JP7799031B2 - Block copolymers, resin compositions, cured products, resin films, prepregs, laminates, and materials for electronic circuit boards - Google Patents

Description

The present invention relates to block copolymers, resin compositions, cured products, resin films, prepregs, laminates, and materials for electronic circuit boards.

2. Description of the Related Art In recent years, with the remarkable progress in information network technology and the expansion of services utilizing information networks, electronic devices are required to handle larger amounts of information and to process faster.
To meet these demands, materials with low dielectric loss are required for various substrates such as printed circuit boards and flexible substrates.

In order to obtain materials with low dielectric loss, cured resins containing, as their main component, a thermosetting resin such as an epoxy resin, which has a low dielectric constant and/or a low dielectric dissipation factor and excellent mechanical properties such as strength, or a thermoplastic resin such as a polyphenylene ether resin, have been studied and disclosed.
However, the materials disclosed so far still have room for improvement in terms of low dielectric constant and low dielectric loss tangent, and when these materials are used in printed circuit boards, there is a problem that the amount of information and processing speed are limited.

To overcome these problems, various rubber components have been proposed as modifiers for the above-mentioned thermosetting resins and thermoplastic resins.
For example, Patent Document 1 discloses at least one elastomer selected from the group consisting of block copolymers of vinyl aromatic compounds and olefinic alkene compounds, hydrogenated products thereof, and homopolymers of vinyl aromatic compounds, as a modifier for lowering the dielectric loss tangent and dielectric constant of polyphenylene ether resins.
Furthermore, Patent Document 2 discloses a styrene-based elastomer as a modifier for lowering the dielectric loss tangent and dielectric constant of an epoxy resin.

Japanese Patent Application Laid-Open No. 2021-147486 Japanese Patent Application Laid-Open No. 2020-15861

However, resin compositions using the modifiers disclosed in Patent Documents 1 and 2 still do not have a sufficiently low dielectric constant or low dielectric loss tangent, and the addition of these modifiers reduces the strength of the resin composition, making it difficult to achieve sufficient strength.

The present invention therefore aims to provide a block copolymer and a resin composition containing the block copolymer that produce a cured product with a low dielectric constant, low dielectric tangent, and excellent strength properties.

As a result of intensive research aimed at solving the problems of the conventional art described above, the present inventors have found that a cured product of a resin composition containing a block copolymer having a predetermined structure has a low dielectric constant and a low dielectric dissipation factor, and also has excellent strength properties, thereby completing the present invention.
That is, the present invention is as follows.

[1]
a polymer block (C) which is a random block consisting of vinyl aromatic monomer units and conjugated diene monomer units;
The polymer block (A) mainly contains a vinyl aromatic monomer unit and/or the polymer block (B) mainly contains a conjugated diene monomer unit,
It is a block copolymer that satisfies the following conditions (i) to (iv):
The conjugated diene monomer units in the block copolymer contain units (a) derived from a 1,2-bond and/or a 3,4-bond and units (b) derived from a 1,4-bond, and the content of the units (a) derived from a 1,2-bond and/or a 3,4-bond is 25 to 85% when the total content of the conjugated diene monomer units in the block copolymer is taken as 100% .
<Condition (i)>
The mass ratio of the vinyl aromatic monomer units to the conjugated diene monomer units in the polymer block (C) is vinyl aromatic monomer units/conjugated diene monomer units=5/95 to 95/5.
<Condition (ii)>
The content of the polymer block (C) is 5 parts by mass or more and 95 parts by mass or less based on 100 parts by mass of the block copolymer.
<Condition (iii)>
The weight average molecular weight is 35,000 or less.
<Condition (iv)>
The content of the vinyl aromatic monomer unit is 5 parts by mass or more and 80 parts by mass or less based on 100 parts by mass of the block copolymer.
[2]
Component (I): the block copolymer described in [1] above;
Contains at least one component selected from the group consisting of the following components (II) to (IV):
Resin composition.
Component (II): A radical initiator. Component (III): At least one polar resin selected from the group consisting of polyphenylene ether resins, bisphenol A epoxy resins, phenoxy resins, and polyimide resins (excluding component (I)).
Component (IV): Curing agent (excluding component (II))
[3]
Contains the component (III),
The resin composition according to [2] above, wherein the component (III) is at least one selected from the group consisting of bisphenol A epoxy resins, polyimide resins, polyphenylene ether resins, and phenoxy resins .
[4]
A cured product comprising the block copolymer described in [1] above.
[5]
A cured product of the resin composition described in [2] or [3] above.
[6]
A resin film made of the resin composition according to [2] or [3] above.
[7]
A substrate;
A prepreg that is a composite with the resin composition according to [2] or [3] above.
[8]
The prepreg according to [7], wherein the substrate is glass cloth.
[9]
A laminate comprising the resin film according to [6] above and a metal foil.
[10]
A laminate comprising a cured product of the prepreg according to [7] or [8] above and a metal foil.
[11]
A material for electronic circuit boards, comprising the cured product according to [5] above.

The present invention provides a block copolymer and a resin composition containing the block copolymer that produce a cured product with a low dielectric constant, a low dielectric loss tangent, and excellent strength properties.

Hereinafter, an embodiment of the present invention (hereinafter referred to as "the present embodiment") will be described in detail.
It should be noted that the following embodiments are merely examples for explaining the present invention, and are not intended to limit the present invention to the following content, and the present invention can be implemented in various modified forms within the scope of its gist.

[Block copolymer]
The block copolymer of this embodiment is
a polymer block (C) (hereinafter sometimes referred to as polymer block (C)) consisting of a vinyl aromatic monomer unit and a conjugated diene monomer unit;
The copolymer has a polymer block (A) (hereinafter may be referred to as polymer block (A)) mainly composed of vinyl aromatic monomer units and/or a polymer block (B) (hereinafter may be referred to as polymer block (B)) mainly composed of conjugated diene monomer units.
The block copolymer of this embodiment satisfies the following conditions (i) to (iv).
<Condition (i)>
The mass ratio of the vinyl aromatic monomer unit to the conjugated diene monomer unit in the polymer block (C) (vinyl aromatic compound/conjugated diene compound) is 5/95 to 95/5.
<Condition (ii)>
The content of the polymer block (C) is 5 parts by mass or more and 95 parts by mass or less based on 100 parts by mass of the block copolymer.
<Condition (iii)>
The weight average molecular weight is 35,000 or less.
<Condition (iv)>
The content of the vinyl aromatic monomer unit is 5 parts by mass or more and 95 parts by mass or less based on 100 parts by mass of the block copolymer.
The block copolymer of this embodiment provides a cured product that has a low dielectric constant and a low dielectric loss tangent, and also has excellent strength properties.

The conjugated diene monomer unit refers to a structural unit derived from a conjugated diene compound in a polymer block or block copolymer produced by polymerization of a conjugated diene compound.
A conjugated diene compound is a diolefin having a pair of conjugated double bonds.
Examples of conjugated diene compounds include, but are not limited to, 1,3-butadiene, 2-methyl-1,3-butadiene, isoprene, 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene, 2-methyl-1,3-pentadiene, 1,3-hexadiene, and 1,3-cyclohexadiene.
Among these, 1,3-butadiene and isoprene are preferred, and 1,3-butadiene is more preferred. 1,3-Butadiene and isoprene are widely used and easily available, are advantageous from the viewpoint of cost, and can easily be copolymerized with styrene, which is widely used as a vinyl aromatic compound, as described below.
These may be used alone or in combination of two or more.
The conjugated diene compound may be a biotechnological compound.

The vinyl aromatic monomer unit refers to a structural unit derived from a vinyl aromatic compound in a polymer block or block copolymer produced by polymerization of a vinyl aromatic compound.
Examples of vinyl aromatic compounds include, but are not limited to, styrene, α-methylstyrene, p-methylstyrene, divinylbenzene, 1,1-diphenylethylene, N,N-dimethyl-p-aminoethylstyrene, and N,N-diethyl-p-aminoethylstyrene.
These may be used alone or in combination of two or more.

The polymer block (C) constituting the block copolymer of the present embodiment is a polymer block composed of vinyl aromatic monomer units and conjugated diene monomer units, and no other monomers are intentionally added.
The vinyl aromatic compound and the conjugated diene compound used to form the vinyl aromatic monomer units and the conjugated diene monomer units contained in the polymer block (C) may be the above-mentioned vinyl aromatic compound and conjugated diene compound.
The distribution state of the vinyl aromatic monomer units in the polymer block (C) is not particularly limited, and the vinyl aromatic monomer units in the polymer block (C) may be uniformly distributed or tapered. Further, there may be a plurality of portions where the vinyl aromatic monomer units are uniformly distributed and/or a plurality of portions where the vinyl aromatic monomer units are tapered, and there may be a plurality of segments with different contents of the vinyl aromatic monomer units.
The polymer block (A) constituting the block copolymer is mainly composed of vinyl aromatic monomer units. The term "mainly composed" means that the polymer block (A) is essentially composed of vinyl aromatic monomer units, and no other monomers are intentionally added.
The polymer block (B) is mainly composed of conjugated diene monomer units. The term "mainly composed of" means that the polymer block (B) is substantially composed of conjugated diene monomer units, and that no other monomers than the conjugated diene monomers are intentionally added.

When the block copolymer of this embodiment contains polymer block (A), the content of polymer block (A) in the block copolymer can be measured by a method using a nuclear magnetic resonance (NMR) spectrometer (the method described in Y. Tanaka, et al., RUBBER CHEMISTRY and TECHNOLOGY 54, 685 (1981), hereinafter referred to as the "NMR method") using the block copolymer before hydrogenation or the hydrogenated block copolymer after hydrogenation as a sample.

When the block copolymer of this embodiment contains polymer block (B), the content of polymer block (B) can be measured by NMR.

The block copolymer of this embodiment has a polymer block (C).
The polymer block (C) comprises vinyl aromatic monomer units and conjugated diene monomer units.
The content of the polymer block (C) in the block copolymer of the present embodiment can be measured by an NMR method.
Polymer block (C) can be distinguished from polymer block (A) and polymer block (B) in that it has a structure in which vinyl aromatic monomer units and conjugated diene monomer units are intentionally used as constituent units.

<Condition (i)>
The mass ratio of the vinyl aromatic monomer units to the conjugated diene monomer units in the polymer block (C) is vinyl aromatic monomer units/conjugated diene monomer units=5/95 to 95/5.

As described below, the resin composition of this embodiment contains the block copolymer of this embodiment (component (I)) and at least one component selected from the group consisting of component (II): a radical initiator, component (III): a polar resin, and component (IV): a curing agent, which will be described below.
The components (II), (III), and (IV) each have a polar group.
From the viewpoint of solubility parameter, vinyl aromatic compounds tend to have higher compatibility with components (II), (III), and (IV) than conjugated diene compounds, but the block copolymer of this embodiment, in which a conjugated diene compound is copolymerized, has less steric hindrance than a block polymer consisting only of a vinyl aromatic compound. As a result, the presence of polymer block (C), which is a random block polymer of a vinyl aromatic compound and a conjugated diene compound, in the block copolymer further improves compatibility with components (III) and (IV), and improves the strength of the resin composition of this embodiment and/or the cured product described below.
Furthermore, the conjugated diene compound has radical reactivity, and as described above, polymer block (C) has excellent compatibility with components (II), (III), and (IV), so that the conjugated diene monomer units contained in polymer block (C) are located in close proximity to components (II), (III), and (IV), creating a state in which the conjugated diene monomer units are more likely to react with these components. Even when the resin composition of this embodiment described below does not contain one or two of components (II), (III), and (IV), the vinyl aromatic monomer units in the block copolymer of this embodiment are amorphous, so the reactivity of the conjugated diene monomer units between molecular chains of different block copolymers tends to be high.

Furthermore, due to the improved compatibility described above, the resin composition and cured product of this embodiment, described below, are prevented from experiencing a decrease in polymer mobility and polarization due to an external electric field, and the resin composition and cured product tend to have a low dielectric tangent and low dielectric constant. Both the loss (dielectric constant) caused by polarization of the polymer due to an external electric field and the energy loss (dielectric tangent) caused by heat generated by movement can be suppressed by ensuring sufficient compatibility and reactivity with components (III) and (IV), described below. Therefore, the block copolymer of this embodiment, having at least one polymer block (C), increases the strength of the resin composition and cured product of this embodiment and leads to a low dielectric tangent and low dielectric constant.

In view of the above, the mass ratio of the vinyl aromatic monomer units to the conjugated diene monomer units in the polymer block (C) (vinyl aromatic monomer units/conjugated diene monomer units) is from 5/95 to 95/5, preferably from 10/90 to 90/10, more preferably from 15/85 to 85/15, and even more preferably from 20/80 to 80/20.
When the amount of vinyl aromatic monomer units in the polymer block (C) is 5% by mass or more, sufficient compatibility in the resin composition for electrical materials is exhibited, and when it is 95% by mass or less, reactivity can be ensured. When the amount of conjugated diene monomer units in the polymer block (C) is 5% by mass or more, good reactivity is exhibited, and when it is 95% by mass or less, good compatibility is exhibited, sufficient strength is maintained, and the resin composition and the cured product tend to have low dielectric tangent and low dielectric constant.

