Copolymer, method for producing the same and cured body containing copolymer

Abstract

To provide a novel copolymer exhibiting excellent low dielectric properties in an uncured state and high elastic modulus at room temperature.SOLUTION: There is provided an α-olefin-cyclic olefin-aromatic polyene copolymer, wherein the dielectric constant of the copolymer in an uncured state at a measurement frequency of 40 GHz is less than 2.4, the dielectric loss tangent is less than 0.0008, and the storage elastic modulus measured at 25°C is 1000 MPa or more.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a copolymer, a method for producing the copolymer, and a cured product containing the copolymer. [Background technology]

[0002] As communication frequencies shift to the gigahertz band and higher, there is a growing need for multilayer substrates made of CCL or FCCL, which contain insulating materials with low dielectric properties. Fluorine-based resins such as perfluoroethylene are characterized by their low dielectric constant, low dielectric loss, and excellent heat resistance, but they have difficulties in moldability and film formability, and also have issues with adhesion to copper foil in wiring, making them difficult to apply to multilayer substrates. Meanwhile, substrates and insulating materials made from post-curing resins such as epoxy resin, unsaturated polyester resin, polyimide resin, and phenolic resin have been widely used due to their heat resistance and ease of handling, but their relatively high dielectric constant and dielectric loss leave room for improvement as insulating materials for high frequencies (Patent Document 1).

[0003] Therefore, hydrocarbon-based resins, which inherently possess low dielectric properties, have attracted attention. In particular, cyclic olefin-based (co)polymers with high glass transition temperatures (Tg) have been proposed as insulating materials for thermoplastic resins (Patent Documents 2 and 3). However, because their glass transition temperatures are close to the solder reflow temperature, crosslinkable (curable) resins are preferable in terms of process compatibility and process window. Converting hydrocarbon-based resins, which are essentially thermoplastic resins, into curable resins requires the introduction of crosslinkable functional groups. However, functional groups that react to radicals or heat generally have polarity, which deteriorates their low dielectric properties. Introducing functional groups composed solely of hydrocarbons, such as aromatic vinyl groups, often requires the use of expensive intermolecular reactions between hydrocarbon-based raw materials (Patent Document 4), which is often uneconomical. Patent Document 5 describes cured products obtained from specific coordination polymerization catalysts and consisting of ethylene-olefin (aromatic vinyl compound)-aromatic polyene copolymers and nonpolar vinyl compound copolymers with specific compositions and blends. This technology selectively copolymerizes only one of the two vinyl groups of an aromatic polyene (divinylbenzene), preserving the remaining vinyl group, making it easy to obtain crosslinkable hydrocarbon copolymer macromonomers with aromatic vinyl functional groups. Cured products obtained from similar olefin-aromatic vinyl compound-aromatic polyene copolymers and compositions containing auxiliary materials and other materials are characterized by low dielectric constants and low dielectric dissipation factors. Depending on the composition and the appropriate selection of auxiliary materials, a wide range of physical properties, from soft to hard, can be achieved (Patent Documents 6 and 7). However, the specifically described olefin-aromatic vinyl compound-aromatic polyene copolymers are relatively soft, and to harden them, large amounts of other crosslinkable hard resins or inorganic fillers must be added. However, known crosslinkable hard resins lack sufficient low dielectric properties, and adding large amounts reduces the low dielectric properties of the cured product. Adding a relatively large amount of inorganic filler generally results in a high dielectric constant, particularly for the resulting cured product, due to the high dielectric constant of inorganic fillers.In addition to being hard, it is important for the cured product to also exhibit a high glass transition temperature (Tg). This allows for a low coefficient of linear expansion (CTE) across the processing temperature range of electronic circuit component manufacturing processes, including solder reflow. Therefore, rigid resins with higher glass transition temperatures are in demand. Furthermore, insulating materials used in circuit boards and other applications are made by mixing and curing various resins, fillers, flame retardants, and other raw materials, and high compatibility with these raw materials is also required. Resins and flame retardants, in particular, contain many aromatic groups to ensure stability and flame resistance at high temperatures, so crosslinkable rigid materials with high compatibility with these materials are in demand. Therefore, there is a demand for materials that are crosslinkable and whose cured products have excellent low dielectric properties, high glass transition temperatures, and high elastic moduli at room and high temperatures. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 6-192392 [Patent Document 2] International Publication No. 1998 / 56011 [Patent Document 3] Japanese Patent Application Laid-Open No. 2016-037045 [Patent Document 4] Japanese Patent Application Laid-Open No. 2004-087639 [Patent Document 5] Japanese Patent Application Laid-Open No. 2007-217706 [Patent Document 6] International Publication No. 2021 / 112087 [Patent Document 7] International Publication No. 2021 / 112088 Summary of the Invention [Problem to be solved by the invention]

[0005] However, the above-mentioned prior art does not describe that an α-olefin-cyclic olefin-aromatic vinyl compound-aromatic polyene copolymer in an uncured state has sufficient levels of low dielectric properties, high glass transition temperature, and high elastic modulus. [Means for solving the problem]

[0006] In view of the above-mentioned problems, the present invention aims to provide a novel cross-linkable copolymer (polymer compound) that is an α-olefin-cyclic olefin-aromatic vinyl compound-aromatic polyene copolymer that has low dielectric constant even in an uncured state, a high glass transition temperature, and a high elastic modulus at room temperature and at high temperatures, and a cured product thereof.

[0007] That is, the present invention can provide the following aspects.

[0008] Aspect 1. An α-olefin-cyclic olefin-aromatic polyene copolymer, wherein the copolymer in an uncured state has a dielectric constant of less than 2.4 and a dielectric dissipation factor of less than 0.0008 at a measurement frequency of 40 GHz, and a storage modulus measured at 25°C of 1000 MPa or more. Aspect 2. An α-olefin-cyclic olefin-aromatic vinyl compound-aromatic polyene copolymer, wherein the copolymer in an uncured state has a dielectric constant of less than 2.4 and a dielectric dissipation factor of less than 0.0008 at a measurement frequency of 40 GHz, and a storage modulus measured at 25°C of 1000 MPa or more.

[0009] Aspect 3. Aspect 3. The copolymer of aspect 1 or 2, wherein the copolymer in an uncured state has a dielectric constant of less than 2.3 and a dielectric loss tangent of less than 0.0004 at a measurement frequency of 40 GHz.

[0010] Aspect 4. A copolymer according to any one of aspects 1 to 3, wherein the copolymer contains 1000 ppm or less of metals derived from the catalyst and the co-catalyst in total.

[0011] Aspect 5. A copolymer according to any one of Aspects 1 to 4, which, when cured alone, exhibits a dielectric constant of less than 3.5 and a dielectric loss tangent of less than 0.001 at a measurement frequency of 40 GHz.

[0012] Aspect 6. Aspect 6. The copolymer according to any one of Aspects 1 to 5, which, when cured alone, has a dielectric constant of less than 2.3 and a dielectric loss tangent of less than 0.0004 at a measurement frequency of 40 GHz.

[0013] Aspect 7. A copolymer according to any one of Aspects 1 to 6, which, when cured alone, has a storage modulus of 1 MPa or more as measured at 280° C. in the cured product.

[0014] Aspect 8. A copolymer according to any one of Aspects 1 to 7, which, when cured alone, has a storage modulus of 5 MPa or more as measured at 280° C. in the cured product.

[0015] Aspect 9. A copolymer according to any one of aspects 1 to 8, which satisfies all of the following (1) to (2) and (4) to (6): (1) The number average molecular weight of the copolymer is 500 or more and 100,000 or less. (2) The α-olefin unit is an α-olefin having 2 to 20 carbon atoms. (4) The cyclic olefin units are cyclic olefin monomer units having from 10 to 30 carbon atoms, and the content thereof is from 30% by mass to 99% by mass. (5) The aromatic polyene unit is one or more polyenes selected from polyenes having 5 to 20 carbon atoms and having a plurality of vinyl groups and / or vinylene groups in the molecule, and the content of vinyl groups and / or vinylene groups derived from the aromatic polyene monomer unit is 2 to 30 per number average molecular weight. (6) The total content of α-olefin units, cyclic olefin units, and aromatic polyene units is 100% by mass.

[0016] Aspect 10. A copolymer according to aspect 2, which satisfies all of the following (1) to (6): (1) The number average molecular weight of the copolymer is 500 or more and 100,000 or less. (2) The α-olefin unit is an α-olefin having 2 to 20 carbon atoms. (3) The aromatic vinyl compound unit is an aromatic vinyl compound having 8 to 20 carbon atoms. (4) The cyclic olefin units are cyclic olefin monomer units having from 10 to 30 carbon atoms, and the content thereof is from 30% by mass to 99% by mass. (5) The aromatic polyene unit is one or more polyenes selected from polyenes having 5 to 20 carbon atoms and having a plurality of vinyl groups and / or vinylene groups in the molecule, and the content of vinyl groups and / or vinylene groups derived from the aromatic polyene monomer unit is 2 to 30 per number average molecular weight. (6) The total content of α-olefin units, cyclic olefin units, aromatic vinyl compound units, and aromatic polyene units is 100% by mass.

[0017] Aspect 11. A copolymer according to any one of Aspects 1 to 10, wherein the cyclic olefin unit comprises at least one selected from the group consisting of norbornene, methylphenylnorbornene, substituted norbornene other than methylphenylnorbornene, and dimethanooctahydronaphthalene.

[0018] Aspect 12. 12. The copolymer according to any one of aspects 1 to 11, having a glass transition temperature in the range of 100°C or higher and 350°C or lower.

[0019] Aspect 13. 13. The copolymer according to any one of aspects 1 to 12, having a number average molecular weight of 500 or more and less than 30,000.

[0020] Aspect 14. A method for producing a copolymer according to any one of Aspects 1 to 13, comprising copolymerizing monomers of an α-olefin, a cyclic olefin, an aromatic polyene, and, if necessary, an aromatic vinyl compound, by coordination polymerization using a coordination polymerization catalyst.

[0021] Aspect 15. Aspect 15. The method for producing a copolymer according to aspect 14, wherein the coordination polymerization catalyst is a polymerization catalyst comprising a transition metal compound represented by the following general formula (1) and a co-catalyst: General formula (1) [ka] In the formula, A and B are each independently a group selected from an unsubstituted or substituted cyclopentaphenanthryl group, an unsubstituted or substituted benzoindenyl group, an unsubstituted or substituted cyclopentadienyl group, and an unsubstituted or substituted indenyl group. Y is bonded to A and B and is a methylene group, silylene group, ethylene group, germylene group, or boron residue having hydrogen or a hydrocarbon group having 1 to 15 carbon atoms (which may contain 1 to 3 nitrogen, oxygen, sulfur, phosphorus, or silicon atoms) as a substituent. The substituents may be different or the same. Y may also have a cyclic structure. X is hydrogen, halogen, 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, or a dialkylamide group having an alkyl substituent having 1 to 6 carbon atoms. M is zirconium, hafnium, or titanium.

[0022] Aspect 16. Aspect 16. The method for producing a copolymer according to aspect 15, wherein A and B in general formula (1) are each independently a group selected from an unsubstituted or substituted cyclopentadienyl group and an unsubstituted or substituted indenyl group.

[0023] Aspect 17. 17. The process of any one of claims 15 to 16, wherein a co-catalyst comprising a boron compound is used.

[0024] Aspect 18. 18. The process of claim 17, wherein the co-catalyst further comprises an aluminum compound.

[0025] Aspect 19. A cured product comprising the copolymer according to any one of aspects 1 to 13.

[0026] Aspect 20. An α-olefin-cyclic olefin-aromatic polyene copolymer satisfying all of the following (1) to (2) and (4) to (6): (1) The number average molecular weight of the copolymer is 500 or more and 100,000 or less. (2) The α-olefin unit is an α-olefin having 2 to 20 carbon atoms. (4) The cyclic olefin units are cyclic olefin monomer units having from 10 to 30 carbon atoms, and the content thereof is from 30% by mass to 99% by mass. (5) The aromatic polyene unit is one or more polyenes selected from polyenes having 5 to 20 carbon atoms and having a plurality of vinyl groups and / or vinylene groups in the molecule, and the content of vinyl groups and / or vinylene groups derived from the aromatic polyene monomer unit is 2 to 30 per number average molecular weight. (6) The total content of α-olefin units, cyclic olefin units, and aromatic polyene units is 100% by mass. one or more additive components selected from the group consisting of a resin component, a curing agent, a monomer, a solvent, and a filler; A cured product of a composition comprising: The hardened body has a dielectric constant of 3.5 or less and a dielectric loss tangent of 0.0015 or less at a measurement frequency of 40 GHz.

