JP7590484B2 - Curable resin composition, prepreg and cured product thereof - Google Patents

Description

The present invention relates to a curable resin composition, a prepreg and a cured product thereof, and is suitable for use in electrical and electronic components such as semiconductor encapsulants, printed wiring boards and build-up laminates, lightweight, high-strength materials such as carbon fiber reinforced plastics and glass fiber reinforced plastics, and 3D printing applications.

In recent years, the required characteristics of laminates for mounting electric and electronic components have become more extensive and sophisticated due to the expansion of fields of use. Conventional semiconductor chips were mainly mounted on metal lead frames, but semiconductor chips with high processing power such as central processing units (hereinafter referred to as CPUs) are increasingly being mounted on laminates made of polymer materials.

The fifth generation communication system "5G", whose development is currently accelerating, is expected to further increase capacity and speed of communication. In 5G, the frequency used will become higher, but in order to realize high-speed communication using high frequencies, it is important to reduce transmission loss, and further low dielectric properties will be required for the board material. The transmission loss that occurs on the printed circuit board is due to conductor loss and dielectric loss. As described in Non-Patent Document 1, the conductor loss is proportional to the square root of the relative dielectric constant and the dielectric loss tangent of the dielectric, so it can be said that improving the dielectric loss tangent, which has a higher contribution rate than the relative dielectric constant, is effective in reducing transmission loss. Materials with low dielectric loss tangent include thermoplastic materials such as PTFE (polytetrafluoroethylene), LCP (liquid crystal polymer), and rubber materials, but they are poor in moldability compared to thermosetting resins. In addition, since rubber materials have a high linear expansion coefficient, when used for a board, cracks may occur due to the difference in linear expansion coefficient with IC chips, which have a low linear expansion coefficient, and the reliability of the product may be impaired. In light of this, there is a need to develop thermosetting resins with excellent low dielectric properties, or compositions that contain thermosetting resins.

In light of this background, the development of thermosetting resins with excellent low dielectric properties and compositions containing thermosetting resins is being considered. For example, Patent Document 1 proposes a composition containing a maleimide resin and a propenyl group-containing phenolic resin. However, on the other hand, since phenolic hydroxyl groups that do not participate in the reaction remain during the curing reaction, the electrical properties are not sufficient. Patent Document 2 discloses an allyl ether resin in which hydroxyl groups are substituted with allyl groups. However, it has been shown that Claisen rearrangement occurs at 190°C, and at 200°C, which is the molding temperature of a general substrate, phenolic hydroxyl groups that do not contribute to the curing reaction are generated, so the electrical properties are not satisfactory. Patent Document 3 proposes a composition having a monofunctional maleimide compound and an olefin-containing polymer with the aim of providing a resin composition that can obtain a cured product with low dielectric properties and high heat resistance, but the dielectric properties are not sufficient.

Signal loss factors in high-speed signal transmission on printed circuit boards (Mitsui Mining & Smelting Co., Ltd.) 29th Japan Institute of Electronics Packaging Spring Conference 16P1-17

Japanese Patent Application Publication No. 04-359911 International Publication No. 2016/002704 Patent No. 7190649

The present invention has been made in consideration of these circumstances, and aims to provide a curable resin composition and a cured product thereof that are excellent in high heat resistance, high elastic modulus, low linear expansion coefficient, and low dielectric tangent.

That is, the present invention relates to the following [1] to [9]. Note that in this application, "(Numerical value 1) to (Numerical value 2)" indicates that the upper and lower limits are included.
[1]
A curable resin composition comprising a compound represented by the following formula (1) and a polymer containing a structural unit represented by the following formula (2).

(In formula (1), each of the multiple R's exists independently and represents a hydrogen atom, a hydrocarbon group having 1 to 10 carbon atoms, or a halogenated alkyl group having 1 to 10 carbon atoms. p and r represent integers from 0 to 4, q represents an integer from 0 to 3, and n represents the average number of repetitions, with 1≦n≦20.)

[2]
The curable resin composition according to the above item [1], wherein the polymer containing the structural unit represented by the formula (2) further contains a structural unit represented by the following formula (3):

(In formula (3), each R represents a hydrogen atom or an alkyl group having 1 to 10 carbon atoms.)
[3]
The curable resin composition according to the above item [1] or [2] further contains a polyphenylene ether compound having an unsaturated double bond, and/or a hydrogenated product of a block copolymer comprising a block unit of a polymer composed of a styrene-based monomer and a block unit of a polymer composed of a conjugated diene compound.
[4]
The curable resin composition according to the above item [3], wherein the polyphenylene ether compound having an unsaturated double bond is represented by the following formula (4) or the following formula (5):

(In formula (4), n is the average number of repetitions, and 1<n<10.)

(In formula (5), n is the average number of repetitions, and 1<n<10.)
[5]
The curable resin composition according to the above item [3] or [4], wherein the hydrogenated product of the block copolymer is a compound represented by the following formula (6):

(In formula (6), l, m, and n are the average values of the repeating numbers and represent real numbers from 1 to 10,000. The order of the repeating units bracketed by l, m, and n is not limited, and the bonding style may be any of alternating, block, and random.)
[6]
The curable resin composition according to any one of the above items [1] to [5], further comprising at least one selected from the group consisting of a maleimide compound, a compound having an ethylenically unsaturated bond, a cyanate ester resin, polybutadiene and modified products thereof, polystyrene and modified products thereof, and polyethylene and modified products thereof.
[7]
A prepreg comprising a sheet-shaped fiber substrate and the curable resin composition according to any one of items [1] to [6] above.
[8]
A cured product obtained by curing the curable resin composition according to any one of the above items [1] to [6].
[9]
A cured product obtained by curing the prepreg described in the preceding item [7].

The present invention makes it possible to provide a curable resin composition that has excellent heat resistance, high elastic modulus, low linear expansion coefficient, and low dielectric tangent, and a cured product thereof.

1 shows a GPC chart of Synthesis Example 1. 2 shows a GPC chart of Synthesis Example 2.

[Compound represented by formula (1)]
The curable resin composition of the present embodiment contains a compound represented by the following formula (1).

In formula (1), each of the multiple R's exists independently and represents a hydrogen atom, a hydrocarbon group having 1 to 10 carbon atoms, or a halogenated alkyl group having 1 to 10 carbon atoms, preferably a hydrogen atom or a hydrocarbon group having 1 to 10 carbon atoms, and more preferably a hydrogen atom or a hydrocarbon group having 1 to 3 carbon atoms. Hydrocarbons having 10 or fewer carbon atoms are less likely to undergo molecular vibration when exposed to high frequency waves, and therefore have particularly excellent electrical properties.

In formula (1), p and r are integers of 0 to 4, preferably 0 to 2. q is an integer of 0 to 3, preferably 0 to 2. n is the average number of repetitions, and is preferably 1≦n≦20, more preferably 1.1≦n≦20, particularly preferably 1.1≦n≦10, and most preferably 1.1≦n≦5. The value of n can be calculated from the number average molecular weight (Mn) of the compound represented by formula (1) measured by gel permeation chromatography (GPC). The number average molecular weight is preferably 200 or more and less than 5000, more preferably 300 or more and less than 3000, and particularly preferably 400 or more and less than 2000. If the weight average molecular weight is less than 5000, purification by washing with water is easy, and if it is 200 or more, the target compound does not volatilize in the solvent distillation step.

The number of olefins contained in the compound represented by formula (1) was examined in accordance with the iodine value measurement method in JIS K0070. First, 0.096 g of the compound described in formula (1) was weighed out. 4 ml of dichloromethane was added to dissolve the compound. 10 ml of Wiess's reagent was added and the mixture was left to stand in the dark for 30 minutes. 8 ml of potassium iodide solution (100 g/L) and 40 ml of water were weighed and added to the sample. Titration was performed using a 0.1 mol/L aqueous sodium thiosulfate solution and a starch solution as an indicator. The end point of the starch reagent was when the color disappeared.

The iodine value of the compound represented by formula (1) calculated by this method is preferably 100 to 200, more preferably 110 to 190, and particularly preferably 120 to 180. If the iodine value is greater than 200, the number of olefins is large, and curing may proceed too far during prepreg production, making it difficult to obtain the desired molded product. On the other hand, if the iodine value is less than 100, the number of olefins is small, and the heat resistance of the cured product obtained when the composition is cured may be poor. If the iodine value is within the above-mentioned range, a cured product that does not lose moldability or heat resistance can be obtained.

The amount of the compound represented by formula (1) added is preferably 1 to 99 parts by mass, more preferably 3 to 80 parts by mass, even more preferably 3 to 60 parts by mass, and particularly preferably 5 to 40 parts by mass, per 100 parts by mass of the total amount of the curable resin composition. If it is more than this range, heat resistance may be poor. If it is less than this range, excellent dielectric properties cannot be achieved. If it is within the above range, excellent heat resistance and dielectric properties are achieved.

The compound represented by the formula (1) is derived from the compound represented by the following formula (1-1):

In formula (1-1), the values and preferred ranges of R, p, r, q, and n are the same as those in formula (1). X represents a halogen atom, and from the viewpoints of reactivity and stability of the raw materials, a bromine atom or a chlorine atom is preferred, with a bromine atom being particularly preferred.

The compound represented by the formula (1) can be obtained, for example, by a method of subjecting the compound represented by the formula (1-1) to a dehydrohalogenation reaction in a solvent in the presence of a basic catalyst. Examples of the solvent to be used include, but are not limited to, water-insoluble solvents such as aromatic solvents such as toluene and xylene, aliphatic solvents such as cyclohexane and n-hexane, ethers such as diethyl ether and diisopropyl ether, ester solvents such as ethyl acetate and butyl acetate, and ketone solvents such as methyl isobutyl ketone and cyclopentanone. Two or more of these may be used in combination. In addition to the water-insoluble solvent, aprotic polar solvents can also be used in combination. Examples include dimethyl sulfone, dimethyl sulfoxide, dimethylformamide, dimethylacetamide, 1,3-dimethyl-2-imidazolidinone, and N-methylpyrrolidone, and two or more of these may be used in combination. When using an aprotic polar solvent, it is preferable to use one having a higher boiling point than the water-insoluble solvent to be used in combination. The catalyst is not particularly limited, but examples include basic catalysts such as sodium hydroxide, potassium hydroxide, and potassium carbonate. Since it is difficult to completely proceed with the dehydrohalogenation reaction, the aprotic polar solvent may be used in large excess relative to the substrate, and the dehydrohalogenation reaction may be repeated two or more times. For example, the dehydrohalogenation reaction of the compound represented by the formula (2) may be carried out in an organic solvent in the presence of a base catalyst, and the resulting solution may be washed with water and then returned to the reaction vessel, and the base catalyst may be added to carry out the reaction again. This can increase the progress of the dehydrohalogenation reaction. That is, it is possible to reduce the amount of residual halogen contained in the target compound. The amount of residual halogen is preferably 1 to 10,000 ppm in the target product, more preferably 1 to 1,000 ppm, and even more preferably 1 to 750 ppm. If the amount of residual halogen contained in the compound represented by the formula (1) is large, molecular vibration occurs when exposed to high frequency, which has a negative effect on electrical properties, particularly dielectric loss tangent. Furthermore, if the amount of residual halogen is large, the risk of problems such as metal corrosion and ion migration increases in environmental tests such as HAST tests (High Accelerated Stress Tests), so the above halogen content is preferable.

The method for producing the compound represented by the formula (1-1) is not particularly limited, but for example, a compound having a (2-bromoethyl)benzene structure may be reacted with a bishalogenated methylaryl compound (or a bishydroxymethylaryl compound, etc.) under an acid catalyst such as hydrochloric acid, sulfonic acid, or activated clay, or a compound having a (2-bromoethyl)benzene structure may be reacted with a bishydroxymethylaryl compound under an acid catalyst such as hydrochloric acid, sulfonic acid, or activated clay. When sulfonic acid or the like is used as a catalyst, the reaction may be neutralized with an alkali metal such as sodium hydroxide or potassium hydroxide before proceeding to the extraction step. For the extraction step, an aromatic hydrocarbon solvent such as toluene or xylene may be used alone, or a non-aromatic hydrocarbon such as cyclohexane or toluene may be used in combination. After extraction, the organic layer is washed with water until the wastewater becomes neutral, and the solvent and the excess compound having a (2-bromoethyl)benzene structure are distilled off using an evaporator or the like to obtain a compound having at least two or more 2-bromoethylbenzene structures in the target molecule.

