Resin compositions, resin composition varnishes, and prepregs

Abstract

To provide a resin composition that yields printed circuit boards with excellent dielectric properties, and a prepreg containing the same. [Solution] The present invention provides a resin composition comprising (A) a vinyl aromatic copolymer and (B) a polyphenylene ether, wherein (A) the vinyl aromatic copolymer has structural units derived from a divinyl aromatic compound and structural units derived from a monovinyl aromatic compound, with the proportion of structural units derived from the monovinyl aromatic compound being 55 to 95 mol%, the proportion of structural units derived from the divinyl aromatic compound being 5 to 45 mol%, and the number average molecular weight being 2000 to 8000, and (B) the polyphenylene ether having 20 to 900 μmol / g of OH groups and a weight average molecular weight being 10000 to 50000.

Description

[Technical Field]

[0001] The present invention relates to resin compositions, resin composition varnishes, and prepregs. [Background technology]

[0002] In recent years, with the remarkable advancements in information network technology and the expansion of services utilizing information networks, electronic devices are required to have larger data capacities and faster processing speeds. To meet these demands, printed circuit boards (PCBs) mounted on electronic devices are now strongly required to have low dielectric constant and low dielectric loss tangent, in addition to the conventionally required properties such as insulation reliability, heat resistance, rigidity, and flame retardancy. Therefore, further improvements in dielectric loss tangent are being considered, particularly for resin compositions and glass cloth substrates, which are the main insulating materials constituting printed circuit boards.

[0003] As a resin composition, a polyphenylene ether (PPE) composition having a low dielectric constant, dielectric loss tangent, and high heat resistance is suitably used as the printed circuit board material described above. For example, the resin composition described in Patent Document 1 discloses that when a specific modified PPE, a specific cyanurate compound as a crosslinking agent, a copolymer of butadiene and styrene, and an organic peroxide are contained in predetermined proportions, it exhibits excellent low dielectric constant and low dielectric loss tangent.

[0004] Furthermore, for example, Patent Document 2 discloses that when a polymer of an aromatic compound that does not contain heteroatoms is used in the preparation of a resin composition, a resin composition with even lower dielectric constant and lower dielectric loss tangent can be obtained. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2017-82200 [Patent Document 2] International Publication No. 2017 / 115813 [Overview of the project] [Problems to be Solved by the Invention]

[0006] However, in the case of polymers of aromatic compounds containing no heteroatoms, there are significant problems with brittleness and adhesiveness. Currently, mainly PPE compositions are used as resin compositions that satisfy all the main properties such as heat resistance, processability, moldability, and conductor adhesion required for printed wiring boards. With the spread of the fifth-generation mobile communication system (5G), further reduction of the dielectric tangent of PPE compositions with excellent property balance has become an issue. However, PPE that has been reduced in molecular weight and the ends have been modified with crosslinkable functional groups, which is currently widely used, has a problem that the dielectric properties inherent to PPE are reduced due to the reduction in molecular weight.

[0007] Therefore, an object of the present invention is to provide a resin composition from which a printed wiring board having excellent dielectric properties can be obtained, and a prepreg containing the same. [Means for Solving the Problems]

[0008] As a result of intensive studies to solve the above problems, the present inventors have found that the above problems can be solved, and have completed the present invention. That is, the present invention is as follows. [1] (A) Vinyl aromatic copolymer (B) Polyphenylene ether A resin composition containing: The (A) vinyl aromatic copolymer has a structural unit derived from a divinyl aromatic compound and a structural unit derived from a monovinyl aromatic compound, the proportion of the structural unit derived from the monovinyl aromatic compound is 55 to 95 mol%, the proportion of the structural unit derived from the divinyl aromatic compound is 5 to 45 mol%, and the number average molecular weight is 2000 to 8000, The (B) polyphenylene ether has an OH group number of 20 to 900 μmol / g and a weight average molecular weight of 10000 to 50000, and is characterized by the resin composition. [[ID=??]] [2] The resin composition according to [1], wherein the proportion of components with a molecular weight of 1000 or less, obtained as the area value by gel permeation chromatography of the vinyl aromatic copolymer (A), is 1 to 30%. [3] The resin composition according to [1] or [2], wherein the (A) vinyl aromatic copolymer has a boron content of 0.5 to 5 ppm. [4] The resin composition according to any one of [1] to [3], wherein the (B) polyphenylene ether comprises 5 to 90 mol% of repeating units derived from phenol of formula (1) and 10 to 95 mol% of repeating units derived from phenol of formula (2), based on a total of 100 mol% of repeating units derived from phenol of formula (1) and repeating units derived from phenol of formula (2). [ka] (In formula (1), R 11 Each of these is independently a saturated hydrocarbon group having 1 to 6 carbon atoms which may be substituted, an aryl group having 6 to 12 carbon atoms which may be substituted, or a halogen atom, and R 12 Each of these is independently a hydrogen atom, an optionally substituted C1-C6 hydrocarbon group, an optionally substituted C6-C12 aryl group, or a halogen atom. [ka] {In formula (2), R 22 Each of these is independently a hydrogen atom, an optionally substituted saturated or unsaturated hydrocarbon group having 1 to 20 carbon atoms, an optionally substituted aryl group having 6 to 12 carbon atoms, or a halogen atom, and two R 22 Both are not hydrogen atoms, but R 21 This is a substructure represented by the following equation (3). [ka] (In formula (3), R 31 Each of these is independently a linear alkyl group having 1 to 8 carbon atoms, which may be substituted, or two R31 is a cyclic alkyl structure having 1 to 8 carbon atoms bonded thereto, and R 32 is, independently of each other, an alkylene group having 1 to 8 carbon atoms which may be substituted, b is, independently of each other, 0 or 1, and R 33 is a hydrogen atom, an alkyl group having 1 to 8 carbon atoms which may be substituted, or a phenyl group which may be substituted.)} [5] A resin composition varnish comprising the resin composition according to any one of [1] to [4] and an aromatic solvent. [6] A prepreg comprising the resin composition according to any one of [1] to [4], a base material, and an aromatic solvent, and containing 0.1 to 1.0 wt% of the aromatic solvent. [Advantages of the Invention]

[0009] According to the present invention, there can be provided a resin composition capable of obtaining a printed wiring board excellent in dielectric characteristics, and a prepreg containing the same. [Modes for Carrying Out the Invention]

[0010] Hereinafter, modes for carrying out the present invention (hereinafter simply referred to as "the present embodiment") will be described. Since the following embodiments are an aspect of the present invention, the present invention is not limited only to the following embodiments. Therefore, the following embodiments can be appropriately modified and implemented within the scope of the gist of the present invention. Also, in this specification, "~" means including the numerical values at both ends as the upper limit value and the lower limit value unless otherwise specified. In this specification, the upper limit value and the lower limit value of the numerical range can be arbitrarily combined.

