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

Abstract

Provided is a conjugated diene copolymer comprising a polymer block (A) that is mainly composed of vinyl aromatic monomer units and a random polymer block (C) that is mainly composed of vinyl aromatic monomer units and conjugated diene monomer units, and satisfying specific conditions (i) to (iii).

Description

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

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

[0002] In recent years, with the remarkable progress of information network technology and the expansion of services utilizing information networks, electronic devices are required to have larger information capacity and higher processing speed. In order to meet these requirements, materials with low dielectric loss are demanded as materials for insulating layers of various substrates such as printed boards and flexible boards.

[0003] Conventionally, in order to obtain a material with low dielectric loss, cured resins mainly composed of radically curable thermosetting resins such as polyphenylene ether resins which have low dielectric constant and / or low dielectric loss tangent and are excellent in mechanical properties such as strength have been studied and disclosed. However, conventionally disclosed materials still have room for improvement from the viewpoints of low dielectric constant and low dielectric loss tangent, and have the problem that when these materials are used for printed boards, the information amount and processing speed are limited. Further, from the viewpoint of reducing transmission loss, metal foils used as conductors, mainly copper foils, are those with low roughness. Although the use of low-roughness copper foil can reduce transmission loss, it has a problem that the adhesion to the insulating layer tends to decrease.

[0004] For the purpose of improving such problems, various rubber components have been conventionally proposed as modifiers for the above-described thermosetting resins. For example, Patent Document 1 discloses at least one elastomer selected from the group consisting of block copolymers of a vinyl aromatic compound and an olefinic alkene compound, hydrogenated products thereof, and homopolymers of a vinyl aromatic compound, as a modifier for reducing the dielectric loss tangent and dielectric constant of a polyphenylene ether resin. Further, for example, Patent Document 2 discloses a styrenic elastomer as a modifier for reducing the dielectric loss tangent and dielectric constant of an epoxy resin.

[0005] Japanese Patent Publication No. 2021-147486 Japanese Patent Publication No. 2020-15861

[0006] However, the resin compositions using the modifiers disclosed in Patent Documents 1 and 2 still have room for improvement in terms of reducing dielectric loss, strength, and solder heat resistance and moisture resistance.

[0007] Therefore, the present invention aims to provide a conjugated diene copolymer and a resin composition containing the said conjugated diene copolymer that yield a cured product with low dielectric loss and excellent strength, solder heat resistance, and moisture resistance.

[0008] As a result of diligent research to solve the problems of the prior art described above, the present inventors have found that a cured resin composition containing a conjugated diene copolymer having a predetermined structure exhibits low dielectric loss and excellent strength, solder heat resistance, and moisture resistance, thus completing the present invention.

[0009] In other words, the present invention is as follows: [1] A conjugated diene copolymer comprising: a polymer block (A) mainly composed of vinyl aromatic monomer units; and a random polymer block (C) mainly composed of vinyl aromatic monomer units and conjugated diene monomer units, wherein the following conditions (i) to (iii) are satisfied: <Condition (i)> The amount of vinyl aromatic monomer units in the conjugated diene copolymer is 20% by mass or more and 75% by mass or less; <Condition (ii)> The number average molecular weight (Mn) of the conjugated diene copolymer is 30,000 or more and 300,000 or less; <Condition (iii)> The conjugated diene monomer units in the conjugated diene copolymer include units (a) derived from 1,2-bonds and / or 3,4-bonds and units (b) derived from 1,4-bonds, and the amount of unit (a) in 100 g of the conjugated diene copolymer is 0.15 mol or more and 1.2 mol or less. [2] The conjugated diene copolymer according to [1] that satisfies the following formula (i): 15 ≤ (a / (a ​​+ b + a1 + b1)) × 100 < 80 ... formula (i) a: amount of unit (a) in 100 g of the conjugated diene copolymer (mol) a1: amount of hydrogenated alkenyl monomer unit of unit (a) in 100 g of the conjugated diene copolymer (mol) b: amount of unit (b) in 100 g of the conjugated diene copolymer (mol) b1: amount of hydrogenated alkenyl monomer unit of unit (b) in 100 g of the conjugated diene copolymer (mol) [3] The conjugated diene copolymer according to [1] that satisfies the following formula (iii). 35 ≤ (a / (a ​​+ b + a1 + b1)) × 100 < 80 ... Formula (iii) a: Amount (mol) of unit (a) in 100 g of the conjugated diene copolymer a1: Amount (mol) of hydrogenated alkenyl monomer units of unit (a) in 100 g of the conjugated diene copolymer b: Amount (mol) of unit (b) in 100 g of the conjugated diene copolymer b1: Amount (mol) of hydrogenated alkenyl monomer units of unit (b) in 100 g of the conjugated diene copolymer [4] The conjugated diene copolymer according to [2] or [3], further satisfying the following formula (ii).0 ≤ a1 + b1 < a + b ... Formula (ii) a: Amount of unit (a) in 100 g of the conjugated diene copolymer (mol) a1: Amount of hydrogenated alkenyl monomer unit of unit (a) in 100 g of the conjugated diene copolymer (mol) b: Amount of unit (b) in 100 g of the conjugated diene copolymer (mol) b1: Amount of hydrogenated alkenyl monomer unit of unit (b) in 100 g of the conjugated diene copolymer (mol) [5] The conjugated diene copolymer according to any one of [1] to [4], wherein the conjugated diene monomer unit in the conjugated diene copolymer comprises a unit (a) derived from a 1,2-bond and / or a 3,4-bond and a unit (b) derived from a 1,4-bond, and the amount of unit (a) in 100 g of the conjugated diene copolymer is 0.55 mol or more and 1.2 mol or less. [6] The conjugated diene copolymer according to any one of [1] to [5], wherein the amount of vinyl aromatic monomer units in the conjugated diene copolymer is 20% by mass or more and less than 45% by mass. [7] The conjugated diene copolymer according to any one of [1] to [6], wherein the amount of vinyl aromatic monomer units in the conjugated diene copolymer is 20% by mass or more and less than 40% by mass. [8] The conjugated diene copolymer according to any one of [1] to [7], wherein the amount of vinyl aromatic monomer units in the polymer block (C) is 10% by mass or more and less than 60% by mass. [9] The conjugated diene copolymer according to any one of [1] to [8], wherein the amount of vinyl aromatic monomer units in the polymer block (C) is 10% by mass or more and less than 45% by mass.

[10] The conjugated diene copolymer according to any one of [1] to [9], further comprising a polymer block (B) mainly composed of conjugated diene monomer units.

[11] The conjugated diene copolymer according to

[10] , wherein the content of the polymer block (B) in the conjugated diene copolymer is 25% by mass or less.

[12] The conjugated diene copolymer according to

[11] , wherein the conjugated diene copolymer contains two or more polymer blocks (A), and at least one end is the polymer block (B).

[13] The conjugated diene copolymer according to any one of [1] to

[12] , wherein the number average molecular weight (Mn) is 65,000 or more and 300,000 or less.

[14] A conjugated diene copolymer according to any one of [1] to

[13] , wherein the number average molecular weight (Mn) is 70,000 or more and 250,000 or less.

[15] A conjugated diene copolymer according to any one of [1] to

[14] , wherein the number average molecular weight of the polymer block (A) is 3,000 or more.

[16] A conjugated diene copolymer according to any one of [1] to

[15] , having at least two polymer blocks (A).

[17] A resin composition comprising: Component (I): A conjugated diene copolymer according to any one of [1] to

[16] , and at least one selected from the group consisting of the following components (II), (III), and (IV). Component (II): Radical initiator Component (III): Curable resin (excluding component (I)) Component (IV): Curing agent

[18] The resin composition according to

[17] , wherein component (III) is a radical curable resin.

[19] The resin composition according to

[18] , wherein the reactive group of the radical curable resin which is component (III) is at least one reactive group selected from the group consisting of vinyl group, maleimide group, allyl group and methacrylic group.

[20] A cured product comprising the conjugated diene copolymer according to any one of [1] to

[16] .

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

[17] to

[19] .

[22] A resin film comprising the resin composition according to any one of

[17] to

[19] .

[23] A prepreg comprising a composite of a substrate and the resin composition according to any one of

[17] to

[19] .

[24] The prepreg according to

[23] , wherein the substrate is glass cloth.

[25] An electronic circuit board material comprising the cured product according to

[20] and / or the resin film according to

[22] .

[0010] According to the present invention, it is possible to provide a conjugated diene copolymer and a resin composition containing the conjugated diene copolymer that yield a cured product with low dielectric loss and excellent strength, solder heat resistance, and moisture resistance.

[0011] The following describes in detail embodiments for carrying out the present invention (hereinafter simply referred to as "this embodiment"). It should be noted that this embodiment is illustrative for explaining the present invention and is not intended to limit the present invention to the following content; the present invention can be implemented in various modifications within the scope of its gist.

[0012] [Conjugated Diene Copolymer] The conjugated diene copolymer of this embodiment includes a polymer block (A) mainly composed of vinyl aromatic monomer units (hereinafter sometimes referred to as polymer block (A)) and a random polymer block (C) mainly composed of vinyl aromatic monomer units and conjugated diene monomer units (hereinafter sometimes referred to as polymer block (C)), and satisfies the following conditions (i) to (iii). <Condition (i)> The amount of vinyl aromatic monomer units in the conjugated diene copolymer is 20% by mass or more and 75% by mass or less. <Condition (ii)> The number average molecular weight (Mn) in the conjugated diene copolymer is 30,000 or more and 300,000 or less. <Condition (iii)> The conjugated diene monomer unit in the conjugated diene copolymer contains a unit (a) derived from a 1,2-bond and / or a 3,4-bond and a unit (b) derived from a 1,4-bond, and the amount of unit (a) in 100 g of the conjugated diene copolymer is 0.15 mol or more and 1.2 mol or less.

[0013] Examples of vinyl aromatic monomers include, but are not limited to, o-methylstyrene, p-methylstyrene, o-ethylstyrene, p-ethylstyrene, o-isopropylstyrene, para-isopropylstyrene, o-methyl-α-methylstyrene, p-methyl-α-methylstyrene, o-ethyl-α-methylstyrene, p-ethyl-α-methylstyrene, o-isopropyl-α-methylstyrene, para-isopropyl-α-methylstyrene, divinylbenzene, styrene, 1,1-diphenylethylene, N,N-dimethyl-p-aminoethylstyrene, and N,N-diethyl-p-aminoethylstyrene.

[0014] The conjugated diene monomer units are not limited to the following, but examples include 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, isoprene, etc. or mixtures thereof. However, from the viewpoint of availability, 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, and 1,3-cyclohexadiene are preferred, and 1,3-butadiene is more preferred.

[0015] These may be used individually or in combination of two or more types.

[0016] Furthermore, the aforementioned conjugated diene monomer units may be bio-derived conjugated diene monomer units.

[0017] Here, "primarily composed of vinyl aromatic monomer units" means that the total amount of vinyl aromatic monomer units in the polymer block (A) is 90% by mass or more, preferably 95% by mass or more, and more preferably 100% by mass (intentionally excluding other copolymer components).

[0018] The inclusion of the polymer block (A) in this embodiment results in high strength for the conjugated diene copolymer, improving the strength of the resin composition containing the conjugated diene copolymer and the cured product containing the resin composition, as described later. Furthermore, from the viewpoint of obtaining sufficient strength, the number average molecular weight of the polymer block (A) is preferably 3000 or more, more preferably 3500 or more, even more preferably 4000 or more, even more preferably 4500 or more, and particularly preferably 5000 or more. The upper limit of the number average molecular weight of the polymer block (A) is not particularly limited, but for example, it is 200,000 or less, preferably 150,000 or less, and more preferably 100,000 or less.

[0019] Polymer block (C) mainly consists of vinyl aromatic monomer units and conjugated diene monomer units. Here, "mainly consisting of vinyl aromatic monomer units and conjugated diene monomer units" means that the total amount of vinyl aromatic monomer units and conjugated diene monomer units in polymer block (C) is 90% by mass or more, preferably 95% by mass or more, and more preferably 100% by mass (intentionally excluding other copolymer components). Polymer block (C) is intentionally formulated with vinyl aromatic monomer units and conjugated diene monomer units and can be clearly distinguished from polymer block (A) and polymer block (B), which mainly consists of conjugated diene monomer units and will be described later.

[0020] In this embodiment, the conjugated diene copolymer is compatible with and / or bonds with components (II), (III), and (IV) described later, and the conjugated diene copolymers bond with each other. As a result, the network formed by components (II), (III), and (IV) and the network formed by the conjugated diene copolymer become compatible in the cured state, which tends to improve the dielectric properties and strength of the cured resin composition.

[0021] Here, vinyl aromatic monomer units are known to be more polar than conjugated diene monomer units. Furthermore, unsaturated bonds derived from conjugated diene monomer units are known to be radically reactive. Therefore, the presence of the polymer block (C) in the conjugated diene copolymer makes it easier for the conjugated diene monomer units having radically reactive groups to become compatible with and / or bond with components (II), (III), and (IV) described later, thereby improving the dielectric properties and strength of the cured resin composition.

