JP7501368B2 - Resin composition, prepreg, laminate, resin film, multilayer printed wiring board, and multilayer printed wiring board for millimeter wave radar - Google Patents

Description

The present invention relates to a resin composition, a prepreg, a laminate, a resin film, a multilayer printed wiring board, and a multilayer printed wiring board for millimeter wave radar.

In mobile communication devices such as mobile phones, their base station equipment, network infrastructure devices such as servers and routers, and large computers, the speed and capacity of the signals used are increasing year by year. Accordingly, the printed wiring boards mounted on these electronic devices need to be compatible with higher frequencies, and there is a demand for board materials with excellent dielectric properties (low dielectric constant and low dielectric tangent; hereinafter sometimes referred to as high frequency properties) in the high frequency band that enable reduction in transmission loss. In recent years, in addition to the electronic devices mentioned above, new systems that handle high frequency wireless signals have been put into practical use or are planned to be put into practical use in the ITS field (related to automobiles and transportation systems) and in the field of indoor short-range communication as applications that handle such high frequency signals, and it is expected that in the future, there will be an even greater demand for low transmission loss board materials for the printed wiring boards mounted on these devices.

Conventionally, polyphenylene ether (PPE) resins have been used as heat-resistant thermoplastic polymers with excellent high-frequency characteristics in printed wiring boards that require low transmission loss. For example, a method of using polyphenylene ether and a thermosetting resin in combination has been proposed. Specifically, a resin composition containing polyphenylene ether and an epoxy resin (see, for example, Patent Document 1), a resin composition containing polyphenylene ether and a cyanate resin with a low dielectric constant among thermosetting resins (see, for example, Patent Document 2), and the like have been disclosed.
However, the resin compositions described in Patent Documents 1 and 2 are generally insufficient in terms of high-frequency characteristics in the GHz range, adhesion to conductors, low thermal expansion coefficient, and flame retardancy, and the heat resistance is sometimes reduced due to low compatibility between polyphenylene ether and thermosetting resins.

（式中、Ｒ^１は各々独立に、炭素数１～５の脂肪族炭化水素基又はハロゲン原子である。ｘは０～４の整数である。） Under these circumstances, with an objective of providing a resin composition that has particularly good compatibility and dielectric properties in the high frequency band, high adhesion to conductors, excellent heat resistance, a high glass transition temperature, a low thermal expansion coefficient, and high flame retardancy, a resin composition has been proposed that contains a polyphenylene ether derivative (A) having an N-substituted maleimide structure-containing group and a structural unit represented by the following general formula in one molecule, one or more thermosetting resins (B) selected from the group consisting of epoxy resins, cyanate resins, and maleimide compounds, and a styrene-based thermoplastic elastomer (C) (see, for example, Patent Document 3):

(In the formula, each R ¹ is independently an aliphatic hydrocarbon group having 1 to 5 carbon atoms or a halogen atom; and x is an integer of 0 to 4.)

Japanese Patent Application Laid-Open No. 58-069046 Japanese Patent Publication No. 61-018937 International Publication No. 2016/175326

The resin composition described in Patent Document 3 certainly has excellent dielectric properties in the high frequency band, but there is room for further improvement in terms of heat resistance. Furthermore, in recent years, there has been a strong demand for the development of a resin composition with improved dielectric properties in the 10 GHz band or higher that can be used in fifth-generation mobile communication system (5G) antennas that use radio waves in the frequency band above 6 GHz and millimeter-wave radars that use radio waves in the frequency band from 30 to 300 GHz.

In view of the current situation, the present invention aims to provide a resin composition that has excellent heat resistance and can exhibit excellent dielectric properties in high frequency bands of 10 GHz or more, and a prepreg, laminate, resin film, multilayer printed wiring board, and multilayer printed wiring board for millimeter wave radar that use the resin composition.

Means for Solving the Problems The present inventors have conducted intensive research to solve the above problems, and as a result have found that a resin composition containing a polyphenylene ether derivative having a specific molecular structure, one or more compounds selected from the group consisting of specific maleimide compounds and their derivatives, and a specific crosslinking agent has excellent heat resistance and exhibits excellent dielectric properties in a high frequency band of 10 GHz or more, and have thus completed the present invention.
That is, the present invention relates to the following [1] to [15].

（式中、Ｒ^ａ１は炭素数２～１０のエチレン性不飽和結合含有基である。ｎ１は１又は２であり、ｎ２は０又は１である。＊は、他の構造への結合位置を示す。）
［８］前記（Ａ）成分が、記一般式（ａ１－２）で表される構造を含む、上記［１］～［７］のいずれかに記載の樹脂組成物。

（式中、Ｒ^ａ２及びＲ^ａ３は、各々独立に、炭素数２～１０のエチレン性不飽和結合含有基である。＊は、他の構造への結合位置を示す。）
［９］前記（Ａ）成分において、エチレン性不飽和結合含有基の数が、２個以上である、上記［１］～［８］のいずれかに記載の樹脂組成物。
［１０］前記（Ｂ）成分が、Ｎ－置換マレイミド基を２個以上有するマレイミド化合物（ｂ１）由来の構造単位とジアミン化合物（ｂ２）由来の構造単位とを有する、上記［１］～［９］のいずれかに記載の樹脂組成物。
［１１］上記［１］～［１０］のいずれかに記載の樹脂組成物を含有してなるプリプレグ。
［１２］上記［１１］に記載のプリプレグと金属箔とを含有してなる積層板。
［１３］上記［１］～［１０］のいずれかに記載の樹脂組成物を含有してなる樹脂フィルム。
［１４］上記［１１］に記載のプリプレグ、上記［１２］に記載の積層板及び上記［１３］に記載の樹脂フィルムからなる群から選択される１種以上を含有してなる多層プリント配線板。
［１５］上記［１１］に記載のプリプレグ、上記［１２］に記載の積層板及び上記［１３］に記載の樹脂フィルムからなる群から選択される１種以上を含有してなるミリ波レーダー用多層プリント配線板。 [1] (A) a polyphenylene ether derivative having an ethylenically unsaturated bond-containing group,
(B) one or more compounds selected from the group consisting of maleimide compounds having two or more N-substituted maleimide groups and derivatives thereof;
(C) a crosslinking agent having two or more ethylenically unsaturated bonds;
A resin composition comprising:
[2] The resin composition according to the above [1], wherein the component (C) has the two or more ethylenically unsaturated bonds as vinyl groups.
[3] The resin composition according to the above [2], wherein the component (C) is a polybutadiene having the two or more ethylenically unsaturated bonds as 1,2-vinyl groups.
[4] The resin composition according to the above [3], wherein the content of structural units having a 1,2-vinyl structure is 50 mol% or more relative to all structural units derived from butadiene constituting the polybutadiene.
[5] The resin composition according to the above [3] or [4], wherein the number average molecular weight of the polybutadiene is 500 to 10,000.
[6] The resin composition according to any one of [1] to [5] above, wherein the content of the (C) component is 5 to 60 parts by mass per 100 parts by mass of the total of the resin components in the resin composition.
[7] The resin composition according to any one of [1] to [6] above, wherein the component (A) includes a structure represented by the following general formula (a1-1):

(In the formula, R ^a1 is an ethylenically unsaturated bond-containing group having 2 to 10 carbon atoms. n1 is 1 or 2, and n2 is 0 or 1. * indicates the bonding position to other structures.)
[8] The resin composition according to any one of the above [1] to [7], wherein the component (A) includes a structure represented by the following general formula (a1-2):

(In the formula, R ^a2 and R ^a3 each independently represent an ethylenically unsaturated bond-containing group having 2 to 10 carbon atoms. * indicates the bonding position to other structures.)
[9] The resin composition according to any one of the above [1] to [8], wherein the number of ethylenically unsaturated bond-containing groups in the component (A) is 2 or more.
[10] The resin composition according to any one of the above [1] to [9], wherein the component (B) has a structural unit derived from a maleimide compound (b1) having two or more N-substituted maleimide groups and a structural unit derived from a diamine compound (b2).
[11] A prepreg comprising the resin composition according to any one of [1] to [10] above.
[12] A laminate comprising the prepreg according to [11] above and a metal foil.
[13] A resin film comprising the resin composition according to any one of [1] to [10] above.
[14] A multilayer printed wiring board comprising one or more members selected from the group consisting of the prepreg according to [11] above, the laminate according to [12] above, and the resin film according to [13] above.
[15] A multilayer printed wiring board for millimeter wave radar comprising one or more selected from the group consisting of the prepreg according to [11] above, the laminate according to [12] above, and the resin film according to [13] above.

According to the present invention, it is possible to provide a resin composition that has excellent heat resistance and can exhibit excellent dielectric properties (low dielectric constant and low dielectric tangent) in high frequency bands of 10 GHz or more, and a prepreg, a resin film, a laminate, a multilayer printed wiring board, and a multilayer printed wiring board for millimeter wave radar that use the resin composition.

In the numerical ranges described in this specification, the upper or lower limit of the numerical range may be replaced with the values shown in the examples. In addition, the lower and upper limits of the numerical ranges may be arbitrarily combined with the lower or upper limit of other numerical ranges.
In addition, unless otherwise specified, each of the components and materials exemplified in this specification may be used alone or in combination of two or more. In this specification, the content of each component in the composition means the total amount of the multiple substances present in the composition when multiple substances corresponding to each component are present in the composition, unless otherwise specified.
The present invention also includes any combination of the features described in this specification.

[Resin composition]
The resin composition of the present embodiment is
(A) a polyphenylene ether derivative having an ethylenically unsaturated bond-containing group (hereinafter, sometimes simply referred to as polyphenylene ether derivative (A) or component (A)),
(B) one or more compounds selected from the group consisting of maleimide compounds having two or more N-substituted maleimide groups and derivatives thereof (hereinafter, sometimes simply referred to as maleimide compound (B) or component (B));
(C) a crosslinking agent having two or more ethylenically unsaturated bonds (hereinafter, sometimes simply referred to as crosslinking agent (C) or component (C));
The resin composition comprises:
Each component will be described in detail below.

<Polyphenylene ether derivative (A)>
The polyphenylene ether derivative (A) has an ethylenically unsaturated bond-containing group.
In this specification, the term "ethylenically unsaturated bond-containing group" refers to a substituent containing a carbon-carbon double bond capable of undergoing an addition reaction, and does not include a double bond in an aromatic ring.

The position of the ethylenically unsaturated bond-containing group is not particularly limited, and for example, it may be present at one end of the (A) component, or may be present at both ends. The (A) component may be a mixture of a polyphenylene ether derivative having an ethylenically unsaturated bond-containing group at one end and a polyphenylene ether derivative having an ethylenically unsaturated bond-containing group at both ends, but it is preferable to contain at least a polyphenylene ether derivative having an ethylenically unsaturated bond-containing group at one end, and it is more preferable to be a polyphenylene ether derivative having an ethylenically unsaturated bond-containing group at one end itself.
When the component (A) contains a polyphenylene ether derivative having an ethylenically unsaturated bond-containing group at one end, the content of the polyphenylene ether derivative having an ethylenically unsaturated bond-containing group at one end in the component (A) may be 30% by mass or more, 45% by mass or more, 55% by mass or more, 70% by mass or more, 90% by mass or more, or may be substantially 100% by mass.

Examples of the ethylenically unsaturated bond-containing group contained in component (A) include unsaturated aliphatic hydrocarbon groups such as vinyl groups, isopropenyl groups, allyl groups, 1-methylallyl groups, and 3-butenyl groups; and heteroatom-containing substituents such as maleimide groups and (meth)acryloyl groups. Among these, from the viewpoint of dielectric properties in high frequency bands of 10 GHz or more, unsaturated aliphatic hydrocarbon groups or maleimide groups are preferred, allyl groups or maleimide groups are more preferred, and allyl groups are even more preferred.
In this specification, groups which contain an unsaturated aliphatic hydrocarbon group in part but cannot be considered an unsaturated aliphatic hydrocarbon group when viewed as a whole, such as a maleimide group, a (meth)acryloyl group, etc., are not included in the above-mentioned "unsaturated aliphatic hydrocarbon group".

Next, a polyphenylene ether derivative having an unsaturated aliphatic hydrocarbon group as an ethylenically unsaturated bond-containing group [hereinafter, sometimes simply referred to as polyphenylene ether derivative (A1) or (A1) component] and a polyphenylene ether derivative having a maleimide group as an ethylenically unsaturated bond-containing group [hereinafter, sometimes simply referred to as polyphenylene ether derivative (A2) or (A2) component] will be described in more detail.

(Polyphenylene Ether Derivative (A1))
The component (A1) is a polyphenylene ether derivative having an unsaturated aliphatic hydrocarbon group as an ethylenically unsaturated bond-containing group.
From the viewpoint of dielectric properties in a high frequency band of 10 GHz or more, the number of unsaturated aliphatic hydrocarbon groups that component (A1) has in one molecule is preferably 2 or more, more preferably 4 or more, and there is no particular upper limit, and it may be 8 or less, or 6 or less. Furthermore, from the viewpoint of dielectric properties in a high frequency band of 10 GHz or more, the number of unsaturated aliphatic hydrocarbon groups that component (A1) has at one end is preferably 2 or more, more preferably 4 or more, and there is no particular upper limit, and it may be 8 or less, or 6 or less.
It is most preferable that the number of unsaturated aliphatic hydrocarbon groups contained in the component (A1) and the number of unsaturated aliphatic hydrocarbon groups contained at one terminal of the component (A1) are both four.

（式（ａ１－１）中、Ｒ^ａ１は、各々独立に、炭素数２～１０の不飽和脂肪族炭化水素基である。ｎ１は１又は２であり、ｎ２は０又は１である。＊は、他の構造への結合位置を示す。） From the viewpoint of dielectric properties in the high frequency band of 10 GHz or more, the component (A1) preferably contains a structure represented by the following general formula (a1-1):

(In formula (a1-1), each R ^a1 is independently an unsaturated aliphatic hydrocarbon group having 2 to 10 carbon atoms. n1 is 1 or 2, and n2 is 0 or 1. * indicates the bonding position to another structure.)

In the above general formula (a1-1), examples of the unsaturated aliphatic hydrocarbon group having 2 to 10 carbon atoms represented by R ^a1 include a vinyl group, an isopropenyl group, an allyl group, a 1-methylallyl group, a 3-butenyl group, etc. Among these, from the viewpoint of dielectric properties in a high frequency band of 10 GHz or more, an unsaturated aliphatic hydrocarbon group having 2 to 5 carbon atoms is preferable, and an allyl group is more preferable.

（式（ａ１－２）中、Ｒ^ａ２及びＲ^ａ３は、各々独立に、炭素数２～１０の不飽和脂肪族炭化水素基である。＊は、他の構造への結合位置を示す。） From the viewpoint of dielectric properties in the high frequency band of 10 GHz or more, the component (A1) also preferably has an embodiment including a structure represented by the following general formula (a1-2):

(In formula (a1-2), R ^a2 and R ^a3 each independently represent an unsaturated aliphatic hydrocarbon group having 2 to 10 carbon atoms. * indicates the bonding position to other structures.)

In the above general formula (a1-2), the unsaturated aliphatic hydrocarbon group having 2 to 10 carbon atoms represented by R ^a2 and R ^a3 may be the same as R ^a1 in the above general formula (a1-1), and is preferably the same.

