Dye compositions for anisotropic dye films, anisotropic dye films and polarizing elements

Abstract

To provide a dye composition for an anisotropic dye film, capable of forming an anisotropic dye film which has good heat resistance, has little defects and shows high dichroism; an anisotropic dye film formed by using such a composition for an anisotropic dye film; and a polarizing element employing such an anisotropic dye film.

1 . A dye composition for an anisotropic dye film, which comprises a dye and a compound having at least two groups selected from the group consisting of an acidic group, a basic group and a neutral group, wherein at least one of said at least two groups is a basic group.  
   
   
       2 . The dye composition for an anisotropic dye film according to  claim 1 , wherein the content of the compound to the dye is at least 0.05 and at most 4 by molar ratio.  
   
   
       3 . The dye composition for an anisotropic dye film according to  claim 1 , wherein the compound is a cyclic compound.  
   
   
       4 . The dye composition for an anisotropic dye film according to  claim 1 , wherein the compound is a hydroxylamine.  
   
   
       5 . The dye composition for an anisotropic dye film according to  claim 1 , wherein the compound is an amino acid.  
   
   
       6 . The dye composition for an anisotropic dye film according to  claim 1 , wherein the composition is a solution which further contains a solvent.  
   
   
       7 . The dye composition for an anisotropic dye film according to  claim 1 , wherein the dye is an acidic dye.  
   
   
       8 . The dye composition for an anisotropic dye film according to  claim 1 , wherein the dye is an azo dye.  
   
   
       9 . An anisotropic dye film formed by using the dye composition for an anisotropic dye film as defined in  claim 1 .  
   
   
       10 . The anisotropic dye film according to  claim 9 , formed by a wet system deposition method.  
   
   
       11 . The anisotropic dye film according to  claim 9 , wherein the film thickness is at most 30 μm.  
   
   
       12 . An anisotropic dye film comprising a dye and a compound having at least two groups selected from the group consisting of an acidic group, a basic group and a neutral group, wherein at least one of said at least two groups is a basic group.  
   
   
       13 . The anisotropic dye film according to  claim 9 , which has a dichroic ratio of at least 5.  
   
   
       14 . The anisotropic dye film according to  claim 12 , which has a dichroic ratio of at least 5.  
   
   
       15 . The anisotropic dye film according to  claim 9 , wherein the order parameter before a heat resistance test at 170° C. for 30 minutes, is at least 0.5, and the decrease in the order parameter after the heat resistance test is at most 7%.  
   
   
       16 . The anisotropic dye film according to  claim 12 , wherein the order parameter before a heat resistance test at 170° C. for 30 minutes, is at least 0.5, and the decrease in the order parameter after the heat resistance test is at most 7%.  
   
   
       17 . A polarizing element employing the anisotropic dye film as defined in  claim 9 .  
   
   
       18 . A polarizing element employing the anisotropic dye film as defined in  claim 12.