Examples of the maleimide compound (B) include phenylmaleimide compounds such as 4,4'-diphenylmethane bismaleimide, polyphenylmethane 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 (B), commercially available products may be used, such as the solid content of MIR-3000-70MT manufactured by Nippon Kayaku Co., Ltd., BMI-4000 and BMI-5100 manufactured by Daiwa Kasei Kogyo Co., Ltd., and BMI-689, BMI-1500, and BMI-3000J manufactured by Designer Molecules Inc.

[0063] 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, and naphthalene ring-containing epoxy compounds. The epoxy compound also includes epoxy resins, which are polymers of the above epoxy compounds.

[0064] 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).

[0065] 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.

[0066] The vinyl compound is a compound having a vinyl group in its molecule. Examples include monofunctional vinyl compounds (monovinyl compounds) having one vinyl group in their molecule, and polyfunctional vinyl compounds having two or more vinyl groups in their molecule. Examples of polyfunctional vinyl compounds include divinylbenzene, curable polybutadienes having a carbon-carbon unsaturated double bond in their molecule, butadiene-styrene copolymers other than the styrene-based polymers, polyphenylene ether compounds having vinylbenzyl groups (ethenylbenzyl groups) at their terminals, and modified polyphenylene ethers in which the terminal hydroxyl groups of polyphenylene ethers are modified with methacrylic groups. Examples of butadiene-styrene copolymers other than the styrene-based polymers include curable butadiene-styrene copolymers having a carbon-carbon unsaturated double bond in their molecule that are liquid at 25°C, curable butadiene-styrene random copolymers having a carbon-carbon unsaturated double bond in their molecule, and curable butadiene-styrene random copolymers having a carbon-carbon unsaturated double bond in their molecule that are liquid at 25°C.

[0067] 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.

[0068] 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.

[0069] 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).

[0070] The organic component may be used alone or in combination of two or more kinds.

[0071] The weight-average molecular weight of the organic component is not particularly limited and is preferably 100 to 5000, more preferably 100 to 4000, and even more preferably 100 to 3000. If the weight-average molecular weight of the organic component is too low, the organic component may be more likely to volatilize from the resin composition. If the weight-average molecular weight of the organic component is too high, the viscosity of the resin composition varnish or the melt viscosity during heat molding may become too high, potentially resulting in poor appearance and moldability during B-stage formation. Therefore, when the weight-average molecular weight of the organic component is within this range, a resin composition with excellent heat resistance and moldability of the cured product can be obtained. This is thought to be because the resin composition can be cured appropriately. The weight-average molecular weight may be measured using a common molecular weight measurement method, specifically, a value measured using gel permeation chromatography (GPC), etc.

[0072] The organic component has an average number of functional groups per molecule that contribute to the reaction during curing of the resin composition (the number of functional groups), which varies depending on the weight-average molecular weight of the organic component, but is preferably 1 to 20, and more preferably 2 to 18. If the number of functional groups is too small, it tends to be difficult to obtain sufficient heat resistance of the cured product. On the other hand, if the number of functional groups is too large, the reactivity becomes too high, which may cause problems such as reduced shelf life and reduced fluidity of the resin composition.

[0073] (Inorganic filler) The inorganic filler is not particularly limited as long as it can be used as an inorganic filler contained in a resin composition. Examples of the inorganic filler include metal oxides such as silica, alumina, titanium oxide, magnesium oxide, and mica, metal hydroxides such as magnesium hydroxide and aluminum hydroxide, talc, aluminum borate, barium sulfate, aluminum nitride, boron nitride, barium titanate, magnesium carbonate such as anhydrous magnesium carbonate, and calcium carbonate. Among these, silica, metal hydroxides such as magnesium hydroxide and aluminum hydroxide, aluminum oxide, boron nitride, and barium titanate are preferred, and silica is more preferred. The silica is not particularly limited, and examples include crushed silica, spherical silica, and silica particles.

[0074] The inorganic filler may be a surface-treated or untreated inorganic filler. Examples of the surface treatment include treatment with a silane coupling agent.

