Epoxy resin curable composition and adhesive containing the same

Abstract

Provided is an epoxy resin curable composition that cures quickly and has a high hardness and excellent color tone after curing. This epoxy resin curable composition, which contains an epoxy resin having two or more epoxy groups per molecule, thiol compound A having two or more thiol groups per molecule, an amine compound having primary and / or secondary amino groups and thiol compound B represented by any of specific general formulae (1) to (3), is characterized in that: the thiol compound A and the thiol compound B are different from each other; and when the number of moles of the epoxy groups in the epoxy resin curable composition is regarded as Me, the number of moles of the thiol groups in the thiol compound A is regarded as MA and the number of moles of the thiol groups in the thiol compound B is regarded as MB, then the molar ratio MA / Me is 0.29-0.80 and the molar ratio MB / Me is 0.02-0.4.

Description

[Technical Field]

[0001] The present invention relates to an epoxy resin curable composition that exhibits rapid curing, high hardness after curing, strong adhesive strength, and excellent color tone in the cured product. [Background technology]

[0002] Epoxy resins have long been widely used as adhesives due to their excellent adhesion, chemical resistance, and physical properties. For applications requiring rapid curing and high adhesive strength, methods are known to add thiol compounds as curing agents and amines as curing accelerators.

[0003] Numerous compounds containing terminal thiol groups that do not have a polysulfide skeleton in their main chain have been reported as compounds that can rapidly react thiol groups with epoxy groups (see, for example, Patent Document 1). Among these, compounds having a polyether skeleton in their main chain and containing three or more thiol groups per molecule are widely available as epoxy resin curing agents that combine economy and safety. Examples of compounds having a polyether skeleton in their main chain and containing three or more thiol groups per molecule include "Polythiol QE-340M" from Toray Fine Chemicals Co., Ltd., and "Capcure3-800" and "GPM-800" from Gabriel Performance Products.

[0004] Examples of amines widely used as curing accelerators for thiol and epoxy groups include tertiary amines such as 2,4,6-tris(dimethylaminomethyl)phenol (manufactured by Evonik Co., Ltd., ANCAMINE K-54), N,N-dimethylpropylamine, and bis(2-dimethylaminoethyl) ether.

[0005] However, conventionally known epoxy resin curing compositions yellow and discolor upon curing, which posed a problem in applications where near-colorless and excellent color tone are required, such as adhesives for glass and decorative items.

[0006] Conventional colorless epoxy resin curable compositions have slow curing times, making them unsuitable for applications requiring rapid curing, and their hardness and adhesive strength are not always sufficient. Thus, it has been difficult to achieve a combination of rapid curing, hardness, adhesive strength, and color in epoxy resin curable compositions consisting of epoxy resin, thiol compounds, and amine compounds. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] Japanese Patent Publication No. 8-269203 [Overview of the project] [Problems that the invention aims to solve]

[0008] This invention provides an epoxy resin curable composition that exhibits rapid curing, high hardness after curing, and excellent color tone. [Means for solving the problem]

[0009] The epoxy resin curable composition of the present invention is an epoxy resin curable composition comprising an epoxy resin having two or more epoxy groups in one molecule, a thiol compound A having two or more thiol groups in one molecule, an amine compound having a primary amine and / or a secondary amine, and a thiol compound B represented by any of the following general formulas (1) to (3), wherein the thiol compound A and thiol compound B are different from each other, the number of moles of epoxy groups contained in the epoxy resin curable composition is Me, and the number of moles of thiol groups contained in the thiol compound A is M. A M is the number of moles of thiol groups in the thiol compound B. B In that case, the molar ratio M A / Me is 0.29-0.80, and the molar ratio M B It is characterized by / Me being between 0.02 and 0.4. (R 2 ) n -C-(R 3 -O-CO-R 1-SH) 4-n (1) (In general formula (1), R 1 is an alkylene group having 1 to 10 carbon atoms independently of each other, R 2 is a hydrogen atom, an alkyl group having 1 to 10 carbon atoms or a hydroxyalkyl group having 1 to 3 carbon atoms, R 3 is an alkylene group having 1 to 3 carbon atoms independently of each other, n represents an integer of 0 to 2, and -SH is bonded to any carbon atom of R 1 .)

Chemical formula

Advantages of the invention

[0010] The epoxy resin curable composition of the present invention cures quickly, has high hardness after curing, strong adhesive strength, and excellent color tone.

[0011] When the epoxy resin curable composition of the present invention is used as an adhesive, it has strong adhesive force to various adherends such as metals and glasses. This epoxy resin curable composition can be used as an adhesive, a sealing material, a potting material, a coating agent, a resin modifier, etc.

[0012] In particular, since the epoxy resin curable composition of the present invention has an excellent color tone, it is optimal for glass adhesives, decorative adhesives, watch part adhesives, electrical and electronic adhesives, electrical and electronic potting materials, and household carpentry adhesives. [Modes for carrying out the invention]

[0013] The epoxy resin curable composition of the present invention contains an epoxy resin having two or more epoxy groups in one molecule, a thiol compound A having two or more thiol groups in one molecule, an amine compound having a primary amino group and / or a secondary amino group, and a thiol compound B represented by a specific structural formula and different from thiol compound A.

