Curable resin composition, varnish, cured product, method for producing a cured product

Abstract

The present invention addresses the problem of providing a means with which it is possible to inhibit a volatile component (sulfur-containing volatile component) which has an odor generated during production of a cured product by means of a curable resin composition containing a benzoxazine compound having a thiol group. The problem is solved by providing a curable resin composition containing 100 parts by weight of a component (A) and a range of 5-2,000 parts by weight of at least one component among a component (B) and a component (C).　(A): A benzoxazine compound represented by general formula (1).　(B): A compound having a cyclic ether group that has a three- or four-membered ring.　(C): A compound having a reactive group that includes a carbon-carbon double bond or a carbon-carbon triple bond.

Description

Technical Field

[0001] The present invention relates to a curable resin composition, a varnish, a cured product, and a method for producing a cured product, which contain a benzoxazine compound having benzoxazine rings at both ends of a linking group and further having a thiol group, and a specific curing agent.

Background Art

[0002] Benzoxazine compounds are known as thermosetting resin raw materials that cure by ring-opening polymerization of the benzoxazine ring without generating volatile by-products upon heating, and are used as raw materials for molded articles, liquid crystal alignment agents, resin compositions for semiconductor encapsulation, etc. that can be used as materials for insulating substrates. On the other hand, the curing temperature of ordinary benzoxazine compounds is relatively high, and in recent years, catalysts, polymerization accelerators, and highly reactive benzoxazine compounds have been developed to lower the polymerization temperature. Among these highly reactive benzoxazine compounds, a hydroxy-functional benzoxazine composition in which a hydroxy group is introduced into the structure has been reported (Patent Document 1). However, in order to lower the temperature in the molding process of thermosetting resins, improve efficiency by shortening the heating and cooling times and energy savings, and suppress thermal degradation of materials due to exposure to high temperatures during polymerization, excellent materials that can be cured under low temperature conditions are desired. Under such circumstances, the present inventor invented a benzoxazine compound having benzoxazine rings at both ends of a linking group and further having a thiol group as a novel benzoxazine compound that can be cured under low temperature conditions, and filed a patent application (Patent Document 2).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

[0004] In a study on the production of cured products using a benzoxazine compound represented by the following general formula (1) among the benzoxazine compounds having a thiol group, it was found that under the curing conditions described in Patent Document 2, when the curable resin composition cured, a decrease in weight and the generation of volatile components with an odor occurred before and after curing. [ka] (In the formula, R1 independently represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms; R2 independently represents an alkylene group having 1 to 10 carbon atoms, including a linear, branched, or aliphatic ring; and X represents a single bond, an oxygen atom, a sulfur atom, a sulfonyl group, a carbonyl group, or a divalent group represented by formula 1a or formula 1b below.) [ka] (In formulas 1a and 1b, R3 and R4 each independently represent hydrogen, an alkyl group having 1 to 10 carbon atoms, an alkyl halide having 1 to 10 carbon atoms, or an aryl group having 6 to 12 carbon atoms. R3 and R4 may also be bonded to each other to form a cycloalkylidene group having 5 to 20 carbon atoms. Ar1 and Ar2 each independently represent an aryl group having 6 to 12 carbon atoms. * indicates the bond position.) When volatile components are generated during the manufacturing of cured products, vacuum voids are created inside the cured product, making those areas brittle and reducing mechanical strength. This can lead to problems such as poor quality cured products, shrinkage of the cured product during volatilization, and poor dimensional stability. Furthermore, volatile components with odors are undesirable from a safety, hygiene, and environmental standpoint, requiring measures such as introducing equipment that prevents their release outside the system. The inventors have clarified that the volatile component with an odor is generated when the benzoxazine compound represented by general formula (1) decomposes during thermal curing, and that this is a sulfur-containing volatile component. They hypothesize that the generation of this volatile component with an odor (sulfur-containing volatile component) is due to a change in the thiol group portion of the benzoxazine structure, as shown in the following formula. [ka] (In the formula, R1 and R2 have the same definitions as in general formula 1.) For example, when R2 of a benzoxazine compound represented by general formula (1) is an ethylene group, the volatile component (sulfur-containing volatile component) that produces an odor during curing is thiazolidine. Given the above background, the objective is to provide a means for suppressing odorous volatile components (sulfur-containing volatile components) generated during the production of cured products using a curable resin composition containing a benzoxazine compound represented by general formula (1). Furthermore, since the glass transition temperature of a cured product using only the benzoxazine compound having a thiol group described in Patent Document 2 is lower than that of existing Fa-type benzoxazines, the objective is to provide a cured product with further improved heat resistance. [Means for solving the problem]

[0005] As a result of diligent research to solve the above-mentioned problems, the inventors of the present invention have found that by using a composition containing a benzoxazine compound having a thiol group and a compound having a specific reactive group, the generation of volatile components (sulfur-containing volatile components) that produce an odor during curing can be suppressed, and have completed the present invention. Furthermore, it was found that the resulting cured product exhibited significantly improved heat resistance compared to cured products using only benzoxazine compounds containing thiol groups.

[0006] The present invention is as follows: 1. A curable resin composition containing 100 parts by weight of component (A) and at least one of components (B) and (C) in an amount ranging from 5 to 2000 parts by weight. (A): A benzoxazine compound represented by the following general formula (1). [ka] (In the formula, R1 independently represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms; R2 independently represents an alkylene group having 1 to 10 carbon atoms, including a linear, branched, or aliphatic ring; and X represents a single bond, an oxygen atom, a sulfur atom, a sulfonyl group, a carbonyl group, or a divalent group represented by formula 1a or formula 1b below.) [ka] (In formulas 1a and 1b, R3 and R4 each independently represent hydrogen, an alkyl group having 1 to 10 carbon atoms, an alkyl halide having 1 to 10 carbon atoms, or an aryl group having 6 to 12 carbon atoms. R3 and R4 may also be bonded to each other to form a cycloalkylidene group having 5 to 20 carbon atoms. Ar1 and Ar2 each independently represent an aryl group having 6 to 12 carbon atoms. * indicates the bond position.) (B): Compounds having a cyclic ether group of three or four members. (C): A compound having a reactive group containing a carbon-carbon double bond or a carbon-carbon triple bond. 2. The curable resin composition described in 1., which contains the following component (D). (D): Curing reaction catalyst 3. The curable resin composition according to 2, wherein the curing reaction catalyst is an acid catalyst. 4. A curable resin composition according to any one of items 1 to 3, further comprising the following component (E). (E): Filler A varnish containing the curable resin composition described in 5.1 and the following component (F). (F): Organic solvent A cured product obtained by curing the curable resin composition described in 6.1. 7. A method for producing a cured product containing component (A), which comprises curing a curable resin composition containing the following component (A) and at least one of the following components (B) and component (C). (A): A benzoxazine compound represented by the following general formula (1). [Chemical formula] (In the formula, each R1 independently represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, each R2 independently represents a linear, branched or aliphatic ring-containing alkylene group having 1 to 10 carbon atoms, and X represents a single bond, an oxygen atom, a sulfur atom, a sulfonyl group, a carbonyl group, or a divalent group represented by the following formula 1a or formula 1b.) [Chemical formula] (In formula 1a and formula 1b, each of R3 and R4 independently represents hydrogen, an alkyl group having 1 to 10 carbon atoms, a halogenated alkyl group having 1 to 10 carbon atoms or an aryl group having 6 to 12 carbon atoms, and R3 and R4 may be bonded to each other to form a cycloalkylidene group having 5 to 20 carbon atoms as a whole, each of Ar1 and Ar2 independently represents an aryl group having 6 to 12 carbon atoms, and * represents a bonding position respectively.) (B): A compound having a 3- or 4-membered cyclic ether group. (C): A compound having a reactive group containing a carbon-carbon double bond or a carbon-carbon triple bond. 8. The method for producing a cured product according to 7., wherein the method for producing the cured product includes a pre-curing step with a temperature condition in the range of 60°C to 150°C and a curing step with a temperature condition in the range of 150°C to 240°C. 9. The method for producing a cured product according to 7. or 8., wherein the curable resin composition further contains the following component (D). (D): A curing reaction catalyst 10. The method for producing a cured product according to 9., wherein the curing reaction catalyst is an acid catalyst. [Advantages of the Invention]

