JP7505200B2 - Prepregs, metal-clad laminates, printed wiring boards, multilayer wiring boards and electronic devices - Google Patents

Description

The present invention relates to a prepreg. It also relates to a metal-clad laminate, a printed wiring board, and a multilayer wiring board that have an insulating layer made of a cured product of the prepreg. It also relates to an electronic device equipped with a printed wiring board, and an electronic device equipped with a multilayer wiring board.

Due to advances in technology for high-speed processing of large amounts of information, the frequency band of signals used in printed wiring boards and other devices is shifting from the megahertz range to the gigahertz range. Since the higher the frequency, the greater the transmission loss of electrical signals, there is a need to develop electronic materials with excellent dielectric properties in the high-frequency range, and printed wiring boards and other devices that use these materials.

Patent Document 1 proposes a prepreg having a semi-cured resin composition containing an epoxy resin, a curing agent, and a fluororesin filler, which is filled into a woven fabric and/or nonwoven fabric and covers the surface, with the objective of providing a high-frequency circuit board with excellent dielectric properties.

JP 2016-166347 A

In addition to satisfying low dielectric constant characteristics, prepregs are required to reduce the occurrence of warping of the board. However, adding a large amount of filler to reduce warping causes the board to lose flexibility, become hard and brittle, and become more susceptible to cracking. For this reason, there is a strong demand for prepregs and printed wiring boards that have low dielectric constant characteristics, low warping properties, and excellent crack resistance.

The present invention has been made in view of the above background, and aims to provide highly reliable prepregs, metal-clad laminates, printed wiring boards, multilayer wiring boards, and electronic devices that have excellent dielectric properties and low warpage, and can effectively reduce the occurrence of cracks.

As a result of extensive investigations, the inventors have found that the problems of this embodiment can be solved in the following aspect, and have completed the present invention.
[1]: A substrate and a semi-cured product of a thermosetting resin composition impregnated into the substrate,
The thermosetting resin composition comprises:
A composition (I) containing a styrene-based elastomer (P1) having a carboxylic acid anhydride group, and any one of a polyisocyanate component (C1), an epoxy compound (C4) and a phenol compound (C5) which reacts with the anhydride group;
a composition (II) containing a polyamide resin (P2) having a phenolic hydroxyl group in a side group and a tri- or higher functional compound (C2) capable of reacting with the phenolic hydroxyl group, or a composition (III) containing a polyurethane resin (P3) having a carboxyl group and an epoxy compound (C3) capable of reacting with the carboxyl group,
The cured product of the thermosetting resin composition is
A prepreg having a relative dielectric constant of 4.0 or less and a dielectric tangent of 0.010 or less.
[2] The styrene-based elastomer (P1) is
a block copolymer having at least one of a structural unit derived from an olefin and a structural unit derived from a conjugated diene, and a structural unit derived from styrene; and the polyisocyanate component (C1) is an isocyanate group-containing compound having two or more isocyanates;
The polyamide resin (P2) is
The polyamide resin (P2) satisfies the following (i) and/or (ii), and further, the polyamide resin (P2) of (i) satisfies the following (iii) and (vi), and the polyamide resin (P2) of (ii) satisfies the following (iv) to (vi),
The compound (C2) satisfies the following (vii):
2. The prepreg according to claim 1, wherein the polyurethane resin (P3) is a polyurethane polyurea resin.
(i) Polyamide resin (P2) is a polyamide (A-1) in which a phenolic hydroxyl group and a hydrocarbon group having 20 to 60 carbon atoms (but excluding the aromatic ring to which the phenolic hydroxyl group is bonded) are contained within the same polymer.
(ii) Polyamide resin (P2) is a polyamide (A-3) obtained by mixing polyamide (a-1) containing a phenolic hydroxyl group in a side group and polyamide (a-2) containing a hydrocarbon group having 20 to 60 carbon atoms.
(iii) Monomers constituting the polyamide (A-1) include a monomer having a phenolic hydroxyl group and a monomer having a hydrocarbon group having 20 to 60 carbon atoms.
(iv) The polybasic acid monomer and/or polyamine monomer constituting the polyamide (a-1) contains a monomer having a phenolic hydroxyl group, and the polybasic acid monomer and the polyamine monomer do not contain a monomer having a hydrocarbon group having 20 to 60 carbon atoms.
(v) The polybasic acid monomer and/or the polyamine monomer constituting the polyamide (a-2) contain a monomer having a hydrocarbon group having 20 to 60 carbon atoms, and the polybasic acid monomer and the polyamine monomer do not contain a monomer having a phenolic hydroxyl group.
(vi) At least a part of the monomers having a hydrocarbon group with 20 to 60 carbon atoms includes a compound having a cyclic structure with 5 to 10 carbon atoms.
(vii) The compound (C2) is at least one member selected from the group consisting of an epoxy group-containing compound, an isocyanate group-containing compound, a carbodiimide group-containing compound, a metal chelate, a metal alkoxide, and a metal acylate.
[3]: The prepreg according to [1] or [2], wherein the storage modulus at 25°C after curing of the thermosetting resin composition is 1 to 5000 MPa.
[4]: An insulating layer made of a cured product of the prepreg according to any one of [1] to [3];
A metal layer formed on one or both sides of the insulating layer.
[5]: An insulating layer made of a cured product of the prepreg according to any one of [1] to [3];
A circuit pattern formed on one or both sides of the insulating layer.
[6]: A multilayer wiring board in which two or more interlayer insulating layers and two or more circuit pattern layers are laminated, and at least one of the interlayer insulating layers is an insulating layer made of a cured product of the prepreg according to any one of [1] to [3].
[7]: An electronic device equipped with the printed wiring board according to [5] or the multilayer wiring board according to [6].

The present invention provides highly reliable prepregs, metal-clad laminates, printed wiring boards, multilayer wiring boards, and electronic devices that have excellent dielectric properties and low warpage, and can effectively reduce the occurrence of cracks.

An example of an embodiment to which the present invention is applied is described below. The numerical values specified in this specification are values determined by the methods disclosed in the embodiments or examples. Furthermore, the numerical values "A to B" specified in this specification refer to a range that satisfies numerical value A and a value greater than numerical value A, and numerical value B and a value smaller than numerical value B. Furthermore, the sheet in this specification includes not only sheets defined in JIS, but also films. Unless otherwise noted, the various components mentioned in this specification may be used independently, either alone or in combination of two or more types.

<<Prepreg>>
The prepreg according to the present embodiment includes a substrate and a semi-cured product of a thermosetting resin composition impregnated into the substrate. The prepreg can be manufactured by a known method using the thermosetting resin composition. For example, the prepreg can be manufactured by impregnating the substrate with the thermosetting resin composition, and then heating and drying the thermosetting resin composition to semi-cure (B-stage).

The thermosetting resin composition of this embodiment uses any one of the following compositions (I) to (III). Composition (I) is a thermosetting resin composition containing a styrene-based elastomer (P1) having a carboxylic acid anhydride group and any one of a polyisocyanate component (C1), an epoxy compound (C4) and a phenolic compound (C5) that reacts with the anhydride group. Hereinafter, the thermosetting resin composition containing the styrene-based elastomer (P1) and the polyisocyanate component (C1) is referred to as composition (I)-1, the thermosetting resin composition containing the styrene-based elastomer (P1) and the epoxy compound (C4) is referred to as composition (I)-2, and the thermosetting resin composition containing the styrene-based elastomer (P1) and the phenolic compound (C5) is referred to as composition (I)-3. Composition (II) is a thermosetting resin composition containing a polyamide resin (P2) having a phenolic hydroxyl group in a side group and a trifunctional or higher compound (C2) that can react with the phenolic hydroxyl group. Composition (III) is a thermosetting resin composition containing a polyurethane resin (P3) having a carboxyl group and an epoxy compound (C3) capable of reacting with the carboxyl group.

The cured product of the thermosetting resin composition of this embodiment has a dielectric constant of 4.0 or less and a dielectric dissipation factor of 0.010 or less. More preferably, the dielectric constant is 3.5 or less and the dielectric dissipation factor is 0.005 or less, and even more preferably, the dielectric constant is 3.2 or less and the dielectric dissipation factor is 0.003 or less. The lower limit values of the dielectric constant and the dielectric dissipation factor are not particularly limited, but the dielectric constant is usually 2.0 or more and the dielectric dissipation factor is 0.001 or more. The dielectric constant of the cured product of the thermosetting resin composition can be adjusted by the type of resin of the thermosetting resin composition and the type and amount of the filler.

The storage modulus of the cured product of the thermosetting resin composition of this embodiment at 25°C is preferably 1 to 5000 MPa. More preferably, the storage modulus is in the range of 5 to 2000 MPa, and even more preferably, the storage modulus is in the range of 10 to 1000 MPa. By making the storage modulus of the cured product of the thermosetting resin composition at 25°C 1 to 5000 MPa, the cured product of the prepreg has excellent low warpage properties and has the excellent effect of suppressing the occurrence of cracks.

The amount of solids of the thermosetting resin composition attached to the substrate is preferably 20 to 90% by mass in terms of the content of the thermosetting resin composition after drying in the prepreg. More preferably, it is 30 to 80% by mass, and even more preferably, it is 40 to 70% by mass. For example, the thermosetting resin composition of this embodiment can be impregnated or coated on a substrate so that the amount of solids of the thermosetting resin composition attached in the prepreg is 20 to 90% by mass, and then the substrate can be heated and dried at a temperature of, for example, 40 to 200°C for 1 to 30 minutes to be semi-cured (B-staged).

As the substrate, any known material can be used without restriction, and examples thereof include organic fibers, inorganic fibers, and glass fibers. Examples of organic fibers include polyimide, polyester, tetrafluoroethylene, and fully aromatic polyamide. Examples of inorganic fibers include carbon fibers. Examples of glass fibers include E-glass cloth, D-glass cloth, S-glass cloth, Q-glass cloth, NE-glass cloth, L-glass cloth, T-glass cloth, spherical glass cloth, and low-dielectric glass cloth. Among these, from the viewpoint of low thermal expansion coefficient, E-glass cloth, T-glass cloth, S-glass cloth, Q-glass cloth, and organic fibers are preferable. The substrate may be used alone or in combination of two or more types.

The shape of the substrate can be appropriately selected depending on the intended use and performance. Specific examples include woven fabric, nonwoven fabric, roving, chopped strand mat, and surfacing mat. Examples of the weaving method of the woven fabric include plain weave, sash weave, and twill weave. It can be arbitrarily selected and designed depending on the desired characteristics. The thickness of the substrate can be, for example, in the range of about 0.01 to 1.0 mm. From the viewpoint of thinning, 500 μm or less is preferable, and 300 μm or less is more preferable.

If necessary, the substrate can be surface-treated with a silane coupling agent or mechanically opened to bring out the desired properties. Corona treatment or plasma treatment may also be used. Surface treatments using silane coupling agents include amino silane coupling treatment, vinyl silane coupling treatment, cationic silane coupling treatment, and epoxy silane coupling treatment.

The method of impregnating the substrate with the thermosetting resin composition is not particularly limited, but examples include a method of preparing a varnish of the thermosetting resin composition using an organic solvent such as alcohols, ethers, acetals, ketones, esters, alcohol esters, ketone alcohols, ether alcohols, ketone ethers, ketone esters, or ester ethers, and immersing the substrate in the varnish, a method of coating or spraying the varnish onto the substrate, and a method of laminating both sides of the substrate with a film made of the thermosetting resin composition.

<<Thermosetting resin composition>>
The thermosetting resin composition according to the present embodiment has a relative dielectric constant of 4.0 or less and a dielectric dissipation factor of 0.010 or less after curing, and is selected from any one of the following compositions (I)-1, (I)-2, (I)-3, (II), and (III).

[[Composition (I)-1]]
Composition (I)-1 is a thermosetting resin composition containing a styrene-based elastomer (P1) having a carboxylic acid anhydride group (hereinafter sometimes abbreviated as an acid anhydride group) and a polyisocyanate component (C1) that reacts with the acid anhydride group. In this specification, the term "elastomer" refers to a polymer that has rubber elasticity at room temperature even without vulcanization treatment. In terms of chemical structure, it generally has an ABA type block or an (A-B)n type multiblock structure. Moreover, the styrene-based elastomer refers to a copolymer having a block having polystyrene (hereinafter also referred to as a polystyrene block).

<Styrene-based elastomer (P1)>
It is important that the styrene-based elastomer (P1) has a carboxylic acid anhydride group. By reacting the acid anhydride group in the styrene-based elastomer (P1) with the polyisocyanate component (C1) described later, it is possible to form an imide group that has excellent heat resistance and has the function of suppressing the dielectric constant and dielectric loss tangent to a low value.
A preferred example of the styrene-based elastomer (P1) is a block copolymer having at least one of a structural unit derived from an olefin and a structural unit derived from a conjugated diene, and a structural unit derived from styrene.
By using a styrene-based elastomer (P1) having a polystyrene structure in the molecule, excellent heat resistance can be achieved. Specific examples include styrene-butadiene block copolymer, styrene-ethylene-propylene block copolymer, styrene-butadiene-styrene block copolymer, styrene-isoprene-styrene block copolymer, styrene-ethylene-butylene-styrene block copolymer, styrene-ethylene-propylene block copolymer, styrene-isoprene-styrene block copolymer, etc.
In these styrene-based elastomers (P1), the portions other than the polystyrene block are regarded as one block. In addition, among the portions other than the polystyrene block, examples of the block formed from units (residues) derived from two or more monomers include, in the above example, a copolymer of ethylene and propylene and a copolymer of ethylene and butylene. Such a block formed from units derived from two or more monomers other than the polystyrene block may be a random copolymer or a block copolymer.

Imide groups can also be formed by the reaction of acid anhydride groups with amino groups, but this is not preferred for the following reasons: The first-stage reaction between an acid anhydride group and an amino group, i.e., the ring-opening reaction of the acid anhydride group by the amino group, is extremely fast, which shortens the usable time of the thermosetting adhesive.
The second-stage reaction between the acid anhydride group and the amino group, i.e., the reaction of forming an imide group by ring closure of an amic acid, requires higher heating temperature than the reaction of the acid anhydride group and the isocyanate group to form an imide group. If the heating is insufficient, the amic acid, which is the precursor of the imide group, remains, and the dielectric constant and dielectric tangent become high. Furthermore, if the amic acid remains, when the prepreg described below, or a metal-clad laminate, printed wiring board, multilayer wiring board, etc. containing the cured product of the prepreg are placed in a solder bath or a solder reflow furnace, the imidization reaction accompanied by the elimination of water proceeds explosively, causing foaming.
When the carboxylic anhydride group of the styrene-based elastomer (P1) and the isocyanate group of the polyisocyanate component (C) are heat-cured at about 150 to 200°C, the heat resistance and insulating property are improved, the dielectric constant and the dielectric tangent are reduced, and a new peak is observed in the vicinity of 1700 cm ^-2 in the infrared absorption spectrum, as in the case of the reaction between the carboxylic anhydride group and the amino group (the above-mentioned first and second steps), and therefore it is considered that an imide group is formed.

Examples of methods for introducing an acid anhydride group into the styrene-based elastomer (P1) include a method of polymerizing a monomer having an acid anhydride group as one of the raw materials for producing the styrene-based elastomer (P1) with other raw materials, a method of introducing an acid anhydride group into a side chain after polymer synthesis, and a method of grafting reaction. For example, a method of copolymerizing an appropriate amount of an ethylenically unsaturated carboxylic acid anhydride such as maleic anhydride, and a method of synthesizing the styrene-based elastomer (P1) and then grafting using an appropriate amount of an ethylenically unsaturated carboxylic acid anhydride such as maleic anhydride and a peroxide can be mentioned. Also, instead of an acid anhydride, an appropriate amount of an ethylenically unsaturated carboxylic acid such as maleic acid can be used. In this case, at least a portion of the carboxylic acid is made to be an anhydride group after the introduction of the carboxylic acid.

The styrene-based elastomer (P1) preferably contains 5 to 60% by mass of polystyrene blocks, more preferably 10 to 50% by mass, and even more preferably 20 to 40% by mass, per 100% by mass excluding the anhydride of the ethylenically unsaturated carboxylic acid. When the polystyrene block is 5% by mass or more, a cured product with excellent viscoelasticity is obtained, and when the polystyrene block is 60% by mass or less, the solubility in solvents is improved, and the solution stability of the thermosetting resin composition is excellent.

The acid anhydride group value of the styrene-based elastomer (P1) is preferably 0.1 to 40 mg CH ₃ ONa/g, more preferably 1 to 30 mg _{CH 3} ONa/g, and even more preferably 5 to 20 mg _{CH 3} ONa/g. By using a styrene-based elastomer (P1) having an acid anhydride group value of 0.1 mg _{CH 3} ONa/g or more, the adhesiveness can be improved, and the heat resistance and insulating properties can be improved. By using a styrene-based elastomer (P1) having an acid anhydride group value of 40 mg CH ₃ ONa/g or less, a low dielectric constant necessary for printed wiring boards and the like through which high-frequency electric signals propagate can be achieved.

In addition, styrene-based elastomers (P1) in which some of the acid anhydride groups have been ring-opened with water, alcohol, amine, etc. to become carboxylic acids can also be used as styrene-based elastomers (P1). By ring-opening some of the acid anhydride groups to become carboxylic acids, it is expected that the adhesive strength to conductive circuits described below will be improved. However, if one in which all of the acid anhydride groups have been ring-opened to become carboxylic acids is used, amide groups rather than imide groups will be generated by the reaction with the polyisocyanate component (C1) described below, resulting in a large dielectric tangent.