[0014] Examples of epoxy resins having two or more epoxy groups in one molecule include epoxy resins obtained by adding epichlorohydrin to polyhydric phenols such as bisphenol A, bisphenol F, resorcinol, hydroquinone, pyrocatechol, 4,4-dihydroxybiphenyl, and 1,5-hydroxynaphthalene; epoxy resins obtained by adding epichlorohydrin to polyhydric alcohols such as ethylene glycol, propylene glycol, and glycerin; epoxy resins obtained by adding epichlorohydrin to aromatic dicarboxylic acids such as oxybenzoic acid and phthalic acid; and polysulfide polymers having epoxy groups at the ends (product names "FLEP-50" and "FLEP-60," both manufactured by Toray Fine Chemicals Co., Ltd.). From the viewpoint of workability and suppression of poor mixing, epoxy resins having two or more epoxy groups in one molecule are preferably liquid at room temperature. Examples of epoxy resins having two or more epoxy groups in one molecule include jER-828 (trade name, manufactured by Mitsubishi Chemical Corporation), DER-331 (trade name, manufactured by Dow Chemical), jER-825 (trade name, manufactured by Mitsubishi Chemical Corporation), jER-827 (trade name, manufactured by Mitsubishi Chemical Corporation), jER-806 (trade name, manufactured by Mitsubishi Chemical Corporation), and jER-807 (trade name, manufactured by Mitsubishi Chemical Corporation).

[0015] Epoxy resins having two or more epoxy groups per molecule are preferably those with an epoxy equivalent of 50 to 1000 g / eq. More preferably, epoxy resins having two or more epoxy groups per molecule have an epoxy equivalent of 100 to 300 g / eq.

[0016] The epoxy resin curable composition contains at least two thiol compounds, consisting of thiol compound A and thiol compound B, which allows for rapid curing, high hardness after curing, strong adhesive strength, and excellent color tone.

[0017] Thiol compound B is a different compound from thiool compound A, and is a thiol compound represented by one of the following general formulas (1) to (3). (R 2 ) n -C-(R 3 -O-CO-R 1 -SH) 4-n (1) (In general formula (1), R 1 These are alkylene groups with 1 to 10 carbon atoms, R 2 R is a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, or a hydroxyalkyl group having 1 to 3 carbon atoms. 3 The terms are alkylene groups with 1 to 3 carbon atoms, n is an integer from 0 to 2, and -SH is R 1 (It bonds to any carbon atom.) [ka] (R 2 ) n -C-(R 3 -OR 1 -SH) 4-n (3) (In general formula (3), R 1 These are alkylene groups with 1 to 10 carbon atoms, R 2 R is a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, or a hydroxyalkyl group having 1 to 3 carbon atoms. 3 The terms are alkylene groups with 1 to 3 carbon atoms, n is an integer from 0 to 2, and -SH is R 1 (It bonds to any carbon atom.)

[0018] In general formula (1), multiple R 1These are alkylene groups having 1 to 10 carbon atoms, preferably alkylene groups having 2 to 7 carbon atoms, and more preferably alkylene groups having 2 to 4 carbon atoms, independently of each other. 1 The alkylene group R may be the same or different from each other. 1 Examples include methylene group, ethylene group, propylene group, 1-methylethylene group, butylene group, ethylethylene group, dimethylethylene group, and the like.

[0019] In general formula (1), multiple R 3 These are alkylene groups having 1 to 3 carbon atoms, preferably alkylene groups having 1 to 2 carbon atoms, independently of each other. 3 The alkylene group R may be the same or different from each other. 3 Examples include methylene groups, ethylene groups, propylene groups, methylethylene groups, and so on.

[0020] In general formula (1), multiple R 2 These are independently a hydrogen atom, a C1-C10 alkyl group or a C1-C3 hydroxyalkyl group, preferably a hydrogen atom, a C1-C4 alkyl group or a C1-C2 hydroxyalkyl group. 3 These may be the same or different from each other. Alkyl group R 3 Examples of hydroxyalkyl groups include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl group, tert-butyl group, etc. Examples of hydroxyalkyl groups include methylol group, hydroxyethyl group, and hydroxypropyll group.

[0021] In general formula (1), n ​​represents an integer between 0 and 2, and -SH represents the alkylene group R 1 A bond of any carbon atom that makes up the structure.

[0022] Examples of thioether compound B represented by general formula (1) include 1,4-bis(3-mercaptopropionyloxy)butane, 1,4-bis(3-mercaptobutyryloxy)butane, trimethylolpropantris(3-mercaptopropionate), trimethylolpropantris(3-mercaptobutyrate), trimethylolpropantris(3-mercaptoisobutyrate), trimethylolpropantris(2-mercaptoisobutyrate), trimethylolpropantristhioglycolate, pentaerythritoltetrakis(3-mercaptopropionate), pentaerythritoltetrakis(3-mercaptobutyrate), pentaerythritoltetrakis(3-mercaptoisobutyrate), pentaerythritoltetrakis(2-mercaptoisobutyrate), pentaerythritoltetrakisthioglycolate, and the like.

