Olefin-aromatic vinyl compound-aromatic polyene copolymer, method for producing the same, composition containing the same, and cured products thereof

Abstract

To provide a novel olefin-aromatic vinyl compound-aromatic polyene copolymer and a method for producing the same, the copolymer being nonvolatile, having a low molecular weight, and enabling realization of a high crosslink density.SOLUTION: An olefin-aromatic vinyl compound-aromatic polyene copolymer has a number average molecular weight (Mn) of 500 or more and less than 12,000, contains an olefin monomer unit, an aromatic vinyl compound monomer unit, and an aromatic polyene monomer unit, and has aromatic vinyl groups derived from the aromatic polyene monomer unit, wherein the number of the aromatic vinyl groups is two or more per the number average molecular weight (Mn), and the number average molecular weight (Mn) per the aromatic vinyl group is 500 or less.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to an olefin-aromatic vinyl compound-aromatic polyene copolymer and a method for producing the same, a composition containing the crosslinkable copolymer, and a cured product thereof, an electrical insulating material, etc. [Background technology]

[0002] As communication frequencies shift to the gigahertz band and higher, particularly the millimeter-wave band of 30 gigahertz and above, the low dielectric properties required of insulating materials used in multilayer substrates equipped with CCLs and FCCLs are becoming increasingly sophisticated. Fluorine-based resins such as perfluoroethylene are characterized by low dielectric constants, low dielectric loss, and high heat resistance, but they are poor in moldability and film formability, and also have issues with adhesion to copper foil in wiring, making them difficult to apply to multilayer substrates.

[0003] Therefore, hydrocarbon-based resins and monomers with inherently low dielectric properties have attracted attention. To convert hydrocarbon-based resins, which are essentially thermoplastic resins, into curable resins, it is necessary to introduce polymerizable or crosslinkable functional groups. However, functional groups that react to radicals or heat often contain oxygen or nitrogen atoms and are generally highly polar, raising concerns about deterioration of dielectric properties. Therefore, hydrocarbon-based resins and monomers with functional groups composed solely of hydrocarbons have attracted attention. 1,2-Polybutadiene (co)polymers have a high vinyl group content but have issues with their dielectric properties. Furthermore, the vinyl groups bonded to their aliphatic backbones have low reactivity. Therefore, hydrocarbon-based resins and monomers containing highly reactive aromatic vinyl groups as functional groups have attracted particular attention. For example, divinylbenzene (DVB) and bisvinylphenylethane (BVPE), which are compounds containing two aromatic vinyl groups, have been proposed (see Patent Document 1). The vinyl group equivalent weight (molecular weight / number of vinyl groups) of divinylbenzene is 65, and that of bisvinylphenylethane is 117. Because these vinyl group equivalents are small, adding these compounds to a curing composition can increase crosslink density. However, because divinylbenzene is volatile at room temperature, when used as a varnish in the manufacturing process of a cured product, for example, divinylbenzene is easily removed during the solvent removal process, making it difficult to consistently obtain a cured product with consistent physical properties. On the other hand, bisvinylphenylethane has a relatively large molecular weight and is nonvolatile at room temperature, making it easy to handle, but it is produced using an expensive intermolecular reaction, making it less economical.

[0004] Additionally, cured products have been proposed that consist of ethylene-olefin (aromatic vinyl compound)-aromatic polyene copolymers and nonpolar vinyl compound copolymers, which are hydrocarbon resins obtained using specific coordination polymerization catalysts (see Patent Documents 2 and 3). These techniques selectively copolymerize only one of the two vinyl groups in the aromatic polyene (divinylbenzene), preserving the remaining vinyl group, making it easy to obtain crosslinkable hydrocarbon copolymer macromonomers that have aromatic vinyl functional groups. Furthermore, cured products of the copolymers obtained using these techniques, as well as cured products of compositions of the copolymers with auxiliary materials, are characterized by low dielectric constants and low dielectric loss tangents. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2004-087639 [Patent Document 2] International Publication No. 2021-112087 [Patent Document 3] International Publication No. 2022-014599 Summary of the Invention [Problem to be solved by the invention]

[0006] However, the copolymers specifically disclosed in Patent Documents 2 and 3 are intended to have moldability when used as a varnish, for example, low viscosity and excellent impregnation properties, and there is room for improvement in the dielectric properties and high-temperature mechanical strength of the cured product using the copolymer.

[0007] The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide a novel olefin-aromatic vinyl compound-aromatic polyene copolymer that is nonvolatile, has a low molecular weight, and is capable of achieving a high crosslink density, as well as a method for producing the same. Another object of the present invention is to provide a novel olefin-aromatic vinyl compound-aromatic polyene copolymer that can produce a cured product having excellent dielectric properties and a high storage modulus, and a method for producing the same. Another object of the present invention is to provide a novel composition and a cured product thereof, which are obtained using the above-mentioned novel olefin-aromatic vinyl compound-aromatic polyene copolymer, as well as electrical insulating materials such as CCL substrates, FCCL substrates, interlayer insulating materials, antennas, and coverlays. [Means for solving the problem]

[0008] That is, the present invention provides various specific embodiments as shown below. <1> The number average molecular weight (Mn) is 500 or more and less than 12,000, The copolymer comprises an olefin monomer unit, an aromatic vinyl compound monomer unit, and an aromatic polyene monomer unit, having an aromatic vinyl group derived from the aromatic polyene monomer unit, the number of the aromatic vinyl groups per the number average molecular weight (Mn) is 2 or more, and the number average molecular weight (Mn) per aromatic vinyl group is 500 or less; Olefin-aromatic vinyl compound-aromatic polyene copolymer.

[0009] <2> The content of the olefin monomer unit is 1% by mass or more and 70% by mass or less, The total content of the aromatic vinyl compound monomer units and the aromatic polyene monomer units is 30% by mass or more and less than 99% by mass. <1> The olefin-aromatic vinyl compound-aromatic polyene copolymer according to claim 1.

[0010] <3> The olefin monomer unit contains at least an α-olefin having 3 or more carbon atoms, The content of the α-olefin having 3 or more carbon atoms is 30% by mass or more and 100% by mass or less based on the total amount of the olefin monomer units. <1> or <2> The olefin-aromatic vinyl compound-aromatic polyene copolymer according to claim 1.

[0011] <4> The olefin monomer unit is a single or multiple unit selected from α-olefins having 2 to 20 carbon atoms, or a combination of an α-olefin having 2 to 20 carbon atoms and a cyclic olefin having 5 to 20 carbon atoms. <1> ~ <3> The olefin-aromatic vinyl compound-aromatic polyene copolymer according to any one of the preceding claims.

[0012] <5> The olefin monomer unit is a combination of an α-olefin having 2 to 20 carbon atoms and a cyclic olefin having 5 to 20 carbon atoms. <1> ~ <3> The olefin-aromatic vinyl compound-aromatic polyene copolymer according to any one of the preceding claims.

[0013] <4> The total metal content is 1,500 ppm or less <1> ~ <5> The olefin-aromatic vinyl compound-aromatic polyene copolymer according to any one of the preceding claims. Merge.

[0014] <7> The boron content is 500 ppm or less <1> ~ <5> The olefin-aromatic vinyl compound-aromatic polyene copolymer according to any one of the preceding claims.

[0015] <8> <1> ~ <7> The olefin-aromatic vinyl compound-aromatic polyene copolymer according to any one of composition.

[0016] <9> Further containing a curing agent <8> The composition described in

[0017] <10> Further containing a radical crosslinkable monomer and / or a radical crosslinkable resin component <8> or <9> The composition described in

[0018] <11> <1> ~ <7> The olefin-aromatic vinyl compound-aromatic polyene copolymer according to any one of Hardened body.

[0019] <12> <11> The cured body according to claim 1, CCL substrate, FCCL substrate, interlayer insulation material, antenna, or coverlay.

[0020] <13> copolymerizing an olefin monomer, an aromatic vinyl compound monomer, and an aromatic polyene monomer in the presence of a coordination polymerization catalyst; synthesizing an olefin-aromatic vinyl compound-aromatic polyene copolymer having a number average molecular weight (Mn) of 500 or more and less than 12,000, comprising an olefin monomer unit, an aromatic vinyl compound monomer unit, and an aromatic polyene monomer unit, having aromatic vinyl groups derived from the aromatic polyene monomer units, wherein the number of the aromatic vinyl groups per number average molecular weight (Mn) is 2 or more, and the number average molecular weight (Mn) per aromatic vinyl group is 500 or less; A method for producing an olefin-aromatic vinyl compound-aromatic polyene copolymer.

[0021] <14> The coordination polymerization catalyst comprises a transition metal compound and a cocatalyst. <13> A method for producing the copolymer described in

[0022] <15> The transition metal compound includes a transition metal compound represented by the following general formula (1): <14> A method for producing the copolymer described in [ka] (In the formula, M is a central metal selected from the group consisting of zirconium, hafnium, and titanium. A and B each independently represent a group selected from the group consisting of a substituted or unsubstituted cyclopentaphenanthryl group, a substituted or unsubstituted benzoindenyl group, a substituted or unsubstituted cyclopentadienyl group, and a substituted or unsubstituted indenyl group. Y is a divalent group bonding to A and B, and is selected from the group consisting of a methylene group, a silylene group, an ethylene group, a germylene group, and a boron residue, which may further have a hydrogen atom or a hydrocarbon group having 1 to 15 carbon atoms (which may further contain 1 to 3 nitrogen atoms, oxygen atoms, sulfur atoms, phosphorus atoms, or silicon atoms) as a substituent, and these substituents may be different or the same. Furthermore, Y may have a cyclic structure. Each X is independently selected from the group consisting of a hydrogen atom, a halogen atom, an alkyl group having 1 to 15 carbon atoms, an aryl group having 6 to 10 carbon atoms, an alkylaryl group having 8 to 12 carbon atoms, a silyl group having a hydrocarbon substituent having 1 to 4 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, and a dialkylamide group having an alkyl substituent having 1 to 6 carbon atoms.

[0023] <16> The co-catalyst comprises a boron compound. <14> or <15> A method for producing the copolymer described in

[0024] <17> the olefin-aromatic vinyl compound-aromatic polyene copolymer contains a copolymerization component derived from an olefin monomer, the olefin monomer comprises an α-olefin having 3 or more carbon atoms; The content of the α-olefin having 3 or more carbon atoms is 30% by mass or more and 100% by mass or less relative to the total amount of the olefin monomers. <13> ~ <16> 10. A method for producing the copolymer according to claim 9. [Effects of the Invention]

[0025] According to one aspect of the present invention, a novel olefin-aromatic vinyl compound-aromatic polyene copolymer that is nonvolatile, has a low molecular weight, and can achieve a high crosslink density, and a method for producing the same can be realized. Furthermore, according to one aspect of the present invention, the use of the crosslinkable copolymer improves the handleability (nonvolatility, low viscosity, etc.) when used as a varnish, and also improves the moldability (impregnation ability, flowability, etc.) of the uncured composition. Furthermore, according to one aspect of the present invention, the use of the crosslinkable copolymer increases the crosslink density of the resulting cured product, thereby enabling the realization of a cured product having excellent dielectric properties and a high storage modulus. Furthermore, according to one aspect of the present invention, it is possible to improve the mechanical properties and mechanical strength at high temperatures, and it is also possible to reduce the coefficient of linear expansion (CTE). These features make it possible to provide novel electrical insulating materials for high frequency bands, such as CCL substrates, FCCL substrates, interlayer insulating materials, antennas, and coverlays. DETAILED DESCRIPTION OF THE INVENTION

[0026] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. However, the following embodiments are merely examples for explaining the present invention, and the present invention is not limited thereto. That is, the present invention can be implemented with any modifications within the scope of the gist thereof. In this specification, for example, the expression of a numerical range such as "1 to 100" includes both the lower limit "1" and the upper limit "100". The same applies to the expression of other numerical ranges.

