Patent ID: 8632863
Filing Date: 2014-01-21
Classification: B29C,B29D,B29K,B32B,C08J,C09K,G02B,G02F,Y10T

Abstract:
1. A polymer film comprising a cellulose acylate which is a protecting film for a polarizing plate and that has: a ratio R (VT/VM) of a sound velocity in a transverse direction VT to a sound velocity in a machine direction VM of from 1.05 to 1.50; a tensile modulus in a transverse direction of from 453 to 600 kgf/mm an in-plane retardation Re(λ) and a thickness-direction retardation Rth(λ) satisfying formula (I): wherein Re(λ) represents an in-plane retardation at a wavelength of λ (nm); and Rth(λ) represents a thickness-direction retardation at a wavelength of λ (nm); and an in-plane retardation Re(λ) and a thickness-direction retardation Rth(λ) satisfying formula (II): wherein Re(λ) represents an in-plane retardation at a wavelength of λ (nm); and Rth(λ) represents a thickness-direction retardation at a wavelength of λ (nm), and wherein an acyl substituent in the cellulose acylate is substantially an acetyl group alone, and a total degree of substitution thereof is from 2.80 to 2.99.