Thiol compounds

Abstract

The purpose of the present invention is to provide a novel thiol compound that is used in curing or the like of an epoxy resin. Specifically, provided are: a compound represented by a specific formula; and a curing agent for epoxy resins and an epoxy resin composition containing the compound.

Description

Technical Field

[0001] This invention relates to novel thiol compounds used in the curing of epoxy resins, etc. More specifically, these novel thiol compounds can be used as curing agents for epoxy resins. Background Technology

[0002] Compositions using compounds containing thiol groups (also known as hydrogen sulfide groups or mercapto groups, -SH groups) as curing agents for epoxy resins have been extensively studied due to their excellent low-temperature curing properties. In particular, various studies have been conducted on compounds having multiple thiol groups within the molecule (Patent Documents 1-3).

[0003] Existing technical documents Patent documents Patent Document 1: Japanese Patent Application Publication No. 2012-153794 Patent Document 2: Japanese Patent Application Publication No. 2016-164134 Patent Document 3: International Publication No. 2014 / 084292 Summary of the Invention

[0004] Typically, during the curing of epoxy resins, the use of difunctional thiol compounds with long molecular chains yields cured products with high elongation, low elasticity, and excellent impact resistance. However, when fingers or other objects come into contact with the cured surface, uncured material sometimes adheres to the fingers, affecting the surface condition of the cured product. Therefore, there is a need for thiol compounds that exhibit "tack-free" properties (i.e., do not adhere to fingers) and also possess high elongation and low elasticity.

[0005] The inventors conducted in-depth research to solve the aforementioned problems. They discovered that compounds with specific thiol groups are multifunctional thiol compounds exhibiting high elongation and low elasticity, and are effective as curing agents for resins that produce resins with good non-stick properties, thus completing the present invention. That is, the present invention may include the following methods.

[0006] [1] Compounds represented by general formula (I): (In formula (I), Ring P can be independently phenyl or naphthyl. When ring P is phenyl, there are 1 to 5 A atoms relative to each ring P; when ring P is naphthyl, there are 1 to 7 A atoms relative to each ring P. Each A is independently -R1-SH. R1 is independently a C1 to C6 alkylene group that is optionally substituted with one or more Y atoms. B is a substituent on ring P other than A, and is independently a hydrogen atom, a C1-C6 alkyl group optionally substituted with one or more Y atoms, or a C1-C6 alkoxy group optionally substituted with one or more Y atoms. When ring P is phenyl, A and B are independently bonded to the ortho, meta, or para positions relative to the position of ring P bonded to the main chain; when ring P is naphthyl, A and B are independently bonded to the ortho, meta, para, ana-, ε-, kata-, peri-, pros-, amphi-, or 2,7 positions relative to the position of ring P bonded to the main chain, and X is independently -CH2-, -O-, -N(-R2)-, or -S-. R2 can be a hydrogen atom, a C1-C6 alkyl group optionally substituted with one or more Y atoms, or a C1-C6 alkoxy group optionally substituted with one or more Y atoms. Y can be independently a hydrogen atom, a C1-C6 alkyl group, or a C1-C6 alkoxy group. Z can be a direct bond, -CH2-, -O-, or -S-, respectively. (n is an integer from 1 to 20). [2] According to the compound described in [1] above, wherein ring P is phenyl, and A exists in one of each ring P, and A is independently bonded to the ortho or para position relative to the position of ring P bonded to the main chain. [3] According to the compound described in [1] above, ring P is phenyl, A exists once in each ring P, R1 is a straight-chain C2-C3 alkylene chain, B is all hydrogen atoms, X is -O-, Y is hydrogen atom, Z is a direct bond or -O-, and n is an integer from 2 to 5. [4] According to the compound described in [1] above, ring P is phenyl, R1 is a straight-chain C2-C3 alkylene, A is present in one ring P, one B present in each ring P is methyl, methoxy or phenyl, all other B present in each ring P is hydrogen atom, X is -O-, Y is hydrogen atom, Z is direct bond or -O-, and n is an integer from 2 to 5. [5] The following compounds are shown: or [6] An epoxy resin composition comprising an epoxy resin and any one of the compounds described in [1] to [5] above. [7] An epoxy resin curing agent comprising any one of the compounds described in [1] to [5] above. [8] An epoxy resin cured product is formed by thermally curing an epoxy resin and any one of the compounds described in [1] to [5] above.

[0007] According to the present invention, a curing agent for epoxy resin can be provided, which exhibits high elongation and low elasticity, and produces a cured product with good non-stick properties. By using the thiol-containing compound of the present invention, the curing of the epoxy resin proceeds rapidly, resulting in an epoxy resin cured product with good non-stick properties. Attached Figure Description

[0008] Figure 1 The NMR data represent the thiol compound (1) prepared in Example 1. Figure 2 The NMR data represent the thiol compound (3) prepared in Example 3. Detailed Implementation

[0009] Here, the methods for implementing the invention are described in detail. The preferred or more preferred methods shown in the examples below, regardless of whether they are referred to as "preferred" or "more preferred," can be appropriately combined with each other. In addition, the description of numerical ranges is just an example, and it is also preferable to use ranges that appropriately combine the upper and lower limits of each range and the numerical values ​​of the embodiments. Furthermore, terms such as "containing" or "comprising" can also be read as "substantially composed of" or "composed of only".

[0010] [Thiols] One aspect of the present invention is a thiol compound represented by the following general formula (I).

[0011] In formula (I), ring P is independently phenyl or naphthyl, preferably phenyl. When ring P is phenyl, A is present in 1 to 5, preferably 1 to 3, more preferably 1 to 2, and even more preferably 1, relative to each ring P. When ring P is naphthyl, A is present in 1 to 7, preferably 1 to 5, more preferably 1 to 3, and even more preferably 1 to 2, relative to each ring P. Each A is independently -R1-SH, and R1 is independently a C1-C6 alkylene group optionally substituted with one or more Y atoms. R1 is preferably an unsubstituted C2-C5 alkylene group, more preferably an unsubstituted C2-C3 alkylene group. The alkylene group can be straight-chain or branched, saturated or unsaturated, and may not be substituted with Y. Y is defined as follows.

[0012] B is a substituent on ring P other than A. Therefore, the total number of substituents A and B on one ring P is 5 when ring P is phenyl and 7 when ring P is naphthyl. The number of substituents A and B on one ring P is, for example, 1 to 2 A and 0 to 2 B (excluding hydrogen atoms) relative to each ring P, more preferably 1 A and 0 to 1 B (excluding hydrogen atoms) relative to each ring P. B is independently a hydrogen atom, a C1-C6 alkyl group optionally substituted with one or more Y atoms, or a C1-C6 alkoxy group optionally substituted with one or more Y atoms. Y is defined as follows. Preferably, B is independently a hydrogen atom, an unsubstituted C1-C3 alkyl group, or an unsubstituted C1-C3 alkoxy group; more preferably, B is independently a hydrogen atom, a methyl group, or a methoxy group; and even more preferably, B is a hydrogen atom. Alternatively, one or two B atoms present in each ring P may be methyl, methoxy, or phenyl, and all other B atoms present in each ring P may be hydrogen atoms. When ring P is phenyl, 0 to 4, preferably 0 to 3, more preferably 1 to 2 B atoms relative to each ring P may be groups other than hydrogen atoms. When ring P is naphthyl, 0 to 6, preferably 0 to 5, more preferably 1 to 3, and even more preferably 1 to 2 B atoms relative to each ring P may be groups other than hydrogen atoms.

