Graft copolymers of unsaturated monomers and polyhydroxy compounds, a process for their production and their use

A process for producing a graft copolymer comprising polymerizing a mixture of monoethylenically unsaturated monomers at a temperature of up to 200.degree. C. in the presence of a radical polymerization initiator and from 1 to 60%-wt. of at least one polyhydroxy compound, reaction product thereof, or derivative thereof, based on the total weight of monoethylenically unsaturated monomer and polyhydroxy compound, reaction product thereof or derivative thereof, wherein the monoethylenically unsaturated monomer mixture consists of

• A) 45-96%-wt. of at least one monoethylenically unsaturated C.sub.3 -C.sub.10 monocarboxylic acid or salt thereof with a monovalent cation,
• B) 4-55%-wt. of at least one monoethylenically unsaturated monomer containing sulfonic acid groups, one monoethylenically unsaturated sulfuric acid ester and/or vinyl phosphonic acid and/or the salts of these acids with monovalent cations,
• C) 0-30%-wt. of at least one water-soluble, monoethylenically unsaturated compound modified with 2-50 moles of alkylene oxide per mole,
• D) 0-45%-wt. of at least one additional water-soluble, radically polymerizable monomer,
• E) 0-30%-wt. of other radically polymerizable monomers which are slightly soluble or insoluble in water, with the sum of A) through E) totaling 100%-wt. of the ethylenically unsaturated monomer mixture.

A method of binding multivalent metal ions comprising contacting a solution containing said ions with a graft copolymer obtained by radical graft copolymerization of a monomer mixture consisting of:

• A) 45-96%-wt. of at least one monoethylenically unsaturated C.sub.3 -C.sub.10 monocarboxylic acid or salt thereof with a monovalent cation;
• B) 4-55%-wt. of at least one monoethylenically unsaturated, sulfonic acid group-containing monomer, one monoethylenically unsaturated sulfuric acid ester, vinylphosphonic acid or salt thereof with a monovalent cation;
• C) 0-30%-wt. of at least one water-soluble, monoethylenically unsaturated compound modified with 2-50 moles of alkylene oxide per mole;
• D) 0-45%-wt. of at least one further water-soluble, radically polymerizable monomer;
• E) 0-30%-wt. of at least one other radically polymerizable monomer which is slightly soluble or insoluble in water;
• with the sum of A) to E) equalling 100%-wt., in the presence of at least one polyhydroxy compound, reaction product thereof, derivative thereof or mixture thereof, wherein the content of said at least one polyhydroxy compound, reaction product thereof, derivative thereof or mixture thereof amounts to 1 to 60%-wt. of the total mixture.