The molar ratio of the acid anhydride to the ring-opened carboxylic acid is preferably acid anhydride: carboxylic acid = 100-50: 0-50, more preferably 100-75: 0-25, and further preferably 100-85: 0-15.
The ratio of the acid anhydride group to the ring-opened carboxylic acid can be determined by the following method. That is, the amount (mg) of sodium methoxide required to neutralize 1 g of styrene-based elastomer (P1) is determined, and this is taken as the total acid value. The total acid value is divided by the molecular weight of sodium methoxide to determine the amount of carboxylic acid contained in 1 g of styrene-based elastomer (P1): X (mmol). The total acid value includes both the carboxylic acid whose acid anhydride group contained in 1 g of styrene-based elastomer (P1) has been ring-opened at the time of measuring the acid value, and the carboxylic acid that has already been ring-opened at the time of measuring the acid value.
Separately, the amount (mmol) of perchloric acid required to neutralize 1 g of styrene-based elastomer (P1) is calculated, and this is converted into the amount (mg) of sodium methoxide to obtain the acid anhydride value. The amount Y (mmol) of acid anhydride groups contained in 1 g of styrene-based elastomer (P1) can be calculated by dividing the acid anhydride value by the molecular weight of sodium methoxide.
When 1 mole of an acid anhydride group is ring-opened, 2 moles of carboxylic acid are generated. If the amount of carboxylic acid that is contained in 1 g of the styrene-based elastomer (P1) and has already been ring-opened at the time of measuring the acid value is Z (mmol), then:
Z = X-2Y.
In other words, the ratio of acid anhydride and ring-opened carboxylic acid contained in the styrene-based elastomer (P1) is
Y:Z=Y:(X-2Y).
The molecular weight of sodium methoxide, which is the standard for the total acid value, and the molecular weight of potassium hydroxide, which is the standard for the acid anhydride group value, are close in value. Therefore, if the total acid value is X', the acid anhydride group value is Y', and the acid value derived from the carboxylic acid that has already been ring-opened at the time of measuring the acid value is Z', then, simply,
Z'=X'-2Y';
The ratio of acid anhydride and ring-opened carboxylic acid contained in the styrene-based elastomer (P1) is as follows:
Y':Z'=Y':(X'-2Y').

The styrene-based elastomer (P1) preferably has a mass average molecular weight of about 5,000 to 1,000,000, more preferably 10,000 to 500,000, more preferably 25,000 to 200,000, and even more preferably 25,000 to 100,000.

Commercially available styrene-based elastomers (P1) include, for example, the Tuftec M series manufactured by Asahi Kasei Corporation and the Kraton FG series manufactured by Kraton Polymer Japan. These may be used alone or in combination of two or more types.

<Polyisocyanate Component (C1)>
By reacting the polyisocyanate component (C1) with the above-mentioned styrene-based elastomer (P1), a cured product having excellent heat resistance and insulating properties, and low dielectric constant and dielectric loss tangent can be obtained. The polyisocyanate component (C1) is preferably an isocyanate group-containing compound having two or more isocyanates. Furthermore, it can also impart adhesiveness. The isocyanate group-containing compound is not particularly limited as long as it has two or more isocyanate groups in the molecule.

Specific examples of the isocyanate group-containing compound having two isocyanate groups in one molecule include aromatic diisocyanates such as 1,3-phenylene diisocyanate, 4,4'-diphenyl diisocyanate, 1,4-phenylene diisocyanate, 4,4'-diphenylmethane diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 4,4'-toluidine diisocyanate, dianisidine diisocyanate, and 4,4'-diphenyl ether diisocyanate;
Aliphatic diisocyanates such as trimethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, pentamethylene diisocyanate, 1,2-propylene diisocyanate, 2,3-butylene diisocyanate, 1,3-butylene diisocyanate, dodecamethylene diisocyanate, and 2,4,4-trimethylhexamethylene diisocyanate;
Aromatic aliphatic diisocyanates such as ω,ω'-diisocyanate-1,3-dimethylbenzene, ω,ω'-diisocyanate-1,4-dimethylbenzene, ω,ω'-diisocyanate-1,4-diethylbenzene, 1,4-tetramethylxylylene diisocyanate, and 1,3-tetramethylxylylene diisocyanate;
Alicyclic diisocyanates such as 3-isocyanatemethyl-3,5,5-trimethylcyclohexyl isocyanate [also known as isophorone diisocyanate], 1,3-cyclopentane diisocyanate, 1,3-cyclohexane diisocyanate, 1,4-cyclohexane diisocyanate, methyl-2,4-cyclohexane diisocyanate, methyl-2,6-cyclohexane diisocyanate, 4,4'-methylenebis(cyclohexyl isocyanate), 1,3-bis(isocyanatemethyl)cyclohexane, and 1,4-bis(isocyanatemethyl)cyclohexane are included.

Specific examples of isocyanate group-containing compounds having three isocyanate groups per molecule include aromatic polyisocyanates such as 2,4,6-triisocyanate toluene and 1,3,5-triisocyanate benzene, aliphatic polyisocyanates such as lysine triisocyanate, aromatic aliphatic polyisocyanates such as 4,4',4"-triphenylmethane triisocyanate, and alicyclic polyisocyanates, as well as the trimethylolpropane adduct of the diisocyanate described above, biuret products reacted with water, and trimers having an isocyanurate ring.

A blocked isocyanate in which at least a portion of the isocyanate groups of the polyisocyanate component (C1) are blocked with a blocking agent may be used. Specific examples include polyisocyanate components (C1) in which the isocyanate groups are blocked with ε-caprolactam, MEK (methyl ethyl ketone) oxime, cyclohexanone oxime, pyrazole, phenol, etc. In particular, the use of hexamethylene diisocyanate trimer having an isocyanurate ring and blocked with MEK oxime or pyrazole is highly preferred because it enhances the adhesive strength to polyimide and copper and has excellent heat resistance.

The content of isocyanate groups in the polyisocyanate component (C1) relative to 1 mol of acid anhydride groups in the styrene-based elastomer (P1) is preferably in the range of 0.1 to 20 mol, more preferably in the range of 0.5 to 10 mol, and even more preferably in the range of 1 to 3 mol. By making the content of isocyanate groups 0.1 mol or more relative to the acid anhydride groups in the styrene-based elastomer (P1), the crosslink density can be increased and the heat resistance, insulating properties, and adhesive properties can be improved. By making the content of isocyanate groups 20 mol or less, the generation of new polar groups can be suppressed and the deterioration of the dielectric tangent can be suppressed.

<Silane coupling agents, thiol compounds>
Composition (I)-1 can contain a silane coupling agent and/or a thiol compound to the extent that the physical properties are not impaired. By reacting the silane coupling agent and/or the thiol compound with, for example, a styrene-based elastomer (P1), a cured product excellent in heat resistance and insulation and low in dielectric constant and dielectric loss tangent can be obtained. Furthermore, adhesiveness can also be imparted. In addition, by using a silane coupling agent and a thiol compound, adhesiveness to conductive patterns, conductive layers, and resin films, typified by copper, can be improved. In addition, the solder heat resistance after humidification, the flexibility of the cured product of the prepreg, and the electrical insulation can also be improved without deteriorating the dielectric constant and dielectric loss tangent.

Examples of silane coupling agents include silane coupling agents having N, S or O and/or their hydrolysis condensates. For example, vinyl methoxysilane, vinyl ethoxysilane, 2-(3,4-epoxycyclohexyl)ethyl trimethoxysilane, 3-glycidoxypropyl methyl dimethoxysilane, 3-glycidoxypropyl trimethoxysilane, 3-glycidoxypropyl methyl diethoxysilane, 3-glycidoxypropyl triethoxysilane, p-styryl trimethoxysilane, 3-methacryloxypropyl methyl dimethoxysilane, 3-methacryloxypropyl triethoxysilane, 3-acryloxypropyl trimethoxysilane, N-2-(aminoethyl)-3-aminopropyl methyl dimethoxysilane, N-2-(aminoethyl)-3-aminopropyl trimethoxysilane, 3-aminopropyl trimethoxysilane, 3-aminopropyl triethoxysilane, 3-triethoxysilyl-N-(1,3-dimethyl-butylidene )propylamine, N-phenyl-3-aminopropyltrimethoxysilane, N-(vinylbenzyl)-2-aminoethyl-3-aminopropyltrimethoxysilane hydrochloride, tris-(trimethoxysilylpropyl)isocyanurate, 3-ureidopropyltrialkoxysilane, 3-isocyanatopropyltriethoxysilane, 3-phenylaminopropyltrimethoxysilane, 1,2-ethanediamine, N-{3-(trimethoxysilyl)propyl}-, N-{(ethenylphenyl)methyl} derivative hydrochloride, vinyltriacetoxysilane, allyltrimethoxysilane, as well as silane coupling agents whose functional groups are protected with alkoxy groups, sulfide/polysulfide silane coupling agents, polymer-type alkoxy oligomer type and multifunctional group type silane coupling agents can be used.

The thiol compound contains, for example, at least a thiol group and a linear or branched chain hydrocarbon group or a cyclic hydrocarbon group. It may contain two or more thiol groups. The hydrocarbon group may be saturated or unsaturated. Some of the hydrogen atoms of the hydrocarbon group may be substituted with hydroxyl groups, amino groups, carboxyl groups, halogen atoms, alkoxysilyl groups, etc. Examples of colorless thiols include 1-propanethiol, 3-mercaptopropionic acid, (3-mercaptopropyl)trimethoxysilane, 1-butanethiol, 2-butanethiol, isobutyl mercaptan, isoamyl mercaptan, cyclopentanethiol, 1-hexanethiol, cyclohexanethiol, 6-hydroxy-1-hexanethiol, 6-amino-1-hexanethiol hydrochloride, 1-heptanethiol, 7-carboxy-1-heptanethiol, 7-amido-1-heptanethiol, 1-octanethiol, tert-octanethiol, 8-hydroxy-1-octanethiol, 8-amino-1-octanethiol hydrochloride, 1H,1H,2H,2H-perfluorooctanethiol, 1-nonanethiol, 1-decanethiol, 10-carboxy-1-octanethiol ... 1-decanethiol, 10-amido-1-decanethiol, 1-naphthalenethiol, 2-naphthalenethiol, 1-undecanethiol, 11-amino-1-undecanethiol hydrochloride, 11-hydroxy-1-undecanethiol, 1-dodecanethiol, 1-tetradecanethiol, 1-hexadecanethiol, 16-hydroxy-1-hexadecanethiol, 16-amino-1-hexadecanethiol hydrochloride, 1-octadecanethiol, 1,4-butanedithiol, 2,3-butanedithiol, 1,6-hexaneedithiol, 1,2-benzeneedithiol, 1,9-nonanedithiol, 1,10-decanedithiol, 1,3,5-benzenetrithiol, 3-mercaptopropylmethyldimethoxysilane, and 3-mercaptopropyltrimethoxysilane. Thiols can be used alone or in combination with two or more types.

The amount of the silane coupling agent and/or the thiol compound contained in the composition (I)-1 is not particularly limited, but is preferably 0.01 to 50 parts by mass in total, more preferably 0.1 to 25 parts by mass, and even more preferably 1 to 15 parts by mass, per 100 parts by mass of the solid content of the styrene-based elastomer (P1).
By including a thiol compound or a silane coupling agent (which does not contain sulfur atoms), when the prepreg is cured, it is possible to improve the dimensional stability and the heat resistance of the cured product after being humidified, as well as to achieve a better balance of the often contradictory properties of adhesion and low dielectric constant, and flexibility and electrical insulation.

<Filler>
A filler may be further added to the composition (I)-1 for the purpose of imparting flame retardancy, controlling the fluidity of the resin composition, improving the elastic modulus of the cured product, etc. The filler is not particularly limited, but examples of the shape include spherical, powdery, fibrous, needle-like, and scaly shapes.

Examples of the filler include polytetrafluoroethylene powder, polyethylene powder, polyacrylic acid ester powder, epoxy resin powder, polyamide powder, polyurethane powder, polysiloxane powder, etc., as well as polymer fillers such as a multi-layered core-shell filler using silicone, acrylic, styrene-butadiene rubber, butadiene rubber, etc.;
(Poly)phosphate compounds such as melamine phosphate, melamine polyphosphate, guanidine phosphate, guanidine polyphosphate, ammonium phosphate, ammonium polyphosphate, ammonium amido phosphate, ammonium amido polyphosphate, carbamate phosphate, and carbamate polyphosphate; organic phosphate compounds, phosphazene compounds, phosphonic acid compounds, phosphinic acid compounds such as aluminum diethylphosphinate, aluminum methylethylphosphinate, aluminum diphenylphosphinate, aluminum ethylbutylphosphinate, aluminum methylbutylphosphinate, and aluminum polyethylenephosphinate; phosphorus-based flame-retardant fillers such as phosphine oxide compounds, phosphorane compounds, and phosphoramide compounds;
Nitrogen-based flame-retardant fillers such as benzoguanamine, melamine, melam, melem, melon, melamine cyanurate, cyanuric acid compounds, isocyanuric acid compounds, triazole compounds, tetrazole compounds, diazo compounds, and urea;
Examples of inorganic fillers include silica, mica, talc, kaolin, clay, hydrotalcite, wollastonite, xonotlite, silicon nitride, boron nitride, aluminum nitride, calcium hydrogen phosphate, calcium phosphate, glass flakes, hydrated glass, calcium titanate, sepiolite, magnesium sulfate, aluminum hydroxide, magnesium hydroxide, zirconium hydroxide, barium hydroxide, calcium hydroxide, titanium oxide, tin oxide, aluminum oxide, magnesium oxide, zirconium oxide, zinc oxide, molybdenum oxide, antimony oxide, nickel oxide, zinc carbonate, magnesium carbonate, calcium carbonate, barium carbonate, zinc borate, and aluminum borate.

Considering the environmental impact that has been a topic of discussion in recent years, it is desirable to use a non-halogen flame retardant such as a phosphorus-based flame retardant filler or a nitrogen-based flame retardant filler. Among these, examples of fillers that are more effective in terms of flame retardancy when used in combination with composition (I)-1 include phosphazene compounds, phosphine compounds, melamine polyphosphate, ammonium polyphosphate, melamine cyanurate, and hydroxide compounds. In order to further reduce the dielectric constant and dielectric tangent, it is preferable to use polytetrafluoroethylene powder and phosphine compounds, which make it possible to obtain a cured product that is excellent in balance not only in dielectric properties but also in adhesion, flexibility, electrical insulation, and heat resistance. Fillers are used alone or in combination.

The average particle size of the filler is preferably 0.1 to 25 μm. When a filler with an average particle size close to 0.1 μm is used, the filler's modification effect is easily obtained, and furthermore, the dispersibility and stability of the dispersion liquid are easily improved. Furthermore, when a filler with an average particle size close to 25 μm is used, the mechanical properties of the cured product are easily improved.

The total amount of filler added can be within a range that does not impair low warpage. For example, it can be 0.01 to 500 parts by mass per 100 parts by mass of the styrene-based elastomer (P1). The filler can improve the modifying effect and the mechanical properties of the cured product.

The filler can be added by any conventional method without any restrictions. For example, a dispersion liquid containing the filler is prepared, and the dispersion liquid containing the filler is kneaded with a three-roll mill or the like into the reaction liquid before, during, or after the polymerization of the styrene-based elastomer (P1). In order to disperse the filler well and stabilize the dispersion state, a dispersant and/or a thickener may be used within a range that does not affect the properties of the prepreg.

<Other ingredients>
In addition to the essential components and the optional components described above, composition (I)-1 may further contain, within the scope of the purpose, an epoxy group-containing compound, an oxetane group-containing compound, an aziridine group-containing compound, a carbodiimide group-containing compound, a benzoxazine compound, a β-hydroxyalkylamide group-containing compound, etc. Also, it may contain dyes, pigments, antioxidants, polymerization inhibitors, defoamers, leveling agents, ion collectors, moisturizers, viscosity adjusters, preservatives, antibacterial agents, antistatic agents, antiblocking agents, ultraviolet absorbers, infrared absorbers, etc.

Examples of the epoxy group-containing compound include epoxy resins such as glycidyl ether type epoxy resins, glycidyl amine type epoxy resins, glycidyl ester type epoxy resins, and cyclic aliphatic (alicyclic) epoxy resins. Examples of the glycidyl ether type epoxy resins include cresol novolac type epoxy resins, phenol novolac type epoxy resins, α-naphthol novolac type epoxy resins, bisphenol A type novolac type epoxy resins, tetrabromobisphenol A type epoxy resins, brominated phenol novolac type epoxy resins, tris(glycidyloxyphenyl)methane, and tetrakis(glycidyloxyphenyl)ethane.
Examples of the glycidylamine type epoxy resin include tetraglycidyldiaminodiphenylmethane, triglycidyl paraaminophenol, triglycidyl meta-aminophenol, and tetraglycidyl meta-xylylenediamine.

Although examples of oxetane group-containing compounds, aziridine compounds, carbodiimide group-containing compounds, benzoxazine compounds, and β-hydroxyalkylamide group-containing compounds are omitted, known compounds can be appropriately selected and used.

[[Composition (II)]]
Composition (II) is a thermosetting resin composition containing a polyamide resin (P2) (hereinafter also referred to as "polyamide resin (P2)") having a phenolic hydroxyl group in a side group, and a tri- or higher functional compound (C2) (hereinafter also referred to as "compound (C2)") capable of reacting with the above-mentioned phenolic hydroxyl group.

<Polyamide resin (P2)>
The polyamide resin (P2) is usually synthesized using a polybasic acid compound selected from divalent or higher polybasic acids and/or acid anhydrides and/or lower alkyl esters thereof as monomers, and a divalent or higher polyamine compound. The phenolic hydroxyl groups in the polyamide resin (P2) can form a crosslinked structure by thermal curing with a trifunctional or higher compound (C2).
Suitable examples of the polyamide resin (P2) include the following (i) and/or (ii). That is, the polyamide resin (P2) of (i) is a polyamide (A-1) in which a phenolic hydroxyl group and a hydrocarbon group having 20 to 60 carbon atoms (but not including an aromatic ring to which the phenolic hydroxyl group is bonded) are contained in the same polymer. The polyamide resin (P2) of (ii) is a polyamide (A-3) in which a polyamide (a-1) containing a phenolic hydroxyl group in a side group and a polyamide (a-2) containing a hydrocarbon group having 20 to 60 carbon atoms (but not including an aromatic ring to which the phenolic hydroxyl group is bonded) are mixed.

In terms of solubility in general-purpose solvents and productivity, the former polyamide (A-1) is preferred. In the following description, the parentheses for the hydrocarbon group having 20 to 60 carbon atoms (excluding the aromatic ring to which the phenolic hydroxyl group is bonded) will be omitted, but when the term "hydrocarbon group having 20 to 60 carbon atoms" is used, it is assumed that the condition in the parentheses is satisfied. The term "hydrocarbon group having 20 to 60 carbon atoms" will also be expressed as "C20-60 hydrocarbon group." The term "hydrocarbon group having 20 to 60 carbon atoms" refers to a hydrocarbon group having 20 to 60 carbon atoms contained in all or part of the residues other than the functional groups that contribute to the polymerization of the monomer, and the number of carbon atoms in a continuous structure that does not contain elements other than carbon and hydrogen is counted. More preferably, all of the residues other than the functional groups that contribute to the polymerization of the monomer are hydrocarbon groups having 20 to 60 carbon atoms. In other words, it refers to the total number of carbon atoms in the continuous hydrocarbon groups, including the main chain and the side groups or side chains directly connected to the main chain, in the resulting polyamide (A-1), and includes aliphatic (including alicyclic) and aromatic rings. However, it does not include aromatic rings to which phenolic hydroxyl groups are bonded. In addition, each hydrocarbon group bonded via an aromatic ring to which a phenolic hydroxyl group is bonded is counted as a separate hydrocarbon group.

