Method for the purification of propylene polymers.

摘要

Disclosed is a method for the purification of propylene polymers which comprises bringing a propylene polymer containing volatile components into contact with a gas consisting mainly of propylene at a temperature lower than the melting point of the polymer, whereby the volatile components are removed from the propylene polymer. A process gas obtained by evaporating the reaction medium contained in a slurry resulting from bulk polymerization using propylene itself as the reaction medium or a process gas separated and recovered from a polymerization mixture resulting from vapor phase polymerization is suitable for use in the practice of the present invention, because its dew point is low enough for drying purposes and it can be recycled in large amounts. The method of the present invention permits the volatile components contained in the polymer to be removed to substantially the same extent as is attainable by the conventional drying method using a large amount of nitrogen gas. Thus, the present method has very great economic advantages over the conventional one.