Process for the preparation of polymaleic acid from maleic anhydride in the presence of acetic anhydride and hydrogen peroxyde, and the use of the polymaleic acid thus prepared as builder and as incrustation inhibitor in detergent compositions

摘要

Process for the preparation of polymaleic acids with molecular weights between 200 and 1500 by polymerizing maleic anhydride in the presence of hydrogen peroxide and acetic anhydride and saponifying the polymaleic anhydride formed, characterized in that the maleic anhydride is dissolved in 1 to 5 times the molar amount of acetic anhydride with the 0.2- up to 0.5 times the molar amount of hydrogen peroxide with simultaneous heating of the reaction mixture to 80 to 140 ° C. and after the addition of the hydrogen peroxide the reaction ends at 100 to 140 ° C. The process can advantageously be carried out in the presence of non-oxidizing acids, reducing agents and, preferably, reducing acids such as phosphorous acids or oxalic acid. The polymaleic acids obtained are suitable as builders and incrustation inhibitors.