From the viewpoint of dielectric properties in the high frequency band of 10 GHz or more, it is more preferable that the (A1) component contains a structure represented by any one of the following general formulas (a1-3) to (a1-5), and it is even more preferable that the (A1) component contains a structure represented by the following general formula (a1-5).

（式（ａ１－３）中、Ｒ^ａ４は炭素数２～１０の不飽和脂肪族炭化水素基である。＊は、他の構造への結合位置を示す。）

(In formula (a1-3), R ^a4 is an unsaturated aliphatic hydrocarbon group having 2 to 10 carbon atoms. * indicates the bonding position to other structures.)

（式（ａ１－４）中、Ｒ^ａ５及びＲ^ａ６は、各々独立に、炭素数２～１０の不飽和脂肪族炭化水素基である。Ｘ^ａ１は、炭素数１～６の２価の脂肪族炭化水素基である。＊は、他の構造への結合位置を示す。）

(In formula (a1-4), R ^a5 and R ^a6 each independently represent an unsaturated aliphatic hydrocarbon group having 2 to 10 carbon atoms. X ^a1 represents a divalent aliphatic hydrocarbon group having 1 to 6 carbon atoms. * indicates the bonding position to other structures.)

（式（ａ１－５）中、Ｒ^ａ７～Ｒ^ａ１０は、各々独立に、炭素数２～１０の不飽和脂肪族炭化水素基である。Ｘ^ａ２は２価の有機基である。＊は、他の構造への結合位置を示す。）

(In formula (a1-5), R ^a7 to R ^a10 each independently represent an unsaturated aliphatic hydrocarbon group having 2 to 10 carbon atoms. X ^a2 represents a divalent organic group. * indicates the bonding position to other structures.)

Examples of the unsaturated aliphatic hydrocarbon group having 2 to 10 carbon atoms represented by R ^a4 to R ^a10 in the above general formulas (a1-3) to (a1-5) include the same as those in the case of R ^a1 in the general formula (a1-1), and the preferred ones are also the same.
Examples of the divalent aliphatic hydrocarbon group having 1 to 6 carbon atoms represented by X ^a1 in general formula (a1-4) above include alkylene groups having 1 to 6 carbon atoms, such as a methylene group, an ethylene group, and a trimethylene group, and alkylidene groups having 2 to 6 carbon atoms, such as an isopropylidene group. Among these, a methylene group and an isopropylidene group are preferred, and an isopropylidene group is more preferred.
The divalent organic group represented by X ^a2 in the above general formula (a1-5) includes an aliphatic hydrocarbon group which may contain a heteroatom in part, an alicyclic hydrocarbon group which may contain a heteroatom in part, an aromatic hydrocarbon group which may contain a heteroatom in part, and a group consisting of any combination thereof. Examples of the heteroatom include an oxygen atom, a nitrogen atom, and a sulfur atom. The divalent organic group represented by X ^a2 is preferably a group that does not contain a heteroatom, more preferably an aliphatic hydrocarbon group that does not contain a heteroatom, or an alicyclic hydrocarbon group that does not contain a heteroatom, and even more preferably a group consisting of a combination of an aliphatic hydrocarbon group that does not contain a heteroatom and an alicyclic hydrocarbon group that does not contain a heteroatom.

（式中、Ｘ^ａ２は上記一般式（ａ１－５）中のＸ^ａ２と同じである。＊は、他の構造への結合位置を示す。） More preferred embodiments of the structures represented by the above general formula (a1-3), (a1-4) or (a1-5) are structures represented by the following formulas (a1-3'), (a1-4') or (a1-5'), respectively, from the viewpoint of dielectric properties in a high frequency band of 10 GHz or more. Among these, from the viewpoint of dielectric properties in a high frequency band of 10 GHz or more, the structures represented by the following formulas (a1-4') or (a1-5') are more preferred, and the structure represented by the following formula (a1-5') is even more preferred.

(In the formula, X ^a2 is the same as X ^a2 in the above general formula (a1-5). * indicates the bonding position to other structures.)

（式中、Ｒ^ａ１１は、各々独立に、炭素数１～５の脂肪族炭化水素基又はハロゲン原子である。ｎ３は０～４の整数である。） Since the component (A1) is a polyphenylene ether derivative, it naturally also has a phenylene ether bond, and it preferably has a structural unit represented by the following general formula (a-1).

(In the formula, each R ^a11 is independently an aliphatic hydrocarbon group having 1 to 5 carbon atoms or a halogen atom; and n3 is an integer of 0 to 4.)

Each R ^a11 in the above general formula (a-1) is independently an aliphatic hydrocarbon group having 1 to 5 carbon atoms or a halogen atom. Examples of the aliphatic hydrocarbon group include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a t-butyl group, and an n-pentyl group. The aliphatic hydrocarbon group is preferably an aliphatic hydrocarbon group having 1 to 3 carbon atoms, and more preferably a methyl group. Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.
Among the above, R ^a11 is preferably an aliphatic hydrocarbon group having 1 to 5 carbon atoms.
n3 is an integer of 0 to 4, and may be an integer of 1 or 2, or may be 2. When n3 is 1 or 2, R ^a11 may be substituted at the ortho position on the benzene ring (based on the substitution position of the oxygen atom). When n3 is 2 or more, multiple R ^a11 may be the same or different.
The structural unit represented by the above general formula (a-1) may specifically be a structural unit represented by the following general formula (a-1').

（式中、Ｘ^ａ２は上記一般式（ａ１－５）中のＸ^ａ２と同じである。ｎ４～ｎ６は、各々独立に、１～２００の整数である。） The component (A1) may contain a polyphenylene ether derivative represented by any one of the following general formulas (a1-6) to (a1-8), and particularly preferably contains a polyphenylene ether derivative represented by the following general formula (a1-7) or (a1-8), and more preferably contains a polyphenylene ether derivative represented by the following general formula (a1-8).

(In the formula, X ^a2 is the same as X ^a2 in the above general formula (a1-5). Each of n4 to n6 is independently an integer of 1 to 200.)

In the above general formulas (a1-6) to (a1-8), n4 to n6 are each independently an integer of 1 to 200, and from the viewpoint of dielectric properties in a high frequency band of 10 GHz or more and from the viewpoint of compatibility with the resin composition, may be an integer of 1 or more, may be an integer of 10 or more, may be an integer of 20 or more, or may be an integer of 25 or more. From the same viewpoint, n4 to n6 may each independently be an integer of 150 or less, may be an integer of 120 or less, or may be an integer of 100 or less.
In any of the above general formulae (a1-6) to (a1-8), the polyphenylene ether derivatives having different values of n4 to n6 may be a mixture, and usually tend to be a mixture.

[Number average molecular weight (Mn) of component (A1)]
The number average molecular weight of the polyphenylene ether derivative (A1) is preferably 1,000 to 25,000. When the number average molecular weight of the polyphenylene ether derivative (A1) is 1,000 or more, the dielectric properties in the high frequency band of 10 GHz or more tend to be further improved, and when it is 25,000 or less, the compatibility with the resin composition tends to be good and separation tends to be difficult even when left for a long period of time. From the same viewpoint, the number average molecular weight of the polyphenylene ether derivative (A1) is more preferably 2,000 to 20,000, further preferably 3,000 to 10,000, and particularly preferably 4,000 to 6,000.
In this specification, the number average molecular weight is a value calculated from a calibration curve using standard polystyrene by gel permeation chromatography (GPC), and more specifically, a value determined by the measurement method described in the Examples.

[Method for producing component (A1)]
One embodiment of a method for producing the component (A1) will be described below, but the method is not limited to the following description.
For example, a phenol compound containing a structure represented by any one of the above general formulae (a1-1) to (a1-5) [hereinafter may be abbreviated as unsaturated aliphatic hydrocarbon group-containing phenol compound (1)] and a polyphenylene ether having a number average molecular weight of 3,000 to 30,000 [hereinafter may be abbreviated as raw material polyphenylene ether] are subjected to a redistribution reaction in an organic solvent, thereby producing a polyphenylene ether derivative (A1) while decreasing the molecular weight of the polyphenylene ether.

The above redistribution reaction is, for example, a reaction in which an unsaturated aliphatic hydrocarbon group-containing phenolic compound (1) is mixed with raw material polyphenylene ether that has already been produced by polymerization, and a reaction catalyst described below is added as necessary, so that an oxy radical of the unsaturated aliphatic hydrocarbon group-containing phenolic compound (1) attacks a carbon atom in the raw material polyphenylene ether to which an oxygen atom is bonded, breaking the O-C bond there and lowering the molecular weight. At that time, the oxy radical of the unsaturated aliphatic hydrocarbon group-containing phenolic compound (1) that attacked bonds with the carbon atom whose bond has been broken, and is incorporated into the polyphenylene ether structure. Known methods can be used and applied for the redistribution reaction.

The molecular weight of the polyphenylene ether derivative (A1) can be controlled by the amount of the unsaturated aliphatic hydrocarbon group-containing phenol compound (1) used, and the more the amount of the unsaturated aliphatic hydrocarbon group-containing phenol compound (1) used, the lower the molecular weight of the (A1) component. In other words, the amount of the unsaturated aliphatic hydrocarbon group-containing phenol compound (1) used may be appropriately adjusted so that the number average molecular weight of the finally produced (A1) component falls within a suitable range.
The amount of the unsaturated aliphatic hydrocarbon group-containing phenol compound (1) used is not particularly limited, but for example, when the number average molecular weight of the starting polyphenylene ether to be reacted with the unsaturated aliphatic hydrocarbon group-containing phenol compound (1) is 3,000 to 30,000, the unsaturated aliphatic hydrocarbon group-containing phenol compound (1) is used in an amount such that the number of hydroxyl groups per mole of the starting polyphenylene ether is 1 to 10 moles, preferably 2 to 6 moles, to obtain the (A1) component having a number average molecular weight within the above-mentioned preferred range.

The organic solvent used in the production process of the polyphenylene ether derivative (A1) is not particularly limited, but examples thereof include alcohols such as methanol, ethanol, butanol, butyl cellosolve, ethylene glycol monomethyl ether, and propylene glycol monomethyl ether; ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone; aromatic hydrocarbons such as toluene, xylene, and mesitylene; esters such as methoxyethyl acetate, ethoxyethyl acetate, butoxyethyl acetate, and ethyl acetate; and nitrogen-containing compounds such as N,N-dimethylformamide, N,N-dimethylacetamide, and N-methyl-2-pyrrolidone. These may be used alone or in combination of two or more.

In addition, in the production process of the polyphenylene ether derivative (A1), as described above, a reaction catalyst can be used as necessary. For example, from the viewpoint of obtaining the (A1) component with a stable number average molecular weight with good reproducibility, it is preferable to use an organic peroxide such as t-butylperoxyisopropyl monocarbonate in combination with a metal carboxylate such as manganese naphthenate or manganese octylate. In addition, there is no particular limit to the amount of the reaction catalyst used. From the viewpoint of the reaction rate and gelation suppression when producing the (A1) component, for example, the organic peroxide may be 0.5 to 5 parts by mass and the metal carboxylate may be 0.05 to 0.5 parts by mass per 100 parts by mass of the raw material polyphenylene ether to be reacted with the unsaturated aliphatic hydrocarbon group-containing phenol compound (1).

The above-mentioned unsaturated aliphatic hydrocarbon group-containing phenol compound (1), the above-mentioned starting material polyphenylene ether having a number average molecular weight of 3,000 to 30,000, an organic solvent and, if necessary, a reaction catalyst are charged in predetermined amounts into a reactor, and the mixture is reacted while being heated, kept warm and stirred, to obtain the polyphenylene ether derivative (A1).
The reaction temperature and reaction time in this step can be appropriately adjusted using reaction conditions for a known redistribution reaction; however, from the viewpoints of workability and suppression of gelation, and from the viewpoint of obtaining the component (A1) having the desired number average molecular weight, the reaction temperature may be set to 70 to 110° C., and the reaction time to 1 to 8 hours, for example.

The solids concentration during the reaction in the manufacturing process of component (A1) [hereinafter also referred to as the reaction concentration] is not particularly limited, but may be, for example, 10 to 60% by mass, or 20 to 50% by mass. If the reaction concentration is 10% by mass or more, the reaction rate does not become too slow and tends to be more advantageous in terms of manufacturing costs, and if it is 60% by mass or less, better solubility tends to be obtained, and further, the solution viscosity is low, stirring efficiency is good, and gelation tends to be less likely.

The solution of polyphenylene ether derivative (A1) produced in the manner described above may be concentrated to remove some of the organic solvent, or may be diluted by adding additional organic solvent, if necessary.

The resin composition of this embodiment tends to have better dielectric properties in the high frequency band of 10 GHz or higher than a resin composition containing the above raw material polyphenylene ether instead of component (A1).

(Polyphenylene ether derivative (A2))
The component (A2) is a polyphenylene ether derivative having a maleimide group as an ethylenically unsaturated bond-containing group, and the number of maleimide groups in one molecule is preferably 1 or more, and may be 5 or less, 3 or less, or 2 or less, from the viewpoint of dielectric properties in a high frequency band of 10 GHz or more.

（式中、Ｒ^ａ１２は、各々独立に、炭素数１～５の脂肪族炭化水素基又はハロゲン原子である。ｍ１は０～４の整数である。Ｘ^ａ３は、下記一般式（ａ２－２）、（ａ２－３）、（ａ２－４）又は（ａ２－５）で表される２価の基である。） From the viewpoints of high-frequency characteristics (low dielectric constant, low dielectric tangent), adhesion to a conductor, heat resistance, glass transition temperature, thermal expansion coefficient, and flame retardancy, the component (A2) preferably contains a structure derived from bismaleimide in which nitrogen atoms of two maleimide groups are bonded to each other via an organic group, and more preferably has a group represented by the following general formula (a2-1):

(In the formula, each R ^a12 is independently an aliphatic hydrocarbon group having 1 to 5 carbon atoms or a halogen atom. m1 is an integer of 0 to 4. ^{X a3} is a divalent group represented by the following general formula (a2-2), (a2-3), (a2-4) or (a2-5).)

Examples of the aliphatic hydrocarbon group having 1 to 5 carbon atoms represented by R ^a12 include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a t-butyl group, and an n-pentyl group. The aliphatic hydrocarbon group may be an aliphatic hydrocarbon group having 1 to 3 carbon atoms, or may be a methyl group. Examples of the halogen atom represented by R ^a12 include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom. Among the above, R ^a12 may be an aliphatic hydrocarbon group having 1 to 5 carbon atoms.
m1 is an integer of 0 to 4, and may be an integer of 0 to 2, or may be 0. When m1 is an integer of 2 or more, multiple R ^a12 may be the same or different.
The divalent group represented by X ^a3 and represented by general formula (a2-2), (a2-3), (a2-4) or (a2-5) is as follows.

（式中、Ｒ^ａ１３は、各々独立に、炭素数１～５の脂肪族炭化水素基又はハロゲン原子である。ｍ２は０～４の整数である。）
Ｒ^ａ１３が表す炭素数１～５の脂肪族炭化水素基、ハロゲン原子としては、Ｒ^ａ１２の場合と同様に説明される。
ｍ２は０～４の整数であり、入手容易性の観点から、０～２の整数であってもよく、０又は１であってもよく、０であってもよい。ｍ２が２以上の整数である場合、複数のＲ^ａ１３同士は同一であっても異なっていてもよい。

(In the formula, each R ^a13 is independently an aliphatic hydrocarbon group having 1 to 5 carbon atoms or a halogen atom; and m2 is an integer of 0 to 4.)
The aliphatic hydrocarbon group having 1 to 5 carbon atoms and the halogen atom represented by R ^a13 are the same as those described for R ^a12 .
m2 is an integer of 0 to 4, and from the viewpoint of availability, may be an integer of 0 to 2, may be 0 or 1, or may be 0. When m2 is an integer of 2 or more, multiple R ^a13 may be the same or different.