[0013] When ring P is phenyl, A and B can be independently bonded to the ortho, meta, or para positions relative to the position where ring P is bonded to the main chain. Preferably, A and B can be independently bonded to the ortho or para positions relative to the position where ring P is bonded to the main chain. As a more preferred embodiment, it is appropriate that there is one A on ring P, and there is no B or one B other than a hydrogen atom on ring P, in which case the A is bonded to the ortho or para position relative to the position where ring P is bonded to the main chain, and the B is bonded to the ortho position relative to the position where ring P is bonded to the main chain, in which case the B other than a hydrogen atom is present. On the other hand, when ring P is naphthyl, A and B can be independently bonded to the ortho, meta, para, ana-, ε-, kata-, peri-, pros-, amphi-, or 2,7 positions relative to the position of ring P bonded to the main chain. Preferably, A and B can be independently bonded to the ana-, ε-, kata-, peri-, amphi-, or 2,7 positions relative to the position of ring P bonded to the main chain. As a more preferred embodiment, it is appropriate that there is one A on ring P, and there is no B or one B other than a hydrogen atom on ring P, with the A bonded to the amphi- or 2,7 positions relative to the position of ring P bonded to the main chain, and that B is bonded to the amphi- or 2,7 positions relative to the position of ring P bonded to the main chain. X is independently -CH2-, -O-, -N(-R2)-, or -S-. Here, R2 is independently a hydrogen atom, a C1-C6 alkyl group optionally substituted with one or more Y atoms, or a C1-C6 alkoxy group optionally substituted with one or more Y atoms. R2 is preferably an unsubstituted C2-C5 alkylene group, more preferably an unsubstituted C2-C3 alkylene group. The alkylene group can be straight-chain or branched, saturated or unsaturated, and may not be substituted with Y. Y is defined as follows. X is preferably -CH2- or -O-, more preferably -O-. Y is independently a hydrogen atom, a C1-C6 alkyl group, or a C1-C6 alkoxy group. Y is preferably a hydrogen atom, a methyl group, or an ethyl group, and more preferably a hydrogen atom. Z can be a direct bond, -CH2-, -C2H4-, -C3H6-, -C4H8-, -O-, or -S-, respectively. Z is preferably a direct bond or -O-, and more preferably a direct bond. n is, for example, an integer from 1 to 20, preferably an integer from 1 to 10, and more preferably an integer from 2 to 5 or from 1 to 3.

[0014] As a more specific example of the thiol compounds of the present invention, the following thiol compounds (1) to (5) and (5)' are given. Thiol compounds (1)

[0015] Thiol compounds (2)

[0016] Thiol compounds (3)

[0017] Thiol compounds (4)

[0018] Thiol compounds (5) Thiol compounds (5)

[0019] [Preparation methods of thiols] The above-mentioned thiols can be manufactured by known methods, for example, as follows. Hereinafter, the above-mentioned thiols (1) will be used as an example for explanation. First, 2-allylphenol and 1,4-dibromobutane are used as starting materials. Tetra-n-butylammonium bromide is added as a phase transfer catalyst, and methyl isobutyl ketone (MIBK) is added as a reaction solvent. The mixture is dissolved at a temperature of 50–200°C, preferably 60–150°C, more preferably 100°C ± 10–20°C, for example, maintaining the temperature for 1 minute to 12 hours, preferably 10 minutes to 5 hours, more preferably 30 minutes ± 10–20 minutes. An alkali such as KOH aqueous solution is added to the resulting solution, and then the water is removed by distillation by returning only MIBK to the system at a temperature range of 100–150°C, preferably 110–120°C, while the reaction proceeds for 1–24 hours, preferably 2–10 hours, more preferably 6 hours ± 1 hour. Then, the temperature is lowered to about 60°C, distilled water is added and the mixture is allowed to stand. The lower brine layer, a byproduct, is discarded. Distilled water and an alkali (such as sodium dihydrogen phosphate, for neutralization) are then added and the mixture is allowed to stand and separate. The lower brine layer, a byproduct, is discarded again. An equal volume of distilled water is then added for 1 to 5 washes, preferably 2 to 3, to purify the solution. For example, azeotropic dehydration is performed by heating to 50 to 200°C, preferably 60 to 150°C, more preferably 120°C ± 10 to 20°C. The resulting solution is precisely filtered to remove impurities. MIBK and unreacted 2-allylphenol are subjected to vacuum distillation to obtain a liquid resin. The obtained liquid resin, thioacetic acid, toluene, and azobisisobutyronitrile (AIBN) are mixed and reacted, for example, at 50 to 200°C, preferably 60 to 150°C, more preferably 80°C ± 10 to 20°C, for example, for 30 minutes to 24 hours, preferably 1 to 10 hours, more preferably 4 hours ± 1 to 2 hours. After removing toluene from the obtained reactants, crystallization is performed with methanol, and the crystals are dried and recovered. The recovered dried crystals are mixed with an alkali such as NaOH and reacted, for example, at 50–200°C, preferably 60–150°C, more preferably 80°C ± 10–20°C, for example, for 30 minutes to 12 hours, preferably 1–5 hours, more preferably 2 hours ± 1 hour. After neutralization with an acid such as hydrochloric acid, the organic layer is separated and washed with water. Toluene is removed from the washed organic layer to obtain the target thiol compound.

[0020] [Uses of thiols] The aforementioned thiols are polyfunctional thiols with relatively long molecular chains and two or more thiol groups. When used as curing agents in the curing of epoxy resins, they can produce cured products with excellent impact resistance, high elongation, and low elasticity. Furthermore, these thiols exhibit excellent low-temperature curing properties and superior hydrolysis resistance compared to other thiols with ester groups, making them useful as curing agents for epoxy resins. Additionally, these thiols can also be used as crosslinking agents or curing aids for compounds containing carbon-carbon double bonds (alkene compounds). The reaction of thiols with carbon-carbon double bonds, known as the thiol-ene reaction, is known. These thiols can be used in the reaction (thiol-ene reaction) of resins containing carbon-carbon double bonds, such as (meth)acrylate compounds, allyl compounds, vinyl compounds, unsaturated polyesters, and polybutadiene, with the aforementioned thiols. By using this thiol compound as a crosslinking agent or curing aid, it is less susceptible to oxygen inhibition during the reaction and exhibits excellent reactivity with compounds containing carbon-carbon double bonds, thus enabling rapid crosslinking of compounds with carbon-carbon double bonds. It should be noted that, in various applications, only one thiol compound of the present invention may be used, or multiple compounds may be used in combination.

[0021] [Epoxy Resin Composition] One aspect of the present invention is an epoxy resin composition containing an epoxy resin and the aforementioned thiol compound. Examples of epoxy resins include epoxy resin compounds having an average of two or more epoxy groups per molecule. Examples of epoxy resins include: polyglycidyl ethers obtained by reacting polyphenols such as bisphenol A, bisphenol F, bisphenol AD, catechol, and resorcinol, glycerol, or polyols such as polyethylene glycol with epichlorohydrin; polyglycidyl ether esters obtained by reacting hydroxy acids such as p-hydroxybenzoic acid and β-hydroxynaphthoic acid with epichlorohydrin; polyglycidyl esters obtained by reacting polycarboxylic acids such as phthalic acid and terephthalic acid with epichlorohydrin; and epoxy phenolic varnish resins, epoxy cresol varnish resins, epoxy polyolefins, cyclic aliphatic epoxy resins, and other polyurethane-modified epoxy resins; etc. As preferred epoxy resins, from the viewpoint of maintaining high heat resistance and low moisture permeability, bisphenol A type epoxy resin, bisphenol F type epoxy resin, phenolic varnish type epoxy resin, biphenyl aryl alkyl type epoxy resin, phenolic aryl alkyl type epoxy resin, aromatic glycidylamine type epoxy resin, and epoxy resin having a dicyclopentadiene structure are preferred, with bisphenol A type epoxy resin and bisphenol F type epoxy resin being more preferred, and bisphenol A type epoxy resin being even more preferred.

