| 摘要 |
<p>Heat setting a biaxially oriented polyamide film comprises heat setting a biaxially oriented film having a low anistropy in hot water shrinkage ratio in a flat state, if desired, after preheating treatment. Process comprises heating the film in a temp. range of 40 to 10 deg.C lower than its melting point in close contact with the surface of a heated material with both ends of the film clamped, and cooling the film to a temp. at which the film is not deformed easily. The invention also relates to a biaxially oriented polyamide film which has a hot water shrinkage ratio at 100 deg.C of up to 5.0% in all directions at all positions in the transverse direction and an anisotropy H (%) is hot water shrinkage ratio calculated according to the equation alpha of up to 30%, preferably up to 20% wherein S45 and S135 represent hot water shrinkage ratios at 100 deg.C in the directions at angles 45 deg. and 135 deg. left from the machine direction, respectively. This film is one which could not be obtained by the conventional tenter process, etc..</p> |
