Freeze-dried polyvinyl alcohol gel
AssigneeNippon Oil Co., Ltd.
InventorMasao Nambu
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Abstract
A process for the preparation of a hydrogel is provided. The process comprises the steps of solidifying an aqueous solution containing 2.5 to 25 wt % of a polyvinyl alcohol of an average polymerization degree of not less than 800 and 1 to 80 wt % of a water-soluble polyhydric alcohol by cooling the aqueous solution to not higher than -3.degree. C. and then dehydrating in vacuum the solidified mass into a percent dehydration degree of 5 to 95 wt %. The hydrogel is suitable for use as a cooling medium.
Claims10
A process for the preparation of a hydrogel, comprising the steps of solidifying an aqueous solution containing 2.5 to 25 wt % of a polyvinyl alcohol having a degree of hydrolysis of not less than 95 mol % and an average polymerization degree of not less than 800, and 1 to 80 wt % of a water-soluble polyhydric alcohol having 2 to 6 hydroxyl groups, by cooling said aqueous solution to a temperature of not higher than - (minus) 3.degree. C., and then dehydrating in vacuum the solidified mass until the percent dehydration rate reaches 5 to 95 wt %.
Dependencies are inferred from the claim text.