Patent ID: 6444744
Filing Date: 2002-09-03
Classification: A61L,C08F

Abstract:
A crosslinked water-absorbent resin which is internally-crosslinked, which is obtained by aqueous solution polymerization or reverse-phase suspension polymerization, which has a water-soluble content of 25 weight % or below, which has an absorption capacity of 20 g/g or more for a physiological salt solution under a load of 50 g/cm2, over a period of 60 minutes, wherein the physiological salt solution is 0.9 wt % aqueous sodium chloride solution and which is obtained by a process comprising the steps of:a) producing an acrylic acid, wherein hydroquinone is used in the step of producing the acrylic acid in an amount greater than 0.20 ppm â€œbased on acrylic acidâ€ ; b) reducing a total amount of hydroquinone and benzoquinone in the acrylic acid or its salt to at most 0.20 ppm â€œbased on acrylic acidâ€ ; c) providing a monomer component, wherein a major portion of the monomer component is one or both of the acrylic acid or its salt; and d) polymerizing the monomer component to obtain the crosslinked water-absorbent resin.