Examples of compounds having a (2-bromoethyl)benzene structure include, but are not limited to, (2-bromoethyl)benzene, 1-(2-bromoethyl)-2-methylbenzene, 1-(2-bromoethyl)-3-methylbenzene, 1-(2-bromoethyl)-4-methylbenzene, 1-(2-bromoethyl)-2,3-dimethylbenzene, 1-(2-bromoethyl)-2,4-dimethylbenzene, 1-(2-bromoethyl)-2,5-dimethylbenzene, and 1-(2-bromoethyl)-2,6-dimethylbenzene. These may be used alone or in combination of two or more. A large number of carbon atoms improves solvent solubility, but reduces heat resistance, so it is preferably unsubstituted or substituted with an alkyl group having 1 to 3 carbon atoms, more preferably unsubstituted or substituted with an alkyl group having 1 to 2 carbon atoms, and most preferably unsubstituted or substituted with a methyl group.

Examples of bishalogenated methylaryl compounds include, but are not limited to, o-xylylene difluoride, m-xylylene difluoride, p-xylylene difluoride, o-xylylene dichloride, m-xylylene dichloride, p-xylylene dichloride, o-xylylene dibromide, m-xylylene dibromide, p-xylylene dibromide, o-xylylene diiodide, m-xylylene diiodide, p-xylylene diiodide, etc. These may be used alone or in combination of two or more. From the viewpoint of the reactivity of the raw materials during synthesis, chloride-based compounds, bromide-based compounds, and iodide-based compounds are preferred, and chloride-based compounds and bromide-based compounds are more preferred.

Examples of bishydroxymethylaryl compounds include, but are not limited to, o-benzenedimethanol, m-benzenedimethanol, and p-benzenedimethanol. These may be used alone or in combination of two or more. The amount of these compounds used is preferably 0.05 to 0.8 parts by mass, and more preferably 0.1 to 0.6 parts by mass, per part by mass of the compound having a (2-bromoethyl)benzene structure.

When reacting a compound having a (2-bromoethyl)benzene structure with a halogenated methylaryl compound, etc., a catalyst may be used as needed, such as hydrochloric acid, phosphoric acid, sulfuric acid, formic acid, p-toluenesulfonic acid, methanesulfonic acid, Lewis acids such as aluminum chloride and zinc chloride, activated clay, acidic clay, white carbon, zeolite, solid acids such as silica alumina, acidic ion exchange resins, etc. These may be used alone or in combination of two or more. The amount of catalyst used is 0.05 to 0.8 moles, preferably 0.1 to 0.7 moles, per mole of the compound having a (2-bromoethyl)benzene structure used. If the amount of catalyst used is too large, the viscosity of the reaction solution may be too high, making stirring difficult, and if the amount is too small, the reaction may proceed slowly. The reaction may be carried out using an organic solvent such as hexane, cyclohexane, octane, toluene, or xylene, as necessary, or may be carried out without a solvent. For example, after adding an acidic catalyst to a mixed solution of a compound having a (2-bromoethyl)benzene structure, a halogenated methylaryl compound, and a solvent, if the catalyst contains water, the water is removed from the system by azeotropy. Then, the reaction is carried out at 40 to 180°C, preferably 50 to 170°C, for 0.5 to 20 hours. After the reaction is completed, the acidic catalyst may be neutralized with an alkaline aqueous solution, but it is also possible to proceed to the water washing step without neutralization. For the water washing step, a water-insoluble organic solvent is added to the oil layer and water washing is repeated until the wastewater becomes neutral.

The softening point of the compound represented by formula (1-1) is preferably 80°C or lower, more preferably 70°C or lower. If the softening point is 80°C or lower, the viscosity when induced into the compound represented by formula (1) is low. This makes it easier to ensure fluidity, does not impair the impregnation into glass cloth or carbon fiber, and facilitates B-stage formation, such as prepreg formation. If the viscosity is reduced by increasing the dilution solvent, there is a possibility that the resin will not adhere sufficiently to the fibrous material during the impregnation process.

[Polymer containing a structural unit represented by formula (2)]
The curable resin composition of the present embodiment further contains a polymer including a structural unit represented by the following formula (2).

The number of olefins in the polymer containing the structural unit represented by the above formula (2) is calculated by the above-mentioned iodine value measurement method. The iodine value is preferably 50 to 200, more preferably 60 to 180, and particularly preferably 70 to 160. If the iodine value is greater than the above range, the reactivity may be too high, and problems such as a decrease in the storage stability of the curable resin composition or a decrease in the fluidity of the curable resin composition may occur. The decrease in fluidity may cause molding defects such as the generation of voids during molding, which may impair the reliability of the wiring board. On the other hand, if the iodine value is smaller than the above range, the heat resistance of the cured product may deteriorate. Therefore, if the iodine value is within the above range, the heat resistance and moldability will be excellent.

The weight-average molecular weight (Mw) of the polymer containing the structural unit represented by the above formula (2) is preferably 10,000 to 50,000, more preferably 15,000 to 45,000, and particularly preferably 20,000 to 40,000. If it is smaller than the above range, the polymer may become liquid, and the prepreg surface may become sticky during prepreg production. On the other hand, if it is larger than the above range, the impregnation of the varnish into the glass cloth during prepreg production is poor, and workability deteriorates. In addition, the flowability deteriorates when multi-layering and molding, and moldability deteriorates. If it is within the above range, workability and moldability are excellent.

The amount of the polymer containing the structural unit represented by formula (2) added is preferably 1 to 99 parts by mass, more preferably 3 to 80 parts by mass, even more preferably 3 to 60 parts by mass, and particularly preferably 5 to 40 parts by mass, per 100 parts by mass of the total amount of the curable resin composition. If it is more than the above range, the low dielectric properties may deteriorate, and if it is less than the above range, the heat resistance may be poor. By being within the above range, the heat resistance and dielectric properties are excellent.

The polymer containing the structural unit represented by the above formula (2) preferably further contains a structural unit represented by the following formula (3).

(In formula (3), each R represents a hydrogen atom or an alkyl group having 1 to 10 carbon atoms.)

Examples of the structural unit represented by the above formula (3) include the following formulas (3-a) to (3-e):

The structural unit represented by the above formula (3) is preferably the above formula (3-a), (3-b), or (3-c), and more preferably (3-a) or (3-c). These may contain only one type, or two or more types.

[Polyphenylene Ether Compound Having Unsaturated Double Bond]
The curable resin composition of the present embodiment may contain a polyphenylene ether compound having an unsaturated double bond. Examples of the unsaturated double bond include a (meth)acrylic group, a styrene group, an allyl group, a vinyl group, and a methallyl group. A (meth)acrylic group, a styrene group, and a vinyl group are preferred, a (meth)acrylic group and a styrene group are more preferred, and a styrene group is particularly preferred. Commercially available polyphenylene ether compounds having an unsaturated double bond include SA-9000-111 (manufactured by Sabic, a polyphenylene ether compound having a methacrylic group) represented by the following formula (5) and OPE-2St 1200 and OPE-2St 2200 (manufactured by Mitsubishi Gas Chemical Co., Ltd., a polyphenylene ether compound having a styrene group) represented by the following formula (4). In particular, a compound represented by the following formula (4) is preferred from the viewpoint of reactivity and dielectric properties.

(In formula (4), n is the average number of repetitions, and 1<n<10.)

(In formula (5), n is the average number of repetitions, and 1<n<10.)

The number average molecular weight (Mn) of the polyphenylene ether compound having an unsaturated double bond is preferably 500 to 5000, more preferably 750 to 4000, and even more preferably 1000 to 3000. If the molecular weight is 500 or more, the heat resistance of the cured product is improved. If the molecular weight is 5000 or less, the melt viscosity is low, sufficient fluidity can be obtained, and moldability is good. In addition, since the reactivity is improved, the curing time can be shortened and the heat resistance of the cured product is also improved. Specifically, the number average molecular weight can be measured using gel permeation chromatography, etc.

Polyphenylene ether compounds having unsaturated double bonds can be made radically polymerizable by reacting the polyphenylene ether compounds with compounds having unsaturated double bonds, such as methacryl chloride, acrylic chloride, and chloromethylstyrene.

The polyphenylene ether compound having an unsaturated double bond may be obtained by a polymerization reaction, or may be obtained by a redistribution reaction of a high molecular weight polyphenylene ether compound having a weight average molecular weight of 10,000 to 30,000. The redistribution reaction may be performed, for example, by heating a high molecular weight polyphenylene ether compound in a solvent such as toluene in the presence of a phenolic compound and a radical initiator to cause the redistribution reaction. The polyphenylene ether compound obtained by the redistribution reaction in this way is preferable because it has hydroxyl groups derived from the phenolic compound that contribute to hardening at both ends of the molecular chain, and therefore can maintain even higher heat resistance. The polyphenylene ether compound obtained by the polymerization reaction is also preferable because it exhibits excellent fluidity.

In the case of polyphenylene ether compounds obtained by a polymerization reaction, the molecular weight of the polyphenylene ether compound having an unsaturated double bond can be adjusted by adjusting the polymerization conditions, etc. In the case of polyphenylene ether compounds obtained by a redistribution reaction, the molecular weight can be adjusted by adjusting the conditions of the redistribution reaction, etc. More specifically, it is possible to adjust the amount of the phenolic compound used in the redistribution reaction. In other words, the greater the amount of the phenolic compound, the lower the molecular weight of the obtained component polyphenylene ether compound.

The amount of the polyphenylene ether compound having an unsaturated double bond added is preferably 1 to 80 parts by mass, more preferably 5 to 75 parts by mass, and particularly preferably 10 to 70 parts by mass, per 100 parts by mass of the total amount of the curable resin composition. If it is more than this range, the dielectric properties are not sufficient. If it is less than this range, the heat resistance may be poor. If it is within the above range, the heat resistance and dielectric properties are excellent.

[Hydrogenated block copolymer consisting of block units of polymer made of styrene-based monomer and block units of polymer made of conjugated diene compound]
The curable resin composition of the present embodiment may contain a hydrogenated product of a block copolymer composed of a block unit of a polymer composed of a styrene-based monomer and a block unit of a polymer composed of a conjugated diene compound. The block unit of the polymer composed of a styrene-based monomer is, for example, represented by the following formula (a).

R ₁ and R ₂ are each preferably independently a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, more preferably a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, particularly preferably a hydrogen atom or a methyl group, and most preferably a hydrogen atom. If the number of carbon atoms is greater than 5, the dielectric tangent may deteriorate due to molecular vibration, and the heat resistance may decrease. p is preferably 1 to 5, more preferably 1 to 3, and particularly preferably 1. q is the average number of repetitions and represents a real number of 1 to 10,000, and q is preferably 1 to 7,500, more preferably 1 to 5,000, and even more preferably 1 to 3,000.

The block units of the polymer consisting of a conjugated diene compound are obtained by polymerizing at least one diene compound selected from linear conjugated dienes such as butadiene, isoprene, farnesene, 2,3-dimethyl-1,3-butadiene, and 1,3-pentadiene. From the viewpoint of availability of raw materials, among the linear conjugated dienes, butadiene, isoprene, and farnesene are preferred, butadiene and isoprene are more preferred, and isoprene is most preferred.

Any known material may be used as the hydrogenated product of a block copolymer consisting of block units of a polymer made of a styrene-based monomer and block units of a polymer made of a conjugated diene compound, but a compound represented by the following formula (6) is preferred.

In formula (6), l, m, and n are the average number of repeats and represent real numbers from 1 to 10,000, preferably from 1 to 9,000, and more preferably from 1 to 8,000. The order of the repeat units bounded by l, m, and n is not limited, and the bonding style may be alternating, block, or random. The most preferred embodiment is when a hydrogenated styrene-ethylene propylene-styrene block copolymer (SEPS) is used.

The compound represented by formula (6) does not have a polar group, nor does it have an unsaturated bond derived from an aliphatic hydrocarbon. Therefore, even if it is exposed to temperatures of 125°C or higher, which is the temperature at which semiconductor operation is guaranteed, for a long period of time, it is not easily oxidized, and oxygen, which is a polar group, is not easily incorporated into the skeleton. Therefore, deterioration of the dielectric properties after high-temperature storage tests can be reduced, and it also has excellent low water absorption properties.

The amount of hydrogenated block copolymer consisting of block units of a polymer made of a styrene-based monomer and block units of a polymer made of a conjugated diene compound added is preferably 1 to 40 parts by mass, more preferably 5 to 35 parts by mass, and particularly preferably 10 to 30 parts by mass, per 100 parts by mass of the total amount of the curable resin composition. If it is more than this range, the viscosity of the varnish may be too high, and the impregnation into the glass cloth may be poor. If it is less than this range, the dielectric properties may be deteriorated. If it is within the above range, the impregnation and dielectric properties are excellent.

