Latent curing agent and heat-curable epoxide composition containing the same

Abstract

An object of the present invention is to provide a liquid latent curing agent having high storage stability and a curable epoxide composition using the same. The above-mentioned problem is solved by the present invention by providing (A) a compound obtainable by reacting (a) a bicyclic compound having an amidine skeleton or a compound having a guanidine skeleton, (b) an alcohol having 1 to 20 carbon atoms, and (c) an aliphatic isocyanate compound having one or more isocyanate groups; or (B) This problem can be solved by a latent curing agent including (a) a bicyclic compound having an amidine skeleton or a compound having a guanidine skeleton, and (c) a compound obtained by reacting an aliphatic isocyanate compound having one isocyanate group.

Description

[Technical Field]

[0001] The present invention relates to a latent curing agent and a heat-curable epoxide composition. According to the present invention, a liquid latent curing agent having excellent stability can be provided. [Background technology]

[0002] Latent curing agents for curable epoxide compositions that have good storage stability and cure when heated are in high demand because they can reduce the need for frequent mixing. Most conventional latent curing agents are solids that have been ground into fine particles before use (Patent Document 1, Patent Document 2). On the other hand, there are also liquid latent curing agents. For example, 2-ethyl-4-methylimidazole has a melting point of about 41° C. and can be used in liquid form (Patent Document 3). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Special Publication No. 6-6620 [Patent Document 2] Special Publication No. 6-6621 [Patent Document 3] Japanese Patent Application Laid-Open No. 2010-168516 Summary of the Invention [Problem to be solved by the invention]

[0004] Conventional solid latent curing agents have had problems such as the cost, time, and transportation required for microparticulating the curing agent. On the other hand, the liquid latent curing agent described in Patent Document 3 solves the above problems, but when used in a curable epoxide composition, it has poor storage stability and its viscosity increases over time. Therefore, an object of the present invention is to provide a liquid latent curing agent having high storage stability and a curable epoxide composition using the same. [Means for solving the problem]

[0005] The present inventors have conducted extensive research into liquid latent curing agents with high storage stability, and have surprisingly found that a liquid latent curing agent obtained by reacting a compound having an amidine skeleton or a guanidine skeleton, an alcohol, and an aliphatic isocyanate compound has excellent storage stability. The present invention is based on this finding. Therefore, the present invention provides [1] (A) A compound obtained by reacting (a) a bicyclic compound having an amidine skeleton or a compound having a guanidine skeleton, (b) an alcohol having 1 to 20 carbon atoms, and (c) an aliphatic isocyanate compound having one or more isocyanate groups; or (B) a latent curing agent comprising: (a) a bicyclic compound having an amidine skeleton or a compound having a guanidine skeleton, and (c) a compound obtained by reacting an aliphatic isocyanate compound having one isocyanate group; [2] The latent curing agent according to [1], wherein in (A), the molar ratio of the bicyclic compound having an amidine skeleton or the compound having a guanidine skeleton to the aliphatic isocyanate compound is 0.01 to 5.0, and the molar ratio of the alcohol having 1 to 20 carbon atoms is 0.05 to 10.0, and in (B), the molar ratio of the bicyclic compound having an amidine skeleton or the compound having a guanidine skeleton to the aliphatic isocyanate compound is 0.01 to 5.0. [3] A method for producing a latent curing agent, characterized by: (A) reacting (a) a bicyclic compound having an amidine skeleton or a compound having a guanidine skeleton, (b) an alcohol having 1 to 20 carbon atoms, and (c) an aliphatic isocyanate compound having one or more isocyanate groups; or (B) reacting (a) a bicyclic compound having an amidine skeleton or a compound having a guanidine skeleton, and (c) an aliphatic isocyanate compound having one isocyanate group; [4] The method for producing a latent curing agent according to [3], wherein in (A), the molar ratio of the bicyclic compound having an amidine skeleton or the compound having a guanidine skeleton to the aliphatic isocyanate compound is 0.01 to 5.0, and the molar ratio of the alcohol having 1 to 20 carbon atoms is 0.05 to 10.0, and in (B), the molar ratio of the bicyclic compound having an amidine skeleton or the compound having a guanidine skeleton to the aliphatic isocyanate compound is 0.01 to 5.0. [5] A thermosetting epoxide composition comprising an epoxide compound having an average of more than one epoxy group in the molecule and the latent curing agent according to [1] or [2]. [6] A cured product obtained by curing the heat-curable epoxide composition according to [5]. [7] A coating material comprising the thermosetting epoxide composition according to [5], and [8] An adhesive comprising the thermosetting epoxide composition according to [5]. Regarding. [Effects of the Invention]

[0006] The latent curing agent of the present invention can provide a heat-curable epoxide composition with excellent stability. DETAILED DESCRIPTION OF THE INVENTION

[0007] [1] Latent hardener The latent curing agent of the present invention includes (A) a compound obtained by reacting (a) a bicyclic compound having an amidine skeleton or a compound having a guanidine skeleton (hereinafter, sometimes referred to as component a), (b) an alcohol having 1 to 20 carbon atoms (hereinafter, sometimes referred to as component b), and (c) an aliphatic isocyanate compound having one or more isocyanate groups (hereinafter, sometimes referred to as component c). The latent curing agent of the present invention also includes a compound obtained by reacting (B)(a) a bicyclic compound having an amidine skeleton or a compound having a guanidine skeleton (hereinafter, sometimes referred to as component a), and (c) an aliphatic isocyanate compound having one isocyanate group (hereinafter, sometimes referred to as component c).