[0075] Examples of the silane coupling agent include silane coupling agents having at least one functional group selected from the group consisting of a vinyl group, a styryl group, a methacryloyl group, an acryloyl group, a phenylamino group, an isocyanurate group, a ureido group, a mercapto group, an isocyanate group, an epoxy group, and an acid anhydride group. That is, the silane coupling agent has at least one reactive functional group selected from the group consisting of a vinyl group, a styryl group, a methacryloyl group, an acryloyl group, a phenylamino group, an isocyanurate group, a ureido group, a mercapto group, an isocyanate group, an epoxy group, and an acid anhydride group, and further includes compounds having a hydrolyzable group such as a methoxy group or an ethoxy group.

[0076] 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.

[0077] The average particle size of the inorganic filler is not particularly limited, and is preferably 0.01 to 50 μm, and more preferably 0.05 to 20 μm. Here, the average particle size refers to the volume average particle size. The volume average particle size can be measured, for example, by laser diffraction.

[0078] (Content) The content of the maleimide compound (A) is preferably 10 to 80 parts by mass, more preferably 15 to 75 parts by mass, per 100 parts by mass of the total mass of the maleimide compound (A) and the styrene-based polymer. That is, the content of the styrene-based polymer is preferably 20 to 90 parts by mass, more preferably 25 to 85 parts by mass, per 100 parts by mass of the total mass of the maleimide compound (A) and the styrene-based polymer. Furthermore, when the resin composition contains the organic component, the content of the styrene-based polymer is preferably 20 to 90 parts by mass, more preferably 25 to 85 parts by mass, per 100 parts by mass of the total mass of the maleimide compound (A), the styrene-based polymer, and the organic component. If the content of the maleimide compound (A) is too low, the effect of adding the maleimide compound (A) is less likely to be achieved, and for example, excellent heat resistance tends to be less likely to be maintained. If the content of the maleimide compound (A) is too high, adhesion to metal foil tends to be reduced. For these reasons, when the contents of the maleimide compound (A) and the styrene-based polymer are each within the above range, a cured product can be more suitably obtained that has excellent low dielectric properties and 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.

[0079] As described above, the resin composition may contain an inorganic filler. When the resin composition contains the inorganic filler, the content of the inorganic filler is preferably 1 to 250 parts by mass, and more preferably 10 to 200 parts by mass, per 100 parts by mass of the total mass of the maleimide compound (A) and the styrene-based polymer.

[0080] As described above, the resin composition may contain an organic component. When the resin composition contains the organic component, the content of the organic component is preferably 1 to 60 parts by mass, and more preferably 1 to 55 parts by mass, relative to 100 parts by mass of the total mass of the maleimide compound (A), the styrene-based polymer, and the organic component.

[0081] (Other ingredients) The resin composition according to the present embodiment may contain, as necessary, components other than the maleimide compound (A) and the styrene-based polymer (other components), as long as the effects of the present invention are not impaired. The other components contained in the resin composition according to the present embodiment may include not only the organic components and inorganic fillers described above, but also additives such as reaction initiators, reaction accelerators, catalysts, polymerization retarders, polymerization inhibitors, dispersants, leveling agents, silane coupling agents, antifoaming agents, antioxidants, heat stabilizers, antistatic agents, UV absorbers, dyes, pigments, and lubricants.

[0082] 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'-bis(t-butylperoxy-m-isopropyl)benzene, 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'-bis(t-butylperoxy-m-isopropyl)benzene is preferred. α,α'-bis(t-butylperoxy-m-isopropyl)benzene has a relatively high reaction initiation temperature, which 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, α,α'-bis(t-butylperoxy-m-isopropyl)benzene has low volatility and does not volatilize during drying or storage of the prepreg, resulting in good stability. The reaction initiators may be used alone or in combination of two or more.

[0083] 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.

[0084] As described above, the resin composition according to this embodiment may contain a flame retardant. The inclusion of a flame retardant can enhance the flame retardancy of the cured resin composition. 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, and tetradecabromodiphenoxybenzene, which have melting points of 300°C or higher, are preferred. The use of a halogen-based flame retardant is believed to suppress halogen elimination at high temperatures and prevent 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. Examples of the phosphorus-based flame retardant include, but are not limited to, phosphate ester-based flame retardants, phosphazene-based flame retardants, bisdiphenylphosphine oxide-based flame retardants, and phosphinate-based flame retardants. Specific examples of phosphate ester-based flame retardants include condensed phosphate esters of dixylenyl phosphate. A specific example of a phosphazene-based flame retardant is phenoxyphosphazene. A specific example of a bisdiphenylphosphine oxide-based flame retardant is xylylenebisdiphenylphosphine oxide. A specific example of a phosphinate-based flame retardant is, for example, a metal phosphinate salt of an aluminum dialkylphosphinate. As the flame retardant, each of the exemplified flame retardants may be used alone or in combination of two or more.

