CN117897416A - Copolymer and resin composition - Google Patents

Abstract

The purpose of the present invention is to provide a copolymer having excellent solvent solubility and low dielectric loss tangent. A copolymer comprising an aromatic vinyl monomer unit, a monomer unit containing a crosslinking group, and a monomer unit providing a homopolymer having a glass transition temperature of 150 ℃ or higher.

Description

Copolymer and resin composition

Technical Field

The present invention relates to copolymers and resin compositions.

Background technique

In recent years, electrical equipment, electronic equipment, and communication equipment have developed significantly. Currently, these devices tend to use higher frequency bands. Generally, various printed circuit boards are used in these devices. Therefore, printed circuit boards are also required to have excellent electrical properties corresponding to the high frequency bands, excellent heat resistance that can withstand soldering operations, and the like.

For example, Patent Document 1 discloses an invention relating to a composition comprising a predetermined fluorine-containing thermosetting resin, a siloxane compound, and a catalyst for a hydrosilylation reaction. However, the fluorine-containing thermosetting resin specifically disclosed is only a resin in which a crosslinking group is introduced into a fluorine resin containing an OH group by a polymerization reaction.

Patent Document 2 discloses an invention related to a predetermined laminate, and describes the introduction of crosslinking groups using a fluorine-containing thermosetting resin. However, it only describes the introduction of crosslinking groups into an OH group-containing fluorine resin by a polymer reaction.

Patent Document 3 discloses an invention relating to a predetermined curable resin composition composed of a fluorine-containing polymer and a hydrosilylation crosslinking agent, and describes examples of dicyclopentadiene and fluoroolefin. However, it cannot be said that the polymerization efficiency is good. In addition, a curing system using a crosslinking agent is disclosed, but a curing reaction using only heat is not disclosed.

Prior art literature

Patent Literature

Patent Document 1: International Publication No. 2008/044765

Patent Document 2: Japanese Patent Application Publication No. 2014-26619

Patent Document 3: International Publication No. 2011/115042

Summary of the invention

Problems to be solved by the invention

The present invention provides a copolymer having excellent solvent solubility and low dielectric loss tangent.

Means for solving problems

The present invention (1) relates to a copolymer comprising: an aromatic vinyl monomer unit, a monomer unit containing a crosslinking group, and a monomer unit providing a homopolymer having a glass transition temperature of 150° C. or higher.

The present invention (2) is the copolymer of the present invention (1), which is a thermosetting resin.

The present invention (3) is the copolymer of the present invention (1) or (2), wherein the aromatic vinyl monomer unit is a styrene unit.

The present invention (4) is a copolymer in combination with any one of the present inventions (1) to (3), wherein the crosslinking group-containing monomer unit comprises a diene monomer unit having an alicyclic structure.

The present invention (5) is a copolymer in combination with any one of the present inventions (1) to (3), wherein the crosslinking group-containing monomer unit includes a monomer unit having a dicyclopentenyl structure.

The present invention (6) is a copolymer in combination with any one of the present inventions (1) to (3), wherein the crosslinking group-containing monomer unit comprises at least one selected from the group consisting of dicyclopentadiene units and dicyclopentenyl vinyl ether units.

The present invention (7) is a copolymer in combination with any one of the present inventions (1) to (6), wherein the monomer unit providing a homopolymer having a glass transition temperature of 150° C. or higher comprises a maleimide unit.

The present invention (8) is the copolymer of the present invention (7), wherein the maleimide unit includes at least one selected from the group consisting of N-cyclohexylmaleimide units and N-phenylmaleimide units.

The present invention (9) is a copolymer in combination with any one of the present inventions (1) to (8), further comprising a fluorine-containing monomer unit which provides a C-F bond to the main chain.

The present invention (10) is a copolymer in combination with any one of the present inventions (1) to (9), wherein the glass transition temperature is 140°C or higher.

The present invention (11) is a copolymer in combination with any one of the present inventions (2) to (10), wherein the thermal curing temperature is 240°C or lower.

The present invention (12) is a copolymer in combination with any one of the present inventions (1) to (11), which has solubility in methyl ethyl ketone or toluene.

The present invention (13) is a copolymer in combination with any one of the present inventions (1) to (12), wherein the crosslinking group-containing monomer unit accounts for 1 mol% or more of all polymerized units constituting the copolymer.

The present invention (14) is a copolymer in any combination with any one of the present inventions (1) to (13), wherein the monomer unit providing a homopolymer having a glass transition temperature of 150°C or higher accounts for 5 mol% or more of all the polymer units constituting the copolymer.

The present invention (15) is a copolymer in combination with any one of the present inventions (1) to (14), wherein the dielectric loss tangent is 0.0030 or less.

The present invention (16) relates to a copolymer composition comprising a copolymer in any combination of any one of the present inventions (1) to (15) and a solvent.

The present invention (17) is the copolymer composition of the present invention (16), comprising: a polymer containing two or more vinyl groups or a monomer component containing two or more vinyl groups.

The present invention (18) is the copolymer composition of the present invention (16) or (17), which contains a photopolymerization initiator.

The present invention (19) is a copolymer composition in combination with any one of the present inventions (16) to (18), wherein the gel fraction is 30% or more.

The present invention (20) relates to a film comprising a copolymer in any combination with any one of the present inventions (1) to (15).

The present invention (21) relates to a laminate comprising a substrate and a resin layer provided on the substrate, wherein the resin layer comprises a copolymer in any combination with any one of the present inventions (1) to (15).

The present invention (22) relates to a metal-clad laminate comprising a metal foil and a resin layer provided on the metal foil, wherein the resin layer comprises a copolymer in any combination with any one of the present inventions (1) to (15).

The present invention (23) relates to a printed circuit board characterized by comprising a pattern circuit formed by etching the metal foil of the metal-clad laminate of the present invention (22).

Effects of the Invention

According to the present invention, a copolymer having excellent solvent solubility and low dielectric loss tangent can be provided.

Detailed ways

As described in patent documents 1 and 2, in order to make a resin (polymer) into a thermosetting resin, it is necessary to introduce a crosslinking group. In addition, the introduction of the crosslinking group so far is usually a method of synthesizing a polymer containing an OH group and introducing an acryloyl group by a polymer reaction, and in particular, the method of introducing an acrylic monomer having an isocyanate and reacting with an OH group is simple and widely used. However, the electrical properties of the resin using an acryloyl group as a crosslinking group are not very good. As other methods, there is also a method of simply copolymerizing a diene monomer during polymerization, but there is a problem of gelation during polymerization or the amount of crosslinking group introduced being limited.

Through intensive research by the present inventors, it was found that by using a copolymer (resin) of the aromatic vinyl monomer of the present invention, a monomer containing a crosslinking group and a monomer providing a homopolymer with a glass transition temperature of 150°C or above, a copolymer with excellent solvent solubility and low dielectric loss tangent can be provided, thereby completing the present invention.

The copolymer (resin) of the present invention has an aromatic vinyl monomer unit, a monomer unit containing a crosslinking group, and a monomer unit providing a homopolymer having a glass transition temperature of 150° C. or higher. The copolymer has these three units, and is endowed with a very low dielectric loss tangent and excellent solvent solubility. In addition, the dielectric constant and linear expansion coefficient are also low. Furthermore, since the monomer unit containing a crosslinking group is introduced, self-crosslinking (thermal crosslinking, etc.) can be performed even without the use of a crosslinking agent, and good thermosetting properties can be imparted.

The copolymer of the present invention has an aromatic vinyl monomer unit.

"Aromatic vinyl monomer unit" is a polymerization unit based on an aromatic vinyl monomer. The above copolymer may contain one aromatic vinyl monomer unit or two or more aromatic vinyl monomer units. It should be noted that the above aromatic vinyl monomer unit may be any one of a fluorine-containing monomer unit (a polymerization unit based on a fluorine-containing monomer) and a non-fluorine-containing monomer unit (a polymerization unit based on a non-fluorine-containing monomer).

The aromatic vinyl monomer is a monomer containing an aromatic ring and a vinyl group in the molecule, and examples thereof include styrene, α-methylstyrene, p-methylstyrene, o-methylstyrene, tert-butylstyrene, etc. Among the aromatic vinyl monomer units, styrene units are preferred from the perspective of low dielectric constant and low dielectric loss tangent.

Due to the excellent low dielectric constant and low dielectric loss tangent, the above-mentioned aromatic vinyl monomer unit is preferably 5 mol% or more, more preferably 20 mol% or more, more preferably 30 mol% or more, relative to all the polymer units constituting the above-mentioned copolymer, and is preferably 90 mol% or less, more preferably 80 mol% or less, and further preferably 70 mol% or less.

The copolymer of the present invention has a monomer unit having a crosslinking group.

"Mercan units containing crosslinking groups" are polymerized units based on monomers containing crosslinking groups (monomers having crosslinking groups). The above copolymer may contain one monomer unit containing crosslinking groups, or may contain two or more monomer units. It should be noted that the above monomer unit containing crosslinking groups may be any one of fluorine-containing monomer units and non-fluorine-containing monomer units.

The crosslinking group-containing monomer is a crosslinking group (a crosslinking group) in the molecule. Examples of the crosslinking group include a group containing a carbon-carbon double bond, a halogen atom, an acid anhydride group, a carboxyl group, an amino group, a cyano group, and a hydroxyl group.

Due to the excellent low dielectric constant and low dielectric loss tangent, the above-mentioned monomer units containing cross-linking groups are preferably 1 mol% or more, more preferably 3 mol% or more, more preferably 5 mol% or more, relative to all the polymer units constituting the above-mentioned copolymer. In addition, it is preferably 50 mol% or less, more preferably 30 mol% or less, and further preferably 20 mol% or less.

The crosslinking group-containing monomer unit is not particularly limited as long as it is a monomer unit having a crosslinking group, but is preferably a diene monomer unit having an alicyclic structure (a polymerized unit based on a diene monomer having an alicyclic structure) from the perspective of low dielectric constant and low dielectric loss tangent.

