Abstract: This invention is directed to aqueous compositions and the process for preparing same and more specifically to aqueous coating compositions comprising polymeric resin binders and pigments dispersed in an aqueous system with starch ester dispersants. The dispersant consists of mixed esters of starch derived from (a) low molecular weight hydrolyzed starch having a plurality of anhydroglucose units or a derivative of said starch and (b) at least about 0.5 mole of acylating agent for each anhydroglucose unit of the hydrolyzed starch or its derivative. The acylating agent is a combination of anhydrides or acyl compounds consisting of (i) from about 0.1 to 2.9 moles of at least one anhydride of a polycarboxylic acid and (ii) from 0.1 to 2.9 moles of at least one compound selected from the class consisting of anhydrides of monocarboxylic acids and the acyl halides of monocarboxylic acids.

Abstract: This invention is directed to aqueous compositions and to the process for preparing same which comprises a dispersion of polymeric resin binders and pigments in an aqueous system with a dispersant. The dispersant consists of half-esters of starch derived from (a) low molecular weight hydrolyzed starch having a plurality of anhydroglucose units or a derivative of said starch and (b) at least about 0.25 mole of at least one cyclic anhydride of a polycarboxylic acid for each anhydroglucose unit of the hydrolyzed starch and/or its derivatives.These half-ester starch dispersants are characterized as having pendant carboxyl groups and average molecular weights ranging up to about 100,000 with a high degree of substitution, i.e. wherein on an average of about 0.25 to 3.0 of the hydroxyl groups of each anhydroglucose unit are esterified. The unreacted carboxyl groups pendant from the backbone of the starch esters may be further reacted, i.e.