[0027] In this specification, the term "sheet" also encompasses the concept of "film." Furthermore, the term "film" as used herein also encompasses the concept of "sheet." In this specification, the term "composition" encompasses the concept of "varnish." That is, a liquid composition is specifically referred to as a "varnish." In this specification, the term "interlayer insulating material" encompasses the concepts of a bonding sheet or interlayer adhesive. Among the constituent units in a copolymer, a constituent unit derived from an olefin monomer may be simply referred to as an olefin monomer unit or an olefin. The same applies to aromatic vinyl compound monomer units and aromatic polyene monomer units. Furthermore, the term "aromatic vinyl group" encompasses not only aromatic vinyl groups but also aromatic vinylene groups, with aromatic vinyl groups being preferred.

[0028] <Olefin-aromatic vinyl compound-aromatic polyene copolymer> The olefin-aromatic vinyl compound-aromatic polyene copolymer of the present embodiment (hereinafter, may be simply referred to as "the crosslinkable copolymer") has a number average molecular weight (Mn) of 500 or more and less than 12,000, contains olefin monomer units, aromatic vinyl compound monomer units, and aromatic polyene monomer units, has aromatic vinyl groups derived from the aromatic polyene monomer units, the number of the aromatic vinyl groups is 2 or more per number average molecular weight (Mn), and the number average molecular weight (Mn) per aromatic vinyl group is 500 or less.

[0029] The crosslinkable copolymer is a crosslinkable copolymer containing at least three copolymerized units, namely, an olefin monomer unit, an aromatic vinyl compound monomer unit, and an aromatic polyene monomer unit, and having a predetermined proportion of aromatic vinyl groups. The crosslinkable copolymer is also referred to as an "olefin-aromatic polyene copolymer containing an aromatic vinyl group," or alternatively, as an "olefin-aromatic polyene crosslinkable copolymer." In one embodiment, the crosslinkable copolymer can be an "olefin-aromatic vinyl group-containing olefin-aromatic polyene copolymer."

[0030] The number average molecular weight (Mn) of the crosslinkable copolymer is 500 or more and less than 12,000. In this specification, a number average molecular weight (Mn) of 500 or more and less than 12,000 means that the molecular weight, calculated as standard polystyrene, obtained by GPC (gel permeation chromatography) falls within that range. The viscosity of the crosslinkable copolymer measured in a 25% by mass toluene solution is preferably 5,000 mPa·s or less. Furthermore, the viscosity of the crosslinkable copolymer measured in a 50% by mass toluene solution is more preferably 5,000 mPa·s or less, and most preferably 3,000 mPa·s or less.

[0031] The number-average molecular weight (Mn) of the crosslinkable copolymer may be preferably 1,000 or more but less than 10,000, more preferably 1,000 or more but less than 8,000. The method for adjusting the molecular weight of the crosslinkable copolymer to fall within the above range can be any known method, and is not particularly limited. Examples include, but are not limited to, using a preferred coordination polymerization catalyst as specified herein as the catalyst used in synthesizing the crosslinkable copolymer, adjusting the monomer feed ratio during synthesis of the crosslinkable copolymer, and setting the copolymer composition range to a specific range. For example, the number-average molecular weight (Mn) of the crosslinkable copolymer can be adjusted by adjusting the content ratio of the olefin monomer or aromatic polyene monomer. Furthermore, when the olefin monomer used is a combination of ethylene and an α-olefin having 3 or more carbon atoms, the number-average molecular weight (Mn) of the crosslinkable copolymer can also be adjusted by adjusting the polymerization conditions, such as the monomer feed ratio, so that the content ratio of the α-olefin having 3 or more carbon atoms in the olefin monomer falls within the above range.

[0032] The crosslinkable copolymer contains an olefin monomer unit. The olefin monomer (olefin) is not particularly limited, but may be one or more selected from ethylene, α-olefins having 3 to 20 carbon atoms (preferably 3 to 15 carbon atoms, more preferably 4 to 12 carbon atoms), and cyclic olefins having 5 to 20 carbon atoms (preferably 5 to 15 carbon atoms, more preferably 5 to 12 carbon atoms). The olefin is preferably a compound composed of carbon and hydrogen atoms, substantially free of oxygen, nitrogen, and halogen atoms (i.e., a compound consisting of 99% or more by mass of carbon and hydrogen, preferably consisting only of carbon and hydrogen). Examples of α-olefins having 3 to 20 carbon atoms include propylene, 1-butene, 1-hexene, 1-octene, 1-decane, 1-dodecane, 4-methyl-1-pentene, and 3,5,5-trimethyl-1-hexene. Examples of cyclic olefins having 5 to 20 carbon atoms include norbornene, cyclopentene, and acenaphthylene. The olefin monomers can be used alone or in any combination and ratio of two or more. For example, the olefin monomer may be ethylene alone, an α-olefin having 3 to 20 carbon atoms alone, or a cyclic olefin alone. Alternatively, ethylene may be used in combination with an α-olefin having 3 to 20 carbon atoms, an α-olefin having 3 to 20 carbon atoms alone, or a cyclic olefin having 5 to 20 carbon atoms alone. Alternatively, ethylene may be used in combination with an α-olefin having 3 to 20 carbon atoms, an α-olefin having 3 to 20 carbon atoms alone, or a cyclic olefin having 5 to 20 carbon atoms alone. The crosslinkable copolymer and cured product containing the same advantageously have a lower dielectric constant and lower dielectric loss tangent than those not containing the olefin monomer units. Furthermore, the brittleness of the resulting cured product can be reduced, which is preferable. Among these, the olefin monomer preferably contains at least an α-olefin having 3 to 20 carbon atoms, or a combination of ethylene and an α-olefin having 3 to 20 carbon atoms.Alternatively, an α-olefin having from 2 to 20 carbon atoms may be used in combination with a cyclic olefin having from 5 to 20 carbon atoms, and more preferably, ethylene and a cyclic olefin having from 5 to 20 carbon atoms. The crosslinkable copolymer and a cured product containing the same have the advantage of being able to achieve a lower dielectric constant and a lower dielectric loss tangent by containing the above-mentioned olefin monomer units compared to products not containing the olefin monomer units. Furthermore, the inclusion of one or more α-olefins having from 2 to 20 carbon atoms suppresses the brittleness of the cured product containing the copolymer, and improves elongation and adhesion to copper foil.

[0033] The crosslinkable copolymer contains an aromatic polyene monomer unit. The aromatic polyene monomer (aromatic polyene) is not particularly limited, but examples thereof include polyenes having 10 to 20 carbon atoms (preferably 10 to 15 carbon atoms, more preferably 10 to 12 carbon atoms) and containing multiple vinyl and / or vinylene groups in the molecule. Preferred examples include ortho-, meta-, and para-divinylbenzenes, mixtures thereof, divinylnaphthalene, divinylanthracene, p-2-propenylstyrene, and p-3-butenylstyrene, which have an aromatic vinyl structure and are substantially free of oxygen, nitrogen, or halogen atoms and are composed of carbon and hydrogen atoms. Bifunctional aromatic vinyl compounds, such as 1,2-bis(vinylphenyl)ethane (abbreviated as BVPE), as described in JP 2004-087639 A, can also be used. These divinylbenzenes are referred to as "divinylbenzenes" in this specification. When divinylbenzenes are used as the aromatic polyene, the curing efficiency during curing treatment tends to be high and curing tends to be easy. The aromatic polyene monomers can be used alone or in any combination and ratio of two or more. Among these, ortho-, meta-, and para-divinylbenzenes, or mixtures thereof are preferred, and meta-divinylbenzene, para-divinylbenzene, or mixtures thereof are most preferred.

[0034] The crosslinkable copolymer contains an aromatic vinyl compound monomer unit. The aromatic vinyl compound monomer of the aromatic vinyl compound monomer unit has one aromatic vinyl group in its molecule. The aromatic vinyl (aromatic vinyl group) is not particularly limited, but is an aromatic vinyl having from 8 to 20 carbon atoms (preferably from 8 to 18 carbon atoms), such as styrene, para- or meta-ethylvinylbenzene, para-methylstyrene, para-isobutylstyrene, various vinylnaphthalenes, and various vinylanthracenes. The aromatic vinyl can be used alone or in any combination and ratio of two or more types. Commercially available divinylbenzene usually contains para- or meta-ethylvinylbenzene as an impurity, and copolymerization using this commercially available divinylbenzene may result in the unintentional inclusion of an aromatic vinyl compound monomer unit in the crosslinkable copolymer. In this specification, there may be cases where the aromatic vinyl compound monomer units also correspond to the above-mentioned aromatic polyene monomer units. In such cases, only the aromatic monovinyl compound monomer units will be regarded as aromatic vinyl compound monomer units, and the others will be regarded as aromatic polyene monomer units.

[0035] The number of aromatic vinyl groups contained in the crosslinkable copolymer is 2 or more per the above-mentioned number average molecular weight (Mn), and the number average molecular weight (Mn) per aromatic vinyl group is 500 or less. When the number of aromatic vinyl groups per number average molecular weight is 2 or more, crosslinking proceeds efficiently, and when the number average molecular weight per aromatic vinyl group is 500 or less, a high crosslink density can be achieved.

[0036] The number of aromatic vinyl groups possessed by the crosslinkable copolymer may be two or more per number-average molecular weight (Mn) of the crosslinkable copolymer, preferably 2.5 or more, and more preferably 3 or more. The upper limit is not particularly limited, but is, for example, 40 or less, preferably 30 or less, and more preferably 25 or less. Cured products obtained using the crosslinkable copolymer satisfying this condition have a higher crosslink density, thereby enabling improved mechanical properties and high-temperature mechanical strength. For example, a cured product of the crosslinkable copolymer alone or a cured product of a composition containing the crosslinkable copolymer can easily achieve a storage modulus at 280°C of 40 MPa or more, preferably 50 MPa or more, and more preferably 55 MPa or more. In particular, when blended in the same proportions, the crosslinkable copolymer can exhibit a higher crosslink density and a higher storage modulus (particularly at 280°C) than an olefin-aromatic vinyl compound-aromatic polyene copolymer having less than two aromatic vinyl groups per number-average molecular weight (Mn). Furthermore, it is also possible to reduce the coefficient of linear expansion (CTE) of a cured product of the crosslinkable copolymer alone or a cured product containing the crosslinkable copolymer.

[0037] The number of aromatic vinyl groups per number average molecular weight in the crosslinkable copolymer is determined by the ratio of the number average molecular weight (Mn) calculated in terms of standard polystyrene obtained by a GPC (gel permeation chromatography) method known to those skilled in the art to the number average molecular weight (Mn) of the crosslinkable copolymer. 1 H-NMR measurement and / or quantitative mode measurement 13 The number average molecular weight (Mn) can be determined by comparing the composition determined by C-NMR measurement with the vinyl group content derived from aromatic polyene units. Such methods for measuring the number average molecular weight (Mn) and methods for quantifying the content of functional groups contained in the copolymer are obvious and well known to those skilled in the art. Furthermore, the number average molecular weight (Mn) can also be determined by the methods described in the patent documents in the prior art literature of this specification.

[0038] Furthermore, in the crosslinkable copolymer, the number-average molecular weight (Mn) per aromatic vinyl group is the value obtained by dividing the number-average molecular weight (Mn) of the crosslinkable copolymer by the number of aromatic vinyl groups per number-average molecular weight (Mn) (equivalent weight per aromatic vinyl group). The number-average molecular weight (Mn) of the crosslinkable copolymer per aromatic vinyl group may be 500 or less. The lower limit is not particularly limited, but is, for example, 150 or more as a guide, preferably 170 or more, and particularly preferably 200 or more. A cured product obtained using the crosslinkable copolymer satisfying this condition can have improved mechanical properties and mechanical strength at high temperatures due to an increased crosslink density. For example, in a cured product of the crosslinkable copolymer alone or a cured product of a composition containing the crosslinkable copolymer, it is easy to achieve a storage modulus at 280°C of 40 MPa or more, preferably 50 MPa or more, and more preferably 55 MPa or more. In particular, the composition can exhibit a higher storage modulus (particularly the storage modulus at 280°C) compared to when an olefin-aromatic vinyl compound-aromatic polyene copolymer having an equivalent weight per aromatic vinyl group of more than 500 is blended in the same ratio. Furthermore, the coefficient of linear expansion (CTE) of a cured product of the crosslinkable copolymer alone or a cured product containing the crosslinkable copolymer can be reduced compared to when an olefin-aromatic vinyl compound-aromatic polyene copolymer having an equivalent weight per aromatic vinyl group of more than 500 is blended in the same ratio.