[0027] Aspect 21. an α-olefin-cyclic olefin-aromatic vinyl compound-aromatic polyene copolymer that satisfies all of the following (1) to (6); (1) The number average molecular weight of the copolymer is 500 or more and 100,000 or less. (2) The α-olefin unit is an α-olefin having 2 to 20 carbon atoms. (3) The aromatic vinyl compound unit is an aromatic vinyl compound having 8 to 20 carbon atoms. (4) The cyclic olefin units are cyclic olefin monomer units having from 10 to 30 carbon atoms, and the content thereof is from 30% by mass to 99% by mass. (5) The aromatic polyene unit is one or more polyenes selected from polyenes having 5 to 20 carbon atoms and having a plurality of vinyl groups and / or vinylene groups in the molecule, and the content of vinyl groups and / or vinylene groups derived from the aromatic polyene monomer unit is 2 to 30 per number average molecular weight. (6) The total content of α-olefin units, cyclic olefin units, aromatic vinyl compound units, and aromatic polyene units is 100% by mass. one or more additive components selected from the group consisting of a resin component, a curing agent, a monomer, a solvent, and a filler; A cured product of a composition comprising: The hardened body has a dielectric constant of 3.5 or less and a dielectric loss tangent of 0.0015 or less at a measurement frequency of 40 GHz.

[0028] Aspect 22. A cured product according to any one of aspects 19 to 21, further having a storage modulus measured at 25°C of 1000 MPa or more and a storage modulus measured at 280°C of 1 MPa or more.

[0029] Aspect 23. Aspects 19 to 22: The cured product according to any one of aspects 19 to 22, which is an electrical insulating material.

[0030] Aspect 24. A CCL substrate, an FCCL substrate, an interlayer insulating material, a coverlay, a high-frequency transmission circuit, or an antenna, comprising the cured product according to embodiment 23.

[0031] Aspect 25. A method for producing a cured product, comprising the step of polymerizing at least the copolymer according to any one of Aspects 1 to 13 using a radical polymerization initiator that does not contain oxygen or nitrogen atoms in its structure and is composed only of carbon atoms and hydrogen atoms. [Effects of the Invention]

[0032] The copolymer according to the present invention has excellent low dielectric properties even in an uncured state, a high modulus of elasticity at room temperature, and is curable. Furthermore, a cured product of the copolymer exhibits excellent low dielectric properties, a high glass transition temperature, and a high modulus of elasticity at room temperature and at high temperatures. If the copolymer satisfies the above-mentioned properties in an uncured state, a cured product containing the copolymer also satisfies these properties. DETAILED DESCRIPTION OF THE INVENTION

[0033] This will be explained in more detail below. In this specification, the α-olefin-cyclic olefin-aromatic polyene copolymer is included in the α-olefin-cyclic olefin-aromatic vinyl compound-aromatic polyene copolymer and may be collectively referred to by the latter name. In this specification, the α-olefin-cyclic olefin-aromatic vinyl compound-aromatic polyene copolymer may be simply referred to as the copolymer of the present invention or simply as the copolymer. Unless otherwise specified, the numerical ranges in this specification include the upper and lower limits. In this specification, the term sheet also encompasses the concept of film. Furthermore, the term film in this specification is intended to have the same meaning as sheet. Furthermore, the term film in this specification is also intended to encompass the concept of sheet. In this specification, the term "uncured state" is defined as an α-olefin-cyclic olefin-aromatic vinyl compound-aromatic polyene copolymer having a gel fraction (gel content) of 20% by mass or less, more strictly 10% by mass or less, and most strictly 5% by mass or less. The gel content is a value obtained by measurement in accordance with JIS K6796:1998 or measurement in accordance with ASTM D2765-84, which corresponds to ISO10147:1994, which corresponds to JIS.

[0034] In one embodiment of the present invention, an α-olefin-cyclic olefin-aromatic vinyl compound-aromatic polyene copolymer can be provided. In an uncured state, the copolymer may have a dielectric constant of less than 2.4, preferably less than 2.3, or 2.0 or greater, and a dielectric dissipation factor of less than 0.0008, preferably less than 0.0004, and more preferably less than 0.0003 and 0.0001 or greater, measured at a frequency of 40 GHz. Furthermore, the copolymer has a storage modulus measured at 25°C of 1000 MPa or greater. When the copolymer is cured alone, the resulting cured product may have a dielectric constant of less than 3.5 and a dielectric dissipation factor of less than 0.0010, preferably a dielectric constant of 2.0 or greater but less than 3.5, and a dielectric dissipation factor of 0.0001 or greater but less than 0.0010, more preferably a dielectric constant of less than 2.4, or a dielectric dissipation factor of 2.0 or greater but less than 0.0004, and most preferably a dielectric constant of less than 2.3 and a dielectric dissipation factor of less than 0.0003 but 0.0001 or greater. Furthermore, the storage modulus measured at 25° C. may be 1000 MPa or more. Furthermore, the storage modulus of the cured product measured at 280° C. may be preferably 1 MPa or more, more preferably 5 MPa or more.

[0035] In another embodiment, it is also possible to provide an embodiment in which the dielectric constant or dielectric loss tangent in the uncured state does not satisfy the above conditions, but the dielectric constant, dielectric loss tangent, and storage modulus of the cured product satisfy the above conditions.

[0036] <α-olefin-cyclic olefin-aromatic polyene copolymer> Furthermore, the α-olefin-cyclic olefin-aromatic polyene copolymer of the present invention is a copolymer having each of the monomer units of α-olefin, cyclic olefin, and aromatic polyene, and can be produced by any method. Preferably, the α-olefin-cyclic olefin-aromatic polyene copolymer satisfies all of the following (1) to (2) and (4) to (6): (1) The number average molecular weight of the copolymer is 500 or more and 100,000 or less. (2) The α-olefin unit is an α-olefin having 2 to 20 carbon atoms. (4) The cyclic olefin unit is a cyclic olefin monomer having 10 to 30 carbon atoms which may have an aromatic ring, and the content thereof is 30% by mass to 99% by mass. (5) The aromatic polyene unit is one or more polyenes selected from polyenes having 5 to 20 carbon atoms and having a plurality of vinyl groups and / or vinylene groups in the molecule, and the content of vinyl groups and / or vinylene groups derived from the aromatic polyene monomer units is 2 to 30 or 2 to less than 30 per number average molecular weight. (6) The total amount of the α-olefin, cyclic olefin, and aromatic polyene monomer units is 100% by mass.

[0037] The present α-olefin-cyclic olefin-aromatic polyene copolymer can be obtained by copolymerizing the α-olefin, cyclic olefin, and aromatic polyene monomers.

[0038] <α-olefin-cyclic olefin-aromatic vinyl compound-aromatic polyene copolymer> In some embodiments of the present invention, it is preferred to use an aromatic vinyl compound to obtain an α-olefin-cyclic olefin-aromatic vinyl compound-aromatic polyene copolymer. In this specification, the α-olefin-cyclic olefin-aromatic polyene copolymer is sometimes included in the α-olefin-cyclic olefin-aromatic vinyl compound-aromatic polyene copolymer, and may be collectively referred to by the latter name. Furthermore, the α-olefin-cyclic olefin-aromatic vinyl compound-aromatic polyene copolymer of the present invention is a copolymer having each of the monomer units of α-olefin, cyclic olefin, aromatic vinyl compound, and aromatic polyene, and can be produced by any method. Preferably, the α-olefin-cyclic olefin-aromatic vinyl compound-aromatic polyene copolymer is a copolymer that satisfies all of the following (1) to (6): (1) The number average molecular weight of the copolymer is 500 or more and 100,000 or less. (2) The α-olefin unit is an α-olefin having 2 to 20 carbon atoms. (3) The aromatic vinyl compound unit is an aromatic vinyl compound having 8 to 20 carbon atoms. (4) The cyclic olefin unit is a cyclic olefin monomer having 10 to 30 carbon atoms which may have an aromatic ring, and the content thereof is 30% by mass to 99% by mass. (5) The aromatic polyene unit is one or more polyenes selected from polyenes having 5 to 20 carbon atoms and having a plurality of vinyl groups and / or vinylene groups in the molecule, and the content of vinyl groups and / or vinylene groups derived from the aromatic polyene monomer units is 2 to 30 or 2 to less than 30 per number average molecular weight. (6) The total amount of the monomer units of the α-olefin, cyclic olefin, aromatic vinyl compound, and aromatic polyene is 100% by mass.

[0039] The present α-olefin-cyclic olefin-aromatic vinyl compound-aromatic polyene copolymer can be obtained by copolymerizing the α-olefin, cyclic olefin, aromatic vinyl compound, and aromatic polyene monomers.

[0040] The α-olefin monomer is an α-olefin having 2 to 20 carbon atoms, such as ethylene, propylene, 1-butene, 1-hexene, 1-octene, 1-decene, 1-dodecene, 4-methyl-1-pentene, and 3,5,5-trimethyl-1-hexene, with ethylene being the most preferred. The α-olefin content in the copolymer is arbitrary, but is preferably 0% to 40% by mass, more preferably 0% to 30% by mass, even more preferably 1% to 30% by mass, and most preferably 5% to 30% by mass. When the α-olefin monomer unit content is 40% by mass or less, the content of cyclic olefin units is relatively high, allowing the glass transition temperature of the copolymer to fall within a preferred range. The higher the α-olefin monomer unit content (e.g., 5% by mass or more), the less brittle the copolymer and its cured product become.

[0041] As used herein, the term "cyclic olefin monomer" refers to a cyclic olefin having 7 to 30 carbon atoms (preferably 10 to 30 carbon atoms). Cyclic olefins having 7 to 30 carbon atoms include cyclic olefins having one or more alicyclic structures in the molecule and a polymerizable vinyl, vinylene, or vinylidene group. Preferred cyclic olefins are those having a hydrocarbon ring structure without heteroatoms, and more preferably those having an unsaturated hydrocarbon ring. These cyclic olefins have the distinct advantage of low dielectric properties and high glass transition temperatures, while being easily prepared using inexpensive raw materials and simple processes compared to conventional engineering plastics. Examples of such cyclic olefins include norbornenes. Norbornenes are monomers selected from norbornene and substituted norbornenes. Norbornene can be synthesized, for example, by the Diels-Alder reaction of ethylene and cyclopentadiene. Substituted norbornenes are substituted norbornenes containing a polymerizable vinyl, vinylene, or vinylidene group in the molecule, such as dimethanooctahydronaphthalene (DMON) and trimethanododecahydroanthracene (TMDA). These are also Diels-Alder reaction products of norbornenes and cyclopentadiene. These substituted norbornenes are specifically described, for example, in International Publication No. 2006 / 118261. In the present invention, more preferred cyclic olefins have a larger number of ring structures and a higher molecular weight, such as dimethanooctahydronaphthalene (DMON) and trimethanododecahydroanthracene (TMDA). Copolymerization of such cyclic olefins allows for the production of copolymers with higher glass transition temperatures (Tg) at lower mol% content of the monomer units. This allows for the copolymer to maintain a high glass transition temperature while increasing the mol% content of other monomer units. Increasing the mole percent content of aromatic vinyl compound monomer units as other monomer units is preferred because it increases the aromatic properties of the copolymer as a whole and improves the compatibility of the copolymer with other raw materials and resins.These high-molecular-weight cyclic olefins may be used alone or in mixtures with norbornene or the like for copolymerization. In particular, the above-mentioned DMON and TMDA may be obtained as mixtures with norbornene when produced by the Diels-Alder reaction, and using the mixture as is for polymerization can reduce production costs. In the present invention, more preferred cyclic olefins are norbornenes having aromatic substituents, such as phenylnorbornene (5-phenylbicyclo[2.2.1]hept-2-ene), a Diels-Alder reaction product of cyclopentadiene and styrene; indanylnorbornene (1,4-methano-1,9a,4,4a-tetrahydrofluorene), a Diels-Alder reaction product of cyclopentadiene and indene; and methylphenylnorbornene (MPNB, 5-methyl-5-phenylbicyclo[2.2.1]hept-2-ene), a Diels-Alder reaction product of cyclopentadiene and α-methylstyrene. When copolymerized, norbornenes with such aromatic substituents can impart a higher glass transition temperature (Tg) to the resulting copolymer. Furthermore, due to their aromaticity, they exhibit high compatibility with other aromatic raw materials (crosslinkable soft resins and flame retardants). Furthermore, the use of methylphenylnorbornene (5-methyl-5-phenylbicyclo[2.2.1]hept-2-ene) is preferred because it improves the thermal oxidation resistance of the resulting copolymer, as described in JP 2005-239975 A. Norbornenes with these aromatic substituents are specifically described in, for example, JP 11-504669 A and JP 2005-239975 A. The optimal content of cyclic olefin units in the copolymer varies depending on the type of cyclic olefin, but is, for example, 50% to 99% by mass, preferably 50% to 95% by mass, more preferably 70% to 95% by mass, and most preferably 80% to 95% by mass. The optimum content of the cyclic olefin units contained in the present copolymer may be less than 90% by mass from the viewpoint of imparting a certain degree of toughness to the copolymer. A content within this range makes it easier to achieve a desirable high glass transition temperature of the copolymer.The glass transition temperature of the copolymer is preferably 100° C. or higher and 350° C. or lower, more preferably 130° C. or higher and 300° C. or lower, and most preferably 180° C. or higher and 300° C. or lower. Those skilled in the art can appropriately adjust the type and content of the cyclic olefin used to achieve this preferred glass transition temperature.