Further, preferred examples of the polyamide resin (P2) of (i) include polyamide resins satisfying the following (iii) and (vi), and preferred examples of the polyamide resin (P2) of (ii) include polyamide resins satisfying (iv) to (vi).
(iii) Monomers constituting polyamide (A-1) include a monomer having a phenolic hydroxyl group and a monomer having a hydrocarbon group having 20 to 60 carbon atoms. It goes without saying that a monomer having a phenolic hydroxyl group and a hydrocarbon group having 20 to 60 carbon atoms may be used within the same type of monomer.
(iv) The polybasic acid monomer and/or polyamine monomer constituting the polyamide (a-1) contains a monomer having a phenolic hydroxyl group, and the polybasic acid monomer and the polyamine monomer do not contain a monomer having a hydrocarbon group having 20 to 60 carbon atoms.
(v) The polybasic acid monomer and/or polyamine monomer constituting the polyamide (a-2) contains a monomer having a hydrocarbon group having 20 to 60 carbon atoms, and the polybasic acid monomer and the polyamine monomer do not contain a monomer having a phenolic hydroxyl group.
(vi) The monomer having a hydrocarbon group having 20 to 60 carbon atoms includes a compound having a cyclic structure having 5 to 10 carbon atoms. Note that "including a compound having a cyclic structure having 5 to 10 carbon atoms" means that at least a part of the monomer having a hydrocarbon group having 20 to 60 carbon atoms includes a monomer having a cyclic structure having 5 to 10 carbon atoms.

Of the monomers having a hydrocarbon group with 20 to 60 carbon atoms, from the viewpoint of effectively bringing out solubility and flexibility, monomers having a hydrocarbon group with 24 to 56 carbon atoms are more preferable, monomers having a hydrocarbon group with 28 to 48 carbon atoms are even more preferable, and monomers having a hydrocarbon group with 36 to 44 carbon atoms are even more preferable.

By using polyamide resin (P2) in prepregs, it is possible to provide metal-clad laminates, printed wiring boards, and multilayer wiring boards that are excellent in moisture and heat resistance and flexibility without impairing heat resistance or chemical resistance. In addition, there is also the advantage that it is possible to provide a thermosetting resin composition that can be used in a wide range of general-purpose organic solvents. In addition, by using prepregs using polyamide resin (P2) of (i) or/and (ii), it is possible to significantly improve the dimensional stability during heat pressing, adhesion to metals such as copper and polyimide substrates, heat resistance during solder reflow, flexibility when folding a laminate (metal-clad laminate, printed wiring board, etc.) containing a cured product of the prepreg, electrical insulation to prevent leak touch in narrow-pitch wiring circuits, and the dielectric constant and dielectric loss tangent, which are important for prepregs of high-frequency circuits such as printed wiring boards through which high-frequency electrical signals propagate.

By using a monomer having a phenolic hydroxyl group as a monomer constituting the polyamide resin (P2) and introducing a functional group (phenolic hydroxyl group) that serves as a crosslinking point into the side group of the main chain skeleton, the crosslinking density due to thermal curing can be increased, and dimensional stability during hot pressing and heat resistance during solder reflow can be imparted. As for the phenolic hydroxyl group of the side group, a polybasic acid compound (polybasic acid monomer) having a phenolic hydroxyl group and/or a polyamine compound (polyamine monomer) having a phenolic hydroxyl group can be used as the raw material of the polyamide resin (P2) as described later.
In addition, by introducing a C20-60 hydrocarbon group into the polyamide resin (P2), the concentration of amide bonds with high water absorption can be relatively lowered, improving insulation reliability and dielectric properties. Furthermore, due to the flexibility inherent to the C20-60 hydrocarbon group, and by introducing a phenolic hydroxyl group into the monomer constituting the polyamide resin (P2), flexibility can be improved. Therefore, it can be suitably used as a prepreg for printed wiring boards and the like that require foldability.

By including a compound having a cyclic structure with 5 to 10 carbon atoms as a monomer having a C20-60 hydrocarbon group in the polyamide resin (P2), the molecular arrangement can be hindered and the crystallinity can be reduced. As a result, the solubility can be improved. In addition, since the compound having a cyclic structure with 5 to 10 carbon atoms has a structure containing a hydrocarbon group such as a chain-like alkyl group with high freedom and hydrophobicity in the part other than the cyclic structure, it is possible to more effectively increase the solubility and effectively reduce the dielectric constant and dielectric loss tangent. The C20-60 hydrocarbon group can be introduced by using a polybasic acid compound having a C20-60 hydrocarbon group and/or a polyamine compound having a C20-60 hydrocarbon group as the raw material of the polyamide resin (P2) as described later.

Polyamide resin (P2) has two structures, a phenolic hydroxyl group and a C20-60 hydrocarbon group, and can be dissolved in general-purpose organic solvents. It can improve dimensional stability during heat pressing, reduce the dielectric constant and dielectric tangent, and resolve the trade-off between adhesiveness and heat resistance, and flexibility and electrical insulation. The preferred forms of polyamides (A-1) and (A-3) are described in detail below.

<Polyamide (A-1)>
The polyamide (A-1) is obtained by polymerizing a polybasic acid monomer (m ₁ ) and a polyamine monomer (m ₂ ), has a phenolic hydroxyl group on a side group, and has a phenolic hydroxyl group and a C20-60 hydrocarbon group in the same polymer. That is, the polybasic acid monomer (m ₁ ) is selected from at least one selected from the group consisting of polybasic acid compounds having a phenolic hydroxyl group, polybasic acid compounds containing a C20-60 hydrocarbon group, and other polybasic acid compounds, and the polyamine monomer (m ₂ ) is selected from at least one selected from the group consisting of polyamine compounds having a phenolic hydroxyl group, polyamine compounds containing a C20-60 hydrocarbon group, and other polyamine compounds, so that the polymer contains a phenolic hydroxyl group and a C20-60 hydrocarbon group.
The polyamide (A-1) can be obtained by polymerizing a polybasic acid monomer (m ₁ ) and a polyamine monomer (m ₂ ) selected so that the compound containing a C20-60 hydrocarbon group and the compound having a phenolic hydroxyl group are contained in the same type of monomer or in a different monomer.

Here, "so as to be contained within the same type of monomer" means that a polybasic acid compound having a phenolic hydroxyl group and a polybasic acid compound containing a C20-60 hydrocarbon group may be used as the polybasic acid monomer (m ₁ ), and a polyamine compound having a phenolic hydroxyl group and a polyamine compound containing a C20-60 hydrocarbon group may be used as the polyamine monomer (m ₂ ).
Furthermore, "to be included in another monomer" means that the polybasic acid monomer (m ₁ ) may include a polybasic acid compound having a phenolic hydroxyl group, and the polyamine monomer (m ₂ ) may include a polyamine compound having a C20-60 hydrocarbon group, or the polybasic acid monomer (m ₁ ) may include a polybasic acid compound having a C20-60 hydrocarbon group, and the polyamine monomer (m ₂ ) may include a polyamine compound having a phenolic hydroxyl group.
In either case, other polybasic acid compounds and other polyamine compounds can be used as appropriate.

The phenolic hydroxyl group introduced into the side group functions as a crosslinking point for the main chain generated by polymerization of the polybasic acid monomer (m ₁ ) and the polyamine monomer (m ₂ ). That is, a dense crosslinked structure can be formed by thermally curing the polyamide (A-1) and the trifunctional or higher compound (C2) which can react with the phenolic hydroxyl group described below. As a result, the dimensional stability is excellent even during crosslinking during hot pressing, and the heat resistance during soldering after thermal curing is also improved.

The C20-60 hydrocarbon group also reduces the concentration of highly hygroscopic amide bonds, and also provides and improves flexibility and bendability. This reduces the hygroscopicity of the cured product after thermal curing, improving its resistance to moist heat and low dielectric constant and dielectric loss tangent, which are important factors in printed wiring boards that transmit high-frequency electrical signals.

The polybasic acid compound as the polybasic acid monomer (m ₁ ) and the polyamine compound as the polyamine monomer (m ₂ ) may be divalent or higher monomers, and trivalent or higher monomers may be used as appropriate. A divalent monomer and a trivalent or higher monomer may be combined to introduce a branched structure and adjust the molecular weight appropriately. It is also possible to use a monovalent monomer to keep the molecular weight appropriate. By partially including a trivalent or higher monomer, the effect of increasing the cohesive force can be obtained. The trivalent or higher monomer is preferably 0.1 to 20 mol % of the total monomers, and more preferably 1 to 10 mol % or less.

一般式（１）中、Ｒ_１は、構造単位毎に独立の構造を有していてもよい多塩基酸化合物残基である２価の連結基であり、Ｒ_２は、構造単位毎に独立の構造を有していてもよいポリアミン化合物残基である２価の連結基であり、Ｒ_１およびＲ_２の少なくとも一方は、フェノール性水酸基を有する連結基を含み、且つＲ_１およびＲ_２の少なくとも一方は、Ｃ２０～６０炭化水素基を有する連結基を含む。
ポリアミド（Ａ－１）は、－ＣＯ－Ｒ_１－ＣＯ－ＮＨ－Ｒ_２－ＮＨ－で示される構造単位が少なくとも２以上繰り返されたものである。なお、本実施形態の趣旨を逸脱しない範囲において、一般式（１）の構造単位を１つ有し、且つ末端が封止された化合物が熱硬化性樹脂組成物に含まれてもよい。 When the polyamide resin (P2) is obtained using a dibasic acid monomer and a diamine monomer, it has a structural unit of the following general formula (1).

In general formula (1), R ₁ is a divalent linking group which is a polybasic acid compound residue which may have an independent structure for each structural unit, R ₂ is a divalent linking group which is a polyamine compound residue which may have an independent structure for each structural unit, at least one of R ₁ and R ₂ contains a linking group having a phenolic hydroxyl group, and at least one of R ₁ and R ₂ contains a linking group having a C20-60 hydrocarbon group.
Polyamide (A-1) is a compound in which at least two structural units represented by -CO-R ₁ -CO-NH-R ₂ -NH- are repeated. Note that, within the scope of the present embodiment, a compound having one structural unit of general formula (1) and having a blocked end may be contained in the thermosetting resin composition.

The phenolic hydroxyl group-containing monomer and the C20-60 hydrocarbon group-containing monomer may be contained in at least one of the dibasic acid compound and the diamine compound, and these groups may be contained in both the dibasic acid compound and the diamine compound. For example, when two dibasic acid compounds R _1-1 and R _1-2 and two diamine compounds R _2-1 and R _2-2 are used, structural units of -CO-R 1-1 -CO-NH-R _2-1 -NH-, -CO-R _1-1 -CO-NH-R _2-2 -NH-, -CO-R _1-2 -CO-NH-R _2-1 -NH-, _{and -CO-R 1-2 -CO-NH-R 2-2 -NH- may} be contained.

<Polybasic Acid Monomer (m ₁ )>
[Polybasic acid compound having a phenolic hydroxyl group]
The polybasic acid compound having a phenolic hydroxyl group is not particularly limited, and examples thereof include hydroxyisophthalic acids such as 2-hydroxyisophthalic acid, 4-hydroxyisophthalic acid, and 5-hydroxyisophthalic acid;
Dihydroxyisophthalic acids such as 2,5-dihydroxyisophthalic acid, 2,4-dihydroxyisophthalic acid, and 4,6-dihydroxyisophthalic acid;
2-hydroxyterephthalic acid,
Dihydroxyterephthalic acids such as 2,3-dihydroxyterephthalic acid and 2,6-dihydroxyterephthalic acid;
Hydroxyphthalic acids such as 4-hydroxyphthalic acid and 3-hydroxyphthalic acid;
Examples of the dihydroxyphthalic acids include 3,4-dihydroxyphthalic acid, 3,5-dihydroxyphthalic acid, 4,5-dihydroxyphthalic acid, and 3,6-dihydroxyphthalic acid.
Further examples include acid anhydrides and ester derivatives such as polybasic acid methyl esters. The only difference is that the reaction is a dehydration reaction in the case of free polybasic acids and acid anhydrides, whereas the reaction is a corresponding dealcoholization reaction in the case of ester derivatives.
Among these, 5-hydroxyisophthalic acid is preferred from the standpoints of copolymerizability, availability, and the like.
When 5-hydroxyisophthalic acid is used, R ₁ in general formula (1), ie, the divalent linking group which is a polybasic acid compound residue, is the moiety obtained by removing two carboxyl groups from the 5-hydroxyisophthalic acid.

[Polybasic acid compounds containing C20-60 hydrocarbon groups]
A suitable example of a polybasic acid compound containing a C20-60 hydrocarbon group is a polybasic acid compound having a cyclic structure containing 5 to 10 carbon atoms, which is obtained by reacting a monobasic unsaturated fatty acid having one or more double or triple bonds and having 10 to 24 carbon atoms. One example of the reaction is the Diels-Alder reaction. For example, a polybasic acid compound containing a dimerized fatty acid (dimer acid) obtained by subjecting natural fatty acids such as soybean oil fatty acid, tall oil fatty acid, rapeseed oil fatty acid, etc., and oleic acid, linoleic acid, linolenic acid, erucic acid, etc., which are refined from these fatty acids, to the Diels-Alder reaction is preferably used.
The number of cyclic structures may be one or two, and in the case of two, the two rings may be independent or continuous. Examples of the cyclic structure include a saturated alicyclic structure, an unsaturated alicyclic structure, and an aromatic ring. The carboxyl group can be directly bonded to the cyclic structure, but from the viewpoint of improving solubility and flexibility, the carboxyl group is preferably bonded to the cyclic structure via an aliphatic chain. The number of carbon atoms between the carboxyl group and the cyclic structure is preferably 2 to 25.
In addition, from the viewpoints of improving solubility, improving flexibility, and decreasing the dielectric constant and dielectric tangent, it is preferable that the polybasic acid compound containing a C20-60 hydrocarbon group has a chain-like alkyl group with high freedom and hydrophobicity as a portion other than the cyclic structure. It is preferable that there are two or more alkyl groups per cyclic structure. The number of carbon atoms in the alkyl group is preferably 2 to 25.

Polybasic acid compounds containing C20-60 hydrocarbon groups are generally obtained as a composition of monomers containing a dimer derived from dimer acid (dimerized fatty acid) as a residue, and also containing fatty acid of trimerization or higher as a raw material. In particular, it is preferable that the content of monomers containing a dimer derived from dimer acid (dimerized fatty acid) as a residue in 100% by mass of monomers containing C20-60 hydrocarbon groups is 70% by mass or more, preferably 95% by mass or more. In addition, dimers whose degree of unsaturation has been reduced by hydrogenation (hydrogenation reaction) are particularly preferably used from the viewpoints of oxidation resistance (particularly coloring at high temperatures) and gelation suppression during synthesis. As polybasic acid compounds having C20-60 hydrocarbon groups, it is preferable to use monomers (polybasic acid compounds) containing a dimer derived from monobasic unsaturated fatty acid having 10 to 24 carbon atoms as a residue.
Furthermore, it is preferable to use a monomer containing a trimer, which is a tricarboxylic acid, as a residue derived from a monobasic unsaturated fatty acid having 10 to 24 carbon atoms as a part of the polybasic acid compound having a C20 to C60 hydrocarbon group.

The polybasic acid compound having a C20-60 hydrocarbon group can be obtained by a known reaction, but a commercially available product can also be used. Examples of commercially available products include "Pripol 1004", "Pripol 1006", "Pripol 1009", "Pripol 1013", "Pripol 1015", "Pripol 1017", "Pripol 1022", "Pripol 1025", and "Pripol 1040" manufactured by Croda Japan Co., Ltd., and "Empol 1008", "Empol 1012", "Empol 1016", "Empol 1026", "Empol 1028", "Empol 1043", "Empol 1061", and "Empol 1062" manufactured by BASF Japan Co., Ltd. These polybasic acid compounds can be used alone or in combination. Among them, "Pripol 1009" having 36 carbon atoms can be preferably used because it can obtain a polyamide having excellent heat resistance, moist heat resistance, and dielectric constant while maintaining adhesiveness. Pripol 1004 has a structure with 44 carbon atoms, and can be used preferably from the viewpoint of obtaining polyamide with excellent dielectric constant and flexibility. Furthermore, the use of "Pripol 1040," which contains about 75% by mass of a tricarboxylic acid component, which is a trimer, can improve the cohesive strength of polyamide, and can be used preferably from the viewpoint of improving dimensional stability and heat resistance during heat pressing.
The cohesive strength can also be improved by using a trifunctional or higher monomer, which will be exemplified as one of the "other polybasic acid compounds" described later, as the trifunctional polybasic acid compound. However, the trifunctional or higher monomer described later has a relatively low molecular weight, whereas the tricarboxylic acid component, which is a trimer, has a relatively large molecular weight, and is therefore more preferable in that the concentration of amide bonds can be efficiently reduced and the dielectric constant and dielectric loss tangent can be reduced.

[Other polybasic acid compounds]
The polybasic acid compounds other than the polybasic acid compound having a phenolic hydroxyl group and the polybasic acid compound having a C20 to C60 hydrocarbon group are not particularly limited within the scope of the present embodiment, and examples thereof include dibasic acid compounds and polybasic acid compounds having three or more functionalities.
Dibasic acid compounds include:
Aromatic dibasic acids such as phthalic acid, isophthalic acid, terephthalic acid, 1,4-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, benzophenone-4,4'-dicarboxylic acid, and 4,4'-biphenyldicarboxylic acid;
Aliphatic dibasic acids such as oxalic acid, malonic acid, methylmalonic acid, succinic acid, glutaric acid, adipic acid, maleic acid, fumaric acid, malic acid, tartaric acid, thiomalic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, dodecanedioic acid, hexadecanedioic acid, and diglycolic acid;
Examples of the dibasic acid include alicyclic dibasic acids such as 1,3-cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, and 1,3-cyclopentanedicarboxylic acid.
Examples of the trifunctional or higher polybasic acid compound include trimellitic acid, hydrogenated trimellitic acid, pyromellitic acid, hydrogenated pyromellitic acid, and 1,4,5,8-naphthalenetetracarboxylic acid.

