Conjugated diene-based copolymer, conjugated diene-based copolymer composition, resin composition, cured product, resin film, prepreg, laminate, and material for electronic circuit board

Abstract

This conjugated diene-based copolymer satisfies conditions (1)-(4). Condition (1): A polymer block (A) that contains a vinyl aromatic monomeric unit (unit (a-1)) having a radical reactive group is included. Condition (2): A polymer block (B) mainly composed of a conjugated diene monomeric unit (unit (b)) is included. Condition (3): The number average molecular weight of the conjugated diene-based copolymer is more than 40,000 but not more than 150,000. Condition (4): The content of the total vinyl aromatic monomeric unit (a) containing the unit (a-1) in the conjugated diene-based copolymer is 5-70 mass%.

Description

Conjugated diene copolymer, conjugated diene copolymer composition, resin composition, cured product, resin film, prepreg, laminate, and material for electronic circuit board

[0001] The present invention relates to a conjugated diene copolymer, a conjugated diene copolymer composition, a resin composition, a cured product, a resin film, a prepreg, a laminate, and a material for electronic circuit boards.

[0002] In recent years, with the remarkable progress in information network technology and the expansion of services utilizing information networks, electronic devices are required to have larger information capacities and faster processing speeds. To meet these demands, materials with low dielectric loss are required for various substrate materials, such as printed circuit boards and flexible circuit boards. Furthermore, as various electronic devices become smaller, thinner, more multifunctional, and more powerful, the wiring boards used in these products are also required to have higher performance, such as finer wiring, more multilayer wiring, and thinner wiring. These wiring boards require precise wiring, which requires materials for printed circuit boards with high mechanical properties, such as heat resistance, impact resistance, toughness, and adhesion to metal wiring.

[0003] In order to obtain materials with low dielectric loss, resin cured products containing thermosetting resins, such as thermosetting hydrocarbon resins and thermosetting polyphenylene ether resins, as their main components, which exhibit low dielectric constants and / or low dielectric dissipation factors, have been studied and disclosed. However, the materials disclosed so far still have room for improvement in terms of achieving both low dielectric constants and low dielectric dissipation factors and mechanical properties, and when these materials are used in printed circuit boards, there are problems in that the processability of the wiring board is limited in addition to the amount of information and processing speed.

[0004] To address these problems, techniques have been developed for adding a thermoplastic resin, such as a styrene-based block copolymer, which has excellent mechanical properties, as a modifier to the above-mentioned thermosetting hydrocarbon resin or cured resin. For example, Patent Document 1 discloses a technique for using a styrene-based block copolymer as a modifier to reduce the dielectric loss tangent and thermal expansion coefficient of a thermosetting polyphenylene ether resin. However, while styrene-based block copolymers have excellent mechanical properties, they suffer from the problem of being less reactive than thermosetting resins. In view of these problems, Patent Document 2 discloses a resin composition that uses a styrene-based block copolymer, which has excellent reactivity, as a main component, and has a low dielectric constant, low dielectric loss tangent, and excellent heat resistance.

[0005] International Publication No. 2021 / 010432 Japanese Patent Application Laid-Open No. 2022-33057

[0006] However, the resin compositions using styrene-based block copolymers disclosed in Patent Documents 1 and 2 have the problem that there is still room for improvement in terms of achieving a low dielectric constant, a low dielectric loss tangent, heat resistance, and adhesion to metal foil. Furthermore, increasing the amount of rubber components in the resin composition to achieve a low dielectric constant, a low dielectric loss tangent, and improved adhesion to metal foil results in a decrease in heat resistance after curing. Furthermore, during the production process of the resin composition, components insoluble in organic solvents and water are generated due to the metal components remaining in the styrene-based block copolymer, which frequently clogs the mesh and reduces productivity, creating a manufacturing problem.

[0007] Therefore, an object of the present invention is to provide a conjugated diene-based copolymer that can give a cured product having a low dielectric constant and a low dielectric dissipation factor, as well as high heat resistance and high copper adhesion, and a resin composition containing the conjugated diene-based copolymer.

[0008] As a result of extensive investigations aimed at solving the problems of the prior art described above, the present inventors have found that a cured product of a resin composition containing a conjugated diene copolymer having a predetermined structure has a low dielectric constant and a low dielectric loss tangent, and is also excellent in heat resistance and copper adhesion, and have thus completed the present invention.

[0009] [1] A conjugated diene copolymer satisfying the following conditions (1) to (4): (Condition (1)) The conjugated diene copolymer has a polymer block (A) containing a vinyl aromatic monomer unit (unit (a-1)) having a radical reactive group. (Condition (2)) The conjugated diene copolymer has a polymer block (B) mainly composed of a conjugated diene monomer unit (unit (b)). (Condition (3)) The number average molecular weight of the conjugated diene copolymer is more than 40,000 and not more than 150,000. (Condition (4)) The content of all vinyl aromatic monomer units (a) including the unit (a-1) in the conjugated diene copolymer is 5 to 70 mass%. [2] The conjugated diene copolymer according to [1] above further satisfies the following condition (5): (Condition (5)) The conjugated diene copolymer has a tan δ peak maximum temperature of less than -30°C when measured with a dynamic mechanical analyzer (DMA) at 10 rad / s. [3] The conjugated diene copolymer according to [1] or [2] above, further satisfying the following condition (6): (Condition (6)) The amount of residual Co in the conjugated diene copolymer is 0.1 ppm or less, and the amount of residual Ti in the conjugated diene copolymer is 500 ppm or less. [4] The conjugated diene copolymer according to any one of [1] to [3] above, further satisfying the following condition (7): (Condition (7)) The number average molecular weight of the conjugated diene copolymer is more than 40,000 and 100,000 or less. [5] The conjugated diene copolymer according to any one of [1] to [4], wherein the polymer block (A) further comprises a vinyl aromatic monomer unit (unit (a-2)) (excluding the unit (a-1)), and the total content of the vinyl aromatic monomer unit (unit (a-1)) having a radical reactive group and the unit (a-2) in the conjugated diene copolymer is 5 to 70 mass%. [6] The conjugated diene copolymer according to any one of [1] to [5], wherein at least a portion of the unit (b) in the conjugated diene copolymer is hydrogenated. [7] The conjugated diene copolymer according to any one of [1] to [6], wherein at least a portion of the unit (b) in the conjugated diene copolymer is hydrogenated, and the hydrogenation rate is 98% or less.[8] The conjugated diene copolymer according to any one of [1] to [7] above, wherein at least a portion of the units (b) of the conjugated diene copolymer is hydrogenated, and the hydrogenation rate is 50% or more and 98% or less. [9] The conjugated diene copolymer according to any one of [5] to [8] above, wherein the conjugated diene copolymer further satisfies the following condition (8): (Condition (8)) The mass ratio of the units (a-1) to the units (a-2) is (a-1) / (a-2)=30 / 70 to 99 / 1.

[10] A conjugated diene copolymer composition comprising the conjugated diene copolymer (conjugated diene copolymer (D)) according to any one of [1] to [9] above, and a conjugated diene copolymer (E) that satisfies the following condition (9): (Condition (9)) The number average molecular weight is 40,000 or less.

[11] The conjugated diene copolymer composition according to

[10] above, comprising the conjugated diene copolymer (D) according to any one of [1] to [9] above, and the conjugated diene copolymer (E) further satisfying the following condition (10): (Condition (10)) The ratio (MnD / MnE) of the number average molecular weight (MnD) of the conjugated diene copolymer (D) to the number average molecular weight (MnE) of the conjugated diene copolymer (E) is 2 or more.

[12] The conjugated diene copolymer composition according to

[10] or

[11] above, comprising the conjugated diene copolymer (D) according to any one of [1] to [9] above, and the conjugated diene copolymer (E) further satisfying the following condition (11): (Condition (11)) The conjugated diene copolymer composition has a polymer block (A) containing a vinyl aromatic monomer unit (unit (a-1)) having a radical reactive group.

[13] The conjugated diene copolymer composition according to

[12] , wherein the conjugated diene copolymer (E) has a polymer block (B) and / or a random polymer block (C) mainly composed of conjugated diene monomer units (units (b)), and the random polymer block (C) contains a vinyl aromatic monomer unit (units (a-1)) having a radical reactive group and a conjugated diene monomer unit (units (b)).

[14] The conjugated diene copolymer composition according to

[13] above, wherein the random polymer block (C) constituting the conjugated diene copolymer (E) further contains a vinyl aromatic monomer unit (unit (a-2)) (excluding unit (a-1)).

[15] The conjugated diene copolymer composition according to any one of

[11] to

[14] above, which contains the conjugated diene copolymer (E) which further satisfies the following (condition (11)): (condition (11)) The conjugated diene copolymer composition has a polymer block (A) containing a vinyl aromatic monomer unit (unit (a-1)) having a radical reactive group.

[16] The conjugated diene copolymer composition according to

[15] , wherein the conjugated diene copolymer (E) has a polymer block (B) and / or a random polymer block (C) mainly composed of conjugated diene monomer units (units (b)), and the random polymer block (C) contains a vinyl aromatic monomer unit (unit (a-1)) having a radical reactive group and a conjugated diene monomer unit (unit (b)).

[17] The conjugated diene copolymer composition according to

[16] , wherein the random polymer block (C) constituting the conjugated diene copolymer (E) further contains a vinyl aromatic monomer unit (unit (a-2)) (excluding units (a-1)).

[18] A resin composition comprising: component (I): the conjugated diene copolymer according to any one of [1] to [9] above, or the conjugated diene copolymer composition according to any one of

[10] to

[17] above; and at least one component selected from the group consisting of the following components (II) to (III): component (II): a radical initiator; and component (III): a curable resin (excluding component (I)).

[19] The resin composition according to

[18] above, wherein component (III) is at least one selected from the group consisting of polyphenylene ether resins, polyimide resins, liquid crystal polyester resins, fluorine-based resins, epoxy resins, and hydrocarbon resins.

[20] A cured product of the conjugated diene copolymer according to any one of [1] to [9] above or the conjugated diene copolymer composition according to any one of

[10] to

[17] above.

[21] A cured product of the resin composition according to

[18] above.

[22] A resin film containing the resin composition according to

[18] .

[23] A prepreg which is a composite of a substrate and the resin composition described in

[18] above.

[24] The prepreg described in

[23] above, wherein the substrate is glass cloth.

[25] A laminate having the resin film described in

[22] above and a metal foil.

[26] A laminate having a cured product of the prepreg described in

[22] above and a metal foil.

[27] A material for electronic circuit boards which includes the cured product described in

[21] above.

[28] A material for electronic circuit boards which includes the resin film described in

[22] above.

[29] A material for electronic circuit boards which includes the prepreg described in

[23] above.

[0010] According to the present invention, there are provided a conjugated diene-based copolymer and a resin composition containing the conjugated diene-based copolymer, which can give a cured product having a low dielectric constant and a low dielectric loss tangent and excellent heat resistance and copper adhesion.

[0011] Hereinafter, a mode for carrying out the present invention (hereinafter simply referred to as "the present embodiment") will be described in detail. Note that the following present embodiment is an example for explaining the present invention, and is not intended to limit the present invention to the following content, and the present invention can be carried out in various modified forms within the scope of its gist.

[0012] [Conjugated Diene Copolymer] The conjugated diene copolymer of this embodiment satisfies the following conditions (1) to (4): (Condition (1)) It has a polymer block (A) containing a vinyl aromatic monomer unit (unit (a-1)) having a radical reactive group. (Condition (2)) It has a polymer block (B) mainly composed of a conjugated diene monomer unit (unit (b)). (Condition (3)) The number average molecular weight of the conjugated diene copolymer is more than 40,000 and not more than 150,000. (Condition (4)) The content of all vinyl aromatic monomer units (a) including the unit (a-1) in the conjugated diene copolymer is 5 to 70 mass%.

[0013] The conjugated diene copolymer of this embodiment can provide a cured product that has a low dielectric constant and a low dielectric loss tangent, and also has excellent heat resistance and copper adhesion.

[0014] (Condition (1)) The conjugated diene copolymer of this embodiment has a polymer block (A) containing a vinyl aromatic monomer unit (a-1) (hereinafter, may be referred to as unit (a-1)) having a radical reactive group. The polymer block (A) is mainly composed of vinyl aromatic monomer units. That is, the polymer block (A) may be mainly composed of the unit (a-1), or may contain the unit (a-1) and vinyl aromatic monomer units (a-2) excluding the unit (a-1), and may be mainly composed of the sum of these. In this specification, the vinyl aromatic monomer units in the polymer block (A) may be collectively referred to as unit (a). Here, the term "mainly composed of" means that the amount of vinyl aromatic monomer units in the polymer block (A) is 70 mass % or more. From the viewpoint of heat resistance of the cured resin composition, the content of the unit (a-1) in the polymer block (A) is preferably 50 to 100% by mass, more preferably 75 to 100% by mass, and even more preferably 80 to 100% by mass. The unit (a-1) refers to a structural unit derived from a vinyl aromatic compound having a radical reactive group, which is produced by polymerization of a vinyl aromatic compound having a radical reactive group. The "radical reactive group" possessed by the vinyl aromatic monomer unit is a chemical group capable of generating free radicals and / or inducing the formation of free radical species by the action of heat and / or light and / or free radical species of a radical initiator. By including the vinyl aromatic monomer unit (a-1) having a radical reactive group in the conjugated diene copolymer of this embodiment, the cured resin composition using the conjugated diene copolymer of this embodiment tends to have excellent heat resistance.

[0015] The radical reactive group is not particularly limited as long as it generates free radicals, and may be any chemical group. After the monomers are polymerized to produce the conjugated diene copolymer, the radical reactive functional group exists in the conjugated diene copolymer, i.e., the radical reactive group is not consumed during polymerization and maintains its radical reactivity. The radical reactive group is not limited to the following. For example, chemical groups that generate free radicals primarily due to light and / or a radical initiator include benzophenone groups, benzoyl groups, groups containing an anthraquinone skeleton, and thioxanthone groups. Furthermore, chemical groups that generate free radicals primarily due to heat and / or light and / or a radical initiator include groups containing disulfide bonds and groups containing peroxy bonds. Furthermore, chemical groups that generate free radicals primarily due to heat and / or a radical initiator include benzyl carbons having at least one hydrogen substituent, thiol groups, vinyl groups, groups containing an alkoxyamine skeleton, and groups containing an azo bond. Furthermore, the chemical groups shown above may have other substituents or be bonded to other atomic groups as long as they generate free radical species. However, from the viewpoint of the dielectric performance of the cured product of the resin composition of this embodiment, chemical groups containing a benzyl carbon atom having at least one hydrogen substituent, which are low polarity, or chemical groups containing a vinyl group are preferred.

[0016] Examples of the vinyl aromatic compound having a radical reactive group that forms the vinyl aromatic monomer unit (a-1) having a radical reactive group include, but are not limited to, o-methylstyrene, p-methylstyrene, o-ethylstyrene, p-ethylstyrene, o-isopropylstyrene, p-isopropylstyrene, o-methyl-α-methylstyrene, p-methyl-α-methylstyrene, o-ethyl-α-methylstyrene, p-ethyl-α-methylstyrene, o-isopropyl-α-methylstyrene, p-isopropyl-α-methylstyrene, divinylbenzene, or any mixture thereof, with p-methylstyrene being preferred from the viewpoint of the reactivity described above. These may be used alone or in combination of two or more.

[0017] The polymer block (A) constituting the conjugated diene copolymer of this embodiment may contain a vinyl aromatic monomer unit (a-2) (excluding the unit (a-1); hereinafter, this may be referred to as unit (a-2)). The vinyl aromatic monomer unit (a-2) refers to a structural unit derived from a vinyl aromatic compound in a copolymer produced by polymerization of a vinyl aromatic compound. Examples of the vinyl aromatic compound that forms the unit (a-2) include, but are not limited to, styrene, 1,1-diphenylethylene, N,N-dimethyl-p-aminoethylstyrene, and N,N-diethyl-p-aminoethylstyrene. These may be used alone or in combination of two or more.

