JP7513587B2 - Resin composition, prepreg, metal foil-clad laminate, resin composite sheet, and printed wiring board - Google Patents

Description

The present invention relates to a resin composition, and to a prepreg, a metal foil-clad laminate, a resin composite sheet, and a printed wiring board using the same.

In recent years, there has been an accelerating trend toward higher integration and finer design of semiconductor elements used in mobile terminals, electronic devices, communication devices, etc. Accordingly, there is a demand for technology that enables high-density mounting of semiconductor elements, and there is also a demand for improvements in printed wiring boards, which play an important role in such mounting.
On the other hand, the applications of electronic devices are becoming more diverse and expanding. In response to this, the properties required for printed wiring boards, metal foil-clad laminates, prepregs, etc. used therein are becoming more diverse and stricter. In order to obtain improved printed wiring boards while taking into account such required properties, various materials and processing methods have been proposed. One of these is the improvement and development of the resin material that constitutes the prepreg.

For example, Patent Document 1 discloses a resin composition containing (a) a terminal vinyl compound of a bifunctional phenylene ether oligomer having a polyphenylene ether skeleton, (b) a specific maleimide compound, (c) a naphthol aralkyl-type cyanate ester resin, and (d) a novolac-type epoxy resin modified with a naphthalene skeleton.

Patent Document 2 discloses a flame-retardant resin composition comprising a resin having a maleimide group at at least one end (an aminobismaleimide resin made from N,N'-4,4'-diphenylmethane bismaleimide and a diamine as raw materials) and a copolymer of brominated styrene represented by formula (c1) and divinylbenzene represented by formula (c2).

JP 2010-138364 A Japanese Patent Application Laid-Open No. 03-006293

Materials development, including the examples mentioned above, has led to improvements in various properties in semiconductor processes. However, in light of recent technological advances and the expansion of applications, there is a demand for further expansion of material options and improvements in performance and manufacturability.
Therefore, the present invention aims to provide a resin composition containing a specific maleimide compound and having a novel component composition, thereby expanding the options of materials that can be suitably used for prepregs of printed wiring boards.In addition, the present invention aims to provide a resin composition that, in terms of physical properties, sufficiently suppresses the dielectric constant and dielectric loss tangent to low values, sufficiently suppresses the changes in the dielectric constant and dielectric loss tangent after long-term heating to low values, has excellent peel resistance when made into a film or sheet, and has heat resistance sufficient for practical use, and a prepreg, a metal foil-clad laminate, a resin composite sheet, and a printed wiring board using the same.

As a result of investigations conducted by the present inventors in light of the above-mentioned problems, it was discovered that the above-mentioned problems could be solved by combining a resin composition using a maleimide compound having a specific structure with a polyfunctional vinyl aromatic polymer, and this led to the completion of the present invention. Specifically, the above-mentioned problems were solved by the following means <1>, and preferably by <2> to <10>.

（式（１）中、Ｒ^１、Ｒ^２、Ｒ^３およびＲ^４はそれぞれ独立に、水素原子、炭素数１～８のアルキル基またはフェニル基を表し、ｎ１は１以上１０以下の数を表す。）

（式（２）中、Ｒ^６はそれぞれ独立にメチル基またはエチル基を表し、Ｒ^７はそれぞれ独立に水素原子またはメチル基を表す。）

（式（３）中、Ｒ^８はそれぞれ独立に、水素原子、メチル基またはエチル基を表す。）

（式（４）中、Ｒ^９はそれぞれ独立に、水素原子、メチル基またはエチル基を表す。）
＜２＞前記多官能ビニル芳香族重合体（Ａ）が、式（Ｖ）で表される構成単位を有する重合体である、＜１＞に記載の樹脂組成物。

（式（Ｖ）中、Ａｒは芳香族炭化水素連結基を表す。＊は結合位置を表す。）
＜３＞樹脂組成物中の樹脂成分の総量１００質量部に対する、前記マレイミド化合物（Ｂ）の含有量が、５～９５質量部である、＜１＞または＜２＞に記載の樹脂組成物。
＜４＞樹脂組成物中の樹脂成分の総量１００質量部に対する、前記多官能ビニル芳香族重合体（Ａ）の含有量が、５～９５質量部である、＜１＞～＜３＞のいずれか１つに記載の樹脂組成物。
＜５＞さらに充填材（Ｃ）を含む、＜１＞～＜４＞のいずれか１つに記載の樹脂組成物。
＜６＞樹脂組成物中の樹脂成分の総量１００質量部に対する、前記充填材（Ｃ）の含有量が、１０～５００質量部である、＜５＞に記載の樹脂組成物。
＜７＞基材と、＜１＞～＜６＞のいずれか１つに記載の樹脂組成物とから形成された、プリプレグ。
＜８＞＜７＞に記載のプリプレグから形成された少なくとも１つの層と、前記プリプレグから形成された層の片面または両面に配置された金属箔とを含む、金属箔張積層板。
＜９＞支持体と、前記支持体の表面に配置された＜１＞～＜６＞のいずれか１つに記載の樹脂組成物から形成された層とを含む、樹脂複合シート。
＜１０＞絶縁層と、前記絶縁層の表面に配置された導体層とを含むプリント配線板であって、前記絶縁層が、＜１＞～＜６＞のいずれか１つに記載の樹脂組成物から形成された層および＜７＞に記載のプリプレグから形成された層の少なくとも一方を含む、プリント配線板。 <1> A resin composition comprising a polyfunctional vinyl aromatic polymer (A) and a maleimide compound (B), the maleimide compound (B) containing at least one compound represented by any one of the following formulas (1) to (4):

(In formula (1), R ¹ , R ² , R ³ and R ⁴ each independently represent a hydrogen atom, an alkyl group having 1 to 8 carbon atoms or a phenyl group, and n1 represents a number of 1 to 10.)

(In formula (2), each R ⁶ independently represents a methyl group or an ethyl group, and each R ⁷ independently represents a hydrogen atom or a methyl group.)

(In formula (3), each ^R8 independently represents a hydrogen atom, a methyl group, or an ethyl group.)

(In formula (4), each R ⁹ independently represents a hydrogen atom, a methyl group, or an ethyl group.)
<2> The resin composition according to <1>, wherein the polyfunctional vinyl aromatic polymer (A) is a polymer having a structural unit represented by formula (V).

(In formula (V), Ar represents an aromatic hydrocarbon linking group. * represents a bonding position.)
<3> The resin composition according to <1> or <2>, wherein the content of the maleimide compound (B) is 5 to 95 parts by mass based on 100 parts by mass of the total amount of resin components in the resin composition.
<4> The content of the polyfunctional vinyl aromatic polymer (A) relative to 100 parts by mass of the total amount of the resin components in the resin composition is 5 to 95 parts by mass. The resin composition according to any one of <1> to <3>.
<5> The resin composition according to any one of <1> to <4>, further comprising a filler (C).
<6> The resin composition according to <5>, wherein the content of the filler (C) is 10 to 500 parts by mass relative to 100 parts by mass of the total amount of the resin components in the resin composition.
<7> A prepreg formed from a substrate and the resin composition according to any one of <1> to <6>.
<8> A metal foil-clad laminate comprising at least one layer formed from the prepreg according to <7> and a metal foil disposed on one or both sides of the layer formed from the prepreg.
<9> A resin composite sheet comprising a support and a layer formed from the resin composition according to any one of <1> to <6>, which is disposed on a surface of the support.
<10> A printed wiring board including an insulating layer and a conductor layer disposed on a surface of the insulating layer, wherein the insulating layer includes at least one of a layer formed from the resin composition according to any one of <1> to <6> and a layer formed from the prepreg according to <7>.

According to the present invention, by providing a resin composition having a new component composition in a resin composition containing a specific maleimide compound, it is possible to expand the selection of materials that can be suitably used for prepregs. In addition, it is possible to provide a resin composition that has a sufficiently low dielectric constant and dielectric loss tangent, a sufficiently low change in the dielectric constant and dielectric loss tangent after long-term heating, excellent peel resistance against a conductor layer (metal foil) when made into a film or sheet, and heat resistance sufficient for practical use (high glass transition temperature), as well as a prepreg, a metal foil-clad laminate, a resin composite sheet, and a printed wiring board using the same.

The present invention will be described in detail below. In this specification, the word "~" is used to mean that the numerical values before and after it are included as the lower and upper limits.

（式（１）中、Ｒ^１、Ｒ^２、Ｒ^３およびＲ^４はそれぞれ独立に、水素原子、炭素数１～８のアルキル基またはフェニル基を表し、ｎ１は１以上１０以下の数を表す。）

（式（２）中、Ｒ^６はそれぞれ独立にメチル基またはエチル基を表し、Ｒ^７はそれぞれ独立に水素原子またはメチル基を表す。）

（式（３）中、Ｒ^８はそれぞれ独立に、水素原子、メチル基またはエチル基を表す。）

（式（４）中、Ｒ^９はそれぞれ独立に、水素原子、メチル基またはエチル基を表す。）
なお、本実施形態に係る樹脂組成物は、光によって硬化を進行させるのではなく、主に、熱によって硬化を進行させる非感光性熱硬化性樹脂組成物であることが好ましい。 The resin composition according to the present embodiment is characterized in that it contains a polyfunctional vinyl aromatic polymer (A) and a maleimide compound (B), and contains, as the maleimide compound (B), at least one compound represented by any one of the following formulas (1) to (4). By adopting such a constitution, it is possible to provide a resin composition which has a sufficiently low dielectric constant and dielectric loss tangent, and which also has a sufficiently low change in the dielectric constant and dielectric loss tangent after long-term heating, which has excellent peel resistance when made into a film or sheet, and which has sufficient heat resistance for practical use.

