Coatings having improved resistance to stains and dirt

摘要

The present invention relates to an aqueous coating composition based on a specific aqueous polymer dispersion as binder, having increased resistance to domestic stains and dirt without specialist functional monomers. Said aqueous polymer dispersion having an MFFT between 0 and 50 °C, comprises polymer particles obtained by emulsion polymerisation in at least two steps with at least two polymer phases P1 and P2, where P1 represents 75 to 90% by weight of P1+P2 having a Fox Tg1 from 0 to 40 °C and P2 having a Fox Tg2 from 0 to 40°C, said polymer P2 representing 10 to 25% by weight of the sum of the two polymers P1 and P2 and having a calculated Hansch parameter 2.0, and at least one ethylenically unsaturated monomer bearing an acetoacetoxy and/or amine or ureido functional group, said acetoacetoxy and/or amine or ureido functional group being borne by the external surface of the P2 phase. The invention also relates to said aqueous dispersion used as a binder, a method for preparing said dispersion and uses of said composition and dispersion for coatings that are resistant to stains and dirt.