[0018] (Condition (2)) The conjugated diene copolymer of this embodiment has a polymer block (B) (hereinafter may be referred to as polymer block (B)) mainly composed of conjugated diene monomer units (units (b)). Here, the term "mainly composed of" means that the amount of conjugated diene monomer units in polymer block (B) is 70 mass% or more. The conjugated diene monomer units (b) refer to structural units derived from a conjugated diene compound in a conjugated diene copolymer produced by polymerization of a conjugated diene compound. By having the conjugated diene monomer units (b), the cured product of a resin composition using the conjugated diene copolymer of this embodiment tends to have excellent copper adhesion. The conjugated diene compound is a diolefin having a pair of conjugated double bonds. Conjugated diene compounds include, but are not limited to, 1,3-butadiene, 2-methyl-1,3-butadiene, isoprene, 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene, 2-methyl-1,3-pentadiene, 1,3-hexadiene, 1,3-cyclohexadiene, and isoprene. Among these, 1,3-butadiene and isoprene are preferred, and 1,3-butadiene is more preferred. 1,3-Butadiene and isoprene are widely used and easily available, are advantageous from a cost perspective, and are easily copolymerizable with styrene, which is commonly used as a vinyl aromatic compound (described below). These compounds may be used alone or in combination of two or more. Furthermore, the conjugated diene compounds described above may be bio-derived conjugated diene compounds.

[0019] As described above, the conjugated diene copolymer of this embodiment has a polymer block (A) containing a vinyl aromatic monomer unit (a-1) having a radical reactive group and a polymer block (B) mainly composed of a conjugated diene monomer unit (b). The conjugated diene copolymer of this embodiment is preferably one mainly composed of a vinyl aromatic monomer unit (a-1) having a radical reactive group and a conjugated diene monomer unit (b). Here, the term "mainly composed of" means that the conjugated diene copolymer of this embodiment contains the vinyl aromatic monomer units (a-1) having a radical reactive group and the conjugated diene monomer units (b) in a total amount of 51% by mass or more, and the total amount of the vinyl aromatic monomer units (a-1) having a radical reactive group and the conjugated diene monomer units (b) in the conjugated diene copolymer of this embodiment is preferably 60% by mass or more, more preferably 70% by mass or more, even more preferably 80% by mass or more, still more preferably 90% by mass or more, still more preferably 95% by mass or more, and particularly preferably 100% by mass (intentionally not including other copolymerization components).

[0020] Since the conjugated diene copolymer of the present embodiment is mainly composed of the sum of the above-mentioned units (a-1) and (b), compatibility and reactivity with component (II): radical initiator, component (III): curable resin, component (IV): flame retardant, and component (V): filler, which will be described later, as well as reactivity between the conjugated diene copolymers themselves, tend to be good, and a resin composition which becomes a cured product having a low dielectric constant and a low dielectric dissipation factor and excellent heat resistance and copper adhesion tends to be obtained.

[0021] The macrostructure of the conjugated diene copolymer of this embodiment is a block copolymer having two polymer blocks: a polymer block (A) containing vinyl aromatic monomer units (a) (units (a-1) and, optionally, units (a-2)), and a polymer block (B) mainly composed of conjugated diene monomer units (b). The term "mainly composed of" indicating the content of the monomer units constituting the polymer block (A) and the polymer block (B) means that the polymer block (A) and the polymer block (B) are substantially composed of vinyl aromatic monomer units and / or conjugated diene monomer units, and that no other monomers are intentionally added. The composition ratios of the above-described macrostructure, the vinyl aromatic monomer unit (a-1) having a radical reactive group, the vinyl aromatic monomer unit (a-2) other than the (a-1), and the conjugated diene monomer unit (b) in the conjugated diene copolymer of this embodiment can be measured by a method using a nuclear magnetic resonance (NMR) spectrometer (the method described in Y. Tanaka, et al., RUBBER CHEMISTRY and TECHNOLOGY 54, 685 (1981), hereinafter referred to as the "NMR method") using the conjugated diene copolymer before hydrogenation or the hydrogenated conjugated diene copolymer after hydrogenation as a sample.

[0022] (Condition (3)) The conjugated diene copolymer of this embodiment has a number average molecular weight of more than 40,000 and not more than 150,000. The number average molecular weight is determined by measuring the molecular weight of the peak in a chromatogram obtained by gel permeation chromatography (GPC) based on a calibration curve (prepared using the peak molecular weight of the standard polystyrene) obtained from the measurement of commercially available standard polystyrene. When the conjugated diene copolymer of this embodiment has a number average molecular weight within the above range, the cured product of the resin composition of this embodiment, which will be described later, tends to have excellent dielectric constant and dielectric loss tangent. The number average molecular weight of the conjugated diene copolymer can be measured by the method described in the examples below. The molecular weight distribution is the ratio (Mw / Mn) of the weight average molecular weight (Mw) to the weight average molecular weight (Mn). The molecular weight distribution of the single peak of the conjugated diene copolymer of this embodiment, as measured by GPC, is preferably 5.0 or less, more preferably 4.0 or less, even more preferably 3.0 or less, and even more preferably 2.5 or less. When the number-average molecular weight of the conjugated diene copolymer of this embodiment is more than 40,000 and less than 150,000, the compatibility with the curable resin (component (III)), the flame retardant (component (IV)), and the filler (component (V)) described below is improved, and the dielectric loss tangent and / or dielectric constant of the cured product tend to be improved. When the resin composition of this embodiment is used as a varnish and impregnated into a substrate such as glass cloth (described below) to produce a prepreg, the number-average molecular weight of the conjugated diene copolymer of this embodiment is more than 40,000 and less than 150,000, which improves permeability into the substrate and tends to enable the production of a uniform prepreg. From the above perspective, the number-average molecular weight of the conjugated diene copolymer of this embodiment is more than 40,000 and less than 150,000, preferably 125,000 or less, more preferably 100,000 or less, even more preferably 75,000 or less, and even more preferably 60,000 or less. From the viewpoint of good handleability, the lower limit is more than 40,000, preferably 45,000 or more, more preferably 50,000 or more. If the number average molecular weight is 40,000 or less, the conjugated diene copolymer tends to fuse together, resulting in a decrease in handleability.The number average molecular weight, weight average molecular weight, and molecular weight distribution of the conjugated diene copolymer of this embodiment can be controlled within the above-mentioned numerical ranges by adjusting polymerization conditions such as the amount of monomer added, timing of addition, polymerization temperature, and polymerization time.

[0023] (Condition (4)) In the conjugated diene copolymer of this embodiment, the content of all vinyl aromatic monomer units, including the vinyl aromatic monomer unit (a-1) having a radical reactive group, is 5% by mass or more and 70% by mass or less. This is preferably 10% by mass or more and 65% by mass or less, more preferably 15% by mass or more and 60% by mass or less, and even more preferably 20% by mass or more and 55% by mass or less. This tends to improve compatibility and reactivity with the following components: component (II): radical initiator; component (III): curable resin; component (IV): flame retardant; and component (V): filler, as well as reactivity between the conjugated diene copolymers themselves. This tends to result in a resin composition that has a low dielectric constant and a low dielectric dissipation factor and is a cured product that has excellent heat resistance and copper adhesion. From the same viewpoint, when the conjugated diene copolymer of this embodiment contains the vinyl aromatic monomer unit (a-1) having a radical reactive group and the vinyl aromatic monomer unit (a-2), the total content of the vinyl aromatic monomer unit (a-1) having a radical reactive group and the vinyl aromatic monomer unit (a-2) is preferably 5% by mass or more and 70% by mass or less, more preferably 10% by mass or more and 65% by mass or less, even more preferably 15% by mass or more and 60% by mass or less, and even more preferably 20% by mass or more and 55% by mass or less. The content of the unit (a-1), the unit (a-2), and all the vinyl aromatic monomer units in the conjugated diene copolymer of this embodiment can be controlled within the above numerical range by adjusting the type, amount, addition timing, and polymerization time of the monomer in the polymerization step.

[0024] (Condition (5)) The conjugated diene copolymer of this embodiment preferably has a tan δ peak maximum temperature of less than -30°C when measured at 10 rad / s using a dynamic mechanical analyzer (DMA). When the conjugated diene copolymer of this embodiment has this tan δ peak temperature, compatibility and reactivity with the following components (II): radical initiator, component (III): curable resin, component (IV): flame retardant, and component (V): filler, as well as reactivity between the conjugated diene copolymers themselves, tend to be good, resulting in a resin composition that has a low dielectric constant and low dielectric dissipation factor and is a cured product that has excellent heat resistance and copper adhesion. The tan δ peak maximum temperature can be controlled to less than -30°C by adjusting the content of vinyl aromatic monomer units in the conjugated diene copolymer to within the range of 5 to 70% by mass.

[0025] (Condition (6)) In the conjugated diene copolymer of this embodiment, the amount of residual cobalt in the conjugated diene copolymer is preferably 0.1 ppm or less, more preferably 0.05 ppm or less, and even more preferably 0.01 ppm or less. Furthermore, the amount of residual titanium is preferably 500 ppm or less, more preferably 250 ppm or less, and even more preferably 100 ppm or less. When the amounts of residual cobalt and residual titanium in the conjugated diene copolymer of this embodiment are within the above ranges, the efficiency of generating unnecessary metal residue components in the solvent during the step of purifying the conjugated diene copolymer is low, the probability of mesh clogging during the production step is reduced, and productivity tends to be improved. The amount of residual cobalt can be controlled to 0.1 ppm or less by controlling the amount of residual cobalt in the hydrogenation catalyst described below to 0.1 ppm or less, and the amount of residual titanium can be controlled to 500 ppm or less by controlling the amount of the hydrogenation catalyst used to 500 ppm or less.

[0026] (Condition (7)) The number average molecular weight of the conjugated diene copolymer of this embodiment is preferably more than 40,000 and not more than 100,000, more preferably 40,000 or more and not more than 80,000, and even more preferably 40,000 or more and not more than 60,000. From the viewpoint of copper adhesion of the cured product of the resin composition, the conjugated diene copolymer of this embodiment preferably has a number average molecular weight of more than 40,000, and from the viewpoint of heat resistance of the cured product of the resin composition, it is preferably 100,000 or less. The number average molecular weight can be controlled to be within the above-mentioned numerical range by adjusting the polymerization conditions of the conjugated diene copolymer.

[0027] (Hydrogenation Ratio) As described above, the conjugated diene copolymer of this embodiment has a polymer block (B) mainly composed of conjugated diene monomer units (b). In the conjugated diene copolymer of this embodiment, at least a portion of the conjugated diene monomer units (b) may be hydrogenated. That is, the aliphatic double bonds based on the conjugated diene monomer units (b) may be hydrogenated. Hydrogenation of the conjugated diene copolymer tends to produce a resin composition that has a low dielectric constant and a low dielectric loss tangent and that becomes a cured product that is excellent in heat resistance and copper adhesion.

[0028] The conjugated diene copolymer of this embodiment preferably has a hydrogenation rate of 98% or less, more preferably 1% to 98%, and even more preferably 50% to 98%. A hydrogenation rate of 98% or less tends to result in a resin composition with a low dielectric constant, a low dielectric dissipation factor, and excellent copper adhesion. A hydrogenation rate of 1% or more, which reduces the amount of aliphatic double bonds based on the conjugated diene monomer units in the conjugated diene copolymer, can suppress the gelation reaction caused by free radicals derived from the aliphatic double bonds based on the conjugated diene monomer units during storage of the resin composition described below, tending to improve storage stability. Furthermore, a hydrogenation rate of 50% or more improves compatibility and reactivity with the following components: component (II): radical initiator; component (III): curable resin; component (IV): flame retardant; and component (V): filler, as well as reactivity between the conjugated diene copolymers themselves. This tends to result in a resin composition with a low dielectric constant, a low dielectric dissipation factor, and a cured product with excellent heat resistance and copper adhesion.

[0029] A hydrogenation catalyst can be used in the hydrogenation reaction. Examples of the hydrogenation catalyst include, but are not limited to, (1) supported heterogeneous hydrogenation catalysts in which a metal such as Ni, Pt, Pd, or Ru is supported on carbon, silica, alumina, or diatomaceous earth; (2) so-called Ziegler-type hydrogenation catalysts in which a transition metal salt such as an organic acid salt or acetylacetone salt of Ni, Co, Fe, or Cr is used with a reducing agent such as an organoaluminum; and (3) homogeneous hydrogenation catalysts such as so-called organometallic complexes of organometallic compounds of Ti, Ru, Rh, Zr, or the like. Specific examples of the hydrogenation catalyst include the hydrogenation catalysts described in JP-B Nos. 42-8704, 43-6636, 63-4841, 1-37970, 1-53851, and 2-9041. Preferred hydrogenation catalysts include titanocene compounds and / or reducing organometallic compounds. Examples of titanocene compounds that can be used include those described in JP-A-8-109219. Examples of titanocene compounds include, but are not limited to, compounds having at least one ligand with a (substituted) cyclopentadienyl skeleton, an indenyl skeleton, or a fluorenyl skeleton, such as biscyclopentadienyltitanium dichloride and pentamethylcyclopentadienyltitanium trichloride. The titanocene compound may contain one or a combination of two of the above skeletons. Examples of reducing organometallic compounds include, but are not limited to, organic alkali metal compounds such as organolithium compounds, organomagnesium compounds, organoaluminum compounds, organoboron compounds, and organozinc compounds. These compounds may be used alone or in combination. The hydrogenation rate can be controlled to the above-mentioned level by appropriately adjusting the reaction temperature, reaction time, hydrogen supply amount, catalyst amount, and the like in the hydrogenation method. The temperature during the hydrogenation reaction is preferably 55 to 200° C., more preferably 60 to 170° C., and even more preferably 65 to 160° C. The pressure of hydrogen used in the hydrogenation reaction is 0.1 to 15 MPa, preferably 0.2 to 10 MPa, and more preferably 0.3 to 5 MPa.The hydrogenation reaction time is usually 3 minutes to 10 hours, preferably 10 minutes to 5 hours. The hydrogenation reaction can be carried out by a batch process, a continuous process, or a combination thereof.

[0030] (Mass Ratio: Units (a-1) / Units (a-2)) When the conjugated diene copolymer of this embodiment has the vinyl aromatic monomer unit (a-1) having the radical reactive group and the vinyl aromatic monomer unit (a-2) (excluding the unit (a-1)), the mass ratio (a-1) / (a-2) of these units (a-1) to units (a-2) is preferably in the range of 30 / 70 to 99 / 1. When the conjugated diene copolymer of this embodiment has the mass ratio (a-1) / (a-2), compatibility and reactivity with component (II): radical initiator, component (III): curable resin, component (IV): flame retardant, and component (V): filler, as well as reactivity between the conjugated diene copolymers, are improved, and a resin composition tends to be obtained that has a low dielectric constant and a low dielectric dissipation factor and is a cured product that has excellent heat resistance and copper adhesion.

[0031] [Conjugated Diene Copolymer Composition] The conjugated diene copolymer composition of this embodiment contains the conjugated diene copolymer of this embodiment described above and a conjugated diene copolymer (E) that satisfies the following (condition (9)): (condition (9)): the number average molecular weight is 40,000 or less. Here, to distinguish it from the conjugated diene copolymer (E), the conjugated diene copolymer of this embodiment may be referred to as conjugated diene copolymer (D) in this specification. When the conjugated diene copolymer composition of this embodiment contains the conjugated diene copolymer (E) in addition to the conjugated diene copolymer (D), compatibility and reactivity with component (II): a radical initiator, component (III): a curable resin, component (IV): a flame retardant, and component (V): a filler, as well as reactivity between the conjugated diene copolymers, are improved, and a resin composition that has a low dielectric constant and a low dielectric dissipation factor and that forms a cured product that is excellent in heat resistance and copper adhesion, is obtained.