The curable resin composition of this embodiment can be further mixed with the following materials:

[Polymerization initiator]
The curable resin composition of the present embodiment can also improve the curability by adding a polymerization initiator. The polymerization initiator is a compound capable of polymerizing an olefin functional group such as an ethylenically unsaturated bond, and examples of such a polymerization initiator include an olefin metathesis polymerization initiator, an anionic polymerization initiator, a cationic polymerization initiator, and a radical polymerization initiator. Among these, it is preferable to use a radical polymerization initiator having curability and moderate stability. The radical polymerization initiator is a compound that generates radicals by irradiation with ultraviolet light or visible light or by heating, and initiates a chain polymerization reaction. Examples of radical polymerization initiators that can be used include organic peroxides, azo compounds, and benzopinacoles, and it is preferable to use an organic peroxide because it has little effect on curing temperature control, outgassing suppression, and electrical properties of decomposition products.

Examples of the organic peroxides include ketone peroxides such as methyl ethyl ketone peroxide and acetylacetone peroxide, diacyl peroxides such as benzoyl peroxide, dialkyl peroxides such as dicumyl peroxide and 1,3-bis-(t-butylperoxyisopropyl)-benzene, peroxyketals such as t-butylperoxybenzoate and 1,1-di-t-butylperoxycyclohexane, α-cumylperoxyneodecanoate, t-butylperoxyneodecanoate, t-butylperoxypivalate, 1,1,3,3-tetramethylbutylperoxy-2-ethylhexanoate, t-amylperoxy-2-ethylhex ... Examples of the peroxycarbonate include, but are not limited to, alkyl peresters such as di-2-ethylhexyl peroxydicarbonate, bis(4-t-butylcyclohexyl)peroxydicarbonate, t-butylperoxyisopropyl carbonate, 1,6-bis(t-butylperoxycarbonyloxy)hexane, t-butyl hydroperoxide, cumene hydroperoxide, t-butyl peroxyoctoate, lauroyl peroxide, etc. These may be used alone or in combination. Among the above organic peroxides, ketone peroxides, diacyl peroxides, hydroperoxides, dialkyl peroxides, peroxyketals, alkyl peresters, percarbonates, etc. are preferred, with dialkyl peroxides being more preferred.

Examples of the azo compounds include, but are not limited to, azobisisobutyronitrile, 4,4'-azobis(4-cyanovaleric acid), 2,2'-azobis(2,4-dimethylvaleronitrile), etc. Furthermore, these may be used alone or in combination.

The amount of polymerization initiator added is preferably 0.01 to 5 parts by mass, and particularly preferably 0.01 to 3 parts by mass, per 100 parts by mass of the curable resin composition. If the amount of polymerization initiator used is less than 0.01 parts by mass, there is a risk that the molecular weight will not be sufficiently extended during the polymerization reaction, and if it is more than 5 parts by mass, there is a risk that the dielectric properties such as the dielectric constant and dielectric loss tangent will be impaired.

[Curing accelerator]
The curable resin composition of the present embodiment can also have improved curability by adding a curing accelerator. As the curing accelerator, an anionic curing accelerator that accelerates the curing reaction by generating anions upon irradiation with ultraviolet light or visible light or heating, or a cationic curing accelerator that accelerates the curing reaction by generating cations upon irradiation with ultraviolet light or visible light or heating, is preferred.

Examples of anionic curing accelerators include imidazoles such as 2-methylimidazole, 2-ethylimidazole, and 2-ethyl-4-methylimidazole; trialkylamines such as triethylamine and tributylamine; 4-dimethylaminopyridine, benzyldimethylamine, 2,4,6-tris(dimethylaminomethyl)phenol, and 1,8-diazabicyclo(5,4,0)-undecene; of which 4-dimethylaminopyridine and 1,8-diazabicyclo(5,4,0)-undecene are preferred. Other examples include phosphines such as triphenylphosphine; quaternary ammonium salts such as tetrabutylammonium salts, triisopropylmethylammonium salts, trimethyldecanylammonium salts, cetyltrimethylammonium salts, and hexadecyltrimethylammonium hydroxide, but are not limited to these. These may be used alone or in combination.

Examples of cationic curing accelerators include quaternary phosphonium salts such as triphenylbenzylphosphonium salt, triphenylethylphosphonium salt, and tetrabutylphosphonium salt (the counter ion of the quaternary salt may be a halogen, an organic acid ion, a hydroxide ion, or the like, but is not particularly specified, and organic acid ions and hydroxide ions are particularly preferred), transition metal compounds (transition metal salts) such as tin octylate, zinc carboxylate (zinc 2-ethylhexanoate, zinc stearate, zinc behenate, zinc myristate), and zinc phosphate ester (zinc octylphosphate, zinc stearylphosphate), but are not limited to these. These may be used alone or in combination.

The amount of the curing accelerator used is 0.01 to 5.0 parts by mass per 100 parts by mass of the curable resin composition, as needed.

[Inorganic filler]
The curable resin composition of the present embodiment may contain an inorganic filler. Examples of inorganic fillers include, but are not limited to, powders such as fused silica, crystalline silica, porous silica, alumina, zircon, calcium silicate, calcium carbonate, quartz powder, silicon carbide, silicon nitride, boron nitride, zirconia, aluminum nitride, graphite, forsterite, steatite, spinel, mullite, titania, talc, clay, iron oxide asbestos, and glass powder, or inorganic fillers obtained by making these into a spherical or crushed shape. In addition, these may be used alone or in combination.

When obtaining a curable resin composition for semiconductor encapsulation, the inorganic filler is used in an amount of preferably 80 to 92 parts by mass, and more preferably 83 to 90 parts by mass, per 100 parts by mass of the curable resin composition. When obtaining a curable resin composition for an interlayer insulating layer forming material, or a substrate material such as a copper-clad laminate, prepreg, or RCC, the inorganic filler is used in an amount of preferably 5 to 80 parts by mass, and more preferably 10 to 60 parts by mass, per 100 parts by mass of the curable resin composition.

[Polymerization inhibitor]
The curable resin composition of the present embodiment may contain a polymerization inhibitor. By containing a polymerization inhibitor, storage stability is improved and the reaction initiation temperature can be controlled. By controlling the reaction initiation temperature, it becomes easy to ensure fluidity, impregnation into glass cloth and the like is not impaired, and B-stage such as prepreg formation is facilitated. If the polymerization reaction proceeds too much during prepreg formation, problems such as difficulty in lamination during the lamination process are likely to occur.

The polymerization inhibitor may be added when synthesizing the compound represented by formula (1) or after synthesis. The amount of the polymerization inhibitor used is 0.008 to 1 part by weight, preferably 0.01 to 0.5 parts by weight, per 100 parts by weight of the compound represented by formula (1).

Examples of polymerization inhibitors include phenol-based, sulfur-based, phosphorus-based, hindered amine-based, nitroso-based, and nitroxyl radical-based. A single type of polymerization inhibitor may be used, or multiple types may be used in combination. Of these, in this embodiment, phenol-based, hindered amine-based, nitroso-based, and nitroxyl radical-based inhibitors are preferred.

Examples of the phenol-based polymerization inhibitors include monophenols such as 2,6-di-t-butyl-p-cresol, butylated hydroxyanisole, 2,6-di-t-butyl-p-ethylphenol, stearyl-β-(3,5-di-t-butyl-4-hydroxyphenyl)propionate, isooctyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate, 2,4-bis-(n-octylthio)-6-(4-hydroxy-3,5-di-t-butylanilino)-1,3,5-triazine, and 2,4-bis[(octylthio)methyl]-o-cresol; -butylphenol), 2,2'-methylenebis(4-ethyl-6-t-butylphenol), 4,4'-thiobis(3-methyl-6-t-butylphenol), 4,4'-butylidenebis(3-methyl-6-t-butylphenol), triethylene glycol-bis[3-(3-t-butyl-5-methyl-4-hydroxyphenyl)propionate], 1,6-hexanediol-bis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate], N,N'-hexamethylenebis(3,5-di-t-butyl-4-hydroxy-hydrocinnamamide), 2,2-thio-diethylenebis[3-(3,5-di bisphenols such as bis(3,5-di-t-butyl-4-hydroxybenzylsulfonate ethyl)calcium, 1,1,3-tris(2-methyl-4-hydroxy-5-t-butylphenyl)butane, 1,3,5-trimethyl-2,4,6-tris(3,5-di-t-butyl-4-hydroxyphenyl)propionate, 3,5-di-t-butyl-4-hydroxybenzylphosphonate-diethyl ester, 3,9-bis[1,1-dimethyl-2-{β-(3-t-butyl-4-hydroxy-5-methylphenyl)propionyloxy}ethyl]2,4,8,10-tetraoxaspiro[5,5]undecane, bis(3,5-di-t-butyl-4-hydroxybenzylsulfonate ethyl)calcium, 1,1,3-tris(2-methyl-4-hydroxy-5-t-butylphenyl)butane, 1,3,5-trimethyl-2,4,6-tris(3,5-di-t -butyl-4-hydroxybenzyl)benzene, tetrakis-[methylene-3-(3',5'-di-t-butyl-4'-hydroxyphenyl)propionate]methane, bis[3,3'-bis-(4'-hydroxy-3'-t-butylphenyl)butyric acid]glycol ester, tris-(3,5-di-t-butyl-4-hydroxybenzyl)-isocyanurate, 1,3,5-tris(3',5'-di-t-butyl-4'-hydroxybenzyl)-S-triazine-2,4,6-(1H,3H,5H)trione, tocopherol and other polymeric phenols are included, but are not limited to these.

Examples of the sulfur-based polymerization inhibitor include, but are not limited to, dilauryl-3,3'-thiodipropionate, dimyristyl-3,3'-thiodipropionate, and distearyl-3,3'-thiodipropionate.

Examples of the phosphorus-based polymerization inhibitors include triphenyl phosphite, diphenyl isodecyl phosphite, phenyl diisodecyl phosphite, tris(nonylphenyl) phosphite, diisodecyl pentaerythritol phosphite, tris(2,4-di-t-butylphenyl) phosphite, cyclic neopentane tetrayl bis(octadecyl) phosphite, cyclic neopentane tetrayl bis(2,4-di-t-butylphenyl) phosphite, cyclic neopentane tetrayl bis(2,4-di-t-butyl-4-methylphenyl) phosphite, bis[2-t -butyl-6-methyl-4-{2-(octadecyloxycarbonyl)ethyl}phenyl]hydrogen phosphite and other phosphites, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, 10-(3,5-di-t-butyl-4-hydroxybenzyl)-9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, 10-decyloxy-9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide and other oxaphosphaphenanthrene oxides, but are not limited to these.

Examples of the hindered amine polymerization inhibitors include ADK STAB LA-40MP, ADK STAB LA-40Si, ADK STAB LA-402AF, ADK STAB LA-87, DEKA STAB LA-82, DEKA STAB LA-81, ADK STAB LA-77Y, ADK STAB LA-77G, ADK STAB LA-72, ADK STAB LA-68, ADK STAB LA-63P, ADK STAB LA-57, ADK STAB LA -52, Chimassorb 2020FDL, Chimassorb 944FDL, Chimassorb 944LD, Tinuvin 622SF, Tinuvin PA144, Tinuvin 765, Tinuvin 770DF, Tinuvin XT55FB, Tinuvin 111FDL, Tinuvin 783FDL, Tinuvin 791FB, etc., but are not limited to these.

Examples of the nitroso-based polymerization inhibitor include, but are not limited to, p-nitrosophenol, N-nitrosodiphenylamine, ammonium salt of N-nitrosophenylhydroxyamine, (cupferron), etc. Among these, the ammonium salt of N-nitrosophenylhydroxyamine (cupferron) is preferred.

Examples of the nitroxyl radical polymerization inhibitor include, but are not limited to, di-tert-butyl nitroxide, 2,2,6,6-tetramethylpiperidine-1-oxyl, 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl, 4-oxo-2,2,6,6-tetramethylpiperidine-1-oxyl, 4-amino-2,2,6,6-tetramethylpiperidine-1-oxyl, 4-methoxy-2,2,6,6-tetramethylpiperidine-1-oxyl, 4-acetoxy-2,2,6,6-tetramethylpiperidine-1-oxyl, and 4-benzoyloxy-2,2,6,6-tetramethylpiperidine-1-oxyl.

