A method for producing a curable resin composition, a step-growth polymer, and a cured product.

Abstract

The present invention provides a curable resin composition and a step-growth polymer thereof for forming a cured product having excellent toughness by solving the problem of brittleness of heat-resistant crosslinked materials. [Solution] A curable resin composition containing the following components (A), (B), and (C): Component (A): A polyphenylene ether prepolymer, which is a compound defined by formula (1) (in formula (1), -(OXO)- is defined by formula (2)), has a polydispersity index of 2.8 or less, and a number average molecular weight of 1,000 or more and 5,000 or less; Component (B): A bifunctional phenol, which has a content of trifunctional or higher molecular species of less than 20%; and Component (C): A curing accelerator. JPEG2026044153000034.jpg19170 JPEG2026044153000035.jpg28170

Description

[Technical Field]

[0001] The present invention relates to a curable resin composition, a step-growth polymer, and a method for producing a cured product. [Background technology]

[0002] BACKGROUND ART Crosslinked heat-resistant polymers such as epoxy resins, or curable oligomers such as epoxy-type oligomers, are excellent in heat resistance, insulating properties, adhesive properties, etc., and are widely used industrially in composite structural materials, electrical and electronic applications, etc.

[0003] Furthermore, polyphenylene ether (hereinafter, PPE) resins have been reported in the fields of resin curing products, prepregs, copper-clad laminates, laminates, printed circuit boards, etc. (Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 9-291148 [Patent Document 2] Japanese Patent Application Publication No. 2023-143431 [Patent Document 3] Japanese Patent Application Laid-Open No. 2003-238654 [Non-patent literature]

[0005] [Non-Patent Document 1] ACS Appl. Mater. Interfaces 2012, 4, 564-572 [Non-patent document 2] Mol.Cryst.Liq.Cryst.,Vol.588,41-50,2014 Summary of the Invention [Problem to be solved by the invention]

[0006] As shown in many documents, crosslinked heat-resistant polymers are known to have the problem of being brittle (hereinafter referred to as "brittleness").

[0007] It has been reported that the cause of brittleness is the formation of gel balls (also called local cross-linked structures, nodules, or domains) during the curing stage of cross-linked polymers (Non-Patent Document 1). This is thought to be because multiple gel balls form a non-uniform structure in the polymer network of the cured product, and cracks propagate through structural defects between the multiple gel balls.

[0008] In the field of liquid crystal epoxy resins, as shown in many documents, attempts have been made to improve toughness by forming a highly uniform network structure in the cured resin (Non-Patent Document 2). However, such liquid crystal epoxy resins require specific curing conditions, and therefore, there remains a problem in their versatility.

[0009] Regarding these issues and the current situation, JP 2023-143431 (Patent Document 2) reports an invention in which (1) a bifunctional prepolymer in which a functional group is bonded to the end of a molecular chain with low mobility in the main chain and (2) a bifunctional compound in which functional groups capable of addition reaction with the end groups of the prepolymer are bonded to both ends are polymerized, and then the end sites are crosslinked to form a highly tough crosslinked structure or cured product.

[0010] In the examples of Patent Document 3, a specific example is disclosed in which a polymer is synthesized by using a solution reaction when polymerizing (1) a bifunctional prepolymer having a functional group bonded to the end of a molecular chain with low main chain mobility, and (2) a bifunctional compound having functional groups bonded to both ends capable of addition reaction with the end groups of the prepolymer, and the polymer is isolated and then the end portions of the polymer are crosslinked. However, from an industrial perspective, it is extremely useful in terms of the simplicity and productivity of the molding process to polymerize (1) a bifunctional prepolymer having a functional group bonded to the end of a molecular chain with low main chain mobility, and (2) a bifunctional compound having functional groups bonded to both ends capable of addition reaction with the end groups of the prepolymer, and then crosslink the end portions of the polymer "without isolating the polymer."

[0011] As a structure corresponding to a bifunctional prepolymer in which a functional group is bonded to the end of a molecular chain with low main chain mobility, PPE in which the molecular chain end is epoxidized (hereinafter also referred to as Ep-PPE) is disclosed in Patent Documents 1 and 3. However, Patent Document 3 only discloses an example in which such a PPE with epoxy ends is cured with a multifunctional phenolic curing agent in which the number of hydroxyl groups contained in one molecule is greater than two.

[0012] Furthermore, Patent Document 1 discloses epoxy-terminated PPE, but the method for producing epoxy-terminated PPE involves blending a bisphenol with one-terminated PPE and carrying out a redistribution reaction. However, this increases the polydispersity (molecular weight distribution), resulting in an increase in melt viscosity and poor moldability.

[0013] Furthermore, in order to achieve high molecular weight using (1) a bifunctional prepolymer in which a functional group is bonded to the end of a molecular chain having low mobility in the main chain, and (2) a bifunctional compound in which functional groups capable of addition reaction with the end groups of the prepolymer are bonded to both ends, as described in Patent Document 2, it is necessary for the viscosity of the resin composition to be low and fluidity to be guaranteed during the reaction process.

[0014] Regarding curing agents, paragraph 0023 of Patent Document 1 states, "Curing agents for these epoxy resins include commonly used amine-based agents such as primary and secondary amines, phenol-based agents including polyphenols such as bisphenol A and bisphenol F, and acid anhydride-based agents." However, it is a well-known fact in the technical field that commonly used bisphenol F contains a polynuclear compound containing three or more phenolic hydroxyl groups in one molecule in an amount of approximately 20% based on the total amount.

[0015] It was found that when polymerizing ((1) a bifunctional prepolymer in which a functional group is bonded to the end of a molecular chain with low main chain mobility, and (2) a bifunctional compound in which functional groups capable of addition reaction with the end groups of the prepolymer are bonded to both ends) as described in Patent Document 1, if a small amount of trifunctional or higher molecular species is present, a branching reaction will proceed and gelation will occur before the molecular chain can be linearly extended, resulting in an inhomogeneous cured product with low toughness.

[0016] Therefore, an object of the present invention is to provide a curable resin composition and a step-growth polymer thereof that solves the problem of brittleness of heat-resistant crosslinked materials and forms a cured product with excellent toughness. Another object of the present invention is to provide a method for producing a cured product with excellent moldability, which can be produced by on-site molding, without the need for a step of isolating the reaction product of a PPE prepolymer and a bifunctional phenol from the curable resin composition. [Means for solving the problem]

