US Patent 7638205 Optical laminate film and method for producing same

An optical laminate film comprising a layer (A) comprising a material having a negative intrinsic birefringence value as a primary component; and a layer (B) comprising a transparent resin as a primary component which is laminated to at least one side of the layer (A). The optical laminate film satisfies the following conditions:(a) nz>(nx+ny)/2(b) 0≦ dispersion of retardation Re≦+10 nm,wherein retardation Re is represented by the formula [|nx−ny|×D] where D represents thickness (μm) of the laminated film, nz represents a refractive index in the thickness direction, and nx and ny each represent a refractive index, respectively in two directions orthogonal to each other and both of which are perpendicular to the thickness direction, all of the refractive indices being measured using light with wavelength of 550 nm.