[0032] The conjugated diene copolymer composition of this embodiment contains a conjugated diene copolymer (D) and a conjugated diene copolymer (E). Methods for producing the conjugated diene copolymer composition include: (1) solution polymerization of each component that forms two or more peaks in a chromatogram obtained by GPC measurement, and mixing the solutions containing the polymers; (2) mixing each component after removing the solvent and catalyst; (3) adding a polymerization initiator in two stages during the polymerization reaction; (4) adding a protic reagent such as alcohol as a modifier, coupling agent, or polymerization terminator that reacts with the living terminal during the polymerization reaction in a molar amount that is insufficient relative to the living terminal to stop the reaction of some living terminals; (5) adding a protic reagent such as alcohol as a modifier or polymerization terminator in an equimolar amount to the living terminal after the polymerization reaction to stop the reaction of all living terminals, and then adding a new polymerization initiator and monomer to the solution to carry out polymerization.

[0033] As described above, the number average molecular weight (MnE) of the conjugated diene copolymer (E) is 40,000 or less, preferably 35,000 or less, and more preferably 30,000 or less. The lower limit of the number average molecular weight of the conjugated diene copolymer (E) is not particularly limited, but if the number average molecular weight is too small, the molecular weight between crosslinking points decreases during reaction with the curable resin (component (III) described below), making it difficult to form an appropriate crosslink density, and the effect of reducing the dielectric constant and / or dielectric loss tangent of the resin composition of this embodiment tends to be reduced. From the viewpoint of reducing the dielectric constant and / or dielectric loss tangent, the number average molecular weight of the conjugated diene copolymer (E) is preferably 2,000 or more, more preferably 2,500 or more, even more preferably 3,000 or more, and even more preferably 3,500 or more.

[0034] The conjugated diene copolymer (E) preferably further satisfies the following condition (10): (Condition (10)) The ratio (MnD / MnE) of the number average molecular weight (MnD) of the conjugated diene copolymer (D) to the number average molecular weight (MnE) of the conjugated diene copolymer (E) is 2 or greater. When the conjugated diene copolymer (E) satisfies the condition (10), compatibility and reactivity with the following components (II): radical initiator, component (III): curable resin, component (IV): flame retardant, and component (V): filler, as well as reactivity between the conjugated diene copolymers themselves, tend to be improved, resulting in a resin composition that has a low dielectric constant and low dielectric dissipation factor and is a cured product with excellent heat resistance and copper adhesion. (MnD / MnE) is more preferably 2.5 or greater, and even more preferably 5 or greater.

[0035] The conjugated diene copolymer (E) preferably satisfies the following condition (11): (Condition (11)) The conjugated diene copolymer (E) has a polymer block (A) containing a vinyl aromatic monomer unit (a-1) having a radical reactive group. When the conjugated diene copolymer (E) satisfies the condition (11), compatibility and reactivity with component (II): radical initiator, component (III): curable resin, component (IV): flame retardant, and component (V): filler, as well as reactivity between the conjugated diene copolymers, tend to be good, and a resin composition which forms a cured product having a low dielectric constant and a low dielectric dissipation factor and excellent heat resistance and copper adhesion, is obtained.

[0036] The conjugated diene copolymer (E) preferably has, in addition to the polymer block (A), a polymer block (B) and / or a random polymer block (C) mainly composed of conjugated diene monomer units (b). That is, the conjugated diene copolymer (E) is preferably a block copolymer composed of polymer block (A) and polymer block (B), a block copolymer composed of polymer block (A) and polymer block (C), or a block copolymer composed of polymer block (A), polymer block (B), and polymer block (C). The term "mainly composed of," which indicates the content of the monomer units constituting the polymer blocks (A) to (C), means that the polymer blocks are substantially composed of vinyl aromatic monomer units and / or conjugated diene monomer units, and that no other monomers are intentionally added. The random polymer block (C) preferably has a vinyl aromatic monomer unit (a-1) having a radical-reactive group and a conjugated diene monomer unit (b). The random polymer block (C) may further have a vinyl aromatic monomer unit (a-2) (excluding the unit (a-1)). When the conjugated diene copolymer composition of this embodiment contains the conjugated diene copolymer (E) in addition to the conjugated diene copolymer (D), compatibility and reactivity with component (II): radical initiator, component (III): curable resin, component (IV): flame retardant, and component (V): filler, as well as reactivity between the conjugated diene copolymers, are improved, and a resin composition that has a low dielectric constant and a low dielectric dissipation factor and that is a cured product that is excellent in heat resistance and copper adhesion, is obtained.

[0037] [Resin Composition] The resin composition of this embodiment contains the conjugated diene copolymer of this embodiment or the conjugated diene copolymer composition of this embodiment (component (I)) and at least one component selected from the group consisting of the following components (II) to (III): component (II): radical initiator; component (III): curable resin (excluding component (I)). The resin composition of this embodiment may further contain at least one selected from the group consisting of component (IV): flame retardant, and component (V): filler. From the viewpoints of achieving a low dielectric constant, low dielectric loss tangent, heat resistance, and copper adhesion of the resin composition of this embodiment and its cured product, the resin composition of this embodiment preferably contains the above-mentioned components (I), (II), and (III) curable resin (excluding component (I)).

[0038] (Component (II): Radical Initiator) Conventionally known radical initiators can be used. For example, thermal radical initiators include, but are not limited to, hydroperoxides such as diisopropylbenzene hydroperoxide (Percumyl P), cumene hydroperoxide (Percumyl H), and t-butyl hydroperoxide (Perbutyl H), α,α-bis(t-butylperoxy-m-isopropyl)benzene (Perbutyl P), dicumyl peroxide (Percumyl D), 2,5-dimethyl-2,5-bis(t-butylperoxy)hexane (Perhexa 25B), t-butylcumyl peroxide (Perbutyl C), di-t-butyl peroxide (Perbutyl ... Examples of the radical initiator include dialkyl peroxides such as hexyne-3 (Perhexyne 25B) and t-butylperoxy-2-ethylhexanoate (Perbutyl O), ketone peroxides, peroxyketals such as n-butyl-4,4-di-(t-butylperoxy)valerate (Perhexa V), organic peroxides such as diacyl peroxides, peroxydicarbonates, and peroxyesters, and azo compounds such as 2,2-azobisisobutylnitrile, 1,1'-(cyclohexane-1-1-carbonitrile), 2,2'-azobis(2-cyclopropylpropionitrile), and 2,2'-azobis(2,4-dimethylvaleronitrile). These radical initiators may be used alone or in combination of two or more.

[0039] (Component (III): Curable Resin) As the curable resin, conventionally known resins can be used. Examples of the curable resin include, but are not limited to, polyphenylene ether resins, polyimide resins, liquid crystal polyester resins, fluorine-based resins, epoxy resins, and hydrocarbon resins. These curable resins may be used alone or in combination of two or more.

[0040] The polyphenylene ether resin, component (III), may be any resin that falls within the category of polyphenylene ether resins and contains phenylene ether units as repeating structural units. It may also contain structural units other than phenylene ether units. Regarding the homopolymer containing phenylene ether units, there is no particular limitation as to whether the phenylene group in the phenylene unit has a substituent. Examples of the substituent include acrylic groups such as an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, and a tert-butyl group, cyclic alkyl groups such as a cyclohexyl group, a vinyl group, an allyl group, an isopropenyl group, a 1-butenyl group, a 1-pentenyl group, a p-vinylphenyl group, a p-isopropenylphenyl group, a m-vinylphenyl group, a m-isopropenylphenyl group, an o-vinylphenyl group, an o-isopropenylphenyl group, a p-vinylbenzyl group, a p-isopropenylbenzyl group, a m-vinylbenzyl group, a m-isopropenylbenzyl group, an o-vinylbenzyl group, an o-isopropenylbenzyl group, a p-vinylphenylethenyl group, a p-vinylphenylpropenyl group, a p-vinylphenylbutenyl group, a m-vinylphenylethenyl group, a m-vinylphenylpropenyl group, a m-vinylphenylbutenyl group, and an o-vinylphenylethenyl group. Examples of functional group-containing substituents include unsaturated bond-containing substituents such as thenyl group, o-vinylphenylpropenyl group, o-vinylphenylbutenyl group, methacryl group, acrylic group, 2-ethylacrylic group, and 2-hydroxymethylacrylic group; and functional group-containing substituents such as hydroxyl group, carboxyl group, carbonyl group, thiocarbonyl group, acid halide group, acid anhydride group, carboxylic acid group, thiocarboxylic acid group, aldehyde group, thioaldehyde group, carboxylic acid ester group, amide group, sulfonic acid group, sulfonate ester group, phosphoric acid group, phosphate ester group, amino group, imino group, nitrile group, pyridyl group, quinoline group, epoxy group, thioepoxy group, sulfide group, isocyanate group, isothiocyanate group, silicon halide group, silanol group, alkoxy silicon group, tin halide group, boronic acid group, boron-containing group, boronate salt group, alkoxytin group, and phenyltin group. From the viewpoint of curability, it is preferable that the compound has any polar group for the purpose of having radical reactivity and / or reactivity with the curing agent (IV).From the viewpoint of the curability of the resin composition of the present embodiment, the polyphenylene ether resin as component (III) preferably has a molecular weight of not more than 100,000, more preferably not more than 50,000, and even more preferably not more than 10,000. The polyphenylene ether resin may have a linear structure or a crosslinked or branched structure.

[0041] The polyimide resin, component (III), may be any polyimide resin having an imide bond in the repeating unit and belonging to the category known as a polyimide resin. For example, a typical polyimide structure obtained by polycondensation (imide bond) of a tetracarboxylic acid or its dianhydride with a diamine is exemplified. From the viewpoint of curability, it is preferable for the polyimide structure to have an unsaturated group at the terminal. Examples of polyimide resins having an unsaturated group at the terminal include maleimide polyimide resins, nadiimide polyimide resins, and allylnadiimide polyimide resins. Examples of tetracarboxylic acids or their dianhydrides include, but are not limited to, aromatic tetracarboxylic acid dianhydrides, alicyclic tetracarboxylic acid dianhydrides, and aliphatic tetracarboxylic acid dianhydrides. These may be used alone or in combination of two or more. Examples of diamines include, but are not limited to, aromatic diamines, alicyclic diamines, and aliphatic diamines commonly used in polyimide synthesis. These may be used alone or in combination of two or more. In addition, at least one of the tetracarboxylic acid, the dianhydride thereof, and the diamine may have one or more functional groups selected from the group consisting of a fluorine group, a trifluoromethyl group, a hydroxyl group, a sulfone group, a carbonyl group, a heterocycle, a long-chain alkyl group, an allyl group, and the like, from the viewpoint of reducing the dielectric constant and the dielectric loss tangent.In addition, as the polyimide resin, commercially available polyimide resins may be used, and examples thereof include, but are not limited to, Neoprim (registered trademark) C-3650 (manufactured by Mitsubishi Gas Chemical Company, Inc., trade name), Neoprim C-3G30 (manufactured by Mitsubishi Gas Chemical Company, Inc., trade name), Neoprim C-3450 (manufactured by Mitsubishi Gas Chemical Company, Inc., trade name), Neoprim P500 (manufactured by Mitsubishi Gas Chemical Company, Inc., trade name), BT (bismaleimide-triazine) resin (manufactured by Mitsubishi Gas Chemical Company, Inc.), JL-20 (manufactured by New Japan Chemical Company, Inc., trade name) (these polyimide resin varnishes may contain silica), Rikacoat SN20, Rikacoat PN20, and I.S. Examples of such an anti-oxidant include Pyre-ML manufactured by T Co., Ltd.; UPIA-AT, UPIA-ST, UPIA-NF, and UPIA-LB manufactured by Ube Industries, Ltd.; PIX-1400, PIX-3400, PI2525, PI2610, HD-3000, and AS-2600 manufactured by Hitachi Chemical Co., Ltd.; HPC-5000, HPC-5012, HPC-1000, HPC-5020, HPC-3010, HPC-6000, HPC-9000, HCI-7000, HCI-1000S, HCI-1200E, and HCI-1300 manufactured by Showa Denko K.K.; BMI-2300 manufactured by Daiwa Kasei Kogyo Co., Ltd.; and MIR-3000 manufactured by Shin Nippon Kayaku Co., Ltd.

[0042] The liquid crystal polyester resin of component (III) is a polyester that forms an anisotropic molten phase and may be any resin that falls into the category of liquid crystal polyester resins, such as "X7G" manufactured by Eastman Kodak Company, Xyday (Zydar) manufactured by Dartco, Econol manufactured by Sumitomo Chemical Co., Ltd., and Vectra manufactured by Celanese Corporation.

[0043] The fluorine-based resin of component (III) may be any resin that falls into the category of fluorine-based resins, and is an olefin polymer containing a fluorine group. Examples of the fluorine-based resin include, but are not limited to, polytetrafluoroethylene, perfluoroalkoxyalkane, ethylene-tetrafluoroethylene copolymer, perfluoroethylene-propene copolymer, polyvinylidene fluoride, polychlorotrifluoroethylene, and ethylene-chlorotrifluoroethylene copolymer.

[0044] The epoxy resin as component (III) may be any resin that falls into the category of epoxy resins, and preferably has two or more epoxy groups in one molecule from the viewpoint of strength. Examples of epoxy resins include, but are not limited to, bixylenol-type epoxy resins, bisphenol A-type epoxy resins, bisphenol F-type epoxy resins, bisphenol S-type epoxy resins, bisphenol AF-type epoxy resins, dicyclopentadiene-type epoxy resins, trisphenol-type epoxy resins, naphthol novolac-type epoxy resins, phenol novolac-type epoxy resins, tert-butyl-catechol-type epoxy resins, naphthalene-type epoxy resins, naphthol-type epoxy resins, anthracene-type epoxy resins, glycidylamine-type epoxy resins, glycidyl ester-type epoxy resins, cresol novolac-type epoxy resins, biphenyl-type epoxy resins, alicyclic epoxy resins, heterocyclic epoxy resins, spiro ring-containing epoxy resins, cyclohexane-type epoxy resins, cyclohexanedimethanol-type epoxy resins, naphthylene ether-type epoxy resins, trimethylol-type epoxy resins, and tetraphenylethane-type epoxy resins. These epoxy resins may be used alone or in combination of two or more.

[0045] The hydrocarbon resin as component (III) may be any resin that falls into the category of so-called curable hydrocarbon resins, and preferably has two or more radical reactive groups in one molecule.

[0046] (Component (IV): Flame Retardant) Conventionally known flame retardants can be used. Examples of flame retardants include, but are not limited to, halogenated compounds, non-halogenated compounds, non-halogenated intumescent compounds, phosphorus-containing compounds, nitrogen-containing compounds, bromine-containing compounds, and mixtures thereof. These flame retardants may be used alone or in combination of two or more.

[0047] (Component (V): Filler) Conventionally known fillers can be used as the filler. Examples of fillers include, but are not limited to, inorganic fillers such as silica, calcium carbonate, magnesium carbonate, magnesium hydroxide, aluminum hydroxide, calcium sulfate, barium sulfate, carbon black, glass fiber, glass beads, glass balloons, glass flakes, graphite, titanium oxide, potassium titanate whiskers, carbon fiber, alumina, kaolin clay, silicic acid, calcium silicate, quartz, mica, talc, clay, zirconia, potassium titanate, alumina, and metal particles; and organic fillers such as wood chips, wood powder, pulp, and cellulose nanofibers. The shape of these fillers is not particularly limited and may be scaly, spherical, granular, powdery, irregular, or the like. The resin composition or cured product of this embodiment is often exposed to high temperatures during molding, etc., and to prevent shrinkage and deformation of the molded product due to the temperature change, it is preferable that the filler have a small linear expansion coefficient. From the viewpoint of reducing the linear expansion coefficient, silica is preferred as the filler, and examples of silica include amorphous silica, fused silica, crystalline silica, synthetic silica, hollow silica, etc. These fillers may be used alone or in combination of two or more.

