| 摘要 |
PROBLEM TO BE SOLVED: To obtain a resin film that is suitably useful as a magnetic tape with reduced deformation along the edge parts by adjusting the resin film so that the relation between the increase in the stress and the elongation immediately before the breakage in the widthwise direction may satisfies a specific formula. SOLUTION: This invention is to prepare a film that satisfies formula I in the relation between the increase in the stress in the widthwise direction F (MPa) immediately before the breakage and the elongation S (%) immediately before the breakage. In a preferred embodiment, this film mainly comprises a polyamide resin. In order to satisfy the relation, for example, the density and crystallinity of the film are adjusted at a heat treatment step, or the difference in the Young's modulus in the longitudinal direction and in the widthwise direction is suppressed within a prescribed range, when the film is produced. In addition, the film is desirably to have a Young's modulus of >=7 GPa and the Young's modulus E (MPa) in the film width direction, F and S satisfy the relation of formula II.
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