[0085] (Manufacturing method) The method for producing the resin composition is not particularly limited, and examples thereof include a method in which the maleimide compound (A) and the styrene-based polymer are mixed to a predetermined content, etc. In addition, in the case of obtaining a varnish-like composition containing an organic solvent, the method described below can be used.

[0086] Furthermore, 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.

[0087] [Prepreg] FIG. 1 is a schematic cross-sectional view showing an example of a prepreg 1 according to an embodiment of the present invention.

[0088] 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.

[0089] 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 can be exemplified by the state between when the viscosity starts to increase and when the composition is completely cured.

[0090] 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 obtained by drying or heat-drying the resin composition.

[0091] 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 the 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.

[0092] 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 polyphenylene ether compound and the organic components and does not inhibit the curing reaction. Specific examples include toluene and methyl ethyl ketone (MEK).

[0093] 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, L glass, S glass, T 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.

[0094] 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.

[0095] 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 possible to adjust the final composition and impregnation amount to the desired one.

[0096] The fibrous substrate 3 impregnated with the resin composition (resin varnish) 2 is heated under desired conditions, for example, at 80°C to 180°C for 1 minute to 10 minutes. By heating, a prepreg 1 in an uncured (A-stage) or semi-cured (B-stage) state is obtained. The heating also volatilizes the organic solvent from the resin varnish, reducing or eliminating the organic solvent.

[0097] The resin composition according to this embodiment is a resin composition that can yield a cured product having low dielectric properties, excellent adhesion to metal foil, a high glass transition temperature, and sufficient suppression of increases in dielectric constant and dielectric dissipation factor due to temperature rise. Therefore, a prepreg including this resin composition or a semi-cured product of this resin composition can yield a cured product having low dielectric properties, excellent adhesion to metal foil, a high glass transition temperature, and sufficient suppression of increases in dielectric constant and dielectric dissipation factor due to temperature rise. This prepreg can be used to suitably manufacture wiring boards that include an insulating layer containing a cured product having low dielectric properties, excellent adhesion to metal foil, a high glass transition temperature, and sufficient suppression of increases in dielectric constant and dielectric dissipation factor due to temperature rise.

[0098] [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.

[0099] 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 including 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 formed from 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-supported copper foil having a release layer and a carrier to improve handling.

[0100] 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 a method in which one or more prepregs 1 are stacked, and then a metal foil 13 such as copper foil is stacked on both or one of the upper and lower surfaces of the prepreg 1, and the metal foil 13 and the prepreg 1 are heated and pressurized 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 is obtained by stacking the metal foil 13 on the prepreg 1 and then heating and pressurizing the resulting laminate. The heating and pressurizing 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 other factors. For example, the temperature can be 170 to 220°C, the pressure can be 3 to 4 MPa, and the time can be 60 to 200 minutes. The metal-clad laminate may 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.

[0101] The resin composition according to the present embodiment is a resin composition that can yield a cured product having low dielectric properties, excellent adhesion to metal foil, a high glass transition temperature, and sufficient suppression of increases in dielectric constant and dielectric dissipation factor due to temperature rise. Therefore, a metal-clad laminate having an insulating layer containing a cured product of this resin composition is a metal-clad laminate having an insulating layer containing a cured product having low dielectric properties, excellent adhesion to metal foil, a high glass transition temperature, and sufficient suppression of increases in dielectric constant and dielectric dissipation factor due to temperature rise. This metal-clad laminate can then be used to suitably produce wiring boards having an insulating layer containing a cured product having low dielectric properties, excellent adhesion to metal foil, a high glass transition temperature, and sufficient suppression of increases in dielectric constant and dielectric dissipation factor due to temperature rise.

[0102] [Wiring board] FIG. 3 is a schematic cross-sectional view showing an example of wiring board 21 according to an embodiment of the present invention.

