WÄSSRIGE POLYURETHANZUBEREITUNGEN

摘要

Aqueous polyurethane preparations which contain from 10 to 60% by weight of at least one polyurethane A which is built up from a) at least one organic diisocyanate or a mixture of organic isocyanates which has an arithmetic mean NCO functionality of from 1.9 to 2.3 [monomers I], b) at least one dihydric polyether alcohol having a number average molecular weight of from 500 to 5000 or a mixture of polyether alcohols having a number average molecular weight of from 500 to 5000 and having an arithmetic mean functionality of alcoholic OH groups of from 1.6 to 2.3 [monomers II], c) at least one alcohol containing 1 to 3 alcoholic OH groups and at least one ionogenic group [monomers III], d) no, one or more dihydric alcohols having a number average molecular weight of from 62 to 499 or a mixture of alcohols having a number average molecular weight of from 62 to 499 and having an arithmetic mean functionality of alcoholic OH groups of from 1.9 to 2.3 [monomers IV], e) no, one or more monohydric polyether alcohols [monomers V], and f) no, one or more polyamines containing at least two <2bL>N-H groups [monomers VI], with the proviso that the amounts of incorporated monomers I to VI are such that the OH/NCO equivalent ratio for the incorporated monomers II/monomers I is from 0.2 to 0.6, for the monomers III/monomers I is from 0.2 to 0.8, for the monomers IV/monomers I is from 0 to 0.2, and for the monomers V/monomers I is from 0 to 0.2, and the -N-H/NCO equivalent ratio of the incorporated monomers VI/monomers I is from 0 to 0.1, that the arithmetic mean functionality of all the incorporated monomers I to monomers V, determined via the sum of the NCO groups of the monomers I and the alcoholic OH groups of the monomers II to monomers V, is from 1.8 to 2.3, that the NCO/(OH + <2bL>N-H) equivalent ratio for the incorporated monomers I, the OH groups of the incorporated monomers II to monomers V and the <2bL>N-H groups of the incorporated monomers VI is from 0.9 to 1.0 and, in the case of the additional incorporation of monomers VI, the NCO/OH equivalent ratio for the incorporated monomers I and the sum of the incorporated monomers II to monomers V is at the same time greater than 1, that the monomers II have a degree of ethoxylation of less than 30% by weight, that the monomers V have a degree of ethoxylation of at least 40% by weight, and that from 0.05 to 2 mmol of the ionogenic groups of the incorporated monomers III per gram of polyurethane A in the aqueous preparation are in ionised form. These aqueous polyurethane preparations are suitable as primers (bottom coats) for finishes (dressings) on greased (oiled) and/or waterproofed leathers.