[0007] The curable resin composition of the present invention, comprising a benzoxazine compound having a thiol group and a compound having a specific reactive group, can suppress the generation of volatile components (sulfur-containing volatile components) that produce an odor during curing. Furthermore, the cured product obtained from this curable resin composition has excellent heat resistance. Furthermore, the method for producing a cured product using a curable resin composition containing a benzoxazine compound having a thiol group according to the present invention can suppress the generation of odorous volatile components (sulfur-containing volatile components) during production by curing a curable resin composition containing a benzoxazine compound having a thiol group and a compound having a specific reactive group. [Brief explanation of the drawing]

[0008] [Figure 1] This figure shows the dynamic viscoelastic analysis (DMA) chart of the cured product obtained in Example 14. [Figure 2] This figure shows the dynamic viscoelastic analysis (DMA) chart of the cured product obtained in Comparative Example 3. [Modes for carrying out the invention]

[0009] <Curable resin composition of the present invention> The curable resin composition of the present invention contains 100 parts by weight of component (A) as described below, and at least one of the following components (B) and (C) in an amount ranging from 5 to 2000 parts by weight.

[0010] <Component (A): Benzoxazine compound represented by general formula (1)> Component (A) is a benzoxazine compound represented by the following general formula (1). [ka] (In the formula, R1 independently represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms; R2 independently represents an alkylene group having 1 to 10 carbon atoms, including a linear, branched, or aliphatic ring; and X represents a single bond, an oxygen atom, a sulfur atom, a sulfonyl group, a carbonyl group, or a divalent group represented by formula 1a or formula 1b below.) [ka] (In formulas 1a and 1b, R3 and R4 each independently represent hydrogen, an alkyl group having 1 to 10 carbon atoms, an alkyl halide having 1 to 10 carbon atoms, or an aryl group having 6 to 12 carbon atoms. R3 and R4 may also be bonded to each other to form a cycloalkylidene group having 5 to 20 carbon atoms. Ar1 and Ar2 each independently represent an aryl group having 6 to 12 carbon atoms. * indicates the bond position.) In general formula (1), R1 is preferably independently a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, more preferably a hydrogen atom or an alkyl group having 1 carbon atom (methyl group), and particularly preferably a hydrogen atom. When R1 is not a hydrogen atom, the bond position is preferably the ortho position on the benzene ring relative to the oxygen atom of the benzoxazine ring. In general formula (1), R2 is an alkylene group having 1 to 10 carbon atoms, which is either linear, branched, or contains an aliphatic ring. Specifically, examples include a methylene group, an ethylene group, a propane-1,2-diyl group, a propane-1,3-diyl group, a butane-1,4-diyl group, a pentane-1,5-diyl group, a hexane-1,6-diyl group, a cyclohexane-1,3-diyl group, and a cyclohexane-1,4-diyl group. Among these, the ethylene group, a propane-1,2-diyl group, a propane-1,3-diyl group, and a butane-1,4-diyl group are particularly preferred. Among these, R2 is preferably a linear or branched alkylene group having 1 to 10 carbon atoms, more preferably a linear or branched alkylene group having 1 to 6 carbon atoms, even more preferably a linear or branched alkylene group having 1 to 4 carbon atoms, and particularly preferably a linear or branched alkylene group having 2 to 4 carbon atoms.

[0011] When X in the above general formula (1) is formula (1a), more preferred R3 and R4 are, independently, hydrogen, an alkyl group having 1 to 6 carbon atoms, a halogenated alkyl group having 1 to 6 carbon atoms, or an aryl group having 6 to 12 carbon atoms, and even more preferably hydrogen, an alkyl group having 1 to 4 carbon atoms, a trifluoromethyl group, or an aryl group having 6 to 8 carbon atoms, and particularly preferably hydrogen, an alkyl group having 1 to 4 carbon atoms, or a phenyl group. Furthermore, R3 and R4 may bond to each other to form a cycloalkylidene group having 5 to 20 carbon atoms in total. The cycloalkylidene group having 5 to 20 carbon atoms may include an alkyl group as a branched chain. The cycloalkylidene group preferably has 5 to 15 carbon atoms, more preferably 6 to 12 carbon atoms, and particularly preferably 6 to 9 carbon atoms. Examples of cycloalkylidene groups include, for example, cyclopentylidene group (5 carbon atoms), cyclohexylidene group (6 carbon atoms), 3-methylcyclohexylidene group (7 carbon atoms), 4-methylcyclohexylidene group (7 carbon atoms), 3,3,5-trimethylcyclohexylidene group (9 carbon atoms), cycloheptylidene group (7 carbon atoms), and cyclododecanylidene group (12 carbon atoms). Preferably, the group is cyclohexylidene group (6 carbon atoms), 3-methylcyclohexylidene group (7 carbon atoms), 4-methylcyclohexylidene group (7 carbon atoms), 3,3,5-trimethylcyclohexylidene group (9 carbon atoms), or cyclododecanylidene group (12 carbon atoms), and more preferably, cyclohexylidene group (6 carbon atoms), 3,3,5-trimethylcyclohexylidene group (9 carbon atoms), or cyclododecanylidene group (12 carbon atoms). In the above general formula (1), when X is formula (1b), preferred Ar1 and Ar2 are, independently, a benzene ring and a naphthalene ring, and it is more preferable that both Ar1 and Ar2 are benzene rings. For example, when both Ar1 and Ar2 are benzene rings, the group represented by formula (1b) is a fluorenylidene group. In general formula (1), the bond position between X and the two benzoxazine rings is preferably at the ortho or para position on the benzene ring relative to the oxygen atom of the benzoxazine ring.