（式中、Ｒ^ａ１４及びＲ^ａ１５は、各々独立に、炭素数１～５の脂肪族炭化水素基又はハロゲン原子である。Ｘ^ａ４は炭素数１～５のアルキレン基、炭素数２～５のアルキリデン基、エーテル基、スルフィド基、スルホニル基、カルボニルオキシ基、ケト基、単結合、又は下記一般式（ａ２－３－１）で表される２価の基である。ｍ３及びｍ４は各々独立に０～４の整数である。）
Ｒ^ａ１４及びＲ^ａ１５が表す炭素数１～５の脂肪族炭化水素基、ハロゲン原子としては、Ｒ^ａ１２の場合と同じものが挙げられる。該脂肪族炭化水素基としては、炭素数１～３の脂肪族炭化水素基であってもよく、メチル基、エチル基であってもよく、エチル基であってもよい。
Ｘ^ａ４が表す炭素数１～５のアルキレン基としては、例えば、メチレン基、１，２－ジメチレン基、１，３－トリメチレン基、１，４－テトラメチレン基、１，５－ペンタメチレン基等が挙げられる。該アルキレン基としては、高周波特性（低誘電率、低誘電正接）、導体との接着性、耐熱性、ガラス転移温度、熱膨張係数及び難燃性の観点から、炭素数１～３のアルキレン基であってもよく、メチレン基であってもよい。
Ｘ^ａ４が表す炭素数２～５のアルキリデン基としては、例えば、エチリデン基、プロピリデン基、イソプロピリデン基、ブチリデン基、イソブチリデン基、ペンチリデン基、イソペンチリデン基等が挙げられる。これらの中でも、高周波特性（低誘電率、低誘電正接）、導体との接着性、耐熱性、ガラス転移温度、熱膨張係数及び難燃性の観点から、イソプロピリデン基であってもよい。
Ｘ^ａ４としては、上記選択肢の中でも、炭素数１～５のアルキレン基、炭素数２～５のアルキリデン基であってもよい。
ｍ３及びｍ４は各々独立に０～４の整数であり、入手容易性の観点から、いずれも、０～２の整数であってもよく、０又は２であってもよい。ｍ３又はｍ４が２以上の整数である場合、複数のＲ^ａ１４同士又はＲ^ａ１５同士は、それぞれ同一であっても異なっていてもよい。
なお、Ｘ^ａ４が表す一般式（ａ２－３－１）で表される２価の基は以下のとおりである。

(In the formula, R ^a14 and R ^a15 each independently represent an aliphatic hydrocarbon group having 1 to 5 carbon atoms or a halogen atom. X ^a4 represents an alkylene group having 1 to 5 carbon atoms, an alkylidene group having 2 to 5 carbon atoms, an ether group, a sulfide group, a sulfonyl group, a carbonyloxy group, a keto group, a single bond, or a divalent group represented by the following general formula (a2-3-1). m3 and m4 each independently represent an integer of 0 to 4.)
Examples of the aliphatic hydrocarbon group having 1 to 5 carbon atoms and the halogen atom represented by R ^a14 and R ^a15 include the same as those for R ^a12 . The aliphatic hydrocarbon group may be an aliphatic hydrocarbon group having 1 to 3 carbon atoms, a methyl group, an ethyl group, or an ethyl group.
Examples of the alkylene group having 1 to 5 carbon atoms represented by X ^a4 include a methylene group, a 1,2-dimethylene group, a 1,3-trimethylene group, a 1,4-tetramethylene group, a 1,5-pentamethylene group, etc. From the viewpoints of high-frequency characteristics (low dielectric constant, low dielectric tangent), adhesion to a conductor, heat resistance, glass transition temperature, thermal expansion coefficient, and flame retardancy, the alkylene group may be an alkylene group having 1 to 3 carbon atoms or may be a methylene group.
Examples of the alkylidene group having 2 to 5 carbon atoms represented by X ^a4 include an ethylidene group, a propylidene group, an isopropylidene group, a butylidene group, an isobutylidene group, a pentylidene group, an isopentylidene group, etc. Among these, an isopropylidene group may be used from the viewpoints of high-frequency characteristics (low dielectric constant, low dielectric tangent), adhesion to a conductor, heat resistance, glass transition temperature, thermal expansion coefficient, and flame retardancy.
Among the above options, X ^a4 may be an alkylene group having 1 to 5 carbon atoms or an alkylidene group having 2 to 5 carbon atoms.
m3 and m4 each independently represent an integer of 0 to 4, and from the viewpoint of availability, each may be an integer of 0 to 2, or may be 0 or 2. When m3 or m4 is an integer of 2 or more, multiple R ^a14s or multiple R ^a15s may be the same or different.
The divalent group represented by X ^a4 in general formula (a2-3-1) is as follows.

（式中、Ｒ^ａ１６及びＲ^ａ１７は、各々独立に、炭素数１～５の脂肪族炭化水素基又はハロゲン原子である。Ｘ^ａ５は炭素数１～５のアルキレン基、イソプロピリデン基、エーテル基、スルフィド基、スルホニル基、カルボニルオキシ基、ケト基又は単結合である。ｍ５及びｍ６は各々独立に０～４の整数である。）
Ｒ^ａ１６及びＲ^ａ１７が表す炭素数１～５の脂肪族炭化水素基、ハロゲン原子としては、Ｒ^ａ１４及びＲ^ａ１５の場合と同様に説明される。
Ｘ^ａ５が表す炭素数１～５のアルキレン基、炭素数２～５のアルキリデン基としては、Ｘ^ａ４が表す炭素数１～５のアルキレン基、炭素数２～５のアルキリデン基と同じものが挙げられる。
Ｘ^ａ５としては、上記選択肢の中から、炭素数２～５のアルキリデン基を選択してもよい。
ｍ５及びｍ６は０～４の整数であり、入手容易性の観点から、いずれも、０～２の整数であってもよく、０又は１であってもよく、０であってもよい。ｍ５又はｍ６が２以上の整数である場合、複数のＲ^ａ１６同士又はＲ^ａ１７同士は、それぞれ同一であっても異なっていてもよい。

(In the formula, R ^a16 and R ^a17 each independently represent an aliphatic hydrocarbon group having 1 to 5 carbon atoms or a halogen atom. X ^a5 represents an alkylene group having 1 to 5 carbon atoms, an isopropylidene group, an ether group, a sulfide group, a sulfonyl group, a carbonyloxy group, a keto group, or a single bond. m5 and m6 each independently represent an integer of 0 to 4.)
The aliphatic hydrocarbon group having 1 to 5 carbon atoms and the halogen atom represented by R ^a16 and R ^a17 are the same as those explained for R ^a14 and R ^a15 .
Examples of the alkylene group having 1 to 5 carbon atoms and the alkylidene group having 2 to 5 carbon atoms represented by X ^a5 include the same as the alkylene group having 1 to 5 carbon atoms and the alkylidene group having 2 to 5 carbon atoms represented by X ^a4 .
X ^a5 may be an alkylidene group having 2 to 5 carbon atoms selected from the above options.
m5 and m6 are integers of 0 to 4, and from the viewpoint of availability, each may be an integer of 0 to 2, or may be 0 or 1, or may be 0. When m5 or m6 is an integer of 2 or more, multiple R ^a16s or multiple R ^a17s may be the same or different.

（式中、ｍ７は０～１０の整数である。）
ｍ７は、入手容易性の観点から、０～５の整数であってもよく、０～３の整数であってもよい。

(In the formula, m7 is an integer from 0 to 10.)
From the viewpoint of availability, m7 may be an integer of 0 to 5, or may be an integer of 0 to 3.

（式中、Ｒ^ａ１８及びＲ^ａ１９は各々独立に、水素原子又は炭素数１～５の脂肪族炭化水素基である。ｍ８は１～８の整数である。）
Ｒ^ａ１８及びＲ^ａ１９が表す炭素数１～５の脂肪族炭化水素基、ハロゲン原子としては、Ｒ^ａ１２の場合と同様に説明される。
ｍ８は１～８の整数であり、１～３の整数であってもよく、１であってもよい。

(In the formula, R ^a18 and R ^a19 each independently represent a hydrogen atom or an aliphatic hydrocarbon group having 1 to 5 carbon atoms; m8 represents an integer of 1 to 8.)
The aliphatic hydrocarbon group having 1 to 5 carbon atoms and the halogen atom represented by R ^a18 and R ^a19 are the same as those described for R ^a12 .
m8 is an integer of 1 to 8, and may be an integer of 1 to 3, or may be 1.

In terms of high frequency characteristics (low dielectric constant, low dielectric tangent), adhesion to a conductor, heat resistance, glass transition temperature, thermal expansion coefficient, and flame retardancy, X ^a3 in the group represented by the above general formula (a2-1) is preferably a group represented by any of the following formulas:

（式中、Ｘ^ａ３、Ｒ^ａ１１、Ｒ^ａ１２、ｎ３及びｍ１は上記定義のとおりである。ｍ９は１以上の整数である。）
ｍ９は、１～３００の整数であってもよく、１０～２５０の整数であってもよく、３０～２００の整数であってもよく、５０～１５０の整数であってもよい。 The component (A2) is preferably a polyphenylene ether derivative represented by the following general formula (a2-6).

(In the formula, X ^a3 , R ^a11 , R ^a12 , n3 and m1 are as defined above. m9 is an integer of 1 or more.)
m9 may be an integer from 1 to 300, an integer from 10 to 250, an integer from 30 to 200, or an integer from 50 to 150.

（式中、ｍ９は上記一般式（ａ２－６）中のｍ９と同じである。） The component (A2) is more preferably a polyphenylene ether derivative represented by any one of the following general formulas:

(In the formula, m9 is the same as m9 in general formula (a2-6) above.)

As the (A2) component, a polyphenylene ether derivative represented by the above general formula (a2-7) is preferred from the viewpoint of inexpensive raw materials, a polyphenylene ether derivative represented by the above general formula (a2-8) is preferred from the viewpoint of excellent dielectric properties and low water absorption, and a polyphenylene ether derivative represented by the above general formula (a2-9) is preferred from the viewpoint of excellent adhesion to the conductor and mechanical properties (elongation, breaking strength, etc.). Therefore, depending on the desired properties, one type of polyphenylene ether derivative represented by any of the above general formulas (a2-7) to (a2-9) can be used alone or two or more types can be used in combination.

[Number average molecular weight (Mn) of component (A2)]
The number average molecular weight of component (A2) is preferably 4,000 to 12,000, more preferably 5,000 to 10,000, and even more preferably 6,000 to 8,000. When the number average molecular weight of component (A2) is 4,000 or more, a better glass transition temperature tends to be obtained, and when it is 12,000 or less, better moldability tends to be obtained.

[Method for producing component (A2)]
The component (A2) can be obtained, for example, by the following production method.
First, an aminophenol compound represented by the following general formula (a2-10) [hereinafter may be abbreviated as aminophenol compound (AP)] and, for example, a polyphenylene ether having a number average molecular weight of 15,000 to 25,000 are subjected to a known redistribution reaction in an organic solvent to produce a polyphenylene ether compound (A″) [hereinafter may be simply abbreviated as polyphenylene ether compound (A″)] having a primary amino group in one molecule while decreasing the molecular weight of the polyphenylene ether. Next, the polyphenylene ether compound (A″) is subjected to a Michael addition reaction with a bismaleimide compound represented by the following general formula (a2-11) [hereinafter may be abbreviated as bismaleimide compound (BM)] to produce the component (A2).

（式中、Ｒ^ａ１２及びｍ１は、上記一般式（ａ２－１）中のものと同じである。）

(In the formula, R ^a12 and m1 are the same as those in the above general formula (a2-1).)

（式中、Ｘ^ａ３は、上記一般式（ａ２－１）中のものと同じである。）

(In the formula, ^Xa3 is the same as in the above general formula (a2-1).)

Examples of the aminophenol compound (AP) include o-aminophenol, m-aminophenol, p-aminophenol, etc. Among these, from the viewpoints of the reaction yield when producing the polyphenylene ether compound (A'') and the heat resistance when made into a resin composition, prepreg, and laminate, m-aminophenol and p-aminophenol are preferred, and p-aminophenol is more preferred.

The molecular weight of the polyphenylene ether compound (A'') can be controlled by the amount of the aminophenol compound (AP) used. The greater the amount of the aminophenol compound (AP) used, the lower the molecular weight of the polyphenylene ether compound (A''). In other words, the amount of the aminophenol compound (AP) used can be appropriately adjusted so that the number average molecular weight of the finally produced component (A2) falls within a suitable range.
The amount of the aminophenol compound (AP) to be blended is not particularly limited, but for example, if the number average molecular weight of the polyphenylene ether to be reacted with the aminophenol compound (AP) is 15,000 to 25,000, then by using the compound in the range of 0.5 to 6 parts by mass per 100 parts by mass of the polyphenylene ether, it is possible to obtain an (A2) component having a number average molecular weight of 4,000 to 12,000.

The polyphenylene ether compound (A'') is obtained by charging a reactor with predetermined amounts of the aminophenol compound (AP), the polyphenylene ether having a number average molecular weight of 15,000 to 25,000, an organic solvent, and, if necessary, a reaction catalyst, and reacting them while heating, keeping the temperature, and stirring. The reaction temperature and reaction time in this step can be the same as those in the production method for component (A1) above, and are reaction conditions that are applicable to known redistribution reactions. In addition, the preferred embodiments of the organic solvent, reaction catalyst, and the amounts used thereof used in the production step are the same as those in the production method for component (A1).

The solution of polyphenylene ether compound (A'') produced in the above manner may be continuously supplied as it is to the next step of producing a polyphenylene ether derivative (A2). At this time, the solution of polyphenylene ether compound (A'') may be cooled or adjusted to the reaction temperature of the next step. Furthermore, this solution may be concentrated as necessary to remove a portion of the organic solvent, or may be diluted by adding an organic solvent.

Examples of the bismaleimide compound (BM) used in producing the component (A2) include bis(4-maleimidophenyl)methane, polyphenylmethane maleimide, bis(4-maleimidophenyl)ether, bis(4-maleimidophenyl)sulfone, 3,3'-dimethyl-5,5'-diethyl-4,4'-diphenylmethane bismaleimide, 4-methyl-1,3-phenylene bismaleimide, m-phenylene bismaleimide, 2,2-bis[4-(4- Examples of such bis(4-maleimidophenyl)propane, bis(4-maleimidophenyl)sulfone, bis(4-maleimidophenyl)sulfide, bis(4-maleimidophenyl)ketone, 2,2-bis[4-(4-maleimidophenoxy)phenyl]propane, bis[4-(4-maleimidophenoxy)phenyl]sulfone, 4,4'-bis(3-maleimidophenoxy)biphenyl, 1,6-bismaleimido-(2,2,4-trimethyl)hexane, etc. These may be used alone or in combination of two or more.
Among these, bis(4-maleimidophenyl)methane is preferred from the viewpoints of obtaining a polyphenylene ether derivative containing the above general formula (a2-7) and being inexpensive; 3,3'-dimethyl-5,5'-diethyl-4,4'-diphenylmethane bismaleimide is preferred from the viewpoints of obtaining a polyphenylene ether derivative containing the above general formula (a2-8), having excellent dielectric properties and low water absorption; and 2,2-bis[4-(4-maleimidophenoxy)phenyl]propane is preferred from the viewpoints of obtaining a polyphenylene ether derivative containing the above general formula (a2-9) and having high adhesion to a conductor and excellent mechanical properties (elongation, breaking strength, etc.).

