| 摘要 |
PURPOSE:To shorten the change-over time of synthetic resin and at the same time reduce the usage of purging material by a method wherein specified purging material, which is compatible with the second synthetic resin, is fed to an extruder and, after the purging of the first synthetic resin, the second synthetic resin is fed in order to displace the purging material. CONSTITUTION:Purging material, which is formed by blending 1-20 wt.% of fine moisture absorbent particles with synthetic resin compatible with the second synthetic resin and having a melt index less than or equal to 40 dg/min, is fed to an extruder in order to purge the first synthetic resin. After the purging of the first synthetic resin, the second synthetic resin is fed to the extruder in order to displace said purging material. The first synthetic resin is polyester and the second synthetic resin is polyolefin. As the fine moisture absorbent particle, moisture absorbent, which contains 0.05 wt.% or more and the particle diameter of which is 0.1-150 mum, preferably 1-25 mum, is used. The purging material fed to the extruder is foamed by turning the water content in the purging material into steam under heat so as to remarkably expand its volume in the interior of the extruder, resulting in serving to expel the first synthetic resin. |