[0022] From the viewpoint of ensuring sufficient reaction sites in the radical reactivity described above, the amount of vinyl aromatic monomer units in the conjugated diene copolymer of this embodiment is preferably 75% by mass or less, more preferably 70% by mass or less, even more preferably 60% by mass or less, even more preferably 50% by mass or less, particularly preferably less than 45% by mass, especially preferably 40% by mass or less, and even more preferably 38% by mass or less. On the other hand, the lower limit of the amount of vinyl aromatic monomer units in the conjugated diene copolymer of this embodiment is 20% by mass or more, preferably 22% by mass or more, and more preferably 25% by mass or more, from the viewpoint of the strength described above.

[0023] Also, from a similar viewpoint, in the conjugated diene copolymer of this embodiment, the amount of vinyl aromatic monomer units in the polymer block (C) is preferably 10% by mass or more and 60% by mass or less, more preferably 10% by mass or more and 50% by mass or less, even more preferably 10% by mass or more and less than 45% by mass, even more preferably 10% by mass or more and 43% by mass or less, particularly preferably 10% by mass or more and 40% by mass or less, and especially preferably 15% by mass or more and 40% by mass or less.

[0024] In recent years, the insulating layer of printed circuit boards has been required to possess both high strength and flexibility.

[0025] From the standpoint of high flexibility, it is preferable that components (II), (III), and (IV), described later, are bonded to a highly flexible conjugated diene copolymer.

[0026] As described above, the conjugated diene copolymer of this embodiment preferably contains polymer block (A), polymer block (C), and polymer block (B) mainly composed of conjugated diene monomer units (hereinafter also simply referred to as "polymer block (B)"), in order to have high reactivity and flexibility. Furthermore, in terms of balancing compatibility with components (II), (III), and (IV) described later, the content of polymer block (B) in the conjugated diene copolymer of this embodiment is preferably 25% by mass or less, more preferably 20% by mass or less, even more preferably 17% by mass or less, and even more preferably 15% by mass or less.

[0027] In this embodiment, each content can be calculated using the method described in the examples below.

[0028] Since polymer block (B) mainly consists of conjugated diene monomer units, it exhibits higher reactivity compared to polymer block (C) because the conjugated diene monomer units, which are the reaction sites, are not affected by steric hindrance from vinyl aromatic monomer units. Furthermore, the inclusion of polymer block (B) tends to improve the flexibility of the conjugated diene copolymer of this embodiment. Therefore, it is preferable that the conjugated diene copolymer of this embodiment includes polymer block (A), polymer block (C), and polymer block (B) mainly consisting of conjugated diene monomer units.

[0029] Here, "primarily composed of conjugated diene monomer units" means that the total amount of conjugated diene monomer units in the polymer block (B) is 90% by mass or more, preferably 95% by mass or more, and more preferably 100% by mass (intentionally excluding other copolymer components). In recent years, cured products used in the insulating layer of printed circuit boards are required to have a low coefficient of thermal expansion (CTE) while maintaining the aforementioned flexibility. Conventionally, cured products with small molecular weights between crosslinking points are known to exhibit low CTE, but it is also known that cured products with small molecular weights between crosslinking points tend to have reduced flexibility. In order to achieve both low CTE and flexibility, it is preferable that the conjugated diene copolymer has reactivity with the thermosetting resin described later and intramolecular reactivity. That is, by increasing the molecular weight between crosslinking points of the cured product through reaction with the thermosetting resin, a cured product with excellent flexibility is obtained, and by the intramolecular reaction, the molecular chains of the conjugated diene copolymer in the cured product become less mobile at high temperatures, which tends to lower the CTE. Therefore, the conjugated diene copolymer preferably has a random polymer block (C) containing vinyl aromatic monomer units and conjugated diene monomer units that have excellent compatibility and / or reactivity with thermosetting resins described later, and a polymer block (B) mainly composed of conjugated diene monomer units that have excellent intramolecular reactivity. More preferably, the amount of vinyl aromatic monomer units in polymer block (C) is 10% by mass or more, even more preferably 15% by mass or more. The upper limit of the amount of vinyl aromatic monomer units in polymer block (C) is preferably 60% by mass or less, more preferably 50% by mass or less, even more preferably 45% by mass or less, even more preferably 43% by mass or less, particularly preferably 40% by mass or less, and especially preferably 40% by mass or less. The amount of vinyl aromatic monomer units in the polymer block (C) is preferably 10% by mass or more and 60% by mass or less, more preferably 10% by mass or more and 50% by mass or less, even more preferably 10% by mass or more and less than 45% by mass, even more preferably 10% by mass or more and 43% by mass or less, particularly preferably 10% by mass or more and 40% by mass or less, and especially preferably 15% by mass or more and 40% by mass or less.When the amount of vinyl aromatic monomer units in polymer block (C) is 60% by mass or less, the steric hindrance of the vinyl aromatic monomer units is suppressed, and the reactivity of the double bond derived from the conjugated diene monomer units tends to improve. When the amount of vinyl aromatic monomer units in polymer block (C) is 10% by mass or more, the compatibility with the thermosetting resin described later tends to improve. Furthermore, the content of polymer block (B) in the conjugated diene copolymer is preferably 3% by mass or more and 25% by mass or less, more preferably 3% by mass or more and 20% by mass or less, even more preferably 3% by mass or more and 17% by mass or less, even more preferably 3% by mass or more and 15% by mass or less, and even more preferably 5% by mass or more and 15% by mass or less. When the content of polymer block (B) in the conjugated diene copolymer is 3% by mass or more, intramolecular reactions are sufficient and the CTE tends to be low. Furthermore, if the content of polymer block (B) in the conjugated diene copolymer is 25% by mass or less, the compatibility and / or reactivity with the thermosetting resin described later becomes sufficient, and flexibility tends to improve. In addition, it is preferable that the conjugated diene copolymer of this embodiment contains two or more polymer blocks (A), and at least one end is polymer block (B). Including two or more polymer blocks (A) in the conjugated diene copolymer of this embodiment, and more preferably having at least one end of the conjugated diene copolymer be polymer block (B), tends to reduce the mobility of the conjugated diene copolymer in the cured product described later, and the CTE tends to decrease. Furthermore, cured products used in the insulating layer of printed circuit boards tend to require high adhesion to low-roughness metal foils, especially copper foils. In terms of achieving a high balance between adhesion to low-roughness metal foil and low CTE, the conjugated diene copolymer in the cured product described later preferably has the random polymer block (C) and the polymer block (B) mainly composed of the conjugated diene monomer units, more preferably the amount of vinyl aromatic monomer units in the random polymer block (C) is 25% by mass or less, even more preferably the content of the polymer block (B) in the conjugated diene copolymer is 25% by mass or less, and even more preferably at least one end of the conjugated diene copolymer is the polymer block (B).The conjugated diene copolymer of this embodiment tends to have improved interaction with metal foil due to the presence of the polymer block (C). Preferably, the conjugated diene copolymer of this embodiment has the polymer block (B), more preferably the amount of vinyl aromatic monomer units in the polymer block (B) is less than 45% by mass, and even more preferably at least one end of the conjugated diene copolymer is the polymer block (B). With this configuration, the conjugated diene copolymer of this embodiment tends to have improved wettability with metal foil, and as a result tends to have excellent adhesion to metal foil.

[0030] The number-average molecular weight of the conjugated diene copolymer in this embodiment is 30,000 or more. Having a number-average molecular weight of 30,000 or more yields a high-strength conjugated diene copolymer, improving the strength of the resin composition and / or the cured product of the resin composition, as described later. From the above viewpoint, the number-average molecular weight of the conjugated diene copolymer in this embodiment is 30,000 or more, preferably 40,000 or more, more preferably 45,000 or more, more preferably 55,000 or more, even more preferably 65,000 or more, particularly preferably 70,000 or more, and especially preferably 75,000 or more. Furthermore, because the conjugated diene copolymer in this embodiment has a number-average molecular weight of 35,000 or more, it tends to exist as a solid with no fluidity rather than a liquid. Therefore, it is preferable in that it is easy to mold into shapes such as pellets to suit handling needs during transportation and processing.

[0031] The upper limit of the number-average molecular weight of the conjugated diene copolymer in this embodiment is 300,000 or less, more preferably 250,000 or less, more preferably 230,000 or less, and even more preferably 200,000 or less, because in the resin composition manufacturing method described later, each component is dissolved in a solvent and then mixed to produce a resin film and prepreg, from the viewpoint of solubility in the solvent. Furthermore, in order to reduce the molecular weight between crosslinking points from the viewpoint of low CTE as mentioned above, the number-average molecular weight of the conjugated diene copolymer is preferably 250,000 or less, more preferably 240,000 or less, even more preferably 230,000 or less, and even more preferably 220,000 or less.

[0032] The method for controlling the number-average molecular weight of the conjugated diene copolymer within the aforementioned range is not particularly limited, but one example is controlling the amount of polymerization initiator described later.

[0033] The number-average molecular weight can be measured by the method described in the examples below. It is the number-average molecular weight obtained by measuring the molecular weight of the peaks in the chromatogram obtained by gel permeation chromatography (GPC), based on a calibration curve (created using the peak molecular weight of standard polystyrene) obtained from measurements of commercially available standard polystyrene.

[0034] The conjugated diene copolymer of this embodiment may include copolymer block (D) obtained by copolymerizing conjugated diene monomer units and / or vinyl aromatic monomer units with other compounds other than polymer block (A), polymer block (C), and polymer block (B), within a range that does not impair dielectric properties, in order to impart compatibility with components (II), (III), and (IV) described later and / or reactivity and / or adhesion to metal foil.

[0035] For example, when the conjugated diene copolymer of this embodiment, which includes copolymer block (D), is produced by anionic polymerization, methyl methacrylate (MMA) can copolymerize with vinyl aromatic compounds and conjugated diene compounds. However, when MMA is included, the polarity of the conjugated diene copolymer of this embodiment tends to increase, improving the aforementioned compatibility and / or reactivity and / or adhesion to metal foils, but the dielectric constant and / or dielectric loss tangent of the conjugated diene copolymer tend to worsen.

[0036] In the conjugated diene copolymer of this embodiment, the conjugated diene monomer unit includes a unit (a) derived from a 1,2-bond and / or 3,4-bond and a unit (b) derived from a 1,4-bond, and the amount of unit (a) in 100 g of the conjugated diene copolymer is 0.15 mol or more and 1.2 mol or less.

[0037] The amount of unit (a) in 100 g of the conjugated diene copolymer is 0.15 mol or more, which ensures sufficient reactivity, improving not only dielectric performance and strength but also solder heat resistance. From the above viewpoint, the amount of unit (a) in 100 g of the conjugated diene copolymer is 0.15 mol or more, preferably 0.25 mol or more, more preferably 0.35 mol or more, even more preferably 0.45 mol or more, even more preferably 0.55 mol or more, and particularly preferably 0.65 mol or more. The upper limit of the amount of unit (a) in 100 g of the conjugated diene copolymer is 1.2 mol or less, preferably 1.15 mol or less, more preferably 1.1 mol or less, even more preferably 1.05 mol or less, and even more preferably 1 mol or less, from the viewpoint of avoiding deterioration of solder heat resistance, dielectric loss tangent and dielectric constant due to unreacted unit (a) after curing.

[0038] The content of unit (a) can be controlled to the above-mentioned numerical range by using modifiers such as polar compounds in the polymerization process of the conjugated diene copolymer, and can be calculated by the method described in the examples below.

[0039] Examples of modifying agents include tertiary amine compounds and ether compounds. It is preferable to use tertiary amine compounds.

[0040] Tertiary amine compounds are compounds represented by the general formula R1R2R3N (wherein R1, R2, and R3 are each independently a hydrocarbon group having 1 to 20 carbon atoms, or a hydrocarbon group having a tertiary amino group).

[0041] Examples of tertiary amine compounds include, but are not limited to, trimethylamine, triethylamine, tributylamine, N,N-dimethylaniline, N-ethylpiperidine, N-methylpyrrolidine, N,N,N',N'-tetramethylethylenediamine, N,N,N',N'-tetraethylethylenediamine, 1,2-dipiperidinoethane, trimethylaminoethylpiperazine, N,N,N',N'',N''-pentamethylethylenetriamine, and N,N'-dioctyl-p-phenylenediamine.

[0042] The addition amount of the regulator is preferably 0.1 mol or more, more preferably 0.5 mol or more, and still more preferably 0.7 mol or more, per 1 mol of the polymerization initiator described below.

[0043] The conjugated diene-based copolymer of the present embodiment may be hydrogenated.

[0044] The method for hydrogenating the conjugated diene-based copolymer is not particularly limited, and a known method can be applied.

[0045] A known hydrogenation catalyst can be used in the hydrogenation reaction. The hydrogenation catalyst is not particularly limited, and examples thereof include: (1) supported heterogeneous hydrogenation catalysts obtained by supporting a metal such as Ni, Pt, Pd, or Ru on carbon, silica, alumina, diatomaceous earth, or the like; (2) so-called Ziegler-type hydrogenation catalysts using a transition metal salt such as an organic acid salt of Ni, Co, Fe, Cr or the like or an acetylacetonate salt and a reducing agent such as organoaluminum; and (3) homogeneous hydrogenation catalysts such as so-called organometallic complexes including organometallic compounds of Ti, Ru, Rh, Zr or the like.

