Continuous process for the production of partially blocked isocyanates

摘要

A method for manufacturing partially blocked isocyanate curing agents in which a polyisocyanate and a blocking agent for the polyisocyanate are separately and continuously metered into a reaction zone in predetermined nonstoichiometric proportion under reaction conditions, and in which the reaction mixture is continuously withdrawn from the reaction zone to provide a partially blocked isocyanate curing agent product. The partially blocked isocyanate curing agent product may be continuously reacted with a polyhydroxy resin coating precursor at a temperature below the unblocking temperature of the blocking agent in respect of the polyisocyanate to provide a heat curable powder coating composition.