(In formula (1), R ¹ , R ² , R ³ and R ⁴ each independently represent a hydrogen atom, an alkyl group having 1 to 8 carbon atoms or a phenyl group, and n1 represents a number of 1 or more and 10 or less.)

(In formula (2), each R ⁶ independently represents a methyl group or an ethyl group, and each R ⁷ independently represents a hydrogen atom or a methyl group.)

(In formula (3), each ^R8 independently represents a hydrogen atom, a methyl group, or an ethyl group.)

(In formula (4), each R ⁹ independently represents a hydrogen atom, a methyl group, or an ethyl group.)
The resin composition according to the present embodiment is preferably a non-photosensitive thermosetting resin composition, the curing of which is promoted mainly by heat, rather than by light.

<Polyfunctional vinyl aromatic polymer (A)>
The resin composition according to this embodiment contains a polyfunctional vinyl aromatic polymer (A).
The polyfunctional vinyl aromatic polymer (A) is preferably a polymer obtained by polymerizing an aromatic compound having two or more vinyl groups in the molecule. The aromatic compound having two or more vinyl groups in the molecule may be, for example, any of the positional isomers of the vinyl group, or may be a mixture of such positional isomers. More specifically, when the polyfunctional vinyl aromatic polymer (A) is an aromatic compound having two vinyl groups in the molecule, it may be any of the m-form, p-form, o-form, or a mixture of these positional isomers, and is preferably any of the m-form, p-form, or a mixture of these positional isomers.
The monomer that constitutes the polyfunctional vinyl aromatic polymer (A) can be an aromatic compound having one or more vinyl groups (hereinafter, the aromatic compound having two or more vinyl groups is also called polyfunctional vinyl aromatic compound), and is preferably an aromatic compound having one or two vinyl groups.For example, the polyfunctional vinyl aromatic polymer (A) can be exemplified by a polymer that comprises the structural unit (a) derived from the aromatic compound having two vinyl groups (also called divinyl aromatic compound) and the structural unit (b) derived from the aromatic compound having one vinyl group.

The divinyl aromatic compound forming the structural unit (a) is preferably a compound having a hydrocarbon aromatic ring, and examples thereof include divinylbenzene, diallylbenzene, bis(vinyloxy)benzene, bis(1-methylvinyl)benzene, divinylnaphthalene, divinanthracene, divinylbiphenyl, divinylphenanthrene, and bis(4-allyloxyphenyl)fluorene. Divinylbenzene is particularly preferred. The form of the structural unit derived from the divinyl aromatic compound in the polymer may be (a-1) a form in which only one vinyl group is polymerized and the other vinyl group is left unreacted, or (a-2) a form in which both are polymerized. In this embodiment, it is preferable to include (a-1) a form in which one vinyl group is left unreacted. The polyfunctional vinyl aromatic compound (preferably the divinyl aromatic compound) may have any substituent Z (e.g., an alkyl group having 1 to 6 carbon atoms, an alkenyl group having 2 to 6 carbon atoms, an alkynyl group having 2 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, a hydroxy group, an amino group, a carboxy group, a halogen atom, etc.) within the range in which the effects of the present invention are exhibited.

式（Ｖ）中、Ａｒは芳香族炭化水素連結基を表す。具体例としては、下記Ｌ^１の例が挙げられる。式中の＊は結合位置を表す。
芳香族炭化水素連結基とは、置換基を有していてもよい芳香族炭化水素のみからなる基であってもよいし、置換基を有していてもよい芳香族炭化水素と他の連結基の組み合わせからなる基であってもよく、置換基を有していてもよい芳香族炭化水素のみからなる基であることが好ましい。なお、芳香族炭化水素が有していてもよい置換基は、上述の置換基Ｚが挙げられる。また、上記芳香族炭化水素は、置換基を有さない方が好ましい。
芳香族炭化水素連結基は、通常、２価の連結基である。 The structural unit (a) derived from the above-mentioned polyfunctional vinyl aromatic compound (preferably a divinyl aromatic compound) preferably contains a structural unit represented by the following formula (V).

In formula (V), Ar represents an aromatic hydrocarbon linking group. Specific examples include the following examples of ^L1 . In the formula, * represents a bonding position.
The aromatic hydrocarbon linking group may be a group consisting of only aromatic hydrocarbons which may have a substituent, or may be a group consisting of a combination of aromatic hydrocarbons which may have a substituent and other linking groups, and is preferably a group consisting of only aromatic hydrocarbons which may have a substituent. The substituents which the aromatic hydrocarbons may have include the above-mentioned substituent Z. It is also preferable that the aromatic hydrocarbons do not have a substituent.
The aromatic hydrocarbon linking group is usually a divalent linking group.

Specific examples of aromatic hydrocarbon linking groups include phenylene groups, naphthalenediyl groups, anthracenediyl groups, phenanthrenediyl groups, biphenyldiyl groups, and fluorenediyl groups, which may have a substituent, and among these, phenylene groups which may have a substituent are preferred. Examples of the substituent include the above-mentioned substituent Z, but it is preferable that the above-mentioned phenylene groups and other groups do not have a substituent.

It is more preferable that the structural unit (a) derived from a polyfunctional vinyl aromatic compound (preferably a divinyl aromatic compound) contains at least one of a structural unit represented by the following formula (V1), a structural unit represented by the following formula (V2), and a structural unit represented by the following formula (V3). In the following formulas, * indicates a bonding position.

式（Ｖ１）～（Ｖ３）中、Ｌ^１は芳香族炭化水素連結基（炭素数６～２２が好ましく、６～１８がより好ましく、６～１０がさらに好ましい）である。具体的には、置換基を有していてもよい、フェニレン基、ナフタレンジイル基、アントラセンジイル基、フェナントレンジイル基、ビフェニルジイル基、フルオレンジイル基が挙げられ、中でも置換基を有していてもよいフェニレン基が好ましい。置換基は、上述の置換基Ｚが例示されるが、上述したフェニレン基等の基は置換基を有さない方が好ましい。

In formulae (V1) to (V3), ^L1 is an aromatic hydrocarbon linking group (preferably having 6 to 22 carbon atoms, more preferably 6 to 18 carbon atoms, and even more preferably 6 to 10 carbon atoms). Specific examples include phenylene groups, naphthalenediyl groups, anthracenediyl groups, phenanthrenediyl groups, biphenyldiyl groups, and fluorenediyl groups, which may have a substituent, and among these, phenylene groups which may have a substituent are preferred. Examples of the substituent include the above-mentioned substituent Z, but it is preferable that the above-mentioned phenylene groups and other groups do not have a substituent.

As described above, the polyfunctional vinyl aromatic polymer (A) may be a homopolymer of the structural unit (a), but may also be a copolymer with the structural unit (b) or the like. When the polyfunctional vinyl aromatic polymer (A) is a copolymer, the copolymerization ratio of the structural unit (a) is preferably 5 mol% or more, more preferably 10 mol% or more, and even more preferably 15 mol% or more. As an upper limit, it is practical to set the upper limit to 90 mol% or less.

When the polyfunctional vinyl aromatic polymer (A) is a copolymer containing a structural unit (b) derived from a monovinyl aromatic compound, examples of the monovinyl aromatic compound include vinyl aromatic compounds such as styrene, vinylnaphthalene, and vinylbiphenyl; and nuclear alkyl-substituted vinyl aromatic compounds such as o-methylstyrene, m-methylstyrene, p-methylstyrene, o,p-dimethylstyrene, o-ethylvinylbenzene, m-ethylvinylbenzene, p-ethylvinylbenzene, methylvinylbiphenyl, and ethylvinylbiphenyl. The monovinyl aromatic compounds exemplified here may have the above-mentioned substituent Z as appropriate. In addition, these monovinyl aromatic compounds may be used alone or in combination.

It is preferable that the structural unit (b) derived from a monovinyl aromatic compound is a structural unit represented by the following formula (V4).

式（Ｖ４）中、Ｌ^２は芳香族炭化水素連結基であり、好ましいものの具体例としては、上記Ｌ^１の例が挙げられる。
Ｒ^Ｖ１は水素原子または炭素数１～１２の炭化水素基（好ましくはアルキル基）である。Ｒ^Ｖ１が炭化水素基であるとき、その炭素数は１～６が好ましく、１～３がより好ましい。Ｒ^Ｖ１およびＬ^２は上述の置換基Ｚを有していてもよい。

In formula (V4), ^L2 is an aromatic hydrocarbon linking group, and preferred specific examples include the examples of ^L1 above.
R ^V1 is a hydrogen atom or a hydrocarbon group (preferably an alkyl group) having 1 to 12 carbon atoms. When R ^V1 is a hydrocarbon group, the number of carbon atoms is preferably 1 to 6, and more preferably 1 to 3. R ^V1 and L ² may have the above-mentioned substituent Z.