<Condition (ii)>
As described above, from the viewpoint of obtaining a resin composition and a cured product exhibiting sufficient compatibility, sufficient strength, and having a low dielectric loss tangent and low dielectric constant, the content of polymer block (C) in the block copolymer of this embodiment is 5 parts by mass or more and 95 parts by mass or less relative to 100 parts by mass of the block copolymer. Furthermore, the content of polymer block (A) and/or polymer block (B) is preferably 5 parts by mass or more and 95 parts by mass or less relative to 100 parts by mass of the block copolymer of this embodiment.
The content of the polymer block (C) in the block copolymer of the present embodiment is preferably 10 parts by mass or more and 90 parts by mass or less, more preferably 15 parts by mass or more and 85 parts by mass or less, and even more preferably 20 parts by mass or more and 80 parts by mass or less, relative to 100 parts by mass of the block copolymer.
The content of polymer block (A) and/or polymer block (B) is more preferably 10 parts by mass or more and 90 parts by mass or less, even more preferably 15 parts by mass or more and 85 parts by mass or less, and even more preferably 20 parts by mass or more and 80 parts by mass or less.

Furthermore, from the viewpoint of reactivity as described above, the block copolymer of this embodiment preferably contains at least one polymer block (B), and the content of the polymer block (B) is preferably 5 parts by mass or more, more preferably 10 parts by mass or more, and even more preferably 15 parts by mass or more, relative to 100 parts by mass of the block copolymer of this embodiment.
Furthermore, when the block copolymer of the present embodiment contains polymer block (A), from the viewpoint of compatibility between the block copolymer and the above-described component (III) and/or component (IV), the content of polymer block (A) is preferably 5 to 95 parts by mass, more preferably 10 to 90 parts by mass, even more preferably 15 to 85 parts by mass, still more preferably 20 to 80 parts by mass, and still more preferably 25 to 80 parts by mass, relative to 100 parts by mass of the block copolymer.

The block copolymer of this embodiment has at least one polymer block (A) and/or one polymer block (B). The block copolymer of this embodiment preferably has at least one polymer block (B) at its terminal.
The polymer block (A) is amorphous because it is a polymer block mainly composed of vinyl aromatic monomer units. The resin composition and cured product of this embodiment, which will be described later, have the polymer block (A), which improves the entanglement strength between polymer chains.
The polymer block (B) is a polymer block mainly composed of conjugated diene monomer units and therefore has radical reactivity. In the resin composition and cured product of this embodiment described below, the components (II) to (IV) constituting the resin composition react with the block copolymer or the block copolymers react with each other, thereby improving the strength of the cured product.

[0043] In view of the improved compatibility due to the aromatic vinyl compound, the improved strength due to the aggregation of the polymer comprised of the aromatic vinyl compound, the reactivity between the block copolymers due to the conjugated diene compound, and the reactivity between the block copolymer and components (II), (III), and (IV), the content of the aromatic vinyl monomer units and the conjugated diene monomer units in the block copolymer of this embodiment is preferably 5 parts by mass or more per 100 parts by mass of the block copolymer. By making the content of the aromatic vinyl monomer units and the conjugated diene monomer units 5 parts by mass or more per 100 parts by mass of the block copolymer, the compatibility of the block copolymer with other components in the resin composition for electrical materials can be maintained, strength due to the aggregation of the aromatic vinyl monomer units and sufficient reactivity can be ensured, and the resin composition and cured product tend to exhibit sufficient strength.
Furthermore, the upper limit of the content of the vinyl aromatic monomer unit and the conjugated diene monomer unit relative to 100 parts by mass of the block copolymer of the present embodiment is preferably 95 parts by mass or less, from the viewpoints of the strength, low dielectric tangent, and low dielectric constant of the resin composition and the cured product.

The block copolymer of this embodiment may be copolymerized with other monomers copolymerizable with the vinyl aromatic compound and/or the conjugated diene compound to the extent that the desired dielectric performance, i.e., the desired low dielectric tangent and low dielectric constant, is not impaired. The polymer block formed by the other monomers is referred to as polymer block (D).
The content of the polymer block (D) relative to 100 parts by mass of the block copolymer of this embodiment is preferably 30 parts by mass or less, more preferably 20 parts by mass or less, even more preferably 10 parts by mass or less, still more preferably 5 parts by mass or less, and still more preferably 0 part by mass. In other words, it is preferable not to intentionally add any monomers other than the vinyl aromatic compound and the conjugated diene compound.

<Condition (iii)>
The weight average molecular weight of the block copolymer of this embodiment is 35,000 or less.
The weight-average molecular weight is a weight-average molecular weight (Mn) obtained by measuring the molecular weight of a peak in a chromatogram obtained by gel permeation chromatography (GPC) based on a calibration curve (prepared using the peak molecular weight of the standard polystyrene) obtained by measuring commercially available standard polystyrene, and specifically, can be measured by the method described in the examples below.
The molecular weight distribution is the ratio (Mw/Mn) of the weight average molecular weight (Mw) to the weight average molecular weight (Mn).
The single-peak molecular weight distribution of the block copolymer of the present embodiment measured by GPC is preferably 5.0 or less, more preferably 4.0 or less, even more preferably 3.0 or less, and still more preferably 2.5 or less, from the viewpoint of preventing deterioration of handleability due to a sudden decrease in viscosity caused by contamination with low-molecular-weight polymers, specifically polymers having a weight-average molecular weight of 500 or less.
When the weight-average molecular weight of the block copolymer of this embodiment is 35,000 or less, crosslinkability is improved, a uniform mesh structure is formed, and a high-strength cured product is obtained. In addition, compatibility with components (III) and (IV) described below is improved, and the dielectric constant and dielectric loss tangent tend to be low.

Furthermore, when a prepreg is formed using the resin composition of the present embodiment, when a substrate such as a glass cloth described later is immersed in a varnish described later, since the weight-average molecular weight of the block copolymer of the present embodiment is 35,000 or less, the block copolymers are uniformly crosslinked with each other and are uniformly compatible with component (III): a polar resin, and this tends to improve the strength of a cured product containing the block copolymer and to achieve a low dielectric loss tangent and a low dielectric constant.
Furthermore, in a prepreg using the resin composition of the present embodiment, good permeability into a substrate can be obtained, making it possible to produce a uniform prepreg, which tends to improve strength and achieve a low dielectric loss tangent and a low dielectric constant.
From the above viewpoints, the weight-average molecular weight of the block copolymer of this embodiment is 35,000 or less, preferably 30,000 or less, more preferably 25,000 or less, even more preferably 20,000 or less, and still more preferably 25,000 or less. There is no particular lower limit for the weight-average molecular weight of the block copolymer, but from the viewpoints of suppressing stickiness of the block copolymer and achieving good handleability, a weight-average molecular weight of 500 or more is preferred.
The weight average molecular weight and molecular weight distribution of the block copolymer of this embodiment can be controlled within the above numerical ranges by adjusting the polymerization conditions such as the amount of monomer added, the timing of addition, the polymerization temperature, and the polymerization time.

<Condition (iv)>
The block copolymer of the present embodiment has a content of vinyl aromatic monomer units of 5 parts by mass or more and 95 parts by mass or less relative to 100 parts by mass of the block copolymer.
By making the content of the vinyl aromatic monomer unit 5 parts by mass or more, compatibility with the components (II), (III), and (IV) described below is improved from the viewpoint of the solubility parameter, and the strength of the resin composition and the cured product of this embodiment is improved, and there is a tendency for a low dielectric tangent and a low dielectric constant to be achieved. From the viewpoint of the solubility parameter, the content of the vinyl aromatic monomer unit is preferably 10 parts by mass or more, more preferably 15 parts by mass or more, even more preferably 20 parts by mass or more, and still more preferably 25 parts by mass or more.
By setting the content of the vinyl aromatic monomer unit to 95 parts by mass or less, the reactivity of the block copolymer of this embodiment with the components (II), (III), and (IV) described below, as well as the reactivity of the block copolymer of this embodiment with itself, can be ensured. The content of the vinyl aromatic monomer unit is preferably 90 parts by mass or less, more preferably 85 parts by mass or less, and even more preferably 80 parts by mass or less.
The content of the vinyl aromatic monomer unit in the block copolymer of this embodiment can be measured by NMR, specifically, by the method described in the Examples below.
The content of the vinyl aromatic monomer unit in the block copolymer of this embodiment can be controlled within the above-mentioned numerical range by adjusting the amount of the monomer added in the polymerization step.

In the block copolymer of this embodiment, the conjugated diene monomer units in the polymer block (B) and the polymer block (C) contain units (a) (hereinafter sometimes referred to as units (a)) derived from a 1,2-bond and/or a 3,4-bond and units (b) (hereinafter sometimes referred to as units (b)) derived from a 1,4-bond. When the total content of the conjugated diene monomer units in the polymer block (B) and the polymer block (C) is taken as 100%, the content of the units (a) derived from a 1,2-bond and/or a 3,4-bond is preferably 10 to 95%, more preferably 15 to 90%, even more preferably 20 to 85%, and even more preferably 25 to 80% or less, from the viewpoints of the reactivity between the block copolymers during curing to obtain a cured product and the reactivity with components (III) and (IV) described below.
When both 1,2-bonds and 3,4-bonds are contained, the total content of the 1,2-bonds and 3,4-bonds is the content of units (a).

The content of the unit (a) can be controlled by using a regulator such as a polar compound in the polymerization step of the block copolymer, and can be calculated by the method described in the examples below.
Examples of the regulator include tertiary amine compounds and ether compounds, with tertiary amine compounds being preferred.
The tertiary amine compound is a compound of the general formula R1R2R3N (wherein R1, R2, and R3 are hydrocarbon groups having 1 to 20 carbon atoms or hydrocarbon groups having a tertiary amino group).
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.

The amount of regulator added is preferably 0.1 mol or more, more preferably 0.5 mol or more, and even more preferably 1.0 mol or more, per mol of the polymerization initiator described below. Furthermore, when the unit (a) is to be 80% or more, the amount of regulator added is preferably 0.15 mol or more, more preferably 0.5 mol or more, and even more preferably 1.0 mol or more, per mol of the polymerization initiator described below.

The block copolymer of the present embodiment may include a block copolymer in which the aliphatic double bonds based on a conjugated diene compound have been hydrogenated to the extent that the curing reaction is not impaired.
The method for hydrogenating the block copolymer is not particularly limited, and any conventionally known method can be applied.

In the hydrogenation reaction, a hydrogenation catalyst can be used.
Examples of hydrogenation catalysts that can be used include: (1) supported heterogeneous hydrogenation catalysts in which a metal such as Ni, Pt, Pd, or Ru is supported on carbon, silica, alumina, or diatomaceous earth; (2) so-called Ziegler-type hydrogenation catalysts that use a transition metal salt such as an organic acid salt or acetylacetone salt of Ni, Co, Fe, Cr, or the like, and a reducing agent such as organoaluminum; and (3) homogeneous hydrogenation catalysts such as so-called organometallic complexes of organometallic compounds of Ti, Ru, Rh, Zr, or the like.
Specific examples of the hydrogenation catalyst that can be used include the hydrogenation catalysts described in Japanese Patent Publication Nos. 42-8704, 43-6636, 63-4841, 1-37970, 1-53851, and 2-9041.
Preferred hydrogenation catalysts include titanocene compounds and reducing organometallic compounds.
The titanocene compound may be a compound described in JP-A-8-109219. Examples of the titanocene compound include compounds having at least one ligand having a (substituted) cyclopentadienyl skeleton, an indenyl skeleton, or a fluorenyl skeleton, such as biscyclopentadienyltitanium dichloride and monopentamethylcyclopentadienyltitanium trichloride. The titanocene compound may contain one of the above skeletons alone or a combination of two of them.
Examples of the reducing organometallic compound include organic alkali metal compounds such as organolithium compounds, organomagnesium compounds, organoaluminum compounds, organoboron compounds, and organozinc compounds, which may be used singly or in combination of two or more.

The hydrogenation rate of the block copolymer of this embodiment can be controlled by appropriately adjusting the reaction temperature, reaction time, hydrogen supply amount, catalyst amount, etc. in the hydrogenation method. The temperature during the hydrogenation reaction is preferably 55 to 200°C, more preferably 60 to 170°C, and even more preferably 65 to 160°C. The pressure of the hydrogen used in the hydrogenation reaction is usually 0.1 to 15 MPa, preferably 0.2 to 10 MPa, and more preferably 0.3 to 5 MPa. The hydrogenation reaction time is usually 3 minutes to 10 hours, and preferably 10 minutes to 5 hours.
The hydrogenation reaction can be carried out using either a batch process, a continuous process, or a combination thereof.

When the curing reaction to obtain the cured product of this embodiment, which will be described later, is a radical reaction, the hydrogenation rate of the block copolymer of this embodiment is preferably 5 to 95%, more preferably 10 to 90%, and even more preferably 13 to 87%, from the viewpoint of the balance between curing reactivity and thermal stability. When the curing reaction to obtain the cured product is a reaction other than a radical reaction, the hydrogenation rate can be selected from the range of 0 to 100%, from the viewpoint of compatibility between the block copolymer of this embodiment and other components.

[Method for producing block copolymer]
The block copolymer of this embodiment can be produced, for example, by living anionic polymerization in a hydrocarbon solvent using a polymerization initiator such as an organic alkali metal compound.

Examples of hydrocarbon solvents include 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.

