NOVEL CROSS-LINKING MECHANISM FOR THIN ORGANIC COATINGS BASED ON THE HANTZSCH DI-HYDROPYRIDINE SYNTHESIS REACTION

摘要

Disclosed is cross-linking process for cross-linking polymeric chains in a coating composition. In one embodiment the process utilizes a Hantzsch dihydropyridine reaction to form reaction products including cross-linking polymeric resin chains having beta-keto ester functions using a source of aldehyde and a source of ammonia or a primary amine to form a permanent dihydropyridine bond between the beta-keto ester functions. The novel cross-linking reaction can occur at lower temperatures compared to typical cross-linking reactions and can occur in aqueous solutions that have a neutral to mildly alkaline pH of from 6 to 11. The novel cross-linking reaction provides many advantages to performing cross-linking of polymeric chains in coating resins.

主权项

1. A coated metal substrate comprising:
a metal substrate coated with a dried in place coating composition comprising reaction products of a polymeric resin containing pendant beta-keto ester functions with an aldehyde and a source of either ammonia or a primary amine; wherein said polymeric resin comprises a plurality of polymeric chains and wherein each of said polymeric chains contains at least one of said pendant beta-keto ester functions; and wherein a portion of said polymeric chains are cross-linked to each other by a Hantzsch dihydropyridine reaction between two equivalents of said beta-keto ester functions, one equivalent of said aldehyde and one equivalent of said ammonia or said primary amine.