Patent ID: 7755726

Claim:
A transparent polymer film satisfying all the following formulae (I)-(III), and having a moisture permeability of at least 500 g/(m 2 ·day) in terms of the thickness of 80 μm at 40° C. and a relative humidity of 90%: Re< 5, and | Rth|< 20 (I) | Re (700)− Re (400)|<5, and (II) | Rth (700)− Rth (400)|<20 | Re (10%)− Re (80%)|<5, and (III) | Rth (10%)− Rth (80%)|<15 wherein Re and Rth represent in-plane retardation and thickness-direction retardation (unit: nm) respectively at a measuring wavelength of 632.8 nm, Re(λ) and Rth(λ) represent in-plane retardation and thickness-direction retardation (unit: nm) respectively at a wavelength of λ (unit: nm), Re(H %) and Rth(H %) represent in-plane retardation and thickness-direction retardation respectively at a relative humidity H (unit: %) and a measuring wavelength of 632.8 nm.