[0012] Specific examples of benzoxazine compounds represented by general formula (1) according to the present invention are shown below, which have the following chemical structures: compounds (p-1) to (p-63). Of these, compounds (p-1) to (p-42), compounds (p-46) to (p-48), and compounds (p-52) to (p-63) are preferred, and compounds (p-1) to (p-15), compounds (p-22) to (p-30), compounds (p-34) to (p-42), and compounds (p-52) to (p-63) are more preferred. [ka] [ka] [ka]

[0013] [ka] [ka] [ka]

[0014] There are no particular restrictions on the starting materials or manufacturing methods for the benzoxazine compound represented by general formula (1) according to the present invention. For example, as illustrated in the reaction equation below, a manufacturing method can be used to obtain the target benzoxazine compound represented by general formula (1) by cyclizing a bisphenol compound represented by general formula (2), an aminothiol compound represented by general formula (3), and formaldehyde through a dehydration condensation reaction. [ka] (In the formula, R1, R2, and X are the same as defined in general formula 1.)

[0015] In the above manufacturing method, a bisphenol compound represented by general formula (2), an aminothiol compound represented by general formula (3), and formaldehydes are used as starting materials. Examples of bisphenol compounds represented by general formula (2) include, for example, bisphenol F (bis(2-hydroxyphenyl)methane, 2-hydroxyphenyl-4-hydroxyphenylmethane, bis(4-hydroxyphenyl)methane), bisphenol E (1,1-bis(4-hydroxyphenyl)ethane), bisphenol A (2,2-bis(4-hydroxyphenyl)propane), bisphenol C (2,2-bis(4-hydroxy-3-methylphenyl)propane), 2,2-bis(4-hydroxyphenyl)-4-methylpentane, 4,4'-dihydroxybiphenyl, 4,4'-dihydroxy-3,3'-dimethylbiphenyl, bis(4-hydroxyphenyl) ether, and 4,4'-dihydroxybenzophenone. Examples include bis(4-hydroxyphenyl)sulfone, bis(4-hydroxyphenyl)sulfide, 1,1-bis(4-hydroxyphenyl)-1-phenylethane, 1,1-bis(4-hydroxyphenyl)-1-naphthylethane, 2,2-bis(4-hydroxyphenyl)hexafluoropropane, bisphenol M (1,3-bis(2-(4-hydroxyphenyl)-2-propyl)benzene), bisphenol Z (1,1-bis(4-hydroxyphenyl)cyclohexane), bisphenol TMC (1,1-bis(4-hydroxyphenyl)-3,3,5-trimethylcyclohexane), 1,1-bis(4-hydroxyphenyl)cyclododecane, and 9,9-bis(4-hydroxy-3-methylphenyl)fluorene. Examples of aminothiol compounds represented by general formula (3) include, for example, 2-aminoethanethiol, 3-amino-1-propanthol, 2-amino-1-methylethanethiol, 2-amino-2-methylethanethiol, 5-amino-1-pentanethiol, and 6-amino-1-hexanethiol. Among these, 2-aminoethanethiol, 3-amino-1-propanthol, 2-amino-1-methylethanethiol, 2-amino-2-methylethanethiol, 5-amino-1-pentanethiol, and 6-amino-1-hexanethiol are preferred, 2-aminoethanethiol, 3-amino-1-propanthol, and 2-amino-1-methylethanethiol are more preferred, and 2-aminoethanethiol is particularly preferred. Examples of formaldehydes include, for instance, aqueous formaldehyde solutions, 1,3,5-trioxane, and paraformaldehyde.

[0016] In the above manufacturing method, the amount of formaldehyde used is preferably in the range of 4.0 to 20.0 moles, more preferably in the range of 4.0 to 16.0 moles, and even more preferably in the range of 4.0 to 12.0 moles, per mole of the bisphenol compound represented by general formula (2). In the above manufacturing method, the amount of aminothiol compound represented by general formula (3) used is preferably in the range of 2.0 to 10.0 moles, more preferably in the range of 2.0 to 8.0 moles, and even more preferably in the range of 2.0 to 6.0 moles, per mole of bisphenol compound represented by general formula (2).

[0017] While a catalyst is not particularly necessary to accelerate the reaction, an acid catalyst or a base catalyst may be used if necessary. Examples of usable acid catalysts include concentrated hydrochloric acid, hydrochloric acid gas, trifluoroacetic acid, methanesulfonic acid, p-toluenesulfonic acid, benzoic acid, and mixtures thereof. Examples of usable base catalysts include, but are not limited to, sodium hydroxide, sodium carbonate, triethylamine, triethanolamine, and mixtures thereof. The reaction is usually carried out in the presence of a solvent. While there are no particular restrictions on the solvent as long as it does not inhibit the reaction, toluene, xylene, ethyl acetate, butyl acetate, chloroform, dichloromethane, tetrahydrofuran, and dioxane are preferred. These solvents can be used alone or in combination. Furthermore, there are no particular restrictions on the amount of solvent used as long as it does not hinder the reaction, but it is usually used in an amount of 0.5 to 5 times the weight of the bisphenol compound represented by general formula (2), preferably in an amount of 1 to 3 times the weight. The reaction temperature is usually in the range of 10 to 150°C, preferably in the range of 10 to 120°C, more preferably in the range of 10 to 80°C, even more preferably in the range of 20 to 70°C, and particularly preferably in the range of 20 to 60°C. The reaction may be carried out under normal pressure, under pressurized pressure, or under reduced pressure. In another embodiment, the procedure may include removing water originating from the raw materials or water generated during the reaction from the system. The procedure for removing water generated from the reaction solution is not particularly limited and can be carried out by azeotropic distillation of the generated water with the solvent system in the reaction solution. The generated water can be removed from the reaction system using, for example, an isobaric dropping funnel with a stopcock, a Diemroth condenser, a Dean-Stark apparatus, etc.

[0018] The resulting reaction mixture can be used to obtain a benzoxazine compound represented by general formula (1) from this mixture by known methods after the reaction is complete. For example, after the reaction, the reaction mixture may be subjected to treatments such as deactivation of 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. Alternatively, the target product can be obtained by adding the residual liquid to a poor solvent and precipitating it, or by adding a solvent to the reaction mixture, crystallizing it, and filtering to obtain the target product in powder or granular form. The benzoxazine compound obtained by the above method can be purified to a high purity product by conventional purification methods such as washing with a solvent or water or recrystallization.

