| 摘要 |
The present invention relates to polyisocyanate adducts containing allophanate groups, siloxane groups and optionally isocyanurate groups that are prepared by reacting compounds a) which i) are substantially free of hydroxyl groups and isocyanate groups, ii) have average of at lest two urethane groups per molecule and iii) contain 0 to 50 percent by weight of the polyisocyanate adducts, with an excess quantly, based on the equivalents of urethane groups, of polyisocyanates b), which optionally contain siloxane groups, to form polyisocyanate adducts and optionally removing at least a portion of the unreacted excess polyisocyanates b), provided that compounds a) and polyisocyanates b) contain a total of at least 0.001 percent by weight, of siloxane groups, based on the weight of the polyisocyanate adducts. The present invention also relates to a process for preparing these polyisocyanates adducts, to blends of the polyisocyanates with other polyisocyanates that which do not contain siloxane groups and to the use of the polyisocyanate adducts or polyisocyanate blends, optionally in blocked form, in one or two-component coating compositions.
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