Cantor Colburn LLP
Aqueous coating compositions having low or zero VOCs and comprising encapsulated or polymer adsorbed pigments and letdown binders
The present invention provides aqueous compositions useful as zero VOC coating compositions having a % opacifying pigment volume concentration (% OPVC) of from 2 to 25 and comprising (i) an opacifier composition of an at least partially polymer encapsulated opacifying pigment, a polymer opacifying pigment composite or their mixtures, with the opacifying pigment, encapsulated in and/or as a composite with at least one soft polymer having a measured glass transition temperature (measured Tg) of 5° C. or less, and (ii) a hard binder polymer having a measured Tg of at least 30° C. and a weight average particle size of 120 nm or less, wherein the ratio of the weight average particle size of the opacifier composition to that of the hard binder polymer is from 2:1 to 12:1 and the volume ratio of the opacifying pigment to the soft polymer solids in the opacifier composition is from 2:5 to 1:1.
Rohm and Haas Company
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Wenqin Ann R. Zhenwen
Wang Hermes Fu