The present invention relates to a liquid-crystalline medium based on a mixture of polar compounds having negative dielectric anisotropy (), which is distinguished by the fact that it has a value for the ratio .sub.1/n.sup.2 in the range 6-45 with a clearing point of >60 C. and a of 2.3. Media of this type are particularly suitable for electro-optical displays having active-matrix addressing based on the ECB, PA LCD, FFS or IPS effect.

The present invention relates to a liquid-crystalline medium based on a mixture of polar compounds having negative dielectric anisotropy (), which is distinguished by the fact that it has a value for the ratio .sub.1/n.sup.2 in the range 6-45 with a clearing point of >60 C. and a of 2.3. Media of this type are particularly suitable for electro-optical displays having active-matrix addressing based on the ECB, PA LCD, FFS or IPS effect.

The present invention relates to a liquid-crystalline medium based on a mixture of polar compounds having negative dielectric anisotropy (), which is distinguished by the fact that it has a value for the ratio .sub.1/n.sup.2 in the range 6-45 with a clearing point of >60 C. and a of 2.3. Media of this type are particularly suitable for electro-optical displays having active-matrix addressing based on the ECB, PA LCD, FFS or IPS effect.

To show a liquid crystal composition satisfying at least one of characteristics such as a high maximum temperature of a nematic phase, a low minimum temperature of the nematic phase, small viscosity, suitable optical anisotropy, large dielectric anisotropy, large specific resistance, high stability to ultraviolet light and heat; a liquid crystal composition having a suitable balance regarding at least two of the characteristics; and an AM device having a short response time, a large voltage holding ratio, a large contrast ratio, a long service life and so forth. The liquid crystal composition has the nematic phase and contains a specific compound having large dielectric anisotropy as a first component, and may contain a specific compound having a high maximum temperature or small viscosity as a second component, and a specific compound having large dielectric anisotropy as a third component, and a liquid crystal display device includes the composition.

An object of the present invention is to provide a powder mixture containing a polymerizable liquid crystal compound, the powder mixture having a low risk of occurrence of fire due to the flammability of solvent, causing no changes in the appearance due to, for example, precipitation or crystallization of the solute during storage at low temperatures, causing no changes in the composition due to evaporation of solvent during long-term storage or leakage of solvent during long-term storage or transportation, being not viscous and having fluidity unlike nematic liquid crystal compositions, and being easily handled. Another object is to provide a nematic liquid crystal composition, a solution composition, cured products, optical films, and display devices that employ the above-described powder mixture.

The invention relates to a liquid-crystalline medium comprising at least one compound of the formula I, ##STR00001##
in which
R.sup.1 and R.sup.2 have the meanings indicated in Claim 1,
and to the use thereof in electro-optical liquid-crystal displays.

The present invention relates to liquid-crystalline media comprising a) one or more compounds of the formula ST-1, as defined herein, and b) one or more compounds of the formula ST-2, as defined herein, and c) one or more compounds of the formula RV, as defined herein, and d) one or more compounds selected from formula IA and IB, as defined herein, and to liquid-crystal displays containing these media, especially to displays addressed by an active matrix and in particular to displays of the in-plane switching (IPS) or fringe-field switching (FFS) type.

The present invention relates to a polymer composition which contains (A) a photosensitive side-chain polymer that exhibits liquid crystallinity in a predetermined temperature range and has a repeating unit comprising a vertically aligning group, and (B) an organic solvent. The present invention provides: a liquid crystal alignment film which has excellent tilt angle characteristics, while being provided with alignment controllability with high efficiency; a polymer composition which enables the achievement of this liquid crystal alignment film; a twisted nematic liquid crystal display element; and a vertical field switching mode liquid crystal display element.

Disclosed is a liquid crystal composition and use thereof. The liquid crystal composition comprises components a, b and c; wherein component a is selected from one of the compounds represented by formula I; component b is a liquid crystal composition having a dielectric anisotropy of greater than 3; and component c is a liquid crystal composition having a dielectric anisotropy of 3 to 3. The liquid crystal composition has a high contrast ratio property, and has a low change rate at a low temperature, that is, the decrease of contrast ratio at a low temperature (such as 20 C.) is smaller as compared to a normal temperature. The composition has suitable properties with regard to practical applications, including a broader nematic phase range, an appropriate dielectric anisotropy, optical anisotropy and operating voltage, an excellent response time, a high electrical resistivity and voltage holding ratio, a low rotary viscosity, etc. ##STR00001##

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