PRODUCTION METHOD FOR PHASE SHIFT FILM, AND PRODUCTION METHOD FOR CIRCULAR POLARIZING PLATE

摘要

Provided is a method whereby a phase shift film having reduced biaxiality, a small Nz coefficient, and a slow axis lying in a diagonal direction can be produced at high production efficiency. This production method for phase shift film comprises: clipping the left and right side edge portions of a film to be stretched, respectively within left and right clips of variable pitch type having a clip pitch that is variable in the longitudinal direction; preheating the film; with the location at which the clip pitch of either the left or right clips begins to decrease and the location at which the clip pitch of the other clips begins to decrease positioned at different positions in the longitudinal direction, the clip pitch of the respective clips are reduced to a prescribed pitch, stretching the film diagonally; and the clips which clip the film are released.