When the polyfunctional vinyl aromatic polymer (A) is a copolymer containing the structural unit (b), the copolymerization ratio of the structural unit (b) is preferably 10 mol% or more, more preferably 15 mol% or more. The upper limit is preferably 98 mol% or less, more preferably 90 mol% or less, and even more preferably 85 mol% or less.

The polyfunctional vinyl aromatic polymer (A) may have other structural units. Examples of the other structural units include structural units (c) derived from a cycloolefin compound. Examples of the cycloolefin compound include hydrocarbons having a double bond in the ring structure. Specifically, in addition to monocyclic olefins such as cyclobutene, cyclopentene, cyclohexene, and cyclooctene, compounds having a norbornene ring structure such as norbornene and dicyclopentadiene, and cycloolefin compounds in which aromatic rings such as indene and acenaphthylene are condensed can be mentioned. Examples of norbornene compounds include those described in paragraphs 0037 to 0043 of JP 2018-39995 A, the contents of which are incorporated herein by reference. The cycloolefin compounds exemplified here may further have the above-mentioned substituent Z.

When the polyfunctional vinyl aromatic polymer (A) is a copolymer containing the structural unit (c), the copolymerization ratio of the structural unit (c) is preferably 10 mol% or more, more preferably 20 mol% or more, and even more preferably 30 mol% or more. The upper limit is preferably 90 mol% or less, more preferably 80 mol% or less, and even more preferably 70 mol% or less, and may be 50 mol% or less, or may be 30 mol% or less.

The polyfunctional vinyl aromatic polymer (A) may further incorporate a structural unit (d) derived from a different polymerizable compound (hereinafter also referred to as other polymerizable compound). Examples of other polymerizable compounds (monomers) include compounds containing three vinyl groups. Specific examples include 1,3,5-trivinylbenzene, 1,3,5-trivinylnaphthalene, and 1,2,4-trivinylcyclohexane. Alternatively, examples include ethylene glycol diacrylate and butadiene. The copolymerization ratio of the structural unit (d) derived from the other polymerizable compound is preferably 30 mol% or less, more preferably 20 mol% or less, and even more preferably 10 mol% or less.

An example of an embodiment of the polyfunctional vinyl aromatic polymer (A) is a polymer that essentially contains the structural unit (a) and at least one of the structural units (b) to (d).Furthermore, an example is one in which the total of the structural units (a) to (d) accounts for 95 mol % or more, or even 98 mol % or more, of all the structural units.
In another embodiment of the polyfunctional vinyl aromatic polymer (A), the structural unit (a) is essential, and among all structural units excluding the terminals, structural units containing aromatic rings preferably account for 90 mol % or more, more preferably 95 mol % or more, and may even be 100 mol %.
In calculating the mole percentage per total number of constituent units, one constituent unit is defined as being derived from one molecule of the monomer that constitutes the polyfunctional vinyl aromatic polymer (A).

The method for producing the polyfunctional vinyl aromatic polymer (A) is not particularly limited and may be a conventional method, but for example, a monomer containing a divinyl aromatic compound (optionally in the presence of a monovinyl aromatic compound, a cycloolefin compound, etc.) may be polymerized in the presence of a Lewis acid catalyst. As the Lewis acid catalyst, a metal fluoride or a complex thereof may be used.

The structure of the chain end of the polyfunctional vinyl aromatic polymer (A) is not particularly limited, but in terms of the group derived from the above divinyl aromatic compound, it may have a structure of the following formula (E1). In addition, ^L1 in formula (E1) is the same as defined in the above formula (V1). * represents a bonding position.
*-CH=CH- ^L1 -CH= _CH2 (E1)

When a group derived from a monovinyl aromatic compound is at the chain end, the structure may be that of the following formula (E2), in which ^L2 and R ^V1 are the same as defined in the above formula (V4). * represents a bonding position.
*-CH=CH-L ² -R ^V1 (E2)

The molecular weight of the polyfunctional vinyl aromatic polymer (A) is preferably 300 or more, more preferably 500 or more, and even more preferably 1,000 or more, in terms of number average molecular weight Mn. The upper limit is preferably 100,000 or less, more preferably 10,000 or less, even more preferably 5,000 or less, and even more preferably 4,000 or less. The monodispersity (Mw/Mn), which is expressed as the ratio of the weight average molecular weight Mw to the number average molecular weight Mn, is preferably 100 or less, more preferably 50 or less, and even more preferably 20 or less. A practical lower limit is 1.1 or more. The polyfunctional vinyl aromatic polymer (A) is preferably soluble in toluene, xylene, tetrahydrofuran, dichloroethane, or chloroform.

In this specification, for the polyfunctional vinyl aromatic polymer (A), reference can be made to the compounds described in paragraphs 0029 to 0058 of WO 2017/115813 and their synthesis reaction conditions, etc., the compounds described in paragraphs 0013 to 0058 of JP 2018-039995 A and their synthesis reaction conditions, etc., the compounds described in paragraphs 0008 to 0043 of JP 2018-168347 A and their synthesis reaction conditions, etc., the compounds described in paragraphs 0014 to 0042 of JP 2006-070136 A and their synthesis reaction conditions, etc., the compounds described in paragraphs 0014 to 0061 of JP 2006-089683 A and their synthesis reaction conditions, etc., and the compounds described in paragraphs 0008 to 0036 of JP 2008-248001 A and their synthesis reaction conditions, etc., which are incorporated herein by reference.

The content of the polyfunctional vinyl aromatic polymer (A) is preferably 5 parts by mass or more, more preferably 10 parts by mass or more, more preferably 15 parts by mass or more, even more preferably 20 parts by mass or more, and may be 30 parts by mass or more, 40 parts by mass or more, 50 parts by mass or more, or 60 parts by mass or more, when the total amount of the resin components in the resin composition is 100 parts by mass. By making the content of the polyfunctional vinyl aromatic polymer (A) equal to or more than the above lower limit, a low dielectric constant and a low dielectric loss tangent (particularly a low dielectric constant) can be effectively achieved. On the other hand, the upper limit of the content of the polyfunctional vinyl aromatic polymer (A) is preferably 95 parts by mass or less, more preferably 90 parts by mass or less, more preferably 85 parts by mass or less, even more preferably 80 parts by mass or less, and may be 70 parts by mass or less, when the total amount of the resin components in the resin composition is 100 parts by mass.
The polyfunctional vinyl aromatic polymer (A) may be contained in the resin composition in one type or in two or more types. When two or more types are contained, it is preferable that the total amount is in the above range.
The resin component includes the polyfunctional vinyl aromatic polymer (A) and the maleimide compound (B), and also includes other resin components described below.

（式（１）中、Ｒ^１、Ｒ^２、Ｒ^３およびＲ^４はそれぞれ独立に、水素原子、炭素数１～８のアルキル基またはフェニル基を表し、ｎ１は１以上１０以下の数を表す。）
式（１）中、Ｒ^１、Ｒ^２、Ｒ^３およびＲ^４は、それぞれ独立に、メチル基、エチル基、フェニル基または水素原子であることが好ましく、水素原子であることがより好ましい。
ｎ１は、１～１０の数を表し、１～４の数がより好ましい。ｎ１が異なる化合物が２種以上含まれていてもよい。 <Maleimide Compound (B)>
The maleimide compound (B) used in the resin composition according to this embodiment includes a compound represented by any one of the following formulas (1) to (4).

(In formula (1), R ¹ , R ² , R ³ and R ⁴ each independently represent a hydrogen atom, an alkyl group having 1 to 8 carbon atoms or a phenyl group, and n1 represents a number of 1 to 10.)
In formula (1), R ¹ , R ² , R ³ and R ⁴ are each preferably independently a methyl group, an ethyl group, a phenyl group or a hydrogen atom, and more preferably a hydrogen atom.
n1 represents a number from 1 to 10, and more preferably a number from 1 to 4. Two or more compounds having different n1 may be included.

（式（２）中、Ｒ^６はそれぞれ独立にメチル基またはエチル基を表し、Ｒ^７はそれぞれ独立に水素原子またはメチル基を表す。）
４つのＲ^６のうち、１～３つがメチル基であり、残りの３～１つがエチル基であることが好ましく、４つのＲ^６のうち、２つがメチル基であり、残りの２つがエチル基であることがより好ましい。さらに好ましくは、２つの芳香族環について、それぞれ、置換している２つのＲ^６がメチル基とエチル基であることがより好ましい。

(In formula (2), each R ⁶ independently represents a methyl group or an ethyl group, and each R ⁷ independently represents a hydrogen atom or a methyl group.)
Of the four R ⁶ , it is preferred that one to three are methyl groups and the remaining three to one are ethyl groups, and it is more preferred that two of the four R ⁶ are methyl groups and the remaining two are ethyl groups. It is even more preferred that, for each of the two aromatic rings, the two R ⁶ substituting the two are a methyl group and an ethyl group.

