| 摘要 |
Stable dispersions of polyureas and/or polyhydrazodicarboxamides in hydroxyl-containing compounds are obtained by reacting 1) organic polyisocyanates with 2) primary and/or secondary amino group-containing polyamines and/or hydrazines and/or hydrazides, in 3) compounds containing at least one hydroxyl group as dispersants, where components 1, 2 and 3 are fed continuously to a through-flow mixer in such an amount that the mean residence time in the mixing unit is less than 10 minutes and the equivalent ratio of components 1 and 2 is between 0.8 and 1.05, and where either all three components separately or component 1 and combined components 2 and 3 are fed to the through-flow mixer, and where the reaction product leaving the through-flow mixer is subsequently collected in a receiver, if component 3 contains hydroxyl-containing polyesters, polyester-amides and/or polycarbonates having a molecular weight of between 400 and 16 000 and/or polyols having a molecular weight of between 62 and 400 and optionally additionally hydroxyl-containing, relatively high-molecular-weight polyethers. The dispersions of polyisocyanate polyaddition products in hydroxyl-containing dispersants which are accessible according to the invention can be used, for example, for the preparation of polyurethane plastics, in particular foams, having improved mechanical properties. |