Examples of the diene monomer having an alicyclic structure include monocyclic alicyclic dienes, polycyclic alicyclic condensed dienes, and crosslinked cyclic dienes. Examples of the monocyclic alicyclic dienes include 1,4-cyclohexadiene, 1,5-cyclooctadiene, 1,5-cyclododecadiene, 4-vinylcyclohexene, 1-allyl-4-isopropenylcyclohexane, 3-allylcyclopentene, 1-isopropenyl-4-(4-butenyl)cyclohexane, and limonene. Examples of polycyclic alicyclic condensed dienes and crosslinked cyclic dienes include tetrahydroindene, methyltetrahydroindene, dicyclopentadiene, bicyclo(2,2,1)heptadiene-2,5-diene, 2-methylbicycloheptadiene, alkenyl, alkylidene, cycloalkenyl, and cycloalkylidene norbornene (5-methylene-2-norbornene, 5-ethylidene-2-norbornene, 5-isopropylidene norbornene, 5-(4-cyclopentenyl)-2-norbornene, 5-cyclohexylidene-2-norbornene, etc.). Among them, limonene, dicyclopentadiene, and 5-ethylidene-2-norbornene are preferred.

As the above-mentioned monomer unit containing a crosslinking group, from the perspective of low dielectric constant and low dielectric loss tangent, it is also preferred to select at least one of the group consisting of a dicyclopentadiene unit (a polymerization unit based on dicyclopentadiene) and a monomer unit having a dicyclopentenyl structure (a polymerization unit based on a monomer having a dicyclopentenyl structure). Among them, a monomer unit having a dicyclopentenyl structure is more preferred. Here, the monomer unit having a dicyclopentenyl structure preferably contains 0 to 1 heteroatoms.

Among the above-mentioned crosslinking group-containing monomer units, at least one selected from the group consisting of dicyclopentadiene units and dicyclopentenyl vinyl ether units is preferred.

The dicyclopentadiene (DCPD) is a monomer represented by the following formula.

[Chemistry 1]

Due to the excellent low dielectric constant and low dielectric loss tangent, the above-mentioned dicyclopentadiene unit is preferably 1 mol% or more, more preferably 3 mol% or more, more preferably 5 mol% or more, relative to all the polymer units constituting the above-mentioned copolymer, and is preferably 50 mol% or less, more preferably 30 mol% or less, and further preferably 20 mol% or less.

Examples of the monomer containing the dicyclopentenyl structure include monomers having a dicyclopentenyl group represented by the following formulae (I-1) and (I-2).

[Chemistry 2]

Examples of the monomer having a dicyclopentenyl group represented by the above formula (I-1) or (I-2) include the following compounds.

[Chemistry 3]

(In the formula, R ⁵¹ is a hydrogen atom or a methyl group.)

Among them, the compound represented by the following formula is preferred.

[Chemistry 4]

Specific examples of the monomer having a dicyclopentenyl group represented by the above formula (I-1) or (I-2) include dicyclopentenyl acrylate and dicyclopentenyl methacrylate.

Examples of the monomer having a dicyclopentenyl group represented by the above formula (I-1) or (I-2) include the following compounds.

[Chemistry 5]

(In the formula, R ⁶¹ is a hydrogen atom or a methyl group.)

Among them, the compound represented by the following formula is preferred.

[Chemistry 6]

Specific examples of the monomer having a dicyclopentenyl group represented by the above formula (I-1) or (I-2) include dicyclopentenyl vinyl ether and the like.

Due to the excellent low dielectric constant and low dielectric loss tangent, the monomer unit containing the above-mentioned dicyclopentenyl structure is preferably 1 mol% or more, more preferably 3 mol% or more, more preferably 5 mol% or more, relative to all the polymer units constituting the above-mentioned copolymer. In addition, it is preferably 50 mol% or less, more preferably 30 mol% or less, and further preferably 20 mol% or less.

The copolymer of the present invention has the above-mentioned monomer units that provide a homopolymer with a glass transition temperature (Tg) of 150°C or more (polymerized units based on monomers that provide a homopolymer with a Tg of 150°C or more). Regarding the "monomer units that provide a homopolymer with a glass transition temperature of 150°C or more", in the case of making a homopolymer obtained by polymerizing only the same type of monomers, it is a polymerized unit based on monomers with a glass transition temperature of 150°C or more. The above-mentioned copolymer may contain one such monomer unit or two or more. It should be noted that the monomer unit may be any one of a fluorine-containing monomer unit and a non-fluorine-containing monomer unit.

In the above-mentioned monomer unit that provides a homopolymer with a glass transition temperature (Tg) of 150°C or higher, the Tg is preferably 170°C or higher, more preferably 200°C or higher, and further preferably 250°C or higher, and is preferably 400°C or lower, more preferably 350°C or lower, and further preferably 320°C or lower.

The above-mentioned Tg is a value measured by a differential scanning calorimeter (DSC).

Due to the excellent low dielectric constant and low dielectric loss tangent, the monomer unit of the homopolymer providing a glass transition temperature of 150°C or above is preferably 5 mol% or more, more preferably 20 mol% or more, more preferably 30 mol% or more, relative to all the polymer units constituting the above-mentioned copolymer, and is preferably 80 mol% or less, more preferably 70 mol% or less, and further preferably 60 mol% or less.

As the monomer unit providing the homopolymer having a glass transition temperature of 150° C. or higher, it is preferred to include a maleimide unit (a monomer unit based on maleimide) due to its excellent low dielectric constant and low dielectric loss tangent, and more preferably include an N-substituted maleimide unit (a monomer unit based on N-substituted maleimide). Among them, it is preferred to include monomer units represented by the following formulas (II-1) and (II-2).

[Chemistry 7]

(In the formula, R ¹¹ is an arylalkyl group having 7 to 14 carbon atoms or an aryl group having 6 to 14 carbon atoms. R ¹² and R ¹³ are each independently a hydrogen atom, an oxygen atom, a sulfur atom, an alkyl group having 1 to 12 carbon atoms, or an aryl group having 6 to 14 carbon atoms. It should be noted that R ¹¹ , R ¹² , and R ¹³ may or may not have a substituent.)

[Chemistry 8]

(In the formula, R ¹⁴ is a hydrogen atom, a cycloalkyl group having 3 to 12 carbon atoms, or an alkyl group having 1 to 12 carbon atoms. R ¹⁵ and R ¹⁶ are each independently a hydrogen atom, an oxygen atom, a sulfur atom, an alkyl group having 1 to 12 carbon atoms, or an aryl group having 6 to 14 carbon atoms. It should be noted that R ¹⁴ , R ¹⁵ , and R ¹⁶ may or may not have a substituent.)

Examples of the substituents in R ¹¹ to R ¹⁶ in the above formulae (II-1) and (II-2) include halogen atoms, alkyl groups having 1 to 6 carbon atoms, alkoxy groups having 1 to 6 carbon atoms, nitro groups, benzyl groups and the like.

Examples of monomers that form the monomer unit represented by the above formula (II-1) include N-aryl maleimides, N-aromatic substituted maleimides, and the like. Specifically, examples include N-phenyl maleimide, N-benzyl maleimide, N-(2-chlorophenyl) maleimide, N-(4-chlorophenyl) maleimide, N-(4-bromophenyl) maleimide, N-(2-methylphenyl) maleimide, N-(2,6-dimethylphenyl) maleimide, N-(2-ethylphenyl) maleimide, N-(2-methoxyphenyl) maleimide, N-(2-nitrophenyl) maleimide, N-(2,4 ,6-trimethylphenyl)maleimide, N-(4-benzylphenyl)maleimide, N-(2,4,6-tribromophenyl)maleimide, N-naphthylmaleimide, N-anthrylmaleimide, 3-methyl-1-phenyl-1H-pyrrole-2,5-dione, 3,4-dimethyl-1-phenyl-1H-pyrrole-2,5-dione, 1,3-diphenyl-1H-pyrrole-2,5-dione, 1,3,4-triphenyl-1H-pyrrole-2,5-dione, etc. Among them, from the perspective of low dielectric constant and low dielectric loss tangent, N-phenylmaleimide and N-benzylmaleimide are preferred, and N-phenylmaleimide is more preferred.

Due to the excellent low dielectric constant and low dielectric loss tangent, the monomer unit represented by the above formula (II-1) is preferably 5 mol% or more, more preferably 20 mol% or more, more preferably 30 mol% or more, relative to all the polymer units constituting the above copolymer, and is preferably 80 mol% or less, more preferably 70 mol% or less, and further preferably 60 mol% or less.

Examples of the monomers forming the monomer unit represented by the formula (II-2) include N-methylmaleimide, N-ethylmaleimide, N-n-propylmaleimide, N-isopropylmaleimide, N-n-butylmaleimide, N-isobutylmaleimide, N-sec-butylmaleimide, N-tert-butylmaleimide, N-n-pentylmaleimide, N-n-hexylmaleimide, N-n-heptylmaleimide, N-n-octylmaleimide, N -laurylmaleimide, N-2-ethylhexylmaleimide, N-cyclopentylmaleimide, N-cyclohexylmaleimide, N-cyclohexylmethylmaleimide, 1-cyclohexyl-3-methyl-1H-pyrrole-2,5-dione, 1-cyclohexyl-3,4-dimethyl-1H-pyrrole-2,5-dione, 1-cyclohexyl-3-phenyl-1H-pyrrole-2,5-dione, 1-cyclohexyl-3,4-diphenyl-1H-pyrrole-2,5-dione, etc. Among them, from the perspective of low dielectric constant and low dielectric loss tangent, N-methylmaleimide, N-ethylmaleimide, N-isopropylmaleimide, and N-cyclohexylmaleimide are preferred, and N-cyclohexylmaleimide is more preferred.

Due to the excellent low dielectric constant and low dielectric loss tangent, the monomer unit represented by the above formula (II-2) is preferably 5 mol% or more, more preferably 20 mol% or more, more preferably 30 mol% or more, relative to all the polymer units constituting the above copolymer, and is preferably 80 mol% or less, more preferably 70 mol% or less, and further preferably 60 mol% or less.

Due to the excellent low dielectric constant and low dielectric loss tangent, the total unit amount of the monomer units represented by the above formulas (II-1) and (II-2) is preferably 5 mol% or more, more preferably 20 mol% or more, more preferably 30 mol% or more, relative to all the polymer units constituting the above copolymer, and is preferably 80 mol% or less, more preferably 70 mol% or less, and further preferably 60 mol% or less.

The maleimide-based unit preferably includes at least one selected from the group consisting of N-cyclohexylmaleimide units and N-phenylmaleimide units.

From the perspective of low dielectric constant and low dielectric loss tangent, the molar ratio of the aromatic vinyl monomer unit/monomer unit containing a cross-linking group in the copolymer of the present invention is preferably (50 to 95)/(5 to 50), more preferably (55 to 95)/(5 to 45), and further preferably (60 to 95)/(5 to 40).

