WO2024106523A1 - Benzoxazine compound, resin material composition containing same, curable resin composition, and cured product of same - Google Patents

Abstract

The present invention addresses the problem of providing a new benzoxazine compound that can be stored for an extended period of time even under room temperature conditions, a resin material composition containing the benzoxazine compound, a curable resin composition, and a cured product of the same. As a solution to the problem, provided is a benzoxazine compound represented by general formula (1). (In the formula, each R₁ independently represents an alkylene group having 1-4 carbon atoms, and X represents a cycloalkylidene group having 5-20 carbon atoms.)

Description

Benzoxazine compound, resin raw material composition containing the same, curable resin composition, and cured product thereof

The present invention relates to a benzoxazine compound, a resin raw material composition containing the same, a curable resin composition, and a cured product thereof. More specifically, the present invention relates to a benzoxazine compound having benzoxazine rings at both ends of a cycloalkylidene group and further having an allyl group, a resin raw material composition containing the same, a curable resin composition, and a cured product thereof.

Benzoxazine compounds are compounds synthesized by reacting phenols, amines, and formaldehyde, and are known as thermosetting resin raw materials that cure by ring-opening polymerization of benzoxazine rings without producing volatile by-products when heated, and are used as raw materials for molded products that can be used as materials for insulating substrates, liquid crystal alignment agents, semiconductor encapsulation resin compositions, etc. For such applications, heat resistance with excellent stability and reliability at high temperatures is required.
On the other hand, problems remain regarding heat resistance, such as the lack of heat resistance at 200° C. or higher, and in order to improve these problems, a benzoxazine composition into which an allyl group has been introduced has been reported (Patent Document 1).

JP 2003-286320 A

It has become clear that, among benzoxazine monomers having an allyl group, the benzoxazine compound represented by formula (i) undergoes a polymerization reaction even at room temperature, resulting in a decrease in purity, and thus posing a problem in its handling as a resin raw material.
An object of the present invention is to provide a novel benzoxazine compound having an allyl group, which can be stored for a long period of time even under room temperature conditions, a resin raw material composition containing the same, a curable resin composition, and a cured product thereof.

As a result of extensive research into solving the above problems, the present inventors discovered that a benzoxazine compound using cycloalkylidene bisphenol as a raw material, having benzoxazine rings at both ends of the cycloalkylidene group, and further having an allyl group, can be stored for long periods even at room temperature, thus completing the present invention.

The present invention is as follows.
1. A benzoxazine compound represented by general formula (1):
(In the formula, each R ₁ independently represents an alkylene group having 1 to 4 carbon atoms, and X represents a cycloalkylidene group having 5 to 20 carbon atoms.)
2. The benzoxazine compound according to 1., wherein X is a cyclohexylidene group, a 3-methylcyclohexylidene group, a 4-methylcyclohexylidene group, a 3,3,5-trimethylcyclohexylidene group, or a cyclododecanylidene group.
3. A resin raw material composition comprising the benzoxazine compound according to 1.
4. The resin raw material composition according to 3., wherein the content of the benzoxazine compound represented by the general formula (1) is in the range of 10 to 100 area % based on the area of all peaks detected by analysis by gel permeation chromatography using a differential refractometer as a detector.
5. A curable resin composition comprising the benzoxazine compound according to 1. or the resin raw material composition according to 3.
6. The curable resin composition according to 5., comprising the benzoxazine compound according to 1. or the resin raw material composition according to 3., and one or more selected from the group consisting of an epoxy resin, a benzoxazine compound other than the benzoxazine compound represented by general formula (1), a phenolic resin, and a bismaleimide compound.
7.5. A cured product obtained by curing the curable resin composition described in 7.5.

The benzoxazine compound of the present invention and the resin raw material composition containing the same are extremely useful because they can be stored for a long period of time even under room temperature conditions, as compared with the conventionally known benzoxazine compounds represented by formula (i).
Furthermore, the benzoxazine compound of the present invention and the curable resin composition containing the resin raw material composition containing the same can give a cured product having excellent heat resistance and dielectric properties, which makes them very useful as resin materials for prepregs, printed circuit boards, sealants for semiconductors and electronic parts, electric and electronic molded parts, automobile parts, laminates, paints, resist inks, etc.

FIG. 1 is a diagram showing a spectrum by ¹ H NMR analysis of the benzoxazine compound represented by formula (1-4) obtained in Example 1. FIG. 2 is a diagram showing a spectrum by ¹ H NMR analysis of the benzoxazine compound represented by formula (1-5) obtained in Example 2.

<Benzoxazine Compound of the Present Invention>
The benzoxazine compound of the present invention is represented by the general formula (1).
(In the formula, each R ₁ independently represents an alkylene group having 1 to 4 carbon atoms, and X represents a cycloalkylidene group having 5 to 20 carbon atoms.)
In general formula (1), R ₁ 's are each independently an alkylene group having 1 to 4 carbon atoms, preferably an alkylene group having 1 to 2 carbon atoms, more preferably a methylene group or 1,2-ethylene group, and particularly preferably a methylene group.
X in general formula (1) represents a cycloalkylidene group having 5 to 20 carbon atoms, which may contain an alkyl group as a branched chain, in which case the number of carbon atoms of the alkyl group as a branched chain is also included in the number of carbon atoms of 5 to 20. The cycloalkylidene group preferably has 5 to 15 carbon atoms, more preferably has 6 to 12 carbon atoms, further preferably has 6 to 10 carbon atoms, and particularly preferably has 6 to 9 carbon atoms.
Specific examples of the cycloalkylidene group include a cyclopentylidene group (5 carbon atoms), a cyclohexylidene group (6 carbon atoms), a 3-methylcyclohexylidene group (7 carbon atoms), a 4-methylcyclohexylidene group (7 carbon atoms), a 3,3,5-trimethylcyclohexylidene group (9 carbon atoms), a cycloheptylidene group (7 carbon atoms), a bicyclo[2.2.1]heptane-2,2-diyl group (7 carbon atoms), a 1,7,7-trimethylbicyclo[2.2.1]heptane-2,2-diyl group (10 carbon atoms), a 4,7,7-trimethylbicyclo[2.2.1]heptane-2,2-diyl group (10 carbon atoms), a tricyclo[5.2.1.0 ^2,6 ]decane-8,8-diyl group (10 carbon atoms), 2,2-adamantylidene group (10 carbon atoms), cyclododecanylidene group (12 carbon atoms), etc. are preferred. A cyclohexylidene group (6 carbon atoms), a 3-methylcyclohexylidene group (7 carbon atoms), a 4-methylcyclohexylidene group (7 carbon atoms), a 3,3,5-trimethylcyclohexylidene group (9 carbon atoms) or a cyclododecanylidene group (12 carbon atoms) is preferred, a cyclohexylidene group (6 carbon atoms), a 3,3,5-trimethylcyclohexylidene group (9 carbon atoms) or a cyclododecanylidene group (12 carbon atoms) is more preferred, and a 3,3,5-trimethylcyclohexylidene group (9 carbon atoms) is particularly preferred.