Examples of the polymerization initiator include organic alkali metal compounds such as aliphatic hydrocarbon alkali metal compounds, aromatic hydrocarbon alkali metal compounds, and organic amino alkali metal compounds, which are generally known to have anionic polymerization activity for conjugated diene compounds and vinyl aromatic compounds. Examples of alkali metals include lithium, sodium, and potassium.
Examples of organic alkali metal compounds include aliphatic and aromatic hydrocarbon lithium compounds having 1 to 20 carbon atoms, including compounds containing one lithium atom per molecule, dilithium compounds containing multiple lithium atoms per molecule, trilithium compounds, and tetralithium compounds.
Specific examples of organic alkali metal compounds include n-propyllithium, n-butyllithium, sec-butyllithium, tert-butyllithium, n-pentyllithium, n-hexyllithium, benzyllithium, phenyllithium, tolyllithium, a reaction product of diisopropenylbenzene and sec-butyllithium, and a reaction product of divinylbenzene, sec-butyllithium, and a small amount of 1,3-butadiene. Furthermore, 1-(t-butoxy)propyllithium, as disclosed in U.S. Patent No. 5,708,092, and lithium compounds into which one to several isoprene monomer molecules have been inserted to improve solubility, siloxy group-containing alkyllithiums such as 1-(t-butyldimethylsiloxy)hexyllithium, as disclosed in British Patent No. 2,241,239, amino group-containing alkyllithiums such as diisopropylamidelithium and hexamethyldisilazidelithium, as disclosed in U.S. Patent No. 5,527,753, and aminolithiums such as lithium diisopropylamidelithium and hexamethyldisilazidelithium can also be used.

As a method for polymerizing a vinyl aromatic compound and a conjugated diene polymer using an organic alkali metal compound as a polymerization initiator, a conventionally known method can be applied.
The polymerization method may be, for example, batch polymerization, continuous polymerization, or a combination of these. In particular, batch polymerization is preferred for obtaining a uniform polymer block.
The polymerization temperature is preferably 0°C to 180°C, more preferably 30°C to 150°C. The polymerization time varies depending on the conditions, but is usually within 48 hours, preferably 0.1 to 10 hours. The polymerization atmosphere is preferably an inert gas atmosphere such as nitrogen gas. The polymerization pressure is not particularly limited, and may be set within a pressure range that allows the monomer and solvent to be maintained in a liquid phase within the above temperature range. Furthermore, care must be taken to prevent the introduction of impurities that may inactivate the catalyst and living polymer, such as water, oxygen, and carbon dioxide gas, into the polymerization system.

Furthermore, at the end of the polymerization process, a coupling reaction may be carried out by adding a required amount of a bifunctional or higher functional coupling agent within a range that satisfies the above-mentioned conditions (i) to (iv), but the coupling rate is preferably 40% or less, more preferably 30% or less, even more preferably 20% or less, and it is even more preferable that no coupling agent is included.

The bifunctional coupling agent is not particularly limited and may be any known one.
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.
Furthermore, as the tri- or higher functional polyfunctional coupling agent, any known agent may be used, and there is no particular limitation.
Examples of polyfunctional coupling agents having three or more functionalities include, but are not limited to, polyhydric epoxy compounds such as trihydric or higher polyalcohols, epoxidized soybean oil, diglycidyl bisphenol A, and 1,3-bis(N-N'-diglycidylaminomethyl)cyclohexane; halogenated silicon compounds represented by the general formula R ₄ -nSiX _n (where R is a hydrocarbon group having 1 to 20 carbon atoms, X is a halogen, and n is an integer of 3 to 4), such as methylsilyl trichloride, t-butylsilyl trichloride, silicon tetrachloride, and brominated versions thereof; and halogenated tin compounds represented by the general formula R ₄ -nSnX _n (where R is a hydrocarbon group having 1 to 20 carbon atoms, X is a halogen, and n is an integer of 3 to 4), such as methyltin trichloride, t-butyltin trichloride, and tin tetrachloride. Dimethyl carbonate, diethyl carbonate, and the like may also be used.

If necessary, the catalyst residue can be removed from the solution of the block copolymer of this embodiment obtained as described above, and the block copolymer can be separated from the solution.
The polymerization initiator used in producing a block copolymer by anionic living polymerization and the compound containing a metal atom in the hydrogenation catalyst in the hydrogenation reaction described above tend to react with moisture in the air during a desolvation step, etc., to generate a specific metal compound that remains in the block copolymer. When these metal compounds are contained in a cured product using the conjugated diene-based polymer of this embodiment, the dielectric constant and dielectric loss tangent tend to increase, and further, ion migration tends to occur easily when the product is used as an electronic material.
Examples of the remaining metal compounds include compounds of metals contained in the polymerization initiator and the hydrogenation catalyst, oxides of each atom such as titanium oxide, amorphous titanium oxide, orthotitanic acid, metatitanic acid, titanium hydroxide, nickel hydroxide, nickel monoxide, lithium oxide, lithium hydroxide, cobalt oxide, and cobalt hydroxide, and composite oxides of each atom with a different metal such as lithium titanate, barium titanate, strontium titanate, nickel titanate, and nickel-iron oxide.
In order to achieve a low dielectric constant and a low dielectric loss tangent in the resin composition and the cured product of this embodiment and to make ion migration less likely to occur, the amount of metal compounds remaining in the block copolymer is preferably 150 ppm or less, more preferably 130 ppm or less, even more preferably 100 ppm or less, and still more preferably 90 ppm or less, in terms of the amount of residual metal. Typical examples of residual metals include Ti, Ni, Li, Co, etc.

Methods for reducing the amount of residual metal in the block copolymer of this embodiment can be any conventionally known method, and are not particularly limited. Examples include a method of adding water and carbon dioxide gas after the hydrogenation reaction of the block copolymer to neutralize the hydrogenation catalyst residue; and a method of adding water, carbon dioxide gas, and an acid to neutralize the hydrogenation catalyst residue. 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 block copolymer desolvation process, so the amount of residual metal is generally about 1 to 15 ppm. Therefore, it is preferable to remove 20% or more of the amount of metal added to the block 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.

It is also possible to reduce the amount of residual metal in the block copolymer by reducing the amount of polymerization initiator and hydrogenation catalyst added. However, reducing the amount of polymerization initiator increases the molecular weight of the block copolymer, and if the molecular weight falls outside the preferred molecular weight range mentioned above, the strength of the cured product tends to decrease. Furthermore, reducing the amount of hydrogenation catalyst during the hydrogenation reaction tends to increase the hydrogenation reaction time and temperature, significantly reducing productivity.

Methods for separating the solvent when recovering the block copolymer include, for example, adding a polar solvent that is a poor solvent for the block copolymer, such as acetone or alcohol, to the reaction solution after hydrogenation to precipitate and recover the block copolymer; pouring the reaction solution into boiling water with stirring and removing the solvent by steam stripping; and directly heating the block copolymer solution to distill off the solvent.

In addition, various stabilizers such as phenol-based stabilizers, phosphorus-based stabilizers, sulfur-based stabilizers, and amine-based stabilizers can be added to the hydrogenated block copolymer.

The block copolymer of this embodiment may have a "polar group" to the extent that the low dielectric loss tangent and low dielectric constant are not impaired.
Examples of the "polar group" include, but are not limited to, functional groups selected from the group consisting of a hydroxyl group, a carboxyl group, a carbonyl group, a thiocarbonyl group, an acid halide group, an acid anhydride group, a carboxylic acid group, a thiocarboxylic acid group, an aldehyde group, a thioaldehyde group, a carboxylic acid ester group, an amide group, a sulfonic acid group, a sulfonate ester group, a phosphoric acid group, a phosphoric acid ester group, an amino group, an imino group, a nitrile group, a pyridyl group, a quinoline group, an epoxy group, a thioepoxy group, a sulfide group, an isocyanate group, an isothiocyanate group, a silicon halide group, a silanol group, an alkoxy silicon group, a tin halide group, a boronic acid group, a boron-containing group, a boronate salt group, an alkoxy tin group, and a phenyl tin group, and atomic groups containing at least one of these functional groups.

The "polar group" can be formed using a modifying agent.
Examples of the modifying agent include, but are not limited to, tetraglycidyl meta-xylenediamine, 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, glycidyl methacrylate, and crotonic acid.

The method for forming the "polar group" in the block copolymer of this embodiment can be any known method, and is not particularly limited.
Examples of such methods include a melt-kneading method, a method in which each component is dissolved or dispersed and mixed in a solvent or the like and then reacted, etc. Other examples include a method of polymerizing by anionic living polymerization using a polymerization initiator having a functional group or an unsaturated monomer having a functional group, a method of modifying by addition reaction of a modifier that forms or contains a functional group at the living end, and a method of reacting an organic alkali metal compound such as an organolithium compound with a block copolymer (metalation reaction) and then adding a modifier that has a functional group to the block polymer to which the organic alkali metal has been added.

[Resin composition]
The resin composition of this embodiment contains the block copolymer of this embodiment (component (I)) and at least one component selected from the group consisting of the following components (II) to (IV):
Component (II): Radical initiator Component (III): Polar resin (excluding component (I))
Component (IV): Curing agent (excluding component (II))

From the viewpoint of achieving a low dielectric constant, a low dielectric loss tangent, and flexibility of the resin composition of this embodiment and its cured product, it is preferable that the resin composition of this embodiment contains component (I): the block copolymer, and component (II): a radical initiator.

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

(Component (III): Polar Resin)
The resin composition of the present embodiment may contain component (III): a polar resin (excluding component (I)) from the viewpoint of imparting performance such as adhesion to a predetermined substrate, within a range that does not impair the low dielectric loss tangent and low dielectric constant of the cured product. By containing a polar resin, the resin composition of the present embodiment tends to have excellent adhesion to a predetermined substrate.
When component (III) is a polar resin having radical reactivity, the amount of the above-mentioned component (II): radical initiator can be appropriately adjusted or component (II) can be omitted depending on the reactivity.

Examples of the polar resin having radical reactivity as component (III) include a polymer having at least one vinyl group in the polymer, a homopolymer of a compound containing a halogen element, and a copolymer of these with any compound, etc. From the viewpoint of the low dielectric loss tangent and low dielectric constant of the resin composition and the cured product of this embodiment, the polar resin as component (III) is preferably a polymer having a vinyl group.
The polymer having a vinyl group may be a polymer consisting of a repeating unit having a vinyl group, a polymer of a compound having a vinyl group and a compound having a polar group, or a polymer having a vinyl group obtained by reaction of the polar groups of a compound having a polar group.
Examples of compounds having a vinyl group and a polar group include, but are not limited to, (meth)acrylic acid (in this specification, "(meth)acrylic" means methacrylic or acrylic), maleic acid, maleic acid monoalkyl ester, carboxyl group-containing vinyl monomers such as fumaric acid, vinyl sulfonic acid, (meth)allyl sulfonic acid, methyl vinyl sulfonic acid, styrene sulfonic acid, sulfone group-containing vinyl monomers such as vinyl sulfonic acid, (meth)allyl sulfonic acid, methyl vinyl sulfonic acid, styrene sulfonic acid, hydroxyl group-containing vinyl monomers such as hydroxystyrene, N-methylol (meth)acrylamide, hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, phosphate group-containing vinyl monomers such as 2-hydroxyethyl (meth)acryloyl phosphate, phenyl-2-acryloyloxyethyl phosphate, 2-acryloyloxyethyl phosphonic acid, hydroxy Examples of the vinyl monomer include hydroxy group-containing vinyl monomers such as styrene, N-methylol (meth)acrylamide, hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, polyethylene glycol (meth)acrylate, and 1-butene-3-ol; amino group-containing vinyl monomers such as aminoethyl (meth)acrylate, dimethylaminoethyl (meth)acrylate, and diethylaminoethyl (meth)acrylate; amide group-containing vinyl monomers such as (meth)acrylamide, N-methyl (meth)acrylamide, and N-butylacrylamide; nitrile group-containing vinyl monomers such as (meth)acrylonitrile, cyanostyrene, and cyanoacrylate; and epoxy group-containing vinyl monomers such as glycidyl methacrylate, tetrahydrofurfuryl (meth)acrylate, and p-vinylphenyl phenyloxide.
Examples of compounds containing halogen elements include, but are not limited to, vinyl chloride, vinyl bromide, vinylidene chloride, allyl chloride, chlorostyrene, bromostyrene, dichlorostyrene, chloromethylstyrene, tetrafluorostyrene, and chloroprene.

(Component (IV) Curing Agent)
When the radical reactivity of the above-described component (III) is low, from the viewpoint of reactivity, it is preferable that the resin composition of the present embodiment contains component (IV): a curing agent (excluding component (II)).
Component (IV): a curing agent generally has the function of reacting with component (III): a polar resin to cure the resin composition.
The "reaction" of component (III) and component (IV) means that the polar groups of each component have covalent bonding properties. When polar groups react with each other, for example, when OH of a carboxyl group is eliminated, the original polar group changes or disappears. If this results in the formation of a covalent bond, this is included in the definition of the polar groups being "reactive."

From the viewpoint of curing reactivity, it is preferable that component (IV): curing agent has two or more polar groups in one molecular chain that can react with the functional groups of component (III): polar resin.
The component (IV) may be used alone or in combination of two or more.
The type of polar group contained in component (III) and component (IV) is not particularly limited, but examples thereof include:
an epoxy group, a carboxy group, a carbonyl group, an ester group, an imidazole group, a hydroxyl group, an amino group, a mercaptan group, a benzoxazine group, a carbodiimide group, or a phenolic hydroxyl group;
an amino group, a carboxy group, a carbonyl group, a hydroxyl group, an acid anhydride group, a sulfonic acid group, or an aldehyde group;
Isocyanate groups, hydroxyl groups, carboxylic acids, and phenolic hydroxyl groups;
an acid anhydride group and a hydroxy group;
A silanol group, a hydroxy group, and a carboxylic acid group;
a halogen group, a carboxylic acid group, a carboxylic acid ester group, an amino group, a phenol group, or a thiol group;
Alkoxy groups, hydroxy groups, alkoxide groups, and amino groups;
Examples include a maleimide group and a cyanate group.
Whether the bond of these polar groups is component (III) or component (IV) can be selected arbitrarily.

