There is provided a composition containing a discotic liquid crystal compound, a chiral agent, and a surfactant which can form a light reflecting layer formed by fixing a cholesteric liquid crystalline phase, which exhibits excellent durability under a hot and humid environment and excellent heat resistance, and has few alignment defects; a light reflecting film; a luminance-improving film; a backlight unit; and a liquid crystal display device.

The invention relates to bimesogenic compounds of formula I

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wherein R.sup.11, R.sup.12, MG.sup.11, MG.sup.12, X.sup.11, X.sup.12 and Sp.sup.1 have the meaning given in claim 1, to the use of bimesogenic compounds of formula I in liquid crystal media and particular to flexoelectric liquid crystal devices comprising a liquid crystal medium according to the present invention.

The present invention relates to dielectrically positive liquid-crystalline media comprising one or more compounds of the formula I,

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and one or more compounds selected from the group of the compounds of the formulae II and III and/or IV,

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in which the parameters have the respective meanings indicated in the specification, and optionally one or more further dielectrically positive compounds and optionally one or more further dielectrically neutral compounds, and to liquid-crystal displays, especially active-matrix displays and in particular TN, IPS and FFS displays, containing these media.

A cholesteric liquid crystal mixture containing a compound represented by Z.sup.1Y.sup.1-A.sup.1-Y.sup.3-M.sup.1-Y.sup.4-A.sup.2-Y.sup.2Z.sup.2, a compound represented by Z.sup.3Y.sup.5-A.sup.3-Y.sup.7-M.sup.2-P, and a tri- or higher functional polymerizable monomer suppresses deposition of a liquid crystal at the time of forming a film, exhibits a wide characteristic reflection bandwidth of the film. Z.sup.1 to Z.sup.3 represent a polymerizable group; A.sup.1 to A.sup.3 represent an alkylene spacer having a chain of 1 to 30 atoms; M.sup.1 and M.sup.2 represent (-T.sup.1-Y.sup.8).sub.n-T.sup.2-; n indicates a natural number; T.sup.1 and T.sup.2 represent a hydrocarbon or heterocyclic ring; Y.sup.1 to Y.sup.5, Y.sup.7 and Y.sup.8 represent a single bond, O, CO, OCO, COO or OCOO; and P represents a hydrogen atom or an alkyl group.

An aromatic amine compound is represented by:

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A.sup.1s each independently represent a substituted or unsubstituted alkylene group or a substituted or unsubstituted divalent aromatic group, and A.sup.2s and A.sup.3s each independently represent a substituted or unsubstituted alkyl group or a substituted or unsubstituted aromatic group, where at least one of A.sup.1, A.sup.2 and A.sup.3 represents an aromatic group. s and t each independently represent an integer from 0 to 6. R.sup.1 and R.sup.2 each independently represent a substituent. p+s and q+t each independently represent an integer from 0 to 6. Ts each independently represent a divalent linking group formed from at least one selected from a carbonyl group, an oxygen atom, an imino group, and an alkylene group. Q represents a trivalent linking group composed of at least one selected from an oxygen atom, a nitrogen atom, a carbon atom, a phosphorus atom, a sulfur atom, and a hydrogen atom.

A compound represented by General Formula (I), A.sup.1 to A.sup.4 each independently represent a non-aromatic ring group, an aromatic hydrocarbon ring group, or an aromatic heterocyclic group, which may have a substituent, Z represents O, S, CHRCHR, OCHR, CHRO, CO, SO, SO.sub.2, COO, OCO, COS, SCO, OCOO, SCHR, CHRS, SOCHR, CHRSO, SO.sub.2CHR, CHRSO.sub.2, CF.sub.2O, OCF.sub.2, CF.sub.2S, SCF.sub.2, OCHRCHRO, SCHRCHRS, SOCHRCHRSO, SO.sub.2CHRCHRSO.sub.2, CHCHCOO, CHCHOCO, COOCHCH, OCOCHCH, COOCHRCHR, OCOCHRCHR, CHRCHRCOO, CHRCHROCO, COOCHR, OCOCHR, CHRCOO, CHROCO, CRCR, CRN, NCR, NN, CRNNCR, CFCF, CC, or a single bond, R represents a hydrogen atom or an alkyl group having 1 to 10 carbon atoms, and m1 represents an integer of 2 to 7. ##STR00001##