[Flame retardant]
The curable resin composition of the present embodiment may contain a flame retardant. Examples of the flame retardant include halogen-based flame retardants, inorganic flame retardants (antimony compounds, metal hydroxides, nitrogen compounds, boron compounds, etc.), and phosphorus-based flame retardants. From the viewpoint of achieving halogen-free flame retardancy, phosphorus-based flame retardants are preferred.
The phosphorus-based flame retardant may be of either a reactive type or an additive type. Specific examples include phosphoric acid esters such as trimethyl phosphate, triethyl phosphate, tricresyl phosphate, trixylyleneyl phosphate, cresyl diphenyl phosphate, cresyl-2,6-dixylyleneyl phosphate, 1,3-phenylene bis(dixylyleneyl phosphate), 1,4-phenylene bis(dixylyleneyl phosphate), and 4,4'-biphenyl(dixylyleneyl phosphate), phosphanes such as 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide and 10(2,5-dihydroxyphenyl)-10H-9-oxa-10-phosphaphenanthrene-10-oxide, phosphorus-containing epoxy compounds obtained by reacting epoxy resins with active hydrogen of the phosphanes, red phosphorus, and the like, but are not limited thereto. In addition, these may be used alone or in combination. Of the above-listed substances, phosphates, phosphanes, or phosphorus-containing epoxy compounds are preferred, with 1,3-phenylenebis(dixylilenyl phosphate), 1,4-phenylenebis(dixylilenyl phosphate), 4,4'-biphenyl(dixylilenyl phosphate) or phosphorus-containing epoxy compounds being particularly preferred.

The content of the flame retardant is preferably in the range of 0.1 to 0.6 parts by mass per 100 parts by mass of the curable resin composition. If it is less than 0.1 part by mass, the flame retardancy may be insufficient, and if it is more than 0.6 parts by mass, it may have a negative effect on the moisture absorption and dielectric properties of the cured product.

[Light stabilizer]
The curable resin composition of the present embodiment may contain a light stabilizer. As the light stabilizer, a hindered amine light stabilizer, in particular HALS, etc., is preferable. Examples of HALS include reaction products of dibutylamine, 1,3,5-triazine, N,N'-bis(2,2,6,6-tetramethyl-4-piperidyl-1,6-hexamethylenediamine and N-(2,2,6,6-tetramethyl-4-piperidyl)butylamine, reaction products of dimethyl succinate-1-(2-hydroxyethyl)-4-hydroxy-2,2,6,6-tetramethylpiperidine, poly[{6-(1,1,3,3-tetramethylbutyl)amino-1,3,5-triazine-2,4-diyl}{(2,2,6,6-tetramethyl-4-piperidyl)imino}hexamethylene{(2,2,6,6-tetramethyl-4-piperidyl)imino}], bis(1,2 ,2,6,6-pentamethyl-4-piperidyl)[[3,5-bis(1,1-dimethylethyl)-4-hydroxyphenyl]methyl]butyl malonate, bis(2,2,6,6-tetramethyl-4-piperidyl)sebacate, bis(1,2,2,6,6-pentamethyl-4-piperidyl)sebacate, bis(1-octyloxy-2,2,6,6-tetramethyl-4-piperidyl)sebacate, 2-(3,5-di-t-butyl-4-hydroxybenzyl)-2-n-butylmalonate bis(1,2,2,6,6-pentamethyl-4-piperidyl), and the like, but are not limited thereto. These may be used alone or in combination.

The content of the light stabilizer is preferably in the range of 0.001 to 0.1 parts by mass per 100 parts by mass of the curable resin composition. If it is less than 0.001 parts by mass, it may be insufficient to exhibit the light stabilizing effect, and if it is more than 0.1 parts by mass, it may have a negative effect on the moisture absorption and dielectric properties of the cured product.

[Binder resin]
The curable resin composition of the present embodiment may use a binder resin. Examples of the binder resin include, but are not limited to, butyral resins, acetal resins, acrylic resins, epoxy-nylon resins, NBR-phenol resins, epoxy-NBR resins, and silicone resins. These may be used alone or in combination.

The amount of binder resin used is preferably within a range that does not impair the flame retardancy and heat resistance of the cured product, and is preferably 0.05 to 50 parts by mass, and more preferably 0.05 to 20 parts by mass, per 100 parts by mass of the curable resin composition, as needed.

[Additives]
The curable resin composition of the present embodiment may contain additives, such as modified acrylonitrile copolymers, polyethylene, fluororesins, silicone gels, silicone oils, surface treatment agents for fillers such as silane coupling agents, release agents, and colorants such as carbon black, phthalocyanine blue, and phthalocyanine green.

The amount of additive is preferably 1,000 parts by mass or less, and more preferably 700 parts by mass or less, per 100 parts by mass of the curable resin composition.

The curable resin composition of the present embodiment may further include epoxy resins, active ester compounds, phenolic resins, polyphenylene ether compounds having no unsaturated double bonds, amine resins, compounds having ethylenically unsaturated bonds, isocyanate resins, polyamide resins, maleimide compounds, cyanate ester resins, polyimide resins, polybutadiene and modified products thereof, polystyrene and modified products thereof, polyethylene and modified products thereof, etc., which may be used alone or in combination. Among these compounds, from the perspective of the balance of heat resistance, adhesion, and dielectric properties, it is preferable to contain maleimide compounds, polyphenylene ether compounds having no unsaturated double bonds, amine resins, compounds having ethylenically unsaturated bonds, isocyanate resins, polyamide resins, compounds having ethylenically unsaturated bonds, cyanate ester resins, polybutadiene and modified products thereof, polystyrene and modified products thereof, and polyethylene and modified products thereof. By containing these compounds, the brittleness of the cured product can be improved and adhesion to metals can be improved, and cracks in the package during solder reflow and reliability tests such as thermal cycles can be suppressed. Unless otherwise specified, the total amount of the above compounds used is preferably 10 times by mass or less, more preferably 5 times by mass or less, and particularly preferably 3 times by mass or less, relative to the compound represented by formula (1). The preferred lower limit is 0.1 times by mass or more, more preferably 0.25 times by mass or more, and even more preferably 0.5 times by mass or more. By being within the above range, it is possible to take advantage of the low dielectric properties of the compound represented by formula (1) while adding the effects of each compound added. The following examples of these components can be used.

[Epoxy resin]
Preferred examples of the epoxy resin include, but are not limited to, the following. The epoxy resin may be liquid or solid, and may be used alone or in combination.

Examples of liquid epoxy resins include bisphenol A type epoxy resins, bisphenol F type epoxy resins, bisphenol AF type epoxy resins, naphthalene type epoxy resins, glycidyl ester type epoxy resins, glycidyl amine type epoxy resins, phenol novolac type epoxy resins, alicyclic epoxy resins having an ester skeleton, cyclohexane type epoxy resins, cyclohexane dimethanol type epoxy resins, glycidyl amine type epoxy resins, and epoxy resins having a butadiene structure. Specific examples include "RE310S", "RE410S" (all manufactured by Nippon Kayaku Co., Ltd., bisphenol A type epoxy resin), "RE303S", "RE304S", "RE403S", "RE404S" (all manufactured by Nippon Kayaku Co., Ltd., bisphenol F type epoxy resin), "HP4032", "HP4032D", "HP4032SS" (all manufactured by DIC Corporation, naphthalene type epoxy resin), "828US", "jER828EL", "825", "828EL" (all manufactured by Mitsubishi Chemical Corporation, bisphenol A type epoxy resin), "jE807", "1750" (all manufactured by Mitsubishi Chemical Corporation, bisphenol F type epoxy resin), "jER152" (manufactured by Mitsubishi Chemical Corporation, phenol Novolac type epoxy resin), "630", "630LSD" (all manufactured by Mitsubishi Chemical Corporation, glycidylamine type epoxy resin), "ZX1059" (manufactured by Nippon Steel & Sumitomo Metal Chemical Co., Ltd., a mixture of bisphenol A type epoxy resin and bisphenol F type epoxy resin), "EX-721" (manufactured by Nagase ChemteX Corporation, glycidyl ester type epoxy resin), "Celloxide 2021P" (manufactured by Daicel Corporation, alicyclic epoxy resin having an ester skeleton), "PB-3600" (manufactured by Daicel Corporation, epoxy resin having a butadiene structure), "ZX1658", "ZX1658GS" (all manufactured by Nippon Steel & Sumitomo Metal Chemical Co., Ltd., liquid 1,4-glycidylcyclohexane type epoxy resin), etc. may be used. These may be used alone or in combination of two or more.

Examples of solid epoxy resins include bixylenol type epoxy resins, naphthalene type epoxy resins, naphthalene type tetrafunctional epoxy resins, cresol novolac type epoxy resins, dicyclopentadiene type epoxy resins, trisphenol type epoxy resins, naphthol type epoxy resins, biphenyl type epoxy resins, naphthylene ether type epoxy resins, anthracene type epoxy resins, bisphenol A type epoxy resins, bisphenol AF type epoxy resins, and tetraphenylethane type epoxy resins. Examples of the solid epoxy resins include naphthol type epoxy resins, bisphenol AF type epoxy resins, naphthalene type epoxy resins, and biphenyl type epoxy resins. Specific examples include "HP4032H" (manufactured by DIC Corporation, naphthalene type epoxy resin), "HP-4700", and "HP-4710" (all manufactured by DIC Corporation, naphthalene type tetrafunctional epoxy resin), "N-690" (manufactured by DIC Corporation, cresol novolac type epoxy resin), "N-695" (manufactured by DIC Corporation, cresol novolac type epoxy resin), "HP-7200" (manufactured by DIC Corporation, dicyclopentadiene type epoxy resin), "HP-7200", "HP-7200HH", and "HP-7200H" (all manufactured by DIC Corporation, dicyclopentadiene type epoxy resin). epoxy resin), "EXA-7311", "EXA-7311-G3", "EXA-7311-G4", "EXA-7311-G4S", "HP-6000" (all manufactured by DIC Corporation, naphthylene ether type epoxy resin), "EPPN-502H" (manufactured by Nippon Kayaku Co., Ltd., trisphenol type epoxy resin), "NC-7000L", "NC-7300" (all manufactured by Nippon Kayaku Co., Ltd., naphthol-cresol novolac type epoxy resin), "NC-3000H", "NC-3000", "NC-3000L", "NC-3100" (all manufactured by Nippon Kayaku Co., Ltd., biphenyl ether type epoxy resin), arylalkyl type epoxy resin), "XD-1000-2L", "XD-1000-L", "XD-1000-H", "XD-1000-H" (all manufactured by Nippon Kayaku Co., Ltd., dicyclopentadiene type epoxy resin), "ESN475V" (manufactured by Nippon Steel & Sumikin Chemical Co., Ltd., naphthol type epoxy resin), "ESN485" (manufactured by Nippon Steel & Sumikin Chemical Co., Ltd., naphthol novolac type epoxy resin), "YX-4000H", "YX-4000", "YL6121" (all manufactured by Mitsubishi Chemical Corporation, biphenyl type epoxy resin), "YX-4000HK" (manufactured by Mitsubishi Chemical Corporation, bixyl lenol type epoxy resin), "YX-8800" (manufactured by Mitsubishi Chemical Corporation, anthracene type epoxy resin), "PG-100", "CG-500" (manufactured by Osaka Gas Chemicals Co., Ltd., fluorene type epoxy resin), "YL-7760" (manufactured by Mitsubishi Chemical Corporation, bisphenol AF type epoxy resin), "YL-7800" (manufactured by Mitsubishi Chemical Corporation, fluorene type epoxy resin), "jER1010" (manufactured by Mitsubishi Chemical Corporation, solid bisphenol A type epoxy resin), "jER1031S" (manufactured by Mitsubishi Chemical Corporation, tetraphenylethane type epoxy resin), etc. These may be used alone or in combination of two or more.

[Active ester compound]
The active ester compound refers to a compound that contains at least one ester bond in the structure and has an aliphatic chain, an aliphatic ring, or an aromatic ring bonded to both sides of the ester bond. Examples of the active ester compound include compounds having two or more highly reactive ester groups in one molecule, such as phenol esters, thiophenol esters, N-hydroxyamine esters, and esters of heterocyclic hydroxy compounds, and are obtained by a condensation reaction between at least one compound of a carboxylic acid compound, an acid chloride, or a thiocarboxylic acid compound and at least one compound of a hydroxy compound or a thiol compound. In particular, from the viewpoint of improving heat resistance, it is preferable to obtain it from a carboxylic acid compound or an acid chloride and a hydroxy compound, and the hydroxy compound is preferably a phenol compound or a naphthol compound. The active ester compound may be used alone or in combination of two or more types.