[0023] In general formula (3), multiple R 1 These are alkylene groups having 1 to 10 carbon atoms, preferably alkylene groups having 2 to 7 carbon atoms, and more preferably alkylene groups having 2 to 4 carbon atoms, independently of each other. 1 The alkylene group R may be the same or different from each other. 1 Examples include methylene group, ethylene group, propylene group, 1-methylethylene group, butylene group, ethylethylene group, dimethylethylene group, and the like.

[0024] In general formula (3), multiple R 3 These are alkylene groups having 1 to 3 carbon atoms, preferably alkylene groups having 1 to 2 carbon atoms, independently of each other. 3 The alkylene group R may be the same or different from each other. 3 Examples include methylene groups, ethylene groups, propylene groups, methylethylene groups, and so on.

[0025] In general formula (3), multiple R 2These are independently a hydrogen atom, a C1-C10 alkyl group or a C1-C3 hydroxyalkyl group, preferably a hydrogen atom, a C1-C4 alkyl group or a C1-C2 hydroxyalkyl group. 3 These may be the same or different from each other. Alkyl group R 3 Examples of hydroxyalkyl groups include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl group, tert-butyl group, etc. Examples of hydroxyalkyl groups include methylol group, hydroxyethyl group, and hydroxypropyll group.

[0026] In general formula (3), n represents an integer between 0 and 2, and -SH represents the alkylene group R 1 A bond of any carbon atom that makes up the structure.

[0027] Examples of thioether compound B represented by general formula (3) include trimethylolpropane monopropanthol, trimethylolpropane bis(propanthol), trimethylolpropane tris(propanthol), pentaerythritol monopropanthol, pentaerythritol bis(propanthol), pentaerythritol tris(propanthol), pentaerythritol tetrakis(propanthol), and the like.

[0028] Thiol compound A is a different compound from the thiool compound B described above, and is a thiol compound containing two or more thiol groups in one molecule. Thiol compound A preferably has a polyether moiety in its main chain, and preferably has a thiol group on the carbon adjacent to the carbon having a hydroxyl group. Furthermore, thiol compound A preferably does not have a carbonyl group. The absence of a carbonyl group in thiol compound A is preferable because it suppresses hydrolysis of the cured product and improves its water resistance.

[0029] The structure having a polyether portion in the main chain is preferably represented by the following general formula (4), and the terminal thiol group is preferably represented by the following formula (5). [ka] (However, R 1 R is a residue obtained by removing m hydrogen atoms from a polyhydric amine or polyhydric alcohol with 10 or fewer carbon atoms, 2 (where n is an alkylene group with 2 to 4 carbon atoms, n is an integer from 1 to 200, and m is an integer from 2 to 8.) [ka]

[0030] In the above general formula (4), R 1 The residue is obtained by removing m hydrogen atoms from a polyhydric amine or polyhydric alcohol having 10 or fewer carbon atoms. Examples of polyhydric amines or polyhydric alcohols having 10 or fewer carbon atoms include glycerin, trimethylolpropane, trimethylolethane, hexanetriol, diglycerin, pentaerythritol, triethanolamine, ethylenediamine, and sucrose. These polyhydric amines and polyhydric alcohols may be used alone or in combination. Among the above polyols, glycerin, trimethylolpropane, and trimethylolethane are particularly preferred.

[0031] In the above general formula (4), R 2 This refers to an alkylene group having 2 to 4 carbon atoms. Examples of alkylene groups having 2 to 4 carbon atoms include ethylene, n-propylene, isopropylene, n-butylene, and isobutylene.

[0032] In the general formula (4) above, n is an integer between 1 and 200, preferably between 1 and 100. Also, m is an integer between 2 and 8, preferably between 2 and 5.

[0033] Examples of thiol compounds A having the structure represented by the general formulas (4) and (5) and lacking a carbonyl group include "Polythiol QE-340M" manufactured by Toray Fine Chemicals Co., Ltd., and "Capcure3-800" and "GPM-800" manufactured by Gabriel Performance Products.

[0034] A thiol compound A containing two or more thiol groups in one molecule preferably has at least one thiol group represented by formula (5), and more preferably has two or more. In thiol compound A, all thiol groups may be contained in the structure represented by formula (5).

[0035] Thiol compound A, which contains two or more thiol groups in one molecule, preferably has a thiol group content of 1 to 50% by mass, and more preferably has a thiol group content of 5 to 20% by mass.

[0036] The statement that thiol compound A does not have a carbonyl group means that thiol compound A does not have a carbonyl group, carboxyl group, thiocarboxyl group, amide group, ester bond, thioester bond, etc.

[0037] The epoxy resin and thiol compound described above have a ratio of the number of moles of thiol groups derived from thiol compound A to the number of moles of epoxy groups derived from epoxy resin Me in the epoxy resin curable composition. A Mole ratio M A / Me is 0.29-0.8, and the number of moles of thiol groups from thiol compound B is M relative to the number of moles of epoxy groups from epoxy resin present in the epoxy resin curable composition Me. B Mole ratio M B / Me is between 0.02 and 0.4.

