STN liquid crystal display

A liquid-crystal mixture comprising:

• a) 0-60% by weight of a liquid-crystalline component A comprising one or more compounds having a dielectric anisotropy of greater than +1.5;
• b) 0-60% by weight of a liquid-crystalline component B comprising one or more compounds having a dielectric anisotropy of between −1.5 and +1.5;
• c) 0-20% by weight of a liquid-crystalline component D comprising one or more compounds having a dielectric anisotropy of below −1.5;
• and
• d) optionally an optically active component C in an amount whereby the ratio between the layer thickness (separation of the outer plates) and the natural pitch of the resultant chiral nematic liquid-crystal mixture is 0.2 to 1.3,
• wherein liquid-crystal mixture additionally comprises at least one compound of formula IA
• in which
• Ra is H or an alkyl group having 1 to 7 carbon atoms, and
• Rb is an alkyl or alkoxy group having 1 to 10 carbon atoms or an alkenyl or alkenyloxy group having 2 to 10 carbon atoms;
• and at least one compound of formula IB, or at least one compound of formula IC or at least one compound of formula IB and at least one compound of formula IC
• wherein
• Rc is H or an alkyl group having 1 to 7 carbon atoms,
• Rd is F, OCF3, OCHF2, an alkyl or alkoxy group having 1 to 7 carbon atoms or an alkenyl group having 2 to 7 carbon atoms,
• Re is an alkyl or alkoxy group having 1 to 10 carbon atoms or an alkenyl or alkenyloxy group having 2 to 10 carbon atoms,
• Y1 to Y4 are each, independently of one another, H or F,
• q is 0 or 1, and
• p is 0, 1 or 2.

A supertwist liquid-crystal display comprising

• two outer plates which, together with a frame, form a cell,
• a nematic liquid-crystal mixture of positive dielectric anisotropy present in said cell,
• electrode layers with alignment layers on the insides of said outer plates,
• a pretilt angle between the longitudinal axis of the molecules at the surface of said outer plates and said outer plates of 0 to 30 degrees, and
• a twist angle of the liquid-crystal mixture in the cell from alignment layer to alignment layer with a value of 22.5° to 600°, and
• said nematic liquid-crystal mixture comprises
• a) −60% by weight of a liquid-crystalline component A comprising one or more compounds having a dielectric anisotropy of greater than +1.5;
• b) 0-60% by weight of a liquid-crystalline component B comprising one or more compounds having a dielectric anisotropy of between −1.5 and +1.5;
• c) 0-20% by weight of a liquid-crystalline component D comprising one or more compounds having a dielectric anisotropy of below −1.5;
• and
• d) optionally an optically active component C in an a mount whereby the ratio between the layer thickness and the natural pitch of the resultant chiral nematic liquid-crystal mixture is 0.2 to 1.3,
• wherein said liquid-crystal mixture contains at least one compound of formula IA
• in which
• Ra is H or an alkyl group having 1 to 7 carbon atoms, and
• Rb is an alkyl or alkoxy group having 1 to 10 carbon atoms or an alkenyl or alkenyloxy group having 2 to 10 carbon atoms;
• and at least one compound of formula IB, or at least one compound of formula IC, or at least one compound of formula IB and at least one compound of formula IC
• wherein
• Rc is H or an alkyl group having 1 to 7 carbon atoms,
• Rd is F, OCF3, OCHF2, an alkyl or alkoxy group having 1 to 7 carbon atoms or an alkenyl group having 2 to 7 carbon atoms,
• Re is an alkyl or alkoxy group having 1 to 10 carbon atoms or an alkenyl or alkenyloxy group having 2 to 10 carbon atoms,
• Y1 to Y4 are each, independently of one another, H or F,
• q is 0 or 1, and
• p is 0, 1 or 2;
• and
• wherein component B comprises one or more compounds selected from formulae T2a-T2g
• in which
• R1 and R2 are each, independently, alkyl, alkoxy or alkenyl group having 1 to 12 carbon atoms, in which, in addition, one or two non-adjacent CH2 groups may be replaced by —O—, —CH═CH—, —CO—, —OCO— or —COO— in such a way that O atoms are not linked directly to one another,
• Z4 is —CO—O—, —CH2CH2— or a single bond, and one, two or three of the radicals L1 to L6 are F and the others are H with the proviso that L1 and L2 or L3 and L4 or L5 and L6 are not both simultaneously F.

A supertwist liquid-crystal display comprising

• two outer plates which, together with a frame, form a cell,
• a nematic liquid-crystal mixture of positive dielectric anisotropy present in said cell,
• electrode layers with alignment layers on the insides of said outer plates,
• a pretilt angle between the longitudinal axis of the molecules at the surface of said outer plates and said outer plates of 0 to 30 degrees, and
• a twist angle of the liquid-crystal mixture in the cell from alignment layer to alignment layer with a value of 22.5° to 600°, and
• said nematic liquid-crystal mixture comprises
• a) 0-60% by weight of a liquid-crystalline component A comprising one or more compounds having a dielectric anisotropy of greater than +1.5;
• b) 0-60% by weight of a liquid-crystalline component B comprising one or more compounds having a dielectric anisotropy of between −1.5 and +1.5;
• c) 0-20% by weight of a liquid-crystalline component D comprising one or more compounds having a dielectric anisotropy of below −1.5;
• and
• d) optionally an optically active component C in an amount whereby the ratio between the layer thickness and the natural pitch of the resultant chiral nematic liquid-crystal mixture is 0.2 to 1.3,
• wherein said liquid-crystal mixture contains at least one compound of formula IA
• in which
• Ra is H or an alkyl group having 1 to 7 carbon atoms, and
• Rb is an alkyl or alkoxy group having 1 to 10 carbon atoms or an alkenyl or alkenyloxy group having 2 to 10 carbon atoms;
• and at least one compound of formula IB, or at least one compound of formula IC, or at least one compound of formula IB and at least one compound of formula IC
• wherein
• Rc is H or an alkyl group having 1 to 7 carbon atoms,
• R is F, OCF3, OCHF2, an alkyl or alkoxy group having 1 to 7 carbon atoms or an alkenyl group having 2 to 7 carbon atoms,
• Re is an alkyl or alkoxy group having 1 to 10 carbon atoms or an alkenyl or alkenyloxy group having 2 to 10 carbon atoms,
• Y1 to Y4 are each, independently of one another, H or F,
• q is 0 or 1, and
• p is 0, 1 or 2;
• and
• wherein component B comprises one or more compounds selected formulae T3a to T3e
• in which
• R1 and R2 are each, independently, an alkyl, alkoxy or alkenyl group having 1 to 12 carbon atoms, in which, in addition, one or two non-adjacent CH2 groups may be replaced by —O—, —CH═CH—, —CO—, —OCO— or —COO— in such a way that O atoms are not linked directly to one another and Z4 is —CO—O—, —CH2CH2— or a single bond.