METHOD OF PREPARING COATING HAVING IMPROVED YELLOWING RESISTANCE AND COATING OBTAINED THEREBY

摘要

PURPOSE: To obtain a coated substrate having improved resistance to yellowing by preparing a one-component coating composition comprising a specific blocked polyisocyanate and a compound containing at least two isocyanate-reactive groups. CONSTITUTION: This one-component coating composition is composed of a blocked polyisocyanate (a) which is a reaction product of a polyisocyanate with an oxime- or lactam-blocking agent for isocyanate groups and a compound (b) containing at least two isocyanate reactive groups, each component (a) and/or (b) of the composition containing a group--CO-(R)N-N(R)-CO-, (wherein R represents hydrogen or an optionally substituted hydrocarbon group) in an amount of 0.01-5% by weight based on solids content of each component. A desirable coating is formed by a laminated coating of the one-component coating composition over a coating composition containing acid groups and/or a melamine resins which has previously been applied to the substrate.