Nematic liquid-crystal composition

Abstract

The invention relates to a nematic liquid-crystal composition especially for active matrix displays with high voltage holding ratio, good low temperature stability and without reversed domains.

Description

The invention relates to nematic liquid-crystal compositions based on terminally and laterally fluorinated compounds. These compositions are useful for active and passive matrix application.

Active matrix displays (AMD) are highly favored for commercially interesting displays with a high information content. Such AMDs are used for TV application and also for displays with high information content for automobiles and airplanes.

AMDs have non-linear electrical switching elements which are integrated at each picture element. As non-linear driving elements thin film transistors (TFT) [Okubo, U., et al., 1982, SID 82 Digest, pp. 40-41] or diodes (e.g.: metal insulator metal: MIM) [Niwa, K., et al., 1984, SID 84, Digest, pp. 304-307] can be applied. These non-linear driving elements allow to use an electro-optical effect with a rather flat electro-optical characteristic if a good viewing angle characteristic can be obtained. So a TN-type LC cell [Schadt, M. and Halfrich, W., 1971, Appl. Phys. Lett., 18, 127] with a twist angle of 90.degree. can be used. To provide the good contrast over a wide viewing angle, operation in the first minimum of: transmission [Pohl, L., Eidenschink, R., Pino, F. del., and Weber, G., 1980, German Pat., DBP 30 22 818, and 1981, U.S. Pat. No. 4 398 803; Pohl, L., Weber, G., Eidenschink, R., Baur, G., and Fehrenbach, W., 1981, Appl. Phys. Lett., 38, 497; Weber, G., Finkenzeller, U., Geelhaar, T., Plach, H. J., Rieger, B., and Pohl, L., 1988, Int. Symp. on Liq. Cryst., Freiburg, to be published in Liq. Crys.] is required. These AMDs are very well suited for TV applications and consequently are of high commercial interest. For these applications some physical properties of the liquid crystals become more important than for passive TN displays. Some of the decisive properties for the performance of an AMD are resistivity and stability of the liquid crystal [Togashi, S., Sekiguchi, K., Tanabe, H., Yamamoto, E., Sorimachi, K., Kajima, E., Watanabe, H., Shimuzu, H., Proc. Eurodisplay 84, Sept. 1984: A 210-288 Matrix LCD Controlled by Double Stage Diode Rings, p. 144 ff, Paris; Stromer, M., Proc. Eurodisplay 84, Sept. 1984: Design of Thin Film Transistors for Matrix Addressing of Television Liquid Crystal Displays, p. 145 ff, Paris].

In an AMD the non-linear switching elements are addressed in a multiplex scheme. So they charge the electrodes of a pixel in the limited time they are active. Then they become inactive until they are addressed again in the next cycle. Consequently the change of the voltage on an activated (charged) pixel is a nondesired but a very decisive feature of such a display. The discharge of a pixel is determined by two factors. They are the capacity of the electrodes of the pixel and resistivity of the dielectric material between the electrodes, namely the liquid crystal. The characteristic time constant of the decay of the voltage at a pixel (RC-time) has to be significantly bigger than the time between two adressing cycles (tadr.). A parameter frequently used to describe the performance of an AMD is the voltage holding ratio HR of a picture element: ##EQU1##

As the voltage at a pixle decays exponentially an increase of the holding ratio necessitates liquid crystal materials with exceptionally high resistivities.

There are several points of importance for the resistivity of the liquid crystal inside a display, e.g. orientation layers, curing condition of the orientation material. But by no means less important are the electrical properties of the liquid crystal used. Especially the resistivity of the liquid crystal in the display determines the magnitude of the voltage drop at the pixel.