[0019] In the present invention, two or more benzoxazine compounds represented by general formula (1) may be used in combination as component (A). Alternatively, two or more benzoxazine compounds represented by general formula (1) may be used in combination by using a mixture of benzoxazine compounds represented by general formula (1) obtained by using two or more bisphenol compounds represented by general formula (2) in combination in the reaction for producing the benzoxazine compound represented by general formula (1). There are no particular restrictions on the ratio of the two or more bisphenol compounds represented by general formula (2) when used in combination. To give a specific example, when using bisphenol F as the bisphenol compound represented by general formula (2), a mixture of its positional isomers, namely bis(2-hydroxyphenyl)methane, 2-hydroxyphenyl-4-hydroxyphenylmethane, and bis(4-hydroxyphenyl)methane, can be used, and there are no particular restrictions on their ratio. Bisphenol F with a high proportion of bis(2-hydroxyphenyl)methane can be obtained, for example, by the method described in Japanese Patent Publication No. 08-245464, and bisphenol F with a high proportion of bis(4-hydroxyphenyl)methane can be obtained, for example, by the method described in Japanese Patent Publication No. 06-340565. When a mixture of positional isomers of bisphenol F and 2-aminoethanethiol as the aminothiol compound represented by general formula (3) are synthesized by the above production method, a mixture of compounds (p-1), (p-4), and (p-7) can be obtained. The bisphenol compound represented by general formula (2) used may contain a polynuclear compound, which is a by-product in the production of bisphenol (dinuclear compound). There are no particular restrictions on the content ratio, but it is preferably 50% by weight or less, more preferably 30% by weight or less, and even more preferably 15% by weight or less. Furthermore, in the reaction for producing the benzoxazine compound represented by general formula (1), two or more benzoxazine compounds represented by general formula (1) may be used in combination by using a mixture of benzoxazine compounds represented by general formula (1) obtained by using two or more aminothiol compounds represented by general formula (3). There are no particular restrictions on the ratio of the two or more aminothiol compounds represented by general formula (3) when used in combination.

[0020] The benzoxazine compound represented by general formula (1) according to the present invention may be a crude product containing compounds produced as by-products in the reaction for its manufacture. Examples of such by-product compounds include compounds with a higher molecular weight than the benzoxazine compound represented by general formula (1). The content of the benzoxazine compound represented by general formula (1) in the crude product of the benzoxazine compound represented by general formula (1) is not particularly limited. Its content can be analyzed by gel permeation chromatography using a differential refractometer as a detector. Typically, the peak area of ​​the benzoxazine compound represented by general formula (1) relative to the area of ​​all peaks detected by such analysis is preferably 10 area% or more, more preferably 20 area% or more, more preferably 30 area% or more, and particularly preferably 40 area% or more. The upper limit is 99.9 area%.

[0021] <Component (B): Compound having a cyclic ether group with 3 or 4 members> Component (B) in the curable resin composition of the present invention is a compound having a 3- or 4-membered cyclic ether group, and it is preferable to use a compound having a 3-membered cyclic ether group. Examples of compounds having a three-membered cyclic ether group include glycidyl ether compounds, alicyclic epoxy compounds, and epoxy resins, which are preferred. Examples of glycidyl ether compounds include, for example, glycidyl ether compounds obtained by the reaction of polyhydric phenols such as bisphenol A diglycidyl ether (DGEBA), bisphenol F diglycidyl ether, bisphenol S diglycidyl ether, hexahydrobisphenol A diglycidyl ether, tetramethylbisphenol A diglycidyl ether, resorcinol diglycidyl ether, biphenol diglycidyl ether, tetramethylbiphenol diglycidyl ether, hexamethylbiphenol diglycidyl ether, tetrabromobisphenol A diglycidyl ether, and dihydroxynaphthalene diglycidyl ether with epichlorohydrin. Examples of alicyclic epoxy compounds include 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate, bi(3,4-epoxycyclohexyl), bis(3,4-epoxycyclohexyl) ether, bis(3,4-epoxycyclohexyl)methane, and 2,2-bis(3,4-epoxycyclohexyl)propane. Examples of epoxy resins include phenol novolac type epoxy resins, orthocresol type epoxy resins, biphenyl type epoxy resins, biphenyl aralkyl type epoxy resins, naphthalene type epoxy resins, anthracene dihydride type epoxy resins, and brominated novolac type epoxy resins. Examples of compounds having a four-membered cyclic ether group include oxetane compounds. Specifically, examples include 3-ethyl-3-hydroxymethyloxetane, 1,4-bis[(3-ethyl-3-oxetanyl)methoxymethyl]benzene, 3-ethyl-3-(phenoxymethyl)oxetane, di[(3-ethyl-3-oxetanyl)methyl]ether, 3-ethyl-3-[(2-ethylhexyloxymethyl)]oxetane, bis[(3-ethyl-3-oxetanyl)methyl]terephthalate, bis[(3-ethyl-3-oxetanyl)methyl]isophthalate, 4,4'-bis[(3-ethyl-3-oxetanyl)methoxymethyl]biphenyl, and phenol novolac oxetane.

[0022] <Component (C): Compound having a reactive group containing a carbon-carbon double bond or carbon-carbon triple bond> Component (C) in the curable resin composition of the present invention is a compound having a reactive group containing a carbon-carbon double bond or a carbon-carbon triple bond. Reactive groups containing carbon-carbon double or carbon-carbon triple bonds include vinyl groups, vinyl ether groups, allyl groups, allyl ether groups, acryloyl groups, methacryloyl groups, styrene groups, maleimide groups, and alkynyl groups. Among these, compounds having a maleimide group are preferred. Examples of compounds having a maleimide group include, in addition to bismaleimide compounds having the following structure, p-phenylenebismaleimide, m-phenylenebismaleimide, 4,4'-diphenylmethanebismaleimide, 4,4-diphenyletherbismaleimide, 4,4-diphenylsulfonebismaleimide, 2,2-bis[4-(4-maleimidophenoxy)phenyl]propane, and 1,3-bis(4-maleimidophenoxy)benzene. [ka]

[0023] In the curable resin composition of the present invention, the amount of component (B) used, the amount of component (C) used, or the total amount of component (B) and component (C) used is in the range of 5 to 2000 parts by weight per 100 parts by weight of component (A). Preferably, it is in the range of 10 to 1000 parts by weight per 100 parts by weight of component (A), more preferably in the range of 20 to 500 parts by weight per 100 parts by weight of component (A), and particularly preferably in the range of 50 to 200 parts by weight per 100 parts by weight of component (A).

[0024] <Component (D): Curing reaction catalyst> The curable resin composition of the present invention may contain a curing reaction catalyst as component (D). Suitable curing catalysts include acid catalysts, alkali catalysts, and phosphorus-based compounds. Among these, acid catalysts are preferred. The acid catalyst is preferably an organic acid catalyst, and examples of organic acid catalysts include p-toluenesulfonic acid and methanesulfonic acid. The alkali catalyst is preferably an organic alkali catalyst. Examples of organic alkali catalysts include tertiary amines such as 1,8-diaza-bicyclo[5.4.0]undeca-7-ene, triethylenediamine, and tris(2,4,6-dimethylaminomethyl)phenol, and imidazoles such as 2-ethyl-4-methylimidazole and 2-methylimidazole. Examples of phosphorus-based compounds include triphenylphosphine, tetraphenylphosphonium bromide, tetraphenylphosphonium tetraphenylborate, and tetra-n-butylphosphonium-O,O-diethylphosphorodithioate. Among these, p-toluenesulfonic acid, 2-methylimidazole, and triphenylphosphine are particularly preferred. These may be used individually or in combination. The amount of component (D) used is in the range of 0.1% to 20% by weight relative to the total amount of components (A), (B), and (C). Preferably, it is in the range of 0.1% to 15% by weight, more preferably in the range of 0.1% to 10% by weight, and particularly preferably in the range of 0.1% to 8% by weight.