In the copolymer of the present invention, from the perspective of low dielectric constant and low dielectric loss tangent, the molar ratio of the monomer unit providing a homopolymer with a glass transition temperature of 150° C. or higher/the monomer unit containing a crosslinking group is preferably (50 to 95)/(5 to 50), more preferably (60 to 90)/(10 to 40), and further preferably (65 to 90)/(10 to 35).

In the copolymer, the total content of the aromatic vinyl monomer unit, the crosslinking group-containing monomer unit, and the monomer unit providing a homopolymer having a glass transition temperature of 150° C. or higher is preferably 70 mol% or higher, more preferably 80 mol% or higher, further preferably 90 mol% or higher, still more preferably 95 mol% or higher, and particularly preferably 97 mol% or higher relative to the total polymerized units. It may be 100 mol% relative to the total polymerized units.

From the perspective of low dielectric constant and low dielectric loss tangent, the copolymer of the present invention preferably further has a fluorine-containing monomer unit that provides a C-F bond to the main chain (hereinafter also referred to as a "fluorine-containing monomer unit"). In this case, the above-mentioned copolymer contains fluorine atoms and has a C-F bond between the carbon atoms and the fluorine atoms that form the main chain.

The fluorinated monomer units (polymerized units based on fluorinated monomers) can be introduced into the copolymer by using fluorinated monomers. The fluorinated monomers can be any of cyclic monomers and non-cyclic monomers. The cyclic monomers and non-cyclic monomers preferably have C-F bonds between carbon atoms and fluorine atoms that form the main chain of the copolymer.

Examples of the fluorine-containing monomer include fluorine-containing vinyl monomers, fluorine-containing acrylic monomers, fluorine-containing styrene monomers, hydrogen-containing fluoroolefins, fluorine-containing norbornene, etc. Among them, fluorine-containing vinyl monomers and fluorine-containing acrylic monomers are preferred.

As the above-mentioned fluorine-containing vinyl monomer, it is preferably at least one selected from the group consisting of tetrafluoroethylene [TFE], trifluorochloroethylene [CTFE], hexafluoropropylene [HFP] and perfluoro (alkyl vinyl ether), more preferably at least one selected from the group consisting of TFE, CTFE, HFP and perfluoro (alkyl vinyl ether). From the aspects of excellent low dielectric constant and low dielectric loss tangent, dispersibility, moisture resistance, heat resistance, flame retardancy, adhesion and chemical resistance, and from the aspects of excellent low dielectric constant and low dielectric loss tangent, weather resistance and moisture resistance, it is more preferably at least one selected from the group consisting of TFE, CTFE and HFP, from the aspect of not containing chlorine, it is further preferably at least one selected from the group consisting of TFE and HFP, and from the aspect of excellent copolymerizability, TFE is particularly preferred.

Examples of the perfluoro(alkyl vinyl ether) include perfluoro(methyl vinyl ether) [PMVE], perfluoro(ethyl vinyl ether) [PEVE], perfluoro(propyl vinyl ether) [PPVE], and perfluoro(butyl vinyl ether), but are not limited thereto.

Among the above-mentioned fluorine-containing vinyl monomers, fluorine-containing ethylene, fluorine-containing propylene, fluorine-containing vinyl ether and the like are preferred, and tetrafluoroethylene, chlorotrifluoroethylene, hexafluoropropylene and perfluoro(alkyl vinyl ether) are more preferred.

In particular, the fluorine-containing vinyl monomer represented by the following formula is preferred.

[Chemistry 9]

(In the formula, R ⁷¹ to R ⁷⁴ are independently monovalent groups, and at least one of R ⁷¹ to R ⁷³ is a fluorine atom or a CF ₃ group.)

Examples of the monovalent group for R ⁷¹ to R ⁷⁴ include a hydrogen atom, a halogen atom (a fluorine atom, a chlorine atom, etc.), and a monovalent hydrocarbon group.

The monovalent hydrocarbon group may have heteroatoms such as nitrogen atoms and oxygen atoms. The monovalent hydrocarbon group may be linear, branched or cyclic. The number of carbon atoms in the monovalent hydrocarbon group is preferably 1 to 8, more preferably 1 to 5, and even more preferably 1 to 3. Examples of the monovalent hydrocarbon group include alkyl, alkenyl, and alkynyl groups having the above-mentioned number of carbon atoms.

The monovalent group is preferably a hydrogen atom, a fluorine atom, a chlorine atom, a fluorinated alkyl group having the above number of carbon atoms, or a fluorinated alkoxy group having the above number of carbon atoms.

As the fluorine-containing acrylic monomer, for example, the compound represented by the following formula can be mentioned from the viewpoint that a C-F bond can be introduced into the main chain of the polymer and the glass transition temperature of the polymer can be increased.

[Chemistry 10]

(In the formula, ^R41 represents an alkyl group which may be substituted with one or more fluorine atoms.)

[Chemistry 11]

(In the formula, ^R42 represents an alkyl group which may be substituted with one or more fluorine atoms.)

Examples of the alkyl group of the "alkyl group which may be substituted with one or more fluorine atoms" represented by R ⁴¹ and R ⁴² include methyl group, ethyl group, propyl group, butyl group and the like. Among them, methyl group, ethyl group and tert-butyl group are preferred, and methyl group is more preferred.

In particular, the fluorine-containing acrylic monomer represented by the following formula is preferred.

[Chemistry 12]

Specific examples of the fluorine-containing acrylic monomer represented by the above formula include methyl-2-fluoroacrylate and ethyl-2-fluoroacrylate.

As the fluorinated acrylic monomer, the monomers represented by the following formulae (monomers having a dicyclopentenyl group represented by the above formulae (I-1) and (I-2)) can also be mentioned. For example, by using these monomers, the dicyclopentenyl group represented by the above formulae (I-1) and (I-2) can be introduced into the copolymer.

[Chemistry 13]

The fluorinated styrene monomer is preferably at least one selected from the group consisting of _CF2 =CF-C6H5, CF2=CF- _{C6H4 -CH3} and _CF2 =CF- _C6H4 - _CF3 , from the viewpoint of being able to introduce _a CF bond into the polymer main chain and increase the _glass transition temperature of _{the polymer . Among} them, the fluorinated styrene monomer represented by the following formula is preferred.

[Chemistry 14]

As the hydrogen-containing fluoroolefin, preferably one in which the hydrogen atoms of ethylene are replaced with fluorine atoms, and examples thereof include vinyl fluoride, trifluoroethylene, and vinylidene fluoride [VDF]. Among them, vinyl fluoride is preferred.

The fluorinated norbornene may have one norbornene skeleton or two or more norbornene skeletons as long as it has a polymerizable group. The fluorinated norbornene is produced by a Diels-Alder addition reaction of an unsaturated compound and a diene compound.

Examples of the unsaturated compound include fluorinated olefins, fluorinated allyl alcohols, fluorinated homoallyl alcohols, α-fluoroacrylic acid, α-trifluoromethylacrylic acid, fluorinated acrylates or fluorinated methacrylates, 2-(benzoyloxy)pentafluoropropane, 2-(methoxyethoxymethyloxy)pentafluoropropylene, 2-(tetrahydroxypyranyloxy)pentafluoropropylene, 2-(benzoyloxy)trifluoroethylene, and 2-(methoxymethyloxy)trifluoroethylene.

Examples of the diene compound include cyclopentadiene and cyclohexadiene.

Examples of the fluorine-containing norbornene include compounds represented by the following formula.

[Chemistry 15]

Among the above-mentioned fluorine-containing monomers, the above-mentioned fluorine-containing monomer preferably contains at least one selected from the group consisting of fluorine-containing ethylene, fluorine-containing propylene and fluorine-containing vinyl ether, and more preferably contains at least one selected from the group consisting of vinylidene fluoride, tetrafluoroethylene, chlorotrifluoroethylene, vinyl fluoride, hexafluoropropylene and perfluoro(alkyl vinyl ether).

Furthermore, the fluorine-containing monomer preferably contains at least one of a compound represented by the following formula, tetrafluoroethylene and hexafluoropropylene.

[Chemistry 16]

Furthermore, the fluorine-containing monomer preferably contains at least one compound represented by the following formula.

[Chemistry 17]

When the above-mentioned polymer contains the above-mentioned fluorinated monomer unit, due to the excellent low dielectric constant and low dielectric loss tangent, the above-mentioned fluorinated monomer unit is preferably 1 mol% or more, more preferably 3 mol% or more, more preferably 5 mol% or more, relative to all the polymer units constituting the above-mentioned copolymer, and is preferably 80 mol% or less, more preferably 50 mol% or less, and further preferably 30 mol% or less.

The copolymer of the present invention may contain the above-mentioned aromatic vinyl monomer units, crosslinking group-containing monomer units, monomer units providing a homopolymer having a glass transition temperature of 150° C. or higher, and “other monomer units” (polymerized units based on other monomers) other than the fluorine-containing monomer units.

Examples of the above-mentioned other monomers include fluorine-free monomers (hereinafter also referred to as "non-fluorine-containing monomers") that are reactive with the above-mentioned aromatic vinyl monomers, monomers containing crosslinking groups, and monomers that provide homopolymers having a glass transition temperature of 150° C. or higher. Examples of the above-mentioned non-fluorine-containing monomers include hydrocarbon monomers, etc.

Due to the excellent low dielectric constant and low dielectric loss tangent, the above-mentioned other monomer units (polymer units based on other monomers) are preferably 0.1 mol% or more, more preferably 0.5 mol% or more, more preferably 1 mol% or more, relative to all the polymer units constituting the above-mentioned copolymer, and are preferably 50 mol% or less, more preferably 40 mol% or less, and further preferably 30 mol% or less.

Examples of the other monomers include:

Olefins such as ethylene, propylene, butene, isobutylene, and 1-decene;

Alkyl vinyl ethers such as ethyl vinyl ether, propyl vinyl ether, butyl vinyl ether, isobutyl vinyl ether, cyclohexyl vinyl ether, and 2-ethylhexyl vinyl ether;

Vinyl acetate, vinyl propionate, vinyl butyrate, vinyl isobutyrate, vinyl valerate, vinyl pivalate, vinyl caproate, vinyl caprylate, vinyl caprate, vinyl versatate, vinyl laurate, vinyl myristic acid, vinyl palmitate, vinyl stearate, vinyl benzoate, vinyl p-tert-butylbenzoate, vinyl cyclohexanecarboxylate, vinyl monochloroacetate, vinyl adipate, vinyl acrylate, vinyl methacrylate, vinyl crotonate, vinyl sorbate, vinyl cinnamate, vinyl undecylenate, vinyl hydroxyacetate, vinyl hydroxypropionate, vinyl hydroxybutyrate, vinyl hydroxyvalerate, vinyl hydroxyisobutyrate, vinyl hydroxycyclohexanecarboxylate, and other vinyl esters;

Alkyl allyl ethers such as ethyl allyl ether, propyl allyl ether, butyl allyl ether, isobutyl allyl ether, cyclohexyl allyl ether, etc.

