| 摘要 |
A method for producing a birefringent film involving a step of stretching a polymer film, which comprises stretching the polymer film in its width direction and simultaneously allowing it to shrink in its longitudinal direction, in such a manner that the change ratio of the length in the width direction (STD) by the above stretching and the change ratio of the length in the longitudinal direction (SMD) by the above shrinkage, with the proviso that the lengths of the film in the width and longitudinal directions before the stretching or shrinkage are taken as 1, respectively, satisfy the following formula (1): (1/STD) 1/2 <= SMD < 1 (1). The birefringent film exhibits excellent uniformity in the in-plane phase contrast, the thickness direction phase contrast and the orientation axis. |
