| 摘要 |
PROBLEM TO BE SOLVED: To provide an optical film, manufacturing method thereof, and a polarizing plate using the optical film, capable of obtaining a polarizing plate in which optical leakage in crossed Nicol state is less even if observed obliquely as well as squarely, and revealing excellent polarizing characteristics. SOLUTION: The optical film is formed by fusion-extrusion of an amorphous thermo-plastic resin. The thickness of the film is less than 100 μm, with normal retardation R(0) as 10 nm or less. The retardation Rs(40) and Rf(40) that are measured in the direction inclined 40 deg. toward phase-advancing axis and phase- lagging axis, respectively, from the normal direction of the film are R(0)+6 nm or less, with dislocation of optical axis as ±10 deg. or less. The resin of the film is a norbornene-based resin. Related to the method of manufacturing the optical film, the temperature of film just before the contact point to a cooling roll is 'Tg of the resin' + 50 deg.C or above when the film of the resin extruded into a sheet is brought into tight contact with the cooling roll. Related to the polarizing plate, the optical film is laminated at least on one side of a polarizer. |