In addition, cases where the polar group of component (III) and the polar group of component (IV) do not react directly but can react by adding a curing accelerator such as a catalyst are also included in the definition of "reactive."
For example, when component (III) is a polar resin having an epoxy group and component (IV) is a curing agent having an acid anhydride group, the reactivity between the epoxy group and the acid anhydride group is usually very low, but by adding a compound having an amino group as a curing accelerator, the epoxy group and the amino group in component (III) react, and some or all of the epoxy groups in component (III) become hydroxyl groups. The hydroxyl groups react with the acid anhydride groups of component (IV): the curing agent, and the resin composition cures.

From the standpoint of reactivity, the ratio of component (III): polar resin to component (IV): curing agent is, in terms of the molar ratio of polar groups, preferably polar groups of component (III): polar groups of component (IV) = 1:0.01 to 1:20, more preferably 1:0.05 to 1:15, and even more preferably 1:0.1 to 1:10.

Component (IV): Curing agent is a curing agent having an ester group, but is not limited to the following: EXB9451, EXB9460, EXB, 9460S, HPC8000-65T, HPC8000H-65TM, EXB8000L-65TM, EXB8150-65T, EXB9416-70BK manufactured by DIC Corporation; and YLH1026, DC808, YLH1026, YLH1030, YLH1048 manufactured by Mitsubishi Chemical Corporation.

Examples of curing agents having hydroxyl groups include, but are not limited to, MEH-7700, MEH-7810, MEH-7851, NHN, CBN, and GPH manufactured by Nippon Kayaku Co., Ltd., SN170, SN180, SN190, SN475, SN485, SN495, SN-495V, and SN375 manufactured by Nippon Steel & Sumikin Chemical Co., Ltd., and TD-2090, LA-7052, LA-7054, LA-1356, LA-3018-50P, and EXB-9500 manufactured by DIC Corporation.

Examples of curing agents having a benzoxazine group include, but are not limited to, ODA-BOZ manufactured by JFE Chemical Corporation, HFB2006M manufactured by Showa Highpolymer Co., Ltd., and P-d and Fa manufactured by Shikoku Chemicals Corporation.

Examples of curing agents having an isocyanate group include, but are not limited to, bifunctional cyanate resins such as bisphenol A dicyanate, polyphenol cyanate, oligo(3-methylene-1,5-phenylene cyanate), 4,4'-methylenebis(2,6-dimethylphenyl cyanate), 4,4'-ethylidene diphenyl dicyanate, hexafluorobisphenol A dicyanate, 2,2-bis(4-cyanate)phenylpropane, 1,1-bis(4-cyanate phenylmethane), bis(4-cyanate-3,5-dimethylphenyl)methane, 1,3-bis(4-cyanate phenyl-1-(methylethylidene))benzene, bis(4-cyanate phenyl)thioether, and bis(4-cyanate phenyl)ether; multifunctional cyanate resins derived from phenol novolac and cresol novolac; and prepolymers in which these cyanate resins are partially converted to triazine. Commercially available products include PT30, PT60, ULL-950S, BA230, and BA230S75 manufactured by Lonza Japan.

Examples of curing agents having a carbodiimide group include, but are not limited to, V-03 and V-07 manufactured by Nisshinbo Chemical Inc.

Examples of the curing agent having an amino group include, but are not limited to, 4,4'-methylenebis(2,6-dimethylaniline), diphenyldiaminosulfone, 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylsulfone, 3,3'-diaminodiphenylsulfone, m-phenylenediamine, m-xylylenediamine, diethyltoluenediamine, 4,4'-diaminodiphenyl ether, 3,3'-dimethyl-4,4'-diaminobiphenyl, 2,2'-dimethyl-4,4'-diaminobiphenyl, 3,3'-dihydroxybenzidine, 2,2-bis(3-amino bis(4-aminophenoxy)phenyl)propane, 3,3-dimethyl-5,5-diethyl-4,4-diphenylmethanediamine, 2,2-bis(4-aminophenyl)propane, 2,2-bis(4-(4-aminophenoxy)phenyl)propane, 1,3-bis(3-aminophenoxy)benzene, 1,3-bis(4-aminophenoxy)benzene, 1,4-bis(4-aminophenoxy)benzene, 4,4'-bis(4-aminophenoxy)biphenyl, bis(4-(4-aminophenoxy)phenyl)sulfone, bis(4-(3-aminophenoxy)phenyl)sulfone, and the like. Commercially available products include KAYABOND C-200S, KAYABOND C-100, Kayahard A-A, Kayahard A-B, and Kayahard A-S manufactured by Nippon Kayaku Co., Ltd., and Epicure W manufactured by Mitsubishi Chemical Corporation.
From the viewpoint of reactivity, the amino group is preferably a primary amine or a secondary amine, more preferably a primary amine.

Examples of curing agents having an acid anhydride group include, but are not limited to, phthalic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, methyltetrahydrophthalic anhydride, methylhexahydrophthalic anhydride, methylnadic anhydride, hydrogenated methylnadic anhydride, trialkyltetrahydrophthalic anhydride, dodecenyl succinic anhydride, 5-(2,5-dioxotetrahydro-3-furanyl)-3-methyl-3-cyclohexene-1,2-dicarboxylic anhydride, trimellitic anhydride, pyromellitic anhydride, and benzophenone. Examples of suitable acid anhydrides include tetracarboxylic dianhydride, biphenyltetracarboxylic dianhydride, naphthalenetetracarboxylic dianhydride, oxydiphthalic dianhydride, 3,3'-4,4'-diphenylsulfonetetracarboxylic dianhydride, 1,3,3a,4,5,9b-hexahydro-5-(tetrahydro-2,5-dioxo-3-furanyl)-naphtho[1,2-C]furan-1,3-dione, ethylene glycol bis(anhydrotrimellitate), and polymeric acid anhydrides such as styrene-maleic acid resins in which styrene and maleic acid are copolymerized.

Furthermore, compounds having at least two of the above-described radically reactive structures also have the function of reacting with component (III) to cure the resin composition, and such compounds can also be used as curing agents for component (IV).
Examples of the compound having at least two radical-reactive structures include, but are not limited to, allyl monomers such as triallyl isocyanurate (Taikyu, manufactured by Mitsubishi Chemical Corporation), tris(2-hydroxyethyl) isocyanurate, diallyl fumarate, diallyl adipate, triallyl citrate, and diallyl hexahydrophthalate.

When the resin composition of the present embodiment described above contains component (III), from the viewpoint of adhesiveness, component (III): polar resin is preferably at least one selected from the group consisting of epoxy-based resins, polyimide-based resins, polyphenylene ether-based resins, liquid crystal polyester-based resins, and fluorine-based resins. More preferably, it is at least one selected from the group consisting of epoxy-based resins, polyimide-based resins, and polyphenylene ether-based resins.

The polyimide resin may be any resin that has an imide bond in the repeating unit and falls into the category of polyimide resins. For example, a typical polyimide structure obtained by polycondensation (imide bond) of a tetracarboxylic acid or its dianhydride with a diamine can be used. From the viewpoint of curability, it is preferable that the polyimide structure has an unsaturated group at the end. Examples of polyimide resins having an unsaturated group at the end include, but are not limited to, maleimide polyimide resins, nadimide polyimide resins, and allylnadimide polyimide resins.
The tetracarboxylic acid or its dianhydride is not limited to the following, but examples thereof include aromatic tetracarboxylic acid dianhydrides, alicyclic tetracarboxylic acid dianhydrides, aliphatic tetracarboxylic acid dianhydrides, etc. These may be used alone or in combination of two or more.
The diamine is not limited to the following, but examples thereof include aromatic diamines, alicyclic diamines, aliphatic diamines, etc., which are commonly used in the synthesis of polyimides. These may be used alone or in combination of two or more.
Furthermore, from the viewpoint of reducing the dielectric constant and the dielectric loss tangent of the resin composition and the cured product of the present embodiment, at least one of the tetracarboxylic acid, the dianhydride thereof, and the diamine may have one or more functional groups of at least one type selected from the group consisting of a fluorine group, a trifluoromethyl group, a hydroxyl group, a sulfone group, a carbonyl group, a heterocycle, a long-chain alkyl group, and an allyl group.

In addition, commercially available polyimide resins may be used as the polyimide resin, and examples thereof include, but are not limited to, Neoprim (registered trademark) C-3650 (manufactured by Mitsubishi Gas Chemical Company, Inc., product name), Neoprim C-3G30 (manufactured by Mitsubishi Gas Chemical Company, Inc., product name), Neoprim C-3450 (manufactured by Mitsubishi Gas Chemical Company, Inc., product name), Neoprim P500 (manufactured by Mitsubishi Gas Chemical Company, Inc., product name), BT (bismaleimide triazine) resin (manufactured by Mitsubishi Gas Chemical Company, Inc.), JL-20 (manufactured by New Japan Chemical Company, Inc., product name) (these polyimide resin varnishes may contain silica), Rikacoat SN20, Rikacoat PN20, and I.S. Examples of such an anti-oxidant include Pyre-ML manufactured by T Co., Ltd.; UPIA-AT, UPIA-ST, UPIA-NF, and UPIA-LB manufactured by Ube Industries, Ltd.; PIX-1400, PIX-3400, PI2525, PI2610, HD-3000, and AS-2600 manufactured by Hitachi Chemical Co., Ltd.; HPC-5000, HPC-5012, HPC-1000, HPC-5020, HPC-3010, HPC-6000, HPC-9000, HCI-7000, HCI-1000S, HCI-1200E, and HCI-1300 manufactured by Showa Denko K.K.; BMI-2300 manufactured by Daiwa Kasei Kogyo Co., Ltd.; and MIR-3000 manufactured by Shin Nippon Kayaku Co., Ltd.

The polyphenylene ether resin of component (III) may be any resin that belongs to the category known as polyphenylene ether resin and contains phenylene ether units as repeating structural units, and may also contain other structural units in addition to phenylene ether units.
In the homopolymer having a phenylene ether unit, the phenylene group in the phenylene unit may or may not have a substituent. Examples of the substituent include, but are not limited to, acrylic groups such as ethyl, propyl, isopropyl, butyl, isobutyl, and tert-butyl groups, cyclic alkyl groups such as cyclohexyl groups, vinyl groups, allyl groups, isopropenyl groups, 1-butenyl groups, 1-pentenyl groups, p-vinylphenyl groups, p-isopropenylphenyl groups, m-vinylphenyl groups, m-isopropenylphenyl groups, o-vinylphenyl groups, o-isopropenylphenyl groups, p-vinylbenzyl groups, p-isopropenylbenzyl groups, m-vinylbenzyl groups, m-isopropenylbenzyl groups, o-vinylbenzyl groups, o-isopropenylbenzyl groups, p-vinylphenylethenyl groups, p-vinylphenylpropenyl groups, p-vinylphenylbutenyl groups, m-vinylphenylethenyl groups, m-vinylphenylpropenyl groups, m-vinylphenylbutenyl groups, and o-vinyl Examples of the functional group-containing substituent include an unsaturated bond-containing substituent such as an o-vinylphenylethenyl group, an o-vinylphenylpropenyl group, an o-vinylphenylbutenyl group, a methacryl group, an acryl group, a 2-ethylacryl group, or a 2-hydroxymethylacryl group; and a functional group-containing substituent such as a hydroxyl group, a carboxyl group, a carbonyl group, a thiocarbonyl group, an acid halide group, an acid anhydride group, a carboxylic acid group, a thiocarboxylic acid group, an aldehyde group, a thioaldehyde group, a carboxylic acid ester group, an amide group, a sulfonic acid group, a sulfonate ester group, a phosphoric acid group, a phosphoric acid ester group, an amino group, an imino group, a nitrile group, a pyridyl group, a quinoline group, an epoxy group, a thioepoxy group, a sulfide group, an isocyanate group, an isothiocyanate group, a silicon halide group, a silanol group, an alkoxy silicon group, a tin halide group, a boronic acid group, a boron-containing group, a boronate salt group, an alkoxytin group, and a phenyltin group. From the viewpoint of curability, it is preferable that the compound has any polar group for the purpose of having radical reactivity and/or reactivity with the curing agent (IV).

From the viewpoint of the curability of the resin composition of this embodiment, the polyphenylene ether resin, which is component (III), preferably has a molecular weight of 100,000 or less, more preferably 50,000 or less, and even more preferably 10,000 or less. Furthermore, the polyphenylene ether resin may be linear or may have a crosslinked or branched structure.

The liquid crystal polyester resin, component (III), is a polyester that forms an anisotropic molten phase and may be any resin that falls into the category of liquid crystal polyester resins. Examples include, but are not limited to, Eastman Kodak's "X7G," Dartco's Xyday (Zydar), Sumitomo Chemical's Econol, and Celanese's Vectra.

