Patent ID: 6881457
Filing Date: 2005-04-19
Classification: C09K,G02B

Abstract:
1. An optical compensation film comprising a cellulose ester film comprising cellulose ester wherein (a) each of photoelastic coefficient C(md) in a mechanical direction and a photoelastic coefficient C(td) in a transverse direction of the cellulose ester film is 1×10 (b) a retardation R (c) a retardation R (d) each of a dimensional variation ratio S(md) in the mechanical direction and a dimensional variation ratio S(td) in the transverse direction of the cellulose ester film prior to and after being allowed to stand at ambient conditions of 80° C. and 90 percent relative humidity for 50 hours are −1 to 1 percent, and |S(md)|>|S(td)|; and (e) the cellulose ester simultaneously satisfies Formulas (IV) and (V); wherein nx is a refractive index in a transverse direction within a plane of the film, ny is a refractive index in a mechanical direction within a plane of the film, nz is a refractive index in a thickness direction of the film, and d is a thickness of the film in nm; and wherein X is a degree of substitution of an acetyl group and Y is a degree of substitution of a propionyl group or a butyryl group.