Polyaspartic add process developed
STEPHEN C. STINSON · Chemical & Engineering News · 1992
A commercial process to make polyaspartic acid homopolymers and copolymers has been developed by chemists at Donlar Corp., Harvey, III. The company expects to develop the biodegradable resins to replace polyacrylic acid in certain applications. Donlar president Larry Koskan says initial efforts will be for use as detergent builders and in water treatment. Polyaspartic acid will have to show clear advantages in performance and biodegradability, however, because its cost will be $2.00 to $10 per lb, in comparison with 90 cents to $1.50 per lb for polyacrylic acid. The process begins with heating of crystalline racemic aspartic acid in a profile of temperatures from 200 to 300 °C to split out water and form poly- N,α-succinimide. Base hydrolysis then opens the imide ring to give the resin polymerized 70 to 80% through the β-carboxyl group and 20 to 30% through the α-carboxyl group. Although molecular weights are controlled in a range of 25,000 to 30,000, ...