[0048] (Other Additives) The resin composition and / or cured product of this embodiment may contain other additives. The other additives are not particularly limited as long as they are commonly used in the formulation of resin compositions and cured products. Examples of other additives include, but are not limited to, pigments and / or colorants such as carbon black and titanium oxide; lubricants such as stearic acid, behenic acid, zinc stearate, calcium stearate, magnesium stearate, and ethylene bisstearamide; mold release agents; plasticizers such as organic polysiloxanes, fatty acid esters such as phthalates, adipates, and azelaates, and mineral oils; antioxidants such as hindered phenols and phosphorus-based heat stabilizers; hindered amine light stabilizers; benzotriazole ultraviolet absorbers; antistatic agents; organic fillers; thickeners; antifoaming agents; leveling agents; resin additives such as adhesion promoters; other additives, or mixtures thereof. From the viewpoint of achieving the aforementioned low dielectric constant and low dielectric loss tangent, it tends to be preferable that the resin composition of the present embodiment does not contain a pigment, a colorant, a lubricant, a release agent, or an antistatic agent.

[0049] The resin composition in this embodiment may be a melt-kneaded mixture of the components, or a mixture of the components dissolved in a solvent and stirred (hereinafter referred to as "varnish"). However, from the viewpoint of ease of handling, varnish is preferred. Examples of solvents constituting the varnish include, but are not limited to, ketones such as acetone, methyl ethyl ketone (MEK), cyclohexanone, and γ-butyrolactone; acetate esters such as ethyl acetate, butyl acetate, cellosolve acetate, propylene glycol monomethyl ether acetate, carbitol acetate, and diethyl glycol monoacerate; carbitols such as cellosolve and butyl carbitol; aromatic hydrocarbons such as toluene and xylene; and amide solvents such as dimethylformamide, dimethylacetamide (DMAc), and N-methylpyrrolidone. The organic solvents may be used alone or in combination of two or more.

[0050] (Method for Producing Resin Composition) The method for producing the resin composition of this embodiment is not particularly limited, and known methods can be used. For example, a method of melt-kneading each component using a general mixer such as a Banbury mixer, a single-screw extruder, a twin-screw extruder, a co-kneader, or a multi-screw extruder, or a method of dissolving or dispersing and mixing each component and then removing the solvent by heating, etc. are mentioned. From the viewpoint of processability into a molded article suitable for use as a material for electronic circuit boards, such as a prepreg or a resin film, which will be described later, a method of dissolving or dispersing and mixing each component and then removing the solvent by heating is preferred.

[0051] [Cured Product] The cured product of this embodiment includes the conjugated diene copolymer of this embodiment described above. The cured product of this embodiment is a cured product of the conjugated diene copolymer, conjugated diene copolymer composition, or resin composition of this embodiment. The cured product of this embodiment can be obtained by curing the conjugated diene copolymer, conjugated diene copolymer composition, or resin composition of this embodiment at any temperature and for any period of time. This concept encompasses not only completely cured products, but also partially cured products containing uncured components (semi-cured products). In the process for producing a laminate described below, a further curing treatment step may be carried out on the cured product. The reaction temperature in the curing step of the cured product of this embodiment is preferably 80°C or higher, more preferably 100°C or higher, and even more preferably 120°C or higher. The reaction time is preferably 10 to 240 minutes, more preferably 20 to 230 minutes, and even more preferably 30 to 220 minutes. When the resin composition of this embodiment is a varnish, the curing reaction is preferably carried out after removing the solvent. The drying may be carried out by a conventionally known method such as heating or hot air blowing, and is preferably carried out at a temperature lower than the curing reaction temperature. The drying is carried out so that the amount of solvent in the cured product is preferably 10% by mass or less, more preferably 5% by mass or less.

[0052] [Resin Film] The resin film of this embodiment includes the resin composition of this embodiment. The resin film of this embodiment can be obtained, for example, by spreading a varnish made of the resin composition of this embodiment onto a suitable support to form a uniform thin film, drying it, and removing the solvent. This resin film can be wound into a roll and stored. The resin film of this embodiment may be laminated with a predetermined protective film. In such a case, the resin film can be used by peeling off the protective film. Examples of the support include films made of plastic materials, metal foils, release papers, etc. Examples of films made of plastic materials that serve as supports include polyesters such as polyethylene terephthalate and polyethylene naphthalate, polycarbonates, acrylics such as polymethyl methacrylate (PMMA), cyclic polyolefins, triacetyl cellulose (TAC), polyether sulfide (PES), polyether ketone, polyimides, etc., with polyethylene terephthalate and polyethylene naphthalate being preferred from the standpoints of availability and cost. Examples of metal foils include copper foil and aluminum foil, with copper foil being preferred. The copper foil may be a foil made of a single metal such as copper, or a foil made of an alloy of copper and another metal (for example, tin, chromium, silver, magnesium, nickel, zirconium, silicon, titanium, etc.). The surface of the support that is to be bonded to the resin composition layer may be subjected to a matte treatment, a corona treatment, an antistatic treatment, or a release treatment.

[0053] [Prepreg] The prepreg of this embodiment includes a substrate and the resin composition of this embodiment impregnated or coated on the substrate. That is, the prepreg of this embodiment is a composite of the resin composition of this embodiment and the substrate. The prepreg can be obtained, for example, by impregnating a substrate such as glass cloth with the varnish of the resin composition of this embodiment described above, followed by removing the solvent by the drying method described above. Examples of substrates include various glass cloths such as roving cloth, cloth, chopped mat, and surfacing mat; asbestos cloth, metal fiber cloth, and other synthetic or natural inorganic fiber cloths; woven or nonwoven fabrics obtained from liquid crystal fibers such as wholly aromatic polyamide fiber, wholly aromatic polyester fiber, and polybenzoxazole fiber; natural fiber cloths such as cotton cloth, linen cloth, and felt; natural cellulose-based substrates such as carbon fiber cloth, kraft paper, cotton paper, and cloth obtained from paper-glass blend yarn; and polytetrafluoroethylene porous film. However, glass cloth is preferred from the viewpoint of dielectric performance. These substrates can be used alone or in combination of two or more. The proportion of solids made up of the resin composition of this embodiment in the prepreg is preferably 30 to 80% by mass, more preferably 40 to 70% by mass. When the proportion of solids made up of the resin composition is 30% by mass or more, the prepreg tends to have better insulation reliability when used for electronic substrates, etc. When the proportion of solids is 80% by mass or less, the prepreg tends to have better mechanical properties such as rigidity when used for electronic substrates, etc.

[0054] [Laminate] The laminate of this embodiment includes the resin film and metal foil described above. The laminate of this embodiment can also include the cured prepreg and metal foil described above. The laminate of this embodiment can be produced, for example, by laminating a resin film made of the resin composition of this embodiment onto a substrate to form a resin layer and obtain a prepreg (step (a)), heating and pressing the resin layer to flatten it and obtain a cured prepreg (step (b)), and further forming a predetermined wiring layer made of metal foil on the resin layer (step (c)). In step (a), the method for laminating the resin film onto the substrate is not particularly limited. Examples include lamination methods using a multi-stage press, a vacuum press, a normal pressure laminator, and a laminator that heats and presses under vacuum. A method using a laminator that heats and presses under vacuum is preferred. This method using a laminator allows the resin to fill the spaces between the circuits without voids, even if the target electronic circuit board has a fine wiring circuit on its surface. Lamination may be performed batchwise or continuously using a roll or the like. Examples of substrates include, but are not limited to, glass epoxy substrates, metal substrates, polyester substrates, polyimide substrates, polyphenylene ether-based substrates, and fluororesin substrates. The surface of the substrate on which the resin layer is to be laminated may be pre-roughened, and the number of substrate layers is not limited. In step (b), the resin film laminated in step (a) and the substrate are heated and pressurized to be flattened. Conditions can be adjusted as desired depending on the type of substrate and the composition of the resin film, but preferred examples include a temperature of 100 to 300°C, a pressure of 0.2 to 20 MPa, and a time of 30 to 180 minutes. In step (c), a predetermined wiring layer made of metal foil is further formed on the resin layer produced by heating and pressurizing the resin film and substrate. The formation method is not particularly limited, and includes conventionally known methods, such as subtractive etching and semi-additive methods. The subtractive method is a method of forming the desired wiring by forming an etching resist layer on a metal layer in a shape corresponding to the desired pattern shape, and then performing a development process to dissolve and remove the metal layer in the areas where the resist has been removed using a chemical solution.The semi-additive process involves forming a metal coating on the surface of a resin layer by electroless plating, forming a plating resist layer on the metal coating in a shape corresponding to the desired pattern, and then forming a metal layer by electrolytic plating. The unnecessary electroless plating layer is then removed with a chemical solution or the like to form the desired wiring layer. Furthermore, holes such as via holes may be formed in the resin layer as needed. The method for forming the holes is not particularly limited, and any conventionally known method can be used. Examples of methods that can be used for forming the holes include NC drills, carbon dioxide lasers, UV lasers, YAG lasers, and plasma.

[0055] [Metal-Clad Laminate] The laminate of the present embodiment described above may be in the form of a plate or a flexible laminate. The laminate of the present embodiment may be a metal-clad laminate. The metal-clad laminate is obtained by laminating and curing the resin composition of the present embodiment or the prepreg of the present embodiment with a metal foil, with a portion of the metal foil removed. The metal-clad laminate preferably has a configuration in which a cured product of the prepreg (also referred to as a "cured product composite") and a metal foil are laminated and adhered together, and is suitable for use as a material for electronic circuit boards. Examples of metal foil include aluminum foil and copper foil, and among these, copper foil is preferred due to its low electrical resistance. The cured product of the prepreg to be combined with the metal foil may be one or more sheets, and depending on the application, metal foil is laminated on one or both sides of the cured product to form a laminate. Examples of methods for producing the metal-clad laminate include forming a prepreg composed of the resin composition of this embodiment and a substrate, overlaying the prepreg on a metal foil, and then curing the resin composition to obtain a metal-clad laminate in which the cured prepreg and the metal foil are laminated. One particularly preferred application of the metal-clad laminate is a printed wiring board. The printed wiring board is preferably prepared by removing at least a portion of the metal foil from the metal-clad laminate. The printed wiring board can be produced by a pressure-heat molding method using the prepreg of this embodiment described above. The substrate can be the same as that described above for the prepreg. By containing the resin composition of this embodiment, the printed wiring board has excellent strength and electrical properties (low dielectric constant and low dielectric tangent), and can suppress fluctuations in electrical properties due to environmental changes, as well as excellent insulation reliability and mechanical properties.

[0056] [Material for Electronic Circuit Board] The material for electronic circuit board of this embodiment includes a cured product of the resin composition of this embodiment. The material for electronic circuit board of this embodiment can be produced using the resin composition and / or varnish of this embodiment described above. The material for electronic circuit board of this embodiment includes at least one selected from the group consisting of a cured product of the resin composition described above, a resin film containing the resin composition of this embodiment or its cured product, and a prepreg which is a composite of a substrate and a resin composition. The material for electronic circuit board of this embodiment can be used as a printed wiring board having a resin-coated metal foil.

[0057] Hereinafter, the present embodiment will be described in detail with reference to specific examples and comparative examples, but the present invention is not limited to the following examples and comparative examples.

[0058] The methods for identifying the structure and measuring the physical properties of the conjugated diene copolymer or conjugated diene copolymer composition (component (I)) used in the following Examples and Comparative Examples are shown below.

[0059] [Methods for identifying the structure of conjugated diene copolymers and measuring their physical properties] ((1) Content of vinyl aromatic monomer units in conjugated diene copolymers) Using a conjugated diene copolymer before hydrogenation, the contents of the vinyl aromatic monomer units (a-1) having a radical reactive group and the vinyl aromatic monomer units (a-2) (excluding the units (a-1)) in the conjugated diene copolymer were measured using a nuclear magnetic resonance spectrometer (ECS-400, manufactured by JEOL).

[0060] (2) Amount of Vinyl Bonds in Conjugated Diene Copolymer The amount of vinyl bonds in a conjugated diene copolymer before hydrogenation was measured using an infrared spectrophotometer (FT / IR-230, manufactured by JASCO Corporation). The amount of vinyl bonds in the conjugated diene copolymer was calculated by the Hampton method. This value was taken as the content of units derived from 1,2-bonds and / or 3,4-bonds, when the total content of polymer block (B) and polymer block (C) in component (I) conjugated diene copolymer was taken as 100%.

[0061] (3) Number Average Molecular Weight of Conjugated Diene Copolymer) The molecular weight of the component (I) conjugated diene copolymer before modification and hydrogenation was measured by GPC [apparatus: LC-10 (Shimadzu Corporation), column: TSKgel GMHXL (4.6 mm × 30 cm)]. Tetrahydrofuran was used as the solvent. The measurement was carried out at a temperature of 35°C. The number average molecular weight was determined by using the molecular weight of the peak in the chromatogram and a calibration curve (prepared using the peak molecular weight of the standard polystyrene) obtained from the measurement of a commercially available standard polystyrene. When there are multiple peaks in the chromatogram, the molecular weight was determined as the average molecular weight from the molecular weight of each peak and the composition ratio of each peak (determined from the area ratio of each peak in the chromatogram).

[0062] (4) Hydrogenation Rate of Double Bonds of Conjugated Diene Monomer Units of Conjugated Diene Copolymer) The hydrogenation rate of double bonds of conjugated diene monomer units of the hydrogenated conjugated diene copolymer was measured using a nuclear magnetic resonance spectrometer (ECS-400, manufactured by JEOL).

[0063] (5) Maximum tan δ peak temperature Measurement was performed using an ARES-G2 rheometer, a viscoelasticity measuring device manufactured by TA Instruments Co., Ltd. Measurement temperature: Sweeping was performed in the range of −100 to 150° C. at a temperature rise rate of 5° C. / min, a frequency of 10 rad / sec, and a strain of 0.25%, and the maximum tan δ peak temperature of the conjugated diene copolymer (D) was measured.

[0064] (6) Residual Co Amount A sample was prepared by dissolving the conjugated diene copolymer before or after hydrogenation in a mixed solution of sulfuric acid and nitric acid using a microwave decomposition apparatus manufactured by Milestone General Co., Ltd., and the amount of residual Co was measured using an ICP optical emission spectrometer iCAP7400Duo manufactured by Thermo SCIENTIFIC.

[0065] (7) Residual Ti Amount A sample was prepared by dissolving the conjugated diene copolymer before or after hydrogenation in a mixed solution of sulfuric acid and nitric acid using a microwave decomposition apparatus manufactured by Milestone General Co., Ltd., and the residual Ti amount was measured using an ICP optical emission spectrometer iCAP7400Duo manufactured by Thermo SCIENTIFIC.

[0066] (Proportion of polymer block (C) in copolymer, proportion of unit (a-1) in random polymer block (C), proportion of unit (a-2) in random polymer block (C), proportion of unit (b) in random polymer block (C)) Using the conjugated diene copolymer after hydrogenation, the proportion of polymer block (C) in the conjugated diene copolymer, and the proportion of unit (a-1), proportion of unit (a-2), and proportion of unit (b) in the polymer block (C) were measured using a nuclear magnetic resonance spectrometer (ECS-400, manufactured by JEOL).

[0067] [Materials for Conjugated Diene Copolymer, Conjugated Diene Copolymer Composition, and Resin Composition] (Preparation of Hydrogenation Catalyst) The hydrogenation catalyst used in producing the conjugated diene copolymer in the Examples and Comparative Examples described below was prepared by the following method. A reaction vessel equipped with a stirrer was purged with nitrogen, and 1 liter of dried and purified cyclohexane was charged thereto. Next, 100 mmol of bis(η5-cyclopentadienyl)titanium dichloride was added. While thoroughly stirring, an n-hexane solution containing 200 mmol of trimethylaluminum was added, and the mixture was allowed to react at room temperature for approximately 3 days. This yielded a hydrogenation catalyst.

[0068] (Component (I): Conjugated diene copolymer and conjugated diene copolymer composition) Component (I): conjugated diene copolymer constituting the resin composition, and each of the conjugated diene copolymers constituting the conjugated diene copolymer composition combining two types of conjugated diene copolymers were prepared as follows. The structure and physical properties of each conjugated diene copolymer are shown in Tables 1, 2, 3, and 6 below. The constituent components and the amount of each component of each conjugated diene copolymer composition are shown in Tables 4, 5, and 7. In the tables, (A) represents a polymer block (A) mainly composed of vinyl aromatic monomer units. (B) represents a polymer block (B) mainly composed of conjugated diene monomer units. (C) represents a random polymer block (C) composed of vinyl aromatic monomer units and conjugated diene monomer units.