[0038] Mole ratio M A If / Me is less than 0.29, the curing speed will be slower. Also, the molar ratio M A If / Me exceeds 0.8, the Shore D hardness of the cured product of the epoxy resin curable composition cannot be increased. On the other hand, the molar ratio M B If / Me is less than 0.02, the Shore D hardness of the cured product cannot be increased. Also, the molar ratio M B When / Me exceeds 0.4, the Shore D hardness of the cured epoxy resin composition actually decreases. (Molar ratio M) AThe amount of / Me can be determined so that it is preferably 0.29 to 0.7, more preferably 0.29 to 0.65, and even more preferably 0.29 to 0.57. Molar ratio M B The amount of / Me can be determined so that it is preferably 0.02 to 0.3, more preferably 0.03 to 0.2, and even more preferably 0.04 to 0.14.

[0039] The epoxy resin curable composition is characterized by the number of moles M of thiol groups derived from thiol compound A present in the composition. A The number of moles of thiol groups derived from thiol compound B relative to M B Mole ratio M B / M A However, it is preferable that the molar ratio M be 0.02 to 0.5, more preferably 0.04 to 0.4, and even more preferably 0.13 to 0.34. B / M A A value of 0.02 or higher is preferable as it increases the Shore D hardness of the cured product. Also, the molar ratio M B / M A A value of 0.5 or less is preferable because it results in a faster curing speed.

[0040] The amount of thiol compound A is determined by the molar ratio M mentioned above. A The relationship / Me is satisfied, preferably with a molar ratio M B / M A The composition can be appropriately designed to satisfy the relationship and according to the physical properties of the epoxy resin curable composition. For example, it is preferable to blend 50 to 150 parts by mass of thiol compound A with 100 parts by mass of epoxy resin having two or more epoxy groups in one molecule. When 50 to 150 parts by mass of thiol compound A is added to 100 parts by mass of epoxy resin, the epoxy resin curable composition hardens quickly, has high hardness of the cured product, and has sufficient adhesive strength. The amount of thiol compound A blended with 100 parts by mass of epoxy resin is more preferably 60 to 120 parts by mass, and even more preferably 70 to 100 parts by mass.

[0041] Thiol compound B has the molar ratio M described above. B The relationship / Me is satisfied, preferably with a molar ratio MB / M A The composition can be appropriately designed to satisfy the relationship and according to the physical properties of the epoxy resin curable composition. For example, it is preferable to blend 1 to 40 parts by mass of thiol compound B with 100 parts by mass of epoxy resin having two or more epoxy groups in one molecule. When the amount of thiol compound B is 1 to 40 parts by mass with 100 parts by mass of epoxy resin, a cured product with high Shore D hardness and excellent curing speed can be obtained. The amount of thiol compound B blended with 100 parts by mass of epoxy resin is more preferably 1 to 20 parts by mass, and even more preferably 2 to 12 parts by mass.

[0042] The epoxy resin curable composition contains an amine compound having a primary amino group and / or a secondary amino group. The amine compound may have only a primary amino group derived from a primary amine, only a secondary amino group derived from a secondary amine, or both a primary amino group derived from a primary amine and a secondary amino group derived from a secondary amine.

[0043] The amine compound is preferably an aliphatic amine. Examples of aliphatic amines include ethylenediamine, 1,2-diaminopropane, 1,3-diaminopropane, 1,5-diaminopentane, hexamethylenediamine, tetramethylenediamine, trimethylhexamethylenediamine, 2-methyl-1,5-diaminopentane, polyetherdiamine, 1,3-diaminopropane, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, dipropylenetriamine, and bis(hexamethylene)triamine. It is preferable that the amine compound is not an amine in which the amino group of the aliphatic amine is composed solely of secondary amino groups. That is, the aliphatic amine should have at least one primary amino group.

[0044] The amine compound is more preferably an amine having two or more primary amino groups and / or secondary amino groups in one molecule, and no tertiary amino groups. Examples of amine compounds include ethylenediamine, 1,2-diaminopropane, 1,3-diaminopropane, 1,5-diaminopentane, hexamethylenediamine, tetramethylenediamine, trimethylhexamethylenediamine, 2-methyl-1,5-diaminopentane, polyetherdiamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, dipropylenetriamine, bis(hexamethylene)triamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, dipropylenetriamine, and bis(hexamethylene)triamine. Amines having two or more amino groups in one molecule and not having a tertiary amino group in the molecule are more preferably ethylenediamine, diethylenetriamine, triethylenetetramine, 1,3-diaminopropane, and tetraethylenepentamine.

[0045] The amine compound more preferably has three or more primary amino groups and / or secondary amino groups in one molecule. Amines having three or more amino groups in one molecule include diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, dipropylenetriamine, and bis(hexamethylene)triamine, with triethylenetetramine being even more preferred.

[0046] The amine compound is preferably a modified product prepared from an amine having three or more primary amino groups and / or secondary amino groups in one molecule. Among them, modified products prepared from amines having three or more amino groups in one molecule are particularly preferred, such as modified products of diethylenetriamine, modified products of triethylenetetramine, modified products of tetraethylenepentamine, etc. Among these, modified products obtained by reacting a mono- or polyepoxy compound with the amino groups of triethylenetetramine are more preferred. Examples of modified products prepared from amines having three or more amino groups in one molecule include "BB-AMINE 3138" manufactured by BB RESINS SRL.

[0047] The modified product prepared from an amine having three or more amino groups in one molecule preferably has an amine value of 500 to 2500 KOHmg / g, and more preferably has an amine value of 800 to 1700 KOHmg / g.