Specific examples of the benzoxazine compound represented by general formula (1) in the present invention include compounds represented by the following formulas (1-1) to (1-20). Among these, compounds (1-1) to (1-5) and compounds (1-11) to (1-15) are preferred, compounds (1-1), (1-4), (1-5), (1-11), (1-14) and (1-15) are more preferred, compounds (1-4), (1-5), (1-14) and (1-15) are even more preferred, and compounds (1-4) and (1-14) are particularly preferred.

<Production Method of the Compound of the Present Invention>
The starting material and the manufacturing method for the benzoxazine compound represented by the general formula (1) in the present invention are not particularly limited. For example, as illustrated in the following reaction formula, a manufacturing method can be mentioned in which a bisphenol compound represented by the general formula (2), an amine compound represented by the general formula (3), and formaldehyde are subjected to a dehydration condensation reaction to cyclize, thereby obtaining the target benzoxazine compound represented by the general formula (1).
(In the formula, R ₁ and X are defined as in general formula (1).)

In the above production method, a bisphenol compound represented by the general formula (2), an amine compound represented by the general formula (3), and a formaldehyde compound are used as starting materials.
Specific examples of the bisphenol compound represented by the general formula (2) include bisphenol Z (1,1-bis(4-hydroxyphenyl)cyclohexane), 1,1-bis(4-hydroxyphenyl)-3-methylcyclohexane, 1,1-bis(4-hydroxyphenyl)-4-methylcyclohexane, 1,1-bis(4-hydroxyphenyl)-3,3,5-trimethylcyclohexane, 1,1-bis(4-hydroxyphenyl)cyclododecane, 2,2-bis(4-hydroxyphenyl)bicyclo[2.2.1]heptane, 2,2-bis(4-hydroxyphenyl)-1,7,7-trimethylbicyclo[2.2.1]heptane, 2,2-bis(4-hydroxyphenyl)-4,7,7-trimethylbicyclo[2.2.1]heptane, 4,4'-(tricyclo[5.2.1.0 ^2,6 ]decane-8,8-diyl)bisphenol, 2,2-bis(4-hydroxyphenyl)adamantane, etc. Among them, bisphenol Z (1,1-bis(4-hydroxyphenyl)cyclohexane), 1,1-bis(4-hydroxyphenyl)-3-methylcyclohexane, 1,1-bis(4-hydroxyphenyl)-4-methylcyclohexane, 1,1-bis(4-hydroxyphenyl)-3,3,5-trimethylcyclohexane or 1,1-bis(4-hydroxyphenyl)cyclododecane is preferred, 1,1-bis(4-hydroxyphenyl)-3,3,5-trimethylcyclohexane or 1,1-bis(4-hydroxyphenyl)cyclododecane is more preferred, and 1,1-bis(4-hydroxyphenyl)-3,3,5-trimethylcyclohexane is particularly preferred.
Specific examples of the amine compound represented by the general formula (3) include allylamine, 3-butene-1-amine, and 4-pentene-1-amine. Of these, allylamine is preferred.
The amine compound represented by the general formula (3) can also be used as a salt with an inorganic acid such as hydrochloric acid or sulfuric acid. In such a case, the reaction is carried out in the further presence of an alkaline aqueous solution in which sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, sodium hydrogen carbonate, potassium hydrogen carbonate, or the like is dissolved in water.
Specific examples of formaldehydes include aqueous formaldehyde solutions, 1,3,5-trioxane, and paraformaldehyde.
In the above production method, the amount of formaldehyde used is preferably in the range of 4.0 to 20.0 mol, more preferably in the range of 4.0 to 16.0 mol, and even more preferably in the range of 4.0 to 12.0 mol, per mol of the bisphenol compound represented by general formula (2).
In the above production method, the amount of the amine compound represented by general formula (3) used is preferably in the range of 2.0 to 10.0 mol, more preferably in the range of 2.0 to 8.0 mol, and even more preferably in the range of 2.0 to 6.0 mol, per 1 mol of the bisphenol compound represented by general formula (2).

No particular catalyst is required to promote the reaction, but an acid catalyst or base catalyst can be used as necessary. In this case, examples of acid catalysts that can be used include concentrated hydrochloric acid, hydrochloric acid gas, trifluoroacetic acid, methanesulfonic acid, p-toluenesulfonic acid, benzoic acid, and mixtures thereof, while examples of base catalysts that can be used include, but are not limited to, sodium hydroxide, sodium carbonate, triethylamine, triethanolamine, and mixtures thereof. Among these, p-toluenesulfonic acid and sodium hydroxide are preferred, and sodium hydroxide is even more preferred.