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

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

Furthermore, when an epoxy resin is used as component (III) from the viewpoint of reactivity, it is preferable to also contain component (IV) a curing agent. In this case, examples of polar groups possessed by component (IV) the curing agent include carboxyl groups, imidazole groups, hydroxyl groups, amino groups, mercaptan groups, benzoxazine groups, and carbodiimide groups. From the viewpoint of reactivity, carboxyl groups, imidazole groups, hydroxyl groups, benzoxazine groups, and carbodiimide groups are preferred. From the viewpoint of dielectric performance, hydroxyl groups, carboxyl groups, imidazole groups, benzoxazine groups, and carbodiimide groups are more preferred, and hydroxyl groups, carboxyl groups, and carbodiimide groups are even more preferred.

Furthermore, when two or more polar resins with different radical reactivity are used as component (III), it is preferable to use component (II): a radical initiator in combination with component (IV): a curing agent from the perspective of curability. For example, when a maleimide-type polyimide resin with excellent radical reactivity and a bisphenol A epoxy resin with no radical reactivity are used as component (III), it is preferable to add the aforementioned component (II): a radical initiator and the aforementioned component (IV): a curing agent from the perspective of curability.

Furthermore, when a polar resin having a high melting point and high rigidity is used as the polar resin (component (III)), the resin composition of this embodiment does not need to contain component (IV). Examples of the resin having a high melting point and high rigidity as component (III) include liquid crystal polyester resins and fluorine-based resins such as polytetrafluoroethylene.
Since component (III) has a high melting point and high rigidity, the composition tends to have a strength required for practical use even when component (IV) is not contained.

(Component (V): Additive)
The resin composition of the present embodiment may further contain various additives such as a curing accelerator, a filler, and a flame retardant as component (V).
The additives contained in the component (I) block copolymer are also the same as those of the component (V) of the resin composition.

The curing accelerator is added to promote the reactivity between the above-mentioned components, and any conventionally known accelerator can be used, such as a phosphorus-based curing accelerator, an amine-based curing accelerator, an imidazole-based curing accelerator, a guanidine-based curing accelerator, or a metal-based curing accelerator.
The curing accelerator may be used alone or in combination of two or more.

Phosphorus-based curing accelerators include, but are not limited to, triphenylphosphine, phosphonium borate compounds, tetraphenylphosphonium tetraphenylborate, n-butylphosphonium tetraphenylborate, tetrabutylphosphonium decanoate, (4-methylphenyl)triphenylphosphonium thiocyanate, tetraphenylphosphonium thiocyanate, butyltriphenylphosphonium thiocyanate, etc., with triphenylphosphine and tetrabutylphosphonium decanoate being preferred.

Amine-based curing accelerators include, but are not limited to, trialkylamines such as triethylamine and tributylamine, 4-dimethylaminopyridine, benzyldimethylamine, 2,4,6-tris(dimethylaminomethyl)phenol, 1,8-diazabicyclo(5,4,0)-undecene, etc., with 4-dimethylaminopyridine and 1,8-diazabicyclo(5,4,0)-undecene being preferred.

Examples of the imidazole curing accelerator include, but are not limited to, 2-methylimidazole, 2-undecylimidazole, 2-heptadecylimidazole, 1,2-dimethylimidazole, 2-ethyl-4-methylimidazole, 1,2-dimethylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole, 2-phenyl-4-methylimidazole, 1-benzyl-2-methylimidazole, and 1-benzyl-2-phenylimidazole. Imidazole, 1-cyanoethyl-2-methylimidazole, 1-cyanoethyl-2-undecylimidazole, 1-cyanoethyl-2-ethyl-4-methylimidazole, 1-cyanoethyl-2-phenylimidazole, 1-cyanoethyl-2-undecylimidazole, 1-cyanoethyl-2-phenylimidazolium trimellitate, 1-cyanoethyl-2-phenylimidazolium trimellitate, 2,4-diamino-6-[2'-methylimidazolyl-(1')]-ethyl-s-triazol-4-one 2,4-diamino-6-[2'-undecylimidazolyl-(1')]-ethyl-s-triazine, 2,4-diamino-6-[2'-ethyl-4'-methylimidazolyl-(1')]-ethyl-s-triazine, 2,4-diamino-6-[2'-methylimidazolyl-(1')]-ethyl-s-triazine isocyanuric acid adduct, 2-phenylimidazole isocyanuric acid adduct, 2-phenyl-4,5-dihydroxymethylimidazole, 2 [0039] Examples of the imidazole compound include 1-phenyl-4-methyl-5-hydroxymethylimidazole, 2,3-dihydro-1H-pyrrolo[1,2-a]benzimidazole, 1-dodecyl-2-methyl-3-benzylimidazolium chloride, 2-methylimidazoline, and 2-phenylimidazoline, as well as adducts of imidazole compounds with epoxy resins. Of these, 2-ethyl-4-methylimidazole and 1-benzyl-2-phenylimidazole are preferred.
As the imidazole-based curing accelerator, a commercially available product may be used, and examples thereof include, but are not limited to, P200-H50 manufactured by Mitsubishi Chemical Corporation.

Guanidine-based curing accelerators include, but are not limited to, dicyandiamide, 1-methylguanidine, 1-ethylguanidine, 1-cyclohexylguanidine, 1-phenylguanidine, 1-(o-tolyl)guanidine, dimethylguanidine, diphenylguanidine, trimethylguanidine, tetramethylguanidine, pentamethylguanidine, 1,5,7-triazabicyclo[4.4.0]dec-5-ene, 7-methyl-1,5,7-trimethyl-1,5,7-triazabicyclo[4.4.0]dec-5-ene, and 7-methyl-1,5,7-tri ... Examples thereof include triazabicyclo[4.4.0]dec-5-ene, 1-methylbiguanide, 1-ethylbiguanide, 1-n-butylbiguanide, 1-n-octadecylbiguanide, 1,1-dimethylbiguanide, 1,1-diethylbiguanide, 1-cyclohexylbiguanide, 1-allylbiguanide, 1-phenylbiguanide, and 1-(o-tolyl)biguanide, and dicyandiamide and 1,5,7-triazabicyclo[4.4.0]dec-5-ene are preferred.

Examples of metal-based curing accelerators include organometallic complexes or organometallic salts of metals such as cobalt, copper, zinc, iron, nickel, manganese, and tin.
Examples of organometallic complexes include, but are not limited to, organic cobalt complexes such as cobalt(II) acetylacetonate and cobalt(III) acetylacetonate, organic copper complexes such as copper(II) acetylacetonate, organic zinc complexes such as zinc(II) acetylacetonate, organic iron complexes such as iron(III) acetylacetonate, organic nickel complexes such as nickel(II) acetylacetonate, and organic manganese complexes such as manganese(II) acetylacetonate.
Examples of organic metal salts include, but are not limited to, zinc octoate, tin octoate, zinc naphthenate, cobalt naphthenate, tin stearate, and zinc stearate.

Examples of fillers include, but are not limited to, inorganic fillers such as silica, calcium carbonate, magnesium carbonate, magnesium hydroxide, aluminum hydroxide, calcium sulfate, barium sulfate, carbon black, glass fiber, glass beads, glass balloons, glass flakes, graphite, titanium oxide, potassium titanate whiskers, carbon fiber, alumina, kaolin clay, silicic acid, calcium silicate, quartz, mica, talc, clay, zirconia, potassium titanate, alumina, and metal particles; and organic fillers such as wood chips, wood powder, pulp, and cellulose nanofibers.
These may be used alone or in combination of two or more.
The shape of these fillers is not particularly limited and may be any of scaly, spherical, granular, powdery, irregular, etc.

The resin composition or cured product of this embodiment is often exposed to high temperatures during molding, etc. To prevent shrinkage and deformation of the molded product due to temperature changes, it is preferable that the filler have a low linear expansion coefficient. From the perspective of reducing the linear expansion coefficient, silica is preferred as the filler. Examples of silica include amorphous silica, fused silica, crystalline silica, synthetic silica, and hollow silica.

Examples of the flame retardant include halogen-based 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, alkylsulfonates, antimony trioxide, aluminum hydroxide, magnesium hydroxide, zinc borate, hexabromobenzene, decabromodiphenylethane, 4,4-dibromobiphenyl, and ethylenebistetrabromophthalimide.
These flame retardants may be used alone or in combination of two or more.
The above flame retardants also include so-called flame retardant assistants, which by themselves have a low flame retardancy effect but when used in combination with other flame retardants, exhibit a synergistically superior effect.

Fillers and flame retardants that have been previously surface-treated with a surface treatment agent such as a silane coupling agent can also be used.
Examples of surface treatment agents include fluorine-containing silane coupling agents, aminosilane coupling agents, epoxysilane coupling agents, mercaptosilane coupling agents, silane coupling agents, alkoxysilanes, organosilazane compounds, titanate coupling agents, etc. These may be used alone or in combination.

There are no particular restrictions on the other additives, so long as they are generally used in compounding resin compositions and cured products.
Examples of other additives include, but are not limited to, pigments and/or colorants such as carbon black and titanium oxide; lubricants such as stearic acid, behenic acid, zinc stearate, calcium stearate, magnesium stearate, and ethylene bisstearamide; mold release agents; plasticizers such as organic polysiloxanes, fatty acid esters such as phthalate esters, adipate compounds, and azelaate compounds, and mineral oil; antioxidants such as hindered phenols and phosphorus-based heat stabilizers; hindered amine light stabilizers; benzotriazole-based ultraviolet absorbers; antistatic agents; organic fillers; thickeners; antifoaming agents; leveling agents; resin additives such as adhesion promoters; other additives, and mixtures thereof.

From the viewpoint of achieving a low dielectric constant and a low dielectric loss tangent for the resin composition and cured product of this embodiment, it tends to be preferable that the resin composition of this embodiment does not contain pigments, colorants, lubricants, release agents, or antistatic agents.

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

[Cured product]
The cured product of this embodiment contains the block copolymer of this embodiment described above.
The cured product of this embodiment can be obtained by subjecting the resin composition of this embodiment to a curing reaction at a desired temperature and time. The term "cured product" encompasses not only completely cured products, but also semi-cured products in which only a portion of the resin composition is cured and uncured components remain. In the process for producing the laminate described below, a step of further curing the cured product may be carried out. The reaction temperature for the curing step of this embodiment is preferably 80°C or higher, more preferably 100°C or higher, and even more preferably 120°C or higher. The reaction time is preferably 10 to 240 minutes, more preferably 20 to 230 minutes, and even more preferably 30 to 220 minutes. When the resin composition of this embodiment is a varnish, it is preferable to perform the curing reaction after drying and removing the solvent. Drying methods may be conventionally known, such as heating or hot air blowing, and are preferably performed at a temperature lower than the curing reaction temperature. When performing the curing reaction after solvent removal, the resin composition is dried so that the solvent content is preferably 10% by mass or less, more preferably 5% by mass or less.

[Resin film]
The resin film of the present embodiment is made of the resin composition of the present embodiment.
The resin film of this embodiment can be obtained by spreading a varnish made from the resin composition of this embodiment described above into a uniform thin film and drying it as described above to remove the solvent, and then rolling it up into a roll and storing it.
The resin film of this embodiment may be configured with a predetermined protective film laminated thereon, and in such a case, the resin film can be used by peeling off the protective film.

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

[Laminate]
The laminate of this embodiment includes the resin film and metal foil described above, and also includes the cured product of the prepreg described above and metal foil.
The laminate of the present embodiment can be produced, for example, through a step (a) of laminating a resin film made of the resin composition of the present embodiment onto a substrate to form a resin layer and obtain a prepreg, a step (b) of heating and pressurizing the resin layer to flatten it and obtain a cured prepreg, and a step (c) of further forming a predetermined wiring layer made of metal foil on the resin layer.
In the step (a), the method of laminating the resin film on the substrate is not particularly limited, but for example, a method of laminating using a multi-stage press, a vacuum press, a normal pressure laminator, or a laminator that heats and pressurizes under vacuum can be mentioned, and the method of using a laminator that heats and pressurizes under vacuum is preferred.By using this method of using a laminator, even if the target electronic circuit board has a fine wiring circuit on the surface, it is possible to fill the gaps between the circuits with resin without generating voids.In addition, lamination may be a batch type or a continuous type using a roll or the like.

The substrate of the laminate described above can be the same as the substrate that constitutes the prepreg described above, as well as a glass epoxy substrate, a metal substrate, a polyester substrate, a polyimide substrate, a polyphenylene ether substrate, a fluororesin substrate, etc. The surface of the substrate onto which the resin layer is laminated may be roughened in advance, and there is no limit to the number of substrate layers.

In the step (b), the resin film and the substrate laminated in the step (a) are heated and pressurized to be flattened. The conditions can be adjusted as desired 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.
In the step (c), a predetermined wiring layer made of a metal foil is further formed on the resin layer produced by heating and pressing the resin film and the substrate. The formation method is not particularly limited, and includes conventionally known methods, such as subtractive etching methods and semi-additive methods.
The subtractive method is a method of forming the desired wiring by forming an etching resist layer on a metal layer in a shape corresponding to the desired pattern shape, and then performing a development process to dissolve and remove the metal layer in the areas where the resist has been removed with a chemical solution.
The semi-additive method is a method in which a metal coating is formed on the surface of a resin layer by electroless plating, a plating resist layer of a shape corresponding to the desired pattern is formed on the metal coating, a metal layer is then formed by electrolytic plating, and the unnecessary electroless plating layer is then removed with a chemical solution or the like to form the desired wiring layer.

