CURING AGENT FOR POLYURETHANE COATING MATERIAL AND METHOD FOR PRODUCING SAME

摘要

A method for producing a curing agent for polyurethane coating materials which is composed of an aliphatic diisocyanate or an aliphatic diisocyanate and a polyester polyol is characterized in that a copolymerized lactone polyol is used as the polyester polyol which lactone polyol is obtained through ring-opening copolymerization of at least two kinds of cyclic lactone compounds wherein a low-molecular-weight compound having at least two active hydrogen groups is used as an initiator. By using at least two kinds of cyclic lactone compounds, there can be obtained a curing agent for polyurethane coating materials which enables to form a coating film having high mechanical strength, especially high flexibility and impact resistance at low temperatures, and excellent gloss retention.