The reaction is usually carried out in the presence of a solvent. There are no particular limitations on the solvent as long as it does not inhibit the reaction, but preferred examples include aromatic hydrocarbons with 6 to 9 carbon atoms, such as toluene and xylene, aliphatic alkyls with 5 to 8 carbon atoms, such as hexane, heptane, and cyclohexane, aliphatic esters with 3 to 6 carbon atoms, such as methyl acetate, ethyl acetate, methyl propionate, and butyl acetate, and water. Among these, aromatic hydrocarbons with 6 to 9 carbon atoms and aliphatic esters with 3 to 6 carbon atoms are more preferred, and aliphatic esters with 3 to 6 carbon atoms are even more preferred. These solvents can be used alone or in combination. There are no particular limitations on the amount of solvent used as long as it does not interfere with the reaction, but usually, the amount is preferably in the range of 200 to 400 parts by weight, and more preferably in the range of 250 to 300 parts by weight, per 100 parts by weight of the bisphenol compound represented by general formula (2).

The reaction temperature is usually preferably in the range of 30 to 100°C, more preferably in the range of 30 to 80°C, and particularly preferably in the range of 40 to 70°C.
The reaction may be carried out under normal pressure, or under increased or reduced pressure.
There is no limitation on the method of mixing the raw materials, bisphenol compound represented by general formula (2), formaldehydes, and amine compound represented by general formula (3). For example, (a) a method of mixing an amine compound represented by general formula (3) with a mixture containing a bisphenol compound represented by general formula (2) and formaldehydes to carry out a reaction, and (b) a method of mixing a bisphenol compound represented by general formula (2) with a mixture containing formaldehydes and an amine compound represented by general formula (3), etc. can be mentioned. These mixtures may contain the above-mentioned solvents and catalysts, and there is no limitation on the method of mixing the catalyst, but it is preferable to mix the catalyst before mixing the amine compound represented by general formula (3).
In the production method of the present invention, there is no limitation on the method for mixing the remaining raw materials with the raw material mixture. However, from the viewpoint of reaction selectivity and suppressing the production of high molecular weight components as by-products, it is preferable to mix the raw materials continuously or intermittently, for example, over a period of 10 minutes to 2 hours, rather than mixing them all at once.

As another embodiment, the method may include a procedure for removing water derived from the raw materials or water generated during the reaction from the system. The procedure for removing the generated water from the reaction solution is not particularly limited, and can be carried out by azeotropically distilling the generated water with the solvent system in the reaction solution. The generated water can be removed from the reaction system by using, for example, a pressure-equalizing dropping funnel equipped with a cock, a Dimroth condenser, a Dean-Stark apparatus, or the like.

After the reaction is completed, the benzoxazine compound represented by general formula (1) can be obtained from the resulting reaction mixture by a known method. For example, after the reaction, the reaction mixture may be subjected to a treatment such as deactivating the catalyst used or washing with water, and the target product can be obtained as a residual liquid by distilling off the remaining raw materials and solvent from the reaction mixture. It is also possible to obtain the target product by precipitating the target product by adding a poor solvent to the residual liquid, or to obtain the target product in powder or granular form by adding a solvent to the reaction mixture to crystallize and filter it. The benzoxazine compound extracted by the above method can be made into a high-purity product by ordinary purification means such as washing with a solvent or water or recrystallization.

<Resin raw material composition containing benzoxazine compound represented by general formula (1)>
The resin raw material composition of the present invention is characterized by containing a benzoxazine compound represented by general formula (1), and can be obtained by distilling off the remaining raw materials and the solvent from the above-mentioned reaction mixture. The residual liquid can be added to a poor solvent to obtain a precipitated target product, or a solvent can be added to the reaction mixture to crystallize and filter to obtain a powder or granular resin raw material composition of the present invention. For example, the resin raw material composition of the present invention, which contains a large amount of the benzoxazine compound represented by general formula (1), can be obtained by carrying out normal purification such as washing with a solvent or water or recrystallization.

The resin raw material composition in the present invention may contain a compound that is a by-product in the reaction for producing the benzoxazine compound represented by general formula (1). Examples of such by-products include compounds having a higher molecular weight than the benzoxazine compound represented by general formula (1).
In the resin raw material composition of the present invention, the content of the benzoxazine compound represented by general formula (1) is not particularly limited, but the content can be analyzed by gel permeation chromatography using a differential refractometer as a detector, and is usually in the range of 10 to 100 area %, preferably in the range of 20 to 100 area %, more preferably in the range of 40 to 100 area %, and particularly preferably in the range of 60 to 100 area %, based on the areas of all peaks detected in such analysis.

<Curable resin composition containing a benzoxazine compound represented by general formula (1) or a resin raw material composition containing the same>
The benzoxazine compound of the present invention represented by the general formula (1) or a resin raw material composition containing the same can be used as a curable resin composition containing the compound as an essential component.
One embodiment of the present invention is a curable resin composition obtained by mixing a benzoxazine compound represented by general formula (1) or a resin raw material composition containing the same with an inorganic filler such as silicon oxide, aluminum oxide, magnesium oxide, boron nitride, aluminum nitride, silicon nitride, silicon carbide, or hexagonal boron nitride, or a reinforcing fiber such as carbon fiber, glass fiber, organic fiber, boron fiber, steel fiber, or aramid fiber.
Another embodiment is a curable resin composition that contains, as an essential component, the benzoxazine compound represented by the general formula (1) or a resin raw material composition containing the same, and also contains other polymer materials.
The polymer material constituting the curable resin composition of the present invention is not particularly limited, but may contain an epoxy resin, a phenolic resin, a bismaleimide compound, a benzoxazine compound other than the benzoxazine compound represented by general formula (1), and raw materials for each of them.