[0039] In the olefin-aromatic vinyl compound-aromatic polyene copolymer of this embodiment, the respective contents of the olefin monomer units, aromatic vinyl compound monomer units, and aromatic polyene monomer units (hereinafter sometimes referred to as the "contents of copolymerization components") can be set within any range and are not particularly limited. For example, the total content of the aromatic vinyl compound monomer units and aromatic polyene monomer units is not particularly limited, but may be 20% by mass or more and 99% by mass or less, preferably 30% by mass or more and less than 99% by mass, and more preferably 35% by mass or more and less than 85% by mass, in the crosslinkable copolymer. When the total content of the aromatic vinyl compound monomer units and aromatic polyene monomer units is 20% by mass or more, the crosslinkable copolymer is favorably compatible with other materials, such as hard crosslinking materials and flame retardants, and a highly homogeneous composition tends to be obtained, which is preferable. The content of the aromatic vinyl compound monomer unit in the crosslinkable copolymer is not particularly limited, but may be 30% by mass or less, preferably 20% by mass or less. The lower limit is not particularly limited, but may be, for example, 1% by mass or more, preferably 3% by mass or more, and more preferably 5% by mass or more.

[0040] Meanwhile, in the olefin-aromatic vinyl compound-aromatic polyene copolymer of this embodiment, the content of the olefin monomer unit is not particularly limited, but may be 1% by mass or more and 80% by mass or less, preferably 1% by mass or more and 70% by mass or less, and more preferably 15% by mass or more and 65% by mass or less, in the crosslinkable copolymer. By setting the content of the olefin monomer unit to 80% by mass or less, it is easy to satisfy the condition that the equivalent weight per aromatic vinyl group in the crosslinkable copolymer is 500 or less. An olefin monomer unit content of 1% by mass or more, particularly 10% by mass or more, is preferable because it improves the flexibility and toughness of the crosslinkable copolymer and tends to make it easier to avoid problems such as cracking when producing a cured product of the composition. In this specification, a crosslinkable copolymer with an olefin content of 0% by mass is referred to as an aromatic vinyl-aromatic polyene copolymer.

[0041] Furthermore, when the olefin monomer contains at least an α-olefin having 3 to 20 carbon atoms, the content of the α-olefin having 3 to 20 carbon atoms may be 30% by mass or more, more preferably 35% by mass or more, even more preferably 40% by mass or more, and particularly preferably 45% by mass or more, based on the total amount of the olefin monomer. The upper limit is not particularly limited, but may be 100% by mass or less, more preferably 80% by mass or less, and even more preferably 60% by mass or less. By using an α-olefin having 3 to 20 carbon atoms in such a content, the number average molecular weight of the resulting crosslinkable copolymer tends to be more easily controlled to a more preferable value of less than 8,000. This indicates that the α-olefin having 3 to 20 carbon atoms in the crosslinkable copolymer also functions as a chain transfer agent for polymerization. By increasing the amount of the α-olefin having 3 to 20 carbon atoms and adjusting it to achieve the above composition, the resulting crosslinkable copolymer tends to be more easily controlled to a desired low molecular weight.

[0042] Furthermore, when the olefin monomer is a combination of ethylene and an α-olefin having 3 to 20 carbon atoms, the content of the α-olefin having 3 to 20 carbon atoms may be 20% by mass or more, more preferably 30% by mass or more, and even more preferably 40% by mass or more, based on the total amount of the olefin monomers. The upper limit is not particularly limited, but may be 80% by mass or less, more preferably 70% by mass or less, and even more preferably 60% by mass or less. On the other hand, the content of ethylene may be 20% by mass or more, more preferably 30% by mass or more, and even more preferably 40% by mass or more, based on the total amount of the olefin monomers. The upper limit is not particularly limited, but may be 80% by mass or less, more preferably 70% by mass or less, and even more preferably 60% by mass or less. The combined use of ethylene and an α-olefin having 3 to 20 carbon atoms in such a ratio tends to facilitate the number average molecular weight of the resulting crosslinkable copolymer to be less than 8,000, which is more preferred. This indicates that the α-olefin having 3 to 20 carbon atoms in the crosslinkable copolymer also plays a role as a chain transfer agent in polymerization, and by increasing the amount of the α-olefin having 3 to 20 carbon atoms charged and adjusting it so that the above composition is achieved, it tends to be easier to make the resulting crosslinkable copolymer have a desired low molecular weight.

[0043] Specific examples of the olefin-aromatic vinyl compound-aromatic polyene copolymer of this embodiment include ethylene-styrene-divinylbenzene copolymer, ethylene-ethylvinylbenzene-divinylbenzene copolymer, ethylene-1-hexene-styrene-divinylbenzene copolymer, ethylene-1-octene-styrene-divinylbenzene copolymer, ethylene-1-octene-ethylvinylbenzene-divinylbenzene, 1-octene-styrene-divinylbenzene copolymer, 1-octene-ethylvinylbenzene-divinylbenzene copolymer, ethylene-norbornene-ethylvinylbenzene-divinylbenzene copolymer, norbornene-ethylvinylbenzene-divinylbenzene copolymer, etc. Furthermore, examples of the olefin-aromatic polyene copolymer include ethylene-divinylbenzene copolymer, ethylene-octene-divinylbenzene copolymer, ethylene-norbornene-divinylbenzene copolymer, norbornene-divinylbenzene copolymer, 1-octene-divinylbenzene copolymer, etc.

[0044] The olefin-aromatic vinyl compound-aromatic polyene copolymer of this embodiment may contain trace amounts of metals, for example, derived from the catalyst or co-catalyst used during synthesis. In some embodiments, an olefin-aromatic vinyl compound-aromatic polyene copolymer can be provided, preferably having a total metal content of 1,500 ppm or less. The metals referred to herein are metals or light metals derived from the catalyst or co-catalyst, specifically zirconium, hafnium, titanium, iron, nickel, palladium, cobalt, and aluminum. That is, the metal content derived from the catalyst or co-catalyst is defined as the sum of the respective contents of these metal elements and aluminum, and can be defined as the sum of the respective element contents. Crosslinkable copolymers having a total metal content of 1,500 ppm or less, preferably 1,200 ppm or less, more preferably less than 1,000 ppm, and particularly preferably 500 ppm or less, tend to have excellent low dielectric properties. For example, when the crosslinkable copolymer is cured alone, the resulting cured product can exhibit a dielectric constant of less than 2.4 at a measurement frequency of 40 GHz and a dielectric loss tangent of less than 0.0005 at a measurement frequency of 40 GHz. Particularly preferably, the metal derived from the catalyst or co-catalyst may be zirconium and aluminum contained in the transition metal compound and co-catalyst of the coordination polymerization catalyst described below, and the metal content derived from the catalyst or co-catalyst may be the sum of the respective contents of zirconium and aluminum.

[0045] The olefin-aromatic vinyl compound-aromatic polyene copolymer of this embodiment may contain a trace amount of boron, for example, derived from the catalyst or co-catalyst used during synthesis. In certain embodiments, an olefin-aromatic vinyl compound-aromatic polyene copolymer having a boron content of preferably 50 ppm or less can be provided. The boron referred to herein is boron derived from the catalyst or co-catalyst. Crosslinkable copolymers having a boron content of 50 ppm or less, preferably 30 ppm or less, and particularly preferably less than 10 ppm, tend to exhibit excellent low dielectric performance. For example, when the crosslinkable copolymer is cured alone, the resulting cured product can exhibit a dielectric constant of less than 2.4 at a measurement frequency of 40 GHz and a dielectric dissipation factor of less than 0.0005 at a measurement frequency of 40 GHz. Particularly preferably, the boron derived from the catalyst or co-catalyst may be boron contained in a boron compound or aluminum compound that can be used as the catalyst or co-catalyst. The boron content derived from the catalyst or co-catalyst may be the sum of the respective contents of the boron compound and aluminum compound.

[0046] <Composition> The composition of the present embodiment contains the above-mentioned olefin-aromatic vinyl compound-aromatic polyene copolymer. The composition of the present embodiment may contain the crosslinkable copolymer alone, or may further contain a solvent as an additional component other than the crosslinkable copolymer alone.

[0047] The composition of this embodiment may contain a solvent (solvent) as needed. The amount of solvent used may be appropriately determined as needed and is not particularly limited. The solvent can be used, for example, to adjust the viscosity and fluidity of the composition. In particular, when the composition of this embodiment is in the form of a varnish, a solvent is preferably used. A solvent with a high boiling point at atmospheric pressure, i.e., low volatility, results in a uniform thickness of the applied film; therefore, a solvent with a boiling point above a certain level is preferred. A preferred boiling point at atmospheric pressure is approximately 75°C or higher, more preferably 130°C or higher and 300°C or lower. Examples of solvents that can be used include cyclohexane, cyclohexanone, methyl ethyl ketone (MEK), toluene, ethylbenzene, xylene, mesitylene, tetralin, acetone, limonene, anethole, mixed alkanes, and mixed aromatic solvents. The amount of solvent used in the composition of this embodiment is arbitrary; however, for example, it is preferably 5 to 500 parts by mass, more preferably 10 to 300 parts by mass, and most preferably 50 to 150 parts by mass per 100 parts by mass of the crosslinkable copolymer.

[0048] The composition of the present embodiment may contain, as necessary, for example, (a) a curing agent, (b) a radically crosslinkable resin component, (c) a radically crosslinkable monomer, etc. These may be used alone or in any combination of two or more.

[0049] (a) Hardener The composition of this embodiment may contain a curing agent. The inclusion of a curing agent allows for efficient polymerization, crosslinking, or curing. Conventional curing agents can be used, and the type is not particularly limited. For example, conventional curing agents that can be used for the polymerization, crosslinking, or curing of aromatic polyenes or aromatic vinyls can be used. Examples of such curing agents include, but are not limited to, radical curing agents (radical generators), cationic curing agents (cation generators), and anionic curing agents (anion generators). These can be used alone or in any combination of two or more. Radical curing agents are preferred. Organic peroxides and azo-based curing agents are more preferred, and can be freely selected depending on the application and conditions. A catalog listing organic peroxides can be downloaded from the NOF Corporation website, for example, https: / / www.nof.co.jp / product-search / family / 1020001. Organic peroxides are also listed in catalogs from Fujifilm Wako Pure Chemical Industries, Ltd. and Tokyo Chemical Industry Co., Ltd., and commercially available products are available from these companies. Furthermore, hydrocarbon-based radical curing agents, i.e., radical curing agents composed only of carbon and hydrogen atoms and not containing oxygen or nitrogen atoms in their structure, such as 2,3-dimethyl-2,3-diphenylbutane, can also be used. When such hydrocarbon-based radical curing agents are used to produce cured products, the absence of oxygen or nitrogen atoms tends to result in cured products with lower dielectric constants and dielectric dissipation factors, further improving the low dielectric properties of the cured products. Known photocuring agents that utilize light, ultraviolet light, or radiation can also be used as curing agents. Examples of photocuring agents include photoradical curing agents, photocationic curing agents, and photoanionic curing agents. These can be used alone or in any combination of two or more. Such photocuring agents are available, for example, from Tokyo Chemical Industry Co., Ltd. Furthermore, polymerization, crosslinking, and curing can also be achieved using radiation or electron beams themselves. Polymerization, crosslinking, and curing can also be achieved by thermal polymerization of the raw materials contained therein without the use of a curing agent.

[0050] There are no particular restrictions on the amount of curing agent used, but generally, 0.01 to 10 parts by mass per 100 parts by mass of the composition of this embodiment is preferred. In this case, the composition of this embodiment preferably excludes the curing agent and solvent. When using a curing agent such as a peroxide or azo-based curing agent, the curing treatment should be carried out at an appropriate temperature and time, taking into account its half-life. The conditions for this are optional depending on the curing agent, but a temperature range of approximately 50°C to 200°C is generally appropriate.