[0022] Epoxy resin can be in a liquid or solid state. Furthermore, a mixture of liquid and solid epoxy resins can be used as the epoxy resin used herein. Here, "liquid" and "solid" refer to the state of the epoxy resin at room temperature (25°C). Specific examples of liquid epoxy resins include: liquid bisphenol A type epoxy resin (manufactured by Mitsubishi Chemical Corporation, "jER (registered trademark) epoxy resin 828", "jER (registered trademark) epoxy resin 827"), liquid bisphenol F type epoxy resin (manufactured by Mitsubishi Chemical Corporation, "jER (registered trademark) epoxy resin 807"), naphthalene type difunctional epoxy resin (manufactured by DIC Corporation, "HP4032", "HP4032D"), liquid bisphenol AF type epoxy resin (manufactured by Nippon Steel Epoxy Manufacturing Co., Ltd., "ZX1059"), and hydrogenated epoxy resin (manufactured by Mitsubishi Chemical Corporation, "jER (registered trademark) epoxy resin YX8000"). Among them, the preferred materials are "jER (registered trademark) epoxy resin 828", "jER (registered trademark) epoxy resin 827" and "jER (registered trademark) epoxy resin 807" manufactured by Mitsubishi Chemical Corporation, which have high heat resistance and low viscosity, and "jER (registered trademark) epoxy resin 828" is more preferred. In addition, specific examples of solid epoxy resins include: naphthalene-type tetrafunctional epoxy resin ("HP4700" manufactured by DIC Corporation), dicyclopentadiene-type polyfunctional epoxy resin ("HP7200" manufactured by DIC Corporation), naphthol-type epoxy resin ("ESN-475V" manufactured by Nippon Steel Epoxy Manufacturing Co., Ltd. (Toto Chemical Co., Ltd.), butadiene-structured epoxy resin ("PB-3600" manufactured by Daicel Co., Ltd.), biphenyl-structured epoxy resin ("NC3000H" and "NC3000L" manufactured by Nippon Chemical Co., Ltd., and "YX4000" manufactured by Mitsubishi Chemical Co., Ltd.), etc.

[0023] From the viewpoints of coatability, processability, and adhesion, it is preferable that at least 10% by mass of the total epoxy resin used is liquid epoxy resin, more preferably 30% by mass or more, and even more preferably 50% by mass or more. In the epoxy resin composition of the present invention, the content of the thiol compound of the present invention relative to 100 parts by mass of the epoxy resin also depends on the number of thiol groups. However, for example, when the thiol compound of the present invention is a difunctional thiol compound having two thiol groups (thiol equivalent = 2), it is preferably 5 parts by mass or more, more preferably 10 parts by mass or more, further preferably 20 parts by mass or more, further more preferably 30 parts by mass or more, particularly preferably 40 parts by mass or more, and especially preferably 50 parts by mass or more. Furthermore, the content of the thiol compound of the present invention relative to 100 parts by mass of the epoxy resin of the present invention is preferably 300 parts by mass or less, more preferably 250 parts by mass or less, further preferably 225 parts by mass or less, further more preferably 200 parts by mass or less, especially preferably 180 parts by mass or less, and particularly preferably 170 parts by mass or less. The preferred content of the thiol compound of the present invention can be within any range selected from the upper limit, lower limit, and values ​​of the examples. When the number of thiol groups contained in the thiol compound of the present invention is greater than 2, it can be a content proportional to the above-mentioned content or thiol equivalent. That is, for example, when the number of thiol groups is 4 (thiol equivalent = 4), the above "preferably 5 parts by mass or more" can be read as "preferably 2.5 parts by mass or more", and "preferably 300 parts by mass or less" can be read as "preferably 150 parts by mass or less".

[0024] Other components that can be added to the epoxy resin composition of the present invention include curing accelerators, solvents, preservation stabilizers, other curing agents, thixotropic agents, fillers, diluents, dispersants, flexibility agents, coupling agents, antioxidants, etc. Examples of latent curing accelerators include latent curing accelerators. A latent curing accelerator is a solid compound that is insoluble in epoxy resin at room temperature (25°C), but can be soluble by heating and function as a curing accelerator for epoxy resin. Examples of latent curing accelerators that are solid at room temperature (25°C) include imidazole compounds and amine adducts, but are not limited to these. Among these, amine adducts are preferred. Examples of amine adducts include reaction products of amine compounds and epoxy compounds (amine-epoxy adduct latent curing accelerators) and reaction products of amine compounds and isocyanate compounds (amine-isocyanate latent curing accelerators).

[0025] Examples of imidazole compounds that are solid at room temperature (25°C) include: 2-heptadecylimidazolium, 2-phenyl-4,5-dihydroxymethylimidazolium, 2-undecylimidazolium, 2-phenyl-4-methyl-5-hydroxymethylimidazolium, 2-phenyl-4-benzyl-5-hydroxymethylimidazolium, 2,4-diamino-6-(2-methylimidazolium-(1))-ethyl-triazine, 2,4-diamino-6-(2'-methylimidazolium-(1)')-ethyl-triazine / isocyanuric acid adduct, 2-methylimidazolium, 2-phenylimidazolium, 2-phenyl-4-methylimidazolium, 1-cyanoethyl-2-phenylimidazolium, 1-cyanoethyl-2-methylimidazolium-trimethoxycyanate, 1-cyanoethyl-2-phenylimidazolium-trimethoxycyanate, N-(2-methylimidazolium-1-ethyl)-urea, etc.

[0026] Examples of epoxy compounds used as raw materials for manufacturing latent curing accelerators of the aforementioned amine-epoxy adduct systems include: polyglycidyl ethers obtained by reacting polyphenols such as bisphenol A, bisphenol F, catechol, and resorcinol, or polyols such as glycerol and polyethylene glycol, with epichlorohydrin; glycidyl ether esters obtained by reacting hydroxy acids such as p-hydroxybenzoic acid and β-hydroxynaphthoic acid with epichlorohydrin; polyglycidyl esters obtained by reacting polycarboxylic acids such as phthalic acid and terephthalic acid with epichlorohydrin; glycidyl amine compounds obtained by reacting 4,4'-diaminodiphenylmethane or m-aminophenol with epichlorohydrin; and polyfunctional epoxy compounds such as epoxidized phenolic varnish resin, epoxidized cresol varnish resin, and epoxidized polyolefin, or monofunctional epoxy compounds such as butyl glycidyl ether, phenyl glycidyl ether, and glycidyl methacrylate; etc.

[0027] The amine compound used as a raw material for manufacturing the aforementioned amine adduct system latent curing accelerator is any amine compound that has one or more active hydrogen atoms in its molecule capable of undergoing addition reactions with an epoxy group or an isocyanate group (also known as an isocyanate group), and has one or more amino groups (at least one of primary, secondary, and tertiary amino groups) in its molecule. Examples of such amine compounds include, for example, aliphatic amines such as diethylenetriamine, triethylenetetramine, propylamine, 2-hydroxyethylaminopropylamine, cyclohexylamine, and 4,4'-diamino-dicyclohexylmethane; aromatic amine compounds such as 4,4'-diaminodiphenylmethane and 2-methylaniline; and nitrogen-containing heterocyclic compounds such as 2-ethyl-4-methylimidazolium, 2-ethyl-4-methylimidazoline, 2,4-dimethylimidazoline, piperidine, and piperazine; etc.

