Method for producing water-absorbing resin
OwnerShinichi Uda, Tomoki Kawakita +1inventors
InventorsShinichi Uda, Tomoki Kawakita, Yasuhiro Nawata
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Abstract
A process for preparing a water-absorbent resin comprising carrying out a reversed phase suspension polymerization in multi-steps of at least two steps when the water-absorbent resin is prepared by subjecting a water-soluble ethylenically unsaturated monomer to the reversed phase suspension polymerization, said process for preparing a water-absorbent resin being characterized by adding a phosphorus-containing compound to at least one step in the second and subsequent steps, to carry out the polymerization reaction. The water-absorbent resin can be suitably used in hygienic materials such as disposable diaper, incontinence pad and sanitary napkin, especially in disposable diaper.
Claims3
1] A process for preparing a water-absorbent resin comprising carrying out a reversed phase suspension polymerization in multi-steps of at least two steps when the water-absorbent resin is prepared by subjecting a water-soluble ethylenically unsaturated monomer to the reversed phase suspension polymerization, said process for preparing a water-absorbent resin being characterized by adding a phosphorus-containing compound to at least one step in the second and subsequent steps, to carry out the polymerization reaction.
2] The process for preparing a water-absorbent resin according to claim 1, wherein the phosphorus-containing compound is at least one member selected from the group consisting of phosphorous acid compounds, phosphoric acid compounds and hypophosphorous acid compounds.
3] The process for preparing a water-absorbent resin according to claim 1 or 2, wherein the amount of the phosphorus-containing compound is from 0.00001 to 0.05 mol per 1 mol of the water-soluble ethylenically unsaturated monomer used in the polymerization reaction in the step of adding a phosphorus-containing compound, to carry out polymerization reaction.