Alkyl allyl esters such as ethyl allyl ester, propyl allyl ester, butyl allyl ester, isobutyl allyl ester, cyclohexyl allyl ester, etc.; etc.

Among them, olefins and alkyl vinyl ethers are preferred, 1-decene, ethyl vinyl ether, propyl vinyl ether, butyl vinyl ether, isobutyl vinyl ether, cyclohexyl vinyl ether, and 2-ethylhexyl vinyl ether are more preferred, and 1-decene, cyclohexyl vinyl ether, and 2-ethylhexyl vinyl ether are further preferred.

As the other monomer, a monomer having an alicyclic structure is preferably selected from the viewpoint of being able to impart solvent solubility to the copolymer.

As the monomer having an alicyclic structure, at least one (meth)acrylic acid ester selected from the group consisting of isobornyl methacrylate, isobornyl acrylate, cyclohexyl methacrylate, cyclohexyl acrylate, dicyclopentanyl acrylate, and dicyclopentanyl methacrylate is preferred.

As the hydrocarbon monomers of the above other monomers, hydrocarbon monomers containing functional groups may also be used. Examples of the above hydrocarbon monomers containing functional groups include monomers containing OH groups. Examples of the above hydrocarbon monomers containing functional groups include:

Non-fluorinated monomers having an OH group (hydroxyl group) such as hydroxyalkyl vinyl ethers such as hydroxyethyl vinyl ether, hydroxypropyl vinyl ether, hydroxybutyl vinyl ether, hydroxyisobutyl vinyl ether and hydroxycyclohexyl vinyl ether;

Non-fluorinated monomers having a carboxyl group, such as itaconic acid, succinic acid, succinic anhydride, fumaric acid, fumaric anhydride, crotonic acid, maleic acid, maleic anhydride, and di-2-ethylhexyl fumarate;

Non-fluorinated monomers having a glycidyl group, such as glycidyl vinyl ether and glycidyl allyl ether;

Non-fluorinated monomers having an amino group, such as aminoalkyl vinyl ether and aminoalkyl allyl ether;

Non-fluorine-containing monomers having an amide group, such as (meth)acrylamide and hydroxymethylacrylamide; etc.

The copolymer of the present invention is preferably a thermosetting resin from the perspective of excellent low dielectric constant and low dielectric loss tangent. For example, a thermosetting resin can be provided by using the above-mentioned aromatic vinyl monomer, a monomer containing a crosslinking group, and a monomer providing a homopolymer with a glass transition temperature of 150° C. or more.

The fluorine content of the copolymer of the present invention is preferably 10% by mass or less, more preferably 5% by mass or less, and further preferably 3% by mass or less, based on the total mass of the copolymer, and may contain no fluorine.

The fluorine content of the copolymer can be determined by elemental analysis using an automatic sample combustion apparatus.

The number average molecular weight of the copolymer of the present invention is preferably 1000 to 50000. Within this range, solvent solubility and thermosetting properties are improved. The number average molecular weight of the fluorine-containing thermosetting resin is more preferably 2000 to 30000, and even more preferably 4000 to 20000.

The number average molecular weight of the copolymer can be measured by gel permeation chromatography (GPC).

From the perspective of excellent electrical properties, especially the ability to reduce dielectric loss tangent, the glass transition temperature of the copolymer of the present invention is preferably 140° C. or higher, more preferably 150° C. or higher, further preferably 180° C. or higher, still more preferably 200° C. or higher, and particularly preferably 220° C. or higher. The higher the glass transition temperature, the better, but from the perspective of processability, it is preferably 300° C. or lower.

The glass transition temperature is a value determined by a midpoint method based on heat absorption in the second run using a DSC measuring apparatus under the following conditions in accordance with ASTM E1356-98.

Measurement conditions

Heating rate: 20℃/min

Sample volume: 10 mg

Thermal cycle: -50℃～300℃, heating, cooling, heating

From the perspective of excellent low dielectric constant and low dielectric loss tangent, the thermal curing temperature of the copolymer of the present invention is preferably 300° C. or less, more preferably 270° C. or less, further preferably 250° C. or less, particularly preferably 240° C. or less, and most preferably 230° C. or less. The lower limit is not particularly limited, but is preferably 80° C. or more, and more preferably 100° C. or more.

The above-mentioned thermal curing temperature is a value determined by the method described in Examples below.

The copolymer of the present invention preferably has solubility in methyl ethyl ketone (MEK) or toluene.

The solubility in MEK was evaluated by the method described in Examples below.

From the perspective of low dielectric constant and low dielectric loss tangent, the dielectric constant (relative dielectric constant) of the copolymer of the present invention is preferably 2.50 or less, more preferably 2.47 or less, further preferably 2.30 or less, and particularly preferably 2.25 or less. The lower limit is not particularly limited, and the smaller the value, the more preferred.

The above-mentioned dielectric constant (relative dielectric constant) is a value determined by the method described in Examples below.

From the perspective of low dielectric constant and low dielectric loss tangent, the dielectric loss tangent of the copolymer of the present invention is preferably 0.0030 or less, more preferably 0.0028 or less, further preferably 0.0025 or less, and particularly preferably 0.0020 or less. The lower limit is not particularly limited, and the smaller the value, the more preferred.

The dielectric loss tangent is a value determined by the method described in the examples described later.

The copolymer of the present invention can be produced, for example, by a method for producing a copolymer comprising the following steps: appropriately adjusting the composition of the copolymer as described above, polymerizing monomers such as the aromatic vinyl monomer, the monomer containing a crosslinking group, and the monomer providing a homopolymer having a glass transition temperature of 150° C. or higher in the presence of a chain transfer agent.

The copolymer of the present invention can be produced by solution polymerization, emulsion polymerization, suspension polymerization or bulk polymerization, and is preferably obtained by solution polymerization.

The copolymer of the present invention is preferably produced by polymerizing the above-mentioned aromatic vinyl monomer, the above-mentioned crosslinking group-containing monomer, and the above-mentioned monomer providing a homopolymer having a glass transition temperature of 150° C. or higher by a solution polymerization method using an organic solvent, a polymerization initiator, a chain transfer agent, etc. The polymerization temperature is usually 0 to 150° C., preferably 5 to 130° C. The polymerization pressure is usually 0.1 MPaG to 10 MPaG (1 kgf/cm ² G to 100 kgf/cm ² G).

Examples of the organic solvent include esters such as methyl acetate, ethyl acetate, propyl acetate, n-butyl acetate, and tert-butyl acetate; ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone; aliphatic hydrocarbons such as hexane, cyclohexane, octane, nonane, decane, undecane, dodecane, and mineral spirits; aromatic hydrocarbons such as benzene, toluene, xylene, naphthalene, and solvent naphtha; alcohols such as methanol, ethanol, tert-butyl alcohol, isopropanol, and ethylene glycol monoalkyl ether; cyclic ethers such as tetrahydrofuran, tetrahydropyran, and dioxane; dimethyl sulfoxide, or mixtures thereof.

As the above-mentioned polymerization initiator, for example, persulfates such as ammonium persulfate and potassium persulfate can be used (and a reducing agent such as sodium bisulfite, sodium pyrosulfite, cobalt naphthenate, dimethylaniline, etc. can be used in combination as needed); redox initiators composed of an oxidizing agent (such as ammonium peroxide, potassium peroxide, etc.) and a reducing agent (such as sodium sulfite, etc.) and a transition metal salt (such as ferric sulfate, etc.); diacyl peroxides such as acetyl peroxide, benzoyl peroxide, diisobutyryl peroxide, dilauroyl peroxide, didecanoyl peroxide, dicyclohexyl peroxydicarbonate, bis(4-tert-butylcyclohexyl) peroxydicarbonate; dialkoxycarbonyl peroxides such as isopropoxycarbonyl peroxide and tert-butoxycarbonyl peroxide; ketone peroxides such as methyl ethyl ketone peroxide and cyclohexanone peroxide; hydrogen peroxide, tert-butyl hydroperoxide, cumene hydroperoxide, etc. Oxides; dialkyl peroxides such as di-tert-butyl peroxide and dicumyl peroxide; alkyl peroxyesters such as tert-butyl peroxyacetate, tert-butyl peroxypivalate, tert-butyl peroxy-2-ethylhexanoate, tert-butyl peroxyisopropyl monocarbonate, tert-butyl peroxybenzoate, tert-butyl peroxyneodecanoate, tert-butyl peroxylaurate, tert-hexyl peroxypivalate, tert-hexyl peroxy-2-ethylhexanoate, and tert-hexyl peroxyisopropyl monocarbonate; azo compounds such as 2,2'-azobisisobutyronitrile, 2,2'-azobis(2,4-dimethylvaleronitrile), 2,2'-azobis(2-methylvaleronitrile), 2,2'-azobis(2-cyclopropylpropionitrile), dimethyl 2,2'-azobisisobutyrate, 2,2'-azobis[2-(hydroxymethyl)propionitrile], and 4,4'-azobis(4-cyanopentenoic acid);

As the chain transfer agent, in addition to compounds such as 2,4-diphenyl-4-methyl-pentene, for example, thiol compounds can also be used. As the thiol compound, any thiol compound known to function as a chain transfer agent may be used, preferably tert-dodecyl mercaptan, n-dodecyl mercaptan, tert-octyl mercaptan, n-octyl mercaptan, trimethylolpropane tri-3-mercaptopropionate, pentaerythritol tetra-3-mercaptopropionate, dipentaerythritol hexa-3-mercaptopropionate and (tris-[(3-mercaptopropionyloxy)-ethyl]-isocyanurate) and the like. Among them, from the perspective of ease of polymerization control and toughness of the resulting copolymer, monoalkyl mercaptan having 5 to 30 carbon atoms, such as tert-dodecyl mercaptan, n-dodecyl mercaptan, tert-octyl mercaptan and n-octyl mercaptan, is particularly preferably used.

In addition, for example, alcohols can be used, preferably alcohols having 1 to 10 carbon atoms, and more preferably monohydric alcohols having 1 to 10 carbon atoms. Specifically, methanol, ethanol, propanol, isopropanol, n-butanol, tert-butanol, 2-methylpropanol, cyclohexanol, methylcyclohexanol, cyclopentanol, methylcyclopentanol, and dimethylcyclopentanol can be used. Among them, methanol, isopropanol, tert-butanol, cyclohexanol, methylcyclohexanol, cyclopentanol, methylcyclopentanol, etc. are preferred, and methanol and isopropanol are particularly preferred.

