Patent ID: 7074850

Claim:
A polyurethane block copolymer of the general formulae I to IV where: A is a polyurethane block containing at least one hydrophilic end group X 1 which is terminated by OH, SH, NH2 or NHR, where R is selected from C 1 â€“C 12 -alkyl or C 6 â€“C 14 -aryl, B is a hydrophobic polyurethane block from which hydrophilic end groups X 1 are absent, X 1 and X 2 are each a hydrophilic end group, X 1 being a carboxyl group or being an SO3 group introduced by incorporation of a sulfo-containing diol, each X 2 being the same or different and being selected from the group consisting of â€”OH, O(CH 2 â€”CH 2 â€”O) x â€”H, â€”O(â€”CHCH 3 â€”CH 2 â€”O) x â€”H, â€”O(â€”CH 2 â€”CHCH 3 â€”O) x â€”H, and â€”O(â€”CH 2 â€”CH 2 â€”CH 2 â€”CH 2 â€”O) x â€”H, where x is an integer from 1 to 20, and n is an integer from 1 to 20.