| 摘要 |
<p>A linear crystalline polyuretedione which has a structure represented by general formula (1), wherein Y represents the group (a), X represents (b), (c) or -NCO; R1 represents R2 or (d); R2 represents a residue formed by removing two hydroxyl groups from a diol; R3 represents a residue formed by removing an active hydrogen atom from an active hydrogen compound; R4 represents a residue formed by removing two NCO groups from a diisocyanate; and n is 1 or above, provided 0-15 % of Ys are replaced by a triazine ring represented by formula (e). It has a latent NCO content of 12-21 wt.%, a weight-average molecular weight of 2,000 to 20,000 and a melting point of 60-140 °C, and does not cause blocking at a temperature of 40 °C or below. It can be used as a curing agent for powder coating material and does not emit disagreeable odor of the blocking agent in the step of baking the coating. A powder coating composition containing this polymer gives a coating film with excellent surface smoothness, weathering resistance and mechanical properties.</p> |