Among them, 2,4-diphenyl-4-methyl-pentene is preferred. For example, by combining a diene monomer containing an olefin having different reactivity, such as the above-mentioned diene monomer having a dicyclopentenyl group, with 2,4-diphenyl-4-methyl-pentene, gelation during polymerization can be prevented and a crosslinking group can be introduced in one step.

The copolymer composition (resin composition) of the present invention comprises the above-mentioned copolymer and a solvent.

The copolymer composition of the present invention has excellent solvent solubility and thermosetting properties by making the copolymer have the above-mentioned structure. In addition, by using it in a resin layer, the resin layer can have a low dielectric constant and a low dielectric loss tangent.

In the copolymer composition of the present invention, the above copolymer is the same as the copolymer of the present invention. Therefore, all preferred embodiments of the copolymer described in the copolymer of the present invention can be adopted.

The copolymer composition of the present invention contains a solvent. As the above-mentioned solvent, an organic solvent is preferred. The organic solvent is not particularly limited, and examples thereof include esters such as ethyl acetate, butyl acetate, isopropyl acetate, isobutyl acetate, cellosolve acetate, and propylene glycol methyl ether acetate; ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone; cyclic ethers such as tetrahydrofuran and dioxane; amides such as N,N-dimethylformamide and N,N-dimethylacetamide; aromatic hydrocarbons such as toluene and xylene; alcohols such as propylene glycol methyl ether; hydrocarbons such as hexane and heptane; and mixed solvents thereof.

The copolymer composition of the present invention may further contain the above-mentioned monomers and other monomer components, for example, monomer components such as styrene and methyl (meth)acrylate.

From the aspect of improving thermosetting properties, the copolymer composition of the present invention may contain a crosslinking agent. The crosslinking agent used in the present embodiment is not particularly limited as long as it is a crosslinking agent having two or more carbon-carbon unsaturated double bonds in the molecule. That is, the crosslinking agent can form crosslinks and solidify by reacting with the copolymer of the aromatic vinyl monomer of the present invention, the monomer containing a crosslinking group, and the monomer providing a homopolymer with a glass transition temperature of 150°C or more. The crosslinking agent is preferably a compound having two or more carbon-carbon unsaturated double bonds at the end. The crosslinking agent can be used alone or in combination of two or more.

As specific crosslinking agents, triallyl isocyanurate compounds such as triallyl isocyanurate (TAIC), bismaleimides described later, divinylbenzene, dicyclopentenyl (meth)acrylate, pentaerythritol tri(meth)acrylate monomer components containing two or more vinyl groups, vinyl compounds having two or more vinyl groups in the molecule such as polybutadiene, etc. can be cited. As the vinyl compound having two or more vinyl groups in the above-mentioned molecule, preferably a polymer containing two or more vinyl groups such as polybutadiene. The copolymer composition of the present invention preferably contains: the above-mentioned polymer containing two or more vinyl groups or the above-mentioned monomer component containing two or more vinyl groups. From the aspect of improving thermosetting, bismaleimides are preferred. Preferred bismaleimides include, for example, 1,2-bis(maleimide)ethane, N-succinimidyl-3-maleimide propionate, 4,4′-diphenylmethane bismaleimide, N,N′-m-phenylene bismaleimide, N,N′-p-phenylene bismaleimide, bisphenol A diphenyl ether bismaleimide, 3,3′-dimethyl-5,5′-diethyl-4,4′-diphenylmethane bismaleimide, 4-methyl-1,3-phenylene bismaleimide, 1,6′-bismaleimide-(2,2,4-trimethyl)hexane, 1-maleimide-3-maleimidemethyl-3,5,5 -trimethylcyclohexane, 1,1'-(cyclohexane-1,3-diylbis(methylene))bis(1H-pyrrole-2,5-dione), 1,1'-(4,4'-methylenebis(cyclohexane-4,1-diyl))bis(1H-pyrrole-2,5-dione), 1,1'-(3,3'-(piperazine-1,4-diyl)bis(propane-3,1-diyl))bis(1H-pyrrole-2,5-dione), 2,2'-(ethylenedioxy)bis(ethylmaleimide), succinimidyl-4-(N-maleimidomethyl)cyclohexane-1-carboxylate, 2,2-bis[4-(4-maleimidophenoxy)phenyl]propane, etc.

The polybutadiene used in this embodiment can preferably use 1,2-polybutadiene, for example. Commercially available products can also be used. For example, in addition to being available as a product of JSR Corporation, liquid polybutadiene can also be obtained from Nippon Soda Co., Ltd.: product name B-1000, 2000, 3000. In addition, as a copolymer containing a 1,2-polybutadiene structure that can be preferably used, "Ricon100" of TOTAL CRAY VALLEY can be exemplified. The maleimides used in this embodiment can use commercially available products, for example, "BMI-2300" made by Yamato Chemical Industry Co., Ltd., "MIR-3000" made by Nippon Kayaku Co., Ltd., "BMI-70" made by K·I Chemical Industry Co., LTD., and "BMI-80" made by K·I Chemical Industry Co., LTD. can be preferably used.

The content of the maleimide in the above-mentioned copolymer resin composition can be suitably set according to desired characteristics, is not particularly limited. When the copolymer solid component (resin solid component) in the copolymer composition is set to 100 mass parts, the content of the maleimide compound is preferably more than 1 mass part, more preferably more than 5 mass parts. As the upper limit, preferably less than 90 mass parts, more preferably less than 60 mass parts, further preferably less than 40 mass parts, or less than 30 mass parts. By being such a scope, there is a good tendency of balance between electrical characteristics and curing reactivity.

The maleimides may be used alone or in combination of two or more. When two or more maleimides are used, the total amount is preferably within the above range.

Furthermore, the above-mentioned polymerization initiator and photopolymerization initiator may also be included. Examples of the photopolymerization initiator include benzoins such as benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin propyl ether, and benzoin isobutyl ether; acetophenones such as acetophenone, 2,2-diethoxy-2-phenylacetophenone, 2,2-diethoxy-2-phenylacetophenone, 1,1-dichloroacetophenone, 2-hydroxy-2-methyl-phenylpropane-1-one, diethoxyacetophenone, 1-hydroxycyclohexyl phenyl ketone, and 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropane-1-one; and 2-ethylanthracene. Anthraquinones such as quinone, 2-tert-butylanthraquinone, 2-chloroanthraquinone, and 2-amylanthraquinone; thioxanthones such as 2,4-diethylthioxanthone, 2-isopropylthioxanthone, and 2-chlorothioxanthone; ketals such as acetophenone dimethyl ketal and benzil dimethyl ketal; benzophenones such as benzophenone, 4-benzoyl-4'-methyldiphenyl sulfide, and 4,4'-dimethylaminobenzophenone; phosphine oxides such as 2,4,6-trimethylbenzoyldiphenylphosphine oxide and bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide, etc.

These may be used alone or in combination of two or more.

The copolymer composition of the present invention may not contain a crosslinking agent (curing agent), and may not contain a crosslinking agent (curing agent) and a curing accelerator. For example, when the above-mentioned copolymer contains a dicyclopentenyl group, self-crosslinking can be performed even without using a crosslinking agent or a curing accelerator. Therefore, it is not necessary to add extra components, and electrical properties can be improved.

In the copolymer composition of the present invention, the copolymer content is preferably 10% by mass or more, more preferably 25% by mass or more, and further preferably 40% by mass or more, relative to 100% by mass of the solid content, and may be 100% by mass or less, or 80% by mass or less.

The copolymer composition of the present invention may contain a flame retardant, an inorganic filler, a silane coupling agent, a release agent, a pigment, an emulsifier and the like.

The copolymer composition of the present invention may contain various additives according to the required properties. Examples of the additives include pigment dispersants, defoamers, leveling agents, UV absorbers, light stabilizers, thickeners, adhesion improvers, matting agents, and the like.

From the viewpoint of thermosetting properties, the gel fraction of the copolymer composition of the present invention is preferably 30% or more, more preferably 35% or more, further preferably 40% or more, and particularly preferably 50% or more.

In addition, the said gel fraction is a value measured by the method described in the Example mentioned later.

The method for preparing the copolymer composition of the present invention is not particularly limited, and examples thereof include a method of mixing a solution or dispersion of the copolymer with other components.

The copolymer composition of the present invention can be suitably used as a resin layer of a laminate having a substrate and a resin layer disposed on the substrate, and can be particularly suitably used as a resin layer of a metal-clad laminate. In addition, it can also be used for a resin for powder coatings, a resin for optical applications, and a resist material. The present invention also relates to a film comprising the above copolymer. The present invention also relates to a laminate, which is a laminate having a substrate and a resin layer disposed on the above substrate, wherein the above resin layer comprises the above copolymer.

The copolymer composition of the present invention is a metal-clad laminate having a metal foil and a resin layer disposed on the metal foil, and the resin layer can be suitably used for a metal-clad laminate formed by the copolymer composition of the present invention. The resin layer can be formed by curing the copolymer composition of the present invention. The present invention also relates to a metal-clad laminate, which is a metal-clad laminate having a metal foil and a resin layer disposed on the metal foil, wherein the resin layer contains the copolymer.

The metal-clad laminate comprises a metal foil and a resin layer. The resin layer has excellent insulation properties and functions as a base material of the metal-clad laminate.

Examples of the metal foil include metal foils made of copper, aluminum, iron, nickel, chromium, molybdenum, tungsten, zinc or alloys thereof, preferably copper foil. In addition, for the purpose of improving the adhesive force, the metal foil may be subjected to a chemical or mechanical surface treatment such as plate walling, nickel plating, copper-zinc alloy plating, or aluminum alkoxide, aluminum chelate, or silane coupling agent.

The metal-clad laminate may further include other layers as long as it includes the metal foil and the resin layer. The metal foil and the resin layer may each be one type or two or more types.

The metal-clad laminate may further include a second resin layer disposed on the resin layer (hereinafter referred to as the "first resin layer"). That is, the metal-clad laminate may be sequentially laminated with a metal foil, a first resin layer, and a second resin layer. In addition to serving as a base material, the first resin layer may also serve as an adhesive layer for bonding the metal foil to the second resin layer.

