| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for controlling the thickness of a tubular biaxially oriented film by which the biaxially oriented film free from thickness irregularity is manufactured as well as a device for controlling the film thickness. SOLUTION: An air ring 6 for flowing air toward an initiating point for transverse orientation along the peripheral side of a tube 2 after orientation is provided between a completion point for transverse orientation of a manufacturing device for a tubular biaxially oriented film and its initiating point for folding. In addition, an actuator 7 for partially adjusting an air flow by making the gap of a slit 10 variable, is installed at the air ring 6. For the heavy thickness part of the film after orientation, the blown air flow is throttled by the air ring 6 to increase the temperature of the heavy thickness part and thus the orientation of the film is promoted to thin the film. On the contrary, for the thin part of the film, the air flow is increased to lower the temperature of the thin part and thus the orienting process is regulated to thicken the film. |
