Patent ID: 9598521
Date: 2017-03-21
CPC Classifications: A61K,A61Q,C08F

Claim:
1. A method for producing hydrophilic polymer particles, the method comprising: step 1: preparing a dispersion in which an aqueous-phase component including hydrophilic monomers and a polymerization initiator is dispersed in an oil-phase component including a hydrophobic solvent having a solubility of 1 mass % or less in water at 25° C.; step 2: reducing a dissolved oxygen concentration of the dispersion prepared in step 1; and step 3: polymerizing the hydrophilic monomers in the aqueous phase by supplying oxygen to a reaction vessel and, while oxygen is being supplied, heating the dispersion whose dissolved oxygen concentration was reduced in step 2 in the reaction vessel so that a temperature of the dispersion increases, wherein a time from a start of reduction of the dissolved oxygen concentration of the dispersion in step 2 to a start of heating of the dispersion in step 3 is greater than or equal to 0.1 hour and less than or equal to 3.5 hours, and an amount of oxygen supplied to the reaction vessel in step 3 is greater than or equal to 0.02 volume % per hour and less than or equal to 0.9 volume % per hour with respect to a volume of the dispersion, under standard conditions of a temperature of 25° C. and an absolute pressure of 101.3 kPa.