Latent Curing Agent
An aluminum chelate-based latent curing agent, which can cure a thermosetting epoxy resin at a relatively low temperature in a short time, is made latent by reacting a silsesquioxane-type oxetane derivative with an aluminum chelating agent in the presence of an alicyclic epoxy compound, and then further reacting the resultant mixture with a liquid epoxy resin and an imidazole compound or with an aromatic vinyl compound and a radical polymerization initiator.
1 . An aluminum chelate-based latent curing agent being made latent by reacting a silsesquioxane-type oxetane derivative with an aluminum chelating agent in the presence of an alicyclic epoxy compound, and then further reacting the resultant mixture with a liquid epoxy resin and an imidazole compound or with an aromatic vinyl compound and a radical polymerization initiator.
2 . The aluminum chelate-based latent curing agent according to claim 1 , wherein the aluminum chelating agent is a complex compound having three β-ketoenolate negative ions coordinated to aluminum.
3 . The aluminum chelate-based latent curing agent according to claim 1 , wherein the aluminum chelating agent is aluminum ethylacetoacetate diisopropylate, aluminum trisethylacetoacetate, aluminum alkylacetoacetate diisopropylate, aluminum bisethylacetoacetate monoacetylacetonate or aluminum trisacetylacetonate.
4 . The aluminum chelate-based latent curing agent according to claim 1 , wherein the aluminum chelating agent is aluminum ethylacetoacetate diisopropylate.
5 . The aluminum chelate-based latent curing agent according to claim 1 , wherein the silsesquioxane-type oxetane derivative contains an oxetanylsilsesquioxane represented by the formula (1).
6 . The aluminum chelate-based latent curing agent according to claim 1 , wherein the alicyclic epoxy compound is 3′,4′-epoxycyclohexylmethyl 3,4-epoxycyclohexanecarboxylate.
7 . The aluminum chelate-based latent curing agent according to claim 1 , wherein the silsesquioxane-type oxetane derivative is contained in an amount of from 0.1 to 500 parts by weight with respect to 100 parts by weight of the aluminum chelating agent, and the alicyclic epoxy compound is contained in an amount of from 0.1 to 1,000 parts by weight with respect to 100 parts by weight of the sum of the aluminum chelating agent and the silsesquioxane-type oxetane derivative.
8 . The aluminum chelate-based latent curing agent according to claim 1 , wherein the liquid epoxy resin is contained in an amount of from 0.1 to 200 parts by weight with respect to 1 part by weight of the aluminum chelating agent, and the imidazole compound is contained in an amount of from 0.01 to 1 part by weight with respect to 1 part by weight of the liquid epoxy resin.
9 . The aluminum chelate-based latent curing agent according to claim 1 , wherein the aromatic vinyl compound is contained in an amount of from 0.1 to 200 parts by weight with respect to 1 part by weight of the aluminum chelating agent, and the radical polymerization initiator is contained in an amount of from 0.01 to 1 part by weight with respect to 1 part by weight of the aromatic vinyl compound.
10 . A method for producing an aluminum chelate-based latent curing agent, the method comprising:
reacting an aluminum chelating agent and a silsesquioxane-type oxetane derivative in the presence of an alicyclic epoxy compound in a non-aqueous solvent by heating; and
further reacting the resultant mixture with a liquid epoxy resin and an imidazole compound or with an aromatic vinyl compound and a radical polymerization initiator to obtain the aluminum chelate-based latent curing agent as a sediment.
11 . The production method according to claim 10 , wherein a heating temperature is in the range of from 80 to 200° C.
12 . The production method according to claim 10 , wherein the reaction is carried out under a nitrogen atmosphere.
13 . A thermosetting composition comprising the aluminum chelate-based latent curing agent according to claim 1 , a silane coupling agent and a thermosetting compound.
14 . The thermosetting composition according to claim 13 , wherein the thermosetting compound is an alicyclic epoxy compound.
15 . The thermosetting composition according to claim 13 , wherein the thermosetting compound is an oxetane compound.
16 . The thermosetting composition according to claim 13 , wherein the silane coupling agent is an oxetane-type silane coupling agent and/or an alicyclic epoxy-type silane coupling agent.
17 . The thermosetting composition according to claim 16 , wherein the oxetane-type silane coupling agent is an oxetanyl silane compound represented by the formula (2).
18 . The thermosetting composition according to claim 16 , wherein the alicyclic epoxy-type silane coupling agent is 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane represented by the formula (3).
19 . An anisotropic conductive composition comprising conductive particles dispersed in the thermosetting composition according to claim 13 .