The present invention relates to a liquid crystal (LC) medium comprising a compound of formula I

##STR00001## and one or more compounds selected from the group of compounds of the formulae IIA, IIB, IIC and IID,

##STR00002## as defined in claim 1, and to the use of the LC medium for optical, electro-optical and electronic purposes, in particular in LC displays, especially in IPS, FFS, VA or PS-VA displays.

The invention relates to a liquid-crystalline medium based on a mixture of polar compounds having positive dielectric anisotropy, characterised in that it comprises one or more compounds of the formula I in a total concentration of ≥40%, ##STR00001##
in which the parameters have the meanings indicated in claim 1, and to the use of the liquid-crystalline medium for electro-optical purposes, in particular in liquid-crystal light valves for lighting devices for motor vehicles, and to liquid-crystal light valves which comprise this medium and lighting devices for motor vehicles which contain such liquid-crystal light valves.

The present invention provides a compound represented by formula (i), a liquid crystal composition using the compound, and a liquid crystal display device using the liquid crystal composition. The compound represented by formula (i) has a partial structure K.sup.i1 represented by any of general formulas (K-1) to (K-17) and further has ring B having at least two P-Sp- groups. Therefore, when used for a liquid crystal composition, the compound adsorbs to substrates sandwiching the liquid crystal composition (liquid crystal layer) and allows liquid crystal molecules to be held such that they are aligned in a vertical direction without a PI layer, and improved alignment stability and low-temperature storage stability can be achieved.

The compound is represented by general formula (i). In the compound, in a group K.sup.i1, at least two secondary carbon atoms in an alkyl group (a linear alkyl, halogenated alkyl, or cyanogenated alkyl group having 3 to 40 carbon atoms) are replaced with C(X.sup.i1) and/or CH(CN), where X.sup.i1 is an oxygen atom, a sulfur atom, NH, or NR.sup.13; in addition, a group A.sup.i2, a group A.sup.i3, or the group K.sup.i1 includes, as a substituent, at least one P.sup.i1-Sp.sup.i1- group, where P.sup.i1 is a polymerizable group, and SP.sup.i1 is a spacer group or a single bond. The liquid crystal composition including the compound represented by general formula (i) can be adsorbed onto substrates between which a liquid crystal layer is held, and, consequently, without the use of an alignment film, liquid crystal molecules can be maintained in a state in which the liquid crystal molecules are aligned in a vertical direction.

##STR00001##

A complex (10) includes a liquid crystal component (13) and a support (11, 12) of the liquid crystal component (13), in which a lubricating interface derivation region (16) is formed between the liquid crystal component (13) and the support (11, 12). An optical element includes a pair of substrates (11, 12) having electrodes (18, 19) on at least one substrate (11), and a liquid crystal component (13) with which a space between the pair of substrates (11, 12) is filled, in which a lubricating interface derivation region (16) is formed between the pair of substrates (11, 12) and the liquid crystal component (13). It is preferable that the lubricating interface deriving agent (14) is present in the lubricating interface derivation region.

A liquid crystal composite that contains a liquid crystal composition satisfying at least one of characteristics such as high maximum temperature, low minimum temperature, small viscosity, large optical anisotropy and large positive dielectric anisotropy, and that is suitable for dimming, or having a suitable balance regarding at least two of the characteristics; and a liquid crystal dimming device having the liquid crystal composite. The liquid crystal composite contains a polymer and a liquid crystal composition containing a specific compound having large positive dielectric anisotropy. The liquid crystal composite may further contain a specific compound having high maximum temperature or low minimum temperature; or a specific compound having large negative dielectric anisotropy.

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.

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 crystalline compound, a liquid crystal composition, and a liquid crystal display element are provided. The liquid crystalline compound satisfying at least one physical property among high stability against heat and light, high transparency, low minimum temperature of the liquid crystal phase, low viscosity, proper optical anisotropy, negatively large dielectric anisotropy, proper elastic constant, good compatibility with other liquid crystalline compounds at room temperature and low temperature. The liquid crystalline compound represented by formula (1).

##STR00001##