| abstract |
The present invention relates to a water-soluble crosslinked copolymer having a molecular weight ≤ 500,000, wherein the sulfonic acid or sulfonate group-containing monomer unit a) 20 to 95 wt%, the N-methylol or N-alkoxymethyl group-containing monomer unit b) 4-8 wt% C) 0.1-20 wt% of the hydrophobic monomer unit selected from the group consisting of a water-insoluble ethylenically unsaturated compound and a hydrophobic end group of the initiator radical or the modulator molecule (the content of wt% is based on the total weight of the polymer). do.n n n The content of the sulfonic acid or sulfonate group-containing monomer unit can be selectively substituted by a carboxyl group-containing monomer unit d) or an amide group-containing monomer unit e) up to 50 wt% based on the total weight of the monomer unit a). |