The amount of the bismaleimide compound (BM) used is determined by the amount of the aminophenol compound (AP) used. The equivalent ratio (Tb1/Ta1) of the _-NH2 group equivalent (Ta1) of the aminophenol compound (AP) to the maleimide group equivalent (Tb1) of the bismaleimide compound (BM) is preferably 2 to 6, more preferably 2 to 4. By using the bismaleimide compound within the above-mentioned equivalent ratio range, the resin composition, prepreg, and laminate of this embodiment tend to have better heat resistance, high glass transition temperature, and high flame retardancy.

In the Michael addition reaction when producing the (A2) component, a reaction catalyst can be used as necessary. The reaction catalyst is not particularly limited, but examples thereof include acid catalysts such as p-toluenesulfonic acid; amines such as triethylamine, pyridine, and tributylamine; imidazole compounds such as methylimidazole and phenylimidazole; and phosphorus-based catalysts such as triphenylphosphine. These may be used alone or in combination of two or more. The amount of the reaction catalyst is not particularly limited, but is, for example, 0.01 to 5 parts by mass per 100 parts by mass of the polyphenylene ether compound (A'').

The bismaleimide compound (BM) and, if necessary, a reaction catalyst, etc. are charged in a predetermined amount into a polyphenylene ether compound (A'') solution, and the Michael addition reaction is carried out while heating, keeping warm, and stirring to obtain the component (A2). From the viewpoint of workability and gelation suppression, the reaction temperature may be, for example, 50 to 160°C, and the reaction time may be in the range of 1 to 10 hours. In addition, in this process, the reaction concentration (solid content concentration) and solution viscosity can be adjusted by adding or concentrating an organic solvent as described above. As the organic solvent to be additionally used, the organic solvents exemplified in the production process of the polyphenylene ether compound (A'') can be applied, and these may be used alone or in combination of two or more kinds. Among these, methyl ethyl ketone, cyclohexanone, propylene glycol monomethyl ether, N,N-dimethylformamide, and N,N-dimethylacetamide may be selected from the viewpoint of solubility.

The reaction concentration (solids concentration) in the production process of the component (A2) and the polyphenylene ether compound (A'') is not particularly limited, and may be, for example, 10 to 60 mass % or 20 to 50 mass % in any of the above production processes. When the reaction concentration is 10 mass % or more, the reaction rate does not become too slow, and there is a tendency that it is more advantageous in terms of production costs. Furthermore, when the reaction temperature is 60 mass % or less, better solubility tends to be obtained. Furthermore, the solution viscosity is low, the stirring efficiency is good, and gelation tends to occur less.
After the (A2) component is produced, the solution may be concentrated by removing part or all of the organic solvent in the solution, or may be diluted by adding an organic solvent, depending on the workability when removing the component from the reactor, the usage conditions when various thermosetting resins are added to the component (A2) to prepare the resin composition of the present embodiment (for example, the solution viscosity and solution concentration suitable for the production of a prepreg), etc. The organic solvent to be added is not particularly limited, and one or more of the organic solvents described above can be used.

The formation of the polyphenylene ether compounds (A'') and (A2) obtained by the above-mentioned production steps can be confirmed by taking a small amount of a sample after the end of each step and subjecting it to GPC measurement and IR measurement.
First, it can be confirmed that the desired polyphenylene ether compound (A'') has been produced by GPC measurement showing a lower molecular weight than polyphenylene ether having a number average molecular weight of 15,000 to 25,000 and disappearance of the peak of the raw material aminophenol compound (AP) and by IR measurement showing the appearance of a primary amino group at 3300 to 3500 cm ^-1 . Next, it can be confirmed that the desired (A2) component has been produced by purifying the (A2) component by reprecipitation and then confirming the disappearance of the peak of the primary amino group at 3300 to 3500 cm ^-1 and the appearance of a peak of the maleimide carbonyl group at 1700 to 1730 cm ^-1 by IR measurement.

<Maleimide Compound (B)>
The maleimide compound (B) is one or more selected from the group consisting of maleimide compounds having two or more N-substituted maleimide groups and derivatives thereof. The maleimide compound (B) does not include the polyphenylene ether derivative (A). Furthermore, the maleimide compound (B) does not contain the structural unit represented by the above general formula (a-1) and does not contain a polyphenylene ether skeleton.
Furthermore, examples of the "derivatives thereof" include addition reaction products of the maleimide compound having two or more N-substituted maleimide groups and an amine compound such as the diamine compound (b2) described below.
As the maleimide compound (B), from the viewpoints of solubility in organic solvents, compatibility, adhesion to conductors, and dielectric properties in a high frequency band of 10 GHz or more, a derivative of a maleimide compound having two or more N-substituted maleimide groups is preferred, and a polyamino bismaleimide compound having a structural unit derived from a maleimide compound (b1) [hereinafter, sometimes simply referred to as a maleimide compound (b1) or a (b1) component] having two or more N-substituted maleimide groups and a structural unit derived from a diamine compound (b2) [hereinafter, sometimes abbreviated as a polyamino bismaleimide compound (B1) or a (B1) component] is more preferred.
The structural units derived from the component (b1) and the structural units derived from the component (b2) may each be of one type or a combination of two or more types.

Specific examples of the (b1) component are not particularly limited as long as they are maleimide compounds having two or more N-substituted maleimide groups, and examples include aromatic maleimide compounds such as bis(4-maleimidophenyl)methane, polyphenylmethane maleimide, bis(4-maleimidophenyl)ether, bis(4-maleimidophenyl)sulfone, 3,3'-dimethyl-5,5'-diethyl-4,4'-diphenylmethane bismaleimide, 4-methyl-1,3-phenylene bismaleimide, m-phenylene bismaleimide, and 2,2-bis[4-(4-maleimidophenoxy)phenyl]propane; and aliphatic maleimide compounds such as 1,6-bismaleimido-(2,2,4-trimethyl)hexane and pyrrolidine binder type long-chain alkyl bismaleimide. Among these, from the viewpoints of adhesion to the conductor and mechanical properties, aromatic maleimide compounds are preferred, and 2,2-bis[4-(4-maleimidophenoxy)phenyl]propane and 3,3'-dimethyl-5,5'-diethyl-4,4'-diphenylmethane bismaleimide are more preferred.

（式中、Ｘ^ｂ１は２価の有機基を示し、＊は他の構造への結合位置を示す。） Examples of the structural unit derived from the component (b1) include one or more types selected from the group consisting of groups represented by the following general formula (b1-1) and groups represented by the following general formula (b1-2):

(In the formula, X ^b1 represents a divalent organic group, and * represents a bonding position to another structure.)

X ^b1 in the above general formulae (b1-1) and (b1-2) is a divalent organic group and corresponds to a residue of the component (b1). Note that the residue of the component (b1) refers to the structure of the portion of the component (b1) excluding the functional group used in the bond, i.e., the maleimide group.
Examples of the divalent organic group represented by X ^b1 include groups represented by the following general formula (b1-3), (b1-4), (b1-5) or (b1-6).

（式中、Ｒ^ｂ１は、各々独立に、炭素数１～５の脂肪族炭化水素基又はハロゲン原子である。ｐ１は０～４の整数である。）
Ｒ^ｂ１が表す炭素数１～５の脂肪族炭化水素基としては、例えば、メチル基、エチル基、ｎ－プロピル基、イソプロピル基、ｎ－ブチル基、イソブチル基、ｔ－ブチル基、ｎ－ペンチル基等が挙げられる。該脂肪族炭化水素基としては、炭素数１～３の脂肪族炭化水素基であってもよく、メチル基であってもよい。
ハロゲン原子としては、フッ素原子、塩素原子、臭素原子、ヨウ素原子等が挙げられる。
ｐ１は０～４の整数であり、入手容易性の観点から、０～２の整数であってもよく、０又は１であってもよく、０であってもよい。ｐ１が２以上の整数である場合、複数のＲ^ｂ１同士は同一であっても異なっていてもよい。

(In the formula, each R ^b1 is independently an aliphatic hydrocarbon group having 1 to 5 carbon atoms or a halogen atom; p1 is an integer of 0 to 4.)
Examples of the aliphatic hydrocarbon group having 1 to 5 carbon atoms represented by R ^b1 include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a t-butyl group, an n-pentyl group, etc. The aliphatic hydrocarbon group may be an aliphatic hydrocarbon group having 1 to 3 carbon atoms or may be a methyl group.
Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.
p1 is an integer of 0 to 4, and from the viewpoint of availability, may be an integer of 0 to 2, may be 0 or 1, or may be 0. When p1 is an integer of 2 or more, multiple R ^b1 may be the same or different.

（式中、Ｒ^ｂ２及びＲ^ｂ３は、各々独立に、炭素数１～５の脂肪族炭化水素基又はハロゲン原子である。Ｘ^ｂ２は炭素数１～５のアルキレン基、炭素数２～５のアルキリデン基、エーテル基、スルフィド基、スルホニル基、カルボニルオキシ基、ケト基、単結合、又は下記一般式（ｂ１－４－１）で表される２価の基である。ｐ２及びｐ３は各々独立に０～４の整数である。）
Ｒ^ｂ２及びＲ^ｂ３が表す炭素数１～５の脂肪族炭化水素基、ハロゲン原子としては、Ｒ^ｂ１の場合と同じものが挙げられる。該脂肪族炭化水素基としては、炭素数１～３の脂肪族炭化水素基であってもよく、メチル基、エチル基であってもよく、エチル基であってもよい。
Ｘ^ｂ２が表す炭素数１～５のアルキレン基としては、例えば、メチレン基、１，２－ジメチレン基、１，３－トリメチレン基、１，４－テトラメチレン基、１，５－ペンタメチレン基等が挙げられる。該アルキレン基としては、高周波特性（低誘電率、低誘電正接）、導体との接着性、耐熱性、ガラス転移温度、熱膨張係数及び難燃性の観点から、炭素数１～３のアルキレン基であってもよく、メチレン基であってもよい。
Ｘ^ｂ２が表す炭素数２～５のアルキリデン基としては、例えば、エチリデン基、プロピリデン基、イソプロピリデン基、ブチリデン基、イソブチリデン基、ペンチリデン基、イソペンチリデン基等が挙げられる。これらの中でも、高周波特性（低誘電率、低誘電正接）、導体との接着性、耐熱性、ガラス転移温度、熱膨張係数及び難燃性の観点から、イソプロピリデン基であってもよい。
Ｘ^ｂ２としては、上記選択肢の中でも、炭素数１～５のアルキレン基、炭素数２～５のアルキリデン基であってもよい。
ｐ２及びｐ３は各々独立に０～４の整数であり、入手容易性の観点から、いずれも、０～２の整数であってもよく、０又は２であってもよい。ｐ２又はｐ３が２以上の整数である場合、複数のＲ^ｂ２同士又はＲ^ｂ３同士は、それぞれ同一であっても異なっていてもよい。
なお、Ｘ^ｂ２が表す一般式（ｂ１－４－１）で表される２価の基は以下のとおりである。

(In the formula, R ^b2 and R ^b3 each independently represent an aliphatic hydrocarbon group having 1 to 5 carbon atoms or a halogen atom. X ^b2 represents an alkylene group having 1 to 5 carbon atoms, an alkylidene group having 2 to 5 carbon atoms, an ether group, a sulfide group, a sulfonyl group, a carbonyloxy group, a keto group, a single bond, or a divalent group represented by the following general formula (b1-4-1). p2 and p3 each independently represent an integer of 0 to 4.)
Examples of the aliphatic hydrocarbon group having 1 to 5 carbon atoms and the halogen atom represented by R ^b2 and R ^b3 include the same as those for R ^b1 . The aliphatic hydrocarbon group may be an aliphatic hydrocarbon group having 1 to 3 carbon atoms, a methyl group, an ethyl group, or an ethyl group.
Examples of the alkylene group having 1 to 5 carbon atoms represented by X ^b2 include a methylene group, a 1,2-dimethylene group, a 1,3-trimethylene group, a 1,4-tetramethylene group, a 1,5-pentamethylene group, etc. From the viewpoints of high-frequency characteristics (low dielectric constant, low dielectric tangent), adhesion to a conductor, heat resistance, glass transition temperature, thermal expansion coefficient, and flame retardancy, the alkylene group may be an alkylene group having 1 to 3 carbon atoms or a methylene group.
Examples of the alkylidene group having 2 to 5 carbon atoms represented by X ^b2 include an ethylidene group, a propylidene group, an isopropylidene group, a butylidene group, an isobutylidene group, a pentylidene group, an isopentylidene group, etc. Among these, an isopropylidene group may be used from the viewpoints of high-frequency characteristics (low dielectric constant, low dielectric tangent), adhesion to a conductor, heat resistance, glass transition temperature, thermal expansion coefficient, and flame retardancy.
Among the above options, X ^b2 may be an alkylene group having 1 to 5 carbon atoms or an alkylidene group having 2 to 5 carbon atoms.
p2 and p3 each independently represent an integer of 0 to 4, and from the viewpoint of availability, each may be an integer of 0 to 2, or may be 0 or 2. When p2 or p3 is an integer of 2 or more, multiple R ^b2s or multiple R ^b3s may be the same or different.
The divalent group represented by X ^b2 and represented by general formula (b1-4-1) is as follows.

（式中、Ｒ^ｂ４及びＲ^ｂ５は、各々独立に、炭素数１～５の脂肪族炭化水素基又はハロゲン原子である。Ｘ^ｂ３は炭素数１～５のアルキレン基、イソプロピリデン基、エーテル基、スルフィド基、スルホニル基、カルボニルオキシ基、ケト基又は単結合である。ｐ４及びｐ５は各々独立に０～４の整数である。）
Ｒ^ｂ４及びＲ^ｂ５が表す炭素数１～５の脂肪族炭化水素基、ハロゲン原子としては、Ｒ^ｂ１の場合と同様に説明される。
Ｘ^ｂ３が表す炭素数１～５のアルキレン基、炭素数２～５のアルキリデン基としては、Ｘ^ｂ２が表す炭素数１～５のアルキレン基、炭素数２～５のアルキリデン基と同じものが挙げられる。
Ｘ^ｂ３としては、上記選択肢の中から、炭素数２～５のアルキリデン基を選択してもよい。
ｐ４及びｐ５は０～４の整数であり、入手容易性の観点から、いずれも、０～２の整数であってもよく、０又は１であってもよく、０であってもよい。ｐ４又はｐ５が２以上の整数である場合、複数のＲ^ｂ４同士又はＲ^ｂ５同士は、それぞれ同一であっても異なっていてもよい。

(In the formula, R ^b4 and R ^b5 each independently represent an aliphatic hydrocarbon group having 1 to 5 carbon atoms or a halogen atom. X ^b3 represents an alkylene group having 1 to 5 carbon atoms, an isopropylidene group, an ether group, a sulfide group, a sulfonyl group, a carbonyloxy group, a keto group, or a single bond. p4 and p5 each independently represent an integer of 0 to 4.)
The aliphatic hydrocarbon group having 1 to 5 carbon atoms and the halogen atom represented by R ^b4 and R ^b5 are the same as those described for R ^b1 .
Examples of the alkylene group having 1 to 5 carbon atoms and the alkylidene group having 2 to 5 carbon atoms represented by X ^b3 include the same as the alkylene group having 1 to 5 carbon atoms and the alkylidene group having 2 to 5 carbon atoms represented by X ^b2 .
X ^b3 may be an alkylidene group having 2 to 5 carbon atoms selected from the above options.
p4 and p5 are integers of 0 to 4, and from the viewpoint of availability, each may be an integer of 0 to 2, or may be 0 or 1, or may be 0. When p4 or p5 is an integer of 2 or more, multiple R ^b4s or multiple R ^b5s may be the same or different.