[0028] Furthermore, if compounds containing tertiary amines within the molecule are used in the aforementioned raw materials, latent curing accelerators with excellent curing-promoting abilities can be manufactured. Examples of compounds having a tertiary amino group within the molecule include: dimethylaminopropylamine, diethylaminopropylamine, dipropylaminopropylamine, dibutylaminopropylamine, dimethylaminoethylamine, diethylaminoethylamine, N-methylpiperazine, 2-methylimidazole, 2-ethylimidazole, 2-ethyl-4-methylimidazole, and 2-phenylimidazole, which are amines having a tertiary amino group within the molecule; 2-dimethylaminoethanol, 1-methyl-2-dimethylaminoethanol, 1-phenoxymethyl-2-dimethylaminoethanol, 2-diethylaminoethanol, 1-butoxymethyl-2-dimethylaminoethanol, 1-(2-hydroxy-3-phenoxypropyl)-2-methylimidazole, 1-(2-hydroxy-3-phenoxypropyl)-2-ethyl-4-methylimidazole, 1-(2-hydroxy-3-butoxypropyl)-2-methylimidazole, etc. Alcohols, phenols, thiols, carboxylic acids, and acylhydrazides containing a tertiary amino group in the molecule, such as 1-(2-hydroxy-3-butoxypropyl)-2-ethyl-4-methylimidazolium, 1-(2-hydroxy-3-phenoxypropyl)-2-phenylimidazoline, 1-(2-hydroxy-3-butoxypropyl)-2-methylimidazoline, 2-(dimethylaminomethyl)phenol, 2,4,6-tris(dimethylaminomethyl)phenol, N-β-hydroxyethylmorpholine, 2-dimethylaminoethanethiol, 2-mercaptopyridine, 2-benzimidazole, 2-mercaptopyridine, 2-mercaptopyridine, 2-mercaptopyridine, 2-mercaptopyridine, 2-mercaptopyridine, 2-mercaptopyridine, 2-mercaptopyridine, 2-mercaptopyridine, 2-dimethylaminobenzoic acid, 2-dimethylglycine, nicotinic acid, isonicotinic acid, pyridinecarboxylic acid, 2-dimethylglycylhydrazide, 2-dimethylpropionylhydrazide, nicotinylhydrazide, and isonicotinylhydrazide; etc.

[0029] When manufacturing an amine adduct-based latent curing accelerator by reacting the aforementioned epoxy compound with an amine compound through an addition reaction, an active hydrogen compound having two or more active hydrogen atoms in its molecule may be further added. Examples of such active hydrogen compounds include: bisphenol A, bisphenol F, bisphenol S, hydroquinone, catechol, resorcinol, pyrogallol, and polyphenols such as linear phenolic resins; polyols such as trimethylolpropane; polycarboxylic acids such as adipic acid and phthalic acid; 1,2-dimercaptoethane, 2-mercaptoethanol, 1-mercapto-3-phenoxy-2-propanol, mercaptoacetic acid, anthranilic acid, lactic acid, etc.

[0030] Examples of isocyanate compounds used as raw materials for manufacturing the aforementioned amine adduct-based latent curing accelerators include: monofunctional isocyanate compounds such as butyl isocyanate, isopropyl isocyanate, phenyl isocyanate, and benzyl isocyanate; polyfunctional isocyanate compounds such as hexamethylene diisocyanate, toluene diisocyanate (e.g., 2,4-toluene diisocyanate, 2,6-toluene diisocyanate), 1,5-naphthalene diisocyanate, diphenylmethane-4,4'-diisocyanate, isophorone diisocyanate, phenylenediamine diisocyanate, terephthalene diisocyanate, 1,3,6-hexamethylene triisocyanate, and bicycloheptane triisocyanate; and compounds containing terminal isocyanate groups obtained by reacting these polyfunctional isocyanate compounds with active hydrogen compounds; etc. Examples of such compounds containing a terminal isocyanate group include: addition compounds with a terminal isocyanate group obtained by reacting toluene diisocyanate with trimethylolpropane, and addition compounds with a terminal isocyanate group obtained by reacting toluene diisocyanate with pentaerythritol.

[0031] Curing accelerators can be readily obtained, for example, by appropriately mixing the above-mentioned raw materials, reacting them at a temperature from room temperature (25°C) to 200°C, cooling and curing them, and then pulverizing them; or by reacting the above-mentioned raw materials in solvents such as methyl ethyl ketone, dioxane, and tetrahydrofuran, removing the solvent, and then pulverizing the solid components.

[0032] Commercially available curing accelerators can be used. Examples of amine-epoxy adduct-based latent curing accelerators include: Ajicure PN-23 (Ajinomoto Fine-Techno Co., Ltd.), Ajicure PN-H (Ajinomoto Fine-Techno Co., Ltd.), Ajicure PN-40 (Ajinomoto Fine-Techno Co., Ltd.), Hardener X-3661S (ACR Corporation), Hardener X-3670S (ACR Corporation), Novacure HX-3742 (Asahi Kasei Corporation), and Novacure HX-3721 (Asahi Kasei Corporation). Examples of amine-isocyanate-based latent curing accelerators include: Fuji Chemical FXE-1000 (Fuji Chemical Co., Ltd.). FXR-1030” (Fuji Chemical Co., Ltd.), etc.

[0033] In the epoxy resin composition of the present invention, the content of the curing accelerator relative to 100 parts by weight of the epoxy resin is preferably 0.1 parts by weight or more, more preferably 0.5 parts by weight or more, even more preferably 1 part by weight or more, even more preferably 1.5 parts by weight or more, and particularly preferably 2 parts by weight or more. Furthermore, the content of the curing accelerator relative to 100 parts by weight of the epoxy resin of the present invention is preferably 40 parts by weight or less, more preferably 35 parts by weight or less, even more preferably 30 parts by weight or less, even more preferably 25 parts by weight or less, and particularly preferably 20 parts by weight or less. The preferred content of the curing accelerator can be selected from any value selected from the upper limit, lower limit, and values ​​of the examples.

[0034] Examples of solvents commonly used in this field include water or organic solvents. Examples of organic solvents include toluene, tetrahydrofuran, methyl ethyl ketone, methyl isobutyl ketone, and dioxane. The solvent may be present, but it is preferable that it is ultimately removed from the epoxy resin composition.

[0035] Storage stabilizers are used to impart excellent storage stability to the epoxy resin composition. As a storage stabilizer, it is preferable, for example, to further contain one or more selected from borate ester compounds, titanate compounds, aluminate compounds, zirconate compounds, isocyanate compounds, carboxylic acids, acid anhydrides, and mercapto organic acids. Examples of the aforementioned borate esters include, for instance, trimethyl borate, triethyl borate, tripropyl borate, triisopropyl borate, tributyl borate, tripentyl borate, triallyl borate, trihexyl borate, tricyclohexyl borate, trioctyl borate, trinonyl borate, tridecyl borate, tri(dodecyl) borate, tri(hexadecyl) borate, tri(octadecyl) borate, tri(2-ethylhexyloxy)borane, bis(1,4,7,10-tetraoxaundecyl)(1,4,7,10,13-pentaoxatetradecyl)(1,4,7-trioxaundecyl)borane, tribenzyl borate, triphenyl borate, tri-o-toluene borate, tri-m-toluene borate, and triethanolamine borate.

