PROCESS FOR THE PREPARATION OF PLASTIC FILMS WITH MODIFIED OPTICAL CHARACTERISTICS

摘要

An optically virtually isotropic plastic film, in particular for use in liquid crystal displays, can be produced by a method in which first an optically uniaxial birefringent plastic film is produced by casting or extrusion, and then irreversible molecular reorientation is produced in layers of the film close to the surface by heating or by immersion in a solvent or swelling agent. This reoriented structure is retained after cooling or drying of the film, and results in the birefringence (anisotropy) initially present being eliminated or compensated.