[0046] Specific examples of the hydrogenation catalyst are not particularly limited, and for example, the hydrogenation catalysts described in Japanese Examined Patent Publication No. Sho 42-8704, Japanese Examined Patent Publication No. Sho 43-6636, Japanese Examined Patent Publication No. Sho 63-4841, Japanese Examined Patent Publication No. Hei 1-37970, Japanese Examined Patent Publication No. Hei 1-53851, and Japanese Examined Patent Publication No. Hei 2-9041 can be used.

[0047] Preferred hydrogenation catalysts include titanocene compounds and / or reducing organometallic compounds.

[0048] The titanocene compound is not particularly limited, and for example, the compounds described in Japanese Unexamined Patent Publication No. Hei 8-109219 can be used. Examples of the titanocene compound include, but are not limited to, compounds having at least one ligand having a (substituted) cyclopentadienyl skeleton, an indenyl skeleton, or a fluorenyl skeleton, such as biscyclopentadienyl titanium dichloride and monopentamethylcyclopentadienyl titanium trichloride. The titanocene compound may contain one type of the above skeleton alone or a combination of two types thereof.

[0049] Reducing organometallic compounds include, but are not limited to, organolithium and other organoalkali metal compounds, organomagnesium compounds, organoaluminum compounds, organoboron compounds, and organozinc compounds.

[0050] These may be used individually or in combination of two or more types.

[0051] When the conjugated diene copolymer of this embodiment is hydrogenated, the hydrogenation rate can be controlled within the above-mentioned numerical range by appropriately adjusting the reaction temperature, reaction time, hydrogen supply amount, catalyst amount, etc., in the hydrogenation method. The hydrogenation reaction is preferably carried out at a temperature of 55 to 200°C, more preferably at 60 to 170°C, and even more preferably at 65 to 160°C. The hydrogen pressure used in the hydrogenation reaction is 0.1 to 15 MPa, preferably at 0.2 to 10 MPa, and more preferably at 0.3 to 5 MPa. The hydrogenation reaction time is usually 3 minutes to 10 hours, preferably at 10 minutes to 5 hours.

[0052] The hydrogenation reaction can be carried out using a batch process, a continuous process, or a combination of both.

[0053] Here, as a method for controlling the amount of unit (a) in 100 g of the conjugated diene copolymer, a method of controlling the amount of vinyl aromatic monomer units in the conjugated diene copolymer can also be mentioned.

[0054] For example, if the proportion of unit (a) in the conjugated diene monomer unit is small, the amount of unit (a) in 100 g of the conjugated diene copolymer can be reduced to 0.15 mol or more by reducing the amount of vinyl aromatic monomer unit in the conjugated diene copolymer.

[0055] However, from the viewpoint of compatibility with and / or reaction with components (II), (III), and (IV) described later, and from the viewpoint of avoiding deterioration of heat resistance, dielectric loss tangent, and dielectric constant due to unreacted units (a) after curing, it is preferable that the amount of unit (a) in the conjugated diene monomer units contained in the conjugated diene copolymer of this embodiment satisfies the following formulas (i) and (ii).

[0056] 15 ≤ a / (a ​​+ b + a1 + b1) < 80 ... Equation (i) 0 ≤ a1 + b1 < a + b ... Equation (ii) a: Amount (mol) of unit (a) in 100 g of the conjugated diene copolymer a1: Amount (mol) of hydrogenated alkenyl monomer units of unit (a) in 100 g of the conjugated diene copolymer b: Amount (mol) of unit (b) in 100 g of the conjugated diene copolymer b1: Amount (mol) of hydrogenated alkenyl monomer units of unit (b) in 100 g of the conjugated diene copolymer

[0057] In other words, the lower limit of the amount of unit (a) in the conjugated diene monomer units contained in the conjugated diene copolymer of this embodiment is preferably 15% or more, more preferably 25% or more, even more preferably 30% or more, and even more preferably 35% or more, which can be expressed in formula as follows: 35 ≤ (a / (a ​​+ b + a1 + b1)) × 100 < 80 ... formula (iii) The particularly preferred lower limit of (a / (a ​​+ b + a1 + b1)) × 100 is 40% or more. The upper limit of (a / (a ​​+ b + a1 + b1)) × 100 is more preferably less than 77%, even more preferably less than 75%, even more preferably less than 73%, and especially preferably less than 70%.

[0058] [Method for producing conjugated diene copolymers] The conjugated diene copolymer of this embodiment can be produced, for example, by living anionic polymerization in a hydrocarbon solvent using a polymerization initiator such as an organoalkali metal compound.

[0059] Examples of hydrocarbon solvents include, but are not limited to, aliphatic hydrocarbons such as n-butane, isobutane, n-pentane, n-hexane, n-heptane, and n-octane; alicyclic hydrocarbons such as cyclohexane, cycloheptane, and methylcycloheptane; and aromatic hydrocarbons such as benzene, toluene, xylene, and ethylbenzene.

[0060] Polymerization initiators are not particularly limited, but examples include organoalkali metal compounds such as aliphatic hydrocarbon alkali metal compounds, aromatic hydrocarbon alkali metal compounds, and organic aminoalkali metal compounds, which are generally known to have anionic polymerization activity towards conjugated diene compounds and vinyl aromatic compounds.

[0061] Alkali metals are not particularly limited, but examples include lithium, sodium, and potassium.

[0062] The organoalkali metal compounds are not particularly limited, but examples include aliphatic and aromatic hydrocarbon lithium compounds having 1 to 20 carbon atoms, and include compounds containing one lithium atom per molecule, dilithium compounds, trilithium compounds, and tetralithium compounds containing multiple lithium atoms per molecule.

[0063] Examples of organoalkali metal compounds include, but are not particularly limited, n-propyllithium, n-butyllithium, sec-butyllithium, tert-butyllithium, n-pentyllithium, n-hexyllithium, benzyllithium, phenyllithium, tolyllithium, reaction products of diisopropenylbenzene and sec-butyllithium, and reaction products of divinylbenzene, sec-butyllithium and a small amount of 1,3-butadiene. Furthermore, although not particularly limited, other lithium compounds can also be used, such as 1-(t-butoxy)propyllithium disclosed in U.S. Patent No. 5,708,092 and lithium compounds in which one to several isoprene monomers are inserted to improve solubility; siloxy group-containing alkyllithiums such as 1-(t-butyldimethylsiloxy)hexyllithium disclosed in British Patent No. 2,241,239; amino group-containing alkyllithiums disclosed in U.S. Patent No. 5,527,753; and aminolithium compounds such as diisopropylamide lithium and hexamethyldisilazidolithium.

[0064] Conventional known methods can be applied as methods for polymerizing vinyl aromatic compounds and conjugated diene compounds using organoalkali metal compounds as polymerization initiators.

[0065] The polymerization method is not particularly limited, but may include, for example, batch polymerization, continuous polymerization, or a combination thereof. Batch polymerization is preferred for obtaining a uniform polymer block.

[0066] The polymerization temperature is preferably 0°C to 180°C, and more preferably 30°C to 150°C.

[0067] The polymerization time varies depending on the conditions, but is usually within 48 hours, and preferably 0.1 to 10 hours.

[0068] Furthermore, an inert gas atmosphere such as nitrogen gas is preferred as the atmosphere for the polymerization system.

[0069] The polymerization pressure should be set to a pressure range that can maintain the monomer and solvent in the liquid phase within the above temperature range, and is not particularly limited. Furthermore, it is preferable to take care to prevent the polymerization system from containing impurities that would deactivate the catalyst and living polymer, such as water, oxygen, or carbon dioxide.

[0070] Furthermore, at the end of the polymerization step described above, a coupling reaction may be carried out by adding a required amount of a bifunctional or more coupling agent. However, the coupling rate is preferably 40% or less, more preferably 30% or less, and even more preferably 20% or less. It is even more preferable that the product contains no coupling agent.

[0071] Conventional and known bifunctional coupling agents can be used, and are not particularly limited.

[0072] Examples of bifunctional coupling agents include, but are not limited to, alkoxysilane compounds such as trimethoxysilane, triethoxysilane, tetramethoxysilane, tetraethoxysilane, dimethyldimethoxysilane, diethyldimethoxysilane, dichlorodimethoxysilane, dichlorodiethoxysilane, trichloromethoxysilane, and trichloroethoxysilane; dihalogen compounds such as dichloroethane, dibromoethane, dimethyldichlorosilane, and dimethyldibromosilane; and acid esters such as methyl benzoate, ethyl benzoate, phenyl benzoate, and phthalates.

[0073] Furthermore, conventionally known polyfunctional coupling agents with three or more functions can be used, and are not particularly limited.

[0074] Examples of polyfunctional coupling agents with three or more functions include polyalcohols with three or more functions, epoxidized soybean oil, diglycidylbisphenol A, and polyvalent epoxy compounds such as 1,3-bis(N-N'-diglycidylaminomethyl)cyclohexane; general formula R ４ -nSix ｎ Silicon halide compounds represented by (where R is a hydrocarbon group having 1 to 20 carbon atoms, X is a halogen, and n is an integer from 3 to 4), such as methylsilyl trichloride, t-butylsilyl trichloride, silicon tetrachloride, and their brominated products; general formula R ４ -nSnX ｎ Examples of tin halogen compounds represented by (where R is a hydrocarbon group having 1 to 20 carbon atoms, X is a halogen, and n is an integer from 3 to 4) include polyvalent halogen compounds such as methyltin trichloride, t-butyltin trichloride, and tin tetrachloride. Dimethyl carbonate and diethyl carbonate may also be used.

[0075] The conjugated diene copolymer of this embodiment may be subjected to a hydrogenation reaction as needed, and the hydrogenation reaction can be carried out by a known method using a known hydrogenation catalyst.

[0076] The solution of the conjugated diene copolymer obtained as described above can be separated from the solution by removing catalyst residue as needed.

[0077] When producing the conjugated diene copolymer of this embodiment by anionic living polymerization, the polymerization initiator and the metal atom-containing compound in the hydrogenation catalyst in the hydrogenation reaction described above tend to react with moisture in the air during the desolvent removal process, etc., to generate a predetermined metal compound that remains in the conjugated diene copolymer. It is preferable that the materials for electronic circuit boards include a step of dissolving each material in an organic solvent and removing impurities such as the aforementioned metal compound by filtration. In filtration, metal compounds tend to clog filters such as meshes, leading to a decrease in productivity.

[0078] Furthermore, when these metal compounds are included in the cured product of this embodiment, the dielectric constant and dielectric loss tangent tend to increase, and in addition, ion migration tends to occur more easily in electronic material applications.

[0079] The remaining metal compounds are not particularly limited, but include, for example, metal compounds contained in polymerization initiators and hydrogenation catalysts. Specifically, they are not particularly limited, but include, for example, oxides of various atoms such as titanium dioxide, amorphous titanium dioxide, orthotitanic acid and metatitanic acid, titanium hydroxide, nickel hydroxide, nickel monoxide, lithium oxide, lithium hydroxide, cobalt oxide, and cobalt hydroxide, as well as composite oxides of various atoms with dissimilar metals such as lithium titanate, barium titanate, strontium titanate, nickel titanate, and nickel-iron oxide.

[0080] From the viewpoint of productivity, the residual amount of metal compound in the conjugated diene copolymer of this embodiment is preferably 150 ppm or less, more preferably 130 ppm or less, even more preferably 100 ppm or less, and even more preferably 90 ppm or less as residual metal. In particular, from the viewpoint of particle size, the Co particle size is preferably 80 ppm or less, more preferably 60 ppm or less, even more preferably 40 ppm or less, even more preferably 20 ppm or less, even more preferably 10 ppm or less, even more preferably 5 ppm or less, and even more preferably 2 ppm or less.

[0081] Furthermore, from the viewpoint of lowering the dielectric constant, lowering the dielectric loss tangent, and making ion migration less likely to occur, the residual amount of metal compound in the conjugated diene copolymer of this embodiment is preferably 80 ppm or less, more preferably 70 ppm or less, even more preferably 60 ppm or less, and even more preferably 50 ppm or less.

[0082] The method for reducing the residual amount of metal compounds in the conjugated diene copolymer of this embodiment is not particularly limited and can be any conventionally known method. For example, a method of neutralizing the hydrogenation catalyst residue by adding water and carbon dioxide after the hydrogenation reaction of the conjugated diene copolymer; or a method of neutralizing the hydrogenation catalyst residue by adding an acid in addition to water and carbon dioxide. Specifically, the method described in Japanese Patent Application No. 2014-557427 can be applied. Even when these metal removal methods are used, water containing hydroxides of metal compounds is mixed in during the desolventing process of the conjugated diene copolymer, so it is common for about 1 to 15 ppm to be present. Therefore, it is preferable to remove 20% or more of the amount of metal added to the conjugated diene copolymer, more preferably 30% or more, even more preferably 40% or more, even more preferably 50% or more, and even more preferably 60% or more.

[0083] Furthermore, it is possible to reduce the amount of residual metal compounds in the conjugated diene copolymer of this embodiment by reducing the amount of polymerization initiator and hydrogenation catalyst added. However, reducing the amount of polymerization initiator increases the molecular weight of the conjugated diene copolymer, and if it falls outside the preferred molecular weight range mentioned above, the strength of the cured product tends to decrease. Also, when performing the hydrogenation reaction, reducing the amount of hydrogenation reaction catalyst leads to a longer hydrogenation reaction time and a higher hydrogenation reaction temperature, which tends to significantly reduce productivity.

