Optical alignment method and liquid crystal display element

Abstract

An optical alignment method which develops a pretilt angle by batch plane exposure without tilting a substrate. This optical alignment method provides liquid crystal aligning capability to the surface of a polymer film by exposing the surface of the polymer film through a slit exposure mask while the surface of the polymer film and the slit exposure mask are moved relative to each other substantially at a fixed rate. Alternatively, liquid crystal aligning capability is provided to the surface of the polymer film by exposing the surface of the polymer film through an optical exposure pattern while the optical exposure pattern having a plurality of lines with a certain width at certain intervals is formed on the surface of the polymer film continuously.

1 . An optical alignment method comprising providing liquid crystal aligning capability to the surface of a polymer film by exposing the surface of the polymer film to radiation with an irradiation intensity distribution while the surface of the polymer film and radiation are moved relative to each other substantially at a fixed rate without inclination of the surface of the polymer film.  
   
   
       2 . The optical alignment method of  claim 1 , wherein liquid crystal aligning capability is provided to the surface of the polymer film by exposing the surface of the polymer film to radiation through a slit exposure mask while the surface of the polymer film and the slit exposure mask are moved relative to each other substantially at a fixed rate.  
   
   
       3 . The optical alignment method of  claim 1 , wherein the exposure of the surface of the polymer film to radiation with an irradiation intensity distribution is carried out by forming a projection pattern on the polymer film by a projector and by exposing the polymer film to radiation while the surface of the polymer film and the projection pattern are moved relative to each other substantially at a fixed rate.  
   
   
       4 . The optical alignment method of  claim 1 , wherein liquid crystal aligning capability and the developability of a pretilt angle of 80° or more are provided to the surface of the polymer film.  
   
   
       5 . The optical alignment method of  claim 4 , wherein the polymer film is made from a polymer having (A) a structure crosslinkable by light and (B) at least one group selected from the group consisting of a fluorine-containing organic group, alkyl group having 10 to 30 carbon atoms and alicylic organic group having 10 to 30 carbon atoms.  
   
   
       6 . The optical alignment method of  claim 1 , wherein the polymer film provided with liquid crystal aligning capability on the surface is a liquid crystal alignment film.  
   
   
       7 . A liquid crystal display element comprising a liquid crystal alignment film formed by the optical alignment method of  claim 1 .  
   
   
       8 - 26 . (canceled)  
   
   
       27 . The optical alignment method of  claim 5 , wherein recurring units of structure (A) account for 10-95 percent of the total of all recurring units, and recurring units having structure (B) account for 5-50 percent of the total of all recurring units.  
   
   
       28 . The optical alignment method of  claim 1 , wherein said surface of the polymer film is exposed to radiation through a slit exposure mask, and wherein said polymer film remain stationary and said slit exposure mask is moved relative to the surface of the polymer film during exposure.  
   
   
       29 . The optical alignment method of  claim 1 , wherein said polymer film is located on a transparent conductive film side of a substrate.  
   
   
       30 . The optical alignment method of  claim 1 , wherein the thickness of the polymer film is 0.001-1 μm.  
   
   
       31 . The optical alignment method of  claim 1 , wherein said substrate is transparent glass or a transparent plastic film.  
   
   
       32 . The optical alignment method of  claim 1 , wherein the surface of the polymer film and radiation are moved relative to each other at a rate of 5 μm/sec to 1 mm/sec.  
   
   
       33 . The optical alignment method of  claim 1 , wherein said polymer film is at a temperature ranging from its glass transition temperature to a temperature 100 degrees centigrade higher than its glass transition temperature during exposure.  
   
   
       34 . The optical alignment method of  claim 1 , wherein said radiation is polarized light.  
   
   
       35 . The optical alignment method of  claim 1 , wherein said radiation is non-polarized light.  
   
   
       36 . The optical alignment method of  claim 1 , wherein said radiation is polarized ultraviolet radiation having a wavelength of 320 to 450 nm.  
   
   
       37 . The optical alignment method of  claim 1 , wherein the thickness of the polymer film is 0.001-1 μm, the surface of the polymer film and radiation are moved relative to each other at a rate of 5 μm/sec to 1 mm/sec, and the radiation is polarized light.  
   
   
       38 . The optical alignment method of  claim 28 , wherein the thickness of the polymer film is 0.001-1 μm, the surface of the polymer film and radiation are moved relative to each other at a rate of 5 μm/sec to 1 mm/sec, and the radiation is polarized light.  
   
   
       39 . The optical alignment method of  claim 38 , wherein said radiation is polarized ultraviolet radiation having a wavelength of 320 to 450 nm.