JP2024070466A - Resin composition, prepreg, resin-coated film, resin-coated metal foil, metal-clad laminate, and wiring board - Google Patents

Abstract

[Problem] It is an object of the present invention to provide a resin composition which gives a cured product having a low dielectric constant and a low thermal expansion coefficient. Another object of the present invention is to provide a prepreg, a resin-attached film, a resin-attached metal foil, a metal-clad laminate, and a wiring board which are obtained using the resin composition. [Solution] A resin composition which contains a curable compound (A) containing at least one selected from the group consisting of maleimide compounds, benzoxazine compounds, and hydrocarbon-based compounds, and polysilsesquioxane particles (B), the polysilsesquioxane particles (B) having a predetermined amount of structural units represented by the following formula (1) in the molecule. [Chemical 1]JPEG2024070466000062.jpg3555In formula (1), R1 represents an alkyl group or an aryl group. [Selected Figure] None

Description

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

As the amount of information processed by various electronic devices increases, mounting technologies such as higher integration, higher density wiring, and multi-layering of the semiconductor devices mounted on them are rapidly developing. Furthermore, wiring boards used in various electronic devices are required to be high-frequency compatible wiring boards, such as millimeter wave radar boards for in-vehicle applications. Substrate materials for constituting the insulating layers of wiring boards used in various electronic devices are required to have low relative dielectric constants and dielectric dissipation factors in order to increase the signal transmission speed and reduce loss during signal transmission.

Examples of substrate materials with low relative dielectric constants and dielectric loss tangents include resin compositions containing curable compounds, and more specifically, the resin compositions described in Patent Document 1.

Patent Document 1 describes a polyphenylene ether resin composition containing an ethenylbenzylated polyphenylene ether having a number average molecular weight of 1,000 to 7,000 and a crosslinking curing agent. Patent Document 1 discloses that even if a polyphenylene ether having a small molecular weight is used, a polyphenylene ether resin composition can be obtained that can produce a laminate with high heat resistance without deteriorating the dielectric properties.

JP 2006-516297 A

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

In recent years, small portable devices such as mobile communication terminals and notebook PCs have been rapidly becoming more multifunctional, more powerful, thinner, and smaller. Accordingly, wiring boards used in these products are also required to have finer conductor wiring, more multi-layered conductor wiring layers, thinner, and higher performance in terms of mechanical properties. In particular, as wiring boards become thinner, there is a problem that semiconductor packages equipped with semiconductor chips on wiring boards warp, making mounting defects more likely to occur. In order to suppress warping of semiconductor packages equipped with semiconductor chips on wiring boards, the insulating layer is required to have a low thermal expansion coefficient (thermal expansion rate). Therefore, the substrate material for constituting the insulating layer of the wiring board is required to produce a cured product with a low thermal expansion coefficient. In addition, as wiring boards become thinner, the insulating layer constituting the wiring board is also required to have a low relative dielectric constant from the viewpoint of ease of impedance matching.

The present invention was made in consideration of the above circumstances, and aims to provide a resin composition that produces a cured product with a low dielectric constant and a low thermal expansion coefficient. The present invention also aims to provide a prepreg, a resin-coated film, a resin-coated metal foil, a metal-clad laminate, and a wiring board that are obtained using the resin composition.

After extensive investigation, the inventors have found that the above object can be achieved by the present invention.

A resin composition according to one embodiment of the present invention comprises a curable compound (A) containing at least one selected from the group consisting of maleimide compounds, benzoxazine compounds, and hydrocarbon compounds, and polysilsesquioxane particles (B), the polysilsesquioxane particles (B) having in their molecules a structural unit represented by the following formula (1) and at least one selected from the structural units represented by the following formulas (2) to (5), the ratio of the number of Si atoms contained in the structural unit represented by the following formula (1) in the polysilsesquioxane particles (B) to the total number of Si atoms contained in each of the structural units represented by the following formulas (1) to (5) in the polysilsesquioxane particles (B) being 70% or more and less than 100%, and the ratio of the total number of Si atoms contained in each of the structural units represented by the following formulas (2) to (4) in the polysilsesquioxane particles (B) to the total number of Si atoms contained in each of the structural units represented by the following formulas (1) to (5) in the polysilsesquioxane particles (B) being more than 0% and 20% or less.

In formula (1), R ₁ represents an alkyl group or an aryl group.

In formula (2), _R2 represents an alkyl group or an aryl group.

According to the present invention, it is possible to provide a resin composition that can produce a cured product having a low dielectric constant and a low thermal expansion coefficient. In addition, according to the present invention, there are provided a prepreg, a resin-coated film, a resin-coated metal foil, a metal-clad laminate, and a wiring board, which are obtained using the resin composition.

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

The following describes embodiments of the present invention, but the present invention is not limited to these.

[Resin composition]
A resin composition according to one embodiment of the present invention is a resin composition containing a curable compound (A) and polysilsesquioxane particles (B) described below.

(Curable Compound (A))
The curable compound (A) is not particularly limited as long as it is at least one selected from the group consisting of maleimide compounds (A1), benzoxazine compounds (A2), and hydrocarbon-based compounds (A3). The curable compound (A) may contain any one of the maleimide compounds (A1), benzoxazine compounds (A2), and hydrocarbon-based compounds (A3), or may contain two or more of them. In addition, the curable compound (A) may contain one of the maleimide compounds (A1), benzoxazine compounds (A2), and hydrocarbon-based compounds (A3), or may contain two or more of them.

(Maleimide compound (A1))
The maleimide compound (A1) is not particularly limited as long as it is a compound having a maleimide group in the molecule. The maleimide compound (A1) may be a monofunctional maleimide compound having one maleimide group in the molecule, a polyfunctional maleimide compound having two or more maleimide groups in the molecule, or a modified maleimide compound. The modified maleimide compound may be, for example, a modified maleimide compound in which a part of the molecule is modified with an amine compound, a modified maleimide compound in which a part of the molecule is modified with a silicone compound, or a modified maleimide compound in which a part of the molecule is modified with an amine compound and a silicone compound.

The maleimide compound (A1) may, for example, be a maleimide compound (A1-1) having an indane structure in the molecule. The indane structure may, for example, be a divalent group formed by removing two hydrogen atoms from indane or indane substituted with a substituent, and specifically may be a structure represented by the following formula (7). That is, the maleimide compound (A1-1) may, for example, be a maleimide compound having a structure represented by the following formula (7) in the molecule. The maleimide compound (A1-1) also has a maleimide group in the molecule.

In formula (7), Rb is independent. That is, each Rb may be the same group or different groups. For example, when r is 2 or 3, two or three Rb bonded to the same benzene ring may be the same group or different groups. Rb represents an alkyl group having 1 to 10 carbon atoms, an alkyloxy group (alkoxy group) having 1 to 10 carbon atoms, an alkylthio group having 1 to 10 carbon atoms, an aryl group having 6 to 10 carbon atoms, an aryloxy group having 6 to 10 carbon atoms, an arylthio group having 6 to 10 carbon atoms, a cycloalkyl group having 3 to 10 carbon atoms, a halogen atom, a hydroxyl group, or a mercapto group (thiol group). r represents 0 to 3.

Specific examples of the maleimide compound (A1-1) include maleimide compounds having a structure represented by the following formula (8) in the molecule.

In formula (8), each Ra is independent. That is, each Ra may be the same group or different groups. For example, when q is 2 to 4, the 2 to 4 Ras bonded to the same benzene ring may be the same group or different groups. Ra represents an alkyl group having 1 to 10 carbon atoms, an alkyloxy group having 1 to 10 carbon atoms, an alkylthio group having 1 to 10 carbon atoms, an aryl group having 6 to 10 carbon atoms, an aryloxy group having 6 to 10 carbon atoms, an arylthio group having 6 to 10 carbon atoms, a cycloalkyl group having 3 to 10 carbon atoms, a halogen atom, a nitro group, a hydroxyl group, or a mercapto group. Rb is the same as Rb in formula (7), and each independently represents an alkyl group having 1 to 10 carbon atoms, an alkyloxy group having 1 to 10 carbon atoms, an alkylthio group having 1 to 10 carbon atoms, an aryl group having 6 to 10 carbon atoms, an aryloxy group having 6 to 10 carbon atoms, an arylthio group having 6 to 10 carbon atoms, a cycloalkyl group having 3 to 10 carbon atoms, a halogen atom, a nitro group, a hydroxyl group, or a mercapto group. q represents 0 to 4. r represents 0 to 3. n represents 0.95 to 10.

r is the average value of the substitution degree of Rb, and is preferably small, specifically 0. That is, in the benzene ring to which Rb can be bonded, a hydrogen atom is preferably bonded to the position to which Rb can be bonded. The maleimide compound (A1-1) in which r is 0 is easy to synthesize. This is thought to be due to the fact that steric hindrance is reduced and the electron density of the aromatic ring is increased. In addition, when r is 1 to 3, Rb is preferably at least one selected from the group consisting of an alkyl group having 1 to 4 carbon atoms, a cycloalkyl group having 3 to 6 carbon atoms, and an aryl group having 6 to 10 carbon atoms, among the above. In addition, Ra is preferably at least one selected from the group consisting of an alkyl group having 1 to 4 carbon atoms, a cycloalkyl group having 3 to 6 carbon atoms, and an aryl group having 6 to 10 carbon atoms, among the above. By being an alkyl group having 1 to 4 carbon atoms, a cycloalkyl group having 3 to 6 carbon atoms, and an aryl group having 6 to 10 carbon atoms, it becomes easier to dissolve in a solvent and the decrease in the reactivity of the maleimide group can be suppressed, and a suitable cured product can be obtained. This is thought to be due to a decrease in planarity near the maleimide group and a decrease in crystallinity.

Specific examples of the groups represented by Ra and Rb include the following groups:

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

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

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

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

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

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

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

The halogen atom may be a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, or the like.

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

n is the average number of repetitions, and as described above, is 0.95 to 10, preferably 0.98 to 8, more preferably 1 to 7, and even more preferably 1.1 to 6. In the maleimide compound represented by formula (7) and the maleimide compound represented by formula (8), the content of the maleimide compound in which n, the average number of repetitions (degree of polymerization), is 0, is preferably 32 mass% or less relative to the total amount of the maleimide compound.

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

Specific examples of the maleimide compound (A1-1) include maleimide compounds represented by formulas (9) to (11).

In formula (9), n is 0.95 to 10.

In formula (10), n is 0.95 to 10.

In formula (11), n is 0.95 to 10.

The method for producing the maleimide compound (A1-1) is not particularly limited as long as it can produce the maleimide compound. Specifically, the maleimide compound is obtained by a so-called maleimide reaction in which an amine compound represented by the following formula (12) is reacted with maleic anhydride in an organic solvent such as toluene in the presence of a catalyst such as toluenesulfonic acid. More specifically, after the maleimide reaction, unreacted maleic anhydride and other impurities are removed by washing with water or the like, and the solvent is removed by reducing pressure. A dehydrating agent may be used during this reaction.

In formula (12), each Ra is independent. That is, each Ra may be the same group or different groups. For example, when q is 2 to 4, the 2 to 4 Ras bonded to the same benzene ring may be the same group or different groups. Ra represents an alkyl group having 1 to 10 carbon atoms, an alkyloxy group having 1 to 10 carbon atoms, an alkylthio group having 1 to 10 carbon atoms, an aryl group having 6 to 10 carbon atoms, an aryloxy group having 6 to 10 carbon atoms, an arylthio group having 6 to 10 carbon atoms, a cycloalkyl group having 3 to 10 carbon atoms, a halogen atom, a nitro group, a hydroxyl group, or a mercapto group. Rb is the same as Rb in formula (7), and each independently represents an alkyl group having 1 to 10 carbon atoms, an alkyloxy group having 1 to 10 carbon atoms, an alkylthio group having 1 to 10 carbon atoms, an aryl group having 6 to 10 carbon atoms, an aryloxy group having 6 to 10 carbon atoms, an arylthio group having 6 to 10 carbon atoms, a cycloalkyl group having 3 to 10 carbon atoms, a halogen atom, a nitro group, a hydroxyl group, or a mercapto group. q represents 0 to 4. r represents 0 to 3. n represents 0.95 to 10.

The amine compound represented by the formula (12) can be obtained, for example, by reacting 2,6-dimethylaniline with α,α'-dihydroxy-1,3-diisopropylbenzene in an organic solvent such as xylene using activated clay as a catalyst.