[0025] <Component (E): Filler> The curable resin composition of the present invention may contain a filler as component (E). Examples of fillers for component (E) include silicon dioxide, aluminum oxide, magnesium oxide, boron nitride, aluminum nitride, silicon nitride, and silicon carbide. These can be used in combination with inorganic fillers such as hexagonal boron nitride, or with reinforcing fibers such as carbon fiber, glass fiber, organic fiber, boron fiber, steel fiber, and aramid fiber.

[0026] The curable resin composition of the present invention may contain other curable resin materials besides the above components (A) to (E). Examples of such materials include phenolic resins and benzoxazine compounds other than those represented by general formula (1).

[0027] 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.

[0028] Examples of benzoxazine compounds other than those represented by general formula (1) include benzoxazine compounds having structures represented by the following general formulas (A) to (C). [ka] (In the formula, Ra represents a divalent group having 1 to 30 carbon atoms, Rb independently represents a monovalent group having 1 to 10 carbon atoms which may have substituents, and n represents 0 or 1.) [ka] (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 Rd independently represents a monovalent group having 1 to 10 carbon atoms.) [ka] (In the formula, Re independently represents a monovalent group with 1 to 10 carbon atoms, and m represents 0 or 1.)

[0029] In benzoxazine compounds having the structure represented by general formula (A), Ra represents a divalent group having 1 to 30 carbon atoms. Specific examples include alkylene groups such as 1,2-ethylene, 1,4-butylene, and 1,6-hexylene; alkylene groups containing cyclic structures such as 1,4-cyclohexylene, dicyclopentadienylene, and adamantylene; and arylene groups such as 1,4-phenylene, 4,4'-biphenylene, diphenyl ether-4,4'-diyl, diphenyl ether-3,4'-diyl, diphenyl ketone-4,4'-diyl, and diphenyl sulfone-4,4'-diyl. In benzoxazine compounds having the structure represented by general formula (A), Rb independently represents a monovalent group having 1 to 10 carbon atoms. Specific examples 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 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, hydroxyl groups, and thiol groups. Examples of benzoxazine compounds having the structure represented by general formula (A) include Pd-type benzoxazine manufactured by Shikoku Chemicals, and JBZ-OP100N and JBZ-BP100N manufactured by JFE Chemical Corporation.

[0030] In benzoxazine compounds having the 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 divalent groups 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 cyclic structures such as 1,4-cyclohexylene, dicyclopentadienylene, and adamantylene; and alkylidene groups such as ethylidene, propyridene, isopropylidene, butylidene, phenylethylidene, cyclopentylidene, cyclohexylidene, cycloheptylidene, cyclododecylidene, 3,3,5-trimethylcyclohexylidene, and fluorenylidene. In benzoxazine compounds having the structure represented by general formula (B), Rd independently represents a monovalent group having 1 to 10 carbon atoms. Specific examples 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 include alkoxy groups having 1 to 4 carbon atoms, acyl groups having 1 to 4 carbon atoms, halogen atoms, carboxyl groups, sulfo groups, allyloxy groups, and hydroxyl groups. Examples of benzoxazine compounds having the structure represented by general formula (B) include Fa-type benzoxazine manufactured by Shikoku Chemicals Co., Ltd. and BS-BXZ manufactured by Konishi Chemical Industry Co., Ltd.

[0031] In benzoxazine compounds having the structure represented by general formula (C), Re independently represents a monovalent group having 1 to 10 carbon atoms. Specific examples 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 include alkoxy groups having 1 to 4 carbon atoms, acyl groups having 1 to 4 carbon atoms, halogen atoms, carboxyl groups, sulfo groups, allyloxy groups, hydroxyl groups, and thiol groups.

[0032] The curable resin composition of the present invention may contain a solvent as component (F), and is particularly preferred to be in the form of a varnish dissolved or dispersed in component (F). Component (F) is not particularly limited as long as it dissolves or disperses the curable resin composition of the present invention. For example, aromatic hydrocarbon solvents, aliphatic ketone solvents having 3 to 7 carbon atoms, and ether-based solvents can be used. There are no restrictions on the amount of solvent that can be used, as long as it is sufficient to dissolve or disperse each component, but it is 10 times or less by weight, more preferably 5 times or less by weight, more preferably 1 time or less by weight, and particularly preferably 0.5 times or less by weight, relative to the total amount of component (A), component (B), and / or component (C) used. Varnish can be used, for example, to form a film-like resin composition by applying it to a support using a coater and then drying it, or to produce a composition after impregnation of reinforcing fibers and removal of the solvent.

[0033] The curable resin composition of the present invention is obtained by mixing a benzoxazine compound represented by general formula (1), which is component (A), with at least one of components (B) and (C), and optionally with components (D) to (F) and other curable resin materials. The mixing method is not particularly limited, and conventionally known methods can be used depending on the components used. For example, mixing can be done using a mixer or by melt-mixing using a kneader. The mixing of each component can be carried out in air or in an inert gas atmosphere such as nitrogen, but it is preferable to carry it out in an inert gas atmosphere to prevent degradation by oxygen. The curable resin composition of the present invention may generate bubbles during curing if it contains water or residual solvent. Therefore, 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 the temperature at which the curable resin composition of the present invention becomes molten, but it is preferable to perform it at a maximum of 150°C because curing does not proceed and degassing is easy. The pressure of the vacuum degassing treatment is not particularly limited, but a low pressure (high degree of reduced pressure) is preferable, and it may be performed in air or under an inert gas atmosphere such as nitrogen. It is preferable to continue this vacuum degassing treatment until bubbles can no longer be visually confirmed.

[0034] <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. One method for producing the cured product of the present invention is a method having a curing step in which the curable resin composition is cured under high temperature conditions. A pre-curing step may be included before the curing step, in which a curing reaction is carried out at a lower temperature than the curing step, and it is preferable to include such a step. The temperature conditions in the pre-curing process are in the range of 60°C to less than 150°C, preferably in the range of 70°C to 140°C, more preferably in the range of 80°C to 130°C, and particularly preferably in the range of 90°C to 130°C. The temperature conditions in the curing process are in the range of 150°C to 240°C, preferably in the range of 150°C to 220°C, more preferably in the range of 150°C to 210°C, and particularly preferably in the range of 150°C to 200°C. When curing within this temperature range, a reaction time of 1 to 10 hours is sufficient. The curing process and the pre-curing process may be carried out in air or under an inert gas atmosphere such as nitrogen, but carrying them out under an inert gas atmosphere is preferable in order to prevent deterioration of the resulting cured product due to oxygen.