[0011] The resin composition of this embodiment is a composition comprising (A) a vinyl aromatic copolymer and (B) a polyphenylene ether, wherein (A) the vinyl aromatic copolymer has structural units derived from a divinyl aromatic compound and structural units derived from a monovinyl aromatic compound, with the proportion of structural units derived from the monovinyl aromatic compound being 55 to 95 mol%, the proportion of structural units derived from the divinyl aromatic compound being 5 to 45 mol%, and the number average molecular weight being 2000 to 8000, and the number of OH groups of (B) the polyphenylene ether being 20 to 900 μmol / g, and the weight average molecular weight being 10000 to 50000.

[0012] [(A) Vinyl aromatic copolymer] The (A) vinyl aromatic copolymer of this embodiment (hereinafter sometimes simply referred to as "polymer") has structural units derived from a divinyl aromatic compound and structural units derived from a monovinyl aromatic compound, wherein the proportion of structural units derived from the monovinyl aromatic compound is 55 to 95 mol%, the proportion of structural units derived from the divinyl aromatic compound is 5 to 45 mol%, and the number average molecular weight is 2000 to 8000.

[0013] The copolymer exhibits good compatibility with PPE, fluidity during vacuum press molding, and a low dielectric loss tangent of the substrate when the proportion of monovinylbenzene-derived structural units is 55 mol% or more. When the proportion of monovinylbenzene-derived structural units is 95 mol% or less, low dielectric loss tangent structural units other than monovinylbenzene, crosslinkable structural units, etc., can be introduced into the copolymer. From this viewpoint, the proportion of monovinylbenzene-derived structural units is preferably 55 to 95 mol%, and more preferably 65 to 85 mol%.

[0014] The copolymer exhibits good compatibility with PPE, high substrate heat resistance, high Tg, and low dielectric loss tangent when the proportion of divinylbenzene-derived structural units is 5 mol% or more. When the proportion of divinylbenzene-derived structural units is 45 mol% or less, gelation and localization during the curing of the resin composition are prevented, and impregnation into glass cloth is improved during the fabrication of laminates. From this viewpoint, the proportion of divinylbenzene-derived structural units is preferably 5 to 45 mol%, and more preferably 10 to 35 mol%.

[0015] The copolymer, having a number-average molecular weight of 2000 or more, allows for control of volatility when the resin composition is applied to a glass cloth substrate, resulting in a product with stable properties. A number-average molecular weight of 8000 or less prevents adverse effects on solvent solubility, PPE compatibility, or fluidity during vacuum press molding. From this viewpoint, the number-average molecular weight (Mn) of the copolymer is preferably 2000 to 8000, more preferably 2500 to 7000, and even more preferably 3000 to 6000.

[0016] Copolymers with a molecular weight of 1000 or less, when containing 1% or more (GPC area value) of the component, tend to suppress the amount of resin powder shedding from the prepreg after coating the resin composition onto a glass cloth substrate and drying, thereby preventing cracks during heat resistance testing after substrate molding and improving insulation reliability between insulating layers. When the amount of component with a molecular weight of 1000 or less is 30% or less (GPC area value), the amount of resin powder shedding tends to be suppressed while suppressing curing inhibition and substrate Tg reduction during substrate molding. From this viewpoint, it is preferable that the amount of component with a molecular weight of 1000 or less in the copolymer is 1 to 30% (GPC area value). It is more preferable that the amount of this component is 1 to 20%, and even more preferable that it is 1 to 10%.

[0017] The copolymer preferably contains 0.01 to 5.0 mol% monovinylbenzene monomer. A concentration of 0.01 mol% or more tends to improve fluidity during vacuum press molding while suppressing the amount of resin powder shedding from the prepreg surface after prepreg molding. A concentration of 5.0 mol% or less tends to suppress substrate Tg reduction and improve the storage stability of the prepreg.

[0018] Copolymers with a boron content of 0.5 ppm or more tend to exhibit improved interfacial adhesion to low-dielectric glass cloth substrates containing a large amount of boron, thereby improving the adhesion, a common problem for hydrocarbon compound polymers. A boron content of 5 ppm or less suppresses the substrate's water absorption. The boron content can often be adjusted, for example, by using a boron compound as a polymerization catalyst and then purifying the material. From this perspective, the boron content of the copolymer is preferably 0.5 to 5 ppm, and more preferably 0.5 to 3 ppm.

[0019] In this embodiment, examples of monovinylbenzene constituting the copolymer include styrene, ethyl vinylbenzene, ethyl vinylnaphthalene, and ethyl vinyl biphenyl. Examples of divinylbenzene constituting the copolymer include divinylbenzene, divinylnaphthalene, and divinyl biphenyl. Among these, styrene and divinylbenzene are most preferred from the viewpoint of compatibility with PPE.

[0020] Furthermore, copolymerizable monomers other than monovinylbenzene and divinylbenzene may be introduced, to the extent that they do not impair the properties of the copolymer of this embodiment. Examples include cyclic olefin compounds such as norbornene, ethylidenenorbornene, cyclopentadiene, dicyclopentadiene, indene, and acenaphthylene.

[0021] The molecular weight distribution (Mw / Mn), expressed as the ratio of the weight-average molecular weight (Mw) to the number-average molecular weight (Mn) of the copolymer, is preferably 2.5 or less. A Mw / Mn of 2.5 or less prevents adverse effects on solvent solubility, PPE compatibility, or fluidity during vacuum press molding. From this viewpoint, the Mw / Mn of the copolymer is more preferably 1 or more and 2.0 or less, or 1 or more and less than 2.0.

[0022] As a method for producing the copolymer according to this embodiment, known polymerization methods using monovinylbenzene, divinylbenzene, or monomers copolymerizable therewith as described above may be employed. For example, cationic polymerization, anionic polymerization, radical polymerization, coordination polymerization, etc., can be used alone or in combination. For one specific synthesis of this embodiment, refer to the method described in the examples.

[0023] The amount of copolymer in the resin composition according to this embodiment is 5 to 70% by mass relative to the total amount of copolymer and PPE. From the viewpoint of compatibility with other components, or from the viewpoint of reducing the dielectric loss tangent of molded articles of resin compositions, prepregs containing resin compositions, laminates of multiple prepregs, and laminates of prepregs and substrates, improving heat resistance, and having a good appearance, the amount of copolymer is preferably 10 to 50% by mass, and more preferably 15 to 40% by mass.

[0024] [(B) Polyphenylene ether] In this embodiment, a resin composition comprising (B) polyphenylene ether is provided. (B) polyphenylene ether comprises phenylene ether units as repeating structural units. The phenylene groups in the phenylene ether units may or may not have substituents.