Examples of epoxy resins include orthocresol type epoxy resins, biphenyl type epoxy resins, biphenyl aralkyl type epoxy resins, naphthalene type epoxy resins, anthracene dihydride type epoxy resins, brominated novolac type epoxy resins, bisphenol A type epoxy resins, bisphenol F type epoxy resins, bisphenol S type epoxy resins, cycloalkylidene bisphenol type epoxy, phenol novolac type epoxy resins, cresol novolac type epoxy resins, resorcinol type epoxy resins, trisphenylmethane type epoxy resins, dicyclopentadiene type epoxy resins, and alicyclic epoxy resins.
Among these, from the viewpoint of the heat resistance and dielectric properties of the obtained cured product, it is preferable to use at least one epoxy resin selected from cycloalkylidene bisphenol type epoxy, dicyclopentadiene type epoxy resin, and alicyclic epoxy resin, which are epoxy resins having a cyclic aliphatic structure.

Commercially available biphenyl-type epoxy resins include, for example, "jER" YX4000H, "jER" YX4000, and "jER" YL6616 (manufactured by Mitsubishi Chemical Corporation).
An example of a commercially available biphenyl aralkyl type epoxy resin is NC-3000 (manufactured by Nippon Kayaku Co., Ltd.).
Commercially available naphthalene-type epoxy resins include, for example, "Epiclon" HP4032 (manufactured by DIC Corporation), NC-7000, and NC-7300 (manufactured by Nippon Kayaku Co., Ltd.).
Commercially available bisphenol A type epoxy resins include, for example, "jER" 825, "jER" 826, "jER" 827, "jER" 828, and "jER" 834 (manufactured by Mitsubishi Chemical Corporation), "Epiclon" (registered trademark, the same applies below) 850 (manufactured by DIC Corporation), "Epotohto" (registered trademark, the same applies below) YD-128 (manufactured by Nippon Steel Chemical Co., Ltd.), and DER-331 and DER-332 (manufactured by The Dow Chemical Company).
Commercially available bisphenol F type epoxy resins include, for example, "jER" 806, "jER" 807, "jER" 1750, "jER" 4007P, "jER" 4010P (manufactured by Mitsubishi Chemical Corporation), "Epiclon" 830 (manufactured by DIC Corporation), "Epototo" YD-170, "Epototo" YDF2001, and "Epototo" YDF2004 (manufactured by Nippon Steel Chemical Co., Ltd.).
An example of the bisphenol S type epoxy resin is EXA-1515 (manufactured by DIC Corporation).
Specific examples of cycloalkylidene bisphenol type epoxy include compounds represented by the following formula:
Commercially available phenol novolac type epoxy resins include, for example, "jER" 152, "jER" 154 (manufactured by Mitsubishi Chemical Corporation), "Epiclon" N-740, "Epiclon" N-770, and "Epiclon" N-775 (manufactured by DIC Corporation).
Commercially available cresol novolac epoxy resins include, for example, "Epicron" N-660, "Epicron" N-665, "Epicron" N-670, "Epicron" N-673, and "Epicron" N-695 (manufactured by DIC Corporation), EOCN-1020, EOCN-102S, and EOCN-104S (manufactured by Nippon Kayaku Co., Ltd.).
An example of a commercially available resorcinol type epoxy resin is "Denacol" (registered trademark, the same applies below) EX-201 (manufactured by Nagase ChemteX Corporation).
An example of a commercially available trisphenylmethane type epoxy resin is TMH-574 (manufactured by Sumitomo Chemical Co., Ltd.).
Examples of dicyclopentadiene type epoxy resins include compounds represented by the following formula.
Commercially available dicyclopentadiene type epoxy resins include, for example, "Epicron" HP7200, "Epicron" HP7200L, "Epicron" HP7200H (manufactured by DIC Corporation), "Tactix" (registered trademark) 558 (manufactured by Huntsman Advanced Materials, Inc.), and XD-1000 (manufactured by Nippon Kayaku Co., Ltd.).
Examples of the alicyclic epoxy resin include (3',4'-epoxycyclohexane)methyl-3,4-epoxycyclohexanecarboxylate, (3',4'-epoxycyclohexane)octyl-3,4-epoxycyclohexanecarboxylate, 1-methyl-4-(2-methyloxiranyl)-7-oxabicyclo[4.1.0]heptane, limonene dioxide, 1,2-epoxy-4-vinylcyclohexane, and compounds represented by the following formula:
Commercially available products of (3',4'-epoxycyclohexane)methyl-3,4-epoxycyclohexanecarboxylate include, for example, "Celloxide" (registered trademark, the same applies below) 2021P (manufactured by Daicel Corporation) and CY179 (manufactured by Huntsman Advanced Materials).

Examples of phenolic resins include novolac-type phenolic resins such as phenol novolac resin, cresol novolac resin, naphthol novolac resin, aminotriazine novolac resin, and trisphenylmethane-type phenol novolac resin; modified phenolic resins such as terpene-modified phenolic resin and dicyclopentadiene-modified phenolic resin; aralkyl-type resins such as phenol aralkyl resins having a phenylene skeleton and/or biphenylene skeleton, and naphthol aralkyl resins having a phenylene skeleton and/or biphenylene skeleton; and resol-type phenolic resins.

Examples of the bismaleimide compound include raw materials for bismaleimide compounds having the following structures:

Examples of benzoxazine compounds other than the benzoxazine compound represented by general formula (1) include benzoxazine compounds having structures represented by the following general formulas (A) to (C).
(In the formula, Ra represents a divalent group having 1 to 30 carbon atoms, each Rb represents a monovalent group having 1 to 10 carbon atoms which may have a substituent, and each n represents independently 0 or 1.)
(In the formula, Rc represents a divalent group having 1 to 30 carbon atoms, a direct bond, an oxygen atom, a sulfur atom, a carbonyl group, or a sulfonyl group, and each Rd independently represents a monovalent group having 1 to 10 carbon atoms.)
(In the formula, each Re independently represents a monovalent group having 1 to 10 carbon atoms, and m represents 0 or 1.)

