The present invention relates to a polymer having excellent liquid crystal alignment and electrical properties and thus is suitable for use as a liquid crystal alignment agent, a liquid crystal alignment agent containing the same, a liquid crystal aligning film formed from the liquid crystal alignment agent, and a liquid crystal display device containing the liquid crystal aligning film.

This liquid crystal display device is provided with: a first substrate; a second substrate that faces the first substrate; a liquid crystal layer that is arranged between the first substrate and the second substrate; and liquid crystal alignment films (a first alignment film and a second alignment film) that are formed on the first substrate and the second substrate, respectively. The first substrate and the second substrate respectively have an electrode on the liquid crystal layer side surfaces. At least one of the first alignment film and the second alignment film is a photo-alignment film. Each pixel has a plurality of alignment regions, in which the alignment directions of liquid crystal molecules are different from each other, within the pixel. The liquid crystal layer has negative dielectric anisotropy, while having a thickness of 2.9 m or less.

The present invention provides a liquid crystal display device that includes: a pair of substrates; a liquid crystal layer held between the substrates; and an alignment film disposed on a liquid crystal layer side surface of at least one of the substrates, the liquid crystal layer containing a liquid crystal material that has a nematic-isotropic phase transition temperature of 75 C. or lower and a nematic phase temperature range narrower than 100 C., the alignment film containing a first polymer and a second polymer, the first polymer having in its main chain at least one selected from a polyamic acid structure and a polyimide structure or a polysiloxane structure, the second polymer being obtained by polymerizing at least one monomer including at least one monomer containing a chalcone group.

The present invention provides a liquid crystal display device and a method of producing the same in which the occurrence of a bright dot at an edge portion of a display region is suppressed during use in a wide temperature range. The liquid crystal display device of the present invention includes: a liquid crystal layer disposed between a first substrate and a second substrate; an alignment film disposed adjacent to the liquid crystal layer of at least one of the first substrate or the second substrate; and a sealing material to achieve adhesion between the first substrate and the second substrate, wherein the liquid crystal layer contains a liquid crystal material, the liquid crystal material contains an alkoxy group-containing liquid crystal compound and exhibits a liquid crystal phase at 10 C. or higher and 80 C. or lower, the sealing material is a cured product of an epoxy resin-containing sealant, and the alignment film includes at least one of a first alignment film including a polymer layer formed using a first alignment agent containing a polyamic acid and a polysiloxane, or a second alignment film including a polymer layer formed using a second alignment agent containing a polyamic acid in which a silane coupling agent is adsorbed onto a surface of the polymer layer.

Provided are a liquid crystal alignment film capable of being given anisotropy through photoalignment and stable to light, and a liquid crystal display device capable of keeping a high voltage holding ratio without degradation of display quality even when exposed to strong light for a long period of time. To provide these, used is a liquid crystal aligning agent for photoalignment which contains a polymer having a structural unit containing a photoreactive structure and in which the structural unit containing a photoreactive structure undergoes chemical reaction by heating.

An alignment film is given a 2-layer structure comprising a photoalignment film that is photoalignable and a low-resistivity alignment film whose resistivity is smaller than that of the photoalignment film. The photoalignment film is formed by a polyimide whose precursor is polyamide acid alkyl ester, the number molecular weight of the photoalignment film is large, and the stability of alignment of the photoalignment film by photoalignment is excellent. The low-resistivity alignment film is formed by a polyimide whose precursor is polyamide acid, the number molecular weight of the low-resistivity alignment film is small, and the resistivity of the low-resistivity alignment film is small. The 2-layer structure alignment film can be maintaining an excellent photoalignment characteristic, so DC afterimages can be controlled.

According to one embodiment, a liquid crystal display device includes a first substrate, a second substrate disposed to oppose the first substrate, a layer of liquid crystal located between the first substrate and the second substrate, and an alignment film disposed on the first substrate so as to be in contact with the layer of the liquid crystal. The liquid crystal has a refractive-index anisotropy n of 0.11 or more, the layer of the liquid crystal has a thickness d of 2.5 m or less, and a product nd of the refractive-index anisotropy n and the thickness d is 0.20 or more but 0.31 or less. The transmissivity of light having a wavelength of 450 nm in the first substrate and the alignment film is 85% or more but 97% or less.

The present invention provides an alignment film capable of reducing generation of bubbles in a liquid crystal layer, a liquid crystal panel including the alignment film, and a method for producing the liquid crystal panel. The alignment film contains at least one selected from the group consisting of a polyamic acid containing a bisaniline fluorene skeleton and a polyimide containing a bisaniline fluorene skeleton. Preferably, the bisaniline fluorene skeleton of the polyamic acid is contained in a diamine unit of the polyamic acid and the bisaniline fluorene skeleton of the polyimide is contained in a diamine unit of the polyimide.

The present invention provides a liquid crystal alignment film not only having an excellent alignment property and stability, but also having high film strength, and thus exhibiting excellent durability and a high residual image property, a method for preparing the same, and a liquid crystal display device using the same.

An alignment film is given a 2-layer structure comprising a photoalignment film that is photoalignable and a low-resistivity alignment film whose resistivity is smaller than that of the photoalignment film. The photoalignment film is formed by a polyimide whose precursor is polyamide acid alkyl ester, the number molecular weight of the photoalignment film is large, and the stability of alignment of the photoalignment film by photoalignment is excellent. The low-resistivity alignment film is formed by a polyimide whose precursor is polyamide acid, the number molecular weight of the low-resistivity alignment film is small, and the resistivity of the low-resistivity alignment film is small. The 2-layer structure alignment film can be maintaining an excellent photoalignment characteristic, so DC afterimages can be controlled.