[0008] <Bicyclic compound (a) having an amidine skeleton> The amidine skeleton in the bicyclic compound having an amidine skeleton has a structure represented by the following formula (1). [ka] The bicyclic compound having an amidine skeleton is not particularly limited as long as it has the amidine skeleton and is bicyclic, but may be represented by the following formula (2): [ka] or diazabicycloundecene (1,8-diazabicyclo[5.4.0]undec-7-ene; DBU (registered trademark)) represented by the following formula (3): [ka] An example is diazabicyclononene (1,5-diazabicyclo[4.3.0]non-5-ene; DBN), represented by the formula: Therefore, bicyclic compounds with an amidine skeleton contain a nitrogen atom and are heterobicyclic compounds with an amidine skeleton.

[0009] <Compound (a) having a guanidine skeleton> The guanidine skeleton in the compound having a guanidine skeleton is represented by the following formula (4): [ka] The compound having a guanidine skeleton is not limited to, but may be a compound represented by the following general formula (5): [ka] (wherein each R is independently an alkyl group having 1 to 6 carbon atoms) For example, the compound is represented by the following formula (6): [ka] Examples of such methylguanidine include 1,1,3,3-tetramethylguanidine (TMG) represented by the following formula: or 1,3-diphenylguanidine, 1,2,3-tris(tert-butoxycarbonyl)guanidine, phenylbiguanide, and 1,3-di-o-tolylguanidine. The latent curing agent of the present invention may contain both a bicyclic compound having an amidine skeleton and a compound having a guanidine skeleton. A latent curing agent containing two types of components a can also exhibit the excellent stability that is an effect of the present invention.

[0010] Alcohols with 1 to 20 carbon atoms (b) The alcohol having 1 to 20 carbon atoms may be a primary alcohol, a secondary alcohol, or a tertiary alcohol. Examples of the primary alcohol include methanol (C1), ethanol (C2), propan-1-ol (C3), butan-1-ol (C4), pentan-1-ol (C5), hexane-1-ol (C6), heptan-1-ol (C7), octan-1-ol (C8), nonan-1-ol (C9), decan-1-ol (C10), and tetrahydrofuran (C11). 10 ), undecane-1-ol (C 11 ), dodecan-1-ol (C 12 ), tridecan-1-ol (C 13 ), tetradecan-1-ol (C 14 ), pentadecan-1-ol (C 15 ), hexadecan-1-ol (C 16 ), heptadecan-1-ol (C 17 ), octadecane-1-ol (C 18 ), nonadecan-1-ol (C 19 ), or icosan-1-ol (C 20 ) are listed. Secondary alcohols include propan-2-ol (C3), butan-2-ol (C4), pentan-2-ol (C5), hexan-2-ol (C6), heptan-2-ol (C7), cyclohexanol (C6) or 2-methylbutan-1-ol (C5). Tertiary alcohols include 2-methylpropan-2-ol (C4), 2-methylbutan-2-ol (C5), 2-methylpentan-2-ol (C6), 2-methylhexan-2-ol (C7), 2-methylheptan-2-ol (C8), 3-methylpentan-3-ol (C6), or 3-methyloctan-3-ol (C9). The alkyl group contained in the alcohol having 1 to 20 carbon atoms may be a linear alkyl group, a branched alkyl group, or a cyclic alkyl group.

[0011] Aliphatic isocyanate compound (c) The aliphatic isocyanate compound is not particularly limited as long as it has one or more isocyanate groups, but examples thereof include monoisocyanates and diisocyanates. Specific examples of the aliphatic isocyanate compound having one or more isocyanate groups include hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, octadecyl isocyanate, hexyl isocyanate, and butyl isocyanate. Furthermore, examples of the aliphatic isocyanate compound having one isocyanate group include monoisocyanates, and specific examples of the monoisocyanates include hexyl isocyanate and butyl isocyanate.

