| 摘要 |
A process for preparing polyisocyanate prepolymers containing allophanate structural units and prepolymers prepared thereby. The process includes the steps of reacting a) one or more aliphatic and/or cycloaliphatic polyisocyanates with b) one or more polyhydroxy compounds to give an NCO-functional polyurethane prepolymer, whose resultant urethane groups are fully or partly allophanatized; reacting the prepolymer with c) polyisocyanates, which may be different from those of a), and using d) zinc(II) compounds as catalysts. The prepolymers can be used to produce coatings, adhesive bonds and/or seals. The coatings can include A) one or more of the prepolymers and B) at least one diol or polyol and/or C) at least one linear and/or cyclic, aliphatic, araliphatic and/or aromatic diamine or polyamine. The coatings can be used to coat substrates.
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