[0103] 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 composed of 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.

[0104] The method for producing the wiring board 21 is not particularly limited as long as it can produce the wiring board 21. Specifically, a method for producing the wiring board 21 using the prepreg 1 is exemplified. For example, the method includes a method for producing 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 produced 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, other methods for forming a circuit include circuit formation by a semi-additive process (SAP). The wiring board 21 is a wiring board having an insulating layer 12 containing a cured product that has low dielectric properties, excellent adhesion to the metal foil, a high glass transition temperature, and sufficient suppression of increases in the relative dielectric constant and dielectric loss tangent due to temperature rise.

[0105] [Metal foil with resin] FIG. 4 is a schematic cross-sectional view showing an example of a resin-coated metal foil 31 according to this embodiment.

[0106] 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.

[0107] 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 obtained by drying or heat-drying the resin composition. The fibrous substrate may be the same as the fibrous substrate of a prepreg.

[0108] 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.

[0109] 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 film, polyester film, polymethylpentene film, and films formed by providing a release agent layer on these films.

[0110] The method for producing the resin-coated metal foil 31 is not particularly limited as long as it can produce the resin-coated metal foil 31. Examples of methods for producing the resin-coated metal foil 31 include a method of applying the varnish-like resin composition (resin varnish) onto the metal foil 13 and heating it. The varnish-like resin composition is applied onto the metal foil 13, for example, using a bar coater. The applied resin composition is heated, for example, at 80°C or higher and 180°C or lower, for 1 minute or longer and 10 minutes or shorter. The heated resin composition is formed on the metal foil 13 as an uncured resin layer 32. Note that the heating volatilizes the organic solvent from the resin varnish, thereby reducing or removing the organic solvent.

[0111] The resin composition according to this embodiment is a resin composition that can yield a cured product having low dielectric properties, excellent adhesion to metal foil, a high glass transition temperature, and sufficient suppression of increases in dielectric constant and dielectric dissipation factor with temperature rise. Therefore, a resin-coated metal foil having a resin layer containing this resin composition or a semi-cured product of this resin composition is a resin-coated metal foil having a resin layer that can yield a cured product having low dielectric properties, excellent adhesion to metal foil, a high glass transition temperature, and sufficient suppression of increases in dielectric constant and dielectric dissipation factor with temperature rise. This resin-coated metal foil can be used to produce a wiring board having an insulating layer containing a cured product having low dielectric properties, excellent adhesion to metal foil, a high glass transition temperature, and sufficient suppression of increases in dielectric constant and dielectric dissipation factor with temperature rise. For example, by laminating the resin-coated metal foil on a wiring board, a multilayer wiring board can be produced. A wiring board obtained using such a resin-coated metal foil can be a wiring board having an insulating layer containing a cured product having low dielectric properties, excellent adhesion to metal foil, a high glass transition temperature, and sufficient suppression of increases in dielectric constant and dielectric dissipation factor with temperature rise.

[0112] [Resin-coated film] FIG. 5 is a schematic cross-sectional view showing an example of a resin-coated film 41 according to the present embodiment.

[0113] 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.

[0114] 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 include a resin layer containing a semi-cured product of the resin composition (the resin composition in B stage) and a support film, or may be a resin-coated film including 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.

[0115] 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.

[0116] The resin-coated film 41 may be provided with a cover film or the like as needed. 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.

[0117] 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.

[0118] 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 a temperature of 80°C to 180°C for 1 minute to 10 minutes. 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.

[0119] The resin composition according to this embodiment has low dielectric properties, excellent adhesion to metal foil, a high glass transition temperature, and can yield a cured product in which increases in dielectric constant and dielectric dissipation factor due to temperature are sufficiently suppressed. Therefore, a resin-coated film having a resin layer containing this resin composition or a semi-cured product of this resin composition is a resin-coated film having a resin layer that can yield a cured product in which increases in dielectric constant and dielectric dissipation factor due to temperature are sufficiently suppressed. This resin-coated film can be suitably used to produce a wiring board having an insulating layer containing a cured product in which increases in dielectric properties, excellent adhesion to metal foil, a high glass transition temperature, and can yield a cured product in which increases in dielectric constant and dielectric dissipation factor due to temperature are sufficiently suppressed. For example, a multilayer wiring board can be produced by laminating the resin-coated film on a wiring board and then peeling off the support film, or by laminating the resin-coated film on a wiring board after peeling off the support film. A wiring board obtained using such a resin-coated film has an insulating layer containing a cured product that has low dielectric properties, excellent adhesion to metal foil, a high glass transition temperature, and in which increases in relative dielectric constant and dielectric loss tangent due to temperature rise are sufficiently suppressed.

