A liquid-crystalline medium, in particular based on a mixture of polar compounds, having compounds of formulae Y, CY, PY and/or LY, and compounds of formula S1 and/or S2:

##STR00001##

Provided is a liquid crystal compound that can obtain a high-speed response and a sufficient contrast ratio in switching of a display device. A compound represented by formula (1) described below is utilized.

##STR00001##

In formula (1), ring A is naphthylene, phenantolylene or anthracenylene, and in the groups, at least one piece of hydrogen may be replaced by halogen, —CH.sub.3, —C.sub.2H.sub.5, —CF.sub.3, —CHF.sub.2, —CH.sub.2F, —OCF.sub.3, —OCHF.sub.2 or —OCH.sub.2F; and X.sup.1, X.sup.2, X.sup.3, X.sup.4, X.sup.5, Y.sup.1, Y.sup.2, Y.sup.3, Y.sup.4 and Y.sup.5 are independently hydrogen or fluorine, but at least two or more of X.sup.1, X.sup.2, X.sup.3, X.sup.4, X.sup.5, Y.sup.1, Y.sup.2, Y.sup.3, Y.sup.4 and Y.sup.5 is fluorine.

It is an object of the present invention to provide a liquid crystal composition having positive Δ∈, having a liquid crystal phase in a wide temperature range, having high solubility at low temperatures, having high ODF process compatibility, having a high specific resistance and voltage holding ratio, and being insensitive to heat and light. In order to achieve this object, there is provided a liquid crystal composition containing at least one compound represented by the following general formula (i) and at least one compound represented by the following general formula (ii). ##STR00001## (wherein R.sup.i1 denotes an alkyl group having 2 to 5 carbon atoms) ##STR00002## (wherein R.sup.ii1 and R.sup.ii2 independently denote an alkyl group having 1 to 5 carbon atoms or an alkenyl group having 2 to 5 carbon atoms, and X.sup.ii1 and X.sup.ii2 independently denote a hydrogen atom or a fluorine atom)

The present invention belongs to the technical field of liquid crystal materials, and in particular relates to a negative liquid crystal composition and a liquid crystal display element or liquid crystal display containing the liquid crystal composition. The present invention discloses a negative dielectric nematic liquid crystal composition, comprising a compound represented by Formula I, one or more compounds represented by Formula II, and one or more compounds represented by Formula III. The liquid crystal composition has a relatively low rotational viscosity (γ.sub.1), a high clearing point (Cp), a good solubility and a high stability to heat and light (VHR) on the basis of maintaining an appropriate optical anisotropy (Δn), and can be used for developing a liquid crystal display element or liquid crystal display with a low cell thickness, a wide temperature for display, and a fast response.

##STR00001##

The present invention provides a novel liquid crystal material composition comprising one or more compound, in order to achieve the properties of low viscosity, high resistivity, good low-temperature mutual solubility, fast response, excellent transmission, and which can be used for a variety of fast response display modes. Since the working temperature of a LCD material is subjected to the temperature range of individual LC molecules, information can only be displayed in a specific temperature range of the specific liquid crystal macro-alignment phase. At low temperature, the viscosity of liquid crystal increases exponentially, which in turn substantially reduces the response speed and overall performances of the display system. The liquid crystal composition according to the present invention overcomes these problems with balanced chemical composition by achieving low viscosity, good low-temperature performance and excellent transmission in a wide range of LCD applications including TN, IPS or FFS displays, thus improving display performance.

The present invention relates to a liquid crystal composition for a light-scattering liquid crystal device shown in FIG. 1 containing a polymerizable compound selected from the group consisting of compounds represented by the following general formula (1) as a first component and containing a compound having a negative dielectric anisotropy as a second component, a light-scattering liquid crystal device using the liquid crystal composition, and a smart window using the light-scattering liquid crystal device. A reverse mode type light-scattering liquid crystal device can have excellent transparency when no voltage is applied and a reduced driving voltage by the liquid crystal composition of the present invention.

Shown is a liquid crystal composition satisfying at least one of characteristics such as high maximum temperature, low minimum temperature, small viscosity, suitable optical anisotropy, large dielectric anisotropy and small frequency dependence, or has a suitable balance regarding at least two of the characteristics, and an AM device including the composition. The liquid crystal composition contains a specific compound having large positive dielectric anisotropy as a first component, and a specific compound having small viscosity as a second component, and may contain a specific compound having high maximum temperature or small viscosity as a third component, a specific compound having positive dielectric anisotropy as a fourth component or a specific compound having negative dielectric anisotropy as a fifth component.

Shown is a liquid crystal composition satisfying at least one of characteristics such as a high maximum temperature, a low minimum temperature, a small viscosity, a suitable optical anisotropy and a large dielectric anisotropy, or has a suitable balance regarding at least two of the characteristics, and an AM device including the composition. The liquid crystal composition contains a specific compound having large negative dielectric anisotropy as a first component, and a specific compound having small viscosity as a second component, and may contain a specific compound having negative dielectric anisotropy as a third component, a specific compound having a high maximum temperature or small viscosity as a fourth component or a specific compound having a polymerizable group as an additive component.

The present invention relates to a liquid crystal display device including a specific liquid crystal composition and a sealant in which a cured product of a specific curable resin composition is used. The present invention provides a liquid crystal display device which prevents a decrease in the voltage holding ratio (VHR) of the liquid crystal layer and which enables elimination of problematic defective display such as voids, uneven alignment, and screen burn-in. Since the liquid crystal display device of the present invention prevents a decrease in the voltage holding ratio (VHR) of the liquid crystal layer and enables a reduction in defective display such as uneven alignment and screen burn-in, it is particularly useful for active-matrix liquid crystal display devices of a VA mode and PSVA mode and can be applied to liquid crystal display apparatuses such as liquid crystal TVs, monitors, mobile phones, and smartphones.

A liquid crystal composition, comprising, at least one compound represented by Formula 1-A:

##STR00001##

wherein, in the Formula 1-A, R—*, R.sup.1—*, Q—*, *—Z1-*, *—Z2-*,

##STR00002##

n1, n2, n3, n4, L1-*, L2-*, L3-*, L4-*, L5-*, L6-*, L7-*, and L8-* are the same as defined in the specification, and * is defined as a bonding site to a neighboring atom.