Examples of the carboxylic acid compound include benzoic acid, acetic acid, succinic acid, maleic acid, itaconic acid, phthalic acid, isophthalic acid, terephthalic acid, and pyromellitic acid.

Examples of the acid chlorides include acetyl chloride, acrylic acid chloride, methacrylic acid chloride, malonyl chloride, succinic acid dichloride, diglycolyl chloride, glutaric acid dichloride, suberic acid dichloride, sebacic acid dichloride, adipic acid dichloride, dodecane dioyl dichloride, azelaic acid chloride, 2,5-furan dicarbonyl dichloride, phthaloyl chloride, isophthaloyl chloride, terephthaloyl chloride, trimesic acid chloride, bis(4-chlorocarbonylphenyl) ether, 4,4'-diphenyl dicarbonyl chloride, and 4,4'-azodibenzoyl dichloride.

Examples of the phenol compounds and naphthol compounds include hydroquinone, resorcin, bisphenol A, bisphenol F, bisphenol S, phenolphthaline, methylated bisphenol A, methylated bisphenol F, methylated bisphenol S, phenol, o-cresol, m-cresol, p-cresol, catechol, α-naphthol, β-naphthol, 1,5-dihydroxynaphthalene, 1,6-dihydroxynaphthalene, 2,6-dihydroxynaphthalene, dihydroxybenzophenone, trihydroxybenzophenone, tetrahydroxybenzophenone, phloroglucin, benzenetriol, dicyclopentadiene-type diphenol compounds, phenol novolac, and phenol resins described below. Here, "dicyclopentadiene-type diphenol compounds" refer to diphenol compounds obtained by condensing one molecule of dicyclopentadiene with two molecules of phenol.

Specific examples of preferred active ester compounds include active ester compounds containing a dicyclopentadiene-type diphenol structure, active ester compounds containing a naphthalene structure, active ester compounds containing an acetylated product of phenol novolac, active ester compounds containing a benzoylated product of phenol novolac, the compounds described in Example 2 of WO 2020/095829, and the compounds disclosed in WO 2020/059625. Among these, active ester compounds containing a naphthalene structure and active ester compounds containing a dicyclopentadiene-type diphenol structure are more preferred. The dicyclopentadiene-type diphenol structure refers to a divalent structural unit consisting of phenylene-dicyclopentylene-phenylene.

Commercially available active ester compounds include, for example, active ester compounds containing a dicyclopentadiene-type diphenol structure such as "EXB9451", "EXB9460", "EXB9460S", "HPC-8000-65T", "HPC-8000H-65TM", "EXB-8000L-65TM", and "EXB-8150-65T" (manufactured by DIC Corporation), active ester compounds containing a naphthalene structure such as "EXB9416-70BK" (manufactured by DIC Corporation), and phenol novolac. Examples of active ester compounds containing acetylated phenol novolac include "DC808" (manufactured by Mitsubishi Chemical Corporation), active ester compounds containing benzoylated phenol novolac include "YLH1026", "YLH1030", and "YLH1048" (manufactured by Mitsubishi Chemical Corporation), active ester curing agent that is an acetylated phenol novolac, and "EXB-9050L-62M" (manufactured by DIC Corporation) as a phosphorus atom-containing active ester curing agent.

Regarding the compounding ratio of the active ester compound and the epoxy resin, the ratio (α/β) of the active ester equivalent (α) to the epoxy equivalent (β) is preferably 0.5 to 1.5, more preferably 0.8 to 1.2, and even more preferably 0.90 to 1.10. Outside the above range, there is a risk that excess epoxy groups or active ester groups will remain in the system, which may cause deterioration of characteristics in high-temperature storage tests (e.g., 150°C, 1000 hours) and long-term reliability tests under high-temperature and high-humidity conditions (e.g., temperature: 85°C, humidity: 85%).

[Phenol resin]
A phenolic resin is a compound having two or more phenolic hydroxyl groups in a molecule. Examples of the phenolic resin include, but are not limited to, a reaction product of a phenol with an aldehyde, a reaction product of a phenol with a diene compound, a reaction product of a phenol with a ketone, a reaction product of a phenol with a substituted biphenyl, a reaction product of a phenol with a substituted phenyl, a reaction product of a bisphenol with an aldehyde, and the like. These may be used alone or in combination.
Specific examples of the above-mentioned raw materials are given below, but the raw materials are not limited thereto.
<Phenols>
Phenol, alkyl-substituted phenol, aromatic-substituted phenol, hydroquinone, resorcin, naphthol, alkyl-substituted naphthol, dihydroxybenzene, alkyl-substituted dihydroxybenzene, dihydroxynaphthalene, etc.
<Aldehydes>
Formaldehyde, acetaldehyde, alkyl aldehyde, benzaldehyde, alkyl-substituted benzaldehyde, hydroxybenzaldehyde, naphthaldehyde, glutaraldehyde, phthalaldehyde, crotonaldehyde, cinnamaldehyde, furfural, and the like.
<Diene Compound>
Dicyclopentadiene, terpenes, vinylcyclohexene, norbornadiene, vinylnorbornene, tetrahydroindene, divinylbenzene, divinylbiphenyl, diisopropenylbiphenyl, butadiene, isoprene, and the like.
<Ketones>
Acetone, methyl ethyl ketone, methyl isobutyl ketone, acetophenone, benzophenone, fluorenone, etc.
<Substituted biphenyls>
4,4'-bis(chloromethyl)-1,1'-biphenyl, 4,4'-bis(methoxymethyl)-1,1'-biphenyl, 4,4'-bis(hydroxymethyl)-1,1'-biphenyl, and the like.
<Substituted phenyls>
1,4-bis(chloromethyl)benzene, 1,4-bis(methoxymethyl)benzene, 1,4-bis(hydroxymethyl)benzene and the like.

[Polyphenylene ether compound having no unsaturated double bonds]
The polyphenylene ether compound having no unsaturated double bond means a polyphenylene ether compound other than the polyphenylene ether compound having the unsaturated double bond. The number average molecular weight (Mn) of the polyphenylene ether compound having no unsaturated double bond is preferably 500 to 5000, more preferably 2000 to 5000, and more preferably 2000 to 4000. If the molecular weight is less than 500, the heat resistance of the cured product tends to be insufficient. If the molecular weight is more than 5000, the melt viscosity increases and sufficient fluidity cannot be obtained, which tends to lead to molding defects. In addition, the reactivity decreases, the curing reaction takes a long time, and the amount of unreacted material that is not incorporated into the curing system increases, which tends to decrease the glass transition temperature of the cured product and decrease the heat resistance of the cured product.
If the number average molecular weight of the polyphenylene ether compound is 500 to 5000, it is possible to exhibit excellent heat resistance, moldability, etc. while maintaining excellent dielectric properties. The number average molecular weight here can be specifically measured using gel permeation chromatography, etc.

The polyphenylene ether compound having no unsaturated double bonds may be obtained by a polymerization reaction or may be obtained by a redistribution reaction of a high molecular weight polyphenylene ether compound having a number average molecular weight of about 10,000 to 30,000. The polyphenylene ether compound obtained by the redistribution reaction may be obtained, for example, by heating a high molecular weight polyphenylene ether compound in a solvent such as toluene in the presence of a phenolic compound and a radical initiator to cause a redistribution reaction. The polyphenylene ether compound obtained by the redistribution reaction in this way has hydroxyl groups derived from the phenolic compound that contribute to hardening at both ends of the molecular chain, and is therefore preferable in that it can maintain even higher heat resistance, and that functional groups can be introduced at both ends of the molecular chain even after modification with a compound having an ethylenically unsaturated bond. In addition, the polyphenylene ether compound having no unsaturated double bonds obtained by the polymerization reaction is preferable in that it exhibits excellent fluidity.

In the case of a polyphenylene ether compound obtained by a polymerization reaction, the molecular weight of the polyphenylene ether compound having no unsaturated double bonds can be adjusted by adjusting the polymerization conditions. In the case of a polyphenylene ether compound having no unsaturated double bonds obtained by a redistribution reaction, the molecular weight of the polyphenylene ether compound having no unsaturated double bonds can be adjusted by adjusting the conditions of the redistribution reaction. More specifically, it is possible to adjust the amount of the phenolic compound used in the redistribution reaction. That is, the greater the amount of the phenolic compound, the lower the molecular weight of the polyphenylene ether compound obtained. In this case, poly(2,6-dimethyl-1,4-phenylene ether) or the like can be used as a high molecular weight polyphenylene ether compound that undergoes the redistribution reaction. In addition, the phenolic compound used in the redistribution reaction is not particularly limited, but a polyfunctional phenolic compound having two or more phenolic hydroxyl groups in the molecule, such as bisphenol A, phenol novolac, cresol novolac, etc., is preferably used. These may be used alone or in combination of two or more.

[Amine resin]
The amine resin is a compound having two or more amino groups in the molecule. Examples of the amine resin include diaminodiphenylmethane, diaminodiphenylsulfone, isophoronediamine, naphthalenediamine, aniline novolak (a reaction product of aniline and formalin), N-methylaniline novolak (a reaction product of N-methylaniline and formalin), orthoethylaniline novolak (a reaction product of orthoethylaniline and formalin), a reaction product of 2-methylaniline and formalin, a reaction product of 2,6-diisopropylaniline and formalin, a reaction product of 2,6-diethylaniline and formalin, a reaction product of 2-ethyl-6-ethylaniline and formalin, a reaction product of 2,6-dimethylaniline and formalin, and a reaction product obtained by reacting aniline and xylylene chloride. Examples of the aniline resin include, but are not limited to, the aniline resin disclosed in Japanese Patent No. 6429862, a reaction product of aniline and a substituted biphenyl (4,4'-bis(chloromethyl)-1,1'-biphenyl and 4,4'-bis(methoxymethyl)-1,1'-biphenyl, etc.), a reaction product of aniline and a substituted phenyl (1,4-bis(chloromethyl)benzene, 1,4-bis(methoxymethyl)benzene and 1,4-bis(hydroxymethyl)benzene, etc.), 4,4'-(1,3-phenylenediisopropylidene)bisaniline, 4,4'-(1,4-phenylenediisopropylidene)bisaniline, a reaction product of aniline and diisopropenylbenzene, dimer diamine, etc. Furthermore, these may be used alone or in combination.

[Compound containing an ethylenically unsaturated bond]
The compound containing an ethylenically unsaturated bond is a compound having one or more ethylenically unsaturated bonds in the molecule that can be polymerized by heat or light, regardless of whether a polymerization initiator is used or not.
Examples of the compound containing an ethylenically unsaturated bond include, but are not limited to, a reaction product of the phenol resin with an ethylenically unsaturated bond-containing halogen-based compound (chloromethylstyrene, allyl chloride, methallyl chloride, acrylic acid chloride, methacrylic acid chloride, etc.), a reaction product of an ethylenically unsaturated bond-containing phenol (2-allylphenol, 2-propenylphenol, 4-allylphenol, 4-propenylphenol, eugenol, isoeugenol, etc.) with a halogen-based compound (1,4-bis(chloromethyl)benzene, 4,4'-bis(chloromethyl)biphenyl, 4,4'-difluorobenzophenone, 4,4'-dichlorobenzophenone, 4,4'-dibromobenzophenone, cyanuric chloride, etc.), a reaction product of an epoxy resin or alcohol with a (meth)acrylic acid (acrylic acid, methacrylic acid, etc.), and an acid-modified product thereof. In addition, these may be used alone or in combination.

[Isocyanate resin]
An isocyanate resin is a compound having two or more isocyanate groups in the molecule. Examples of the isocyanate resin include aromatic diisocyanates such as p-phenylene diisocyanate, m-phenylene diisocyanate, p-xylylene diisocyanate, m-xylylene diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 4,4'-diphenylmethane diisocyanate, and naphthalene diisocyanate; aliphatic or alicyclic diisocyanates such as isophorone diisocyanate, hexamethylene diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, hydrogenated xylene diisocyanate, norbornene diisocyanate, and lysine diisocyanate; polyisocyanates such as one or more biuret forms of isocyanate monomers or isocyanate forms obtained by trimerizing the diisocyanate compounds; and polyisocyanates obtained by a urethanization reaction between the isocyanate compounds and polyol compounds, but are not limited thereto. These may be used alone or in combination.

