Patent ID: 9081133
Filing Date: 2015-07-14
Classification: C09K,G02B,G02F

Abstract:
1. A polarizing plate protective film, comprising: a cellulose ester film containing polyester which has no aromatic ring in its molecule and exhibits negative birefringence; and an actinic radiation cured resin layer serving as a hard coat layer provided on the cellulose ester film; wherein the cellulose ester film is stretched by 1.01 times or more in a width direction and exhibits a retardation value Ro, defined by Expression (I), of 0 to 10 nm and a retardation value Rt, defined by Expression (II), of −20 to 20 nm: wherein nx is a refractive index in a slow axis direction in a plane of the polarizing plate protective film, ny is a refractive index in a direction orthogonal to the slow axis in the plane, nz is a refractive index in a film thickness direction, and d is a film thickness (nm), and wherein a difference value ΔRt defined by Expression (III) is less than 15 nm, where Rt (23° C., 80% RH) represents a retardation value Rt measured after the polarizing plate protective film was placed under an environment of 23° C. and 80% RH for 10 hours, and Rt (23° C., 20% RH) represents a retardation value Rt measured after the polarizing plate protective film was placed under an environment of 23° C. and 20% RH for 10 hours, wherein the polyester is represented by Formula (3) or (4): wherein B1 is a monocarboxylic acid, G is a dihydric alcohol, A is a dibasic acid; B wherein B wherein the polyester represented by Formula (3) or (4) counteracts an increase in each of the retardation values (absolute value) Ro and Rt of the cellulose ester film when the cellulose ester film is stretched.