[0042] In a preferred embodiment, the cyclic olefin units contained in the copolymer may include one or more selected from the group consisting of norbornene, methylphenylnorbornene, substituted norbornenes other than methylphenylnorbornene, and dimethanooctahydronaphthalene, and more preferably, may include one or more selected from the group consisting of norbornene, methylphenylnorbornene, and dimethanooctahydronaphthalene.

[0043] The aromatic vinyl compound monomer is an aromatic vinyl compound having from 8 to 20 carbon atoms, such as styrene, paramethylstyrene, ethylvinylbenzene, paraisobutylstyrene, various vinylnaphthalenes, and various vinylanthracenes. The aromatic vinyl compound may be copolymerized with components contained as impurities in the aromatic polyene used for polymerization, resulting in the copolymer. The content of aromatic vinyl compound monomer units contained in the copolymer is optional, but is preferably from 0 to 40% by mass, more preferably from 0 to 30% by mass, even more preferably from 0 to 20% by mass, still more preferably from 0 to 10% by mass, and even more preferably 0% by mass. The content of aromatic vinyl compound monomer units contained in the copolymer may exceed 0% by mass. The content of aromatic vinyl compound monomer units contained in the copolymer may be 30% by mass or less, less than 30% by mass, 10% by mass or less, less than 10%, 1% by mass or less, less than 1% by mass, or less than 0.5% by mass.

[0044] When the content of aromatic vinyl compound monomer units is 40% by mass or less, the content of cyclic olefin units is relatively high, making it possible to increase the glass transition temperature of the copolymer. On the other hand, when the content of aromatic vinyl compound monomer units is 10% by mass or more, preferably 30% by mass or more, it is possible to improve the aromaticity of the copolymer, especially when the cyclic olefin in the copolymer of the present invention does not have an aromatic substituent, and this is preferable because it improves compatibility with other resin materials, flame retardants, and fillers, suppresses bleed-out of flame retardants, and facilitates high filler loading. As described above, the glass transition temperature and aromaticity of the copolymer can be adjusted by the aromatic vinyl compound content of the copolymer.

[0045] The aromatic polyene monomer is a polyene having 5 to 20 carbon atoms and containing multiple vinyl and / or vinylene groups in its molecule, preferably a polyene having 8 to 20 carbon atoms. The aromatic polyene monomer is preferably a polyene having 8 to 20 carbon atoms and containing multiple vinyl groups in its molecule, more preferably a compound having an aromatic vinyl structure, such as ortho-, meta-, or para-divinylbenzenes or mixtures thereof, divinylnaphthalene, divinylanthracene, p-2-propenylstyrene, or p-3-butenylstyrene, and consisting essentially of carbon and hydrogen without containing oxygen, nitrogen, or halogen. Bifunctional aromatic vinyl compounds, such as 1,2-bis(vinylphenyl)ethane (abbreviation: BVPE), described in JP 2004-087639 A, can also be used. Among these, ortho-, meta-, or para-divinylbenzenes or mixtures thereof are preferred, and a mixture of meta- and para-divinylbenzene is most preferred. In this specification, these divinylbenzenes are referred to as divinylbenzenes. When a divinylbenzene is used as the aromatic polyene, the vinyl group contained in the divinylbenzene unit is preferred because it has high crosslinking efficiency during curing treatment and facilitates curing.

[0046] The number-average molecular weight of the copolymer is preferably 500 to 100,000, more preferably 500 to 30,000, or less than 30,000, even more preferably 500 to 15,000, or less than 15,000, and even more preferably 500 to 12,000, or less than 12,000. A number-average molecular weight of 500 or greater improves the mechanical properties of the composition in the uncured state and provides appropriate adhesion, facilitating molding and processing as a thermoplastic resin. A number-average molecular weight of 30,000 or less improves molding processability. A number-average molecular weight of 30,000 or less is particularly advantageous because it allows the viscosity of a varnish containing the copolymer to be kept below a certain value. A varnish viscosity lower than a certain value improves workability and facilitates impregnation of glass fibers and the like with the varnish, improving embedding properties in semiconductor devices with uneven surfaces.

[0047] In the copolymer, the content of vinyl groups and / or vinylene groups derived from aromatic polyene units is 2 to 30, preferably 3 to 20, per number-average molecular weight. The content of vinyl groups and / or vinylene groups derived from aromatic polyene units may be less than 30, preferably less than 20, per number-average molecular weight. The content of vinyl groups and / or vinylene groups may be collectively referred to as the "vinyl group content" below. Since vinyl groups are superior to vinylene groups in terms of crosslinking efficiency, in the present invention, the content of vinyl groups (excluding vinylene groups in this case) derived from aromatic polyene units is preferably 2 to 30, preferably 3 to 20, per number-average molecular weight. A vinyl group content of 2 or more results in high crosslinking efficiency and a cured product with sufficient crosslink density. Increasing the vinyl group content facilitates improving the mechanical properties of the final cured product at room temperature and high temperature. The vinyl group content derived from aromatic polyene units (divinylbenzene units) per number average molecular weight in the copolymer is determined by 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, and 1H-NMR measurement and / or quantitative mode 13 This can be obtained by comparing the composition obtained by C-NMR measurement with the vinyl group content derived from the aromatic polyene units. Such a method is obvious and well known to those skilled in the art. It can also be achieved by the methods described in the patent documents in the prior art literature of this specification. The content of aromatic polyene monomer units in the copolymer is arbitrary, but is preferably less than 40% by mass, more preferably less than 30% by mass. At such a content, the number of crosslinking groups is appropriately suppressed, resulting in improved stability during copolymer production and curing.

[0048] In the present copolymer, the α-olefin-cyclic olefin-aromatic vinyl compound-aromatic polyene copolymer may, for example, be at least one member selected from the group consisting of propylene-norbornene-styrene-divinylbenzene copolymer, 1-hexene-norbornene-styrene-divinylbenzene copolymer, 1-octene-norbornene-styrene-divinylbenzene copolymer, ethylene-norbornene-ethylvinylbenzene-divinylbenzene copolymer, propylene-styrene-norbornene-divinylbenzene copolymer, 1-hexenestyrene-styrene-norbornene-divinylbenzene copolymer, and 1-octene-norbornene-styrene-divinylbenzene copolymer. Further, copolymers in which the above-mentioned norbornene is replaced with dimethanooctahydronaphthalene (DMON), trimethanododecahydroanthracene (TMDA), phenylnorbornene (5-phenylbicyclo[2.2.1]hept-2-ene), or methylphenylnorbornene (5-methyl-5-phenylbicyclo[2.2.1]hept-2-ene) are also suitable examples of copolymers of the present invention.

[0049] In an α-olefin-cyclic olefin-aromatic polyene copolymer or α-olefin-cyclic olefin-aromatic vinyl compound-aromatic polyene copolymer according to certain embodiments, an embodiment in which the content of α-olefin monomer units is 0% by mass (i.e., no α-olefin monomer units are included) can also be provided. Such copolymers are also referred to herein as "cyclic olefin-aromatic polyene copolymers" or "cyclic olefin-aromatic vinyl compound-aromatic polyene copolymers." The copolymer according to this embodiment is described below. Here, the types of the cyclic olefin, aromatic vinyl compound, and aromatic polyene monomers, and the content of each monomer unit in the copolymer are as described above.

[0050] The above-described cyclic olefin-aromatic polyene copolymer or cyclic olefin-aromatic vinyl compound-aromatic polyene copolymer can be produced by the production method described herein. Specifically, it can be produced from the respective monomers of a cyclic olefin, an aromatic vinyl compound, and an aromatic polyene using a coordination polymerization catalyst comprising a transition metal compound and a cocatalyst. The chemical structure of the copolymer obtained using a coordination polymerization catalyst comprising a combination of a transition metal compound and a cocatalyst is characterized by the absence of a specific structure. That is, while conventional copolymers obtained by cationic polymerization methods according to prior art have characteristic polymer terminal structures such as those described in WO 2018 / 181842, the copolymers according to embodiments of the present invention have a notable difference in that they do not have such structures. This difference allows the present invention to achieve the effect of facilitating molecular design.

[0051] The polymer terminal structure contained in the cyclic olefin-aromatic polyene copolymer or the cyclic olefin-aromatic vinyl compound-aromatic polyene copolymer is 1 H-NMR, 13This can be qualitatively or quantitatively clarified by known methods using C-NMR. A typical example of such a copolymer is a cyclic olefin-aromatic vinyl compound-aromatic polyene copolymer composed of norbornene, DMON, or MPNB as the cyclic olefin, styrene or ethylvinylbenzene as the aromatic vinyl compound, and divinylbenzene as the aromatic polyene. The polymer end structure contained therein is substantially one of the structures represented by E-1 to E-8 below, or any combination thereof. In the case of cyclic olefins other than those mentioned above, aromatic vinyl compounds other than those mentioned above, or aromatic polyenes other than divinylbenzene, these structural formulas can be understood by replacing them with the corresponding structures. "Substantially" indicates that 90 mol% or more, preferably 95 mol% or more, and most preferably 99 mol% or more of the total end structures of the copolymer are one of the structures represented by E-1 to E-8 below, or any combination thereof.

[0052] [ka]

[0053] In the above formula, P represents a polymer structural residue of norbornene (or DMNO or MPNB)-styrene (or ethylvinylbenzene)-divinylbenzene copolymer, and Z represents hydrogen, an ethyl group, or a vinyl group.

[0054] When the cyclic olefin is DMON or MPNB, the structure including the substituents R1 and R2 is as shown below.

[0055] [ka]

[0056] The polymerization initiation terminals, which account for approximately half of the polymer terminal structures, are generally E-1, E-2, E-4, and E-5. These structures are saturated terminals, and therefore aromatic vinyl compound-aromatic polyene copolymers inherently possess high durability, including heat resistance. The proportion of polymerization initiation terminal structures varies depending on various factors, such as whether the initial monomer insertion occurs into a metal-hydrogen bond or into a metal-alkyl group structure, whether the initial monomer insertion occurs with a cyclic olefin, styrene, or divinylbenzene, and whether the initial monomer is 2,1 insertion or 1,2 insertion when styrene or divinylbenzene is used.

[0057] Furthermore, among polymer end structures, the chain transfer ends (also called polymerization termination ends) of growing polymer chains generally consist of E-1, E-6, and E-8, with E-3, E-4, and E-7 also included. The proportion of chain transfer end structures can vary depending on whether chain transfer occurs by hydrogen abstraction at the beta position, chain transfer to another coordination monomer, chain transfer to an alkylaluminum cocatalyst component, or chain transfer to a chain transfer agent such as hydrogen. Cyclic olefins generally have a rigid structure, so there is little E-3 structure resulting from hydrogen abstraction at the beta position.

[0058] The polymer terminal structure of the above cyclic olefin-aromatic polyene copolymer or cyclic olefin-aromatic vinyl compound-aromatic polyene copolymer is in any case composed of one or more of the structures E-1 to E-8 above, and does not substantially contain other structures. The aromatic vinyl compound-aromatic polyene copolymer which may contain an olefin according to the present invention is obtained by specific coordination polymerization, and is therefore a copolymer with a relatively low degree of polymer chain branching and high linearity, and the proportion of polymer terminal structures contained is itself relatively small.

[0059] Examples of polymers obtained by cationic polymerization according to the prior art are compared with those of the present invention. The characteristic terminal structures (structures designated as t1 and t2 in WO 2018 / 181842) formed by chain transfer, such as electrophilic substitution reactions of a carbocation at the polymer growing end to an aromatic monomer or an aromatic ring contained in the polymer itself, as described in WO 2018 / 181842, are not included in the copolymers of the present invention. On the other hand, the aromatic vinyl compound-aromatic polyene copolymer according to the prior art described in WO 2018 / 181842 contains a large number of terminal structures per polymer molecule due to its dendritic, multi-branched structure. The terminal structures described therein are mostly unsaturated structures of vinyl groups or vinylene groups with diverse structures due to cationic polymerization, which poses challenges in heat resistance stability. In particular, the relatively large amount of vinylene groups remains in large quantities in the cured product even after the curing reaction, thereby impairing the heat resistance stability after curing. This problem has not been resolved. That is, if a large number of unsaturated groups such as vinylene groups are present in the cured product, they will bond with or react with oxygen in the air, undesirably increasing the dielectric constant and dielectric loss tangent of the cured product.

