Patent ID: 8445081

Claim:
A polarizing plate protective film comprising: a cellulose ester; a polyester having no aromatic ring and having a weight average molecular weight of not less than 500 and not more than 10,000, the polyester containing a compound represented by Formula (B1) or (B2): B 1 -(G-A-) m G-B 1 Formula (B1) wherein B 1 is mono-carboxylic acid having 1-12 carbon atoms; G is dihydric alcohol having 2-12 carbon atoms; and A is dibasic acid having 2-12 carbon atoms; neither of B 1 , G and A contains an aromatic ring; and m is a repeating number that is an integer not less than 1: B 2 -(A-G-) n A-B 2 Formula (B2) wherein B 2 is monohydric alcohol having 1-12 carbon atoms; G is dihydric alcohol having 2-12 carbon atoms; A is dibasic acid having 2-12 carbon atoms; neither of B 2 G and A contains an aromatic ring; and n is a repeating number that is an integer not less than 1; a saccharide ester compound in which all or a part of OH groups in Compound (A) or in Compound (B) are esterified, wherein Compound (A) consists of one of a furanose structure and a pyranose structure, and Compound (B) consists of two to twelve of at least one type of a furanose structure and a pyranose structure which are bonded in Compound (B); wherein the polarizing plate protective film has a thickness of 20 μm to 60 μm and exhibits Ro of 0 to 5 nm and Rt of −10 to +20 nm, which are represented by the following equations: Ro =( nx−ny )× d Equation (i) Rt =(( nx+ny )/2 −nz )× d Equation (ii) wherein, Ro is a retardation value in the film plane; Rt is a retardation value in the thickness direction; nx is a refractive index in the slow axis direction in the film plane; ny is a refractive index in the fast axis direction in the film plane; nz is a refractive index in the film thickness direction (refractive index was measured under an environment of 23° C. and 55% RH, at a wavelength of 590 nm); and d is a film thickness (nm)), wherein the polarizer protective film has a variation less than 10 nm in thickness direction retardation value due to a humidity change between 20% RH at 23° C. and 80% RH at 50° C. when the film has a film thickness of 40 μm.