The maleimide compound (A1) is not limited to the maleimide compound (A1-1), and may be a maleimide compound (A1-2) other than the maleimide compound (A1-1). Examples of the maleimide compound (A1-2) other than the maleimide compound (A1-1) include a maleimide compound having a maleimide group in the molecule and not having an indane structure in the molecule. Examples of the maleimide compound (A1-2) include a maleimide compound having one or more maleimide groups in the molecule, and a modified maleimide compound. The maleimide compound (A1-2) is not particularly limited as long as it is a maleimide compound having one or more maleimide groups in the molecule and not having an indane structure in the molecule. Specific examples of the maleimide compound (A1-2) include phenylmaleimide compounds such as 4,4'-diphenylmethane bismaleimide, polyphenylmethane maleimide, m-phenylene bismaleimide, bisphenol A diphenyl ether bismaleimide, 3,3'-dimethyl-5,5'-diethyl-4,4'-diphenylmethane bismaleimide, 4-methyl-1,3-phenylene bismaleimide, and biphenyl aralkyl-type polymaleimide compounds, and N-alkyl bismaleimide compounds having an aliphatic skeleton, etc. Examples of the modified maleimide compound include modified maleimide compounds in which a part of the molecule is modified with an amine compound, modified maleimide compounds in which a part of the molecule is modified with a silicone compound, etc. As the maleimide compound different from the maleimide compound, a commercially available product can be used, for example, the solid content of MIR-3000-70MT and the solid content of MIR-5000-60T manufactured by Nippon Kayaku Co., Ltd., BMI-4000 and BMI-5100 manufactured by Daiwa Kasei Kogyo Co., Ltd., and BMI-689, BMI-1500, BMI-3000J, and BMI-5000 manufactured by Designer Molecules Inc. may be used.

(Benzoxazine compound (A2))
The benzoxazine compound (A2) is not particularly limited as long as it is a compound having a benzoxazine group in the molecule. The benzoxazine compound (A2) may be, for example, a benzoxazine resin. As the benzoxazine compound (A2), a commercially available product may be used, for example, JBZ-OP100D manufactured by JFE Chemical Corporation, ODA-BOZ manufactured by JFE Chemical Corporation, P-d manufactured by Shikoku Chemical Industry Co., Ltd., F-a manufactured by Shikoku Chemical Industry Co., Ltd., ALP-d manufactured by Shikoku Chemical Industry Co., Ltd., and HFB2006M manufactured by Showa Polymer Co., Ltd. may be used.

(Hydrocarbon Compound (A3))
The hydrocarbon compound (A3) is not particularly limited as long as it is a thermosetting hydrocarbon compound. Examples of the hydrocarbon compound (A3) include a hydrocarbon compound represented by the following formula (6).

In formula (6), X represents a hydrocarbon group having 6 or more carbon atoms, including at least one selected from an aromatic cyclic group and an aliphatic cyclic group. n represents 1 to 10.

The aromatic cyclic group is not particularly limited, but examples thereof include a phenylene group, a xylylene group, a naphthylene group, a tolylene group, and a biphenylene group. The aliphatic cyclic group is not particularly limited, but examples thereof include a group containing an indane structure and a group containing a cycloolefin structure. Among these, X is preferably an aromatic cyclic group, and more preferably a xylylene group. The number of carbon atoms in the hydrocarbon group is not particularly limited as long as it is 6 or more, but is preferably 6 to 20.

More specifically, examples of the hydrocarbon-based compound represented by the formula (6) include the hydrocarbon-based compound represented by the following formula (13). In addition, it is preferable that the hydrocarbon-based compound (A3) contains a hydrocarbon-based compound represented by the following formula (13).

In formula (13), n is an integer from 1 to 10.

Examples of the hydrocarbon-based compound (A3) include aromatic polymers having structural units derived from bifunctional aromatic compounds, such as divinyl aromatic compounds, in which two carbon-carbon unsaturated double bonds are bonded to an aromatic ring. The structural units derived from the bifunctional aromatic compounds are structural units obtained by polymerizing the bifunctional aromatic compounds. Examples of the bifunctional aromatic compounds include divinylbenzenes such as m-divinylbenzene and p-divinylbenzene, and more preferably p-divinylbenzene. The aromatic polymer may have not only structural units derived from the bifunctional aromatic compounds, but also other structural units. Examples of the other structural units include structural units derived from monofunctional aromatic compounds, such as monovinyl aromatic compounds, in which one carbon-carbon unsaturated double bond is bonded to an aromatic ring. Examples of the monovinyl aromatic compounds include ethylvinyl aromatic compounds. The structural units derived from the monofunctional aromatic compounds are structural units obtained by polymerizing the monofunctional aromatic compounds. The aromatic polymer has not only the structural unit derived from the bifunctional aromatic compound, but also other structural units, and is a copolymer of the structural unit derived from the bifunctional aromatic compound and other structural units such as the structural unit derived from the monofunctional aromatic compound. This copolymer may be a block copolymer or a random copolymer. As described above, examples of the hydrocarbon-based compound (A3) include the aromatic polymer, and among them, for example, a polyfunctional vinyl aromatic copolymer is mentioned. For example, the polyfunctional vinyl aromatic copolymer includes a copolymer having a repeating unit (a) derived from a divinyl aromatic compound and a repeating unit (b) derived from a monovinyl aromatic compound. The content of the repeating unit (a) and the repeating unit (b) in the polyfunctional vinyl aromatic copolymer is not particularly limited, but when the sum of the repeating unit (a) and the repeating unit (b) is taken as 100 mol%, it is preferable that the repeating unit (a) is contained in an amount of 2 mol% or more and less than 95 mol%, and the repeating unit (b) is contained in an amount of 5 mol% or more and less than 98 mol%. The molecular weight of the polyfunctional vinyl aromatic copolymer is not particularly limited, but is preferably, for example, a number average molecular weight (Mn) of 300 to 10,000. Examples of the polyfunctional vinyl aromatic copolymer include the polyfunctional vinyl aromatic copolymer described in JP 2018-168347 A. The hydrocarbon-based compound (A3) preferably contains at least one of the polyfunctional vinyl aromatic copolymer and the hydrocarbon-based compound represented by formula (6).

(Polysilsesquioxane Particles (B))
The polysilsesquioxane particles (B) have a structural unit ( ^T3 structure) represented by the following formula (1) and at least one selected from the group consisting of structural units represented by the following formulas (2) to (5) [a structural unit ( ^T2 structure) represented by the following formula (2), a structural unit ( ^Q2 structure) represented by the following formula (3), a structural unit ( ^Q3 structure) represented by the following formula (4), and a structural unit ( ^Q4 structure) represented by the following formula (5)] in the molecule.

In the polysilsesquioxane particles (B), the ratio of the number of Si atoms contained in the structural unit represented by the following formula (1) to the total number of Si atoms contained in each of the structural units represented by the following formulas (1) to (5) in the polysilsesquioxane particles (B) is 70% or more and less than 100%. That is, the ratio [ ^T3 /(T3+T2+Q2+Q3+Q4)] of the number of Si atoms contained in the ^T3 structure to the total number of Si atoms contained in each of the ^T3 structure, the ^{T2 structure} , the ^{Q2 structure ,} the ^{Q3 structure} , and the ^Q4 structure is ⁷⁰ % or more and less than 100%.

In the polysilsesquioxane particles (B), the ratio of the total number of Si atoms contained in each of the structural units represented by the following formulas (2) to (4) to the total number of Si atoms contained in each of the structural units represented by the following formulas (1) to (5) is more than 0% and not more than 20%. That is, the ratio of the total number of Si atoms contained in each of the ^T2 structure, the ^Q2 structure, and the ^Q3 structure to the total number of Si atoms contained in each of the ^T3 structure, the ^T2 structure, the ^Q2 structure, the ^Q3 structure, and the ^Q4 structure [( ^T2 + ^Q2 + ^Q3 )/( ^T3 + ^T2 + ^Q2 + ^Q3 + ^Q4 )] is more than 0% and not more than 20%.

The polysilsesquioxane particles (B) are not particularly limited as long as they have a structural unit represented by the following formula (1) in the molecule so as to be in the above ratio, and further have at least one selected from the structural units represented by the following formulas (2) to (5) in the molecule so as to be in the above ratio. That is, in the polysilsesquioxane particles (B), the ^T3 structure is in the molecule, and as long as any of the ^T2 structure, the ^Q2 structure, the ^Q3 structure, and the ^Q4 structure is in the molecule so as to be in the above ratio, the ^T2 structure, the ^Q2 structure, the ^Q3 structure, and the ^Q4 structure may be in the molecule without being present. In addition, the polysilsesquioxane particles (B) may have a structure other than these structures as long as they have the ^T3 structure, the ^T2 structure, the ^Q2 structure, the ^Q3 structure, and the ^Q4 structure in the molecule so as to be in the above ratio.

In formula (1), R ₁ represents an alkyl group or an aryl group.

In formula (2), _R2 represents an alkyl group or an aryl group.

The alkyl group is not particularly limited, and is preferably an alkyl group having 1 to 30 carbon atoms, and more preferably an alkyl group having 1 to 18 carbon atoms. Examples of the alkyl group include a methyl group, an ethyl group, a propyl group, a hexyl group, and a decyl group, and among these, a methyl group is preferred. The aryl group is not particularly limited, and is preferably an aryl group having 6 to 10 carbon atoms. Examples of the aryl group include a phenyl group and a naphthyl group, and among these, a phenyl group is preferred. The R ₁ and R ₂ are preferably the alkyl group, and more preferably a methyl group. The R ₁ and R ₂ may be any of these groups alone, or two or more of them may be combined.

In the polysilsesquioxane particles (B), the ratio [ ^T3 /(T3 ^{+T2+Q2+Q3+Q4)] of the number of Si atoms contained in the T3 structure to the total number of Si atoms contained in each of the T3 structure, the T2 structure , the Q2 structure ,} the ^Q3 structure ^, and ^{the Q4} structure is, as described above, 70% or more and less than 100%, preferably 80% or more and less than 100%, and more preferably 86% or more and less than 100%. In the polysilsesquioxane particles (B), the more the ^T3 structure, the lower the relative dielectric constant and the lower the thermal expansion coefficient of the cured resin composition obtained when cured, which is preferable. This is because the more the ^T3 structure, the fewer the number of hydroxyl groups contained in the polysilsesquioxane particles (B), and therefore the lower the relative dielectric constant and the lower the thermal expansion coefficient of the cured product. Therefore, when the ratio [ ^T3 /( ^T3 + ^T2 + ^Q2 + ^Q3 + ^Q4 )] is within the above range, the resulting cured resin composition tends to have a low dielectric constant and a low thermal expansion coefficient. However, in reality, the polysilsesquioxane particles (B) also have structures other than the ^T3 structure, such as the ^T2 structure, the ^Q2 structure, the ^Q3 structure, and the ^Q4 structure, in the molecule.

In the polysilsesquioxane particles (B), the ratio [( ^{T2 +} Q2 ^{+ Q3} ) / (T3 ^{+ T2 +} Q2 + Q3 + Q4)] of the total number of Si atoms contained in each of the ^{T2 structure, the Q2 structure} , and the ^Q3 structure to the total ^number of Si atoms contained in each of the T3 structure, the ^T2 structure, ^{the Q2} structure ^, the ^Q3 structure, and ^{the Q4 structure is} , as described above, more than 0% and 20% or less, preferably more than 0% and ¹⁵ % or less, and more preferably more than 0% and 10% or less. In the polysilsesquioxane particles (B), the smaller the ^T2 structure, the ^Q2 structure, and the ^Q3 structure, the more the ^T3 structure becomes relatively more, and when cured, a resin composition having a low dielectric constant and a low thermal expansion coefficient is obtained, which is preferable. This is because of the same reason as described above, that is, the more the ^T3 structure, the fewer the number of hydroxyl groups contained in the polysilsesquioxane particles (B), and the cured product has a low dielectric constant and a low thermal expansion coefficient. Therefore, if the ratio [( ^T2 + ^Q2 + ^Q3 )/( ^T3 + ^T2 + ^Q2 + ^Q3 + ^Q4 )] is within the above range, the cured product of the obtained resin composition tends to have a low dielectric constant and a low thermal expansion coefficient.

The method of measuring the ratio [( ^T3 /( ^T3 + ^T2 + ^Q2 + ^Q3 + ^Q4 )] and the ratio [( ^T2 + ^Q2 + ^Q3 )/( ^T3 + ^T2 + ^Q2 + ^Q3 + ^Q4 )] is not particularly limited as long as these ratios can be obtained. For example, a method of calculating the ratio of the Si atoms contained in each of the ^T3 structure, the ^T2 structure, the ^Q2 structure, the ^Q3 structure, and the ^Q4 structure as a ratio to the total number of Si atoms contained in each of the ^T3 structure, the ^T2 structure ^, the ^Q2 structure, the Q3 structure, and the ^Q4 structure from each of the obtained ratios can be used. That is, ^T3 /( ^T3 + ^T2 + ^Q2 + ^Q3 + ^Q4 ), ^T2 /( ^T3 + ^T2 + ^Q2 + ^Q3 + ^Q4 ), ^Q2 /( ^T3 + ^T2 + ^Q2 + ^Q3 + ^Q4 ), ^Q3 /( ^T3 + ^T2 + ^Q2 + ^Q3 + ^Q4 ), and ^Q4 /( ^T3 + ^T2 + ^Q2 + ^Q3 + ^Q4 ) are each measured by a method capable of calculating the ratios from the obtained ratios.