[0035] The curable resin composition of the present invention can suppress the generation of volatile components with odor during the production of the cured product. Furthermore, the curable resin composition of the present invention can produce a cured product with significantly improved heat resistance compared to the case in which only a benzoxazine compound having a thiol group is used. Furthermore, it has been revealed that the benzoxazine compound having a thiol group invented by the present inventors for the curable resin composition of the present invention has a lower curing temperature compared to conventionally known benzoxazine compounds, thereby improving workability by shortening the curing time and saving energy, and can be used on heat-sensitive materials (substrates), and that its cured product can be melted at a lower temperature compared to benzoxazine compounds having a hydroxyl group, thus enabling the manufacture and handling of the curable resin composition using this benzoxazine compound at a lower temperature. In view of these points, the curable resin composition of the present invention and the cured products obtained therefrom can be used as useful materials in fields such as prepregs, printed circuit boards, encapsulants for electronic components, electrical and electronic molded components, insulating substrates, liquid crystal alignment agents, semiconductor encapsulants, automotive parts, laminations, paints, and resist inks. [Examples]

[0036] The present invention will be described in more detail below with reference to examples. <Analysis method> 1. Analysis of the reaction solution composition and purity of benzoxazine compounds (gel permeation chromatography: GPC) The purity of the synthesized benzoxazine compound was expressed as the area percentage of the benzoxazine compound obtained through this analysis. Device: HLC-8320 / Manufactured by Tosoh Corporation Detector: Differential refractometer (RI) [Measurement conditions] Flow rate: 1mL / min Elutate: Tetrahydrofuran Temperature: 40℃ Wavelength: 254nm Measurement sample: 1 g of a benzoxazine compound-containing composition was diluted 200-fold with tetrahydrofuran and used as the measurement sample.

[0037] 2. Measurement of the weight loss rate during curing of curable resin compositions A curable resin composition was prepared by grinding and mixing 5g of component (A) (benzoxazine compound), 5g of component (B) (a compound having a cyclic ether group of 3 or 4 members), and / or 5g of component (C) (a compound having a reactive group containing a carbon-carbon double bond or carbon-carbon triple bond) in a mortar and pestle with 5% by weight of component (D) (curing reaction catalyst) relative to the total amount of component (A) and component (B) and / or component (C). The composition was placed in a 50 mL test tube and then heated under a nitrogen atmosphere at the specified temperature and time described in the Examples and Comparative Examples. The weight of the mixture before and after heating was measured. The weight loss rate was calculated by dividing the weight difference by the weight of the mixture before heating.

[0038] 3. Measurement of the amount of sulfur-containing volatile components generated during the curing of curable resin compositions. The amount of sulfur-containing volatile components generated was calculated by analyzing the sulfur-containing volatile components using the following equipment and conditions, and then using the calibration curve method. Analyzer: GC-2010Plus / manufactured by Shimadzu Corporation Vaporizer: TurboMatrix40 / PerkinElmer, Inc. [Measurement conditions] Evaporation chamber temperature: 300℃ Carrier gas: Nitrogen Total flow rate: 50.0mL / min Column flow rate: 0.74 mL / min Column: TC-1 Vaporization pressure: 240 kPa Insulation temperature / insulation time: As described in the Examples and Comparative Examples. Pressurization time: 3.0 min Injection time: 0.10min Sample for measurement: A curable resin composition was prepared by grinding and mixing 2g of component (A), 2g of component (B) and / or component (C), and 5% by weight of component (D) relative to the total amount of component (A) and component (B) or component (C) in a mortar. The mixture was then placed in an HS-GC vial, placed under a nitrogen atmosphere, and sealed with an aluminum cap. After heating the sealed HS-GC vials at the above-mentioned incubation temperature and incubation time, the gas phase portion within the HS-GC vials was analyzed.

[0039] 4. Preparation of the cured product The cured material was prepared using a constant-temperature drying oven. Equipment: Vacuum constant temperature drying oven DP-32 / Manufactured by Yamato Scientific Co., Ltd. Manufacturing container: Silicone casting plate for DMA measurement

[0040] 5. Measurement of the glass transition temperature (Tg) of the cured product Equipment: Discovery DMA 850 / TA Instruments [Measurement conditions] Measurement mode: 3-point bending Heating rate: 2°C / min. Basic frequency: 1Hz Atmosphere: Air current Sample size: 50 x 8 x 3 mm

[0041] <Synthesis Example 1> (Synthesis of benzoxazine compound A represented by the following chemical formula) [ka] A 500 mL four-necked flask equipped with a thermometer, stirrer, condenser, and dropping funnel was charged with 31 g (0.15 mol) of bisphenol F (90.1 wt% dinuclear content, isomer ratio: bis(2-hydroxyphenyl)methane 18.8 wt%, 2-hydroxyphenyl-4-hydroxyphenylmethane 49.3 wt%, bis(4-hydroxyphenyl)methane 31.9 wt%, polynuclear content 9.9 wt%), 74 g of 94% paraformaldehyde, and 57 g of toluene. After purging the reaction vessel with nitrogen, the temperature of the mixed solution was raised to 30°C. Then, 24 g of 2-aminoethanethiol was added dropwise to the four-necked flask using a dropping funnel over 1 hour while maintaining the temperature at 30°C. After the addition was complete, the mixture was stirred for another 3 hours at 30°C. Analysis of the reaction solution composition by GPC using the above analytical method showed that the proportion of the target compound present in the reaction solution was 88 area %. After the reaction was complete, the reaction solution was washed with alkaline water using a 3% sodium hydroxide aqueous solution, followed by washing with water until the pH of the reaction solution was 7 or less. Then, toluene and water were removed by vacuum distillation at 30°C. The distillation pressure was gradually reduced until it reached 2.3 kPa. After removing a certain amount of solvent, the remaining solvent was further removed under conditions of 90°C and 2.8 kPa. The composition containing the target compound was extracted, cooled and solidified, and then pulverized to obtain 156 g of the target compound (purity: 75%, 25% area of ​​a compound with a higher molecular weight than the target compound). 1 ¹H-NMR analysis confirmed that the target compound with the above chemical formula was obtained. 1¹H-NMR analysis (400 MHz, solvent: CDCl3, reference substance: tetramethylsilane): 1.32-1.95 (2H, brm), 2.91-3.05 (4H, m), 3.07-3.22 (4H, m), 3.64-4.13 (10H, m), 6.66-7.12 (6H, m).

[0042] <Comparative Example 1> Under the above conditions for measuring the weight loss rate during curing and the amount of sulfur-containing volatile components generated, the weight loss rate during curing and the amount of sulfur-containing volatile components generated were measured under the same conditions as above, but with only benzoxazine compound A obtained in Synthesis Example 1 used as component (A), and without using components (B) and / or (C) and (D). Heating was performed at a temperature of 175°C for 1 hour. It was confirmed that the sulfur-containing volatile component when benzoxazine compound A is used is thiazolidine. It is hypothesized that the generation of thiazolidine occurs through the process shown in the following formula. [ka] As a result, the weight loss rate was 2.3% by weight, and the amount of thiazolidine generated was 36.2 mol%.