（式（３）中、Ｒ^８はそれぞれ独立に、水素原子、メチル基またはエチル基を表す。）
Ｒ^８はメチル基またはエチル基であることが好ましく、メチル基であることがより好ましい。

(In formula (3), each ^R8 independently represents a hydrogen atom, a methyl group, or an ethyl group.)
^R8 is preferably a methyl group or an ethyl group, and more preferably a methyl group.

（式（４）中、Ｒ^９はそれぞれ独立に、水素原子、メチル基またはエチル基を表す。）
Ｒ^９はメチル基またはエチル基であることが好ましく、メチル基であることがより好ましい。

(In formula (4), each R ⁹ independently represents a hydrogen atom, a methyl group, or an ethyl group.)
R ⁹ is preferably a methyl group or an ethyl group, and more preferably a methyl group.

The equivalent weight of the unsaturated imide group of the maleimide compound (B) is preferably 200 g/eq or more, and preferably 400 g/eq or less. When two or more types of maleimide compounds (B) are contained, the weighted average equivalent weight of the unsaturated imide group is taken into consideration of the mass of each maleimide compound (B) contained in the resin composition.

The content of the maleimide compound (B) is preferably 5 parts by mass or more, more preferably 10 parts by mass or more, even more preferably 15 parts by mass or more, even more preferably 20 parts by mass or more, and may be 30 parts by mass or more, when the total amount of the resin components in the resin composition is 100 parts by mass. By making the content of the maleimide compound (B) equal to or more than the above lower limit, peel strength and heat resistance tend to be improved. On the other hand, the upper limit of the content of the maleimide compound (B) is preferably 95 parts by mass or less, more preferably 90 parts by mass or less, even more preferably 85 parts by mass or less, even more preferably 80 parts by mass or less, and may be 70 parts by mass or less, 60 parts by mass or less, 50 parts by mass or less, or 40 parts by mass or less, when the total amount of the resin components in the resin composition is 100 parts by mass.
The maleimide compound (B) may be used alone or in combination of two or more kinds. When two or more kinds are used, the total amount thereof falls within the above range.

In the present invention, it is particularly preferable to appropriately adjust the amount of the maleimide compound (B) relative to the polyfunctional vinyl aromatic polymer (A) since the effects of the present invention can be exhibited at a high level. Specifically, the dielectric constant and dielectric tangent can be maintained at a low level, while high heat resistance and peel strength can be achieved. In view of such an action, the content of the maleimide compound (B) is preferably 6 parts by mass or more, more preferably 11 parts by mass or more, and even more preferably 25 parts by mass or more, relative to 100 parts by mass of the content of the polyfunctional vinyl aromatic polymer (A). The upper limit is preferably 1900 parts by mass or less, more preferably 900 parts by mass or less, and even more preferably 400 parts by mass or less.

In the resin composition according to this embodiment, when the filler (C) described later is not included, the resin component preferably accounts for 90 mass % or more of the resin composition, more preferably 95 mass % or more, and even more preferably 98 mass % or more.
In the resin composition according to the present embodiment, when the filler (C) is included, the resin component preferably accounts for 15% by mass or more of the resin composition, more preferably 20% by mass or more, and even more preferably 30% by mass or more. The upper limit of the resin component is preferably 90% by mass or less of the resin composition, more preferably 85% by mass or less, and even more preferably 80% by mass or less.

<Filler (C)>
The resin composition according to the present embodiment preferably contains a filler (C) in order to improve the low dielectric constant, low dielectric tangent, flame resistance and low thermal expansion, and is preferably an inorganic filler. As the filler (C) used, a known one can be appropriately used, and the type is not particularly limited, and one generally used in the industry can be suitably used. Specifically, silicas such as natural silica, fused silica, synthetic silica, amorphous silica, aerosil, and hollow silica, white carbon, titanium white, zinc oxide, magnesium oxide, zirconium oxide, boron nitride, aggregated boron nitride, silicon nitride, aluminum nitride, barium sulfate, aluminum hydroxide, aluminum hydroxide heat-treated product (aluminum hydroxide heat-treated to remove a part of the water of crystallization), boehmite, magnesium hydroxide, and other metal hydrates, molybdenum compounds such as molybdenum oxide and zinc molybdate, zinc borate, zinc stannate, alumina, clay, and other fillers can be used. Examples of fillers include inorganic fillers such as calcined clay, kaolin, talc, calcined clay, calcined kaolin, calcined talc, mica, E-glass, A-glass, NE-glass, C-glass, L-glass, D-glass, S-glass, M-glass G20, short glass fibers (including fine glass powders such as E-glass, T-glass, D-glass, S-glass, and Q-glass), hollow glass, and spherical glass, as well as organic fillers such as styrene-type, butadiene-type, and acrylic-type rubber powders, core-shell type rubber powders, silicone resin powder, silicone rubber powder, and silicone composite powder.
Among these, one or more selected from the group consisting of silica, aluminum hydroxide, boehmite, magnesium oxide and magnesium hydroxide are suitable, and silica is more preferred. The silica is preferably spherical silica. The spherical silica may also be hollow silica.
The use of these fillers improves the properties of the resin composition, such as thermal expansion properties, dimensional stability, and flame retardancy.

The content of the filler (C) in the resin composition according to the present embodiment can be appropriately set according to the desired properties, and is not particularly limited, but when the total amount of the resin components in the resin composition is 100 parts by mass, it is preferably 10 parts by mass or more, more preferably 20 parts by mass or more, even more preferably 30 parts by mass or more, and may be 50 parts by mass or more. The upper limit is preferably 500 parts by mass or less, more preferably 400 parts by mass or less, even more preferably 300 parts by mass or less, even more preferably 250 parts by mass or less, and may be 200 parts by mass or less.
The filler (C) may be used alone or in combination of two or more. When two or more fillers are used, the total amount thereof is preferably within the above range.

<Other resin components>
The resin composition according to the present embodiment may contain other resin components in addition to the above-mentioned polyfunctional vinyl aromatic polymer (A) and maleimide compound (B). Examples of the other resin components include at least one selected from the group consisting of maleimide compounds other than the above-mentioned maleimide compound (B), epoxy resins, phenolic resins, cyanate ester compounds (e.g., phenol novolac-type cyanate ester compounds, naphthol aralkyl-type cyanate ester compounds, biphenyl aralkyl-type cyanate ester compounds, naphthylene ether-type cyanate ester compounds, xylene resin-type cyanate ester compounds, adamantane skeleton-type cyanate ester compounds, bisphenol A-type cyanate ester compounds, diallyl bisphenol A-type cyanate ester compounds, bisphenol M-type cyanate ester compounds, etc.), nadimide compounds, oxetane resins, benzoxazine compounds, compounds having a polymerizable unsaturated group, modified polyphenylene ethers terminally modified with a substituent containing a carbon-carbon unsaturated double bond, elastomers, and active ester compounds.
When the resin composition according to the present embodiment contains other resin components, the content thereof is preferably, for example, 1 to 30 parts by mass relative to 100 parts by mass of the resin component.
In addition, the total content ratio of the polyfunctional vinyl aromatic polymer (A) and the maleimide compound (B) in the resin components contained in the resin composition according to this embodiment is preferably 50 mass% or more, more preferably 60 mass% or more, more preferably 70 mass% or more, and even more preferably 80 mass% or more.

<Curing accelerator (catalyst)>
The resin composition according to the present embodiment may further include a curing accelerator. The curing accelerator is not particularly limited, but examples thereof include organic metal salts (e.g., zinc octylate, zinc naphthenate, cobalt naphthenate, copper naphthenate, iron acetylacetonate, nickel octylate, manganese octylate, etc.), phenolic compounds (e.g., phenol, xylenol, cresol, resorcin, catechol, octylphenol, nonylphenol, etc.), alcohols (e.g., 1-butanol, 2-ethylhexanol, etc.), imidazoles (e.g., 2-methylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole, 1-cyanoethyl-2-phenylimidazole, etc.), and the like. imidazole, 1-cyanoethyl-2-ethyl-4-methylimidazole, 2-phenyl-4,5-dihydroxymethylimidazole, 2-phenyl-4-methyl-5-hydroxymethylimidazole, etc.), and derivatives of these imidazoles such as adducts of carboxylic acids or acid anhydrides thereof, amines (for example, dicyandiamide, benzyldimethylamine, 4-methyl-N,N-dimethylbenzylamine, etc.), phosphorus compounds (for example, phosphine compounds, phosphine oxide compounds, phosphonium salt compounds, diphosphine compounds, etc.), and epoxy-imidazole adduct compounds.
Preferred curing accelerators are imidazoles and organometallic salts, with imidazoles being more preferred.