[0051] The composition of this embodiment may also contain one or more (b1) radical-crosslinkable soft resins or (b2) radical-crosslinkable hard resins as the (b) radical-crosslinkable resin component. The addition of these components allows the mechanical properties of the uncured sheet and the resulting cured product to be adapted to the mechanical properties required for various uses. Note that the distinction between soft and hard is based on the state provided by the manufacturer (at room temperature and atmospheric pressure). These may be used alone or in any combination of two or more.

[0052] (b1) Radical crosslinkable soft resin Examples of radical-crosslinkable soft resins include, but are not limited to, single or multiple elastomers selected from ethylene- or propylene-based elastomers having radical-crosslinkable functional groups, conjugated diene polymers, aromatic vinyl-conjugated diene block or random copolymers, and hydrogenated products thereof. These may be used singly or in any combination of two or more. The amount of radical-crosslinkable soft resin used may be appropriately determined as needed and is not particularly limited. From the viewpoints of the handleability and moldability (handleability as a thermoplastic resin) of the composition in an uncured state, as well as reduced tackiness, the amount of radical-crosslinkable soft resin used may be, for example, preferably 100 parts by mass or less, more preferably 1 to 50 parts by mass, and even more preferably 1 to 30 parts by mass, per 100 parts by mass of the crosslinkable copolymer. Radical-crosslinkable soft resins suitable for use in the composition of the present embodiment preferably have a number-average molecular weight of 500 to 100,000, and more preferably 1,000 to 4,500.

[0053] (ethylene or propylene elastomers with radical crosslinkable functional groups) Examples of ethylene-based elastomers include, but are not limited to, ethylene-α-olefin copolymers such as ethylene-octene copolymer and ethylene-1-hexene copolymer, EPR, and EPDM. Examples of propylene-based elastomers include, but are not limited to, atactic polypropylene, low stereoregular polypropylene, and propylene-α-olefin copolymers such as propylene-1-butene copolymer. These elastomers can be used alone or in any combination of two or more. Examples of radically crosslinkable functional groups include, but are not limited to, functional groups typically found in rubber raw materials such as EPDM, such as vinyl groups, allyl groups, and ethylidene norbornene groups (units). These radically crosslinkable soft resins may be modified, for example, by introducing functional groups using maleic anhydride or other compounds.

[0054] (Conjugated diene polymers, aromatic vinyl-conjugated diene block or random copolymers, and hydrogenated products thereof) Examples of conjugated diene polymers include, but are not limited to, polybutadiene and 1,2-polybutadiene. Examples of aromatic vinyl-conjugated diene block or random copolymers and their hydrogenated products (hydrogenated products) include, but are not limited to, SBS, SIS, SEBS, SEPS, SEEPS, and SEEBS. Suitable 1,2-polybutadiene is available, for example, from Nippon Soda Co., Ltd. under the product names B-1000, 2000, and 3000 of liquid polybutadiene. Suitable copolymers containing a 1,2-polybutadiene structure include "Ricon 100" from TOTAL CRAY VALLEY. These may be used alone or in any combination of two or more. These conjugated diene polymers and their hydrogenated products may be modified, for example, by introducing functional groups using maleic anhydride or other compounds. Among conjugated diene polymers, polymers containing no or fewer vinylene groups in the main chain are preferred. Vinylene groups in the main chain tend to remain in the cured product even after curing, and these vinylene groups are likely to react with oxygen in the air to generate oxygen-containing polar groups. This means that the cured product tends to have high dielectric constants and dielectric dissipation factors after high-temperature durability tests (e.g., in air at 125°C). From this perspective, 1,4-polybutadiene copolymers are not suitable as conjugated diene polymers, and 1,2-polybutadiene polymers or copolymers containing a 1,2-polybutadiene structure are preferred. Furthermore, from this perspective, various hydrogenated polymers in which the vinylene group content has been significantly reduced by hydrogenation are preferred. Examples of hydrogenated polymers of conjugated diene polymers include hydrogenated SBR, SEBS, SEPS, SEEPS, and SEEBS, with hydrogenated polymers of conjugated diene polymers containing methyl-substituted styrene being preferred.

[0055] As the radical crosslinkable soft resin that can be suitably used in the composition of this embodiment, other olefin-aromatic vinyl-aromatic polyene copolymers shown below can also be used.

[0056] (Another olefin-vinyl aromatic-aromatic polyene copolymer) Another olefin-aromatic vinyl-aromatic polyene copolymer is an olefin-aromatic vinyl-aromatic polyene copolymer different from the above-mentioned olefin-aromatic vinyl-aromatic polyene copolymer (the crosslinkable copolymer). That is, it is an olefin-aromatic vinyl-aromatic polyene copolymer other than an olefin-aromatic vinyl-aromatic polyene copolymer having a number average molecular weight (Mn) of 500 or more and less than 12,000, having two or more aromatic vinyl groups per number average molecular weight (Mn), and having a number average molecular weight (Mn) per aromatic vinyl group of 500 or less. Such olefin-aromatic vinyl-aromatic polyene copolymers that satisfy all of the other specific conditions are described, for example, in WO 2021 / 112087, WO 2021 / 112088, and WO 2022 / 014599. An olefin-aromatic vinyl-aromatic polyene copolymer that satisfies all of these other specific conditions is flexible and exhibits a low dielectric constant and a low dielectric dissipation factor, and therefore is suitable for preparing a composition in combination with the above-mentioned olefin-aromatic vinyl-aromatic polyene copolymer (the crosslinkable copolymer) to give a cured product with a higher crosslink density, a lower dielectric constant, and a lower dielectric dissipation factor. Specifically, a composition containing preferably 1 to 50 parts by mass, more preferably 1 to 30 parts by mass, of the other olefin-aromatic vinyl-aromatic polyene copolymer per 100 parts by mass of the above-mentioned olefin-aromatic vinyl-aromatic polyene copolymer (the crosslinkable copolymer) can exhibit the characteristic of low tackiness (self-adhesiveness) in an uncured state.

[0057] (b2) Radical crosslinkable hard resin Examples of radical-crosslinkable hard resins include, but are not limited to, polyether resins, polyether ketone resins, and aromatic polyene resins having radical-crosslinkable functional groups. For example, to avoid impairing the flexibility of the resulting uncured sheet, the amount of radical-crosslinkable hard resin used may be preferably 1 to 70 parts by mass, more preferably 1 to 50 parts by mass, and even more preferably 1 to 30 parts by mass per 100 parts by mass of the crosslinkable copolymer. Using these radical-crosslinkable hard resins in amounts within the above ranges is preferable from the viewpoints of adjusting the tackiness in the uncured state, adjusting the adhesiveness of the cured product to other components, maintaining strength, and maintaining a high elastic modulus. Radical-crosslinkable hard resins suitable for use in the composition of this embodiment preferably have a number-average molecular weight of 500 to 100,000, more preferably 1,000 to 4,500.

[0058] (Polyether resin with functional groups) Examples of polyether-based resins include, but are not limited to, polyphenylene ether and polyether. Polyphenylene ether having a functional group preferably has its molecular terminals modified with the functional group. Furthermore, when added for the purpose of curing the composition of this embodiment, it is preferable that the polyphenylene ether has multiple functional groups in one molecule. For example, modified polyphenylene ether is preferable. Examples of functional groups include radically polymerizable functional groups and epoxy groups, and preferably radically polymerizable functional groups. A preferred radically polymerizable functional group is a vinyl group. Examples of vinyl groups include one or more of the group consisting of an allyl group, a (meth)acryloyl group, and an aromatic vinyl group. One or more of the group consisting of a (meth)acryloyl group and an aromatic vinyl group are more preferred, and an aromatic vinyl group is most preferred. In other words, in the composition of this embodiment, a bifunctional polyphenylene ether in which both molecular chain terminals are modified with radically polymerizable functional groups is particularly preferred. Examples of such polyphenylene ethers include, but are not limited to, Noryl (trademark) SA9000 manufactured by SABIC (modified polyphenylene ether having methacryloyl groups at both ends, number-average molecular weight 2200) and bifunctional polyphenylene ether oligomer manufactured by Mitsubishi Gas Chemical Company, Inc. (OPE-2St, modified polyphenylene ether having vinylbenzyl groups at both ends, number-average molecular weight 1200). Also usable are allylated PPE manufactured by Asahi Kasei Corporation and aromatic polyethers (ELPAC HC-F series) manufactured by JSR Corporation. Among these, preferred are bifunctional polyphenylene ether oligomers (OPE-2St) manufactured by Mitsubishi Gas Chemical Company, Inc. and aromatic polyethers (ELPAC HC-F series) manufactured by JSR Corporation. These may be used alone or in any combination of two or more.

[0059] (aromatic polyene resin) The aromatic polyene resin includes divinylbenzene-based reactive hyperbranched copolymers (PDV or ODV) manufactured by Nippon Steel Chemical & Material Co., Ltd. Such PDVs are described, for example, in the literature "Synthesis of Polyfunctional Aromatic Vinyl Copolymers and Development of New IPN-Type Low Dielectric Loss Materials Using Them" (Kawabe Masanao, Journal of the Japan Institute of Electronics Packaging, p. 125, Vol. 12 No. 2 (2009)). The aromatic polyene resin is preferably a resin (copolymer) substantially composed of aromatic polyene monomer units and aromatic monovinyl compound monomer units, and more preferably, the aromatic polyene resin does not contain olefin monomer units. The aromatic polyene resin is preferably a resin obtained by cationic polymerization or anionic polymerization. These can be used alone or in any combination of two or more.

[0060] (c) Radical crosslinkable monomer The radical crosslinkable monomer is a monomer that can be polymerized with a radical curing agent. The amount of the radical crosslinkable monomer used may be appropriately determined as needed and is not particularly limited, but may preferably be 10 parts by mass or less per 100 parts by mass of the crosslinkable copolymer. The composition of this embodiment may be substantially free of a radical crosslinkable monomer. When the content of the radical crosslinkable monomer is 10 parts by mass or less, the uncured composition does not become viscous and tends to be easily molded into a thermoplastic resin. Furthermore, when the uncured sheet obtained using this composition contains the radical crosslinkable monomer within the above range, the content of the radical crosslinkable monomer tends to be less likely to change during storage. The radical crosslinkable monomer that can be suitably used in the composition of this embodiment preferably has a molecular weight of less than 1,000, more preferably less than 500. Preferred examples of the radical crosslinkable monomer include aromatic vinyl compound monomers, aromatic polyene monomers, and / or polar monomers. As the radical crosslinkable monomer, aromatic vinyl compounds and aromatic polyenes are more preferred. Also suitable for use are BVPE (1,2-bis(vinylphenyl)ethane) as described in JP-A-2003-212941. These may be used singly or in any combination of two or more. From the viewpoint of enhancing the mechanical strength (elastic modulus) of the cured product at high temperatures, the amount of aromatic polyene is preferably 1 to 30 parts by mass per 100 parts by mass of the crosslinkable copolymer.

[0061] Furthermore, a relatively small amount of polar monomer can be used to impart adhesion to other materials, which is necessary when using the composition as an insulating material, or to improve crosslink density. Examples of the polar monomer include, but are not limited to, various maleimides, bismaleimides, maleic anhydride, glycidyl (meth)acrylate, triallyl isocyanurate, tri(meth)acrylic isocyanurate, and trimethylolpropane tri(meth)acrylate. Maleimides and bismaleimides that can be used in the composition of this embodiment are described, for example, in International Publication No. 2016 / 114287 and Japanese Patent Application Laid-Open No. 2008-291227. Commercially available products are also available from Nippon Kayaku Co., Ltd., Daiwa Kasei Kogyo Co., Ltd., Designer Molecules Inc., and other companies. These compounds can be used alone or in any combination of two or more. Among these maleimide group-containing compounds, bismaleimides are preferred from the viewpoints of solubility in organic solvents, high-frequency characteristics, high adhesion to conductors, and moldability of prepregs.