[0017] The present inventors conducted extensive research to solve the above-mentioned problems. As a result, they succeeded in forming a highly tough crosslinked structure or cured product by combining component (A), a bifunctional prepolymer having a predetermined number-average molecular weight and polydispersity, with component (B), a bifunctional compound having a content of trifunctional or higher molecular species of less than 20% and having functional groups capable of addition reaction with the prepolymer end groups attached to both ends, while maintaining a constant molecular chain length and crosslinked. Thus, the present invention has been completed. [1] A curable resin composition comprising the following components (A), (B) and (C): Component (A): [ka] [ka] [ka] A compound defined by formula (1) (In formula (1), -(OXO)- is defined in formula (2), R1, R2, R7, and R8 may be the same or different and each represent a halogen atom, an alkyl group having 6 or less carbon atoms, or a phenyl group. R3, R4, R5, and R6 may be the same or different and each represent a hydrogen atom, a halogen atom, an alkyl group having 6 or less carbon atoms, or a phenyl group. A is a linear, branched, or cyclic hydrocarbon having 20 or fewer carbon atoms, or a direct bond. In formula (1), -(YO)- is one type of structure defined by formula (3), or two or more types of structures defined by formula (3) are randomly arranged. R9, R 10 may be the same or different and each represents a halogen atom, an alkyl group having 6 or less carbon atoms, or a phenyl group. R 11 , R12 may be the same or different and each represents a hydrogen atom, a halogen atom, or an alkyl or phenyl group having 6 or less carbon atoms; a and b each represent an integer of 0 to 30, at least one of which is not 0; The polydispersity is 2.8 or less, A polyphenylene ether prepolymer having a number average molecular weight of 1,000 or more and 5,000 or less. Component (B): A difunctional phenol containing less than 20% of trifunctional or higher molecular species. Component (C): Curing accelerator. [2] In the formula (2), at least R1, R2, R7, and R8 are methyl groups, and the formula (3) has a structure represented by the following formula (4), formula (5), or a structure in which formulas (4) and (5) are randomly arranged. The curable resin composition according to [1]. [ka] [ka] [3] The melting point of the difunctional phenol is 180°C or less. The curable resin composition according to [1] or [2]. [4] The curing accelerator is a phosphorus-based compound. The curable resin composition according to any one of [1] to [3]. [5] Component (E) includes a latent curing agent. The curable resin composition according to any one of [1] to [4]. [6] Further comprising a difunctional epoxy resin as component (D), The curable resin composition according to any one of [1] to [5]. [7] It is shown in the following equation (6): The number average molecular weight is 4000 or more. Step-growth polymer. [ka] [ka] [ka] (In formula (6), -(OXO)- is defined in formula (2), R1, R2, R7, and R8 may be the same or different and each represent a halogen atom, an alkyl group having 6 or less carbon atoms, or a phenyl group. R3, R4, R5, and R6 may be the same or different and each represent a hydrogen atom, a halogen atom, an alkyl group having 6 or less carbon atoms, or a phenyl group. A is a linear, branched, or cyclic hydrocarbon having 20 or fewer carbon atoms, or a direct bond. In formula (6), -(YO)- is one type of structure represented by formula (3), or two or more types of structures defined by formula (3) are randomly arranged. R9, R 10 may be the same or different and each represents a halogen atom, an alkyl group having 6 or less carbon atoms, or a phenyl group. R 11 , R 12 may be the same or different and represent a hydrogen atom, a halogen atom, or an alkyl or phenyl group having 6 or less carbon atoms. a and b represent integers of 0 to 30, at least one of which is not 0. Z is a residue of a bifunctional phenol in which the content of trifunctional or higher functional molecular species is less than 20%, and c is an integer of 0 or greater. [8] The method includes a reaction step of reacting the following components (A) and (B) to obtain a step-growth polymer: Method for producing a cured product. (A): [ka] [ka] [ka] A compound defined by formula (1) (In formula (1), -(OXO)- is represented by formula (2), R1, R2, R7, and R8 may be the same or different and each represent a halogen atom, an alkyl group having 6 or less carbon atoms, or a phenyl group. R3, R4, R5, and R6 may be the same or different and each represent a hydrogen atom, a halogen atom, an alkyl group having 6 or less carbon atoms, or a phenyl group. A is a linear, branched, or cyclic hydrocarbon having 20 or fewer carbon atoms, or a direct bond. In formula (1), -(YO)- is one type of structure represented by formula (3), or two or more types of structures defined by formula (3) are randomly arranged. R9, R 10 may be the same or different and each represents a halogen atom, an alkyl group having 6 or less carbon atoms, or a phenyl group. R 11 , R 12 may be the same or different and each represents a hydrogen atom, a halogen atom, an alkyl group having 6 or less carbon atoms, or a phenyl group; a and b each represent an integer of 0 to 30, at least one of which is not 0; The polydispersity is 2.8 or less, A polyphenylene ether prepolymer having a number average molecular weight of 1,000 or more and 5,000 or less. (B): A difunctional phenol having a content of trifunctional or higher molecular species of less than 20%. [Effects of the Invention]

[0018] According to the present invention, it is possible to provide a curable resin composition and a step-growth polymer thereof that solve the problem of brittleness of heat-resistant crosslinked materials and form a cured product with excellent toughness. Furthermore, on-site molding can be used, which does not involve a step of isolating the reaction product of the PPE prepolymer and the bifunctional phenol from the curable resin composition, and a method for producing a cured product with excellent moldability can be provided. [Brief explanation of the drawings]

[0019] [Figure 1] 1 shows the results of 1H-NMR measurement of Ep-PPE (1) of Example 1. [Figure 2] 1 shows the results of 1H-NMR measurement of the step-growth polymer of Example 1. DETAILED DESCRIPTION OF THE INVENTION

[0020] Hereinafter, an embodiment of the present invention (hereinafter referred to as "the present embodiment") will be described in detail. The present embodiment is an example for explaining the present invention, and the present invention is not limited to this embodiment alone. The present invention can be practiced by appropriately modifying it within the scope of its gist.

[0021] Curable resin composition The curable resin composition of the present embodiment contains component (A), component (B), and component (C), and may contain other components as long as the effects of the present invention are not impaired.

[0022] 1.1. Component (A) Component (A) is a polyphenylene ether prepolymer defined by the following formula (1), with a polydispersity of 2.8 or less and a number average molecular weight of 1,000 to 5,000. Hereinafter, polyphenylene ether will also be referred to as PPE. A prepolymer is a substance with an intermediate structure that is produced by stopping the polymerization reaction or condensation reaction of monomers midway before becoming a final polymer. [ka] [ka] [ka] (In formula (1), -(OXO)- is defined in formula (2), R1, R2, R7, and R8 may be the same or different and each represent a halogen atom, an alkyl group having 6 or less carbon atoms, or a phenyl group. R3, R4, R5, and R6 may be the same or different and each represent a hydrogen atom, a halogen atom, an alkyl group having 6 or less carbon atoms, or a phenyl group. A is a linear, branched, or cyclic hydrocarbon having 20 or fewer carbon atoms, or a direct bond. In formula (1), -(YO)- is one type of structure defined by formula (3), or two or more types of structures defined by formula (3) are randomly arranged. R9, R 10 may be the same or different and each represents a halogen atom, an alkyl group having 6 or less carbon atoms, or a phenyl group. R 11 , R 12 may be the same or different and represent a hydrogen atom, a halogen atom, an alkyl group having 6 or less carbon atoms, or a phenyl group. a and b represent integers of 0 to 30, at least one of which is not 0.

[0023] <-(OXO)-, R1, R2, R7, R8> R1, R2, R7, and R8 in formula (2) are not particularly limited, and examples thereof include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a tertiary butyl group, a pentyl group, a hexyl group, a phenyl group, a bromine atom, and a chlorine atom. Among these, a methyl group is preferred from the viewpoint of smooth oxidative polymerization of the polyphenylene ether (PPE) resin and from the viewpoint of the water absorption and heat resistance of the resin.

[0024] <R3、R4、R5、R6> R3, R4, R5, and R6 in formula (2) are not particularly limited, and examples thereof include a hydrogen atom, a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a tertiary butyl group, a pentyl group, a hexyl group, a phenyl group, a bromine atom, and a chlorine atom. Among these, a hydrogen atom is preferred from the viewpoint of smooth progress of oxidative polymerization of the polyphenylene ether (PPE) resin and from the viewpoint of the water absorption and heat resistance of the resin.

[0025] Furthermore, A in the above formula (2) is not particularly limited, and examples thereof include a direct bond, an isopropylidene group, a methylene group, an ethylidene group, a butylidene group, and a cyclohexylidene group. Among these, from the viewpoint of heat resistance, a direct bond, an isopropylidene group, or a methylene group is preferred, and an isopropylidene group is more preferred.

