Patent ID: 8648150

Claim:
A method for producing a water absorbent resin which method is a method for producing surface cross-linked water absorbent resin particles, wherein: in the step (a) of adding a surface cross-linking agent and water to a particulate water absorbent resin in a mixer, a temperature of the particulate water absorbent resin is preset to 30° C. to 150° C.; and a continuous mixing apparatus is used which meets the following requirements (i) through (iii): (i) at least one stirring vane revolves at 300 rpm to 3000 rpm; (ii) a revolving shaft of the at least one stirring vane is in a vertical direction; and (iii) a mixing vessel is vertically divided into two or more rooms by a partition whose aperture ratio is 5% to 70%; and the particulate water absorbent resin is supplied to the mixer in an amount of 10 kg/hr to 300 kg/hr per liter of the volume of the mixing vessel of the mixer.