| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a stretched film having no unevenness of thickness in the width direction and no variation in orientation direction, excellent in optical characteristics, slanted in an orientation axis within the range of a predetermined angle to the winding direction, and wide and long. <P>SOLUTION: A method for producing the stretched film comprises: a process of obtaining a first stretched film having an orientation angle θ1 of 0°≤θ1≤1° to the width direction, and a birefringence Δn of the range of 0.001-0.003 by stretching a long non-stretched film composed of a thermoplastic resin in the direction orthogonal to its advancing direction; and a process of obtaining a second stretched film having an orientation angle θ2 to the winding direction of the range of 40°<θ2<50° by re-stretching in a tenter satisfying each condition of 1.0≤R2/R1≤2.0 (1), 0°≤θo≤θi≤6° (2), and 4°≤θo<SB POS="POST">(max)</SB>+θi<SB POS="POST">(max)</SB>≤7° (3) while letting out the first stretched film in a direction by an angle θ of 10°<θ<60° to the winding direction. <P>COPYRIGHT: (C)2012,JPO&INPIT |