[0043] The results from Comparative Example 1 revealed that in a curable resin composition using only benzoxazine compound A, which has a thiol group in component (A), weight loss and the generation of large amounts of sulfur-containing volatile components (thiazolidine) occurred during the production of the cured product.

[0044] <Example 1> Under the above conditions for measuring the amount of sulfur-containing volatile components generated, the amount of sulfur-containing volatile components (thiazolidinediones) generated was measured when benzoxazine compound A obtained in Synthesis Example 1 was used as component (A), 4,4'-diphenylmethanebismaleimide (BMI) was used as component (C), and component (D) was not used. Heating was performed at a temperature of 175°C for 1 hour. As a result, the amount of thiazolidinedione generated was 17.1 mol%.

[0045] <Example 2> Under the above conditions for measuring the amount of sulfur-containing volatile components generated, the amount of sulfur-containing volatile components (thiazolidine) generated was measured when benzoxazine compound A obtained in Synthesis Example 1 was used as component (A), bisphenol A diglycidyl ether (DGEBA) was used as component (B), and component (D) was not used. Heating was performed at a temperature of 175°C for 1 hour. As a result, it was confirmed that thiazolidinediones were not present.

[0046] The results from Examples 1 and 2 revealed that the curing agent for the curable resin composition of the present invention, which contains component (B) and / or component (C) in addition to a benzoxazine compound having a thiol group, can suppress the generation of sulfur-containing volatile components (thiazolidine).

[0047] <Comparative Example 2> Under the above conditions for measuring the weight loss rate during curing and the amount of sulfur-containing volatile components generated, only benzoxazine compound A obtained in Synthesis Example 1 was used as component (A), and the conditions were changed to omit components (B) and / or (C), and the catalyst, while other conditions remained the same. The weight loss rate during curing and the amount of sulfur-containing volatile components (thiazolidine) generated were measured. The mixture was heated at 120°C for 1 hour, followed by heating at 175°C for 4 hours. As a result, the weight loss rate was 3.6% by weight, and the amount of thiazolidine generated was 56.0 mol%.

[0048] <Example 3> Under the above conditions for measuring the amount of sulfur-containing volatile components generated, the amount of sulfur-containing volatile components (thiazolidinediones) generated was measured when benzoxazine compound A obtained in Synthesis Example 1 was used as component (A), 4,4'-diphenylmethanebismaleimide (BMI) was used as component (C), and component (D) was not used. The mixture was heated at 120°C for 1 hour, followed by heating at 175°C for 4 hours. As a result, the amount of thiazolidinedion generated was 3.0 mol%.

[0049] <Example 4> Under the above conditions for measuring the weight loss rate during curing and the amount of sulfur-containing volatile components generated, the weight loss rate and the amount of sulfur-containing volatile components (thiazolidinediones) generated were measured when benzoxazine compound A obtained in Synthesis Example 1 was used as component (A), bisphenol A diglycidyl ether (DGEBA) was used as component (B), and component (D) was not used. The mixture was heated at 120°C for 1 hour, and then heated at 175°C for 4 hours. As a result, the weight loss rate was 0.9% by weight. Furthermore, it was confirmed that no thiazolidine was present.

[0050] The results from Examples 3 and 4 revealed that the curable resin composition of the present invention, comprising a benzoxazine compound having a thiol group as component (A) and components (B) and / or (C), can further suppress the generation of thiazolidinedions by having a pre-curing step at 120°C in the curing reaction. On the other hand, the results from Comparative Example 2 revealed that the curable resin composition using only a benzoxazine compound having a thiol group could not suppress the generation of thiazolidine, even under curing reaction conditions that could suppress the generation of thiazolidine in Examples 3 and 4, because it did not contain component (B) or component (C).

[0051] <Example 5> The amount of sulfur-containing volatile components (thiazolidine) generated was measured when benzoxazine compound A obtained in Synthesis Example 1 was used as component (A), BMI as component (C), and 2-methylimidazole (2MI) as component (D). The mixture was heated at 175°C for 1 hour. As a result, the amount of thiazolidinedione generated was 23.8 mol%.

[0052] <Example 6> The amount of sulfur-containing volatile components (thiazolidine) generated was measured when benzoxazine compound A obtained in Synthesis Example 1 was used as component (A), BMI as component (C), and 2-methylimidazole (2MI) as component (D). The mixture was heated at 120°C for 1 hour, followed by heating at 175°C for 4 hours. As a result, the amount of thiazolidinedione generated was 14.2 mol%.

[0053] <Example 7> The amount of sulfur-containing volatile components (thiazolidine) generated was measured when benzoxazine compound A obtained in Synthesis Example 1 was used as component (A), DGEBA as component (B), and 2-methylimidazole (2MI) as component (D). The mixture was heated at 120°C for 1 hour, followed by heating at 175°C for 4 hours. As a result, the amount of thiazolidinedione generated was 34.6 mol%.

[0054] <Example 8> The amount of sulfur-containing volatile components (thiazolidines) generated was measured when benzoxazine compound A obtained in Synthesis Example 1 was used as component (A), DGEBA as component (B), and triphenylphosphine (TPP) as component (D). Heating was performed at a temperature of 175°C for 1 hour. As a result, the amount of thiazolidinedione generated was 11.2 mol%.

[0055] <Example 9> The weight loss rate and the amount of sulfur-containing volatile components (thiazolidine) generated were measured when benzoxazine compound A obtained in Synthesis Example 1 was used as component (A), DGEBA as component (B), and triphenylphosphine (TPP) as component (D). After heating at 120°C for 1 hour, the mixture was heated at 175°C for 4 hours. As a result, the weight loss rate was 1.0% by weight, and the amount of thiazolidine generated was 0.6 mol%.

[0056] <Example 10> The amount of sulfur-containing volatile components (thiazolidine) generated was measured when benzoxazine compound A obtained in Synthesis Example 1 was used as component (A), BMI as component (C), and triphenylphosphine (TPP) as component (D). The mixture was heated at 120°C for 1 hour, followed by heating at 175°C for 4 hours. As a result, the amount of thiazolidinedione generated was 11.0 mol%.

[0057] <Example 11> The amount of sulfur-containing volatile components (thiazolidine) generated was measured when benzoxazine compound A obtained in Synthesis Example 1 was used as component (A), BMI as component (C), and p-toluenesulfonic acid monohydrate (PTSA) as component (D). Heating was performed at a temperature of 175°C for 1 hour. As a result, the amount of thiazolidinedion generated was 4.6 mol%.

[0058] <Example 12> The weight loss rate and the amount of sulfur-containing volatile components (thiazolidine) generated were measured when benzoxazine compound A obtained in Synthesis Example 1 was used as component (A), BMI as component (C), and p-toluenesulfonic acid monohydrate (PTSA) as component (D). The mixture was heated at 120°C for 1 hour, followed by heating at 175°C for 4 hours. As a result, the weight loss rate was 2.1% by weight, and the amount of thiazolidine generated was 1.0 mol%.

