A process for removing volatile substances from a polymer composition

摘要

There is disclosed a method for removing volatile materials, which comprises adding a blowing aid to a polymer composition containing volatile materials, mixing them in a static mixing apparatus, and extruding the resultant mixture by an extruding apparatus into a devolatilizing tank, thereby the mixture is made to be blown, to cause removal of volatile materials. First, the blowing aid (6) is discharged with an addition nozzle apparatus (2), in a direction opposite to the direction of the flow of the polymer composition (1), to be added, and the polymer composition is introduced into the static mixing apparatus (3), at a pressure at which the blowing does not take place, thereby mixing them. Then, using the extruding apparatus (11), the resultant mixture is extruded into the devolatilizing tank (4), so that the polymer is made into a blown product at such a temperature and a pressure that the blowing coefficient B given by the expression (1) becomes 1.4 or more, thereby causing removal of volatile materials:B = A'/A    wherein A represents the cross-sectional area of an extruding apparatus, and A' represents the average cross-sectional area of the polymer composition in a direction perpendicular to the vertical direction of the blown polymer composition, at a point where the polymer composition is dropped from the lower part of an opening section of the extruding apparatus vertically 50 cm to 1 m. The method can give a polymer composition having residual volatile materials in very small amounts, by removing volatile materials continuously with high efficiency.