[0062] Bismaleimides may be used as polyaminobismaleimide compounds. Polyaminobismaleimide compounds can be obtained, for example, by subjecting a compound having two maleimide groups at its terminals to a Michael addition reaction with an aromatic diamine compound having two primary amino groups in the molecule. To achieve high crosslinking efficiency with a small amount of addition, it is preferable to use a polar monomer having a bifunctional or higher polyfunctional group. Examples of such polar monomers include bismaleimides, triallyl isocyanurate (TAIC), and trimethylolpropane tri(meth)acrylate. These may be used alone or in any combination of two or more. The amount of polar monomer suitable for use in the composition of this embodiment is, for example, preferably 0.1 to 10 parts by mass, more preferably 0.1 to 5 parts by mass, per 100 parts by mass of the crosslinkable copolymer. Using 10 parts by mass or less of the polar monomer tends to result in a low dielectric constant and dielectric loss tangent of the resulting cured product. In this case, the dielectric constant of the resulting cured body can be, for example, lower than 3.0, and the dielectric loss tangent can be lower than 0.005.

[0063] Furthermore, the composition of this embodiment may contain, as necessary, for example, (d) a filler, (e) a flame retardant, (f) a surface modifier, etc., as long as the low tackiness of the uncured sheet obtained using the composition and the dielectric properties of the cured product are not impaired. These may be used alone or in any combination of two or more. In a preferred embodiment, from the viewpoint of achieving both low tackiness and low dielectric properties, it is desirable to add these additives in small amounts (e.g., 100 parts by mass or less of each based on 100 parts by mass of the crosslinkable copolymer) or to essentially eliminate them. These may be used alone or in any combination of two or more.

[0064] (d) Filler The composition of the present embodiment may contain a conventionally known filler, if necessary. Either inorganic or organic fillers can be used as the filler, and the type is not particularly limited. These fillers can be added for purposes such as controlling the coefficient of thermal expansion, controlling thermal conductivity, and reducing cost. The amount used can be appropriately determined as needed and is not particularly limited. When adding an inorganic filler, it is preferable to use a known surface modifier, such as a silane coupling agent. In particular, when the objective is to produce a cured product with excellent low dielectric constant and low dielectric loss, the inorganic filler is preferably one or more of boron nitride (BN) or silica, with silica being more preferred. Fused silica is preferred as the silica. From the perspective of low dielectric properties, the filler may be used in an amount of preferably 400 parts by mass or less, more preferably 100 parts by mass or less, per 100 parts by mass of the crosslinkable copolymer. Furthermore, hollow fillers or fillers with many voids may be added to improve and enhance low dielectric properties (low dielectric constant, low dielectric loss tangent). These may be used alone or in any combination of two or more.

[0065] Furthermore, instead of inorganic fillers, organic fillers such as high molecular weight polyethylene, ultra-high molecular weight polyethylene, polystyrene, styrene-divinylbenzene copolymer, or fluorine-based resins can be used. Examples of fluorine-based resins include PTFE (polytetrafluoroethylene) and PFA (perfluoroalkoxyalkane), but the type is not particularly limited as long as it is a known resin containing fluorine. Examples of such fluorine-based resins include Fluon+ from AGC. TM EA-2000 is an example. These can be used alone or in any combination of two or more. When used in applications where the melting point or glass transition temperature is lower than the solder reflow temperature of 290°C, it is preferable from the viewpoint of heat resistance that the organic filler is crosslinked itself. Furthermore, it is preferable that the organic filler is blended in the form of fine particles or powder. These organic fillers can also suppress increases in the dielectric constant and dielectric loss tangent.

[0066] On the other hand, by mixing and dispersing a high-dielectric-constant insulating filler having a dielectric constant of preferably 4 to 10,000, more preferably 5 to 10,000 at 1 GHz, into the composition of this embodiment, it is possible to produce a cured insulating product having a high-dielectric-constant insulating layer with a dielectric constant of preferably 4 to 20 while suppressing an increase in dielectric loss tangent (dielectric loss). Increasing the dielectric constant of a film made from the cured insulating product enables the miniaturization of circuits and the increase in capacitance of capacitors, contributing to the miniaturization of high-frequency electrical components. High-dielectric-constant, low-dielectric-loss-tangent insulating layers are suitable for applications such as capacitors, inductors for resonant circuits, filters, and antennas. Suitable high-dielectric-constant insulating fillers for use in the composition of this embodiment include inorganic fillers or metal particles that have been subjected to an insulating treatment. Specific examples include known high-dielectric-constant inorganic fillers such as barium titanate and strontium titanate, as specifically described in, for example, JP 2004-087639 A.

[0067] (e) Flame retardants The composition of the present embodiment may contain a flame retardant, if necessary. From the viewpoint of maintaining a low dielectric constant and a low dielectric dissipation factor, preferred flame retardants include, but are not limited to, known organic phosphorus-based flame retardants such as phosphate esters or condensates thereof, known bromine-based flame retardants, and red phosphorus. Among phosphate esters, compounds having multiple xylenyl groups in the molecule are preferred from the viewpoint of flame retardancy and a low dielectric dissipation factor. These compounds may be used alone or in any combination of two or more. Furthermore, the composition of the present embodiment may contain, if necessary, a flame retardant aid in addition to the flame retardants described above. Examples of the flame retardant aid include, but are not limited to, antimony-based compounds such as antimony trioxide, antimony tetroxide, antimony pentoxide, and sodium antimonate, and nitrogen-containing compounds such as melamine, triallyl-1,3,5-triazine-2,3,4-(1H,3H,5H)-trione, and 2,4,6-trialyloxy-1,3,5-triazine. The amounts of these flame retardants and flame retardant auxiliaries used may be appropriately set as needed and are not particularly limited, but are usually preferably 1 to 100 parts by mass in total per 100 parts by mass of the crosslinkable copolymer. Also, 30 to 100 parts by mass of a polyphenylene ether (PPE) resin with low dielectric constant and excellent flame retardancy may be used per 100 parts by mass of the flame retardant.

[0068] (f) Surface modifier The composition of this embodiment may optionally contain a surface modifier, for example, to improve adhesion to copper foil for wiring. The use of a surface modifier is expected to increase the adhesive strength (peel strength), particularly to the smooth surface of copper foil. The amount of surface modifier used may be appropriately determined as needed and is not particularly limited. However, it is preferably 0.001 to 10 parts by mass, more preferably 0.01 to 5 parts by mass, and even more preferably 0.01 to 1 part by mass, per 100 parts by mass of the crosslinkable copolymer. When the amount of surface modifier used is within the above range, the dielectric constant and dielectric loss tangent of the cured product obtained from the composition of this embodiment tend to be low. Conventionally known surface modifiers can be used, and the type is not particularly limited. Examples of such surface modifiers include silane-based surface modifiers (also known as silane coupling agents), titanate-based surface modifiers, and isocyanate-based surface modifiers. Silane-based surface modifiers are preferred. These can be used alone or in any combination of two or more. Such silane-based surface modifiers are commercially available from, for example, Shin-Etsu Chemical Co., Ltd., Dow Corning, Evonik, and the like.

[0069] The composition and varnish of this embodiment may contain various additives commonly used in the art, such as antioxidants, weathering agents, light stabilizers, lubricants, compatibilizers, antistatic agents, etc., to the extent that the effects and objects of the present invention are not impaired. The composition and varnish of this embodiment can be obtained by mixing, dissolving, or melting the various additives described above, and any known method can be used for mixing, dissolving, or melting.

[0070] The composition of the present embodiment can be mixed by a known kneading method, for example, a twin-screw kneader, various rolls, various kneaders, etc. When the composition of the present embodiment is a varnish, each component can be mixed by adding it to the varnish and stirring.

[0071] <Varnish> The varnish of this embodiment can exhibit a viscous liquid state at room temperature or at an elevated temperature of 100°C or less by adjusting the composition or molecular weight of the crosslinkable copolymer, adding a solvent, or adding a liquid flame retardant. The varnish of this embodiment can have a viscosity of, for example, several hundred thousand mPa·s or less at room temperature, preferably 5,000 mPa·s or less, more preferably 2,000 mPa·s or less, and particularly preferably 500 mPa·s or less. The varnish of this embodiment can be applied, impregnated, filled, or dripped onto other materials using an appropriate method, and then the solvent removed to form a molded product. The desired cured product can then be obtained by curing with heat or light. Taking advantage of these properties, insulating coatings or layers can be formed by various transfer molding (pressure molding), applying the varnish onto or between substrates or semiconductor device materials, or forming sheets or films by extrusion lamination or spin coating, followed by curing. Furthermore, the polymerization liquid obtained when copolymerizing the olefin-aromatic vinyl compound-aromatic polyene copolymer of this embodiment (which generally contains, in addition to the crosslinkable copolymer, solvents used during polymerization such as toluene, ethylbenzene, cyclohexane, and methylcyclohexane, residual monomers such as styrene and divinylbenzene, residual monomers such as olefin monomers, catalysts, and co-catalyst components) can also be used as a varnish as is. Alternatively, a varnish can also be obtained by distilling off some or all of the solvent and residual monomers from this polymerization liquid under reduced pressure, and diluting the resulting solution with the solvent as needed. In other words, the varnish of this embodiment may contain residual monomers from the copolymerization, the solvent used during the copolymerization, and the like.

[0072] <Molded body> The shape of a molded article obtained from the composition of this embodiment is arbitrary. The composition of this embodiment can exhibit the properties of a thermoplastic resin. Therefore, under conditions that do not cause crosslinking, the composition can be molded into shapes such as sheets, tubes, strips, pellets, etc. in a substantially uncured state using known molding methods for thermoplastic resins, such as extrusion molding, injection molding, press molding, and inflation molding, and then crosslinked (cured). These known molding methods can produce uncured sheets and films. For example, when the composition of this embodiment is a varnish, it can be applied to a substrate and then the solvent is removed by heating, reducing pressure, air drying, or the like to obtain a molded article in the form of a sheet or film. Alternatively, a composite can be obtained by impregnating a porous substrate, woven fabric, or nonwoven fabric with the varnish of this embodiment and removing the solvent. In this case, the composition can be dropped onto a substrate and then removed to form a hemispherical shape, for example. In particular, the sheet may be in an uncured (semi-cured) state to the extent that it can maintain its sheet shape, or it may be fully cured after lamination with another substrate or copper foil. To achieve a semi-cured state, examples include using multiple curing agents with different half-life temperatures in combination by adjusting the amounts used, appropriately adjusting the curing time and / or curing temperature, or changing the curing mode (e.g., photocuring for semi-curing and peroxide for full curing). A conventional solvent drying process can also be used for this semi-curing process. Alternatively, when curing by heating and pressurizing using a press or the like, the heating conditions can be multi-staged to introduce a semi-cured state midway through the process, thereby suppressing varnish bleeding and thickness unevenness. The degree of curing of a molded product, particularly a sheet, can be quantitatively measured using known dynamic mechanical analysis (DMA) or gel content.

[0073] <Curing> The composition or varnish of this embodiment, and the molded articles obtained therefrom, can be cured by a known method, taking into consideration the curing conditions (temperature, time, pressure) of the raw materials and curing agent contained therein. For example, when the curing agent used is a peroxide, the curing conditions can be determined by taking into consideration the half-life temperature and the like disclosed for each peroxide.

[0074] <Cured product obtained from the composition, cured product of molded product> The cured product of the molded article obtained from the composition of this embodiment is sufficiently cured, and the gel content measured in accordance with ASTM is preferably 90% by mass or more. Furthermore, in the measurement range of 10 to 50 GHz, particularly preferably at 40 GHz, the dielectric constant of the cured product is preferably 3.0 to 2.0, more preferably 2.8 to 2.0, and most preferably 2.5 to 2.0. The dielectric loss tangent is preferably 0.003 to 0.0002, more preferably 0.002 to 0.0002. Furthermore, the volume resistivity of the obtained cured product is preferably 1×10 15 The electrical insulating material has a water absorption of 0.1 mass % or less, which are particularly preferable for use in high frequency bands of 3 GHz or more.

[0075] <Electrical insulating materials, etc.> The crosslinkable copolymer of this embodiment or a cured product obtained from the composition of this embodiment is particularly suitable as an electrical insulating material for high-frequency signals, and these cured products can be suitably used for CCL substrates, FCCL substrates, interlayer insulating materials, antennas, coverlays, etc. That is, the present invention can also provide CCL substrates, FCCL substrates, interlayer insulating materials, antennas, coverlays, etc., made from the crosslinkable copolymer or a composition containing the same. The crosslinkable copolymer of this embodiment or a cured product obtained from the composition of this embodiment has a high crosslink density and is therefore considered to be particularly useful as an insulating material for package substrates.