[0084] The method for separating the solvent when extracting the conjugated diene copolymer is not particularly limited, but examples include adding a polar solvent that is a poor solvent for the conjugated diene copolymer, such as acetone or alcohol, to the reaction solution after hydrogenation to precipitate and recover the conjugated diene copolymer; adding the reaction solution to hot water under stirring and removing the solvent by steam stripping to recover the copolymer; or directly heating the conjugated diene copolymer solution to remove the solvent by distillation.

[0085] Furthermore, various stabilizers such as phenolic stabilizers, phosphorus-based stabilizers, sulfur-based stabilizers, and amine-based stabilizers can be added to the hydrogenated products of conjugated diene copolymers.

[0086] The conjugated diene copolymer of this embodiment may have "polar groups" to the extent that it does not impair dielectric properties.

[0087] "Polar groups" are not limited to the following, but examples include atomic groups containing at least one functional group selected from the group consisting of hydroxyl groups, carboxyl groups, carbonyl groups, thiocarbonyl groups, acid halide groups, acid anhydride groups, carboxylic acid groups, thiocarboxylic acid groups, aldehyde groups, thioaldehyde groups, carboxylic acid ester groups, amide groups, sulfonic acid groups, sulfonic acid ester groups, phosphoric acid groups, phosphoric acid ester groups, amino groups, imino groups, nitrile groups, pyridyl groups, quinoline groups, epoxy groups, thioepoxy groups, sulfide groups, isocyanate groups, isothiocyanate groups, silicon halide groups, silanol groups, alkoxysilicon groups, tin halide groups, boronic acid groups, boron-containing groups, boronic acid bases, alkoxytin groups, and phenyltin groups.

[0088] The aforementioned "polar group" can be formed using a modifying agent.

[0089] Examples of denaturing agents include, but are not limited to, tetraglycidylmetoxylendiamine, tetraglycidyl-1,3-bisaminomethylcyclohexane, ε-caprolactone, δ-valerolactone, 4-methoxybenzophenone, γ-glycidoxyethyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyldimethylphenoxysilane, bis(γ-glycidoxypropyl)methylpropoxysilane, 1,3-dimethyl-2-imidazolidinone, 1,3-diethyl-2-imidazolidinone, N,N'-dimethylpropyleneurea, N-methylpyrrolidone, maleic acid, maleic anhydride, maleic anhydride imide, fumaric acid, itaconic acid, acrylic acid, methacrylic acid, glycidylmethacrylate ester, crotonic acid, and the like.

[0090] Known methods can be applied to form the "polar group," and are not particularly limited.

[0091] Examples include melt-kneading methods and methods in which each component is dissolved or dispersed in a solvent and reacted. Other methods include anionic living polymerization using polymerization initiators having functional groups or unsaturated monomers having functional groups, methods of modification by adding a modifying agent that forms or contains functional groups at the living end, and methods of reacting a conjugated diene copolymer with an organolithium compound or other organolithium metal compound (metallation reaction), and then adding a modifying agent having a functional group to the block polymer to which the organolithium metal has been added.

[0092] [Resin Composition] The resin composition of this embodiment comprises the conjugated diene copolymer (component (I)) described above, and at least one component selected from the group consisting of the following components (II), (III), and (IV). Component (II): Radical initiator Component (III): Curable resin (excluding component (I)) Component (IV): Curing agent

[0093] The resin composition of this embodiment may also contain the following components (V), (VI), and (VII): Component (V): Flame retardant Component (VI): Filler Component (VII): Crosslinking aid

[0094] (Component (II): Radical initiator) Conventional known radical initiators can be used.

[0095] For example, as thermal radical initiators, there are, but are not limited to, hydroperoxides such as diisopyrubenzene hydroperoxide (permyl P), cumene hydroperoxide (permyl H), t-butyl hydroperoxide (perbutyl H), α,α-bis(t-butylperoxy-m-isopropyl)benzene (perbutyl P), dicumyl peroxide (permyl D), 2,5-dimethyl-2,5-bis(t-butylperoxy)hexane (perhexa 25 B), t-butylcumyl peroxide (perbutyl C), di-t-butyl peroxide (perbutyl D), and 2,5-dimethyl-2,5-bis(t-butylperoxy)hexane. Examples include dialkyl peroxides such as hexyn-3 (perhexyn 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, as well as azo compounds such as 2,2-azobisisobutylnitrile, 1,1'-(cyclohexane-1-1-carbonitride), 2,2'-azobis(2-cyclopropylpropionitrile), and 2,2'-azobis(2,4-dimethylvaleronitrile).

[0096] These may be used individually or in combination of two or more types.

[0097] (Component (III): Curable Resin) Component (III): Curable resin refers to a resin that undergoes a polymerization reaction upon heating or other means, forming a polymer network structure. From the viewpoint of the polymerization reaction described above, the curable resin has multiple reactive groups. The polymerization reaction is not particularly limited, but curing by radical reaction and addition reaction or curing by radical reaction is preferred from the viewpoint of reducing dielectric loss tangent and dielectric constant. In other words, component (III): Curable resin is preferably a radical curable resin. Curing by condensation reaction tends to require highly polar reactive groups compared to radical reaction, and tends to have a lower effect on reducing dielectric loss tangent and dielectric constant.

[0098] Reactive groups that undergo curing by radical reactions are chemical groups that can generate and / or induce the formation of free radicals by the action of heat and / or light and / or free radical species of a radical initiator. For example, chemical groups that generate free radicals mainly by light and / or radical initiators are not particularly limited, but examples include benzophenone groups, benzoyl groups, groups containing an anthraquinone skeleton, and thioxanthone groups.

[0099] Furthermore, while there are no particular limitations on the chemical groups that generate free radicals in response to heat and / or light and / or radical initiators, examples include groups containing disulfide bonds and groups containing peroxy bonds. Also, while there are no particular limitations on the chemical groups that mainly generate free radicals in response to heat and / or radical initiators, examples include benzyl carbon having at least one hydrogen substituent, thiol groups, vinyl groups, groups containing alkoxyamine skeletons, groups containing azo bonds, maleimide groups, allyl groups, and methacrylic groups. From the viewpoint of radical reactivity, it is preferable that the reactive groups of the radical-curable resin include at least one reactive group selected from the group consisting of vinyl groups, maleimide groups, allyl groups, and methacrylic groups.

[0100] (Ratio of components (I) to (III)) From the viewpoint of SP value, component (I): conjugated diene copolymer tends to have better dielectric constant and dielectric loss tangent than component (III): curable resin, specifically a resin containing at least one reactive group selected from the group consisting of vinyl groups, maleimide groups, allyl groups, and methacrylic groups. Therefore, from the viewpoint of lowering the dielectric constant and dielectric loss tangent of the resin composition of this embodiment, the mass ratio of component (I) and component (III) in the resin composition of this embodiment is preferably component (I) / component (III) = 1 / 99 to 99 / 1, more preferably 10 / 90 to 80 / 20, and even more preferably 20 / 80 to 70 / 30.

[0101] Furthermore, while it is preferable that component (II): radical initiator is not included from the viewpoint of lowering dielectric constant and / or lowering dielectric loss tangent, it is possible to adjust it as needed by considering the balance between lower dielectric constant and / or lower dielectric loss tangent and heat resistance and / or adhesion to metal foil and / or coefficient of thermal expansion (CTE) depending on the radical reactivity of components (I) and (III) and / or curing temperature and / or curing time.

[0102] (Component (V): Flame retardant) The resin composition of this embodiment may further contain a flame retardant as component (V).

[0103] Furthermore, the flame retardant included as an additive to component (I) conjugated diene copolymer is synonymous with component (V) of the resin composition.

[0104] Examples of flame retardants include, but are not limited to, halogenated flame retardants such as bromine compounds, phosphorus-based flame retardants such as aromatic compounds, and flame retardants containing aromatic bromine compounds such as metal hydroxides, alkyl sulfonates, antimony trioxide, aluminum hydroxide, magnesium hydroxide, zinc borate, hexabromobenzene, decabromodiphenylethane, 4,4-dibromoviphenyl, and ethylenebistetrabromophthalimide.

[0105] These flame retardants can be used individually or in combination of two or more types.

[0106] Among the flame retardants mentioned above, there are also so-called flame retardant enhancers, which have low flame retardant effects on their own but exhibit a synergistically superior effect when used in combination with other flame retardants.

[0107] (Component (VI): Filler) The resin composition of this embodiment may further contain a filler as component (VI).

[0108] Furthermore, the filler included as an additive to component (I) conjugated diene copolymer is synonymous with component (VI) of the resin composition.

[0109] 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 fibers, glass beads, glass balloons, glass flakes, graphite, titanium dioxide, 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.

[0110] These can be used individually or in combination.

[0111] The shape of these fillers can be flaky, spherical, granular, powdery, or irregularly shaped; there are no particular restrictions.

[0112] The inclusion of a filler tends to improve the CTE, and silica is preferred as the filler. While the silica is not particularly limited, examples include amorphous silica, fused silica, crystalline silica, synthetic silica, and hollow silica.

[0113] For fillers and flame retardants, it is also possible to use types that have been pre-treated with surface treatment agents such as silane coupling agents.

[0114] The surface treatment agent is not particularly limited, but examples include fluorine-containing silane coupling agents, aminosilane coupling agents, epoxysilane coupling agents, mercaptosilane coupling agents, silane coupling agents, alkoxysilanes, organosilazane compounds, titanate coupling agents, and the like. These may be used individually or in combination.

[0115] The amount of component (VI) added can be adjusted as needed, taking into consideration the balance between lower dielectric constant and / or lower dielectric loss tangent, heat resistance and / or adhesion to metal foil and / or CTE.

[0116] (Component (VII) Crosslinking Agent) The resin composition of this embodiment may further contain a crosslinking agent as component (VII).

[0117] The crosslinking aid is not particularly limited, but for example, a low-molecular-weight compound having at least two structures with reactive groups can be used.

[0118] Furthermore, the crosslinking aid included as an additive to component (I) conjugated diene copolymer is synonymous with component (VII) of the resin composition.

[0119] Low molecular weight compounds having at least two structures containing reactive groups also have the function of reacting with component (I) and / or component (III) to cure the resin composition.

[0120] Compounds having at least two structures with reactive groups include, but are not limited to, triallyl isocyanurate (Tyke, manufactured by Mitsubishi Chemical Corporation), 1,2-bis(4-vinylphenyl)ethane, tris(2-hydroxyethyl) isocyanurate, diallyl fumarate, diallyl adipate, triallyl citrate, diallyl hexahydrophthalate, and other allyl monomers.

[0121] The amount of component (VII) added can be adjusted as needed, taking into consideration the balance between lower dielectric constant and / or lower dielectric loss tangent, heat resistance and / or adhesion to metal foil and / or CTE.

[0122] (Other additives) The resin composition of this embodiment may contain other additives.

[0123] Other additives are not particularly limited as long as they are commonly used in the formulation of resin compositions.

[0124] Other additives include, but are not limited to, pigments and / or colorants such as carbon black and titanium dioxide; lubricants such as stearic acid, behenic acid, zinc stearate, calcium stearate, magnesium stearate, and ethylenebisstearoamide; release agents; plasticizers such as organic polysiloxanes, fatty acid esters such as phthalate esters, adipic acid ester compounds, and azelaic acid ester compounds, and mineral oil; antioxidants such as hindered phenol and phosphorus-based heat stabilizers; hindered amine-based light stabilizers; benzotriazole-based ultraviolet absorbers; antistatic agents; organic fillers; thickeners; defoamers; leveling agents; resin additives such as adhesion promoters; and other additives or mixtures thereof.

[0125] From the viewpoint of achieving the aforementioned low dielectric constant and low dielectric loss tangent, it is preferable that the resin composition of this embodiment does not contain pigments, colorants, lubricants, release agents, or antistatic agents.

[0126] The resin composition in this embodiment may be a mixture of melted and kneaded components, or a mixture of components dissolved in a solvent and stirred (hereinafter referred to as "varnish"), but varnish is preferred from the viewpoint of ease of handling.

[0127] The solvents that make up the varnish are not particularly limited, but examples include ketones such as acetone, methyl ethyl ketone (MEK), cyclohexanone, and γ-butyrolactone; acetic acid esters such as ethyl acetate, butyl acetate, cellosolve acetate, propylene glycol monomethyl ether acetate, carbitol acetate, and diethyl glycol monoacetate; 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. Organic solvents may be used individually or in combination of two or more.

[0128] (Method for producing the resin composition) The method for producing the resin composition of this embodiment is not particularly limited, and known methods can be used.

[0129] Specifically, although not particularly limited, examples include a method of melting and kneading each component using a general mixer such as a Banbury mixer, single-screw extruder, twin-screw extruder, conider, or multi-screw extruder, or a method of dissolving or dispersing each component and then heating and removing the solvent. From the viewpoint of processability into molded articles suitable for electronic circuit board materials such as prepregs and resin films, which will be described later, the method of dissolving or dispersing each component and then heating and removing the solvent is preferred.

[0130] [Cured product] The cured product of this embodiment contains the conjugated diene copolymer described above.

[0131] The cured product of this embodiment is the cured product of the conjugated diene copolymer described above, or the resin composition described above.

