Latent hardener
A latent curing agent that can cure a thermosetting epoxy resin in a relatively short period of time and at a relatively low temperature has a structure in which an aluminum chelating agent is held by a porous resin carrier obtained through interfacial polymerization of a polyfunctional isocyanate compound. The aluminum chelating agent is preferably a complex compound comprising β-ketoenolate anion ligands coordinated to aluminum. The latent curing agent can be produced by dissolving the aluminum chelating agent and the polyfunctional isocyanate compound in a volatile organic solvent, adding the resulting solution to an aqueous phase containing a dispersing agent, and stirring the resulting mixture to cause interfacial polymerization of the isocyanate compound while the mixture is being heated.
1 . A latent curing agent comprising an aluminum chelating agent and a porous resin carrier for the aluminum chelating agent, the porous resin carrier being obtained through interfacial polymerization of a polyfunctional isocyanate compound.
2 . The latent curing agent according to claim 1 , wherein the aluminum chelating agent is a complex compound in which a β-ketoenolate anion ligand is coordinated to aluminum.
3 . The latent curing agent according to claim 1 , wherein the aluminum chelating agent is aluminum monoacetylacetonate bis(ethylacetoacetate).
4 . A method for producing the latent curing agent according to claim 1 , comprising:
dissolving an aluminum chelating agent and a polyfunctional isocyanate compound in a volatile organic solvent;
adding the resulting solution to an aqueous phase containing a dispersing agent; and
stirring the resulting mixture while the mixture is heated to cause interfacial polymerization of the isocyanate compound.
5 . The method according to claim 4 , wherein the volatile organic solvent is an acetic aced lower alkyl ester.
6 . The method according to claim 4 , wherein the aluminum chelating agent and the polyfunctional isocyanate compound are dissolved in the volatile organic solvent and the viscosity of the resulting solution is adjusted to in the range of 1 to 2.5 mPa.S.
7 . The method according to claim 6 , wherein the aluminum chelating agent is used in an amount of one-half or less by weight of the polyfunctional isocyanate compound.
8 . The method according to claim 4 , wherein the aluminum chelating agent is used in an amount of an equal amount or more by weight of the polyfunctional isocyanate compound.
9 . A thermosetting resin composition containing the latent curing agent according to claim 1 , a silane coupling agent, and a thermosetting resin.
10 . The thermosetting resin composition according to claim 9 , wherein the thermosetting resin is a thermosetting epoxy resin.
11 . The method according to claim 5 , wherein the aluminum chelating agent and the polyfunctional isocyanate compound are dissolved in the volatile organic solvent and the viscosity of the resulting solution is adjusted to in the range of 1 to 2.5 mPa.S.
12 . The method according to claim 5 , wherein the aluminum chelating agent is used in an amount of an equal amount or more by weight of the polyfunctional isocyanate compound.
13 . A thermosetting resin composition containing the latent curing agent according to claim 2 , a silane coupling agent, and a thermosetting resin.
14 . A thermosetting resin composition containing the latent curing agent according to claim 3 , a silane coupling agent, and a thermosetting resin.