These polybasic acid compounds may be used alone or in combination with the polybasic acid compound having a phenolic hydroxyl group or the polybasic acid compound having a C20-60 hydrocarbon group. Among them, isophthalic acid and 1,4-cyclohexanedicarboxylic acid are preferably used because they can give a tough polyamide having better heat resistance while retaining flexibility.
In addition, by using a trifunctional or higher functional group, a branched structure can be introduced into the polyamide, which can increase the molecular weight and the cohesive strength of the resulting polyamide. As a result, the dimensional stability and heat resistance in particular can be improved without adversely affecting the adhesiveness, flexibility, and electrical insulation properties.

Furthermore, a monofunctional basic compound can be used in combination with a polybasic acid compound. By using a monofunctional compound, the number of carboxyl groups and amino groups that can become terminal functional groups of the polyamide can be reduced, and the molecular weight of the resulting polyamide can be controlled. As a result, the stability over time of the polyamide resin can be improved.
Examples of the monobasic acid compound include benzoic acid, 4-hydroxybenzoic acid, and 2-ethylhexanoic acid.

<Polyamine monomer (m ₂ )>
The polyamine compound having a phenolic hydroxyl group is not particularly limited, but examples thereof include polyamines represented by the following general formula (2).

In the formula, _R3 represents a direct bond or a group consisting of carbon, hydrogen, oxygen, nitrogen, sulfur, or a halogen, and examples thereof include a divalent hydrocarbon group having 1 to 30 carbon atoms, a divalent hydrocarbon group having 1 to 30 carbon atoms in which some or all of the hydrogen atoms have been substituted by halogen atoms, -(C=O)-, _-SO2- , -O-, -S-, -NH-(C=O)-, -(C=O)-O-, a group represented by the following general formula (3), and a group represented by the following general formula (4). In the formula, r and s each independently represent an integer of 1 to 20, and _R4 represents a hydrogen atom or a methyl group.

The above _R3 is preferably a direct bond.

When a compound of general formula (2) is used, R ₂ in general formula (1), i.e., a divalent linking group which is a polyamine compound residue, is the portion obtained by removing two amino groups from the compound of general formula (2).

[Polyamine compound containing C20-60 hydrocarbon group]
Examples of polyamine compounds containing C20-60 hydrocarbon groups include compounds in which the carboxyl groups of the polybasic acid compounds having C20-60 hydrocarbon groups are converted to amino groups. Examples of commercially available products include "Priamine 1071", "Priamine 1073", "Priamine 1074", and "Priamine 1075" manufactured by Croda Japan, and "Versamine 551" manufactured by BASF Japan. These polyamine compounds can be used alone or in combination. Among them, "Priamine 1071" containing about 20 to 25% by mass of a triamine component which is a trimer can improve the cohesive force of polyamide, and can be used preferably from the viewpoint of improving dimensional stability and heat resistance during heat pressing. In addition, the use of a triamine which is a trimer is also preferable from the viewpoint of reducing the dielectric constant and dielectric loss tangent.
From the viewpoint of the production stability of the polyamide, the total amount of the triamine trimer and the tricarboxylic acid trimer is preferably 0.1 to 20 mass%, and more preferably 1 to 10 mass%, of 100 mass% of all monomers used to form the polyamide.

[Other polyamine compounds]
Next, examples of polyamine compounds other than the polyamine compound having a phenolic hydroxyl group and the polyamine compound having a C20 to C60 hydrocarbon group include, but are not particularly limited to, diamine compounds and triamine compounds, provided that they do not deviate from the spirit of the present embodiment.
Examples of the diamine compound include aromatic diamines such as 1,4-diaminobenzene, 1,3-diaminobenzene, 1,2-diaminobenzene, 1,5-diaminonaphthalene, 1,8-diaminonaphthalene, 2,3-diaminonaphthalene, 2,6-diaminotoluene, 2,4-diaminotoluene, 3,4-diaminotoluene, 4,4'-diaminodiphenylmethane, 3,4'-diaminodiphenylether, 4,4'-diaminodiphenylether, 4,4'-diamino-1,2-diphenylethane, 3,3'-diaminodiphenylmethane, 3,4'-diaminodiphenylmethane, 4,4'-diaminobenzophenone, 4,4'-diaminodiphenylsulfone, 3,3'-diaminobenzophenone, and 3,3'-diaminodiphenylsulfone;
Aliphatic polyamines such as ethylenediamine, 1,3-propanediamine, 1,4-butanediamine, 1,6-hexanediamine, 1,7-heptanediamine, 1,9-nonanediamine, 1,12-dodecamethylenediamine, and metaxylenediamine;
Alicyclic diamines such as isophorone diamine, norbornane diamine, 1,2-cyclohexane diamine, 1,3-cyclohexane diamine, 1,4-cyclohexane diamine, 4,4'-diaminodicyclohexylmethane, and piperazine are included.
Examples of trifunctional or higher polyamine compounds include 1,2,4-triaminobenzene and 3,4,4'-triaminodiphenyl ether.
In addition, even if it has an aromatic ring, if the amino group is not directly attached, it is classified as aliphatic, etc.

These polyamine compounds may be used alone or in combination with the polyamines having a phenolic hydroxyl group or the polyamines having a C20-60 hydrocarbon group. Among them, isophorone diamine and norbornane diamine are preferably used because they give a tough polyamide with better heat resistance while retaining flexibility.

In addition, by using a trifunctional or higher functional compound, a branched structure can be introduced into the polyamide, increasing its molecular weight and increasing the cohesive strength of the resulting polyamide. As a result, it is possible to improve dimensional stability and heat resistance in particular without adversely affecting adhesion, flexibility, or electrical insulation.

Furthermore, monofunctional amine compounds can also be used in combination with polyamine compounds. By using monofunctional compounds, it is possible to reduce the number of carboxyl groups and amino groups that can become terminal functional groups of polyamides, and the molecular weight of the resulting polyamide can be controlled. As a result, it is possible to improve the stability over time of polyamide resins in particular. On the other hand, if the number of carboxyl groups and amino groups that can become terminal functional groups is not reduced by monofunctional compounds, phenol groups and carboxyl groups and/or amino groups will be mixed in the resin, and when a trifunctional or higher compound (C2) that can react with phenolic hydroxyl groups is used in combination, the difference in reactivity between the two can be utilized to improve processability and adhesion, which is desirable. Examples of monofunctional amine compounds include aniline, 4-aminophenol, and 2-ethylhexylamine.

The polyamide (A-1) can be obtained by appropriately selecting the polybasic acid monomer (m ₁ ) and the polyamine monomer (m ₂ ) according to the performance to be particularly improved, such as dimensional stability, adhesion, heat resistance, flexibility, electrical insulation, etc.

The polyamide (A-1) obtained by polymerization may be a polymer obtained by randomly polymerizing a component having a phenolic hydroxyl group and a component having a C20 to C60 hydrocarbon group, or may be a block polymer.
That is, a mixture of multiple types of polybasic acid monomer compounds may be polymerized with one type of polyamine compound, a mixture of multiple types of polybasic acid compounds may be polymerized with a mixture of multiple types of polyamine compounds, one type of polybasic acid compound may be polymerized with a mixture of multiple types of polyamine compounds, or one type of polybasic acid compound may be polymerized with one type of polyamine compound and then, depending on the functional groups remaining at the terminals, another polybasic acid compound or another polyamine compound may be further polymerized.

The polyamide (A- ₁ ) preferably contains 10 to 95 mol %, more preferably 14 to 92 mol %, and even more preferably 18 to 88 mol %, of a compound containing a C20-60 hydrocarbon group per 100 mol in total of all monomers used, i.e., the polybasic acid monomer (m 1 ), the polyamine monomer (m ₂ ), and the monobasic acid or monofunctional amine compound used as necessary.

The method for calculating the number of moles of a monomer containing a C20-60 hydrocarbon group will now be described. First, the molecular weight (M) of the monomer containing a C20-60 hydrocarbon group is calculated using the following formula.
M = (56.11 x F x 1000) / E
F: Number of functional groups of monomers containing C20-60 hydrocarbon groups E: Acid value of monomers containing C20-60 hydrocarbon groups (mgKOH/g)
Next, the mass of the compound containing a C20-60 hydrocarbon group subjected to polymerization is divided by the molecular weight (M) to determine the number of moles of the compound containing a C20-60 hydrocarbon group subjected to polymerization.
The number of moles of each monomer used in the polymerization is calculated in the same manner, and these are added together to calculate the number of moles of all monomers used in the polymerization. The proportion (mol %) of the compound containing a C20-60 hydrocarbon group can then be calculated by dividing the number of moles of the compound containing a C20-60 hydrocarbon group by the number of moles of all monomers.

<Polyamide ester (A-2)>
As one type of polyamide resin (P2), there can also be used a polyamide ester (A-2) having a phenolic hydroxyl group as a side group, a C20 to C60 hydrocarbon group, and an ester bond, which is obtained by further reacting a polyol compound with a carboxylic acid terminal of the polyamide (A-1) described above.

[Polyol compound]
The polyol compound, which is a compound necessary for introducing an ester bond, will be described below.
The polyol compound may be any compound having two or more hydroxyl groups, and examples of such polyol compounds include aliphatic or alicyclic diols such as ethylene glycol, propylene glycol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,9-nonanediol, neopentyl glycol, 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol, dimer diol, hydrogenated bisphenol A, and spiroglycol;
Examples of the aromatic diols include 1,4-bis(2-hydroxyethoxy)benzene, 4,4'-methylenediphenol, 4,4'-dihydroxybiphenol, o-, m-, and p-dihydroxybenzene, 1,2-indanediol, 1,3-naphthalenediol, 1,5-naphthalenediol, 1,7-naphthalenediol, 9,9'-bis(4-hydroxyphenyl)fluorene, and 9,9'-bis(3-methyl-4-hydroxyphenyl)fluorene.
Other examples include phosphorus atom-containing diols, sulfur atom-containing diols, and bromine atom-containing diols.

Also usable are those having repeating units with a degree of polymerization of 2 or more in their structure, such as polyester polyols, polycarbonate polyols, polyether polyols, polybutadiene polyols, and polysiloxane polyols.

By reacting these polyol compounds with polyamide (A-1) and introducing ester bonds, it is possible to improve the solubility in general-purpose solvents compared to when the ester bonds are not present. The ratio of amide bonds to ester bonds in the polyamide ester (A-2) is preferably 0.5 or more, more preferably 0.7 or more, and even more preferably 1 or more.
By making the amide bond/ester bond ratio 0.5 or more, it is possible to improve the solubility in general-purpose solvents while taking advantage of the excellent heat resistance, moldability, and insulation reliability of the amide bond. When heat resistance, moldability, and insulation reliability are more important than solubility in general-purpose solvents, it is preferable to increase the number of amide bonds.
The theoretical amide bond/ester bond ratio in the polyamide ester (A-2) can be determined as follows.
The mole number of the functional group (i.e., amino group) which is less among the mole number of the carboxyl group in the polybasic acid compound and the mole number of the amino group in the polyamine compound used in the polyamide polymerization is taken as the mole number of the amide bond. On the other hand, the mole number of the functional group which is less among the mole number of the carboxyl group in the polyamide and the mole number of the alcoholic hydroxyl group in the polyol compound used in the polyester polymerization is taken as the mole number of the ester bond. The mole number of the amide bond/ester bond molar ratio can be calculated by dividing the mole number of the amide bond by the mole number of the ester bond.
The number of moles of each functional group, carboxyl group, amino group, and alcoholic hydroxyl group, can be obtained by multiplying the number of moles of each monomer containing the functional group by the number of functional groups contained in the monomer. The number of moles of each monomer can be calculated from the mass of the monomer used in the polymerization and the molecular weight of the monomer.

<Polyamide (A-3)>
Polyamide (A-3) is a polyamide obtained by mixing polyamides (a-1) and (a-2). Polyamide (a-1) is obtained by polymerizing a polybasic acid monomer (m ₃ ) and a polyamine monomer (m ₄ ), and has a phenolic hydroxyl group in a side group and does not have a C20-60 hydrocarbon group. As long as the above conditions are satisfied, other polybasic acid monomers and polyamine monomers can be used as appropriate.
That is, the polybasic acid monomer (m ₃ ) is selected from at least one selected from the group consisting of polybasic acid compounds having a phenolic hydroxyl group and other polybasic acid compounds (excluding polybasic acid compounds having a C20-60 hydrocarbon group), and the polyamine monomer (m ₄ ) is selected from at least one selected from the group consisting of polyamine compounds having a phenolic hydroxyl group and other polyamine compounds (excluding polyamine compounds having a C20-60 hydrocarbon group), so that a phenolic hydroxyl group is contained in the polymer.
At least one of the polybasic acid monomer (m ₃ ) and the polyamine monomer (m ₄ ) has a phenolic hydroxyl group. A divalent monomer and a trivalent or higher monomer may be combined to introduce a branched structure and adjust the molecular weight appropriately. It is also possible to use a monovalent monomer to keep the molecular weight appropriate.
That is, the polyamide (a-1) is a polyamide having a phenolic hydroxyl group in the side group but not having a C20-60 hydrocarbon group.

On the other hand, the polybasic acid monomer (m ₅ ) is at least one selected from the group consisting of polybasic acid compounds containing a C20-60 hydrocarbon group and other polybasic acid compounds (excluding polybasic acid compounds having a phenolic hydroxyl group), and the polyamine monomer (m ₆ ) is at least one selected from the group consisting of polyamine compounds containing a C20-60 hydrocarbon group and other polyamine compounds (excluding polyamine compounds having a phenolic hydroxyl group), and at least one of the polybasic acid monomer (m ₅ ) and the polyamine monomer (m ₆ ) contains a C20-60 hydrocarbon group.
That is, the polyamide (a-2) is a polyamide having a C20-60 hydrocarbon group but no phenolic hydroxyl group in the side group.

In other words, polyamide (A-3) is a mixture of polyamide (a-1) having a phenolic hydroxyl group in the side group but no C20-60 hydrocarbon group, and polyamide (a-2) having a C20-60 hydrocarbon group but no phenolic hydroxyl group in the side group.
The tri- or higher functional compound (C2) capable of reacting with a phenolic hydroxyl group, which will be described later, is capable of reacting with at least one of a carboxyl group and an amino group in many cases in addition to reacting with a phenolic hydroxyl group.
When a thermosetting resin composition containing polyamide (A-3) and a tri- or higher functional compound (C2) capable of reacting with a phenolic hydroxyl group is heat-cured, if the tri- or higher functional compound (C2) capable of reacting with a phenolic hydroxyl group is one capable of reacting with at least one of a carboxyl group and an amino group, the terminal carboxyl group and the terminal amino group of the polyamide (a-1) containing a phenolic hydroxyl group and the polyamide (a-2) having a C20-60 hydrocarbon group in the polyamide (A-3) can also be utilized in the thermosetting reaction.

The mixing ratio of polyamide (a-1) containing phenolic hydroxyl groups to polyamide (a-2) having C20-60 hydrocarbon groups can be adjusted appropriately depending on the phenolic hydroxyl value and molecular weight of polyamide (a-1), but it is preferable that polyamide containing phenolic hydroxyl groups:polyamide having C20-60 hydrocarbon groups = 5:95 to 80:20 (mass ratio), and more preferably 10:90 to 50:50.

The terms "mixture" and "mixing" in reference to polyamide (A-3) include the following cases. That is, the case where a mixture is obtained in advance from polyamide (a-1) and polyamide (a-2) and then a trifunctional or higher compound (C2) capable of reacting with a phenolic hydroxyl group, which will be described later, is blended; the case where polyamide (a-1), polyamide (a-2) and a trifunctional or higher compound (C2) capable of reacting with a phenolic hydroxyl group, which will be described later, are blended; the case where polyamide (a-1) and a trifunctional or higher compound (C2) capable of reacting with a phenolic hydroxyl group, which will be described later, are blended and then polyamide (a-2) is blended; and the reverse is also included.

As the polybasic acid monomer (m ₃ ), there can be mentioned, among the polybasic acid monomers (m ₁ ), those other than the polybasic acid compounds containing a C20 to 60 hydrocarbon group. Also, monobasic compounds can be used in combination.
As the polyamine monomer (m ₄ ), there can be mentioned, among the polyamine monomers (m ₂ ), polyamine compounds other than those containing a C20 to C60 hydrocarbon group. Also, monofunctional amine compounds can be used in combination.

As the polybasic acid monomer (m ₅ ), there can be mentioned, among the polybasic acid monomers (m ₁ ), those other than the polybasic acid compounds having a phenolic hydroxyl group. Furthermore, monobasic compounds can also be used in combination.
As the polyamine monomer (m ₆ ), there can be mentioned, among the polyamine monomers (m ₂ ), polyamine compounds other than those having a phenolic hydroxyl group. Also, monofunctional amine compounds can be used in combination.

The polyamide (A-3) preferably contains 10 to 95 mol %, more preferably 14 to 92 mol %, and even more preferably 18 to ₈₈ mol % of a compound containing a C20 to ₆₀ hydrocarbon group per 100 mol in total of all monomers used in the formation thereof, i.e., the polybasic acid monomer (m ₃ ), the polyamine monomer (m 4 ), the polybasic acid monomer (m 5 ), the polyamine monomer (m ₆ ), and the monobasic acid or monofunctional amine compound used as necessary.

<Specifications of Polyamide Resin (P2)>
Next, the specifications (phenolic hydroxyl value, weight average molecular weight, glass transition temperature) of the polyamide resin (P2) will be described.

As long as the polyamide resin (P2) contains phenolic hydroxyl groups in the polyamide side groups, the terminals may be carboxyl groups or amino groups, or the polyamide resin may not have functional groups at the terminals. The amount of phenolic hydroxyl groups contained in the polyamide side groups can be adjusted as appropriate by changing the type and amount of the trifunctional or higher compound (C2) that can react with the phenolic hydroxyl groups.

