Patent ID: 8729218

Claim:
Manufacturing method of polyaspartic acid with high yield and minimal heat degradation comprising the steps of: a) reacting maleic anhydride and an alcohol to give monoalkyl maleate compound; b) reacting thus obtained monoalkyl maleate compound and ammonia gas or an aqueous solution of ammonia to give a reaction solution of an ammonium salt of a monoalkyl maleate; c) adding an amide polar solvent without active hydrogen to thus obtained reaction solution of an ammonium salt of a monoalkyl maleate and heating the mixture to effect condensation polymerization for obtaining polysuccinimide; d) hydrolyzing the resulting polysuccinimide, while cooling and neutralizing the mixture to obtain polyaspartic acid; and e) separating the amide polar solvent from the polyaspartic acid to obtain polyaspartic acid in an aqueous solution, wherein high molecular weight polyaspartic acid having an average molecular weight from about 10,000 to about 20,000 and a carboxyl group content of at least 93% is obtained with a production yield of at least 98 mol %.