[0069] Example 1: Conjugated Diene Copolymer (D1) Batch polymerization was carried out using a tank-type reactor (internal volume 10 L) equipped with a stirrer and a jacket. First, a cyclohexane solution (concentration 20% by mass) containing 5 parts by mass of p-methylstyrene and 5 parts by mass of styrene was added. Next, 0.15 parts by mass of n-butyllithium per 100 parts by mass of total monomers and 0.5 mol of tetramethylethylenediamine (TMEDA) per 1 mole of n-butyllithium were added, and polymerization was carried out at 60°C for 10 minutes. Next, a cyclohexane solution (concentration 20% by mass) containing 30 parts by mass of butadiene was added, and polymerization was carried out at 60°C for 15 minutes. Next, a cyclohexane solution (concentration 20% by mass) containing 12.5 parts by mass of p-methylstyrene and 12.5 parts by mass of styrene was added, and polymerization was carried out at 60°C for 15 minutes. Next, a cyclohexane solution (concentration 20% by mass) containing 35 parts by mass of butadiene was added, and polymerization was carried out at 60°C for 15 minutes. Thereafter, methanol was added to terminate the polymerization reaction, thereby obtaining a conjugated diene copolymer. The conjugated diene copolymer obtained as described above contained 17.5% by mass of the unit (a-1), 17.5% by mass of the unit (a-2), 35% by mass in total of the units (a-1) and (a-2), and had a number average molecular weight of 5.0 × 10 ４ The molecular weight distribution was 1.10, and the content of units derived from 1,2-bonds and / or 3,4-bonds (vinyl bond content) was 50%. The hydrogenation catalyst prepared as described above was added to the resulting conjugated diene copolymer in an amount of 90 ppm (Ti) per 100 parts by mass of the block copolymer, and a hydrogenation reaction was carried out at a hydrogen pressure of 0.7 MPa and a temperature of 80°C for approximately 1.25 hours to obtain conjugated diene copolymer (D1). The hydrogenation rate was 97%. The maximum tan δ peak temperature was less than -30°C. Furthermore, the residual Co content was 0.1 ppm or less, and the residual Ti content was 500 ppm or less.

[0070] Example 2: Conjugated Diene Copolymer (D2) Batch polymerization was carried out using a tank-type reactor (internal volume 10 L) equipped with a stirrer and a jacket. First, a cyclohexane solution (concentration 20% by mass) containing 7.5 parts by mass of p-methylstyrene and 2.5 parts by mass of styrene was added. Next, 0.15 parts by mass of n-butyllithium per 100 parts by mass of total monomers and 0.5 mol of tetramethylethylenediamine (TMEDA) per 1 mole of n-butyllithium were added, and polymerization was carried out at 60°C for 10 minutes. Next, a cyclohexane solution (concentration 20% by mass) containing 30 parts by mass of butadiene was added, and polymerization was carried out at 60°C for 15 minutes. Next, a cyclohexane solution (concentration 20% by mass) containing 18.75 parts by mass of p-methylstyrene and 6.25 parts by mass of styrene was added, and polymerization was carried out at 60°C for 15 minutes. Next, a cyclohexane solution (concentration 20% by mass) containing 35 parts by mass of butadiene was added, and polymerization was carried out at 60°C for 15 minutes. Thereafter, methanol was added to terminate the polymerization reaction, thereby obtaining a conjugated diene copolymer (D2). The conjugated diene copolymer obtained as described above contained 26.25% by mass of the unit (a-1), 8.75% by mass of the unit (a-2), 35% by mass in total of the units (a-1) and (a-2), and had a number average molecular weight of 5.0 × 10 ４ The molecular weight distribution was 1.05, the content of units derived from 1,2-bonds and / or 3,4-bonds (vinyl bond content) was 50%, the hydrogenation rate was 0%, the maximum tan δ peak temperature was less than -30°C, the residual Co content was 0.1 ppm or less, and the residual Ti content was 500 ppm or less.

[0071] Example 3 Conjugated Diene Copolymer (D3) The hydrogenation catalyst prepared as described above was added to the conjugated diene copolymer (D2) obtained in Example 2 in an amount of 90 ppm (Ti) per 100 parts by mass of the conjugated diene copolymer, and a hydrogenation reaction was carried out at a hydrogen pressure of 0.7 MPa and a temperature of 80°C for about 0.5 hours to obtain a conjugated diene copolymer (D3). The conjugated diene copolymer (D3) obtained as described above contained 26.25% by mass of units (a-1), 8.75% by mass of units (a-2), a total of 35% by mass of units (a-1) and (a-2), and had a number average molecular weight of 5.0 × 10 ４The molecular weight distribution was 1.05, the content of units derived from 1,2-bonds and / or 3,4-bonds (vinyl bond content) was 50%, the hydrogenation rate was 55%, the maximum tan δ peak temperature was less than -30°C, the residual Co content was 0.1 ppm or less, and the residual Ti content was 500 ppm or less.

[0072] Example 4 Conjugated Diene Copolymer (D4) A conjugated diene copolymer (D4) was obtained by the same procedure as in Example 3, except that the hydrogenation reaction was carried out for 1.25 hours. The conjugated diene copolymer (D4) obtained as described above contained 26.25% by mass of units (a-1), 8.75% by mass of units (a-2), a total of 35% by mass of units (a-1) and (a-2), and had a number average molecular weight of 5.0 × 10 ４ The molecular weight distribution was 1.05, and the content of units derived from 1,2-bonds and / or 3,4-bonds (vinyl bond content) was 50%. The hydrogenation rate was 97%. The maximum tan δ peak temperature was less than -30°C. The residual Co content was 0.1 ppm or less, and the residual Ti content was 500 ppm or less.

[0073] Example 5: Conjugated Diene Copolymer (D5) Batch polymerization was carried out using a tank-type reactor (internal volume 10 L) equipped with a stirrer and a jacket. First, a cyclohexane solution (concentration 20% by mass) containing 9.5 parts by mass of p-methylstyrene and 0.5 parts by mass of styrene was added. Next, 0.15 parts by mass of n-butyllithium per 100 parts by mass of total monomers and 0.5 mol of tetramethylethylenediamine (TMEDA) per 1 mole of n-butyllithium were added, and polymerization was carried out at 60°C for 10 minutes. Next, a cyclohexane solution (concentration 20% by mass) containing 30 parts by mass of butadiene was added, and polymerization was carried out at 60°C for 15 minutes. Next, a cyclohexane solution (concentration 20% by mass) containing 23.75 parts by mass of p-methylstyrene and 1.25 parts by mass of styrene was added, and polymerization was carried out at 60°C for 15 minutes. Next, a cyclohexane solution (concentration 20% by mass) containing 35 parts by mass of butadiene was added, and polymerization was carried out at 60°C for 15 minutes. Thereafter, methanol was added to terminate the polymerization reaction, thereby obtaining a conjugated diene copolymer. The conjugated diene copolymer obtained as described above contained 33.25% by mass of the unit (a-1), 1.75% by mass of the unit (a-2), a total of 35% by mass of the units (a-1) and (a-2), and had a number average molecular weight of 5.1 × 10 ４ The molecular weight distribution was 1.04, the content of units derived from 1,2-bonds and / or 3,4-bonds (vinyl bond content) was 50%, the hydrogenation rate was 0%, the maximum tan δ peak temperature was less than -30°C, the residual Co content was 0.1 ppm or less, and the residual Ti content was 500 ppm or less.

[0074] Example 6: Conjugated diene copolymer (D6) The hydrogenation catalyst prepared as described above was added to the conjugated diene copolymer (D5) obtained in Example 5 in an amount of 90 ppm (Ti) per 100 parts by mass of the conjugated diene copolymer, and a hydrogenation reaction was carried out at a hydrogen pressure of 0.7 MPa and a temperature of 80°C for about 0.4 hours to obtain a conjugated diene copolymer (D6). The conjugated diene copolymer (D6) obtained as described above contained 26.25% by mass of units (a-1), 8.75% by mass of units (a-2), a total of 35% by mass of units (a-1) and (a-2), and had a number average molecular weight of 5.1 × 10 ４The molecular weight distribution was 1.05, the content of units derived from 1,2-bonds and / or 3,4-bonds (vinyl bond content) was 50%, the hydrogenation rate was 45%, the maximum tan δ peak temperature was less than -30°C, the residual Co content was 0.1 ppm or less, and the residual Ti content was 500 ppm or less.

[0075] Example 7 Conjugated Diene Copolymer (D7) A conjugated diene copolymer (D7) was obtained by the same procedure as in Example 6, except that the hydrogenation reaction was carried out for 0.6 hours. The conjugated diene copolymer (D7) obtained as described above contained 26.25% by mass of units (a-1), 8.75% by mass of units (a-2), 35% by mass in total of units (a-1) and (a-2), and had a number average molecular weight of 5.0 × 10 ４ The molecular weight distribution was 1.05, the content of units derived from 1,2-bonds and / or 3,4-bonds (vinyl bond content) was 50%, the hydrogenation rate was 55%, the maximum tan δ peak temperature was less than -30°C, the residual Co content was 0.1 ppm or less, and the residual Ti content was 500 ppm or less.

[0076] Example 8: Conjugated diene copolymer (D8) A conjugated diene copolymer (D8) was obtained by the same procedure as in Example 6, except that the hydrogenation reaction was carried out for 1.25 hours. The conjugated diene copolymer (D8) obtained as described above contained 26.25% by mass of units (a-1), 8.75% by mass of units (a-2), 35% by mass in total of units (a-1) and (a-2), and had a number average molecular weight of 5.1 × 10 ４ The molecular weight distribution was 1.05, and the content of units derived from 1,2-bonds and / or 3,4-bonds (vinyl bond content) was 50%. The hydrogenation rate was 97%. The maximum tan δ peak temperature was less than -30°C. The residual Co content was 0.1 ppm or less, and the residual Ti content was 500 ppm or less.

[0077] Example 9: Conjugated Diene Copolymer (D9) Batch polymerization was carried out using a tank-type reactor (internal volume 10 L) equipped with a stirrer and a jacket. First, a cyclohexane solution (concentration 20% by mass) containing 19 parts by mass of p-methylstyrene and 1 part by mass of styrene was added. Next, 0.15 parts by mass of n-butyllithium per 100 parts by mass of total monomers and 0.5 mol of tetramethylethylenediamine (TMEDA) per 1 mole of n-butyllithium were added, and polymerization was carried out at 60°C for 20 minutes. Next, a cyclohexane solution (concentration 20% by mass) containing 20 parts by mass of butadiene was added, and polymerization was carried out at 60°C for 15 minutes. Next, a cyclohexane solution (concentration 20% by mass) containing 33.25 parts by mass of p-methylstyrene and 1.75 parts by mass of styrene was added, and polymerization was carried out at 60°C for 25 minutes. Next, a cyclohexane solution (concentration 20% by mass) containing 25 parts by mass of butadiene was added, and polymerization was carried out at 60°C for 15 minutes. Thereafter, methanol was added to terminate the polymerization reaction, thereby obtaining a conjugated diene copolymer. The conjugated diene copolymer obtained as described above contained 52.25% by mass of the unit (a-1), 2.75% by mass of the unit (a-2), a total of 55% by mass of the units (a-1) and (a-2), and had a number average molecular weight of 5.1 × 10 ４ The molecular weight distribution was 1.06, and the content of units derived from 1,2-bonds and / or 3,4-bonds (vinyl bond content) was 50%. The hydrogenation catalyst prepared as described above was added to the resulting conjugated diene copolymer in an amount of 90 ppm (Ti) per 100 parts by mass of the conjugated diene copolymer, and a hydrogenation reaction was carried out at a hydrogen pressure of 0.7 MPa and a temperature of 80°C for approximately 1.25 hours to obtain conjugated diene copolymer (D9). The hydrogenation rate was 97%. The maximum tan δ peak temperature was less than -30°C. Furthermore, the residual Co content was 0.1 ppm or less, and the residual Ti content was 500 ppm or less.

[0078] Example 10: Conjugated Diene Copolymer (D10) Batch polymerization was carried out using a tank-type reactor (internal volume 10 L) equipped with a stirrer and a jacket. First, a cyclohexane solution (concentration 20% by mass) containing 9.5 parts by mass of p-methylstyrene and 0.5 parts by mass of styrene was added. Next, 0.15 parts by mass of n-butyllithium per 100 parts by mass of total monomers and 0.8 mol of tetramethylethylenediamine (TMEDA) per 1 mole of n-butyllithium were added, and polymerization was carried out at 60°C for 10 minutes. Next, a cyclohexane solution (concentration 20% by mass) containing 65 parts by mass of butadiene was added, and polymerization was carried out at 60°C for 40 minutes. Next, a cyclohexane solution (concentration 20% by mass) containing 23.75 parts by mass of p-methylstyrene and 1.25 parts by mass of styrene was added, and polymerization was carried out at 60°C for 15 minutes. Thereafter, methanol was added to terminate the polymerization reaction, and a conjugated diene copolymer was obtained. The conjugated diene copolymer obtained as described above contained 33.25% by mass of units (a-1), 1.75% by mass of units (a-2), a total of 35% by mass of units (a-1) and (a-2), and had a number average molecular weight of 5.1 × 10 ４ The molecular weight distribution was 1.06, and the content of units derived from 1,2-bonds and / or 3,4-bonds (vinyl bond content) was 70%. The hydrogenation catalyst prepared as described above was added to the resulting conjugated diene copolymer in an amount of 90 ppm (Ti) per 100 parts by mass of the conjugated diene copolymer, and a hydrogenation reaction was carried out at a hydrogen pressure of 0.7 MPa and a temperature of 80°C for approximately 1.25 hours to obtain a conjugated diene copolymer (D10). The hydrogenation rate was 97%. The maximum tan δ peak temperature was less than -30°C. Furthermore, the residual Co content was 0.1 ppm or less, and the residual Ti content was 500 ppm or less.

[0079] Example 11: Conjugated Diene Copolymer (D11) Batch polymerization was carried out using a tank-type reactor (internal volume 10 L) equipped with a stirrer and a jacket. First, a cyclohexane solution (concentration 20% by mass) containing 10 parts by mass of p-methylstyrene was added. Next, 0.15 parts by mass of n-butyllithium per 100 parts by mass of total monomers and 0.6 mol of tetramethylethylenediamine (TMEDA) per 1 mole of n-butyllithium were added, and polymerization was carried out at 60°C for 10 minutes. Next, a cyclohexane solution (concentration 20% by mass) containing 30 parts by mass of butadiene was added, and polymerization was carried out at 60°C for 15 minutes. Next, a cyclohexane solution (concentration 20% by mass) containing 25 parts by mass of p-methylstyrene was added, and polymerization was carried out at 60°C for 15 minutes. Next, a cyclohexane solution (concentration 20% by mass) containing 35 parts by mass of butadiene was added, and polymerization was carried out at 60°C for 15 minutes. Thereafter, methanol was added to terminate the polymerization reaction, and a conjugated diene copolymer was obtained. The conjugated diene copolymer obtained as described above contained 35% by mass of units (a-1), 0% by mass of units (a-2), the total of units (a-1) and (a-2) was 35% by mass, and the number average molecular weight was 5.0 × 10 ４ The molecular weight distribution was 1.08, and the content of units derived from 1,2-bonds and / or 3,4-bonds (vinyl bond content) was 60%. The hydrogenation catalyst prepared as described above was added to the resulting conjugated diene copolymer in an amount of 90 ppm (Ti) per 100 parts by mass of the conjugated diene copolymer, and a hydrogenation reaction was carried out at a hydrogen pressure of 0.7 MPa and a temperature of 80°C for approximately 1.25 hours to obtain a conjugated diene copolymer (D12). The hydrogenation rate was 97%. The maximum tan δ peak temperature was less than -30°C. Furthermore, the residual Co content was 0.1 ppm or less, and the residual Ti content was 500 ppm or less.