[Phenol hydroxyl value]
Specifically, the phenolic hydroxyl value of the polyamide resin (P2) is preferably 1 to 80 mgKOH/g, more preferably 5 to 60 mgKOH/g, and even more preferably 5 to 30 mgKOH/g. By using a polyamide having a phenolic hydroxyl value of 1 mgKOH/g or more, a dense crosslinked structure can be formed, and the resistance of the cured coating film can be improved. In addition, by using a polyamide having a phenolic hydroxyl value of 80 mgKOH/g or less, a cured coating film having good hardness, adhesion, and flexibility can be obtained. In addition, when a polyamide having a phenolic hydroxyl value in the range of 1 to 80 mgKOH/g close to 1 mgKOH/g is used, the adhesion and flexibility of the resulting coating film are improved, while when a polyamide having a phenolic hydroxyl value in the range of 80 mgKOH/g close to 1 mgKOH/g is used, the number of crosslinking points increases, and the heat resistance of the finally obtained coating film is improved. In this way, the phenolic hydroxyl value of the polyamide resin (P2) can be adjusted according to the purpose within the range of 1 to 80 mgKOH/g.

In the case of (i), the phenolic hydroxyl value can be adjusted by the charge ratio (polymerization composition) of the monomer having a phenolic hydroxyl group among the monomers. In the case of (ii), the phenolic hydroxyl value can be adjusted by the ratio of the monomer having a phenolic hydroxyl group among all the monomers in the polyamides (a-1) and (a-2). For example, by using only 5-hydroxyisophthalic acid having a phenolic hydroxyl group as the polybasic acid compound and only dimer diamine having no phenolic hydroxyl group as the polyamine compound, the phenolic hydroxyl value of the finally obtained polyamide resin (P2) can be made close to 80 mgKOH/g, and the heat resistance of the cured coating film can be further improved.

In the case of polyamide (A-3) among polyamide resins (P2), the phenolic hydroxyl value of the mixture is regarded as the phenolic hydroxyl value of polyamide resin (P2).

[Weight average molecular weight]
Of the polyamide resins (P2), the weight average molecular weight of the polyamide (A-1) is preferably 3,000 to 1,000,000, more preferably 5,000 to 550,000, and even more preferably 10,000 to 300,000, from the viewpoints of handleability and adhesiveness and heat resistance when made into a thermosetting resin composition.
Of the polyamide resins (P2), the weight average molecular weight of the polyamide (a-1) is preferably 500 to 30,000, more preferably 1000 to 20,000, and even more preferably 1,000 to 10,000, from the viewpoint of solubility in general-purpose solvents described later.
In addition, among the polyamide resins (P2), the weight average molecular weight of the polyamide (a-2) is preferably in the same range as that of the polyamide (A-1).

[Glass transition temperature of polyamide resin (P2)]
The glass transition temperature of the polyamide resin (P2) is preferably −40° C. to 120° C., and more preferably −30° C. to 80° C. By adjusting the glass transition temperature of the polyamide resin (P2) to the range of −40° C. to 120° C., it is possible to suppress extrusion during hot pressing, and further to achieve good embedding properties in a substrate, thereby further improving adhesion.

The glass transition temperature can be adjusted by appropriately setting the ratio of polybasic acid compounds having C20-60 hydrocarbon groups or polyamine compounds having C20-60 hydrocarbon groups. For example, by increasing the blending ratio of polybasic acid compounds having C20-60 hydrocarbon groups or polyamine compounds having C20-60 hydrocarbon groups, it is possible to lower the concentration of amide bonds with high water absorption and impart the flexibility and bendability characteristic of dimerized fatty acids, so that the glass transition temperature can be adjusted to a range close to -40°C.

In the case of polyamide (A-3) among polyamide resins (P2), the glass transition temperature of the mixture is regarded as the glass transition temperature of polyamide resin (P2).

[Organic solvent solubility of polyamide resin (P2)]
The polyamide resin (P2) is soluble in a wide range of general-purpose organic solvents. The term "soluble" means that the polyamide resin dissolves at 5 parts by mass or more in 95 parts by mass of a mixed solvent of general-purpose solvents such as hydrocarbon solvents, alcohol solvents, ketone solvents, and ester solvents at 25°C. In particular, the polyamide resin dissolves at 5 parts by mass or more in 95 parts by mass of a mixed solvent of toluene/isopropanol = 50/50 (mass ratio) at 25°C.
Examples of the hydrocarbon solvent include benzene, toluene, ethylbenzene, xylene, cyclohexane, hexane, etc. Examples of the alcohol solvent include methanol, ethanol, propanol, isopropanol, butanol, isobutanol, sec-butanol, tert-butanol, etc. Examples of the ketone solvent include acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, etc. Examples of the ester solvent include methyl acetate, ethyl acetate, propyl acetate, butyl acetate, etc.

<Synthesis of polyamide resin (P2)>
Next, a method for synthesizing the polyamide resin (P2) will be described.
The polymerization conditions for the polyamide resin (P2) are not particularly limited, and known conditions such as melt polymerization, interfacial polymerization, solution polymerization, bulk polymerization, solid-phase polymerization, and combinations of these methods can be used. Generally, industrially, the reaction is carried out at 150 to 300°C for about 1 to 24 hours in the presence or absence of a catalyst. In order to promote the dehydration or dealcoholization reaction and to avoid coloration and decomposition reactions due to high temperatures, it is preferable to carry out the reaction at 180 to 270°C under reduced pressure below atmospheric pressure.

When synthesizing a polyamide (A-1) containing a phenolic hydroxyl group, for example, a flask filled with nitrogen is charged with a polybasic acid compound having a phenolic hydroxyl group and/or a polyamine compound having a phenolic hydroxyl group, a polybasic acid compound having a C20-60 hydrocarbon group and/or a polyamine compound having a C20-60 hydrocarbon group, and ion-exchanged water in predetermined amounts, and the mixture is heated and stirred at 20 to 100° C. to uniformly dissolve or disperse the mixture. Thereafter, the mixture is gradually heated to 230° C. while removing the ion-exchanged water and water generated by the reaction, and when the temperature reaches 230° C., the pressure is reduced to about 15 mmHg and maintained for about 1 hour to obtain polyamide (A-1).
In addition, when a polybasic acid compound and a polyamine compound are mixed, a salt is formed and the mixture tends to solidify. When the two are mixed in the presence of ion-exchanged water, the salt formed dissolves or disperses in the ion-exchanged water. Therefore, it is preferable to use ion-exchanged water from the viewpoint of safety, etc.

When synthesizing a polyamide ester (A-2) containing a phenolic hydroxyl group having an ester bond, for example, a polyamide (A-1) having a terminal carboxylic acid is synthesized by reacting a polybasic acid compound in a ratio in which the total molar ratio is greater than the total molar ratio of the polyamine compound, and then a polyol compound and an esterification catalyst are added, the temperature is gradually increased again to 230°C, and then the pressure is reduced to 1 to 2 mmHg and maintained for 3 hours to obtain polyamide ester (A-2).

Specific examples of catalysts that can be used to obtain polyamide (A-1) and polyamide ester (A-2) include inorganic phosphorus compounds such as phosphoric acid, phosphorous acid, hypophosphorous acid, pyrophosphoric acid, polyphosphoric acid, and their alkali metal salts and alkaline earth metal salts; phosphites such as triphenyl phosphite and diphenyl phosphite; titanium-based catalysts such as tetrabutyl orthotitanate and tetraisopropyl orthotitanate; tin-based catalysts such as dibutyltin oxide, dibutyltin laurate, and monobutylhydroxytin oxide; and zirconium-based catalysts such as tetrabutoxyzirconium, zirconium acetate, and zirconium octylate.

These may be used in combination of two or more kinds. In addition, the present invention may be carried out without any problem even if these catalysts are contained in the polyamide resin (P2).

The by-products are inorganic salt catalysts such as decomposition products of the catalyst used, oxides of the decomposition products or modified products thereof, and by-products of amide compounds such as oligomers, but they may be contained in the polyamide resin (P2).

<Tri- or More Functional Compound (C2) Reactive with Phenolic Hydroxyl Group>
The thermosetting resin composition of this embodiment contains the polyamide resin (P2) and a trifunctional or higher compound (C2) capable of reacting with a phenolic hydroxyl group. The trifunctional or higher compound (C2) capable of reacting with a phenolic hydroxyl group will be described. The composition (II) uses the compound (C2) as a curing agent for the polyamide resin (P2) described above. In addition to the trifunctional or higher compound (C2), a bifunctional compound (C) capable of reacting with a phenolic hydroxyl group [hereinafter also referred to as "compound (C)"] can also be added within the scope of this embodiment. When compound (C) is added, it is preferable to set it to 100 parts by mass or less, more preferably 60 parts by mass or less, from the viewpoint of effectively increasing the crosslink density with respect to 100 parts by mass of compound (C2).

[Epoxy group-containing compound]
The tri- or higher functional epoxy group-containing compound that can be used as the compound (C2) is not particularly limited as long as it is a compound having an epoxy group in the molecule, and examples of the epoxy resin that can be used include glycidyl ether type epoxy resins, glycidyl amine type epoxy resins, glycidyl ester type epoxy resins, and cyclic aliphatic (alicyclic) epoxy resins.

Examples of the glycidyl ether type epoxy resin include cresol novolac type epoxy resin, phenol novolac type epoxy resin, and tetrakis(glycidyloxyphenyl)ethane.
Examples of the glycidylamine type epoxy resin include tetraglycidyldiaminodiphenylmethane and tetraglycidylmetaxylylenediamine.
As the epoxy group-containing compound, it is preferable to use tetrakis(glycidyloxyphenyl)ethane or tetraglycidyldiaminodiphenylmethane from the viewpoints of high adhesiveness and heat resistance.

Examples of epoxy group-containing compounds that can be used as compound (C) include glycidyl ether type epoxy resins, cyclic aliphatic (alicyclic) epoxy resins, bisphenol A type epoxy resins, bisphenol F type epoxy resins, dicyclopentadiene type epoxy resins, etc. Examples of glycidyl ester type epoxy resins include diglycidyl phthalate, diglycidyl hexahydrophthalate, and diglycidyl tetrahydrophthalate.
Examples of cyclic aliphatic (alicyclic) epoxy resins include 3',4'-epoxycyclohexylmethyl 3,4-epoxycyclohexane carboxylate, etc. As the epoxy group-containing compound, compound (C2) can be used alone or in combination of two or more kinds, or compound (C2) can be used in combination with compound (C).

[Isocyanate compounds]
The isocyanate group-containing compound that can be used as the compound (C2) is not particularly limited as long as it has three or more isocyanate groups in the molecule. The isocyanate group may be either blocked with a blocking agent or not, but is preferably blocked with a blocking agent.

The isocyanate group-containing compound that can be used as the bifunctional compound (C) that can react with a phenolic hydroxyl group is not particularly limited, but examples include aromatic diisocyanates such as 4,4'-diphenylmethane diisocyanate, 2,4-tolylene diisocyanate, and 2,6-tolylene diisocyanate, aliphatic diisocyanates such as hexamethylene diisocyanate, and alicyclic diisocyanates such as isophorone diisocyanate, etc.

The isocyanate group-containing compound that can be used as the trifunctional or higher compound (C2) that can react with a phenolic hydroxyl group is not particularly limited, but examples thereof include the trimethylolpropane adduct of the diisocyanate described above, the biuret product reacted with water, and a trimer having an isocyanurate ring.

The blocked isocyanate compound is not particularly limited as long as it is a blocked isocyanate group-containing compound in which the isocyanate group in the isocyanate group-containing compound is protected with ε-caprolactam, MEK oxime, or the like. Specific examples include compounds in which the isocyanate group in the isocyanate group-containing compound is blocked with ε-caprolactam, MEK oxime, cyclohexanone oxime, pyrazole, phenol, or the like. In particular, hexamethylene diisocyanate trimer having an isocyanurate ring and blocked with MEK oxime or pyrazole is highly preferred when used in this embodiment because it not only has excellent storage stability, but also excellent adhesive strength and solder heat resistance to bonding materials such as polyimide and copper.

[Carbodiimide group-containing compound]
Examples of carbodiimide group-containing compounds that can be used as the trifunctional or higher functional compound (C2) that can react with a phenolic hydroxyl group include the Carbodilite series manufactured by Nisshinbo Industries, Inc. Among these, Carbodilite V-01, 03, 05, 07, and 09 are preferred because they have excellent compatibility with organic solvents.

[Metal chelate compounds]
Metal chelate compounds usable as the trifunctional or higher compound (C2) capable of reacting with a phenolic hydroxyl group include aluminum chelate compounds, titanium chelate compounds, and zirconium chelate compounds, but are not particularly limited because chelate bonds can be formed even with various metals having a central metal such as iron, cobalt, indium, etc. The number of functional groups of the metal chelates and metal alkoxides and metal acylates described below is calculated as the valence of the central metal, and trifunctional or higher compounds, i.e. compounds having a central metal valence of 3 or higher, can be used as the compound (C2).

Representative examples of the aluminum chelate compound used in composition (II) include aluminum acetylacetonate and aluminum ethyl acetoacetate.

Typical examples of titanium chelate compounds include titanium acetylacetonate, titanium ethylacetoacetate, titanium octylene glycolate, titanium lactate, titanium triethanolamine, and polytitanium acetylacetonate.

Typical examples of zirconium chelate compounds include zirconium acetylacetonate, zirconium ethyl acetylacetonate, and zirconium lactate ammonium salt.

[Metal alkoxide]
Examples of metal alkoxide compounds include aluminum alkoxide compounds, titanium alkoxide compounds, and zirconium alkoxide compounds, but are not particularly limited because alkoxide bonds can be formed with various metals such as iron, cobalt, and indium as the central metal.

Typical examples of aluminum alkoxide compounds include aluminum isopropylate, aluminum butyrate, and aluminum ethylate.

Typical examples of titanium alkoxide compounds include isopropyl titanate, normal butyl titanate, butyl titanate dimer, tetraoctyl titanate, tertiary amyl titanate, tertiary butyl titanate, and tetrastearyl titanate.

Typical examples of zirconium alkoxide compounds include normal propyl zirconate and normal butyl zirconate.

[Metal acylate]
Examples of metal acylate compounds include aluminum acylate compounds, titanium acylate compounds, and zirconium acylate compounds, but are not particularly limited because alkoxide bonds can be formed with various metals such as iron, cobalt, and indium as the central metal.

The tri- or higher functional compound (C2) includes not only three or more functional groups of the same type in one molecule, but also functional groups containing three or more functional groups in total. For example, a mixture of chelate, alkoxide, and acylate in one molecule can also be suitably used.

Only one type of compound (C2) may be used alone, or multiple compounds may be used in combination. When multiple compounds are used in combination, a synergistic effect is exhibited, such as improved processability and adhesion, by utilizing the difference in reactivity between the polyamide resin (P2) containing a mixture of phenolic groups and carboxyl groups and/or amino groups, which is desirable. Among them, "at least one selected from the group consisting of metal chelates, metal alkoxides, and metal acylates" and "a trifunctional or higher epoxy group-containing compound" are preferred because they have significantly different reactivities and can be expected to have a large synergistic effect due to the different characteristics of the physical properties that can be improved. The amount of compound (C2) used may be determined in consideration of the application of the curable resin composition, and is not particularly limited, but is preferably added in a ratio of 0.5 to 100 parts by mass, and more preferably 1 to 80 parts by mass, per 100 parts by mass of polyamide resin (P2). By using compound (C2), the crosslink density of the curable resin composition can be adjusted to an appropriate value, so that various physical properties of the coating film after curing can be further improved. When the amount of compound (C2) used is close to 0.5 parts by mass, the crosslink density of the coating film after heat curing can be prevented from becoming too high, and the desired flexibility and adhesion can be exhibited. Furthermore, by suppressing an increase in polar functional groups, the desired dielectric constant, dielectric tangent, and moist heat resistance can be exhibited. Furthermore, when the amount used is close to 100 parts by mass, the crosslink density after heat curing can be further increased, and as a result, the coating film resistance, such as the electrical insulation of the coating film, can be improved.

In the composition (II), a compound capable of reacting with a carboxyl group or a compound capable of reacting with an amino group can be used in combination with the compound (C2).
Examples of compounds that can react with a carboxyl group include aziridine compounds, β-hydroxyalkylamide group-containing compounds, and dicyandiamide, while examples of compounds that can react with an amino group include maleimide compounds.

In particular, 2,2'-bishydroxymethylbutanol tris[3-(1-aziridinyl)propionate] is preferably used in this embodiment because, when used in this embodiment, it can suppress extrusion during heat pressing and improve the heat resistance while maintaining the flexibility of the cured coating film.

Composition (II) may contain a compound that directly contributes to the curing reaction as a curing accelerator. Examples of the curing accelerator include phosphine compounds, phosphonium salts, imidazole compounds, and tertiary amine compounds.

The composition (II) essentially contains the polyamide resin (P2) and the compound (C2), and may contain an organic solvent as appropriate.
Examples of low boiling point solvents include toluene, cyclohexane, hexane, isopropanol, methyl ethyl ketone, ethyl acetate, etc. Examples of high boiling point solvents include carbitol acetate, methoxypropyl acetate, cyclohexanone, diisobutyl ketone, N,N-dimethylformamide, N,N-dimethylacetamide, N-methyl-2-pyrrolidone, dimethyl sulfoxide, etc. Organic solvents can be used alone or in combination as appropriate.
When a solvent is used in producing the polyamide resin (P2), the composition (II) may contain the solvent, or the solvent used in producing the polyamide resin (P2) may be distilled off and then another solvent may be added to obtain a liquid composition (II).
The solid content of the composition (II) is from 5 to 80% by mass, and preferably from the viewpoint of handling properties, from 10 to 50% by mass.

<Other additives>
Composition (II) may further contain other components (additives) exemplified in composition (I)-1 as optional components within the scope of not impairing the object of the invention, such as dyes, pigments, flame retardants, antioxidants, polymerization inhibitors, defoamers, leveling agents, ion collectors, moisturizers, viscosity modifiers, preservatives, antibacterial agents, antistatic agents, antiblocking agents, ultraviolet absorbers, infrared absorbers, and fillers.
As the filler, the same fillers as those in the composition (I)-1 can be suitably used.
In particular, when the prepreg of the present embodiment is used for an insulating member that is in direct contact with a circuit in electronic material applications (e.g., a circuit protective film, a coverlay layer, an interlayer insulating material, etc.) or a member that may become highly heated around a circuit (e.g., a printed wiring board, a supporting substrate, etc.), it is preferable to use a flame retardant in combination.

[[Composition (III)]]
The composition (III) is a thermosetting resin composition containing a polyurethane resin (P3) and an epoxy compound (C3) capable of reacting with the polyurethane resin. The polyurethane resin also includes a polyurethane polyurea resin.