In addition, holes such as via holes may be formed in the resin layer as needed. The method for forming the holes is not particularly limited, and any conventionally known method can be used. Examples of methods that can be used for forming holes include NC drills, carbon dioxide lasers, UV lasers, YAG lasers, and plasma.

[Metal-clad laminate]
The laminate in the above-described embodiment may be in the form of a plate or may be a flexible laminate.
The laminate of this embodiment may be a metal-clad laminate.
The metal-clad laminate is obtained by laminating the resin composition of the present embodiment or the prepreg of the present embodiment and a metal foil, followed by curing, and a portion of the metal foil is removed from the metal-clad laminate.
The metal-clad laminate preferably has a configuration in which a cured prepreg (also referred to as a "cured composite") and a metal foil are laminated and adhered together, and is suitably used as a material for electronic circuit boards.

Examples of metal foils include aluminum foil and copper foil, and among these, copper foil is preferred because of its low electrical resistance.
The cured prepreg to be combined with the metal foil may be one or more sheets, and depending on the application, the metal foil is placed on one or both sides of the cured product to form a laminate.
Examples of the method for producing the laminate include a method in which a prepreg composed of the resin composition of the present embodiment and a substrate is formed, this is layered on a metal foil, and the resin composition is cured to obtain a laminate in which the cured prepreg and the metal foil are laminated together.
One particularly preferred application of the laminate is a printed wiring board, which is preferably a metal-clad laminate from which at least a portion of the metal foil has been removed.
The printed wiring board can be produced by a pressure and heat molding method using the prepreg of the present embodiment described above. The substrate can be the same as that described above for the prepreg. By including the resin composition of the present embodiment, the printed wiring board has excellent strength and electrical properties (low dielectric constant and low dielectric loss tangent), and can suppress fluctuations in electrical properties due to environmental changes, and has excellent insulation reliability and mechanical properties.

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

Below, we will explain this embodiment in detail using 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 block copolymer (component (I)) used in the following examples and comparative examples are shown below.

[Methods for identifying polymer structure and measuring physical properties]
((1) Content of vinyl aromatic monomer units in block copolymer)
The content of vinyl aromatic monomer units in the block copolymer before hydrogenation was measured using an ultraviolet spectrophotometer (Shimadzu Corporation, UV-2450).

((2) Amount of vinyl bond in block copolymer)
The vinyl bond content of the block copolymer before hydrogenation was measured using an infrared spectrophotometer (manufactured by JASCO Corporation, FT/IR-230).
The vinyl bond content of the block copolymer was calculated by the Hampton method.

((3) Molecular Weight and Molecular Weight Distribution of Block Copolymer)
The molecular weight of the component (I) block copolymer before modification and before hydrogenation was measured by GPC [apparatus: LC-10 (Shimadzu Corporation), column: TSKgel GMHXL (4.6 mm x 30 cm)].
The solvent used was tetrahydrofuran.
The measurement was carried out at a temperature of 35°C.
The molecular weight is a weight average molecular weight determined by using the molecular weight of the peak in the chromatogram and a calibration curve (prepared using the peak molecular weight of the standard polystyrene) determined from measurements of commercially available standard polystyrene.
When there are multiple peaks in the chromatogram, the molecular weight is the average molecular weight calculated from the molecular weight of each peak and the composition ratio of each peak (calculated from the area ratio of each peak in the chromatogram). The molecular weight distribution is the ratio (Mw/Mn) of the obtained weight average molecular weight (Mw) to the number average molecular weight (Mn).

((4) Hydrogenation rate of double bonds of conjugated diene monomer units of block copolymer)
Component (I) after hydrogenation: The hydrogenation rate of the double bonds of the conjugated diene monomer units was measured using a nuclear magnetic resonance spectrometer (manufactured by BRUKER, DPX-400) for the block copolymer.

((5) Mass Ratio of Vinyl Aromatic Monomer Units to Conjugated Diene Monomer Units in Polymer Block (C))
Each time the vinyl aromatic compound (styrene) and conjugated diene compound (butadiene) constituting each polymer block were added to the reaction vessel, the polymerization solution was sampled before the addition. Approximately 20 mL of the sampled polymer solution was injected into a sealed 100 mL bottle containing 0.50 mL of n-propylbenzene and approximately 20 mL of toluene as internal standards, to prepare a measurement sample. The measurement sample was measured using a gas chromatograph (Shimadzu Corporation: GC-14B) equipped with a backed column loaded with Apiezon grease. The amount of residual monomer in the polymer solution was determined from the previously obtained calibration curves for butadiene monomer and styrene monomer, and the polymerization rates of butadiene monomer and styrene monomer were confirmed to be 100%. Therefore, the compositional ratio of vinyl aromatic monomer units to conjugated diene monomer units in polymer block (C) was set to the same value as the mass ratio of the added vinyl aromatic monomer and conjugated diene monomer units.
The polymerization rate of butadiene was measured at a constant temperature of 90°C, and the polymerization rate of styrene was measured under the conditions of 90°C (held for 10 minutes) to 150°C (at a rate of 10°C/min).
The compositions of the polymer block (C) are shown in Tables 1 and 2. The sum of these is the content (parts by mass) of the polymer block (C) relative to 100 parts by mass of the block copolymer.

[Block copolymer, resin composition material]
(Preparation of hydrogenation catalyst)
In the examples and comparative examples described later, the hydrogenation catalyst used in producing the block copolymer was prepared by the following method.
A reaction vessel equipped with a stirrer was purged with nitrogen, and 1 liter of dried and purified cyclohexane was placed in the vessel.
Next, 100 mmol of bis(η5-cyclopentadienyl)titanium dichloride was added, and an n-hexane solution containing 200 mmol of trimethylaluminum was added while thoroughly stirring, and the reaction was carried out at room temperature for about 3 days, thereby obtaining a hydrogenation catalyst.

(Component (I) Block Copolymer)
A block copolymer of a vinyl aromatic compound and a conjugated diene was prepared as follows.
The structure and physical properties of each block copolymer are shown in Tables 1 and 2.
In the table, (A) denotes a polymer block (A) mainly composed of vinyl aromatic monomer units, (B) denotes a polymer block (B) mainly composed of conjugated diene monomer units, and (C) denotes a polymer block (C) composed of vinyl aromatic monomer units and conjugated diene monomer units.

<Block copolymer (1)>
Batch polymerization was carried out using a tank-type reactor (internal volume: 10 L) equipped with a stirrer and a jacket.
First, a cyclohexane solution (concentration: 20% by mass) containing 35 parts by mass of styrene was added.
Next, 0.45 parts by mass of n-butyllithium per 100 parts by mass of the total monomers and 0.8 mol of tetramethylethylenediamine (TMEDA) per 1 mol of n-butyllithium were added, and polymerization was carried out at 70° C. for 20 minutes.
Next, a cyclohexane solution (concentration: 20% by mass) containing 35 parts by mass of styrene and 30 parts by mass of butadiene was added and polymerized at 70° C. for 30 minutes.
Thereafter, methanol was added to terminate the polymerization reaction, thereby obtaining a block copolymer.
The block copolymer (1) obtained as described above had a styrene content of 70% by mass, a weight-average molecular weight of 1.5 × 10 ⁴ , a molecular weight distribution of 1.10, and a content of units (a) derived from 1,2-bonds and/or 3,4-bonds (vinyl bond amount: units (a)/conjugated diene monomer units in polymer block (C)) of 70%.

<Block copolymer (2)>
Batch polymerization was carried out using a tank-type reactor (internal volume: 10 L) equipped with a stirrer and a jacket.
First, a cyclohexane solution containing 15 parts by mass of butadiene (concentration: 20% by mass) was added.
Next, 0.45 parts by mass of n-butyllithium per 100 parts by mass of the total monomers and 0.8 mol of tetramethylethylenediamine (TMEDA) per 1 mol of n-butyllithium were added, and polymerization was carried out at 70° C. for 10 minutes.
Next, a cyclohexane solution (concentration: 20% by mass) containing 70 parts by mass of styrene and 15 parts by mass of butadiene was added and polymerized at 70° C. for 30 minutes.
Thereafter, methanol was added to terminate the polymerization reaction, thereby obtaining a block copolymer.
The block copolymer (2) obtained as described above had a styrene content of 70% by mass, a weight-average molecular weight of 1.5 × 10 ⁴ , a molecular weight distribution of 1.10, and a content of units (a) derived from 1,2-bonds and/or 3,4-bonds (vinyl bond amount: units (a)/(conjugated diene monomer units in polymer block (B) + polymer block (C))) of 70%.

<Block copolymer (3)>
Batch polymerization was carried out using a tank-type reactor (internal volume: 10 L) equipped with a stirrer and a jacket.
First, a cyclohexane solution containing 10 parts by mass of butadiene (concentration: 20% by mass) was added.
Next, 0.45 parts by mass of n-butyllithium per 100 parts by mass of the total monomers and 0.8 mol of tetramethylethylenediamine (TMEDA) per 1 mol of n-butyllithium were added, and polymerization was carried out at 70° C. for 15 minutes.
Next, a cyclohexane solution (concentration: 20% by mass) containing 70 parts by mass of styrene and 10 parts by mass of butadiene was added and polymerized at 70° C. for 30 minutes.
Next, a cyclohexane solution (concentration: 20% by mass) containing 10 parts by mass of butadiene was added and polymerization was carried out for 15 minutes, after which methanol was added to terminate the polymerization reaction, thereby obtaining a block copolymer.
The block copolymer (3) obtained as described above had a styrene content of 70% by mass, a weight average molecular weight of 1.5 × 10 ⁴ , a molecular weight distribution of 1.10, and a content of units (a) derived from 1,2-bonds and/or 3,4-bonds (vinyl bond amount: units (a)/(conjugated diene monomer units in polymer block (B) + polymer block (C))) of 71%.

<Block copolymer (4)>
Batch polymerization was carried out using a tank-type reactor (internal volume: 10 L) equipped with a stirrer and a jacket.
First, a cyclohexane solution (concentration: 20% by mass) containing 5 parts by mass of styrene was added.
Next, 0.65 parts by mass of n-butyllithium per 100 parts by mass of the total monomers and 0.8 mol of tetramethylethylenediamine (TMEDA) per 1 mol of n-butyllithium were added, and polymerization was carried out at 70° C. for 7 minutes.
Next, a cyclohexane solution (concentration: 20% by mass) containing 5 parts by mass of styrene and 90 parts by mass of butadiene was added and polymerized at 70° C. for 40 minutes.
Thereafter, methanol was added to terminate the polymerization reaction, thereby obtaining a block copolymer.
The block copolymer (4) obtained as described above had a styrene content of 10% by mass, a weight-average molecular weight of 1.5 × ¹⁰ , a molecular weight distribution of 1.10, and a content of units (a) derived from 1,2-bonds and/or 3,4-bonds (vinyl bond amount: units (a)/conjugated diene monomer units in polymer block (C)) of 69%.

<Block copolymer (5)>
Batch polymerization was carried out using a tank-type reactor (internal volume: 10 L) equipped with a stirrer and a jacket.
First, a cyclohexane solution containing 25 parts by mass of butadiene (concentration: 20% by mass) was added.
Next, 0.65 parts by mass of n-butyllithium per 100 parts by mass of the total monomers and 0.8 mol of tetramethylethylenediamine (TMEDA) per 1 mol of n-butyllithium were added, and polymerization was carried out at 70° C. for 15 minutes.
Next, a cyclohexane solution (concentration: 20% by mass) containing 35 parts by mass of styrene and 15 parts by mass of butadiene was added and polymerized at 70° C. for 20 minutes.
Next, a cyclohexane solution (concentration: 20% by mass) containing 25 parts by mass of butadiene was added and polymerization was carried out for 15 minutes, after which methanol was added to terminate the polymerization reaction, thereby obtaining a block copolymer.
The block copolymer (5) obtained as described above had a styrene content of 35% by mass, a weight-average molecular weight of 1.5 × 10 ⁴ , a molecular weight distribution of 1.10, and a content of units (a) derived from 1,2-bonds and/or 3,4-bonds (vinyl bond amount: units (a)/(conjugated diene monomer units in polymer block (B) + polymer block (C))) of 70%.

<Block copolymer (6)>
Batch polymerization was carried out using a tank-type reactor (internal volume: 10 L) equipped with a stirrer and a jacket.
First, a cyclohexane solution containing 15 parts by mass of butadiene (concentration: 20% by mass) was added.
Next, 0.65 parts by mass of n-butyllithium per 100 parts by mass of the total monomers and 0.8 mol of tetramethylethylenediamine (TMEDA) per 1 mol of n-butyllithium were added, and polymerization was carried out at 70° C. for 10 minutes.
Next, a cyclohexane solution (concentration: 20% by mass) containing 55 parts by mass of styrene and 15 parts by mass of butadiene was added and polymerized at 70° C. for 30 minutes.
Next, a cyclohexane solution (concentration: 20% by mass) containing 15 parts by mass of butadiene was added and polymerization was carried out for 15 minutes, after which methanol was added to terminate the polymerization reaction, thereby obtaining a block copolymer.
The block copolymer (6) obtained as described above had a styrene content of 55% by mass, a weight-average molecular weight of 1.5 × 10 ⁴ , a molecular weight distribution of 1.10, and a content of units (a) derived from 1,2-bonds and/or 3,4-bonds (vinyl bond amount: units (a)/(conjugated diene monomer units in polymer block (B) + polymer block (C))) of 70%.