[0120] According to the present invention, there is provided a resin composition which can give a cured product having low dielectric properties, excellent adhesion to metal foil, a high glass transition temperature, and which can sufficiently suppress increases in relative dielectric constant and dielectric loss tangent due to temperature rise. 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 which can be obtained using the resin composition.

[0121] 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. [Example]

[0122] [Examples 1 to 17 and Comparative Examples 1 to 9] In this example, each component used in preparing the resin composition will be described.

[0123] (Maleimide compound (A)) Maleimide compound (A): A maleimide compound having an arylene structure in the molecule oriented at the meta position (solid content in MIR-5000-60T (a toluene solution of a maleimide compound) manufactured by Nippon Kayaku Co., Ltd., maleimide compound (A2) represented by the formula (2) above) (styrene polymer) Styrene-based polymer-1: hydrogenated methylstyrene (ethylene / butylene) methylstyrene block copolymer (V9827 manufactured by Kuraray Co., Ltd., weight-average molecular weight Mw 92000, solid at 25°C) Styrene-based polymer-2: hydrogenated methylstyrene (ethylene / ethylene propylene) methylstyrene block copolymer (V9461 manufactured by Kuraray Co., Ltd., weight average molecular weight Mw 240,000, solid at 25°C) Styrene-based polymer-3: Hydrogenated styrene (ethylene propylene) styrene block copolymer (2002 manufactured by Kuraray Co., Ltd., weight average molecular weight Mw 54,000, solid at 25°C) Styrene-based polymer-4: hydrogenated styrene-isoprene-styrene block copolymer (7125F manufactured by Kuraray Co., Ltd., weight-average molecular weight Mw 99,000, number-average molecular weight Mn 82,000, solid at 25°C) Styrene-based polymer-5: Hydrogenated styrene (ethylene butylene) styrene block copolymer (H1041 manufactured by Asahi Kasei Corporation, weight average molecular weight Mw 80,000, solid at 25°C) Styrene-based polymer-6: styrene-(methylstyrene)-based block copolymer (FTR2140 manufactured by Mitsui Chemicals, Inc., weight-average molecular weight Mw 3230, solid at 25°C) Styrene-based polymer-7: Styrene-based polymer (FTR6125 manufactured by Mitsui Chemicals, Inc., weight-average molecular weight Mw 1950, number-average molecular weight Mn 1150, solid at 25°C) (organic ingredients) Maleimide compound (B)-1: a maleimide compound not having an arylene structure oriented at the meta position in the molecule (BMI-4000 manufactured by Daiwa Chemical Industry Co., Ltd.) Maleimide compound (B)-2: A maleimide compound that does not have an arylene structure bonded in a meta-oriented manner in the molecule (BMI-5100 manufactured by Daiwa Chemical Industry Co., Ltd.) Maleimide compound (B)-3: a maleimide compound that does not have an arylene structure oriented at the meta position in the molecule (BMI-689, an N-alkyl bismaleimide compound manufactured by Designer Molecules Inc.) Maleimide compound (B)-4: a maleimide compound that does not have an arylene structure oriented at the meta position in the molecule (BMI-1500, an N-alkyl bismaleimide compound manufactured by Designer Molecules Inc.) Maleimide compound (B)-5: a maleimide compound not having an arylene structure oriented at the meta position in the molecule (BMI-3000J manufactured by Designer Molecules Inc.) Epoxy compound: dicyclopentadiene epoxy resin (HP-7200 manufactured by DIC Corporation) Vinyl compound-1: Liquid butadiene-styrene copolymer (Ricon 100 manufactured by Cray Valley, liquid at 25°C) Vinyl compound-2: a compound represented by the following formula (22) (SD-5 manufactured by Sanko Co., Ltd.)