In the benzoxazine compound having a structure represented by general formula (A), Ra represents a divalent group having 1 to 30 carbon atoms. Specific examples thereof include alkylene groups such as 1,2-ethylene, 1,4-butylene, and 1,6-hexylene, alkylene groups containing a cyclic structure such as 1,4-cyclohexylene, dicyclopentadienylene, and adamantylene, and arylene groups such as 1,4-phenylene, 4,4'-biphenylene, diphenylether-4,4'-diyl, diphenylether-3,4'-diyl, diphenylketone-4,4'-diyl, and diphenylsulfone-4,4'-diyl.
In the benzoxazine compound having a structure represented by general formula (A), Rb each independently represents a monovalent group having 1 to 10 carbon atoms. Specific examples thereof include alkyl groups such as methyl, ethyl, propyl, and butyl groups, alkenyl groups such as vinyl and allyl groups, alkynyl groups such as ethynyl and propargyl groups, and aryl groups such as phenyl and naphthyl groups. These groups may further have a substituent such as an alkoxy group having 1 to 4 carbon atoms, an acyl group having 1 to 4 carbon atoms, a halogen atom, a carboxyl group, a sulfo group, an allyloxy group, a hydroxyl group, or a thiol group.
Examples of benzoxazine compounds having a structure represented by general formula (A) include Pd-type benzoxazine manufactured by Shikoku Kasei Corporation, and JBZ-OP100N and JBZ-BP100N manufactured by JFE Chemical Corporation.

In the benzoxazine compound having a structure represented by general formula (B), Rc represents a divalent group having 1 to 30 carbon atoms, a direct bond, an oxygen atom, a sulfur atom, a carbonyl group, or a sulfonyl group. Examples of the divalent group having 1 to 30 carbon atoms include alkylene groups such as methylene, 1,2-ethylene, 1,4-butylene, and 1,6-hexylene, alkylene groups containing a cyclic structure such as 1,4-cyclohexylene, dicyclopentadienylene, and adamantylene, and alkylidene groups such as ethylidene, propylidene, isopropylidene, butylidene, phenylethylidene, cyclopentylidene, cyclohexylidene, cycloheptylidene, cyclododecylidene, 3,3,5-trimethylcyclohexylidene, and fluorenylidene.
In the benzoxazine compound having a structure represented by general formula (B), Rd each independently represents a monovalent group having 1 to 10 carbon atoms. Specific examples thereof include alkyl groups such as methyl, ethyl, propyl, and butyl groups, alkenyl groups such as vinyl and allyl groups (except when Rc is a cycloalkylidene group having 5 to 20 carbon atoms), alkynyl groups such as ethynyl and propargyl groups, and aryl groups such as phenyl and naphthyl groups. These substituents may further have substituents such as alkoxy groups having 1 to 4 carbon atoms, acyl groups having 1 to 4 carbon atoms, halogen atoms, carboxyl groups, sulfo groups, allyloxy groups, hydroxy groups, and thiol groups.
Examples of benzoxazine compounds having the structure represented by general formula (B) include Fa-type benzoxazine manufactured by Shikoku Kasei Co., Ltd. and BS-BXZ manufactured by Konishi Chemical Industry Co., Ltd.

In the benzoxazine compound having a structure represented by general formula (C), each Re independently represents a monovalent group having 1 to 10 carbon atoms. Specific examples thereof include alkyl groups such as methyl, ethyl, propyl, and butyl groups, alkenyl groups such as vinyl and allyl groups, alkynyl groups such as ethynyl and propargyl groups, and aryl groups such as phenyl and naphthyl groups. These substituents may further have substituents such as alkoxy groups having 1 to 4 carbon atoms, acyl groups having 1 to 4 carbon atoms, halogen atoms, carboxyl groups, sulfo groups, allyloxy groups, hydroxy groups, and thiol groups.
In particular, the curable resin composition of the present invention preferably contains a benzoxazine compound represented by general formula (1) or a resin raw material composition containing the same, and one or more compounds selected from the group consisting of an epoxy resin, a benzoxazine compound other than the benzoxazine compound represented by general formula (1), a phenolic resin, and a bismaleimide compound.

In the curable resin composition of the present invention, the mixing amount of the benzoxazine compound represented by general formula (1) or the resin raw material composition containing the same and the other polymer materials is in the range of 0.01 parts by weight to 100 parts by weight per 1 part by weight of the benzoxazine compound represented by general formula (1) or the resin raw material composition containing the same.
The curable resin composition of the present invention can be obtained by adding the benzoxazine compound represented by the general formula (1) or a resin raw material composition containing the same to the polymeric material as necessary, but the method of addition is not particularly limited and any conventionally known method can be used. For example, the method of adding the compound during synthesis or polymerization of the polymeric material, the method of adding a resin made of the polymeric material to a molten resin melted in, for example, a melt extrusion process, and the like, and the method of impregnating a resin product made of the polymeric material can be mentioned.
In the curable resin composition of the present invention, if the composition contains water or residual solvent, bubbles will be generated during curing, so it is preferable to perform a vacuum degassing treatment as a pretreatment to prevent this. The temperature of this vacuum degassing treatment is not particularly limited as long as it is a temperature at which the curable resin composition of the present invention is in a molten state, but it is preferable to perform the treatment with an upper limit of 150°C because curing does not proceed and degassing is easy. The pressure of the vacuum degassing treatment is not particularly limited, but it is better to have a low pressure (high degree of vacuum), and it may be performed either in air or in a nitrogen-substituted atmosphere. This vacuum degassing treatment is performed until bubbles can no longer be visually confirmed.
The curable resin composition of the present invention can be used in combination with inorganic fillers such as silicon oxide, aluminum oxide, magnesium oxide, boron nitride, aluminum nitride, silicon nitride, silicon carbide, and hexagonal boron nitride, or reinforcing fibers such as carbon fiber, glass fiber, organic fiber, boron fiber, steel fiber, and aramid fiber, depending on the needs of the application.

