Associative copolymers with hydrophobic quaternized (meth)acrylamide and (meth)acrylic acid derivatives

A process for the preparation of a water-soluble copolymer comprising the step of

• reacting a monomer (a) of formula (I)
• wherein
• Q1 is O or NH;
• R1 and R2 are H;
• R3 is H or CH3;
• R5, R6 are independently selected from the group consisting of CH3 and C2H5;
• Q2 is an alkylene chain having 2 to 8 carbon atoms;
• R7 is a hydrocarbon radical having 10 to 14 carbon atoms;
• X is a counter ion having a negative charge;
• with at least one monoethylenically unsaturated, anionic monomer (b) selected from the group consisting of acrylic acid, methacrylic acid, itaconic acid, crotonic acid, maleic acid, fumaric acid, 2-acrylamido-2-methylpropane sulfonic acid, vinylsulfonic acid, vinylphosphonic acid, allylsulfonic acid, allylphosphonic acid and their salts thereof, preferably water-soluble salts of an alkali metal, alkaline-earth metal and ammonium;
• and
• at least one monoethylenically unsaturated, non-ionic monomer (c) selected from the group consisting of acrylamide, methacrylamide, N-isopropylacrylamide, N,N-dimethylacrylamide, N-methylolacrylamide, N-vinylformamide, N-vinyl acetamide, N-vinylpyridine and N-vinylpyrrolidone;
• wherein the reaction is carried out in the presence of at least a first additive, wherein the first additive is a sulfosuccinate of formula (II)
• wherein
• R8, R9 are independently a hydrocarbon radical having 4 to 20 carbon atoms;
• and
• Y is a counter ion with a positive charge and wherein the molar ratio of the at least first additive to monomer (a) is 1:10 to 10:1.