[0132] The cured product of this embodiment is obtained by curing the above-mentioned conjugated diene copolymer or resin composition at any temperature and time. This concept includes not only completely cured products but also partially cured products containing uncured components (semi-cured products).

[0133] In the manufacturing process of the laminate described later, a further curing step may be performed on the cured material.

[0134] The reaction temperature for the curing process of the cured product in 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. If the resin composition is a varnish, it is preferable to perform the curing reaction after removing the solvent. The drying method may be carried out by conventionally known methods such as heating or hot air blowing, and it is preferable to carry it out at a temperature lower than the curing reaction temperature. The amount of solvent in the cured product is preferably 10% by mass or less, more preferably 5% by mass or less.

[0135] [Resin Film] The resin film of this embodiment contains the above-described resin composition.

[0136] The resin film of this embodiment is not particularly limited, but can be obtained, for example, by spreading a varnish made of the above-described resin composition into a uniform thin film on a suitable support, drying it, and removing the solvent. Such a resin film can be wound into a roll for storage.

[0137] The resin film of this embodiment may have a predetermined protective film laminated on it, in which case it can be used by peeling off the protective film.

[0138] The support material is not particularly limited, but examples include films made of plastic materials, metal foils, and release paper.

[0139] The film, which is made of a plastic material that serves as a support, is not particularly limited, but examples include polyesters such as polyethylene terephthalate and polyethylene naphthalate, polycarbonate, acrylics such as polymethyl methacrylate (PMMA), cyclic polyolefins, triacetylcellulose (TAC), polyether sulfide (PES), polyether ketones, and polyimides. From the viewpoint of availability and cost, polyethylene terephthalate and polyethylene naphthalate are preferred.

[0140] The metal foil is not particularly limited, but examples include copper foil and aluminum foil, with copper foil being preferred. As for the copper foil, foil made of monometallic copper may be used, or foil made of an alloy of copper with another metal (for example, tin, chromium, silver, magnesium, nickel, zirconium, silicon, titanium, etc.) may be used.

[0141] Furthermore, the support is not particularly limited, but for example, the surface that bonds with the resin composition layer may be treated with a matte finish, corona treatment, antistatic treatment, or release treatment.

[0142] [Prepreg] The prepreg of this embodiment comprises a substrate and the above-mentioned resin composition impregnated or coated onto the substrate. That is, the prepreg of this embodiment comprises a composite of the above-mentioned resin composition and the substrate.

[0143] The prepreg of this embodiment is not particularly limited, but for example, it can be obtained by impregnating a substrate such as glass cloth with the above-mentioned resin composition varnish, and then removing the solvent by the drying method described above.

[0144] The base material is not particularly limited, but examples 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 fully aromatic polyamide fibers, fully aromatic polyester fibers, and polybenzoxazole fibers; natural fiber cloths such as cotton cloth, linen cloth, and felt; natural cellulose-based base materials such as carbon fiber cloth, kraft paper, cotton paper, and cloths obtained from paper-glass blended yarns; and polytetrafluoroethylene porous films. However, glass cloth is preferred from the viewpoint of dielectric performance.

[0145] These substrates can be used individually or in combination of two or more types.

[0146] The proportion of solids consisting of the above-mentioned resin composition in the prepreg of this embodiment is preferably 30 to 80% by mass, and more preferably 40 to 70% by mass. When the proportion of solids consisting of the above-mentioned resin composition is 30% by mass or more, the prepreg tends to have even better insulation reliability when used for electronic circuit boards, etc. When the proportion of solids consisting of the above-mentioned resin composition is 80% by mass or less, the mechanical properties such as rigidity tend to be even better in applications such as electronic circuit boards.

[0147] [Laminate] The laminate of this embodiment has the resin film and metal foil described above.

[0148] Furthermore, the laminate of this embodiment may also have a configuration comprising the cured prepreg described above and a metal foil.

[0149] The laminate of this embodiment can be manufactured, for example, by the steps of (a) laminating a resin film made of the above-mentioned resin composition onto a substrate to form a resin layer and obtain a prepreg; (b) heating and pressurizing the resin layer to flatten it and obtain a cured prepreg; and (c) further forming a predetermined wiring layer made of metal foil on the resin layer.

[0150] In step (a), the method of laminating the resin film onto the substrate is not particularly limited, but examples include lamination using a multi-stage press, a vacuum press, an atmospheric pressure laminator, or a laminator that heats and pressurizes under vacuum, with the method using a laminator that heats and pressurizes under vacuum being preferred.

[0151] This laminating method allows for the creation of voids and the spaces between circuits to be filled with resin, even if the target electronic circuit board has fine wiring circuits on its surface. Furthermore, lamination can be done in batch mode or continuously using a roll or similar device.

[0152] The substrates are not limited to the following, but examples include glass epoxy substrates, metal substrates, polyester substrates, polyimide substrates, polyphenylene ether substrates, and fluororesin substrates. The surface on which the resin layer of the substrate is laminated may be roughened beforehand, and the number of substrate layers is not limited.

[0153] In step (b), the resin film and substrate laminated in step (a) are heated and pressurized to flatten them. The conditions can be arbitrarily adjusted depending on the type of substrate and the composition of the resin film, but for example, a temperature of 100 to 300°C, a pressure of 0.2 to 20 MPa, and a time of 30 to 180 minutes are preferred.

[0154] In step (c) above, a predetermined wiring layer made of metal foil is formed on the resin layer produced by heating and pressurizing the resin film and the substrate. The formation method is not particularly limited and conventionally known methods can be used, but examples include etching methods such as the subtractive method and the semi-additive method.

[0155] The subtractive method is a method for forming desired wiring by creating an etching resist layer in a shape corresponding to the desired pattern shape on a metal layer, and then dissolving and removing the metal layer in the areas where the resist has been removed using a chemical solution during a subsequent development process.

[0156] The semi-additive method involves forming a metal film on the surface of a resin layer using electroless plating, creating a plating resist layer with a shape corresponding to the desired pattern on the metal film, then forming a metal layer using electroplating, and finally removing the unnecessary electroless plating layer with a chemical solution to form the desired wiring layer.

[0157] Furthermore, holes such as via holes may be formed in the resin layer as needed, and there are no particular limitations on the method of forming the holes; conventionally known methods can be used. Examples of methods for forming the holes include NC drills, carbon dioxide lasers, UV lasers, YAG lasers, plasma, etc.

[0158] [Metal-clad laminate] The laminate of this embodiment described above may be in the form of a plate or a flexible laminate having flexibility.

[0159] The laminate in this embodiment may be a metal-clad laminate.

[0160] The metal-clad laminate is obtained by laminating the above-mentioned resin composition or prepreg with metal foil and curing it, with a portion of the metal foil removed.

[0161] Metal-clad laminates preferably have a form in which a cured prepreg (also called a "cured composite") and a metal foil are laminated and tightly bonded together, and are suitable for use as electronic circuit board materials.

[0162] While there are no particular limitations on the metal foil, examples include aluminum foil and copper foil, and among these, copper foil is preferred because of its low electrical resistance.

[0163] The cured prepreg combined with metal foil can consist of one or multiple sheets. Depending on the application, the metal foil is layered on one or both sides of the cured material to form a laminate.

[0164] The method for manufacturing the metal-clad laminate is not particularly limited, but for example, one method is to form a prepreg composed of the above-mentioned resin composition and a substrate, layer this with a metal foil, and then cure the above-mentioned resin composition to obtain a metal-clad laminate in which the cured prepreg and the metal foil are laminated.

[0165] One particularly preferred application of the metal-clad laminate is a printed circuit board. Preferably, in the printed circuit board, at least a portion of the metal foil is removed from the metal-clad laminate.

[0166] The printed circuit board is not particularly limited, but for example, it can be manufactured by a pressure-heat molding method using the prepreg described above. The same prepreg as described above can be used as the base material. By containing the resin composition described above, the printed circuit board has excellent strength and electrical properties (low dielectric constant and low dielectric loss tangent), can suppress fluctuations in electrical properties due to environmental changes, and has excellent insulation reliability and mechanical properties.

[0167] [Electronic Circuit Board Material] The electronic circuit board material of this embodiment includes a cured product of the resin composition described above.

[0168] Furthermore, the electronic circuit board material of this embodiment can be manufactured using the resin composition and / or varnish described above.

[0169] The electronic circuit board material of this embodiment includes at least one selected from the group consisting of the cured resin composition described above, the resin film described above, and the prepreg described above. The electronic circuit board material of this embodiment is not particularly limited, but can be used, for example, as a printed wiring board comprising resin-coated metal foil.

[0170] The present invention will be described in detail below with reference to specific examples and comparative examples, but the present invention is not limited in any way by the following examples and comparative examples. The methods for identifying the structure and measuring the physical properties of the conjugated diene copolymer or component (I) used in the following examples and comparative examples are shown below.

[0171] [Method for Identifying the Structure and Measuring the Physical Properties of Conjugated Diene Copolymers] ((1) Composition ratio of polymer block (A), polymer block (B), and polymer block (C) in the conjugated diene copolymer, and the amount of vinyl aromatic monomer units and conjugated diene monomer units in polymer block (C)) A sample of the polymerization solution was taken before each addition of the vinyl aromatic compound and / or conjugated diene compound constituting each polymer block to the reaction vessel. Approximately 20 mL of the sampled polymer solution was injected into a 100 mL sealed bottle containing 0.50 mL of n-propylbenzene and approximately 20 mL of toluene as internal standards to prepare a sample for measurement. The sample for measurement was measured using a gas chromatography system (Shimadzu Corporation: GC-14B) equipped with a backed column supported with apiezon grease. The amount of residual monomer in the polymer solution was determined from the calibration curves for butadiene monomer and styrene monomer obtained in advance, and it was confirmed that the polymerization rate of butadiene monomer and / or styrene monomer was 100%. Therefore, the composition ratios of polymer block (A), polymer block (B), and polymer block (C) in the conjugated diene copolymer, as well as the amount of vinyl aromatic monomer units and conjugated diene monomer units in polymer block (C), were set to be the same as the mass ratio of the added vinyl aromatic compound to the conjugated diene compound. The polymerization rate of butadiene was measured at a constant temperature of 90°C, while the polymerization rate of styrene was measured under conditions of 90°C (hold for 10 minutes) to 150°C (10°C / min).

[0172] (2) Content of vinyl aromatic monomer units and conjugated diene monomer units in conjugated diene copolymers) Using conjugated diene copolymers before hydrogenation, the content of vinyl aromatic monomer units and conjugated diene monomer units in the conjugated diene copolymers was measured using a nuclear magnetic resonance spectrometer (BRUKER, DPX-400).

[0173] (3) Amount of Units (a) (Vinyl Bond Amount) and Units (b) of the Conjugated Diene Copolymer The amount of units (a) (vinyl bond amount) was measured using an infrared spectrophotometer (JASCO Corporation, FT / IR-230) with the conjugated diene copolymer before hydrogenation. The amount of units (a) of 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 / or polymer block (C) of component (I) conjugated diene copolymer is taken as 100%. The amount of units (b) was calculated by subtracting the amount of units (a) from the amount of conjugated diene monomers in the conjugated diene copolymer mentioned above.

[0174] (4) Molecular weight of conjugated diene copolymer (I) The molecular weight of component (I) conjugated diene copolymer before modification and hydrogenation was measured by GPC [apparatus: LC-10 (Shimadzu Corporation), column: TSKgelGMHXL (4.6 mm × 30 cm)]. Tetrahydrofuran was used as the solvent. The measurement was performed at a temperature of 35°C. The molecular weight is the number average molecular weight obtained by using a calibration curve (created using the peak molecular weight of standard polystyrene) obtained from the measurement of commercially available standard polystyrene, based on the molecular weight of the peaks in the chromatogram. In cases where there are multiple peaks in the chromatogram, the molecular weight is the average molecular weight obtained 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).

[0175] (5) Molecular weight of polymer block (A) As described above, it was confirmed that the polymerization rate of butadiene monomer and / or styrene monomer was 100%. Therefore, the molecular weight of polymer block (A) was calculated using the number-average molecular weight of the conjugated diene copolymer and the polymer block (A) ratio measured as described above.

[0176] (6) Hydrogenation rate of double bonds of conjugated diene monomer units in conjugated diene copolymers (amount of unit (a1) and unit (b1)) Using the conjugated diene copolymer after hydrogenation, the hydrogenation rate of double bonds of conjugated diene monomer units was measured using a nuclear magnetic resonance spectrometer (BRUKER, DPX-400).

[0177] [Materials for Conjugated Diene Copolymers and Resin Compositions] (Preparation of Hydrogenation Catalyst) In the examples and comparative examples described later, the hydrogenation catalyst used when producing the conjugated diene copolymer was prepared by the following method. A reaction vessel equipped with a stirring device was purged with nitrogen, and 1 liter of dried and purified cyclohexane was charged into it. Next, 100 mmol of bis(η5-cyclopentadienyl)titanium dichloride was added. While stirring thoroughly, an n-hexane solution containing 200 mmol of trimethylaluminum was added, and the reaction was carried out at room temperature for about 3 days. A hydrogenation catalyst was obtained by this method.

[0178] (Component (I): Conjugated diene copolymer) Conjugated diene copolymers (X1) to (X32) were prepared as follows. The structures of each conjugated diene copolymer are shown in Tables 1 to 4.