[0025] Furthermore, the (B) polyphenylene ether of this embodiment contains at least a repeating unit derived from the phenol of formula (1) and a repeating unit derived from the phenol of formula (2), and the repeating units in the compound may consist only of the repeating unit derived from the phenol of formula (1) and the repeating unit derived from the phenol of formula (2). [ka] (In formula (1), R 11 Each of these is independently a saturated hydrocarbon group having 1 to 6 carbon atoms which may be substituted, an aryl group having 6 to 12 carbon atoms which may be substituted, or a halogen atom, and R 12 Each of these is independently a hydrogen atom, an optionally substituted C1-C6 hydrocarbon group, an optionally substituted C6-C12 aryl group, or a halogen atom. [ka] {In formula (2), R 22 Each of these is independently a hydrogen atom, an optionally substituted saturated or unsaturated hydrocarbon group having 1 to 20 carbon atoms, an optionally substituted aryl group having 6 to 12 carbon atoms, or a halogen atom, and two R 22 Both are not hydrogen atoms, but R 21 This is a substructure represented by the following equation (3). [ka] (In formula (3), R 31 Each of these is independently a linear alkyl group having 1 to 8 carbon atoms, which may be substituted, or two R 31 It is a cyclic alkyl structure with 1 to 8 carbon atoms bonded together, R 32 Each is independently an alkylene group having 1 to 8 carbon atoms, which may be substituted, and each is independently 0 or 1, R 33 (This is one of the following: a hydrogen atom, an optionally substituted C1-C8 alkyl group, or an optionally substituted phenyl group.)

[0026] In the above equation (1), R11 Each of these is preferably an independently saturated hydrocarbon group having 1 to 6 carbon atoms or an aryl group having 6 to 12 carbon atoms, more preferably a methyl group or a phenyl group, and even more preferably a methyl group. In formula (1), the two R 11 It is preferable that both have the same structure. The above R 11 Substituents for saturated hydrocarbon groups having 1 to 6 carbon atoms and aryl groups having 6 to 12 carbon atoms include saturated or unsaturated hydrocarbon groups having 1 to 10 carbon atoms, aryl groups having 6 to 10 carbon atoms, and halogen atoms.

[0027] In the above equation (1), R 12 Each of these is preferably a hydrogen atom or a hydrocarbon group having 1 to 6 carbon atoms, and more preferably a hydrogen atom or a methyl group. In formula (1), the two R 12 These are preferably different, and more preferably one is a hydrogen atom and the other is a hydrocarbon group having 1 to 6 carbon atoms (preferably a methyl group). The above R 12 Substituents for the hydrocarbon group having 1 to 6 carbon atoms and the aryl group having 6 to 12 carbon atoms include saturated or unsaturated hydrocarbon groups having 1 to 10 carbon atoms, aryl groups having 6 to 10 carbon atoms, and halogen atoms.

[0028] In equation (2) above, R 22 Each of these is preferably independently a hydrogen atom, a saturated or unsaturated hydrocarbon group having 1 to 15 carbon atoms, or an aryl group having 6 to 12 carbon atoms that may be substituted with an alkyl group having 1 to 6 carbon atoms; more preferably a hydrogen atom, a hydrocarbon group having 1 to 6 carbon atoms, or an aryl group having 6 to 10 carbon atoms that may be substituted with an alkyl group having 1 to 6 carbon atoms; and even more preferably a hydrogen atom or a methyl group. In formula (2), the two R 22 It is preferable that they are different, and more preferably that one is a hydrogen atom and the other is a hydrocarbon group having 1 to 6 carbon atoms (preferably a methyl group). The above R 22Substituents in saturated or unsaturated hydrocarbon groups having 1 to 20 carbon atoms and aryl groups having 6 to 12 carbon atoms include saturated or unsaturated hydrocarbon groups having 1 to 10 carbon atoms, aryl groups having 6 to 10 carbon atoms, and halogen atoms.

[0029] The substructure represented by formula (3) above is preferably a group containing secondary and / or tertiary carbons, such as an isopropyl group, isobutyl group, sec-butyl group, tert-butyl group, tert-amyl group, 2,2-dimethylpropyl group, cyclohexyl group, or a structure having a phenyl group at its terminal, more preferably a tert-butyl group or a cyclohexyl group, and even more preferably a tert-butyl group. Note that the above R 31 Substituents in a linear alkyl group having 1 to 8 carbon atoms, the above R 32 Substituents in the alkylene group having 1 to 8 carbon atoms, and the above R 33 Examples of substituents on the C1-C8 alkyl group and phenyl group include C1-C10 saturated or unsaturated hydrocarbon groups, C6-C10 aryl groups, and halogen atoms.

[0030] In this embodiment, the structure of polyphenylene ether can be identified by analyzing it using techniques such as NMR and mass spectrometry. A specific method for identifying the structure of polyphenylene ether involves performing field desorption mass spectrometry (FD-MS), which is known to be less prone to fragmentation, and estimating the repeating units based on the spacing of the detected ions. Furthermore, a method for estimating the structure of polyphenylene ether can be proposed by combining electron ionization (EI) peak analysis of fragment ions with structural analysis by NMR.

[0031] The polyphenylene ether of this embodiment preferably contains 5 to 90 mol% of repeating units derived from phenol of formula (1) and 10 to 95 mol% of repeating units derived from phenol of formula (2), based on a total of 100 mol% of repeating units derived from phenol of formula (1) and repeating units derived from phenol of formula (2). From the viewpoint of obtaining a polyphenylene ether with excellent solvent solubility and low dielectric loss tangent, the repeating units derived from phenol of formula (2) are preferably 15 mol% or more, and more preferably 20 mol% or more. From a similar viewpoint, the repeating units derived from phenol of formula (1) are preferably 85 mol% or less, and more preferably 80 mol% or less. The repeating unit derived from the phenol of formula (1) contained in the polyphenylene ether of this embodiment may be one type or multiple types. Similarly, the repeating unit derived from the phenol of formula (2) contained in the polyphenylene ether of this embodiment may be one type or multiple types.

[0032] In this embodiment, with respect to 100 mol% of the monomer units contained in the polyphenylene ether (for example, all monomer units derived from phenol contained in the polyphenylene ether), the total moles of the repeating units derived from phenol of formula (1) and the repeating units derived from phenol of formula (2) are preferably 75 mol% or more, more preferably 90 mol% or more, and even more preferably 95 mol% or more.

[0033] The ratio of the repeating unit derived from phenol in formula (1) to the repeating unit derived from phenol in formula (2) is, for example, 1 H-NMR, 13 It can be determined using analytical techniques such as 13C-NMR, and more specifically, it can be measured by the method described in the examples below.

[0034] Since the phenol in formula (1) does not have an unsubstituted ortho position (i.e., hydrogen atoms are not bonded to the two ortho carbon atoms of the carbon atom to which the hydroxyl group is bonded), it can react with other phenolic monomers only at the phenolic hydroxyl group and the para carbon atom. Therefore, the repeating units derived from formula (1) include repeating units having the structure of formula (8) below. [ka] (In formula (8), R 11 and R 12 This is the same as equation (1).

