NOVEL BLOCKED POLYISOCYANATE AND USES THEREOF

摘要

A novel blocked polyisocyanate prepared by reacting at least one diisocyanate selected from among aliphatic diisocyanates and alicyclic diisocyanates with a polyhydroxy compound having 4.5 to 10 hydroxyl groups on average, removing unreacted diisocyanate from the reaction mixture substantially completely to prepare a non-blocked polyisocyanate, and blocking the terminal isocyanate groups of the non-blocked polyisocyanate with a thermally dissociating blocking agent. A coating composition comprising a polyol as the main component and the blocked polyisocyanate as the curing agent is excellent in low-temperature curing properties and can give coating films having high impact resistance. Further, the blocked polyisocyanate is excellent in compatibility with plasticizers, so that an adhesion-improving composition comprising the blocked polyisocyanate and a plasticizer and/or a solvent can give a plastisol composition excellent in low-temperature adhesion when combined with a plastisol.