<Cured product obtained by curing the curable resin composition of the present invention>
The cured product of the present invention can be obtained by curing the curable resin composition of the present invention, which contains, as an essential component, the benzoxazine compound represented by general formula (1) of the present invention or a resin raw material composition containing the same.
Examples of methods for producing the cured product of the present invention include a method of heating to a predetermined temperature to cure, a method of heating and melting the composition and pouring it into a mold or the like and further heating the mold to cure and mold it, a method of injecting the molten material into a pre-heated mold to cure it, a method of preparing a varnish containing the curable resin composition of the present invention and a solvent, removing the solvent and drying the mixture, pouring it into a mold and heating to cure it, and a method of preparing a varnish, casting it on a support such as a polyimide or polyester film, or a glass substrate, removing the solvent and drying the resulting film, and heating to cure it.

The cured product of the present invention can be cured by ring-opening polymerization under the same curing conditions as those for ordinary benzoxazine. The curing temperature is usually in the range of 70 to 300° C., preferably in the range of 100 to 280° C., and more preferably in the range of 100 to 260° C., but in order to improve the mechanical properties of the obtained cured product, it is particularly preferable to set the temperature in the range of 100 to 240° C. When curing is performed in such a temperature range, the reaction time may be about 1 to 10 hours.
Although the resin composition of the present invention can be cured only by heat, depending on the components other than the benzoxazine compound represented by the general formula (1) and their contents, it is preferable to use a curing accelerator. The curing accelerator that can be used is not particularly limited, and examples thereof include tertiary amines such as 1,8-diaza-bicyclo[5.4.0]undecene-7, triethylenediamine, and tris(2,4,6-dimethylaminomethyl)phenol, imidazoles such as 2-ethyl-4-methylimidazole and 2-methylimidazole, phosphorus compounds such as triphenylphosphine, tetraphenylphosphonium bromide, tetraphenylphosphonium tetraphenylborate, and tetra-n-butylphosphonium-O,O-diethylphosphorodithioate, quaternary ammonium salts, organic metal salts, and derivatives thereof. These may be used alone or in combination. Among these curing accelerators, it is preferable to use tertiary amines, imidazoles, and phosphorus compounds.

The benzoxazine compound of the present invention, and the resin raw material composition and curable resin composition containing the same can be suitably used as resin raw materials for varnishes that can be applied to various substrates, prepregs impregnated with the varnish, copper-clad laminates, printed circuit boards, sealants for semiconductors and electronic components, electrical and electronic molded parts, automobile parts, laminates, paints, resist inks, etc., and the cured products can be suitably used as material resins for these products. Among these, the cured products obtained using the benzoxazine compound of the present invention have excellent heat resistance and dielectric properties, and are therefore useful as resin materials for prepregs, copper-clad laminates, printed circuit boards, sealants for semiconductors and electronic components, and electrical and electronic molded parts.

The present invention will now be described more specifically with reference to examples.
<Analysis method>
1. Liquid Chromatography: LC
Measurement device: High performance liquid chromatography Analysis device: Prominence UFLC (Shimadzu Corporation)
Pump: LC-20AD
Column oven: CTO-20A
Detector: SPD-20A
Column: HALO-C18 (inner diameter 3 mm, length 75 mm)
Oven temperature: 50°C
Flow rate: 0.7 mL/min.
Detection wavelength: 280 nm
Mobile phase: (A) 0.2% by volume acetic acid aqueous solution, (B) tetrahydrofuran Gradient conditions: (A) vol.% (time from start of analysis)
20% (0 min.) → 40% (10 min.) → 60% (20 min.) → 100% (37 min.) → 100% (40 min.)
2. Gel Permeation Chromatography: GPC
Apparatus: HLC-8320/Tosoh Corporation Detector: Differential refractometer (RI)
[Measurement condition]
Flow rate: 1 mL/min.
Eluent: Tetrahydrofuran Temperature: 40°C
Wavelength: 254 nm
Sampling pitch: 100 sec.
Measurement sample: 10 mg of benzoxazine compound diluted 50 times with tetrahydrofuran Injection volume: 10 μL
[Column] (from upstream)
Guard Column HXL-L + G4000HXL + G3000HXL + G2000HXL x 2 (7.8mm ID x 30cm, Tosoh Corporation)
3. NMR analysis Measurement device: Fourier transform nuclear magnetic resonance AVANCE III HD 400 (manufactured by BRUKER)
The measurement sample was dissolved in deuterated chloroform, and the ¹ H-NMR spectrum was measured.
4. Measurement of glass transition temperature (Tg) (dynamic mechanical analysis (DMA))
Apparatus: DMA850/manufactured by TA Instruments Japan, Inc. Measurement conditions: 3-point bending Measurement temperature: 30 to 310°C
Measurement frequency: 1.0 (Hz)
Sample dimensions: (60mm x 15mm x 2mm)
Heating rate: 1.0° C./min.
5. Evaluation of Dielectric Properties The films (sample size: width 1.5 mm, length 8.0 mm) prepared in the examples and comparative examples were measured for relative dielectric constant and dielectric loss tangent using the following device (sample size: width 1.5 mm, length 8.0 mm).
Measurement device: PNA network analyzer N522B (Keysight Technologies, Inc.)
Cavity resonator: CP531 for 10 GHz (manufactured by Kanto Electronics Application Development Co., Ltd.)
[Measurement condition]
Test method: Compliant with IEC 62180 (cavity resonator perturbation method)
Test conditions: Frequency: 10 GHz
Number of measurements: n = 2