When the curing accelerator is contained, the lower limit is preferably 0.005 parts by mass or more, more preferably 0.01 parts by mass or more, and even more preferably 0.1 parts by mass or more, relative to 100 parts by mass of the total amount of the resin components in the resin composition. The upper limit of the curing accelerator content is preferably 10 parts by mass or less, more preferably 5 parts by mass or less, and even more preferably 2 parts by mass or less, relative to 100 parts by mass of the total amount of the resin components in the resin composition.
The curing accelerator may be used alone or in combination of two or more. When two or more types are used, the total amount falls within the above range.

<Solvent>
The resin composition according to the present embodiment may contain a solvent, and preferably contains an organic solvent. In this case, the resin composition according to the present embodiment is in a form (solution or varnish) in which at least a part, preferably all, of the various resin components described above are dissolved or compatible in the solvent. The solvent is not particularly limited as long as it is a polar organic solvent or a non-polar organic solvent that can dissolve or compatible at least a part, preferably all, of the various resin components described above. Examples of polar organic solvents include ketones (e.g., acetone, methyl ethyl ketone, methyl isobutyl ketone, etc.), cellosolves (e.g., propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, etc.), esters (e.g., ethyl lactate, methyl acetate, ethyl acetate, butyl acetate, isoamyl acetate, ethyl lactate, methyl methoxypropionate, methyl hydroxyisobutyrate, etc.), amides (e.g., dimethoxyacetamide, dimethylformamides, etc.), and examples of non-polar organic solvents include aromatic hydrocarbons (e.g., toluene, xylene, etc.).
The solvents may be used alone or in combination of two or more.

<Other ingredients>
In addition to the above components, the resin composition of the present embodiment may contain, within the scope of not impairing the effects of the present invention, a flame retardant, an ultraviolet absorber, an antioxidant, a polymerization initiator (which may be either a photopolymerization initiator or a thermal polymerization initiator, and may be either a radical polymerization initiator or a cationic polymerization initiator), a fluorescent brightener, a photosensitizer, a dye, a pigment, a thickener, a flow control agent, a lubricant, an antifoaming agent, a dispersant, a leveling agent, a gloss agent, a polymerization inhibitor, a silane coupling agent, etc. These additives may be used alone or in combination of two or more.

<Physical Properties of Resin Composition>
When the resin composition according to the present embodiment is molded into a 1.6 mm thick plate-shaped cured product, the relative dielectric constant (Dk) at 10 GHz can be 2.7 or less, or can be 2.6 or less, or can be 2.5 or less. The lower limit of the dielectric constant is ideally 1.0, but 2.1 or more is practical.
Furthermore, when the resin composition according to the present embodiment is molded into a plate-like cured product having a thickness of 1.6 mm, the dielectric loss tangent (Df) at 10 GHz can be 0.0040 or less, 0.0020 or less, or 0.0015 or less. The lower limit of the dielectric constant is ideally 0, but is practically 0.0005 or more.
The dielectric constant and the dielectric loss tangent are measured by the method described in the examples below.

The resin composition according to this embodiment, when molded into a 1.6 mm thick plate-shaped cured product, can have a glass transition temperature of 200° C. or higher, can be 220° C. or higher, or can be 300° C. or higher. There is no particular upper limit to the glass transition temperature, but it is practical to set the upper limit to 400° C. or lower, or even 350° C. or lower.
The glass transition temperature is measured by the method described in the Examples section below.

<Method of producing resin composition>
The resin composition according to the present embodiment can be produced by a conventional method. For example, a polyfunctional vinyl aromatic polymer (A) and a maleimide compound (B) can be mixed. The preferred content at this time is as described above. In addition, in the resin composition according to the present embodiment, the filler (C), other resin components, and other additives may be appropriately coexisted and kneaded. By blending other resin components, the appearance may be improved or other properties may be improved.
An example of the resin composition according to the present embodiment is a varnish containing a solvent. Another example of the resin composition according to the present embodiment is a plate-shaped cured product or film. Furthermore, the resin composition according to the present embodiment is preferably used for the applications described below.

<Applications>
The resin composition according to the present embodiment can be used as a cured product. Specifically, the resin composition according to the present embodiment can be suitably used as a low dielectric constant material and/or a low dielectric tangent material, as an insulating layer of a printed wiring board, and as a material for a semiconductor package. The resin composition according to the present embodiment can be suitably used as a material for constituting a prepreg, a metal foil-clad laminate formed from a prepreg, a resin composite sheet, and a printed wiring board.
When the resin composition according to the present embodiment is used to form a layered molded product, the thickness is preferably 5 μm or more, more preferably 10 μm or more. The upper limit is preferably 2 mm or less, more preferably 1 mm or less. In addition, the thickness of the layered molded product means the thickness including the glass cloth, for example, when the resin composition according to the present embodiment is impregnated into a glass cloth or the like.
The molded article such as a film formed from the resin composition according to the present embodiment may be used for applications in which a pattern is formed by exposure and development, or for applications in which no exposure and development is required. It is particularly suitable for applications in which no exposure and development is required.

<<Prepreg>>
The prepreg according to the preferred embodiment is formed from a substrate (prepreg substrate) and the resin composition according to the present embodiment. The prepreg according to the present embodiment can be obtained, for example, by applying (for example, impregnating or coating) the resin composition according to the present embodiment to the substrate, and then semi-curing by heating (for example, a method of drying at 120 to 220°C for 2 to 15 minutes, etc.). In this case, the amount of the resin composition attached to the substrate, that is, the amount of the resin composition (including the filler) relative to the total amount of the semi-cured prepreg, is preferably in the range of 20 to 99 mass%.

The substrate is not particularly limited as long as it is a substrate used in various printed wiring board materials. Examples of the substrate material include glass fibers (e.g., E glass, D glass, L glass, S glass, T glass, Q glass, UN glass, NE glass, spherical glass, etc.), inorganic fibers other than glass (e.g., quartz, etc.), and organic fibers (e.g., polyimide, polyamide, polyester, liquid crystal polyester, etc.). The form of the substrate is not particularly limited, and substrates composed of layered fibers such as woven fabric, nonwoven fabric, roving, chopped strand mat, and surfacing mat are examples. In particular, substrates composed of long fibers such as glass cloth are preferred. Here, long fibers refer to, for example, those having a number average fiber length of 6 mm or more. These substrates can be used alone or in combination of two or more. Among these substrates, from the viewpoint of dimensional stability, woven fabrics that have been subjected to ultra-opening treatment and clogging treatment are preferred, from the viewpoint of moisture absorption and heat resistance, glass woven fabrics that have been surface-treated with a silane coupling agent such as epoxy silane treatment or amino silane treatment are preferred, and from the viewpoint of electrical properties, low-dielectric glass cloths made of glass fibers exhibiting low dielectric constant and low dielectric loss tangent, such as L-glass, NE-glass, Q-glass, etc. The thickness of the substrate is not particularly limited and may be, for example, about 0.01 to 0.19 mm.

<<Metal foil laminate>>
A metal foil-clad laminate according to a preferred embodiment includes at least one layer formed from the prepreg of this embodiment and a metal foil arranged on one or both sides of the layer formed from the prepreg. The metal foil-clad laminate of this embodiment can be produced, for example, by arranging at least one prepreg of this embodiment (preferably two or more sheets are stacked), arranging a metal foil on one or both sides of the prepreg, and laminating and molding it. More specifically, it can be produced by arranging a metal foil such as copper or aluminum on one or both sides of the prepreg and laminating and molding it. The number of prepregs is preferably 1 to 10 sheets, more preferably 2 to 10 sheets, and even more preferably 2 to 7 sheets. The metal foil is not particularly limited as long as it is used as a material for printed wiring boards, and examples of the metal foil include copper foil such as rolled copper foil and electrolytic copper foil. The thickness of the copper foil is not particularly limited and may be about 1.5 to 70 μm. Examples of the molding method include methods that are commonly used when molding laminates and multilayer boards for printed wiring boards. More specifically, a method of laminating and molding using a multi-stage press machine, a multi-stage vacuum press machine, a continuous molding machine, an autoclave molding machine, or the like at a temperature of about 180 to 350°C, a heating time of about 100 to 300 minutes, and a surface pressure of about 20 to 100 kg/ ^cm2 can be mentioned. In addition, a multilayer board can be made by combining and laminating a wiring board for an inner layer (also called an inner layer circuit board) separately prepared in combination with the prepreg of this embodiment. As a manufacturing method for a multilayer board, for example, a copper foil of about 35 μm is placed on both sides of one prepreg of this embodiment, and the laminate is formed by the above molding method, and then an inner layer circuit is formed, and this circuit is blackened to form an inner layer circuit board, and then the inner layer circuit board and the prepreg of this embodiment are alternately placed one by one, and copper foil is further placed on the outermost layer, and laminated and molded preferably under vacuum under the above conditions to produce a multilayer board. The metal foil-clad laminate of this embodiment can be suitably used as a printed wiring board.

