Dow Global Technolgoies LLC

Rohm and Haas Company

Ian D Robertson

James Charles Bohling

Wei Gao

Justin Gimbal

The present invention relates to a composition comprising an aqueous dispersion of multiphase polymer particles comprising first polymer particles having a Tof less than 30° C. and second polymer particles having a Tin the range of from 100° C. to 110° C., wherein the second polymer particles are phase separated from and occluded within the first polymer particles; wherein the number average molecular weight (M) of the multiphase polymer particles is in the range of from 9,000 to 25,000 g/mole; and wherein the second polymer particles comprise at least 95 weight percent methyl methacrylate. The composition of the present invention is useful in a formulation that can be used to prepare a water-resistant blister free LASD coating with little or no surface defects.

Aqueous dispersion of occluded polymer particles

The present invention relates to a process for preparing an aqueous dispersion of multiphase occluded polymer particles comprising the steps of a) contacting, under emulsion polymerization conditions, first monomers and a chain transfer agent to form an aqueous dispersion of first polymer particles having a Tin the range of from −30° C. to 30° C.; then b) contacting the aqueous dispersion of first polymer particles with a second monomer under emulsion polymerization conditions to form an aqueous dispersion of second polymer particles occluded within the first polymer particles, wherein the first monomers a phosphorus acid monomer or a salt thereof; and the second monomer comprises at least 90 weight percent methyl methacrylate. The aqueous dispersion of occluded polymer particles arising from the process of the present invention is useful in a formulation that can be used to prepare a water-resistant blister free LASD coating.

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Collegeville, PA, United States of America

Ian D Robertson