[0060] Furthermore, Japanese Patent Application Laid-Open No. 2018-39995 also describes a conventional cyclic olefin-aromatic vinyl compound-aromatic polyene copolymer obtained by a similar cationic polymerization. While this patent document does not describe the terminal structure, the same manufacturing method as in WO 2018 / 181842 is used. The majority of the resulting polymer is composed of aromatic polyene and aromatic vinyl compound units, contains a high content of aromatic polyene (divinylbenzene) units, and has a similarly large molecular weight distribution (Mw / Mn). Based on this, it is believed to have a terminal structure similar to that described in WO 2018 / 181842, and to have a dendritic multi-branched structure. Because part of the terminal structure contains a cyclic olefin structure, it is possible to reduce the proportion of unsaturated groups at the terminals. The increase in the dielectric constant and dielectric loss tangent after heat resistance testing was also reduced compared to when the cyclic olefin was not included, but this is still not considered sufficient. In contrast to the dendritic structure with many terminal groups of the prior art, the copolymer of the present invention has a relatively linear structure, and the number of terminal structures per copolymer molecule is small. Furthermore, cyclic olefins are not unevenly distributed at the terminals of the copolymer, so the number of cyclic olefin terminals per copolymer molecule can generally be less than 1.5.

[0061] The α-olefin-cyclic olefin-aromatic vinyl compound-aromatic polyene copolymer of the present invention can be sufficiently cured by being cured alone. Here, "curing alone" refers to adding a curing agent (peroxide or other radical polymerization initiator) in an amount of 1 part by mass or less per 100 parts by mass of the copolymer and curing under appropriate curing conditions for the peroxide used. The degree of curing can be evaluated by the gel content, which is greater than 50%, preferably greater than 90%, and particularly preferably greater than 95%. The resulting cured product exhibits excellent low dielectric properties, a high glass transition temperature, and a high modulus of elasticity at room temperature and at high temperatures. Specifically, the dielectric constant of the cured product may be 3.5 or less, preferably 2.0 to 3.5, more preferably 2.0 to less than 3.5, and even more preferably 2.0 to less than 2.5. The dielectric dissipation factor of the cured product may be less than 0.001, preferably 0.0002 to less than 0.001, and substantially 0.0005 to less than 0.001. The glass transition temperature can be any value, but can be from 100°C to 350°C, preferably from 130°C to 300°C. The storage modulus measured at 25°C can be 1000 MPa or higher, and the storage modulus measured at 280°C can be 1 MPa or higher, more preferably 5 MPa or higher. Here, the gel fraction is a value obtained in accordance with the aforementioned JIS K6796:1998 (or ASTM D2765-84, which corresponds to ISO10147:1994, which corresponds to the JIS), and the dielectric constant and dielectric dissipation factor are values ​​obtained at 25°C and 40 GHz. The glass transition temperature and storage modulus at each temperature are obtained by dynamic mechanical analysis (DMA) at a measurement frequency of 1 Hz. Therefore, it is possible to obtain a cured product with a sufficiently high gel fraction by curing a composition containing this copolymer, and the cured product can exhibit excellent low dielectric properties, a high glass transition temperature, and a high storage modulus at room temperature and at high temperatures.

[0062] <Composition containing the copolymer of the present invention> The copolymer of the present invention can be cured alone, but it can also be combined with other materials to form a composition, and the composition can be cured. Here, the other materials can include the following "resin component," "curing agent," "monomer," "other olefin-aromatic vinyl compound-aromatic polyene copolymer not containing a cyclic olefin," "solvent," "filler," "other additives," etc.

[0063] <Resin component> Any resin component can be used as long as it does not impair the effects of the present invention, but preferably one or more selected from hydrocarbon elastomers, polyether resins, aromatic polyene resins, and olefin-aromatic vinyl compound-aromatic polyene copolymers containing no cyclic olefins can be used. Of these, hydrocarbon elastomers and olefin-aromatic vinyl compound-aromatic polyene copolymers containing no cyclic olefins are more preferred. Among hydrocarbon elastomers, conjugated diene polymers are preferred. Among conjugated diene polymers, 1,2-polybutadiene is preferred. The amount of resin components may be preferably 1 to 500 parts by mass in total, more preferably 1 to 300 parts by mass in total, per 100 parts by mass of the copolymer of the present invention.

[0064] <Hydrocarbon elastomer> The hydrocarbon-based elastomer suitable for use in the composition of the present invention may have a number-average molecular weight of 20,000 or more, preferably 30,000 or more. Examples of hydrocarbon-based elastomers include single or multiple elastomers selected from ethylene-based or propylene-based elastomers, conjugated diene polymers, block or random copolymers of aromatic vinyl compounds and conjugated dienes, and hydrogenated products thereof. Examples of ethylene-based elastomers include ethylene-α-olefin copolymers such as ethylene-octene copolymers and ethylene-1-hexene copolymers, EPR, and EPDM. Examples of propylene-based elastomers include atactic polypropylene, low stereoregular polypropylene, and propylene-α-olefin copolymers such as propylene-1-butene copolymer. These hydrocarbon-based elastomers may be modified, for example, by introducing functional groups using maleic anhydride or other compounds.

[0065] <Conjugated diene polymer> Examples of conjugated diene polymers include polybutadiene and 1,2-polybutadiene. Examples of aromatic vinyl compound-conjugated diene block or random copolymers and their hydrogenated products (hydrogenated products) include SBS, SIS, SEBS, SEPS, SEEPS, and SEEBS. Suitable 1,2-polybutadiene is available, for example, as a product from JSR Corporation, and also from Nippon Soda Co., Ltd. under the product names of liquid polybutadiene: B-1000, 2000, and 3000. Another suitable copolymer containing a 1,2-polybutadiene structure is "Ricon 100" from TOTAL CRAY VALLEY. These conjugated diene polymers and their hydrogenated products may be modified, for example, by introducing functional groups with maleic anhydride or other compounds. Among conjugated diene polymers, conjugated diene copolymers are preferred. Among these conjugated diene copolymers, hydrogenated block copolymers such as SEBS, SEPS, SEEPS, and SEEBS are useful as compatibilizers for the copolymer of the present invention and other resin components. These are available from Asahi Kasei under the trade names Tuftec or SOE-SS, from Kuraray Co., Ltd. under the trade name Septon, and from KRATON under the trade name Kraton.

[0066] <Polyether resin> Examples of polyether-based resins include polyphenylene ether and polyether. Polyphenylene ethers having functional groups are preferably those in which the molecular terminals are modified with functional groups. Furthermore, when added for the purpose of curing the composition of the present invention, 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 radically polymerizable functional groups are preferred. The radically polymerizable functional group is preferably a vinyl group. As the vinyl group, one or more of the group consisting of an allyl group, a (meth)acryloyl group, and an aromatic vinyl group are preferred, and one or more of the group consisting of a (meth)acryloyl group and an aromatic vinyl group are more preferred, with an aromatic vinyl group being the most preferred. In other words, in the composition of the present invention, 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 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. Of these, the bifunctional polyphenylene ether oligomer (OPE-2St) manufactured by Mitsubishi Gas Chemical Company, Inc. and aromatic polyethers (ELPAC HC-F series) manufactured by JSR Corporation are preferred.

[0067] <Aromatic polyene resin> Aromatic polyene resins include divinylbenzene-based reactive hyperbranched copolymers (PDV or ODV) manufactured by Nippon Steel Chemical & Material Co., Ltd. Such copolymers are described, for example, in the literature "Synthesis of polyfunctional aromatic vinyl copolymers and development of new IPN-type low dielectric loss materials using the same" (Kawabe Masanao et al., Journal of the Japan Institute of Electronics Packaging, p. 125, Vol. 12 No. 2 (2009)).

[0068] <Another olefin-aromatic vinyl compound-aromatic polyene copolymer that does not contain cyclic olefin> Another olefin-aromatic vinyl compound-aromatic polyene copolymer that does not contain a cyclic olefin and that can be used in the present invention is an olefin-aromatic vinyl compound-aromatic polyene copolymer that satisfies all of the following (A) to (E): (A) The number average molecular weight of the copolymer is 500 or more and 100,000 or less. (B) The olefin monomer unit is one or more α-olefins selected from α-olefins having from 2 to 20 carbon atoms, and the olefins do not include cyclic olefins. (C) The aromatic vinyl compound monomer unit is an aromatic vinyl compound having 8 to 20 carbon atoms, and the content of the aromatic vinyl compound monomer unit is 0 to 90 mass %. (D) The aromatic polyene monomer unit is one or more polyenes selected from polyenes having 5 to 20 carbon atoms and containing a plurality of vinyl groups and / or vinylene groups in the molecule, and the content of vinyl groups and / or vinylene groups derived from the aromatic polyene unit per number average molecular weight is 2 to 30. The content of vinyl groups and / or vinylene groups derived from the aromatic polyene unit per number average molecular weight may be 2 to less than 30. (E) The total of the olefin monomer units, aromatic vinyl compound monomer units, and aromatic polyene monomer units is 100% by mass. Details of the α-olefin, aromatic vinyl compound, and aromatic polyene monomers are as described above. Such copolymers are specifically described in JP 2009-161743 A, WO 2021 / 112087, WO 2021 / 112088, and WO 2022 / 014599. However, as described above, these other copolymers do not contain cyclic olefins. Among olefin-aromatic vinyl compound-aromatic polyene copolymers that do not contain cyclic olefins, copolymers with an aromatic vinyl compound monomer content of 0 to 60% by mass are particularly soft, and therefore, by blending them with the copolymer of the present invention, the toughness of the resulting cured body can be improved and cracking can be suppressed, making them preferable.

[0069] <Curing agent> The curing agent that may be contained in the composition may be a known curing agent that can be used for the polymerization or curing of conventional aromatic polyenes and aromatic vinyl compounds. Examples of such curing agents include radical polymerization initiators, cationic polymerization initiators, and anionic polymerization initiators, but radical polymerization initiators are preferred. Organic peroxides, azo polymerization initiators, etc. are preferred, and can be freely selected depending on the application and conditions. A catalog listing organic peroxides can be found on the NOF Corporation website, for example. https: / / www.nof.co.jp / product-search / family / 1020001 The following information can be downloaded from the website. Organic peroxides are also listed in catalogs from Fujifilm Wako Pure Chemical Industries, Ltd. and Tokyo Chemical Industry Co., Ltd. The curing agents used in the present invention are available from these companies. Furthermore, hydrocarbon-based radical polymerization initiators, i.e., those composed only of carbon and hydrogen atoms and containing no oxygen or nitrogen atoms in their structure, such as 2,3-dimethyl-2,3-diphenylbutane, can also be used. Producing a cured product using such hydrocarbon-based radical polymerization initiators can yield cured products with lower dielectric constants and dielectric dissipation factors, thereby further improving the low dielectric properties of the cured product. Known photopolymerization initiators that utilize light, ultraviolet light, or radiation can also be used as curing agents. Examples of curing agents that use photopolymerization initiators include photoradical polymerization initiators, photocationic polymerization initiators, and photoanionic polymerization initiators. Such photopolymerization initiators are available, for example, from Tokyo Chemical Industry Co., Ltd. Furthermore, curing using radiation or electron beams themselves is also possible. Crosslinking and curing by thermal polymerization of the raw materials contained in the product without the use of a curing agent is also possible.

[0070] There are no particular restrictions on the amount of curing agent used, but generally, an amount of 0.01 to 10 parts by mass per 100 parts by mass of the composition (preferably excluding the curing agent and solvent) is preferred. When using a curing agent such as a peroxide or azo-based polymerization initiator, the curing process should be carried out at an appropriate temperature and time, taking into account its half-life. In this case, the conditions can be determined based on the curing agent, but a temperature range of approximately 50°C to 180°C is generally appropriate.

[0071] <Monomer> The composition of the present invention may contain any amount of monomer, but preferably 300 parts by weight or less per 100 parts by weight of copolymer. The composition may be substantially free of monomer. If a monomer is contained, the amount is preferably 1 part by weight or more, more preferably 5 parts by weight or more. In particular, when the monomer content is 30 parts by weight or less, the uncured composition is less likely to become viscous, facilitating molding and processing as a thermoplastic resin. Furthermore, when the content of volatile monomers is below a certain level, odor in the uncured state is not a problem. When a solvent is added to the composition to produce a varnish-like product, the monomer is lost as the solvent evaporates during use, resulting in a problem of a decrease in the effective content of the monomer. Furthermore, when the product is in the form of an uncured sheet, containing a certain amount of monomer or less reduces the change in the monomer content during storage. Monomers suitable for use in the composition of the present invention preferably have a molecular weight of less than 1,000, more preferably less than 500. Monomers that can be suitably used in the composition of the present invention are the aromatic vinyl compound monomers described above, the aromatic polyene monomers described above, the aromatic vinylene monomers described below, and / or the polar monomers described below. The monomers are preferably those that can be polymerized with a radical polymerization initiator, and more preferably one or more from the group consisting of aromatic vinyl compounds and aromatic polyenes. Also suitable for use is BVPE (1,2-bis(vinylphenyl)ethane) described in JP-A-2003-212941.