Recently LC compositions with very good HR values could be obtained by using exclusively fluorinated compounds instead of the conventional LC compositions which are based on cyano compounds. Unfortunately, however, such LC compositions based on fluorinated compounds still pose severe problems. In many cases they tend to have lower pretilt angles than cyano based mixtures and they tend to show smectic phases and/or crystallization problems at low temperatures and it is also very difficult to realize very low threshold voltages without using cyano compounds. Finally the compositions based on fluorinated compounds show reverse domain phenomena (reverse tilt disclination) in many cases. One reason for this problem may reside in the relatively small surface tilt angle of the compositions compared to cyano LC based compositions. Another reason may also be the influence of the elastic constants and especially the K.sub.22 value.

There is thus still a great need for liquid-crystal composition having a high resistivity and other suitable material properties for use in AMDs such as a broad nematic mesophase range with an extremely low transition temperature smecticnematic, no crystallization at low temperatures and being completely free of reverse domain phenomena (reverse tilt disclination).

The invention has for its object to provide a liquid-crystal composition with a very high resistivity which meets also the other demands.

Fluorinated compounds generally show a tendency towards lower pretilt angles than cyano compounds. Nevertheless, the present inventors found big differences of pretilt angles between different structures of fluorinated compounds. Some examples are given in the following table 1 which shows that fluorinated LCs can come close to the pretilt angles of cyano LCs.

TABLE 1______________________________________Tilt Angles of Various MixturesFluorinated*.sup.1 Tilt Angles (deg)compounds J-1*.sup.3 J-2*.sup.3______________________________________L 2.3 4.5M 1.6 4.1N 1.5 4.0O 1.4 4.1P 1.0 3.5Mix.X*.sup.4 1.3 3.0 ##STR1## 2.2 5.5ZLI-3086 1.2 3.1______________________________________ *.sup.1 Each compound, L-P, is mixed with Mix.X in the ratio of 25:75. *.sup.2 This compound is mixed with ZLI3086 (a sales item of E. Merck Darmstadt, Germany in the ratio of 25:75). *.sup.3 Low temp. baking type polyimides from Japan Synthetic Rubbers wer used as alignment reagents. *.sup.4 Does not contain cyano components and consists of 15% of PCH32, 15% of PCH53, 20% of PCH301, 15% of PCH302, 15% of PCH304, 6% of BCH32, 6 of BCH52, 4% of CBC33F and 4% of CBC53F.

The structures of fluorinated compounds used in Table 1

__________________________________________________________________________ DesignationMark (Acronym) Structure Group__________________________________________________________________________L CCP-nOCF2.F.F ##STR2## 3M CUP-nF.F ##STR3## 2N ECCP-nF ##STR4## 1O ECCP-nF.F ##STR5## 1P ECCP-nOCF3 ##STR6## 1__________________________________________________________________________ It has now been found that a nematic liquid-crystal composition based on terminally and laterally fluorinated compounds, characterized in that it comprises about 8 to 70% by weight of one or more compounds from group 1: ##STR7## wherein R.sup.1 denotes a straight-chain alkyl group of 2 to 5 carbon atoms, E.sup.1 is ##STR8## L is H or F and Q is OCF.sub.2, OCFH, OCFC.sub.1, CF.sub.2 or a single bond, about 8 to 60% by weight of one or more compounds from group 2: ##STR9## wherein R.sup.2 denotes a straight-chain alkyl group of 2 to 5 carbon atoms, E.sup.2 is ##STR10## and each L is H or F, and/or about 8 to 40% by weight of one or more compounds from group 3: ##STR11## wherein R.sup.3 denotes a straight-chain alkyl group of 2 to 5 carbon atoms, E.sup.3 is ##STR12## and Q and L are as defined above, with the proviso that both L are F if E.sup.3 is trans-1,4-cyclohexylene, is highly suited for AMD application. Very high RC time values can be obtained in AMDs. These compositions also show a reduced viscosity, allow operation in AMDs in the first minimum of transmission, do not exhibit any crystallization at -30 .degree. C. and are free of reverse domain problems (reverse tilt disclination). The latter being due to the very specific selection of fluorinated compounds which makes it possible to achieve fairly high pretilt angles.