[0179] <Example 1: Conjugated diene copolymer (X1)> Batch polymerization was carried out using a tank reactor (internal volume 10 L) equipped with a stirrer and a jacket. First, a cyclohexane solution (concentration 20% by mass) containing 12.5 parts by mass of styrene was added. Next, 0.064 parts by mass of n-butyllithium per 100 parts by mass of total monomer and 1.5 mol of tetramethylethylenediamine (TMEDA) per mole of n-butyllithium were added, and polymerization was carried out at 60°C for 15 minutes. Next, 70 parts by mass of butadiene and 17.5 parts by mass of styrene were added, and polymerization was carried out at 60°C for 70 minutes. Methanol was then added to stop the polymerization reaction, and a conjugated diene copolymer (X1) was obtained. Next, as stabilizers, octadecyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate was added at a rate of 0.25 parts by mass per 100 parts by mass of the conjugated diene polymer (X1), and 2-methyl-4,6-bis((octylthio)methyl)phenol was added at a rate of 0.08 parts by mass per 100 parts by mass of the conjugated diene polymer (X1).

[0180] <Example 2: Conjugated diene copolymer (X2)> Batch polymerization was carried out using a tank reactor (internal volume 10 L) equipped with a stirrer and a jacket. First, a cyclohexane solution (concentration 20% by mass) containing 25 parts by mass of styrene was added. Next, 0.056 parts by mass of n-butyllithium per 100 parts by mass of total monomer and 1.5 mol of tetramethylethylenediamine (TMEDA) per mole of n-butyllithium were added, and polymerization was carried out at 60°C for 25 minutes. Next, 60 parts by mass of butadiene and 15 parts by mass of styrene were added, and polymerization was carried out at 60°C for 60 minutes. Methanol was then added to stop the polymerization reaction, and a conjugated diene copolymer (X2) was obtained. Next, as stabilizers, octadecyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate was added at a rate of 0.25 parts by mass per 100 parts by mass of the conjugated diene polymer (X2), and 2-methyl-4,6-bis((octylthio)methyl)phenol was added at a rate of 0.08 parts by mass per 100 parts by mass of the conjugated diene polymer (X2).

[0181] <Example 3: Conjugated diene copolymer (X3)> Batch polymerization was carried out using a tank reactor (internal volume 10 L) equipped with a stirrer and a jacket. First, a cyclohexane solution (concentration 20% by mass) containing 62.5 parts by mass of styrene was added. Next, 0.048 parts by mass of n-butyllithium per 100 parts by mass of total monomer and 1.5 mol of tetramethylethylenediamine (TMEDA) per mole of n-butyllithium were added, and polymerization was carried out at 60°C for 40 minutes. Next, 30 parts by mass of butadiene and 7.5 parts by mass of styrene were added, and polymerization was carried out at 60°C for 45 minutes. Methanol was then added to stop the polymerization reaction, and a conjugated diene copolymer (X3) was obtained. Next, as stabilizers, octadecyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate was added at a rate of 0.25 parts by mass per 100 parts by mass of the conjugated diene polymer (X3), and 2-methyl-4,6-bis((octylthio)methyl)phenol was added at a rate of 0.08 parts by mass per 100 parts by mass of the conjugated diene polymer (X3).

[0182] <Example 4: Conjugated diene copolymer (X4)> Batch polymerization was carried out using a tank reactor (internal volume 10 L) equipped with a stirrer and a jacket. First, a cyclohexane solution (concentration 20% by mass) containing 8 parts by mass of styrene was added. Next, 0.064 parts by mass of n-butyllithium per 100 parts by mass of total monomer and 1.5 mol of tetramethylethylenediamine (TMEDA) per mole of n-butyllithium were added, and polymerization was carried out at 60°C for 15 minutes. Next, 70 parts by mass of butadiene and 14 parts by mass of styrene were added, and polymerization was carried out at 60°C for 60 minutes. Next, 8 parts by mass of styrene were added, and polymerization was carried out at 60°C for 60 minutes. After that, methanol was added to stop the polymerization reaction and obtain a conjugated diene copolymer (X4). Next, as stabilizers, octadecyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate was added at a rate of 0.25 parts by mass per 100 parts by mass of the conjugated diene polymer (X4), and 2-methyl-4,6-bis((octylthio)methyl)phenol was added at a rate of 0.08 parts by mass per 100 parts by mass of the conjugated diene polymer (X4).

[0183] <Example 5: Conjugated diene copolymer (X5)> Conjugated diene copolymer (X5) was obtained by performing the same procedure as for conjugated diene copolymer (X4), except that 0.6 mol of TMEDA was added per 1 mol of n-butyllithium.

[0184] <Example 6: Conjugated diene copolymer (X6)> A conjugated diene copolymer was prepared by the same procedure as for the conjugated diene copolymer (X4). To the conjugated diene copolymer obtained by the above method, the hydrogenation catalyst prepared as described above was added at a rate of 40 ppm Ti based on 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 0.2 hours to obtain the conjugated diene copolymer (X6). Next, as stabilizers, octadecyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate was added at a rate of 0.25 parts by mass per 100 parts by mass of the conjugated diene polymer (X6), and 2-methyl-4,6-bis((octylthio)methyl)phenol was added at a rate of 0.08 parts by mass per 100 parts by mass of the conjugated diene polymer (X6).

[0185] <Example 7: Conjugated diene copolymer (X7)> Conjugated diene copolymer (X7) was obtained by performing the same procedure as for the production of conjugated diene copolymer (X6), except that the hydrogenation reaction time was set to 0.5 hours.

[0186] <Example 8: Conjugated diene copolymer (X8)> Conjugated diene copolymer (X8) was obtained by performing the same procedure as for the production of conjugated diene copolymer (X6), except that the hydrogenation reaction time was set to 0.75 hours.

[0187] <Example 9: Conjugated diene copolymer (X9)> The same procedure as for the production of the conjugated diene copolymer (X4) was followed, except that n-butyllithium was added in an amount of 0.16 parts by mass per 100 parts by mass of the total monomer.

[0188] <Example 10: Conjugated diene copolymer (X10)> Batch polymerization was carried out using a tank reactor (internal volume 10 L) equipped with a stirrer and a jacket. First, a cyclohexane solution (concentration 20% by mass) containing 4.4 parts by mass of styrene was added. Next, 0.064 parts by mass of n-butyllithium per 100 parts by mass of total monomer and 1.5 mol of tetramethylethylenediamine (TMEDA) per mole of n-butyllithium were added, and polymerization was carried out at 60°C for 10 minutes. Next, 65 parts by mass of butadiene and 16.3 parts by mass of styrene were added, and polymerization was carried out at 60°C for 60 minutes. Next, 4.4 parts by mass of styrene were added, and polymerization was carried out at 60°C for 10 minutes. Next, 10 parts by mass of butadiene were added, and polymerization was carried out at 60°C for 15 minutes. After that, methanol was added to stop the polymerization reaction, and the conjugated diene copolymer (X10) was obtained. Next, as stabilizers, octadecyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate was added at a rate of 0.25 parts by mass per 100 parts by mass of the conjugated diene polymer (X10), and 2-methyl-4,6-bis((octylthio)methyl)phenol was added at a rate of 0.08 parts by mass per 100 parts by mass of the conjugated diene polymer (X10).

[0189] <Example 11: Conjugated diene copolymer (X11)> Batch polymerization was carried out using a tank 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 styrene was added. Next, 0.066 parts by mass of n-butyllithium per 100 parts by mass of total monomer and 1.5 mol of tetramethylethylenediamine (TMEDA) per mole of n-butyllithium were added, and polymerization was carried out at 60°C for 15 minutes. Next, 60 parts by mass of butadiene and 15 parts by mass of styrene were added, and polymerization was carried out at 60°C for 60 minutes. Next, 7.5 parts by mass of styrene were added, and polymerization was carried out at 60°C for 15 minutes. Next, 10 parts by mass of butadiene were added, and polymerization was carried out at 60°C for 10 minutes. After that, methanol was added to stop the polymerization reaction, and the conjugated diene copolymer (X11) was obtained. Next, as stabilizers, octadecyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate was added at a rate of 0.25 parts by mass per 100 parts by mass of the conjugated diene polymer (X10), and 2-methyl-4,6-bis((octylthio)methyl)phenol was added at a rate of 0.08 parts by mass per 100 parts by mass of the conjugated diene polymer (X10).

[0190] <Example 12: Conjugated diene copolymer (X12)> A conjugated diene copolymer was prepared by the same procedure as for the production of the conjugated diene copolymer (X11). To the conjugated diene copolymer obtained by the above method, the hydrogenation catalyst prepared as described above was added at a rate of 60 ppm Ti based on 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 the conjugated diene copolymer (X12). Next, as stabilizers, octadecyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate was added at a rate of 0.25 parts by mass per 100 parts by mass of the conjugated diene copolymer (X12), and 2-methyl-4,6-bis((octylthio)methyl)phenol was added at a rate of 0.08 parts by mass per 100 parts by mass of the conjugated diene copolymer (X12).

[0191] <Example 13: Conjugated diene copolymer (X13)> Batch polymerization was carried out using a tank 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, 0.066 parts by mass of n-butyllithium per 100 parts by mass of total monomer and 1.5 mol of tetramethylethylenediamine (TMEDA) per mole of n-butyllithium were added, and polymerization was carried out at 60°C for 15 minutes. Next, 40 parts by mass of butadiene and 10 parts by mass of styrene were added, and polymerization was carried out at 60°C for 45 minutes. Next, 10 parts by mass of styrene was added, and polymerization was carried out at 60°C for 15 minutes. Next, 30 parts by mass of butadiene was added, and polymerization was carried out at 60°C for 25 minutes. After that, methanol was added to stop the polymerization reaction, and the conjugated diene copolymer (X13) was obtained. Next, as stabilizers, octadecyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate was added at a rate of 0.25 parts by mass per 100 parts by mass of the conjugated diene polymer (X10), and 2-methyl-4,6-bis((octylthio)methyl)phenol was added at a rate of 0.08 parts by mass per 100 parts by mass of the conjugated diene polymer (X10).

[0192] <Example 14: Conjugated diene copolymer (X14)> The same procedure as for the production of conjugated diene copolymer (X13) was followed, except that 0.05 mol of sodium t-pentoxide (NaOAm) was added to 1 mole of n-butyllithium. Conjugated diene copolymer (X14) was obtained by the above method.

[0193] <Example 15: Conjugated diene copolymer (X15)> Batch polymerization was carried out using a tank reactor (internal volume 10 L) equipped with a stirrer and a jacket. First, a cyclohexane solution (concentration 20% by mass) containing 25 parts by mass of styrene was added. Next, 0.048 parts by mass of n-butyllithium per 100 parts by mass of total monomer and 1.5 mol of tetramethylethylenediamine (TMEDA) per mole of n-butyllithium were added, and polymerization was carried out at 60°C for 25 minutes. Next, 20 parts by mass of butadiene and 20 parts by mass of styrene were added, and polymerization was carried out at 60°C for 25 minutes. Next, 25 parts by mass of styrene were added, and polymerization was carried out at 60°C for 25 minutes. Next, 10 parts by mass of butadiene were added, and polymerization was carried out at 60°C for 10 minutes. After that, methanol was added to stop the polymerization reaction, and the conjugated diene copolymer (X15) was obtained. Next, as stabilizers, octadecyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate was added at a rate of 0.25 parts by mass per 100 parts by mass of the conjugated diene polymer (X15), and 2-methyl-4,6-bis((octylthio)methyl)phenol was added at a rate of 0.08 parts by mass per 100 parts by mass of the conjugated diene polymer (X15).

[0194] <Example 16: Conjugated diene copolymer (X16)> The same procedure as for the production of conjugated diene copolymer (X11) was carried out, except that n-butyllithium was used in an amount of 0.032 parts by mass per 100 parts by mass of total monomer. Conjugated diene copolymer (X16) was obtained by the above method.

[0195] <Comparative Example 1: Conjugated diene copolymer (X17)> Batch polymerization was carried out using a tank reactor (internal volume 10 L) equipped with a stirrer and a jacket. First, a cyclohexane solution (concentration 20% by mass) containing 30 parts by mass of styrene was added. Next, 0.064 parts by mass of n-butyllithium per 100 parts by mass of total monomer and 1.5 mol of tetramethylethylenediamine (TMEDA) per mole of n-butyllithium were added, and polymerization was carried out at 60°C for 30 minutes. Next, 70 parts by mass of butadiene was added, and polymerization was carried out at 60°C for 60 minutes. Then methanol was added to stop the polymerization reaction, and a conjugated diene copolymer (X17) was obtained. Next, as stabilizers, octadecyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate was added at a rate of 0.25 parts by mass per 100 parts by mass of the conjugated diene polymer (X17), and 2-methyl-4,6-bis((octylthio)methyl)phenol was added at a rate of 0.08 parts by mass per 100 parts by mass of the conjugated diene polymer (X17).

[0196] <Comparative Example 2: Conjugated diene copolymer (X18)> The same procedure as for the production of conjugated diene copolymer (X1) was carried out, except that n-butyllithium was used in an amount of 0.027 parts by mass per 100 parts by mass of total monomer. Conjugated diene copolymer (X18) was obtained by the above procedure.