[Polyamide resin]
Examples of polyamide resins include reaction products of one or more of diamines, diisocyanates, and oxazolines with dicarboxylic acids, reaction products of diamines with acid chlorides, and ring-opening polymers of lactam compounds. These may be used alone or in combination.
Specific examples of the above-mentioned raw materials are given below, but the raw materials are not limited thereto.
<Diamine>
Ethylenediamine, trimethylenediamine, tetramethylenediamine, pentamethylenediamine, hexamethylenediamine, heptamethylenediamine, octamethylenediamine, nonamethylenediamine, decanediamine, undecanediamine, dodecanediamine, tridecanediamine, tetradecanediamine, pentadecanediamine, hexadecanediamine, heptadecanediamine, octadecanediamine, nonadecanediamine, eicosanediamine, 2-methyl-1,5-diaminopentane, 2-methyl diamino-1,8-diaminooctane, dimer diamine, cyclohexane diamine, bis-(4-aminocyclohexyl)methane, bis(3-methyl-4-aminocyclohexyl)methane, xylylene diamine, norbornane diamine, isophorone diamine, bisaminomethyltricyclodecane, phenylenediamine, diethyltoluenediamine, naphthalenediamine, diaminodiphenylmethane, bis(4-amino-3,5-dimethylphenyl)methane, bis(4-amino-3,5-diethylphenyl)methane , 4,4'-methylenebis-o-toluidine, 4,4'-methylenebis-o-ethylaniline, 4,4'-methylenebis-2-ethyl-6-methylaniline, 4,4'-methylenebis-2,6-diisopropylaniline, 4,4-ethylenedianiline, diaminodiphenyl sulfone, diaminodiphenyl ether, 1,3-bis(3-aminophenoxy)benzene, 1,3-bis(4-aminophenoxy)benzene, 4,4-bis(4-aminophenoxy)biphenyl, 2,2-bis[4-(4-amino bis[4-(4-aminophenoxy)phenyl]propane, bis[4-(4-aminophenoxy)phenyl]sulfone, 2,2-bis(3-amino-4-hydroxyphenyl)propane, 2,2-bis(4-aminophenyl)hexafluoropropane, 4,4'-(1,3-phenylenediisopropylidene)bisaniline, 4,4'-(1,4-phenylenediisopropylidene)bisaniline, 9,9-bis(4-aminophenyl)fluorene, 2,7-diaminofluorene, aminobenzylamine, diaminobenzophenone, and the like.
<Diisocyanate>
Benzene diisocyanate, toluene diisocyanate, 1,3-bis(isocyanatomethyl)benzene, 1,3-bis(isocyanatomethyl)cyclohexane, bis(4-isocyanatophenyl)methane, isophorone diisocyanate, 1,3-bis(2-isocyanato-2-propyl)benzene, 2,2-bis(4-isocyanatophenyl)hexafluoropropane, dicyclohexylmethane-4,4'-diisocyanate, and the like.
<Dicarboxylic acid>
Oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, suberic acid, azelaic acid, sebacic acid, undecanedioic acid, dodecanedioic acid, terephthalic acid, isophthalic acid, 5-hydroxyisophthalic acid, 2-chloroterephthalic acid, 2-methylterephthalic acid, 5-methylisophthalic acid, 5-sodium sulfoisophthalic acid, hexahydroterephthalic acid, hexahydroisophthalic acid, cyclohexanedicarboxylic acid, biphenyldicarboxylic acid, naphthalenedicarboxylic acid, benzophenonedicarboxylic acid, furandicarboxylic acid, 4,4'-dicarboxydiphenyl ether, and 4,4'-dicarboxydiphenyl sulfide.
<Acid chloride>
Acetyl chloride, acrylic acid chloride, methacrylic acid chloride, malonyl chloride, succinic acid dichloride, diglycolyl chloride, glutaric acid dichloride, suberic acid dichloride, sebacic acid dichloride, adipic acid dichloride, dodecandioyl dichloride, azelaic acid chloride, 2,5-furandicarbonyl dichloride, phthaloyl chloride, isophthaloyl chloride, terephthaloyl chloride, trimesic acid chloride, bis(4-chlorocarbonylphenyl) ether, 4,4'-diphenyldicarbonyl chloride, 4,4'-azodibenzoyl dichloride, and the like.
<Lactam>
ε-caprolactam, ω-undecanelactam, ω-laurolactam, and the like.

[Polyimide resin]
Examples of polyimide resins include, but are not limited to, reaction products of the diamines and the tetracarboxylic dianhydrides shown below. These may be used alone or in combination.
<Tetracarboxylic acid dianhydride>
4,4'-(hexafluoroisopropylidene)diphthalic anhydride, 5-(2,5-dioxotetrahydro-3-furanyl)-3-methyl-cyclohexene-1,2 dicarboxylic anhydride, pyromellitic dianhydride, 1,2,3,4-benzenetetracarboxylic dianhydride, 3,3',4,4'-benzophenonetetracarboxylic dianhydride, 2,2',3,3'-benzophenonetetracarboxylic dianhydride, 3,3',4,4'-biphenyltetracarboxylic dianhydride, 3,3',4,4'-diphenylsulfonate tetracarboxylic dianhydride, 2,2',3,3'-biphenyltetracarboxylic dianhydride, methylene-4,4'-diphthalic dianhydride, 1,1-ethylidene-4,4'-diphthalic dianhydride, 2,2'-propylidene-4,4'-diphthalic dianhydride, 1,2-ethylene-4,4'-diphthalic dianhydride, 1,3-trimethylene-4,4'-diphthalic dianhydride, 1,4-tetramethylene-4,4'-diphthalic dianhydride, 1,5-pentamethylene-4,4'-diphthalic dianhydride, 4,4'-oxydiphthalic dianhydride Anhydride, thio-4,4'-diphthalic dianhydride, sulfonyl-4,4'-diphthalic dianhydride, 1,3-bis(3,4-dicarboxyphenyl)benzene dianhydride, 1,3-bis(3,4-dicarboxyphenoxy)benzene dianhydride, 1,4-bis(3,4-dicarboxyphenoxy)benzene dianhydride, 1,3-bis[2-(3,4-dicarboxyphenyl)-2-propyl]benzene dianhydride, 1,4-bis[2-(3,4-dicarboxyphenyl)-2-propyl]benzene dianhydride, bis[3-(3 ,4-dicarboxyphenoxy)phenyl]methane dianhydride, bis[4-(3,4-dicarboxyphenoxy)phenyl]methane dianhydride, 2,2-bis[3-(3,4-dicarboxyphenoxy)phenyl]propane dianhydride, 2,2-bis[4-(3,4-dicarboxyphenoxy)phenyl]propane dianhydride, bis(3,4-dicarboxyphenoxy)dimethylsilane dianhydride, 1,3-bis(3,4-dicarboxyphenyl)-1,1,3,3-tetramethyldisiloxane dianhydride, 2,3,6,7- Naphthalene tetracarboxylic dianhydride, 1,4,5,8-naphthalene tetracarboxylic dianhydride, 1,2,5,6-naphthalene tetracarboxylic dianhydride, 3,4,9,10-perylene tetracarboxylic dianhydride, 2,3,6,7-anthracene tetracarboxylic dianhydride, 1,2,7,8-phenanthrene tetracarboxylic dianhydride, ethylene tetracarboxylic dianhydride, 1,2,3,4-butane tetracarboxylic dianhydride, 1,2,3,4-cyclobutane tetracarboxylic dianhydride), cyclopentane tetracarboxylic dianhydride tetracarboxylic dianhydride, cyclohexane-1,2,3,4-tetracarboxylic dianhydride, cyclohexane-1,2,4,5-tetracarboxylic dianhydride, 3,3',4,4'-bicyclohexyltetracarboxylic dianhydride, carbonyl-4,4'-bis(cyclohexane-1,2-dicarboxylic acid) dianhydride, methylene-4,4'-bis(cyclohexane-1,2-dicarboxylic acid) dianhydride, 1,2-ethylene-4,4'-bis(cyclohexane-1,2-dicarboxylic acid) dianhydride, 1,1-ethylidene-4,4' -bis(cyclohexane-1,2-dicarboxylic acid) dianhydride, 2,2-propylidene-4,4'-bis(cyclohexane-1,2-dicarboxylic acid) dianhydride, oxy-4,4'-bis(cyclohexane-1,2-dicarboxylic acid) dianhydride, thio-4,4'-bis(cyclohexane-1,2-dicarboxylic acid) dianhydride, sulfonyl-4,4'-bis(cyclohexane-1,2-dicarboxylic acid) dianhydride, bicyclo[2,2,2]oct-7-ene-2,3,5,6-tetracarboxylic acid dianhydride, rel-[1S,5 R,6R]-3-oxabicyclo[3,2,1]octane-2,4-dione-6-spiro-3'-(tetrahydrofuran-2',5'-dione), 4-(2,5-dioxotetrahydrofuran-3-yl)-1,2,3,4-tetrahydronaphthalene-1,2-dicarboxylic anhydride, ethylene glycol-bis-(3,4-dicarboxylic anhydride phenyl)ether, 4,4'-biphenyl bis(trimellitic acid monoester acid anhydride), 9,9'-bis(3,4-dicarboxyphenyl)fluorene dianhydride, and the like.

[Maleimide Compound]
The curable resin composition of the present embodiment may contain a maleimide compound. A maleimide compound is a compound having one or more maleimide groups in the molecule. Examples of the maleimide compound include 4,4'-diphenylmethane bismaleimide, polyphenylmethane maleimide, m-phenylene bismaleimide, 2,2'-bis[4-(4-maleimidophenoxy)phenyl]propane, 3,3'-dimethyl-5,5'-diethyl-4,4'-diphenylmethane bismaleimide, 4-methyl-1,3-phenylene bismaleimide, 4,4'-diphenylether bismaleimide, 4,4'-diphenylsulfone bismaleimide, 1,3-bis(3-maleimidophenoxy)benzene, 1,3-bis(4-maleimidophenoxy)benzene), and Xylox type maleimide compounds (anilix). maleimide, manufactured by Mitsui Chemicals Fine Co., Ltd.), biphenylaralkyl-type maleimide compound (solidified by distilling off the solvent under reduced pressure from a resin solution containing the maleimide compound (M2) described in Example 4 of JP 2009-001783 A), bisaminocumylbenzene-type maleimide (maleimide compound described in WO 2020/054601 A), maleimide compounds having an indane structure described in Japanese Patent No. 6629692 or WO 2020/217679, MATERIAL STAGE Vol. 18, No. 12 2019 ``Continued Epoxy Resin CAS Number Story - Hardener CAS Number Memorandum No. 31 Bismaleimide (1)'' and MATERIAL STAGE Vol. 19, No. Examples of the maleimide compounds include, but are not limited to, the maleimide compounds described in "Epoxy Resin CAS Number Story Continued - Hardener CAS Number Memorandum No. 32 Bismaleimide (2)" in 2019. These compounds may be used alone or in combination.

[Cyanate ester resin]
The cyanate ester resin is a cyanate ester compound obtained by reacting a phenol resin with a cyanogen halide, and specific examples thereof include dicyanatobenzene, tricyanatobenzene, dicyanatonaphthalene, dicyanatobiphenyl, 2,2'-bis(4-cyanatophenyl)propane, bis(4-cyanatophenyl)methane, bis(3,5-dimethyl-4-cyanatophenyl)methane, 2,2'-bis(3,5-dimethyl-4-cyanatophenyl)propane, 2,2'-bis(4-cyanatophenyl)ethane, 2,2'-bis(4-cyanatophenyl)hexafluoropropane, bis(4-cyanatophenyl)sulfone, bis(4-cyanatophenyl)thioether, phenol novolac cyanate, and phenol-dicyclopentadiene co-condensates in which the hydroxyl groups have been converted to cyanate groups, but are not limited thereto. These may be used alone or in combination.
Furthermore, the cyanate ester compound, the synthesis method of which is described in JP-A-2005-264154, is particularly preferred as the cyanate ester compound because it has low moisture absorption, excellent flame retardancy, and excellent dielectric properties.
The cyanate ester resin may contain a catalyst such as zinc naphthenate, cobalt naphthenate, copper naphthenate, lead naphthenate, zinc octoate, tin octoate, lead acetylacetonate, or dibutyltin maleate, if necessary, to trimerize the cyanate group to form a sym-triazine ring.

The catalyst is preferably used in an amount of 0.0001 to 0.10 parts by mass, and more preferably 0.00015 to 0.0015 parts by mass, per 100 parts by mass of the cyanate ester resin and curable resin composition.

