Process for producing a low water content PVA hydrogel
First Claim
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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Abstract
The present invention relates to a method of producing polyvinyl alcohol hydrogel characterized by the following features: the production process consists of a low-temperature processing stage in which the solution of polyvinyl alcohol with a polymerization degree over 1200 is processed at a low temperature so that polyvinyl alcohol is gelated, and a high-temperature processing stage in which the polyvinyl alcohol gelated int he low-temperature processing stage is dried, then processed at higher than 100° C.; in this way, polyvinyl alcohol hydrogel with a saturated water content lower than 40 wt % is obtained. The hydrogels of this invention are useful for providing improved artificial articular cartilage for replacement of cartilage in the human body.
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Citations
7 Claims
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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. - View Dependent Claims (2, 3, 4, 5, 6, 7)
- 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°
Specification