[0072] <Aromatic vinylene monomer> The aromatic vinylene monomer that may be included in the present invention refers to a compound having both a single aromatic ring or multiple condensed aromatic rings having 9 to 30 carbon atoms and a vinylene group. Examples of such aromatic vinylene compounds include indenes, beta-substituted styrenes, acenaphthylenes, etc. Examples of indenes include indene, various alkyl-substituted indenes, and phenyl-substituted indenes. Examples of beta-substituted styrenes include beta-alkyl-substituted styrenes such as beta-methylstyrene, and phenyl-substituted styrenes. Examples of acenaphthylenes include acenaphthylene, various alkyl-substituted acenaphthylenes, and various phenyl-substituted acenaphthylenes. As the aromatic vinylene compound, the above-exemplified compounds may be used alone or in combination of two or more. From the viewpoints of industrial availability and radical polymerizability, acenaphthylene is the most preferred aromatic vinylene compound.

[0073] <Polar monomer> A relatively small amount of polar monomer can be used to impart adhesion to other materials required as an insulating material. Examples of such polar monomers include 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 present invention are described, for example, in International Publication No. 2016 / 114287 and are available commercially, for example, from Daiwa Kasei Co., Ltd. These maleimide group-containing compounds may be used as polyaminobismaleimide compounds from the viewpoints of solubility in organic solvents, high-frequency characteristics, high adhesion to conductors, and prepreg moldability. 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 its molecule. When attempting to obtain high crosslinking efficiency with the addition of a small amount, it is preferable to use a polar monomer having a multifunctional group (bifunctional or higher), such as bismaleimides, triallyl isocyanurate (TAIC), or trimethylolpropane tri(meth)acrylate. The amount of polar monomer that may be contained in the composition may be in the range of 0.1 to 30 parts by mass, preferably 0.1 to 10 parts by mass, per 100 parts by mass of the copolymer. Using 30 parts by mass or less reduces the dielectric constant and dielectric dissipation factor of the resulting cured product. For example, in a preferred embodiment, the dielectric constant of the cured product of the copolymer is 3.5 or less, and the dielectric dissipation factor is 1.2 x 10 -3 It is possible to reduce it to the following:

[0074] <Solvent> An appropriate solvent may be added to the composition of the present invention as needed. The solvent is used to adjust the viscosity and fluidity of the composition. Volatile solvents are preferred, such as cyclohexane, toluene, ethylbenzene, acetone, and isopropanol. The solvent is used to adjust the viscosity and fluidity of the composition as a varnish. 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 is 100°C or higher, more preferably 130°C to 300°C, at atmospheric pressure. Solvents suitable for such varnishes include cyclohexane, toluene, xylene, mesitylene, tetralin, acetone, ethylbenzene, limonene, mixed alkanes, mixed aromatic solvents, ethylene glycol methyl ether acetate, ethylene glycol monoethyl ether acetate, and ethylene glycol monobutyl ether. In the case of a solvent, the amount used is preferably in the range of 10 to 2000 parts by mass, more preferably 5 to 500 parts by mass, and even more preferably 10 to 300 parts by mass, per 100 parts by mass of the composition of the present invention. The solvent is preferably removed by a drying treatment or the like before curing the composition.

[0075] <Filler> Inorganic or organic fillers may be added as needed. These fillers are added for purposes such as controlling the coefficient of thermal expansion, controlling thermal conductivity, and reducing cost, and the amount added can be arbitrary depending on the purpose. The composition of the present invention can contain a particularly large amount of inorganic filler, with the maximum amount being 2,000 parts by mass per 100 parts by mass of copolymer. When adding an inorganic filler, it is preferable to use a known surface modifier, such as a silane coupling agent. In particular, when aiming for a composition with low dielectric constant and low dielectric loss, one of the objectives of the present invention, boron nitride (BN) is preferred as the inorganic filler. From the perspective of low dielectric properties, adding a large amount of filler increases the dielectric constant, so preferably less than 500 parts by mass, more preferably less than 400 parts by mass, of filler per 100 parts by mass of copolymer is used. Furthermore, hollow fillers or fillers with a large number of voids may be added to improve and enhance low dielectric properties (low dielectric constant, low dielectric loss tangent).

[0076] Alternatively, organic fillers such as high-molecular-weight polyethylene, ultra-high-molecular-weight polyethylene, polystyrene, styrene-divinylbenzene copolymer, or fluorine-based resins can be used instead of inorganic fillers. Fluorine-based resins include known fluorine-containing resins such as PTFE (polytetrafluoroethylene) and PFA (perfluoroalkoxyalkane). An example of such a resin is Fluon+ (registered trademark) EA-2000 from AGC. When the melting point or glass transition temperature of the organic filler is lower than the solder reflow temperature of 290°C, it is preferable for the organic filler itself to be crosslinked from the standpoint of heat resistance, and it is preferable for it to be incorporated in the form of fine particles or powder. These organic fillers can also suppress increases in dielectric constant and dielectric loss tangent.

[0077] On the other hand, by mixing and dispersing a high-dielectric-constant insulating filler having a dielectric constant at 1 GHz of preferably 3 to 10,000, more preferably 5 to 10,000, into the composition of the present invention, it is possible to produce a cured insulating product having a high-dielectric-constant insulating layer with a dielectric constant of preferably 2.5 to 20, more preferably 2.8 to 10, while suppressing an increase in the 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. Examples of high-dielectric-constant insulating fillers used in the present invention 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. Other examples are specifically described in, for example, JP 2004-087639 A.

[0078] <Other additives> The composition may further contain one or more selected from a flame retardant and a surface modifier. The composition of the present invention can serve as a matrix for a cured body, and when cured, it has excellent filling properties for other materials. Therefore, the cured body containing one or more selected from these fillers, flame retardants, and surface modifiers tends to exhibit impact resistance and toughness even after curing.

[0079] <Flame retardant> Known flame retardants can be used in the composition of the present invention. From the viewpoint of maintaining a low dielectric constant and a low dielectric loss tangent, preferred flame retardants are known organophosphorus-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 particularly preferred from the viewpoint of flame retardancy and a low dielectric loss tangent.

[0080] In addition to the flame retardant, antimony compounds such as antimony trioxide, antimony tetroxide, antimony pentoxide, and sodium antimonate, or nitrogen-containing compounds such as melamine, triallyl-1,3,5-triazine-2,3,4-(1H,3H,5H)-trione, and 2,4,6-triaryloxy-1,3,5-triazine may be added as a flame retardant aid. The total amount of these flame retardants and flame retardant aids is usually preferably 1 to 100 parts by mass per 100 parts by mass of the composition. Alternatively, 30 to 200 parts by mass of a polyphenylene ether (PPE) resin with a low dielectric constant and excellent flame retardancy may be used per 100 parts by mass of the flame retardant.

[0081] <Surface modifier> The composition of the present invention may contain various surface modifiers for the purpose of improving adhesion to fillers, copper plates, and wiring. The amount of the surface modifier used per 100 parts by mass of the composition of the present invention other than the surface modifier is preferably 0.01 to 10 parts by mass, more preferably 0.1 to 5 parts by mass. Examples of the surface modifier include various silane coupling agents and titanate coupling agents. Various silane coupling agents and titanate coupling agents may be used singly or in combination.

[0082] In the present invention, the flow temperature of the curable resin or composition can be adjusted to suit the purpose and molding method by changing the compounding ratio of the "resin component," "curing agent," "monomer," "solvent," "filler," or "other additives." Specifically, the composition of the present invention can take the form of a product such as a "thermoplastic composition," a "semi-cured state (such as a B-stage sheet)," or a "varnish."

[0083] The composition of the present invention can be obtained by mixing, dissolving, or melting one or more of the following: "resin components," "curing agents," "monomers," "solvents," "fillers," and "other additives." Furthermore, general additives that are typically added to resins, such as lubricants, stabilizers, antioxidants, weather resistance agents, and ultraviolet absorbers, can also be used to the extent that the object of the present invention is not impaired. Any known method can be used for mixing, dissolving, or melting these components.

[0084] <Thermoplastic composition and molded article thereof> The composition of the present invention uses a copolymer having a molecular weight above a certain level, generally a weight-average molecular weight of about 50,000 or more, and when it contains the specified resin components, it can exhibit the properties of a thermoplastic resin. Therefore, it can be molded into shapes such as sheets, tubes, strips, and pellets in a substantially uncured state using known molding methods for thermoplastic resins under conditions that do not cause crosslinking. The molded product may be crosslinked (cured) after or during molding.

[0085] A preferred embodiment of the present composition is as follows. When the resin component contains a certain proportion or more of one or more resins selected from the hydrocarbon elastomer, polyether resin, olefin-aromatic vinyl compound-aromatic polyene copolymer not containing a cyclic olefin, or aromatic polyene resin, excluding resins that are liquid at room temperature, the composition is also easily molded into a thermoplastic resin in an uncured state. The thermoplastic properties of the above thermoplastic compositions can be utilized by molding them into various shapes, such as sheets, at or below the action temperature of the curing agent, and then laminating and combining them with semiconductor elements, wiring, or substrates as needed, followed by heat curing and bonding.

[0086] The composition of the present invention may be provided as a sheet obtained by molding the composition, heated and melted at a temperature below or equal to the curing agent's working temperature or decomposition temperature, using a known method. Forming into a sheet may be achieved by T-die extrusion, two-roll extrusion, or extrusion lamination onto a substrate film. In this case, the composition's composition, copolymer / monomer mass ratio, or solvent, resin components, and flame retardant are selected and adjusted so that the composition melts below or equal to the curing agent's working temperature or decomposition temperature and becomes solid at or near room temperature. In this case, the sheet is substantially uncured. After various processing and assembly steps, the sheet is finally treated at a temperature and time above the curing agent's working temperature or decomposition temperature to achieve complete curing. This method is a common technique used for ethylene-vinyl acetate resin-based crosslinked sealant sheets for solar cells (photovoltaic power generation devices).

[0087] <Molded body in semi-cured state (B-stage sheet, etc.)> The composition of the present invention can also be formed into a molded article, such as a sheet or tube, in a partially crosslinked state, for example, a state in which a portion of the curing agent contained therein has reacted and semi-cured (so-called B-stage state). Here, the semi-cured state is defined as a state in which the gel content of the resin component in the composition of the present invention is greater than 20% by mass and not more than 80% by mass, independently of the definition of the uncured state. The gel content is a value obtained by measurement in accordance with JIS K6796:1998. For example, by employing multiple curing agents and / or curing conditions with different curing temperatures, the composition can be semi-cured and the melt viscosity and fluidity can be controlled to achieve a B-stage state. That is, the curable resin or composition can be molded into an easily handleable B-stage sheet by a first curing step (partial curing), which can then be laminated and pressure-bonded to an electronic device or substrate, followed by a second curing step (complete curing) to form the final shape. In this case, the composition, i.e., the copolymer / monomer mass ratio, is selected, and if necessary, a solvent, resin component, and flame retardant are added. The composition, which further contains a curing agent such as a peroxide, is partially cured and adjusted to a sheet shape (B-stage state). After molding and assembling the device, the composition can be fully cured by heating under pressure. Known methods can be used to partially cure the composition. For example, peroxides with different decomposition temperatures are used in combination, and the composition is treated for a predetermined time at a temperature at which only one of the peroxides is substantially active to obtain a semi-cured sheet. Finally, the sheet is fully cured by treating the sheet for a sufficient time at a temperature at which all of the curing agents are active.

[0088] Furthermore, the molded article may be a sheet. The sheet may be uncured (semi-cured) to the extent that it can maintain its sheet shape, or may be fully cured. The degree of curing of the composition can be quantitatively measured by known dynamic mechanical analysis (DMA).

[0089] <Varnish-like composition and molded article thereof> The composition of the present invention can also be made into a viscous liquid varnish by adjusting its composition and blending ratio. For example, a varnish can be obtained by using a sufficient amount of solvent and / or an appropriate amount of liquid monomer. When used as a varnish, it is preferable to add an appropriate solvent to the composition of the present invention. The solvent is used to adjust the viscosity and fluidity of the composition as a varnish. A solvent with a high boiling point at atmospheric pressure, i.e., low volatility, contributes to a uniform thickness of the applied film; therefore, a solvent with a boiling point above a certain level is preferred. A preferred boiling point is approximately 110°C to 300°C at atmospheric pressure. Examples of solvents suitable for such varnishes include toluene, xylene, mesitylene, ethylbenzene, limonene, ethylene glycol methyl ether acetate, ethylene glycol monoethyl ether acetate, and ethylene glycol monobutyl ether. The amount of the solvent used is preferably in the range of 10 to 2,000 parts by mass per 100 parts by mass of the composition of the present invention.

[0090] The varnish can be applied to or impregnated into a substrate, and the solvent or the like can be removed by drying or the like to produce an uncured or semi-cured molded article. This molded article generally has the form of a sheet, film, or tape. In this embodiment, the obtained uncured or semi-cured molded article is cured.

