| 摘要 |
A pipe for supplying a dope to a co-casting die consists of a goose neck portion connected to a feed block of the co-casting die, and a straight pipe portion connected to the goose neck portion. The goose neck portion has a radius of curvature of 50 mm to 400 mm, and the straight pipe portion forms an angle of 0 to 20 degrees to the horizontal plane. Venting valves are opened up at the beginning of dope feeding, and are closed to some extent as the dope comes out. After the air is completely vented out, the venting valves are completely closed. Thereby, an air collection is completely let out from the pipe, a plastic web discharged from die lips of the co-casting die would not contain any air bubbles, it is prevented that the web splashes to put on the die lips, causing streaks on the produced film.
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