| 摘要 |
PROBLEM TO BE SOLVED: To produce a film containing polypropylene of high quality by together extruding a plurality of kinds of melts through a flat sheet die at the same time and forming the edge portions of a film from a propylene polymer or a propylene polymer mixture during a production process. SOLUTION: The compression, heating and melting of polymers and the supply of melt streams A, B are performed simultaneously by using a coextrusion adapter 6. However, the melt streams A, B are arranged in parallel 16. The juxtaposed melts are shaped into a film in a flat sheet die 8 and the edge parts of the film are formed from a polymer A (from the melt stream from an extruder 2). The actual film 14 includes a polymer B (from the melt stream of an extruder 1). These edge parts 12 are cut off after the longitudinal and transverse stretching of the film. |