[0091] <Curing> The composition can be cured by a known method, taking into consideration the curing conditions (temperature, time, pressure) of the curing agent contained therein. 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.

[0092] <Cured product of the composition> The dielectric constant and dielectric loss tangent of the cured product obtained from the composition of the present invention are measured by a known resonator method. In this specification, the resonator method is performed at a measurement frequency of 40 GHz. The dielectric constant of the cured product may be 3.5 or less, preferably 3.5 to 2.0, and particularly preferably 3.0 to 2.0. The dielectric loss tangent of the cured product may be 0.0015 or less, 0.0002 to 0.0015, and preferably 0.0005 to 0.0010. The volume resistivity of the cured product is preferably 1×10 15 Ω·cm or more. These values ​​are preferred for high-frequency electrical insulating materials, for example, at frequencies of 3 GHz or higher. Because the copolymer used in the composition of the present invention is relatively soft and has excellent tensile elongation, cured products obtained from compositions using the copolymer exhibit sufficient mechanical properties while also having relatively high impact resistance and the ability to adapt to the thermal expansion of the substrate. That is, the storage modulus of the cured product of the present invention, measured at room temperature (25°C), is preferably 30 GPa or less but 0.1 GPa or more, more preferably less than 30 GPa but 0.1 GPa or more, and even more preferably 1 GPa or more but 20 GPa or less. Furthermore, the storage modulus measured at a high temperature (280°C) is preferably 1 MPa or more but 1 GPa or less, more preferably 5 MPa or more but 1 GPa or less, and even more preferably 10 MPa or more but 1 GPa or less. Those skilled in the art can determine the formulation of a composition having the above physical property parameters and prepare a cured product by referring to the information described in this specification and publicly known documents. The cured product obtained from the composition of the present invention can exhibit heat resistance and mechanical properties at high temperatures sufficient for practical use, even under conditions in which the monomer in the composition and the aromatic polyene as a component of the monomer are kept below a certain percentage.

[0093] <General uses of the composition> The composition of the present invention can be used as a substrate or base material for single-layer or multi-layer printed circuit boards, flexible printed circuit boards, so-called single-layer or multi-layer CCL (copper clad laminate) boards, and single-layer or multi-layer FCCL (flexible copper clad laminate) boards. It can also be used as various electrical insulating materials for wiring, preferably high-frequency signal wiring, such as coverlays, high-frequency transmission circuits, antennas, solder resists, build-up materials, interlayer insulating materials, bonding sheets, interlayer adhesives, and bump sheets for flip-chip bonders.

[0094] In another aspect, the present invention provides a composition comprising an olefin-aromatic vinyl compound-aromatic polyene copolymer (which may be an α-olefin-cyclic olefin-aromatic vinyl compound-aromatic polyene copolymer), the composition having, as a cured product, a storage modulus of 10 MPa to 10 GPa at 250°C, a dielectric constant of 2.0 to 3.5, and a dielectric loss tangent of 0.0015 or less, preferably 1.2 × 10 -3 There can be provided an electrically insulating material that is:

[0095] In one embodiment of the present invention, there is also provided a method for producing the copolymer. The production method includes copolymerizing each of the monomers of an α-olefin, a cyclic olefin, and an aromatic polyene by coordination polymerization. In another embodiment, there is also provided a method for producing a cured product, which includes polymerizing the copolymer using a radical polymerization initiator that does not contain oxygen or nitrogen atoms in its structure and is composed only of carbon and hydrogen atoms.

[0096] Coordination polymerization is a polymerization method using a coordination polymerization catalyst consisting of a transition metal compound and a co-catalyst. Transition metal compounds containing zirconium, hafnium, titanium, iron, nickel, cobalt, and palladium are preferred as transition metal compounds. In particular, for copolymerizing cyclic olefin monomers, transition metal compounds containing zirconium, titanium, nickel, iron, and palladium are preferred. The most preferred coordination polymerization catalyst is a coordination polymerization catalyst consisting of a transition metal compound represented by the following general formula (1) and a co-catalyst. More preferably, the production method may include a step of copolymerizing each of the monomers of an α-olefin, a cyclic olefin, an aromatic vinyl compound (if included), and an aromatic polyene using a polymerization catalyst consisting of a transition metal compound represented by the following general formula (1) and a co-catalyst:

[0097] General formula (1) [ka] In the above formula, A and B are each independently a group selected from an unsubstituted or substituted cyclopentaphenanthryl group, an unsubstituted or substituted benzoindenyl group, an unsubstituted or substituted cyclopentadienyl group, and an unsubstituted or substituted indenyl group. Y is a methylene group, silylene group, ethylene group, germylene group, or boron residue having a bond to A and B and having hydrogen or a hydrocarbon group having 1 to 15 carbon atoms (which may contain 1 to 3 nitrogen, oxygen, sulfur, phosphorus, or silicon atoms) as a substituent. The substituents may be different or the same. Y may also have a cyclic structure. Most preferably, Y is a methylene group having a bond to A and B and having hydrogen or a hydrocarbon group having 1 to 15 carbon atoms (which may contain 1 to 3 nitrogen, oxygen, sulfur, phosphorus, or silicon atoms) as a substituent. X is hydrogen, halogen, 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, or a dialkylamide group having an alkyl substituent having 1 to 6 carbon atoms. M is a transition metal, and may preferably be zirconium, hafnium, or titanium.

[0098] To obtain a copolymer with a relatively low molecular weight and low viscosity when made into a varnish, A and B in the above general formula (1) are preferably each independently selected from an unsubstituted or substituted cyclopentadienyl group or an unsubstituted or substituted indenyl group. It is particularly preferable to use a transition metal compound having both an unsubstituted or substituted cyclopentadienyl group and an unsubstituted or substituted indenyl group. To obtain a copolymer with a high aromatic polyene content, i.e., a copolymer with a high number of vinyl and / or vinylene groups derived from aromatic polyene monomer units per number-average molecular weight, it is preferable to use a transition metal compound having at least one group selected from an unsubstituted or substituted indenyl group or an unsubstituted or substituted benzoindenyl group. Copolymers with a high aromatic polyene content can increase the crosslink density of the cured product, resulting in a cured product with a storage modulus of 5 MPa or more measured at 280°C.

[0099] The cocatalyst in the polymerization catalyst of the present invention may be a known cocatalyst used in combination with a transition metal compound. Preferred examples of such cocatalysts include aluminum compounds and boron compounds. Alumoxanes such as methylaluminoxane (also referred to as methylalumoxane or MAO) are suitable aluminum compounds. Aluminum alkyls such as triisobutylaluminum and triethylaluminum 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, EP 0985689A1, and JP 6-184179 A.

[0100] Examples of boron compounds include trispentafluorophenylborane, triphenylcarbenium tetrakis(pentafluorophenyl)borate {trityltetrakis(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-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 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. Among these, the most preferred boron promoters are those containing boron and a fluorine-substituted aromatic group bonded thereto. Examples include 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. While a phenyl group is used as an example of the fluorine-substituted aromatic group, fused aromatic groups such as a fluorine-substituted naphthyl group can also be used.

[0101] The co-catalyst is used in an aluminum atom / transition metal atom ratio relative to the metal of the transition metal compound of 0.1 to 100,000, preferably 10 to 10,000. A ratio of 0.1 or more can effectively activate the transition metal compound, while a ratio of 100,000 or less is economically advantageous. The transition metal compound and co-catalyst may be mixed and prepared outside of polymerization equipment, or may be mixed inside the equipment during polymerization.

[0102] In particular, the aluminum atom / transition metal atomic ratio of the co-catalyst, such as alumoxane, relative to the metal in the transition metal compound is preferably 0.1 to 100,000, more preferably 10 to 10,000. A ratio of 0.1 or more can effectively activate the transition metal compound, while a ratio of 100,000 or less is economically advantageous. When a boron compound is used as the co-catalyst, the boron atom / transition metal atomic ratio is preferably 0.1 to 100, more preferably 0.1 to 10, and most preferably in the range of 0.8 to 1.2. A ratio of 0.1 or more can effectively activate the transition metal compound, while a ratio of 100 or less is economically advantageous.

[0103] In a preferred embodiment, a boron compound is essential, and an aluminum compound may be used as a co-catalyst if necessary. The use of a boron compound as a co-catalyst reduces the amount of metal components, such as aluminum derived from the aluminum compound, contained in the final copolymer, and the dielectric constant and dielectric loss tangent of the final uncured copolymer, or the dielectric constant and dielectric loss tangent of the single cured product or composition, can be reduced to particularly preferred ranges. For example, the dielectric constant of the uncured copolymer can be less than 2.3 and the dielectric loss tangent can be less than 0.0004. Furthermore, when a boron compound is used as a co-catalyst, the dielectric constant of the final cured product of the copolymer can be less than 2.3 and the dielectric loss tangent can be less than 0.0004.

[0104] In one embodiment, an uncured α-olefin-cycloolefin-aromatic polyene copolymer or α-olefin-cycloolefin-aromatic vinyl compound-aromatic polyene copolymer can be provided, having a total metal content derived from the catalyst and co-catalyst of 1000 ppm or less, preferably 750 ppm or less, and most preferably 500 ppm or less. Here, the metal content derived from the catalyst and co-catalyst is defined as the sum of the respective contents of the transition metal elements (as described above) used in the catalyst and the boron and / or aluminum compounds used in the co-catalyst, and can be defined as the sum of the respective contents of zirconium, hafnium, titanium, iron, nickel, palladium, cobalt, boron, and aluminum. Particularly preferably, the metal derived from the catalyst may be zirconium, and the metal derived from the co-catalyst may be aluminum and boron. The metal content derived from the catalyst and co-catalyst may be the sum of the respective contents of zirconium, aluminum, and boron. Note that boron is included in the category of metals in this specification. An uncured α-olefin-cycloolefin-aromatic polyene copolymer or α-olefin-cycloolefin-aromatic vinyl compound-aromatic polyene copolymer having a total metal content of 1000 ppm or less, preferably 750 ppm or less, and most preferably 500 ppm or less, can exhibit one or more of the following properties: a dielectric constant of less than 2.3 at a measurement frequency of 40 GHz, a dielectric dissipation factor of less than 0.0004 at a measurement frequency of 40 GHz, and a storage modulus of 1000 MPa or more measured at 25° C. More preferably, the uncured copolymer may have a dielectric constant of less than 2.3 and a dielectric dissipation factor of less than 0.0004 at a measurement frequency of 40 GHz, and a storage modulus of 1000 MPa or more measured at 25° C. [Example]

[0105] The present invention will be described below with reference to examples, but the present invention should not be construed as being limited to the following examples.

[0106] The copolymers obtained in the synthesis examples were analyzed by the following methods. The content of vinyl group units derived from ethylene, cyclic olefin, and divinylbenzene in the copolymer is determined by: 1 H-NMR measurement and quantitative mode 13 C-NMR measurement was performed, and the measurement was performed by a known method based on the area intensity of the obtained peak. The sample was dissolved in heavy 1,1,2,2-tetrachloroethane, and the measurement was performed at 80 to 130°C.

[0107] 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.

[0108] Column: Two 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

[0109] <Viscosity> The viscosity of the copolymer obtained in each example was determined as follows. A 25% by mass toluene solution of each copolymer was prepared and 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.

[0110] <Gel content> The gel content was determined as the boiling toluene insoluble matter according to ASTM D2765-84.

[0111] <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.

[0112] <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 from the sheet. Measurements were taken for both the uncured and cured state.

[0113] <Measurement of storage modulus> Using a dynamic viscoelasticity measuring device (TA Instruments, formerly Rheometrics RSA-G2), measurements were taken at a frequency of 1 Hz while the temperature was raised from room temperature (23°C), and the storage modulus was measured at 25°C and 280°C. Measurement samples (3mm x 40mm) were cut out from a film approximately 0.1mm thick, and the storage modulus was measured in both the uncured and cured states. The glass transition temperature was also determined from the temperature at the peak of the loss tangent (tanδ) in the uncured state. 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%

[0114] <Quantitative determination of metal content in copolymers> The metal content (in the example below, the content of transition metal elements used in the metal catalyst, and the content of boron and aluminum used in the promoter) was 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 spectrometry 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, and after heating and dissolution, the mixture was adjusted to a constant volume of 5 ml to form a test solution, which was then quantitatively analyzed by ICP emission spectrometry (using an Agilent 5110VDV).

