Acrylamide containing emulsion copolymers for thickening purposes
 There are disclosed stable, aqueous dispersions of water-insoluble emulsion copolymers of (1) about 10-70% by weight of methacrylic or acrylic acid, (2) about 0.5-25% by weight of an N-alkyl acrylamide, and (3) at least 25% by weight, to a total of 100%, of a C.sub.1 -C.sub.4 alkyl (meth)acrylate, and, optionally, included in the total monomer mixture a small amount of (4) about 0.05-1% by weight of a polyethylenically unsaturated monomer. The emulsion copolymers, when neutralized and solubilized by addition of an alkali, are high efficiency thickeners for aqueous systems and have improved tolerance to ionic or electrolyte content. Typical systems that can be thickened are paint latices, cosmetic preparations, food preparations, ionic detergents, dye pastes for textiles, pharmaceuticals, and oil well drilling muds. Surfactants enhance the thickening properties afforded by the copolymers. 
Rohm and Haas Company
A A C C C D C C A A A C G C A
A61K A61Q C08F C11D C09K D06P C09D C08F A61K A61K A61K C08L G02B C09K A61Q
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Travis E. Ching-Jen
Stevens Chang