In addition, in the metal-clad laminate, the first resin layer may be provided on a surface of the metal foil different from the surface on which the first resin layer is provided (the surface on the opposite side). That is, the metal-clad laminate may be laminated in the order of the first resin layer, the metal foil, and the first resin layer, or in the order of the first resin layer, the metal foil, the first resin layer, and the second resin layer.

The second resin layer may be made of a resin used in conventional printed circuit boards. The second resin layer is preferably made of at least one resin selected from the group consisting of polyethylene terephthalate and polyimide, and is more preferably made of polyimide from the viewpoint of heat resistance.

As the first resin layer, a film having a thickness of 1 μm to 150 μm may be used. When the metal foil and the second adhesive layer are bonded to each other via the first resin layer, the thickness of the first resin layer after drying may be 1 μm to 100 μm.

As the second resin layer, a resin film having a thickness of 1 μm to 150 μm can be used.

The metal-clad laminate can be obtained by a production method including the step of bonding a metal foil and a film composed of the copolymer composition to obtain a metal-clad laminate.

As the bonding method, a method of laminating a metal foil and a film made of the copolymer composition and then performing thermocompression bonding at 50°C to 300°C using a heating press is preferred.

The production method may further include a step of molding the copolymer composition to obtain a film composed of the copolymer.

As the molding method, there can be mentioned melt extrusion molding, solvent casting, spraying and the like, without particular limitation. The above copolymer composition may contain an organic solvent, a curing agent, etc., and may also contain a curing accelerator, a pigment dispersant, a defoaming agent, a leveling agent, a UV absorber, a light stabilizer, a thickener, a close fit improver, a matting agent, etc.

The metal-clad laminate can also be obtained by a production method including the step of applying the copolymer composition on a metal foil to form a first resin layer.

The manufacturing method may also include the following step after the step of forming the first resin layer: further bonding a resin film to form a second resin layer on the first resin layer to obtain a metal-clad laminate having a metal foil and the first and second resin layers. The resin film may be a film composed of a resin suitable for forming the second resin layer.

As a method for bonding the resin films, a method of performing thermocompression bonding at 50° C. to 300° C. using a heating press machine is preferred.

In the above-mentioned production method, as a method for applying the composition for forming the first resin layer to the metal foil, there can be mentioned brush coating, dip coating, spray coating, comma coating, knife coating, die coating, die lip coating, roll coater coating, curtain coating, etc. After the composition is applied, it can be cured by drying at 25°C to 200°C for 1 minute to 1 week in a hot air drying furnace or the like.

The metal-clad laminate can also be produced by a production method including the following steps: a step of applying the copolymer composition to a resin film that becomes a second resin layer to form a first resin layer; and a step of bonding a metal foil to the first resin layer of a laminate consisting of a first resin layer and a second resin layer obtained by the forming step to obtain a metal-clad laminate having a metal foil and the first and second resin layers. The resin film may be a film consisting of a resin suitable for forming the second resin layer.

As a method for applying the composition for forming the first resin layer to the resin film, there can be mentioned brush coating, dip coating, spray coating, comma coating, knife coating, die coating, die lip coating, roll coater coating, curtain coating, etc. After the composition is applied, it can be cured by drying at 25° C. to 200° C. for 1 minute to 1 week in a hot air drying furnace or the like.

In the above-mentioned manufacturing method, as a method for bonding the metal foil to the first resin layer of a laminate composed of a first resin layer and a second resin layer, the following method is preferred: after overlapping the laminate composed of the first resin layer and the second resin layer and the metal foil in the manner in which the first resin layer of the laminate and the metal foil are bonded, hot pressing is performed at 50°C to 300°C using a heating press.

The metal-clad laminate can be applied to a printed circuit board having a pattern circuit formed by etching the metal foil of the metal-clad laminate. The present invention also relates to a printed circuit board, characterized in that it has a pattern circuit formed by etching the metal foil of the metal-clad laminate. The printed circuit board can be a flexible substrate or a rigid substrate, but is preferably a rigid substrate.

The printed circuit board may include a cover film on the metal-clad laminate, and the cover film may be bonded to the metal-clad laminate via the resin layer.

The etching method is not limited, and a conventionally known method can be used. In addition, the pattern circuit is not limited, and any pattern circuit printed circuit can be used.

The use of the printed circuit board is not limited. For example, since the printed circuit board has a resin layer with a low dielectric constant and a low dielectric loss tangent, it can also be used for printed circuit boards used in applications with high bandwidths such as 4G (37.5 Mbps) and 5G (several G to 20 Gbps).

Example

Next, the present invention will be described with reference to examples, but the present invention is not limited to these examples.

Hereinafter, the present invention will be described in more detail by way of examples.

The physical properties described in this specification were measured by the following measurement methods.

(1) NMR analysis

Measuring device: NMR measuring device manufactured by VARIAN

1H-NMR measurement conditions: 400 MHz (tetramethylsilane = 0 ppm)

(2) Elemental analysis (determination of fluorine content (mass %))

Measuring device: Automatic sample combustion device (AQF-100 manufactured by Mitsubishi Chemical Corporation) with built-in ion chromatograph (ICS-1500 Ion Chromatography System manufactured by DIONEX Corporation)

Sample 3mg

(3) Molecular weight

Measuring device: Shodex GPC-104 manufactured by Showa Denko K.K.

Measurement conditions: Tetrahydrofuran was used as the eluent, and polystyrene with a known molecular weight was used as the molecular weight standard sample.

(4) Glass transition temperature

The glass transition temperature and the crystalline melting point were determined by a midpoint method based on heat absorption in the second run using a DSC measuring apparatus manufactured by METLER TOLEDO in accordance with ASTM E1356-98.

Measurement conditions

Heating rate: 20℃/min

Sample volume: 10 mg

Thermal cycle: -50℃～300℃, heating, cooling, heating

(5) Relative dielectric constant and dielectric loss tangent

The film of the copolymer prepared in the synthesis example was produced by vacuum hot pressing. The relative dielectric constant and dielectric loss tangent of the produced film (sample F) were measured as follows.

The changes in the resonant frequency and Q value of the sample F prepared above were measured using a network analyzer using a cavity resonator, and the dielectric loss tangent (tanδ) at 12 GHz was calculated according to the following formula. The cavity resonator method was performed according to Professor Kobayashi of Saitama University [Non-destructive measurement of the complex dielectric constant of dielectric slab materials based on the cavity resonator method MW87-53].

tanδ＝(1/Qu)×{1+(W2/W1)}-(Pc/ωW1)

[Number 1]

XtanX＝(L/2M)YcosY

P _c =P ₁ +P ₂ +P ₃

The symbols in the formula are as follows.

D: Cavity resonator diameter (mm)

M: Single-side length of cavity resonator (mm)

L: Sample length (mm)

c: speed of light (m/s)

Id: Attenuation (dB)

F0: Resonance frequency (Hz)

F1: The high frequency at which the attenuation from the resonance point is 3dB (Hz)

F2: Low frequency frequency at which the attenuation from the resonance point is 3dB (Hz)

ε0: Vacuum dielectric constant (H/m)

εr: relative dielectric constant of the sample

μ0: vacuum magnetic permeability (H/m)

Rs: Effective surface resistance taking into account the surface roughness of the conductor cavity (Ω)

J0: -0.402759

J1: 3.83171

(6) Evaluation of solvent solubility

30 g of methyl ethyl ketone was weighed into a 100 ml sample bottle with respect to 20 g of the copolymer prepared in the synthesis example, and the mixture was shaken and mixed, and the solubility was visually confirmed.

(7) Thermosetting evaluation (gel fraction)

2 g of the solution prepared in the above solvent solubility evaluation or the cured composition using the copolymer and the crosslinking agent is taken into an aluminum cup and heated and dried for 1 hour at each set firing temperature to obtain a thermally cured product. Take out the cured product and wrap it with a 400-mesh metal mesh that has been weighed in advance. Add 25 ml of methyl ethyl ketone and the cured product wrapped with the metal mesh to a 50 ml sample tube, and immerse the cured product in methyl ethyl ketone for 24 hours. Then, take out the metal mesh, dry it, measure the mass after drying, and calculate the mass of the dried cured product after immersion in methyl ethyl ketone.

The gel fraction was calculated as: mass of the dried solidified product after immersion in methyl ethyl ketone/mass of the solidified product before immersion in methyl ethyl ketone×100.

(8) Thermal curing temperature

The thermal curing temperature is the temperature of the peak top of the exothermic peak observed when measuring using a DSC measuring device, or the temperature of the peak top of the exothermic peak observed in the temperature range where the weight loss is less than 1% by heating 10 mg of the sample from room temperature at a heating rate of 10°C/min using a differential thermal/thermogravimetric measuring device [TG-DTA] (trade name: TG/DTA7200, manufactured by Hitachi High-Technologies Corporation) is taken as the thermal curing temperature.

(9) Linear expansion rate

A film (sample sheet) of the copolymer prepared in the Synthesis Example was prepared, and the linear expansion coefficient (linear expansion coefficient) was measured as follows.

The linear expansion coefficient of the film was determined by performing TMA measurement in the following compression mode using TMA-7100 (manufactured by Hitachi High-Technologies Corporation).

[Tensile mode measurement]

As a sample piece, an extruded film cut into a length of 10 mm, a width of 10 mm, and a thickness of 760 μm was used. The linear expansion coefficient was determined from the displacement of the sample at 30° C. to 200° C. at a heating rate of 2° C./min while being compressed with a load of 49 mN.

<Synthesis of Copolymer>

Synthesis Example 1

Into a 300ml four-necked flask, add 100g of methyl isobutyl ketone, 16g of styrene, 24g of dicyclopentenyl vinyl ether, 24g of cyclohexylmaleimide (glass transition temperature of homopolymer 300°C), and 0.8g of 2,4-diphenyl-4-methyl-1-pentene. Set the internal temperature to 70°C, add 2g of tert-butyl peroxypivalate, and react for 3 hours. After cooling the reaction container, add a large amount of methanol at room temperature to precipitate the copolymer. Wash the obtained copolymer with methanol, filter and dry it to obtain a copolymer.

According to NMR analysis, the composition of the obtained copolymer was 41 mol % of a structure derived from styrene, 15 mol % of a structure derived from dicyclopentenyl vinyl ether, and 44 mol % of a structure derived from cyclohexylmaleimide.

According to molecular weight analysis, the number average molecular weight (Mn) was 16,000, and the weight average molecular weight (Mw) was 41,000. The glass transition temperature (Tg) was 180°C.

As a result of DSC measurement up to 250°C, an exothermic peak was confirmed from around 190°C to 250°C.