[0197] <Comparative Example 3: Conjugated diene copolymer (X19)> Batch polymerization was carried out using a tank reactor (internal volume 10 L) equipped with a stirrer and a jacket. First, a cyclohexane solution (concentration 20% by mass) containing 75 parts by mass of styrene was added. Next, 0.044 parts by mass of n-butyllithium per 100 parts by mass of total monomer and 1.5 mol of tetramethylethylenediamine (TMEDA) per mole of n-butyllithium were added, and polymerization was carried out at 60°C for 60 minutes. Next, 20 parts by mass of butadiene and 5 parts by mass of styrene were added, and polymerization was carried out at 60°C for 20 minutes. Methanol was then added to stop the polymerization reaction, and a conjugated diene copolymer (X19) was obtained. Next, as stabilizers, octadecyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate was added at a rate of 0.25 parts by mass per 100 parts by mass of the conjugated diene polymer (X19), and 2-methyl-4,6-bis((octylthio)methyl)phenol was added at a rate of 0.08 parts by mass per 100 parts by mass of the conjugated diene polymer (X19).

[0198] <Comparative Example 4: Conjugated diene copolymer (X20)> The same procedure as for the production of the conjugated diene copolymer (X11) was followed, except that TMEDA was not added. The conjugated diene copolymer (X20) was obtained by the above method.

[0199] <Comparative Example 5: Conjugated diene copolymer (X21)> Batch polymerization was carried out using a tank reactor (internal volume 10 L) equipped with a stirrer and a jacket. First, a cyclohexane solution (concentration 20% by mass) containing 6.1 parts by mass of styrene was added. Next, 0.070 parts by mass of n-butyllithium per 100 parts by mass of total monomer and 1.5 mol of tetramethylethylenediamine (TMEDA) per mole of n-butyllithium were added, and polymerization was carried out at 60°C for 10 minutes. Next, 85 parts by mass of butadiene and 8.9 parts by mass of styrene were added, and polymerization was carried out at 60°C for 70 minutes. Methanol was then added to stop the polymerization reaction, and a conjugated diene copolymer (X21) was obtained. Next, as stabilizers, octadecyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate was added at a rate of 0.25 parts by mass per 100 parts by mass of the conjugated diene polymer (X21), and 2-methyl-4,6-bis((octylthio)methyl)phenol was added at a rate of 0.08 parts by mass per 100 parts by mass of the conjugated diene polymer (X21). In the production of the resin compositions and cured products described later, the conjugated diene polymers of Examples 1 to 16 and Comparative Examples 1 to 5 with added stabilizers were used as component (I).

[0200] <Example 49: Conjugated diene copolymer (X22)> Batch polymerization was carried out using a tank reactor (internal volume 10 L) equipped with a stirrer and a jacket. First, a cyclohexane solution (concentration 20% by mass) containing 30 parts by mass of styrene was added. Next, 0.13 parts by mass of n-butyllithium per 100 parts by mass of total monomer and 1.0 mol of tetramethylethylenediamine (TMEDA) per mole of n-butyllithium were added, and polymerization was carried out at 60°C for 5 minutes. Next, a cyclohexane solution (concentration 20% by mass) containing 37.5 parts by mass of butadiene and 25 parts by mass of styrene was added, and polymerization was carried out at 60°C for 35 minutes. Then, a cyclohexane solution (concentration 20% by mass) containing 7.5 parts by mass of butadiene was added, and polymerization was carried out at 60°C for 7 minutes. After that, methanol was added to stop the polymerization reaction and a conjugated diene copolymer (x22) was obtained. The conjugated diene copolymer (x22) obtained as described above has a styrene content of 55% by mass, a vinyl aromatic monomer content of 40% by mass per 100 parts by mass of polymer block (C), and a weight-average molecular weight of 6.5 × 10⁻⁶. ４ The content of unit (a) derived from 1,2-bonds and / or 3,4-bonds (vinyl bond content: unit (a) / butadiene) was 60%. Using the obtained conjugated diene copolymer (x22), the hydrogenation catalyst prepared as described above was added at a rate of 90 ppm on a Ti basis per 100 parts by mass of the conjugated diene block copolymer, and the hydrogenation reaction was carried out at a hydrogen pressure of 0.7 MPa and a temperature of 80°C for about 0.3 hours to obtain hydrogenated conjugated diene block copolymer (X22). The hydrogenation rate was 30%.

[0201] <Example 50: Conjugated diene copolymer (X23)> The same procedure as for the production of conjugated diene copolymer (X11) was carried out, except that n-butyllithium was used in an amount of 0.044 parts by mass per 100 parts by mass of total monomer. Conjugated diene copolymer (X23) was obtained by the above method.

[0202] <Example 51: Conjugated diene copolymer (X24)> Batch polymerization was carried out using a tank reactor (internal volume 10 L) equipped with a stirrer and a jacket. First, a cyclohexane solution (concentration 20% by mass) containing 8.75 parts by mass of styrene was added. Next, 0.066 parts by mass of n-butyllithium per 100 parts by mass of total monomer and 1.5 mol of tetramethylethylenediamine (TMEDA) per mole of n-butyllithium were added, and polymerization was carried out at 60°C for 15 minutes. Next, 50 parts by mass of butadiene and 12.5 parts by mass of styrene were added, and polymerization was carried out at 60°C for 60 minutes. Then, 8.75 parts by mass of styrene was added, and polymerization was carried out at 60°C for 15 minutes. Finally, 20 parts by mass of butadiene was added, and polymerization was carried out at 60°C for 10 minutes. After that, methanol was added to stop the polymerization reaction and a conjugated diene copolymer (X24) was obtained. Next, as stabilizers, octadecyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate was added at a rate of 0.25 parts by mass per 100 parts by mass of the conjugated diene copolymer (X24), and 2-methyl-4,6-bis((octylthio)methyl)phenol was added at a rate of 0.08 parts by mass per 100 parts by mass of the conjugated diene copolymer (X24).

[0203] <Example 52: Conjugated diene copolymer (X25)> Batch polymerization was carried out using a tank reactor (internal volume 10 L) equipped with a stirrer and a jacket. First, a cyclohexane solution (concentration 20% by mass) containing 9.35 parts by mass of styrene was added. Next, 0.066 parts by mass of n-butyllithium per 100 parts by mass of total monomer and 1.5 mol of tetramethylethylenediamine (TMEDA) per mole of n-butyllithium were added, and polymerization was carried out at 60°C for 15 minutes. Next, 55 parts by mass of butadiene and 16.3 parts by mass of styrene were added, and polymerization was carried out at 60°C for 60 minutes. Next, 9.35 parts by mass of styrene were added, and polymerization was carried out at 60°C for 15 minutes. Next, 10 parts by mass of butadiene were added, and polymerization was carried out at 60°C for 10 minutes. Thereafter, methanol was added to stop the polymerization reaction, and the conjugated diene copolymer (X25) was obtained. Next, as stabilizers, octadecyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate was added at a rate of 0.25 parts by mass per 100 parts by mass of the conjugated diene copolymer (X25), and 2-methyl-4,6-bis((octylthio)methyl)phenol was added at a rate of 0.08 parts by mass per 100 parts by mass of the conjugated diene copolymer (X25).

[0204] <Example 53: Conjugated diene copolymer (X26)> Batch polymerization was carried out using a tank reactor (internal volume 10 L) equipped with a stirrer and a jacket. First, a cyclohexane solution (concentration 20% by mass) containing 11.85 parts by mass of styrene was added. Next, 0.066 parts by mass of n-butyllithium per 100 parts by mass of total monomer and 1.5 mol of tetramethylethylenediamine (TMEDA) per mole of n-butyllithium were added, and polymerization was carried out at 60°C for 15 minutes. Next, 45 parts by mass of butadiene and 11.3 parts by mass of styrene were added, and polymerization was carried out at 60°C for 60 minutes. Next, 11.85 parts by mass of styrene was added, and polymerization was carried out at 60°C for 15 minutes. Next, 20 parts by mass of butadiene was added, and polymerization was carried out at 60°C for 10 minutes. After that, methanol was added to stop the polymerization reaction, and the conjugated diene copolymer (X26) was obtained. Next, as stabilizers, octadecyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate was added at a rate of 0.25 parts by mass per 100 parts by mass of the conjugated diene polymer (X10), and 2-methyl-4,6-bis((octylthio)methyl)phenol was added at a rate of 0.08 parts by mass per 100 parts by mass of the conjugated diene copolymer (X26).

[0205] <Example 54: Conjugated diene copolymer (X27)> The same procedure as for the production of conjugated diene copolymer (X11) was carried out, except that n-butyllithium was used in an amount of 0.051 parts by mass per 100 parts by mass of total monomer. Conjugated diene copolymer (X27) was obtained by the above method.

[0206] <Example 55: Conjugated diene copolymer (X28)> The same procedure as for the production of conjugated diene copolymer (X11) was carried out, except that n-butyllithium was used in an amount of 0.040 parts by mass per 100 parts by mass of total monomer. Conjugated diene copolymer (X28) was obtained by the above method.

[0207] <Example 56: Conjugated diene copolymer (X29)> The same procedure as for the production of conjugated diene copolymer (X12) was followed, except that the hydrogenation reaction time was 0.25 hours. Conjugated diene copolymer (X29) was obtained by the above method.

[0208] <Example 57: Conjugated diene copolymer (X30)> The same procedure as for the production of conjugated diene copolymer (X10) was followed, except that n-butyllithium was added in an amount of 0.062 parts by mass per 100 parts by mass of total monomer, and TMEDA was added in an amount of 0.7 mol per mole of n-butyllithium. Conjugated diene copolymer (X30) was obtained by the above method.

[0209] <Example 58: Conjugated diene copolymer (X31)> The same procedure as for the production of conjugated diene copolymer (X25) was carried out, except that n-butyllithium was used in an amount of 0.094 parts by mass per 100 parts by mass of total monomer. Conjugated diene copolymer (X31) was obtained by the above method.

[0210] <Example 59: Conjugated diene copolymer (X32)> Batch polymerization was carried out using a tank 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 styrene was added. Next, 0.066 parts by mass of n-butyllithium per 100 parts by mass of total monomer and 1.5 mol of tetramethylethylenediamine (TMEDA) per mole of n-butyllithium were added and polymerized at 60°C for 15 minutes. Then, 10 parts by mass of butadiene was added and polymerized at 60°C for 10 minutes, 7.5 parts by mass of styrene was added and polymerized at 60°C for 15 minutes, 60 parts by mass of butadiene and 15 parts by mass of styrene were added and polymerized at 60°C for 60 minutes. After that, methanol was added to stop the polymerization reaction and a conjugated diene copolymer (X32) was obtained. Next, as stabilizers, octadecyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate was added at a rate of 0.25 parts by mass per 100 parts by mass of the conjugated diene copolymer (X32), and 2-methyl-4,6-bis((octylthio)methyl)phenol was added at a rate of 0.08 parts by mass per 100 parts by mass of the conjugated diene copolymer (X32).

[0211] (Component (II): Radical initiator) Perbutyl P (manufactured by NOF Corporation)

[0212] (Component (III): Curable resin) Polyphenylene ether (PPE) resin: OPE-2St 1200 (manufactured by Mitsubishi Gas Chemical Co., Ltd.) The PPE resin (Component (III)) was polymerized as follows: A 1.5-liter jacketed reactor equipped with a sparger for introducing oxygen-containing gas at the bottom of the reactor, stirring turbine blades and baffles, and a reflux condenser in the vent gas line at the top of the reactor was filled with 0.2512 g of cupric chloride dihydrate, 1.1062 g of 35% hydrochloric acid, 3.6179 g of di-n-butylamine, 9.5937 g of N,N,N',N'-tetramethylpropanediamine, 211.63 g of methanol and 493.80 g of n-butanol, and 180.0 g of 2,6-dimethylphenol containing 5 mol% 2,2-bis(3,5-dimethyl-4-hydroxyphenyl)propane. The solvent composition mass ratio used was n-butanol:methanol = 70:30. Oxygen was then introduced into the reactor at a rate of 180 mL / min via a sparger while vigorously stirring. Simultaneously, the polymerization temperature was maintained at 40°C by passing a heat transfer medium through the jacket. The polymerization solution gradually took on a slurry-like state. When the polyphenylene ether reached the desired number-average molecular weight, the aeration of the oxygen-containing gas was stopped, and the resulting polymerization mixture was heated to 50°C. Hydroquinone (reagent from Wako Pure Chemical Industries, Ltd.) was then added in small amounts, and the mixture was kept warm at 50°C until the slurry-like polyphenylene ether turned white. Next, 720 g of a methanol solution containing 6.5% by mass of 36% hydrochloric acid was added, filtered, and repeatedly washed with methanol to obtain wet polyphenylene ether. Finally, it was vacuum-dried at 100°C to obtain dry polyphenylene ether. ηsp / c was 0.103 dl / g, and the yield was 97%. The ηsp / c was measured by determining the reduced viscosity (ηsp / c) at 30°C using an Ubbelohde viscous tube with the aforementioned polyphenylene ether as a 0.5 g / dl chloroform solution. The unit is dl / g. The obtained polyphenylene ether was modified as follows: 152.5 g of polyphenylene ether and 152.5 g of toluene were mixed and heated to approximately 85°C. Then 2.1 g of dimethylaminopyridine was added. Once all the solid had dissolved, 18.28 g of methacrylic anhydride was gradually added.The obtained solution was maintained at 85°C for 3 hours while being continuously mixed. The solution was then cooled to room temperature to obtain a toluene solution of methacrylate-sealed polyphenylene ether. 1000 mL of methanol at 10°C was added dropwise to the obtained toluene solution in a 3 L cylindrical stainless steel container equipped with a homogenizer for stirring. The resulting powder was filtered, washed with methanol, and dried under nitrogen at 85°C for 18 hours to obtain methacrylate-sealed polyphenylene ether (component (III)). The reactive groups of the obtained radical-curable resin, component (III), contained methacrylate groups.