[0115] <Example 1: Preparation of Copolymer P-1>

[0116] The raw material divinylbenzene (DVB) was "Divinylbenzene (96%)" manufactured by Nippon Steel Chemical & Material Co., Ltd. (liquid at room temperature, a mixture of meta and para isomers containing 96% by mass of divinylbenzene, with the remainder being ethylvinylbenzene). The raw material was norbornene (75%, toluene solution) manufactured by Maruzen Petrochemical Co., Ltd., which was first mixed with a small amount of triisobutylaluminum (TIBA) and stirred at room temperature. The mixture was then purified by distillation under nitrogen. A 10-L polymerization vessel equipped with a heating and cooling jacket and a stirrer was used. The interior of the polymerization vessel was first thoroughly dried and purged with nitrogen. 3 kg of toluene, 1 kg of pure norbornene, and 180 g of pure divinylbenzene were then charged, and approximately 20 L of dry nitrogen was bubbled in at an internal temperature of 50°C. The inside of the polymerization vessel was then purged with ethylene gas, and 5 mmol of TIBA (manufactured by Kanto Chemical Co., Ltd.) was added and stirred, followed by 50 mmol of MMAO (modified MAO) (manufactured by Tosoh Finechem Co., Ltd.) in terms of aluminum. The internal temperature was stabilized at 60°C, and the internal pressure of the polymerization vessel was increased to 0.4 MPaG (gauge) by supplying ethylene and stabilized. Then, 100 μmol of rac-diphenylmethylene(1-indenyl)(cyclopentadienyl)zirconium dichloride (structure: see formula (2) below) as a catalyst and 100 g of a toluene solution containing 2 mmol of TIBA were added to the polymerization vessel from a catalyst tank installed above the polymerization vessel to initiate polymerization. The ethylene consumed during the polymerization was gradually replenished, and the polymerization was continued while maintaining the internal temperature at 60°C and the internal pressure at 0.4 MPaG. After about two hours of polymerization, when the ethylene consumption reached 200 g, the ethylene gas in the polymerization vessel was discharged and the pressure returned to normal, and 50 g of isopropanol (a polymerization terminator) was added to the polymerization vessel to terminate the polymerization. The resulting polymerization liquid was poured in small amounts into a sufficiently large amount of methanol / acetone mixed solution, and the precipitated polymer was recovered by stirring and filtering. The polymer was then thoroughly dried in a vacuum at room temperature to obtain ethylene-norbornene-divinylbenzene copolymer P-1.

[0117] Formula (2) [ka]

[0118] <Example 2: Preparation of Copolymer P-2> Polymerization was carried out in the same manner as in the synthesis of P-1, except that the amount of norbornene used was changed to 1.4 kg in terms of pure content, and the polymerization was terminated when the amount of ethylene consumed reached 100 g, thereby obtaining an ethylene-norbornene-divinylbenzene copolymer, P-2.

[0119] <Example 3: Preparation of Copolymer P-3> Polymerization was carried out in the same manner as in the synthesis of P-1, except that the amounts of raw materials used were changed to 2 kg of toluene, 2 kg of pure norbornene, 300 g of pure divinylbenzene, and 100 mmol of MMAO (modified MAO) manufactured by Tosoh Finechem Co., Ltd., in terms of aluminum. Furthermore, the catalyst used was changed to 100 g of a toluene solution containing 200 μmol of dimethylmethylenebis(cyclopentadienyl)zirconium dichloride (see formula (3) below for its structure) and 4 mmol of TIBA. The polymerization was terminated when the amount of ethylene consumed reached 150 g, yielding an ethylene-norbornene-divinylbenzene copolymer, P-3.

[0120] Formula (3) [ka]

[0121] <Example 4: Preparation of copolymer P-4> As in the synthesis of P-3, dimethylmethylenebis(cyclopentadienyl)zirconium dichloride was used as the catalyst, except that MMAO was not used as the cocatalyst; instead, tritium tetrakis(pentafluorophenyl)borate (manufactured by Tosoh Finechem Co., Ltd.) was used. Specifically, a catalyst solution prepared by stirring and dissolving 125 micromoles of tritium tetrakis(pentafluorophenyl)borate in 200 mL of a toluene solution containing 110 micromoles of dimethylmethylenebis(cyclopentadienyl)zirconium dichloride and 2 millimoles of triisobutylaluminum was added, and polymerization was carried out at an internal polymerization temperature of 90 °C. The polymerization was terminated when the ethylene consumption reached 150 g, yielding the ethylene-norbornene-divinylbenzene copolymer P-4.

[0122] Since P-1 to P-4 obtained in each example contained small amounts of residual monomer and solvent, they were redissolved in toluene. The solution was gradually added to a sufficiently large amount of a methanol / acetone mixed solution. The precipitated polymer was stirred, filtered, and dried under vacuum at room temperature for 24 hours to obtain purified polymers. The composition and molecular weight of the resulting P-1 to P-4 are shown in Table 1. The purified polymer was redissolved in toluene to obtain a 50% by mass toluene solution (varnish). The varnish was applied to a smooth Teflon (registered trademark) plate with an applicator, air-dried at 25°C for more than 3 hours, further dried under vacuum at 120°C for 12 hours, and then dried under vacuum at 200°C for 60 minutes to obtain a transparent sheet with a thickness of 0.1 mm. The sheet was cut into pieces and the gel content was measured. The gel content measurement results confirmed that the sheet was in an uncured state. Viscoelasticity spectroscopy (DMA) was performed using this sheet to measure the storage modulus and glass transition temperature at 25°C. The dielectric properties of this sheet were also measured. The results are shown in Table 1. It is clear that the copolymers of the present invention exhibit a high glass transition temperature in the uncured state, a high storage modulus (25°C), and low dielectric constant and dielectric loss tangent. In particular, P-4 obtained using a boron compound as a promoter exhibits a low dielectric constant and a significantly low dielectric loss tangent.

[0123] [Table 1a] [Table 1b]

[0124] <Example 5: Preparation of hardened sheet> Using a vessel equipped with a heating and cooling jacket and agitator, 100 parts by weight of P-1 (ethylene-norbornene-divinylbenzene copolymer) was heated to approximately 50°C and stirred in 100 parts by weight of toluene to dissolve the copolymer, creating a 50% by weight toluene solution (varnish). Furthermore, 1 part by weight of a curing agent (Perbutyl P) was added (based on the weight of the copolymer), dissolved, and mixed with stirring to obtain a varnish-like composition (Table 2). The resulting composition was poured into a Teflon® mold (frame length 7 cm, width 7 cm, thickness 0.2 mm, 0.5 mm, or 1.0 mm) on a PET sheet placed on a glass plate, thoroughly air-dried at 25°C, and then further dried in a vacuum dryer at 60°C for at least 3 hours to obtain an uncured sheet. The Teflon sheet and Teflon mold were then placed in a press under a load of 5 MPa, and the mixture was heated at 120°C for 30 minutes, 150°C for 30 minutes, and then 200°C for 120 minutes. The Teflon sheet and mold were then removed to obtain a cured sheet. The gel fraction, storage modulus (25°C and 280°C), dielectric constant, dielectric dissipation factor (both measured at 23°C and 40 GHz), and water absorption of the resulting cured sheet were measured.

[0125] Example 6: Preparation of hardened sheet A cured sheet was obtained in the same manner as in Example 5, and the physical properties were determined in the same manner.

[0126] <Examples 7-8: Preparation of cured sheets> Compared with P-1 and P-2, P-3 and P-4, which have glass transition temperatures above 150°C, are more difficult to remove residual toluene from the polymer. A cured sheet was obtained as follows, and physical properties were determined in the same manner. Using a container similar to those used in Examples 5 and 6, 100 parts by weight of P-3 or P-4 (ethylene-norbornene-divinylbenzene copolymer) was heated to approximately 50°C and stirred in 100 parts by weight of toluene solvent to dissolve the copolymer, creating a 50% by weight toluene solution (varnish). Furthermore, 1 part by weight of a curing agent (2,3-dimethyl-2,3-diphenylbutane, manufactured by Kanto Chemical Co., Inc.) was added relative to the parts by weight of the copolymer, dissolved, and mixed with stirring to obtain a varnish-like composition (Table 2). The resulting composition was poured into a Teflon® mold (7 cm long, 7 cm wide, 0.1 mm thick) on a PET sheet placed on a glass plate. After thorough air drying at 25°C, the mixture was further dried in a vacuum oven at 100°C for 3 hours to obtain an uncured sheet substantially free of solvent. Multiple uncured sheets were stacked to the required thickness for each measurement. The Teflon sheet and Teflon mold were placed in a vacuum press under a load of 5 MPa, and the resulting mixture was heated at 250°C for 60 minutes. The Teflon sheet and Teflon mold were then removed to obtain a cured sheet. The gel fraction, storage modulus (25°C and 280°C), dielectric constant, dielectric dissipation factor (both measured at 23°C and 40 GHz), and water absorption of the resulting cured sheet were measured.

[0127] Table 2 shows the formulations (units in the table are parts by mass) and physical properties (gel content, storage modulus at 25°C and 280°C, dielectric constant, dielectric dissipation factor, and water absorption). Table 2 also shows the viscosity of a 25% by mass toluene solution (varnish) for each Example. The cured sheets obtained in Examples 5 to 8 exhibited a high gel content and were sufficiently cured. Their storage moduli at room temperature (25°C) provided sufficient hardness for substrates, particularly rigid substrates. Furthermore, they exhibited the low dielectric constant and low dielectric dissipation factor required for high-frequency insulating materials. The cured sheets obtained in Examples 5 and 6 exhibited a high storage modulus at high temperatures (280°C) and possessed high mechanical properties at high temperatures. Furthermore, the viscosity of a 25% by mass toluene solution (varnish) containing the copolymer obtained in Examples 5 and 6 was 10,000 mPa·s or less. The cured sheet obtained in Example 8 exhibited a particularly low dielectric constant (2.1) and dielectric dissipation factor (0.0002).

[0128] [Table 2]

[0129] <Example 9: Preparation of copolymer P-5> Polymerization, polymer recovery, and post-treatment were carried out in the same manner as in the production method for P-4. However, 1.5 kg of pure norbornene, 2.5 kg of toluene, and 200 g of pure divinylbenzene were charged. A catalyst solution was added, prepared by adding 210 micromoles of tritylium tetrakis(pentafluorophenyl)borate to 300 mL of a toluene solution containing 200 micromoles of dimethylmethylenebis(cyclopentadienyl)zirconium dichloride and 5 millimoles of triisobutylaluminum, followed by stirring. The polymerization was carried out at an internal temperature of 60°C, while maintaining the internal pressure of the polymerization vessel at 0.15 MPaG (gauge) by supplying ethylene. During the polymerization, the same amount of catalyst solution as the catalyst solution described above was further added. The polymerization was terminated when ethylene consumption reached 100 g, yielding ethylene-norbornene-divinylbenzene copolymer P-5.

[0130] <Example 10: Preparation of copolymer P-6> Polymerization, polymer recovery, and post-treatment were carried out in the same manner as in the production method for P-5. However, 1.5 kg of DMON (1,4,5,8-dimethano-1,2,3,4,4a,5,8,8a-octahydronaphthalene, manufactured by Maruzen Petrochemical Co., Ltd., purity 98%) was used instead of norbornene. The polymerization was terminated when the ethylene consumption reached 100 g, yielding ethylene-MPNB-divinylbenzene copolymer P-6.

[0131] <Example 11: Preparation of copolymer P-7> Polymerization, polymer recovery, and post-treatment were carried out in the same manner as in the production method for P-5. However, 1.5 kg of MPNB (methylphenylnorbornene, manufactured by Maruzen Petrochemical Co., Ltd., purity 98%) was used instead of norbornene. The polymerization was terminated when the ethylene consumption reached 100 g, yielding an ethylene-MPNB-divinylbenzene copolymer, P-7.

[0132] <Example 12: Preparation of copolymer P-8> The raw material divinylbenzene (DVB) was "Divinylbenzene (81%)" manufactured by Nippon Steel Chemical & Material Co., Ltd. (liquid at room temperature, a mixture of meta and para isomers containing 81% divinylbenzene by mass, with the remainder being ethylvinylbenzene). The raw material was norbornene (75%, toluene solution) manufactured by Maruzen Petrochemical Co., Ltd., which was first mixed with a small amount of triisobutylaluminum (TIBA) and stirred at room temperature. The mixture was then purified by distillation under nitrogen. A 10 L polymerization vessel equipped with a heating and cooling jacket and a stirrer was used. The interior of the vessel was thoroughly dried and purged with nitrogen. 2 kg of toluene, 1 kg of pure norbornene, and 2 kg of divinylbenzene (81% divinylbenzene) were then charged. Approximately 20 L of dry nitrogen was bubbled through the vessel at an internal temperature of 50 °C. The interior of the polymerization vessel was then purged with nitrogen gas, and 6 mmol of TIBA (manufactured by Kanto Chemical 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 0.1 MPaG (gauge) using nitrogen. After stabilizing, 210 μmol of tritylium tetrakis(pentafluorophenyl)borate was dissolved in 100 g of a toluene solution containing 200 μmol of dimethylmethylenebis(cyclopentadienyl)zirconium dichloride and 2 mmol of TIBA, and the catalyst solution was added to the polymerization vessel from a catalyst tank installed above the polymerization vessel to initiate polymerization. The polymerization was continued while maintaining the internal temperature at 60°C and the internal pressure at 0.1 MPaG. After 4 hours of polymerization, 50 g of isopropanol (a polymerization terminator) was added to the polymerization vessel to terminate the polymerization. The resulting polymerization solution was gradually added to a large amount of methanol / acetone mixed solution, and the precipitated polymer was recovered by stirring and filtration. It was then thoroughly vacuum dried at room temperature to obtain norbornene-ethylvinylbenzene-divinylbenzene copolymer P-8.

