Object To provide a tilt-imparted liquid crystal display element that is obtained through UV irradiation of a polymerizable liquid crystal composition, whose drive voltage can be reduced with a fast decay time maintained, and that is well balanced between characteristics, such as decay time, drive voltage, and transmittance. A polymerizable liquid crystal composition for use in it is also provided. Solution A liquid crystal display element has polymer networks formed in the liquid crystal phase 5 in FIG. 3. The polymer networks are formed by polymerizing a polymerizable liquid crystal composition that contains, as essential ingredients, a radically polymerizable monomer component (A), a liquid crystal material (B), and a polymerization initiator (C) that has a molecular structure resulting from substituting any two or more hydrogen atoms in the aromatic nucleus in the molecular structure of an alkylphenone-based photopolymerization initiator, for example with a C1-10 alkyl group (i).

A liquid crystal compound is represented by formula (1): ##STR00001## In formula (1), R.sup.1 is alkyl or the like; ring A.sup.1 and ring A.sup.2 are independently 1,4-cyclohexylene, 1,4-phenylene or the like; Z.sup.1, Z.sup.2 and Z.sup.3 are independently a single bond, CF.sub.2O or the like; X.sup.1 is fluorine, chlorine, CF.sub.3 or the like; L.sup.1 and L.sup.2 are independently hydrogen, fluorine or the like; a and b are independently 0, 1, 2 or 3; and W is a group represented by formula (1a) or formula (1b); ##STR00002## In formula (1a) and formula (1b), L.sup.3 to L.sup.8 are independently hydrogen, fluorine or the like.

A liquid crystal (LC) medium containing a polymerisable compound, a process for its preparation, its use for optical, electro-optical and/or electronic purposes, in particular in LC displays, especially in an LC display of the polymer sustained alignment (PSA) type, and an LC display, especially a PSA display, containing the LC medium.

Provided are a liquid crystal composition satisfying at least one of characteristics including a high maximum temperature, a low minimum temperature, small viscosity, suitable optical anisotropy and large negative dielectric anisotropy, or the liquid crystal composition having a suitable balance regarding at least two of the above 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 component having high maximum temperature or small viscosity as a third component, a specific component having negative dielectric anisotropy as a fourth component, or a specific compound having a polymerizable group as an additive.

A liquid-crystalline medium having least one compound of the formula I, ##STR00001## and at least one compound of the formulae ST-1 to ST-17, ##STR00002## ##STR00003## ##STR00004## in which R.sup.1 and R.sup.1*, A.sup.1 and A.sup.1*, Z.sup.1 and Z.sup.1*, X, L.sup.1 and L.sup.2, R.sup.ST, ring A, Z.sup.ST, p and q have the meanings indicated in claim 1, and the use thereof for an active-matrix display, in particular based on the VA, PSA, PA-VA, SS-VA, SA-VA, PS-VA, PALC, IPS, PS-IPS, UB-FFS, U-IPS, FFS or PS-FFS effect.

Disclosed are a liquid crystal composition and a display element or display using the liquid crystal composition, wherein the liquid crystal composition contains one or more compounds of general formulas I, II and III, ##STR00001##
The liquid crystal composition disclosed in the present invention has an excellent performance, an optical anisotropy in the range of 0.080 to 0.150, a low rotary viscosity, a fast response time, and good chemical, optical and thermal stabilities, and is very suitable for manufacturing liquid crystal display elements, particularly suitable for active matrix display elements, such as active matrix displays using a VA, FFS or IPS mode.

A liquid-crystalline medium which comprises at least one compound selected from the group of compounds of the formulae IA to IH, ##STR00001##
in which Z.sup.1 denotes a single bond, CH.sub.2CH.sub.2, CH?CH, CH.sub.2O, OCH.sub.2, CF.sub.2O, OCF.sub.2, COO, OCO, C.sub.2F.sub.4, (CH.sub.2).sub.4, CHFCHF, CF.sub.2CH.sub.2, CH.sub.2CF.sub.2, C?C, CF?CF, CH?CHCHO or CH.sub.2CF.sub.2O,
and the use thereof for an active-matrix display, in particular based on the VA, PSA, PS-VA, PALC, FFS, PS-FFS, SA-VA, PS-IPS or IPS effect.

The invention relates to a compound of formula I, ##STR00001##
wherein R.sup.11, R.sup.21, A.sup.11, A, Z, X.sup.11, X.sup.21, Y.sup.11, Y.sup.12, Sp.sup.11, Sp.sup.21, o and p have one of the meanings as given in claim 1. The invention further relates to method of production of a compound of formula I, to the use of said compounds in LC media and to LC media comprising one or more compounds of formula I. Further, the invention relates to a method of production of such LC media, to the use of such media in LC devices, and to LC device comprising a LC medium according to the present invention. The present invention further relates to a process for the fabrication such liquid crystal display and to the use of the liquid crystal mixtures according to the invention for the fabrication of such liquid crystal display.

A liquid-crystalline medium which comprises at least one compound selected from the group of compounds of the formulae IA to IH, ##STR00001##
in which Z.sup.1 denotes a single bond, CH.sub.2CH.sub.2, CH?CH, CH.sub.2O, OCH.sub.2, CF.sub.2O, OCF.sub.2, COO, OCO, C.sub.2F.sub.4, (CH.sub.2).sub.4, CHFCHF, CF.sub.2CH.sub.2, CH.sub.2CF.sub.2, C?C, CF?CF, CH?CHCHO or CH.sub.2CF.sub.2O,
and the use thereof for an active-matrix display, in particular based on the VA, PSA, PS-VA, PALC, FFS, PS-FFS, SA-VA, PS-IPS or IPS effect.

Liquid crystal compound satisfying at least one of physical properties such as high stability to heat or light, high maximum temperature, high clearing point, low minimum temperature of liquid crystal phase, small viscosity, suitable optical-anisotropy, large negative dielectric-anisotropy, suitable elastic constant and good compatibility with other liquid crystal compounds; liquid crystal composition containing the compound; and liquid crystal display device including the composition. Compound represented by formula (1), wherein R.sup.1 is alkyl having 1 to 15 carbons; R.sup.2 is alkyl having branched-chain and 3 to 15 carbons; A.sup.1, A.sup.2 are independently 1,2-cyclopropylene; Z.sup.1, Z.sup.2 are independently single bond or alkylene having 1 to 15 carbons; L.sup.1, L.sup.2 are fluorine, chlorine, OCF.sub.3 or OCH.sub.2F; X.sup.1, X.sup.2 are oxygen or sulfur; and a is 0 or 1, b is 0 or 1, and sum of a and b is 0, 1 or 2.

##STR00001##