Patent ID: 8894816

Claim:
A process for making vinylamine-vinylformamide-styrene terpolymer additives comprising: a) reacting vinylformamide with styrene or substituted styrene under free radical, emulsion polymerization reaction conditions; b) producing a first polymer product which comprises randomly distributed repeating units by the formula (I) and (II): wherein Ar is an aromatic selected from the group consisting of phenyl and phenyl substituted with alkyl, alkoxy, sulfonate, halo and pyridine or substituted pyridine; R 1 is hydrogen or alkyl; x and y are numbers greater than zero mole percent, and the sum of x and y is 100 mole percent, the ratio of x:y is in the range of from 99:1 to 50:50; c) hydrolyzing the first polymer product with an acid or base treatment; d) producing a second polymer product comprising randomly distributed repeating monomer units having at least two of the formula (III), (IV), (V) and (VI): wherein, R 2 and R 3 are H; R 4 is H or alkyl; m 1 and m 2 independently is a positive mole percent, and m 3 and m 4 independently is 0 to 99 mole percent, and the sum of m 1 , m 2 , m 3 and m 4 is equal to or less than the x mole percent of formula (I).