METHOD FOR PREPARING HIGHLY ABSORBENT POLYMERS

摘要

A process is provided herein for producing highly water-absorbent hydrophilic gels. The process comprises polymerizing acrylic acid and/or methacrylic acid in the presence of polyvinyl alcohol to obtain a polymer (A). Polymer (A) is then subjected to neutralization followed by heat treatment or to heat treatment followed by neutralization. Alternatively a neutralized product of acrylic acid and/or methacrylic acid may be polymerized in the presence of polyvinyl alcohol to obtain a polymer (B). Polymer (B) is then subjected to heat treatment. According to this invention, the polymerization is carried out in an aqueous solution having a total concentration of acrylic acid and/or methacrylic acid or its neutralized product (the weight of the neutralized product is converted to the acid basis) and polyvinyl alcohol of 10 to 60% by weight, the heat treatment temperature is 50.degree. to 150.degree.C, and the weight ratio of polyvinyl-alcohol to acrylic acid and/or methacrylic acid or its salt (the weight of the neutralized product is converted to the acid basis) is 5 to 95: 95 to 5. The polymers are hydrophilic gels which can preferably be used as water-absorbent materials or gel materials used in a hydrated swollen state.