| abstract |
This invention relates to a latex thickener which consists essentially of the free radical addition product obtained by the emulsion polymerization of: (a) 3-15 parts styrene; (b) 15-45 parts ethyl acrylate; (c) 30-60 parts of at least one acid having the formula: <IMAGE> wherein R1 and R2 can be the same or different and are hydrogen or lower alkyl of 1 to about 3 carbons; and (d) 10-25 parts of a mixture of esters; wherein the mixture of esters is the condensation reaction product of reactive amounts of (i) an ethylenically unsaturated cyclic carboxylic acid anhydride containing from 4 to about 8 carbon atoms; and (ii) an ethoxylated alcohol having the general formula: <IMAGE> wherein R is from one to three aliphatic radicals of 1 to about 30 carbon atoms each and n is an integer from about 6 to 150; and (iii) a diol containing from about 2 to about 10 carbon atoms. The novel thickeners of this invention are especially useful in increasing the high shear viscosity of latex coating compositions, and especially coating compositions which contain polymeric vesiculated beads as part of the pigmentation. |