Patent ID: 7129320

Claim:
A polymeric phosphinic acid or its salt of the formula (I) where X is 1/m of a metal of valency m, R 1 and R 2 are identical or different and are hydrogen, a carboxy group, a carboxylic acid derivative, an unsubstituted or substituted alkyl group having from 1 to 10 carbon atoms, phenyl, benzyl, or alkyl-substituted aromatic systems, R 3 and R 4 may be identical or different and are an unsubstituted or substituted alkyl group having from 2 to 20 carbon atoms, an OH group or are OX, with the above meaning for X, and ū is from 2 to 1000, and wherein X is a metal of groups IIA, IIIA, IVA, VA, IIB, IVB, VIIB, VIIIB of the Periodic Table of the Elements, or is cerium.