[0124] [ka]

[0125] Vinyl compound-3: Modified polyphenylene ether (SA9000 manufactured by SABIC Innovative Plastics, weight-average molecular weight Mw 2000) in which the terminal hydroxyl groups of polyphenylene ether were modified with methacrylic groups. Vinyl compound 4: Polyphenylene ether compound having a vinylbenzyl group (ethenylbenzyl group) at the end (OPE-2st 2200, manufactured by Mitsubishi Gas Chemical Company, Inc., number average molecular weight Mn 2200) Allyl compound: triallyl isocyanurate (TAIC) (TAIC manufactured by Nippon Kasei Co., Ltd.) (Reaction initiator) PBP: α,α'-di(t-butylperoxy)diisopropylbenzene (Perbutyl P (PBP) manufactured by NOF Corporation) (Reaction accelerator) 2E4MZ: 2-ethyl-4-methylimidazole (2E4MZ manufactured by Shikoku Chemicals Corporation) (Inorganic filler) Silica: Silica particles surface-treated with a silane coupling agent containing a phenylamino group in the molecule (SC2050-MTX, manufactured by Admatechs Co., Ltd.)

[0126] [Preparation method] First, each component other than the inorganic filler was added to toluene and mixed to a solids concentration of 30% by mass in the composition (parts by mass) shown in Tables 1 and 2. The mixture was stirred for 60 minutes. The filler was then added to the resulting liquid, and the inorganic filler was dispersed using a bead mill. This resulted in a varnish-like resin composition (varnish).

[0127] Next, a resin-coated metal foil and an evaluation substrate (a cured resin-coated metal foil) were obtained as follows.

[0128] The obtained varnish was applied to a copper foil (3EC-VLP, manufactured by Mitsui Mining & Smelting Co., Ltd., thickness 12 μm) to a thickness of 50 μm, and then heated and dried for 3 minutes at 130° C. to produce a resin-coated metal foil (resin-coated copper foil). Two of the obtained resin-coated metal foils were then stacked, heated to a temperature of 220° C. at a temperature increase rate of 3° C. / min, and heated and pressed at 220° C. for 120 minutes under a pressure of 3 MPa to obtain an evaluation substrate (cured resin-coated metal foil).

[0129] The resin-coated metal foil and evaluation substrate (cured resin-coated metal foil) prepared as described above were evaluated by the following methods.

[0130] [Glass transition temperature (Tg)] The copper foil was removed by etching from the evaluation substrate (the cured product of the resin-coated metal foil) to prepare an unclad plate, which was used as a test piece, and the Tg of the cured product of the resin composition was measured using a viscoelasticity spectrometer "DMS6100" manufactured by Seiko Instruments Inc. Dynamic viscoelasticity measurement (DMA) was performed using a tensile module at a frequency of 10 Hz, and the temperature at which tan δ reached a maximum when the temperature was raised from room temperature to 320°C at a heating rate of 5°C / min was taken as Tg (°C).

[0131] If the measured Tg exceeds 300°C, it is indicated as ">300" in Table 1. If the measured Tg is less than 20°C, it is indicated as "<20" in Table 1.

[0132] [Thermal expansion coefficient] The copper foil was removed from the evaluation substrate (the cured resin-coated metal foil) by etching to obtain an unclad plate measuring 25 mm in length and 5 mm in width. The unclad plate was used as a test specimen, and the dimensional change of the test specimen was measured using a TMA device (TMA6000 manufactured by SII NanoTechnology Inc.) with a probe distance of 15 mm and a tensile load of 50 mV over a temperature range of -70 to 320°C. From this dimensional change, the average thermal expansion coefficient over a range of 30 to 260°C was calculated, and this average thermal expansion coefficient was used as the thermal expansion coefficient (CTE: ppm / °C).

[0133] [Peel Strength] The copper foil was peeled off from the evaluation substrate (cured resin-coated metal foil), and the peel strength at this time was measured in accordance with JIS C 6481 (1996). Specifically, a pattern 10 mm wide and 100 mm long was formed on the evaluation substrate, and the copper foil was peeled off at a rate of 50 mm / min using a tensile tester, and the peel strength (N / mm) at this time was measured.

