ONE-COMPONENT COATING COMPOSITION CONTAINING OXIME-OR LACTAM-BLOCKED POLYISOCYANATE AND HAVING IMPROVED RESISTANCE TO YELLOWING

摘要

PURPOSE: To provide a one-component polyurethane coating composition which has improved resistance to yellowing and little deteriorates in other important properties when applied in the presence of an acid and/or a melamine resin. ;CONSTITUTION: There is provided a blocked polyisocyanate which is the reaction product of a polyisocyanate with (i) 60-99.9 equivalent %, based on the equivalents of isocyanate groups of the polyisocyanate prior to blocking, of an oxide or lactam blocking agent for isocyanate groups and (ii) 0.1-40 equivalent %, based on the equivalents of isocyanate groups of the polyisocyanate prior to blocking, of hydrazine and/or a compound which is soluble in either the polyisocyanate, the blocking agent or an optional organic solvent for the polyisocyanate and contains the group, H(R)-N-NR-CO- (the carbonyl group is bound to carbon or nitrogen and R is hydrogen or an optionally substituted hydrocarbon radical).;COPYRIGHT: (C)1994,JPO