Patent ID: 8623791

Claim:
A copolymer consisting of: an A monomer; a B monomer; and a C monomer, wherein: the A monomer is an acrylamide; the B monomer is an acrylic acid B1 monomer; and the C monomer is an alkyl sulfonate C2 monomer containing acryloxy group: wherein M is Na + or K + , R is H or CH 3 , and n=0, 1 or 2, wherein the structure of the copolymer is represented by general formula 1, (A+B1+C2): wherein a represents the quantity of the A monomer, b represents the quantity of the B monomer, c represents the quantity of the C2 monomer, and the ratio of (a:b:c) is in the range of (2-8):1:(0.5-5.0), wherein in C2 monomer R being H and n=0 do not occur simultaneously; and wherein the relative molecular weight of the copolymer is from 500,000 to 700,000.