The following are examples of methods for synthesizing the carboxyl group-containing polyurethane resin (P3). For example, it can be produced by reacting a polyol compound, a diisocyanate compound, and a diol compound having a carboxyl group. In addition, when synthesizing the polyurethane resin (P3), an excess of a diisocyanate compound can be added to synthesize a carboxyl group-containing urethane prepolymer having an isocyanate group at its terminal, and then a diamine compound can be reacted to produce a urethane urea resin into which a urea group has been introduced.

The polyol compound refers to a compound having a weight average molecular weight of 500 or more and two or more hydroxyl groups. Specific examples of the polyol compound include polyether polyols such as polyethylene oxide, polypropylene oxide, block copolymers or random copolymers of ethylene oxide/propylene oxide, polytetramethylene glycol, and block copolymers or random copolymers of tetramethylene glycol and neopentyl glycol;
Polyester polyols which are condensation products of polyhydric alcohols or polyether polyols with polybasic acids such as maleic anhydride, maleic acid, fumaric acid, itaconic anhydride, itaconic acid, adipic acid, isophthalic acid, etc.; polycarbonate polyols obtained by the reaction of glycol or bisphenol with a carbonate ester, or by the reaction of glycol or bisphenol with phosgene in the presence of an alkali;
Examples of the polyol include caprolactone-modified polyols such as caprolactone-modified polytetramethylene polyols, polyolefin-based polyols, polybutadiene-based polyols such as hydrogenated polybutadiene polyols, silicone-based polyols, etc. These polyol compounds may be used alone or in combination of two or more kinds.

The diol compound having a carboxyl group is not particularly limited as long as it has two hydroxyl groups and one or more carboxyl groups in the molecule, but examples include dimethylolbutanoic acid, dimethylolpropionic acid, and derivatives thereof (caprolactone adducts, ethylene oxide adducts, propylene oxide adducts, etc.), 3-hydroxysalicylic acid, 4-hydroxysalicylic acid, 5-hydroxysalicylic acid, 2-carboxy-1,4-cyclohexanedimethanol, etc. These diol compounds having a carboxyl group may be used alone or in combination of two or more types.

Examples of diisocyanate compounds include aromatic diisocyanates, aliphatic diisocyanates, araliphatic diisocyanates, and alicyclic diisocyanates.

Examples of aromatic diisocyanates include 1,3-phenylene diisocyanate, 4,4'-diphenyl diisocyanate, 1,4-phenylene diisocyanate, 4,4'-diphenylmethane diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 4,4'-toluidine diisocyanate, 2,4,6-triisocyanate toluene, 1,3,5-triisocyanate benzene, dianisidine diisocyanate, 4,4'-diphenyl ether diisocyanate, 4,4',4"-triphenylmethane triisocyanate, etc.

Examples of aliphatic diisocyanates include trimethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, pentamethylene diisocyanate, 1,2-propylene diisocyanate, 2,3-butylene diisocyanate, 1,3-butylene diisocyanate, dodecamethylene diisocyanate, and 2,4,4-trimethylhexamethylene diisocyanate.

Examples of aromatic aliphatic diisocyanates include ω,ω'-diisocyanate-1,3-dimethylbenzene, ω,ω'-diisocyanate-1,4-dimethylbenzene, ω,ω'-diisocyanate-1,4-diethylbenzene, 1,4-tetramethylxylylene diisocyanate, and 1,3-tetramethylxylylene diisocyanate.

Examples of alicyclic diisocyanates include 3-isocyanatemethyl-3,5,5-trimethylcyclohexyl isocyanate [also known as isophorone diisocyanate], 1,3-cyclopentane diisocyanate, 1,3-cyclohexane diisocyanate, 1,4-cyclohexane diisocyanate, methyl-2,4-cyclohexane diisocyanate, methyl-2,6-cyclohexane diisocyanate, 4,4'-methylenebis(cyclohexyl isocyanate), 1,3-bis(isocyanatemethyl)cyclohexane, and 1,4-bis(isocyanatemethyl)cyclohexane.
These diisocyanate compounds may be used alone or in combination of two or more kinds.

The diamine compound acts as a chain extender, and examples thereof include diaminobenzene, diaminotoluene, diaminodimethylbenzene, diaminomesitylene, diaminochlorobenzene, diaminonitrobenzene, diaminoazobenzene, diaminonaphthalene, diaminobiphenyl, diaminodimethoxybiphenyl, diaminodiphenyl ether, diaminodimethyldiphenyl ether, methylenedianiline, methylenebis(methylaniline), methylenebis(dimethylaniline), methylenebis(methoxyaniline), and methylenebis(dimethoxyaniline). aromatic polyamines such as methylene bis(ethylaniline), methylene bis(diethylaniline), methylene bis(ethoxyaniline), methylene bis(diethoxyaniline), methylene bis(dibromoaniline), isopropylidenedianiline, hexafluoroisopropylidenedianiline, diaminobenzophenone, diaminodimethylbenzophenone, diaminoanthraquinone, diaminodiphenyl thioether, diaminodimethyldiphenyl thioether, diaminodiphenyl sulfone, diaminodiphenyl sulfoxide, and diaminofluorene;
aliphatic polyamines such as ethylene polyamines, propane polyamines, hydroxypropane polyamines, butane polyamines, heptane polyamines, hexane polyamines, diaminodiethylamine, diaminodipropylamine, azapentane polyamines, triazaundecane polyamines, nonamethylene polyamines, undecamethylene polyamines, dodecamethylene polyamines, methylpentamethylene polyamines, 2,2,4 (or 2,4,4)-trimethylhexamethylene polyamines, and polyamine compounds having 20 to 48 carbon atoms;
Alicyclic polyamines such as bis-(4,4'-aminocyclohexyl)methane, metaxylylenepolyamine, paraxylylenepolyamine, isophoronepolyamine, norbornanepolyamine, cyclopentanepolyamine, cyclohexanepolyamine, piperazine, and homopiperazine can be used.

It is preferable to use a urethane urea resin with urea groups introduced as the polyurethane resin (P3). By introducing urea groups, it becomes easier to improve adhesion and flexibility.

<Epoxy compound (C3)>
The epoxy group-containing compound that can be used as the epoxy compound (C3) may be any compound having an epoxy group in the molecule, and is not particularly limited thereto. However, epoxy resins such as glycidyl ether type epoxy resins, glycidyl amine type epoxy resins, glycidyl ester type epoxy resins, or cyclic aliphatic (alicyclic) epoxy resins can be used. The number of functional groups of the epoxy group is not particularly limited, but is preferably bifunctional or more, and more preferably trifunctional or more. Specific examples include compounds similar to the compound (C2) exemplified in the composition (II). Also, examples include epoxy compounds having at least one nitrogen atom in the molecule.

By using an epoxy compound that has at least one tertiary nitrogen atom in the molecule, it is possible to improve the dielectric constant and dielectric tangent while also improving metal adhesion and heat resistance. This is because the high reactivity, which is a unique property of epoxy compounds that have tertiary nitrogen atoms, makes it possible to increase the reaction rate under specified curing conditions, improve the crosslink density of the cured product, and obtain a high elastic modulus. As a result, it is possible to suppress the water absorption rate, which determines the dielectric properties. In addition, nitrogen atoms can take various coordination forms, which strongly support adhesion between metals and organic compounds and also provide excellent metal adhesion.

When an epoxy compound having at least one tertiary nitrogen atom in the molecule is used, the nitrogen atoms contained in the compound can increase the reaction rate under specified curing conditions, making it possible to suppress the decrease in elastic modulus and increase in water absorption rate caused by unreacted low molecular weight compounds, and furthermore, the metal adhesion derived from the nitrogen atoms can be improved, so that good dielectric properties and various other properties can be satisfied at the same time.
The epoxy compound having at least one or more tertiary nitrogen atoms in the molecule is not particularly limited as long as it has at least one nitrogen compound in a compound containing an epoxy group in the molecule. Specific examples of the epoxy compound having at least one or more tertiary nitrogen atoms in the molecule include N-glycidylphthalimide and epoxy compounds having structures represented by the following formulas (5) to (15).

In the formula, X represents an aliphatic group having 0 to 6 carbon atoms or an aromatic group; Y represents any one of a methylene group, an ethylene group, a trimethylene group, an ethylidene group, an isopropylidene group, a vinylene group, a vinylidene group, an oxy group, an imino group, a thio group, and a sulfonyl group; R ₁ to R ₃ represent a hydrogen atom or an aliphatic group having 1 to 6 carbon atoms; and j represents an integer of 0 to 4.

All of these are preferred because they have excellent dielectric properties in terms of thermosetting and low moisture absorption, but 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane, N,N,N',N'-tetraglycidyl-m-xylylenediamine, triglycidyl-m-aminophenol, triglycidyl-p-aminophenol, and 4,4'-methylenebis[N,N-bis(oxiranylmethyl)aniline] are particularly preferred because they are multifunctional and tend to improve the heat resistance of the cured prepreg when used in composition (III) in addition to the dielectric properties. In addition, N,N-diglycidylaniline and N,N-diglycidyltoluidine are bifunctional and tend to improve the flexibility of the cured coating film and the adhesion to polyimide and copper when used in composition (III) in addition to the dielectric properties, and are therefore preferred.

[[Composition (I)-2]]
Composition (I)-2 is a thermosetting resin composition containing a styrene-based elastomer (P1) having an acid anhydride group (anhydride group of a carboxylic acid) and an epoxy compound (C4) that reacts with the acid anhydride group. The styrene-based elastomer (P1) is the same as in composition (I)-1, so a description thereof will be omitted. By reacting the acid anhydride group in the styrene-based elastomer (P1) with the epoxy compound (C4), an ester group that is excellent in heat resistance and has the function of suppressing the dielectric constant and dielectric loss tangent can be formed.

<Epoxy compound (C4)>
By reacting the epoxy compound (C4) with the above-mentioned styrene-based elastomer (P1), a cured product having excellent heat resistance and insulation properties and low dielectric constant and dielectric loss tangent can be obtained. The epoxy compound (C4) is not particularly limited as long as it has one or more epoxy groups, but an epoxy compound having two or more epoxy groups is preferred, and an epoxy compound having three or more epoxy groups is more preferred. Among these, a glycidylamine-based epoxy compound having three or more epoxy groups is particularly preferred. By using the epoxy compound (C4), further adhesion can be imparted.

Examples of epoxy group-containing compounds that can be used as the epoxy compound (C4) include ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, bisphenol A-epichlorohydrin type epoxy resin, bisphenol F-epichlorohydrin type epoxy resin, biphenol-epichlorohydrin type epoxy resin, polyglycidyl ether of glycerin-epichlorohydrin adduct, resorcinol diglycidyl ether, polybutadiene diglycidyl ether, hydroquinone diglycidyl ether, dibromoneopentyl glycol diglycidyl ether, neopentyl glycol diglycidyl ether, hexahydrophthalic acid diglycidyl ester, hydrogenated bisphenol A type diglycidyl ether, Examples of such epoxy compounds include epoxy compounds having excellent flexibility as disclosed in JP-A-2004-156024, JP-A-2004-315595, and JP-A-2004-323777, and epoxy compounds having the structure represented by the following formula:

Other examples include epoxy resins such as glycidyl ether type epoxy resins, glycidyl amine type epoxy resins, glycidyl ester type epoxy resins, and cyclic aliphatic (alicyclic) epoxy resins. Specific examples include compounds similar to compound (C2) exemplified in composition (II) and compound (C3) exemplified in composition (III).

In addition, by using an epoxy compound having at least one nitrogen atom in the molecule, it is possible to more effectively improve the dielectric constant and the dielectric loss tangent while improving the metal adhesion and heat resistance. The reason is as explained in the composition (III), and the same effect can be obtained with the styrene-based elastomer (P1) and the epoxy compound (C4) that reacts with the acid anhydride group of the styrene-based elastomer (P1).
Suitable examples of the epoxy compound having at least one tertiary nitrogen atom in the molecule include the compounds exemplified in the composition (III), specifically, N-glycidylphthalimide and the epoxy compounds having the structures represented by the above formulas (5) to (15).

All of these are preferred because they have excellent dielectric properties in terms of thermosetting and low moisture absorption, but 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane, N,N,N',N'-tetraglycidyl-m-xylylenediamine, triglycidyl-m-aminophenol, triglycidyl-p-aminophenol, and 4,4'-methylenebis[N,N-bis(oxiranylmethyl)aniline] are particularly preferred because they are multifunctional and tend to improve the heat resistance of the cured prepreg when used in composition (I)-2 in addition to the dielectric properties. In addition, N,N-diglycidylaniline and N,N-diglycidyltoluidine are bifunctional and tend to improve the flexibility of the cured coating film and the adhesion to polyimide and copper when used in composition (I)-2 in addition to the dielectric properties, and are therefore preferred.

Commercially available products include jER603 (a trifunctional polyfunctional glycidylamine compound, N,N-bis(2,3-epoxypropyl)-4-(2,3-epoxypropoxy)aniline), jER604 (a trifunctional polyfunctional glycidylamine compound, N,N,N',N'-tetraglycidyl-4,4'-diaminodiphenylethane), and TETRAD-X (a tetrafunctional polyfunctional glycidylamine compound).

The content of epoxy groups in the epoxy compound (C4) relative to 1 mol of acid anhydride groups in the styrene-based elastomer (P1) is preferably in the range of 0.1 to 20 mol, more preferably in the range of 0.5 to 10 mol, and even more preferably in the range of 1 to 5 mol. By making the content of epoxy groups 0.1 mol or more relative to the acid anhydride groups in the styrene-based elastomer (P1), the crosslink density can be increased and the heat resistance, insulating properties, and adhesive properties can be improved. By making the content of epoxy groups 20 mol or less, the generation of new polar groups can be suppressed and the deterioration of the dielectric tangent can be suppressed.

Composition (I)-2 can contain a silane coupling agent and/or a thiol compound to the extent that the physical properties are not impaired. The effects are as described for composition (I)-1. In addition, suitable examples and suitable contents of the silane coupling agent and thiol compound are the same as those for composition (I)-1.

A filler can be added to composition (I)-2 for the purposes of imparting flame retardancy, controlling the fluidity of the resin composition, improving the elastic modulus of the cured product, etc. The shape and preferred examples of the filler, the preferred range of average particle size and content, and the addition method are the same as those of composition (I)-1.

In addition to the essential components and the optional components described above, composition (I)-2 may further contain oxetane group-containing compounds, aziridine group-containing compounds, carbodiimide group-containing compounds, benzoxazine compounds, and β-hydroxyalkylamide group-containing compounds within the scope of the purpose. It may also contain dyes, pigments, antioxidants, polymerization inhibitors, defoamers, leveling agents, ion collectors, moisturizers, viscosity adjusters, preservatives, antibacterial agents, antistatic agents, antiblocking agents, ultraviolet absorbers, infrared absorbers, etc.

[[Composition (I)-3]]
Composition (I)-3 is a thermosetting resin composition containing a styrene-based elastomer (P1) having an acid anhydride group (anhydride group of a carboxylic acid) and a phenol compound (C5) that reacts with the acid anhydride group.
The styrene-based elastomer (P1) is the same as that in composition (I)-1, and therefore the explanation thereof will be omitted.
By reacting the acid anhydride group in the styrene-based elastomer (P1) with the phenol compound (C5), it is possible to form an ester group which has excellent heat resistance and also has the function of keeping the dielectric constant and the dielectric loss tangent low.

<Phenol Compound (C5)>
By reacting the phenolic compound (C5) with the above-mentioned styrene-based elastomer (P1), a cured product having excellent heat resistance and insulation properties, and low dielectric constant and dielectric loss tangent can be obtained. The phenolic compound (C5) is not particularly limited as long as it has one or more phenolic hydroxyl groups, but a phenolic compound having two or more phenolic hydroxyl groups is preferred, and a phenolic compound having three or more phenolic hydroxyl groups is more preferred. Furthermore, adhesion can be imparted.