Such compositions preferably contain two, three or four compounds from group 1. Preferred compositions comprise more than 12% by weight of one or more compounds from group 1.

The compounds from groups 1 to 3 are known from the European Patent Applns. 0 387 032 and 0 280 902, the European Patents 0 051 738 and 0 125 653, the International Patent Application WO 89/02884 and U.S. Pat. No. 4,302,352, U.S. Pat. No. 4,710,315 and U.S. Pat. No. 4,419,264 or can be prepared in analogy to known compounds.

Preferred compositions comprise simultaneously one or more compounds from each of groups 1a and 1b: ##STR13##

Preferably the compositions comprise one or more compounds from group 2 which are selected from the following formulae: ##STR14##

Preferably the compositions comprise one or more compounds from group 3 which are selective from the formula 3a to 3f: ##STR15##

Preferred compounds from group 1 are those wherein L=F and Q=single bond (=subgroup 1'). However, compositions are especially preferred which contain also compounds from group 1 wherein Q is OCF.sub.2, OCFH, OCFC.sub.1 or CF.sub.2 and L is H or F (=subgroup 1"). In subgroup 1", Q is preferably OCF.sub.2 or CF.sub.2, OCF.sub.2 being especially preferred. The weight ratio of components from subgroup 1' and subgroup 1" is preferably .gtoreq.1. Especially preferred are compositions with subgroup 1'/subgroup 1".gtoreq.2:1. Of course also compositions are of particular importance which are mainly or even exclusively based on subgroup 1' components. Also preferred are compositions being based on subgroup 1' components which comprise simultaneously one or more compounds from each of groups 1 a and 1b.

Preferred compositions also comprise one or more compounds from group 0 having two rings: ##STR16## where R.sup.0 denotes a straight-chain alkyl group of 2 to 5 carbon atoms, E.sup.0 is --(CH.sub.2).sub.4 --, --(CH.sub.2).sub.2 --, --CO--O-- or a single bond an L and Q are as defined in group 1. Preferably E.sup.0 is --(CH.sub.2).sub.2 -- or a single bond, Q is a single bond and one of L is H and the other L is H or F.

The compositions according to this invention preferably comprise 30 to 60% by weight and especially 35 to 55% by weight of components from group 1. The preferred weight percent ranges for the other groups (if present) are as follows:

group 0: 5 to 30%, especially 10 to 25% group 2: 12 to 40%, especially 15 to 25% group 3: 12 to 30%, especially 15 to 25%

Preferably, the components from groups 1, 2 and 3 form the basis of the claimed compositions and constitute at least 60% (preferably at least 75%) by weigh of the compositions. It is, however, also possible to use besides components from groups 0 to 3 also other LC components in smaller percentages for fine-tuning the claimed compositions.

From many experimental investigations it also resulted that the most efficient compounds from group 2 are those of the formula ##STR17##

These components are preferably used in an amount of 18 to 30% by weight. Higher amounts are possible but do not further improve the "reverse domain" behavior.

The preparation of the compositions according to the invention is effected in the conventional manner. In general, the desired amount of the components which are used in the smaller amounts is dissolved in the component which constitutes the main constituent, preferably at elevated temperature. If this temperature is chosen to be above the clear point of the main constituent, the completeness of the process of dissolving can be observed particularly easily.

However, it is also possible to mix solutions of the components in a suitable organic solvent, for example acetone, chloroform or methanol, and to remove the solvent after thorough mixing, for example by distillation under reduced pressure. It is self-evident that with this method it must be ensured that the solvent does not introduce any contaminants or undesirable dopants.

By means of suitable additives the liquid crystal phases according to the invention can be modified in such a way that they can be used in any hitherto disclosed kind of AMD.

For the tilt angle measurement, we used crystal rotation method. Cell gap of all test cells used in this work was around 50 .mu.m. Test cells were cells made of Soda lime+ITO by DNT with Polyimide orientation layer (Nissan Chemicals SE-150). Before tilt angle measurement, all test cells were heated up 20 minutes at 120 .degree. C. after filling LC mixtures as the isotropic treatment.