[Polybutadiene and its modified products]
Polybutadiene and its modified products are polybutadiene or compounds having a structure derived from polybutadiene in the molecule. The unsaturated bonds in the polybutadiene-derived structure may be partially or entirely converted to single bonds by hydrogenation.
Examples of polybutadiene and modified products thereof include, but are not limited to, polybutadiene, hydroxyl-terminated polybutadiene, (meth)acrylated polybutadiene, carboxylic acid-terminated polybutadiene, amine-terminated polybutadiene, styrene-butadiene rubber, and the like. These may be used alone or in combination. Of these, polybutadiene or styrene-butadiene rubber is preferred from the viewpoint of dielectric properties. Examples of styrene-butadiene rubber (SBR) include RICON-100, RICON-181, RICON-184 (all manufactured by Cray Valley Corporation), 1,2-SBS (manufactured by Nippon Soda Co., Ltd.), and examples of polybutadiene include B-1000, B-2000, B-3000 (all manufactured by Nippon Soda Co., Ltd.), and the like. The molecular weight of polybutadiene and styrene-butadiene rubber is preferably 500 to 10,000 in weight average molecular weight, more preferably 750 to 7,500, and even more preferably 1,000 to 5,000. Below the lower limit of the above range, the amount of volatilization is large, making it difficult to adjust the solid content during prepreg preparation, and above the upper limit of the above range, the compatibility with other curable resins is deteriorated. In general, in the case of compounds containing heteroatoms such as oxygen and nitrogen, such as bismaleimide and polymaleimide, it is difficult to ensure compatibility with low-polarity compounds such as compounds mainly composed of hydrocarbons or compounds composed only of hydrocarbons due to their polarity. On the other hand, the compound represented by the above formula (1) is not a skeleton design in which heteroatoms such as oxygen and nitrogen are actively introduced, and is therefore also excellent in compatibility with materials having low polarity and low dielectric properties and compounds composed only of hydrocarbons.

[Polystyrene and its modified products]
Polystyrene and modified products thereof are polystyrene or compounds having a structure derived from polystyrene in the molecule.
Examples of polystyrene and modified products thereof include polystyrene, styrene-2-isopropenyl-2-oxazoline copolymers (Epocross RPS-1005, RP-61, both manufactured by Nippon Shokubai Co., Ltd.), SEP (styrene-ethylene-propylene copolymer: Septon 1020, manufactured by Kuraray Co., Ltd.), SEPS (styrene-ethylene-propylene-styrene copolymer: Septon 2002, Septon 2004F, Septon 2005, Septon 2006, Septon 2063, Septon 2104, all manufactured by Kuraray Co., Ltd.), SEEPS (styrene-ethylene/ethylene-propylene-styrene block copolymer: Septon 4003, Septon 4044, Septon 4055, Septon 4077, Septon 4099, all manufactured by Kuraray Co., Ltd.), and SEBS (styrene-ethylene-butylene-styrene block copolymer: Septon 4003, Septon 4044, Septon 4055, Septon 4077, Septon 4099, all manufactured by Kuraray Co., Ltd.). Examples of the block copolymer include, but are not limited to, SEEPS-OH (a styrene-ethylene/ethylene propylene-styrene block copolymer having a hydroxyl group at the end: SEPTON HG252, manufactured by Kuraray Co., Ltd.), SIS (styrene-isoprene-styrene block copolymer: SEPTON 5125, SEPTON 5127, manufactured by Kuraray Co., Ltd.), hydrogenated SIS (hydrogenated styrene-isoprene-styrene block copolymer: HYBRAR 7125F, HYBRAR 7311F, manufactured by Kuraray Co., Ltd.), SIBS (styrene-isobutylene-styrene block copolymer: SIBSTAR073T, SIBSTAR102T, SIBSTAR103T (all manufactured by Kaneka Corporation), SEPTON V9827 (manufactured by Kuraray Co., Ltd.)). These may be used alone or in combination. Polystyrene and modified products thereof have higher heat resistance and are less susceptible to oxidative deterioration, so it is preferable that they do not have unsaturated bonds. The weight-average molecular weight of polystyrene and modified products thereof is not particularly limited as long as it is 10,000 or more, but if it is too large, the compatibility with not only polyphenylene ether compounds but also low molecular weight components with a weight-average molecular weight of about 50 to 1,000 and oligomer components with a weight-average molecular weight of about 1,000 to 5,000 deteriorates, making it difficult to ensure mixing and solvent stability, so it is preferably about 10,000 to 300,000.

[Polyethylene and its modified products]
Polyethylene and modified products thereof are compounds having polyethylene or a structure derived from polyethylene in the molecule. Examples of polyethylene and modified products thereof include ethylene-propylene copolymers, ethylene-styrene copolymers, ethylene-propylene-ethylidene norbornene copolymers (EBT: K-8370EM, K-9330M, etc., manufactured by Mitsui Chemicals, Inc.), ethylene-propylene-vinyl norbornene copolymers (VNB-EPT: PX-006M, PX-008M, PX-009M, etc., manufactured by Mitsui Chemicals, Inc.), ethylene-vinyl alcohol copolymers, ethylene-vinyl acetate copolymers, etc., but are not limited thereto. From the viewpoint of improving heat resistance, it is preferable to use ethylene-propylene-ethylidene norbornene copolymers and ethylene-propylene-vinyl norbornene copolymers containing a crosslinkable structure. Moreover, these may be used alone or in combination. The weight average molecular weight of the polyethylene and modified products thereof is not particularly limited as long as it is 10,000 or more. However, if it is too large, compatibility with not only the polyphenylene ether compound but also low molecular weight components having a weight average molecular weight of about 50 to 1,000 and oligomer components having a weight average molecular weight of about 1,000 to 5,000 deteriorates, making it difficult to ensure mixing and solvent stability. Therefore, it is preferably about 10,000 to 300,000.

The curable resin composition of this embodiment is obtained by preparing the above components in a predetermined ratio, pre-curing at 130 to 180°C for 30 to 500 seconds, and then post-curing at 150 to 200°C for 2 to 15 hours, allowing the curing reaction to proceed sufficiently to obtain a cured product. The components of the curable resin composition can also be uniformly dispersed or dissolved in a solvent, etc., and cured after removing the solvent.

The method for preparing the curable resin composition of this embodiment is not particularly limited, but each component may be mixed uniformly or may be prepolymerized. In the case of prepolymerization, for example, a polymer containing a compound represented by the formula (1) or a structural unit represented by the formula (2) is heated in the presence or absence of a curing accelerator or a polymerization initiator, and in the presence or absence of a solvent to form a prepolymer. Similarly, an amine compound, a compound having an ethylenically unsaturated bond, a maleimide compound, a cyanate ester compound, polybutadiene and its modified products, polystyrene and its modified products, inorganic fillers, and other additives may be added to form a prepolymer. In the absence of a solvent, the components are mixed or prepolymerized by kneading them while softening them at or above their softening points using, for example, an extruder, kneader, roll, etc. In the presence of a solvent, a reaction kettle with a stirring device is used, or the components are weighed out and then the solvent is added to form a homogenous mixture.

As a method of uniform mixing, the mixture is kneaded at a temperature in the range of 50 to 100°C using a device such as a kneader, roll, or planetary mixer to obtain a uniform resin composition. The obtained resin composition is crushed and then molded into a cylindrical tablet using a molding machine such as a tablet machine, or into a granular powder or powder molded body, or these compositions can be melted on a surface support and molded into a sheet having a thickness of 0.05 mm to 10 mm to obtain a molded curable resin composition. The obtained molded body is a non-sticky molded body at 0 to 20°C, and even if stored at -25 to 0°C for one week or more, the flowability and curability are hardly reduced.
The obtained molded article can be molded into a cured product using a transfer molding machine or a compression molding machine.

The curable resin composition of this embodiment can be made into a varnish-like composition (hereinafter, simply referred to as varnish) by adding an organic solvent. The curable resin composition of this embodiment can be dissolved in a solvent such as toluene, xylene, acetone, methyl ethyl ketone, methyl isobutyl ketone, dimethylformamide, dimethylacetamide, N-methylpyrrolidone, etc. as necessary to make a varnish, which can be impregnated into a substrate such as glass fiber, carbon fiber, polyester fiber, polyamide fiber, alumina fiber, paper, etc., and dried by heating to obtain a prepreg, which can be hot-press molded to obtain a cured product of the curable resin composition of this embodiment. The solvent used in this case is 10 to 70% by weight, preferably 15 to 70% by weight, of the mixture of the curable resin composition of this embodiment and the solvent. If the composition is in a liquid state, a cured product of the curable resin containing carbon fiber can be obtained as it is, for example, by the RTM method.

The curable composition of this embodiment can also be used as a modifier for a film-type composition. Specifically, it can be used to improve flexibility in the B-stage. Such a film-type resin composition can be obtained as a sheet-like adhesive by applying the curable resin composition of this embodiment as a curable resin composition varnish onto a release film, removing the solvent under heating, and then performing B-stage conversion. This sheet-like adhesive can be used as an interlayer insulating layer in a multilayer substrate, etc.

The curable resin composition of the present embodiment can be heated and melted, reduced in viscosity, and impregnated into reinforcing fibers such as glass fibers, carbon fibers, polyester fibers, polyamide fibers, and alumina fibers to obtain a prepreg. Specific examples include glass fibers such as E glass cloth, D glass cloth, S glass cloth, Q glass cloth, spherical glass cloth, NE glass cloth, and T glass cloth, as well as inorganic fibers other than glass, and organic fibers such as polyparaphenylene terephthalamide (Kevlar (registered trademark), manufactured by DuPont), fully aromatic polyamide, polyester, polyparaphenylene benzoxazole, polyimide, and carbon fibers, but are not limited to these. The shape of the substrate is not particularly limited, but examples include woven fabric, nonwoven fabric, roving, chopped strand mat, and the like. In addition, plain weave, sash weave, twill weave, and the like are known as weaving methods for woven fabrics, and these known methods can be appropriately selected and used depending on the intended use and performance. In addition, woven fabrics that have been subjected to fiber opening treatment or glass woven fabrics that have been surface-treated with a silane coupling agent or the like are preferably used. The thickness of the substrate is not particularly limited, but is preferably about 0.01 to 0.4 mm. Prepregs can also be obtained by impregnating reinforcing fibers with the varnish and drying them by heating.

Moreover, a laminate can be manufactured using the prepreg. The laminate is not particularly limited as long as it has one or more prepregs, and may have any other layer. The manufacturing method of the laminate can be appropriately applied by a generally known method, and is not particularly limited. For example, when molding a metal foil-clad laminate, a multi-stage press machine, a multi-stage vacuum press machine, a continuous molding machine, an autoclave molding machine, etc. can be used, and the prepregs are laminated together and heated and pressurized to obtain a laminate. At this time, the heating temperature is not particularly limited, but is preferably 65 to 300 ° C, and more preferably 120 to 270 ° C. In addition, the pressure to be applied is not particularly limited, but if the pressure is too high, it is difficult to adjust the solid content of the resin of the laminate, and the quality is not stable, and if the pressure is too low, air bubbles and adhesion between the laminates are deteriorated, so that 2.0 to 5.0 MPa is preferable, and 2.5 to 4.0 MPa is more preferable. The laminate of this embodiment can be suitably used as a metal foil-clad laminate described later by providing a layer made of metal foil.
The prepreg is cut into a desired shape and laminated with copper foil or the like as necessary. The laminate is then heated and cured while applying pressure thereto by press molding, autoclave molding, sheet winding molding or the like, to obtain an electrical and electronic laminate (printed wiring board) or a carbon fiber reinforced material.

The curable resin composition of this embodiment can also be made into a resin sheet. A method for obtaining a resin sheet from the curable resin composition of this embodiment includes, for example, applying the curable resin composition onto a support film (support), drying the composition, and forming a resin composition layer on the support film. When the curable resin composition of this embodiment is used for a resin sheet, it is essential that the film softens under the lamination temperature conditions (70°C to 140°C) in the vacuum lamination method, and exhibits a fluidity (resin flow) that allows resin to fill via holes or through holes in the circuit board at the same time as laminating the circuit board, and it is preferable to mix the above-mentioned components so as to exhibit such characteristics. In addition, the obtained resin sheet or circuit board (copper-clad laminate, etc.) is required to have a uniform appearance in order to exhibit a certain performance at any part without causing a phenomenon in which different characteristic values are locally exhibited due to phase separation, etc.

Here, the through holes in the circuit board have a diameter of 0.1 to 0.5 mm and a depth of 0.1 to 1.2 mm, and it is preferable to make it possible to fill them with resin within this range. If both sides of the circuit board are to be laminated, it is desirable to fill about half of the through holes.

