PARTICULATE WATER ABSORBING AGENT AND METHOD FOR PRODUCTION THEREOF, AND WATER ABSORBING ARTICLE

摘要

A particulate water absorbing agent being prepared by the surface crosslinking treatment of a water absorbing resin having a crosslinked structure, characterized in that (i) a mass average particle diameter (D50) is 200 to 600 mum and particles having a diameter of not less than 150 and less than 850 mum account for 95 to 100 wt % of the total particles, (ii) a logarithmic standard deviation (sigmazeta) of its particle size distribution is 0.25 to 0.45, (iii) a degree of compression is 0 to 18 %, and (iv) a surface tension of a supernatant liquid being obtained four minutes after the dispersion of 0.5 g of said particulate water absorbing agent into 50 ml of a physiological saline solution at 20°C is 55 mN/m or more. The particulate water absorbing agent exhibits high fluidity in a dry state, while retaining high absorbing capability, and can be free from blocking, caking and the sticking to an apparatus or the like, and, when the absorbing agent is contacted with a liquid to be absorbed, the liquid is less prone to reduction of the surface tension, and further, the absorbing agent exhibits enhanced fluidity and bulk density without detriment to absorbing characteristics.