[0036] Examples of the aforementioned titanate compounds include tetraethyl titanate, tetrapropyl titanate, tetraisopropyl titanate, tetrabutyl titanate, and tetraoctyl titanate. Examples of the aforementioned aluminate compounds include triethyl aluminate, tripropyl aluminate, triisopropyl aluminate, tributyl aluminate, and trioctyl aluminate. Examples of the aforementioned zirconate compounds include tetraethyl zirconate, tetrapropyl zirconate, tetraisopropyl zirconate, and tetrabutyl zirconate. Examples of the aforementioned isocyanate compounds include, for example, butyl isocyanate, isopropyl isocyanate, 2-chloroethyl isocyanate, phenyl isocyanate, p-chlorophenyl isocyanate, benzyl isocyanate, hexamethylene diisocyanate, 2-ethylphenyl isocyanate, 2,6-dimethylphenyl isocyanate, toluene diisocyanate (e.g., 2,4-toluene diisocyanate, 2,6-toluene diisocyanate), 1,5-naphthalene diisocyanate, diphenylmethane-4,4'-diisocyanate, benzyltoluidine diisocyanate, isophorone diisocyanate, phenyldimethyl diisocyanate, terephthalic diisocyanate, and bicycloheptane triisocyanate.

[0037] Examples of the aforementioned carboxylic acids include: saturated aliphatic monocarboxylic acids such as formic acid, acetic acid, propionic acid, butyric acid, hexanoic acid, and octanoic acid; unsaturated aliphatic monocarboxylic acids such as acrylic acid, methacrylic acid, and butenoic acid; halogenated fatty acids such as monochloroacetic acid and dichloroacetic acid; monohydroxy acids such as glycolic acid, lactic acid, and gluconic acid (racemic tartaric acid); aliphatic aldehyde acids and keto acids such as glyoxylic acid; aliphatic polycarboxylic acids such as oxalic acid, malonic acid, succinic acid, and maleic acid; aromatic monocarboxylic acids such as benzoic acid, halobenzoic acid, methylbenzoic acid, phenylacetic acid, cinnamic acid, and mandelic acid; and aromatic polycarboxylic acids such as phthalic acid and pyromellitic acid. Examples of the aforementioned acid anhydrides include: succinic anhydride, dodecenylsuccinic anhydride, maleic anhydride, adducts of methylcyclopentadiene and maleic anhydride, hexahydrophthalic anhydride, and methyltetrahydrophthalic anhydride, etc., which are aliphatic polyacid anhydrides; and phthalic anhydride, trimellitic anhydride, and pyromellitic anhydride, etc., which are aromatic polyacid anhydrides. Examples of the aforementioned thiol organic acids include, for example, thiol aliphatic monocarboxylic acids such as thioacetic acid, thiol propionic acid (e.g., 3-mercaptopropionic acid), and thiol butyric acid (e.g., 3-mercaptobutyric acid, 4-mercaptobutyric acid); esters containing thiol and carboxyl groups obtained by esterification of hydroxy acids with thiol organic acids; thiol aliphatic dicarboxylic acids such as mercaptosuccinic acid and dimercaptosuccinic acid (e.g., 2,3-dimercaptosuccinic acid); thiol aromatic monocarboxylic acids such as mercaptobenzoic acid (e.g., 4-mercaptobenzoic acid); etc.

[0038] As a preservation stabilizer, from the viewpoint of high versatility and safety and improved preservation stability, borate ester compounds are preferred, more preferably triethyl borate, tripropyl borate, triisopropyl borate and tributyl borate, and even more preferably triethyl borate. The content of the preservation stabilizer in the epoxy resin composition of the present invention is not particularly limited as long as it can improve the preservation stability of the composition. The preservation stabilizer is preferably 0.001 to 50 parts by weight relative to 100 parts by weight of epoxy resin, more preferably 0.05 to 30 parts by weight, and even more preferably 0.1 to 10 parts by weight.

[0039] Other curing agents can be any compounds other than the thiol compounds of the present invention, and can be used as curing agents for epoxy resins. Examples of other curing agents include, for example, full esters of polyols and thiol organic acids. Here, a full ester refers to an ester of a polyol and a carboxylic acid, wherein all the hydroxyl groups of the polyol form ester bonds. Examples of the aforementioned polyols include, for example, ethylene glycol, trimethylolpropane, pentaerythritol, and dipentaerythritol. Examples of the aforementioned thiol organic acids include, for example, thiol aliphatic monocarboxylic acids such as mercaptoacetic acid, mercaptopropionic acid (e.g., 3-mercaptopropionic acid), and mercaptobutyric acid (e.g., 3-mercaptobutyric acid, 4-mercaptobutyric acid); esters containing thiol and carboxyl groups obtained by esterification of hydroxy acids and thiol organic acids; thiol aliphatic dicarboxylic acids such as mercaptosuccinic acid and dimercaptosuccinic acid (e.g., 2,3-dimercaptosuccinic acid); thiol aromatic monocarboxylic acids such as mercaptobenzoic acid (e.g., 4-mercaptobenzoic acid); etc. The number of carbon atoms in the above-mentioned thiol aliphatic monocarboxylic acids is preferably 2 to 8, more preferably 2 to 6, even more preferably 2 to 4, and particularly preferably 3. Among the above-mentioned thiol organic acids, thiol aliphatic monocarboxylic acids with 2 to 8 carbon atoms are preferred, more preferably thioglycolic acid, 3-mercaptopropionic acid, 3-mercaptobutyric acid, and 4-mercaptobutyric acid, and even more preferably 3-mercaptopropionic acid.

[0040] Specific examples of polyols and thiol organic acids as esters include: ethylene glycol bis(thiol acetate), ethylene glycol bis(3-thiol propionate), ethylene glycol bis(3-thiol butyrate), ethylene glycol bis(4-thiol butyrate), trimethylolpropane tri(thiol acetate), trimethylolpropane tri(3-thiol propionate), trimethylolpropane tri(3-thiol butyrate), trimethylolpropane tri(4-thiol butyrate), pentaerythritol tetra(thiol acetate), pentaerythritol tetra(3-thiol propionate), pentaerythritol tetra(3-thiol butyrate), pentaerythritol tetra(4-thiol butyrate), dipentaerythritol hexa(thiol acetate), dipentaerythritol hexa(3-thiol propionate), dipentaerythritol hexa(3-thiol butyrate), and dipentaerythritol hexa(4-thiol butyrate), etc. Furthermore, from the viewpoint of preservation stability, the above-mentioned full ester is preferably an ester with very low content of basic impurities, and more preferably an ester that does not require the use of basic substances in manufacturing.

[0041] In addition, as other curing agents, such as alkyl polythiols like 1,4-butanedithiol, 1,6-hexanedithiol, and 1,10-decanedithiol; polyethers containing terminal thiol groups; polysulfides containing terminal thiol groups; polythiols obtained by reacting epoxides with hydrogen sulfide; and polythiols with terminal thiol groups obtained by reacting polythiols with epoxides, polythiols obtained by using alkaline substances as reaction catalysts in their manufacturing process can also be used. Polythiols obtained using alkaline substances are preferably subjected to dealkalization treatment to reduce the alkali metal ion concentration to below 50 ppm by weight before use. Examples of dealkalization treatments for polythiols obtained using alkaline substances include: dissolving the polythiols in organic solvents such as acetone and methanol, neutralizing with acids such as dilute hydrochloric acid and dilute sulfuric acid, and then desalting by extraction or washing; adsorption using ion exchange resins; purification by distillation; and so on.

