Patent ID: 7214737

Claim:
An aqueous polymer dispersion prepared from a monomer composition comprising: (A) 50 to 99.99 parts by weight of at least one acrylic or methacrylic ester derived from acrylic or methacrylic acid and from an alcohol having 1 to 12 carbon atoms; (B) 0 to 40 parts by weight of at least one vinylaromatic monomer; (C) 0 to 5 parts by weight of at least one of acrylic acid, methacrylic acid, itaconic acid, crotonic acid, maleic acid, fumaric acid or vinylbenzoic acid; and (D) 0.01 to 5 parts by weight of at least one α, β-ethylenically unsaturated monomer compound (D) comprising at least one carbonyl group having at least one hydrogen atom carried by a carbon atom in the α position with respect to said carbonyl, the compound or compounds (D) being diacetone acrylamide, diacetone methacrylamide, 2-butanone (meth)acrylate, vinyl acetoacetate or acetoacetoxy-ethyl(meth)acrylate, per 100 parts by weight of the monomers (A)+(B)+(C)+(D); (G) 0.5 to 5 parts by weight of at least one anionic surface-active agent; and (H) 0.2 to 5 parts by weight of at least one non-ionic surface-active agent, the amounts (G) and (H) being calculated on the basis of the solid or dry matter and being expressed with respect to 100 parts by weight of the monomers (A)+(B)+(C)+(D), in the overall composition used in the final latex, and 80 to 98% by weight of the monomer components having been added to a reaction medium already comprising a completely or partially polymerized pre-emulsion representing from 2 to 20% by weight of the final overall level of the monomer components in the dispersion finally obtained, characterized in that, at the complete or partial polymerization stage, at least one nonionic surfactant (H) is combined with at least one anionic surfactant (G).