<<Printed wiring board>>
A preferred embodiment of the printed wiring board includes an insulating layer and a conductor layer disposed on the surface of the insulating layer, and the insulating layer includes at least one of a layer formed from the resin composition according to the present embodiment and a layer formed from the prepreg according to the above embodiment. Such a printed wiring board can be manufactured according to a conventional method, and the manufacturing method is not particularly limited. Hereinafter, an example of a method for manufacturing a printed wiring board will be described. First, a metal foil-clad laminate such as the above-mentioned copper foil-clad laminate is prepared. Next, an etching treatment is performed on the surface of the metal foil-clad laminate to form an inner layer circuit, and an inner layer substrate is manufactured. If necessary, a surface treatment is performed on the inner layer circuit surface of this inner layer substrate to increase the adhesive strength, and then a required number of the above-mentioned prepregs are stacked on the surface of the inner layer circuit, and a metal foil for an outer layer circuit is further stacked on the outside thereof, and the laminate is heated and pressed to form an integral structure. In this way, a multi-layer laminate is manufactured in which an insulating layer made of a base material and a cured product of a thermosetting resin composition is formed between the inner layer circuit and the metal foil for the outer layer circuit. Next, this multi-layer laminate is subjected to drilling processing for through holes and via holes, and then a plated metal coating is formed on the wall surfaces of the holes to provide electrical continuity between the inner layer circuit and the metal foil for the outer layer circuit. Furthermore, the metal foil for the outer layer circuit is etched to form the outer layer circuit, thereby producing a printed wiring board.

The printed wiring board obtained in the above manufacturing example has an insulating layer and a conductor layer formed on the surface of the insulating layer, and the insulating layer contains the resin composition of the present embodiment described above. That is, the prepreg of the present embodiment described above (for example, a prepreg formed from a base material and the resin composition of the present embodiment impregnated or applied thereto), and the layer formed from the resin composition of the metal foil-clad laminate of the present embodiment described above are the insulating layer of the present embodiment.

<<Resin composite sheet>>
A resin composite sheet according to a preferred embodiment includes a support and a layer formed from the resin composition according to the present embodiment arranged on the surface of the support. The resin composite sheet can be used as a build-up film or a dry film solder resist. The method for producing the resin composite sheet is not particularly limited, but for example, a method for obtaining a resin composite sheet by applying (coating) a solution in which the resin composition according to the present embodiment is dissolved in a solvent to a support and drying the solution can be mentioned.

Examples of the support used here include, but are not limited to, polyethylene film, polypropylene film, polycarbonate film, polyethylene terephthalate film, ethylene tetrafluoroethylene copolymer film, as well as release films in which a release agent is applied to the surface of these films, organic film substrates such as polyimide film, conductive foils such as copper foil and aluminum foil, glass plates, SUS plates, FRP, and other plate-shaped substrates.

Examples of application methods (coating methods) include a method in which a solution in which the resin composition is dissolved in a solvent is applied onto a support using a bar coater, die coater, doctor blade, baker applicator, or the like. In addition, after drying, a single-layer sheet can be obtained by peeling or etching the support from a resin composite sheet in which the support and the resin composition are laminated. In addition, a single-layer sheet can also be obtained without using a support by supplying a solution in which the resin composition of the present embodiment is dissolved in a solvent into a mold having a sheet-shaped cavity and drying it to form it into a sheet.

In the preparation of the resin composite sheet of this embodiment, the drying conditions for removing the solvent are not particularly limited, but since low temperatures tend to leave the solvent in the resin composition, and high temperatures tend to cause the resin composition to harden, a temperature of 20°C to 200°C for 1 to 90 minutes is preferred. In addition, in the resin composite sheet, the resin composition can be used in an uncured state in which the solvent has simply been dried, or it can be used in a semi-cured (B-stage) state as necessary. Furthermore, the thickness of the resin layer of the resin composite sheet of this embodiment can be adjusted by the concentration of the solution of the resin composition of this embodiment and the coating thickness, and is not particularly limited, but 0.1 to 500 μm is preferred, since a thicker coating thickness generally tends to leave the solvent when drying.

The present invention will be described in more detail below with reference to examples. The materials, amounts, ratios, processing contents, processing procedures, etc. shown in the following examples can be appropriately changed without departing from the spirit of the present invention. Therefore, the scope of the present invention is not limited to the specific examples shown below.
In the present examples, measurements were carried out at 23° C. unless otherwise stated.

Example 1
75 parts by mass of a multifunctional vinylbenzene polymer (ap) synthesized as described below, 25 parts by mass of a biphenylaralkyl-type maleimide (MIR-3000 (trade name) manufactured by Nippon Kayaku Co., Ltd.) (a compound represented by formula (1)), and 0.5 parts by mass of an imidazole catalyst (2E4MZ (trade name) manufactured by Shikoku Kasei Co., Ltd.) were dissolved in methyl ethyl ketone and mixed to obtain a varnish.

(Synthesis of polyfunctional vinylbenzene polymer (ap))
2.25 mol (292.9 g) of divinylbenzene, 1.32 mol (172.0 g) of ethylvinylbenzene, 11.43 mol (1190.3 g) of styrene, and 15.0 mol (1532.0 g) of n-propyl acetate were charged into a reactor, and 600 mmol of a diethyl ether complex of boron trifluoride was added at 70 ° C. and reacted for 4 hours. After the polymerization solution was stopped with an aqueous sodium hydrogen carbonate solution, the oil layer was washed three times with pure water, and the mixture was devolatilized under reduced pressure at 60 ° C. to recover a polyfunctional vinylbenzene polymer (ap). The obtained polyfunctional vinylbenzene polymer (ap) was weighed, and it was confirmed that 860.8 g of a polyfunctional vinylbenzene polymer (ap) was obtained.

The obtained polyfunctional vinylbenzene polymer (ap) had an Mn of 2060, an Mw of 30700, and an Mw/Mn of 14.9. By performing ¹³ C-NMR and ¹ H-NMR analysis, resonance lines derived from each monomer unit were observed in the polyfunctional vinylbenzene polymer (ap). Based on the NMR measurement results and GC analysis results, the ratio of the structural units of the polyfunctional vinylbenzene polymer (ap) was calculated as follows.
Structural units derived from divinylbenzene: 20.9 mol% (24.3 mass%)
Structural units derived from ethylvinylbenzene: 9.1 mol% (10.7 mass%)
Structural units derived from styrene: 70.0 mol% (65.0 mass%)
The content of structural units having a residual vinyl group derived from divinylbenzene was 16.7 mol % (18.5 mass %).

<<Production of hardened plate test pieces with a thickness of 1.6 mm>>
The solvent was evaporated from the resulting varnish to obtain a mixed resin powder. The mixed resin powder was filled into a mold with a side length of 100 mm and a thickness of 1.6 mm, and 12 μm copper foil (3EC-M3-VLP, manufactured by Mitsui Mining & Smelting Co., Ltd.) was placed on both sides and vacuum pressed at a pressure of 30 kg/cm ² and a temperature of 220° C. for 120 minutes to obtain a cured plate with a side length of 100 mm and a thickness of 1.6 mm.

The physical properties of the resulting 1.6 mm thick cured plates (dielectric properties (Dk, Df), peel strength, glass transition temperature, and coefficient of thermal expansion (CTE)) were evaluated according to the methods described below.

Example 2
A varnish was obtained in the same manner as in Example 1, except that the amount of the polyfunctional vinylbenzene polymer (ap) synthesized above was changed to 50 parts by mass, and the amount of the biphenylaralkyl-type maleimide (MIR-3000) was changed to 50 parts by mass. A 1.6 mm thick cured plate was obtained from this varnish in the same manner as in Example 1. The physical properties and the like of the obtained 1.6 mm thick cured plate were evaluated according to the methods described below.

Example 3
A varnish was obtained in the same manner as in Example 1, except that the amount of the polyfunctional vinylbenzene polymer (ap) synthesized above was changed to 25 parts by mass and the amount of the biphenylaralkyl-type maleimide (MIR-3000) was changed to 75 parts by mass. A 1.6 mm thick cured plate was obtained from the obtained varnish in the same manner as in Example 1. The physical properties, etc. of the obtained 1.6 mm thick cured plate were evaluated according to the methods described below.

Example 4
A varnish was obtained in the same manner as in Example 1, except that the amount of the multifunctional vinylbenzene polymer (ap) synthesized above was changed to 50 parts by mass, and 25 parts by mass of phenyl ether type maleimide (BMI-80 (trade name) manufactured by K.I. Chemical Industry Co., Ltd.) (compound represented by formula (3)) was added in addition to 25 parts by mass of biphenylaralkyl type maleimide (MIR-3000). A 1.6 mm thick cured plate was obtained from the obtained varnish in the same manner as in Example 1. The physical properties, etc. of the obtained 1.6 mm thick cured plate were evaluated according to the methods described below.

Example 5
A varnish was obtained in the same manner as in Example 1, except that the amount of the multifunctional vinylbenzene polymer (ap) synthesized above was changed to 50 parts by mass, and 50 parts by mass of BisM type maleimide (BMI-BisM (trade name) manufactured by K.I. Chemical Industry Co., Ltd.) (compound represented by formula (4)) was used instead of 25 parts by mass of biphenylaralkyl type maleimide (MIR-3000). A 1.6 mm thick cured plate was obtained from the obtained varnish in the same manner as in Example 1. The physical properties, etc. of the obtained 1.6 mm thick cured plate were evaluated according to the method described below.