[0026] <y> -(YO)- is one type of structure defined by the above formula (3) or two or more types of structures defined by the above formula (3) arranged randomly.

[0027] <R9、R 10 > R9, R 10 R and R may be the same or different and each represent a halogen atom, an alkyl group having 6 or less carbon atoms, or a phenyl group. 10 Examples of R are, but are not particularly limited to, a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a tertiary butyl group, a pentyl group, a hexyl group, a phenyl group, a bromine atom, and a chlorine atom. Among these, R and R are preferably selected from the viewpoints of smooth progress of oxidative polymerization of the polyphenylene ether (PPE) resin, water absorption of the resin, and heat resistance. 10 Preferably, at least one of R and R is a methyl group. 10 More preferably, both of the groups are methyl groups.

[0028] <R 11 , R 12 > R 11 , R 12 may be the same or different and represent a hydrogen atom, a halogen atom, an alkyl group having 6 or less carbon atoms, or a phenyl group. 11 , R 12 Although not particularly limited, examples of R include a hydrogen atom, a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a tertiary butyl group, a pentyl group, a hexyl group, a phenyl group, a bromine atom, and a chlorine atom. Among these, R is preferably selected from the viewpoints of smooth progress of oxidative polymerization of the polyphenylene ether (PPE) resin, water absorption of the resin, and heat resistance. 11 and R 12 At least one of R is preferably a hydrogen atom. 11 and R 12 It is more preferable that both of the groups are hydrogen atoms.

[0029] <a、b> a and b are each independently an integer of 0 to 30, with at least one not being 0. The larger the values ​​of a and b, the larger the molecular weight of component (A) and the toughness of the cured product tends to increase, while the smaller the values ​​of a and b, the more moldable the product tends to be. The values ​​of a and b mentioned above are linked to the molecular weight of the PPE prepolymer, so the values ​​of a and b suitable for carrying out the present invention depend on the structure of A and / or R1 to R 12 The suitable value varies depending on the structure of the

[0030] The values ​​of a and b, and the structure of A and / or R1 to R 12 The combination of the structures is not particularly limited, but for example, A is a propylidene group, R1, R2, R7, R8, R9, R 10 is a methyl group, R3, R4, R5, R6, R 11 , R 12 When a is a hydrogen atom, the sum of a and b is preferably in the range of 40 (number average molecular weight 4922) to 7 (number average molecular weight 1094), more preferably 36 (number average molecular weight 4458) to 11 (number average molecular weight 1558), even more preferably 32 (number average molecular weight 3994) to 15 (number average molecular weight 2022), and particularly preferably 28 (number average molecular weight 3530) to 19 (number average molecular weight 2486).

[0031] <Polydispersity> The PPE prepolymer of component (A) of the present invention has a polydispersity of 2.8 or less. In this embodiment, polydispersity is defined as the ratio (Mw / Mn) of the number average molecular weight (Mn) to the weight average molecular weight (Mw) measured by gel permeation chromatography (GPC). A smaller polydispersity is preferred because it results in a sharper molecular weight distribution curve and a lower melt viscosity, which results in excellent moldability and, as a result, enables the formation of a cured product with excellent toughness.

[0032] From this viewpoint, the polydispersity of the PPE prepolymer of component (A) is 2.8 or less, preferably 2.5 or less, more preferably 2.0 or less, even more preferably 1.8 or less, even more preferably 1.7 or less, and particularly preferably 1.5 or less.

[0033] The synthesis method for PPE oligomers with low polydispersity is not particularly limited, but known methods such as those described in Patent No. 4007828 can be used. Specifically, they can be synthesized by oxidatively copolymerizing a dihydric phenol and a monohydric phenol in a poor solvent. Examples of poor solvents include methanol, ethanol, n-propanol, iso-propanol, n-butanol, iso-butanol, sec-butanol, tert-butanol, n-pentanol, n-hexanol, cyclohexanol, n-heptanol, and n-octanol. These solvents may be used alone or in combination. The method for adjusting the polydispersity is not particularly limited, but for example, the polydispersity tends to decrease as the amount of the poor solvent used increases.

[0034] <Number average molecular weight 1000 or more and 5000 or less> The PPE prepolymer of component (A) has a number-average molecular weight of 1,000 or more and 5,000 or less. The lower the number-average molecular weight, the better the moldability tends to be when the composition is cured, while the higher the number-average molecular weight, the higher the toughness of the cured product. From the viewpoint of achieving both moldability when cured and toughness of the cured product, the number-average molecular weight is preferably 1,500 to 4,500, more preferably 2,000 to 4,000, and particularly preferably 2,500 to 3,500.

[0035] <Method for synthesizing component (A)> The PPE prepolymer having epoxy groups at both ends, which is component (A), is not particularly limited, but can be obtained, for example, by subjecting a PPE oligomer represented by the following formula (8) to a dehydrohalogenation reaction using a glycidyl halide such as epichlorohydrin and a base, in the presence or absence of a catalyst such as a quaternary ammonium. [ka] (In formula (8), -(OXO)-, R1, R2, R7, R8, R3, R4, R5, R6, A, -(YO)-, R9, R 10 , R 11 , R 12 , a, and b are the same as in the above formulas (1) to (3).

[0036] The PPE oligomer represented by the above formula (8) is not particularly limited, but can be obtained, for example, by oxidative copolymerization of a dihydric phenol and a monohydric phenol.

[0037] The synthesis method of PPE oligomers with low polydispersity is not particularly limited, but is described, for example, in Japanese Patent No. 4007828. That is, they can be synthesized by oxidative copolymerization of dihydric phenol and monohydric phenol in a poor solvent. The poor solvent is not particularly limited, but examples thereof include methanol, ethanol, n-propanol, iso-propanol, n-butanol, iso-butanol, sec-butanol, tert-butanol, n-pentanol, n-hexanol, cyclohexanol, n-heptanol, and n-octanol. These solvents may be used alone or in combination of two or more.

[0038] Here, the dihydric phenol is not particularly limited, but examples thereof include 4,4'-methylenebis(2,6-dimethylphenol), 4,4'-(1-methylethylidene)bis(2,6-dimethylphenol), 4,4'-methylenebis(2,3,6-trimethylphenol), 4,4'-cyclohexylidenebis(2,6-dimethylphenol), 4,4'-(phenylmethylene)bis(2,3,6-trimethylphenol), 4,4'-[1,4-phenylenebis(1-methylethylidene)]bis(2,6-di methylphenol), 4,4'-methylenebis[2,6-bis(1,1-dimethylethyl)phenol], 4,4'-cyclopentylidenebis(2,6-dimethylphenol), 4,4'-(2-furylmethylene)bis(2,6-dimethylphenol), 4,4'-(1,4-phenylenebismethylene)bis(2,6-dimethylphenol), 4,4'-(3,3,5-trimethylcyclohexidene)bis(2,6-dimethylphenol), 4,4'-[4-(1-methylethyl)cyclohexylidene]bis( 2,6-dimethylphenol), 4,4'-(4-methylphenylethylene)bis(2,3,6-trimethylphenol), 4,4'-(1,4-phenylenebismethylene)bis(2,3,6-trimethylphenol), 4-[1-[4-(4-hydroxy-3,5-dimethylphenyl)-4-methylcyclohexyl]-1-methylethyl]-2,6-dimethylphenol, 4,4'-(4-methoxyphenylmethylene)bis(2,3,6-trimethylphenol), 4,4'-[4-(1-methylethyl)phenyl] [phenylmethylene]bis(2,3,6-trimethylphenol), 4,4'-(9H-fluoren-9-ylidene)bis(2,6-dimethylphenol), 4,4'-[1,3-phenylenebis(1-methylethylidene)]bis(2,3,6-trimethylphenol), 4,4'-(1,2-ethanediyl)bis[2,6-di-(1,1-dimethylethyl)phenol], and 5,5'-(1-methylethylidene)bis[3-(1,1-dimethylethyl)-1,1-biphenyl-2-ol].