<Block copolymer (7)>
Batch polymerization was carried out using a tank-type reactor (internal volume: 10 L) equipped with a stirrer and a jacket.
First, a cyclohexane solution containing 5 parts by mass of butadiene (concentration: 20% by mass) was added.
Next, 0.65 parts by mass of n-butyllithium per 100 parts by mass of the total monomers and 0.8 mol of tetramethylethylenediamine (TMEDA) per 1 mol of n-butyllithium were added, and polymerization was carried out at 70° C. for 5 minutes.
Next, a cyclohexane solution (concentration: 20% by mass) containing 90 parts by mass of styrene and 5 parts by mass of butadiene was added and polymerization was carried out at 70° C. for 35 minutes.
Thereafter, methanol was added to terminate the polymerization reaction, thereby obtaining a block copolymer.
The block copolymer (7) obtained as described above had a styrene content of 90% by mass, a weight-average molecular weight of 1.5 × 10 ⁴ , a molecular weight distribution of 1.10, and a content of units (a) derived from 1,2-bonds and/or 3,4-bonds (vinyl bond amount: units (a)/(conjugated diene monomer units in polymer block (B) + polymer block (C))) of 70%.

<Block copolymer (8)>
A polymerization reaction was carried out in the same manner as in the block copolymer (3), except that 0.23 parts by mass of n-butyllithium was added based on 100 parts by mass of the total monomers.
The block copolymer (8) obtained as described above had a styrene content of 70% by mass, a weight-average molecular weight of 3.0 × 10 ⁴ , a molecular weight distribution of 1.10, and a content of units (a) derived from 1,2-bonds and/or 3,4-bonds (vinyl bond amount: units (a)/(conjugated diene monomer units in polymer block (B)+polymer block (C))) of 70%.

<Block copolymer (9)>
A polymerization reaction was carried out in the same manner as in the block copolymer (3), except that 0.29 parts by mass of n-butyllithium was added relative to 100 parts by mass of the total monomers.
The block copolymer (9) obtained as described above had a styrene content of 70% by mass, a weight-average molecular weight of 2.5 × 10 ⁴ , a molecular weight distribution of 1.10, and a content of units (a) derived from 1,2-bonds and/or 3,4-bonds (vinyl bond amount: units (a)/(conjugated diene monomer units in polymer block (B) + polymer block (C))) of 70%.

<Block copolymer (10)>
A polymerization reaction was carried out in the same manner as in the block copolymer (3), except that 1.4 parts by mass of n-butyllithium was added based on 100 parts by mass of the total monomers.
The block copolymer (10) obtained as described above had a styrene content of 70% by mass, a weight-average molecular weight of 0.5 × 10 ⁴ , a molecular weight distribution of 1.10, and a content of units (a) derived from 1,2-bonds and/or 3,4-bonds (vinyl bond amount: units (a)/(conjugated diene monomer units in polymer block (B) + polymer block (C))) of 70%.

<Block copolymer (11)>
The polymerization reaction was carried out in the same manner as in the case of the block copolymer (3), except that 0.1 mol of TMEDA was added per 1 mol of n-butyllithium.
The block copolymer (11) obtained as described above had a styrene content of 70% by mass, a weight-average molecular weight of 1.5 × 10 ⁴ , a molecular weight distribution of 1.10, and a content of units (a) derived from 1,2-bonds and/or 3,4-bonds (vinyl bond amount: units (a)/conjugated diene monomer units in polymer block (B)+polymer block (C)) of 30%.

<Block copolymer (12)>
The polymerization reaction was carried out in the same manner as in the block copolymer (3), except that 2 mol of TMEDA was added per 1 mol of n-butyllithium, the polymerization temperature was set to 50° C., and the polymerization time for each block was extended by 10 minutes.
The block copolymer (12) obtained as described above had a styrene content of 70% by mass, a weight-average molecular weight of 1.5 × 10 ⁴ , a molecular weight distribution of 1.13, and a content of units (a) derived from 1,2-bonds and/or 3,4-bonds (vinyl bond amount: units (a)/(conjugated diene monomer units in polymer block (B) + polymer block (C))) of 85%.

<Block copolymer (13)>
A polymerization reaction was carried out in the same manner as in the case of block copolymer (3). Using the obtained block copolymer, the hydrogenation catalyst prepared as described above was added in an amount of 50 ppm (Ti basis) per 100 parts by mass of the block copolymer, and a hydrogenation reaction was carried out at a hydrogen pressure of 0.7 MPa and a temperature of 80°C for about 0.5 hours to obtain hydrogenated block copolymer (13).
The hydrogenated block copolymer (13) obtained as described above had a styrene content of 70% by mass, a weight-average molecular weight of 1.5 × 10 ⁴ , a molecular weight distribution of 1.10, a content of units (a) derived from 1,2-bonds and/or 3,4-bonds (vinyl bond amount: units (a)/(conjugated diene monomer units in polymer block (B)+polymer block (C))) of 70%, and a hydrogenation rate of 50%.

<Block copolymer (14)>
The same procedure was followed as for block copolymer (13), except that the hydrogenation reaction was carried out for about 0.25 hours.
The hydrogenated block copolymer (14) obtained as described above had a styrene content of 70% by mass, a weight average molecular weight of 1.5 × 10 ⁴ , a molecular weight distribution of 1.10, a content of units (a) derived from 1,2-bonds and/or 3,4-bonds (vinyl bond amount: units (a)/(conjugated diene monomer units in polymer block (B)+polymer block (C))) of 70%, and a hydrogenation rate of 22%.

<Block copolymer (15)>
The same procedure as for block copolymer (13) was carried out, except that the hydrogenation reaction was carried out for about 0.75 hours.
The hydrogenated block copolymer (15) obtained as described above had a styrene content of 70% by mass, a weight average molecular weight of 1.5 × 10 ⁴ , a molecular weight distribution of 1.10, a content of units (a) derived from 1,2-bonds and/or 3,4-bonds (vinyl bond amount: units (a)/(conjugated diene monomer units in polymer block (B)+polymer block (C))) of 71%, and a hydrogenation rate of 69%.

<Block copolymer (16)>
A polymerization reaction was carried out in the same manner as in the block copolymer (1), except that 0.18 parts by mass of n-butyllithium was added based on 100 parts by mass of the total monomers.
The block copolymer (16) obtained as described above had a styrene content of 70% by mass, a weight-average molecular weight of 4.0 × 10 ⁴ , a molecular weight distribution of 1.10, and a content of units (a) derived from 1,2-bonds and/or 3,4-bonds (vinyl bond amount: units (a)/conjugated diene monomer units in polymer block (C)) of 71%.

<Block copolymer (17)>
A polymerization reaction was carried out in the same manner as in the block copolymer (2), except that 0.18 parts by mass of n-butyllithium was added based on 100 parts by mass of the total monomers.
The block copolymer (17) obtained as described above had a styrene content of 70% by mass, a weight-average molecular weight of 4.0 × 10 ⁴ , a molecular weight distribution of 1.10, and a content of units (a) derived from 1,2-bonds and/or 3,4-bonds (vinyl bond amount: units (a)/(conjugated diene monomer units in polymer block (B) + polymer block (C))) of 70%.

<Block copolymer (18)>
A polymerization reaction was carried out in the same manner as in the block copolymer (3), except that 0.18 parts by mass of n-butyllithium was added based on 100 parts by mass of the total monomers.
The block copolymer (18) obtained as described above had a styrene content of 70% by mass, a weight-average molecular weight of 4.0 × 10 ⁴ , a molecular weight distribution of 1.10, and a content of units (a) derived from 1,2-bonds and/or 3,4-bonds (vinyl bond amount: units (a)/(conjugated diene monomer units in polymer block (B) + polymer block (C))) of 71%.

<Block copolymer (19)>
Batch polymerization was carried out using a tank-type reactor (internal volume: 10 L) equipped with a stirrer and a jacket.
First, a cyclohexane solution (concentration: 20% by mass) containing 30 parts by mass of butadiene and 70 parts by mass of styrene was added.
Next, 0.65 parts by mass of n-butyllithium per 100 parts by mass of the total monomers and 0.8 mol of tetramethylethylenediamine (TMEDA) per 1 mol of n-butyllithium were added, and polymerization was carried out at 70° C. for 40 minutes.
Thereafter, methanol was added to terminate the polymerization reaction, thereby obtaining a block copolymer.
The block copolymer (19) obtained as described above had a styrene content of 70% by mass, a weight-average molecular weight of 1.5 × 10 ⁴ , a molecular weight distribution of 1.10, and a content of units (a) derived from 1,2-bonds and/or 3,4-bonds (vinyl bond amount: units (a)/conjugated diene monomer units in polymer block (C)) of 70%.

<Block copolymer (20)>
Batch polymerization was carried out using a tank-type reactor (internal volume: 10 L) equipped with a stirrer and a jacket.
First, a cyclohexane solution (concentration: 20% by mass) containing 15 parts by mass of styrene was added.
Next, 0.65 parts by mass of n-butyllithium per 100 parts by mass of the total monomers and 0.8 mol of tetramethylethylenediamine (TMEDA) per 1 mol of n-butyllithium were added, and polymerization was carried out at 70° C. for 15 minutes.
Next, a cyclohexane solution containing 70 parts by mass of butadiene (concentration: 20% by mass) was added, and polymerization was carried out at 70° C. for 30 minutes.
Next, a cyclohexane solution (concentration: 20% by mass) containing 15 parts by mass of styrene was added, and polymerization was carried out at 70° C. for 15 minutes.
Thereafter, methanol was added to terminate the polymerization reaction, thereby obtaining a block copolymer.
The block copolymer (20) obtained as described above had a styrene content of 70% by mass, a weight-average molecular weight of 1.5 × 10 ⁴ , a molecular weight distribution of 1.10, and a content of units (a) derived from 1,2-bonds and/or 3,4-bonds (vinyl bond amount: units (a)/polymer block (B)) of 70%.

<Block copolymer (21)>
Batch polymerization was carried out using a tank-type reactor (internal volume: 10 L) equipped with a stirrer and a jacket.
First, a cyclohexane solution (concentration: 20% by mass) containing 30 parts by mass of styrene was added.
Next, 0.65 parts by mass of n-butyllithium per 100 parts by mass of the total monomers and 0.8 mol of tetramethylethylenediamine (TMEDA) per 1 mol of n-butyllithium were added, and polymerization was carried out at 70° C. for 30 minutes.
Next, a cyclohexane solution containing 70 parts by mass of butadiene (concentration: 20% by mass) was added, and polymerization was carried out at 70° C. for 30 minutes.
Thereafter, methanol was added to terminate the polymerization reaction, thereby obtaining a block copolymer.
The block copolymer (21) obtained as described above had a styrene content of 70% by mass, a weight-average molecular weight of 1.5 × 10 ⁴ , a molecular weight distribution of 1.10, and a content of units (a) derived from 1,2-bonds and/or 3,4-bonds (vinyl bond amount: units (a)/polymer block (B)) of 70%.

<Block copolymer (22)>
Batch polymerization was carried out using a tank-type reactor (internal volume: 10 L) equipped with a stirrer and a jacket.
First, a cyclohexane solution containing 20 parts by mass of butadiene (concentration: 20% by mass) was added.
Next, 0.45 parts by mass of n-butyllithium per 100 parts by mass of the total monomers and 0.8 mol of tetramethylethylenediamine (TMEDA) per 1 mol of n-butyllithium were added, and polymerization was carried out at 70° C. for 15 minutes.
Next, a cyclohexane solution (concentration: 20% by mass) containing 60 parts by mass of styrene was added, and polymerization was carried out at 70° C. for 45 minutes.
Next, a cyclohexane solution (concentration: 20% by mass) containing 10 parts by mass of styrene and 10 parts by mass of butadiene was added, and polymerization was carried out at 70° C. for 20 minutes.
Thereafter, methanol was added to terminate the polymerization reaction, thereby obtaining a block copolymer.
The block copolymer (22) obtained as described above had a styrene content of 70% by mass, a weight average molecular weight of 1.5 × 10 ⁴ , a molecular weight distribution of 1.10, and a content of units (a) derived from 1,2-bonds and/or 3,4-bonds (vinyl bond amount: units (a)/(conjugated diene monomer units in polymer block (B) + polymer block (C))) of 69%.

<Block copolymer (23)>
Batch polymerization was carried out using a tank-type reactor (internal volume: 10 L) equipped with a stirrer and a jacket.
First, a cyclohexane solution containing 10 parts by mass of butadiene (concentration: 20% by mass) was added.
Next, 0.28 parts by mass of n-butyllithium per 100 parts by mass of the total monomers and 0.8 mol of tetramethylethylenediamine (TMEDA) per 1 mol of n-butyllithium were added, and polymerization was carried out at 70° C. for 10 minutes.
Next, a cyclohexane solution (concentration: 20% by mass) containing 50 parts by mass of styrene was added, and polymerization was carried out at 70° C. for 30 minutes.
Next, a cyclohexane solution (concentration: 20% by mass) containing 20 parts by mass of styrene and 20 parts by mass of butadiene was added, and polymerization was carried out at 70° C. for 30 minutes.
Thereafter, methanol was added to terminate the polymerization reaction, thereby obtaining a block copolymer.
The block copolymer (23) obtained as described above had a styrene content of 70% by mass, a weight-average molecular weight of 2.6 × 10 ⁴ , a molecular weight distribution of 1.10, and a content of units (a) derived from 1,2-bonds and/or 3,4-bonds (vinyl bond amount: units (a)/conjugated diene monomer units in polymer block (B)+polymer block (C)) of 70%.

