| 摘要 |
PROBLEM TO BE SOLVED: To realize the pouring of the constant amount of an additive into a stock resin in an extrusion process and consequently obtain a uniform and stable plastic film by a method wherein the liquid additive, the pressure of which is boosted to a specified times as much as the maximum pressure of a solid bed, is poured. SOLUTION: A pouring nozzle 8 for adding an additive is provided on the barrel 7 of an extruder 2. An important point for realizing the feeding of the constant amount of the additive with the pouring nozzle 8 without being influenced by the pressure fluctuation of a compression part 18 is the provision of a back pressure valve in the midway of a piping running from a feed pump to the pouring nozzle 8 so as to keep a pouring pressure 1-10 times as much as the maximum pressure of a solid bed. As a result, the discharge pressure of the feed pump becomes constant, resulting in making the pour fed from the feed pump constant. Further, a plurality of pouring nozzles 8 may be allowed to simultaneously pour two or more different additional substances. |
