Starch based superabsorbent

摘要

Starch based superabsorbent polymers are prepared by graft polymerisation using a native starch with an amylopectin content of 15-100 wt.% in powder, granular or other particulate form as backbone, and grafting with 30-300 parts weight (per 100 parts weight starch) of a functional monomer or functional monomer mixture comprising 50-100 wt.% of at least one carboxyl group and/or acid anhydride group containing monomer with a degree of neutralisation of 0-100 % (carboxyl monomer) and 0-50 wt.% of at least one carboxyl group- and acid anhydride group-free monomer, added during a heating and stirring procedure to a final polymerisation temperature of 65-100 deg C after exceeding the characteristic swelling temperature of the respective starch being used of 50-80 deg C, carrying out the graft polymerisation in the presence of an organophilic radical-forming peroxide or diazo initiator and controlling the monomer addition such that the polymerisation mixture retains a dry free-flowing consistency, and subsequently fully neutralising the product.