First, a spectrum of silica is obtained by solid-state ²⁹ Si-NMR measurement by the dipolar decoupling (DD) method. In the obtained solid-state ²⁹ Si-NMR spectrum of silica, a spectrum having peaks derived from the Si atoms contained in each of the T ³ structure, the T ² structure, the Q ² structure, the Q ³ structure, and the Q ⁴ structure is obtained. In addition, in the solid-state ²⁹ Si-NMR spectrum of silica, some peaks are in a state of overlapping. Then, when the solid-state ²⁹ Si-NMR spectrum of silica is obtained as a spectrum with overlapping peaks, waveform separation is performed on this spectrum. By doing so, each peak in the solid-state ²⁹ Si-NMR spectrum of silica is obtained. From the attribution of the obtained spectrum, it is possible to know which structure each obtained peak represents.

Then, each peak area (integral area) is obtained from each peak obtained. The peak area is obtained, for example, as follows. The peak area of the ^T3 structure is obtained by obtaining the area surrounded by the peak showing the ^T3 structure (for example, the area surrounded by the peak showing the ^T3 structure and the baseline or X-axis). The peak areas of other structures (the peak areas of the ^T2 structure, the ^Q2 structure, the ^Q3 structure, and the ^Q4 structure) are also obtained in the same manner as the peak area of the ^T3 structure. Then, the peak areas of the obtained ^T3 structure, the ^T2 structure, the ^Q2 structure, the ^Q3 structure, and the ^Q4 structure are defined as ^ST3 , ^ST2 , ^SQ2 , ^SQ3 , and ^SQ4 , and the ratios are calculated as follows.

For example, the ratio [ ^T3/ (T3 ⁺ T2+Q2+Q3+Q4)] of the number of Si atoms contained in the ^T3 structure to the total number of Si atoms contained in each of the ^T3 structure, the ^{T2 structure} , the ^{Q2 structure , the Q3} structure, and the ^Q4 structure is calculated as follows: The peak area ( ^ST3 ) of the ^T3 structure is divided by the sum of the peak areas of the ^T3 structure, the ^T2 structure, the ^Q2 structure, the ^Q3 structure, and the ^Q4 structure ( ^ST3 + ^ST2 + ^SQ2 + ^SQ3 + ^SQ4 ), to obtain the ratio [ ^T3 /( ^T3 + ^T2 + ^Q2 + ^Q3 + ^Q4 )]. That is, the ratio [ ^T3 /( ^T3 + ^T2 + ^Q2 + ^Q3 + ^Q4 )] can be calculated by ^ST3 /( ^ST3 + ^ST2 + ^SQ2 + ^SQ3 + ^SQ4 ) x 100(%).

The ratio [( ^T2 + ^Q2 +Q3)/(T3+T2+ ^{Q2+Q3+Q4)] of the total number of Si atoms contained in each of the T2 structure, the Q2 structure , and} the ^Q3 structure to the total number of Si atoms contained in each of the ^T3 structure, ^{the T2} structure, ^{the Q2 structure ,} the ^Q3 structure, and the ^Q4 structure is calculated as follows. The ratio ^[ ( ^T2 +Q2+ ^Q3 )/(T3+T2+ ^Q2 +Q3+ ^Q4 )] is obtained by dividing the sum of the peak areas of the ^T2 structure, ^{the Q2} structure, and the ^Q3 structure ( ^ST2 + ^SQ2 + ^SQ3 ) by the sum of the peak areas of the ^T3 structure, the ^T2 structure, the ^Q2 structure, ^{the Q3} structure, and ^{the Q4} structure ( ^ST3 + ^ST2 + ^SQ2 + ^SQ3 + ^SQ4 ). That is, the ratio [( ^T2 + ^Q2 + ^Q3 )/( ^T3 + ^T2 + ^Q2 + ^Q3 + ^Q4 )] can be calculated as ( ^ST2 + ^SQ2 + ^SQ3 )/( ^ST3 + ^ST2 + ^SQ2 + ^SQ3 + ^SQ4 )×100(%).

The structure of the polysilsesquioxane particles (B) is not particularly limited, and examples thereof include cage structures such as complete cage structures and incomplete cage structures such as partially cleaved cage structures, ladder structures, and random structures. The polysilsesquioxane particles (B) may contain any of these structures alone or in combination of two or more. In addition, it is preferable that the polysilsesquioxane particles (B) contain polysilsesquioxane of a random structure. Examples of the polysilsesquioxane particles (B) include polysilsesquioxane particles containing polysilsesquioxane of a random structure as a main component (e.g., more than 50 mass %) and polysilsesquioxane of another structure as a subcomponent (e.g., less than 50 mass %), and polysilsesquioxane particles made of polysilsesquioxane of a random structure.

The particle size of the polysilsesquioxane particles (B) is not particularly limited, but is preferably 0.01 to 10 μm, and more preferably 0.1 to 5 μm, in terms of volume average particle size. If the particle size of the polysilsesquioxane particles (B) is within the above range, a resin composition is obtained that, when cured, has a low relative dielectric constant and a low thermal expansion coefficient. The volume average particle size here can be calculated from the particle size distribution measured by a known method such as dynamic light scattering. For example, it can be measured using a particle size meter (Multisizer 3 manufactured by Beckman Coulter, Inc.).

The hydroxyl equivalent of the polysilsesquioxane particles (B) is not particularly limited, but is preferably, for example, 300 to 3000 g/eq, and more preferably 500 to 2500 g/eq. If the hydroxyl equivalent of the polysilsesquioxane particles (B) is within the above range, a resin composition can be obtained that, when cured, has a low relative dielectric constant and a low thermal expansion coefficient. The hydroxyl equivalent here can be determined, for example, from the product specification value.

The polysilsesquioxane particles (B) may be surface-treated polysilsesquioxane particles or may be non-surface-treated polysilsesquioxane particles. Examples of the surface treatment include treatment with a silane coupling agent.

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

The silane coupling agent has a vinyl group, and examples thereof include vinyltriethoxysilane and vinyltrimethoxysilane. The silane coupling agent has a styryl group, and examples thereof include p-styryltrimethoxysilane and p-styryltriethoxysilane. The silane coupling agent has a methacryloyl group, and examples thereof include 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropyltriethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, and 3-methacryloxypropylethyldiethoxysilane. The silane coupling agent has an acryloyl group, and examples thereof include 3-acryloxypropyltrimethoxysilane and 3-acryloxypropyltriethoxysilane. Examples of the silane coupling agent that has a phenylamino group include N-phenyl-3-aminopropyltrimethoxysilane and N-phenyl-3-aminopropyltriethoxysilane.

Examples of the polysilsesquioxane particles (B) include BQ1510-SB, BQ1510-SSB, and BQQ1510 manufactured by TAT.

(Reactive Compound (C))
The resin composition may contain a reactive compound (C) that reacts with the curable compound (A). The resin composition may not contain the reactive compound (C), but preferably contains the reactive compound (C).

The reactive compound (C) is not particularly limited as long as it is a reactive compound that reacts with the curable compound (A) and contributes to the curing of the resin composition. Here, the reactive compound (C) is a compound that reacts with the curable compound (A) and contributes to the curing of the resin composition, and is a compound different from the curable compound (A). Examples of the reactive compound (C) include polyphenylene ether compounds having carbon-carbon unsaturated double bonds in the molecule, epoxy compounds, methacrylate compounds, acrylate compounds, cyanate ester compounds, active ester compounds, allyl compounds, acenaphthylene compounds, and vinyl compounds.

The polyphenylene ether compound is not particularly limited as long as it is a polyphenylene ether compound having a carbon-carbon unsaturated double bond in the molecule. Examples of the polyphenylene ether compound include polyphenylene ether compounds having a carbon-carbon unsaturated double bond at the end, and more specifically, polyphenylene ether compounds having a substituent having a carbon-carbon unsaturated double bond at the molecular end, such as modified polyphenylene ether compounds whose ends are modified with a substituent having a carbon-carbon unsaturated double bond.

Examples of the substituent having a carbon-carbon unsaturated double bond include a group represented by the following formula (14) and a group represented by the following formula (15). That is, examples of the polyphenylene ether compound include a polyphenylene ether compound having at least one group selected from a group represented by the following formula (14) and a group represented by the following formula (15) in the molecule.

In formula (14), p represents 0 to 10. Ar represents an arylene group. R ₃ to R ₅ are each independent. That is, R ₃ to R ₅ may be the same group or different groups. R ₃ to R ₅ represent a hydrogen atom or an alkyl group. In addition, when p is 0 in formula (14), it indicates that Ar is directly bonded to the polyphenylene ether.

The arylene group is not particularly limited. Examples of the arylene group include monocyclic aromatic groups such as a phenylene group, and polycyclic aromatic groups such as a naphthalene ring. The arylene group also includes derivatives in which the hydrogen atom bonded to the aromatic ring is replaced with a functional group such as an alkenyl group, an alkynyl group, a formyl group, an alkylcarbonyl group, an alkenylcarbonyl group, or an alkynylcarbonyl group.

The alkyl group is not particularly limited, and is preferably an alkyl group having 1 to 18 carbon atoms, more preferably an alkyl group having 1 to 10 carbon atoms. Specific examples include a methyl group, an ethyl group, a propyl group, a hexyl group, and a decyl group.

In formula (15), _R6 represents a hydrogen atom or an alkyl group. The alkyl group is not particularly limited, and is preferably, for example, an alkyl group having 1 to 18 carbon atoms, and more preferably an alkyl group having 1 to 10 carbon atoms. Specific examples include a methyl group, an ethyl group, a propyl group, a hexyl group, and a decyl group.

Examples of the group represented by formula (14) include a vinylbenzyl group (ethenylbenzyl group) represented by the following formula (16). Examples of the group represented by formula (15) include an acryloyl group and a methacryloyl group.

Specific examples of the substituent include vinylbenzyl groups (ethenylbenzyl groups) such as o-ethenylbenzyl groups, m-ethenylbenzyl groups, and p-ethenylbenzyl groups, vinylphenyl groups, acryloyl groups, and methacryloyl groups. The polyphenylene ether compound may have one type of the substituent, or two or more types. The polyphenylene ether compound may have, for example, any one of o-ethenylbenzyl groups, m-ethenylbenzyl groups, and p-ethenylbenzyl groups, or may have two or three types of these.

The polyphenylene ether compound has a polyphenylene ether chain in the molecule, and preferably has, for example, a repeating unit represented by the following formula (17) in the molecule.

In formula (17), t represents 1 to 50. R ₇ to R ₁₀ are each independent. That is, R ₇ to R ₁₀ may be the same group or different groups. R ₇ to R ₁₀ represent a hydrogen atom, an alkyl group, an alkenyl group, an alkynyl group, a formyl group, an alkylcarbonyl group, an alkenylcarbonyl group, or an alkynylcarbonyl group. Among these, a hydrogen atom and an alkyl group are preferred.

Specific examples of the functional groups mentioned for R ₇ to R ₁₀ include the following.

The alkyl group is not particularly limited, but for example, an alkyl group having 1 to 18 carbon atoms is preferable, and an alkyl group having 1 to 10 carbon atoms is more preferable. Specific examples include a methyl group, an ethyl group, a propyl group, a hexyl group, and a decyl group.

The alkenyl group is not particularly limited, but is preferably an alkenyl group having 2 to 18 carbon atoms, more preferably an alkenyl group having 2 to 10 carbon atoms. Specific examples include a vinyl group, an allyl group, and a 3-butenyl group.

The alkynyl group is not particularly limited, but for example, an alkynyl group having 2 to 18 carbon atoms is preferable, and an alkynyl group having 2 to 10 carbon atoms is more preferable. Specific examples include an ethynyl group and a prop-2-yn-1-yl group (propargyl group).

The alkylcarbonyl group is not particularly limited as long as it is a carbonyl group substituted with an alkyl group, but for example, an alkylcarbonyl group having 2 to 18 carbon atoms is preferable, and an alkylcarbonyl group having 2 to 10 carbon atoms is more preferable. Specific examples include an acetyl group, a propionyl group, a butyryl group, an isobutyryl group, a pivaloyl group, a hexanoyl group, an octanoyl group, and a cyclohexylcarbonyl group.