[0133] <Example 13: Preparation of copolymer P-9> A polymerization vessel was charged with 2.2 kg of toluene, 1.5 kg of pure DMON, 300 g of styrene, and 200 g of pure divinylbenzene, and copolymerization of ethylene, DMON, styrene, and divinylbenzene was carried out in the same manner as in the production method for P-6. When the ethylene consumption reached 100 g, the polymerization was stopped, and post-treatment was carried out in the same manner to obtain an ethylene-MPNB-ethylvinylbenzene-divinylbenzene copolymer P-9.

[0134] Table 1 shows the composition, molecular weight, gel content, glass transition temperature, storage modulus at 25°C, dielectric properties, and metal content of the copolymers P-5 to P-9. It can be seen that copolymers P-5 to P-9 obtained using a boron compound as a co-catalyst exhibit high glass transition temperatures in the uncured state, high storage modulus (25°C), and remarkably low dielectric constants and dielectric loss tangents.

[0135] Copolymers obtained using DMON or MPNB as the cyclic olefin can exhibit high glass transition temperatures even with relatively low molar contents of DMON or MPNB. Specifically, the DMON content of P-6 is 52 mol%, and the MPNB content of P-7 is 46 mol%. These molar contents are lower than the norbornene content of P-5 (74 mol%), but the glass transition temperatures of P-6 and P-7 are 198°C and 186°C, respectively, which are nearly equivalent to the 190°C of P-5. A relatively low molar content of the cyclic olefin component facilitates the replacement of the remaining monomer components with aromatic vinyl compound units, resulting in copolymers with higher aromatic vinyl compound unit contents. This allows for the aromaticity of the copolymer to be increased while maintaining a high glass transition temperature, which is advantageous because it improves compatibility with other resins and raw materials. An example is shown in P-9. MPNB is particularly preferred because the cyclic olefin itself contains aromatic groups. Furthermore, copolymers obtained using DMON or MPNB as the cyclic olefin exhibit the characteristic of having a low molecular weight while having a similarly high glass transition temperature. Specifically, by using DMON or MPNB as the cyclic olefin, the most preferred number average molecular weight of 12,000 or less can be easily achieved. The ease of molecular weight reduction is desirable because it facilitates the production of a varnish with a lower viscosity.

[0136] Since P-5 to P-9 obtained in each example contained small amounts of residual monomer and solvent, they were redissolved in toluene. The solution was gradually added to a sufficiently large amount of a methanol / acetone mixed solution. The precipitated polymer was stirred, filtered, and dried under vacuum at room temperature for 24 hours to obtain purified polymers. The composition and molecular weight of the resulting P-5 to P-9 are shown in Table 1. The purified polymer was redissolved in toluene to obtain a 50% by mass toluene solution (varnish). The varnish was applied to a smooth Teflon (registered trademark) plate with an applicator, air-dried at 25°C for more than 3 hours, further dried under vacuum at 120°C for 12 hours, and then dried under vacuum at 200°C for 60 minutes to obtain a transparent sheet with a thickness of 0.1 mm. The sheet was cut into pieces and the gel content was measured. The gel content measurement results confirmed that the sheet was in an uncured state. Viscoelasticity spectroscopy (DMA) was performed using this sheet to measure the storage modulus and glass transition temperature at 25°C. The dielectric properties of this sheet were also measured. The results are shown in Table 1. It can be seen that the copolymers of the present invention exhibit a high glass transition temperature in the uncured state, a high storage modulus (25°C), and low dielectric constant and dielectric loss tangent. It can be seen that P-5 to P-9 obtained by using a boron compound as a promoter exhibit low dielectric constant and low dielectric loss tangent.

[0137] When the norbornene-ethylvinylbenzene-divinylbenzene copolymer P-8 was subjected to C-NMR measurement to examine the terminal structures contained therein, no terminal structures other than those E-1 to E-8 were detected. Furthermore, the terminal structures characteristic of cationic polymerization described in WO 2018 / 181842 (structures designated as t1 and t2 in WO 2018 / 181842) were not detected in P-8.

Claims

1. An α-olefin-cyclic olefin-aromatic polyene copolymer, wherein the copolymer in an uncured state has a dielectric constant of less than 2.4 and a dielectric dissipation factor of less than 0.0008 at a measurement frequency of 40 GHz, and a storage modulus measured at 25°C of 1000 MPa or more.

2. An α-olefin-cyclic olefin-aromatic vinyl compound-aromatic polyene copolymer, wherein the copolymer in an uncured state has a dielectric constant of less than 2.4 and a dielectric dissipation factor of less than 0.0008 at a measurement frequency of 40 GHz, and a storage modulus measured at 25°C of 1000 MPa or more.

3. 3. The copolymer according to claim 1, wherein the copolymer in an uncured state has a dielectric constant of less than 2.3 and a dielectric loss tangent of less than 0.0004 at a measurement frequency of 40 GHz.

4. The copolymer according to any one of claims 1 to 3, wherein the total content of metals derived from the catalyst and co-catalyst contained in the copolymer is 1000 ppm or less.

5. The copolymer according to any one of claims 1 to 4, which, when cured alone, exhibits a dielectric constant of less than 3.5 and a dielectric loss tangent of less than 0.001 at a measurement frequency of 40 GHz.

6. 6. The copolymer according to claim 5, which, when cured alone, has a dielectric constant of less than 2.3 and a dielectric loss tangent of less than 0.0004 at a measurement frequency of 40 GHz.

7. The copolymer according to any one of claims 1 to 6, which, when cured alone, has a storage modulus of 1 MPa or more as measured at 280°C of the cured product.

8. The copolymer according to any one of claims 1 to 7, which, when cured alone, has a storage modulus of 5 MPa or more as measured at 280°C of the cured product.

9. The copolymer according to claim 1, which satisfies all of the following (1) to (2) and (4) to (6): (1) The number average molecular weight of the copolymer is 500 or more and 100,000 or less. (2) The α-olefin unit is an α-olefin having 2 to 20 carbon atoms. (4) The cyclic olefin units are cyclic olefin monomer units having from 10 to 30 carbon atoms, and the content thereof is from 30% by mass to 99% by mass. (5) The aromatic polyene unit is one or more polyenes selected from polyenes having 5 to 20 carbon atoms and having a plurality of vinyl groups and / or vinylene groups in the molecule, and the content of vinyl groups and / or vinylene groups derived from the aromatic polyene monomer unit is 2 to 30 per number average molecular weight. (6) The total content of α-olefin units, cyclic olefin units, and aromatic polyene units is 100% by mass.

10. The copolymer according to claim 2, which satisfies all of the following (1) to (6): (1) The number average molecular weight of the copolymer is 500 or more and 100,000 or less. (2) The α-olefin unit is an α-olefin having 2 to 20 carbon atoms. (3) The aromatic vinyl compound unit is an aromatic vinyl compound having 8 to 20 carbon atoms. (4) The cyclic olefin units are cyclic olefin monomer units having from 10 to 30 carbon atoms, and the content thereof is from 30% by mass to 99% by mass. (5) The aromatic polyene unit is one or more polyenes selected from polyenes having 5 to 20 carbon atoms and having a plurality of vinyl groups and / or vinylene groups in the molecule, and the content of vinyl groups and / or vinylene groups derived from the aromatic polyene monomer unit is 2 to 30 per number average molecular weight. (6) The total content of α-olefin units, cyclic olefin units, aromatic vinyl compound units, and aromatic polyene units is 100% by mass.

11. The copolymer according to any one of claims 1 to 10, wherein the cyclic olefin unit comprises at least one selected from the group consisting of norbornene, methylphenylnorbornene, substituted norbornene other than methylphenylnorbornene, and dimethanooctahydronaphthalene.

12. The copolymer according to any one of claims 1 to 11, having a glass transition temperature in the range of 100°C or higher and 350°C or lower.

13. The copolymer according to any one of claims 1 to 12, having a number average molecular weight of 500 or more and less than 30,000.

14. The method for producing the copolymer according to any one of claims 1 to 13, wherein each monomer of an α-olefin, a cyclic olefin, an aromatic polyene, and, if necessary, an aromatic vinyl compound is copolymerized by coordination polymerization using a coordination polymerization catalyst.

15. The method for producing a copolymer according to claim 14, wherein the coordination polymerization catalyst is a polymerization catalyst comprising a transition metal compound represented by the following general formula (1) and a co-catalyst: General formula (1) 【Chemical 1】 In the formula, A and B are each independently a group selected from an unsubstituted or substituted cyclopentaphenanthryl group, an unsubstituted or substituted benzoindenyl group, an unsubstituted or substituted cyclopentadienyl group, and an unsubstituted or substituted indenyl group. Y is bonded to A and B and is a methylene group, silylene group, ethylene group, germylene group, or boron residue having hydrogen or a hydrocarbon group having 1 to 15 carbon atoms (which may contain 1 to 3 nitrogen, oxygen, sulfur, phosphorus, or silicon atoms) as a substituent. The substituents may be different or the same. Y may also have a cyclic structure. X is hydrogen, halogen, 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, or a dialkylamide group having an alkyl substituent having 1 to 6 carbon atoms. M is zirconium, hafnium, or titanium.

16. 16. The method for producing a copolymer according to claim 15, wherein A and B in general formula (1) are each independently a group selected from an unsubstituted or substituted cyclopentadienyl group and an unsubstituted or substituted indenyl group.

17. 17. The process according to claim 15 or 16, wherein a cocatalyst containing a boron compound is used.

18. The process of claim 17 wherein the co-catalyst further comprises an aluminum compound.

19. A cured product comprising the copolymer according to any one of claims 1 to 13.

20. An α-olefin-cyclic olefin-aromatic polyene copolymer that satisfies all of the following (1) to (2) and (4) to (6): (1) The number average molecular weight of the copolymer is 500 or more and 100,000 or less. (2) The α-olefin unit is an α-olefin having 2 to 20 carbon atoms. (4) The cyclic olefin units are cyclic olefin monomer units having from 10 to 30 carbon atoms, and the content thereof is from 30% by mass to 99% by mass. (5) The aromatic polyene unit is one or more polyenes selected from polyenes having 5 to 20 carbon atoms and having a plurality of vinyl groups and / or vinylene groups in the molecule, and the content of vinyl groups and / or vinylene groups derived from the aromatic polyene monomer unit is 2 to 30 per number average molecular weight. (6) The total content of α-olefin units, cyclic olefin units, and aromatic polyene units is 100% by mass. one or more additive components selected from the group consisting of a resin component, a curing agent, a monomer, a solvent, and a filler; A cured product of a composition comprising: The cured product exhibits a dielectric constant of 3.5 or less and a dielectric loss tangent of 0.0015 or less at a measurement frequency of 40 GHz.

21. an α-olefin-cyclic olefin-aromatic vinyl compound-aromatic polyene copolymer that satisfies all of the following (1) to (6); (1) The number average molecular weight of the copolymer is 500 or more and 100,000 or less. (2) The α-olefin unit is an α-olefin having 2 to 20 carbon atoms. (3) The aromatic vinyl compound unit is an aromatic vinyl compound having 8 to 20 carbon atoms. (4) The cyclic olefin units are cyclic olefin monomer units having from 10 to 30 carbon atoms, and the content thereof is from 30% by mass to 99% by mass. (5) The aromatic polyene unit is one or more polyenes selected from polyenes having 5 to 20 carbon atoms and having a plurality of vinyl groups and / or vinylene groups in the molecule, and the content of vinyl groups and / or vinylene groups derived from the aromatic polyene monomer unit is 2 to 30 per number average molecular weight. (6) The total content of α-olefin units, cyclic olefin units, aromatic vinyl compound units, and aromatic polyene units is 100% by mass. one or more additive components selected from the group consisting of a resin component, a curing agent, a monomer, a solvent, and a filler; A cured product of a composition comprising: The cured product exhibits a dielectric constant of 3.5 or less and a dielectric loss tangent of 0.0015 or less at a measurement frequency of 40 GHz.

22. The cured product according to any one of claims 19 to 21, further having a storage modulus measured at 25°C of 1000 MPa or more and a storage modulus measured at 280°C of 1 MPa or more.

23. The cured product according to any one of claims 19 to 22, which is an electrical insulating material.

24. A CCL substrate, an FCCL substrate, an interlayer insulating material, a coverlay, a high-frequency transmission circuit, or an antenna, comprising the cured product according to claim 23.

25. A method for producing a cured product, comprising a step of polymerizing at least the copolymer according to any one of claims 1 to 13 using a radical polymerization initiator composed only of carbon atoms and hydrogen atoms, and not containing oxygen atoms or nitrogen atoms in its structure.

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