CELLULOSE ESTER FILM, OPTICAL COMPENSATION SHEET AND ELLIPTICALLY POLARIZING PLATE

摘要

PROBLEM TO BE SOLVED: To control the relation between the retardation (Rth) in a thickness direction and the retardation (Re) in a plane direction of a cellulose ester film. SOLUTION: The tensile elastic modulus of the cellulose ester film in the machine direction is controlled to 360 to 480 kgf/mm2, and the tensile elastic modulus in the direction perpendicular to the machine direction is controlled to 260 to 440 kgf/mm2. Moreover, the ratio of the tensile elastic modulus in the machine direction to the modulus in the direction perpendicular to the machine direction is controlled to 0.80 to 1.36.