[0048] The blending amount of the amine compound can be appropriately designed according to the physical properties of the cured product. For example, with respect to 100 parts by mass of an epoxy resin having two or more epoxy groups in one molecule, it is preferable to blend 1 to 30 parts by mass of the amine compound. When the amine compound is 1 to 30 parts by mass with respect to 100 parts by mass of the epoxy resin, rapid curing can be achieved, and a cured product having sufficient adhesive strength and excellent color tone adjustment properties can be obtained. The blending amount of the amine compound with respect to 100 parts by mass of the epoxy resin is more preferably 2 to 30 parts by mass, and even more preferably 5 to 30 parts by mass.

[0049] The epoxy resin curable composition of the present invention cures at room temperature. The epoxy resin curable composition has an excellent color tone close to colorless and / or white after curing. In the present invention, excellent color tone means that the chromaticity a * a * b * in the L*a*b* color system is -10 to +10, and b * [[ID=二十一]] * [[ID=二十二]] * [[ID=二十三]] * [[ID=二十四]] * [[ID=二十五]] *When it is outside the range of -10 to +10, the color tone becomes darker. The epoxy resin curable composition preferably has an L value of a cured product with a thickness of 8 mm * a * b * chromaticity a in the color system * is -8 to +8, and b * is -13 to +15. The epoxy resin curable composition is more preferably an L value of a cured product with a thickness of 8 mm after curing for 24 hours at 23°C and 50% RH * a * b * chromaticity a in the color system * is -8 to +5, and b * is -10 to +15. The chromaticity a of the cured product * is more preferably -7 to +3, even more preferably -5 to +1. The chromaticity b of the cured product * is more preferably -7 to +13, even more preferably -5 to +12, and particularly preferably -1 to +11.

[0050] For the epoxy resin curable composition, the color tone of the cured product with a thickness of 8 mm is L * a * b * In the color space of the color system, the lightness L * is preferably 50 or more, more preferably 55 or more, and even more preferably 60 or more.

[0051] The above L * a * b * The color space of the color system is one of the color display methods formulated by the International Commission on Illumination (CIE) in 1976. It physically measures the stimulus amount of the color light that causes the color sensation, and represents it with the lightness (L * value), the degree of magenta and green (a * value), and the degree of yellow and blue (b * value). If the L * value is 0, it represents black, and if it is 100, it represents white. If the a * value is a negative value, it represents a color closer to green, and if it is a positive value, it represents a color closer to red. If the b * value is a negative value, it represents a color closer to blue, and if it is a positive value, it represents a color closer to yellow.

[0052] Said L * a * b * The method for measuring color space is determined by using a colorimeter (for example, the "CR-300" colorimeter manufactured by Minolta Corporation), which is a measuring device specified in the Japanese Industrial Standard JIS Z 8781-4:2013.

[0053] The epoxy resin curable composition preferably has a curing time of 1 to 20 minutes. More preferably, the curing time of the epoxy resin curable composition, when curing 10 g of the epoxy resin curable composition at 23°C and 50% RH, is 1 to 15 minutes, and even more preferably 1 to 10 minutes. A curing time of 1 to 15 minutes is suitable and preferable for applications where rapid curing is required.

[0054] The curing time was measured using the method for determining the pot life of multi-component adhesives (Method 1) described in JIS K 6870. Under conditions of 23°C and 50% RH, 10 g of epoxy resin was mixed with a thiol compound and an amine compound in the specified proportions. The curing time was defined as the point at which a toothpick inserted into the epoxy resin curable composition became immobile.

[0055] When the epoxy resin curable composition is applied to a thickness of 6.0 mm or more and cured at 23°C and 50% RH, it is preferable that the Shore D hardness according to JIS K7215 is 70 or higher 3 hours after the start of curing, and that the Shore D hardness according to JIS K7215 is 75 or higher 24 hours after the start of curing. A Shore D hardness of 70 or higher 3 hours after the start of curing is preferable as it results in a cured product with strong adhesive strength. A Shore D hardness of 71 to 85, and even more preferably 73 to 84, is preferable 3 hours after the start of curing. Furthermore, a Shore D hardness of 75 or higher 24 hours after the start of curing is preferable as it results in a cured product with strong adhesive strength. A Shore D hardness of 76 to 85, and even more preferably 78 to 84, is preferable 24 hours after the start of curing.

[0056] The epoxy resin curable composition may further contain fillers, plasticizers, flexibility-imparting agents, coupling agents, antioxidants, thixotropy-imparting agents, dispersants, etc., to the extent that they do not hinder the objectives of the present invention.

[0057] The epoxy resin curable composition of the present invention can be used as an adhesive that adheres well to metals, glass, stone, concrete, etc., and has excellent color tone. Adhesives containing this epoxy resin curable composition are suitable for use as, for example, adhesives for iron plates, glass, decorative items, watch parts, and general-purpose carpentry adhesives, and are particularly suitable for use as adhesives for glass, decorative items, watch parts, and general-purpose carpentry adhesives. [Examples]

[0058] Examples and comparative examples are shown below. In the following examples, unless otherwise specified, the raw materials used were general reagents purchased from reagent manufacturers. The following apparatus and methods were used for the analysis.

