Water-absorbing agent, manufacture method thereof, and absorbent and absorbent article made therefrom

A water-absorbing agent, comprising a water-absorbing resin having a crosslinking structure constructed by polymerization of an unsaturated monomer component, wherein

• the water-absorbing agent is surface-treated, and
• the water-absorbing agent meets all of properties (1) through (4):
• (1) heat retention indicator 1 (maximum temperature decrease per minute 5 to 10 minutes after 10 times swelling in a 0.90 wt. % sodium chloride at 50° C.) is from 0 to 3.0° C./min;
• (2) a centrifuge retention capacity in a 0.90 wt. % aqueous solution of sodium chloride (30 minute value) is 34 g/g or less;
• (3) an absorbency in a 0.90 wt. % aqueous solution of sodium chloride against a pressure of 2.0 kPa (60 minute value) is less than 30 g/g;
• and
• (4) a saline flow conductivity (SFC) for a 0.69 wt. % aqueous solution of sodium chloride is less than 20×10−7 cm3 sec/g, wherein
• the water-absorbing agent is particles,
• the water-absorbing agent meets following conditions:
• particles having diameters from 600 to 300 μm as specified by sieve classification account for 60 wt. % or more, and those less than 150 μm account for 3 wt. % or less;
• and
• a standard deviation of logarithm (σζ) of particle size distribution is from 0.250 to 0.400;
• and wherein the unsaturated monomer is an acrylic acid (salt), and a ratio of a monomer other than the acrylic acid (salt) to the acrylic acid (salt) is 0 to 30 mole % inclusive.