Example 1 (Synthesis of the benzoxazine compound of the present invention represented by formula (1-4))
In a 2L four-neck flask equipped with a thermometer, a stirrer, a cooling tube, and a dropping funnel, 130 g (1.3 mol) of allylamine hydrochloride was added, and then 110 g (1.3 mol) of 48% NaOH aqueous solution was added slowly over 5 minutes while stirring, while checking the temperature rise. After that, after it was confirmed that the pH of the aqueous layer was about 9 to 10, 107 g (3.3 mol) of paraformaldehyde (purity: 92%) was added in small portions over 30 minutes. At this time, it was confirmed that the temperature of the reaction system rose from 30°C to 55°C. Then, it was air-cooled while stirring, and after it was confirmed that the temperature had dropped to 30°C, it was stirred at 30°C for 1 hour.
After the stirring was completed, 586 g of ethyl acetate and 210 g of 1,1-bis(4-hydroxyphenyl)-3,3,5-trimethylcyclohexane were added to the flask. The temperature of the liquid in the flask was then raised to 55° C., and the reaction was carried out for 24 hours, 3 hours at 60° C., 5 hours at 65° C., and 1 hour at 70° C., and the disappearance of 1,1-bis(4-hydroxyphenyl)-3,3,5-trimethylcyclohexane was confirmed. The temperature of the liquid in the flask was cooled to 40° C. Analysis of the reaction liquid by GPC showed that the proportion of benzoxazine compounds present in the reaction liquid was 75 area %, and the remaining 25 area % was a compound with a higher molecular weight than the benzoxazine compound (high molecular weight component).
The reaction mixture was mixed with 400 g of pure water, stirred for 30 minutes, and then left to stand to confirm separation from the organic layer, after which the aqueous layer was removed. This water washing procedure was repeated six times, and it was confirmed that the pH of the aqueous layer was 7 to 8.
Thereafter, the solvent was removed by distillation under reduced pressure at 40° C. After the solvent was distilled off, the mixture was cooled to obtain a solid benzoxazine compound with no fluidity. The result of measuring the obtained benzoxazine compound by GPC under the above-mentioned analytical conditions was that the purity was 70 area % and the content of high molecular weight components was 30 area %.
The obtained distillation residue was heated to 90°C, poured into a metal tray, cooled to room temperature, and crushed to obtain 250 g of a yellow solid benzoxazine compound. The amount of the solvent contained in the solid was 1.0 wt %. The yield was 78 mol % based on the 1,1-bis(4-hydroxyphenyl)-3,3,5-trimethylcyclohexane used.
The solid thus obtained was analyzed by ¹ H-NMR, and as a result, peaks derived from 3,3,5-trimethylcyclohexylidene groups were observed around 0.4 and 0.8-1.0 ppm, a peak derived from the benzoxazine moiety was observed around 3.3-4.0 ppm, a peak derived from allylamine was observed around 4.8-5.2 ppm, and a peak derived from aromatics was observed around 6.6-7.3 ppm. ^{The 1} H-NMR spectrum is shown in FIG. 1. From the results of this analysis, it was revealed that the target compound was a benzoxazine compound represented by formula (1-4).

Example 2 (Synthesis of the benzoxazine compound of the present invention represented by formula (1-5))
In a 2L four-neck flask equipped with a thermometer, a stirrer, a cooling tube, and a dropping funnel, 120 g (1.2 mol) of allylamine hydrochloride was added, and then 101 g (1.2 mol) of 48% NaOH aqueous solution was added slowly over 5 minutes while stirring, while checking the temperature rise. After that, after it was confirmed that the pH of the aqueous layer was about 9 to 10, 96 g (3.0 mol) of paraformaldehyde (purity: 92%) was added in small portions over 1 hour. At this time, it was confirmed that the temperature of the reaction system rose from 30°C to 45°C. Then, it was air-cooled while stirring, and after it was confirmed that the temperature had dropped to 30°C, it was stirred at 30°C for 1 hour.
After the stirring was completed, 584 g of ethyl acetate and 211 g of 1,1-bis(4-hydroxyphenyl)cyclododecane were added to the flask. The temperature of the liquid in the flask was then raised to 55° C., and the reaction was carried out for 32 hours. Since 1,1-bis(4-hydroxyphenyl)cyclododecane remained, the reaction was further carried out at 60° C. for 4 hours, and the disappearance of 1,1-bis(4-hydroxyphenyl)cyclododecane was confirmed. The temperature of the liquid in the flask was cooled to 40° C. As a result of analyzing the reaction liquid by GPC, the proportion of benzoxazine compounds present in the reaction liquid was 73 area %, and the remaining 27 area % was a compound (high molecular weight component) having a higher molecular weight than the benzoxazine compound.
The reaction mixture was mixed with 400 g of pure water, stirred for 30 minutes, and then left to stand to confirm separation from the organic layer, after which the aqueous layer was removed. This water washing procedure was repeated six times, and it was confirmed that the pH of the aqueous layer was 7 to 8.
Thereafter, the solvent was removed by distillation under reduced pressure at 40° C. After the solvent was distilled off, the mixture was cooled to obtain a solid benzoxazine compound with no fluidity. The result of measuring the obtained benzoxazine compound by GPC under the above-mentioned analytical conditions was that the purity was 70 area % and the content of high molecular weight components was 30 area %.
The obtained distillation residue was heated to 90°C, poured into a metal tray, cooled to room temperature, and crushed to obtain 308 g of a yellow solid benzoxazine compound. The amount of the solvent contained in the solid was 9.9 wt %. The yield was 90 mol % based on the 1,1-bis(4-hydroxyphenyl)cyclododecane used.
The solid was analyzed by ¹ H-NMR, and the peaks derived from cyclododecane were observed at around 0.4 and 0.8-1.0 ppm, the peaks derived from benzoxazine were observed at around 3.3-4.0 ppm, the peaks derived from allylamine were observed at around 4.8-5.2 ppm, and the peaks derived from aromatic compounds were observed at around 6.6-7.3 ppm. ^{The 1} H-NMR spectrum is shown in FIG. 2. From the results of this analysis, it was revealed that the target compound was a benzoxazine compound represented by formula (1-5).