Synthesis Example 2

Into a 300 ml four-necked flask, 60 g of methyl isobutyl ketone, 11 g of styrene, 14 g of dicyclopentadiene, and 5 g of cyclohexylmaleimide were added. The internal temperature was set to 90°C, 2 g of tert-butyl peroxy-2-ethylhexanoate was added, and the reaction was allowed to proceed for 3 hours. After the reaction vessel was cooled, the reaction mixture was added to a large amount of methanol at room temperature to precipitate a copolymer. The obtained copolymer was washed with methanol, filtered, and dried to obtain a copolymer.

According to elemental analysis and NMR analysis, the composition of the obtained copolymer was 60 mol % of a structure derived from styrene, 6 mol % of a structure derived from dicyclopentadiene, and 34 mol % of a structure derived from cyclohexylmaleimide.

According to molecular weight analysis, the number average molecular weight (Mn) was 14,000, and the weight average molecular weight (Mw) was 31,000. The glass transition temperature (Tg) was 145°C.

(As a result of DSC measurement up to 200° C., no exothermic peak was confirmed).

Synthesis Example 3

Into a 300ml four-necked flask, 95g of methyl isobutyl ketone, 12g of styrene, 15g of dicyclopentadiene, 20g of cyclohexylmaleimide, 18g of 1,2,2-trifluorovinylbenzene, and 4g of 2,4-diphenyl-4-methyl-1-pentene were added. The internal temperature was set to 70°C, 2g of tert-butyl peroxypivalate was added, and the reaction was carried out for 3 hours. After the reaction vessel was cooled, the reaction mixture was added into a large amount of methanol at room temperature to precipitate the copolymer. The obtained copolymer was washed with methanol, filtered, and dried to obtain a copolymer.

According to elemental analysis and NMR analysis, the composition of the obtained copolymer was: 6 mol% of the structure derived from 1,2,2-trifluorovinylbenzene (trifluorostyrene), 59 mol% of the structure derived from styrene, 5 mol% of the structure derived from dicyclopentadiene, and 30 mol% of the structure derived from cyclohexylmaleimide.

According to molecular weight analysis, the number average molecular weight (Mn) was 14,000, and the weight average molecular weight (Mw) was 34,000. The glass transition temperature (Tg) was 161° C. As a result of elemental analysis, the fluorine content was 3.4% by mass.

As a result of DSC measurement up to 200°C, an exothermic peak was confirmed from around 170°C to around 200°C.

Synthesis Example 4

Into a 300ml four-necked flask, add 100g of methyl isobutyl ketone, 35g of dicyclopentenyl vinyl ether, 18g of cyclohexyl maleimide, and 2g of 2,4-diphenyl-4-methyl-1-pentene. Set the internal temperature to 70°C, add 1g of tert-butyl peroxy-2-ethylhexanoate, and react for 3 hours. After cooling the reaction vessel, add a large amount of methanol at room temperature to precipitate the copolymer. Wash the obtained copolymer with methanol, filter, and dry to obtain a copolymer.

According to elemental analysis and NMR analysis, the composition of the obtained copolymer was 46 mol % of a structure derived from dicyclopentenyl vinyl ether and 54 mol % of a structure derived from cyclohexylmaleimide.

According to molecular weight analysis, the number average molecular weight (Mn) was 4500, and the weight average molecular weight (Mw) was 7800. The glass transition temperature (Tg) was 205°C.

As a result of the DSC measurement, an exothermic peak was confirmed from 160°C to around 240°C.

Synthesis Example 5

Into a 300ml four-necked flask, add 100g of methyl isobutyl ketone, 29g of dicyclopentadiene, 18g of cyclohexylmaleimide, and 2g of 2,4-diphenyl-4-methyl-1-pentene. Set the internal temperature to 70°C, add 1g of tert-butyl peroxypivalate, and react for 3 hours. After cooling the reaction vessel, add a large amount of methanol at room temperature to precipitate the copolymer. Wash the obtained copolymer with methanol, filter, and dry to obtain a copolymer.

According to elemental analysis and NMR analysis, the composition of the obtained copolymer was 36 mol % of a structure derived from dicyclopentadiene and 64 mol % of a structure derived from cyclohexylmaleimide.

According to molecular weight analysis, the number average molecular weight (Mn) was 2000, and the weight average molecular weight (Mw) was 3000. The glass transition temperature (Tg) was 225°C.

As a result of DSC measurement up to 220°C, an exothermic peak was confirmed in the vicinity of 180°C to 220°C.

The polymer compositions, physical properties, etc. of the polymers prepared in Synthesis Examples 1 to 5 and the films of copolymers prepared using the polymers were measured and evaluated. The results are shown in Table 1.

In addition, the gel fractions of the polymers produced in Synthesis Examples 1 to 5 were measured for the cured products produced at the firing temperatures described in Table 1. The results are described in Table 1.

<Preparation of Copolymer Composition>

According to the proportions in Table 2, each curing composition was prepared by mixing a crosslinking agent A solution (4,4'-diphenylmethanebismaleimide acetone solution (concentration 3 mass%)) or a crosslinking agent B solution (N,N'-(2,2,4-trimethylhexane-1,6-diyl)bismaleimide methyl ethyl ketone solution (concentration 10 mass%)) with a MEK (methyl isobutyl ketone) solution (solid content concentration 40 mass% (polymer solution)) of the polymer prepared in Synthesis Examples 1 to 3. The prepared composition was fired at the firing temperature described in Table 2 to obtain a cured product, and the gel fraction thereof was measured. The results are described in Table 2.

[Table 2]

From Table 2, it can be confirmed that the curing temperature can be lowered by adding a cross-linking agent.

<Synthesis of Copolymer>

Synthesis Example 6

Into a 300 ml four-necked flask, 120 parts by mass of methyl isobutyl ketone, 14 parts by mass of styrene, 40 parts by mass of cyclohexyl maleimide, 15 parts by mass of dicyclopentenyl vinyl ether, and 6 parts by mass of bis-2-ethylhexyl fumarate were added. The internal temperature was set to 85°C, 0.4 parts by mass of tert-butyl peroxy-2-ethylhexanoate was added, and the reaction was carried out for 3 hours. After the reaction vessel was cooled, the reaction mixture was put into a large amount of methanol at room temperature to precipitate the copolymer. The obtained copolymer was washed with methanol, filtered, and dried to obtain a copolymer.

According to NMR analysis, the composition of the obtained copolymer was: 30 mol% of a structure derived from styrene, 11 mol% of a structure derived from dicyclopentenyl vinyl ether, 56 mol% of a structure derived from cyclohexylmaleimide, and 3 mol% of a structure derived from bis-2-ethylhexyl fumarate.

According to the molecular weight analysis, the number average molecular weight (Mn) was 25728, and the weight average molecular weight (Mw) was 187116. The glass transition temperature (Tg) was 205°C.

As a result of TG-DTA measurement up to 600°C, an exothermic peak was confirmed in the range of approximately 190°C to 250°C.

Synthesis Example 7

Into a 300 ml four-necked flask, 120 parts by mass of methyl isobutyl ketone, 23 parts by mass of styrene, 40 parts by mass of cyclohexylmaleimide, 13 parts by mass of dicyclopentadiene, and 6 parts by mass of bis-2-ethylhexyl fumarate were added. The internal temperature was set to 85°C, 0.4 parts by mass of tert-butyl peroxy-2-ethylhexanoate was added, and the reaction was carried out for 3 hours. After the reaction vessel was cooled, the reaction mixture was put into a large amount of methanol at room temperature to precipitate the copolymer. The obtained copolymer was washed with methanol, filtered, and dried to obtain a copolymer.

According to NMR analysis, the composition of the obtained copolymer was: 40 mol% of a structure derived from styrene, 5 mol% of a structure derived from dicyclopentadiene, 52 mol% of a structure derived from cyclohexylmaleimide, and 3 mol% of a structure derived from bis-2-ethylhexyl fumarate.

According to the molecular weight analysis, the number average molecular weight (Mn) was 29862, and the weight average molecular weight (Mw) was 89407. The glass transition temperature (Tg) was 190°C.

As a result of TG-DTA measurement up to 600°C, an exothermic peak was confirmed in the range of approximately 190°C to 250°C.

Synthesis Example 8

Into a 300 ml four-necked flask, 120 parts by mass of methyl isobutyl ketone, 15.6 parts by mass of styrene, 40 parts by mass of cyclohexyl maleimide, 15 parts by mass of dicyclopentenyl vinyl ether, 6 parts by mass of bis-2-ethylhexyl fumarate, and 9 parts by mass of trifluorostyrene were added. The internal temperature was set to 85°C, 0.2 parts by mass of tert-butyl peroxy-2-ethylhexanoate was added, and the reaction was carried out for 3 hours. After the reaction vessel was cooled, the reaction mixture was put into a large amount of methanol at room temperature to precipitate the copolymer. The obtained copolymer was washed with methanol, filtered, and dried to obtain a copolymer.

According to NMR analysis, the composition of the obtained copolymer is: 3 mol% of the structure derived from trifluorostyrene, 33 mol% of the structure derived from styrene, 9 mol% of the structure derived from dicyclopentenyl vinyl ether, 52 mol% of the structure derived from cyclohexylmaleimide, and 3 mol% of the structure derived from bis-2-ethylhexyl fumarate.

According to the molecular weight analysis, the number average molecular weight (Mn) was 38829, and the weight average molecular weight (Mw) was 249053. The glass transition temperature (Tg) was 195°C.

As a result of TG-DTA measurement up to 600°C, an exothermic peak was confirmed in the range of approximately 190°C to 250°C.

Synthesis Example 9

Into a 300 ml four-necked flask, 110 parts by mass of methyl isobutyl ketone, 7.8 parts by mass of styrene, 40 parts by mass of cyclohexylmaleimide, 11.7 parts by mass of dicyclopentadiene, and 10 parts by mass of 1-decene were added. The internal temperature was set to 85°C, 0.2 parts by mass of tert-butyl peroxy-2-ethylhexanoate was added, and the reaction was carried out for 3 hours. After the reaction vessel was cooled, the reaction mixture was put into a large amount of methanol at room temperature to precipitate the copolymer. The obtained copolymer was washed with methanol, filtered, and dried to obtain a copolymer.

According to NMR analysis, the composition of the obtained copolymer was 16 mol % of a structure derived from styrene, 8 mol % of a structure derived from dicyclopentadiene, 66 mol % of a structure derived from cyclohexylmaleimide, and 10 mol % of a structure derived from 1-decene.