Example 6
A varnish was obtained in the same manner as in Example 1, except that the amount of the multifunctional vinylbenzene polymer (ap) synthesized above was changed to 50 parts by mass, and 50 parts by mass of phenylene type maleimide (BMI-70 (trade name) manufactured by K.I. Chemical Industry Co., Ltd.) (a compound corresponding to formula (2)) was used instead of 25 parts by mass of biphenylaralkyl type maleimide (MIR-3000). A test piece of a 1.6 mm thick cured plate was obtained from the obtained varnish in the same manner as in Example 1. The physical properties, etc. of the obtained 1.6 mm thick cured plate were evaluated according to the method described below.

<Reference Example 1>
A varnish was obtained in the same manner as in Example 1, except that the biphenylaralkyl-type maleimide (MIR-3000) and the imidazole catalyst (2E4MZ) were not used. A 1.6 mm thick cured plate was obtained from the obtained varnish in the same manner as in Example 1. The physical properties and the like of the obtained 1.6 mm thick cured plate were evaluated according to the methods described below.

<Reference Example 2>
A varnish was obtained in the same manner as in Example 1, except that the polyfunctional vinylbenzene polymer (ap) synthesized above was not used and the amount of biphenylaralkyl-type maleimide (MIR-3000) was 100 parts by mass. A 1.6 mm thick cured plate was obtained from the obtained varnish in the same manner as in Example 1. The physical properties and the like of the obtained 1.6 mm thick cured plate were evaluated according to the methods described below.

<Reference Example 3>
A varnish was obtained in the same manner as in Example 1, except that the polyfunctional vinylbenzene polymer (ap) synthesized above was not used, and 100 parts by mass of BisM type maleimide (BMI-BisM (trade name) manufactured by K.I. Chemical Industry Co., Ltd.) was used instead of 25 parts by mass of biphenylaralkyl type maleimide (MIR-3000). A 1.6 mm thick cured plate was obtained from the obtained varnish in the same manner as in Example 1. The physical properties, etc. of the obtained 1.6 mm thick cured plate were evaluated according to the methods described below.

<Reference Example 4>
A varnish was obtained in the same manner as in Example 1, except that the amount of the multifunctional vinylbenzene polymer (ap) synthesized above was 50 parts by mass, and 50 parts by mass of a novolak type maleimide (BMI-2300 (trade name) manufactured by Daiwa Kasei Co., Ltd.) (a maleimide compound not corresponding to formulas (1) to (4)) was used instead of 25 parts by mass of the biphenylaralkyl type maleimide (MIR-3000). From the obtained varnish, a 1.6 mm thick cured plate was obtained in the same manner as in Example 1. The obtained 1.6 mm thick cured plate was subjected to evaluation of physical properties, etc. according to the methods described below.

<Reference Example 5>
A varnish was obtained in the same manner as in Example 1, except that the amount of the polyfunctional vinylbenzene polymer (ap) synthesized above was 50 parts by mass, and 50 parts by mass of terminally modified polyphenylene ether (OPE-2St 1200 (product name) manufactured by Mitsubishi Gas Chemical Company, Inc.) was used instead of 25 parts by mass of biphenylaralkyl-type maleimide (MIR-3000). From the obtained varnish, a 1.6 mm thick cured plate was obtained in the same manner as in Example 1. The obtained 1.6 mm thick cured plate was subjected to evaluation of physical properties, etc. according to the methods described below.

<Reference Example 6>
A varnish was obtained in the same manner as in Example 1, except that the amount of the multifunctional vinylbenzene polymer (ap) synthesized above was 50 parts by mass, 36.5 parts by mass of a biphenylaralkyl type epoxy (manufactured by Nippon Kayaku Co., Ltd., NC3000FH (trade name)) and 13.5 parts by mass of a cresol novolak (manufactured by DIC Corporation, KA-1163 (trade name)) were used instead of 25 parts by mass of the biphenylaralkyl type maleimide (MIR-3000), and the amount of the imidazole catalyst was changed to 0.2 parts by mass. From the obtained varnish, a 1.6 mm thick cured plate was obtained in the same manner as in Example 1. The obtained 1.6 mm thick cured plate was evaluated for physical properties and the like according to the methods described below.

<Dielectric properties (Dk and Df)>
The copper foil of the obtained 1.6 mm thick cured plate was removed by etching to obtain a test piece, and the relative dielectric constant (Dk) and dielectric loss tangent (Df) at 10 GHz were measured using a perturbation method cavity resonator. The measurement temperature was 23°C.
The perturbation method cavity resonator used was Agilent 8722ES, a product of Agilent Technologies.
In Table 1 below, Dk (dielectric constant) is expressed as "S" when it is 2.5 or less, "A" when it is more than 2.5 and 2.6 or less, "B" when it is more than 2.6 and 2.7 or less, and "C" when it is more than 2.7. Regarding Df (dielectric loss tangent), "S" when it is 0.0015 or less, "A" when it is more than 0.0015 and 0.0020 or less, "B" when it is more than 0.0020 and 0.0040 or less, and "C" when it is more than 0.0040.

<Long-term heat resistance dielectric properties>
The copper foil of the obtained 1.6 mm thick cured plate was removed by etching to prepare a test specimen, which was then left at 125°C in an air atmosphere for 500 hours. Using the obtained test specimen, Dk and Df at 10 GHz after thermal degradation were measured using a perturbation method cavity resonator to determine the amount of change from Dk and Df before thermal degradation.
The perturbation method cavity resonator used was Agilent 8722ES, a product of Agilent Technologies.
In Table 1 below, the change in Dk after thermal degradation from Dk before thermal degradation was rated as "S" for 0.02 or less, "A" for more than 0.02 and 0.04 or less, "B" for more than 0.04 and 0.06 or less, and "C" for more than 0.06. In addition, the change in Df after thermal degradation from Df before thermal degradation was rated as "S" for 0.001 or less, "A" for more than 0.001 and 0.002 or less, "B" for more than 0.002 and 0.003 or less, and "C" for more than 0.003.

<Peel strength>
Using the cured plate obtained as described above, the copper foil peel strength (adhesive strength) was measured twice in accordance with the provision of JIS C6481, 5.7 "Peel strength", and the average value was calculated.
In Table 1 below, peel strength was rated as "S" for 0.8 kN/m or more, "A" for less than 0.8 kN/m and 0.6 kN/m or more, "B" for less than 0.6 kN/m and 0.5 kN/m or more, and "C" for less than 0.5 kN/m.

<Glass transition temperature>
The glass transition temperature (Tg) was measured for a test piece obtained by removing the copper foil of the 1.6 mm thick cured plate by etching in accordance with JIS C6481 5.17.2 using a dynamic viscoelasticity analyzer by a DMA (Dynamic Mechanical Analysis) bending method. The glass transition temperature was estimated from the obtained tan δ chart.
The dynamic viscoelasticity analyzer used was a device manufactured by TA Instruments.
In Table 1, the glass transition temperatures are categorized as "S" for 300° C. or higher, "A" for 220° C. or higher but lower than 300° C., "B" for 200° C. or higher but lower than 220° C., and "C" for less than 200° C.

<Coefficient of Thermal Expansion (CTE)>
(CTE: Coefficient of linear thermal expansion)
The thermal expansion coefficient of the hardened plate was measured by the TMA method (Thermo-Mechanical Analysis) specified in JIS C 6481 5.19 for a test piece in which the copper foil of the 1.6 mm thick hardened plate was removed by etching, and the value was obtained. Specifically, after the copper foil on both sides of the hardened plate obtained above was removed by etching, the temperature was raised from 40°C to 340°C at a rate of 10°C per minute using a thermomechanical analyzer (manufactured by TA Instruments), and the linear thermal expansion coefficient (ppm/°C) was measured. ppm is a volume ratio. Other details are in accordance with JIS C 6481 5.19.