[0012] <<Amount of each ingredient>> The amount of each component added in the reaction of the latent curing agent of the present invention is not particularly limited as long as the effects of the present invention can be obtained. For example, 0.01 to 5.0 mol of a bicyclic compound having an amidine skeleton or a compound having a guanidine skeleton may be added per 1 mol of an aliphatic isocyanate compound. The lower limit is not limited, but in some embodiments it is 0.03 mol or more, in some embodiments it is 0.05 mol or more, in some embodiments it is 0.07 mol or more, in some embodiments it is 0.09 mol or more, in some embodiments it is 0.1 mol or more, and in some embodiments it is 0.2 mol or more. The upper limit is also not limited, but in some embodiments it is 4.5 mol or less, in some embodiments it is 4.0 mol or less, in some embodiments it is 3.5 mol or less, in some embodiments it is 3.0 mol or less, in some embodiments it is 2.5 mol or less, in some embodiments it is 2.0 mol or less, in some embodiments it is 1.5 mol or less, and in some embodiments it is 1.0 mol or less. The lower and upper limits can be arbitrarily combined to obtain a suitable range. The ratio of the aliphatic isocyanate compound to the bicyclic compound having an amidine skeleton or the compound having a guanidine skeleton is the same in both embodiment (A) and embodiment (B) of the present invention. In embodiment (A) of the present invention, for example, 0.05 to 10.0 mol of the alcohol having 1 to 20 carbon atoms may be added per 1 mol of the aliphatic isocyanate compound. The lower limit is not limited, but in some embodiments it is 0.07 mol or more, in some embodiments it is 0.09 mol or more, in some embodiments it is 0.1 mol or more, in some embodiments it is 0.2 mol or more, in some embodiments it is 0.3 mol or more, in some embodiments it is 0.4 mol or more, and in some embodiments it is 0.5 mol or more. The upper limit is also not limited, but in some embodiments it is 8.0 mol or less, in some embodiments it is 6.0 mol or less, in some embodiments it is 5.0 mol or less, in some embodiments it is 4.0 mol or less, in some embodiments it is 3.0 mol or less, in some embodiments it is 2.5 mol or less, and in some embodiments it is 2.0 mol or less. The above lower and upper limits can be arbitrarily combined to obtain a suitable range.

[0013] <Compounds contained in latent hardeners> The latent curing agent of the present invention includes a compound obtained by reacting the components a, b, and c. Alternatively, the latent curing agent of the present invention includes a compound obtained by reacting the components a and c.

[0014] The latent curing agent of the present invention is liquid. In this specification, liquid means not solid but has even a slight degree of fluidity. Therefore, the viscosity of the latent curing agent of the present invention is 10,000,000 mPa·s or less, in some embodiments 5,000,000 mPa·s or less, in some embodiments 100 mPa·s or less, in some embodiments 1,000,000 mPa·s or less, in some embodiments 300,000 mPa·s or less, and in some embodiments 10 mPa·s or less. The lower limit is 1 mPa·s or more, in some embodiments 10 mPa·s or more, in some embodiments 100 mPa·s or more, and in some embodiments 500 mPa·s or more. The viscosity can be measured using an E-type viscometer, although there is no particular limitation. The E-type viscometer is a rotational viscometer in which a sample is placed between a flat plate and a cone plate, and the cone plate is rotated to measure the viscosity. Specifically, the sample is placed between the flat plate and the cone plate, and the cone plate is rotated. The torque required for rotation is measured, and the viscosity is calculated from the measured torque. The measurement temperature can be, for example, 25°C.

[0015] <<Method for producing latent curing agent>> The method for producing the latent curing agent of the present invention involves reacting (a) a bicyclic compound having an amidine skeleton or a compound having a guanidine skeleton (component a), (b) an alcohol having 1 to 20 carbon atoms (component b), and (c) an aliphatic isocyanate compound having one or more isocyanate groups (component c). This reaction produces a compound that exhibits the effects of the latent curing agent of the present invention. Furthermore, the method for producing the latent curing agent of the present invention involves reacting (a) a bicyclic compound having an amidine skeleton or a compound having a guanidine skeleton (component a), and (c) an aliphatic isocyanate compound having one isocyanate group (component c). This reaction produces a compound that exhibits the effects of the latent curing agent of the present invention.

[0016] In the method for producing the latent curing agent of the present invention, the amounts of component a, component b, and component c added are as described above in "Amount of each component added," and there are no limitations on the order of addition. The reaction temperature is not particularly limited, but is, for example, 23 to 200° C., preferably 50 to 150° C., and more preferably 80 to 120° C. The reaction time is also not particularly limited, but is 5 minutes to 100 hours, preferably 10 minutes to 50 hours, and more preferably 1 to 10 hours. For example, when the reaction temperature is high, the reaction time can be shortened, and when the reaction temperature is low, the reaction time can be lengthened.

[0017] [2] Thermosetting epoxide composition The heat-curable epoxide composition of the present invention comprises an epoxide compound having an average of more than one epoxy group per molecule and the latent curing agent. As shown in the examples below, the heat-curable epoxide composition of the present invention is stable in a mixed state of the epoxide compound and the latent curing agent. Therefore, it can be prepared as a one-part heat-curable epoxide composition and stored for a long period of time. However, the heat-curable epoxide composition of the present invention can also be prepared and stored as a two-part heat-curable epoxide composition consisting of a liquid containing the epoxide compound and a liquid containing the latent curing agent.