The alkenylcarbonyl group is not particularly limited as long as it is a carbonyl group substituted with an alkenyl group, but for example, an alkenylcarbonyl group having 3 to 18 carbon atoms is preferable, and an alkenylcarbonyl group having 3 to 10 carbon atoms is more preferable. Specific examples include an acryloyl group, a methacryloyl group, and a crotonoyl group.

The alkynylcarbonyl group is not particularly limited as long as it is a carbonyl group substituted with an alkynyl group, but for example, an alkynylcarbonyl group having 3 to 18 carbon atoms is preferable, and an alkynylcarbonyl group having 3 to 10 carbon atoms is more preferable. Specific examples include a propioloyl group.

The weight average molecular weight (Mw) and number average molecular weight (Mn) of the polyphenylene ether compound are not particularly limited, and are preferably 500 to 5000, more preferably 800 to 4000, and even more preferably 1000 to 3000. The weight average molecular weight and number average molecular weight may be measured by a general molecular weight measurement method, and specifically, may be a value measured using gel permeation chromatography (GPC). In addition, when the polyphenylene ether compound has a repeating unit represented by the formula (17) in the molecule, t is preferably a value such that the weight average molecular weight and number average molecular weight of the polyphenylene ether compound are within such ranges. Specifically, t is preferably 1 to 50.

When the weight average molecular weight and number average molecular weight of the polyphenylene ether compound are within the above ranges, the compound has the excellent low dielectric properties of polyphenylene ether, and the cured product has excellent heat resistance and excellent moldability. This is believed to be due to the following. When the weight average molecular weight and number average molecular weight of a normal polyphenylene ether are within the above ranges, the compound has a relatively low molecular weight, so the heat resistance tends to decrease. In this regard, since the polyphenylene ether compound has one or more unsaturated double bonds at the end, it is believed that the cured product has sufficiently high heat resistance as the curing reaction progresses. In addition, when the weight average molecular weight and number average molecular weight of the polyphenylene ether compound are within the above ranges, the compound has a relatively low molecular weight, so it is believed that the compound has excellent moldability. Therefore, it is believed that such a polyphenylene ether compound not only has excellent heat resistance of the cured product, but also has excellent moldability.

The average number of the substituents (number of terminal functional groups) at the molecular end per molecule of the polyphenylene ether compound in the polyphenylene ether compound is not particularly limited. Specifically, it is preferably 1 to 5, more preferably 1 to 3, and even more preferably 1.5 to 3. If the number of terminal functional groups is too small, it tends to be difficult to obtain a cured product with sufficient heat resistance. In addition, if the number of terminal functional groups is too large, the reactivity becomes too high, and there is a risk of problems such as a decrease in the storage stability of the resin composition or a decrease in the fluidity of the resin composition. In other words, when such a polyphenylene ether compound is used, there is a risk of moldability problems such as molding defects such as the generation of voids during multilayer molding due to insufficient fluidity, making it difficult to obtain a highly reliable printed wiring board.

The number of terminal functional groups of a polyphenylene ether compound may be, for example, a numerical value representing the average number of the substituents per molecule of all polyphenylene ether compounds present in 1 mole of the polyphenylene ether compound. The number of terminal functional groups can be measured, for example, by measuring the number of hydroxyl groups remaining in the obtained polyphenylene ether compound and calculating the reduction from the number of hydroxyl groups of the polyphenylene ether before it has the substituents (before modification). The reduction from the number of hydroxyl groups of the polyphenylene ether before modification is the number of terminal functional groups. The number of hydroxyl groups remaining in the polyphenylene ether compound can be measured by adding a quaternary ammonium salt (tetraethylammonium hydroxide) that associates with hydroxyl groups to a solution of the polyphenylene ether compound and measuring the UV absorbance of the mixed solution.

The intrinsic viscosity of the polyphenylene ether compound is not particularly limited. Specifically, it may be 0.03 to 0.12 dl/g, but is preferably 0.04 to 0.11 dl/g, and more preferably 0.06 to 0.095 dl/g. If the intrinsic viscosity is too low, the molecular weight tends to be low, and it tends to be difficult to obtain low dielectric properties such as a low dielectric constant and a low dielectric loss tangent. If the intrinsic viscosity is too high, the viscosity is high, sufficient fluidity cannot be obtained, and the moldability of the cured product tends to decrease. Therefore, if the intrinsic viscosity of the polyphenylene ether compound is within the above range, excellent heat resistance and moldability of the cured product can be achieved.

The intrinsic viscosity here is the intrinsic viscosity measured in methylene chloride at 25°C, and more specifically, is the value measured, for example, with a viscometer for a 0.18 g/45 ml methylene chloride solution (liquid temperature 25°C). An example of such a viscometer is the AVS500 Visco System manufactured by Schott.

Examples of the polyphenylene ether compound include a polyphenylene ether compound represented by the following formula (18) and a polyphenylene ether compound represented by the following formula (19). As the polyphenylene ether compound, these polyphenylene ether compounds may be used alone or in combination of these two types of polyphenylene ether compounds.

In formula (18) and formula (19), R ₁₁ to R ₁₈ and R ₁₉ to R ₂₆ are each independent. That is, R ₁₁ to R ₁₈ and R _{19 to R 26 may be the same group or different groups. Furthermore, R 11 to R 18 and R 19 to R 26 represent a} hydrogen atom, an alkyl group, an alkenyl group, an alkynyl group, a formyl group, an alkylcarbonyl group, an alkenylcarbonyl group, or an alkynylcarbonyl group. X ₁ and X ₂ are each independent. That is, X ₁ and X ₂ may be the same group or different groups. X ₁ and X ₂ represent a substituent having a carbon-carbon unsaturated double bond. A and B represent repeating units represented by the following formula (20) and the following formula (21), respectively. Furthermore, in formula (19), Y represents a linear, branched, or cyclic hydrocarbon having 20 or less carbon atoms.

In formula (20) and formula (21), m and n each represent an integer of 0 to 20. R ₂₇ to R ₃₀ and R ₃₁ to R ₃₄ are each independent. That is, R ₂₇ to R ₃₀ and R ₃₁ to R ₃₄ may each represent the same group or different groups. Furthermore, R ₂₇ to R _{30 and R 31 to} R ₃₄ represent a hydrogen atom, an alkyl group, an alkenyl group, an alkynyl group, a formyl group, an alkylcarbonyl group, an alkenylcarbonyl group, or an alkynylcarbonyl group.

The polyphenylene ether compound represented by the formula (18) and the polyphenylene ether compound represented by the formula (19) are not particularly limited as long as they satisfy the above-mentioned constitution. Specifically, in the formula (18) and the formula (19), R ₁₁ to R ₁₈ and R ₁₉ to R ₂₆ are each independent as described above. That is, R ₁₁ to R ₁₈ and R ₁₉ to R ₂₆ may be the same group or different groups. In addition, R ₁₁ to R ₁₈ and R ₁₉ to R ₂₆ represent a hydrogen atom, an alkyl group, an alkenyl group, an alkynyl group, a formyl group, an alkylcarbonyl group, an alkenylcarbonyl group, or an alkynylcarbonyl group. Among these, a hydrogen atom and an alkyl group are preferred.

In formula (20) and formula (21), m and n each preferably represent 0 to 20 as described above. Moreover, m and n each preferably represent a numerical value such that the sum of m and n is 1 to 30. Therefore, it is more preferable that m represents 0 to 20, n represents 0 to 20, and the sum of m and n represents 1 to 30. Moreover, R ₂₇ to R ₃₀ and R ₃₁ to R ₃₄ are each independent. That is, R 27 to R 30 and R ₃₁ to R ₃₄ may each be the same group or different groups. Moreover, R ₂₇ to R ₃₀ and R ₃₁ to R ₃₄ represent a hydrogen atom, an alkyl group, an alkenyl group, an alkynyl group, a formyl group, an alkylcarbonyl group, _an alkenylcarbonyl group, or _an alkynylcarbonyl group. Among these, a hydrogen atom and an alkyl group are preferable.

R ₁₁ to R ₃₄ are the same as R ₇ to R ₁₀ in the above formula (17).

In the formula (19), Y is, as described above, a linear, branched, or cyclic hydrocarbon having 20 or less carbon atoms. Examples of Y include a group represented by the following formula (22).

In the formula (22), R ₃₅ and R ₃₆ each independently represent a hydrogen atom or an alkyl group. Examples of the alkyl group include a methyl group. Examples of the group represented by the formula (22) include a methylene group, a methylmethylene group, and a dimethylmethylene group, and among these, a dimethylmethylene group is preferred.

In the formula (18) and the formula (19), _X1 and _X2 are each independently a substituent having a carbon-carbon double bond. In the polyphenylene ether compound represented by the formula (18) and the polyphenylene ether compound represented by the formula (19), _X1 and _X2 may be the same group or different groups.

A more specific example of the polyphenylene ether compound represented by the formula (18) is, for example, a polyphenylene ether compound represented by the following formula (23):

More specific examples of the polyphenylene ether compound represented by the formula (19) include, for example, a polyphenylene ether compound represented by the following formula (24) and a polyphenylene ether compound represented by the following formula (25).

In the above formulas (23) to (25), m and n are the same as m and n in the above formulas (20) and (21). In addition, in the above formulas (23) and (24), R ₃ to R ₅ , p, and Ar are the same as R ₃ to R ₅ , p, and Ar in the above formula (14). In addition, in the above formulas (24) and (25), Y is the same as Y in the above formula (12). In addition, in the above formula (25), R ₆ is the same as R ₆ in the above formula (15).

The method for synthesizing the polyphenylene ether compound used in this embodiment is not particularly limited as long as it is possible to synthesize a polyphenylene ether compound having a carbon-carbon unsaturated double bond in the molecule. Specific examples of this method include a method in which polyphenylene ether is reacted with a compound in which a substituent having a carbon-carbon unsaturated double bond and a halogen atom are bonded.

Examples of the compound in which a substituent having a carbon-carbon unsaturated double bond is bonded to a halogen atom include compounds in which a substituent represented by the formulas (14) to (16) is bonded to a halogen atom. Specific examples of the halogen atom include a chlorine atom, a bromine atom, an iodine atom, and a fluorine atom, and among these, a chlorine atom is preferred. More specific examples of the compound in which a substituent having a carbon-carbon unsaturated double bond is bonded to a halogen atom include o-chloromethylstyrene, p-chloromethylstyrene, and m-chloromethylstyrene. The compound in which a substituent having a carbon-carbon unsaturated double bond is bonded to a halogen atom may be used alone or in combination of two or more. For example, o-chloromethylstyrene, p-chloromethylstyrene, and m-chloromethylstyrene may be used alone or in combination of two or three.

The raw material polyphenylene ether is not particularly limited as long as it can ultimately synthesize a desired polyphenylene ether compound. Specific examples include polyphenylene ethers composed of 2,6-dimethylphenol and at least one of a difunctional phenol and a trifunctional phenol, and those containing polyphenylene ether as the main component, such as poly(2,6-dimethyl-1,4-phenylene oxide). A bifunctional phenol is a phenolic compound having two phenolic hydroxyl groups in the molecule, such as tetramethylbisphenol A. A trifunctional phenol is a phenolic compound having three phenolic hydroxyl groups in the molecule.

The polyphenylene ether compound can be synthesized by the method described above. Specifically, the polyphenylene ether and the compound in which the substituent having a carbon-carbon unsaturated double bond and a halogen atom are bonded are dissolved in a solvent and stirred. By doing so, the polyphenylene ether reacts with the compound in which the substituent having a carbon-carbon unsaturated double bond and a halogen atom are bonded, and the polyphenylene ether compound used in this embodiment is obtained.

The reaction is preferably carried out in the presence of an alkali metal hydroxide. It is believed that the reaction proceeds favorably in this way. This is because the alkali metal hydroxide functions as a dehydrohalogenation agent, specifically, a dehydrochlorination agent. That is, it is believed that the alkali metal hydroxide removes hydrogen halide from the phenol group of the polyphenylene ether and the compound in which the substituent having the carbon-carbon unsaturated double bond is bonded to a halogen atom, and as a result, the substituent having the carbon-carbon unsaturated double bond is bonded to the oxygen atom of the phenol group instead of the hydrogen atom of the phenol group of the polyphenylene ether.

The alkali metal hydroxide is not particularly limited as long as it can act as a dehalogenating agent, but examples include sodium hydroxide. In addition, the alkali metal hydroxide is usually used in the form of an aqueous solution, specifically, as an aqueous sodium hydroxide solution.