The examples below serve to illustrate the invention without limiting it. In the examples, the melting point and clear point of a liquid crystal substance are given in degrees Celsius. The percentages are by weight.

EXAMPLE 1

A liquid-crystal composition consisting of

11% of trans-1-p-fluorophenyl-4-n-pentylcyclohexane, 11% of trans-1-p-fluorophenyl-4-n-hexylcyclohexane, 14% of 1-[trans-4-(trans-4-pentylcyclohexyl)-cyclohexyl]-2-(3, 4 -difluorophenyl)-ethane, 14% of 1-[trans-4-(trans-4-propylcyclohexyl)-cyclohexyl]-2-(3, 4-difluorophenyl)-ethane, 7% of 1-[trans-4-(trans-4-n-propylcyclohexyl)-cyclohexyl]-2- (p-fluorophenyl)-ethane, 7% of 1-[trans-4-(trans-4-n-pentylcyclohexyl)-cyclohexyl]-2- (p-fluorophenyl)-ethane, 10% of 4'-(trans-4-n-propylcyclohexyl)-3, 4-difluorobiphenyl, 10% of 4'-(trans-4-n-pentylcyclohexyl)-3, 4-difluorobiphenyl, 8% of p-fluorophenyl trans-4-(trans-4-propylcyclohexyl)-cyclohexane carboxylate and 8% of p-fluorophenyl trans-4-(trans-4-pentylcyclohexyl)-cyclohexane carboxylate shows a clearing point of 91.degree. and a birefringence .DELTA.n of 0.0871. This composition can be stored at -30.degree. without crystallization, shows a high resistivity in the order of 10.sup.13 .OMEGA..multidot.cm or more and is well suited for AMDs without reverse domain phenomena (tilt angle 4.7.degree.).

EXAMPLE 2

A liquid crystal composition consisting of

8% of trans-1-p-fluorophenyl-4-n-pentylcyclohexane, 8% of trans-1-p-fluorophenyl-4-n-hexylcyclohexane, 5% of p-fluorophenyl-trans-4-(trans-4-propylcyclohexyl)-cyclohexane carboxylate, 5% of p-fluorophenyl-trans-4-(trans-4-pentylcyclohexyl)-cyclohexane carboxylate, 11% of 4'-(trans-4-propylcyclohexyl)-3,4-difluorobiphenyl, 11% of 4'-(trans-4-pentylcyclohexyl)-3,4-difluorobiphenyl, 6% of p-[trans-4-(trans-4-ethylcyclohexyl)-cyclohexyl]-trifluoromethoxybenzene, 5% of p-[trans-4-(trans-4-propylcyclohexyl)-cyclohexyl]-trifluoromethoxybenzene, 5% of p-[trans-4-(trans-4-butylcyclohexyl)-cyclohexyl]-trifluoromethoxybenzene, 5% of p-[trans-4-(trans-4-pentylcyclohexyl)-cyclohexyl]-trifluoromethoxybenzene, 13% of 1-[trans-4-(trans-4-propylcyclohexyl)-cyclohexyl]-2-(3,4-difluorophenyl)-ethane, 12% of 1-[trans-4-(trans-4-pentylcyclohexyl)-cyclohexyl]-2-(3,4-difluorophenyl)-ethane, 3% of 1-[trans-4-(trans-4-propylcyclohexyl)-cyclohexyl]-2-(p-fluorophenyl)-ethane and 3% of 1-[trans-4-(trans-4-pentylcyclohexyl)-cyclohexyl]-2-(p-fluorophenyl)-ethan shows a clearing point of 98.degree. and a birefringence of 0.0917. This composition can be stored at -30.degree. without crystallization, shows a high resistivity in the order of 10.sup.13 .OMEGA..multidot.cm and is well suited for AMD's without reverse domain phenomena (tilt angle 4.2.degree.).