[0018] Epoxide compounds The epoxide compounds that can be used in the heat-curable epoxide composition of the present invention are compounds that have an average of more than one epoxy group in the molecule.Specific examples of such glycidyl ethers include glycidyl ethers obtained by reacting epichlorohydrin with polyhydric phenols such as bisphenol A, bisphenol F, bisphenol S, hexahydrobisphenol A, tetramethylbisphenol A, tetramethylbisphenol F, catechol, resorcinol, cresol novolak, tetrabromobisphenol A, trihydroxybiphenyl, benzophenone, bisresorcinol, bisphenol hexafluoroacetone, hydroquinone, triphenylmethane, tetraphenylethane, and bixylenol; polyglycidyl ethers obtained by reacting epichlorohydrin with aliphatic polyhydric alcohols such as glycerin, neopentyl glycol, ethylene glycol, propylene glycol, butylene glycol, hexylene glycol, polyethylene glycol, and polypropylene glycol; glycidyl ether esters obtained by reacting epichlorohydrin with hydroxycarboxylic acids such as p-hydroxybenzoic acid and β-hydroxynaphthoic acid; phthalic acid, methylphthalic acid, isophthalic acid, terephthalic acid, and terephthalic acid; Examples of suitable glycidyl esters include polyglycidyl esters obtained from polycarboxylic acids such as tetrahydrophthalic acid, hexahydrophthalic acid, endomethylenetetrahydrophthalic acid, endomethylenehexahydrophthalic acid, trimellitic acid, and polymerized fatty acids; glycidyl aminoglycidyl ethers obtained from aminophenols and aminoalkylphenols; glycidyl aminoglycidyl esters obtained from aminobenzoic acids; glycidyl amines obtained from aniline, toluidine, tribromoaniline, xylylenediamine, diaminocyclohexane, bisaminomethylcyclohexane, 4,4'-diaminodiphenylmethane, and 4,4'-diaminodiphenylsulfone; epoxidized polyolefins; glycidyl hydantoin; glycidyl alkylhydantoin; triglycidyl cyanurate; and monoepoxides such as butyl glycidyl ether, phenyl glycidyl ether, alkylphenyl glycidyl ether, benzoic acid glycidyl ester, and styrene oxide. These glycidyl esters may be used alone or in combination.

[0019] The weight ratio or molar ratio of the epoxide compound to the latent curing agent in the thermosetting epoxide composition of the present invention is not particularly limited as long as the one-component epoxide composition can be cured to a desired gelation degree. That is, thermosetting epoxide compositions are used for various purposes such as adhesives, paints, coatings, sealing, and impregnation, and the desired curing state, curing time, and use conditions vary depending on the purpose, so the weight ratio or molar ratio of the epoxide compound to the latent curing agent in the epoxide composition can be appropriately selected. The weight ratio relative to the epoxide compound is not limited, but for example, the latent curing agent can be mixed with the epoxide compound at a weight molar ratio of 0.01 to 100, more preferably 0.05 to 50, and even more preferably 0.1 to 10.

[0020] To the thermosetting epoxide composition of the present invention, there may be added, if necessary, an epoxy curing agent, an inert organic or inorganic pigment, a dye, a colorant, an anti-fading agent, an antihalation agent, a fluorescent brightener, a surfactant, a plasticizer, a flame retardant, an antioxidant, a filler, an antistatic agent, an antifoaming agent, a flow control agent, an accelerator, a retarder, a thickener, a light stabilizer, an antifungal agent, an antibacterial agent, an antiseptic, a magnetic material, and the like.

[0021] Examples of epoxy curing agents that may be used as needed in the thermosetting epoxide composition of the present invention include acid anhydrides, amines, phenols, dihydrazines, Lewis acids, Bronsted acid salts, polymercaptones, isocyanates, blocked isocyanates, and dicyandiamide.

[0022] The thermosetting epoxide composition of the present invention does not cure at room temperature (e.g., 0°C to 40°C), but cures rapidly when heated (e.g., 100°C to 200°C), and can be used for adhesives, painting, coating, sealing, and impregnation.

[0023] 《Effect》 The mechanism by which the latent curing agent of the present invention is liquid has not been analyzed in detail, but can be assumed as follows: However, the present invention is not limited to the following assumption. The latent curing agent of the present invention comprises a reaction product of (a) a bicyclic compound having an amidine skeleton or a compound having a guanidine skeleton, (b) an alcohol having 1 to 20 carbon atoms, and (c) an aliphatic isocyanate compound having one or more isocyanate groups, and the reaction product obtained from components (a), (b), and (c) is believed to have a specific structure. The latent curing agent of the present invention also comprises a reaction product of (a) a bicyclic compound having an amidine skeleton or a compound having a guanidine skeleton, and (c) an aliphatic isocyanate compound having one isocyanate group, and the reaction product obtained from components (a) and (c) is believed to have a specific structure. Examples of the specific structure of the resulting reaction product include, but are not limited to, a urea bond or a urethane bond. However, it is believed that the inclusion of compounds having these specific structures allows the latent curing agent to be liquid and exhibit excellent stability. [Example]

[0024] The present invention will be specifically described below with reference to examples, but these examples are not intended to limit the scope of the present invention.

[0025] In the following examples, latent curing agents for curable epoxide compositions that are liquid at room temperature were produced using an aliphatic isocyanate compound (component c), an alcohol compound (component b), and a bicyclic compound having an amidine skeleton or a compound having a guanidine skeleton (component a).

