Patent ID: 9223070
Filing Date: 2015-12-29
Classification: B32B,C09K,G02B,G02F

Abstract:
1. An optical film comprising a cellulose ester resin which has an average degree of substitution by acetyl group of 2.0 to 2.6, the optical film having an in-plane phase difference value (Ro) at 23° C., 55% RH and at a measurement wavelength of 590 nm of 30 to 100 nm, a thickness-wise phase difference value (Rth) of 70 to 400 nm, and a thickness of 15 to 50 μm, the optical film satisfying a formula (I) below: in the formula, assuming now an angle of incidence of light on a surface of the film as 0°, S(bs) represents an integral of light obtained by measuring an amount of back-scattered light over a range of angle of emergence from 25° to 85° at 1° intervals, at a measurement wavelength of 590 nm, and at a point 300 mm away from the surface of the film, and S(T) represents a total amount of incident light onto the surface of the film from a light source placed 600 mm away therefrom, where, an angle of emergence of back-scattered light, which is in parallel with a normal line on the surface of the optical film, and propagates in a direction reverse to the incident light, is assumed as 0°, and an angle of emergence of forward-scattered light, which is in parallel with the normal line, and propagates in the direction same as the direction of propagation of the incident light, is assumed as 180°, and wherein the optical film further comprises calcium, magnesium, and acetic acid, and a total content of the calcium and the magnesium and a content of the acetic acid satisfy Relational Expression (a):