[0042] In addition, other curing agents may be used, for example, tris[(3-mercaptopropionyloxy)-ethyl]-isocyanurate, 1,3,5-tris(3-mercaptobutoxyethyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione, etc. Preferably, it is one or more of a total ester of ethylene glycol, trimethylolpropane, pentaerythritol, or dipentaerythritol with a thiol aliphatic monocarboxylic acid having 2 to 8 carbon atoms; more preferably, it is selected from ethylene glycol bis(mercaptoacetate), ethylene glycol bis(3-mercaptopropionate), ethylene glycol bis(3-mercaptobutyrate), ethylene glycol bis(4-mercaptobutyrate), trimethylolpropane tri(mercaptoacetate), trimethylolpropane tri(3-mercaptopropionate), trimethylolpropane tri(3-mercaptobutyrate), trimethylolpropane tri(4-mercaptobutyrate), pentaerythritol tetra(mercaptoacetate), pentaerythritol tetra(3-mercaptopropionate). At least one of pentaerythritol tetra(3-mercaptobutyrate), pentaerythritol tetra(4-mercaptobutyrate), dipentaerythritol hexa(mercaptoacetate), dipentaerythritol hexa(3-mercaptopropionate), dipentaerythritol hexa(3-mercaptobutyrate), and dipentaerythritol hexa(4-mercaptobutyrate); more preferably at least one of trimethylolpropane tri(mercaptoacetate), trimethylolpropane tri(3-mercaptopropionate), trimethylolpropane tri(3-mercaptobutyrate), and trimethylolpropane tri(4-mercaptobutyrate); particularly preferably trimethylolpropane tri(3-mercaptopropionate).

[0043] When other curing agents are used in the epoxy resin composition, the amount preferably is within the range that does not affect the curing of the thiol compound of the present invention. Relative to 100 parts by weight of epoxy resin, the other curing agent is preferably 0.001 to 50 parts by weight, more preferably 0.05 to 30 parts by weight, and even more preferably 0.1 to 10 parts by weight. The ratio of the thiol compound of the present invention to other curing agents, i.e., [mass of the thiol compound of the present invention] / [total mass of the thiol compound of the present invention and other curing agents], is preferably, for example, 0.001 to 0.8. The lower limit of this ratio is more preferably 0.01, further preferably 0.03, and particularly preferably 0.1. The upper limit of this ratio is not particularly limited, but is more preferably 0.6, further preferably 0.4, and particularly preferably 0.2.

[0044] The ratio of the total equivalent amount of thiol groups contained in the thiol compounds and / or other curing agents of the present invention to the equivalent amount of epoxy groups contained in the epoxy resin, i.e., [the total number of thiol groups contained in the thiol compounds and / or other curing agents of the present invention] / [the number of epoxy groups contained in the epoxy resin] is preferably 0.2 to 2.0, more preferably 0.6 to 1.2.

[0045] Examples of thixotropic agents include precipitated silica, calcined silica, and fumed silica (fumed silica), with fumed silica (fumed silica) being preferred. The specific surface area of ​​the thixotropic agent based on the BET method (hereinafter referred to as BET specific surface area) is preferably 50 m². 2 / g or more, more preferably 50-600m 2 / g, further preferably 100-400m 2 / g. When using a thixotropic agent, the content of the thixotropic agent in the epoxy resin composition is preferably 5 to 200 parts by weight, more preferably 10 to 100 parts by weight, relative to 100 parts by weight of epoxy resin.

[0046] The epoxy resin composition can be a one-component epoxy resin composition or a two-component epoxy resin composition. In the case of a two-component epoxy resin composition, for example, an epoxy resin can be used as agent A, and a thiol compound and other additives can be used as agent B to prepare a kit having agent A and agent B. In addition, the epoxy resin composition may contain one or more of the aforementioned thiol compounds and other components.

[0047] [Epoxy resin cured product] One embodiment of the present invention is an epoxy resin cured product obtained by curing the epoxy resin in the presence of the aforementioned thiol compound. As a curing method, a thermosetting method commonly used in epoxy resins can be used. For example, an epoxy resin composition can be prepared by mixing epoxy resin, thiol compound, and other arbitrary additives, and the epoxy resin composition can be maintained at a temperature of, for example, 50–250°C, preferably 80–200°C, more preferably 120°C ± 10–20°C for, for example, 10 minutes to 3 hours, preferably 30 minutes to 2 hours, more preferably 1 hour ± 10–20 minutes to obtain a cured product. When preparing the epoxy resin composition, it is preferable to use a degassing machine or the like to degas each component.

[0048] The epoxy resin cured products of the present invention can be used for applications such as adhesives, casting agents, sealants, fiber-reinforcing resins, coating agents, and paints. Example

[0049] The present invention will now be described in more detail based on embodiments and comparative examples, but the present invention is not limited to the following embodiments. [High Performance Liquid Chromatography and Mass Spectrometry Determination Methods (LC / MS Determination)] (Determination conditions for high performance liquid chromatography and mass spectrometry) The sample was diluted with tetrahydrofuran (THF) to 1 mg / mL and determined by high performance liquid chromatography and mass spectrometry (LC / MS) under the following conditions. High Performance Liquid Chromatography (HPLC): ACQUITY UPLC (manufactured by Nihon Waters) Mass spectrometry (MS): SQ Detector2 (manufactured by Nihon Waters) Chromatographic column: ACQUITY UPLC BEH C8 1.7µm, 2.1mm × 50mm (Nihon Waters) Mobile phase A: 2 mmol ammonium acetate aqueous solution Mobile phase B: 2-propanol / acetonitrile (50:50) Mobile phase mixing time and mixing ratio (A%): 0–0.5 minutes (95%) → 1 minute–8.5 minutes (75%) → 9–11 minutes (5%) → 11.1 minutes (95%) → 13 minutes (95%) Flow rate: 0.30 mL / min Analysis time: 13 minutes Column temperature: 40℃, ion mode: ESI (electrospray ionization) positive ion Ion polarity: Positive ion detection mode Desolventizing gas flow rate: 700 L / hr, 250 °C Conical gas: 70L / hr Ion source heater: 150℃

[0050] [NMR Measurement Methods] NMR data of the thiol compounds prepared in the examples were collected using a JEOL LA-500 (manufactured by JEOL Corporation).

[0051] [Example 1] Synthesis of thiol compound (1) (1) Synthesis of aliphatic skeleton diallyl compound (1) In a 2-liter four-necked round flask equipped with a stirrer, thermometer, condenser, dropping funnel, and Dean-Starktrap, 140.9 g (1.05 mol) of 2-allylphenol (reagent), 108.0 g (0.5 mol) of 1,4-dibromobutane (reagent), 3.1 g of tetrabutylammonium bromide as a phase transfer catalyst, and 300 g of methyl isobutyl ketone (MIBK) as a reaction solvent were added. The mixture was heated to 100°C and maintained for 30 minutes to allow complete dissolution. 175 g (1.5 mol) of 48% KOH aqueous solution was added dropwise to the resulting solution over 1 hour. The water and MIBK, azeotropically distilled by the added KOH aqueous solution, were separated into water and MIBK respectively within the Dean-Starktrap, with only MIBK being returned to the reaction system while the reaction proceeded. The reaction was continued for 6 hours while only returning MIBK to the system and removing water by distillation at 118°C. Then, the temperature was lowered to 60°C, 100g of distilled water was added, and the mixture was allowed to stand, discarding the lower brine layer. Next, 100g of distilled water and an appropriate amount of sodium dihydrogen phosphate for neutralization were added, and the mixture was allowed to stand and separate, discarding the lower brine layer. An equal volume of distilled water was then added, and the mixture was washed twice for purification. The solution was then heated to 118°C for azeotropic dehydration. After removing impurities by precise filtration using filter paper No. 5C (Made by Kiriyama Corporation) and a Kiriyama funnel (Made by Kiriyama Corporation), MIBK and unreacted 2-allylphenol were distilled under reduced pressure at a maximum temperature of 180°C to obtain 145g of liquid resin. The obtained liquid resin was measured using the LC / MS method described above, and spectral peaks were detected at m / z = 323 for the proton adduct and m / z = 340 for the ammonium adduct. Based on this analytical data, the obtained liquid resin was confirmed to be the diallyl compound (1) involved in the following structure.

