A liquid crystal display including a first substrate, a thin film transistor disposed on the first substrate, a first electrode connected to the thin film transistor, and a first alignment layer disposed on the first electrode, wherein the first alignment layer includes polyimide and a capping group connected to a main chain end of the polyimide, and the capping group contains at least one of a first compound represented by the following Chemical Formula 1, and a second compound represented by the following Chemical Formula 2: ##STR00001## A1 and A2 are, independently of each other, an aromatic compound having 4 to 20 carbon atoms or an aliphatic cyclic compound having 4 to 20 carbon atoms; and B1 and B2 are, independently of each other, a crosslinking reaction group containing an alkylene group (—C.sub.nH.sub.2n—, n is a natural number).

Disclosed therein are a photoalignment polyimide copolymer making it easier to form a liquid crystal alignment layer with excellences in alignment properties, thermal and structural stabilities, and adhesiveness to a substrate, and a liquid crystal alignment layer using the same. The photoalignment polyimide copolymer includes all the three types of repeating units each having a defined structure.

An alignment coating structure for a substrate includes at least one substrate, and each of the substrates has a blind via; an alignment plate has at least one opening; the alignment plate covers on the substrate; the opening corresponds to the blind via; and a printing mechanism for transferring polyimide liquid on the alignment plate to a region out of the blind via on the substrate according to a preset printing direction. An alignment coating method for a substrate, including disposing an opening on an alignment plate makes the opening face a blind via in alignment coating. This makes the location where the blind via will not be printed by polyimide liquid, thereby increasing the liquid crystal arrangement randomness of the location where the blind via is, making the optical path be scattered to a certain extent, thereby prevent from occurrence of a Newton's ring or a rainbow pattern.

An alignment film composition includes a copolymer of a dianhydride-based compound and a diamine-based compound, and a cross-linker. The copolymer has a structure represented by Chemical Formula Ia or Chemical Formula Ib, and the cross-linker is represented by Chemical Formula IIa or Chemical Formula IIb:

##STR00001##

Disclosed are an alignment layer and a liquid crystal display having the same. The alignment layer comprises a polyimide compound having an azo group and exhibiting optical alignment characteristics and a discotic liquid crystal compound exhibiting optical anisotropy. The liquid crystal display comprises first and second substrates facing each other, liquid crystal aligned between the first and second substrates, and an alignment layer formed on at least one surface of the first and second substrates. The alignment layer is adjacent to the liquid crystal and has optical alignment characteristics and optical anisotropy.

The present invention provides an alignment film having excellent heat resistance and capable of suppressing generation of defects such as image sticking and stain, and a liquid crystal display device including the alignment film. The alignment film of the present invention contains a copolymer containing a repeating structural unit represented by the following formula (1), wherein X1 and X2 may be the same as or different from each other and are each represented by, for example, any of the following formulas (X-P1) to (X-P4); and Y is represented by, for example, any of the following formulas (Y-P1) to (Y-P4).

##STR00001##

A liquid crystal display device includes a first substrate, a first alignment layer on the first substrate, a second substrate facing the first substrate, a second alignment layer on the second substrate, and a liquid crystal layer between the first substrate and the second substrate and including liquid crystal molecules. The first alignment layer and the second alignment layer include a polymer including at least of polyamic acid, polyimide, and a combination including at least one of the foregoing polymers, and a compound including an epoxy cross-linker represented by Chemical Formula 1.

The invention relates to a liquid crystal alignment agent which provides a polymer composition (A), a solvent (B), and a poly(oxyalkyleneglycol)dialkylether compound (C); wherein the number average molecular weight of the poly(oxyalkyleneglycol)dialkylether compound (C) is from 250 to 2000. The invention also provides a liquid crystal alignment film made by the liquid crystal alignment agent as mentioned above and a liquid crystal display element which provides the liquid crystal alignment film, and the liquid crystal display element has high voltage holding rate and low ion density.

An alignment film for liquid crystal display device includes a first portion positioned towards to the liquid crystal layer and a second portion positioned away from the liquid crystal layer. The first portion provides improved anchoring force while the second portion exhibits a lower volume resistance than the first portion. Thus, AC image sticking and DC image sticking can be minimized at the same time.

A photoalignment agent includes a polyimide and a capping terminal connected to a main chain end terminal of the polyimide. The capping terminal includes an alkylene group (—C.sub.mH.sub.2m—, m is a natural number) and a core stereo unit in a dendrimer format. A liquid crystal display includes a first substrate, a thin film transistor disposed on the first substrate, a first electrode connected to the thin film transistor, and a first alignment layer disposed on the first electrode. The first alignment layer includes a polyimide and a capping terminal connected to a main chain end terminal of the polyimide. The capping terminal includes an alkylene group (—CmH2m-, m is a natural number) and a core stereo unit in a dendrimer format.