| 摘要 |
Polyisocyanates (A) with uretdione groups having mean isocyanate functionality of at least 2.0, optionally other diisocyanates and/or polyisocyanates (B) (70 wt.% or less), polyol(s) (C) and optionally other isocyanate-reactive monofunctional compounds (D) (40 wt.% or less) are reacted in the presence of at least one bismuth-containing catalyst to form polyaddition products containing uretdione groups. Polyols have molecular weight of 62-2000 and mean functionality of at least 2.0. The equivalent ratio of isocyanate groups to isocyanate-reactive groups is 1.8:1-0.6:1. Independent claims are included for the following: (1) polyaddition products containing uretdione groups; and (2) powder coating which has a matt surface prepared from the above-mentioned polyaddition products containing uretdione groups in combination with at least one polyol having hydroxyl number of 20-40 mgKOH/g and at least one polyol having hydroxyl number of 200-300 mgKOH/g. |
