| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for reducing or excluding a gaseous impurity in e resin melt in which the gaseous impurity has an ultralow diffusion rate or from the resin melt. SOLUTION: This method for removing a volatile material from a thermoplastic polymer containing a gaseous impurity in an apparatus equipped with a melting part, a mixing part and a vacuum part and comprises the following: (a) a step for adding a granular foaming agent directly or in a masterbatch to a polymer before introducing the polymer into the melting part or adding a gaseous foaming agent to the mixing part, (b) a step for melting the polymer in the mixing part, (c) a step for mixing the molten polymer with the foaming agent in the mixing part under a pressure sufficient to maintain the foaming agent in the mixture, (d) a step for decomposing the granular foaming agent in the mixing part and/or the vacuum part at a temperature sufficient for decomposition and expansion or expanding the gaseous foaming agent in the vacuum part, (e) a step for reducing the pressure of the molten polymer at the surface by an amount sufficient to remove essentially all the gaseous impurity in the vacuum part, (f) a step for suitably repeating the steps (c), (d) and (e) at least once and (g) and a step for recovering the polymer in an essentially unexpanded state. |