Comparative Synthesis Example 1 (Synthesis of benzoxazine compound represented by formula (i))
19.5 g of water and 19.5 g of NaOH (granular) were charged into a 500 mL four-neck flask equipped with a thermometer, a stirrer, and a cooling tube, and stirred. 19.5 g of allylamine hydrochloride was added to this alkaline solution, and the mixture was stirred for 1 hour under a nitrogen atmosphere. Then, 39.1 g of paraformaldehyde (purity: 92%) was added little by little, and the mixture was stirred for 5 hours. 93 g of ethyl acetate and 50 g of bisphenol F were added to this solution, and the mixture was stirred at 30 to 40 ° C for 13 hours. During the process, 46 g of ethyl acetate was added because the viscosity increased. The disappearance of bisphenol F was confirmed by high performance liquid chromatography (HPLC). As a result of analyzing the reaction solution by GPC, the proportion of the benzoxazine compound represented by formula (i) present in the reaction solution was 65 area %, and the remaining 35 area % was a high molecular weight component.
After the reaction was completed, the salt and unreacted paraformaldehyde were removed by filtration, and the filtrate was washed five times with 50 mL of water.
The washed filtrate was distilled under reduced pressure at 40° C. to remove the solvent. The pressure during distillation was gradually reduced to a final pressure of 1.4 kPa.
After distilling off the solvent, the mixture was cooled to obtain 55 g of a benzoxazine compound represented by formula (i) as a fluid oily product. The amount of the solvent contained in the oily product was 1.0 wt %. The result of measuring the obtained oily product by GPC under the above analytical conditions showed that the purity was 61 area % and the high molecular weight component was 39 area %.

(Evaluation of storage stability)
5 g of the benzoxazine compounds obtained in Examples 1 and 2 and Comparative Synthesis Example 1 were added to test tubes in the atmosphere and sealed, and then the test tubes containing the samples were placed in a thermostatic chamber and heated under the temperature and time conditions shown in Table 1 below. The purity before and after heating was measured by GPC, and the change in purity was calculated. The results are summarized in Table 1.

As shown in Table 1, the purity of the benzoxazine compound represented by formula (i) obtained in Comparative Synthesis Example 1 decreased by 5.4 area % after storage for 7 days at room temperature (30° C.), and decreased by 29.7 area % after storage for 7 hours at a higher temperature of 50° C., compared to that before heating.
From these results, it became clear that the benzoxazine compound represented by formula (i) undergoes a polymerization reaction during storage, resulting in a decrease in purity, and therefore poses a problem in handling it as a resin raw material.
On the other hand, the purity of the compound of formula (1-4) obtained in Example 1 of the present invention did not change at room temperature (30° C.) and at a higher temperature of 50° C., compared with that before heating, and therefore it was revealed that the compound can be stored for a long period of time.
In addition, the purity of the compound of formula (1-5) obtained in Example 2 did not change under high temperature conditions of 50° C. compared with that before heating, and the change was suppressed under room temperature conditions (30° C.), making it clear that the compound can be stored for a long period of time.

Example 3
15 g of the compound of formula (1-4) obtained in Example 1, 16.5 g of dicyclopentadiene type epoxy resin (manufactured by Nippon Kayaku Co., Ltd.: trade name "XD-1000"), 0.64 g of triphenylphosphine as a curing accelerator, and 40.0 g of methyl ethyl ketone were left to stand until completely dissolved. After preparing a varnish in which each component was completely dissolved, the solution was transferred to a tray and dried overnight in a draft, and then dried in a vacuum dryer at 60 ° C. for 4 to 5 hours. Thereafter, the film of the obtained composition was added to a mold (φ100 mm press mold) and cured at 3 MPa under the conditions of 100 ° C. / 1 hour and 130 ° C. / 2 hours in a heat press tester. Thereafter, post-curing treatment was performed in a hot air circulation oven at 140 ° C. / 2 hours, 150 ° C. / 2 hours, 160 ° C. / 2 hours, and 180 ° C. / 2 hours to obtain a cured product.

Comparative Synthesis Example 2
A cured product was obtained in the same manner as in Example 3, except that 10.0 g of a novolac type curing agent (manufactured by Aica Kogyo Co., Ltd.: product name "BRG-555"), 24.0 g of a dicyclopentadiene type epoxy resin (manufactured by Nippon Kayaku Co., Ltd.: product name "XD-1000"), 0.64 g of triphenylphosphine, and 40.0 g of methyl ethyl ketone were used.

The glass transition temperature (Tg) and dielectric properties of the cured products obtained in Example 3 and Comparative Synthesis Example 2 were measured under the above-mentioned analytical conditions. The results are shown in Table 2.

It was confirmed that by using the compound of formula (1-4) obtained in Example 1 as a component of a curable resin, the obtained cured product exhibits good heat resistance (Tg) and dielectric properties.
From the above, it has become clear that the benzoxazine compound of the present invention can give a cured product having excellent heat resistance and dielectric properties by mixing it with an epoxy resin or the like to form a curable resin composition.
For these reasons, it is extremely useful as a resin material for prepregs, copper-clad laminates, printed circuit boards, sealants for semiconductors and electronic components, electric and electronic molded parts, automobile parts, laminates, paints, resist inks, and the like.

Claims (7)

A benzoxazine compound represented by general formula (1):
(In the formula, each R ₁ independently represents an alkylene group having 1 to 4 carbon atoms, and X represents a cycloalkylidene group having 5 to 20 carbon atoms.) The benzoxazine compound according to claim 1, wherein X is a cyclohexylidene group, a 3-methylcyclohexylidene group, a 4-methylcyclohexylidene group, a 3,3,5-trimethylcyclohexylidene group, or a cyclododecanylidene group. A resin raw material composition containing the benzoxazine compound according to claim 1. The resin raw material composition according to claim 3, wherein the content of the benzoxazine compound represented by the general formula (1) is in the range of 10 to 100 area % relative to the area of all peaks detected by analysis by gel permeation chromatography using a differential refractometer as a detector. A curable resin composition comprising the benzoxazine compound according to claim 1 or the resin raw material composition according to claim 3. The curable resin composition according to claim 5, which contains the benzoxazine compound according to claim 1 or the resin raw material composition according to claim 3, and one or more selected from the group consisting of an epoxy resin, a benzoxazine compound other than the benzoxazine compound represented by the general formula (1), a phenolic resin, and a bismaleimide compound. A cured product obtained by curing the curable resin composition according to claim 5 .