According to the molecular weight analysis, the number average molecular weight (Mn) was 26910, and the weight average molecular weight (Mw) was 86654. The glass transition temperature (Tg) was 227°C.

As a result of TG-DTA measurement up to 600°C, an exothermic peak was confirmed in the range of approximately 190°C to 250°C.

Synthesis Example 10

Into a 300 ml four-necked flask, 120 parts by mass of methyl isobutyl ketone, 18 parts by mass of styrene, 40 parts by mass of cyclohexylmaleimide, 12 parts by mass of dicyclopentadiene, and 6 parts by mass of limonene were added. The internal temperature was set to 85°C, 0.2 parts by mass of tert-butyl peroxy-2-ethylhexanoate was added, and the reaction was carried out for 3 hours. After the reaction vessel was cooled, the reaction mixture was put into a large amount of methanol at room temperature to precipitate the copolymer. The obtained copolymer was washed with methanol, filtered, and dried to obtain a copolymer.

According to NMR analysis, the composition of the obtained copolymer was 32 mol % of a structure derived from styrene, 5 mol % of a structure derived from dicyclopentadiene, 58 mol % of a structure derived from cyclohexylmaleimide, and 5 mol % of a structure derived from limonene.

According to the molecular weight analysis, the number average molecular weight (Mn) was 22677, and the weight average molecular weight (Mw) was 85014. The glass transition temperature (Tg) was 220°C.

As a result of TG-DTA measurement up to 600°C, an exothermic peak was confirmed in the range of approximately 190°C to 250°C.

Synthesis Example 11

Into a 300 ml four-necked flask, 120 parts by mass of methyl isobutyl ketone, 18 parts by mass of styrene, 40 parts by mass of cyclohexylmaleimide, 12 parts by mass of dicyclopentadiene, and 6 parts by mass of 2-ethylhexyl vinyl ether were added. The internal temperature was set to 85°C, 0.2 parts by mass of tert-butyl peroxy-2-ethylhexanoate was added, and the reaction was carried out for 3 hours. After the reaction vessel was cooled, the reaction mixture was put into a large amount of methanol at room temperature to precipitate the copolymer. The obtained copolymer was washed with methanol, filtered, and dried to obtain a copolymer.

According to NMR analysis, the composition of the obtained copolymer was 34 mol % of a structure derived from styrene, 4 mol % of a structure derived from dicyclopentadiene, 56 mol % of a structure derived from cyclohexylmaleimide, and 6 mol % of a structure derived from 2-ethylhexyl vinyl ether.

According to the molecular weight analysis, the number average molecular weight (Mn) was 5665, and the weight average molecular weight (Mw) was 10242. The glass transition temperature (Tg) was 206°C.

As a result of TG-DTA measurement up to 600°C, an exothermic peak was confirmed in the range of approximately 190°C to 250°C.

Synthesis Example 12

Into a 300 ml four-necked flask, 120 parts by mass of methyl isobutyl ketone, 19 parts by mass of styrene, 33 parts by mass of cyclohexylmaleimide, 9 parts by mass of dicyclopentadiene, and 10.3 parts by mass of N-dodecylmaleimide were added. The internal temperature was set to 85°C, 0.2 parts by mass of tert-butyl peroxy-2-ethylhexanoate was added, and the reaction was carried out for 3 hours. After the reaction vessel was cooled, the reaction mixture was put into a large amount of methanol at room temperature to precipitate the copolymer. The obtained copolymer was washed with methanol, filtered, and dried to obtain a copolymer.

According to NMR analysis, the composition of the obtained copolymer was: 43 mol % of a structure derived from styrene, 4 mol % of a structure derived from dicyclopentadiene, 43 mol % of a structure derived from cyclohexylmaleimide, and 10 mol % of a structure derived from N-dodecylmaleimide.

According to the molecular weight analysis, the number average molecular weight (Mn) was 35618, and the weight average molecular weight (Mw) was 124375. The glass transition temperature (Tg) was 162°C.

As a result of TG-DTA measurement up to 600°C, an exothermic peak was confirmed in the range of approximately 170°C to 250°C.

Synthesis Example 13

Into a 300 ml four-necked flask, 100 parts by mass of methyl isobutyl ketone, 16.2 parts by mass of styrene, 25.3 parts by mass of N-benzylmaleimide, 12 parts by mass of dicyclopentadiene, and 2.5 parts by mass of 1-decene were added. The internal temperature was set to 85°C, 0.2 parts by mass of tert-butyl peroxy-2-ethylhexanoate was added, and the reaction was carried out for 3 hours. After the reaction vessel was cooled, the reaction mixture was put into a large amount of methanol at room temperature to precipitate the copolymer. The obtained copolymer was washed with methanol, filtered, and dried to obtain a copolymer.

According to NMR analysis, the composition of the obtained copolymer was 41 mol % of a structure derived from styrene, 3 mol % of a structure derived from dicyclopentadiene, 52 mol % of a structure derived from N-benzylmaleimide, and 4 mol % of a structure derived from 1-decene.

According to the molecular weight analysis, the number average molecular weight (Mn) was 24540, and the weight average molecular weight (Mw) was 98036. The glass transition temperature (Tg) was 162°C.

As a result of TG-DTA measurement up to 600°C, an exothermic peak was confirmed in the range of approximately 170°C to 250°C.

The polymer compositions, physical properties, etc. of the polymers prepared in Synthesis Examples 6 to 13 and the films of copolymers prepared using the polymers were measured and evaluated. The results are shown in Table 3.

In addition, the gel fractions of the polymers produced in Synthesis Examples 6 to 13 were measured for the cured products produced at the firing temperatures described in Table 3. Table 3 shows the results.

Embodiment 18

10 parts by mass of the polymer obtained in Synthesis Example 9, 2 parts by mass of polybutadiene (B-2000 manufactured by Nippon Soda Co., Ltd.), and 0.1 parts by mass of an initiator (PERCUMYL D-40 manufactured by NOF Corporation) were dissolved in 48 parts by mass of methyl isobutyl ketone to prepare a copolymer composition.

After impregnating the obtained copolymer composition into glass cloth, the prepreg was prepared by heating and drying at 100°C for about 3 minutes. Specifically, the glass cloth was #1035 type, E glass (density: 2.6 g/ ^cm3 , weight per ^1m2 : 29.1 g, glass cloth thickness: 29 μm, relative dielectric constant: 2.66, dielectric loss tangent: 0.0048) manufactured by Asahi Kasei Corporation. At this time, the content (resin content) of the copolymer composition was adjusted to about 40% by mass.

Next, the four prepregs were overlapped, heated and pressurized for 120 minutes at a temperature of 250°C and a pressure of 2.44MPa (megapascals) to make a test body. The thickness of the test body was 132.2μm. The relative dielectric constant and dielectric loss tangent of the test body were measured, and the results showed that the relative dielectric constant was 3.37, the dielectric loss tangent was 0.00522, and the gel fraction was 67%. The relative dielectric constant and dielectric loss tangent of the cured polymer were calculated by the following formula from the measured values of the relative dielectric constant and dielectric loss tangent of the test body, and the relative dielectric constant was 2.55 and the dielectric loss tangent was 0.00145.

Test body dielectric loss tangent = glass cloth dielectric loss tangent × glass cloth vol%/100 + solidified polymer dielectric loss tangent × solidified polymer vol%/100

Glass cloth dielectric loss tangent = glass cloth fiber dielectric loss tangent × glass cloth fiber vol%/100 + air dielectric loss tangent × air vol%/100

Glass cloth vol% = weight of glass cloth per ^m2 / density of glass cloth / thickness of prepreg per sheet in the test body after impregnation

Cured polymer vol%=1-glass cloth vol%.

Claims (23)

1. A copolymer comprising: an aromatic vinyl monomer unit, a monomer unit containing a crosslinking group, and a monomer unit providing a homopolymer with a glass transition temperature of 150°C or higher. The copolymer according to claim 1 , which is a thermosetting resin. 3 . The copolymer according to claim 1 , wherein the aromatic vinyl monomer unit is a styrene unit. 4 . The copolymer according to claim 1 , wherein the crosslinking group-containing monomer unit comprises a diene monomer unit having an alicyclic structure. 5 . 5 . The copolymer according to claim 1 , wherein the crosslinking group-containing monomer unit comprises a monomer unit having a dicyclopentenyl structure. 6 . The copolymer according to claim 1 , wherein the crosslinking group-containing monomer unit comprises at least one selected from the group consisting of a dicyclopentadiene unit and a dicyclopentenyl vinyl ether unit. 7 . The copolymer according to claim 1 , wherein the monomer unit providing a homopolymer having a glass transition temperature of 150° C. or higher comprises a maleimide unit. 8 . The copolymer according to claim 7 , wherein the maleimide-based unit comprises at least one selected from the group consisting of an N-cyclohexylmaleimide unit and an N-phenylmaleimide unit. The copolymer according to any one of claims 1 to 8, further comprising a fluorine-containing monomer unit which provides a C-F bond to the main chain. 10 . The copolymer according to claim 1 , which has a glass transition temperature of 140° C. or higher. 11. The copolymer according to any one of claims 2 to 10, which has a thermal curing temperature of 240°C or less. 12 . The copolymer according to claim 1 , which is soluble in methyl ethyl ketone or toluene. 13 . The copolymer according to claim 1 , wherein the crosslinking group-containing monomer unit accounts for 1 mol % or more of all polymerized units constituting the copolymer. 14 . The copolymer according to claim 1 , wherein the monomer unit that provides a homopolymer having a glass transition temperature of 150° C. or higher accounts for 5 mol % or more of all polymerized units constituting the copolymer. 15 . The copolymer according to claim 1 , which has a dielectric loss tangent of 0.0030 or less. 16 . A copolymer composition comprising the copolymer according to claim 1 and a solvent. 17 . The copolymer composition according to claim 16 , comprising a polymer containing two or more vinyl groups or a monomer component containing two or more vinyl groups. 18. The copolymer composition according to claim 16 or 17, comprising a photopolymerization initiator. 19. The copolymer composition according to any one of claims 16 to 18, which has a gel fraction of 30% or more. 20. A film comprising the copolymer according to any one of claims 1 to 15. 21 . A laminate comprising a substrate and a resin layer provided on the substrate, wherein the resin layer comprises the copolymer according to claim 1 . 22 . A metal-clad laminate comprising a metal foil and a resin layer provided on the metal foil, wherein the resin layer comprises the copolymer according to claim 1 . 23. A printed circuit board comprising a pattern circuit formed by etching the metal foil of the metal-clad laminate according to claim 22.