[0026] Example 1 In this example, 168.2 parts (1.0 mol) of hexamethylene diisocyanate (abbreviated as HMDI) as an aliphatic isocyanate compound and 90.1 parts (1.0 mol) of 1-methoxy-2-propanol (abbreviated as PM) as an alcohol compound were mixed, and 62.1 parts (0.5 mol) of 1,5-diazabicyclo[4.3.0]nonene-5 (abbreviated as DBN) as a heterobicyclic compound having an amidine skeleton was added dropwise to cause a reaction, thereby obtaining a latent curing agent for a curable epoxide composition that is liquid at room temperature.

[0027] Example 2 The procedure of Example 1 was repeated except that 54.1 parts (0.6 mol) of 1-methoxy-2-propanol (abbreviated as PM) was mixed with 86.9 parts (0.7 mol) of 1,5-diazabicyclo[4.3.0]nonene-5 (abbreviated as DBN).

[0028] Example 3 The procedure of Example 1 was repeated except that 126.1 parts (1.4 mol) of 1-methoxy-2-propanol (abbreviated as PM) was mixed with 37.3 parts (0.3 mol) of 1,5-diazabicyclo[4.3.0]nonene-5 (abbreviated as DBN).

[0029] Example 4 The procedure of Example 3 was repeated except that 159.8 parts (0.9 mol) of hexamethylene diisocyanate (abbreviated as HMDI) was used.

[0030] Example 5 The procedure of Example 3 was repeated except that 210.3 parts (1.0 mol) of trimethylhexamethylene diisocyanate (abbreviated as TMDI) was used in place of HMDI.

[0031] Example 6 A latent curing agent for a curable epoxide composition that is liquid at room temperature was obtained by adding dropwise 62.1 parts (0.5 mol) of 1,5-diazabicyclo[4.3.0]nonene-5-(DBN) as compound a to 99.2 parts (1.0 mol) of butyl isocyanate (BI) as compound c and reacting them.

[0032] Example 7 The procedure of Example 1 was repeated except that 132.2 parts (1.0 mol) of 1-butoxy-2-propanol (abbreviated as PNB) was used as the alcohol compound.

[0033] Example 8 The procedure of Example 1 was repeated except that 164.2 parts (1.0 mol) of triethylene glycol monomethyl ether (abbreviated as TGME) was used as the alcohol compound.

[0034] Example 9 The procedure of Example 3 was repeated except that 45.7 parts (0.3 mol) of 1,8-diazabicyclo[5.4.0]undecene-7 (abbreviated as DBU) was used as the heterobicyclic compound having an amidine skeleton.

[0035] Example 10 The procedure of Example 1 was repeated except that 153.2 parts (1.7 mol) of 1-methoxy-2-propanol was mixed and 23.0 parts (0.2 mol) of 1,1,3,3-tetramethylguanidine (abbreviated as TMG) was used as the compound having a guanidine skeleton.

[0036] In the following Comparative Examples 1 to 3, curing agents were produced using alicyclic or aromatic isocyanate compounds instead of aliphatic isocyanate compounds. In Comparative Examples 4 to 9, curing agents were produced using heteromonocyclic compounds having an amidine skeleton, primary amine compounds, or secondary amine compounds instead of bicyclic compounds having an amidine skeleton or compounds having a guanidine skeleton.

[0037] Comparative Example 1 222.2 parts (1.0 mol) of isophorone diisocyanate (abbreviated as IPDI) as an alicyclic isocyanate compound and 126.1 parts (1.4 mol) of 1-methoxy-2-propanol as an alcohol compound were mixed, and 37.3 parts (0.3 mol) of 1,5-diazabicyclo[4.3.0]nonene-5 (abbreviated as DBN) as a heterobicyclic compound having an amidine skeleton was added dropwise to cause a reaction, and the resulting product was solid at room temperature.

[0038] Comparative Example 2 The procedure of Comparative Example 1 was repeated, except that 174.2 parts (1.0 mol) of tolylene diisocyanate (abbreviated as TDI) was used as the aromatic isocyanate compound instead of IPDI. The obtained product was a solid at room temperature.

[0039] Comparative Example 3 As an aromatic isocyanate compound, 119.1 parts (1.0 mol) of phenyl isocyanate (abbreviated as FI) was reacted with 62.1 parts (0.5 mol) of 1,5-diazabicyclo[4.3.0]nonene-5 (abbreviated as DBN) dropwise. The obtained product was solid at room temperature.

[0040] Comparative Example 4 The procedure of Example 1 was repeated, except that 153.2 parts (1.7 mol) of 1-methoxy-2-propanol was used as the alcohol compound, and 33.1 parts (0.3 mol) of 2-ethyl-4-methylimidazole (abbreviated as 2E4MZ) was used as the heteromonocyclic compound having an amidine skeleton instead of DBN. The obtained product was liquid at room temperature.

