| 摘要 |
PURPOSE:To improve the dimensional stability due to heat treatment by also loosing longitudinally by a method wherein upstream side driving wheels and downstream side driving wheels are provided in a tenter and the peripheral speed of the downstream side driving wheel is made smaller than that of the upstream side driving wheel. CONSTITUTION:In a method to heat-treat uniaxially stretched film 1 while running in a tenter 2 under the state that both sides of the film are held with clips 3, the upstream side wheels and downstream side wheels among the running wheels of the clips are made as driving wheels. At the same time, the driving wheels are run under the condition that the peripheral speed of the downstream side driving wheel 5 is made smaller than that of the upstream side driving wheel 4. Because the stretched film is heat-treated under the state also of being loosen longitudinally due to the difference between the speeds of both said wheels, the dimensional stability is made better. Thus, the titled treatment is suitable for manufacturing magnetic tape and the like. In addition, the facilities for the treatment can simply be obtained, because the only replacement of the running wheels in the conventional device with driving wheels is enough.
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