[0052] diallyl compound (1)

[0053] (2) Synthesis of thiol compound (1) Diallyl compound (1) obtained in (1) above (1) (100 g, 0.31 mol, 1.0 eq), thioacetic acid (51.9 g, 0.682 mol, 2.2 eq), toluene (360 mL), and azobisisobutyronitrile (AIBN, 5.09 g, 0.031 mol, 0.1 eq) were added to a 1 L four-necked flask and reacted at 80 °C for 4 hours. The resulting reactants were concentrated under reduced pressure to remove toluene, and then crystallized with methanol (500 g). The crystals were dried under vacuum, and 110.36 g of the dried crystals were recovered. The recovered dried crystals (110.36 g) and 32% NaOH (550 g) were added to a 3 L four-necked flask and reacted at 80 °C for 2 hours. After neutralization with 1 N HCl (380 mL), the organic layer was separated and washed with water. Toluene was removed from the water-washed organic layer by vacuum concentration to give 89.0 g of the target thiol compound (yield 74%). The obtained thiol compounds were analyzed using the LC / MS method described above, and spectral peaks were detected at m / z = 391 for the proton adduct and m / z = 408 for the ammonium adduct. Based on these analytical data and Figure 1 The NMR spectrum results shown confirm that the obtained thiol compound is the structure of the thiol compound (1) involved in the following structure.

[0054] Thiol compounds (1)

[0055] [Example 2] Synthesis of thiol compound (2) (1) Synthesis of aliphatic skeleton diallyl compounds (2) Except for changing 201.0 g (1.05 mol) of 2-allylphenol (reagent) in Example 1 to 201.0 g (1.05 mol) of 4-allylphenol (reagent), the procedure was the same as in Example 1 to obtain 142 g of liquid resin. The obtained liquid resin was measured using the LC / MS method described above, and spectral peaks were detected at m / z = 323 for the proton adduct and m / z = 340 for the ammonium adduct. Based on this analytical data, the obtained liquid resin was confirmed to be the diallyl compound (2) involved in the following structure.

[0056] diallyl compounds (2)

[0057] (2) Synthesis of thiol compound (2) Except that 100g (0.31mol) of diallyl compound (1) in Example 1 (2) was replaced with 100g (0.31mol) of diallyl compound (2) synthesized in Example 2 (1), the same procedure as in Example 1 (2) was followed to obtain 91g of the target thiol compound. The obtained thiol compound was analyzed using the LC / MS method described above, and spectral peaks were detected at m / z = 391 for the proton adduct and m / z = 408 for the ammonium adduct. Based on the results of this analysis, the obtained thiol compound was confirmed to be the structure of the thiol compound (2) described below.

[0058] Thiol compounds (2)

[0059] [Example 3] Synthesis of thiol compound (3) (1) Synthesis of aliphatic skeleton diallyl compound (3) Except for replacing 108.0 g (0.5 mol) of 1,4-dibromobutane (reagent) in Example 1 with 150.0 g (0.5 mol) of 1,10-dibromodecane, the procedure was the same as in Example 1 to obtain 165 g of liquid resin. The obtained liquid resin was measured using the LC / MS method described above, and spectral peaks were detected at m / z = 407 for the proton adduct and m / z = 424 for the ammonium adduct. Based on this analytical data, the obtained liquid resin was confirmed to be the diallyl compound (3) involved in the following structure.

[0060] diallyl compounds (3)

[0061] (2) Synthesis of thiols (3) Except that 100 g (0.31 mol) of diallyl compound (1) in Example 1 (2) was replaced with 125.9 g (0.31 mol) of diallyl compound (3) synthesized in Example 3 (1), the procedure was the same as in Example 1 (2) to obtain 109 g of the target thiol compound. The LC / MS determination of the obtained thiol compound according to the above-described method yielded spectral peaks of m / z = 475 for the proton adduct and m / z = 492 for the ammonium adduct. Based on this analytical data and Figure 2 The NMR spectrum results shown confirm that the obtained thiol compound is the structure of the thiol compound (3) involved in the following structure.

[0062] Thiol compounds (3)

[0063] [Example 4] Synthesis of thiol compound (4) (1) Synthesis of aliphatic skeleton diallyl compound (4) Except for replacing 201.0 g (1.05 mol) of 2-allylphenol (reagent) in Example 1 with 172.4 g of eugenol, the procedure was the same as in Example 1 to obtain 161 g of liquid resin. The obtained liquid resin was measured using the LC / MS method described above, and spectral peaks were detected at m / z = 383 for the proton adduct and m / z = 400 for the ammonium adduct. Based on this analytical data, the obtained liquid resin was confirmed to be the diallyl compound (4) involved in the following structure.

[0064] diallyl compounds (4)

[0065] (2) Synthesis of thiol compound (4) Except for changing 100g (0.31mol) of diallyl compound (1) in Example 1 (2) to 118.6g (0.31mol) of diallyl compound (4) synthesized in Example 4 (1), the same procedure as in Synthesis Example 1 (2) was followed to obtain 107g of the target thiol compound. The obtained thiol compound was measured using the LC / MS method described above, and spectral peaks were detected at m / z = 451 for the proton adduct and m / z = 468 for the ammonium adduct. Based on the results of this analysis, the obtained thiol compound was confirmed to be the structure of the thiol compound (4) described below.

[0066] Thiol compounds (4)

[0067] [Example 5] Synthesis of thiol compound (5) (1) Synthesis of diallyl compound (5) In a 2-liter four-necked round flask equipped with a stirrer, thermometer, condenser, dropping funnel, and Dianstar water separator, 155.6 g (1.05 mol) of 2-allyl-6-methylphenol (reagent), 150.0 g (0.5 mol) of 1,10-dibromodecane, 3.1 g of tetrabutylammonium bromide as a phase transfer catalyst, and 300 g of methyl isobutyl ketone (MIBK) as a reaction solvent were added. The mixture was heated to 100°C to completely dissolve the phenol. 175 g (1.5 mol) of 48% KOH aqueous solution was added dropwise to the resulting solution over 1 hour. The water and MIBK were separated into water and MIBK by azeotropic distillation of the added KOH aqueous solution, with only MIBK being returned to the reaction system while the reaction continued. The reaction was then continued for 6 hours while only MIBK was returned to the system and water was removed by distillation at 118°C. Then, the temperature was lowered to 60°C, 100g of distilled water was added, and the mixture was allowed to stand, discarding the lower brine layer. Next, 100g of distilled water and an appropriate amount of sodium dihydrogen phosphate for neutralization were added, and the mixture was allowed to stand and separate, discarding the lower brine layer. Then, an equal amount of distilled water was added, and the mixture was washed twice for purification. The solution was then heated to 118°C for azeotropic dehydration. After removing impurities by precise filtration using filter paper No. 5C (manufactured by Kiriyama Corporation) and a Kiriyama funnel (manufactured by Kiriyama Corporation), MIBK and unreacted 2-allyl-6-methylphenol were distilled under reduced pressure at a maximum temperature of 180°C to obtain 176g of liquid resin. The obtained liquid resin was measured using the LC / MS method described above, and spectral peaks were detected at m / z = 435 for the proton adduct and m / z = 452 for the ammonium adduct. Based on this analytical data, the obtained liquid resin was confirmed to be the diallyl compound (5) involved in the structure described below.

