Method of producing water absorbent resin

A method for producing a water absorbent resin comprising:

• a polymerization step of polymerizing an aqueous solution of acrylic acid (salt) to obtain a water-containing gel-like crosslinked polymer;
• a drying step of drying the water-containing gel-like crosslinked polymer to obtain a water absorbent resin powder;
• a classification step of classifying the water absorbent resin powder;
• and
• a surface crosslinking step of surface crosslinking the water absorbent resin powder,
• wherein in the classification step that is carried before the surface crosslinking step and/or after the surface crosslinking step, stretch tension (tension) of a metal sieve mesh used in the classification step is from 35 [N/cm] to 100 [N/cm],
• the method satisfying one or more of the following three requirements:
• (1) an airbrush is installed below the metal sieve mesh used in the classification step, in which the airbrush uses dry air having a dew point of 0° C. or lower, and the classifying apparatus is heated at 40° C. to 80° C.;
• (2) in the classification step, a classification aid particle having specific gravity larger than that of the water absorbent resin powder is added, and a fine powder of the water absorbent resin and the classification aid particle are removed, in which the classification aid particle is an inorganic fine particle or an organic fine particle;
• and
• (3) plural tapping balls or tapping blocks are installed below the metal sieve mesh used in the classification step, in which a gas stream passes through in the classification step, and the dew point of the gas stream is 15° C. or lower.