Microcapsule-type latent curing agent
An aluminum chelate-based latent curing agent having excellent latency and thermal response includes a latent curing agent in which an aluminum chelating agent is retained in a porous resin obtained by interfacial polymerization of a polyfunctional isocyanate compound, and an enzyme-treated gelatin film coating such latent curing agent. This microcapsule-type latent curing agent can be produced by dissolving an aluminum chelating agent and a polyfunctional isocyanate compound in a volatile organic solvent, charging the obtained solution into a gelatin-containing aqueous phase, carrying out interfacial polymerization by heating and stirring, and subjecting the gelatin to an enzyme treatment by adding an enzyme to the obtained polymerization reaction mixture.
1. A microcapsule-type latent curing agent comprising:
a latent curing agent in which an aluminum chelating agent is retained in a porous resin obtained by interfacial polymerization of a polyfunctional isocyanate compound; and
an enzyme-treated gelatin film coating the latent curing agent;
wherein:
the enzyme-treated gelatin film has a thickness of from 1 to 1000 nm;
the enzyme-treated gelatin film is formed of a gelatin obtained by subjecting a gelatin which exhibits a jelly strength according to JIS K6503-2001 of 10 to 200 to an enzyme treatment; and
the enzyme-treated gelatin film has surface irregularities that were formed by the enzyme treatment.
2. The microcapsule-type latent curing agent according to claim 1 , wherein the aluminum chelating agent is a complex compound in which a β-ketoenolate anion to serve as a ligand is coordinated to aluminum.
3. The microcapsule-type latent curing agent according to claim 1 , wherein the aluminum chelating agent is aluminum monoacetylacetonate bis(ethylacetoacetate).
4. The microcapsule-type latent curing agent according to claim 1 , wherein the enzyme-treated gelatin film contains a polyvinyl alcohol.
5. The microcapsule-type latent curing agent according to claim 1 , wherein the gelatin has a weight average molecular weight of 1000 to 110000.
6. A method for producing the microcapsule-type latent curing agent as set forth in claim 1 , the method comprising:
dissolving the aluminum chelating agent and the polyfunctional isocyanate compound in a volatile organic solvent;
charging the obtained solution into a gelatin-containing aqueous phase;
carrying out interfacial polymerization by heating and stirring; and
subjecting the gelatin to the enzyme treatment to form the enzyme-treated gelatin film having surface irregularities by adding an enzyme to the obtained polymerization reaction mixture.
7. The method according to claim 6 , wherein the aqueous phase contains polyvinyl alcohol.
8. The method according to claim 6 , wherein the volatile organic solvent is lower alkyl acetate.
9. A thermosetting resin composition comprising the microcapsule-type latent curing agent as set forth in 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.