| 摘要 |
Mo-2698 PC-173 STABLE, AQUEOUS DISPERSIONS OF POLYURETHANE-UREAS The present invention is directed to a process for the preparation of aqueous polyurethane-urea dispersions with improved hydrolytic stability by a) forming an aqueous polyurethane-urea dispersion, optionally by chain extending an aqueously dispersed isocyanate-terminated prepolymer, containing carboxylic acid groups neutralized with volatile organic bases, b) converting the volatile, organic base-neutralized carboxylic acid groups to nonvolatile cationneutralized carboxylate groups by adding alkali metal salts of organic or inorganic acids having a pKa greater than 0 to the aqueous polyurethane-urea dispersion of (a) in an amount sufficient to displace at least a portion of the volatile organic bases and, optionally, c) removing the volatile organic bases by distillation, optionally under reduced pressure. The present invention is also directed to the products produced by this process. |
