| 摘要 |
PROBLEM TO BE SOLVED: To provide an inflation molding method and apparatus capable of obtaining a good product by enhancing the uniformity of the thickness or physical properties of a film and eliminating the generation of slackening or wrinkles in the film. SOLUTION: In an inflation molding method for molding a cylindrical film 11 comprising a thermoplastic resin, the outer surface of the cylindrical film 11 extruded from the annular slit 7 of a die 1 to be molded is supported at least at three points separated in the peripheral direction of the film and these support positions of the film are set to the region from the upstream position (dotted line A) in an expanding process having a film diameter smaller than that at a solidifying point 12 where the expanding process of the film 11 is completed and a diameter change is eliminated by 10% to the position (dotted line B) set on the downstream side exceeding the solidifying point 12 and becoming symmetric with respect to the position B through the solidifying point 12. |
