Patent ID: 7504551
Filing Date: 2009-03-17
Classification: A61L,C08F,Y10S,Y10T

Abstract:
1. A method of manufacturing color-stable superabsorbent polymer particles comprising the steps of: (a) forming a monomer mixture comprising: wherein M is hydrogen, an ammonium ion, or a monovalent or a divalent metal ion of groups Ia, IIa, IIb, IVa, and VIIIb of the Periodic Table of the Elements; R R R and the salts thereof; or a mixture thereof; (b) polymerizing the monomer and the crosslinking agent in the monomer mixture to form a superabsorbent polymer hydrogel; (c) optionally subjecting the superabsorbent polymer hydrogel to a low dose of UV radiation; (d) comminuting the superabsorbent polymer hydrogel to provide superabsorbent hydrogel particles; and (e) drying the superabsorbent polymer hydrogel particles for a sufficient time at a sufficient temperature to provide the color-stable superabsorbent polymer particles, wherein the color-stable SAP particles, after storage for 30 days at 60° C. and 90% relative humidity, exhibit an HC60 color value of at least 60 and a maximum b-value of 10.