The reaction conditions such as reaction time and reaction temperature vary depending on the compound in which the substituent having a carbon-carbon unsaturated double bond is bonded to a halogen atom, and are not particularly limited as long as the reaction proceeds favorably under the conditions. Specifically, the reaction temperature is preferably room temperature to 100°C, and more preferably 30 to 100°C. The reaction time is preferably 0.5 to 20 hours, and more preferably 0.5 to 10 hours.

The solvent used in the reaction is not particularly limited as long as it can dissolve the polyphenylene ether and the compound in which the substituent having a carbon-carbon unsaturated double bond is bonded to a halogen atom, and does not inhibit the reaction between the polyphenylene ether and the compound in which the substituent having a carbon-carbon unsaturated double bond is bonded to a halogen atom. Specific examples include toluene.

It is preferable that the above reaction is carried out in the presence of not only an alkali metal hydroxide but also a phase transfer catalyst. That is, it is preferable that the above reaction is carried out in the presence of an alkali metal hydroxide and a phase transfer catalyst. It is believed that the above reaction proceeds more smoothly by doing so. This is believed to be due to the following. It is believed that the phase transfer catalyst is a catalyst that has the function of incorporating an alkali metal hydroxide, is soluble in both a polar solvent phase such as water and a non-polar solvent phase such as an organic solvent, and can move between these phases. Specifically, when an aqueous solution of sodium hydroxide is used as the alkali metal hydroxide and an organic solvent such as toluene that is not compatible with water is used as the solvent, even if the aqueous solution of sodium hydroxide is dropped into the solvent being used for the reaction, the solvent and the aqueous solution of sodium hydroxide are separated, and it is believed that the sodium hydroxide is unlikely to move into the solvent. In that case, it is believed that the aqueous solution of sodium hydroxide added as the alkali metal hydroxide is unlikely to contribute to promoting the reaction. In contrast, when the reaction is carried out in the presence of an alkali metal hydroxide and a phase transfer catalyst, the alkali metal hydroxide is transferred to the solvent while being incorporated into the phase transfer catalyst, and the aqueous sodium hydroxide solution is thought to contribute more easily to promoting the reaction. Therefore, it is thought that the reaction proceeds more smoothly when the reaction is carried out in the presence of an alkali metal hydroxide and a phase transfer catalyst.

The phase transfer catalyst is not particularly limited, but examples include quaternary ammonium salts such as tetra-n-butylammonium bromide.

The polyphenylene ether compound contained in the resin composition preferably includes the polyphenylene ether compound obtained as described above.

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

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

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

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

The active ester compound is a compound having an ester group with high reactivity in the molecule, and examples thereof include benzene carboxylic acid active ester, benzene dicarboxylic acid active ester, benzene tricarboxylic acid active ester, benzene tetracarboxylic acid active ester, naphthalene carboxylic acid active ester, naphthalene dicarboxylic acid active ester, naphthalene tricarboxylic acid active ester, naphthalene tetracarboxylic acid active ester, fluorene carboxylic acid active ester, fluorene dicarboxylic acid active ester, fluorene tricarboxylic acid active ester, and fluorene tetracarboxylic acid active ester.

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

The acenaphthylene compound is a compound having an acenaphthylene structure in the molecule, and examples thereof include acenaphthylene, alkylacenaphthylenes, halogenated acenaphthylenes, and phenylacenaphthylenes. Examples of the alkylacenaphthylenes include 1-methylacenaphthylene, 3-methylacenaphthylene, 4-methylacenaphthylene, 5-methylacenaphthylene, 1-ethylacenaphthylene, 3-ethylacenaphthylene, 4-ethylacenaphthylene, and 5-ethylacenaphthylene. Examples of the halogenated acenaphthylenes include 1-chloroacenaphthylene, 3-chloroacenaphthylene, 4-chloroacenaphthylene, 5-chloroacenaphthylene, 1-bromoacenaphthylene, 3-bromoacenaphthylene, 4-bromoacenaphthylene, and 5-bromoacenaphthylene. Examples of the phenylacenaphthylenes include 1-phenylacenaphthylene, 3-phenylacenaphthylene, 4-phenylacenaphthylene, and 5-phenylacenaphthylene. The acenaphthylene compound may be a monofunctional acenaphthylene compound having one acenaphthylene structure in the molecule as described above, or a polyfunctional acenaphthylene compound having two or more acenaphthylene structures in the molecule.

The vinyl compound is a compound having a vinyl group in the molecule, and examples thereof include monofunctional vinyl compounds (monovinyl compounds) having one vinyl group in the molecule, and polyfunctional vinyl compounds having two or more vinyl groups in the molecule. Examples of the polyfunctional vinyl compounds include divinylbenzene, curable polybutadiene having a carbon-carbon unsaturated double bond in the molecule, and curable butadiene-styrene copolymer having a carbon-carbon unsaturated double bond in the molecule.

Among these, the reactive compound (C) is preferably a polyphenylene ether compound (a polyphenylene ether compound having a carbon-carbon unsaturated double bond in the molecule) and a triallyl isocyanurate compound such as triallyl isocyanurate (TAIC). The reactive compound (C) may be used alone or in combination of two or more kinds.

The weight average molecular weight of the reactive compound is not particularly limited, and is preferably 100 to 5000, more preferably 100 to 4000, and even more preferably 100 to 3000. If the weight average molecular weight of the reactive compound is too low, the reactive compound may be easily volatilized from the compounding components of the resin composition. If the weight average molecular weight of the reactive compound is too high, the viscosity of the varnish of the resin composition or the melt viscosity when the resin composition is in the B stage may become too high, which may cause deterioration in moldability and deterioration in appearance after molding. Therefore, if the weight average molecular weight of the reactive compound is within such a range, a resin composition having excellent heat resistance and moldability of the cured product can be obtained. This is thought to be because the resin composition can be cured suitably. Here, the weight average molecular weight may be measured by a general molecular weight measurement method, and specifically, a value measured using gel permeation chromatography (GPC) may be mentioned.

The average number of functional groups per molecule of the reactive compound that contribute to the reaction during curing of the resin composition (number of functional groups) varies depending on the weight average molecular weight of the reactive compound, but is preferably 1 to 20, and more preferably 2 to 18. If the number of functional groups is too small, it tends to be difficult to obtain sufficient heat resistance of the cured product. If the number of functional groups is too large, the reactivity becomes too high, and problems such as reduced storage stability and reduced fluidity of the resin composition may occur.

(Styrene-based elastomer (D))
The resin composition may contain a styrene-based elastomer (D) as necessary within a range that does not impair the effects of the present invention. The resin composition may not contain the styrene-based elastomer (D), but preferably contains the styrene-based elastomer (D).

The styrene-based elastomer (D) is not particularly limited, and examples thereof include elastomers containing a copolymer obtained by polymerizing a monomer containing a styrene-based monomer. The styrene-based elastomer (D) is a compound different from the hydrocarbon compound (A3). The styrene-based elastomer (D) is, for example, an elastomer containing a copolymer obtained by copolymerizing one or more of the styrene-based monomers and one or more other monomers copolymerizable with the styrene-based monomer. The copolymer constituting the styrene-based elastomer (D) may be a random copolymer, a block copolymer, an alternating copolymer, or a graft copolymer, so long as it has a structure derived from the styrene-based monomer in the molecule. Among these, the copolymer constituting the styrene-based elastomer (D) is preferably a block copolymer, that is, a styrene-based block copolymer. The styrene-based block copolymer is not particularly limited, and examples thereof include a block copolymer obtained by polymerizing a monomer containing a styrene-based monomer. That is, the styrene-based block copolymer is a block copolymer having at least the structure (repeating unit) derived from the styrene-based monomer in the molecule. The styrene-based block copolymer may be, for example, a block copolymer obtained by copolymerizing one or more of the styrene-based monomers with one or more of other monomers copolymerizable with the styrene-based monomer. As described above, the styrene-based block copolymer may be a block copolymer having at least the structure (repeating unit) derived from the styrene-based monomer in the molecule, and may be, for example, a binary copolymer, a ternary copolymer, or a quaternary or higher copolymer. The binary copolymer is a binary copolymer of the structure (repeating unit) derived from the styrene-based monomer and the structure (repeating unit) derived from the other copolymerizable monomer. Examples of the terpolymer include a terpolymer of the structure (repeating unit) derived from the styrene-based monomer, a structure (repeating unit) derived from the other copolymerizable monomer, and a structure (repeating unit) derived from the styrene-based monomer, and a terpolymer of the structure (repeating unit) derived from the other copolymerizable monomer, a structure (repeating unit) derived from the styrene-based monomer, and a structure (repeating unit) derived from the other copolymerizable monomer. The styrene-based copolymer may be a hydrogenated styrene-based copolymer obtained by hydrogenating the styrene-based copolymer. The styrene-based copolymer may be a hydrogenated styrene-based block copolymer obtained by hydrogenating the styrene-based block copolymer.

The styrene monomer is not particularly limited, but examples thereof include styrene, styrene derivatives, styrene in which some of the hydrogen atoms of the benzene ring are substituted with an alkyl group, styrene in which some of the hydrogen atoms of the vinyl group are substituted with an alkyl group, vinyltoluene, α-methylstyrene, butylstyrene, dimethylstyrene, and isopropenyltoluene. The styrene monomer may be used alone or in combination of two or more. The other copolymerizable monomer is not particularly limited, but examples thereof include olefins such as α-pinene, β-pinene, and dipentene, non-conjugated dienes such as 1,4-hexadiene and 3-methyl-1,4-hexadiene, and conjugated dienes such as 1,3-butadiene and 2-methyl-1,3-butadiene (isoprene). The other copolymerizable monomer may be used alone or in combination of two or more.

The styrene copolymer may be any of the conventionally known copolymers, and is not particularly limited. For example, the copolymer may be a copolymer (preferably a block copolymer) having a structural unit (structure derived from the styrene monomer) represented by the following formula (26) in the molecule.

In formula (26), R ₃₈ to R ₄₀ each independently represent a hydrogen atom or an alkyl group, and R ₄₁ represents any group selected from the group consisting of a hydrogen atom, an alkyl group, an alkenyl group, and an isopropenyl group. The alkyl group is not particularly limited, and is preferably an alkyl group having 1 to 18 carbon atoms, and more preferably an alkyl group having 1 to 10 carbon atoms. Specific examples include a methyl group, an ethyl group, a propyl group, a hexyl group, and a decyl group. The alkenyl group is preferably an alkenyl group having 1 to 10 carbon atoms.

The styrene-based copolymer preferably contains at least one structural unit represented by the formula (26), and may contain two or more different structural units in combination. The styrene-based copolymer may also contain a structure in which the structural unit represented by the formula (26) is repeated.

The styrene-based copolymer may have at least one of the structural units represented by the following formulas (27) to (29) as a structural unit derived from another monomer copolymerizable with the styrene-based monomer, in addition to the structural unit represented by the formula (26). The structural unit derived from the other monomer copolymerizable with the styrene-based monomer may contain a structure in which each of the structural units represented by the following formulas (27) to (29) is repeated.

In the formulas (27) to (29), R ₄₂ to R ₅₉ each independently represent any group selected from the group consisting of a hydrogen atom, an alkyl group, an alkenyl group, and an isopropenyl group. The alkyl group is not particularly limited, and is preferably, for example, an alkyl group having 1 to 18 carbon atoms, and more preferably, an alkyl group having 1 to 10 carbon atoms. Specific examples include a methyl group, an ethyl group, a propyl group, a hexyl group, and a decyl group. The alkenyl group is preferably an alkenyl group having 1 to 10 carbon atoms.

The styrene-based copolymer preferably contains at least one structural unit represented by the formulas (27) to (29), and may contain a combination of two or more different structural units. The styrene-based copolymer may also contain a structure in which the structural units represented by the formulas (27) to (29) are repeated.

Specific examples of the structural unit represented by formula (26) include structural units represented by the following formulas (30) to (32). The structural unit represented by formula (26) may also be a structure in which the structural units represented by the following formulas (30) to (32) are repeated. The structural unit represented by formula (26) may be one of these alone or a combination of two or more different types.

Specific examples of the structural unit represented by formula (27) include structural units represented by the following formulas (33) to (39). The structural unit represented by formula (27) may also be a structure in which the structural units represented by the following formulas (33) to (39) are repeated. The structural unit represented by formula (27) may be one of these alone or a combination of two or more different types.

More specifically, examples of the structural unit represented by the formula (28) include structural units represented by the following formulas (40) and (41). The structural unit represented by the formula (28) may also be a structure in which the structural units represented by the following formulas (40) and (41) are respectively repeated. The structural unit represented by the formula (28) may be one of these alone or a combination of two or more different types.