[0039] The monohydric phenol is not particularly limited, but examples thereof include 2,6-dimethylphenol and 2,3,6-trimethylphenol.

[0040] The oxidation method is not particularly limited, but examples thereof include a method that directly uses oxygen gas or air, and an electrode oxidation method. Among these, air oxidation is preferred from the viewpoints of safety and low capital investment.

[0041] The catalyst for oxidative polymerization using oxygen gas or air is not particularly limited, but for example, one or more of copper salts such as CuCl, CuBr, Cu2SO4, CuCl2, CuBr2, CuSO4, and CuI can be used. In addition to the above catalysts, mono- and diethylamine, mono- and dipropylamine, mono- and di-n-butylamine, mono- and di-sec-dipropylamine, mono- and dibenzylamine, mono- and dicyclohexylamine, mono- and diethanolamine, ethylmethylamine, methylpropylamine, amine, butyldimethylamine, allylethylamine, methylcyclohexylamine, morpholine, methyl-n-butylamine, ethylisopropylamine, benzylmethylamine, octylbenzylamine, octylchlorobenzylamine, methyl(phenylethyl)amine, benzylethylamine, Nn-butyldimethylamine, N,N'-di-tert-butylethylenediamine, di(chlorophenylethyl)amine, 1-methylamino-4-pentene, pyridine, methylpyridine, 4-dimethylaminopyridine, piperidine, etc. These may be used alone or in combination of two or more.

[0042] Next, an example of a method for synthesizing the PPE prepolymer of component (A) will be described. The PPE oligomer represented by the above formula (8) can be synthesized by subjecting a glycidyl halide such as epichlorohydrin to a dehydrohalogenation reaction in the presence of a base. In this case, epoxidation with a higher purity tends to be achieved by first heating the PPE oligomer and the glycidyl halide such as epichlorohydrin in the presence of a quaternary ammonium salt such as tetramethylammonium chloride before adding the base.

[0043] The base is not particularly limited, but examples thereof include sodium hydroxide, potassium hydroxide, sodium methoxide, sodium ethoxide, calcium hydroxide, sodium carbonate, potassium carbonate, and sodium bicarbonate.

[0044] The reaction temperature in the above dehydrohalogenation reaction is preferably between -10°C and 150°C.

[0045] 1.2.Component (B) Component (B) is a difunctional phenol having a trifunctional or higher molecular species content of less than 20%.

[0046] <Content of trifunctional or higher functional molecular species> Component (B) contains less than 20% trifunctional or higher molecular species. Here, trifunctional or higher molecular species refer to impurities contained in bifunctional phenols with a phenolic hydroxyl group having three or more functionalities. For example, it is well known in the art that commercially available bisphenol F contains trifunctional phenol molecular species in addition to the typical bifunctional phenol molecule. The higher the content of trifunctional or higher molecular species, the more likely it is that when reacted with a PPE prepolymer, gelation will occur before the molecular weight increases sufficiently, resulting in a final cured product with low toughness, since the molecular weight of each molecule will not reach the desired value.

[0047] Therefore, the content of tri- or higher functional molecular species in the bifunctional phenol, component (B) in this embodiment, is less than 20%, preferably less than 15%, more preferably less than 10%, even more preferably less than 5%, and particularly preferably less than 1%.

[0048] Commercially available products that can be used as component (B) are not particularly limited, but examples include "BPF-SG" manufactured by Gun-ei Chemical Co., Ltd., which is bisphenol F with a trifunctional or higher molecular species content of less than 1%, and "Bisphenol F" manufactured by Honshu Chemical Co., Ltd., which is bisphenol F with a trifunctional or higher molecular species content of 8% or more but less than 15%.

[0049] <Melting point of bifunctional phenol of component (B)> The difunctional phenol of component (B) preferably has a low melting point, because the lower the melting point, the lower the temperature at which the composition becomes fluid and a uniform cured product tends to be formed. From this perspective, the melting point of the difunctional phenol of component (B) is preferably 230°C or lower, more preferably 200°C or lower, even more preferably 180°C or lower, even more preferably 160°C or lower, even more preferably 140°C or lower, even more preferably 130°C or lower, even more preferably 120°C or lower, even more preferably 110°C or lower, and particularly preferably 100°C or lower.

[0050] Examples of bifunctional phenols having a melting point of 250°C or less include, but are not limited to, tetramethylbiphenol (melting point 225°C). Examples of bifunctional phenols having a melting point of 180°C or less include, but are not limited to, tetramethylbisphenol A (melting point 165°C) and tetramethylbisphenol F (melting point 162°C). Examples of bifunctional phenols having a melting point of 160°C or less include, but are not limited to, bisphenol A (melting point 158°C). Examples of bifunctional phenols having a melting point of 140°C or less include, but are not limited to, 1,6-dihydroxynaphthalene (melting point 135°C). Examples of bifunctional phenols having a melting point of 130°C or less include, but are not limited to, tertiary butylhydroquinone (melting point 127°C). The bifunctional phenol having a melting point of 120°C or less is not particularly limited, but examples thereof include bisphenol F (120°C) manufactured by Mitsui Chemicals, Inc., which has a content of trifunctional or higher functional molecular species of less than 15%. The bifunctional phenol having a melting point of 100°C or less is not particularly limited, but examples thereof include bisphenol F ("BPF-SG" manufactured by Gun-ei Chemical Co., Ltd., melting point 100°C) which has a content of trifunctional or higher functional molecular species of less than 1%. The above bifunctional phenols may be used alone or in combination of two or more.

[0051] <Compatibility of ingredients (A) and (B)> From the viewpoint of improving the uniformity of the resulting cured product, it is preferable that components (A) and (B), which are constituent elements of the curable resin composition of the present invention, are compatible before the start of curing. Furthermore, compatibility tends to be enhanced when the bifunctional phenol of component (B) contains an alkyl substituent. Furthermore, the fewer the carbon atoms in the alkyl substituent, the more excellent the heat resistance tends to be. From the viewpoint of improving the uniformity of the resulting cured product and improving the compatibility of components (A) and (B), the number of carbon atoms contained in the alkyl substituent is preferably 1 to 8, more preferably 2 to 6, even more preferably 3 to 5, and particularly preferably 4.

[0052] <Phenol hydroxyl group / epoxy group equivalent ratio (r)> The phenolic hydroxyl group / epoxy group equivalent ratio (r) is the stoichiometric ratio of the number of moles of phenolic hydroxyl groups to the number of moles of epoxy groups. The mixing ratio of components (A) and (B) is not particularly limited. However, controlling the mixing ratio of the epoxy groups contained in component (A) to the OH groups contained in component (B) tends to increase the molecular weight of the polymer formed by the reaction of components (A) and (B), making it easier to obtain a molecular weight suitable for this embodiment. From this perspective, the molar equivalent ratio r (=phenolic hydroxyl groups / epoxy groups) of the phenolic hydroxyl groups of component (B) to the epoxy groups of component (A) is preferably 0.3 to 2.0, more preferably 0.4 to 1.2, even more preferably 0.5 to 1.0, even more preferably 0.6 to 0.99, even more preferably 0.7 to 0.95, even more preferably 0.8 to 0.94, and particularly preferably 0.85 to 0.93.

