| 摘要 |
<p>PURPOSE: To reduce a curl phenomenon at the time of the treatment with boiling water to the utmost by satisfying the relations of two specific formulae at the same time. CONSTITUTION: A biaxially oriented polyamide resin film satisfies the relation of formula I:3% <=BSx<=6% (BSx shows the max. value among boiling water shrinkage factors in all directions) and the relation of formula II:BSa<=1.5% (BSa shows the absolute value of the difference between a boiling water shrinkage factor in a direction of +45 deg. with respect to the flow direction of the film and a boiling water shrinkage factor in a direction of -45 deg.) at the same time. The relative viscosity of a polyamide resin is pref. 2-3.5 and, in the case of below 2, impact strength becomes rather insufficient and, in the case of above 3.5, sequential biaxial stretchability becomes inferior by the increase of stretching stress. When the value of BSx is below 3%, impact strength being one of the indexes of toughness/pinhole resistance becomes insufficient and, when the value of BSx exceeds 6%, lamination becomes inferior and delamination resistance at the time of hot water treatment becomes insufficient.</p> |
