| 摘要 |
PURPOSE:To reduce the breakage of a film by a method wherein a clip, whose length in the advancing direction of a plastic film in a grip is different between an upper part and a lower part, is employed and the film is stretched while arranging the grip, whose clip is longer, on the lower surface of the plastic film. CONSTITUTION:A clip should have a length in the advancing direction of a film in a grip, which is different between an upper part and a lower part. In another word, the length of the upper part 3 and the length of the lower part 4 should be different. Further, the longer clip is arranged below the plastic film to expand it. The length of the clip is preferable to be 10-100mm and more preferable to be 20-80mm. The difference of the length is preferable to be O.5-10mm and more preferable to be 1-4mm. When the length and the difference of lengths are smaller than these values, the breakage of the film due to the concentration of stretching stress is readily generated and, on the other hand, when the same are larger than these ranges, the film is stretched between the grips of the clip and whereby not only the breakage of the film is generated readily but also the width of one set of clip becomes wide uselessly and the necking of the end portions of the film upon stretching becomes large.
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