[0053] 1.3.Component (C) <Component (C): Curing accelerator> The curable resin composition of this embodiment contains a curing accelerator as component (C), which accelerates the sequential polymerization reaction of components (A) and (B).

[0054] <(C) Curing accelerator is a phosphorus-based compound> The curing accelerator is not particularly limited, but examples thereof include tertiary amines such as 1,8-diazabicyclo(5,4,0)undecene-7, triethylenediamine, and benzyldimethylamine; imidazoles such as 2-methylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole, and 2-phenyl-4-methylimidazole; and organic phosphorus compounds such as tributylphosphine, triphenylphosphine, and tetraphenylphosphonium tetra-p-tolylborate. Among these, from the viewpoint of excellent electrical properties of the resulting cured product, component (C) is preferably a phosphorus-based compound, more preferably an organic phosphorus-based compound. Furthermore, from the viewpoint of the resulting cured product not losing activity even at high temperatures, tetraphenylphosphonium tetra-p-tolylborate is particularly preferred. These curing accelerators may be used alone or in combination of two or more.

[0055] <When a latent hardener is included as component (E)> The curable resin composition of the present embodiment preferably contains a latent curing agent as component (E). In addition, when component (C) is both a curing accelerator and a latent curing agent, the curable resin composition of the present embodiment also contains component (E). In the present embodiment, the latent curing agent is a curing agent that does not react with epoxy groups below a certain temperature, but exhibits reactivity under temperature conditions above a certain temperature.

[0056] When the phenolic hydroxyl group / epoxy group equivalent ratio (r) is smaller than 1 and a latent curing agent is contained as component E, polymerization between epoxy groups tends to proceed smoothly even when the curable resin composition is heated and the step-growth polymerization reaction proceeds, the molecular weight of the step-growth polymer increases, and the terminal epoxy groups of component (A) are consumed by polymerization, resulting in a decrease in the content of the epoxy groups.

[0057] The latent curing agent is not particularly limited, but examples include compounds that have a low ability to cause the epoxy groups at the terminals of component (A) to react with each other in the low temperature range of 150°C or lower, and that efficiently exhibit the function of causing the epoxy groups at the terminals of component (A) to react with each other in the temperature range of higher than 150°C.Specific examples of the latent curing agent include, but are not particularly limited to, imidazoles with a melting point higher than 150°C, quaternary ammonium salts with a melting point higher than 150°C, and onium salts such as quaternary phosphonium salts.

[0058] Imidazoles having a melting point higher than 150°C are not particularly limited, and examples thereof include 2-phenyl-4,5-dihydroxymethylimidazole, 2,4-diamino-6-[2'-methylimidazolyl-(1')]-ethyl-s-triazine, 2,4-diamino-6-[2'-methylimidazolyl-(1')]-ethyl-s-triazine isocyanuric acid adduct, 2,4-diamino-6-[2'-undecylimidazolyl-(1')]-ethyl-s-triazine, and 2,4-diamino-6-[2'-ethyl-4'-methylimidazolyl-(1')]-ethyl-s-triazine. Quaternary ammonium salts having a melting point higher than 150°C are not particularly limited, but examples thereof include tetrabutylammonium tetraphenylborate, tetraethylammonium p-toluenesulfonate, and tetramethylammonium acetate, while quaternary phosphonium salts having a melting point higher than 150°C are not particularly limited, but examples thereof include tetraphenylphosphonium tetra-p-tolylborate and tetraphenylphosphonium tetraphenylborate. Among these latent curing agents, tetraphenylphosphonium tetra-p-tolylborate is preferred because it functions well as an accelerator in the step-growth polymerization reaction of component (A) and component (B) in the temperature range of 180°C or lower, while suppressing the polymerization reaction of epoxy groups, and tends to promote the polymerization reaction of epoxy groups in the temperature range of 180°C or higher.

[0059] These latent curing agents may be used alone or in combination of two or more. Furthermore, by using a curing accelerator that falls under the category of a latent curing agent in combination with a curing accelerator that does not fall under the category of a latent curing agent, step-growth polymerization proceeds smoothly at low temperatures, and epoxy group polymerization proceeds smoothly at high temperatures, which tends to result in the formation of a cured product that has high toughness, a high glass transition temperature, and a uniform structure.

[0060] <Content of curing accelerator, component (C)> The content of the curing accelerator, component (C), is not particularly limited, but is, for example, preferably 0.1 to 20 parts by mass, more preferably 0.5 to 10 parts by mass, even more preferably 1 to 7 parts by mass, and even more preferably 3 to 5 parts by mass, relative to 100 parts by mass of component (A). The curing accelerator, component (C), may be used alone, or multiple curing accelerators may be used in combination.

[0061] 1.4.Component (D) <Component (D): Difunctional epoxy resin> Since the curable resin composition of this embodiment is a crosslinked heat-resistant resin composition, it may further contain a difunctional epoxy resin as component (D) as needed, within the scope of not impairing the object of the present invention by causing a decrease in heat resistance or toughness, a non-uniform appearance of the cured product, etc. Blending a difunctional epoxy resin may increase the fluidity of the composition at a stage before the start of the sequential polymerization reaction, resulting in excellent moldability.

[0062] Such bifunctional epoxy resins are not particularly limited, but examples include biphenyl-type epoxy resins, naphthalene-skeleton-type epoxy resins, bisphenol A-type epoxy resins, bisphenol F-type epoxy resins, tetramethylbiphenyl-type epoxy resins, tetramethylbisphenol A-type epoxy resins, tetramethylbisphenol F-type epoxy resins, bisphenol E-type epoxy resins, and bisphenol C-type epoxy resins. Among these, from the viewpoint of high heat resistance of the resulting cured product, tetramethylbiphenyl-type epoxy resins, naphthalene-skeleton-type epoxy resins, and bisphenol A-type epoxy resins are preferred, and tetramethylbiphenyl-type epoxy resins and naphthalene-skeleton-type epoxy resins are more preferred. The bifunctional epoxy resins of component (D) may be used alone or in combination of two or more.

[0063] The step-growth polymer of this embodiment is represented by the following formula (6) and has a number average molecular weight of 4000 or more. The step-growth polymer of this embodiment can be produced by step-growth polymerization of component (A) and component (B) of this embodiment. <Sequence-growth polymer represented by formula (6)> [ka] Here, -(OXO)-, R1, R2, R7, R8, R3, R4, R5, R6, A, -(YO)-, R9, and R 10 , R 11 , R 12 , a, and b are the same as in formulas (1) to (3).

[0064] <c in formula (6)> In formula (6), c is a positive real number greater than 0. For each molecular species, c is an integer greater than or equal to 0, but because formula (6) has a number-average aspect, c in formula (6) means a real number that is the average value of c for each molecular species. The value of c in formula (6) is uniquely determined by the number-average molecular weight and partial chemical structure described below.

[0065] <Z in formula (6)> Z in formula (6) represents a residue obtained by removing a hydroxyl group structure from the bifunctional phenol, which is component (B). Examples of such bifunctional phenols include, but are not limited to, hydroquinone, resorcinol, catechol, tertiary butyl catechol, tertiary butyl hydroquinone, tertiary butyl resorcinol, dihydroxybiphenyl, naphthalenediol, bisphenol A, bisphenol F, tetramethylbiphenol, tetramethylbisphenol A, tetramethylbisphenol F, bisphenol E, and bisphenol. From the viewpoint of high heat resistance of the resulting cured product, tetramethylbiphenol, naphthalenediol, or bisphenol A is preferred, and tertiary butyl hydroquinone, tetramethylbiphenol, or dihydroxynaphthalene is more preferred.

