Patent ID: 8470448

Claim:
An acryl resin-containing film satisfying the following equations (1) to (4), and exhibiting a tension softening point of 105 to 145° C. and a photoelastic coefficient of −5.0×10 −8 to 8.0×10 −8 cm 2 /N and not causing a ductile fracture: | R o (589)|≦10 nm Equation (1) | R th (589)|≦20 nm Equation (2) | R o (480)− R o (630)|≦5 nm Equation (3) | R th (480)− R th (630)|≦10 nm Equation (4) wherein R o =(nx−ny)×d, R th =[(nx+ny)/2−nz]×d; nx is a refractive index in a direction of a slow axis in a plane of the film, ny is a refractive index in a direction perpendicular to the slow axis in the plane, nz is a refractive index in a direction of thickness; d is a thickness of the film; and numerical values of 589, 480 and 630 in parentheses are each a wavelength (nm) of a light used to measure an individual birefringence, and wherein the acryl resin-containing film comprises an acryl resin (A), a first species of a cellulose ester resin (B1) and at least one resin selected from the group consisting of a second species of the cellulose ester resin (B1), a cellulose ester resin (B2), and a resin (D) which is other than the resins (A), (B1) and (B2), and exhibits an Abbe's number of 30 to 60; the acryl resin (A) has a weight average molecular weight of 80000 to 1000000; the cellulose ester resin (B1) has a weight average molecular weight (Mw) of 75000 to 250000, and exhibits a total degree of substitution with acyl groups (T1) of 2.00 to 2.99, in which a substitution degree with an acetyl group (ac) is from 0.10 to 1.89 and a substitution degree with acyl groups having 3 to 7 carbon atoms (r) is from 1.10 to 2.89; the cellulose ester resin (B2) exhibits a total substitution degree of the acryl group (T2) of 1.00 to 2.99, a substitution degree of the acetyl group (ac) of 0.1 to 2.99, and a substitution degree with an acyl group other than the acetyl groups of 0 to 2.89; and the acryl resin-containing film exhibits a haze value of less than 2%.