Method for making textured multilayer optical films

Abstract

Methods and apparatuses are provided for the manufacture of coextruded polymeric multilayer optical films. The multilayer optical films have an ordered arrangement of layers of two or more materials having particular layer thicknesses and a prescribed layer thickness gradient throughout the multilayer optical stack. The methods and apparatuses described allow improved control over individual layer thicknesses, layer thickness gradients, indices of refraction, interlayer adhesion, and surface characteristics of the optical films. The methods and apparatuses described are useful for making interference polarizers, mirrors, and colored films that are optically effective over diverse portions of the ultraviolet, visible, and infrared spectra.

1 . A method of making a textured multilayer optical film, said method comprising the steps of: 
 a. forming a multilayer web in which each layer is generally parallel to the major surface of adjacent layers; and    b. embossing the multilayer web with a pattern such that the embossed portion is no longer coplanar with the rest of the film and exhibits a different color than the rest of the film.    
   
   
       2 . The method of  claim 1 , wherein the embossing pattern comprises a fishnet pattern.  
   
   
       3 . The method of  claim 2 , wherein the embossing pattern comprises an emblem.