[0035] The phenol of formula (2) can react with another phenolic monomer at either the ortho or para position of the phenol, in addition to the phenolic hydroxyl group. Therefore, the repeating units derived from the phenol of formula (2) have monomer units of the following formulas (9) and (10), or combinations thereof. [ka] [ka] (R in equations (9) and (10)) 21 , R 22 This is the same as equation (2).

[0036] In this embodiment, the number of OH groups in the polyphenylene ether is 20 to 900 μmol / g. A number of OH groups of 900 μmol / g or less improves compatibility with (A) vinyl aromatic copolymers, resulting in improved heat resistance, Tg, and dielectric loss tangent of the substrate. The number of OH groups is preferably 700 μmol / g or less, and more preferably 500 μmol / g or less. Furthermore, a number of OH groups of 20 μmol / g or more in the polyphenylene ether improves adhesion to copper and other materials, and tends to improve the stability of the synthesis. The number of OH groups is preferably 50 μmol or more, and more preferably 100 μmol or more. In this embodiment, the weight-average molecular weight of the polyphenylene ether is 10,000 to 50,000. A weight-average molecular weight of 10,000 or more provides high heat resistance, Tg, and low dielectric loss tangent derived from the PPE structure. A weight-average molecular weight of 50,000 or less maintains solubility in solvents and resin fluidity during substrate molding. On the other hand, compared to low molecular weight end-modified PPE, crosslinkability and resin fluidity are reduced, requiring a composition with the copolymer described above. The weight-average molecular weight of the PPE is preferably 15,000 to 40,000, and more preferably 20,000 to 35,000.

[0037] The polyphenylene ether in this embodiment may contain, in addition to the phenol of formula (1) and the phenol of formula (2), a terpolymer containing a structure derived from the divalent phenol of formula (11) below as an impurity (in this specification, this may simply be referred to as "impurity A"). The polyphenylene ether in this embodiment may be a mixture of the above polyphenylene ether and the above impurity A. The molar ratio of impurity A to 100 mol% of the polyphenylene ether in this embodiment is preferably 10 mol% or less, and more preferably 5 mol% or less.

[0038] The above impurity A can be synthesized, for example, as a terpolymer containing a structure derived from a divalent phenol with z=0 in formula (11) by reacting the following formula (12), which is generated as a byproduct during the oxidative polymerization of a monovalent phenol, with a polyphenylene ether composed of a monovalent phenol. [ka] {In formula (11), R 11 and R 12 This is the same as equation (1). z is 0 or 1, and Y is [ka] (In the formula, R 41Each of these is independently one of the following: a hydrocarbon group having 1 to 6 carbon atoms (which may be substituted), an aryl group having 6 to 12 carbon atoms (which may be substituted), or a halogen atom. [ka] (In formula (12), R 11 and R 12 This is the same as equation (1).

[0039] In this embodiment, the average number of hydroxyl groups in the polyphenylene ether is preferably less than 3.0 groups / molecule, more preferably less than 2.5 groups / molecule, and even more preferably less than 2.0 groups / molecule in the case of unmodified polyphenylene ether. If the average number of hydroxyl groups exceeds 3.0 groups / molecule, it means that the structure is not controlled and it is a highly branched, unmodified polyphenylene ether.

[0040] The polyphenylene ether in this embodiment may be a modified polyphenylene ether in which the hydroxyl groups contained in the polyphenylene ether are modified into functional groups (for example, functional groups containing unsaturated carbon bonds). In the case of a modified polyphenylene ether, the average number of hydroxyl groups is preferably less than 0.2 per molecule, more preferably less than 0.1 per molecule, and even more preferably less than 0.01 per molecule.

[0041] The polyphenylene ether in this embodiment may have at least one substructure selected from the group consisting of the following formulas (4), (5), (6), and (7). [ka] [ka] [ka] (In formula (6), R 6R is a hydrogen atom or a saturated or unsaturated hydrocarbon group having 1 to 10 carbon atoms, and the above saturated or unsaturated hydrocarbon is R 6 The substituents may be present within the range of 1 to 10 total carbon atoms. [ka] (In formula (7), R 7 R is a saturated or unsaturated divalent hydrocarbon group having 1 to 10 carbon atoms, and the above saturated or unsaturated divalent hydrocarbon is R 7 The substituents may be within the range of 1 to 10 carbon atoms, R 8 R is a hydrogen atom or a saturated or unsaturated hydrocarbon group having 1 to 10 carbon atoms, and the saturated or unsaturated hydrocarbon is R 8 The substituents may be present within the range of 1 to 10 total carbon atoms.

[0042] Furthermore, at least one substructure selected from the group consisting of formulas (4), (5), (6), and (7) above may be directly bonded to the hydroxyl group contained in the polyphenylene ether.

[0043] The polyphenylene ether in this embodiment may include a monovalent phenol having at least one unsaturated hydrocarbon group on the ortho carbon atom of the carbon atom to which the hydroxyl group of phenol is bonded. Preferably, the monovalent phenol has one unsaturated hydrocarbon group bonded to the ortho carbon atom of the carbon atom to which the hydroxyl group of phenol is bonded. The unsaturated hydrocarbon may be bonded to both ortho carbon atoms of the carbon atom to which the hydroxyl group of the monovalent phenol is bonded, or to one ortho carbon atom. Note that the monovalent phenol having at least one unsaturated hydrocarbon group on the ortho carbon atom of the carbon atom to which the hydroxyl group of phenol is bonded refers to a monovalent phenol different from the phenol of formula (1) or the phenol of formula (2).

[0044] The unsaturated hydrocarbon group is preferably an unsaturated hydrocarbon group having 3 to 10 carbon atoms, and preferably an unsaturated hydrocarbon group having 3 to 5 carbon atoms. Examples of such unsaturated hydrocarbon groups include alkenyl groups (e.g., vinyl group, allyl group, etc.) and alkynyl groups (e.g., ethynyl group, 1-propynyl, 2-propynyl, etc.). The above unsaturated hydrocarbon may have substituents to the extent that it satisfies the condition of having 3 to 10 carbon atoms.

[0045] The introduction rate of monovalent phenol having at least one unsaturated hydrocarbon group at the ortho position of the carbon atom to which the hydroxyl group of phenol is bonded can be adjusted as appropriate to control the number of curable functional groups. However, the amount of monovalent phenol having at least one unsaturated hydrocarbon group at the ortho position of the carbon atom to which the hydroxyl group of phenol is bonded is preferably 0.1 to 30 mol%, and more preferably 0.1 to 25 mol%, relative to the total amount of phenol of formula (1) and monovalent phenol having at least one unsaturated hydrocarbon group at the ortho position of the carbon atom to which the hydroxyl group of phenol is bonded.

