Process for the preparation of polymer compositions having low volatile content

摘要

A continuous process for the preparation of polymer compositions having low volatile content which comprises passing a styrene polymer-containing polymerization fluid composition obtained by solution polymerization or bulk polymerization through a volatile component separator comprising vertical foaming preheaters and vacuum vessels directly connected therewith and thereby removing volatile components continuously from the polymerization fluid composition in three stages to obtain a polymer composition having low volatile content, the process being characterized in that each of three stages includes at least one vertical foaming preheater and one vacuum vessel, the first stage is carried out under such pressure and temperature conditions that the polymerization fluid composition leaving this stage contains said styrene polymer in an amount of 60 to 80% by weight and the temperature of the polymerization fluid composition passing through this stage lies between 70 DEG and 120 DEG C., the second stage is carried out under such pressure and temperature conditions that the molten polymer composition leaving this stage has a volatile content of not greater than 1% by weight and can retain good fluidity, and the third stage is carried out in such a way that devolatilization is effected at a pressure of 50 Torr or less in the presence of a highly volatile foaming agent.