[0134] [Heat resistance] The evaluation substrates (cured resin-coated metal foils) were left in dryers at 280°C and 290°C for one hour, respectively. After leaving the laminates, the presence or absence of blistering was visually observed. This observation was performed on two laminates. If no blistering was observed after leaving the laminates in the dryer at 290°C (if the number of blisterings was zero), the laminate was evaluated as "Excellent." Furthermore, if blistering was observed after leaving the laminates in the dryer at 290°C, but no blistering was observed after leaving the laminates in the dryer at 280°C (if the number of blisterings was zero), the laminate was evaluated as "Good." Furthermore, if blistering was observed after leaving the laminates in the dryer at 280°C, the laminate was evaluated as "Poor."

[0135] [Dielectric properties before heat treatment (relative permittivity and dielectric loss tangent)] The copper foil was removed from the evaluation substrate (the cured resin-coated metal foil) by etching. The resulting substrate was used as a test specimen. The specimen was placed in a dryer at 120 °C for 2 hours to remove moisture. The specimen was then removed from the dryer, placed in a desiccator, and returned to 25 °C. The dielectric constant (Dk) and dielectric loss tangent (Df) of the specimen were measured using a cavity resonator perturbation method. Specifically, the dielectric constant (Dk) and dielectric loss tangent (Df) of the specimen before heat treatment were measured at 10 GHz using a network analyzer (Keysight Technologies, Inc., N5230A).

[0136] [Dielectric properties after heat treatment (relative permittivity and dielectric loss tangent)] The test pieces used in the measurement of the dielectric constant and dielectric loss tangent before the heat treatment were subjected to a heat treatment by leaving them in a dryer at 130° C. for 168 hours (one week). The dielectric constant (Dk) and dielectric loss tangent (Df) of the heat-treated test pieces were measured in the same manner as in the measurement of the dielectric constant and dielectric loss tangent before the heat treatment.

[0137] [Change in relative dielectric constant (after heat treatment - before heat treatment)] The difference between the relative dielectric constant before and after the heat treatment (relative dielectric constant after the heat treatment - relative dielectric constant before the heat treatment) was calculated.

[0138] [Change in dielectric tangent (after heat treatment - before heat treatment)] The difference between the dielectric loss tangent before and after the heat treatment (dielectric loss tangent after the heat treatment - dielectric loss tangent before the heat treatment) was calculated.

[0139] The results of the above evaluations are shown in Tables 1 and 2. When the varnish could not be prepared, the evaluation is marked with "-".

[0140] [Table 1]

[0141] [Table 2]

[0142] As can be seen from Tables 1 and 2, when resin compositions containing a styrene-based polymer that is solid at 25°C were used (Examples 1 to 25) containing a maleimide compound having a meta-oriented arylene structure in the molecule (maleimide compound (A)), the glass transition temperature and peel strength were higher than those obtained without the maleimide compound (Examples 1 to 25). Furthermore, cured products were obtained that not only had low dielectric constants and dielectric loss tangents, but also had small changes in dielectric constant and dielectric loss tangent after heat treatment. Specifically, the resin compositions of Comparative Examples 1 and 2, which were similar to those of Example 2 except that they contained a maleimide compound (B) [(B)-1 or (B)-2] that did not have a meta-oriented arylene structure in the molecule instead of the maleimide compound (A), were unable to produce varnishes. Furthermore, even when maleimide compound (B)-3, which did not have a meta-oriented arylene structure in the molecule (Comparative Example 6), was used, a varnish could be produced depending on the maleimide compound. The resin composition of Example 2 had a high glass transition temperature and peel strength, even compared to Comparative Example 6. Furthermore, the resin composition of Example 2 had a high peel strength and a low dielectric constant and dielectric dissipation factor compared to Comparative Example 4, which was similar to Example 2 except that it did not contain the styrene-based polymer. Furthermore, the resin composition of Example 2 had a high glass transition temperature and a low dielectric constant and dielectric dissipation factor compared to compositions containing no styrene-based polymer but instead an organic component (Comparative Examples 3 and 7 to 9), or the changes in the dielectric constant and dielectric dissipation factor after heat treatment were small. Furthermore, the resin composition of Example 2 not only had low heat resistance, such as a low glass transition temperature, but also a low coefficient of thermal expansion compared to Comparative Example 5, which did not contain a maleimide compound. These findings demonstrate that the resin compositions of Examples 1 to 25 have excellent low dielectric properties and adhesion to metal foil, high glass transition temperatures, and can produce cured products in which increases in the dielectric constant and dielectric dissipation factor due to temperature are sufficiently suppressed.Furthermore, Tables 1 and 2 reveal that, even when the type of styrene-based polymer is changed, the content of maleimide compound (A) is changed, or an organic component is further added, 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 are sufficiently suppressed.