EXAMPLE 3

A liquid crystal composition consisting of

11% of trans-1-p-fluorophenyl-4-n-pentylcyclohexane, 10% of trans-1-p-fluorophenyl-4-n-hexylcyclohexane, 10% of P-fluorophenyl-trans-4-(trans-4-propylcyclohexyl)-cyclohexane carboxylate, 10% of p-fluorophenyl-trans-4-(trans-4-pentylcyclohexyl)-cyclohexane carboxylate, 11% of 4'-(trans-4-propylcyclohexyl)-3,4-difluorobiphenyl, 11% of 4'-(trans-4-pentylcyclohexyl)-3,4-difluorobiphenyl, 3% of p-[trans-4-(trans-4-ethylcyclohexyl)-cyclohexyl]-trifluoromethoxybenzene, 3% of p-[trans-4-(trans-4-propylcyclohexyl)-cyclohexyl]-trifluoromethoxybenzene, 3% of p-[trans-4-(trans-4-butylcyclohexyl)-cyclohexyl]-trifluoromethoxybenzene, 3% of p-[trans-4-(trans-4-pentylcyclohexyl)-cyclohexyl]-trifluoromethoxybenzene, 13% of 1-[trans-4-(trans-4-propylcyclohexyl)-cyclohexyl]-2-(3, 4 -di fluorophenyl)-ethane and 12% of 1-[trans-4-(trans-4-pentylcyclohexyl)-cyclohexyl]-2-(3, 4-difluorophenyl)-ethane shows a clearing point of 93.degree. and a birefringence of 0.0899. This composition can be stored at -30.degree. without crystallization, shows a high resistivity in the order of 10.sup.13 .OMEGA..multidot.cm and is well suited for AMD's without reverse domain phenomena (tilt angle 4.2.degree.).

EXAMPLE 4

A liquid crystal composition consisting of

6% of trans-1-p-fluorophenyl-4-n-pentylcyclohexane, 8% of trans-1-p-fluorophenyl-4-n-hexylcyclohexane, 4% of trans-1-p-fluorophenyl-4-n-heptylcyclohexane, 11% of 4'-(trans-4-propylcyclohexyl)-3,4-difluorobiphenyl, 11% of 4'-(trans-4-pentylcyclohexyl)-3,4-difluorobiphenyl, 6% of p-[trans-4-(trans-4-ethylcyclohexyl)-cyclohexyl]-trifluoromethoxybenzene, 6% of p-[trans-4-(trans-4-propylcyclohexyl)-cyclohexyl]-trifluoromethoxybenzene, 6% of p-[trans-4-(trans-4-butylcyclohexyl)-cyclohexyl]-trifluoromethoxybenzene, 6% of p-[trans-4-(trans-4-pentylcyclohexyl)-cyclohexyl]-trifluoromethoxybenzene, 13% of 1-[trans-4-(trans-4-propylcyclohexyl)-cyclohexyl]-2-(3,4-difluorophenyl)-ethane, 13% of 1-[trans-4-(trans-4-pentylcyclohexyl)-cyclohexyl]-2-(3,4-di fluorophenyl)-ethane, 5% of 1-[trans-4-(trans-4-propylcyclohexyl)-cyclohexyl ]-2-(p-fluorophenyl)-ethane and 5% of 1-[trans-4-(trans-4-pentylcyclohexyl)-cyclohexyl]-2-(p-fluorophenyl)-ethane shows a clearing point of 90.degree. and a birefringence of 0.0900. This composition can be stored at -30.degree. without crystallization, shows a high resistivity in the order of 10.sup.13 .OMEGA..multidot.cm and is well suited for AMD's without reverse domain phenomena (tilt angle 3.9.degree.).

