| abstract |
Preparation of a starch ester having an Mn of 1000-50,000 and a degree of substitution of 0.4-3.0 by heating a mixture of starch, a Cl-7 monocarboxylic acid, water, and optionally a catalyst and meanwhile withdrawing water until the ester being formed has attained the desired degree of substitution. Optionally remaining free hydroxyl groups may be esterified by reaction with a carboxylic anhydride of -halide. The resulting solution may be treated to neutralize remaining free monocarboxylic acid by mixing it with an esterifiable hydroxyl compound and esterifying it at 40°-270° under the removal of water. In this way, use is made of cheap ingredients, and the resulting product is suitable for immediate use in a number of applications, e.g., as binder in coating compositions. |