Patent ID: 9062233
Filing Date: 2015-06-23
Classification: B32B,C08F,C08L,C09J,Y10T

Abstract:
1. A process for preparing an aqueous polymer dispersion, the process comprising: preparing a first polymer dispersed in water by free-radical emulsion polymerization in an aqueous medium from a first composition comprising an ethylenically unsaturated, free-radically polymerizable monomer; and subsequently preparing a polymer dispersion in aqueous medium and in the presence of the first polymer by free-radical emulsion polymerization of a second composition, which is different from the first composition and comprises an ethylenically unsaturated, free-radically polymerizable monomer, wherein: the monomer in the preparing of the first polymer comprises a monomer comprising an acid group, said monomer being present in an amount of at least 0.1 part by weight, based on a total amount of monomers in preparing the polymer dispersion; the preparing of the first polymer occurs at a pH less than 5; and the preparing of the polymer dispersion further comprises neutralizing acid groups of the first polymer to an extent such that a pH of the polymer dispersion is greater than 5, wherein the neutralizing comprises feed addition of a neutralizing agent while preparing the polymer dispersion, and the neutralization is performed simultaneously with the polymerization of the second composition.