[0046] In the polyphenylene ether of this embodiment, the molar ratio of the repeating units derived from the phenol of formula (1) and the repeating units derived from the monovalent phenol having at least one unsaturated hydrocarbon group on the ortho carbon atom to which the hydroxyl group of the phenol is bonded, to the total of the repeating units derived from the phenol of formula (1) and the repeating units derived from the monovalent phenol having at least one unsaturated hydrocarbon group on the ortho carbon atom to which the hydroxyl group of the phenol is bonded, is preferably 0.1 to 40 mol%, and more preferably 0.1 to 10 mol%.

[0047] The resin composition may contain one type of PPE or a combination of two or more types of PPE.

[0048] The amount of PPE in the resin composition according to this embodiment is 30 to 95% by mass relative to the total amount of copolymer and PPE. From the viewpoint of compatibility with other components, or from the viewpoint of reducing the dielectric loss tangent of molded articles of the resin composition, prepregs containing the resin composition, laminates of multiple prepregs, laminates of prepregs and substrates, improving heat resistance, and having a good appearance, the amount of PPE is preferably 50 to 90% by mass, and more preferably 60 to 85% by mass.

[0049] [Additives] In this embodiment, the resin composition may contain general crosslinking agents to the extent that they do not impair the properties. For example, triallyl isocyanurate compounds such as triallyl isocyanurate (TAIC) and / or triallyl cyanurate compounds such as triallyl cyanurate (TAC) further improve the compatibility between PPE and styrene copolymers, and further improve the heat resistance or conductor adhesion of the laminate. In addition to trialkenyl isocyanurate / trialkenyl cyanurate, other examples include polyfunctional methacrylate compounds having two or more methacrylate groups in the molecule, polyfunctional acrylate compounds having two or more acrylic groups in the molecule, polyfunctional vinyl compounds such as polybutadiene having two or more vinyl groups in the molecule, and polyfunctional maleimide compounds such as 4,4'-bismaleimidodiphenylmethane having two or more maleimide groups in the molecule. Other thermoplastic resins include styrene-butadiene block copolymer, styrene-ethylene-butadiene block copolymer, styrene-ethylene-butylene block copolymer, styrene-butadiene-butylene block copolymer, styrene-isoprene block copolymer, styrene-ethylene-propylene block copolymer, styrene-isobutylene block copolymer, hydrogenated styrene-butadiene block copolymer, hydrogenated styrene-ethylene-butadiene block copolymer, hydrogenated styrene-butadiene-butylene block copolymer, hydrogenated styrene-isoprene block copolymer, and styrene homopolymer (polystyrene). It is more preferable that one or more are selected from the group consisting of styrene-butadiene block copolymer, hydrogenated styrene-butadiene block copolymer, and polystyrene. The weight-average molecular weight of the thermoplastic resin is preferably 30,000 to 300,000, more preferably 31,000 to 290,000. The weight-average molecular weight is a value obtained by gel permeation chromatography on a standard polystyrene basis.

[0050] [Organic peroxide] In this embodiment, any organic peroxide having the ability to promote the polymerization reaction of the resin composition can be used. Examples of organic peroxides include benzoyl peroxide, cumene hydroperoxide, 2,5-dimethylhexane-2,5-dihydroperoxide, 2,5-dimethyl-2,5-di(t-butylperoxy)hexine-3, di-t-butyl peroxide, t-butylcumyl peroxide, di(2-t-butylperoxyisopropyl)benzene, 2,5-dimethyl-2,5-di(t-butylperoxy)hexane, dicumyl peroxide, di-t-butylperoxyisophthalate, t-butylperoxybenzoate, 2,2-bis(t-butylperoxy)butane, 2,2-bis(t-butylperoxy)octane, 2,5-dimethyl-2,5-di(benzoylperoxy)hexane, di(trimethylsilyl)peroxide, and trimethylsilyltriphenylsilyl peroxide. Furthermore, radical generators such as 2,3-dimethyl-2,3-diphenylbutane can also be used as reaction initiators for the resin composition. Among these, 2,5-dimethyl-2,5-di(t-butylperoxy)hexine-3, di(2-t-butylperoxyisopropyl)benzene, and 2,5-dimethyl-2,5-di(t-butylperoxy)hexane are preferred from the viewpoint of providing a cured product with excellent heat resistance and mechanical properties, as well as a low dielectric constant and low dielectric loss tangent.

[0051] The 1-minute half-life temperature of the organic peroxide is preferably 155°C to 185°C, or 160°C to 180°C, or 165°C to 175°C. In this specification, the 1-minute half-life temperature is the temperature at which the time it takes for the organic peroxide to decompose and its amount of reactive oxygen species to be halved is 1 minute. The 1-minute half-life temperature is a value that can be confirmed by dissolving the organic peroxide in a radical-inert solvent, such as benzene, to a concentration of 0.05 mol / L to 0.1 mol / L, and then thermally decomposing the organic peroxide solution under a nitrogen atmosphere.

[0052] When the half-life temperature of the organic peroxide is 155°C or higher, the PPE can be sufficiently melted before the reaction with the crosslinking agent can begin when the resin composition is subjected to heat and pressure molding, resulting in a tendency towards excellent moldability. On the other hand, when the half-life temperature of the organic peroxide is 185°C or lower, the decomposition rate of the organic peroxide is sufficient under normal heat and pressure molding conditions (e.g., a maximum temperature of 200°C), allowing the crosslinking reaction with the crosslinking agent to proceed efficiently and slowly, thus enabling the formation of a cured product with good electrical properties (especially dielectric loss tangent).

[0053] Examples of organic peroxides with a 1-minute half-life temperature in the range of 155°C to 185°C include t-hexylperoxyisopropyl monocarbonate (155.0°C) (the temperature in parentheses is the 1-minute half-life temperature, the same applies below), t-butylperoxy-3,5,5-trimethylhexanoate (166.0°C), t-butylperoxylaurate (159.4°C), t-butylperoxyisopropyl monocarbonate (158.8°C), t-butylperoxy-2-ethylhexyl monocarbonate (161.4°C), t-hexylperoxybenzoate (160.3°C), and 2,5-dimethyl-2,5-di(benzoylperoxy) Examples include xane (158.2°C), t-butylperoxyacetate (159.9°C), 2,2-di-(t-butylperoxy)butane (159.9°C), t-butylperoxybenzoate (166.8°C), n-butyl4,4-di-(t-butylperoxy)valerate (172.5°C), di(2-t-butylperoxyisopropyl)benzene (175.4°C), dicumyl peroxide (175.2°C), di-t-hexyl peroxide (176.7°C), 2,5-dimethyl-2,5-di(t-butylperoxy)hexane (179.8°C), and t-butylcumyl peroxide (173.3°C).