（式中、ｐ６は０～１０の整数である。）
ｐ６は、入手容易性の観点から、０～５の整数であってもよく、０～３の整数であってもよい。

(In the formula, p6 is an integer from 0 to 10.)
From the viewpoint of availability, p6 may be an integer of 0 to 5, or may be an integer of 0 to 3.

（式中、Ｒ^ｂ６及びＲ^ｂ７は各々独立に、水素原子又は炭素数１～５の脂肪族炭化水素基である。ｐ７は１～８の整数である。）
Ｒ^ｂ６及びＲ^ｂ７が表す炭素数１～５の脂肪族炭化水素基、ハロゲン原子としては、Ｒ^ｂ１の場合と同様に説明される。
ｐ７は１～８の整数であり、１～３の整数であってもよく、１であってもよい。

(In the formula, R ^b6 and R ^b7 each independently represent a hydrogen atom or an aliphatic hydrocarbon group having 1 to 5 carbon atoms; and p7 represents an integer of 1 to 8.)
The aliphatic hydrocarbon group having 1 to 5 carbon atoms and the halogen atom represented by R ^b6 and R ^b7 are the same as those described for R ^b1 .
p7 is an integer of 1 to 8, and may be an integer of 1 to 3, or may be 1.

（波線は、マレイミド基中の窒素原子との結合位置を示す。） X ^b1 in the above general formulae (b1-1) and (b1-2) is preferably a divalent group represented by any one of the following formulae (X ^b1 -1) to (X ^b1 -3) from the viewpoint of adhesion to a conductor, heat resistance, glass transition temperature, thermal expansion coefficient, flame retardancy, and dielectric properties in a high frequency band of 10 GHz or more, and more preferably a divalent group represented by the following formula (X ^b1 -3). In addition, from the viewpoint of dielectric properties in a high frequency band of 10 GHz or more, X ^b1 may have both a group represented by the following formula (X ^b1 -1) and a group represented by the following formula (X ^b1 -3), or X ^b1 may have both a group represented by the following formula (X ^b1 -2) and a group represented by the following formula (X ^b1 -3).

(The wavy line indicates the bond position to the nitrogen atom in the maleimide group.)

The total content of structural units derived from component (b1) in maleimide compound (B) is preferably 5 to 95% by mass, more preferably 30 to 93% by mass, even more preferably 60 to 90% by mass, and particularly preferably 75 to 90% by mass. When the content of structural units derived from component (b1) is within the above range, the dielectric properties in the high frequency band of 10 GHz or more tend to be better, and good film handling properties tend to be obtained.

There are no particular limitations on the component (b2) so long as it is a compound having two amino groups.
Examples of the component (b2) include 4,4'-diaminodiphenylmethane, 4,4'-diamino-3,3'-dimethyldiphenylmethane, 4,4'-diamino-3,3'-diethyldiphenylmethane, 4,4'-diaminodiphenyl ether, 4,4'-diaminodiphenyl sulfone, 3,3'-diaminodiphenyl sulfone, 4,4'-diaminodiphenyl ketone, 4,4'-diaminobiphenyl, 3,3'-dimethyl-4,4'-diaminobiphenyl, 2,2'-dimethyl-4,4'-diaminobiphenyl, 3,3'-dihydroxybenzidine, 2,2-bis(3-amino-4-hydroxyphenyl)propane, 3,3'-dimethyl-5,5'-diethyl-4,4'-diaminodiphenylmethane, 2,2-bis(4-aminophenyl)propane, 2,2-bis[4-(4-aminophenoxy)phenyl]propane, 1,3 ... bis(3-aminophenoxy)benzene, 1,3-bis(4-aminophenoxy)benzene, 1,4-bis(4-aminophenoxy)benzene, 4,4'-bis(4-aminophenoxy)biphenyl, 1,3-bis[1-[4-(4-aminophenoxy)phenyl]-1-methylethyl]benzene, 1,4-bis[1-[4-(4-aminophenoxy)phenyl]-1-methylethyl]benzene, 4,4'-[1,3 4,4'-[1,4-phenylenebis(1-methylethylidene)]bisaniline, 3,3'-[1,3-phenylenebis(1-methylethylidene)]bisaniline, bis[4-(4-aminophenoxy)phenyl]sulfone, bis[4-(3-aminophenoxy)phenyl]sulfone, and 9,9-bis(4-aminophenyl)fluorene.

Among these, 4,4'-diaminodiphenylmethane, 4,4'-diamino-3,3'-dimethyldiphenylmethane, 4,4'-diamino-3,3'-diethyldiphenylmethane, 2,2-bis[4-(4-aminophenoxy)phenyl]propane, 4,4'-[1,3-phenylenebis(1-methylethylidene)]bisaniline, and 4,4'-[1,4-phenylenebis(1-methylethylidene)]bisaniline are preferred as component (b2) from the viewpoints of excellent solubility in organic solvents, reactivity with component (b1), and heat resistance. Also, 3,3'-dimethyl-5,5'-diethyl-4,4'-diaminodiphenylmethane is preferred as component (b2) from the viewpoints of excellent dielectric properties and low water absorption in high frequency bands of 10 GHz or more. From the viewpoints of excellent mechanical properties such as high adhesion to the conductor, elongation, and breaking strength, the component (b2) is preferably 2,2-bis[4-(4-aminophenoxy)phenyl]propane. Furthermore, from the viewpoints of excellent solubility in the above organic solvents, reactivity during synthesis, heat resistance, and high adhesion to the conductor, as well as excellent dielectric properties and low moisture absorption in high frequency bands of 10 GHz or more, the component (b2) is preferably 4,4'-[1,3-phenylenebis(1-methylethylidene)]bisaniline or 4,4'-[1,4-phenylenebis(1-methylethylidene)]bisaniline.

Examples of structural units derived from component (b2) include one or more types selected from the group consisting of groups represented by the following general formula (b2-1) and groups represented by the following general formula (b2-2):

（式中、Ｘ^ｂ４は２価の有機基を示し、＊は他の構造への結合位置を示す。）

(In the formula, X ^b4 represents a divalent organic group, and * represents a bonding position to another structure.)

^Xb4 in the above general formulae (b2-1) and (b2-2) is a divalent organic group and corresponds to a residue of the component (b2). The residue of the component (b2) refers to the structure of the portion of the component (b2) excluding the functional group used in the bond, i.e., the amino group.

（式中、Ｒ^ｂ１１及びＲ^ｂ１２は、各々独立に、炭素数１～５の脂肪族炭化水素基、炭素数１～５のアルコキシ基、水酸基又はハロゲン原子である。Ｘ^ｂ５は、炭素数１～５のアルキレン基、炭素数２～５のアルキリデン基、エーテル基、スルフィド基、スルホニル基、カルボニルオキシ基、ケト基、フルオレニレン基、単結合、又は下記一般式（ｂ２－３－１）もしくは（ｂ２－３－２）で表される２価の基である。ｐ８及びｐ９は各々独立に０～４の整数である。） X ^b4 in the above general formula (b2-1) and the above general formula (b2-2) is preferably a divalent group represented by the following general formula (b2-3).

(In the formula, R ^b11 and R ^b12 each independently represent an aliphatic hydrocarbon group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, a hydroxyl group, or a halogen atom. X ^b5 represents an alkylene group having 1 to 5 carbon atoms, an alkylidene group having 2 to 5 carbon atoms, an ether group, a sulfide group, a sulfonyl group, a carbonyloxy group, a keto group, a fluorenylene group, a single bond, or a divalent group represented by the following general formula (b2-3-1) or (b2-3-2). p8 and p9 each independently represent an integer of 0 to 4.)

（式中、Ｒ^ｂ１３及びＲ^ｂ１４は、各々独立に、炭素数１～５の脂肪族炭化水素基又はハロゲン原子である。Ｘ^ｂ６は炭素数１～５のアルキレン基、イソプロピリデン基、ｍ－フェニレンジイソプロピリデン基、ｐ－フェニレンジイソプロピリデン基、エーテル基、スルフィド基、スルホニル基、カルボニルオキシ基、ケト基又は単結合である。ｐ１０及びｐ１１は各々独立に０～４の整数である。）

(In the formula, R ^b13 and R ^b14 each independently represent an aliphatic hydrocarbon group having 1 to 5 carbon atoms or a halogen atom. X ^b6 each independently represents an alkylene group having 1 to 5 carbon atoms, an isopropylidene group, an m-phenylenediisopropylidene group, a p-phenylenediisopropylidene group, an ether group, a sulfide group, a sulfonyl group, a carbonyloxy group, a keto group, or a single bond. p10 and p11 each independently represent an integer of 0 to 4.)

（式中、Ｒ^ｂ１５は、各々独立に、炭素数１～５の脂肪族炭化水素基又はハロゲン原子である。Ｘ^ｂ７及びＸ^ｂ８は各々独立に、炭素数１～５のアルキレン基、イソプロピリデン基、エーテル基、スルフィド基、スルホニル基、カルボニルオキシ基、ケト基又は単結合である。ｐ１２は０～４の整数である。）

(In the formula, each R ^b15 independently represents an aliphatic hydrocarbon group having 1 to 5 carbon atoms or a halogen atom. Each X ^b7 and X ^b8 independently represents an alkylene group having 1 to 5 carbon atoms, an isopropylidene group, an ether group, a sulfide group, a sulfonyl group, a carbonyloxy group, a keto group, or a single bond. p12 is an integer of 0 to 4.)

The aliphatic hydrocarbon group having 1 to 5 carbon atoms or halogen atom represented by R ^b11 , R ^b12 , R ^b13 , R ^b14 and R ^b15 in general formula (b2-3), (b2-3-1) or (b2-3-2) above can be the same as R ^b1 in general formula (b1-3) above. The aliphatic hydrocarbon group may be an aliphatic hydrocarbon group having 1 to 3 carbon atoms, or may be a methyl group or an ethyl group.
The alkylene group having 1 to 5 carbon atoms represented by X ^b5 and X ^b6 in the above general formula (b2-3), (b2-3-1) or (b2-3-2) and the alkylidene group having 2 to 5 carbon atoms represented by X ^b5 are explained in the same manner as for X ^b2 in the above general formula (b1-4). The alkylene group having 1 to 5 carbon atoms represented by X ^b7 and X ^b8 in the above general formula (b2-3-2) are explained in the same manner as for X ^b2 in the above general formula (b1-4).
p8 and p9 are integers from 0 to 4, and from the viewpoint of availability, each may be an integer from 0 to 2, or may be 0 or 2. p10 and p11 are integers from 0 to 4, and from the viewpoint of availability, each may be an integer from 0 to 2, or may be 0 or 1, or may be 0. p12 is an integer from 0 to 4, and from the viewpoint of availability, each may be an integer from 0 to 2, or may be 0.

The total content of structural units derived from component (b2) in maleimide compound (B) is preferably 5 to 95% by mass, more preferably 7 to 70% by mass, even more preferably 10 to 40% by mass, and particularly preferably 10 to 25% by mass. When the total content of structural units derived from component (b2) is within the above range, excellent dielectric properties in the high frequency band of 10 GHz or more, and better heat resistance, flame retardancy, and glass transition temperature tend to be obtained.

The content ratio of the structural unit derived from the component (b1) and the structural unit derived from the component (b2) in the maleimide compound (B) is such that the equivalent ratio (Ta2/Ta1) of the total equivalent (Ta2) of the group (including _-NH2 ) derived from the _-NH2 group of the component (b2) in the maleimide compound (B) to the total equivalent (Ta1) of the group (including maleimide group) derived from the maleimide group derived from the component (b1) is preferably 0.05 to 10, more preferably 1 to 5. When the equivalent ratio (Ta2/Ta1) is within the above range, the dielectric properties are excellent in a high frequency band of 10 GHz or more, and better heat resistance, flame retardancy, and glass transition temperature tend to be obtained.

From the viewpoints of dielectric properties in the high frequency band of 10 GHz or more, as well as solubility in organic solvents, high adhesion to conductors, and moldability of the resin film, it is preferable that the maleimide compound (B) contains a polyaminobismaleimide compound represented by the following general formula (b2-4):

（式中、Ｘ^ｂ１及びＸ^ｂ４は、上記で説明したとおりである。）

(In the formula, X ^b1 and X ^b4 are as described above.)

(Method for producing polyaminobismaleimide compound (B1))
The component (B1) can be produced, for example, by reacting the components (b1) and (b2) in an organic solvent.
When the polyamino bismaleimide compound (B1) is produced by reacting the component (b1) with the component (b2), a reaction catalyst can be used as necessary. The reaction catalyst is not limited, but examples thereof include acid catalysts such as p-toluenesulfonic acid; amines such as triethylamine, pyridine, and tributylamine; imidazoles such as methylimidazole and phenylimidazole; and phosphorus-based catalysts such as triphenylphosphine. These may be used alone or in combination of two or more. There is no particular limit to the amount of the reaction catalyst used, but it is sufficient to use 0.01 to 5 parts by mass with respect to 100 parts by mass of the total amount of the component (b1) and the component (b2).

The polyaminobismaleimide compound is obtained by charging the (b1) component, the (b2) component, and other components, if necessary, in a synthesis vessel in predetermined amounts, and subjecting the (b1) component and the (b2) component to a Michael addition reaction. The reaction conditions in this step are not particularly limited, but from the viewpoints of workability such as reaction rate, gelation inhibition, etc., the reaction temperature is preferably 50 to 160°C, and the reaction time is preferably 1 to 10 hours.
In this step, the organic solvent can be added or concentrated to adjust the solid content concentration and solution viscosity of the reaction raw materials. The solid content concentration of the reaction raw materials is not particularly limited, but is preferably 10 to 90 mass%, more preferably 20 to 80 mass%. When the solid content concentration of the reaction raw materials is 10 mass% or more, the reaction rate does not become too slow, and it tends to be advantageous in terms of production costs. When the solid content concentration of the reaction raw materials is 90 mass% or less, better solubility is obtained, the stirring efficiency is improved, and gelation tends to be less likely.

The number average molecular weight of the polyaminobismaleimide compound (B1) thus obtained is not particularly limited, but is preferably 400 to 10,000, more preferably 500 to 5,000, even more preferably 600 to 2,000, and particularly preferably 700 to 1,500. The weight average molecular weight of the polyaminobismaleimide compound (B1) is measured in terms of polystyrene by gel permeation chromatography (GPC).