[0076] In another aspect, the present disclosure provides an electrical insulating material comprising an olefin-aromatic vinyl compound-aromatic polyene copolymer, which, as a cured product, has a storage modulus at 280°C of 40 MPa or more, preferably 50 MPa or more and 10 GPa or less, and a dielectric constant of 3.0 or more and 2.0 or more, and a dielectric dissipation factor of 0.003 or less and 0.0002 or more, preferably 0.002 or less and 0.0002 or more, measured at 23°C and 40 GHz.

[0077] <Method of producing an olefin-aromatic vinyl compound-aromatic polyene copolymer> The method for producing the olefin-aromatic vinyl compound-aromatic polyene copolymer of the present embodiment described above is not particularly limited, but an example of a preferred production method will be described below.

[0078] The present disclosure also provides a novel method for producing the above-described olefin-aromatic vinyl compound-aromatic polyene copolymer. Specifically, the method involves copolymerizing an olefin monomer and an aromatic polyene monomer in the presence of a coordination polymerization catalyst to obtain the above-described "crosslinkable copolymer having a number average molecular weight (Mn) of 500 or more but less than 12,000, comprising olefin monomer units and aromatic polyene monomer units, and having aromatic vinyl groups derived from the aromatic polyene monomer units, wherein the number of aromatic vinyl groups per number average molecular weight (Mn) is two or more, and the number average molecular weight (Mn) per aromatic vinyl group is 500 or less." In this case, a coordination polymerization catalyst containing a transition metal compound (transition metal compound catalyst) and a cocatalyst is preferably used. Here, coordination polymerization refers to a polymerization method using a coordination polymerization catalyst containing a transition metal compound and a cocatalyst. The transition metal compound is preferably a transition metal compound containing zirconium, hafnium, titanium, iron, nickel, cobalt, or palladium. In particular, for copolymerizing cyclic olefin monomers, transition metal compounds containing zirconium, titanium, nickel, iron, and palladium are preferred.

[0079] The transition metal compound of the coordination polymerization catalyst is preferably a transition metal compound represented by the following general formula (1). [ka] (In the formula, M is a central metal selected from the group consisting of zirconium, hafnium, and titanium. A and B each independently represent a group selected from the group consisting of a substituted or unsubstituted cyclopentaphenanthryl group, a substituted or unsubstituted benzoindenyl group, a substituted or unsubstituted cyclopentadienyl group, and a substituted or unsubstituted indenyl group. Y is a divalent group bonding to A and B, and is selected from the group consisting of a methylene group, a silylene group, an ethylene group, a germylene group, and a boron residue, which may further have a hydrogen atom or a hydrocarbon group having 1 to 15 carbon atoms (which may further contain 1 to 3 nitrogen atoms, oxygen atoms, sulfur atoms, phosphorus atoms, or silicon atoms) as a substituent, and these substituents may be different or the same. Furthermore, Y may have a cyclic structure. Each X is independently selected from the group consisting of a hydrogen atom, a halogen atom, an alkyl group having 1 to 15 carbon atoms, an aryl group having 6 to 10 carbon atoms, an alkylaryl group having 8 to 12 carbon atoms, a silyl group having a hydrocarbon substituent having 1 to 4 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, and a dialkylamide group having an alkyl substituent having 1 to 6 carbon atoms.

[0080] From the viewpoint of producing a crosslinkable copolymer having a relatively low molecular weight and a low viscosity when made into a varnish, it is preferred that A and B in the formula are each independently a substituted or unsubstituted cyclopentadienyl group, or that one of A and B is a substituted or unsubstituted cyclopentadienyl group and the other is a group selected from substituted or unsubstituted indenyl groups.

[0081] Furthermore, when the olefin monomer used for the crosslinkable copolymer is a combination of ethylene and an α-olefin having 3 or more carbon atoms, as described above, by changing the polymerization conditions such as the monomer charging ratio so that the content of the α-olefin having 3 or more carbon atoms in the crosslinkable copolymer is 30% by mass or more and 100% by mass or less relative to the total amount of the olefin monomers, it becomes easy to obtain a crosslinkable copolymer having a relatively low molecular weight. Specifically, it is possible to easily produce a crosslinkable copolymer having a number average molecular weight of less than 8,000.

[0082] Known cocatalysts can be used in coordination polymerization catalysts, and the type is not particularly limited. Examples include the cocatalysts used in combination with the transition metal compounds described above. Specific examples of such cocatalysts include, but are not limited to, alumoxanes such as methylaluminoxane (also referred to as methylalumoxane or MAO) and boron compounds. Furthermore, alkylaluminums such as triisobutylaluminum (TIBA) and triethylaluminum (TEA) may also be used. Examples of such cocatalysts include the cocatalysts and alkylaluminum compounds described in EP 0872492A2, JP 11-130808 A, JP 9-309925 A, WO 00 / 20426 A, EP 0985689A1, and JP 6-184179 A.

[0083] Examples of boron compounds (boron-containing promoters) include trispentafluorophenylborane, triphenylcarbenium tetrakis(pentafluorophenyl)borate {trityl tetrakis(pentafluorophenyl)borate}, lithium tetrakis(pentafluorophenyl)borate, trimethylammonium tetraphenylborate, triethylammonium tetraphenylborate, tripropylammonium tetraphenylborate, tri(n-butyl)ammonium tetraphenylborate, tri(n-butyl)ammonium tetra(p-tolyl)phenylborate, tri(n-butyl)ammonium tetra(p-ethylphenyl)borate, tri(n-butyl)ammonium tetra(pentafluorophenyl)borate, trimethylammonium tetra(p-tolyl)borate, trimethylammonium tetrakis-3,5-dimethylphenylborate, and triethylammonium tetrakis(pentafluorophenyl)borate. Tetrakis-3,5-dimethylphenylborate, tributylammonium tetrakis-3,5-dimethylphenylborate, tributylammonium tetrakis-2,4-dimethylphenylborate, anilinium tetrakispentafluorophenylborate, N,N'-dimethylanilinium tetraphenylborate, N,N'-dimethylanilinium tetrakis(p-tolyl)borate, N,N'-dimethylanilinium tetrakis(m-tolyl)borate, N,N'-dimethylanilinium tetrakis(2,4-dimethylphenyl)borate, N,N'-dimethylanilinium tetrakis(3,5-dimethylphenyl)borate, N,N'-dimethylanilinium tetrakis(pentafluorophenyl)borate, N,N'-diethylanilinium tetrakis(pentafluorophenyl)borate, N,N'-2,4,5-pentamethylanilinium tetraphenylborate, N,N'-2,4,Examples of suitable tetraphenylborate include 5-pentaethylanilinium tetraphenylborate, di-(isopropyl)ammonium tetrakispentafluorophenylborate, di-cyclohexylammonium tetraphenylborate, triphenylphosphonium tetraphenylborate, tri(methylphenyl)phosphonium tetraphenylborate, tri(dimethylphenyl)phosphonium tetraphenylborate, triphenylcarbenium tetrakis(p-tolyl)borate, triphenylcarbenium tetrakis(m-tolyl)borate, triphenylcarbenium tetrakis(2,4-dimethylphenyl)borate, triphenylcarbenium tetrakis(3,5-dimethylphenyl)borate, tropylium tetrakispentafluorophenylborate, tropylium tetrakis(p-tolyl)borate, tropylium tetrakis(m-tolyl)borate, tropylium tetrakis(2,4-dimethylphenyl)borate, and tropylium tetrakis(3,5-dimethylphenyl)borate, but are not particularly limited thereto. Although boron-containing cocatalysts in which the fluorine-substituted aromatic group is a phenyl group have been exemplified herein, boron-containing cocatalysts having a fused aromatic group such as a fluorine-substituted naphthyl group can also be preferably used. Among these, preferred boron-containing cocatalysts are those having boron and a fluorine-substituted aromatic group bonded thereto. Examples include, but are not limited to, trispentafluorophenylborane, triphenylcarbenium tetrakis(pentafluorophenyl)borate {trityl tetrakis(pentafluorophenyl)borate}, lithium tetrakis(pentafluorophenyl)borate, tri(n-butyl)ammonium tetra(pentafluorophenyl)borate, tropylium tetrakispentafluorophenylborate, and N,N'-dimethylanilinium tetrakis(pentafluorophenyl)borate. Particularly preferred are triphenylcarbenium tetrakis(pentafluorophenyl)borate {trityl tetrakis(pentafluorophenyl)borate} and N,N'-dimethylanilinium tetrakis(pentafluorophenyl)borate is one of the most preferred boron-containing cocatalysts. These are sometimes referred to as TRI-FABA or TRI-FAB, DAN-FABA or DAN-FAB, etc., and can be purchased from Tosoh Finechem Co., Ltd. or Kanto Chemical Co., Ltd.

[0084] The amount of co-catalyst used may be appropriately set as needed and is not particularly limited. For example, when alkylaluminum is used as the co-catalyst, the aluminum atom / transition metal atomic ratio relative to the metal in the transition metal compound is preferably 0.1 to 100,000, more preferably 10 to 10,000. An atomic ratio of 0.1 or more can effectively activate the transition metal compound, while an atomic ratio of 100,000 or less tends to be economically advantageous. The coordination polymerization catalyst of the transition metal compound and co-catalyst may be mixed and prepared outside the polymerization equipment, or may be mixed and prepared inside the equipment during polymerization.

[0085] In particular, when a promoter such as alumoxane is used, the amount of promoter used is preferably 0.1 to 100,000, more preferably 10 to 10,000, in terms of the aluminum atom / transition metal atomic ratio relative to the metal in the transition metal compound. A ratio of 0.1 or more can effectively activate the transition metal compound, while a ratio of 100,000 or less tends to be economically advantageous. Furthermore, when a boron compound is used as the promoter, the amount of promoter used is preferably 0.1 to 100, more preferably 0.1 to 10, and most preferably 0.8 to 1.2, in terms of the boron atom / transition metal atomic ratio. A ratio of 0.1 or more can effectively activate the transition metal compound, while a ratio of 100 or less tends to be economically advantageous.

[0086] In one preferred embodiment, an olefin monomer and an aromatic polyene monomer are copolymerized in the presence of a coordination polymerization catalyst using a boron compound as a cocatalyst. The use of a boron compound as a cocatalyst reduces the amount of metal components, such as aluminum, contained in the final crosslinkable copolymer. Furthermore, olefin-aromatic vinyl compound-aromatic polyene copolymers containing a total of preferably 1,500 ppm or less of metals derived from the catalyst and cocatalyst, more preferably 1,200 ppm or less, even more preferably less than 1,000 ppm, and particularly preferably 500 ppm or less tend to exhibit particularly excellent low dielectric properties. Specifically, the dielectric constant and dielectric dissipation factor of the cured product of the crosslinkable copolymer alone or the cured product of the above-mentioned composition can be reduced to particularly preferred ranges. The final cured product of the crosslinkable copolymer alone can have a dielectric constant of less than 2.4 and a dielectric dissipation factor of less than 0.0005.

[0087] Like metals, boron compounds can also be a factor in causing deterioration of dielectric properties. Therefore, from the viewpoint of excellent low dielectric properties, an olefin-aromatic vinyl compound-aromatic polyene copolymer having a boron content derived from catalysts and co-catalysts of preferably 50 ppm or less, more preferably 30 ppm or less, and particularly preferably less than 10 ppm is preferred. Specifically, the dielectric constant and dielectric loss tangent of a cured product of the crosslinkable copolymer alone or a cured product of the above-mentioned composition can be reduced to particularly preferred ranges, and the finally obtained cured product of the crosslinkable copolymer alone can have a dielectric constant of less than 2.4 and a dielectric loss tangent of less than 0.0005. [Example]

[0088] The features of the present invention will be explained in more detail below with reference to examples, but the present invention is not limited thereto. That is, the materials, amounts used, ratios, processing details, processing procedures, etc. shown in the following examples can be appropriately changed without departing from the spirit of the present invention. Furthermore, the values ​​of various production conditions and evaluation results in the following examples represent preferred upper or lower limits in the embodiments of the present invention, and preferred numerical ranges may be defined by combining the above-mentioned upper or lower limits with the values ​​of the following examples or values ​​of the examples themselves.