[0066] <Number average molecular weight of the step-growth polymer represented by formula (6)> The larger the number average molecular weight of the step-growth polymer represented by formula (6), the higher the toughness of the cured product tends to be, and the smaller the number average molecular weight, the lower the viscosity of the curable resin composition before curing tends to be, thereby tending to provide excellent moldability. From this perspective, the number average molecular weight of the step-growth polymer represented by formula (6) is preferably 3,000 to 50,000, more preferably 4,000 to 40,000, even more preferably 5,000 to 30,000, still more preferably 6,000 to 20,000, even more preferably 8,000 to 15,000, and particularly preferably 9,000 to 12,000.

[0067] <Contains PPE at one end> The PPE prepolymer of component (A) may contain a PPE having one epoxidized end, as shown in formula (7), within the range that does not impair the object of the present invention, such as by reducing heat resistance. [ka] (R9, R 10 , R 11 , R 12 is the same as equation (3). d is a real number greater than 1.

[0068] <Content of one-terminal PPE> From the viewpoint of reducing viscosity and improving moldability, the PPE prepolymer of component (A) preferably contains 1 to 30% by mole of the one-terminal epoxidized PPE represented by formula (7). Here, the mole fraction of the one-terminal epoxidized PPE represented by formula (7) can be determined from the stoichiometric ratio of the number of protons in the terminal epoxy group and the protons assigned to the A structure in formula (2) of component (A) in proton NMR measurement.

[0069] <Other ingredients> The curable resin composition of the present embodiment is not particularly limited, but may contain, if necessary, an inorganic filler, for example, an inorganic powder such as silica, alumina, etc. The suitable content of the inorganic filler varies depending on the application, but is preferably 5 to 90% by weight, more preferably 10 to 50% by weight, based on the total amount of component (A), component (B), component (C), and the inorganic filler.

[0070] The inorganic filler may be surface-treated with a coupling agent to improve compatibility with component (A), although this is not particularly limited. Examples of the coupling agent include, but are not limited to, silane coupling agents such as γ-glycidoxypropyltrimethoxysilane, γ-aminopropyltriethoxysilane, and N-phenyl-γ-aminopropyltrimethoxysilane.

[0071] The curable resin composition of the present embodiment may contain, but is not particularly limited to, a release agent, a colorant, a flame retardant, a stress reducing agent, and the like, as needed.

[0072] The release agent is not particularly limited, but examples thereof include carnauba wax, stearic acid, montanic acid, and carboxyl group-containing polyolefin, etc. The colorant is not particularly limited, but examples thereof include carbon black, etc. The flame retardant is not particularly limited, but examples thereof include antimony trioxide, etc., and the low stress agent is, for example, silicone gel, silicone rubber, silicone oil, etc.

[0073] <Solvent> Alternatively, a varnish may be prepared using the curable resin composition of the present embodiment in a solvent, and then the varnish may be impregnated into glass fiber or carbon fiber, followed by drying and pressing to form a composite material. The solvent is not particularly limited, but examples thereof include hydrocarbons such as toluene and xylene, ketones such as methyl ethyl ketone, methyl isobutyl ketone and acetone, and chlorine-based organic solvents such as chloroform and methylene chloride.

[0074] <Other hardeners> The curable resin composition of this embodiment can use a curing agent within a range that does not impair the object of the present invention of increasing toughness. Here, the curing accelerator in this embodiment has the effect of accelerating the addition reaction between the epoxy group and the phenolic hydroxyl group, while the curing agent means a substance that undergoes an addition reaction with the epoxy group and is incorporated into the structure of the step-growth polymer.

[0075] Such curing agents are not particularly limited, but examples thereof include phenol-based curing agents such as phenol novolac and cresol novolac, and amine-based curing agents such as diaminodiphenylmethane, diaminodiphenylpropane, diaminodiphenylsulfone, and diaminodiphenylether.

[0076] 2. Manufacturing method of the cured product The method for producing a cured product of the present embodiment includes a reaction step of reacting the following components (A) and (B) to obtain a step-growth polymer, and may include other steps as necessary. (A): [ka] [ka] [ka] (In formula (1), -(OXO)- is represented by formula (2), R1, R2, R7, and R8 may be the same or different and each represent a halogen atom, an alkyl group having 6 or less carbon atoms, or a phenyl group. R3, R4, R5, and R6 may be the same or different and each represent a hydrogen atom, a halogen atom, an alkyl group having 6 or less carbon atoms, or a phenyl group. A is a linear, branched, or cyclic hydrocarbon having 20 or fewer carbon atoms, or a direct bond. In formula (1), -(YO)- is one type of structure represented by formula (3), or two or more types of structures defined by formula (3) are randomly arranged. R9, R 10 may be the same or different and each represents a halogen atom, an alkyl group having 6 or less carbon atoms, or a phenyl group. R 11 , R 12 may be the same or different and represent a hydrogen atom, a halogen atom, an alkyl group having 6 or less carbon atoms, or a phenyl group; a and b represent integers of 0 to 30, at least one of which is not 0; The polydispersity is 2.8 or less, PPE prepolymers having a number average molecular weight of 1,000 or more and 5,000 or less; (B): Bifunctional phenols with a content of trifunctional or higher molecular species of less than 20%;

[0077] The method for producing a cured product of the present embodiment is characterized by not adding a solvent in the step-growth polymerization reaction stage, and therefore can provide a curing method using on-site molding that does not include a step of isolating the reaction product of the PPE prepolymer and the bifunctional phenol from the curable resin composition.

[0078] The reaction step of sequentially polymerizing component (A) and component (B) to obtain a sequential polymer is not particularly limited and can be carried out by a conventionally known method. As a specific method, the method described in the following examples can be used.

[0079] The method for producing the cured product of the present embodiment may include a step of preparing a PPE prepolymer of component (A) as a pre-step of the above reaction step. The step of preparing component (A) is not particularly limited, and for example, the above-described method can be used.

Examples

[0080] Next, the present invention will be specifically described based on examples, but the present invention is not particularly limited by the following examples.

[0081] First, the physical properties of the materials used, the measurement methods and evaluation criteria for evaluation will be described below.

[0082] <PPE oligomer> As the PPE oligomer corresponding to formula (8), Zylon TM SSL-NX of Asahi Kasei Corporation was used. Zylon TM The properties of Zylon Number average molecular weight: 2960 Weight average molecular weight: 4760 Polydispersity: 1.61 Content of PPE with one-terminal OH group: 14 [mol%] Content of terminal OH group: 0.831 [meq. / g] <着

[0083] [[]END]] <Tensile testing machine> The tensile test was carried out in accordance with JIS-K-7161-2 using a 1BB-shaped test piece at a crosshead speed of 2 mm / min. The toughness of the cured product was evaluated by the tensile strength and the tensile elongation.

[0084] <Measurement of glass transition temperature (Tg) by dynamic viscoelasticity (DMA)> The dynamic viscoelasticity of the resulting cured product was measured using a TA DMA850 under the following conditions. Test piece: Strip, Measurement mode: Tension mode Test start temperature: 25℃ Heating rate: 4°C / min Maximum test temperature: 300℃ Maximum temperature holding time: 5 minutes Measurement frequency: 10Hz The tan δ peak was taken as Tg.

