| 摘要 |
The present invention relates to a retardation film and a liquid crystal display device and, more specifically, to: an isotropic cellulose acetate film containing a hydroxyl group-ended ester-based plasticizer for an optical film represented by the following chemical formula 1 and meeting the following mathematical formula 1; and a liquid crystal display device containing the same. The present invention is very effective at controlling phase differences in the range of 0≤Re(550)≤20 and -30≤Rth(550)≤30. [Chemical formula 1] M-(G)n-M wherein M is a C4-14 isopropylcarbonyloxy or an ester compound thereof, or a hydroxyl group; G, which is a C8-16 divalent saturated linking group having an atom number of 20-40, is a 2,2,4-trimethyl-1,3-pentanylene group or ethylene glycol and a dicarboxylic acid; and n is an integer of 1 or more. [Mathematical formula 1] (1) Re(λ) = (nx - ny) × d (2) Rth(λ) = ((nx + ny)/2 - nz) × d (3) 0≤Re(550)≤20, -30≤Rth(550)≤30 (4) │Re(450)-Re(550)│≤10, │Rth(450)-Rth(550)│≤15 wherein Re(λ) is an in-plane retardation value at a reference wavelength λ nm; and Rth(λ) is a retardation value in the thickness direction at a reference wavelength λ nm. nx is a refractive index in the in-plane x-axis direction of the film, ny is a refractive index in the in-plane y-axis direction of the film, nz is a refractive index in the thickness direction of the film, and d is the thickness of the film. |
