A liquid crystal display including a first substrate, a second substrate disposed opposite the first substrate, and a liquid crystal layer disposed between the first substrate and the second substrate. The liquid crystal layer includes a liquid crystal composition. The liquid crystal composition includes at least one of liquid crystal compounds including a cyclopentadienyl group.

The present invention relates to a liquid crystal (LC) medium comprising polymerisable compounds, to a process for its preparation, to its use for optical, electro-optical and electronic purposes, in particular in LC displays, and to LC displays comprising it.

Provided is a polar compound having high chemical stability, high capability of aligning liquid crystal molecules, high solubility in a liquid crystal composition, and a large voltage holding ratio when used in a liquid crystal display device. The compound is represented by formula (1): ##STR00001##
in which, for example, R.sup.1 is alkyl having 1 to 15 carbons; MES is a mesogen group having at least one ring; Sp.sup.1 is a single bond or alkylene having 1 to 10 carbons; M.sup.1 and M.sup.2 are hydrogen; and R.sup.2 is a group represented by formulas (1a) to (1c): ##STR00002##
in which, Sp.sup.2 and Sp.sup.3 are a single bond or alkylene having 1 to 10 carbons; S.sup.1 is >CH; S.sup.2 is >C<; and X.sup.1 is OH.

To show a liquid crystal composition containing a polymerizable compound, to exhibit excellent persistence characteristics and display unevenness characteristics, a liquid crystal display device including such a composition, and an optical device. To show a liquid crystal composition containing the polymerizable compound and satisfying at least one of characteristics such as high maximum temperature, low minimum temperature, small viscosity, suitable optical anisotropy, large negative dielectric anisotropy and large specific resistance; and an AM device having characteristics such as a small persistence ratio, a short response time, a low threshold voltage, a large voltage holding ratio, a large contrast ratio and a long service life. The liquid crystal composition contains as a first component a polymerizable monomer that has a capability of a hydrogen bond donor and can form a hydrogen bond with an alignment film surface, or an oligomer, a prepolymer or a polymer of the monomer.

A seal material for liquid crystal display device comprising a seal ingredient including an epoxy monomer and a curing agent, and a moisture absorbent, wherein the moisture absorbent comprises a crystalline compound containing SiO.sub.x (wherein x=1 or higher to 8 or lower) and AlO.sub.y (wherein y=1 or higher to 8 or lower); and the moisture absorbent is contained 5 mass % or more to 18 mass % or less with respect to a total amount of the above-described seal material for liquid crystal display device.

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 substrate 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.

A liquid crystal composition includes one or more compounds represented by Chemical Formula 1. ##STR00001## In Chemical Formula 1, ##STR00002##
are a cyclohexane or tetrahydropyran, and R1 and R2 are each independently hydrogen, a C1 to C8 alkyl group, a C2 to C8 alkenyl group, or a C1 to C8 alkoxy group.

The present invention relates to a process of preparing a light modulation element of the PS-ULH (polymer stabilised ULH) type, which allows to reduce the operational voltage and allows to improve the switching time of the light modulation element.

A compound capable of suppressing the occurrence of alignment defects and lowering the phase transition temperature of a liquid crystal composition without impairing optical characteristics is provided. In particular, a compound represented by formula (A) is provided in which the variable groups are as defined in the specification.

##STR00001##

A liquid crystal display including a first substrate, a second substrate disposed opposite the first substrate, and a liquid crystal layer disposed between the first substrate and the second substrate. The liquid crystal layer includes a liquid crystal composition. The liquid crystal composition includes at least one of liquid crystal compounds including a cyclopentadienyl group.