Cellulose acetate film, and polarizing plate and liquid crystal display device which are made using same

摘要

Provided is a cellulose acetate film which has excellent retardation properties and exhibits low haze even under high-temperature and high-humidity conditions and which, in an alkaline saponification step, causes little dissolution of the film itself or additives in a saponifying liquid. The cellulose acetate film is characterized by comprising: a cellulose acetate which has an acetyl substitution degree of 2.0 to 2.5; and 5 to 15% by mass (relative to the cellulose acetate) of a component which contains a compound represented by general formula (1) wherein m is 0 and a compound represented thereby wherein in is more than 0 at a ratio of 45:55 to 0:100. In general formula (1), G is a mono- or di-saccharide residue; X1 is —O—; R1 is —CO—R2; R2 is an aliphatic or aromatic group; m represents the total number of hydroxyl groups directly bonded to the mono- or di-saccharide residue; and n represents the total number of OR1 groups directly bonded to the mono- or di-saccharide residue, with the proviso that m and n satisfy fee relationships: 3≦m+n≦8 and n is not 0.

主权项

1. A cellulose acetate film comprising:
a cellulose acetate having an acetyl substitution degree of 2.0 to 2.5; and at least one compound having a structure represented by Formula (1) and having a mixing ratio of a component exhibiting m=0:a component exhibiting m>0 of 45:55 through 0:100, a content of the compound being 5 to 15% by mass based on a mass of cellulose acetate,
(HO)m-G-(X1—R1)n  Formula (1)wherein
G represents a residue of a mono- or di-saccharide, X1 represents —O—, R1 represents —CO—R2, R2 represents an aliphatic group or an aromatic group, m represents a total number of a hydroxyl group directly bonded to the mono- or di-saccharide, n represents a total number of OR′ group directly bonded to the mono- or di-saccharide, 3≦m+n≦8, and n is not zero, wherein the compound represented by Formula (1) exhibits an average log P value of 7.5 or more, wherein an in-plane retardation Ro of the film defined by the following Equation (I) is in the range of 30 to 200 nm, and a thickness direction retardation Rt of the film defined by the following Equation (II) is in the range of 70 to 300 nm,
Ro=(nx−ny)×d,  Equation (I)Rt={(nx+ny)/2−nz}×d,  Equation (II)and in the equations, nx is an in-plane refractive index in the slow axis direction of the film, ny is an in-plane refractive index in the fast axis direction perpendicular to the slow axis direction of the film, nz is a refractive index in the film thickness direction of the film, and d is a thickness (nm) of the film,
wherein the cellulose acetate film comprises 5 to 15% by mass based on the mass of the cellulose ester of a compound represented by Formula (1) and exhibiting an average log P value of 7.5 or more.