Patent ID: 8420752

Claim:
A method for producing a particulate water absorbing agent, said method comprising the steps of: (a) circulating, in a neutralization system including a neutralization tank, a mixture solution containing an acid group-containing monomer and salt obtained by a neutralization reaction of the acid-containing monomer with a basic material; (b) continuously supplying, to a polymerization system, a part of the mixture solution that is being circulated; and (c) polymerizing a monomer component of the mixture solution in the polymerization system, the method satisfying a requirement that a value X is not more than 200, the value X being found according to the following expression: X =( V/F )· A wherein V (kg) is a volume of the mixture solution present in the neutralization system, F (kg/h) is a flow volume of the mixture solution to be supplied to the polymerization system, and A(m 2 ) is a contact area of the mixture solution present in the neutralization system with a device(s) and a pipe(s) constituting the neutralization system.