Prepn. of water-absorbent resin used in disposable nappies, hygiene articles etc.

摘要

A water-absorbent resin is prepd. by cross-linking the surface region, by treating and reacting (A) a water-absorbing resin contg. a COOH gp. and/or a salt gp., with a cross-linking agent in presence of (B) an organic solvent with dielectric constant of at least 25, 1-8 wt.% of water w.r.t. (A), (C) a cross-linking accelerator, and (D) a polyglycidyl cpd. with at least 3 glycidyl gps. as cross-linking agent. Pref. a liq. mixt. of (B), water, (C) and (D) is sprayed onto (A), or is added dropwise to (A) with stirring and mixing. Alternatively, (A) is treated with a liq. mixt. of (B), water, (C) and (D). The ratio by wt. of (B):water is 6:4-1:9, and the mixt. of (B), water and (C) is 2-10 wt.% w.r.t. (A). Cross-linking is at 100-180 deg C. (B) The component is ethylene glycol and/or di- or tri-ethylene glycol. (C) The component is a thiol cpd., a mono-amino cpd. or a carboxylic acid, and the ratio by wt. of (D):(C) is 1:0.01-1. (D) The component is polyglycerol polyglycidyl ether (pref.), pentaerythritol polyglycidyl ether or sorbitol polyglycidyl ether.