[0085] <Appearance of molded product> The appearance of the resulting cured product was evaluated visually by a person skilled in the art.

[0086] <Molecular weight measurement (GPC)> The molecular weight was measured using an LC-10AD (Shimadzu Corporation) with a calibration curve prepared using standard polystyrene. The number average molecular weights (Mn) of the resulting PPE prepolymer and step-growth polymer were measured using this calibration curve.

[0087] The polystyrene standards used had molecular weights of 580, 1050, 1200, 1310, 1990, 2970, 4490, 5030, 6180, 6930, 10700, 16500, 19800, 55100, 133000, 288000, 666000, 1280000, and 2780000. Two Shodex LF-804 columns (manufactured by Resonaq Co., Ltd.) connected in series were used. The solvent used was THF, with a solvent flow rate of 1.0 mL / min and a column temperature of 40°C. A differential refractometer (RID-10A, manufactured by Shimadzu Corporation) was used as the detector.

[0088] The number average molecular weight (Mn), weight average molecular weight (Mw) and polydispersity index were calculated from the peak area ratio based on the curve showing the molecular weight distribution obtained by GPC based on the above measurement data.

[0089] <Epoxy group content> The epoxy group content of the epoxy group-containing compound is 1 Quantitative determination was performed by H-NMR measurement using 1,4-bis(trifluoromethyl)benzene as an internal standard. Measurement equipment: Superconducting Fourier transform nuclear magnetic resonance measurement equipment (JNM-EX400 manufactured by Nippon Datum Co., Ltd.) Sample amount: approx. 1.0 mg Measurement solvent: deuterated chloroform (CDCl3), deuterated dimethyl sulfoxide (DMSO) approx. 5 mL Internal standard: tetramethylsilane (TMS) Magnetic strength: 400 MHz Accumulation count: 16 times

[0090] <Epoxy group residual rate> The residual epoxy group rate of the curable resin composition before and after heating was measured by adding KBr (Fujifilm Wako Pure Chemical Industries, Ltd.) to the powder sample, mixing in an agate mortar, and then pressing with a handy press (Shimadzu Corporation). The material was pressure-molded into a disk shape, and measured by FT-IR under the following conditions, and the following calculation formula was used. Measurement equipment: Fourier transform infrared absorption measurement equipment (Spectrum 100, manufactured by Perkin Elmer) Measurement range: 5000~400 cm-1 Number of times accumulated: 4 times Resolution: 4 cm-1 The residual rate of epoxy groups was calculated using the following formula. Epoxy residual rate = [ (Se / Sb) / (Se0 / Sb0)] × 100 Se: Peak area of ​​epoxy group after heating (915 cm-1) Sb: benzene peak area after heating (1605 cm-1) Se0: Peak area of ​​epoxy group before heating (915 cm-1) Sb0: benzene peak area before heating (1605 cm-1)

[0091] The methods for producing Ep-PPE in each synthesis example, and the curable resin compositions in the examples and comparative examples will be described below.

[0092] [Synthesis Example 1] Synthesis of Ep-PPE (1) (PPE prepolymer of component (A)) A 500ml flask was filled with Asahi Kasei's "Zylon TM SSL-NX" (75 g, PhOH 62.3 mmol), 375 g (4.05 mol) of epichlorohydrin, and 0.75 g of tetramethylammonium chloride (TMAC) were added, and the mixture was heated under reflux for 2 hours. After cooling to 55°C, 3.74 g of solid NaOH (NaOH / PhOH = 1.5 eq. / eq.) was added and stirred for 2 hours. The mixture was then depressurized and allowed to react for another hour under azeotropic dehydration conditions. 150 g of distilled water was then added and stirred for 2 minutes. The mixture was then transferred to a separatory funnel and washed four times. The mixture was then transferred to a recovery flask, and the epichlorohydrin was removed using an evaporator (oil bath: 170°C). Toluene was added to replace the solvent, resulting in a 50% resin solution in toluene. Next, a separable flask was fitted with a Teflon anchor stirrer, and 350 g of methanol was added and stirred. A 50% resin solution in toluene was added dropwise from the dropping funnel, while monitoring the dispersion in the flask. The precipitate was then collected by suction and dried to obtain 75 g of Ep-PPE (1) (PPE prepolymer of component (A)).

[0093] The number average molecular weight of the Ep-PPE (1) obtained above was 3060, the weight average molecular weight was 4990 (polydispersity index: 1.63), and the epoxy group content was 0.79 [meq. / g].

[0094] Regarding Ep-PPE(1) 1 The results of H-NMR are shown in Figure 1. Based on the ratio of protons derived from the epoxy end groups and isopropylidene, the content of monofunctional PPE was found to be 20 mol%. The peaks (a) to (f) in Figure 1 were found to correspond to the following structures. [ka]

[0095] [Synthesis Example 2] Synthesis of Ep-PPE (2) (Ep-PPE with high polydispersity) A 500 ml three-neck flask was equipped with a Dimroth valve and a pressure-equalizing dropping funnel. After purging the flask with nitrogen, 100 g of raw material polyphenylene ether S202A (Asahi Kasei) and 100 g of toluene were added, followed by 7.2 g of bisphenol A. A thermometer was installed in the flask, and the flask was heated to 90 °C in an oil bath while stirring with a magnetic stirrer to dissolve the raw material polyphenylene ether polymer. As an initiator, 37.5 g of a 40% meta-xylene solution (NOF Corp.: Niper BMT) of a mixture of benzoyl peroxide, benzoyl m-methylbenzoyl peroxide, and m-toluyl peroxide was diluted in 87.5 g of toluene and charged to the pressure-equalizing dropping funnel.

[0096] The reaction started when the initiator solution began to drip into the flask. The initiator was dripped over 2 hours, and stirring was continued at 80°C for 4 hours after dripping. A redistribution reaction was performed to obtain a solution of low-molecular-weight phenol-modified PPE with phenolic hydroxyl groups from the phenolic compound at the terminals. The molecular weight distribution of this solution was measured using gel permeation chromatography, revealing a number-average molecular weight of 1900 and a weight-average molecular weight of 5700 (polydispersity index 3.0). Next, 10 g of epichlorohydrin and 8 g of a 50% aqueous sodium hydroxide solution were added to 250 g of this solution, and the mixture was stirred at 100°C for 4 hours. The mixture was then cooled to room temperature, and 1 L of methanol was added to precipitate the modified PPE with epoxy groups at the terminals. The precipitate was filtered, washed twice with 1 L of methanol and 1 L of water, and finally washed with 1 L of methanol. The modified PPE was then purified by drying under reduced pressure at 70°C. The number-average molecular weight of the resulting Ep-PPE (2) was 2200, the weight-average molecular weight was 7000 (polydispersity index: 3.2), and the epoxy group content was 0.70 [meq. / g].

[0097] Example 1 2.5 g of the Ep-PPE (1) obtained above (epoxy group 1.98 meq.), 0.148 g of tetramethylbisphenol A (TMBA) (phenolic hydroxyl group 1.04 meq., phenolic hydroxyl group / epoxy group (r) = 0.5 [eq. / eq.]), 0.075 g of tetraphenylphosphonium tetra-p-tolylborate (TPP-TTB), and 5 g of toluene were added and stirred at room temperature for 2 hours. The resulting varnish was cast and dried at 120°C for 10 minutes to obtain a solid resin composition (1). The resulting solid resin composition was filled into several molds and cured using a vacuum press.