A specific method for producing the resin sheet includes preparing a resin composition varnished by blending an organic solvent, applying the varnished resin composition to the surface of a support film (Y), and then drying the organic solvent by heating or blowing hot air onto the resin composition to form a resin composition layer (X).

The organic solvents used here preferably include, for example, ketones such as acetone, methyl ethyl ketone, and cyclohexanone; acetate esters such as ethyl acetate, butyl acetate, cellosolve acetate, propylene glycol monomethyl ether acetate, and carbitol acetate; carbitols such as cellosolve and butyl carbitol; aromatic hydrocarbons such as toluene and xylene; dimethylformamide, dimethylacetamide, and N-methylpyrrolidone; and it is preferable to use the solvent in a proportion that results in a non-volatile content of 30 to 60% by mass.

The thickness of the resin composition layer (X) formed must be equal to or greater than the thickness of the conductor layer. Since the thickness of the conductor layer of the circuit board is in the range of 5 to 70 μm, the thickness of the resin composition layer (X) is preferably 10 to 100 μm. The resin composition layer (X) in this embodiment may be protected with a protective film, which will be described later. By protecting the resin composition layer with a protective film, it is possible to prevent the adhesion of dirt and the like to the surface of the resin composition layer and prevent scratches.

The support film and protective film may be made of polyolefins such as polyethylene, polypropylene, and polyvinyl chloride; polyesters such as polyethylene terephthalate (PET) and polyethylene naphthalate; polycarbonate; polyimide; and even release paper and metal foils such as copper foil and aluminum foil. The support film and protective film may be subjected to a mud treatment, corona treatment, or release treatment. The thickness of the support film is not particularly limited, but is in the range of 10 to 150 μm, and preferably 25 to 50 μm. The thickness of the protective film is preferably 1 to 40 μm.

The support film (Y) is peeled off after laminating it onto the circuit board, or after forming an insulating layer by heat curing. If the support film (Y) is peeled off after the resin composition layer constituting the resin sheet is heat cured, the adhesion of dust and the like during the curing process can be prevented. If the support film is peeled off after curing, a release treatment is applied to the support film in advance.

Incidentally, a multilayer printed circuit board can be manufactured from the resin sheet obtained as described above. For example, when the resin composition layer (X) is protected by a protective film, the protective film is peeled off, and then the resin composition layer (X) is laminated on one or both sides of the circuit board so as to be in direct contact with the circuit board, for example, by a vacuum lamination method. The lamination method may be a batch type or a continuous type using a roll. If necessary, the resin sheet and the circuit board may be heated (preheated) before lamination. The lamination conditions are preferably a pressure bonding temperature (lamination temperature) of 70 to 140°C, a pressure bonding pressure of 1 to 11 kgf/cm ² (9.8×10 ⁴ to 107.9×10 ⁴ N/m ² ), and lamination is preferably performed under reduced pressure of 20 mmHg (26.7 hPa) or less air pressure.

The curable resin composition of this embodiment can be used to manufacture a semiconductor device. Examples of semiconductor devices include DIP (dual in-line package), QFP (quad flat package), BGA (ball grid array), CSP (chip size package), SOP (small outline package), TSOP (thin small outline package), TQFP (thin quad flat package), etc.

The curable resin composition of this embodiment and its cured product can be used in a wide range of fields. Specifically, it can be used in various applications such as molding materials, adhesives, composite materials, and paints. The cured product of the curable resin composition described in this embodiment exhibits excellent heat resistance and dielectric properties, and is therefore suitable for use in electrical and electronic components such as encapsulants for semiconductor elements, encapsulants for liquid crystal display elements, encapsulants for organic EL elements, laminates (printed wiring boards, BGA substrates, build-up substrates, etc.), composite materials for lightweight and high-strength structural materials such as carbon fiber reinforced plastics and glass fiber reinforced plastics, 3D printing, etc.

Next, the present invention will be explained in more detail with reference to examples. Unless otherwise specified, all parts are parts by weight. However, the present invention is not limited to these examples.

Various analytical methods used in the examples are described below.
GPC (gel permeation chromatography) analysis columns: SHODEX GPC KF-601 (2 columns), KF-602, KF-602.5, KF-603
Flow rate: 1.5ml/min.
Column temperature: 40°C
Solvent used: THF (tetrahydrofuran)
Detector: RI (Differential Refraction Detector)

- Iodine value measurement method: Weigh out 0.096 g of the compound to be measured. Add 4 ml of dichloromethane to dissolve. Add 10 ml of Wiess's reagent and leave in the dark for 30 minutes. Measure out 8 ml of potassium iodide solution (100 g/L) and 40 ml of water and add to the sample. Titration was performed using 0.1 mol/L sodium thiosulfate aqueous solution and starch solution as an indicator. The end point of the starch reagent was when the color disappeared.

[Synthesis Example 1]
A flask equipped with a thermometer, a cooling tube, and a stirrer was equipped with an aspirator and a base trap. 370.1 parts of 2-bromoethylbenzene (Tokyo Chemical Industry Co., Ltd.), 175.1 parts of α,α'-dichloro-p-xylene (Tokyo Chemical Industry Co., Ltd.), and 27.3 parts of methanesulfonic acid (Tokyo Chemical Industry Co., Ltd.) were charged into the flask, and the mixture was reacted at 130°C for 6 hours while collecting the generated hydrogen chloride with a base trap. 100 parts of toluene and 600 parts of cyclohexane were added for extraction, and the organic layer was washed five times with 100 parts of water. The solvent and excess 2-bromoethylbenzene were distilled off under heating and reduced pressure to obtain 380 parts of a compound (BEB-1) having a 2-bromoethylbenzene structure represented by the following formula (7) as a liquid resin (Mn: 938, Mw: 1290). The GPC chart of the obtained compound is shown in Figure 1. The average value n of the repeating units calculated from the area % of the GPC chart was 2.2.

[Synthesis Example 2]
A flask equipped with a thermometer, a cooling tube, and a stirrer was charged with 300 parts of BEB-1 obtained in Synthesis Example 1, 245 parts of toluene, 735 parts of dimethyl sulfoxide, 0.15 parts of 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl free radical, and 146.4 parts of 50 wt% aqueous sodium hydroxide solution, and the reaction was continued at 40 ° C. for 6 hours. 100 parts of water was added, the organic layer was washed, and the organic layer was returned to the reaction vessel. 735 parts of dimethyl sulfoxide and 9.8 parts of a 50 wt% aqueous sodium hydroxide solution were added, and the reaction was continued again at 40 ° C. for 1 hour, 300 parts of toluene were added, and the organic layer was repeatedly washed with 100 parts of water until the wastewater became neutral. The mixture was concentrated under reduced pressure using an evaporator, and 180 parts of a compound (O-1) having two or more styrene structures in the molecule represented by the following formula (8) was obtained. The GPC chart of the obtained compound is shown in FIG. 2. The average value n of the repeating units calculated from the area % of the GPC chart was 2.2 (the molecular weight of the resin component was Mn: 797, Mw: 1187).

[Synthesis Example 3]
In a flask equipped with a thermometer, a cooling tube, and a stirrer, 507 parts of divinylbenzene, 304 parts of ethylvinylbenzene, 915 parts of styrene, and 1532 parts of n-propyl acetate were added and heated to 70°C. 41 parts of boron trifluoride diethyl ether complex were further added, and the reaction was continued at 70°C for 4 hours. A saturated aqueous sodium hydrogen carbonate solution was added to stop the reaction, and the organic layer was repeatedly washed three times with 100 parts of pure water. The washed organic layer was concentrated under reduced pressure using an evaporator to obtain a polymer having a structural unit represented by the following formula (2), a structural unit represented by the following formula (3-a), and a structural unit represented by the following formula (3-c). The number average molecular weight Mn of the obtained polymer was 4170, and the weight average molecular weight Mw was 37468. The iodine value was 80.

[Examples 1 and 2, Comparative Examples 1 and 2]
A toluene solution with a solid content of 40% by weight was prepared using the compound obtained in Synthesis Example 2, the polymer obtained in Synthesis Example 3, OPE-2St 2200 (terminal styrylated polyphenylene ether compound, Mn: 2110, manufactured by Mitsubishi Gas Chemical Company, Inc.), and Septon 2104 (styrene-ethylene propylene-styrene rubber, manufactured by Kuraray Co., Ltd.) in the amounts shown in Table 1, and the solution was applied to a mirror-finished copper foil (T4X: manufactured by Fukuda Metal Copper Foil Co., Ltd.) using an applicator with a coating thickness of 200 μm, and then cured in an inert oven at 200° C. for 2 hours, and the copper foil was removed to obtain a cured product. For evaluation, a test piece of the desired size was cut out using a laser cutter as necessary.

<Heat resistance test>
DMA analysis: Using a DMAQ800 manufactured by TA Instruments, the temperature at which the tan δ value was maximized was determined as Tg using a tensile probe under the following conditions: heating rate of 2°C/min., measurement temperature range of 25°C to 350°C, and measurement frequency of 10 Hz. The test was performed with a sample size of 5 mm width x 40 mm length and a thickness of 0.06 mm.

<Mechanical strength test>
A tensile test was carried out using an autograph AGS-X500N manufactured by Shimadzu Corporation, with a chuck distance of 50 mm and a tensile speed of 0.5 mm/min.

<Linear expansion coefficient test>
-TMA analysis Using a TA Instruments TMAQ400, measurements were performed with a tensile probe under the conditions of a temperature rise rate of 2°C/min., a measurement temperature range of 25°C to 330°C, and a load of 0.05N. The sample size was 4mm wide x 35mm long, and the thickness was 0.06mm. The measurement method was as follows: the temperature was raised from 25°C to 270°C, cooled again to 25°C, and then raised to 330°C. The linear expansion coefficient from 60°C to 90°C was defined as α1, and the linear expansion coefficient from 225°C to 240°C was defined as α2.

<Dielectric tangent test>
The test was performed by a cavity resonator perturbation method at 25° C. using a 10 GHz cavity resonator manufactured by AET Co., Ltd. The sample size was 2.5 mm wide x 50 mm long, and the thickness was 0.06 mm.

The results in Table 1 show that Comparative Example 1 has issues with dielectric tangent, and Comparative Example 2 has issues with mechanical strength (elastic modulus) and linear expansion coefficient. On the other hand, Examples 1 and 2 were confirmed to have excellent properties in all characteristics.

The curable resin composition of the present invention is suitably used for electric and electronic parts such as semiconductor encapsulants, printed wiring boards, and build-up laminates.

Claims (8)

A curable resin composition comprising a compound represented by the following formula (1), a polymer containing a structural unit represented by the following formula (2), a polyphenylene ether compound having an unsaturated double bond, and a hydrogenated product of a block copolymer composed of a block unit of a polymer composed of a styrene-based monomer and a block unit of a polymer composed of a conjugated diene compound,
The content of the polyphenylene ether compound is 60 to 80 parts by weight based on the total amount of the curable resin composition .

(In formula (1), each of the multiple R's exists independently and represents a hydrocarbon group having 1 to 10 carbon atoms or a halogenated alkyl group having 1 to 10 carbon atoms. p and r represent integers of 0 to 4, q represents an integer of 0 to 3, n represents the average number of repetitions, and 1≦n≦20.)

The curable resin composition according to claim 1 , wherein the polymer containing the structural unit represented by formula (2) further contains a structural unit represented by formula (3):

(In formula (3), each R represents a hydrogen atom or an alkyl group having 1 to 10 carbon atoms.) The curable resin composition according to claim 1 , wherein the polyphenylene ether compound having an unsaturated double bond is represented by the following formula (4) or the following formula (5).

(In formula (4), n is the average number of repetitions, and 1<n<10.)

(In formula (5), n is the average number of repetitions, and 1<n<10.) The curable resin composition according to claim 1 , wherein the hydrogenated product of the block copolymer is a compound represented by the following formula (6):

(In formula (6), l, m, and n are the average values of the repeating numbers and represent real numbers from 1 to 10,000. The order of the repeating units bracketed by l, m, and n is not limited, and the bonding style may be any of alternating, block, and random.) The curable resin composition according to claim 1, further comprising at least one selected from the group consisting of a maleimide compound, a compound having an ethylenically unsaturated bond other than the polyphenylene ether compound having an unsaturated double bond , a cyanate ester resin, polybutadiene and modified products thereof, polystyrene and modified products thereof, and polyethylene and modified products thereof. A prepreg comprising the curable resin composition according to claim 1 supported on a sheet-like fiber substrate. A cured product obtained by curing the curable resin composition according to any one of claims 1 to 5. A cured product obtained by curing the prepreg according to claim 6.

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