A representative example of a phenolic hydroxyl group-containing compound that can be used as the phenol compound (C5) is, for example, 2,2-bis(4-hydroxyphenyl)propane (also known as bisphenol A). In addition, other examples include bis(4-hydroxyphenol)methane, 1,1-bis(4-hydroxyphenyl)ethane, 1,1-bis(4-hydroxyphenyl)-n-propane, 1,1-bis(4-hydroxyphenyl)-n-butane, 1,1-bis(4-hydroxyphenyl)-n-pentane, 1,1-bis(4-hydroxyphenyl)-n-hexane, 1,1-bis(4-hydroxyphenyl)-n-heptane, 1,1-bis(4-hydroxyphenyl)-n-octane, 1,1-bis(4-hydroxyphenyl)-n-nonane, 1,1-bis(4-hydroxyphenyl)-n-hexane ... bis(4-hydroxyphenyl)-n-decane, bis(4-hydroxyphenyl)phenylmethane, bis(4-hydroxyphenyl)naphthylmethane, bis(4-hydroxyphenyl)toluylmethane, bis(4-hydroxyphenyl)-(4-ethylphenyl)methane, bis(4-hydroxyphenyl)-(4-n-propylphenyl)methane, bis(4-hydroxyphenyl)-(4-isopropylphenyl)methane, bis(4-hydroxyphenyl)-(4-n-butylphenyl)methane, bis(4-hydroxyphenyl)-(4-pentylphenyl)methane, bis(4-hydroxyphenyl)-(4-hexylphenyl)methane, bis(4-hydroxyphenyl)-(4-fluorophenyl)methane, bis(4-hydroxyphenyl)-(4-chlorophenyl)methane , bis(4-hydroxyphenyl)-(2-fluorophenyl)methane, bis(4-hydroxyphenyl)-(2-chlorophenyl)methane, bis(4-hydroxyphenyl)tetrafluorophenylmethane, bis(4-hydroxyphenyl)tetrachlorophenylmethane, bis(3-methyl-4-hydroxyphenyl)methane, bis(3,5-dimethyl-4-hydroxyphenyl)methane, bis(3-ethyl-4-hydroxyphenyl)methane, bis(3-isobutyl-4-hydroxyphenyl)methane, bis(3-t-butyl-4-hydroxyphenyl)-1-phenylmethane, bis(3-phenyl-4-hydroxyphenyl)-1-phenylmethane, bis(3-fluoro-4-hydroxyphenyl)methane, bis(3,5-difluoro-4-his bisphenols in which a hydrogen atom is bonded to the central carbon, such as bis(3-chloro-4-hydroxyphenyl)methane, bis(3,5-dichloro-4-hydroxyphenyl)methane, 1,1-bis(3-methyl-4-hydroxyphenyl)ethane, 1,1-bis(3,5-dimethyl-4-hydroxyphenyl)ethane, 1,1-bis(3-ethyl-4-hydroxyphenyl)ethane, 1,1-bis(3-isobutyl-4-hydroxyphenyl)ethane, 1,1-bis(3-fluoro-4-hydroxyphenyl)ethane, 1,1-bis(3,5-difluoro-4-hydroxyphenyl)ethane, 1,1-bis(3-chloro-4-hydroxyphenyl)ethane, and 1,1-bis(3,5-dichloro-4-hydroxyphenyl)ethane;
2,2-bis(4-hydroxyphenyl)-n-butane, 2,2-bis(4-hydroxyphenyl)-n-pentane, 2,2-bis(4-hydroxyphenyl)-n-hexane, 2,2-bis(4-hydroxyphenyl)-n-heptane, 2,2-bis(4-hydroxyphenyl)-n-octane, 2,2-bis(4-hydroxyphenyl)-n-nonane, 2,2-bis(4-hydroxyphenyl)-n-decane, 1,1-bis(4-hydroxyphenyl)-1-phenyl ethane (commonly known as bisphenol P), 1,1-bis(4-hydroxyphenyl)-1-naphthylethan, 1,1-bis(4-hydroxyphenyl)-1-toluylethane, 1,1-bis(4-hydroxyphenyl)-1-(4-ethylphenyl)ethane, 1,1-bis(4-hydroxyphenyl)-1-(4-n-propylphenyl)ethane, 1,1-bis(4-hydroxyphenyl)-1-(4-isopropylphenyl)ethane, 1,1-bis(4-hydroxyphenyl)-1-(4-isopropylphenyl)ethane, 1,1-bis(4-hydroxyphenyl)-1-(4-isopropylphenyl)ethane, )-1-(4-n-butylphenyl)ethane, 1,1-bis(4-hydroxyphenyl)-1-(4-pentylphenyl)ethane, 1,1-bis(4-hydroxyphenyl)-1-(4-hexylphenyl)ethane, 1,1-bis(3-t-butyl-4-hydroxyphenyl)-1-phenylethane, 1,1-bis(3-phenyl-4-hydroxyphenyl)-1-phenylethane, 1,1-bis(4-hydroxyphenyl)-1-(4-fluorophenyl)ethane, 1, Bisphenols in which one methyl group is bonded to the central carbon, such as 1-bis(4-hydroxyphenyl)-1-(4-chlorophenyl)ethane, 1,1-bis(4-hydroxyphenyl)-1-(2-fluorophenyl)ethane, 1,1-bis(4-hydroxyphenyl)-1-(2-chlorophenyl)ethane, 1,1-bis(4-hydroxyphenyl)-1-tetrafluorophenylethane, and 1,1-bis(4-hydroxyphenyl)-1-tetrachlorophenylethane;
Bisphenols in which two methyl groups are bonded to the central carbon, such as 2,2-bis(3-methyl-4-hydroxyphenyl)propane (commonly known as bisphenol C), 2,2-bis(3,5-dimethyl-4-hydroxyphenyl)propane, 2,2-bis(3-ethyl-4-hydroxyphenyl)propane, 2,2-bis(3-isobutyl-4-hydroxyphenyl)propane, 2,2-bis(3-fluoro-4-hydroxyphenyl)propane, 2,2-bis(3,5-difluoro-4-hydroxyphenyl)propane, 2,2-bis(3-chloro-4-hydroxyphenyl)propane, and 2,2-bis(3,5-dichloro-4-hydroxyphenyl)propane;
Bisphenols which are diphenylmethane derivatives such as bis(4-hydroxyphenyl)-1,1-diphenylmethane, bis(3-methyl-4-hydroxyphenyl)-1,1-diphenylmethane, bis(3-t-butyl-4-hydroxyphenyl)-1,1-diphenylmethane, bis(3-phenyl-4-hydroxyphenyl)-1,1-diphenylmethane, and bis(3-chloro-4-hydroxyphenyl)-1,1-diphenylmethane;
bisphenols which are cyclohexane derivatives such as 1,1-bis(4-hydroxyphenyl)cyclohexane (commonly known as bisphenol Z), 1,1-bis(3-methyl-4-hydroxyphenyl)cyclohexane, 1,1-bis(3,5-dimethyl-4-hydroxyphenyl)cyclohexane, 1,1-bis(3-ethyl-4-hydroxyphenyl)cyclohexane, 1,1-bis(3-isobutyl-4-hydroxyphenyl)cyclohexane, 1,1-bis(3-fluoro-4-hydroxyphenyl)cyclohexane, 1,1-bis(3,5-difluoro-4-hydroxyphenyl)cyclohexane, 1,1-bis(3-chloro-4-hydroxyphenyl)cyclohexane, and 1,1-bis(3,5-dichloro-4-hydroxyphenyl)cyclohexane;
Bisphenols which are 3,3,5-trimethylcyclohexane derivatives such as 1,1-bis(4-hydroxyphenyl)-3,3,5-trimethylcyclohexane, 1,1-bis(3-methyl-4-hydroxyphenyl)-3,3,5-trimethylcyclohexane, 1,1-bis(3,5-dimethyl-4-hydroxyphenyl)-3,3,5-trimethylcyclohexane, 1,1-bis(3-ethyl-4-hydroxyphenyl)-3,3,5-trimethylcyclohexane, 1,1-bis(3-isobutyl-4-hydroxyphenyl)-3,3,5-trimethylcyclohexane, 1,1-bis(3-fluoro-4-hydroxyphenyl)-3,3,5-trimethylcyclohexane, and 1,1-bis(3,5-difluoro-4-hydroxyphenyl)-3,3,5-trimethylcyclohexane;
bisphenols which are fluorene derivatives such as 9,9-bis(4-hydroxyphenyl)fluorene, 9,9-bis(3-methyl-4-hydroxyphenyl)fluorene, 1,1-bis(3,5-dimethyl-4-hydroxyphenyl)fluorene, 9,9-bis(3-ethyl-4-hydroxyphenyl)fluorene, 9,9-bis(3-isobutyl-4-hydroxyphenyl)fluorene, 1,1-bis(3-fluoro-4-hydroxyphenyl)fluorene, and 9,9-bis(3,5-difluoro-4-hydroxyphenyl)fluorene;
Bisphenols which are cycloalkane derivatives such as 1,1-bis(4-hydroxyphenyl)-cyclopentane, 1,1-bis(4-hydroxyphenyl)cyclopentane, 1,1-bis(4-hydroxyphenyl)cyclooctane, 1,1-bis(4-hydroxyphenyl)cyclononane, and 1,1-bis(4-hydroxyphenyl)cyclodecane;
Biphenols in which aromatic rings are directly bonded, such as 4,4'-biphenol;
bisphenols which are sulfone derivatives such as bis(4-hydroxyphenyl)sulfone, bis(3-methyl-4-hydroxyphenyl)sulfone, bis(3,5-dimethyl-4-hydroxyphenyl)sulfone, bis(3-ethyl-4-hydroxyphenyl)sulfone, bis(3-isobutyl-4-hydroxyphenyl)sulfone, bis(3-fluoro-4-hydroxyphenyl)sulfone, and bis(3,5-difluoro-4-hydroxyphenyl)sulfone;
bisphenols having an ether bond, such as bis(4-hydroxyphenyl) ether, bis(3-methyl-4-hydroxyphenyl) ether, bis(3,5-dimethyl-4-hydroxyphenyl) ether, bis(3-ethyl-4-hydroxyphenyl) ether, bis(3-isobutyl-4-hydroxyphenyl) ether, bis(3-fluoro-4-hydroxyphenyl) ether, and bis(3,5-difluoro-4-hydroxyphenyl) ether;
bisphenols having a sulfide bond, such as bis(4-hydroxyphenyl)sulfide, bis(3-methyl-4-hydroxyphenyl)sulfide, bis(3,5-dimethyl-4-hydroxyphenyl)sulfide, bis(3-ethyl-4-hydroxyphenyl)sulfide, bis(3-isobutyl-4-hydroxyphenyl)sulfide, bis(3-fluoro-4-hydroxyphenyl)sulfide, and bis(3,5-difluoro-4-hydroxyphenyl)sulfide;
bisphenols which are sulfoxide derivatives such as bis(4-hydroxyphenyl)sulfoxide, bis(3-methyl-4-hydroxyphenyl)sulfoxide, bis(3,5-dimethyl-4-hydroxyphenyl)sulfoxide, bis(3-ethyl-4-hydroxyphenyl)sulfoxide, bis(3-isobutyl-4-hydroxyphenyl)sulfoxide, bis(3-fluoro-4-hydroxyphenyl)sulfoxide, and bis(3,5-difluoro-4-hydroxyphenyl)sulfoxide;
Bisphenols having an aliphatic ring containing a heteroatom, such as phenolphthalein;
Examples of the bisphenols having no carbon-hydrogen bond include bis(2,3,5,6-tetrafluoro-4-hydroxyphenyl)difluoromethane, 1,1-bis(2,3,5,6-tetrafluoro-4-hydroxyphenyl)perfluoroethane, and 2,2-bis(2,3,5,6-tetrafluoro-4-hydroxyphenyl)perfluoropropane.

Further examples include dihydroxybenzenes such as hydroquinone, resorcinol, catechol, and methylhydroquinone; and dihydroxynaphthalenes such as 1,5-dihydroxynaphthalene and 2,6-dihydroxynaphthalene.

The content of phenolic hydroxyl groups in the phenol compound (C5) relative to 1 mol of acid anhydride groups in the styrene-based elastomer (P1) is preferably in the range of 0.1 to 20 mol, more preferably in the range of 0.5 to 10 mol, and even more preferably in the range of 1 to 3 mol. By making the content of phenolic hydroxyl groups 0.1 mol or more relative to the acid anhydride groups in the styrene-based elastomer (P1), the crosslink density can be increased and the heat resistance, insulating properties, and adhesive properties can be improved. By making the content of epoxy groups 20 mol or less, the generation of new polar groups can be suppressed and the deterioration of the dielectric tangent can be suppressed.

Composition (I)-2 can contain a silane coupling agent and/or a thiol compound to the extent that the physical properties are not impaired. The effects are as described for composition (I)-1. In addition, suitable examples and suitable contents of the silane coupling agent and thiol compound are the same as those for composition (I)-1.

A filler can be further added to composition (I)-3 for the purposes of imparting flame retardancy, controlling the fluidity of the resin composition, improving the elastic modulus of the cured product, etc. The shape and preferred examples of the filler, the preferred range of average particle size and content, and the addition method, etc. are the same as those of composition (I)-1.

In addition to the essential components and the optional components described above, composition (I)-3 can further contain the compounds and additives exemplified in composition (I)-1, provided that the purpose is not impaired.

By using a semi-cured product of any of the thermosetting resin compositions (I)-1 to (I)-3, (II), and (III), it is possible to provide a highly reliable prepreg that has excellent dielectric properties and low warpage, and can effectively reduce the occurrence of cracks.

[Metal-clad laminate]
The metal-clad laminate according to this embodiment is a laminate including at least an insulating layer made of a cured product of a prepreg (hereinafter, also simply referred to as an insulating layer (cured product of a prepreg)) and a metal layer. The metal-clad laminate according to this embodiment can be obtained, for example, by laminating a metal layer and a prepreg, and then curing the prepreg by thermocompression bonding. A known method can be used for the thermocompression bonding method. One method involves hot pressing at a temperature of 120 to 200° C., a pressure of 0.5 to 10 MPa, and a heating time of 0.5 to 5 hours.

Examples of the laminated structure of the metal-clad laminate include a two-layer laminate of metal layer/insulating layer (cured prepreg), a laminate consisting of a multi-layer of metal layer/insulating layer (cured prepreg)/metal layer, or a multi-layer structure of metal layer/insulating layer (cured prepreg)/metal layer/insulating layer (cured prepreg)/metal layer, etc., alternately laminated. In addition, an insulating layer other than the insulating layer (cured prepreg) may be included in the laminate. For example, a laminate of metal layer/insulating layer (cured prepreg)/insulating layer (resin sheet), metal layer/insulating layer (cured prepreg)/insulating layer (resin sheet)/metal layer, metal layer/insulating layer (cured prepreg)/insulating layer (resin sheet)/metal layer, etc., multi-layer laminates can be exemplified. In addition, multiple prepregs can be stacked and cured to adjust the thickness of the insulating layer (cured prepreg). A conductive layer other than the metal layer may also be laminated. The resin sheet may contain a filler, etc.

When the characteristics of the base material used in the prepreg are anisotropic (for example, when the tensile strength is anisotropic), the overlapping direction of multiple prepregs can be adjusted to reinforce the strength. For example, two prepregs can be overlapped so that the anisotropic first direction is shifted by substantially 90°. In addition, for example, a prepreg laminate can be formed by stacking a nonwoven fabric prepreg and a woven fabric prepreg, a prepreg laminate can be formed by arbitrarily stacking prepregs made of the thermosetting resin compositions of compositions (I) to (III), or a laminate of the prepreg according to this embodiment and other prepregs can be used.

The material of the metal layer is not particularly limited, and copper, silver, aluminum, stainless steel, etc. can be used. Metal foil or vapor deposition film can be used. In the case of copper, electrolytic copper or rolled copper is preferably used. The metal layer may be a non-patterned layer or a patterned layer. The thickness of the metal layer can be, for example, 0.1 to 50 μm. It is preferably 1 to 35 μm, and more preferably 6 to 18 μm.

For example, a metal-clad laminate having a layer structure of metal layer/insulating layer (cured prepreg)/metal layer can be obtained by forming a circuit pattern on the metal layer formed on both main surfaces of the insulating layer (cured prepreg) to obtain a circuit board having a circuit pattern layer. Through holes, etc. may be formed in the insulating layer. A core board may be multi-layered by forming vias by overlapping an insulating layer (cured prepreg) and/or an insulating layer (resin sheet, etc.) on it by a build-up process. A circuit board can be obtained, for example, by forming the metal layer of the metal-clad laminate into a desired circuit pattern by a subtractive method, or by forming a desired circuit pattern on one or both sides of the insulating layer (cured prepreg) by an additive method.

[Printed wiring board]
The printed wiring board of this embodiment is manufactured using the prepreg or metal-clad laminate of this embodiment. The printed wiring board of this embodiment can be manufactured, for example, by forming a circuit on the surface of the metal-clad laminate of this embodiment. In addition, the conductor layer of the metal-clad laminate of this embodiment can be formed with wiring or a circuit by a normal etching method, and a plurality of laminates processed with wiring via the prepreg of this embodiment can be laminated and hot-pressed to form a multilayer structure. Thereafter, a multilayer printed wiring board can be manufactured through the formation of through holes or via holes by drilling or laser processing and the formation of interlayer wiring by plating or conductive paste. In addition, the printed wiring board can be suitably used by being mounted on an electronic device.

[Multilayer wiring board]
A multilayer wiring board is a board in which interlayer insulating layers and conductive layers on which circuit patterns are formed are alternately laminated on one or both sides of a core board. Examples of the core board include the above-mentioned circuit boards, glass epoxy boards, silicon boards, ceramic boards such as aluminum nitride boards, bismaleimide-triazine resin boards, etc.

The insulating layer of this embodiment (cured prepreg) can be used as the interlayer insulating layer. In addition to the insulating layer (cured prepreg), a cured resin sheet having low dielectric properties may be used. The interlayer insulating layer may be a laminate of an insulating layer (cured prepreg) and a resin sheet having low dielectric properties, alternately laminated with a conductive layer. Each interlayer insulating layer may have a different configuration.

For example, a multilayer wiring board is made by laminating prepreg on one or both sides of a core board, curing it to form an insulating layer made of the cured prepreg, then drilling or laser processing is used to create openings in this insulating layer (the cured prepreg), filling it with a conductive material to form vias, and laminating a circuit layer on top of this interlayer insulating layer. The process of laminating and curing more prepreg and forming vias is then repeated to form a multilayer circuit board.

By using the prepreg of this embodiment, a circuit board with excellent high-frequency characteristics can be provided. Therefore, it can be suitably used as a multilayer wiring board for communication by high-frequency signals. In addition, the multilayer wiring board can be suitably used by being mounted on electronic equipment.

The present invention will be described in more detail below with reference to examples, but the following examples are not intended to limit the scope of the invention. In the examples, "parts" and "%" represent "parts by mass" and "% by mass", respectively, and Mw means weight average molecular weight.

[Synthesis Example 1] <Synthesis Example of Styrene-Based Elastomer (P1)>
100g of styrene-based elastomer (P1) with a polymer block ratio of styrene:[ethylene/butylene]=15:85 (mass%) and a weight average molecular weight of 55,000 was dry-blended with 1.03g of maleic anhydride, 0.1g of benzoyl peroxide, and 0.6g of Irganox 1010 (BASF Japan, antioxidant), and further mixed and melt-kneaded using a 32mm twin-screw extruder with a vent to obtain a pellet-shaped sample. The temperatures of the twin-screw extruder during mixing and melt-kneading were 40°C at the bottom of the hopper, 80°C in the mixing zone, 170°C in the reaction zone, and 180°C at the die.
To 100 parts by mass of the obtained pellet-like sample, 85 parts by mass of acetone and 85 parts by mass of heptane were added, and the mixture was heated and stirred at 85°C for 2 hours in a pressure-resistant reactor. After completion of the operation, the pellets were collected using a wire net and vacuum-dried at 140°C and 0.1 Torr for 20 hours to obtain a styrene-butadiene block copolymer having an acid anhydride group. The molecular weight distribution was narrow, with a weight average molecular weight of 60,000, a total acid value of 11.2 mgCH ₃ ONa/g, and an acid anhydride value of 5.6 mgCH ₃ ONa/g.

The Mw of Synthesis Example 1 was measured using a Tosoh GPC (gel permeation chromatography) "HPC-8020". GPC is a liquid chromatography that separates and quantifies substances dissolved in a solvent (THF; tetrahydrofuran) based on the difference in their molecular size. The measurements in this invention were performed using two "LF-604" columns (Showa Denko: GPC column for rapid analysis: 6 mm ID x 150 mm size) connected in series, at a flow rate of 0.6 mL/min and a column temperature of 40°C, and the weight average molecular weight (Mw) was determined in polystyrene equivalent.