[0089] The crosslinkable copolymers obtained in the respective examples were analyzed by the following methods. The content of each monomer unit in the crosslinkable copolymer is determined by: 1 H-NMR measurement and quantitative mode if necessary 13 The analysis was performed by a known method using C-NMR measurement in combination with the peak area intensity assigned to each structure. The sample was dissolved in heavy 1,1,2,2-tetrachloroethane, and the measurement was performed at 80 to 130°C.

[0090] The molecular weight was determined as a number average molecular weight (Mn) converted to standard polystyrene using GPC (gel permeation chromatography) under the following conditions.

[0091] Column: Four TSK-GEL MultiporeHXL-M φ7.8×300 mm (manufactured by Tosoh Corporation) connected in series were used. Column temperature: 40℃ Solvent: THF Flow rate: 1.0 ml / min. Detector: RI detector

[0092] <Varnish viscosity> The varnish viscosity of the crosslinkable copolymer obtained in each example was determined as follows. A 25% by mass toluene solution of each crosslinkable copolymer was prepared, and the viscosity was measured at 25°C using a rotational rheometer (MCR302: manufactured by Anton Paar) at a shear rate of 1 sec. -1 The value of was used.

[0093] <Gel content> The gel content was determined as the boiling toluene insoluble matter according to ASTM D2765-84.

[0094] <Measurement of storage modulus> Using a dynamic viscoelasticity measuring device (TA Instruments, formerly Rheometrics RSA-G2), measurements were taken in a nitrogen atmosphere at a frequency of 1 Hz while the temperature was raised from room temperature (23°C), and the storage modulus at 25°C and 280°C was measured. Measurement samples (3 mm x 40 mm) were cut out from films with a uniform thickness of approximately 0.1 to 0.3 mm and measured, and the storage modulus of the cured material was measured. The main measurement parameters involved in the measurement are as follows: Measurement frequency 1Hz Heating rate: 3°C / min Sample measurement length: 10 mm Distortion 0.1%

[0095] <Dielectric constant and dielectric loss (dielectric loss tangent)> The dielectric loss tangent was measured using the cavity resonator perturbation method (Agilent Technologies 8722ES network analyzer, Keysight Technologies split cylinder resonator 40 GHz) at 23°C and 40 GHz using a 0.1 mm x 25 mm x 30 mm sample cut out from the sheet.

[0096] <Water absorption rate> The water absorption rate was measured after immersion in pure water at 23°C for 24 hours in accordance with ASTM D570-98.

[0097] <Quantitative determination of metal and boron contents in crosslinkable copolymers> The metal content (in the examples below, the transition metal element content used in the metal catalyst and the aluminum content used in the promoter) and boron content (in the example below, the boron content used in the promoter) were determined as follows: In addition, the contents of hafnium, titanium, iron, nickel, cobalt, and palladium were also quantified. Measurement was performed by ICP atomic emission spectroscopy under the following conditions in accordance with JIS K 0116:2014. 0.5 g of the composition to be measured was weighed into a platinum crucible and incinerated on a hot plate, an electric stove, and an electric furnace (gradually heated to 600°C). 0.5 ml of HCl (1+1) (i.e., a 1:1 volumetric mixture of hydrochloric acid and water) and ultrapure water were added to the residue, which was dissolved by heating and then adjusted to a constant volume of 5 ml to form a test solution. Quantitative analysis was performed by ICP atomic emission spectroscopy (using an Agilent 5110VDV).

[0098] Example 1: Preparation of crosslinkable copolymer P-1 The raw material divinylbenzene (DVB) was "Divinylbenzene 810 (divinylbenzene content 81 wt%)" manufactured by Nippon Steel Chemical & Material Co., Ltd. (liquid at room temperature, a mixture of meta and para divinylbenzenes containing 81% by mass, with the remainder being ethylvinylbenzene). A 10-L polymerization vessel equipped with a heating and cooling jacket and a stirrer was used. The vessel was thoroughly dried and purged with nitrogen. 2 kg of toluene, 1 kg of 1-octene, and 2 kg of divinylbenzene were charged, and approximately 20 L of dry nitrogen was bubbled through at an internal temperature of 50 °C. The vessel was then purged with ethylene gas, and 5 mmol of TIBA (manufactured by Kanto Chemical Co., Ltd.) was added and stirred. 50 mmol of MMAO (modified MAO) (manufactured by Tosoh Finechem Co., Ltd.) was then added and stirred. The internal temperature was stabilized at 60°C, and the internal pressure of the polymerization vessel was increased to 0.1 MPaG (gauge) by ethylene supply and stabilized. Then, 100 g of a toluene solution containing 100 μmol of dimethylmethylenebis(cyclopentadienyl)zirconium dichloride (structure: see formula (2) below) and 2 mmol of TIBA was added to the polymerization vessel from a catalyst tank installed above the polymerization vessel to initiate polymerization. Polymerization was continued by gradually replenishing the ethylene consumed during polymerization while maintaining the internal temperature at 70°C and the internal pressure at 0.1 MPaG. After approximately 4 hours of polymerization, when ethylene consumption reached 400 g, the ethylene gas in the polymerization vessel was vented and the pressure returned to normal. 50 g of isopropanol (a polymerization terminator) was added to the polymerization vessel to terminate the polymerization. The resulting polymerization solution was poured into a large amount of methanol, stirred, and allowed to stand. The methanol layer containing the monomer and solvent was removed by decantation. A large amount of methanol was then added again, stirred, and allowed to stand. The methanol layer was similarly removed by decantation. This procedure was repeated several times. The precipitate layer containing the cross-linkable copolymer was collected, spread thinly in a shallow container, and thoroughly vacuum dried at 30°C to obtain cross-linkable copolymer P-1, which is a semi-solid ethylene-1-octene-ethylvinylbenzene-divinylbenzene copolymer.

[0099] [ka]

[0100] Example 2: Preparation of crosslinkable copolymer P-2 The amount of MMAO (modified MAO) manufactured by Tosoh Finechem Co., Ltd. used was changed to 40 mmol in terms of aluminum, and the catalyst used was changed from 100 μmol of dimethylmethylenebis(cyclopentadienyl)zirconium dichloride to 50 μmol of racdiphenylmethylene(1-indenyl)(cyclopentadienyl)zirconium dichloride (structure see formula (3) below), and the polymerization temperature was changed to an internal temperature of 60°C. Except for these changes, the same procedure as in Example 1 was carried out, and the crosslinkable copolymer was recovered to obtain crosslinkable copolymer P-2, which is an ethylene-1-octene-ethylvinylbenzene-divinylbenzene copolymer.

[0101] [ka]

[0102] Example 3: Preparation of crosslinkable copolymer P-3 The same procedure as in Example 2 was carried out except that the amount of divinylbenzene used was changed to 3 kg and the polymerization temperature was changed to an internal temperature of 60°C. The crosslinkable copolymer was recovered to obtain a crosslinkable copolymer P-3, which was an ethylene-1-octene-ethylvinylbenzene-divinylbenzene copolymer.

[0103] Example 4: Preparation of crosslinkable copolymer P-4 As in Example 3, rac-diphenylmethylene(1-indenyl)(cyclopentadienyl)zirconium dichloride was used as the catalyst, except that the co-catalyst was changed to tritium tetrakis(pentafluorophenyl)borate (manufactured by Tosoh Finechem Co., Ltd.) instead of MMAO, and polymerization was carried out as follows. 2 kg of toluene, 1 kg of 1-octene, and 3 kg of divinylbenzene were charged into a polymerization vessel, and approximately 20 L of dry nitrogen was bubbled through at an internal temperature of 50°C. The atmosphere inside the polymerization vessel was then replaced with ethylene gas, and 5 mmol of TIBA (manufactured by Kanto Chemical Co., Ltd.) in terms of aluminum moles was added and stirred. The internal temperature was stabilized at 60 °C, and the internal pressure of the polymerization vessel was increased to 0.1 MPaG (gauge) by feeding ethylene and stabilizing it. Then, from a catalyst tank installed above the polymerization vessel, a catalyst solution consisting of 100 g of a toluene solution containing 50 μmol of rac-diphenylmethylene(1-indenyl)(cyclopentadienyl)zirconium dichloride and 1 mmol of triisobutylaluminum dissolved in 100 g of a toluene solution containing 50 μmol of rac-diphenylmethylene(1-indenyl)(cyclopentadienyl)zirconium dichloride, 1 mmol of triisobutylaluminum dissolved in 10 g of a toluene solution containing 55 μmol of tritium tetrakis(pentafluorophenyl)borate was added to the polymerization vessel, and the polymerization was carried out at an internal temperature of 90 °C. During the polymerization, the progress of the polymerization was monitored by the ethylene consumption rate, and 50 g of a toluene solution containing 25 μmol of rac-diphenylmethylene(1-indenyl)(cyclopentadienyl)zirconium dichloride, 25 μmol of tritium tetrakis(pentafluorophenyl)borate, and 1 mmol of triisobutylaluminum was added twice to maintain the polymerization rate. When the amount of ethylene consumed reached 300 g, the polymerization was stopped to obtain a crosslinkable copolymer P-4, which was an ethylene-1-octene-ethylvinylbenzene-divinylbenzene copolymer.

[0104] Example 5: Preparation of crosslinkable copolymer P-5 Using the same polymerization apparatus as in the previous example, the inside of a thoroughly dried polymerization vessel was first purged with nitrogen, and 2 kg of toluene, 1 kg of 1-octene, and 2 kg of divinylbenzene were charged. Approximately 20 L of dry nitrogen was bubbled through at an internal temperature of 50°C. TIBA (manufactured by Kanto Chemical Co., Inc.) (5 mmol, based on the number of moles of aluminum) was then added and stirred. The internal temperature was stabilized at 60°C, and the internal pressure of the polymerization vessel was increased to 0.1 MPaG (gauge) by adding nitrogen and stabilized. Then, 100 g of a toluene solution containing 50 μmol of dimethylmethylenebis(cyclopentadienyl)zirconium dichloride, 55 μmol of tritium tetrakis(pentafluorophenyl)borate, and 1 mmol of TIBA was added from a catalyst tank installed above the polymerization vessel to the polymerization vessel, and polymerization was initiated. 50 g of a toluene solution containing 25 μmol of dimethylmethylenebis(cyclopentadienyl)zirconium dichloride, 25 μmol of tritium tetrakis(pentafluorophenyl)borate, and 1 mmol of triisobutylaluminum was added twice every hour. Polymerization was continued while maintaining an internal temperature of 60°C and an internal nitrogen pressure of 0.1 MPaG. After 5 hours of polymerization, the pressure was released to normal pressure, and 50 g of isopropanol, a polymerization terminator, was added to the polymerization vessel to terminate the polymerization. The procedure was then repeated in the same manner as in the previous examples to obtain a crosslinked copolymer P-5, which was a 1-octene-ethylvinylbenzene-divinylbenzene copolymer.

[0105] <Comparative Example 1> O-3 (ethylene-styrene-divinylbenzene copolymer, number average molecular weight 6,400, equivalent weight per vinyl group of divinylbenzene unit 1,684) described in WO 2022-014599 was used. Perbutyl P was used as the curing agent. The storage modulus (280°C) of O-3 was 3.7 MPa.

[0106] Table 1 shows the composition, number average molecular weight (Mn), number of vinyl groups derived from divinylbenzene units per number average molecular weight, and equivalent weight per vinyl group in the divinylbenzene unit (molecular weight between crosslinking points) of P-1 to P-5 obtained in each Example. The equivalent weight per vinyl group in the divinylbenzene unit was 500 or less in all cases. Table 2 also shows the metal content and boron content contained in the crosslinkable copolymer. It was confirmed that the use of a boron compound-based cocatalyst made it possible to reduce the total metal content, such as that derived from the catalyst and cocatalyst, contained in each crosslinkable copolymer to 1,500 ppm or less, and that the boron content, such as that derived from the catalyst and cocatalyst, contained in each crosslinkable copolymer to 500 ppm or less.

