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.

The present invention provides a liquid crystal display device that is less likely to have display failures and has high reliability and excellent light resistance in aging. The present invention relates to a liquid crystal display device, including: a pair of substrates; a liquid crystal layer containing liquid crystal molecules and interposed between the pair of substrates; and an alignment control layer for perpendicularly aligning the liquid crystal molecules, the alignment control layer being formed by polymerizing a monofunctional monomer and a polyfunctional monomer in a liquid crystal composition containing the liquid crystal molecules, the monofunctional monomer, and the polyfunctional monomer, the polyfunctional monomer generating a radical by annealing and irradiation with light at not less than 340 nm, the monofunctional monomer having a biphenyl skeleton as a core and a polymerizable group bonded to the biphenyl skeleton directly or indirectly via a spacer.

A liquid crystal display device includes a TFT substrate having a first alignment film and an opposing substrate having a second alignment film with liquid crystals sandwiched therebetween. One of the first and second alignment films, comprises a first polyimide produced via polyamide acid ester containing cyclobutane as a precursor and a second polyimide produced via polyamide acid as a precursor. The polyamide acid has a higher polarity than that of the polyamide acid ester. The one of the first and second alignment films is responsive to photo-alignment. A first side of the one of the first and second alignment films is adjacent to the liquid crystals, and a second side thereof is closer to one of the TFT substrate and the counter substrate than the first side. The first side contains more of the first polyimide and less of the second polyimide than the second side.

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##

The present invention relates to a PSA-mode liquid crystal display device including a polymer produced by polymerizing a polymerizable compound by energy ray irradiation in a state in which a mixture of the polymerizable compound and a liquid crystal composition is held between the first substrate and the second substrate, the polymer having a number-average molecular weight of 50,000 or more in terms of polystyrene. In a PSA-mode display device in which alignment of liquid crystal molecules substantially vertically aligned between the substrates is controlled by applying a voltage, a pre-tilt angle can be properly given without being inhibited. Therefore, the present invention provides a PSA-mode display device with good alignment stability, uniform alignment within the substrates, and no or suppressed display defects and a method for producing the same.

To provide a liquid crystal display device having excellent liquid crystal vertical alignment properties, good transparency when a voltage is applied and good scattering properties when no voltage is applied, and good adhesion with the liquid crystal layer. The liquid crystal display device has a liquid crystal layer formed by irradiating and curing with ultraviolet rays a liquid crystal composition containing a liquid crystal and a polymerizable compound disposed between a pair of substrates provided with electrodes, and at least one of the substrates is provided with a liquid crystal alignment film to vertically align a liquid crystal. The liquid crystal composition contains a compound represented by the formula [1], and the liquid crystal alignment film is obtained from a liquid crystal alignment treating agent containing a polymer having a side chain structure represented by the following formula [2-1] or formula [2-2], and a side chain structure represented by the following formula [3]:

X.sup.1—X.sup.2—X.sup.3—X.sup.4—X.sup.5—X.sup.6x.sup.7.sub.pX.sup.8   [1]

(X.sup.1: the formula [1-a] to formula [1-g], etc., X.sup.2, X.sup.3, X.sup.4 and X.sup.6: a single bond, etc., X.sup.5 and X.sup.7: a benzene ring, etc., X.sup.8: a C.sub.1-18 alkyl group, etc.),

##STR00001##

(X.sup.A: H, etc., X.sup.B: a benzene ring, etc., X.sup.C: a C.sub.1-18 alkyl group, etc.),

—Y.sup.1—Y.sup.2—Y.sup.3—Y.sup.4Y.sup.5.sub.nY.sup.t   [2-1]

(Y.sup.1, Y.sup.2 and Y.sup.3: a single bond, etc., Y.sup.4 and Y.sup.5: a benzene ring, etc., Y.sup.6: a C.sub.1-18 alkyl group, etc.,

—Y.sup.7—Y.sup.8   [2-2]

(Y.sup.7: a single bond, Y.sup.8: a C.sub.8-22 alkyl group, etc.).

A display device includes a substrate, a thin film transistor positioned on the substrate, a pixel electrode connected to the thin film transistor, an alignment layer positioned on the pixel electrode, a liquid crystal layer including liquid crystal molecules formed on the alignment layer and positioned in a plurality of microcavities, a roof layer positioned such that the roof layer is spaced apart from the pixel electrode with a microcavity interposed therebetween, and an overcoat positioned on the roof layer and covering a trench positioned between the plurality of microcavities, in which in the liquid crystal layer, a pre-tilt angle manifestation group positioned to be adjacent to the alignment layer is formed, and the pre-tilt angle manifestation group includes a polymer of a compound represented by Chemical Formula 1.

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.

A material from which a cured film exhibiting high solvent resistance, liquid crystal-alignment performance, heat resistance and high transparency can be formed. A composition for forming a thermoset film having photo alignment properties, including: a component (A) that is an acrylic copolymer having a photodimerizing moiety and a thermal cross-linking moiety; and a component (B) that is a cross-linking agent.