(Component (II): Radical initiator)
Perbutyl C (NOF Corporation)
Parkmill D (manufactured by NOF Corporation)

(Component (III): Polar Resin)
As a polar resin, a polyphenylene ether resin (PPE) was polymerized as follows.
A 1.5-liter jacketed reactor equipped with a sparger at the bottom for introducing oxygen-containing gas, stirring turbine blades and baffles, and a reflux condenser on the vent gas line at the top of the reactor was charged 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, 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 weight ratio of the solvents used was n-butanol:methanol = 70:30. Next, oxygen was introduced into the reactor via the sparger at a rate of 180 mL/min with vigorous stirring, and the polymerization temperature was adjusted to maintain 40°C by passing a heat medium through the jacket. The polymerization solution gradually took on the appearance of a slurry. When the polyphenylene ether reached the desired number-average molecular weight, the oxygen-containing gas was stopped and the resulting polymerization mixture was heated to 50°C. Next, hydroquinone (a reagent manufactured by Wako Pure Chemical Industries, Ltd.) was added in small amounts, and the mixture was kept at 50°C until the slurry-like polyphenylene ether turned white. Next, 720 g of a methanol solution containing 6.5 mass% of 36% hydrochloric acid was added, and the mixture was filtered and repeatedly washed with methanol to obtain wet polyphenylene ether. Next, the mixture was vacuum-dried at 100°C to obtain dry polyphenylene ether. The ηsp/c was 0.103 dl/g, and the yield was 97%.
The ηsp/c was measured by preparing a 0.5 g/dl chloroform solution of the polyphenylene ether and determining the reduced viscosity (ηsp/c) at 30° C. using an Ubbelohde viscometer. The unit is dl/g.
The resulting 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. 2.1 g of dimethylaminopyridine was then added. Once all solids had dissolved, 18.28 g of methacrylic anhydride was slowly added. The resulting solution was maintained at 85°C for 3 hours with continuous mixing. The solution was then cooled to room temperature to obtain a toluene solution of methacrylate-capped polyphenylene ether. 1000 mL of 10°C methanol was added dropwise to the resulting toluene solution in a 3 L cylindrical SUS container equipped with a homogenizer for stirring. The resulting powder was filtered, washed with methanol, and dried at 85°C under nitrogen for 18 hours.

(Component (IV): Curing Agent)
Triallyl isocyanurate (TAIC ^™ ) (manufactured by Mitsubishi Chemical Corporation)

[Method for measuring physical properties of resin composition]
((1) Dielectric Loss Tangent and Dielectric Constant)
The dielectric loss tangent at 10 GHz was measured by a cavity resonance method.
The measurement devices used were a network analyzer (N5230A, manufactured by Agilent Technologies) and a cavity resonator (Cavity Resonator CP series, manufactured by Kanto Electronics Application Development Co., Ltd.).
The measurement sample was a test piece measuring 2.6 mm wide x 80 mm long cut out from a cured film described below.
Using the dielectric loss tangent and dielectric constant obtained above, the following examples and comparative examples were evaluated according to the following criteria.

<Evaluation criteria for Examples 1 to 18 and Comparative Examples 1 to 8>
Dielectric tangent
◎: 0.0025 or less
○: 0.0030 or less
△: Less than 0.0035
×: Dielectric constant of 0.0035 or more
◎: 2.53 or less
○: 2.55 or less
△: Less than 2.60
×: 2.60 or more

<Evaluation criteria for Examples 19 to 31 and Comparative Examples 9 to 22>
The evaluation was based on the difference in dielectric loss tangent and dielectric constant between Comparative Example 9, which does not contain a block copolymer, and each Example or Comparative Example (Comparative Example 9 - each Example or Comparative Example).
Dielectric tangent
◎: 0.0012 or more
○: 0.0010 or more and less than 0.0012
△: 0.0080 or more and less than 0.0010
×: Less than 0.0080 (including the same value and positive difference)
dielectric constant
◎: 0.12 or more
○: 0.10 or more and less than 0.12
△: 0.08 or more and less than 0.10
×: Less than 0.08 (including equal and positive differences)

<Evaluation criteria for Examples 32 to 47 and Comparative Examples 23 to 37>
The evaluation was based on the difference in dielectric loss tangent and dielectric constant between Comparative Example 23, which does not contain a block copolymer, and each Example or Comparative Example (Comparative Example 23 - each Example or Comparative Example).
Dielectric tangent
◎: 0.010 or more
○: 0.008 or more and less than 0.010
△: 0.005 or more and less than 0.008
×: Less than 0.005 (including equal and positive differences)
dielectric constant
◎: 0.4 or more
○: 0.3 or more and less than 0.4
△: 0.2 or more and less than 0.3
×: Less than 0.2 (including equal and positive differences)

<Evaluation criteria for Examples 48 to 58 and Comparative Examples 38 to 54>
The evaluation was based on the difference in dielectric loss tangent and dielectric constant between Comparative Example 38, which does not contain a block copolymer, and each Example or Comparative Example (Comparative Example 38 - each Example or Comparative Example).
Dielectric tangent
◎: 0.0012 or more
○: 0.0010 or more and less than 0.0012
△: 0.0080 or more and less than 0.0010
×: Less than 0.0080 (including the same value and positive difference)
dielectric constant
◎: 0.15 or more
○: 0.12 or more and less than 0.15
△: 0.10 or more and less than 0.12
×: Less than 0.10 (including equal and positive differences)

((2) Strength (glass transition temperature: Tg))
The dynamic viscoelasticity of the resin compositions of the examples and comparative examples described below was measured, and the temperature at which tan δ was maximized was determined as the glass transition temperature (Tg).
A high Tg indicates high strength over a wide temperature range.
The measurement was performed using an ARES (trade name, manufactured by TA Instruments) in a tensile mode. A test piece measuring 35 mm in length, approximately 12.5 mm in width, and 0.3 mm in thickness was cut out from the cured film described below, and this was used as the measurement sample.
The measurement was carried out under the conditions of a frequency of 10 rad/s and a measurement temperature of -150 to 270°C.

[Preparation of Resin Composition]
(Examples 1 to 8, Reference Example 9, Examples 10 to 27, Reference Example 28, Examples 29 to 31), (Comparative Examples 1 to 22)
Using the above-mentioned components, a resin composition was prepared by the following preparation method.
The component ratios and physical properties are shown in Tables 3 to 6 below.
First, each component was added to toluene (special grade product manufactured by Wako Pure Chemical Industries, Ltd., used as is), stirred and dissolved to prepare a varnish with a concentration of 20% by mass to 50% by mass.
The varnish was applied to a release-treated Kapton film at a speed of 30 mm/sec, and then dried in a nitrogen stream at 100°C for 30 minutes in a blower dryer to obtain a film. The obtained film was cured in a nitrogen stream at 200°C for 90 minutes in a blower dryer to obtain a cured film.
The cured film was used as an evaluation sample.
Examples 1 to 8, Reference Example 9, Examples 10 to 27, Reference Example 28, Examples 29 to 31, and Comparative Examples 1 to 22 demonstrate that the block copolymers of the present invention, when cured, exhibit an excellent balance of dielectric performance and strength. In particular, the cured products of the present invention are suitable for use in printed wiring boards using glass cloth or metal laminates.

(Examples 32 to 41, Reference Example 42, Examples 43 to 47), (Comparative Examples 23 to 37)
In addition to the above-mentioned components, the following components were further used to prepare resin compositions according to the following preparation method.

<Component (II): Radical Initiator>
Perbutyl P-90 (NOF Corporation)
<Component (III): Polar Resin>
Bisphenol A epoxy resin EXA-850CRP (DIC Corporation)
Phenoxy resin YP-50S (Nippon Steel Chemicals Co., Ltd.)
<Component (IV): Curing Agent>
1-benzyl-2-phenylimidazole (Tokyo Chemical Industry Co., Ltd.)
Phenol-based hardener KA-1163 (DIC Corporation)

The component ratios and physical properties are shown in Tables 7 and 8 below.
First, all components except the phenol-based curing agent were added to toluene, stirred and dissolved to prepare a varnish with a concentration of 20% by mass to 50% by mass.
When a phenolic curing agent was used, a 50% by mass solution of the phenolic curing agent was prepared using methyl ethyl ketone (a special grade product manufactured by Wako Pure Chemical Industries, Ltd.) as a solvent, and the solution was added to the varnish and stirred to prepare a varnish.
The varnish was applied to a release-treated Kapton film at a speed of 30 mm/sec, and then dried in a nitrogen stream in a blower dryer at 100° C. for 30 minutes to obtain a film.
The resulting film was subjected to a curing reaction in a nitrogen stream in a blower dryer at 200° C. for 90 minutes to obtain a cured film.
The cured film was used as an evaluation sample.

(Examples 48 to 55, Reference Example 56, Examples 57 to 58), (Comparative Examples 38 to 54)
In addition to the above-mentioned components, the following components were further used to prepare resin compositions according to the following preparation method.
<Component (III): Polar Resin>
[Polyimide resin]
Bis(3-ethyl-5-methyl-4-maleimidophenyl)methane (BMI-70) (K.I. Chemical Co., Ltd.)
4,4'-bismaleimidodiphenylmethane (BMI-H) (manufactured by K.I. Kasei Co., Ltd.)
<Component (IV): Curing Agent>
Cyanate ester curing agent: 2,2-bis(4-cyanatephenyl)propane (Tokyo Chemical Industry Co., Ltd.)
Diamine curing agent: 4,4'-diaminodiphenylmethane (Tokyo Chemical Industry Co., Ltd.)

The component ratios and physical properties are shown in Tables 9 and 10 below.
First, a polyimide resin, which is a polar resin, and a cyanate ester curing agent and/or a diamine curing agent were dissolved at 160°C in the blending ratios shown in Tables 9 and 10 below, and the mixture was reacted for 6 hours with stirring to obtain a bismaleimide triazine resin oligomer.
The obtained bismaleimide triazine resin oligomer was dissolved in toluene, and the remaining components were added and stirred to dissolve, thereby preparing a varnish having a concentration of 20% to 50% by mass.
The varnish was applied onto a release-treated Kapton film at a speed of 30 mm/sec.
Thereafter, the film was dried in a nitrogen stream in a blower dryer at 100° C. for 30 minutes to obtain a film.
The film was subjected to a curing reaction in a nitrogen stream in a blower dryer at 200° C. for a maximum of 90 minutes to obtain a cured film.
The cured film was used as an evaluation sample.
Examples 48 to 58 and Comparative Examples 38 to 54 demonstrate that the block copolymers of the present invention, when cured, have an excellent balance of dielectric properties and strength. The cured products of the present invention are suitable for use in printed wiring boards using glass cloth and metal laminates.

This application is based on a Japanese patent application (Patent Application No. 2022-033349) filed with the Japan Patent Office on March 4, 2022, and an international application (PCT/JP2023/000860) filed on January 13, 2023, the contents of which are incorporated herein by reference.

The block copolymer of the present invention, resin compositions containing the block copolymer, and cured products have industrial applicability as materials for films, prepregs, electronic circuit boards, and next-generation communication boards.

Claims (11)

a polymer block (C) which is a random block composed of vinyl aromatic monomer units and conjugated diene monomer units;
The polymer block (A) mainly contains vinyl aromatic monomer units and/or the polymer block (B) mainly contains conjugated diene monomer units,
It is a block copolymer that satisfies the following conditions (i) to (iv):
The conjugated diene monomer units in the block copolymer contain units (a) derived from a 1,2-bond and/or a 3,4-bond and units (b) derived from a 1,4-bond, and the content of the units (a) derived from a 1,2-bond and/or a 3,4-bond is 25 to 85% when the total content of the conjugated diene monomer units in the block copolymer is taken as 100% .
<Condition (i)>
The mass ratio of the vinyl aromatic monomer units to the conjugated diene monomer units in the polymer block (C) is vinyl aromatic monomer units/conjugated diene monomer units=5/95 to 95/5.
<Condition (ii)>
The content of the polymer block (C) is 5 parts by mass or more and 95 parts by mass or less based on 100 parts by mass of the block copolymer.
<Condition (iii)>
The weight average molecular weight is 35,000 or less.
<Condition (iv)>
The content of the vinyl aromatic monomer unit is 5 parts by mass or more and 80 parts by mass or less based on 100 parts by mass of the block copolymer. Component (I): the block copolymer of claim 1;
Contains at least one component selected from the group consisting of the following components (II) to (IV):
Resin composition.
Component (II): A radical initiator. Component (III): At least one polar resin selected from the group consisting of polyphenylene ether resins, bisphenol A epoxy resins, phenoxy resins, and polyimide resins (excluding component (I)).
Component (IV): Curing agent (excluding component (II)) Contains the component (III),
3. The resin composition according to claim 2, wherein the component (III) is at least one selected from the group consisting of bisphenol A epoxy resins, polyimide resins, polyphenylene ether resins, and phenoxy resins . A cured product containing the block copolymer described in claim 1. A cured product of the resin composition described in claim 2 or 3. A resin film made from the resin composition described in claim 2 or 3. A substrate;
A prepreg which is a composite with the resin composition according to claim 2 or 3. The prepreg according to claim 7, wherein the substrate is glass cloth. A laminate comprising the resin film of claim 6 and a metal foil. A cured product of the prepreg according to claim 7, a metal foil,
A laminate having: A material for electronic circuit boards comprising the cured product described in claim 5.