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Process for producing a low water content PVA hydrogel

  • US 4,988,761 A
  • Filed: 04/26/1989
  • Issued: 01/29/1991
  • Est. Priority Date: 09/22/1988
  • Status: Expired due to Fees
First Claim
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1. A process of producing polyvinyl alcohol hydrogel comprising (A) subjecting a solution in a mixture of water and water-miscible organic solvent of polyvinyl alcohol with a polymerization degree over 1200, to a temperature below -5°

  • C. so that the polyvinyl alcohol is gelated, (B) drying said hydrogel at an elevated temperature so that it contains less than about 3% by weight of water, (C) subjecting said hydrogel to a temperature higher than 100°

    C. for a time sufficient to reduce the size of the PVA crystals in said hydrogel, (D) saturating the resulting hydrogel with water, whereby polyvinyl alcohol hydrogel with a saturated water content lower than 40 wt % is obtained.

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