| 摘要 |
1488450 Polyureas BAYERAG 23 May 1975 [26 July 1974] 22705/75 Heading C3R A polyamide-urea of polyamide-urea-urethane which contains free carboxyl groups on the main chain is prepared by reacting an organic polyisocyanate, preferably a difunctional NCO-terminated prepolymer of M.Wt. 400-10,000, with a primary and/or secondary diamine, in the presence of a tetracarboxylic acid dianhydride and optionally a solvent, preferably acetone. The products may be rendered water-dispersible by forming salts from the free carboxyl groups by at least partial neutralization with an organic or inorganic base. Suitable primary and secondary diamines have the formula (R) n (NHR<SP>1</SP>) 2 where R represents a divalent C 2 -C 18 aliphatic hydrocarbon radical, C 6 -C 15 aromatic hydrocarbon radical, C 5 -C 15 cycloaliphatic hydrocarbon radical or C 8 -C 18 araliphatic hydrocarbon radical, R<SP>1</SP> represents hydrogen or a C 1 -C 4 aliphatic hydrocarbon radical and n is 0 or 1. The preferred dianhydrides are pyromellitic acid dianhydride and benzophenone tetracarboxylic acid dianhydride. Other suitable dianhydrides are listed. In the examples polyamide-urea-urethanes are prepared by reacting (A) an NCO-terminated prepolymer prepared by reacting either hexamethylene diisocyanate or 2,2,4-trimethylhexamethylenediisocyanate with an adipic acidhexanediol-neopentyl glycol polyester of M.Wt. 2000, with (B) pyromellitic acid dianhydride in acetone and then with (c) either ethylene diamine or 2,2-(bis-cyclohexylamine) propane. Aqueous KOH is then added and the resulting aqueous dispersion is partially or completely freed from acetone. Films are made from the dispersions.
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