Formation of polymerizable layer on a photo-alignment layer of liquid crystal cell and its image sticking characteristics

Abstract

The effect for polymerizable layer on a vertical-type photo-alignment layer was investigated from the point of image sticking characteristics. Fabrication process of the polymerizable layer is followings; photo-alignment treatment is firstly carried out by exposing polarized ultraviolet (UV) from the oblique direction. After construction of the liquid crystal (LC) cell, the LC material including monomers is injected, and unpolarized UV is exposed for formation of the polymerizable layer. For avoiding pretilt angle shift during the exposure, fast rate constant of polymerization is necessary, and mixed monomers 4,4’-dimethacryloyl-oxy-biphenyl (4,4’-DMABiph) and 4,4’-dimethacryloyl-oxy-benzilketal (4,4’-DMABzk) are appropriate for obtaining small level of image sticking parameters. As the image sticking parameters, residual direct current voltage (V_rDC) and difference in pretilt angle (Δtilt) before and after application of alternate current voltage were evaluated, and the results of V_rDC and Δtilt indicated that 6% 4,4’-DMABzk in the mixed monomers 4,4’-DMABiph and 4,4’-DMABzk would be useful for obtaining the small level of image sticking.

Keywords:

• liquid crystal cell
• photo-alignment layer
• polymerizable layer
• monomers
• image sticking
• 4,4’-dimethacryloyl-oxy-benzilketal (4,4’-DMABzk)

Disclosure statement

No potential conflict of interest was reported by the authors.