[0107] [Table 1]

[0108] [Table 2]

[0109] <Examples 6 to 10, Comparative Example 2> Using a vessel equipped with a heating and cooling jacket and a stirring blade, 100 parts by mass of each of the crosslinkable copolymers P-1 to P-5 was heated to approximately 50°C in 100 parts by mass of toluene as a solvent, and stirred to prepare a 50% by mass toluene solution (varnish). All of the resulting copolymers P-1 to P-5 were soluble in the toluene solvent. The viscosity of each varnish was then measured. Subsequently, 1 part by mass of a curing agent (perbutyl P in Examples 6, 7, and 10 and Comparative Example 2, and 2,3-dimethyl-2,3-diphenylbutane in Examples 8 and 9) was added and dissolved relative to the parts by mass of each crosslinkable copolymer, followed by stirring and mixing to prepare a varnish-like composition. Each of the resulting compositions was poured into a Teflon® mold (7 cm long, 7 cm wide, and 0.2 mm, 0.5 mm, or 1.0 mm thick) on a PET sheet placed on a glass plate. The resulting composition was thoroughly air-dried at 25°C and then further dried in a vacuum dryer at 60°C for at least 3 hours to produce an uncured sheet. The Teflon sheet and Teflon mold were then placed in a press, and each resulting uncured sheet was placed inside the mold. In Examples 6, 7, and 10, the composition was then heated under a load of 5 MPa at 120°C for 30 minutes, 150°C for 30 minutes, and then 200°C for 120 minutes. The Teflon sheet and Teflon mold were removed to produce a cured sheet. In Examples 8 and 9, the cured sheets were similarly prepared, except that the heating conditions were changed to 200°C for 30 minutes and 240°C for 1 hour. The resulting cured sheets were then measured for gel content, viscoelasticity (storage modulus), dielectric constant, dielectric dissipation factor (all at 23°C and 40 GHz), and water absorption. The measurement results are shown in Table 3. The cured sheets of Examples 6 to 10 were all sufficiently crosslinked and had excellent dielectric constant, dielectric dissipation factor, and water absorption. Furthermore, the storage modulus at 280°C was significantly higher than 40 MPa for all of Examples 6 to 10.

[0110] [Table 3]

[0111] Example 11: Preparation of crosslinkable copolymer P-6 Using the same polymerization apparatus as in the previous example, first, the inside of a thoroughly dried polymerization vessel was purged with nitrogen, and then 1.0 kg of toluene (including the toluene contained in the norbornene), 1.5 kg of divinylbenzene, and 2.0 kg of acenaphthylene with a purity of 97% by mass, manufactured by Anshan Little Giant Co., Ltd., were charged and completely dissolved. After bubbling with dry nitrogen as in the previous example, the inside of the polymerization vessel was purged with ethylene gas, and 5 mmol of TIBA (manufactured by Kanto Chemical Co., Ltd.) was added and stirred, and 200 mmol of MMAO (modified MAO) (manufactured by Tosoh Finechem Co., Ltd.) was added and stirred. The internal temperature was stabilized at 60°C, and the internal pressure of the polymerization vessel was increased to 0.05 MPaG (gauge) by feeding ethylene. After stabilizing, 100 g of a toluene solution containing 200 μmol of dimethylmethylenebis(cyclopentadienyl)zirconium dichloride (see formula (2) above for structure) and 20 mmol of TIBA was added from a catalyst tank installed above the polymerization vessel to initiate polymerization. While monitoring the ethylene consumption rate, equal amounts of catalyst and MAO were added twice more to maintain the polymerization rate. After approximately 3 hours, when ethylene consumption reached 50 g, the polymerization was terminated in the same manner. After post-treatment, a crosslinked copolymer P-6, an ethylene-acenaphthylene-ethylvinylbenzene-divinylbenzene copolymer, was obtained. The glass transition temperature of this copolymer was 101°C. Due to the use of MAO as a cocatalyst, this copolymer contained a high aluminum content. Therefore, in order to remove metal components such as aluminum, metal components in the copolymer were removed by a method in accordance with Example 16 of International Publication No. 2015 / 174485. As a result, the aluminum content in each copolymer was less than 100 ppm, and the total amount including zirconium derived from the catalyst was also less than 100 ppm.

[0112] Example 12: Preparation of crosslinkable copolymer P-7 Using the same polymerization apparatus as in the previous example, 300 g of norbornene (75% norbornene concentration, toluene solution, manufactured by Maruzen Petrochemical Co., Ltd.) was charged as a pure norbornene content, 1.3 kg of toluene (this toluene includes the toluene contained in the norbornene), 1.3 kg of divinylbenzene, and 1.6 kg of acenaphthylene were charged and completely dissolved. After bubbling with dry nitrogen as in the previous example, the inside of the polymerization vessel was replaced with ethylene gas, and 5 mmol of TIBA (manufactured by Kanto Chemical Co., Ltd.) was added and stirred, and 200 mmol of MMAO (modified MAO) (manufactured by Tosoh Finechem Co., Ltd.) was added and stirred. The internal temperature was stabilized at 60°C, and the internal pressure of the polymerization vessel was increased to 0.05 MPaG (gauge) by supplying ethylene and stabilizing it. Then, 100 g of a toluene solution containing 200 μmol of dimethylmethylenebis(cyclopentadienyl)zirconium dichloride (see formula (2) above for its structure) and 20 mmol of TIBA was added to the polymerization vessel from a catalyst tank installed above the polymerization vessel to initiate polymerization. While monitoring the ethylene consumption rate, the same amounts of catalyst and MAO were added twice more to maintain the polymerization rate. After approximately 3 hours, when the ethylene consumption reached 50 g, the polymerization was terminated in the same manner. After post-treatment, a crosslinked copolymer P-7, an ethylene-norbornene-acenaphthylene-ethylvinylbenzene-divinylbenzene copolymer, was obtained. The glass transition temperature of this copolymer was 110°C. Because this copolymer used MAO as a cocatalyst, it contained a high aluminum content. Therefore, metal components were removed as in Example 11. As a result, the aluminum content in each copolymer was less than 100 ppm, and the total amount including the zirconium derived from the catalyst was also less than 100 ppm. The copolymer P-7 was soluble in toluene, a solvent.

[0113] [Table 4]

[0114] <Examples 13 and 14> Cured sheets were prepared using the formulations shown in Table 5, in the same manner as in Examples 6 to 10 and Comparative Example 2, except that the amount of curing agent Perbutyl P used was changed. Table 5 shows the evaluation results.

[0115] [Table 5] [Industrial Applicability]

[0116] The olefin-aromatic vinyl compound-aromatic polyene copolymer, etc. of the present invention is nonvolatile, has a low molecular weight, and can achieve a high crosslink density. By using this, it is possible to realize a cured product, etc. that has excellent dielectric properties and a high storage modulus, and it is also possible to improve the mechanical properties and mechanical strength at high temperatures. Furthermore, the handleability (nonvolatility, low viscosity, etc.) when used as a varnish is improved, and the moldability (impregnation ability, fluidity, etc.) of the uncured composition can be improved. Therefore, the copolymer, etc. can be widely and effectively used as an electrical insulating material, and can be particularly effectively used in novel electrical insulating material applications for high frequency bands, such as CCL substrates, FCCL substrates, interlayer insulating materials, antennas, coverlays, etc.

Claims

1. The number average molecular weight (Mn) is 500 or more and less than 12,000, The copolymer comprises an olefin monomer unit, an aromatic vinyl compound monomer unit, and an aromatic polyene monomer unit, having an aromatic vinyl group derived from the aromatic polyene monomer unit, the number of the aromatic vinyl groups per the number average molecular weight (Mn) is 2 or more, and the number average molecular weight (Mn) per aromatic vinyl group is 500 or less; Olefin-aromatic vinyl compound-aromatic polyene copolymer.

2. The content of the olefin monomer unit is 1% by mass or more and 70% by mass or less, The total content of the aromatic vinyl compound monomer units and the aromatic polyene monomer units is 30% by mass or more and less than 99% by mass. The olefin-aromatic vinyl compound-aromatic polyene copolymer according to claim 1.

3. The olefin monomer unit contains at least an α-olefin having 3 or more carbon atoms, The content of the α-olefin having 3 or more carbon atoms is 30% by mass or more and 100% by mass or less based on the total amount of the olefin monomer units. The olefin-aromatic vinyl compound-aromatic polyene copolymer according to claim 1.

4. The olefin monomer unit is a single or multiple unit selected from α-olefins having 2 to 20 carbon atoms, or a combination of an α-olefin having 2 to 20 carbon atoms and a cyclic olefin having 5 to 20 carbon atoms. The olefin-aromatic vinyl compound-aromatic polyene copolymer according to claim 1.

5. The olefin monomer unit is a combination of an α-olefin having 2 to 20 carbon atoms and a cyclic olefin having 5 to 20 carbon atoms. The olefin-aromatic vinyl compound-aromatic polyene copolymer according to claim 4.

6. The total metal content is 1,500 ppm or less The olefin-aromatic vinyl compound-aromatic polyene copolymer according to claim 1.

7. The boron content is 50 ppm or less. The olefin-aromatic vinyl compound-aromatic polyene copolymer according to claim 1.

8. The olefin-aromatic vinyl compound-aromatic polyene copolymer according to claim 1 is included. composition.

9. It also contains hydrocarbon radical curing agents that do not contain oxygen or nitrogen atoms in their structure. The composition of claim 8.

10. Further containing a radical crosslinkable monomer and / or a radical crosslinkable resin component The composition of claim 8.

11. A composition comprising the olefin-aromatic vinyl compound-aromatic polyene copolymer of claim 1. Hardened body.

12. The cured product according to claim 11, CCL substrate, FCCL substrate, interlayer insulation material, antenna, or coverlay.

13. copolymerizing an olefin monomer, an aromatic vinyl compound monomer, and an aromatic polyene monomer in the presence of a coordination polymerization catalyst; synthesizing an olefin-aromatic vinyl compound-aromatic polyene copolymer having a number average molecular weight (Mn) of 500 or more and less than 12,000, comprising an olefin monomer unit, an aromatic vinyl compound monomer unit, and an aromatic polyene monomer unit, having aromatic vinyl groups derived from the aromatic polyene monomer units, the number of the aromatic vinyl groups being 2 or more per number average molecular weight (Mn), and the number average molecular weight (Mn) per aromatic vinyl group being 500 or less; A method for producing an olefin-aromatic vinyl compound-aromatic polyene copolymer.

14. The coordination polymerization catalyst comprises a transition metal compound and a cocatalyst. A method for producing the copolymer according to claim 13.

15. The transition metal compound includes a transition metal compound represented by the following general formula (1): A method for producing the copolymer according to claim 14. 【Chemistry 1】 (In the formula, M is a central metal selected from the group consisting of zirconium, hafnium, and titanium. A and B each independently represent a group selected from the group consisting of a substituted or unsubstituted cyclopentaphenanthryl group, a substituted or unsubstituted benzoindenyl group, a substituted or unsubstituted cyclopentadienyl group, and a substituted or unsubstituted indenyl group. Y is a divalent group bonding to A and B, and is selected from the group consisting of a methylene group, a silylene group, an ethylene group, a germylene group, and a boron residue, which may further have a hydrogen atom or a hydrocarbon group having 1 to 15 carbon atoms (which may further contain 1 to 3 nitrogen atoms, oxygen atoms, sulfur atoms, phosphorus atoms, or silicon atoms) as a substituent, and these substituents may be different or the same. Furthermore, Y may have a cyclic structure. Each X is independently selected from the group consisting of a hydrogen atom, a halogen atom, an alkyl group having 1 to 15 carbon atoms, an aryl group having 6 to 10 carbon atoms, an alkylaryl group having 8 to 12 carbon atoms, a silyl group having a hydrocarbon substituent having 1 to 4 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, and a dialkylamide group having an alkyl substituent having 1 to 6 carbon atoms.

16. The co-catalyst comprises a boron compound. A method for producing the copolymer according to claim 14.

17. the olefin-aromatic vinyl compound-aromatic polyene copolymer contains a copolymerization component derived from an olefin monomer, the olefin monomer comprises an α-olefin having 3 or more carbon atoms, The content of the α-olefin having 3 or more carbon atoms is 30% by mass or more and 100% by mass or less relative to the total amount of the olefin monomers. A method for producing the copolymer according to claim 13.

Images