Specific examples of the structural unit represented by formula (29) include structural units represented by the following formulas (42) and (43). The structural unit represented by formula (29) may also be a structure in which the structural units represented by formulas (42) and (43) are repeated. The structural unit represented by formula (29) may be one of these alone or a combination of two or more different types.

Preferred examples of the styrene-based copolymer include copolymers obtained by copolymerizing one or more styrene-based monomers such as styrene, vinyltoluene, α-methylstyrene, isopropenyltoluene, divinylbenzene, and allylstyrene. More specifically, the styrene-based copolymer includes methylstyrene (ethylene/butylene) methylstyrene block copolymer, methylstyrene (ethylene-ethylene/propylene) methylstyrene block copolymer, styrene isoprene block copolymer, styrene isoprene styrene block copolymer, styrene (ethylene/butylene) styrene block copolymer, styrene (ethylene-ethylene/propylene) styrene block copolymer, styrene butadiene styrene block copolymer, styrene (butadiene/butylene) styrene block copolymer, and styrene isobutylene styrene block copolymer. The hydrogenated styrene-based copolymer includes, for example, the hydrogenated product of the styrene-based copolymer. More specifically, examples of the hydrogenated styrene copolymer include hydrogenated methylstyrene (ethylene/butylene) methylstyrene block copolymer, hydrogenated methylstyrene (ethylene-ethylene/propylene) methylstyrene block copolymer, hydrogenated styrene isoprene block copolymer, hydrogenated styrene isoprene styrene block copolymer, hydrogenated styrene (ethylene/butylene) styrene block copolymer, and hydrogenated styrene (ethylene-ethylene/propylene) styrene block copolymer.

The styrene copolymer may be used alone or in combination of two or more of the above exemplified styrene copolymers.

When the styrene-based copolymer contains at least one of the structural units represented by the formulas (30) to (32), the mass fraction (i.e., the content of structural units derived from styrene) is preferably about 10 to 60% of the total polymer, and more preferably about 20 to 40%. This has the advantage that excellent compatibility with the radical polymerizable compound is maintained, and superior dielectric properties are obtained when the resin composition is cured.

The weight average molecular weight of the styrene copolymer is preferably 10,000 to 200,000, and more preferably 50,000 to 180,000. If the molecular weight is too low, the glass transition temperature of the cured product of the resin composition tends to decrease, and the heat resistance tends to decrease. If the molecular weight is too high, the viscosity of the resin composition when made into a varnish or when heated and molded tends to become too high. If the molecular weight is within the above range, there is an advantage that it is possible to ensure appropriate resin fluidity in the resin composition or in the semi-cured state (B stage) of the resin composition. The weight average molecular weight may be measured by a general molecular weight measurement method, and specifically, a value measured using gel permeation chromatography (GPC) may be mentioned.

The styrene-based elastomer (D) is preferably a styrene-based copolymer having a hardness of 20 to 100, and more preferably a styrene-based copolymer having a hardness of 30 to 80. It is believed that by containing a styrene-based copolymer having a hardness within the above range, a resin composition can be obtained that, when cured, has lower dielectric properties such as a relative dielectric constant and a cured product with a low thermal expansion coefficient.

The hardness may be, for example, a durometer hardness, and more specifically, a durometer hardness measured using a type A durometer conforming to JIS K 6253.

As the styrene-based elastomer (D), commercially available products can be used, for example, Septon V9827, Septon V9461, Septon 1020, Septon 2002, Septon 2004F, Septon 2005, Septon 2006, Septon 2063, Septon 2104, Septon 4033, Septon 4044, Septon 4055, Septon 4077, manufactured by Kuraray Co., Ltd. SEPTON 4099, SEPTON 8004, SEPTON 8006, SEPTON 8007L, SEPTON HG252, HYBRAR 5125, HYBRAR 5127, HYBRAR 7125F, and HYBRAR 7311F, FTR2140, and FTR6125 manufactured by Mitsui Chemicals, Inc., DYNARON 1320P, DYNARON 1321P, and DYNARON 2324P manufactured by JSR Corporation, DYNARON 4600P, DYNARON 6200P, DYNARON 6201B, DYNARON 8600P, DYNARON 8300P, DYNARON 8903P, and DYNARON 9901P, and Tuftec H1221, Tuftec H1062, Tuftec H1521, Tuftec H1051, Tuftec H1517, Tuftec H1043, and Tuftec H1062 manufactured by Asahi Kasei Corporation. TUFTEC N504, TUFTEC H1272, TUFTEC M1943, TUFTEC M1911, TUFTEC M1913, TUFTEC MP10, TUFTEC P1083, TUFTEC P1500, TUFTEC P5051, and TUFTEC P2000, and SIBSTAR series 062M, 062T, 072T, 073T, 102T, and 103T manufactured by Kaneka Corporation may also be used.

(Inorganic filler (E))
The resin composition may contain, as necessary, an inorganic filler (E) other than the polysilsesquioxane particles (B) within a range that does not impair the effects of the present invention. Even if the polysilsesquioxane particles (B) act as a filler, the resin composition may contain an inorganic filler (E) other than the polysilsesquioxane particles (B).

The inorganic filler (E) is not particularly limited as long as it is an inorganic filler that can be used as an inorganic filler contained in the resin composition. Examples of the inorganic filler (E) include metal oxides such as silica, alumina, titanium oxide, magnesium oxide, and mica, metal hydroxides such as magnesium hydroxide and aluminum hydroxide, talc, aluminum borate, barium sulfate, aluminum nitride, boron nitride, barium titanate, magnesium carbonates such as anhydrous magnesium carbonate, and calcium carbonate. Among these, silica, metal hydroxides such as magnesium hydroxide and aluminum hydroxide, aluminum oxide, boron nitride, and barium titanate are preferred, and silica is more preferred. The silica is not particularly limited, and examples include crushed silica, spherical silica, and silica particles, and spherical silica is preferred. That is, in the resin composition, it is preferable to use the polysilsesquioxane particles (B) in combination with silica, and it is more preferable to use the polysilsesquioxane particles (B) in combination with spherical silica.

The inorganic filler (E) may be a surface-treated inorganic filler or may be an inorganic filler that has not been surface-treated. Examples of the surface treatment include treatment with a silane coupling agent. The silane coupling agent is not particularly limited, and examples thereof include the same silane coupling agent as the silane coupling agent that can be used for the surface treatment of the polysilsesquioxane particles (B).

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

(Content)
The content of the polysilsesquioxane particles (B) is preferably 10 to 200 parts by mass, more preferably 30 to 150 parts by mass, and even more preferably 50 to 120 parts by mass, relative to 100 parts by mass of the resin component. That is, the content of the polysilsesquioxane particles (B) is preferably 10 to 200 parts by mass, more preferably 30 to 150 parts by mass, and even more preferably 50 to 120 parts by mass, relative to 100 parts by mass in total of the curable compound (A), the reactive compound (C), and the styrene-based elastomer (D). More specifically, when the resin component contains the curable compound (A) and the reactive compound (C) and does not contain the styrene-based elastomer (D), the content of the polysilsesquioxane particles (B) is preferably 10 to 200 parts by mass, more preferably 30 to 150 parts by mass, and even more preferably 50 to 120 parts by mass, relative to 100 parts by mass of the total of the curable compound (A) and the reactive compound (C). Also, when the resin component contains the curable compound (A) but does not contain the reactive compound (C) and the styrene-based elastomer (D), the content of the polysilsesquioxane particles (B) is preferably 10 to 200 parts by mass, more preferably 30 to 150 parts by mass, and even more preferably 50 to 120 parts by mass, relative to 100 parts by mass of the curable compound (A). In addition, when the resin components include the curable compound (A), the reactive compound (C), and the styrene-based elastomer (D), the content of the polysilsesquioxane particles (B) is preferably within the above range, that is, 10 to 200 parts by mass, more preferably 30 to 150 parts by mass, and even more preferably 50 to 120 parts by mass, relative to a total of 100 parts by mass of the curable compound (A), the reactive compound (C), and the styrene-based elastomer (D). When the content of the polysilsesquioxane particles (B) is within the above range, the effect achieved by containing the polysilsesquioxane particles (B) can be fully exhibited, and a resin composition that becomes a cured product having a low relative dielectric constant and a low thermal expansion coefficient when cured can be more suitably obtained.

As described above, the resin composition may contain the reactive compound (C). When the resin composition contains the reactive compound (C), the content of the reactive compound (C) is preferably 10 to 40 parts by mass per 100 parts by mass of the curable compound (A) and the reactive compound (C) in total. In addition, the content of the curable compound (A) is preferably 50 to 90 parts by mass per 100 parts by mass of the curable compound (A) and the reactive compound (C) in total.

As described above, the resin composition may contain the styrene-based elastomer (D). When the resin composition contains the styrene-based elastomer (D), the content of the styrene-based elastomer (D) is preferably 10 to 60 parts by mass per 100 parts by mass of the resin component, i.e., 100 parts by mass in total of the curable compound (A), the reactive compound (C), and the styrene-based elastomer (D).

The resin composition may contain the inorganic filler (E) as described above. When the resin composition contains the inorganic filler (E), that is, when the polysilsesquioxane particles (B) and the inorganic filler (E) are used in combination, the content of the inorganic filler (E) is preferably 10 to 50 parts by mass per 100 parts by mass of the total of the polysilsesquioxane particles (B) and the inorganic filler (E).

(Other ingredients)
The resin composition may contain components (other components) other than the curable compound (A) and the polysilsesquioxane particles (B) within a range that does not impair the effects of the present invention. The resin composition may contain the reactive compound (C), the styrene-based elastomer (D), and the inorganic filler (E) as the other components, as described above. Examples of the other components include additives such as flame retardants, reaction initiators, reaction accelerators, catalysts, polymerization retarders, polymerization inhibitors, dispersants, leveling agents, coupling agents, defoamers, antioxidants, heat stabilizers, antistatic agents, ultraviolet absorbers, dyes and pigments, and lubricants, in addition to the reactive compound (C), the styrene-based elastomer (D), and the inorganic filler (E).

As described above, the resin composition according to the present embodiment may contain a flame retardant. By containing a flame retardant, the flame retardancy of the cured product of the resin composition can be increased. The flame retardant is not particularly limited. Specifically, in fields where halogen-based flame retardants such as bromine-based flame retardants are used, for example, ethylene dipentabromobenzene, ethylene bis tetrabromoimide, decabromodiphenyl oxide, tetradecabromodiphenoxybenzene, and bromostyrene compounds that react with the polymerizable compound, which have a melting point of 300°C or more, are preferred. It is believed that the use of a halogen-based flame retardant can suppress the detachment of halogen at high temperatures and suppress the decrease in heat resistance. In addition, in fields where halogen-free is required, a phosphorus-containing flame retardant (phosphorus-based flame retardant) may be used. The phosphorus-based flame retardant is not particularly limited, but examples thereof include phosphate ester flame retardants, phosphazene flame retardants, bisdiphenylphosphine oxide flame retardants, and phosphinate flame retardants. A specific example of a phosphate ester flame retardant is a condensed phosphate ester of dixylenyl phosphate. A specific example of a phosphazene flame retardant is phenoxyphosphazene. A specific example of a bisdiphenylphosphine oxide flame retardant is xylylenebisdiphenylphosphine oxide. A specific example of a phosphinate flame retardant is, for example, a metal phosphinate salt of an aluminum salt of dialkylphosphinic acid. As the flame retardant, each of the exemplified flame retardants may be used alone or in combination of two or more.

As described above, the resin composition according to the present embodiment may contain a reaction initiator. The reaction initiator is not particularly limited as long as it can promote the curing reaction of the resin composition, and examples thereof include peroxides and organic azo compounds. Examples of the peroxides include α,α'-bis(t-butylperoxy-m-isopropyl)benzene, 2,5-dimethyl-2,5-di(t-butylperoxy)-3-hexyne, and benzoyl peroxide. Examples of the organic azo compounds include azobisisobutyronitrile. If necessary, a carboxylate metal salt or the like can be used in combination. By doing so, the curing reaction can be further promoted. Among these, α,α'-bis(t-butylperoxy-m-isopropyl)benzene is preferably used. Since α,α'-bis(t-butylperoxy-m-isopropyl)benzene has a relatively high reaction initiation temperature, it is possible to suppress the promotion of the curing reaction at a time when curing is not necessary, such as when drying the prepreg, and to suppress the deterioration of the storage stability of the resin composition. Furthermore, α,α'-bis(t-butylperoxy-m-isopropyl)benzene has low volatility and does not volatilize during drying or storage of the prepreg, providing good stability. The reaction initiators may be used alone or in combination of two or more.

