Patent ID: 6620880
Filing Date: 2003-09-16
Classification: C08F,C09D,Y10S

Abstract:
A process for making an environmentally friendly aqueous architectural coating composition comprising the steps of:a) lightly oxidizing a starch by converting some of its hydroxyl groups to carboxylic acid groups optionally present as salt groups to form a modified starch; b) adding free radical initiator to an aqueous dispersion of the modified starch; c) feeding into the aqueous dispersion ethylenically unsaturated monomers wherein at least 93% by weight of the monomers are mono-ethylenically unsaturated monomers and up to 7 mol % of the monomers are carboxylic acid monomers optionally in salt; d) subjecting the aqueous dispersion to a temperature which initiates polymerization of the monomers to produce chains of copolymerized monomers chemically associated with the modified starch thereby creating the starch-containing film-forming binder; e) mixing the binder so produced with other components of the coating composition; and f) choosing the weight ratio of modified starch to unsaturated monomers so as to ensure that the weight of starch in the starch-containing binder does not exceed 50 wt % of the weight of the starch-containing binder.