Polyimide films from pyromellitic dianhydride and 2-2'-bis(perfluoroalkoxy)benzidines as alignment layers for liquid crystal displays
AssigneeE. I. Du Pont de Nemours and Company
InventorsBrian Carl Auman, Edgar Bohm
Life of this patent
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Abstract
A polyimide alignment film based on pyromellitic dianhydride and a 2,2'-bis(perfluoroalkoxy)benzidine, as major components, for use in liquid crystal display devices.
Claims10
A polyimide alignment film for aligning a liquid crystal layer of a liquid crystal display device comprising an aromatic tetracarboxylic acid component containing from 60 to 100 mole %, based on the total molar amount of aromatic tetracarboxylic acid component, of pyromellitic acid or a functional derivative thereof and an aromatic diamine component containing from 40 to 100 mole %, based on the total molar amount of aromatic diamine component, of a fluorinated aromatic diamine of formula (I) ##STR11## wherein R.sub.f is a linear or branched perfluorinated alkyl group containing from 1 to 4 carbon atoms and wherein said polyimide alignment film provides said liquid crystal layer with a tilt angle of from 3 to 25 degrees.
A liquid crystal display device comprising:
- (a) a liquid crystal layer having opposite sides;
- (b) a set of electrodes on either side of said liquid crystal layer;
- and
- (c) a polyimide alignment film layer, between each set of electrodes and said liquid crystal layer, comprising an aromatic tetracarboxylic acid component containing from 60 to 100 mole %, based on the total molar amount of aromatic tetracarboxylic acid component, of pyromellitic acid or a functional derivative thereof and an aromatic diamine component containing from 40 to 100 mole %, based on the total molar amount of aromatic diamine component, of a fluorinated aromatic diamine of formula (I) ##STR12## wherein R.sub.f is a linear or branched perfluorinated alkyl group containing from 1 to 4 carbon atoms and wherein said polyimide alignment film provides said liquid crystal layer with a tilt angle of from 3 to 25 degrees.
Dependencies are inferred from the claim text.