[0041] Comparative Example 5 The procedure of Comparative Example 4 was repeated, except that 24.6 parts (0.3 mol) of 2-methylimidazole (abbreviated as 2MI) was used as a heteromonovalent compound having an amidine skeleton instead of DBN. The obtained product was liquid at room temperature.

[0042] Comparative Example 6 The procedure of Comparative Example 4 was repeated, except that 20.4 parts (0.3 mol) of imidazole (abbreviated as IM) was used as a heteromonovalent compound having an amidine skeleton instead of DBN. The obtained product was liquid at room temperature.

[0043] Comparative Example 7 The procedure of Example 1 was repeated, except that 117.1 parts (1.3 mol) of 1-methoxy-2-propanol was used as the alcohol compound and 41.4 parts (0.7 mol) of propylamine (abbreviated as PA) was used as the primary amine compound instead of DBN. The obtained product was a solid at room temperature.

[0044] Comparative Example 8 The procedure of Comparative Example 7 was repeated, except that 74.9 parts (0.7 mol) of N-methylaniline (abbreviated as N-MA) was used as the secondary amine compound instead of PA. The obtained product was liquid at room temperature.

[0045] Comparative Example 9 The procedure of Comparative Example 7 was repeated, except that 84.8 parts (0.7 mol) of N-methylbenzylamine (abbreviated as N-MBA) was used as the secondary amine compound instead of PA. The obtained product was a solid at room temperature.

[0046] The shapes of the latent curing agents of the present invention obtained in Examples 1 to 10 and the curing agent compositions obtained in Comparative Examples 1 to 9 were measured by the following method. <Evaluation of hardener shape> The shape of the obtained curing agent was visually judged at room temperature to be liquid or solid. Table 1 shows the types and amounts of the isocyanate compound, alcohol compound, and amine compound used for the latent curing agents of the present invention obtained in Examples 1 to 10 and the curing agent compositions obtained in Comparative Examples 1 to 9, as well as the shapes of the obtained curing agent compositions at 23°C.

[0047] [Table 1] HMDI: Hexamethylene diisocyanate TMDI: Trimethylhexamethylene diisocyanate BI: butyl isocyanate IPDI: Isophorone diisocyanate TDI: Tolylene diisocyanate FI: Phenyl isocyanate PM: 1-methoxy-2-propanol PNB: 1-butoxy-2-propanol TGME: Triethylene glycol monomethyl ether DBN: 1,5-diazabicyclo[4.3.0]nonene-5 DBU: 1,8-diazabicyclo[5.4.0]undecene-7 2E4MZ: 2-ethyl-4-methylimidazole 2MI: 2-methylimidazole IM: Imidazole PA: Propylamine N-MA: N-methylaniline N-MBA: N-methylbenzylamine

[0048] In Examples 1 to 4, hexamethylene diisocyanate (HMDI) was used as the aliphatic isocyanate compound, 1-methoxy-2-propanol (PM) was used as the alcohol compound, and 1,5-diazabicyclo[4.3.0]nonene-5 (DBN) was used as the heterobicyclic compound having an amidine skeleton or the compound having a guanidine skeleton, and the obtained latent curing agent was liquid. In Example 5, trimethylhexamethylene diisocyanate (TMDI) was used as the aliphatic isocyanate compound, 1-methoxy-2-propanol (PM) was used as the alcohol compound, and 1,5-diazabicyclo[4.3.0]nonene-5 (DBN) was used as the heterobicyclic compound having an amidine skeleton or the compound having a guanidine skeleton, and the obtained latent curing agent was liquid. In Example 6, butyl isocyanate (BI) was used as the aliphatic isocyanate compound, and 1,5-diazabicyclo[4.3.0]nonene-5 (DBN) was used as the heterobicyclic compound having an amidine skeleton or the compound having a guanidine skeleton, and the obtained latent curing agent was liquid. In Example 7, hexamethylene diisocyanate (HMDI) was used as the aliphatic isocyanate compound, 1-butoxy-2-propanol (PNB) was used as the alcohol compound, and 1,5-diazabicyclo[4.3.0]nonene-5 (DBN) was used as the heterobicyclic compound having an amidine skeleton or the compound having a guanidine skeleton, and the obtained latent curing agent was liquid. In Example 8, hexamethylene diisocyanate (HMDI) was used as the aliphatic isocyanate compound, triethylene glycol monomethyl ether (TGME) was used as the alcohol compound, and 1,5-diazabicyclo[4.3.0]nonene-5 (DBN) was used as the heterobicyclic compound having an amidine skeleton or the compound having a guanidine skeleton, and the obtained latent curing agent was liquid. In Example 9, hexamethylene diisocyanate (HMDI) was used as the aliphatic isocyanate compound, 1-methoxy-2-propanol (PM) was used as the alcohol compound, and 1,8-diazabicyclo[5.4.0]undecene-7 (DBU) was used as the heterobicyclic compound having an amidine skeleton or the compound having a guanidine skeleton, and the obtained latent curing agent was liquid. In Example 10, hexamethylene diisocyanate (HMDI) was used as the aliphatic isocyanate compound, 1-methoxy-2-propanol (PM) was used as the alcohol compound, and 1,1,3,3-tetramethylguanidine (TMG) was used as the heterobicyclic compound having an amidine skeleton or the compound having a guanidine skeleton, and the obtained latent curing agent was liquid.