[0054] The content of organic peroxides is preferably 0.05% by mass or more, more preferably 0.1% by mass or more, even more preferably 0.3% by mass or more, and even more preferably 0.5% by mass or more, based on 100% by mass of the total mass of the resin composition, from the viewpoint of being able to increase the reaction rate, and preferably 3% by mass or less, more preferably 2% by mass or less, and even more preferably 1% by mass or less, from the viewpoint of being able to keep the dielectric constant and dielectric loss tangent of the resulting cured product low. [Flame retardant] The resin composition preferably contains a flame retardant. Examples of flame retardants include inorganic flame retardants such as antimony trioxide, aluminum hydroxide, magnesium hydroxide, and zinc borate; aromatic bromine compounds such as hexabromobenzene, decabromodiphenylethane, 4,4-dibromoviphenyl, and ethylenebistetrabromophthalimide; and phosphorus-based flame retardants such as resorcinol bis-diphenyl phosphate and resorcinol bis-dixylenyl phosphate. These flame retardants may be used individually or in combination of two or more. Among these, decabromodiphenylethane is preferred as the flame retardant from the viewpoint of achieving a low dielectric constant and low dielectric loss tangent when the resin composition is cured.

[0055] The amount of flame retardant is not particularly limited, but from the viewpoint of maintaining flame retardancy at the UL standard 94V-0 level, it is preferably 5 parts by mass or more, more preferably 10 parts by mass or more, and even more preferably 15 parts by mass or more, per 100 parts by mass of the total resin composition. Furthermore, from the viewpoint of maintaining a low dielectric constant and dielectric loss tangent of the resulting cured product, the amount of flame retardant is preferably 50 parts by mass or less, more preferably 45 parts by mass or less, and even more preferably 40 parts by mass or less.

[0056] [Silica Filler] The resin composition may contain silica filler. Either natural silica or synthetic silica can be used as the silica filler; examples include fused silica, amorphous silica, aerosil, and hollow silica. The silica filler content can be 10 to 100 parts by mass per 100 parts by mass of the total of PPE and all components usable as crosslinking agents. Furthermore, the silica filler may be surface-treated with a silane coupling agent or the like.

[0057] In addition to the components mentioned above, the resin composition may further contain additives such as heat stabilizers, antioxidants, UV absorbers, surfactants, and lubricants.

[0058] <Resin composition varnish> The resin composition can be a resin composition varnish containing a solvent, from the viewpoint of obtaining suitable fluidity when impregnating the glass cloth substrate. In the manufacturing process of the prepreg, it is preferable to impregnate the glass cloth substrate with the resin composition varnish and then dry off the solvent using a hot air dryer or the like. The solid components in the resin composition may be dissolved or dispersed in the varnish. The amount of solvent can be adjusted as appropriate so that the fluidity of the resin composition varnish is within a suitable range, but for example, the amount of solvent in the resin composition varnish may be 20 to 80% by mass, 30 to 70% by mass, or 40 to 60% by mass.

[0059] From the viewpoint of solubility of components in the resin composition, preferred solvents include aromatic compounds such as toluene and xylene, methyl ethyl ketone, cyclopentanone, cyclohexanone, and chloroform. These solvents may be used individually or in combination of two or more.

[0060] From the viewpoint of ensuring suitable fluidity of the resin composition varnish even at room temperature, it is preferable that the solvent contains an aromatic compound such as toluene. For example, toluene-methyl ethyl ketone mixed solvent, toluene-cyclohexanone mixed solvent, and toluene-cyclopentanone mixed solvent are preferred. Furthermore, in the case of the resin composition of this embodiment, toluene alone dissolves suitably in such solvents and, consequently, exhibits excellent impregnation into the substrate, so toluene alone is also preferred as a solvent. Furthermore, when the content of aromatic compound solvent in the prepreg is 0.1 to 1.0 wt%, powder shedding of the prepreg is suppressed, and curing inhibition is also suppressed. 0.1 to 0.5 wt% is more preferable.

[0061] <Laminated board (laminated structure)> This embodiment also provides a prepreg obtained by impregnating the resin composition according to this embodiment with a glass cloth formed from E glass fibers, L glass fibers, S glass fibers, quartz glass fibers, etc., or an organic fiber cloth formed from aramid resin fibers, etc., as a base material, and a laminate (laminated body) (specifically, a metal-clad laminate) obtained by optionally using a plurality of such prepregs. The dielectric loss tangent of the laminate is preferably less than 0.0033 and more preferably 0.0031 or less when measured at 10 GHz by the method described in the embodiment. The metal-clad laminate is obtained by laminating and curing the prepreg of this embodiment with a metal foil. The metal-clad laminate preferably has a form in which the cured prepreg (also called a "cured composite") and the metal foil are laminated and in close contact, and is suitably used as a material for electronic circuit boards. Examples of metal foils include aluminum foil and copper foil, and among these, copper foil is preferred because of its low electrical resistance. The cured composite combined with the metal foil may consist of one or more layers, and depending on the application, the metal foil is layered on one or both sides of the composite to form a laminate. A method for manufacturing the laminate includes, for example, forming the aforementioned prepreg, layering it with the metal foil, and then curing the resin composition to obtain a laminate in which the cured composite and the metal foil are laminated. One particularly preferred application of this laminate is a printed circuit board. For printed circuit boards, it is preferable that at least a portion of the metal foil is removed from the metal-clad laminate.

[0062] <Printed wiring board> The printed circuit board according to this embodiment is obtained by removing a portion of the metal foil from a metal-clad laminate. The printed circuit board according to this embodiment can typically be formed by a pressure-heat molding method using the prepreg according to this embodiment described above. By being manufactured from the prepreg according to this embodiment, the printed circuit board according to this embodiment has excellent heat resistance and electrical properties (low dielectric constant and low dielectric loss tangent), can suppress fluctuations in electrical properties due to environmental changes, and has excellent insulation reliability and mechanical properties. [Examples]

[0063] The embodiment will be described in detail below with reference to examples. However, this embodiment is not limited to these examples.

[0064] [material] The following materials will be used.

[0065] (copolymer) For the six combinations shown in Table 1, each component listed in Table 1 was mixed with propyl acetate in a ratio of [propyl acetate] / [monomer] = 0.95 (mol ratio). A boron trifluoride diethyl ether complex was added as a catalyst in a ratio of [catalyst] / [monomer] = 0.038 (mol ratio). Polymerization was carried out by heating at 70°C for 30 minutes, after which polymerization was stopped by adding saturated sodium bicarbonate aqueous solution. The mixture was then concentrated in an evaporator to obtain 10 types of (co)polymers. The monomers used are listed below. St: Styrene DVB: Divinylbenzene • EVB: Ethyl vinylbenzene

[0066] [Table 1]

[0067] (Method for measuring the ratio of each structural unit in vinyl aromatic copolymers) Using a JEOL nuclear magnetic resonance spectrometer (model name: JNM-ECZ500R / S1), 13 C-NMR and 1 The measurements were performed by 1H-NMR analysis. Chloroform-d1 was used as the solvent, and tetramethylsilane resonance lines were used as internal standards. The ratio of the area values ​​of the 5.2 ppm and 5.7 ppm peaks to the area value of the 5.8 ppm to 7.7 ppm peaks was defined as the ratio of structural units (a) derived from the divinyl aromatic compound, and the value obtained by subtracting the ratio of structural units (a) derived from the divinyl aromatic compound from 1 was defined as the ratio of structural units (b) derived from the monovinyl aromatic compound.

