Patent ID: 8501873
Filing Date: 2013-08-06
Classification: C08J,Y10T

Abstract:
1. A water absorbent material comprising a surface cross-linked water absorbent resin resulting from granular irregularly pulverized shaped particles of partial neutralization or whole neutralization of a water absorbent resin having acrylic acid or a metal salt thereof as a main component, which water absorbent material shows a metal atom concentration on the surface of said water absorbent material in the range of 0-10 atom % at 0 second value of polishing and in the range of 2 to below 35 atom % at 10 seconds of polishing as determined by subjecting said water absorbent material to Ar ion discharge polishing under a voltage of 500 V, wherein the water absorbent resin having acrylic acid or a metal salt thereof as a main component has a ratio of partial neutralization in the range of 50-90 mol %, and wherein a fluorine atom ratio to the number of carbon atoms, F/C ratio, in the surface of said water absorbent material on which —COOH has been converted to —COOCH wherein the surface of the water absorbent resin is cross-linked in the presence of 0-0.3 mass part of water, based on 100 mass parts of the water absorbent resin, wherein the proportion of the water absorbent material having a particle diameter of less than 106 μm is in the range of 0-10 mass %, wherein the magnitude of the logarithmic standard deviation δζ which indicates the dispersibility of particle diameter is in the range of 0.25-0.45.