[0049] In Comparative Example 1, isophorone diisocyanate (IPDI) was used as the alicyclic isocyanate compound, 1-methoxy-2-propanol (PM) was used as the alcohol compound, and 1,5-diazabicyclo[4.3.0]nonene-5 (DBN) was used as the heterobicyclic compound having an amidine skeleton or the compound having a guanidine skeleton, but the obtained latent curing agent was solid. In Comparative Example 2, tolylene diisocyanate (TDI) was used as the aromatic isocyanate compound, 1-methoxy-2-propanol (PM) was used as the alcohol compound, and 1,5-diazabicyclo[4.3.0]nonene-5 (DBN) was used as the heterobicyclic compound having an amidine skeleton or the compound having a guanidine skeleton, but the obtained latent curing agent was solid. In Comparative Example 3, phenyl isocyanate (FI) was used as the aromatic isocyanate compound, and 1,5-diazabicyclo[4.3.0]nonene-5 (DBN) was used as the heterobicyclic compound having an amidine skeleton or the compound having a guanidine skeleton, but the obtained latent curing agent was solid. In Comparative Example 4, hexamethylene diisocyanate (HMDI) was used as the aliphatic isocyanate compound, 1-methoxy-2-propanol (PM) was used as the alcohol compound, and 2-ethyl-4-methylimidazole (2E4MZ) was used as the heteromonocompound having an amidine skeleton, but the obtained latent curing agent was liquid. In Comparative Example 5, hexamethylene diisocyanate (HMDI) was used as the aliphatic isocyanate compound, 1-methoxy-2-propanol (PM) as the alcohol compound, and 2-methylimidazole (2MI) as the heteromonocompound having an amidine skeleton, but the obtained latent curing agent was liquid. In Comparative Example 6, hexamethylene diisocyanate (HMDI) was used as the aliphatic isocyanate compound, 1-methoxy-2-propanol (PM) was used as the alcohol compound, and imidazole (IM) was used as the heteromonocompound having an amidine skeleton, but the obtained latent curing agent was liquid. In Comparative Example 7, hexamethylene diisocyanate (HMDI) was used as the aliphatic isocyanate compound, 1-methoxy-2-propanol (PM) as the alcohol compound, and propylamine (PA) as the primary amine compound, but the resulting latent curing agent was solid. In Comparative Example 8, hexamethylene diisocyanate (HMDI) was used as the aliphatic isocyanate compound, 1-methoxy-2-propanol (PM) as the alcohol compound, and N-methylaniline (N-MA) as the secondary amine compound, but the obtained latent curing agent was liquid. In Comparative Example 9, hexamethylene diisocyanate (HMDI) was used as the aliphatic isocyanate compound, 1-methoxy-2-propanol (PM) as the alcohol compound, and N-methylbenzylamine (N-MBA) as the secondary amine compound, but the obtained latent curing agent was solid.

[0050] In the following Examples 11-19, curable epoxide compositions of the present invention were prepared. Example 11 A one-component curable epoxide composition was obtained by mixing 100 parts of diglycidyl ether of bisphenol A (abbreviated as BADGE) having an epoxy equivalent of 190 as the epoxide and 20 parts of the latent curing agent obtained in Example 1 that is liquid at room temperature as the latent curing agent.

[0051] Example 12 The procedure of Example 11 was repeated, except that 10 parts of the latent curing agent that was liquid at room temperature obtained in Example 2 was used as the latent curing agent.

[0052] Example 13 The procedure of Example 11 was repeated, except that 30 parts of the latent curing agent that was liquid at room temperature obtained in Example 3 was used as the latent curing agent.

[0053] Example 14 The procedure of Example 11 was repeated, except that 30 parts of the latent curing agent that was liquid at room temperature obtained in Example 4 was used as the latent curing agent.

[0054] Example 15 The procedure of Example 10 was repeated, except that 30 parts of the latent curing agent that was liquid at room temperature obtained in Example 5 was used as the latent curing agent.

[0055] Example 16 The procedure of Example 11 was repeated, except that 10 parts of the latent curing agent that was liquid at room temperature obtained in Example 6 was used as the latent curing agent.

[0056] Example 17 The procedure of Example 11 was repeated, except that 30 parts of the latent curing agent that was liquid at room temperature obtained in Example 7 was used as the latent curing agent.

[0057] Example 18 The procedure of Example 11 was repeated, except that 30 parts of the latent curing agent that was liquid at room temperature obtained in Example 8 was used as the latent curing agent.

[0058] Example 19 The procedure of Example 11 was repeated, except that 30 parts of the latent curing agent that was liquid at room temperature obtained in Example 9 was used as the latent curing agent.

[0059] Example 20 The procedure of Example 11 was repeated, except that 30 parts of the latent curing agent that was liquid at room temperature obtained in Example 10 was used as the latent curing agent.