[0068] (Method for measuring the molecular weight distribution of vinyl aromatic copolymers) The number-average molecular weight (Mn) of styrene-based elastomers was determined by comparing the elution time of the sample with that of standard polystyrene with a known molecular weight using gel permeation chromatography (GPC). Specifically, a sample with a concentration of 1.0% by mass (solvent: chloroform) was prepared, and the measurement was performed using an HLC-8320GPC (manufactured by Tosoh Corporation) under the following conditions. Columns: Three Shodex K-806L columns connected in series. Eluent: Chloroform Injection volume: 100μL Flow rate: 1.0mL / min Column temperature: 40℃ Detector: RI

[0069] (PPE) PPE1: Dimethylphenol-2-tert-butyl-5-methylphenol copolymer, Mw 25000, OH group count 300 μmol / g A 40-liter jacketed polymerization tank, equipped with a sparger for introducing oxygen-containing gas, stirring turbine blades and baffles at the bottom of the tank, and a reflux condenser in the vent gas line at the top of the tank, was prepared by adding 2.4 g of cupric oxide, 18.1 g of 47% by mass aqueous solution of hydrogen bromide, 5.8 g of di-t-butylethylenediamine, 28.1 g of di-n-butylamine, 85.6 g of butyldimethylamine, 17.9 kg of toluene, 1617 g of 2,6-dimethylphenol, and 383 g of 2-tert-butyl-5-methylphenol while blowing nitrogen gas at a flow rate of 30.9 L / min to form a homogeneous solution. Next, dry air was introduced into the polymerization tank through the sparger at a rate of 21.0 L / min to start polymerization. Dry air was passed through for 105 minutes to obtain the polymerization mixture. The internal temperature was controlled to 40°C during polymerization. The polymerization mixture (polymerization solution) at the end of polymerization was in a homogeneous solution state. The supply of dry air was stopped, and 25.9 g of tetrasodium ethylenediaminetetraacetate (reagent manufactured by Dojin Chemical Laboratories) was added to the polymerization mixture as an aqueous solution in 2 kg of water. The polymerization mixture was stirred at 70°C for 150 minutes, then allowed to stand for 20 minutes, and the organic phase and aqueous phase were separated by liquid-liquid separation. The organic phase was concentrated using a rotary evaporator until the polymer concentration reached 30% by mass. The above solution was mixed with methanol in a ratio of 4 to the polymer solution, and the polymer was precipitated. Wet polyphenylene ether was obtained by vacuum filtration using a glass filter. The wet polyphenylene ether was then washed with methanol in a ratio of 4 to the wet polyphenylene ether. The above washing operation was repeated three times. After that, the wet polyphenylene ether was held at 140°C and 1 mmHg for 120 minutes to obtain dry PPE1.

[0070] PPE2: Dimethylphenol polymer, Mw 30000, OH group count 100 μmol / g The phenol raw material was 2 kg of 2,6-dimethylphenol, and the procedure was carried out in the same manner as for PPE1, except that the air supply was stopped 117 minutes after the introduction of air.

[0071] • PPE3: Product name "SA90", manufactured by Sabic Innovative Plastics, Mw: 4000, OH group count 1100 μmol / g

[0072] (Method for measuring the molecular weight distribution of PPE) As the measuring device, a gel permeation chromatography system (Shimadzu Corporation, LC-2030C Plus) was used to create a calibration curve using standard polystyrene and ethylbenzene. Using this calibration curve, the number-average molecular weight (Mn) and weight-average molecular weight (Mw) of the obtained modified polyphenylene ethers were measured. The standard polystyrenes used had molecular weights of 3,650,000, 2,170,000, 1,090,000, 681,000, 204,000, 52,000, 30,200, 13,800, 3,360, 1,300, and 550. The column used consisted of two Showa Denko K-805L columns connected in series. Chloroform was used as the solvent, with a solvent flow rate of 1.0 mL / min and a column temperature of 40°C. A 1 g / L chloroform solution of modified polyphenylene ether was prepared and used as the sample for measurement. The UV wavelength of the detection unit was set to 254 nm for standard polystyrene and 283 nm for polyphenylene ether.

[0073] (Method for measuring the OH count of PPE) 5.0 mg of polyphenylene ether was weighed. This weighed polyphenylene ether was then dissolved in 25 mL of methylene chloride. To 2.0 mL of the prepared solution, 150 μL of an ethanol solution of 2% by mass of tetraethylammonium hydroxide (TEAH) was added, and the absorbance (Abs) at 318 nm was measured using a UV spectrophotometer (Hitachi, Ltd.: U-3210 model) (using an absorbance measurement cell with a cell length of 1 cm). Based on the measurement results, the number of OH groups obtained from the absorbance was determined using the following formula (1). Number of OH groups (μmol / g)=[(25×Abs) / (ε×5)]×10 6 ...Formula (1) (Here, ε represents the extinction coefficient, which is 4700 L / mol·cm.)

[0074] (Method for measuring the number of OH groups per molecule of PPE) Using the number-average molecular weight obtained by gel permeation chromatography (details are described above), the number of OH groups per molecule of polyphenylene ether was determined by the following formula (2). Average number of hydroxyl groups per molecule (groups / molecule) = (number-average molecular weight determined using gel permeation chromatography) × (number of OH groups obtained from absorbance) / 10 6 ...Formula (2)

[0075] (Method for measuring the molar ratio of dimethylphenol-2-tert-butyl-5-methylphenol copolymer in PPE) The PPE obtained in the examples and comparative examples was dissolved in the measurement solvent (deuterated chloroform with one drop of heavy water added to eliminate the hydroxyl group), and tetramethylsilane was used as an internal standard. 1 ¹H-NMR measurements were performed using a JEOL 500MHz instrument. Before measurement, polyphenylene ether was pre-treated by holding it at 80°C and 1 mmHg for 8 hours to remove volatile components such as toluene and water, and the measurement was performed on the dry, unmodified polyphenylene ether. The signals of units derived from dimethylphenol and 2-tert-butyl-5-methylphenol were identified, and their respective proportions were calculated.