As described above, the resin composition according to the present embodiment may contain a silane coupling agent. The silane coupling agent may be contained in the resin composition, or may be contained in the inorganic filler contained in the resin composition as a silane coupling agent that has been surface-treated in advance. Among these, it is preferable that the silane coupling agent is contained in the inorganic filler as a silane coupling agent that has been surface-treated in advance, and it is more preferable that the silane coupling agent is contained in the inorganic filler as a silane coupling agent that has been surface-treated in advance, and further, that the silane coupling agent is also contained in the resin composition. In the case of a prepreg, the prepreg may contain the silane coupling agent that has been surface-treated in advance in a fibrous base material. Examples of the silane coupling agent include the same silane coupling agent as the silane coupling agent used when surface-treating the inorganic filler described above.

The resin composition according to this embodiment is a resin composition that produces a cured product with a low dielectric constant and a low thermal expansion coefficient.

(Application)
The resin composition is used in producing a prepreg as described below, and is also used in forming a resin layer provided in a resin-coated metal foil and a resin-coated film, and an insulating layer provided in a metal-clad laminate and a wiring board.

(Production method)
The method for producing the resin composition is not particularly limited, and examples thereof include a method in which the curable compound (A) and the polysilsesquioxane particles (B) are mixed to a predetermined content, etc. In addition, in the case of obtaining a varnish-like composition containing an organic solvent, the method described below, etc. can be used.

By using the resin composition according to this embodiment, it is possible to obtain prepregs, metal-clad laminates, wiring boards, resin-coated metal foils, and resin-coated films, as follows.

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

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

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

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

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

First, each component that is soluble in an organic solvent is added to the organic solvent and dissolved therein. At this time, heating may be performed as necessary. After that, components that are not soluble in the organic solvent are added as necessary, and the components are dispersed until a predetermined dispersion state is reached using a ball mill, a bead mill, a planetary mixer, a roll mill, or the like, to prepare a varnish-like resin composition. The organic solvent used here is not particularly limited as long as it dissolves the polyphenylene ether compound and the reactive compound and does not inhibit the curing reaction. Specific examples include toluene and methyl ethyl ketone (MEK).

Specific examples of the fibrous substrate include glass cloth, aramid cloth, polyester cloth, glass nonwoven fabric, aramid nonwoven fabric, polyester nonwoven fabric, pulp paper, and linter paper. When glass cloth is used, a laminate with excellent mechanical strength is obtained, and glass cloth that has been flattened is particularly preferable. Specific examples of the flattening process include a method in which glass cloth is continuously pressed with a press roll at an appropriate pressure to compress the yarn into a flat shape. The thickness of the fibrous substrate that is generally used is, for example, 0.01 mm or more and 0.3 mm or less. In addition, the glass fibers that constitute the glass cloth are not particularly limited, but examples include Q glass, NE glass, E glass, S glass, T glass, L glass, and L2 glass. In addition, the surface of the fibrous substrate may be surface-treated with a silane coupling agent. The silane coupling agent is not particularly limited, but examples thereof include silane coupling agents having at least one group selected from the group consisting of vinyl groups, acryloyl groups, methacryloyl groups, styryl groups, amino groups, and epoxy groups in the molecule.

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

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

The fibrous substrate 3 impregnated with the resin composition (resin varnish) 2 is heated under the desired heating conditions, for example, at 40°C to 180°C for 1 minute to 10 minutes. By heating, a prepreg 1 in an uncured (A stage) or semi-cured (B stage) state is obtained. In addition, by the heating, the organic solvent can be volatilized from the resin varnish, thereby reducing or removing the organic solvent.

The resin composition according to this embodiment is a resin composition that can give a cured product with a low dielectric constant and a low thermal expansion coefficient. That is, when the resin composition is cured, a cured product with a low dielectric constant and a low thermal expansion coefficient is obtained. Therefore, a prepreg including this resin composition or a semi-cured product of this resin composition is a prepreg that can give a cured product with a low dielectric constant and a low thermal expansion coefficient. This prepreg can be used to suitably manufacture a wiring board that has an insulating layer including a cured product with a low dielectric constant and a low thermal expansion coefficient.

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

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

The method for producing the metal-clad laminate 11 is not particularly limited as long as the metal-clad laminate 11 can be produced. Specifically, a method for producing the metal-clad laminate 11 using the prepreg 1 can be mentioned. This method includes a method in which one or more sheets of the prepreg 1 are stacked, and a metal foil 13 such as copper foil is stacked on both sides or one side of the prepreg 1, and the metal foil 13 and the prepreg 1 are heated and pressurized to laminate and integrate them, thereby producing a laminate 11 with metal foil on both sides or one side. That is, the metal-clad laminate 11 is obtained by stacking the metal foil 13 on the prepreg 1 and heating and pressurizing it. In addition, the conditions for the heating and pressing can be appropriately set depending on the thickness of the metal-clad laminate 11 and the type of resin composition contained in the prepreg 1. For example, the temperature can be 170 to 230°C, the pressure can be 2 to 4 MPa, and the time can be 60 to 150 minutes. The metal-clad laminate may also be produced without using a prepreg. For example, a method is available in which a varnish-like resin composition is applied onto a metal foil, a layer containing the resin composition is formed on the metal foil, and then the layer is heated and pressurized.

The resin composition according to the present embodiment is a resin composition that can produce a cured product with a low dielectric constant and a low thermal expansion coefficient. That is, when the resin composition is cured, a cured product with a low dielectric constant and a low thermal expansion coefficient is produced. Therefore, a metal-clad laminate having an insulating layer containing a cured product of this resin composition is a metal-clad laminate having an insulating layer containing a cured product with a low dielectric constant and a low thermal expansion coefficient. This metal-clad laminate can be used to suitably produce a wiring board having an insulating layer containing a cured product with a low dielectric constant and a low thermal expansion coefficient.

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

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

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

The resin composition according to this embodiment is a resin composition that can produce a cured product with a low dielectric constant and a low thermal expansion coefficient. That is, when the resin composition is cured, a cured product with a low dielectric constant and a low thermal expansion coefficient is obtained. Therefore, a wiring board having an insulating layer that includes a cured product of this resin composition is a wiring board having an insulating layer that includes a cured product with a low dielectric constant and a low thermal expansion coefficient.

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

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

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

As the metal foil, any metal foil used in metal-clad laminates or resin-coated metal foils can be used without limitation. Examples of the metal foil include copper foil and aluminum foil.

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

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

The resin composition according to the present embodiment is a resin composition that can provide a cured product with a low dielectric constant and a low thermal expansion coefficient. That is, when the resin composition is cured, a cured product with a low dielectric constant and a low thermal expansion coefficient is obtained. Therefore, a resin-attached metal foil having a resin layer containing this resin composition or a semi-cured product of this resin composition is a resin-attached metal foil having a resin layer that can provide an insulating layer containing a cured product with a low dielectric constant and a low thermal expansion coefficient. This resin-attached metal foil can be used when manufacturing a wiring board that has an insulating layer containing a cured product with a low dielectric constant and a low thermal expansion coefficient. For example, a multilayer wiring board can be manufactured by stacking it on a wiring board. A wiring board obtained using such a resin-attached metal foil can provide a wiring board that has an insulating layer containing a cured product with a low dielectric constant and a low thermal expansion coefficient.

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

As shown in FIG. 5, the resin-attached film 41 according to this embodiment includes a resin layer 42 containing the resin composition or a semi-cured product of the resin composition, and a support film 43. This resin-attached film 41 includes the resin layer 42 and a support film 43 laminated together with the resin layer 42. The resin-attached film 41 may also include other layers between the resin layer 42 and the support film 43.

The resin layer 42 may contain the semi-cured product of the resin composition as described above, or may contain the uncured resin composition. That is, the resin-attached film 41 may include a resin layer containing the semi-cured product of the resin composition (the resin composition in the B stage) and a support film, or may be a resin-attached film including a resin layer containing the resin composition before curing (the resin composition in the A stage) and a support film. The resin layer may contain the resin composition or the semi-cured product of the resin composition, and may or may not contain a fibrous substrate. The resin composition or the semi-cured product of the resin composition may be the resin composition that has been dried or heated. The fibrous substrate may be the same as the fibrous substrate of the prepreg.

The support film 43 can be any support film used for resin-attached films, without any restrictions. Examples of the support film include electrically insulating films such as polyester film, polyethylene terephthalate (PET) film, polyimide film, polyparabanic acid film, polyether ether ketone film, polyphenylene sulfide film, polyamide film, polycarbonate film, and polyarylate film.

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

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

The method for producing the resin-attached film 41 is not particularly limited as long as the resin-attached film 41 can be produced. Examples of the method for producing the resin-attached film 41 include a method of producing the film by applying the varnish-like resin composition (resin varnish) to the support film 43 and heating it. The varnish-like resin composition is applied to the support film 43 by using a bar coater, for example. The applied resin composition is heated, for example, at 40°C or higher and 180°C or lower, for 0.1 minutes or higher and 10 minutes or lower. The heated resin composition is formed on the support film 43 as an uncured resin layer 42. The organic solvent can be volatilized from the resin varnish by the heating, thereby reducing or removing the organic solvent.

The resin composition according to the present embodiment is a resin composition that can provide a cured product having a low dielectric constant and a low thermal expansion coefficient. That is, when the resin composition is cured, a cured product having a low dielectric constant and a low thermal expansion coefficient is obtained. Therefore, a resin-attached film having a resin layer containing this resin composition or a semi-cured product of this resin composition is a resin-attached film having a resin layer that can provide an insulating layer containing a cured product having a low dielectric constant and a low thermal expansion coefficient. This resin-attached film can be suitably used when manufacturing a wiring board having an insulating layer containing a cured product having a low dielectric constant and a low thermal expansion coefficient. For example, a multilayer wiring board can be manufactured by laminating the film on a wiring board and then peeling off the support film, or by laminating the film on a wiring board after peeling off the support film. A wiring board obtained using such a resin-attached film can provide a wiring board having an insulating layer containing a cured product having a low dielectric constant and a low thermal expansion coefficient.

As mentioned above, this specification discloses various aspects of the technology, the main technologies of which are summarized below.

The resin composition according to the first aspect includes at least one curable compound (A) selected from the group consisting of maleimide compounds, benzoxazine compounds, and hydrocarbon compounds, and polysilsesquioxane particles (B). The polysilsesquioxane particles (B) have in their molecules a structural unit represented by the following formula (1) and at least one selected from the structural units represented by the following formulas (2) to (5). In the polysilsesquioxane particles (B), the ratio of the number of Si atoms contained in the structural unit represented by the following formula (1) to the total number of Si atoms contained in each of the structural units represented by the following formulas (1) to (5) is 70% or more and less than 100%, and in the polysilsesquioxane particles (B), the ratio of the total number of Si atoms contained in each of the structural units represented by the following formulas (2) to (4) to the total number of Si atoms contained in each of the structural units represented by the following formulas (1) to (5) is more than 0% and less than 20%.

In formula (1), R ₁ represents an alkyl group or an aryl group.

In formula (2), _R2 represents an alkyl group or an aryl group.

The resin composition according to the second aspect is the resin composition according to the first aspect, in which the polysilsesquioxane particles (B) contain polysilsesquioxane having a random structure.

The resin composition according to the third aspect is the resin composition according to the first or second aspect, in which the hydrocarbon-based compound includes at least one of a polyfunctional vinyl aromatic copolymer and a hydrocarbon-based compound represented by the following formula (6):

In formula (6), X represents a hydrocarbon group having 6 or more carbon atoms, including at least one selected from an aromatic cyclic group and an aliphatic cyclic group, and n represents 1 to 10.

The resin composition according to the fourth aspect is the resin composition according to any one of the first to third aspects, further comprising a reactive compound (C) that reacts with the curable compound (A).

The resin composition according to the fifth aspect is the resin composition according to any one of the first to fourth aspects, in which the content of the polysilsesquioxane particles (B) is 10 to 200 parts by mass per 100 parts by mass of the resin component.

The prepreg according to the sixth aspect is a prepreg comprising a resin composition according to any one of the first to fifth aspects or a semi-cured product of the resin composition, and a fibrous base material.

The resin-attached film according to the seventh aspect is a resin-attached film comprising a resin layer containing the resin composition according to any one of the first to fifth aspects or a semi-cured product of the resin composition, and a support film.

The resin-coated metal foil according to the eighth aspect is a resin-coated metal foil comprising a resin layer containing the resin composition according to any one of the first to fifth aspects or a semi-cured product of the resin composition, and a metal foil.

The metal-clad laminate according to the ninth aspect is a metal-clad laminate comprising an insulating layer containing a cured product of the resin composition according to any one of the first to fifth aspects, and a metal foil.

The metal-clad laminate according to the tenth aspect is a metal-clad laminate having an insulating layer containing a cured product of the prepreg according to the sixth aspect and a metal foil.

