| 摘要 |
<p>A process for the preparation of foam-stabilising aqueous polyurethane-polyurea dispersions is disclosed, in which (A) first a polyurethane prepolymer containing NCO groups - having an NCO functionality of less than two - is produced by reacting (A1) polyisocyanates with (A2) polymeric polyols and/or polyamines having number average molecular weights of 400 to 8000 g/mol, (A3) isocyanate-reactive, non-ionically hydrophilising compounds which are polyoxyalkylene ethers which contain at least one hydroxyl or amino group, and(A4) isocyanate-reactive compounds containing at least one acyclic C7-24 alkyl or C7-24 alkenyl group, and(B) the still free NCO groups of the prepolymer are reacted with a compound (A8), which is selected from the group consisting of isocyanate-reactive amino alcohols, monoamines, polyamines, hydrazine, hydrazides and mixtures thereof, in an amount such that a theoretical ratio of the isocyanate-reactive NH groups of the compound (A8) to the NCO groups of the prepolymer from 0.8 to 1.2 is achieved. Aqueous foam-stabilising polyurethane-polyurea dispersions obtained by said process is used for the production of foams by mechanical expansion, the foams being used for the production of foam coatings, which are suitable for coating on substrates such as leather or imitation leather, full-grain or buffed leather and split leather.</p> |
