Process for preparing highly water absorbent resin
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United States of America Patent
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Apr 16, 1996
Issued Date -
N/A
app pub date -
Jun 15, 1994
filing date -
Sep 20, 1991
priority date (Note) -
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Abstract
The present invention provides an improved process for preparing a highly water absorbent resin having a superior suction power and excellent gel strength, which consists essentially of: (1) neutralizing acrylic acid to a neutralization degree ranging from 50 to 100% based on the total number of moles of the acid employed and polymerizing it by a reverse phase suspension polymerization to provide a neutralized polymer; (2) dehydrating the polymer until its water content reaches 25% by weight or less based on the weight of the polymer through an azeotropic distillation thereof in the presence of a lipophilic solvent; (3) crosslinking the dehydrated polymer in the presence of a hydrophilic crosslinking agent containing at least two epoxy groups in an amount ranging from 0.05 to 5.0% by weight and water added in an amount ranging from 7.0 to 25.0% by weight based on the weight of the dehydrated polymer; (4) dehydrating the crosslinked polymer until 60% by weight or more of the amount of water added in step(3) above is removed through an azeotropic distillation thereof under reflux; and (5) recovering the crosslinked and dehydrated polymer by filtration.
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