The metal-clad laminate according to the eleventh aspect is a wiring board having an insulating layer including a cured product of the resin composition according to any one of the first to fifth aspects, and wiring.

The metal-clad laminate according to the twelfth aspect is a wiring board having an insulating layer including a cured product of the prepreg according to the sixth aspect and wiring.

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

[Examples 1 to 5 and Comparative Examples 1 to 3]
In this example, each component used in preparing the resin composition will be described.

(Curable Compound)
Maleimide compound-1: solid content in MIR-5000-60T manufactured by Nippon Kayaku Co., Ltd. Maleimide compound-2: solid content in MIR-3000-70MT manufactured by Nippon Kayaku Co., Ltd. Hydrocarbon compound: a polyfunctional vinyl aromatic copolymer obtained by the reaction as follows.

3.0 mol (390.6 g) of divinylbenzene, 1.8 mol (229.4 g) of ethylvinylbenzene, 10.2 mol (1066.3 g) of styrene, and 15.0 mol (1532.0 g) of n-propyl acetate were charged into a 5.0 L reactor, and 600 mmol of a diethyl ether complex of boron trifluoride was added at 70°C and reacted for 4 hours. After that, to terminate the reaction, an aqueous solution of sodium bicarbonate was added to the resulting reaction solution, and the oil layer was washed three times with pure water, and the solid was recovered by degassing at 60°C under reduced pressure. The resulting solid was weighed and it was confirmed that 896.7 g was obtained.

The structure of the obtained solid (polymer) was measured by ¹³ C-NMR and ¹ H-NMR analysis using a JNM-LA600 nuclear magnetic resonance spectrometer manufactured by JEOL Ltd. Chloroform- _d1 was used as the solvent, and the resonance line of tetramethylsilane was used as the internal standard. Furthermore, in addition to the results of ¹³ C-NMR and ¹ H-NMR measurements, the amount of specific structural units introduced was calculated from the data on the total amount of each structural unit introduced into the copolymer obtained by GC analysis, and the amount of pendant vinyl group units contained in the polyfunctional vinyl aromatic copolymer was calculated from the amount of specific structural units introduced into the terminal and the number average molecular weight obtained by the GPC measurement.

The obtained solid was subjected to the above-mentioned ¹³ C-NMR and ¹ H-NMR analysis, and the resonance lines derived from each monomer unit were observed. Based on the NMR measurement results and the GC analysis results, it was found that this solid was the polyfunctional vinyl aromatic copolymer. Based on the NMR measurement results and the GC analysis results, the constituent units of this polyfunctional vinyl aromatic copolymer were calculated as follows. The structural units derived from divinylbenzene were 30.4 mol% (33.1 mass%), the structural units derived from styrene were 57.4 mol% (52.7 mass%), the structural units derived from ethylvinylbenzene: 12.2 mol% (14.2 mass%), and the structural units having residual vinyl groups derived from divinylbenzene: 23.9 mol% (25.9 mass%).

The molecular weight and molecular weight distribution of the obtained solid (polyfunctional vinyl aromatic copolymer) were measured using GPC (HLC-8120GPC manufactured by Tosoh Corporation) with tetrahydrofuran as the solvent, a flow rate of 1.0 ml/min, a column temperature of 38°C, and a calibration curve based on monodisperse polystyrene. As a result, the number average molecular weight Mn of the obtained solid was 2980, the weight average molecular weight Mw was 41300, and Mw/Mn was 13.9.

Benzoxazine compound: ALP-d manufactured by Shikoku Chemical Industry Co., Ltd.
(catalyst)
PBP: α,α'-di(t-butylperoxy)diisopropylbenzene (Perbutyl P (PBP) manufactured by NOF Corporation)
(Filling material)
Polysilsesquioxane particle-1: BQ1510-SB manufactured by TAT (R ₁ in the structural unit (T ³ structure) represented by the formula (1) and R ₂ in the structural unit (T ² structure) represented by the formula (2) are methyl groups, [T ³ /(T ³ +T ² +Q ² +Q ³ +Q ⁴ )]: 91%, [T ² /(T ³ +T ² +Q ² +Q ³ +Q ⁴ )]: 9%, hydroxyl group equivalent: 778.18 g/eq)
Polysilsesquioxane particle-2: BQ1510-SSB manufactured by TAT (R ₁ in the structural unit (T ³ structure) represented by the formula (1) and R ₂ in the structural unit (T ² structure) represented by the formula (2) are methyl groups, [T ³ /(T ³ +T ² +Q ² +Q ³ +Q ⁴ )]: 94%, [T ² /(T ³ +T ² +Q ² +Q ³ +Q ⁴ )]: 6%, hydroxyl group equivalent: 1110.42 g/eq)
Polysilsesquioxane particle-3: BQQ1510 manufactured by TAT (R ₁ in the structural unit (T ³ structure) represented by the formula (1) and R ₂ in the structural unit (T ² structure) represented by the formula (2) are methyl groups, [T ³ /(T ³ +T ² +Q ² +Q ³ +Q ⁴ )]: 85.9%, [T ² /(T ³ +T ² +Q ² +Q ³ +Q ⁴ )]: 11.5%, [Q ³ /(T ³ +T ² +Q ² +Q ³ +Q ⁴ )]: 1.1%, [Q ⁴ /(T ³ +T ² +Q ² +Q ³ +Q ⁴ )]: 1.5%, [(T ² +Q ² +Q ³ )/(T ³ +T ² +Q ² +Q ³ + Q ⁴ )]: 14.1%, hydroxyl equivalent: 540.25 g/eq)
Spherical silica: Spherical silica surface-treated with a silane coupling agent having a vinyl group in the molecule (vinylsilane-treated spherical silica, SC2050-MNU manufactured by Admatechs Co., Ltd.)
[Preparation method]
First, the components other than the filler were added to methyl ethyl ketone (MEK) and mixed to a solid content concentration of 50 mass% in the composition (parts by mass) shown in Table 1. The resulting mixture was stirred for 60 minutes. Thereafter, the filler was added to the resulting liquid in the composition (parts by mass) shown in Table 1, and dispersed with a bead mill. In this way, a varnish-like resin composition (varnish) was obtained.

Next, the prepreg was obtained as follows:

The obtained varnish was impregnated into a fibrous substrate (glass cloth: NEA2116-S201 manufactured by Nitto Boseki Co., Ltd.), which was then heated and dried at 120-150°C for 3 minutes to produce a prepreg. The content of the components constituting the resin composition by the curing reaction (resin content) relative to the prepreg was adjusted to 40-50% by mass.

The resin composition and prepreg prepared as described above were evaluated using the methods described below.

[Dielectric properties (dielectric constant)]
Copper foil (3EC-LPIII, 12 μm thick, manufactured by Mitsui Mining & Smelting Co., Ltd.) was placed on both sides of each prepreg obtained. This was used as a pressure body, and was heated to a temperature of 220° C. at a temperature increase rate of 3° C./min, and heated and pressed at 220° C. for 120 minutes under a pressure of 2 MPa, to obtain an evaluation substrate (metal-clad laminate) with a thickness of about 0.1 mm, with copper foil bonded to both sides.

The copper foil was removed from the evaluation substrate (metal-clad laminate) by etching to prepare an unclad plate, which was used as a test piece, and the relative dielectric constant at 10 GHz was measured using a cavity resonator perturbation method. Specifically, the relative dielectric constant of the evaluation substrate at 10 GHz was measured using a network analyzer (N5230A manufactured by Agilent Technologies, Inc.).

[Thermal expansion coefficient]
The copper foil was removed from the evaluation substrate (metal-clad laminate) by etching to prepare an unclad plate, which was used as a test piece, and the thermal expansion coefficient (CTE: ppm/°C) in the Y-axis direction was measured by the TMA method (thermo-mechanical analysis) in accordance with JIS C 6481. For the measurement, a TMA device (TMA6000 manufactured by SII Nano Technology Co., Ltd.) was used, and the measurement was performed in the range of 50 to 260°C.

[Copper foil peel strength]
The copper foil was peeled off from the evaluation substrate (metal-clad laminate), and the peel strength at this time was measured in accordance with JIS C 6481 (1996). Specifically, a pattern having a width of 10 mm, a length of 100 mm, and a thickness of 0.012 mm was formed on the evaluation substrate, and the copper foil was peeled off at a speed of 50 mm/min using a tensile tester, and the peel strength at this time (N/mm) was measured.

The results of each of the above evaluations are shown in Table 1. Note that the parentheses [( )] for the filler indicate the filler content (volume %) relative to the resin composition.

The results of each of the above evaluations are shown in Table 1.

As can be seen from Table 1, in the case of containing polysilsesquioxane particles (the polysilsesquioxane particles (B)) in which [T ³ /(T ³ +T ² +Q ² +Q ³ +Q ⁴ )] is 70% or more and less than 100%, and [(T ² +Q ² +Q ³ )/(T ³ +T ² +Q ² +Q ³ +Q ⁴ )] is more than 0% and 20% or less (Examples 1 to 5), the resin composition was a cured product with a low thermal expansion coefficient (thermal expansion coefficient) compared to the case of not containing a filler such as polysilsesquioxane particles (Comparative Example 1 and Comparative Example 2). In addition, the resin compositions according to Examples 1 to 5 were resin compositions that, even if they contained a filler, were cured products with a low relative dielectric constant compared to the case of containing spherical silica as a filler (Comparative Example 3). From these findings, it was found that when the polysilsesquioxane particles (B) are included as a filler, a resin composition having a low dielectric constant and a low thermal expansion coefficient (thermal expansion coefficient) can be obtained. Also, even when the polysilsesquioxane particles (B) are included, a resin composition having a low dielectric constant and a low thermal expansion coefficient (thermal expansion coefficient) can be obtained, while suppressing (without significantly reducing) the decrease in copper foil peel strength.

REFERENCE SIGNS LIST 1 Prepreg 2 Resin composition or semi-cured resin composition 3 Fibrous substrate 11 Metal-clad laminate 12 Insulating layer 13 Metal foil 14 Wiring 21 Wiring board 31 Metal foil with resin 32, 42 Resin layer 41 Film with resin 43 Support film

Claims (12)

At least one curable compound (A) selected from the group consisting of maleimide compounds, benzoxazine compounds, and hydrocarbon compounds;
Polysilsesquioxane particles (B),
The polysilsesquioxane particles (B) have a structural unit represented by the following formula (1) and at least one structural unit selected from the structural units represented by the following formulas (2) to (5) in a molecule:
In the polysilsesquioxane particles (B), the ratio of the number of Si atoms contained in the structural unit represented by the following formula (1) to the total number of Si atoms contained in each of the structural units represented by the following formulas (1) to (5) is 70% or more and less than 100%,
The polysilsesquioxane particles (B) have a ratio of the total number of Si atoms contained in each of the structural units represented by the following formulas (2) to (4) to the total number of Si atoms contained in each of the structural units represented by the following formulas (1) to (5) of more than 0% and not more than 20%.

[In formula (1), R ₁ represents an alkyl group or an aryl group.]

[In formula (2), _R2 represents an alkyl group or an aryl group.]


The resin composition according to claim 1, wherein the polysilsesquioxane particles (B) contain polysilsesquioxane having a random structure. The resin composition according to claim 1 , wherein the hydrocarbon-based compound comprises at least one of a polyfunctional vinyl aromatic copolymer and a hydrocarbon-based compound represented by the following formula (6):

[In formula (6), X represents a hydrocarbon group having 6 or more carbon atoms including at least one selected from an aromatic cyclic group and an aliphatic cyclic group, and n represents 1 to 10.] The resin composition according to claim 1, further comprising a reactive compound (C) that reacts with the curable compound (A). The resin composition according to claim 1, wherein the content of the polysilsesquioxane particles (B) is 10 to 200 parts by mass per 100 parts by mass of the resin component. A prepreg comprising the resin composition according to any one of claims 1 to 5 or a semi-cured product of the resin composition and a fibrous base material. A resin-coated film comprising a resin layer containing the resin composition according to any one of claims 1 to 5 or a semi-cured product of the resin composition, and a support film. A resin-coated metal foil comprising a resin layer containing the resin composition according to any one of claims 1 to 5 or a semi-cured product of the resin composition, and a metal foil. A metal-clad laminate comprising an insulating layer containing a cured product of the resin composition according to any one of claims 1 to 5, and a metal foil. A metal-clad laminate comprising an insulating layer containing the cured product of the prepreg according to claim 6 and a metal foil. A wiring board comprising an insulating layer containing a cured product of the resin composition according to any one of claims 1 to 5, and wiring. A wiring board comprising an insulating layer containing the cured product of the prepreg according to claim 6 and wiring.