[0059] ·Curing time The curing time of the epoxy resin curable composition was defined as the point at which a toothpick inserted into the epoxy resin curable composition became immobile, based on the method for determining the pot life of multi-component adhesives described in JIS K 6870 (Method 1). Specifically, under conditions of 23°C and 50% RH, a toothpick was inserted into the epoxy resin curable composition obtained by mixing the raw materials for each example, and the point at which the toothpick became immobile was measured as the curing time. The curing time was measured from the start of mixing, and the state of the toothpick was checked every 30 seconds to determine the time in minutes. For Examples 1-4 and Comparative Examples 1-12, 10 g of epoxy resin was mixed with thiol compound A, thiol compound B, and amine compound in the proportions shown in Tables 1 and 2.

[0060] • Hardness (Shore D hardness) The hardness of the epoxy resin curable composition was measured according to the method specified in JIS K 7215. Specifically, the epoxy resin curable composition was poured into multiple containers with an inner diameter of 31 mm and a depth of 8 mm in a room at a temperature of 23°C and a humidity of 50% RH. Starting from the beginning of mixing of the epoxy resin curable composition, measurement samples of 31 × 8 mm in diameter were obtained at 3 hours and 24 hours later. The flat surface of the sample was measured using a Type D durometer. Measurements were performed three times for each measurement sample, and the average value was taken as the hardness value.

[0061] • Brightness and chromaticity The lightness and chromaticity of the epoxy resin cured product were measured. Specifically, using a colorimeter (Minolta "CR-300") specified in JIS Z 8781-4, the epoxy resin curable composition for each example was placed in a container with an inner diameter of 31 mm and a depth of 8 mm and cured at 23°C and 50% RH. After 24 hours, the epoxy resin cured product was removed from the container, and the lightness L of the 8 mm thick epoxy resin cured product was measured. * , chromaticity a * , chromaticity b * The chromaticity a was measured at room temperature. * and b * The measurement results are shown in Tables 1 and 2.

[0062] Example 1 Under conditions of 23°C and 50% RH, 10 g (100 parts by mass) of Mitsubishi Chemical Corporation's "jER828" (bisphenol A type epoxy resin, epoxy equivalent of 184-194 g / eq) as an epoxy resin having two or more epoxy groups per molecule, 7.9 g (79 parts by mass) of Toray Fine Chemicals Co., Ltd.'s "Polythiol QE-340M" as thiol compound A having two or more thiol groups per molecule, and SC Organic Chemicals Co., Ltd.'s "TMMP" (trimethylolpropanetris(3-mercaptopropionate)) as thiol compound B, where n is 1 and R is 1 in general formula (1). 1 is an ethylene group, R 2 is an ethyl group, R 31.0 g (10 parts by mass) of thiol compound A, which is a methylene group, will be abbreviated as "TMMP" below and in the table, and 1.1 g (11 parts by mass) of "BB-AMINE 3138" manufactured by BB RESINS SRL, which is an amine compound having a primary amino group and / or a secondary amino group, were mixed with a spatula for 15 seconds to obtain an epoxy resin curable composition. Note that the number of moles of epoxy groups in the epoxy resin curable composition is Me, and the number of moles of thiol groups derived from thiol compound A is M. A , and the number of moles M of thiol groups derived from thiol compound B B This is shown in Table 1. Also, the molar ratio M A / Me, M A / Me, and M B / M A The calculations were made and recorded.

[0063] When the curing time at 23°C was measured using the obtained epoxy resin curable composition, it cured in 6 minutes. Furthermore, the Shore D hardness was 73 after 3 hours from the start of curing, and 78 after 24 hours from the start of curing. In addition, when the chromaticity of the cured epoxy resin composition was measured, the chromaticity a * -3, b * The result was 7. These results are shown in Table 1.

[0064] Example 2 Thiol compound B is obtained from TMMP, and then from SC Organic Chemicals' "PEMP" (pentaerythritol tetrakis(3-mercaptopropionate), general formula (1), where n is 0, R 1 is an ethylene group, R 3 An epoxy resin curable composition was obtained in the same manner as in Example 1, except that the amount was changed to 1.0 g (10 parts by mass) of the methylene group, which will be abbreviated as "PEMP" below and in the table.

[0065] In the same manner as in Example 1, the curing time at 23°C was measured, and it cured in 6 minutes. Furthermore, the Shore D hardness was 77 after 3 hours from the start of curing, and 80 after 24 hours from the start of curing. In addition, the chromaticity of the cured epoxy resin composition was measured, and the chromaticity a * -3, b* The result was 7. These results are shown in Table 1.

[0066] Example 3 An epoxy resin curable composition was obtained in the same manner as in Example 1, except that thiol compound A was changed to 4.0 g (40 parts by mass) and thiol compound B was changed to 0.3 g (3 parts by mass).

[0067] In the same manner as in Example 1, the curing time at 23°C was measured, and it cured in 6 minutes. Furthermore, the Shore D hardness was 76 after 3 hours from the start of curing, and 80 after 24 hours from the start of curing. In addition, the chromaticity of the cured epoxy resin composition was measured, and the chromaticity a * -5, b * The result was 7. These results are shown in Table 1.