[0213] (Component (VI): Filler) Silica: SOC2 (manufactured by Admatex)

[0214] (Component (VII) Crosslinking Aid) Triallyl isocyanurate (TAIC, manufactured by Mitsubishi Chemical Corporation) [Resin composition and cured product]

[0215] <Examples 17-48, 60-79, Comparative Examples 6-15> Using the components (I): conjugated diene copolymer obtained in Examples 1-16, 49-59 and Comparative Examples 1-5, and components (II), (III), (VI), and (VII), resin compositions and cured products were prepared as follows.

[0216] [Preparation of Varnish] Using each component (I): conjugated diene copolymer obtained in Examples 1-16, 49-59 and Comparative Examples 1-5, each component was measured into a container according to the formulations shown in Tables 5-8 below, dissolved in toluene (manufactured by Wako Pure Chemical Industries, Ltd.), and stirred to prepare a varnish containing the resin composition. At that time, the concentration of the resin composition in the varnish was adjusted to 40-60% by mass. In Tables 5-8, the unit "parts" for the blending ratio of components (II) and (VI) is the mass ratio to the total mass of components (I), (III), and (VII) "100 parts by mass".

[0217] [Preparation of Cured Film] The component ratios are shown in Tables 5 to 8. First, each component was added to toluene, stirred, and dissolved to prepare a varnish with a concentration of 20% to 50% by mass. The varnish was coated onto a Teflon® sheet at a speed of 30 mm / second, and then dried in a forced-air dryer under a nitrogen flow at 100°C for 10 minutes to obtain a film. The obtained film was subjected to a curing reaction in a forced-air dryer under a nitrogen flow at 200°C for 120 minutes to obtain a cured film. The cured film was used as an evaluation sample.

[0218] [Preparation of a laminate of cured film and copper foil] After drying the film under the aforementioned nitrogen atmosphere, the film was sandwiched between two copper foils, and the temperature was raised to 200°C at a heating rate of 2°C / min. A laminate consisting of copper foil / cured film / copper foil was then prepared by heating and pressurizing under the conditions of 200°C, 2 hours, and a pressure of 3 MPa.

[0219] [Measurement Method for Physical Properties of Resin Compositions, etc.] ((1) Dielectric Loss Tangent) The dielectric loss tangent of the above-mentioned cured film at 10 GHz was measured using the cavity resonance method. A network analyzer (N5230A, manufactured by Agilent Technologies) and a cavity resonator (Cavity Resonator CP series) manufactured by Kanto Electronics Applied Development Co., Ltd. were used as the measuring devices. The measurement sample was a test piece measuring 2.6 mm wide x 80 mm long cut from the prepreg as described in the above-mentioned manufacturing method. The dielectric loss tangent (Df) obtained from the above measurement was evaluated on a 5-point scale according to the following criteria. A larger value indicates better dielectric loss tangent (lower dielectric loss). 5: Dielectric loss tangent is less than 0.0033. 4: Dielectric loss tangent is less than 0.0040 and 0.0033 or more. 3: Dielectric loss tangent is less than 0.0045 and 0.0040 or more. 2: The dielectric loss tangent is less than 0.0050 and 0.0045 or greater. 1: The dielectric loss tangent is 0.0050 or greater.

[0220] (2) Strength (Tensile Strength), Toughness (Tensile Elongation at Break) The cured film described above was punched into a JIS No. 1 dumbbell and subjected to a tensile test at room temperature at a tensile speed of 1 mm / min to calculate the tensile strength (unit: MPa) and tensile elongation at break (unit: mm). Using the tensile strength obtained above, the resin compositions of the above-mentioned examples and comparative examples were evaluated according to the following criteria. A higher numerical value indicates better strength and toughness. (Evaluation criteria for tensile strength (strength)) 5: Tensile strength is 50 MPa or more. 4: Tensile strength is 45 MPa or more and less than 50 MPa. 3: Tensile strength is 40 MPa or more and less than 45 MPa. 2: Tensile strength is 35 MPa or more and less than 40 MPa. 1: Tensile strength is less than 35 MPa. (Evaluation criteria for tensile elongation at break (toughness)) 5: Tensile elongation at break is 2.5 mm or more. 4: Tensile elongation at break is 2.2 mm or more and less than 2.5 mm. 3: Tensile elongation at break is 1.8 mm or more and less than 2.2 mm. 2: Tensile elongation at break is 1.5 mm or more and less than 1.8 mm. 1: Tensile elongation at break is less than 1.5 mm.

[0221] (3) Pressure Cooker Test (PCT) The laminate of copper foil and cured film described above was exposed to 110°C and 110% RH for 2 hours. After that, it was immersed in a solder bath at 288°C for 30 seconds, and the appearance was observed to evaluate the solder heat resistance and moisture resistance according to the following criteria. A higher number indicates better solder heat resistance and moisture resistance. (Evaluation criteria for solder heat resistance and moisture resistance) 4: No blistering of copper foil 3: Slight blistering of copper foil 2: Blistering of copper foil present 1: Peeling of copper foil present

[0222] (4) Coefficient of Thermal Expansion (CTE) The above-mentioned cured film was cut into 5 mm x 25 mm pieces, and the CTE was measured using a TMA (TMA-SS7100, manufactured by SII Nanotechnology). The probe was set to tensile strength, the measurement temperature was from 15°C to 150°C, the heating rate was 5°C / min, the measurement load was 1 g, and scanning was performed twice. The CTE (ppm / °C) in the range of 25 to 150°C was determined from the chart obtained from the second heating. The CTE obtained as described above was evaluated according to the following criteria: 5: 7 ppm / °C or less 4: greater than 7 ppm / °C, 10 ppm / °C or less 3: greater than 10 ppm / °C, 13 ppm / °C or less 2: greater than 13 ppm / °C, 16 ppm / °C or less 1: greater than 16 ppm / °C

[0223] (5) Adhesion to copper foil A 1 cm wide cut was made on one side of the laminate of the copper foil and cured film described above, and the strength when the copper foil was peeled off at 90° was measured using a tensile testing machine. The tensile speed was set to 50 cm / mm. The adhesion to copper foil was evaluated from the obtained strength according to the following criteria: 5: 0.7 N / mm or more 4: 0.6 N / mm or more, less than 0.7 N / mm 3: 0.5 N / mm or more, less than 0.6 N / mm 2: 0.4 N / mm or more, less than 0.5 N / mm 1: less than 0.4 N / mm

[0224]

[0225]

[0226]

[0227]

[0228]

[0229]

[0230]

[0231]

[0232] The conjugated diene copolymers of the examples were found to have an excellent balance of dielectric properties (low dielectric loss), strength, and solder heat and moisture resistance as cured products. Therefore, the present invention is suitable for applications such as glass cloth, films, and printed circuit boards using metal laminates with cured products.

[0233] This application is based on Japanese Patent Application No. 2025-051678 filed on March 26, 2025, the contents of which are incorporated herein by reference.

[0234] The conjugated diene copolymer, the resin composition containing the conjugated diene copolymer, and the cured product of the present invention have industrial applicability as materials for films, prepregs, electronic circuit boards, and next-generation communication substrates.

Claims

1. A conjugated diene copolymer comprising a polymer block (A) mainly composed of vinyl aromatic monomer units and a random polymer block (C) mainly composed of vinyl aromatic monomer units and conjugated diene monomer units, and satisfying the following conditions (i) to (iii): <Condition (i)> The amount of vinyl aromatic monomer units in the conjugated diene copolymer is 20% by mass or more and 75% by mass or less. <Condition (ii)> The number average molecular weight (Mn) of the conjugated diene copolymer is 30,000 or more and 300,000 or less. <Condition (iii)> The conjugated diene monomer units in the conjugated diene copolymer include units (a) derived from 1,2-bonds and / or 3,4-bonds and units (b) derived from 1,4-bonds, and the amount of unit (a) in 100 g of the conjugated diene copolymer is 0.15 mol or more and 1.2 mol or less.

2. The conjugated diene copolymer according to claim 1, satisfying the following formula (i): 15 ≤ (a / (a ​​+ b + a1 + b1)) × 100 < 80 ... formula (i) a: Amount (mol) of unit (a) in 100 g of the conjugated diene copolymer a1: Amount (mol) of hydrogenated alkenyl monomer units of unit (a) in 100 g of the conjugated diene copolymer b: Amount (mol) of unit (b) in 100 g of the conjugated diene copolymer b1: Amount (mol) of hydrogenated alkenyl monomer units of unit (b) in 100 g of the conjugated diene copolymer 3. The conjugated diene copolymer according to claim 1, satisfying the following formula (iii): 35 ≤ (a / (a ​​+ b + a1 + b1)) × 100 < 80 ... formula (iii) a: Amount (mol) of unit (a) in 100 g of the conjugated diene copolymer a1: Amount (mol) of hydrogenated alkenyl monomer units of unit (a) in 100 g of the conjugated diene copolymer b: Amount (mol) of unit (b) in 100 g of the conjugated diene copolymer b1: Amount (mol) of hydrogenated alkenyl monomer units of unit (b) in 100 g of the conjugated diene copolymer 4. The conjugated diene copolymer according to claim 2, further satisfying the following formula (ii): 0 ≤ a1 + b1 < a + b ... formula (ii) a: amount of unit (a) in 100 g of the conjugated diene copolymer (mol) a1: amount of hydrogenated alkenyl monomer units of unit (a) in 100 g of the conjugated diene copolymer (mol) b: amount of unit (b) in 100 g of the conjugated diene copolymer (mol) b1: amount of hydrogenated alkenyl monomer units of unit (b) in 100 g of the conjugated diene copolymer (mol) 5. The conjugated diene copolymer according to any one of claims 1 to 3, wherein the conjugated diene monomer unit in the conjugated diene copolymer comprises a unit (a) derived from a 1,2-bond and / or a 3,4-bond and a unit (b) derived from a 1,4-bond, and the amount of unit (a) in 100 g of the conjugated diene copolymer is 0.55 mol or more and 1.2 mol or less.

6. The conjugated diene copolymer according to any one of claims 1 to 3, wherein the amount of vinyl aromatic monomer units in the conjugated diene copolymer is 20% by mass or more and less than 45% by mass.

7. The conjugated diene copolymer according to any one of claims 1 to 3, wherein the amount of vinyl aromatic monomer units in the conjugated diene copolymer is 20% by mass or more and less than 40% by mass.

8. The conjugated diene copolymer according to any one of claims 1 to 3, wherein the amount of vinyl aromatic monomer units in the polymer block (C) is 10% by mass or more and 60% by mass or less.

9. The conjugated diene copolymer according to any one of claims 1 to 3, wherein the amount of vinyl aromatic monomer units in the polymer block (C) is 10% by mass or more and less than 45% by mass.

10. The conjugated diene copolymer according to any one of claims 1 to 3, further comprising a polymer block (B) mainly composed of conjugated diene monomer units.

11. The conjugated diene copolymer according to claim 10, wherein the content of the polymer block (B) in the conjugated diene copolymer is 25% by mass or less.

12. The conjugated diene copolymer according to claim 11, wherein the conjugated diene copolymer contains two or more polymer blocks (A), and at least one terminal is polymer block (B).

13. A conjugated diene copolymer according to any one of claims 1 to 3, wherein the number average molecular weight (Mn) is 65,000 or more and 300,000 or less.

14. A conjugated diene copolymer according to any one of claims 1 to 3, wherein the number average molecular weight (Mn) is 70,000 or more and 250,000 or less.

15. The conjugated diene copolymer according to any one of claims 1 to 3, wherein the number average molecular weight of the polymer block (A) is 3000 or more.

16. The conjugated diene copolymer according to any one of claims 1 to 3, comprising at least two polymer blocks (A).

17. Component (I): A resin composition comprising the conjugated diene copolymer described in claim 1 and at least one selected from the group consisting of the following components (II), (III), and (IV). Component (II): Radical initiator Component (III): Curable resin (excluding component (I)) Component (IV): Curing agent 18. The resin composition according to claim 17, wherein the component (III) is a radical-curable resin.

19. The resin composition according to claim 18, wherein the reactive group of the radical-curable resin, which is component (III), comprises at least one reactive group selected from the group consisting of vinyl group, maleimide group, allyl group, and methacrylic group.

20. A cured product comprising the conjugated diene copolymer described in claim 1.

21. A cured resin product comprising the resin composition according to claim 17 or 18.

22. A resin film comprising the resin composition according to claim 17.

23. A prepreg comprising a composite of a substrate and the resin composition described in claim 17 or 18.

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

25. An electronic circuit board material comprising the cured product according to claim 20 and / or the resin film according to claim 22.

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