(Contents of component (A) and component (B) and their content ratios)
In the resin composition of the present embodiment, the content of component (A) is not particularly limited, but from the viewpoint of dielectric properties in the high frequency band of 10 GHz or more, the content is preferably 1 part by mass or more, more preferably 1 to 20 parts by mass, even more preferably 2 to 10 parts by mass, and particularly preferably 3 to 7 parts by mass, relative to 100 parts by mass of the total of the resin components in the resin composition.
In this specification, the term "resin component" refers to the components (A), (B), (C), and, optionally, the component (D). In other words, when the resin composition does not contain the component (D), the "resin component" refers to the components (A), (B), and (C), and when the resin composition contains the component (D), the "resin component" includes the components (A), (B), (C), and (D).
The content of the (B) component is not particularly limited, but from the viewpoint of dielectric properties and moldability in a high frequency band of 10 GHz or more, the content is preferably 10 to 90 parts by mass, more preferably 20 to 80 parts by mass, even more preferably 30 to 70 parts by mass, and particularly preferably 35 to 60 parts by mass, relative to 100 parts by mass of the total of the resin components in the resin composition.
The content ratio of the (A) component to the (B) component [(A)/(B)] is not particularly limited, but is preferably 1/99 to 80/20, more preferably 3/97 to 75/25, even more preferably 5/95 to 70/30, even more preferably 5/95 to 50/50, particularly preferably 5/95 to 20/80, and most preferably 5/95 to 15/85, in terms of mass ratio. When the content ratio [(A)/(B)] is 1/99 or more, excellent dielectric properties tend to be obtained in high frequency bands of 10 GHz or more, and when it is 80/20 or less, excellent heat resistance, moldability, and processability tend to be obtained.

<Crosslinking Agent (C)>
The crosslinking agent (C) is a crosslinking agent having two or more ethylenically unsaturated bonds.
The resin composition of the present embodiment is excellent in heat resistance and dielectric properties in particular by containing the crosslinking agent (C). Although the reason for this is not clear, it is presumed to be as follows.
The polyphenylene ether derivative (A) contained in the resin composition of this embodiment has an ethylenically unsaturated bond as a reactive group, and can form a cured product by reacting with the (A) component or with the (B) component. However, since the (A) component is a polymer, it may not be sufficiently miscible with other components, or the ethylenically unsaturated bond serving as a reaction point may be present at a part of the end of the molecular chain, etc., and may not be sufficiently reactive with other reactive groups. In the resin composition of this embodiment, it is expected that the application of the crosslinking agent (C) increases the probability that an ethylenically unsaturated bond (derived from the crosslinking agent (C)) exists in the vicinity of the ethylenically unsaturated bond of the (A) component, and an environment in which the ethylenically unsaturated bond of the (A) component is easily reactive is created. It is presumed that this improves the reactivity of the (A) component compared to the conventional method, and that excellent heat resistance and dielectric properties are obtained. Furthermore, it is presumed that the application of the crosslinking agent (C) makes it possible to further densify the three-dimensional crosslinked structure of the cured product formed, and that even more excellent heat resistance and dielectric properties are obtained.

The ethylenically unsaturated bond in component (C) is, for example, an unsaturated bond contained in an unsaturated aliphatic hydrocarbon group such as a vinyl group, an isopropenyl group, an allyl group, a 1-methylallyl group, or a 3-butenyl group; or a heteroatom-containing substituent such as a maleimide group or a (meth)acryloyl group. Among these, from the viewpoint of dielectric properties in high frequency bands of 10 GHz or more, component (C) preferably has an ethylenically unsaturated bond in the unsaturated aliphatic hydrocarbon group, and more preferably has an ethylenically unsaturated bond in the vinyl group.

From the viewpoint of obtaining excellent heat resistance, the number of ethylenically unsaturated bonds contained in one molecule of component (C) is preferably 3 or more, more preferably 5 or more, and even more preferably 10 or more.

Examples of the component (C) include monomers or polymers having two or more ethylenically unsaturated bonds as vinyl groups, such as 1,2,4-trivinylcyclohexane, 1,4-butanediol divinyl ether, nonanediol divinyl ether, 1,4-cyclohexane dimethanol divinyl ether, triethylene glycol divinyl ether, trimethylolpropane trivinyl ether, pentaerythritol tetravinyl ether, divinylbenzene, divinylbiphenyl, 1,3-bis(vinyloxy)adamantane, 1,3,5-tris(vinyloxy)adamantane, vinylcyclohexene, polybutadiene having two or more 1,2-vinyl groups, and butadiene-styrene copolymers having two or more 1,2-vinyl groups; diallyl phthalate, triallyl trimellitate, diethylene glycol bisallyl carbonate, trimethylolpropane diallyl ether, and trimethylolpropane triallyl ether. Examples of such monomers or polymers include those having two or more ethylenically unsaturated bonds as allyl groups, such as 1,3-bis(allyloxy)adamantane, 1,3,5-tris(allyloxy)adamantane, diallyl ether, bisphenol A diallyl ether, 2,5-diallylphenol allyl ether, allyl ether of novolak phenol, and allylated polyphenylene oxide; compounds having two or more ethylenically unsaturated bonds as diisopropenyl groups, such as 1,3-diisopropenylbenzene and 1,4-diisopropenylbenzene; and diene compounds having two or more ethylenically unsaturated bonds, such as 1,5-hexadiene, 1,9-decadiene, and dicyclopentadiene.
Among these, from the viewpoints of compatibility with other resins, dielectric properties, low thermal expansion and heat resistance, a polymer having two or more ethylenically unsaturated bonds as a vinyl group is preferred, polybutadiene having two or more 1,2-vinyl groups and butadiene-styrene copolymer having two or more 1,2-vinyl groups are more preferred, and polybutadiene having two or more 1,2-vinyl groups is even more preferred.
In this specification, the term "polybutadiene" refers to a butadiene homopolymer. In other words, the component (C) is preferably a butadiene homopolymer having two or more 1,2-vinyl groups.
The component (C) may be used alone or in combination of two or more types.

When component (C) is a polybutadiene having two or more 1,2-vinyl groups, the content of structural units having a 1,2-vinyl structure relative to all structural units derived from butadiene constituting the polybutadiene [hereinafter sometimes abbreviated as vinyl group content] is preferably 50 mol% or more, more preferably 60 mol% or more, even more preferably 70 mol% or more, particularly preferably 80 mol% or more, and most preferably 85 mol% or more. From the same viewpoint, it is preferable that the polybutadiene having two or more 1,2-vinyl groups is a 1,2-polybutadiene homopolymer.

The number average molecular weight of a polymer having two or more ethylenically unsaturated bonds, preferably a polybutadiene having two or more 1,2-vinyl groups, is preferably 500 to 10,000, more preferably 800 to 5,000, and even more preferably 1,000 to 3,500, from the viewpoints of compatibility with other resins, dielectric properties, low thermal expansion, and heat resistance. Also, from the viewpoint of compatibility, it may be 3,000 or less, or may be 2,500 or less. The number average molecular weight of a polymer having two or more ethylenically unsaturated bonds can be measured by the method described in the Examples.

In the resin composition of this embodiment, there is no particular restriction on the content of component (C), but from the viewpoint of obtaining excellent heat resistance and from the viewpoint of dielectric properties in the high frequency band of 10 GHz or more, the content is preferably 5 to 60 parts by mass, more preferably 7 to 40 parts by mass, even more preferably 10 to 30 parts by mass, and particularly preferably 13 to 20 parts by mass, per 100 parts by mass of the total of the resin components in the resin composition.

<Other ingredients>
The resin composition of this embodiment may further contain other components. Examples of other components include one or more selected from a styrene-based thermoplastic elastomer (D) [hereinafter, sometimes abbreviated as the (D) component. ], an inorganic filler (E) [hereinafter, sometimes abbreviated as the (E) component. ], a curing accelerator (F) [hereinafter, sometimes abbreviated as the (F) component. ], and a flame retardant (G) [hereinafter, sometimes abbreviated as the (G) component. ]. By including these, it is possible to further improve the various properties when the laminate is formed. However, the resin composition of this embodiment may not include one or more selected from the (D), (E), (F) and (G) components depending on the desired performance.
These components are described in detail below.

（式中、Ｒ^ｄ１は水素原子又は炭素数１～５のアルキル基であり、Ｒ^ｄ２は、炭素数１～５のアルキル基である。ｋは、０～５の整数である。） (Styrene-based thermoplastic elastomer (D))
By including the styrene-based thermoplastic elastomer (D) in the resin composition of the present embodiment, the dielectric properties in the high frequency band of 10 GHz or more, moldability, adhesion to a conductor, solder heat resistance, glass transition temperature, thermal expansion coefficient, and flame retardancy tend to be improved and these properties tend to be well-balanced.
The (D) component is not particularly limited as long as it is a thermoplastic elastomer having a structural unit derived from a styrene-based compound represented by the following general formula (d-1) (see below), and may be a thermoplastic elastomer having a structural unit derived from styrene (R ^d1 = hydrogen atom, k = 0).

(In the formula, R ^d1 is a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, R ^d2 is an alkyl group having 1 to 5 carbon atoms, and k is an integer of 0 to 5.)

Examples of the alkyl group having 1 to 5 carbon atoms represented by R ^d1 and R ^d2 include a methyl group, an ethyl group, and an n-propyl group, and may be an alkyl group having 1 to 3 carbon atoms or a methyl group.
k may be an integer of 0 to 2, or may be 0 or 1, or may be 0.

Examples of structural units contained in the component (D) other than those derived from styrene-based compounds include structural units derived from butadiene, structural units derived from isoprene, structural units derived from maleic acid, and structural units derived from maleic anhydride.
The component (D) may be used alone or in combination of two or more types.
The butadiene-derived structural unit and the isoprene-derived structural unit may be hydrogenated. When hydrogenated, the butadiene-derived structural unit is a structural unit having a mixture of ethylene units and butylene units, and the isoprene-derived structural unit is a structural unit having a mixture of ethylene units and propylene units.

As component (D), from the viewpoints of dielectric properties in the high frequency band of 10 GHz or more, adhesion to conductors, heat resistance, glass transition temperature and thermal expansion coefficient, one or more types selected from the group consisting of hydrogenated styrene-butadiene-styrene block copolymers (SEBS, SBBS), hydrogenated styrene-isoprene-styrene block copolymers (SEPS) and styrene-maleic anhydride copolymers (SMA) are preferred, one or more types selected from the group consisting of hydrogenated styrene-butadiene-styrene block copolymers (SEBS) and hydrogenated styrene-isoprene-styrene block copolymers (SEPS) are more preferred, and hydrogenated styrene-butadiene-styrene block copolymers (SEBS) are even more preferred.

In the above SEBS, the content of structural units derived from styrene [hereinafter sometimes abbreviated as styrene content] is preferably 5 to 80 mass%, more preferably 10 to 75 mass%, further preferably 15 to 70 mass%, and particularly preferably 20 to 50 mass%, from the viewpoints of dielectric characteristics in a high frequency band of 10 GHz or more, adhesion to a conductor, heat resistance, glass transition temperature, and thermal expansion coefficient. The melt flow rate (MFR) of the SEBS is not particularly limited, but may be 0.1 to 20 g/10 min or 0.5 to 15 g/10 min under measurement conditions of 230° C. and a load of 2.16 kgf (21.2 N).
Examples of commercially available SEBS products include the Tuftec (registered trademark) H series and M series manufactured by Asahi Kasei Corporation, the Septon (registered trademark) series manufactured by Kuraray Co., Ltd., and the Kraton (registered trademark) G Polymer series manufactured by Kraton Polymer Japan, Ltd.

There are no particular restrictions on the weight average molecular weight (Mw) of component (D), but it is preferably 12,000 to 1,000,000, more preferably 30,000 to 500,000, even more preferably 50,000 to 120,000, and particularly preferably 70,000 to 100,000. The weight average molecular weight (Mw) is measured in terms of polystyrene by gel permeation chromatography (GPC).

When the resin composition of this embodiment contains the (D) component, the content of the (D) component is not particularly limited, but from the viewpoint of the dielectric characteristics, adhesion to the conductor, heat resistance, glass transition temperature, and thermal expansion coefficient in the high frequency band of 10 GHz or more, the content is preferably 5 to 60 parts by mass, more preferably 10 to 55 parts by mass, even more preferably 15 to 50 parts by mass, particularly preferably 20 to 45 parts by mass, and most preferably 25 to 40 parts by mass, relative to 100 parts by mass of the total of the (A) to (D) components. When the content of the (D) component is 5 parts by mass or more, the dielectric characteristics and moisture absorption resistance in the high frequency band of 10 GHz or more tend to be better, and when it is 60 parts by mass or less, the heat resistance, moldability, processability, and flame retardancy tend to be better.

(Inorganic filler (E))
By including the inorganic filler (E) in the resin composition of the present embodiment, it is possible to improve the low thermal expansion coefficient, high elastic modulus, heat resistance, and flame retardancy.
The (E) component is not particularly limited, and examples thereof include silica, alumina, titanium oxide, mica, beryllia, barium titanate, potassium titanate, strontium titanate, calcium titanate, aluminum carbonate, magnesium hydroxide, aluminum hydroxide, aluminum silicate, calcium carbonate, calcium silicate, magnesium silicate, silicon nitride, boron nitride, clay (calcined clay, etc.), talc, aluminum borate, and silicon carbide. These may be used alone or in combination of two or more. Among these, silica, alumina, mica, and talc are preferred from the viewpoints of thermal expansion coefficient, elastic modulus, heat resistance, and flame retardancy, and silica and alumina are more preferred, and silica is even more preferred. Examples of silica include precipitated silica produced by a wet method and having a high water content, and dry method silica produced by a dry method and containing almost no bound water, and dry method silica further includes crushed silica, fumed silica, and fused silica (fused spherical silica) depending on the difference in production method.
There is also no particular restriction on the shape and particle size of the inorganic filler (E). For example, the particle size is preferably 0.01 to 20 μm, more preferably 0.1 to 10 μm. Here, the particle size refers to the average particle size, and is the particle size at the point corresponding to 50% volume when the cumulative frequency distribution curve of the particle size is calculated with the total volume of the particles being 100%. The particle size of the inorganic filler (E) can be measured by a particle size distribution measuring device using a laser diffraction scattering method.

When the resin composition of this embodiment contains component (E), the content of component (E) in the resin composition is not particularly limited, but from the viewpoints of thermal expansion coefficient, elastic modulus, heat resistance, and flame retardancy, the content is preferably 5 to 70 parts by mass, more preferably 15 to 65 parts by mass, even more preferably 20 to 60 parts by mass, particularly preferably 30 to 55 parts by mass, and most preferably 40 to 50 parts by mass per 100 parts by mass of the total resin components in the resin composition.

In addition, when the (E) component is used, a coupling agent may be used in combination as necessary for the purpose of improving the dispersibility of the (E) component and the adhesion between the (E) component and the organic component in the resin composition. The coupling agent is not particularly limited, and for example, a silane coupling agent or a titanate coupling agent may be appropriately selected and used. The coupling agent may be used alone or in combination of two or more types. The amount of the coupling agent used is also not particularly limited, and may be, for example, 0.1 to 5 parts by mass or 0.5 to 3 parts by mass relative to 100 parts by mass of the (E) component. Within this range, there is little deterioration in various properties, and the above-mentioned features of the (E) component tend to be effectively exhibited.
When a coupling agent is used, the so-called integral blending method may be used in which the coupling agent is added after the component (E) is blended into the resin composition, but it is preferable to use an inorganic filler that has been surface-treated in advance with a coupling agent by a dry or wet method. By adopting this method, the characteristics of the component (E) can be more effectively expressed.