[0059] <Example 13> The weight loss rate and the amount of sulfur-containing volatile components (thiazolidine) generated were measured when benzoxazine compound A obtained in Synthesis Example 1 was used as component (A), DGEBA as component (B), and p-toluenesulfonic acid monohydrate (PTSA) as component (D). The mixture was heated at 120°C for 1 hour, followed by heating at 175°C for 4 hours. As a result, the weight loss rate was 1.5% by weight. Furthermore, it was confirmed that no thiazolidine was present.

[0060] In the curable resin composition of the present invention, which comprises a benzoxazine compound having a thiol group as component (A) and components (B) and / or (C), it has been found that even when a curing reaction catalyst is further included as component (D), the generation of sulfur-containing volatile components (thiazolidines) can be suppressed compared to when a cured product is produced using only a benzoxazine compound having a thiol group. It was revealed that using PTSA, an acid catalyst, among the components (D), can further suppress the generation of thiazolidinedions.

[0061] The weight loss rate and the amount of sulfur-containing volatile components (thiazolidine) generated (mol%) for curable resin compositions in Examples 1-13 and Comparative Examples 1 and 2 were measured. Furthermore, for Examples 1-13, the suppression rate (%) was calculated in comparison with comparative examples cured under the same curing conditions using only component A. The suppression rate (%) of sulfur-containing volatile components is summarized in Table 1 below. In the table, the "Temperature and Time during Curing" column indicates the temperature and time conditions during curing: (i) means heating at 175°C for 1 hour, and (ii) means heating at 120°C for 1 hour followed by heating at 175°C for 4 hours. "-" in the weight loss rate column indicates that it was not measured. [Table 1]

[0062] (Evaluation of the heat resistance of the cured product) <Example 14> Component (A), 8g of benzoxazine compound A obtained in Synthesis Example 1, and component (C), 8g of BMI, were ground and mixed in a mortar. After melting and degassing at 120°C for 3 hours, the mixture was poured into a preheated silicone casting plate for DMA measurement. Subsequently, it was heated and cured in a dryer at 140°C → 150°C → 160°C → 180°C → 200°C → 220°C → 240°C for 2 hours each, and cooled overnight to obtain a cured product. The obtained cured product was subjected to dynamic viscoelasticity measurement, and the Tg was calculated from the Tanδ value, which was found to be 272°C. The chart of the dynamic viscoelasticity analysis (DMA) of the obtained cured product is shown in Figure 1.

[0063] <Comparative Example 3> Component (A), 9 g of benzoxazine compound A obtained in Synthesis Example 1, was ground in a mortar and pestle, melted and degassed at 100°C for 1.5 hours, and then poured into a preheated silicone casting plate for DMA measurement. Subsequently, it was heated and cured in a dryer at 140°C → 150°C → 160°C → 180°C → 200°C for 2 hours each, and cooled overnight to obtain a cured product. The Tg of the obtained cured product was calculated from the Tanδ value by dynamic viscoelasticity measurement and was found to be 152°C. The chart of the dynamic viscoelasticity analysis (DMA) of the obtained cured product is shown in Figure 2.

[0064] The results from Example 14 and Comparative Example 3 clearly show that the cured product obtained from the curable resin composition of the present invention, which contains a benzoxazine compound having a thiol group and a curing agent consisting of component (B) and / or component (C), exhibits significantly improved heat resistance compared to the cured product of a benzoxazine compound having a thiol group alone.

Claims

1. A curable resin composition containing 100 parts by weight of component (A) and 5 to 2000 parts by weight of at least one of the components (B) and (C) listed below. (A): A benzoxazine compound represented by the following general formula (1). 【Chemistry 1】 (In the formula, R 1 R represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms. 2 (wherein X represents an alkylene group having 1 to 10 carbon atoms, including a linear, branched, or aliphatic ring, and X represents a single bond, an oxygen atom, a sulfur atom, a sulfonyl group, a carbonyl group, or a divalent group represented by formula 1a or formula 1b below.) 【Chemistry 2】 (In formula 1a and formula 1b, R 3 and R 4 Each independently represents hydrogen, an alkyl group having 1 to 10 carbon atoms, an alkyl halogenated group having 1 to 10 carbon atoms, or an aryl group having 6 to 12 carbon atoms, R 3 and R 4 These may bond to each other to form a cycloalkylidene group with 5 to 20 carbon atoms in total, and Ar 1 and Ar 2 Each of these independently represents an aryl group having 6 to 12 carbon atoms, and * indicates the bond position. (B): A compound having a cyclic ether group of three or four members. (C): A compound having a reactive group containing a carbon-carbon double bond or a carbon-carbon triple bond.

2. The curable resin composition according to claim 1, comprising the following component (D). (D): Curing reaction catalyst

3. The curable resin composition according to claim 2, wherein the curing reaction catalyst is an acid catalyst.

4. Furthermore, the curable resin composition according to any one of claims 1 to 3, further containing the following component (E). (E): Filler

5. A varnish comprising the curable resin composition described in claim 1 and the following component (F). (F): Organic solvent

6. A cured product obtained by curing the curable resin composition according to claim 1.

7. A method for producing a cured product containing component (A), characterized by curing a curable resin composition containing component (A) and at least one of the components (B) and (C) listed below. (A): A benzoxazine compound represented by the following general formula (1). 【Transformation 3】 (wherein, R 1 represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, and R 2 represents a linear, branched or aliphatic ring-containing alkylene group having 1 to 10 carbon atoms, and X represents a single bond, an oxygen atom, a sulfur atom, a sulfonyl group, a carbonyl group, or a divalent group represented by the following formula (1a) or formula (1b).) 【Chemistry 4】 (In formula 1a and formula 1b, R 3 and R 4 Each independently represents hydrogen, an alkyl group having 1 to 10 carbon atoms, an alkyl halogenated group having 1 to 10 carbon atoms, or an aryl group having 6 to 12 carbon atoms, R 3 and R 4 These may bond to each other to form a cycloalkylidene group with 5 to 20 carbon atoms in total, and Ar 1 and Ar 2 Each of these independently represents an aryl group having 6 to 12 carbon atoms, and * indicates the bond position. (B): A compound having a cyclic ether group of three or four members. (C): A compound having a reactive group containing a carbon-carbon double bond or a carbon-carbon triple bond.

8. The method for producing a cured product according to claim 7, wherein the method for producing the cured product includes a pre-curing step with a temperature range of 60°C to 150°C and a curing step with a temperature range of 150°C to 240°C.

9. The method for producing a cured product according to claim 7 or 8, wherein the curable resin composition further contains the following component (D). (D): Curing reaction catalyst

10. The method for producing a cured product according to claim 9, wherein the curing reaction catalyst is an acid catalyst.

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