[0068] Example 4 An epoxy resin curable composition was obtained in the same manner as in Example 1, except that thiol compound A was changed to 4.0 g (40 parts by mass), thiol compound B to 0.3 g (3 parts by mass), and amine compound to 3.0 g (30 parts by mass).

[0069] In the same manner as in Example 1, the curing time at 23°C was measured, and it cured in 3 minutes. Furthermore, the Shore D hardness was 82 after 3 hours from the start of curing, and 81 after 24 hours from the start of curing. In addition, the chromaticity of the cured epoxy resin composition was measured, and the chromaticity a * -5, b * The result was 11. These results are shown in Table 1.

[0070] Comparative Example 1 An epoxy resin curable composition was obtained in the same manner as in Example 1, except that thiol compound A was changed to 8.9 g (89 parts by mass) and thiol compound B was not included.

[0071] In the same manner as in Example 1, the curing time at 23°C was measured, and it cured in 6 minutes. Furthermore, the Shore D hardness was 72 after 3 hours from the start of curing, and 73 after 24 hours from the start of curing. In addition, the chromaticity of the cured epoxy resin composition was measured, and the chromaticity a * -5, b * The result was 7. These results are shown in Table 1.

[0072] Comparative Example 2 An epoxy resin curable composition was obtained in the same manner as in Example 1, except that thiol compound A was changed to 0.1 g (1 part by mass) and thiol compound B to 8.8 g (88 parts by mass).

[0073] In the same manner as in Example 1, the curing time at 23°C was measured, and it cured in 11 minutes. Furthermore, the Shore D hardness was 37 after 3 hours from the start of curing, and 47 after 24 hours from the start of curing. In addition, the chromaticity of the cured epoxy resin composition was measured, and the chromaticity a * 0, b * The result was 10. These results are shown in Table 1.

[0074] Comparative Example 3 An epoxy resin curable composition was obtained in the same manner as in Example 1, except that thiol compound A was changed to 11.9 g (119 parts by mass) and thiol compound B was changed to 4.0 g (40 parts by mass).

[0075] In the same manner as in Example 1, the curing time at 23°C was measured, and it cured in 7 minutes. Furthermore, the Shore D hardness was 18 after 3 hours from the start of curing, and 18 after 24 hours from the start of curing. In addition, the chromaticity of the cured epoxy resin composition was measured, and the chromaticity a * 0, b * The result was 10. These results are shown in Table 1.

[0076] Comparative Example 4 An epoxy resin curable composition was obtained in the same manner as in Example 1, except that 11.9 g (119 parts by mass) of thiol compound A and 0.3 g (3 parts by mass) of thiol compound B were used.

[0077] In the same manner as in Example 1, the curing time at 23°C was measured, and it cured in 7 minutes. Furthermore, the Shore D hardness was 42 after 3 hours from the start of curing, and 40 after 24 hours from the start of curing. In addition, the chromaticity of the cured epoxy resin composition was measured, and the chromaticity a * -2, b * The result was 8. These results are shown in Table 1.

[0078] Comparative Example 5 An epoxy resin curable composition was obtained in the same manner as in Example 1, except that thiol compound A was changed to 4.0 g (40 parts by mass) and thiol compound B was changed to 4.0 g (40 parts by mass).

[0079] In the same manner as in Example 1, the curing time at 23°C was measured, and it cured in 6 minutes. Furthermore, the Shore D hardness was 76 after 3 hours from the start of curing, and 74 after 24 hours from the start of curing. In addition, the chromaticity of the cured epoxy resin composition was measured, and the chromaticity a * -1, b * The result was 8. These results are shown in Table 2.

[0080] Comparative Example 6 An epoxy resin curable composition was obtained in the same manner as in Example 1, except that thiol compound A was changed to 11.9 g (119 parts by mass), thiol compound B to 4.0 g (40 parts by mass), and amine compound to 3.0 g (30 parts by mass).

[0081] In the same manner as in Example 1, the curing time at 23°C was measured, and it cured in 4 minutes. Furthermore, the Shore D hardness was 7 after 3 hours from the start of curing, and 5 after 24 hours from the start of curing. In addition, the chromaticity of the cured product of the epoxy resin curable composition was measured, and the chromaticity a * 2, b * The result was 10. These results are shown in Table 2.

[0082] Comparative Example 7 An epoxy resin curable composition was obtained in the same manner as in Example 1, except that thiol compound A was changed to 11.9 g (119 parts by mass), thiol compound B to 4.0 g (40 parts by mass), and amine compound to 0.5 g (5 parts by mass).

[0083] In the same manner as in Example 1, the curing time at 23°C was measured, and it cured in 24 minutes. Furthermore, the Shore D hardness was 19 after 3 hours from the start of curing, and 19 after 24 hours from the start of curing. In addition, the chromaticity of the cured epoxy resin composition was measured, and the chromaticity a * -2, b * The result was 8. These results are shown in Table 2.

[0084] Comparative Example 8 An epoxy resin curable composition was obtained in the same manner as in Example 1, except that thiol compound A was changed to 11.9 g (119 parts by mass), thiol compound B to 0.3 g (3 parts by mass), and amine compound to 3.0 g (30 parts by mass).

