B - Operations – Transporting – 29 – C
Patent
B - Operations, Transporting
29
C
18/527
B29C 55/28 (2006.01) B29C 55/26 (2006.01)
Patent
CA 1320320
Abstract of the Disclosure A process and device for preparing a stretched film by passing a tubular thermoplastic film into pairs of nip rolls having different peripheral speed and by inflating an obtained bubble with internal pressure under heating, wherein the pairs of nip rolls comprise at least three pairs of nip rolls designated with R1, R2 and R3, respectively, pressurized air is admitted into the stretched bubble situated between the rolls R1 and R2 through a slit-like air injecting nozzle provided in a gap between the pair of rolls of R2, and the bubble formed by the supplied pressurized air is inflated and stretched under heating. In this stage, if desired, the amount of injected pressurized air is controlled by manual control or automatic control by detecting the diameter of the bubble so as to keep the bubble's diameter constant. After stretching, the film is collapsed with a collapser device and is introduced to the nip rolls of R2, both side ends of the collapsed film is cut open with film cutting knives positioned between the pair of nip rolls of R2 to make two sheets of flat films, and then, the flat films are introduced to left and right guide rolls so as to avoid interference with the slit-like injecting nozzle and the cutting knives. Finally, the films are drawn with the nip rolls of R3. In the device of the present invention, the diameter and internal pressure of the bubble can be controled with manual or automatic control during the tubularly stretching, and particularly, the device can be suitably applied to tubularly stretching of pourus films.
589437
Kojoh Hisashi
Mizutani Tomoji
Tomoda Kazuhiro
Yamaguchi Naoya
Kohjin Co. Ltd.
Osler Hoskin & Harcourt Llp
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