Patent ID: 9195090
Filing Date: 2015-11-24
Classification: B29C,B29D,B29K,B32B,C08J,C09K,G02B,G02F,Y10T

Abstract:
1. A polymer film 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 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 Re(n) satisfying formula (III): wherein Re(n) means the in-plane retardation (nm) of the film having been stretched by n(%), while Re(0) means the in-plane retardation (nm) of the unstretched film, and wherein the polymer film comprises a cellulose acylate which comprises at least two of the acyl substituents consisting of acetyl, propionyl and butanoyl groups, and a total degree of acyl substitution thereof is from 2.50 to 3.00.