[0080] Example 12: Conjugated Diene Copolymer (D12) Batch polymerization was carried out using a tank-type reactor (internal volume 10 L) equipped with a stirrer and a jacket. First, a cyclohexane solution (concentration 20% by mass) containing 9.5 parts by mass of p-methylstyrene and 0.5 parts by mass of styrene was added. Next, 0.075 parts by mass of n-butyllithium per 100 parts by mass of total monomers and 0.6 mol of tetramethylethylenediamine (TMEDA) per 1 mole of n-butyllithium were added, and polymerization was carried out at 60°C for 10 minutes. Next, a cyclohexane solution (concentration 20% by mass) containing 30 parts by mass of butadiene was added, and polymerization was carried out at 60°C for 15 minutes. Next, a cyclohexane solution (concentration 20% by mass) containing 23.75 parts by mass of p-methylstyrene and 1.25 parts by mass of styrene was added, and polymerization was carried out at 60°C for 15 minutes. Next, a cyclohexane solution (concentration 20% by mass) containing 35 parts by mass of butadiene was added, and polymerization was carried out at 60°C for 15 minutes. Thereafter, methanol was added to terminate the polymerization reaction, thereby obtaining a conjugated diene copolymer. The conjugated diene copolymer obtained as described above contained 35% by mass of the unit (a-1), 0% by mass of the unit (a-2), a total of 35% by mass of the units (a-1) and (a-2), and had a number average molecular weight of 5.0 × 10 ４ The molecular weight distribution was 1.08, and the content of units derived from 1,2-bonds and / or 3,4-bonds (vinyl bond content) was 50%. The hydrogenation catalyst prepared as described above was added to the resulting conjugated diene copolymer in an amount of 90 ppm (Ti) per 100 parts by mass of the conjugated diene copolymer, and a hydrogenation reaction was carried out at a hydrogen pressure of 0.7 MPa and a temperature of 80°C for approximately 1.25 hours to obtain a conjugated diene copolymer (D12). The hydrogenation rate was 97%. The maximum tan δ peak temperature was less than -30°C. Furthermore, the residual Co content was 0.1 ppm or less, and the residual Ti content was 500 ppm or less.

[0081] Example 13: Conjugated diene copolymer (D13) Batch polymerization was carried out using a tank-type reactor (internal volume 10 L) equipped with a stirrer and a jacket. First, a cyclohexane solution (concentration 20% by mass) containing 33.25 parts by mass of p-methylstyrene and 1.75 parts by mass of styrene was added. Next, 0.15 parts by mass of n-butyllithium per 100 parts by mass of total monomers and 0.6 mol of tetramethylethylenediamine (TMEDA) per 1 mole of n-butyllithium were added, and polymerization was carried out at 60°C for 10 minutes. Next, a cyclohexane solution (concentration 20% by mass) containing 15 parts by mass of butadiene was added, and polymerization was carried out at 60°C for 15 minutes. Next, a cyclohexane solution (concentration 20% by mass) containing 26.125 parts by mass of p-methylstyrene and 1.375 parts by mass of styrene was added, and polymerization was carried out at 60°C for 15 minutes. Next, a cyclohexane solution (concentration 20% by mass) containing 7.125 parts by mass of p-methylstyrene, 0.375 parts by mass of styrene, and 15 parts by mass of butadiene was added, and polymerization was carried out at 60°C for 15 minutes. Methanol was then added to terminate the polymerization reaction, yielding a conjugated diene copolymer. The conjugated diene copolymer obtained as described above contained 66.5% by mass of units (a-1), 3.5% by mass of units (a-2), a total of 70% by mass of units (a-1) and (a-2), and had a number average molecular weight of 5.1 x 10 ４ The molecular weight distribution was 1.08, and the content of units derived from 1,2-bonds and / or 3,4-bonds (vinyl bond content) was 50%. The hydrogenation catalyst prepared as described above was added to the resulting conjugated diene copolymer in an amount of 90 ppm (Ti) per 100 parts by mass of the conjugated diene copolymer, and a hydrogenation reaction was carried out at a hydrogen pressure of 0.7 MPa and a temperature of 80°C for approximately 1.25 hours to obtain a conjugated diene copolymer (D13). The hydrogenation rate was 97%. The maximum tan δ peak temperature was -25°C. The residual Co content was 0.1 ppm or less, and the residual Ti content was 500 ppm or less.

[0082] Example 14: Conjugated diene copolymer (D14) Batch polymerization was carried out using a tank-type reactor (internal volume 10 L) equipped with a stirrer and a jacket. First, a cyclohexane solution (concentration 20% by mass) containing 9.5 parts by mass of p-methylstyrene and 0.5 parts by mass of styrene was added. Next, 0.15 parts by mass of n-butyllithium per 100 parts by mass of total monomers and 0.6 mol of tetramethylethylenediamine (TMEDA) per 1 mole of n-butyllithium were added, and polymerization was carried out at 60°C for 10 minutes. Next, a cyclohexane solution (concentration 20% by mass) containing 30 parts by mass of butadiene was added, and polymerization was carried out at 60°C for 15 minutes. Next, a cyclohexane solution (concentration 20% by mass) containing 23.75 parts by mass of p-methylstyrene and 1.25 parts by mass of styrene was added, and polymerization was carried out at 60°C for 15 minutes. Next, a cyclohexane solution (concentration 20% by mass) containing 35 parts by mass of butadiene was added, and polymerization was carried out at 60°C for 15 minutes. Thereafter, methanol was added to terminate the polymerization reaction, thereby obtaining a conjugated diene copolymer. The conjugated diene copolymer obtained as described above had 33.25% by mass of units (a-1), 1.75% by mass of units (a-2), a total of 35% by mass of units (a-1) and (a-2), and a number average molecular weight of 5.1 × 10 ４ The molecular weight distribution was 1.07, and the content of units derived from 1,2-bonds and / or 3,4-bonds (vinyl bond content) was 60%. The hydrogenation catalyst prepared as described above was added to the resulting conjugated diene copolymer in an amount of 90 ppm (Ti) per 100 parts by mass of the conjugated diene copolymer, and a hydrogenation reaction was carried out at a hydrogen pressure of 0.7 MPa and a temperature of 80°C for approximately 1.25 hours to obtain conjugated diene copolymer (D14). The hydrogenation rate was 97%. The maximum tan δ peak temperature was less than -30°C. The residual Co content was 1.0 ppm, and the residual Ti content was 500 ppm or less.

[0083] Example 15: Conjugated diene copolymer (D15) Batch polymerization was carried out using a tank-type reactor (internal volume 10 L) equipped with a stirrer and a jacket. First, a cyclohexane solution (concentration 20% by mass) containing 9.5 parts by mass of p-methylstyrene and 0.5 parts by mass of styrene was added. Next, 0.15 parts by mass of n-butyllithium per 100 parts by mass of total monomers and 0.6 mol of tetramethylethylenediamine (TMEDA) per 1 mole of n-butyllithium were added, and polymerization was carried out at 60°C for 10 minutes. Next, a cyclohexane solution (concentration 20% by mass) containing 30 parts by mass of butadiene was added, and polymerization was carried out at 60°C for 15 minutes. Next, a cyclohexane solution (concentration 20% by mass) containing 23.75 parts by mass of p-methylstyrene and 1.25 parts by mass of styrene was added, and polymerization was carried out at 60°C for 15 minutes. Next, a cyclohexane solution (concentration 20% by mass) containing 35 parts by mass of butadiene was added, and polymerization was carried out at 60°C for 15 minutes. Thereafter, methanol was added to terminate the polymerization reaction, thereby obtaining a conjugated diene copolymer. The conjugated diene copolymer obtained as described above had 33.25% by mass of units (a-1), 1.75% by mass of units (a-2), a total of 35% by mass of units (a-1) and (a-2), and a number average molecular weight of 5.1 × 10 ４ The molecular weight distribution was 1.07, and the content of units derived from 1,2-bonds and / or 3,4-bonds (vinyl bond content) was 60%. The hydrogenation catalyst prepared as described above was added to the resulting conjugated diene copolymer in an amount of 1,000 ppm (based on Ti) per 100 parts by mass of the conjugated diene copolymer, and a hydrogenation reaction was carried out at a hydrogen pressure of 0.7 MPa and a temperature of 80°C for approximately 1.25 hours to obtain conjugated diene copolymer (D16). The hydrogenation rate was 97%. The maximum tan δ peak temperature was less than -30°C. Furthermore, the residual Co content was 0.1 ppm or less, and the residual Ti content was 1,000 ppm.

[0084] Example 16: Conjugated diene copolymer (D16) Batch polymerization was carried out using a tank-type reactor (internal volume 10 L) equipped with a stirrer and a jacket. First, a cyclohexane solution (concentration 20% by mass) containing 33.25 parts by mass of p-methylstyrene and 1.75 parts by mass of styrene was added. Next, 0.15 parts by mass of n-butyllithium per 100 parts by mass of total monomers and 0.6 mol of tetramethylethylenediamine (TMEDA) per 1 mole of n-butyllithium were added, and polymerization was carried out at 60°C for 10 minutes. Next, a cyclohexane solution (concentration 20% by mass) containing 15 parts by mass of butadiene was added, and polymerization was carried out at 60°C for 15 minutes. Next, a cyclohexane solution (concentration 20% by mass) containing 26.125 parts by mass of p-methylstyrene and 1.375 parts by mass of styrene was added, and polymerization was carried out at 60°C for 15 minutes. Next, a cyclohexane solution (concentration 20% by mass) containing 7.125 parts by mass of p-methylstyrene, 0.375 parts by mass of styrene, and 15 parts by mass of butadiene was added, and polymerization was carried out at 60°C for 15 minutes. Methanol was then added to terminate the polymerization reaction, yielding a conjugated diene copolymer. The conjugated diene copolymer obtained as described above contained 66.5% by mass of units (a-1), 3.5% by mass of units (a-2), a total of 70% by mass of units (a-1) and (a-2), and had a number average molecular weight of 5.1 x 10 ４ The molecular weight distribution was 1.08, and the content of units derived from 1,2-bonds and / or 3,4-bonds (vinyl bond content) was 50%. The hydrogenation catalyst prepared as described above was added to the resulting conjugated diene copolymer in an amount of 1,000 ppm (based on Ti) per 100 parts by mass of the conjugated diene copolymer, and a hydrogenation reaction was carried out at a hydrogen pressure of 0.7 MPa and a temperature of 80°C for approximately 1.25 hours to obtain conjugated diene copolymer (D16). The hydrogenation rate was 97%. The maximum tan δ peak temperature was -25°C. The residual Co content was 1.0 ppm, and the residual Ti content was 1,000 ppm.

[0085] Example 50-1: Conjugated diene copolymer (D20) for Example 50 described below As described below, for the conjugated diene copolymer composition (X24) of Example 50, the conjugated diene copolymer (D20) and the conjugated diene copolymer (E14) were prepared in one reactor, and the conjugated diene copolymer (X24) composed of these was obtained. The hydrogenation rate of the conjugated diene copolymer (D20) was 97%. The maximum tan δ peak temperature was less than -30°C. The residual Co amount was 0.1 ppm or less, and the residual Ti amount was 500 ppm or less.

[0086] <Production Example 17: Conjugated diene copolymer (E1)> Batch polymerization was carried out using a tank-type reactor (internal volume 10 L) equipped with a stirrer and a jacket. First, a cyclohexane solution (concentration 20% by mass) containing 17.5 parts by mass of p-methylstyrene and 17.5 parts by mass of styrene was added. Next, 0.66 parts by mass of n-butyllithium per 100 parts by mass of total monomers and 0.5 mol of tetramethylethylenediamine (TMEDA) per 1 mole of n-butyllithium were added, and polymerization was carried out at 60 ° C. for 20 minutes. Next, a cyclohexane solution (concentration 20% by mass) containing 65 parts by mass of butadiene was added, and polymerization was carried out at 60 ° C. for 40 minutes. Thereafter, methanol was added to terminate the polymerization reaction, and a conjugated diene copolymer was obtained. The conjugated diene copolymer obtained as described above contained 17.5% by mass of units (a-1), 17.5% by mass of units (a-2), a total of 35% by mass of units (a-1) and (a-2), and had a number average molecular weight of 1.0 × 10 ４ The molecular weight distribution was 1.06, and the content of units derived from 1,2-bonds and / or 3,4-bonds (vinyl bond content) was 50%. The hydrogenation catalyst prepared as described above was added to the resulting conjugated diene copolymer in an amount of 90 ppm (Ti standard) per 100 parts by mass of the conjugated diene copolymer, and a hydrogenation reaction was carried out at a hydrogen pressure of 0.7 MPa and a temperature of 80°C for approximately 1.25 hours to obtain a conjugated diene copolymer (E1). The hydrogenation rate was 97%.

[0087] <Production Example 18: Conjugated diene copolymer (E2)> Batch polymerization was carried out using a tank-type reactor (internal volume 10 L) equipped with a stirrer and a jacket. First, a cyclohexane solution (concentration 20% by mass) containing 26.25 parts by mass of p-methylstyrene and 8.75 parts by mass of styrene was added. Next, 0.66 parts by mass of n-butyllithium per 100 parts by mass of the total monomers and 0.5 mol of tetramethylethylenediamine (TMEDA) per 1 mole of n-butyllithium were added, and polymerization was carried out at 60 ° C. for 20 minutes. Next, a cyclohexane solution (concentration 20% by mass) containing 65 parts by mass of butadiene was added, and polymerization was carried out at 60 ° C. for 40 minutes. Thereafter, methanol was added to terminate the polymerization reaction, and a conjugated diene copolymer (E2) was obtained. The conjugated diene copolymer (E2) obtained as described above contained 26.25% by mass of units (a-1), 8.75% by mass of units (a-2), the total of units (a-1) and (a-2) was 35% by mass, and the number average molecular weight was 1.0 × 10 ４ The molecular weight distribution was 1.06, the content of units derived from 1,2-bonds and / or 3,4-bonds (vinyl bond content) was 50%, and the hydrogenation rate was 0%.

[0088] Production Example 19: Conjugated diene copolymer (E3) The hydrogenation catalyst prepared as described above was added to the conjugated diene copolymer (E2) obtained in Production Example 18 in an amount of 90 ppm (Ti) per 100 parts by mass of the conjugated diene copolymer, and a hydrogenation reaction was carried out at a hydrogen pressure of 0.7 MPa and a temperature of 80°C for approximately 0.6 hours to obtain a conjugated diene copolymer (E3). The conjugated diene copolymer (E3) obtained as described above contained 26.25% by mass of units (a-1), 8.75% by mass of units (a-2), a total of 35% by mass of units (a-1) and (a-2), and had a number average molecular weight of 1.0 × 10 ４ The molecular weight distribution was 1.06, the content of units derived from 1,2-bonds and / or 3,4-bonds (vinyl bond content) was 50%, and the hydrogenation rate was 55%.

[0089] Production Example 20: Conjugated diene copolymer (E4) A conjugated diene copolymer (E4) was obtained by the same procedure as in Production Example 19, except that the hydrogenation reaction was carried out for 1.25 hours. The conjugated diene copolymer (E4) obtained as described above contained 26.25% by mass of units (a-1), 8.75% by mass of units (a-2), 35% by mass in total of units (a-1) and (a-2), and had a number average molecular weight of 1.0 × 10 ４ The molecular weight distribution was 1.06, the content of units derived from 1,2-bonds and / or 3,4-bonds (vinyl bond content) was 50%, and the hydrogenation rate was 97%.

[0090] <Production Example 21: Conjugated diene copolymer (E5)> Batch polymerization was carried out using a tank-type reactor (internal volume 10 L) equipped with a stirrer and a jacket. First, a cyclohexane solution (concentration 20% by mass) containing 33.25 parts by mass of p-methylstyrene and 1.75 parts by mass of styrene was added. Next, 0.66 parts by mass of n-butyllithium per 100 parts by mass of the total monomers and 0.5 mol of tetramethylethylenediamine (TMEDA) per 1 mole of n-butyllithium were added, and polymerization was carried out at 60 ° C. for 20 minutes. Next, a cyclohexane solution (concentration 20% by mass) containing 65 parts by mass of butadiene was added, and polymerization was carried out at 60 ° C. for 40 minutes. Thereafter, methanol was added to terminate the polymerization reaction, and a conjugated diene copolymer (E5) was obtained. The conjugated diene copolymer (E5) obtained as described above contained 33.25% by mass of units (a-1), 1.75% by mass of units (a-2), a total of 35% by mass of units (a-1) and (a-2), and had a number average molecular weight of 1.0 × 10 ４ The molecular weight distribution was 1.06, the content of units derived from 1,2-bonds and / or 3,4-bonds (vinyl bond content) was 50%, and the hydrogenation rate was 0%.