[0060] Comparative Example 10 The procedure of Example 11 was repeated, except that 30 parts of the latent curing agent that was liquid at room temperature obtained in Comparative Example 4 was used as the latent curing agent.

[0061] Comparative Example 11 The procedure of Example 11 was repeated, except that 30 parts of the latent curing agent that was liquid at room temperature obtained in Comparative Example 5 was used as the latent curing agent.

[0062] Comparative Example 12 The procedure of Example 11 was repeated, except that 30 parts of the latent curing agent that was liquid at room temperature obtained in Comparative Example 6 was used as the latent curing agent.

[0063] Comparative Example 13 The procedure of Example 11 was repeated, except that 30 parts of the latent curing agent that was liquid at room temperature obtained in Comparative Example 8 was used as the latent curing agent.

[0064] The one-component curable epoxide compositions of the present invention obtained in Examples 11 to 20 and the curable epoxide compositions obtained in Comparative Examples 10 to 13 were examined for viscosity increase at room temperature and curability when heated to 150°C by the following methods. <Evaluation of Viscosity Increase> The resulting curable epoxide compositions were stored at 40°C for 7 days and 30 days, and the flowability was evaluated visually. ○: Liquid ×: No liquidity

[0065] <Evaluation of hardening> The obtained curable epoxide composition was heated at a predetermined temperature for a predetermined time, and the state was observed. Specifically, 2.0 g of the curable epoxide composition as a sample was placed in a metal container and left to stand on a hot plate set to 150°C for 1 hour. Evaluation was made according to the following criteria. ○: Post-curing at 150℃ for 1 hour ×: Not cured after 1 hour at 150°C

[0066] Table 2 shows the types of curing agents used in the one-component curable epoxide compositions of the present invention obtained in Examples 11 to 20 and the curable epoxide compositions obtained in Comparative Examples 10 to 13, the blending weight ratio of the curing agent composition to the epoxide compound, the evaluation results of viscosity increase, and the evaluation results of curability.

[0067] [Table 2]

[0068] In Examples 11 to 20, one-component curable epoxide compositions were prepared using the latent curing agents obtained in Examples 1 to 10. The fluidity of the obtained curable epoxide compositions was confirmed after 7 days and 30 days at 40°C, and they were confirmed to cure at 150°C for 1 hour.

[0069] In Comparative Examples 10 to 12, one-component curable epoxide compositions were prepared using the latent curing agents obtained in Comparative Examples 4 to 6. The obtained curable epoxide compositions showed no fluidity after 7 days or 30 days at 40°C. Regarding curability, curing was confirmed in 1 hour at 150°C. In Comparative Example 13, a one-component curable epoxide composition was prepared using the latent curing agent obtained in Comparative Example 8. The fluidity of the obtained curable epoxide composition was confirmed after 7 days and 30 days at 40°C. Regarding curability, no cure was confirmed after 1 hour at 150°C. As explained above, the present invention makes it possible to obtain a latent curing agent that is liquid at room temperature by reacting a compound obtained by reacting a bicyclic compound having an amidine skeleton or a compound having a guanidine skeleton with an alcohol compound and an aliphatic isocyanate compound having one or more isocyanate groups.Furthermore, it is possible to provide a one-component curable epoxide composition that contains, as essential components, an epoxide having an average of more than one epoxy group per molecule and a latent curing agent that is liquid at room temperature. [Industrial Applicability]

[0070] The latent curing agent of the present invention can be used as a liquid latent curing agent for a heat-curable epoxide composition. The heat-curable epoxide composition of the present invention can be used as a one-part curable epoxide composition, and can be used for adhesives, coatings, etc.

Claims

1. (A) (a) a bicyclic compound having an amidine skeleton or a compound having a guanidine skeleton, (b) an alcohol having 1 to 20 carbon atoms, and (c) an aliphatic isocyanate compound having one or more isocyanate groups; A compound obtained by reacting A latent curing agent comprising: In the latent curing agent (A), the molar ratio of the bicyclic compound having an amidine skeleton or the compound having a guanidine skeleton to the aliphatic isocyanate compound is 0.01 to 5.0, and the molar ratio of the alcohol having 1 to 20 carbon atoms is 0.05 to 10.

0.

2. (A) (a) a bicyclic compound having an amidine skeleton or a compound having a guanidine skeleton, (b) an alcohol having 1 to 20 carbon atoms, and (c) an aliphatic isocyanate compound having one or more isocyanate groups; To react A method for producing a latent curing agent, characterized by: In the method (A), the molar ratio of the bicyclic compound having an amidine skeleton or the compound having a guanidine skeleton to the aliphatic isocyanate compound is 0.01 to 5.0, and the molar ratio of the alcohol having 1 to 20 carbon atoms is 0.05 to 10.

0.

3. A heat-curable epoxide composition comprising an epoxide compound having an average of more than one epoxy group in the molecule, and the latent curing agent of claim 1.

4. A cured product obtained by curing the heat-curable epoxide composition according to claim 3.

5. A coating comprising the heat-curable epoxide composition of claim 3.

6. An adhesive comprising the heat-curable epoxide composition of claim 3.

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