（表の注記）
Ｄｋ：１０ＧＨｚにおける比誘電率
Ｄｆ：１０ＧＨｚにおける誘電正接
ピール強度：銅箔の剥離試験の結果
ガラス転移温度：ＤＭＡ法により測定されるｔａｎδから見積もられたガラス転移温度
ＣＴＥ：ＴＭＡ法により測定された熱膨張係数

(Table notes)
Dk: relative dielectric constant at 10 GHz Df: dielectric loss tangent at 10 GHz Peel strength: results of copper foil peel test Glass transition temperature: glass transition temperature estimated from tan δ measured by DMA method CTE: thermal expansion coefficient measured by TMA method

From the results in Table 1 above, in the resin composition in which the polyfunctional vinyl aromatic polymer (A) (polyfunctional vinylbenzene polymer (ap)) according to the present embodiment is combined with the maleimide compound (B) having a specific structure (a compound represented by formulas (1) to (4)), the film molded using this composition had excellent dielectric properties (low dielectric constant, low dielectric tangent), high peel strength, and excellent heat resistance (sufficiently high glass transition temperature), and further had excellent dielectric properties (amount of change) after long-term heating.
In contrast, Reference Example 1 is an example in which the specific maleimide compound (B) was not contained and only the polyfunctional vinyl aromatic polymer (A) was used. The dielectric properties and peel strength after long-term heating were inferior, and the glass transition temperature was also low.
Reference Examples 2 and 3 are examples not containing the polyfunctional vinyl aromatic polymer (A). Reference Example 2 was inferior in relative dielectric constant (Dk). Reference Example 3 was inferior in peel strength and glass transition temperature.
In Reference Example 4, a polyfunctional vinyl aromatic polymer (A) and a compound having a maleimide group are used. However, the compound having a maleimide group is a novolak-type maleimide (BMI-2300), which is not included in the compounds represented by the formulas (1) to (4). In Reference Example 4, the glass transition temperature was low and inferior.
In Reference Example 5, a polyfunctional vinyl aromatic polymer (A) was combined with a terminal-modified polyphenylene ether resin, and this resin composition showed poor dielectric properties after long-term heating.
Reference Example 6 uses a biphenyl aralkyl type epoxy and a cresol novolac resin in combination with a polyfunctional vinyl aromatic polymer (A). This resin composition has poor Df, Dk after long-term heating, peel strength, and a low glass transition temperature.
In addition, among the examples, it is seen that by changing the amounts and types of the polyfunctional vinyl aromatic polymer (A) and the maleimide compound (B), it is possible to obtain a particularly excellent dielectric constant (Example 1), and to obtain excellent dielectric properties, peel strength, and heat resistance (high glass transition temperature) after long-term heating (Examples 2 to 5, especially Examples 2 and 3).

Example 7
50 parts by mass of the polyfunctional vinylbenzene polymer (ap) synthesized above, 50 parts by mass of biphenylaralkyl-type maleimide (MIR-3000 (trade name), manufactured by Nippon Kayaku Co., Ltd.), 0.5 parts by mass of imidazole catalyst (2E4MZ (trade name), manufactured by Shikoku Kasei Co., Ltd.), and 50 parts by mass of slurry silica (spherical silica) (SC2050-MNU (trade name), manufactured by Admatechs Co., Ltd.) were dissolved in methyl ethyl ketone and mixed to obtain a varnish.

The varnish obtained was applied to a low dielectric glass cloth having a thickness of 0.069 mm by impregnation, and the cloth was dried by heating at 150°C for 3 minutes using a dryer (an explosion-proof steam dryer manufactured by Takasugi Seisakusho Co., Ltd.) to obtain a prepreg having a resin composition adhesion amount of 60 mass% relative to the substrate. A 12 μm copper foil (3EC-M3-VLP manufactured by Mitsui Mining & Smelting Co., Ltd.) was placed on both sides of one of the prepregs, and vacuum pressed at a pressure of 30 kg/ ^cm2 and a temperature of 220°C for 120 minutes to obtain a copper foil-clad laminate having a thickness of 0.1 mm.
Four sheets of the prepreg were stacked, and 12 μm copper foil was placed on both sides. The laminate was vacuum pressed at a pressure of 30 kg/cm ² and a temperature of 220° C. for 120 minutes to obtain a copper foil-clad laminate having a thickness of 0.4 mm.

The obtained copper foil-clad laminates having a thickness of 0.1 mm and 0.4 mm were evaluated for physical properties (dielectric properties (Dk, Df), dielectric properties after long-term heating, peel strength, glass transition temperature) according to the above-mentioned methods. However, the cured sheets were copper foil-clad laminates, and the sheet thicknesses were changed from 1.6 mm to 0.1 mm and 0.4 mm. For the copper foil-clad laminates, the copper foil was removed by etching in the measurement of the dielectric properties and glass transition temperature.
The coefficient of thermal expansion (CTE) was measured in the warp direction of the glass cloth. In addition, the moisture absorption and heat resistance (swelling) was measured, which will be described later.

<Reference Example 7>
A varnish was prepared in the same manner as in Example 7, except that the polyfunctional vinylbenzene polymer (ap) synthesized above was used as 100 parts by mass, and that the biphenylaralkyl-type maleimide (MIR-3000) and the imidazole catalyst (2E4MZ) were not used, and a copper foil-clad laminate was obtained. The evaluation results of each item of the obtained copper foil-clad laminate are shown in Table 2.

<Reference Example 8>
A varnish was prepared in the same manner as in Example 7, except that the polyfunctional vinylbenzene polymer (ap) synthesized above was not used and the amount of biphenylaralkyl-type maleimide (MIR-3000) was 100 parts by mass, and a copper foil-clad laminate was obtained. The evaluation results of each item of the obtained copper foil-clad laminate are shown in Table 2.

<Moisture absorption and heat resistance>
A copper foil-clad laminate was cut to a size of 50 mm x 50 mm x 0.4 mm thick insulating layer, and all of the copper foil except for half of one side was removed by etching to obtain a test piece. The obtained test piece was treated in a pressure cooker tester (Hirayama Seisakusho, PC-3 model) at 121°C and 2 atm for 5 hours in accordance with JIS C648, and then immersed in solder at 260°C for 30 seconds. The presence or absence of swelling after immersion was visually observed, and the moisture absorption and heat resistance was evaluated according to the following evaluation criteria.
<<Whether or not there is swelling>>
A: No abnormality B: Blistering

（表の注釈）
Ｄｋ：１０ＧＨｚにおける比誘電率
Ｄｆ：１０ＧＨｚにおける誘電正接
ピール強度：銅箔の剥離試験の結果
ガラス転移温度：ＤＭＡ法により測定されるｔａｎδから見積もられたガラス転移温度
ＣＴＥ：ＴＭＡ法により測定された熱膨張係数

(Table notes)
Dk: relative dielectric constant at 10 GHz Df: dielectric loss tangent at 10 GHz Peel strength: results of copper foil peel test Glass transition temperature: glass transition temperature estimated from tan δ measured by DMA method CTE: thermal expansion coefficient measured by TMA method

From the results in Table 2 above, it was confirmed that when a copper foil-clad laminate was produced using the resin composition according to this embodiment as a filler (spherical silica), it exhibited extremely high heat resistance (high glass transition temperature). In addition, the moisture absorption and heat resistance also showed good results.
In contrast, in Reference Example 7, which did not contain the specific maleimide compound (B), the moisture absorption and heat resistance was poor, and swelling occurred.
Moreover, in Reference Example 8, which did not contain the polyfunctional vinyl aromatic polymer (A), Dk was high.

Claims (9)

The present invention comprises a polyfunctional vinyl aromatic polymer (A) and a maleimide compound (B), and the maleimide compound (B) contains at least one compound represented by any one of the following formulas (1) to (4):
The polyfunctional vinyl aromatic polymer (A) is a polymer having a structural unit represented by formula (V) and is a thermosetting resin (excluding resin compositions containing a compound represented by formula (5) and/or a compound represented by formula (6) below, and excluding resin compositions containing 3,3'-dimethyl-5,5'-diethyl-4,4'-diphenylmethane bismaleimide) .

(In formula (1), R ¹ , R ² , R ³ and R ⁴ each independently represent a hydrogen atom, an alkyl group having 1 to 8 carbon atoms or a phenyl group, and n1 represents a number of 1 or more and 10 or less.)

(In formula (2), each R ⁶ independently represents a methyl group or an ethyl group, and each R ⁷ independently represents a hydrogen atom or a methyl group.)

(In formula (3), each ^R8 independently represents a hydrogen atom, a methyl group, or an ethyl group.)

(In formula (4), each R ⁹ independently represents a hydrogen atom, a methyl group, or an ethyl group.)

(In formula (V), Ar represents an aromatic hydrocarbon linking group. * represents a bonding position.)

The resin composition according to claim 1, wherein the content of the maleimide compound (B) is 5 to 95 parts by mass per 100 parts by mass of the total amount of the resin components in the resin composition. The resin composition according to claim 1 or 2, wherein the content of the polyfunctional vinyl aromatic polymer (A) is 5 to 95 parts by mass per 100 parts by mass of the total amount of the resin components in the resin composition. The resin composition according to any one of claims 1 to 3, further comprising a filler (C). The resin composition according to claim 4, wherein the content of the filler (C) is 10 to 500 parts by mass per 100 parts by mass of the total amount of the resin components in the resin composition. A prepreg formed from a substrate and the resin composition according to any one of claims 1 to 5. A metal foil-clad laminate comprising at least one layer formed from the prepreg according to claim 6 and metal foil disposed on one or both sides of the layer formed from the prepreg. A resin composite sheet comprising a support and a layer formed from the resin composition according to any one of claims 1 to 5, which is disposed on the surface of the support. A printed wiring board including an insulating layer and a conductor layer disposed on the surface of the insulating layer, the insulating layer including at least one of a layer formed from the resin composition according to any one of claims 1 to 5 and a layer formed from the prepreg according to claim 6.