POLYMER FILM HAVING SCATTERING ANISOTROPY AND SURFACE LIGHT SOURCE DEVICE USING THE SAME

摘要

PROBLEM TO BE SOLVED: To provide a polymer film having scattering anisotropy suitable as a polarizing back light material. SOLUTION: The polymer film is prepared by stretching a crystalline polymer compound film and has a dispersion phase in the matrix of the polymer compound. The polymer film has the scattering anisotropy satisfying formula (1)-1: nyNy-znz or (1)-2: nyNy-znz and both of (2): |Ny-z-(ny+nz)/2|=0.03 and (3): |nx-Nx|0.05. In the formulae, nx is the refractive index in the direction with the highest refractive index in the film plane, ny is the refractive index in the direction perpendicular to the x direction in the plane and nz is the refractive index in the thickness direction in the matrix of the crystalline polymer compound, Ny-z is the average refractive index in the y-z plane and Nx is the refractive index in the x direction in the dispersion phase.