PRODUCTION OF WATER ABSORBING POLYMER

PURPOSE:To obtain the subject polymer according to continuous polymerization with excellent productivity and good operating efficiency by specifying a method for mixing an aqueous solution of a monomer with a catalyst. CONSTITUTION:A catalyst (solution) is initially added to an aqueous solution of a monomer consisting essentially of an alpha,beta-unsaturated carboxylic acid (salt) which is a raw material in a feed pipe for feeding the aforementioned aqueous solution of the monomer to a polymerization reactor at a flow velocity of 0.25-4 times based on that of the above-mentioned aqueous solution in the feed pipe. The resultant mixture of the aforementioned aqueous solution of the monomer with the catalyst (solution) prepared in the aforementioned step is subsequently fed to the polymerization reactor to continuously carry out polymerization. Thereby, the objective polymer is obtained. Furthermore, an aqueous solution containing >=20wt.% acrylic acid and alkali metal acrylate at (0-80):(20-10) molar ratio of the acrylic acid to the alkali metal acrylate is preferred as the aqueous solution of the monomer.