Liquid crystal display and method for manufacturing same
A liquid crystal display is provided which is capable of reducing the occurrence of defective display due to variations in the initial alignment direction of a liquid crystal alignment control film in a liquid crystal display of an IPS scheme, realizing the stable liquid crystal alignment, providing excellent mass productivity, and having high image quality with a higher contrast ratio. The liquid crystal display has a liquid crystal layer disposed between a pair of substrates, at least one of the substrates being transparent, and an alignment control film formed between the liquid crystal layer and the substrate. At least one of the alignment control films 109 comprises photoreactive polyimide and/or polyamic acid provided with an alignment control ability by irradiation of substantially linearly polarized light.
1. An photo alignment film material for an IPS type liquid crystal display device, adapted to be an alignment control film of a liquid crystal display to drive a liquid crystal with an electric field arising between a pair of electrodes formed on a substrate, comprising a polyamic acid or polyimide that includes cyclobutanetetracarboxylic acid dianhydride and/or its derivative and aromatic diamine; and
wherein the cyclobutanetetracarboxylic acid dianhydride and/or its derivative is a compound represented by a formula [1]:
where R 1 , R 2 , R 3 , and R 4 of the compound of the formula [1] each independently represent a hydrogen atom, a fluorine atom, an alkyl group or alkoxyl group with a carbon number of 1 to 6, with the proviso that at least one of R 1 , R 2 , R 3 , and R 4 of the compound of formula [1] is not hydrogen,
wherein the aromatic diamine compound contains at least one of compounds selected from a group of compounds consisting of ones represented by formulas [2] to [16]:
where R 1 , R 2 , R 3 and R 4 of the compounds represented by formulas [2] to [16] each independently represent a hydrogen atom, a fluorine atom, an alkyl group or alkoxyl group with a carbon number of 1 to 6, or vinyl group
{—(CH 2 ) m —CH═CH 2 , m=0, 1, 2} or a group represented by {—(CH 2 ) n — C≡CH, n=0, 1, 2}, and in the formula [5], X represents a bond group —S—, —CO—, or —NH—.
2. The photo alignment film material for an IPS type liquid crystal display device according to claim 1 , wherein said alignment control film is polyamic acid or polyimide containing at least 50% of a repeated structure of polyamic acid or polyimide comprising said cyclobutanetetracarboxylic acid dianhydride and/or its derivative and said aromatic diamine.
3. The photo alignment film material for an IPS type liquid crystal display device according to claim 1 , having a glass transition temperature equal to or higher than 250° C.
4. The photo alignment film material for an IPS type liquid crystal display device according to claim 1 , wherein said polyamic acid or polyimide is a photoreactive polyamic acid or polyimide.
5. The photo alignment film material for an IPS type liquid crystal display device according to claim 1 , said film having been subjected to alignment processing by irradiating the film with polarized light having a wavelength in a range of 200 to 400 nm.
6. The alignment control film according to claim 5 , wherein said alignment processing further comprises applying at least one of heating, irradiation of infrared rays, irradiation of far infrared rays, irradiation of electron beams and irradiation of radioactive rays when irradiating the film with the polarized light.
7. The photo alignment film material for an IPS type liquid crystal display device according to claim 1 , adapted to be an alignment control film of a liquid crystal display having an electric field parallel to said substrate.
8. The photo alignment film material for an IPS type liquid crystal display device according to claim 1 , wherein the alignment control film has a thickness of from 1 nm to 100 nm.
9. A varnish comprising the photo alignment film material according to claim 1 mixed with a solvent.
10. The photo alignment film material for an IPS type liquid crystal display device according to claim 8 , wherein said thickness is 1 to 30 nm.
11. The photo alignment film material for an IPS type liquid crystal device according to claim 1 ,
wherein the cyclobutanetetracarboxylic acid dianhydride has the following structure:
12. The photo alignment film material for an IPS type liquid crystal device according to claim 1 ,
wherein the aromatic diamine compound has the following structure: