Method for continuous production of water-absorbent resin

A method for continuous production of a water-absorbent resin by use of a continuous polymerization device comprising a charge part of a monomer aqueous solution containing a monomer, a polymerization initiator and a crosslinking agent;

• an endless belt on which the monomer and a hydropolymer formed are conveyed;
• and a discharge part of the hydropolymer,
• wherein the continuous polymerization device has side walls and a ceiling, and the space ratio in the device represented by the following equation 4 is in the range of 1.2 to 20:
• Space ratio in the device=B/A [Equation 4]
• wherein A is a maximum cross-sectional area (cm2) of the hydropolymer during the polymerization in the width direction of the endless belt, and B is a maximum cross-sectional area (cm2) of the space between the endless belt of the continuous polymerization device and the ceiling of the continuous polymerization device in the width direction of the endless belt;
• and the initial temperature of the polymerization is in the range of 30° C. to 105° C.;
• and the concentration of the monomer in the monomer aqueous solution is in the range of 35 wt % to 80 wt %.