Cosmetic composition containing a cationic polyester and an acrylic terpolymer as well as application of that composition in treating creatinic substances

A cosmetic composition for treating keratinous materials, especially hair, comprises a cationic polymer and an acrylic terpolymer in an aqueous medium. The terpolymer comprises: (1) a carboxylic acid (A) with alpha , beta -monoethylenic unsaturation (20-70, preferably 25-55, wt. %); (2) a monomer (B) with non-surfactant monoethylenic unsaturation other than (A) (20-80, preferably 30-65, wt. %); and (3) a non-ionic urethane monomer (C) prepared by reacting a monohydric non-ionic surfactant with a monoisocyanate with monoethylenic unsaturation (0.5-60, preferably 10-50, wt. %).