Thermosetting polyurethane resin and coating agent thereof prepared from at least two polyoxyalkylene polyols, blocking agent, chain-elongating agent, cross-linking agent and a mixture of diisocyanates

摘要

A thermosetting polyurethane resin which when used as a one-pack surface-protective coating agent for glass bottles, inorganic vessels, and the like exhibits excellent mechanical strength, appearance, and water resistance at sterilization temperatures of about 90 DEG C. is obtained by interacting: (a) 10 to 40% by weight of at least two polyoxyalkylene polyols based on the weight of the nonvolatile matter of the thermosetting polyurethane resin, said at least two polyoxyalkylene polyols including 1 to 8% by weight relative to the nonvolatile matter of the thermosetting polyurethane resin of a nonionic surface active agent selected from the group consisting of a polyoxyethylene glycol or a polyoxyethylene-polyoxypropylene glycol, and mixtures thereof, (b) a monofunctional isocyanate-blocking agent, (c) a chain-elongating agent, (d) a cross-linking agent, and (e) a mixture of methylene-bis (4-cyclohexylisocyanate) and iso-phorone diisocyanate at a molar ratio in the range of from 1:0.3 to 1:1.5.