The total acid value of Synthesis Example 1 is expressed as the amount (mg) of sodium methoxide required to neutralize the acid anhydride group and carboxylic acid contained in 1 g of resin solid. Approximately 1 g of sample was precisely weighed and placed in a stoppered Erlenmeyer flask, and dissolved in 100 mL of cyclohexanone solvent. Phenolphthalein test solution was added as an indicator and held for 30 seconds. Then, titration was performed with 0.1 N sodium methoxide solution until the solution turned a light pink color. The acid value was calculated using the following formula (unit: mg CH ₃ ONa/g).
Acid value (mg CH ₃ ONa/g)=(5.412×a×F)/S
however,
S: Amount of sample collected (g)
a: Amount of 0.1N sodium methoxide solution consumed (mL)
F: Titer of 0.1N sodium methoxide solution

The acid anhydride value of Synthesis Example 1 was measured by precisely weighing about 1 g of sample into a stoppered Erlenmeyer flask, and adding 100 mL of 1,4-dioxane solvent to dissolve it. 10 mL of a mixed solution of octylamine, 1,4-dioxane, and water (mixing ratio by mass: 1.49/800/80) was added, which was greater than the amount of acid anhydride groups in the sample, and stirred for 15 minutes to react with the acid anhydride groups. The excess octylamine was then titrated with a mixed solution of 0.02 M perchloric acid and 1,4-dioxane. In addition, a blank measurement was also performed using 10 mL of a mixed solution of octylamine, 1,4-dioxane, and water (mixing ratio by mass: 1.49/800/80) to which no sample was added. The acid anhydride value was calculated using the following formula (unit: mg CH3ONa/g).
Acid anhydride value (mg CHONa/g) = 0.02 x (B - S) x F x 54.12/W
B: Blank titer (mL)
S: titer of sample (mL)
W: sample solid weight (g)
F: Potency of 0.02 mol/L perchloric acid

The ratio of the acid anhydride group and the ring-opened carboxylic acid in Synthesis Example 1 was determined by the following method.
Acid anhydride group: ring-opened carboxylic acid = acid anhydride value: (total acid value - acid anhydride value x 2)

[Synthesis Example 2] <Synthesis Example of Polyamide Resin (P2)>
A four-neck flask equipped with a stirrer, reflux condenser, nitrogen inlet tube, inlet tube, and thermometer was charged with 324.6 g of Pripol 1009 (manufactured by Croda Japan, C36 dimer acid, containing a compound having one C6 cyclic structure (acid value: 195 mg KOH/g) as a polybasic acid compound having 36 carbon atoms, 25.7 g (0.14 mol) of 5-hydroxyisophthalic acid as a polybasic acid compound having a phenolic hydroxyl group, 138.6 g of Wondamin HM (manufactured by New Japan Chemical, 4,4'-diaminodicyclohexylmethane), and 100 g of ion-exchanged water, and the mixture was stirred until the temperature of the generated heat became constant. After the temperature was stabilized, the temperature was raised to 110°C, After confirming the outflow of water, the temperature was raised to 120°C after 30 minutes, and then the dehydration reaction was continued while raising the temperature by 10°C every 30 minutes. When the temperature reached 230°C, the reaction was continued at that temperature for 3 hours, and the mixture was kept under a vacuum of about 2 kPa for 1 hour, and the temperature was lowered. Finally, an antioxidant was added to obtain polyamide (A-1) having a weight average molecular weight of 21200, an acid value of 10.6 mgKOH/g, an amine value of 0.3 mgKOH/g, a phenolic hydroxyl value of 16.2 mgKOH/g, and a glass transition temperature of 50°C. Incidentally, the monomer having a C20-60 hydrocarbon group was 41.4 mol% out of 100 mol% of the total monomers used in the reaction.

The phenolic hydroxyl value of Synthesis Example 2 is the amount of phenolic hydroxyl groups contained in 1 g of phenolic hydroxyl group-containing polyamide, expressed as the amount of potassium hydroxide (mg) required to neutralize the acetic acid bonded to the phenolic hydroxyl groups when the phenolic hydroxyl groups are acetylated. The phenolic hydroxyl value was measured in accordance with JIS K0070. In the present invention, when calculating the phenolic hydroxyl value of a polyamide containing phenolic hydroxyl groups of a terminal carboxylic acid, the calculation is performed taking into account the acid value, as shown in the following formula.

The phenolic hydroxyl value of Synthesis Example 2 was measured as follows.
Approximately 1 g of sample was precisely weighed and placed in a stoppered Erlenmeyer flask, and dissolved in 100 mL of cyclohexanone solvent. Exactly 5 mL of acetylating agent (a solution of 25 g of acetic anhydride dissolved in pyridine to a volume of 100 mL) was then added and stirred for approximately 1 hour. Phenolphthalein test solution was added as an indicator and allowed to stand for 30 seconds. After that, the solution was titrated with 0.5 N alcoholic potassium hydroxide solution until it turned a pale pink color.
The hydroxyl value was calculated according to the following formula (unit: mgKOH/g).
Hydroxyl value (mgKOH/g) = [{(b-a) x F x 28.05}/S] + D
however,
S: Amount of sample collected (g)
a: Amount of 0.5N alcoholic potassium hydroxide solution consumed (mL)
b: Amount of 0.5N alcoholic potassium hydroxide solution consumed in the blank experiment (mL)
F: Potency of 0.5N alcoholic potassium hydroxide solution D: Acid value (mgKOH/g)

The acid value of Synthesis Example 2 was determined by the following method.
Approximately 1 g of sample was precisely weighed and placed in a stoppered Erlenmeyer flask, and 100 mL of cyclohexanone solvent was added to dissolve it. Phenolphthalein test solution was added as an indicator and the solution was held for 30 seconds. Then, the solution was titrated with 0.1N alcoholic potassium hydroxide solution until it turned a light pink color. The acid value was calculated using the following formula (unit: mgKOH/g).
Acid value (mgKOH/g) = (5.611 x a x F) / S
however,
S: Amount of sample collected (g)
a: Amount of 0.1N alcoholic potassium hydroxide solution consumed (mL)
F: Potency of 0.1N alcoholic potassium hydroxide solution

The amine value of Synthesis Example 2 was determined by the following method.
Approximately 1 g of sample was precisely weighed and placed in a stoppered Erlenmeyer flask, and dissolved in 100 mL of cyclohexanone solvent. A few drops of indicator, which was prepared by mixing 0.20 g of Methyl Orange dissolved in 50 mL of distilled water and 0.28 g of Xylene Cyanol FF dissolved in 50 mL of methanol, were added to the sample and held for 30 seconds. The solution was then titrated with 0.1 N alcoholic hydrochloric acid until it turned blue-gray. The amine value was calculated using the following formula (unit: mg KOH/g).
Acid value (mgKOH/g) = (5.611 x a x F) / S
however,
S: Amount of sample collected (g)
a: consumption of 0.1N alcoholic hydrochloric acid solution (mL)
F: Potency of 0.1N alcoholic hydrochloric acid solution

The Mw of Synthesis Example 2 was determined by the following method.
The measurement of Mw was performed using a GPC (gel permeation chromatography) "GPC-101" manufactured by Showa Denko K.K. GPC is a liquid chromatography that separates and quantifies substances dissolved in a solvent (THF; tetrahydrofuran) based on the difference in their molecular size. The measurement in the present invention was performed using two "KF-805L" (manufactured by Showa Denko K.K.: GPC column: 8 mm ID x 300 mm size) connected in series as a column, under the conditions of a sample concentration of 1 wt%, a flow rate of 1.0 ml/min, a pressure of 3.8 MPa, and a column temperature of 40°C, and the weight average molecular weight (Mw) was determined in polystyrene equivalent. The data was analyzed using the manufacturer's built-in software to calculate the calibration curve, molecular weight, and peak area, and the mass average molecular weight was determined by analyzing the range of retention times from 17.9 to 30.0 minutes.

The glass transition temperature of the polyamide resin (P2) of Synthesis Example 2 was measured as follows.
For the polyamide resin (P2) from which the solvent had been dried and removed, about 5 mg of a sample was weighed into an aluminum standard container using a Mettler Toledo "DSC-1" and measured from -80 to 200°C under conditions of a temperature modulation amplitude of ±1°C, a temperature modulation period of 60 seconds, and a temperature rise rate of 2°C/min, and the glass transition temperature was determined from the differential thermal curve of the reversible component.

[Synthesis Example 3] <Synthesis Example of Polyurethane Resin (P3)>
A reaction vessel equipped with a stirrer, a thermometer, a reflux condenser, a dropping device, and a nitrogen inlet tube was charged with 352 parts of a diol having Mn=1002 obtained from adipic acid and 3-methyl-1,5-pentanediol, 32 parts of dimethylolbutanoic acid, 176 parts of isophorone diisocyanate, and 40 parts of toluene, and reacted for 3 hours at 90 ° C. under a nitrogen atmosphere. 300 parts of toluene was added to this to obtain a solution of a urethane prepolymer having an isocyanate group at the end. Next, 810 parts of the obtained urethane prepolymer solution was added to a mixture of 32 parts of isophorone diamine, 4 parts of di-n-butylamine, 342 parts of 2-propanol, and 576 parts of toluene, and reacted at 70 ° C. for 3 hours to obtain a solution of a polyurethane polyurea resin having Mw=35,000 and an acid value of 21 mgKOH/g. To this were added 144 parts of toluene and 72 parts of 2-propanol to obtain a polyurethane polyurea resin solution with a solid content of 50%.

The Tg of Synthesis Example 3 was measured by differential scanning calorimetry (Mettler Toledo's "DSC-1"). The Mw of Synthesis Example 3 was measured in the same manner as Synthesis Example 1. The acid value was measured by dissolving 1 g of thermosetting resin in 40 mL of methyl ethyl ketone and connecting a Kyoto Electronics Manufacturing Co., Ltd. automatic titrator "AT-510" with the same company's "APB-510-20B" as a burette. Potentiometric titration was performed using a 0.1 mol/L ethanolic KOH solution as the titration reagent, and the mg of KOH per 1 g of resin was calculated.

[Preparation of prepregs and metal clad laminates] (Examples 1 to 5 and Comparative Example 1)
The resin, curing agent, flame retardant, and methyl ethyl ketone as a dilution solvent were mixed in the blending ratio (solid parts by mass) shown in Table 1 to obtain a thermosetting resin composition with a solid content of 60 mass %.
Next, the thermosetting resin composition was applied to a glass fabric (length 530 mm, width 530 mm, thickness 0.18 mm, manufactured by Nitto Boseki Co., Ltd.) by impregnation, and the fabric was dried by heating at 100° C. for 10 minutes to obtain a prepreg having a resin content of 48% by mass. Four sheets of the prepreg were stacked, and 12 μm electrolytic copper foils were placed on the top and bottom of the prepreg. The prepreg was pressed at a pressure of 2.5 MPa and a temperature of 180° C. for 60 minutes to obtain a copper-clad laminate. The evaluation results of the obtained resin sheet are shown in Table 1.

Dielectric constant
Each of the resin compositions of Examples 1 to 5 and Comparative Example 1 was applied onto a release sheet and dried to obtain a sheet in which one side of the resin layer was covered with a release sheet. Thereafter, another set of sheets was obtained in the same manner, and the resin layer sides were overlapped to form release sheets on both sides of the resin layer, i.e., a resin composition sheet with double-sided release sheets was formed in which the overlapped resin layers were sandwiched between the release sheets.
Next, the release sheet on one side was removed, and the resultant was heat-cured for 1 hour at 180° C., after which the release sheet on the other side was removed to prepare a test piece for evaluation. The relative dielectric constant and dielectric loss tangent of this test piece were determined at a measurement temperature of 23° C. and a measurement frequency of 5 GHz by a cavity resonator method using a dielectric constant measuring device manufactured by A.E.T. Co., Ltd.
A: The dielectric constant is 3.2 or less.
B: The relative dielectric constant is greater than 3.2 and equal to or less than 3.5.
C: The dielectric constant is greater than 3.5 and equal to or less than 4.0.
D: The dielectric constant is greater than 4.0.

Dielectric loss tangent A: The dielectric loss tangent is 0.003 or less.
B: The dielectric tangent is greater than 0.003 and not greater than 0.005.
C...The dielectric tangent is greater than 0.005 and not more than 0.010.
D: Dielectric tangent is greater than 0.010.

Storage modulus Next, the above resin composition was applied to the release-treated surface of a peelable PET film using an applicator with a dry film thickness of 0.1 mm, and dried at 100 ° C. for 3 minutes to obtain a coated sheet. Thereafter, the other coated sheet prepared in the same manner was laminated with a roll laminator, and further heat-pressed at 170 ° C. and 2 MPa with a heat press machine to cure the resin composition on the coated sheet. Thereafter, the peelable PET film was peeled off, and the measurement sample was measured using a dynamic modulus measuring device DVA-200 (manufactured by IT Measurement and Control Co., Ltd.) under the conditions of a deformation mode of "tensile", a frequency of 10 Hz, a heating rate of 10 ° C. / min, and a measurement temperature range of 30 to 300 ° C., and the storage modulus and Tg at 25 ° C. were obtained.

Seam test (evaluation of flexibility)
The cracking test was a bending characteristic test with a radius of 15 mm. An evaluation board was prepared by etching the entire surface of the electrolytic copper foil of a copper-clad laminate with a length of 200 mm and a width of 50 mm. Then, this evaluation board was folded in half with a spacer of 30 mm thickness, and pressed from above and below with stainless steel mirror plates weighing 200 g to form a bent part with a radius of 15 mm. After 5 minutes, the evaluation board was returned to its original state, and the presence or absence of breaks and cracks in the bent part was visually confirmed. The evaluation criteria were as follows.
◯: No cracks were observed.
×: Cracks were observed.

The resins and the like used in the present examples and comparative examples are as follows.
(resin)
Resin 1: Cresol novolac epoxy resin, manufactured by DIC Corporation, N-680
Resin 2: resol type phenolic resin, manufactured by DIC Corporation, J-325
Resin 3: Epoxy resin, manufactured by Mitsubishi Chemical Corporation, JER1031S

(Hardening agent)
Curing agent 1: TETRAD-X, manufactured by Mitsubishi Gas Chemical Company, 4-functional polyfunctional glycidylamine compound Curing agent 2: 24A-100: biuret of hexamethylene diisocyanate (hereinafter abbreviated as HDI), manufactured by Asahi Kasei Chemical Company Curing agent 3: dicyandiamide, manufactured by Mitsubishi Chemical Company, DYCY7
Hardener 4: 2-phenylimidazole, manufactured by Shikoku Kasei Co., Ltd., 2PZ
Hardener 5: ZC700, Matsumoto Fine Chemical Co., Ltd., tetrafunctional Zr chelate compound

(Flame retardants)
Flame retardant 1: Aluminum phosphinate

Claims (5)

A substrate and a semi-cured product of a thermosetting resin composition impregnated in the substrate,
The thermosetting resin composition comprises:
A composition (I) containing a styrene-based elastomer (P1) having a carboxylic acid anhydride group, and any one of a polyisocyanate component (C1), an epoxy compound (C4) and a phenol compound (C5) which reacts with the anhydride group;
a composition (II) containing a polyamide resin (P2) having a phenolic hydroxyl group in a side group and a tri- or higher functional compound (C2) capable of reacting with the phenolic hydroxyl group, or a composition (III) containing a polyurethane resin (P3) having a carboxyl group and an epoxy compound (C3) capable of reacting with the carboxyl group,
the thermosetting resin composition is cured at 180° C. for 1 hour , and the cured product has a relative dielectric constant of 4.0 or less and a dielectric dissipation factor of 0.010 or less at a measurement temperature of 23° C. and a measurement frequency of 5 GHz, as measured by a cavity resonator method ;
The styrene-based elastomer (P1) is
a block copolymer having at least one of a structural unit derived from an olefin and a structural unit derived from a conjugated diene, and a structural unit derived from styrene; and the polyisocyanate component (C1) is an isocyanate group-containing compound having two or more isocyanates;
The polyamide resin (P2) is
The polyamide resin (P2) satisfies the following (i) and/or (ii), and further, the polyamide resin (P2) of (i) satisfies the following (iii) and (vi), and the polyamide resin (P2) of (ii) satisfies the following (iv) to (vi),
The compound (C2) satisfies the following (vii):
The polyurethane resin (P3) is a prepreg which is a polyurethane polyurea resin.
(i) Polyamide resin (P2) is a polyamide (A-1) in which a phenolic hydroxyl group and a hydrocarbon group having 20 to 60 carbon atoms and having a chain-like hydrocarbon group (but excluding the aromatic ring to which the phenolic hydroxyl group is bonded) are contained within the same polymer.
(ii) Polyamide resin (P2) is a polyamide (A-3) obtained by mixing polyamide (a-1) containing a phenolic hydroxyl group in a side group and polyamide (a-2) containing a hydrocarbon group having a chain-like hydrocarbon group and having 20 to 60 carbon atoms.
(iii) Monomers constituting the polyamide (A-1) include a monomer having a phenolic hydroxyl group and a monomer having a chain-like hydrocarbon group and a hydrocarbon group having 20 to 60 carbon atoms.
(iv) The polybasic acid monomer and/or polyamine monomer constituting the polyamide (a-1) contains a monomer having a phenolic hydroxyl group, and the polybasic acid monomer and the polyamine monomer do not contain a monomer having a chain-like hydrocarbon group having 20 to 60 carbon atoms.
(v) The polybasic acid monomer and/or the polyamine monomer constituting the polyamide (a-2) contain a monomer having a hydrocarbon group having 20 to 60 carbon atoms which has a chain-like hydrocarbon group, and the polybasic acid monomer and the polyamine monomer do not contain a monomer having a phenolic hydroxyl group.
(vi) At least a part of the monomers having a hydrocarbon group having 20 to 60 carbon atoms and a chain-like hydrocarbon group includes a compound having a cyclic structure having 5 to 10 carbon atoms.
(vii) The compound (C2) is at least one member selected from the group consisting of an epoxy group-containing compound, an isocyanate group-containing compound, a carbodiimide group-containing compound, a metal chelate, a metal alkoxide, and a metal acylate. A metal-clad laminate comprising an insulating layer made of a cured product of the prepreg according to claim 1 and a metal layer formed on one or both sides of the insulating layer. An insulating layer made of a cured product of the prepreg according to claim 1 ;
A circuit pattern formed on one or both sides of the insulating layer. A multilayer wiring board in which two or more interlayer insulating layers and two or more circuit pattern layers are laminated,
2. A multilayer wiring board, wherein at least one of said interlayer insulating layers is an insulating layer made of a cured product of the prepreg according to claim 1 . 5. An electronic device comprising the printed wiring board according to claim 3 or the multilayer wiring board according to claim 4 .