Post-formable multilayer optical films and methods of forming

Abstract

Articles including post-formed multilayer optical films with layers of at least one strain-induced birefringent material, methods of manufacturing such articles by post-forming multilayer optical films, and multilayer optical films that are particularly well-suited to post-forming operations are disclosed. The articles, methods and multilayer optical films of the present invention allow for post-forming of multilayer optical films including strain-induced index of refraction differentials while retaining the desired optical properties of the multilayer optical films.

1 . An article comprising a portion formed from a moldable material and a multilayer optical film having a first major surface attached to the portion and a second major surface disposed generally opposite the first major surface, the multilayer optical film comprising an optical stack having a plurality of layers, the layers comprising at least one birefringent polymer and at least one second polymer, wherein the optical stack comprises a first index of refraction differential between layers in the optical stack along a first axis and a second index of refraction differential along a second axis that is perpendicular to the first axis, wherein the second index of refraction differential is different than the first index of refraction differential, and wherein at least the second major surface comprises a three-dimensional permanent deformation. 
   
   
       2 . The article of  claim 1 , wherein the three-dimensional permanent deformation has a curved shape. 
   
   
       3 . The article of  claim 1 , wherein the three-dimensional permanent deformation comprises a depressed area. 
   
   
       4 . The article of  claim 1 , wherein the three-dimensional permanent deformation comprises a raised area. 
   
   
       5 . The article of  claim 1 , wherein the three-dimensional permanent deformation comprises a raised area in the second major surface and a depressed area in the first major surface, wherein the raised area is disposed opposite the depressed area. 
   
   
       6 . An article comprising a multilayer optical film comprising an optical stack having a plurality of layers, the layers comprising at least one birefringent polymer and at least one second polymer, wherein the optical stack comprises a first index of refraction differential between layers in the optical stack along a first axis and a second index of refraction differential along a second axis that is perpendicular to the first axis, wherein the second index of refraction differential is different than the first index of refraction differential, and wherein the first and second major surfaces each comprise a plurality of undulations comprising arcuate portions, valley portions, and intermediate portions connecting the arcuate portions and the valley portions. 
   
   
       7 . The article of  claim 6 , wherein the undulations have sinusoidal shapes. 
   
   
       8 . The article of  claim 6 , wherein the arcuate portions and the valley portions are generally flat. 
   
   
       9 . The article of  claim 6 , wherein the multilayer optical film comprises a reflective polarizer. 
   
   
       10 . The article of  claim 6 , wherein the multilayer optical film comprises a mirror.