| 摘要 |
PROBLEM TO BE SOLVED: To produce a tubular film uniform in strength in its longitudinal and lateral directions by suppressing the shaking of a film even if a blowup ratio is enhanced when high density polyethylene is used. SOLUTION: In a method for producing a tubular film by emitting a tubular thermoplastic molten resin from an annular resin outlet to inflate the same, pressure of 0.48-5.6 kgf/cm2 is applied to the outside of the tubular film 2 in a region of a temp. range from the m.p. of the molten resin +10 deg.C to the softening point thereof -15 deg.C before starting the inflation of the tubular film and, after pressurization, the tubular film 2 is inflated.
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