[0085] In the same manner as in Example 1, the curing time at 23°C was measured, and it cured in 3 minutes. Furthermore, the Shore D hardness was 21 after 3 hours from the start of curing, and 18 after 24 hours from the start of curing. In addition, the chromaticity of the cured product of the epoxy resin curable composition was measured, and the chromaticity a * 0, b * The result was 10. These results are shown in Table 2.

[0086] Comparative Example 9 An epoxy resin curable composition was obtained in the same manner as in Example 1, except that thiol compound A was changed to 11.9 g (119 parts by mass), thiol compound B to 0.3 g (3 parts by mass), and amine compound to 0.5 g (5 parts by mass).

[0087] In the same manner as in Example 1, the curing time at 23°C was measured, and it cured in 14 minutes. Furthermore, the Shore D hardness was 34 after 3 hours from the start of curing, and 51 after 24 hours from the start of curing. In addition, the chromaticity of the cured epoxy resin composition was measured, and the chromaticity a *-4, b * The result was 6. These results are shown in Table 2.

[0088] Comparative Example 10 An epoxy resin curable composition was obtained in the same manner as in Example 1, except that thiol compound A was changed to 4.0 g (40 parts by mass), thiol compound B to 4.0 g (40 parts by mass), and amine compound to 3.0 g (30 parts by mass).

[0089] In the same manner as in Example 1, the curing time at 23°C was measured, and it cured in 3 minutes. Furthermore, the Shore D hardness was 52 after 3 hours from the start of curing, and 50 after 24 hours from the start of curing. In addition, the chromaticity of the cured epoxy resin composition was measured, and the chromaticity a * -5, b * The result was 12. These results are shown in Table 2.

[0090] Comparative Example 11 An epoxy resin curable composition was obtained in the same manner as in Example 1, except that thiol compound A was changed to 4.0 g (40 parts by mass), thiol compound B to 4.0 g (40 parts by mass), and amine compound to 0.5 g (5 parts by mass).

[0091] In the same manner as in Example 1, the curing time at 23°C was measured, and it cured in 30 minutes. Furthermore, the Shore D hardness was 51 after 3 hours from the start of curing, and 77 after 24 hours from the start of curing. In addition, the chromaticity of the cured epoxy resin composition was measured, and the chromaticity a * -2, b * The result was 8. These results are shown in Table 2.

[0092] [Table 1]

[0093] [Table 2]

Claims

1. An epoxy resin curable composition comprising an epoxy resin having two or more epoxy groups in one molecule, a thiol compound A having two or more thiol groups in one molecule, an amine compound, and a thiol compound B represented by any of the following general formulas (1) to (3), wherein the amine compound is a modified product made from an amine that does not have a tertiary amino group and has three or more primary amino groups and / or secondary amino groups in one molecule, the thiol compound A and thiol compound B are different from each other, the number of moles of epoxy groups contained in the epoxy resin curable composition is Me, and the number of moles of thiol groups contained in the thiol compound A is M. Ａ M is the number of moles of thiol groups in the thiol compound B. Ｂ In that case, the molar ratio M Ａ / Me is between 0.29 and 0.80, and the molar ratio M Ｂ / Me is 0.02 to 0.4, and the molar ratio M Ｂ / M Ａ An epoxy resin curable composition having a ratio of 0.02 to 0.

5. (R ２ ) ｎ -C-(R ３ -O-CO-R １ -SH) ４－ｎ (1) (In general formula (1), R １ These are alkylene groups having 1 to 10 carbon atoms, R ２ R is a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, or a hydroxyalkyl group having 1 to 3 carbon atoms. ３ The terms are alkylene groups with 1 to 3 carbon atoms, n is an integer from 0 to 2, and -SH is R １ (It bonds to any carbon atom.) 【Chemistry 1】 (R) ２ ) ｎ -C-(R ３ -O-R １ -SH) ４－ｎ (3) (In general formula (3), R １ These are alkylene groups having 1 to 10 carbon atoms, R ２ R is a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, or a hydroxyalkyl group having 1 to 3 carbon atoms. ３ The terms are alkylene groups with 1 to 3 carbon atoms, n is an integer from 0 to 2, and -SH is R １ (It bonds to any carbon atom.)

2. The epoxy resin curable composition according to claim 1, wherein the thiol compound A does not have a carbonyl group.

3. L of the hardened product ＊ a ＊ b ＊ The chromaticity in the color system is a ＊ The range is -10 to +10, and b ＊ The epoxy resin curable composition according to claim 1 or 2, wherein the temperature range is -15 to +15.

4. The epoxy resin curable composition according to claim 1 or 2, wherein the curing time when 10 g of the epoxy resin curable composition is used and cured at 23°C and 50% RH is 1 to 15 minutes.

5. The epoxy resin curable composition according to claim 1 or 2, wherein when the epoxy resin curable composition is applied to a thickness of 6.0 mm or more and cured at 23°C and 50% RH, the Shore D hardness according to JIS K7215 is 70 or higher 3 hours after the start of curing, and the Shore D hardness according to JIS K7215 is 75 or higher 24 hours after the start of curing.

6. An epoxy resin curable composition according to claim 1 or 2, for use as an adhesive.

7. An adhesive containing the epoxy resin curable composition according to claim 1 or 2.

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