[0091] Production Example 22: Conjugated diene copolymer (E6) The hydrogenation catalyst prepared as described above was added to the conjugated diene copolymer E5 obtained in Production Example 21 in an amount of 90 ppm (Ti) per 100 parts by mass of the block copolymer, and a hydrogenation reaction was carried out at a hydrogen pressure of 0.7 MPa and a temperature of 80°C for approximately 0.4 hours to obtain a conjugated diene copolymer (E6). The conjugated diene copolymer (E6) obtained as described above contained 33.25% by mass of units (a-1), 1.75% by mass of units (a-2), a total of 35% by mass of units (a-1) and (a-2), and had a number average molecular weight of 1.0 × 10 ４ The molecular weight distribution was 1.06, the content of units derived from 1,2-bonds and / or 3,4-bonds (vinyl bond content) was 50%, and the hydrogenation rate was 45%.

[0092] Production Example 23: Conjugated diene copolymer (E7) A conjugated diene copolymer (E7) was obtained by the same procedure as in Production Example 22, except that the hydrogenation reaction was carried out for 0.6 hours. The conjugated diene copolymer (E7) obtained as described above contained 33.25% by mass of units (a-1), 1.75% by mass of units (a-2), a total of 35% by mass of units (a-1) and (a-2), and had a number average molecular weight of 1.0 × 10 ４ The molecular weight distribution was 1.06, the content of units derived from 1,2-bonds and / or 3,4-bonds (vinyl bond content) was 50%, and the hydrogenation rate was 55%.

[0093] Production Example 24: Conjugated diene copolymer (E8) A conjugated diene copolymer (E8) was obtained by the same procedure as in Production Example 22, except that the hydrogenation reaction was carried out for 1.25 hours. The conjugated diene copolymer (E8) obtained as described above contained 33.25% by mass of units (a-1), 1.75% by mass of units (a-2), a total of 35% by mass of units (a-1) and (a-2), and had a number average molecular weight of 1.0 × 10 ４ The molecular weight distribution was 1.06, the content of units derived from 1,2-bonds and / or 3,4-bonds (vinyl bond content) was 50%, and the hydrogenation rate was 97%.

[0094] <Production Example 25: Conjugated diene copolymer (E9)> Batch polymerization was carried out using a tank-type reactor (internal volume 10 L) equipped with a stirrer and a jacket. First, a cyclohexane solution (concentration 20% by mass) containing 52.25 parts by mass of p-methylstyrene and 2.75 parts by mass of styrene was added. Next, 0.66 parts by mass of n-butyllithium per 100 parts by mass of total monomers and 0.5 mol of tetramethylethylenediamine (TMEDA) per 1 mole of n-butyllithium were added, and polymerization was carried out at 60 ° C. for 30 minutes. Next, a cyclohexane solution (concentration 20% by mass) containing 45 parts by mass of butadiene was added, and polymerization was carried out at 60 ° C. for 30 minutes. Thereafter, methanol was added to terminate the polymerization reaction, and a conjugated diene copolymer was obtained. The conjugated diene copolymer obtained as described above contained 52.25% by mass of units (a-1), 2.75% by mass of units (a-2), a total of 55% by mass of units (a-1) and (a-2), and had a number average molecular weight of 1.0 × 10 ４ The molecular weight distribution was 1.05, and the content of units derived from 1,2-bonds and / or 3,4-bonds (vinyl bond content) was 50%. The hydrogenation catalyst prepared as described above was added to the resulting conjugated diene copolymer in an amount of 90 ppm (Ti standard) per 100 parts by mass of the block copolymer, and a hydrogenation reaction was carried out at a hydrogen pressure of 0.7 MPa and a temperature of 80°C for approximately 1.25 hours to obtain conjugated diene copolymer (E9). The hydrogenation rate was 97%.

[0095] Production Example 26: Conjugated Diene Copolymer (E10) Batch polymerization was carried out using a tank-type reactor (internal volume 10 L) equipped with a stirrer and a jacket. First, a cyclohexane solution (concentration 20% by mass) containing 19.0 parts by mass of p-methylstyrene and 1.0 part by mass of styrene was added. Next, 0.66 parts by mass of n-butyllithium relative to 100 parts by mass of total monomers and 0.5 mol of tetramethylethylenediamine (TMEDA) relative to 1 mole of n-butyllithium were added, and polymerization was carried out at 60°C for 15 minutes. Next, a cyclohexane solution (concentration 20% by mass) containing 38 parts by mass of p-methylstyrene, 2 parts by mass of styrene, and 40 parts by mass of butadiene was added, and polymerization was carried out at 60°C for 45 minutes. Thereafter, methanol was added to terminate the polymerization reaction, and a conjugated diene copolymer was obtained. The conjugated diene copolymer obtained as described above contained 57.0% by mass of units (a-1), 3.0% by mass of units (a-2), a total of 60% by mass of units (a-1) and (a-2), and had a number average molecular weight of 1.0 × 10 ４ The molecular weight distribution was 1.05, and the content of units derived from 1,2-bonds and / or 3,4-bonds (vinyl bond content) was 50%. The hydrogenation catalyst prepared as described above was added to the resulting conjugated diene copolymer in an amount of 90 ppm (Ti) per 100 parts by mass of the conjugated diene copolymer, and a hydrogenation reaction was carried out at a hydrogen pressure of 0.7 MPa and a temperature of 80°C for approximately 1.25 hours to obtain a conjugated diene copolymer (E10). The hydrogenation rate was 97%.

[0096] Production Example 27: Conjugated diene copolymer (E11) Batch polymerization was carried out using a tank-type reactor (internal volume 10 L) equipped with a stirrer and a jacket. First, a cyclohexane solution (concentration 20% by mass) containing 47.5 parts by mass of p-methylstyrene, 2.5 parts by mass of styrene, and 50 parts by mass of butadiene was added. Next, 0.66 parts by mass of n-butyllithium relative to 100 parts by mass of the total monomers and 0.5 mol of tetramethylethylenediamine (TMEDA) relative to 1 mole of n-butyllithium were added, and polymerization was carried out at 60°C for 60 minutes. Thereafter, methanol was added to terminate the polymerization reaction, yielding a conjugated diene copolymer. The conjugated diene copolymer obtained as described above had 47.5% by mass of units (a-1), 2.5% by mass of units (a-2), a total of 50% by mass of units (a-1) and (a-2), and a number average molecular weight of 1.0 x 10 ４ The molecular weight distribution was 1.08, and the content of units derived from 1,2-bonds and / or 3,4-bonds (vinyl bond content) was 50%. The hydrogenation catalyst prepared as described above was added to the resulting conjugated diene copolymer in an amount of 90 ppm (Ti) per 100 parts by mass of the conjugated diene copolymer, and a hydrogenation reaction was carried out at a hydrogen pressure of 0.7 MPa and a temperature of 80°C for approximately 1.25 hours to obtain a conjugated diene copolymer (E11). The hydrogenation rate was 97%.

[0097] Production Example 28: Conjugated diene copolymer (E12) Batch polymerization was carried out using a tank-type reactor (internal volume 10 L) equipped with a stirrer and a jacket. First, a cyclohexane solution (concentration 20% by mass) containing 35 parts by mass of styrene was added. Next, 0.66 parts by mass of n-butyllithium per 100 parts by mass of total monomers and 0.5 mol of tetramethylethylenediamine (TMEDA) per 1 mole of n-butyllithium were added, and polymerization was carried out at 60°C for 20 minutes. Next, a cyclohexane solution (concentration 20% by mass) containing 65 parts by mass of butadiene was added, and polymerization was carried out at 60°C for 40 minutes. Thereafter, methanol was added to terminate the polymerization reaction, yielding a conjugated diene copolymer. The conjugated diene copolymer obtained as described above had 0% by mass of units (a-1), 35% by mass of units (a-2), a total of 35% by mass of units (a-1) and (a-2), and a number average molecular weight of 1.0 x 10４ The molecular weight distribution was 1.06, and the content of units derived from 1,2-bonds and / or 3,4-bonds (vinyl bond content) was 50%. The hydrogenation catalyst prepared as described above was added to the resulting conjugated diene copolymer in an amount of 90 ppm (Ti) per 100 parts by mass of the conjugated diene copolymer, and a hydrogenation reaction was carried out at a hydrogen pressure of 0.7 MPa and a temperature of 80°C for approximately 1.25 hours to obtain a conjugated diene copolymer (E12). The hydrogenation rate was 97%.

[0098] Production Example 29: Conjugated diene copolymer (E13) Batch polymerization was carried out using a tank-type reactor (internal volume 10 L) equipped with a stirrer and a jacket. First, a cyclohexane solution (concentration 20% by mass) containing 95 parts by mass of p-methylstyrene and 5 parts by mass of styrene was added. Next, 0.66 parts by mass of n-butyllithium per 100 parts by mass of the total monomers and 0.5 mol of tetramethylethylenediamine (TMEDA) per 1 mole of n-butyllithium were added, and polymerization was carried out at 60°C for 60 minutes. Thereafter, methanol was added to terminate the polymerization reaction, thereby obtaining a conjugated diene copolymer. The conjugated diene copolymer obtained as described above had 0% by mass of units (a-1), 35% by mass of units (a-2), a total of 35% by mass of units (a-1) and (a-2), and a number average molecular weight of 1.0 x 10 ４ The molecular weight distribution was 1.06, and the content of units derived from 1,2-bonds and / or 3,4-bonds (vinyl bond content) was 50%. The hydrogenation catalyst prepared as described above was added to the resulting conjugated diene copolymer in an amount of 90 ppm (Ti) per 100 parts by mass of the conjugated diene copolymer, and a hydrogenation reaction was carried out at a hydrogen pressure of 0.7 MPa and a temperature of 80°C for approximately 1.25 hours to obtain a conjugated diene copolymer (E13). The hydrogenation rate was 97%.

[0099] <Production Example 50-2: Conjugated diene copolymer (E14) for Example 50 described below> As described below, for the conjugated diene copolymer composition (X24) of Example 50, the conjugated diene copolymer (D20) and the conjugated diene copolymer (E14) were prepared in one reactor, and the conjugated diene copolymer (X24) composed of these was obtained. The hydrogenation rate of the conjugated diene copolymer (E14) was 97%.

[0100] Comparative Example 1: Conjugated Diene Copolymer (D17) Batch polymerization was carried out using a tank-type reactor (internal volume 10 L) equipped with a stirrer and a jacket. First, a cyclohexane solution (concentration 20% by mass) containing 9.5 parts by mass of p-methylstyrene and 0.5 parts by mass of styrene was added. Next, 0.05 parts by mass of n-butyllithium relative to 100 parts by mass of total monomers and 0.6 mol of tetramethylethylenediamine (TMEDA) relative to 1 mole of n-butyllithium were added, and polymerization was carried out at 60°C for 10 minutes. Next, a cyclohexane solution (concentration 20% by mass) containing 30 parts by mass of butadiene was added, and polymerization was carried out at 60°C for 15 minutes. Next, a cyclohexane solution (concentration 20% by mass) containing 23.75 parts by mass of p-methylstyrene and 1.25 parts by mass of styrene was added, and polymerization was carried out at 60°C for 15 minutes. Next, a cyclohexane solution (concentration: 20% by mass) containing 35 parts by mass of butadiene was added, and polymerization was carried out at 60°C for 15 minutes. Thereafter, methanol was added to terminate the polymerization reaction, thereby obtaining a conjugated diene copolymer. The conjugated diene copolymer obtained as described above contained 33.25% by mass of units (a-1), 1.75% by mass of units (a-2), a total of 35% by mass of units (a-1) and (a-2), and had a number average molecular weight of 20.0 × 10 ４ The molecular weight distribution was 1.06, and the content of units derived from 1,2-bonds and / or 3,4-bonds (vinyl bond content) was 59%. The hydrogenation catalyst prepared as described above was added to the resulting conjugated diene copolymer in an amount of 90 ppm (Ti) per 100 parts by mass of the conjugated diene copolymer, and a hydrogenation reaction was carried out at a hydrogen pressure of 0.7 MPa and a temperature of 80°C for approximately 1.25 hours to obtain a conjugated diene copolymer (D17). The hydrogenation rate was 97%. The maximum tan δ peak temperature was less than -30°C. Furthermore, the residual Co content was 0.1 ppm or less, and the residual Ti content was 500 ppm or less.

[0101] Comparative Example 2: Conjugated Diene Copolymer (D18) Batch polymerization was carried out using a tank-type reactor (internal volume 10 L) equipped with a stirrer and a jacket. First, a cyclohexane solution (concentration 20% by mass) containing 38 parts by mass of p-methylstyrene and 2.0 parts by mass of styrene was added. Next, 0.15 parts by mass of n-butyllithium per 100 parts by mass of total monomers and 0.6 mol of tetramethylethylenediamine (TMEDA) per 1 mole of n-butyllithium were added, and polymerization was carried out at 60°C for 25 minutes. Next, a cyclohexane solution (concentration 20% by mass) containing 10 parts by mass of butadiene was added, and polymerization was carried out at 60°C for 10 minutes. Next, a cyclohexane solution (concentration 20% by mass) containing 33.25 parts by mass of p-methylstyrene and 1.75 parts by mass of styrene was added, and polymerization was carried out at 60°C for 25 minutes. Next, a cyclohexane solution (concentration 20% by mass) containing 4.75 parts by mass of p-methylstyrene, 0.25 parts by mass of styrene, and 10 parts by mass of butadiene was added, and polymerization was carried out at 60°C for 10 minutes. Thereafter, methanol was added to terminate the polymerization reaction, thereby obtaining a conjugated diene copolymer. The conjugated diene copolymer obtained as described above contained 76% by mass of units (a-1), 4.0% by mass of units (a-2), a total of 80% by mass of units (a-1) and (a-2), and had a number average molecular weight of 5.1 × 10 ４ The molecular weight distribution was 1.07, and the content of units derived from 1,2-bonds and / or 3,4-bonds (vinyl bond content) was 60%. The hydrogenation catalyst prepared as described above was added to the resulting conjugated diene copolymer in an amount of 90 ppm (Ti) per 100 parts by mass of the conjugated diene copolymer, and a hydrogenation reaction was carried out at a hydrogen pressure of 0.7 MPa and a temperature of 80°C for approximately 1.25 hours to obtain conjugated diene copolymer (D14). The hydrogenation rate was 97%. The maximum tan δ peak temperature was -25°C. The residual Co content was 0.1 ppm or less, and the residual Ti content was 500 ppm or less.

[0102] Comparative Example 3: Conjugated Diene Copolymer (D19) Batch polymerization was carried out using a tank-type reactor (internal volume 10 L) equipped with a stirrer and a jacket. First, a cyclohexane solution (concentration 20% by mass) containing 10 parts by mass of styrene was added. Next, 0.15 parts by mass of n-butyllithium per 100 parts by mass of total monomers and 0.6 mol of tetramethylethylenediamine (TMEDA) per 1 mole of n-butyllithium were added, and polymerization was carried out at 60°C for 10 minutes. Next, a cyclohexane solution (concentration 20% by mass) containing 30 parts by mass of butadiene was added, and polymerization was carried out at 60°C for 15 minutes. Next, a cyclohexane solution (concentration 20% by mass) containing 25 parts by mass of styrene was added, and polymerization was carried out at 60°C for 15 minutes. Next, a cyclohexane solution (concentration 20% by mass) containing 35 parts by mass of butadiene was added, and polymerization was carried out at 60°C for 15 minutes. Thereafter, methanol was added to terminate the polymerization reaction, and a conjugated diene copolymer was obtained. The conjugated diene copolymer obtained as described above had 0% by mass of the unit (a-1), 35% by mass of the unit (a-2), a total of 35% by mass of the units (a-1) and (a-2), and a number average molecular weight of 5.1 × 10 ４ The molecular weight distribution was 1.09, and the content of units derived from 1,2-bonds and / or 3,4-bonds (vinyl bond content) was 60%. The hydrogenation catalyst prepared as described above was added to the resulting conjugated diene copolymer in an amount of 90 ppm (Ti) per 100 parts by mass of the conjugated diene copolymer, and a hydrogenation reaction was carried out at a hydrogen pressure of 0.7 MPa and a temperature of 80°C for approximately 1.25 hours to obtain a conjugated diene copolymer (D19). The hydrogenation rate was 97%. The maximum tan δ peak temperature was less than -30°C. Furthermore, the residual Co content was 0.1 ppm or less, and the residual Ti content was 500 ppm or less.

