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AssigneeRohm and Haas Company
InventorsJoseph M. Rokowski, Adam W. Freeman, Ann E. Evans, Stephen A. Crescimanno
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The present invention provides aqueous coating compositions comprising one or more emulsion copolymer made from itaconic acid, a sulfonic acid or sulfonate ester monomer and an additional acid monomer which is a carboxylic acid and having a glass transition temperature of from −45° C. to −10° C., and one or more pigment, opacifier, filler, extender, or mixture of any of these at a % PVC of from 20 to 55, preferably 30 to 50, wherein coatings made from the coating compositions provide improved resistance to water swelling and dirt pickup resistance. The improvements are observed regardless of whether the compositions contain or are substantially free of zinc or divalent metal ions, or salts or compounds containing them. The present invention also provides roofing substrates coated with the aqueous compositions.
An aqueous composition for coating roofing substrates comprising (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 1,000,000 and a weight average particle size of from 80 to 500 nm, the emulsion copolymer comprising the copolymerization product of a monomer mixture of (a) from 65 wt. % to 94 wt. % of one or more C4 to C24 alkyl(meth)acrylates or a mixture of one or more C8 to C24 alkyl(meth)acrylates with butyl acrylate (BA), (b) from 8 to 34.65 wt. % of a hard vinyl monomer, (c) from 0.25 wt. % to 1.6 wt. % of itaconic acid (IA), and (d) 0.1 to 2.25 wt. % of one or more additional acid monomer chosen from an ethylenically unsaturated carboxylic acid group containing monomer, and a sulfur acid monomer, such that the total amount of monomers c) and d) is 2.5 wt. % or less, all monomer wt. % s based on the total solids in the monomer mixture;
Dependencies are inferred from the claim text.