Disclosed is a manufacturing method of a liquid crystal display device which is a manufacturing method of a liquid crystal display device including a liquid crystal alignment film to which an alignment regulating force is imparted by a photo-alignment treatment, including: a film forming step of forming a film containing a polymer whose main chain is cleaved by irradiation with light; a photo-alignment step of imparting an alignment regulating force to the film formed in the film forming step by irradiation of the film with light in an atmosphere of a temperature lower than 100° C.; and a removing step of removing a low-molecular weight component generated by cleaving the main chain of the polymer through the light irradiation after the light irradiation. Also disclosed is a liquid crystal display device manufactured by the manufacturing method.

To provide a liquid crystal display device, whereby transparency when no voltage is applied and scattering properties when a voltage is applied, are good, adhesion between a liquid crystal layer and a vertical liquid crystal alignment film is high, and its lifespan is long even in a severe environment. The liquid crystal display device has a liquid crystal layer formed by disposing a liquid crystal composition containing a liquid crystal and a polymerizable compound between a pair of substrates provided with electrodes, and irradiating and curing the composition with ultraviolet rays by an ultraviolet irradiation apparatus, and at least one of the substrates is provided with a liquid crystal alignment film to vertically align a liquid crystal, wherein the ultraviolet irradiation apparatus is an ultraviolet irradiation apparatus capable of controlling the irradiation light intensity and wavelength of the ultraviolet rays to be irradiated and the surface temperature of the pair of the substrates, the liquid crystal composition contains a compound represented by the formula [1], and the liquid crystal alignment film is a liquid crystal alignment film obtained from a liquid crystal alignment treating agent containing a polymer having a side chain structure represented by the formula [2-1] or formula [2-2].

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 is a specific side chain structure; X.sup.2, X.sup.3, X.sup.4 and X.sup.6 are each a single bond, etc.; X.sup.5 and X.sup.7 are each a benzene ring, etc.; p is an integer of from 0 to 4; and X.sup.8 is 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.6  [2-1]

(Y.sup.1, Y.sup.2 and Y.sup.3 are each a single bond; Y.sup.4 and Y.sup.5 are each a benzene ring, etc.; n is from 0 to 4; and Y.sup.6 is a C.sub.1-18 alkyl group, etc.,

—Y.sup.7-Y.sup.8  [2-2]

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

A liquid crystal display panel includes a first substrate, a second substrate, a first alignment layer, a second alignment layer and a liquid crystal layer. The second substrate faces the first substrate. The liquid crystal layer is disposed between the first alignment layer and the second alignment layer. The first alignment layer and the second alignment layer each include a polyimide compound polymerized by cyclobutane-1,2,3,4-tetracarboxylic dianhydride and cyclobutane-1,2,3,4-tetracarboxylic dianhydride derivative.

The present invention relates to a liquid crystal alignment composition that not only exhibits high degree of imidization and excellent film strength when manufacturing a liquid crystal alignment film, but also can realize improved alignment property and electrical properties, a method for preparing a liquid crystal alignment film using the same, a liquid crystal alignment film and a liquid crystal display using the same.

The present invention relates to a liquid crystal alignment agent composition including a copolymer for liquid crystal alignment agent containing two types of repeating units classified according to the types of diamine-derived functional groups, and a crosslinker compound in which the protecting group having a specific structure was introduced, a method for preparing a liquid crystal alignment film using the same, and a liquid crystal alignment film and a liquid crystal display device using the same.

The present application relates to a liquid crystal aligning agent, a liquid crystal alignment film and a method for producing the same, as well as a liquid crystal display device. The liquid crystal aligning agent comprises (i) a first polyamic acid having a photoreactive group without a liquid crystal group; (ii) a second polyamic acid having a liquid crystal group without a photoreactive group; (iii) a third polyamic acid having both a liquid crystal group and a photoreactive group; (iv) a fourth polyamic acid having neither a photoreactive group nor a liquid crystal group. The liquid crystal display device using the liquid crystal alignment film formed by the liquid crystal aligning agent provided by the present disclosure has a high display contrast and an improved AC residual image.

An alignment layer composition including a copolymer of a dianhydride compound and a diamine compound, the copolymer including a repeating unit represented by chemical formula (1); and a repeating unit represented by chemical formula (2):

##STR00001##

wherein R.sub.1 is a tetravalent organic group derived from an alicyclic dianhydride or an aromatic dianhydride, and wherein R.sub.1 includes a phenyl ester group.

An alignment layer composition including a copolymer of a dianhydride compound and a diamine compound, wherein the copolymer includes a repeating unit represented by Formula 1:

##STR00001##

wherein each of Ar.sub.1 and Ar.sub.2 is independently a substituted or unsubstituted aromatic group comprising 6 to 30 carbon atoms, X is an electron donating group, and

##STR00002##

is an ester group, wherein “*” indicates a point of attachment to the aromatic groups Ar.sub.1 and Ar.sub.2.

The present invention provides a liquid crystal display device that includes a horizontal alignment film, stabilizes liquid crystal alignment by the PSA technique, can suppress the increase in power consumption, reduction in contrast, and image sticking in display, and has long-term reliability. The present invention is a liquid crystal display device including a pair of substrates, a liquid crystal layer interposed between the pair of substrates, a horizontal alignment film formed on at least one of the pair of substrates, and a polymer layer which is formed on the horizontal alignment film and controls the alignment of adjacent liquid crystal molecules, wherein the polymer layer is formed by the polymerization of at least one or more kinds of monomers added into the liquid crystal layer, and at least one of the one or more kinds of monomers is polymerized by itself functioning as a polymerization initiator by being irradiated with light.

A photo-aligning liquid crystal alignment layer formed by using a photo-aligning liquid crystal aligning agent containing polyamic acid or a derivative thereof which is synthesized by using tetracarboxylic acid dianhydride having no photoreactive structure having a specific structure and diamine having no photoreactive structure having a specific structure together with at least one of tetracarboxylic acid dianhydride having a photoreactive structure and diamine having a photoreactive structure can reduce storage of residual DC in a liquid crystal display device. Further, the above alignment layer can shorten the relaxation time and can prevent afterimages from being generated.