When the (E) component is used in this embodiment, in order to improve the dispersibility of the (E) component in the resin composition, the (E) component may be used as a slurry in which it is dispersed in an organic solvent in advance, as necessary. The organic solvent used to make the (E) component into a slurry is not particularly limited, but for example, the organic solvents exemplified in the manufacturing process of the (A1) component described above can be applied. These may be used alone or in combination of two or more. Among these, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone are preferred from the viewpoint of dispersibility. The solid content (non-volatile content) concentration of the slurry is not particularly limited, but may be, for example, 50 to 80% by mass, or 60 to 80% by mass, from the viewpoint of sedimentation and dispersibility of the inorganic filler (E).

(Cure Accelerator (F))
By including the curing accelerator (F) in the resin composition of the present embodiment, the curability of the resin composition is improved, and the dielectric properties, heat resistance, adhesion to a conductor, elastic modulus, and glass transition temperature in a high frequency band of 10 GHz or more tend to be improved.
Examples of the component (F) include acid catalysts such as p-toluenesulfonic acid; amine compounds such as triethylamine, pyridine, and tributylamine; imidazole compounds such as methylimidazole, phenylimidazole, and isocyanate-masked imidazole (for example, an addition reaction product of hexamethylene diisocyanate resin and 2-ethyl-4-methylimidazole); tertiary amine compounds; quaternary ammonium compounds; phosphorus compounds such as triphenylphosphine; organic peroxides such as dicumyl peroxide, 2,5-dimethyl-2,5-bis(t-butylperoxy)hexyne-3, 2,5-dimethyl-2,5-bis(t-butylperoxy)hexane, t-butylperoxyisopropyl monocarbonate, and α,α'-bis(t-butylperoxy)diisopropylbenzene; and carboxylates such as manganese, cobalt, and zinc. These may be used alone or in combination of two or more. Among these, from the viewpoints of heat resistance, glass transition temperature, and storage stability, imidazole compounds, organic peroxides, and carboxylates may be used, and from the viewpoints of heat resistance, glass transition temperature, elastic modulus, and thermal expansion coefficient, imidazole compounds may be used in combination with organic peroxides or carboxylates. Among organic peroxides, α,α'-bis(t-butylperoxy)diisopropylbenzene may be selected, and among carboxylates, manganese naphthenate may be selected.

When the resin composition of this embodiment contains the (F) component, the content of the (F) component is not particularly limited, but is, for example, preferably 0.01 to 10 parts by mass, more preferably 0.05 to 8 parts by mass, even more preferably 0.1 to 6 parts by mass, and particularly preferably 0.5 to 5 parts by mass, per 100 parts by mass of the total of the resin components in the resin composition. When the content of the (F) component is within the above range, better heat resistance and storage stability tend to be obtained.

(Flame Retardant (G))
By including the flame retardant (G) in the resin composition of this embodiment, the flame retardancy of the resin composition tends to be improved.
Examples of the (G) component include phosphorus-based flame retardants, metal hydrates, and halogen-based flame retardants. From the viewpoint of environmental issues, phosphorus-based flame retardants and metal hydrates are also acceptable. The flame retardant (G) may be used alone or in combination of two or more. Furthermore, a flame retardant assistant may be included as necessary.

- Phosphorus-based flame retardants -
The phosphorus-based flame retardant is not particularly limited as long as it contains phosphorus atoms among those generally used as flame retardants, and may be an inorganic phosphorus-based flame retardant or an organic phosphorus-based flame retardant. From the viewpoint of environmental issues, it is preferable that it does not contain halogen atoms. From the viewpoints of dielectric properties in a high frequency band of 10 GHz or more, adhesion to a conductor, heat resistance, glass transition temperature, thermal expansion coefficient, and flame retardancy, it may be an organic phosphorus-based flame retardant.
Examples of inorganic phosphorus-based flame retardants include red phosphorus; ammonium phosphates such as monoammonium phosphate, diammonium phosphate, triammonium phosphate, and ammonium polyphosphate; inorganic nitrogen-containing phosphorus compounds such as phosphoric acid amide; phosphoric acid; and phosphine oxide.
Examples of organic phosphorus-based flame retardants include aromatic phosphate esters, mono-substituted phosphonic acid diesters, di-substituted phosphinic acid esters, metal salts of di-substituted phosphinic acid, organic nitrogen-containing phosphorus compounds, and cyclic organic phosphorus compounds. Among these, aromatic phosphate ester compounds and metal salts of di-substituted phosphinic acid are preferred. Here, the metal salt may be any of lithium salts, sodium salts, potassium salts, calcium salts, magnesium salts, aluminum salts, titanium salts, and zinc salts, or may be aluminum salts. In addition, aromatic phosphate esters are preferred among organic phosphorus-based flame retardants.

Examples of aromatic phosphate esters include triphenyl phosphate, tricresyl phosphate, trixylenyl phosphate, cresyl diphenyl phosphate, cresyl di-2,6-xylenyl phosphate, resorcinol bis(diphenyl phosphate), 1,3-phenylene bis(di-2,6-xylenyl phosphate), bisphenol A bis(diphenyl phosphate), and 1,3-phenylene bis(diphenyl phosphate).
Examples of the mono-substituted phosphonic acid diester include divinyl phenylphosphonate, diallyl phenylphosphonate, and bis(1-butenyl) phenylphosphonate.
Examples of the disubstituted phosphinate include phenyl diphenylphosphinate and methyl diphenylphosphinate.
Examples of the metal salt of a disubstituted phosphinic acid include a metal salt of a dialkylphosphinic acid, a metal salt of a diallylphosphinic acid, a metal salt of a divinylphosphinic acid, a metal salt of a diarylphosphinic acid, etc. These metal salts may be any of lithium salts, sodium salts, potassium salts, calcium salts, magnesium salts, aluminum salts, titanium salts, and zinc salts, and an aluminum salt may be selected.
Examples of the organic nitrogen-containing phosphorus compound include phosphazene compounds such as bis(2-allylphenoxy)phosphazene and dicresylphosphazene; melamine phosphate; melamine pyrophosphate; melamine polyphosphate; and melam polyphosphate.
Examples of the cyclic organic phosphorus compound include 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, 10-(2,5-dihydroxyphenyl)-9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, and the like.
Among these, aromatic phosphate esters and disubstituted phosphines are preferred, and 1,3-phenylenebis(di-2,6-xylenyl phosphate) and aluminum salts of dialkylphosphinic acid are more preferred.

- Metal hydrates -
Examples of metal hydrates include aluminum hydroxide hydrates and magnesium hydroxide hydrates. These may be used alone or in combination of two or more. The metal hydroxides may also be inorganic fillers, but are classified as flame retardants when they are materials that can impart flame retardancy.
- Halogen-based flame retardants -
Examples of halogen-based flame retardants include chlorine-based flame retardants, bromine-based flame retardants, etc. Examples of chlorine-based flame retardants include chlorinated paraffin, etc.

When the resin composition of this embodiment contains component (G), and a phosphorus-based flame retardant is used as component (G), the content of the phosphorus-based flame retardant in the resin composition is not particularly limited, but is, for example, preferably 0.2 to 5 parts by mass, more preferably 0.3 to 4 parts by mass, and even more preferably 0.5 to 3 parts by mass, in terms of phosphorus atoms, per 100 parts by mass of the total of the resin components in the resin composition. When the content of phosphorus atoms is 0.2 parts by mass or more, better flame retardancy tends to be obtained, and when it is 5 parts by mass or less, better moldability, high adhesion to the conductor, excellent heat resistance, and high glass transition temperature tend to be obtained.

The resin composition of this embodiment may further contain, as necessary, resin materials such as thermoplastic resins and elastomers other than the above components, as well as coupling agents, antioxidants, heat stabilizers, antistatic agents, UV absorbers, pigments, colorants, flame retardant assistants, lubricants, etc., which are appropriately selected and contained. These may be used alone or in combination of two or more. The amounts of these used are not particularly limited, and may be used within a range that does not inhibit the effects of the present invention.

(Organic solvent)
The resin composition of the present embodiment may contain an organic solvent from the viewpoint of facilitating handling by dilution and from the viewpoint of facilitating production of a prepreg, which will be described later. A resin composition containing an organic solvent is generally referred to as a resin varnish or varnish.
The organic solvent is not particularly limited, but examples thereof include alcohol-based solvents such as ethanol, propanol, butanol, methyl cellosolve, butyl cellosolve, and propylene glycol monomethyl ether; ketone-based solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone; ether-based solvents such as tetrahydrofuran; aromatic solvents such as toluene, xylene, and mesitylene; nitrogen-containing solvents such as dimethylformamide, dimethylacetamide, and N-methylpyrrolidone; sulfur-containing solvents such as dimethyl sulfoxide; and ester-based solvents such as γ-butyrolactone.
Among these, from the viewpoint of solubility, alcohol solvents, ketone solvents, and nitrogen atom-containing solvents are preferred, ketone solvents are more preferred, acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone are further preferred, and methyl ethyl ketone is particularly preferred.
The organic solvent may be used alone or in combination of two or more kinds.

When the resin composition of this embodiment contains an organic solvent, the solid content concentration is, for example, 30 to 90% by mass, may be 35 to 80% by mass, or may be 40 to 60% by mass. By using a resin composition having a solid content concentration within the above range, the handling becomes easier, the impregnation into the substrate and the appearance of the produced prepreg are good, the solid content concentration of the resin in the prepreg described below is easily adjusted, and the production of a prepreg having a desired thickness tends to be easier.

The resin composition of this embodiment can be obtained by mixing the (A), (B), and (C) components, and other components used in combination as necessary, by a known method. At this time, each component may be dissolved or dispersed while stirring. The mixing order, temperature, time, and other conditions are not particularly limited and can be set as desired.

The resin composition of this embodiment has good compatibility and tends not to produce precipitates even if left for one day. In an embodiment with better compatibility, precipitates tend not to produce even if left for one week (although phase separation may occur), and in an embodiment with even better compatibility, phase separation tends not to occur even if left for one week.

The dielectric constant (Dk) at 10 GHz of the cured product of the resin composition of this embodiment (a laminate and a cured product of a resin film not including a fiber substrate such as glass cloth) is preferably 3.0 or less, more preferably 2.8 or less. The smaller the dielectric constant (Dk), the better, and there is no particular restriction on the lower limit, but in consideration of the balance with other physical properties, it may be, for example, 2.4 or more, or 2.6 or more.
The dielectric loss tangent (Df) at 10 GHz of the cured product of the resin composition of this embodiment (a laminate not including a fiber substrate such as glass cloth and a cured product of a resin film) is preferably 0.0055 or less, more preferably 0.0050 or less, even more preferably 0.0045 or less, particularly preferably 0.0035 or less, and most preferably 0.0030 or less. The smaller the dielectric loss tangent (Df), the better, and there is no particular restriction on the lower limit, but in consideration of the balance with other physical properties, it may be, for example, 0.0015 or more, 0.0020 or more, or 0.0023 or more.
The dielectric constant (Dk) and the dielectric loss tangent (Df) are values based on the cavity resonator perturbation method, and more specifically, are values measured by a method described in the Examples. In this specification, the term "dielectric constant" simply refers to the relative dielectric constant.

[Prepreg]
The present invention also provides a prepreg containing the resin composition of this embodiment and a sheet-like fiber reinforced substrate. The prepreg is formed using the resin composition of this embodiment and a sheet-like fiber reinforced substrate, and can be obtained, for example, by impregnating or coating the resin composition of this embodiment into a sheet-like fiber reinforced substrate and drying it. More specifically, for example, the prepreg of this embodiment can be produced by heating and drying for 1 to 30 minutes at a temperature of 80 to 200 ° C. in a drying oven and semi-curing (B-stage). The amount of the resin composition used can be determined so that the solid content concentration derived from the resin composition in the prepreg after drying is 30 to 90 mass%. By setting the solid content concentration in the above range, better moldability tends to be obtained when it is made into a laminate.

As the sheet-like fiber reinforcement substrate for the prepreg, known ones used in various laminates for electrical insulating materials are used. Examples of the material for the sheet-like reinforcement substrate include inorganic fibers such as E glass, D glass, S glass, and Q glass; organic fibers such as polyimide, polyester, and tetrafluoroethylene; and mixtures thereof. These sheet-like reinforcement substrates have shapes such as woven fabric, nonwoven fabric, roving, chopped strand mat, and surfacing mat. The thickness of the sheet-like fiber reinforcement substrate is not particularly limited, and for example, a thickness of 0.02 to 0.5 mm can be used. In addition, from the viewpoints of impregnation with the resin composition, heat resistance, moisture absorption resistance, and processability when made into a laminate, those that have been surface-treated with a coupling agent or the like, and those that have been mechanically opened can be used.

The resin composition can be impregnated or coated on the sheet-like reinforcing substrate by the following hot melt method or solvent method.
The hot melt method is a method in which the resin composition does not contain an organic solvent, and (1) the resin composition is first coated onto a coated paper having good peelability from the resin composition, and then the coated paper is laminated onto a sheet-like reinforcing substrate, or (2) the resin composition is directly coated onto a sheet-like reinforcing substrate using a die coater.
On the other hand, the solvent method is a method in which an organic solvent is added to a resin composition, a sheet-like reinforcing substrate is immersed in the obtained resin composition to impregnate the sheet-like reinforcing substrate with the resin composition, and then the substrate is dried.

[Resin film]
The present invention also provides a resin film containing the resin composition of the present embodiment. For example, the resin film can be produced by applying a resin composition containing an organic solvent, i.e., a resin varnish, to a support and drying it by heating. Examples of the support include polyolefin films such as polyethylene, polypropylene, and polyvinyl chloride; polyester films such as polyethylene terephthalate (hereinafter also referred to as "PET") and polyethylene naphthalate; and various plastic films such as polycarbonate films and polyimide films. In addition, metal foils such as copper foil and aluminum foil, release paper, and the like may be used as the support. The support may be subjected to a surface treatment such as a matte treatment or a corona treatment. In addition, the support may be subjected to a release treatment using a silicone resin-based release agent, an alkyd resin-based release agent, a fluororesin-based release agent, or the like.
The thickness of the support is not particularly limited, but is preferably 10 to 150 μm, and more preferably 25 to 50 μm.

There is no particular limitation on the method for applying the resin varnish to the support, and for example, a coating device known to those skilled in the art, such as a comma coater, a bar coater, a kiss coater, a roll coater, a gravure coater, a die coater, etc. These coating devices may be appropriately selected depending on the film thickness.
The drying temperature and drying time may be appropriately determined depending on the amount of organic solvent used, the boiling point of the organic solvent used, and the like. For example, in the case of a resin varnish containing about 40 to 60 mass % of an organic solvent, a resin film can be suitably formed by drying at 50 to 150° C. for about 3 to 10 minutes.

[Laminate]
It is also possible to manufacture a laminate containing the prepreg of this embodiment and a metal foil. Specifically, a laminate can be obtained by disposing a metal foil on one or both sides of a single prepreg of this embodiment, or disposing a metal foil on one or both sides of a prepreg obtained by stacking two or more prepregs of this embodiment, and then hot-pressing and molding the laminate. A laminate having a metal foil is sometimes called a metal-clad laminate.
The metal of the metal foil is not particularly limited as long as it is used in electrical insulating material applications. From the viewpoint of electrical conductivity, the metal may be copper, gold, silver, nickel, platinum, molybdenum, ruthenium, aluminum, tungsten, iron, titanium, chromium, or an alloy containing one or more of these metal elements, with copper and aluminum being preferred, and copper being more preferred.
The conditions for hot pressing are not particularly limited, but may be, for example, a temperature of 100 to 300° C., a pressure of 0.2 to 10 MPa, and a time of 0.1 to 5 hours. In addition, the hot pressing may be performed using a vacuum press or the like to maintain a vacuum state for 0.5 to 5 hours.