[0068] diallyl compounds (5)

[0069] (2) Synthesis of thiol compound (5) Except that 100g (0.31mol) of diallyl compound (1) obtained in Example 1 (2) was replaced with 134.7g (0.31mol) of aliphatic skeleton diallyl compound (5) synthesized in Example 5 (1), the same procedure as in Example 1 (2) was followed to obtain 110g of the target thiol compound. The obtained thiol compound was analyzed using the LC / MS method described above, and spectral peaks were detected at m / z = 475 for the proton adduct and m / z = 492 for the ammonium adduct. Based on the results of this analysis, the obtained thiol compound was confirmed to be the structure of the thiol compound (5) described below.

[0070] Thiol compounds (5)

[0071] [Evaluation Test] The curing state of epoxy resins cured using the thiol compounds obtained in the above examples was evaluated. Specifically, epoxy resin, thiol compounds, and curing accelerator (AJICURE PN-H, manufactured by Ajinomoto Fine Technology Co., Ltd.) were weighed and mixed in the amounts shown in Table 1 below (the amounts of components in Table 1 are parts by mass). Then, the mixture was degassed under vacuum at 900 rpm for 2 minutes using an automatic rotary stirring degassing machine (Kyoritsu Seiki Co., Ltd.: HM-200W) to obtain the target resin composition. The obtained resin composition was cured in a thermal cycling oven at 120°C for 1 hour to obtain a cured product. The surface of the cured product was touched with a finger to check for any residue adhering to the finger. As the epoxy resin, jER (registered trademark) 828 (manufactured by Mitsubishi Chemical Corporation) was used. As the thiol curing agent of Comparative Example 1, BD-1 (1,4-bis(3-mercaptobutyryloxy)butane, manufactured by Risenok Co., Ltd.) was used.

[0072] BD-1 (1,4-bis(3-mercaptobutyryloxy)butane)

[0073] Table 1

[0074] As shown in Table 1, Examples 1 and 2 yielded non-sticky cured products. On the other hand, in Comparative Example 1, a portion of the cured product adhered to the fingers, confirming its stickiness, and visual inspection revealed that at least a portion was in an uncured state.

[0075] [Example of Synthetic Application] In the synthesis of various thiol compounds in the above embodiments, a wide variety of compounds represented by general formula (I) can be synthesized by substituting other compounds as starting materials. Here, a specific synthetic application example of the synthesis example of the aliphatic skeleton diallyl compound (1) of Example 1 is shown below. <Example 1 of Synthetic Application> The raw material replaced in Example 1: 2-Allylphenol Alternative raw material used: 1-(2-propen-1-yl)-2-naphthol Examples of compounds represented by general formula (I): Thiol compounds (1b) with the following structures (in general formula (I), ring P is naphthyl).

[0076] <Example 2 of Synthetic Application> The raw material replaced in Example 1: 2-Allylphenol Alternative raw material used: 4-ethyl-2-(2-propen-1-yl)phenol Examples of compounds represented by general formula (I): Thiol compounds (1c) with the following structures (in general formula (I), B is ethyl). <Example 3 of Synthetic Application> The raw material replaced in Example 1: 2-Allylphenol Alternative raw material used: 4-ethoxy-2-(2-propen-1-yl)phenol Examples of compounds represented by general formula (I): Thiol compounds (1d) with the following structures (in general formula (I), B is ethoxy).

[0077] <Example 4 of Synthetic Application> The raw material replaced in Example 1: 2-Allylphenol Alternative raw material used: 2-vinylphenol Examples of compounds represented by general formula (I): Thiol compounds (1e) with the following structures (in general formula (I), R1 is a C2-alkylene group). (1e) <Example 5 of Synthetic Application> The raw material replaced in Example 1: 2-Allylphenol Alternative raw material used: N-methyl-2-(2-propen-1-yl)aniline Examples of compounds represented by general formula (I): Thiol compounds (1f) with the following structures (in general formula (I), X is -N(CH3)-)

[0078] <Example 6 of Synthetic Application> The raw material replaced in Example 1: 2-Allylphenol Alternative raw material used: 2-(2-propen-1-yl)benzylthiol Examples of compounds represented by general formula (I): Thiol compounds with the following structures (1g) (in general formula (I), X is -S-) <Example 7 of Synthetic Application> The raw material replaced in Example 1: 1,4-dibromobutane Alternative raw material used: 2-bromoethyl ether Examples of compounds represented by general formula (I): Thiol compounds (1h) with the following structures (in general formula (I), Z is -O-)

[0079] <Example 8 of Synthetic Application> The raw material replaced in Example 1: 1,4-dibromobutane Alternative feedstock used: 1,1'-Thiobis[2-bromoethane] Examples of compounds represented by general formula (I): Thiol compounds (1i) with the following structures (in general formula (I), Z is -S-) <Example 9 of Synthetic Application> The raw material replaced in Example 1: 1,4-dibromobutane Alternative raw material used: 1,6-dibromo-2,5-dimethylhexane Examples of compounds represented by general formula (I): Thiol compounds (1j) with the following structures (in general formula (I), Y is methyl)

Claims

1. Compounds represented by general formula (I): In formula (I), The ring P can be phenyl or naphthyl independently. When ring P is phenyl, there are 1 to 5 A atoms relative to each ring P; when ring P is naphthyl, there are 1 to 7 A atoms relative to each ring P. Each A is independently -R1-SH. R1 is independently a C1 to C6 alkylene group that is optionally substituted with one or more Y atoms. B is a substituent on ring P other than A, and is independently a hydrogen atom, a C1-C6 alkyl group optionally substituted with one or more Y atoms, or a C1-C6 alkoxy group optionally substituted with one or more Y atoms. When ring P is phenyl, A and B are independently bonded at the ortho, meta, or para positions relative to the position of ring P bonded to the main chain; when ring P is naphthyl, A and B are independently bonded at the ortho, meta, para, ana-, ε-, kata-, peri-, pros-, amphi-, or 2,7 positions relative to the position of ring P bonded to the main chain. X can be independently -CH2-, -O-, -N(-R2)-, or -S-. R2 can be a hydrogen atom, a C1-C6 alkyl group optionally substituted with one or more Y atoms, or a C1-C6 alkoxy group optionally substituted with one or more Y atoms. Y can be independently a hydrogen atom, a C1-C6 alkyl group, or a C1-C6 alkoxy group. Z can be a direct bond, -CH2-, -O-, or -S-, respectively. n is an integer from 1 to 20.

2. The compound according to claim 1, wherein, Ring P is phenyl, and A exists once in each ring P. Relative to the position of ring P bonded to the main chain, A is independently bonded to the adjacent or opposite position.

3. The compound according to claim 1, wherein, Ring P is phenyl, A exists once in each ring P, R1 is a straight-chain C2-C3 alkylene group, B is all hydrogen atoms, X is -O-, Y is hydrogen atom, Z is a direct bond or -O-, and n is an integer from 2 to 5.

4. The compound according to claim 1, wherein, Ring P is phenyl, A exists once in each ring P, R1 is a straight-chain C2-C3 alkylene, one B in each ring P is methyl, methoxy or phenyl, all other B in each ring P are hydrogen atoms, X is -O-, Y is a hydrogen atom, Z is a direct bond or -O-, and n is an integer from 2 to 5.

5. The following compounds are shown: or 6. An epoxy resin composition comprising an epoxy resin and the compound according to any one of claims 1 to 5.

7. A curing agent for epoxy resin, comprising the compound according to any one of claims 1 to 5.

8. An epoxy resin cured product formed by thermosetting an epoxy resin and a compound according to any one of claims 1 to 5.

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