Patent ID: 6399730
Filing Date: 2002-06-04
Classification: B01J,B29B,C02F,C08F,Y10T

Abstract:
A small particle size, substantially dry, water absorbing crosslinked polymer made by the process, comprising the steps of:preparing a mixture of a monomer, a crosslinker and an initiator in water; heating the atmosphere of a reaction chamber to between about 70Â° F. and about 300Â° F., defined by a vessel; controlling the pressure of the atmosphere in the reaction chamber from about 0.1 to about 30.0 inches of Hg relative to ambient pressure; spraying the mixture into the heated pressure controlled atmosphere forming free-falling droplets; allowing the droplets to fall through the heated, pressure controlled atmosphere for a period of time sufficient to obtain the desired degree of polymerization of the monomer and crosslinking of the polymerized monomer and to form dry particles of flowable water-absorbing polymer powder; and removing fallen particles of dry water-absorbing polymer powder that collect at the bottom of the reaction chamber while maintaining the reduced pressure therein and continuously producing polymer; and wherein a small particle size, substantially dry, water absorbing crosslinked polymer is produced, the polymer having a substantially smooth and spherical shape, a water content of less than about 2 percent by weight and a particle size of less than about 50 microns.