[0103] <Examples 30 to 49> and <Comparative Examples 4 to 6> The above-mentioned conjugated diene copolymers (D) and (E) were combined as shown in Tables 4, 5, and 7 below to prepare conjugated diene copolymer compositions (X).

[0104] Example 50: Conjugated Diene Copolymer Composition (X24) For the conjugated diene copolymer composition (X24), first, a conjugated diene copolymer (D20'), which is a polymer before hydrogenation, and a conjugated diene copolymer (E14'), which is a polymer before hydrogenation, were batch-polymerized using a single reactor, followed by a hydrogenation reaction to obtain a conjugated diene copolymer (X24) composed of the conjugated diene copolymer (D20) and the conjugated diene copolymer (E14). Batch polymerization was carried out using a tank-type reactor (internal volume 10 L) equipped with a stirrer and a jacket. First, a cyclohexane solution (concentration 20% by mass) containing 11.7 parts by mass of p-methylstyrene and 0.6 parts by mass of styrene was added. Next, 0.086 parts by mass of n-butyllithium per 100 parts by mass of the total monomers and 0.5 mol of tetramethylethylenediamine (TMEDA) per 1 mole of n-butyllithium were added, and the mixture was polymerized at 60°C for 12 minutes. Next, a cyclohexane solution (concentration 20% by mass) containing 22.8 parts by mass of butadiene was added, and polymerization was carried out at 60°C for 25 minutes. Next, 0.079 parts by mass of n-butyllithium (NBL2) per 100 parts by mass of total monomers, and 0.4 mol of TMEDA per 1 mol of NBL2 were added. Next, a cyclohexane solution (concentration 20% by mass) containing 21.7 parts by mass of p-methylstyrene and 1.1 parts by mass of styrene was added, and polymerization was carried out at 60°C for 20 minutes. Next, a cyclohexane solution (concentration 20% by mass) containing 42.3 parts by mass of butadiene was added, and polymerization was carried out at 60°C for 45 minutes. Thereafter, methanol was added to terminate the polymerization reaction, and a conjugated diene copolymer composition (X24') was obtained, which is a conjugated diene copolymer composition before hydrogenation. The hydrogenation catalyst prepared as described above was added to the obtained conjugated diene copolymer composition (X24') in an amount of 90 ppm (Ti standard) per 100 parts by mass of the conjugated diene copolymer, and a hydrogenation reaction was carried out at a hydrogen pressure of 0.7 MPa and a temperature of 80°C for approximately 1.25 hours to obtain a conjugated diene copolymer composition (X24). The hydrogenation rate was 97%. The component (D20) in the conjugated diene copolymer composition (X24) obtained as described above contained 33.25% by mass of units (a-1), 1.75% by mass of units (a-2), a total of 35% by mass of units (a-1) and (a-2), and had a number average molecular weight of 9.0 × 10４ The component (E14) had a molecular weight distribution of 1.06, a content of units derived from 1,2-bonds and / or 3,4-bonds (vinyl bond content) of 50%, a content of units (a-1) of 33.25% by mass, a content of units (a-2) of 1.75% by mass, a total content of units (a-1) and (a-2) of 35% by mass, and a number average molecular weight of 3.0×10 ４ The molecular weight distribution was 1.06, and the content of units derived from 1,2-bonds and / or 3,4-bonds (vinyl bond content) was 50%. The number of peaks in the chromatogram of the conjugated diene copolymer measured by GPC was 2, and the ratio of component (D20) to component (E14) was component (D20) / component (E14)=7 / 3.

[0105] (Component (II): Radical initiator) Perbutyl P (manufactured by NOF Corporation)

[0106] (Component (III): Curable Resin) Polyphenylene ether (PPE) resin: OPE-2St 1200 (manufactured by Mitsubishi Gas Chemical Company, Inc.)

[0107] (Component (IV): Flame retardant) SAYTEX 8010 (manufactured by Albemarle Japan Co., Ltd.)

[0108] (Component (V): Filler) SOC2 (manufactured by Admatechs Co., Ltd.)

[0109] [Resin Compositions and Cured Products] <Examples 51 to 87>, <Comparative Examples 7 to 12> Resin compositions and cured products were prepared using the component (I): conjugated diene copolymer, conjugated diene copolymer composition, and the components (II) to (V) of the above examples and comparative examples.

[0110] [Method of Preparing Measurement Samples] First, the above components (I) to (V) were added to toluene and mixed to obtain a mixture with the composition (parts by mass) shown in Tables 8 to 12 so that the solids concentration was 60% by mass. The mixture was stirred for 60 minutes to obtain a varnish-like resin composition (varnish). Next, the varnish was impregnated into a fibrous substrate (glass cloth: L2116 manufactured by Asahi Kasei Corporation) and then heated and dried at 130°C for approximately 50 minutes to produce a prepreg. Six of the obtained prepregs were then stacked, heated to 200°C at a heating rate of 2°C / min, and heated and pressurized at 200°C for 60 minutes under 1.1 MPa to obtain an evaluation substrate (cured prepreg). Furthermore, two sheets of prepreg were placed between two sheets of copper foil, heated to a temperature of 200°C at a temperature increase rate of 2°C / min, and heated and pressurized at 200°C for 60 minutes under conditions of 1.1 MPa to obtain a sample (cured prepreg) for measuring copper adhesive strength.

[0111] [Methods for measuring and evaluating properties] ((1) Dielectric loss tangent and dielectric constant) The dielectric loss tangent at 10 GHz was measured by a cavity resonance method. The measuring devices used were a network analyzer (N5230A, manufactured by Agilent Technologies) and a cavity resonator (Cavity Resonator CP series) manufactured by Kanto Electronics Application Development Co., Ltd. Tables 8 to 12 show the measurement results for each example and comparative example. <Evaluation criteria for (Examples 51 to 87) and (Comparative Examples 7 to 12)> Dielectric loss tangent (Df) 5: The dielectric loss tangent is less than 0.0015. 4: The dielectric loss tangent is less than 0.0019 and 0.0015 or more. 3: The dielectric loss tangent is less than 0.0022 and 0.0019 or more. 2: The dielectric loss tangent is less than 0.0025 and 0.0022 or more. 1: Dielectric loss tangent is 0.0025 or more. Dielectric constant (Dk) 5: Dielectric constant is less than 3.0. 4: Dielectric constant is less than 3.1 and 3.0 or more. 3: Dielectric constant is less than 3.3 and 3.1 or more. 2: Dielectric constant is less than 3.5 and 3.3 or more. 1: Dielectric constant is 3.5 or more.

[0112] (2) Glass transition temperature Tg) Measurement was performed using an ARES-G2 rheometer, a viscoelasticity measuring device manufactured by TA Instruments Inc. Sweeping was performed at a temperature range of 25 to 250°C, a temperature rise rate of 5°C / min, a frequency of 10 rad / sec, and a strain of 0.25%, and the tan δ peak temperature was taken as the glass transition temperature of the cured product. Tables 8 to 12 show the measurement results for each example and comparative example. <Evaluation criteria for (Examples 51 to 87) and (Comparative Examples 7 to 12)> 5: Glass transition temperature is 200°C or higher. 4: Glass transition temperature is 190°C or higher but less than 200°C. 3: Glass transition temperature is 170°C or higher but less than 190°C. 2: Glass transition temperature is 150°C or higher but less than 170°C. 1: Glass transition temperature is less than 150°C.

[0113] ((3) Copper Adhesion) Copper adhesion was evaluated using a tension and compression testing machine TGE manufactured by MinebeaMitsumi Inc. Tables 8 to 12 show the measurement results for each example and comparative example. <Evaluation criteria for (Examples 51 to 87) and (Comparative Examples 7 to 12)> 5: Copper peel strength is 0.8 N / mm or more. 4: Copper peel strength is 0.6 N / mm or more and less than 0.8 N / mm. 3: Copper peel strength is 0.3 N / mm or more and less than 0.6 N / mm. 2: Copper peel strength is 0.1 N / mm or more and less than 0.3 N / mm. 1: Copper peel strength is less than 0.1 N / mm.

[0114] (4) Productivity Productivity was evaluated based on the frequency of mesh clogging during the pelletizing process using a twin-screw extruder BT-30 manufactured by Plastics Engineering Research Institute Co., Ltd. Tables 8 to 12 show the measurement results for each Example and Comparative Example. <Evaluation criteria for Examples 51 to 87 and Comparative Examples 7 to 12> ◯: No mesh clogging occurred even once during 10 kg pelletizing. ×: Mesh clogging occurred one or more times during 10 kg pelletizing.

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[0127] It was revealed that the conjugated diene copolymers of the examples, as cured products, had low dielectric constants and low dielectric loss tangents, and also had excellent heat resistance and copper adhesion. This demonstrates that the present invention is suitable for use in glass cloth using the cured products and printed wiring boards using metal laminates.

[0128] This application is based on a Japanese patent application (Patent Application No. 2024-032302) filed with the Japan Patent Office on March 4, 2024, the contents of which are incorporated herein by reference.

[0129] The conjugated diene copolymer of the present invention, a resin composition containing the conjugated diene copolymer, and a cured product thereof have industrial applicability as materials for films, prepregs, electronic circuit boards, and next-generation communication boards.

Claims

1. A conjugated diene copolymer satisfying the following conditions (1) to (4): (Condition (1)) It has a polymer block (A) containing a vinyl aromatic monomer unit (unit (a-1)) having a radical reactive group. (Condition (2)) It has a polymer block (B) mainly composed of a conjugated diene monomer unit (unit (b)). (Condition (3)) The number average molecular weight of the conjugated diene copolymer is more than 40,000 and not more than 150,000. (Condition (4)) The content of all vinyl aromatic monomer units (a) including the unit (a-1) in the conjugated diene copolymer is 5 to 70 mass%.

2. The conjugated diene copolymer according to claim 1, further satisfying the following condition (5): (Condition (5)) The conjugated diene copolymer has a maximum tan δ peak temperature of less than -30°C when measured with a dynamic mechanical analyzer (DMA) at 10 rad / s.

3. The conjugated diene copolymer according to claim 1, further satisfying the following condition (6): (Condition (6)) The amount of residual Co in the conjugated diene copolymer is 0.1 ppm or less, and the amount of residual Ti in the conjugated diene copolymer is 500 ppm or less.

4. The conjugated diene copolymer according to claim 1, further satisfying the following condition (7): (Condition (7)) The number average molecular weight of the conjugated diene copolymer is more than 40,000 and not more than 100,000.

5. The conjugated diene copolymer according to claim 1, wherein the polymer block (A) further comprises a vinyl aromatic monomer unit (unit (a-2)) (excluding the unit (a-1)), and the total content of the vinyl aromatic monomer unit (unit (a-1)) having a radical reactive group and the unit (a-2) in the conjugated diene copolymer is 5 to 70 mass%.

6. The conjugated diene copolymer according to claim 1, wherein at least a portion of the units (b) of the conjugated diene copolymer is hydrogenated.

7. The conjugated diene copolymer according to claim 1, wherein at least a portion of the units (b) of the conjugated diene copolymer is hydrogenated, and the hydrogenation rate is 98% or less.

8. The conjugated diene copolymer according to claim 1, wherein at least a portion of the units (b) of the conjugated diene copolymer is hydrogenated, and the hydrogenation rate is 50% or more and 98% or less.

9. The conjugated diene copolymer according to claim 5, further satisfying the following condition (8): (Condition (8)) The mass ratio of the units (a-1) to the units (a-2) is (a-1) / (a-2)=30 / 70 to 99 / 1.

10. A conjugated diene copolymer composition comprising the conjugated diene copolymer (conjugated diene copolymer (D)) according to claim 1 and a conjugated diene copolymer (E) that satisfies the following (condition (9)): (condition (9)) The number average molecular weight is 40,000 or less.

11. The conjugated diene copolymer composition according to claim 10, comprising the conjugated diene copolymer (D) according to claim 1, and the conjugated diene copolymer (E) which further satisfies the following (condition (10)): (condition (10)) the ratio (MnD / MnE) of the number average molecular weight (MnD) of the conjugated diene copolymer (D) to the number average molecular weight (MnE) of the conjugated diene copolymer (E) is 2 or more.

12. The conjugated diene copolymer composition according to claim 10, comprising the conjugated diene copolymer (D) according to claim 1, and the conjugated diene copolymer (E) which further satisfies the following (condition (11)): (condition (11)) The conjugated diene copolymer composition has a polymer block (A) containing a vinyl aromatic monomer unit (unit (a-1)) having a radical reactive group.

13. The conjugated diene copolymer composition according to claim 12, wherein the conjugated diene copolymer (E) has a polymer block (B) and / or a random polymer block (C) mainly composed of conjugated diene monomer units (units (b)), and the random polymer block (C) contains vinyl aromatic monomer units (units (a-1)) having a radical reactive group and conjugated diene monomer units (units (b)).

14. The conjugated diene copolymer composition according to claim 13, wherein the random polymer block (C) constituting the conjugated diene copolymer (E) further contains a vinyl aromatic monomer unit (unit (a-2)) (excluding unit (a-1)).

15. The conjugated diene copolymer composition according to claim 11, comprising the conjugated diene copolymer (E) which further satisfies the following (condition (11)): (condition (11)) The conjugated diene copolymer (E) has a polymer block (A) containing a vinyl aromatic monomer unit (unit (a-1)) having a radical reactive group.

16. The conjugated diene copolymer composition according to claim 15, wherein the conjugated diene copolymer (E) has a polymer block (B) and / or a random polymer block (C) mainly composed of conjugated diene monomer units (units (b)), and the random polymer block (C) contains vinyl aromatic monomer units (units (a-1)) having a radical reactive group and conjugated diene monomer units (units (b)).

17. The conjugated diene copolymer composition according to claim 16, wherein the random polymer block (C) constituting the conjugated diene copolymer (E) further contains a vinyl aromatic monomer unit (unit (a-2)) (excluding unit (a-1)).

18. A resin composition comprising: component (I): the conjugated diene copolymer according to any one of claims 1 to 9, or the conjugated diene copolymer composition according to any one of claims 10 to 17; and at least one component selected from the group consisting of the following components (II) to (III): component (II): a radical initiator; and component (III): a curable resin (excluding component (I)).

19. The resin composition according to claim 18, wherein the component (III) is at least one selected from the group consisting of polyphenylene ether resins, polyimide resins, liquid crystal polyester resins, fluorine-based resins, epoxy resins, and hydrocarbon resins.

20. A cured product of the conjugated diene copolymer according to any one of claims 1 to 9 or the conjugated diene copolymer composition according to any one of claims 10 to 17.

21. A cured product of the resin composition according to claim 18.

22. A resin film comprising the resin composition according to claim 18.

23. A prepreg, which is a composite of a substrate and the resin composition according to claim 18.

24. The prepreg according to claim 23, wherein the substrate is glass cloth.

25. A laminate comprising the resin film according to claim 22 and a metal foil.

26. A laminate comprising the cured prepreg of claim 22 and a metal foil.

27. A material for electronic circuit boards, comprising the cured product according to claim 21.

28. A material for an electronic circuit board, comprising the resin film according to claim 22.

29. A material for an electronic circuit board, comprising the prepreg of claim 23.