Acrylic latex binder and method of preparation

摘要

The present invention relates to a process comprising contacting methyl methacrylate or styrene; a C1-C10-alkyl acrylate; and a polymerizable carboxylic acid monomer with a stable aqueous dispersion of first polymer particles, under emulsion polymerization conditions, to form a stable aqueous dispersion of second polymer particles. The first polymer particles have a Tg in the range of from −30° C. to 30° C., and the monomers have a calculated Tg in the range of 50° C. to 120° C. The present invention also relates to the dispersion of second polymer particles, which is useful as a binder to improve freeze-thaw stability in a coatings formulation.

主权项

1. A method comprising the step of contacting monomers with a stable aqueous dispersion of first polymer particles under emulsion polymerization conditions to form a stable aqueous dispersion of second polymer particles, wherein:
a) the first polymer particles comprise structural units of methyl methacrylate or styrene or a combination thereof; and a C1-C10-alkyl acrylate; and have a Tg in the range of from −30° C. to 30° C.; b) the monomers comprise methyl methacrylate or styrene or a combination thereof, a polymerizable carboxylic acid monomer, and a sufficient amount of C1-C10-alkyl acrylate to achieve a calculated Tg in the range of 50° C. to 120° C.; c) the concentration of the polymerizable carboxylic acid monomer is from 2 to 10 weight percent, based on the weight of the monomers; and d) the weight-to-weight ratio of the monomers to the first polymer particles is in the range of 1:99 to 8:92.