Redox polymers for improved dirt and water resistance for elastomeric wall and roof coatings

An aqueous composition for coating roofing substrates comprise (i) one or more emulsion copolymer having a glass transition temperature (Tg) of from −45° C. to −10° C. having a weight average molecular weight of from 100,000 to 2,000,000, the emulsion copolymer being the copolymerization product of a monomer mixture of (a) from 74 wt. % to 97.75 wt. % of one or more C4 to C6 alkyl(meth)acrylates or a mixture thereof with up to 20 wt. % of a C7 to C24 alkyl(meth)acrylate to make a total of 80 to 94 wt. %, (b) from 2 to 20 wt. % of a hard vinyl monomer, and (c) from 0.25 wt. % to 3.0 wt. % of one or more ethylenically unsaturated monofunctional carboxylic acid group containing monomer, (ii) a reductant, (iii) a combination of one or more of a pigment, extender, filler and mixtures thereof with one or more hydrophilic polymeric dispersant in a total amount so that the composition has a pigment volume concentration (% PVC) of from 20 to 55, and (iv) one or more multivalent transition is metal ion or multivalent transition metal ion compound or salt, wherein the monomer mixture comprises 10 wt. % or less of any vinyl aromatic monomer;

• and, further wherein, the monomer mixture comprises 11 wt. % or less of (meth)acrylonitrile, all monomer wt. % s based on the total solids in the monomer mixture.