| 摘要 |
An off-line stretching device includes a film supply chamber, a tenter section, a relaxation chamber, a cooling chamber, and a winding chamber. The film supply chamber includes a splicing section, where a rear end of a preceding film and a front end of a trailing film are overlapped to be spliced to each other by thermal welding. The thermal welding is performed from above and below the film while a temperature of welding heads of a heat sealer, contacting with the film, is kept at a level equal to or less than a decomposition temperature of the preceding and trailing films. The spliced film is stretched in the tenter section and subjected to heat treatment for stress relaxation in the relaxation chamber, to shrink in a film width direction. Since the shrinkage amount of a spliced area and that of a peripheral area become equal to each other, the occurrence of wrinkles in the spliced area and tears of the film in the peripheral area can be prevented. Additionally, since a heat transfer distance between a film surface and a film splicing surface can be shortened, the heating from above and below the film enables high-speed welding. |
