PURPOSE: To obtain a biaxially oriented film low in anisotropy, good in dimensional stability and used in food packing or the like, by specifying a temp. condition in performing such a process that an unoriented film of nylon 12 is oriented by inflation and simultaneously subjected to biaxial orientation and the resulting oriented film is further set under heating.
CONSTITUTION: A tubular unoriented film obtained by cooling molten nylon 12 extruded into a tubular shape is inflated and stretched and simultaneously subjected to biaxial orientation by applying gas pressure to the interior of the tube within a stretchable temp. region and the oriented film is set under heating. In this case, the surface temp. of the film at the begining of inflation is regulated to 60W80°C and a temp. gradient is taken so as to bring the surface temp. of the film at the 1/2W1/3 advance position of an orientation region from the begining of inflation to the finishing point thereof to a max. temp. to adjust the temp. to 80W90°C. In addition, the temp. gradient wherein the surface temp. of the film in the orientation region from the max. temp. position to the finishing point of inflation is fallen 5W10°C from the max. temp. is kept to obtain a film with tensile strength of 1,500kg/cm2 or more in all directions and hot water shrinkage ratio of 3% or less at 100°C.
INUDOU HIDEKI
MORIYAMA TAMIO
IWASAKI MAKOTO
SAKAMOTO YOSHIHIRO
| JPS5521258A | 1980-02-15 | |||
| JP44002600A |
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