Patent ID: 7304124

Claim:
A process for stripping volatile substances from a dispersion comprising polymer particles obtained by polymerization in an aqueous medium, the process comprising: (A) stripping volatile substances from the dispersion by blowing an inert gas into the dispersion to draw the volatile substances into the inert gas; (B) removing volatile substances from the gas mixture of the inert gas and the stripped volatile substances; and (C) continuing the stripping of the volatile substances from the dispersion by circulating a purified inert gas obtained by removing the volatile substances from the gas mixture, and blowing the purified inert gas into the dispersion; wherein an inert gas blowing position in stripping step (A) is set so that a ratio D 2 /D 1 is in a range of 0.5 to 1, where D 1 is a maximum liquid depth of the dispersion and D 2 is a liquid depth to an inert gas blowing position, and wherein stripping is carried out while stirring the dispersion using a stirrer, and the inert gas blowing position is at a distance in a range of 0.05 L to 1.5 L from a center-axis of the stirrer, where L is a horizontal distance from the center-axis of the stirrer to a tip of the stirrer.