Synergistic mixture of polyurethane and emulsion polymers useful as thickeners for aqueous systems

Claim 1

A thickening composition comprising (a) a syneresis reducing amount of a liquid emulsion polymer comprising the copolymerization product of (i) about 15 to about 60 weight percent of an addition polymerizable acid monomer which is represented by the formula: ##STR7## where R is H and R' is H, C 1 -C 4 alkyl, or --CH 2 COOX; R is --COOX and R' is H or --CH 2 COOX; or R is CH 3 and R' is H; and X is H or C 1 -C 4 alkyl, (ii) about 15 to about 80 weight percent of an addition polymerizable nonionic vinyl monomer which is represented by the formula: CH.sub.2 ═CYZ (II) where Y is H and Z is --COOR, --C 6 H 4 R', CN, Cl, ##STR8## Y is CH 3 and Z is --COOR, --C 6 H 4 R', CN or --CH═CH 2 ; or Y and Z are Cl; and R is C 1 -C 8 alkyl or C 2 -C 8 hydroxyalkyl; R' is H, Cl, Br, or C 1 -C 4 alkyl; R" is C 1 -C 8 alkyl, and (iii) about 1 to about 30 weight percent of a nonionic vinyl surfactant ester which is represented by the formula: ##STR9## where R is H or CH 3 ; each R' is C 1 -C 2 alkyl; R" is C 8 -C 20 alkyl or C 8 -C 16 alkylphenyl; n is an average number from about 6-100 and m is an average number from about 0-50 provided that n≧m and Σ(n+m) is about 6-100; and (b) a thickening amount of a urethane polymer having at least three hydrophobic groups, at least two of which are terminal hydrophobic groups, said hydrophobic groups being linked by hydrophilic groups.