[Multilayer printed wiring board]
The multilayer printed wiring board of the present embodiment contains one or more selected from the group consisting of the prepreg of the present embodiment, the resin film of the present embodiment, and the laminate of the present embodiment. The multilayer printed wiring board of the present embodiment can be manufactured by performing a circuit formation process and a multilayer adhesion process by a known method, such as a hole drilling process, a metal plating process, and an etching process of a metal foil, using one or more selected from the group consisting of the prepreg of the present embodiment, the resin film of the present embodiment, and the laminate of the present embodiment.

The resin composition, prepreg, laminate, resin film, and multilayer printed wiring board of this embodiment can be suitably used in electronic devices that handle high-frequency signals of 10 GHz or more. In particular, the multilayer printed wiring board is useful as a multilayer printed wiring board for millimeter-wave radar.

Although preferred embodiments of the present invention have been described above, these are merely examples for the purpose of explaining the present invention, and are not intended to limit the scope of the present invention to these embodiments alone. The present invention can be implemented in various forms different from the above-described embodiments without departing from the spirit of the present invention.

The present invention will be specifically described below with reference to examples. However, the present invention is not limited to the following examples.

In each example, the number average molecular weight was measured by the following procedure.
(Method of measuring number average molecular weight)
The number average molecular weight was calculated by gel permeation chromatography (GPC) from a calibration curve using standard polystyrene. The calibration curve was approximated by a cubic equation using standard polystyrene: TSKstandard POLYSTYRENE (Type; A-2500, A-5000, F-1, F-2, F-4, F-10, F-20, F-40) [manufactured by Tosoh Corporation, product name]. The measurement conditions for GPC are shown below.
Device:
Pump: L-6200 type [manufactured by Hitachi High-Technologies Corporation]
Detector: L-3300 RI [manufactured by Hitachi High-Technologies Corporation]
Column oven: L-655A-52 [manufactured by Hitachi High-Technologies Corporation]
Column: Guard column: TSK Guardcolumn HHR-L + column: TSKgel G4000HHR + TSKgel G2000HHR (all product names manufactured by Tosoh Corporation)
Column size: 6.0 x 40 mm (guard column), 7.8 x 300 mm (column)
Eluent: Tetrahydrofuran Sample concentration: 30 mg/5 mL
Injection volume: 20 μL
Flow rate: 1.00 mL/min Measurement temperature: 40° C.

（式中、Ｘ^ａ２は２価の有機基であり、上記一般式（ａ１－５）中のＸ^ａ２と同様に説明される。） [Production Example A-1: Production of polyphenylene ether derivative (A-1)]
Toluene, polyphenylene ether "ZYLON (registered trademark) S203A" (product name, manufactured by Asahi Kasei Corporation, number average molecular weight = 12,000), and an allyl group-containing compound represented by the following general formula (1) [hereinafter, sometimes abbreviated as tetraallyl bisphenols] were charged into a 2 L glass flask equipped with a thermometer, a reflux condenser, and a stirrer, and dissolved with stirring at 90 to 100°C. The amount of toluene used was such that the reaction concentration became 35% by mass.

(In the formula, X ^a2 is a divalent organic group and is explained in the same manner as X ^a2 in the above general formula (a1-5).)

After visually confirming that the allyl group-containing compound had dissolved, t-butylperoxyisopropyl monocarbonate and manganese octylate were added, and the solution was subjected to a redistribution reaction at a solution temperature of 90 to 100° C. for 6 hours, and then cooled to 40° C. to obtain a polyphenylene ether derivative (A-1) having an allyl group at the molecular end. A small amount of this reaction solution was taken out and subjected to GPC measurement (polystyrene equivalent, eluent: tetrahydrofuran), whereby the double peak derived from tetraallyl bisphenols became a single peak, and the number average molecular weight of the polyphenylene ether compound was 4,200.
The amounts of each component used are shown in Table 1.

[Production Example A-2: Production of polyphenylene ether derivative (A-2)]
Toluene, polyphenylene ether "ZYLON (registered trademark) S202A" (product name, manufactured by Asahi Kasei Corporation, number average molecular weight = 16,000), and p-aminophenol were charged into a 2 L glass flask equipped with a thermometer, a reflux condenser, and a stirrer, and dissolved with stirring at 90° C. The amount of toluene used was such that the reaction concentration became 35% by mass.
After visually confirming that the solution had dissolved, t-butylperoxyisopropyl monocarbonate and manganese naphthenate were added, and the solution was subjected to a redistribution reaction at a temperature of 90° C. for 4 hours, and then cooled to 70° C. to obtain a polyphenylene ether derivative having a primary amino group at the molecular end. A small amount of this reaction solution was taken out and subjected to GPC measurement (polystyrene equivalent, eluent: tetrahydrofuran), and the peak derived from p-aminophenol disappeared, and the number average molecular weight of the polyphenylene ether compound was about 6,200. A small amount of the reaction solution was dropped into a methanol/benzene mixed solvent (mixing mass ratio = 1:1), and the solid matter purified by reprecipitation was subjected to FT-IR measurement, and the appearance of a peak derived from a primary amino group at around 3,400 cm ⁻¹ was confirmed.

Next, 2,2'-bis[4-(4-maleimidophenoxy)phenyl]propane and propylene glycol monomethyl ether (in an amount such that the reaction concentration became 30% by mass) were added to the reaction solution, and the liquid temperature was raised with stirring. The mixture was reacted for 4 hours while maintaining the temperature at 120°C, and then cooled and filtered through a 200 mesh filter to produce a polyphenylene ether derivative (A-2).
A small amount of this reaction solution was taken, and the solid matter was reprecipitated and purified in the same manner as above. The FT-IR measurement of the solid matter confirmed the disappearance of the peak derived from the primary amino group at about 3,500 cm ^-1 and the appearance of the carbonyl group at 1,700 to 1,730 cm ^-1 . In addition, when the solid matter was subjected to GPC (under the same conditions as above), the number average molecular weight was found to be about 6,500.
The amounts of each component used are shown in Table 1.

[Production Example B-1: Production of polyaminobismaleimide compound (B-1)]
Into a 1 L glass flask equipped with a thermometer, a reflux condenser, and a stirrer and capable of being heated and cooled, 2,2-bis[4-(4-maleimidophenoxy)phenyl]propane and 3,3'-dimethyl-5,5'-diethyl-4,4'-diphenylmethane bismaleimide as the maleimide compound (b1), and 4,4'-[1,3-phenylenebis(1-methylethylidene)]bisaniline and propylene glycol monomethyl ether as the diamine compound (b2) were charged, and the liquid temperature was kept at 120°C. The mixture was reacted for 3 hours with stirring, and then cooled and filtered through a 200 mesh filter to produce a polyamino bismaleimide compound (B-1) having a number average molecular weight of 800.
The amounts of each component used are shown in Table 2.

[Preparation of resin composition]
Examples 1 to 5, Comparative Example 1
Each component shown in Table 3 was stirred and mixed while heating at room temperature or 50 to 80°C in the amount (unit: parts by mass) shown in Table 3 to prepare a resin composition having a solids (non-volatile content) concentration of about 50% by mass.
The resin composition obtained in each example was applied to a PET film (manufactured by Teijin Limited, product name: G2-38) having a thickness of 38 μm, and then heated and dried at 170 ° C. for 5 minutes to produce a resin film in a B-stage state. This resin film was peeled off from the PET film and then crushed to produce a resin powder. Next, the above-mentioned resin powder was put into a Teflon (registered trademark) sheet cut into a size of 1 mm thickness × 50 mm length × 35 mm width, and low-profile copper foil (manufactured by Furukawa Electric Co., Ltd., product name: BF-ANP18) having a thickness of 18 μm was placed on the top and bottom of the Teflon (registered trademark) sheet so that the M side was in contact with the put-in resin powder, and the resin composition was cured by heating and pressing under conditions of a temperature of 230 ° C., a pressure of 2.0 MPa, and a time of 120 minutes to produce a resin plate with copper foil on both sides (resin plate thickness: 1 mm).

[Evaluation and measurement methods]
The resin compositions and resin plates obtained in the above Examples and Comparative Examples were subjected to the following measurements and evaluations. The results are shown in Table 3.

(1. Evaluation of Compatibility of Resin Compositions)
The resin compositions obtained in each example were visually observed and the compatibility (presence or absence of macroscopic phase separation and precipitates) was evaluated according to the following criteria.
A: Even after being left for one week or more, no macroscopic phase separation or precipitation occurred.
B: No change occurred after leaving for one day, but after leaving for three days or more, no precipitate was observed, but some macroscopic phase separation occurred.
C: When left for one day, no precipitate was formed, but macroscopic phase separation was observed.
D: After standing for 1 day, precipitation was observed.

(2. Evaluation of dielectric properties (dielectric constant and dielectric tangent) of resin plate)
The resin plate with copper foil on both sides obtained in each example was immersed in a 10 mass % solution of ammonium persulfate (manufactured by Mitsubishi Gas Chemical Company, Inc.) as a copper etching solution to remove the copper foil, and from this evaluation board, a 2 mm x 50 mm evaluation board was produced.
The dielectric constant (Dk) and dielectric loss tangent (Df) of the evaluation substrate were measured in the 10 GHz band in accordance with the cavity resonator perturbation method.

(3. Measurement Method of Thermal Expansion Coefficient and Glass Transition Temperature)
The thermal expansion coefficient (in the plate thickness direction, temperature range: 30 to 120°C) and the glass transition temperature (Tg) were measured using a 5 mm square test piece obtained by etching the copper foil on both sides of a double-sided copper foil-covered resin plate, using a thermomechanical analyzer (TMA) [model number Q400, manufactured by TA Instruments Japan, Inc.] in accordance with the IPC (The Institute for Interconnecting and Packaging Electronic Circuits) standard.

The materials in Table 3 are as follows.
[Component (A)]
Polyphenylene ether derivatives (A-1) and (A-2): The polyphenylene ether derivatives (A-1) and (A-2) produced in Production Examples A-1 and A-2 were used.

[Component (B)]
Polyaminobismaleimide compound (B-1): The polyaminobismaleimide compound (B-1) produced in Production Example B-1 was used.

[Component (C)]
Ricon 257: butadiene-styrene copolymer (manufactured by CRAY VALLEY, product name, mass ratio (butadiene/styrene): 65/35)
B-1000: 1,2-polybutadiene homopolymer, number average molecular weight = 1,200, vinyl group content = 85% or more (product name, manufactured by Nippon Soda Co., Ltd.)
B-2000: 1,2-polybutadiene homopolymer, number average molecular weight = 2,100, vinyl group content = 90% or more (product name, manufactured by Nippon Soda Co., Ltd.)
B-3000: 1,2-polybutadiene homopolymer, number average molecular weight = 3,200, vinyl group content = 90% or more (product name, manufactured by Nippon Soda Co., Ltd.)

[Component (D)]
Kraton (registered trademark) G1652: Hydrogenated styrene-based thermoplastic elastomer (SEBS), melt flow rate 5.0 g/10 min, styrene content 30%, hydrogenation rate 100% (manufactured by Kraton Polymer Japan Co., Ltd., product name)

[Component (E)]
Silica: spherical fused silica, average particle size = 0.5 μm

[Component (F)]
α,α'-bis(t-butylperoxy)diisopropylbenzene G-8009L: isocyanate masked imidazole (addition product of hexamethylene diisocyanate resin and 2-ethyl-4-methylimidazole) (trade name, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.)

[Component (G)]
OP-935: aluminum dialkylphosphinic acid salt, metal salt of disubstituted phosphinic acid, phosphorus content: 23.5% by mass (product name, manufactured by Clariant)
1,3-phenylenebis(di-2,6-xylenyl phosphate), phosphorus content: 9.0% by mass

As is clear from the results shown in Table 3, in Examples 1 to 5 of this embodiment, the compatibility of the resin compositions is good, and the cured products produced using these have excellent heat resistance and excellent dielectric properties in the high frequency band of 10 GHz.
On the other hand, in Comparative Example 1, the glass transition temperature is low and the dielectric properties in the high frequency band of 10 GHz are also insufficient.

The resin composition of the present invention has good compatibility, and laminates made from the resin composition have excellent heat resistance and dielectric properties, particularly in the high frequency band of 10 GHz or higher, and are therefore useful for multilayer printed wiring boards used in fifth-generation mobile communication system (5G) antennas that use radio waves in the frequency band above 6 GHz and millimeter-wave radars that use radio waves in the frequency band of 30 to 300 GHz.

Claims (15)

(A) a polyphenylene ether derivative having an ethylenically unsaturated bond-containing group;
(B) one or more compounds selected from the group consisting of maleimide compounds having two or more N-substituted maleimide groups and derivatives thereof;
(C) a crosslinking agent having two or more ethylenically unsaturated bonds;
A resin composition comprising:
the content of the (B) component is 10 to 90 parts by mass per 100 parts by mass of the total of the resin components in the resin composition,
A resin composition , wherein a content ratio of the component (A) to the component (B) [(A)/(B)] is 1/99 to 50/50 in terms of mass ratio . The resin composition according to claim 1, wherein the component (C) has two or more ethylenically unsaturated bonds as vinyl groups. The resin composition according to claim 2, wherein the component (C) is a polybutadiene having the two or more ethylenically unsaturated bonds as 1,2-vinyl groups. The resin composition according to claim 3, wherein the content of structural units having a 1,2-vinyl structure is 50 mol% or more relative to the total structural units derived from butadiene constituting the polybutadiene. The resin composition according to claim 3 or 4, wherein the number average molecular weight of the polybutadiene is 500 to 10,000. The resin composition according to any one of claims 1 to 5, wherein the content of the (C) component is 5 to 60 parts by mass per 100 parts by mass of the total of the resin components in the resin composition. The resin composition according to any one of claims 1 to 6, wherein the component (A) includes a structure represented by the following general formula (a1-1):

(In the formula, R ^a1 is an ethylenically unsaturated bond-containing group having 2 to 10 carbon atoms. n1 is 1 or 2, and n2 is 0 or 1. * indicates the bonding position to other structures.) The resin composition according to any one of claims 1 to 7, wherein the component (A) includes a structure represented by the following general formula (a1-2):

(In the formula, R ^a2 and R ^a3 each independently represent an ethylenically unsaturated bond-containing group having 2 to 10 carbon atoms. * indicates the bonding position to other structures.) The resin composition according to any one of claims 1 to 8, wherein the number of ethylenically unsaturated bond-containing groups in component (A) is 2 or more. The resin composition according to any one of claims 1 to 9, wherein the (B) component has a structural unit derived from a maleimide compound (b1) having two or more N-substituted maleimide groups and a structural unit derived from a diamine compound (b2). A prepreg containing the resin composition according to any one of claims 1 to 10. A laminate comprising the prepreg according to claim 11 and metal foil. A resin film containing the resin composition according to any one of claims 1 to 10. A multilayer printed wiring board comprising one or more members selected from the group consisting of the prepreg according to claim 11, the laminate according to claim 12, and the resin film according to claim 13. A multilayer printed wiring board for millimeter wave radar comprising one or more selected from the group consisting of the prepreg according to claim 11, the laminate according to claim 12, and the resin film according to claim 13.