[0098] The curing conditions were as follows: temperature increase from room temperature to 180°C at a rate of 4°C / min, hold at 180°C for 5 hours, temperature increase from 180°C to 200°C at a rate of 4°C / min, hold at 200°C for 1 hour, temperature increase from 200 to 220°C at a rate of 4°C / min, and hold at 220°C for 1 hour.

[0099] During the above curing process, samples were taken out at 1 hour, 3 hours, and 5 hours after starting to hold the temperature at 180°C, and at 1 hour after starting to hold the temperature at 200°C, and GPC and FT-IR measurements were performed. Applied pressure is 40kgf / cm 2 It was decided. As a result, when a skilled person visually inspected the sample 5 hours after starting to hold it at 180°C, it was found that no gelation had occurred, and GPC measurement revealed that the number average molecular weight was 10,500. 1 The results of H-NMR measurement are shown in Figure 2. FT-IR of the step-growth polymer 5 hours after starting to hold at 180°C showed that the residual epoxy group rate was 3%. The physical properties of the final cured product are shown in Table 1.

[0100] (Examples 2 to 8 and Comparative Examples 1 and 2) As shown in Table 1, except that the materials and contents were changed, intermediate samples and cured resin products were prepared in the same manner as in Example 1, and the physical properties were measured and evaluated. The results are shown in Table 1.

[0101] [Table 1]

[0102] The abbreviations for the materials used in Table 1 are as follows: (Bifunctional phenol) TMBA: Tetramethylbisphenol A BisF-1: Gunei Chemical Co., Ltd. BPF-SG, binuclear content 99% or more, melting point 100°C BisF-2: Honshu Chemical Co., Ltd. Bisphenol F, dinuclear content 90%, melting point 120°C BisF-3: Bisphenol F, dinuclear content 70%, melting point 130°C tBHQ: tertiary butyl hydroquinone, melting point 127°C (catalyst) TPP-TTB: tetraphenylphosphonium tetra-p-tolylborate 2PHZ-PW: Shikoku Chemicals Co., Ltd., 2-phenol-4,5-dihydroxymethylimidazole 2E4MI: 2-ethyl-4-methylimidazole (Other ingredients) jER828: Mitsubishi Chemical Corporation Bisphenol A liquid epoxy resin

[0103] In Table 1, "Ep-PPE" means polyphenylene ether prepolymer defined by formula (1), "PhOH / Ep" means the equivalent ratio r of phenolic hydroxyl groups / epoxy groups, and "phr" means the ratio of parts by mass of component (C) to 100 parts by mass of component (A). The term "molecular weight during curing" refers to the molecular weight of the polymer obtained by the step-growth polymerization 5 hours after the start of holding the temperature at 180°C under the above-mentioned curing conditions. [Industrial Applicability]

[0104] The curable resin composition of the present invention has industrial applicability because the cured product can be used as a composite structural material, an electric / electronic material, etc.< / y>

Claims

1. A curable resin composition comprising the following components (A), (B), and (C): Component (A): 【Chemistry 1】 【Chemistry 2】 【Transformation 3】 A compound defined by formula (1) (In formula (1), -(OXO)- is defined in formula (2), R 1 , R 2 , R 7 , R 8 may be the same or different and each represents a halogen atom, an alkyl group having 6 or less carbon atoms, or a phenyl group. R 3 , R 4 , R 5 , R 6 may be the same or different and represent a hydrogen atom, a halogen atom, an alkyl group having 6 or less carbon atoms, or a phenyl group. A is a linear, branched, or cyclic hydrocarbon having 20 or fewer carbon atoms, or a direct bond. In formula (1), -(YO)- is one type of structure defined by formula (3), or two or more types of structures defined by formula (3) are randomly arranged. R 9 , R 10 may be the same or different and each represents a halogen atom, an alkyl group having 6 or less carbon atoms, or a phenyl group. R 11 , R 12 may be the same or different and each represents a hydrogen atom, a halogen atom, or an alkyl or phenyl group having 6 or less carbon atoms; a and b each represent an integer of 0 to 30, at least one of which is not 0; The polydispersity is 2.8 or less, A polyphenylene ether prepolymer having a number average molecular weight of 1,000 or more and 5,000 or less. Component (B): A difunctional phenol containing less than 20% of trifunctional or higher molecular species. Component (C): Curing accelerator.

2. In the formula (2), at least the R 1 , R 2 , R 7 , and R 8 is a methyl group, and the formula (3) has the following formula (4), formula (5), or a structure in which the formulas (4) and (5) are randomly arranged. The curable resin composition according to claim 1. 【Chemistry 4】 【Transformation 5】

3. The melting point of the bifunctional phenol is 180°C or less. The curable resin composition according to claim 1.

4. The curing accelerator is a phosphorus-based compound. The curable resin composition according to claim 1.

5. Component (E) contains a latent curing agent. The curable resin composition according to claim 1.

6. Further containing a difunctional epoxy resin as component (D), The curable resin composition according to any one of claims 1 to 5.

7. It is shown in the following equation (6): The number average molecular weight is 4000 or more. Step-growth polymer. 【Transformation 6】 【Transformation 7】 【Transformation 8】 (In formula (6), -(OXO)- is defined in formula (2), R 1 , R 2 , R 7 , R 8 may be the same or different and each represents a halogen atom, an alkyl group having 6 or less carbon atoms, or a phenyl group. R 3 , R 4 , R 5 , R 6 may be the same or different and represent a hydrogen atom, a halogen atom, an alkyl group having 6 or less carbon atoms, or a phenyl group. A is a linear, branched, or cyclic hydrocarbon having 20 or fewer carbon atoms, or a direct bond. In formula (6), -(YO)- is one type of structure represented by formula (3), or two or more types of structures defined by formula (3) are randomly arranged. R 9 , R 10 may be the same or different and each represents a halogen atom, an alkyl group having 6 or less carbon atoms, or a phenyl group. R 11 , R 12 may be the same or different and represent a hydrogen atom, a halogen atom, an alkyl group having 6 or less carbon atoms, or a phenyl group. a and b represent integers of 0 to 30, at least one of which is not 0. Z is a residue of a bifunctional phenol containing less than 20% of trifunctional or higher molecular species, and c is an integer of 0 or greater.

8. The method includes a reaction step of reacting the following components (A) and (B) to obtain a step-growth polymer: Method for producing a cured product. （A）： 【Chemistry 9】 【Chemistry 10】 【Chemistry 11】 A compound defined by formula (1) (In formula (1), -(OXO)- is represented by formula (2), R 1 , R 2 , R 7 , R 8 may be the same or different and each represents a halogen atom, an alkyl group having 6 or less carbon atoms, or a phenyl group. R 3 , R 4 , R 5 , R 6 may be the same or different and represent a hydrogen atom, a halogen atom, an alkyl group having 6 or less carbon atoms, or a phenyl group. A is a linear, branched, or cyclic hydrocarbon having 20 or fewer carbon atoms, or a direct bond. In formula (1), -(YO)- is one type of structure represented by formula (3), or two or more types of structures defined by formula (3) are randomly arranged. R 9 , R 10 may be the same or different and each represents a halogen atom, an alkyl group having 6 or less carbon atoms, or a phenyl group. R 11 , R 12 may be the same or different and each represents a hydrogen atom, a halogen atom, an alkyl group having 6 or less carbon atoms, or a phenyl group; a and b each represent an integer of 0 to 30, at least one of which is not 0; The polydispersity is 2.8 or less, A polyphenylene ether prepolymer having a number average molecular weight of 1,000 or more and 5,000 or less. (B): A difunctional phenol having a content of trifunctional or higher molecular species of less than 20%.

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