[0076] (organic peroxide) • PBP: Bis(1-tert-butylperoxy-1-methylethyl)benzene (product name "Perbutyl P", manufactured by NOF Corporation)

[0077] <Preparation of resin composition varnish> To obtain the 12 resin compositions shown in Table 2, each material was weighed in advance, a toluene / methyl ethyl ketone mixed solvent was placed in a container in a 50:50 ratio, and each material was added to the mixed solvent while stirring with a mixer. The mixture was heated to 80°C and mixed for more than 5 hours to prepare a 60% by mass resin composition varnish.

[0078] <Prepreg fabrication> Low dielectric constant glass cloth L2116 (weight 94g / m²) 2 A 91 μm thick sheet of glass cloth was impregnated with a resin composition varnish under a constant tension of approximately 100 N / m, scraped off with a slit, and dried at 120°C for 10 minutes to produce a prepreg. After drying, the prepreg was wound onto a core tube under a constant tension of approximately 200 N / m, passing through 10 rotating rolls. First, a 200 mm x 200 mm section was cut from the undried prepreg (resin-coated glass cloth) after slit scraping to confirm that the slit scraping conditions resulted in a resin adhesion of 50 wt%.

[0079] <Evaluation Method>

[0080] (1) Prepreg resin powder shedding, laminate appearance, laminate heat resistance The prepreg was unwound from the core tube and cut into 200mm x 200mm pieces. The amount of resin residue on the prepreg after cutting was calculated from the amount of resin residue on the prepreg before drying. Eight layers of prepreg are stacked and heated from room temperature at a rate of 3°C / min while applying a pressure of 5 kg / cm². 2 Vacuum pressing is performed under these conditions, and once the temperature reaches 130°C, heating is increased at a rate of 3°C / min while applying a pressure of 40 kg / cm². 2 Vacuum pressing is performed under these conditions, and once the temperature reaches 200°C, the temperature is maintained at 200°C while the pressure is 40 kg / cm². 2 The laminate was fabricated by vacuum pressing under the conditions of 60 minutes.

[0081] As part of the visual evaluation of the laminate, the presence or absence of streaks in the appearance of the laminate, which indicate areas of the glass cloth yarn bundle that were not impregnated with resin, was visually assessed (in Table 2, ○ indicates no streaks, and × indicates streaks). To evaluate the heat resistance of the laminate, five pieces of laminate were cut to 50mm x 50mm, placed in a pressure cooker at 121°C saturated vapor pressure for 10 hours, removed, and after wiping off surface moisture, they were immersed in a solder bath at 288°C for 20 seconds. The degree of swelling of the laminate was then evaluated according to the following evaluation criteria. ○ (Good): No swelling at all × (Defective): One or more blisters have formed.

[0082] (2) Dielectric loss tangent of substrate (Df, 10 GHz) Similar to the heat resistance evaluation described above, a laminate was fabricated by stacking eight prepregs, and the dielectric loss tangent at 10 GHz was measured using the cavity resonance method. The measurement was performed using a network analyzer (N5230A, Agilent Technologies) and a cavity resonator (Cavity Resornator CP series) manufactured by Kanto Electronics Applied Development Co., Ltd. (3) Interlayer insulation reliability A double-sided copper-clad laminate was fabricated by layering 12 μm thick copper foil on top of a single prepreg sheet. This laminate was then cut to 50 mm x 50 mm, and the top and bottom copper foils were etched to form electrode patterns, thus creating evaluation samples. Ten evaluation samples were placed in a constant temperature and humidity chamber at 85°C and 85%, and a voltage of 100 V was applied. The interlayer insulation reliability (%) was evaluated from the number (percentage) of short circuits after 1000 hours.

[0083] The results are shown in Table 2.

[0084] [Table 2]

[0085] As is clear from Table 2, the examples showed excellent dielectric properties and interlayer insulation reliability, and good results were obtained in terms of prepreg resin powder shedding and laminate appearance. In contrast, the comparative examples did not yield satisfactory results.

[0086] While embodiments of the present invention have been described above, the present invention is not limited thereto and can be modified as appropriate without departing from the spirit of the invention. [Industrial applicability]

[0087] The resin composition of the present invention can be suitably used in the field of resin materials useful for manufacturing printed circuit boards and prepregs that have excellent electrical and mechanical properties.

Claims

1. (A) Vinyl aromatic copolymer (B) Polyphenylene ether A resin composition containing, The vinyl aromatic copolymer (A) has structural units derived from a divinyl aromatic compound and structural units derived from a monovinyl aromatic compound, wherein the proportion of structural units derived from the monovinyl aromatic compound is 55 to 95 mol%, the proportion of structural units derived from the divinyl aromatic compound is 5 to 45 mol%, and the number average molecular weight is 2000 to 8000. The (B) polyphenylene ether contains, with respect to a total of 100 mol% of repeating units derived from the phenol of formula (1) and repeating units derived from the phenol of formula (2), 5 to 90 mol% of repeating units derived from the phenol of formula (1) and 10 to 95 mol% of repeating units derived from the phenol of formula (2). 【Chemistry 1】 (In formula (1), R 11 Each of these is independently a saturated hydrocarbon group having 1 to 6 carbon atoms which may be substituted, an aryl group having 6 to 12 carbon atoms which may be substituted, or a halogen atom, R 12 Each of these is independently a hydrogen atom, an optionally substituted C1-C6 hydrocarbon group, an optionally substituted C6-C12 aryl group, or a halogen atom. 【Chemistry 2】 {In formula (2), R 22 Each of these is independently a hydrogen atom, an optionally substituted saturated or unsaturated hydrocarbon group having 1 to 20 carbon atoms, an optionally substituted aryl group having 6 to 12 carbon atoms, or a halogen atom, and two R 22 Both are not hydrogen atoms, R 21 This is a substructure represented by the following formula (3). 【Transformation 3】 (In formula (3), R 31 is each independently a linear alkyl group having 1 to 8 carbon atoms which may be substituted, or a cyclic alkyl structure having 1 to 8 carbon atoms to which two R 31 are bonded. R 32 is each independently an alkylene group having 1 to 8 carbon atoms which may be substituted. b is each independently 0 or 1. R 33 is a hydrogen atom, an alkyl group having 1 to 8 carbon atoms which may be substituted, or a phenyl group which may be substituted.)} A resin composition characterized in that the number of OH groups of the (B) polyphenylene ether is 20 to 900 μmol / g and the weight-average molecular weight is 10,000 to 50,000.

2. The resin composition according to claim 1, wherein the proportion of the component with a molecular weight of 1000 or less, obtained as the area value by gel permeation chromatography of the vinyl aromatic copolymer (A), is 1 to 30%.

3. The resin composition according to claim 1, wherein the boron content of the vinyl aromatic copolymer (A) is 0.5 to 5 ppm.

4. A resin composition varnish comprising the resin composition according to any one of claims 1 to 3 and an aromatic solvent.

5. A prepreg comprising a resin composition according to any one of claims 1 to 3, a substrate, and an aromatic solvent, wherein the aromatic solvent is present in an amount of 0.1 to 1.0 wt%.

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