[0143] This application is based on Japanese Patent Application No. 2020-153179, filed on September 11, 2020, the contents of which are incorporated herein by reference.

[0144] 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. [Industrial Applicability]

[0145] According to the present invention, there is provided a resin composition which can give a cured product having low dielectric properties, excellent adhesion to metal foil, a high glass transition temperature, and which can sufficiently suppress increases in relative dielectric constant and dielectric loss tangent due to temperature rise. 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 which can be obtained using the resin composition.

Claims

1. a maleimide compound (A) having an arylene structure in the molecule oriented and bonded at the meta position; a styrene-based polymer having a weight average molecular weight of 80,000 to 300,000 and being solid at 25°C; The composition contains the maleimide compound (A) and an organic component other than the styrene-based polymer, The organic component is a resin composition containing at least one selected from an N-alkylbismaleimide compound, a dicyclopentadiene-type epoxy compound, and a compound having a vinylbenzyl group in the molecule.

2. The resin composition according to claim 1 , wherein the maleimide compound (A) comprises a maleimide compound (A1) represented by the following formula (1): 【Chemistry 1】 [In formula (1), Ar represents an arylene group bonded to 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.

3. The resin composition according to claim 2 , wherein the maleimide compound (A1) represented by the formula (1) includes a maleimide compound (A2) represented by the following formula (2): 【Chemistry 2】 [In formula (2), s represents 1 to 5.]

4. 4. The resin composition according to claim 1, wherein the styrene polymer comprises a hydrogenated styrene copolymer.

5. The resin composition according to claim 4, wherein the hydrogenated styrene-based copolymer comprises at least one selected from the group consisting of hydrogenated methylstyrene (ethylene / butylene) methylstyrene block copolymer, hydrogenated methylstyrene (ethylene-ethylene / propylene) methylstyrene block copolymer, hydrogenated styrene isoprene block copolymer, hydrogenated styrene isoprene styrene block copolymer, hydrogenated styrene (ethylene / butylene) styrene block copolymer, and hydrogenated styrene (ethylene-ethylene / propylene) styrene block copolymer.

6. 6. The resin composition according to claim 1, wherein the content of the maleimide compound (A) is 10 to 80 parts by mass relative to 100 parts by mass of the total mass of the maleimide compound (A) and the styrene-based polymer.

7. The resin composition according to any one of claims 1 to 6, further comprising an inorganic filler.

8. 8. The resin composition according to claim 7, wherein the content of the inorganic filler is 1 to 250 parts by mass per 100 parts by mass of the total mass of the maleimide compound (A) and the styrene-based polymer.

9. 9. The resin composition according to claim 1, wherein the content of the styrene-based polymer is 20 to 90 parts by mass relative to 100 parts by mass of the total mass of the maleimide compound (A), the styrene-based polymer, and the organic component.

10. 10. The resin composition according to claim 1, wherein the content of the organic component is 1 to 60 parts by mass relative to 100 parts by mass of the total mass of the maleimide compound (A), the styrene-based polymer, and the organic component.

11. A prepreg comprising the resin composition according to any one of claims 1 to 10 or a semi-cured product of the resin composition and a fibrous base material.

12. A resin-coated film comprising a resin layer containing the resin composition according to any one of claims 1 to 10 or a semi-cured product of the resin composition, and a support film.

13. A resin-coated metal foil comprising a resin layer containing the resin composition according to any one of claims 1 to 10 or a semi-cured product of the resin composition, and a metal foil.

14. A metal-clad laminate comprising an insulating layer containing a cured product of the resin composition according to any one of claims 1 to 10 or a cured product of the prepreg according to claim 11, and a metal foil.

15. A wiring board comprising an insulating layer containing a cured product of the resin composition according to any one of claims 1 to 10 or a cured product of the prepreg according to claim 11, and wiring.

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