EXAMPLE 5

A liquid crystal composition consisting of

10% of trans-1-p-fluorophenyl-4-n-pentylcyclohexane, 8% of trans-1-p-fluorophenyl-4-n-hexylcyclohexane, 6% of trans-1-p-fluorophenyl-4-n-heptylcyclohexane, 5% of p-trifluoromethoxyphenyl-trans-4-(trans-4-propylcyclohexyl)-cyclohexane carboxylate, 5% of p-trifluoromethoxyphenyl-trans-4-(trans-4-pentylcyclohexyl)-cyclohexane carboxylate, 12% of 4'-(trans-4-propylcyclohexyl)-3,4-difluorobiphenyl, 10% of 4'-(trans-4-pentylcyclohexyl)-3,4-difluorobiphenyl, 8% of p-[trans-4-(trans-4-ethylcyclohexyl)-cyclohexyl]-trifluoromethoxybenzene, 12% of p-[trans-4-(trans-4-propylcyclohexyl)-cyclohexyl]-trifluoromethoxybenzene, 7% of p-[trans-4-(trans-4-butylcyclohexyl)-cyclohexyl]-trifluoromethoxybenzene, 11% of p-[trans-4-(trans-4-pentylcyclohexyl)-cyclohexyl]-trifluoromethoxybenzene, 2% of 4,4'-bis-(trans-4-propylcyclohexyl)-2-fluorobiphenyl, 2% of 4,4'-bis-(trans-4-pentylcyclohexyl)-2-fluorobiphenyl and 2% of 4-(trans-4-pentylcyclohexyl)-4'-(trans-4-propylcyclohexyl)-2-fluorobiphenyl shows a clearing point of 96.degree. and a birefringence of 0.094. This composition can be stored at -30.degree. without crystallization, shows a high resistivity in the order of 10.sup.13 .OMEGA..multidot.cm and is well suited for AMD's without reverse domain phenomena (tilt angle 4.2.degree.).

EXAMPLE 6

A liquid crystal composition consisting of

10% of trans-1-p-fluorophenyl-4-n-pentylcyclohexane, 8% of trans-1-p-fluorophenyl-4-n-hexylcyclohexane, 6% of trans-1-p-fluorophenyl-4-n-heptylcyclohexane, 5% of 3,4-difluorophenyl-(trans-4-propylcyclohexylethyl)-benzoate, 5% of 3,4-difluorophenyl-(trans-4-pentylcyclohexylethyl)-benzoate, 12% of 4'-(trans-4-propylcyclohexyl)-3,4-difluorobiphenyl, 10% of 4'-(trans-4-pentylcyclohexyl)-3,4-difluorobiphenyl, 8% of p-[trans-4-(trans-4-ethylcyclohexyl)-cyclohexyl]-trifluoromethoxybenzene, 12% of P-[trans-4-(trans-4-propylcyclohexyl)-cyclohexyl]-trifluoromethoxybenzene, 7% of P-[trans-4-(trans-4-butylcyclohexyl)-cyclohexyl]-trifluoromethoxybenzene, 11% of P-[trans-4-(trans-4-pentylcyclohexyl)-cyclohexyl]-trifluoromethoxybenzene, 2% of 4,4'-bis-(trans-4-propylcyclohexyl)-2-fluorobiphenyl, 2% of 4,4'-bis-(trans-4-pentylcyclohexyl)-2-fluorobiphenyl and 2% of 4-(trans-4-pentylcyclohexyl)-4'-(trans-4-propylcyclohexyl)2-fluorobiphenyl shows a clearing point of 98.degree. and a birefringence of 0.101. This composition can be stored at -30.degree. without crystallization, shows a high resistivity in the order of 10.sup.13 .OMEGA..multidot.cm and is well suited for AMD's without reverse domain phenomena.

In the present application and in the examples below, the structures of the liquid-crystal compounds are indicated by acronyms, with the transformation into chemical formulae taking place in accordance with Tables A and B below. All radicals C.sub.n H.sub.2n+1 and C.sub.m H.sub.2m+1 are straight-chain alkyl radicals containing n or m carbon atoms. The coding in Table B is self-evident. In Table A, only the acronym for the base structure is given. In individual cases, the acronym for the base structure is followed, separated by a hyphen, by a code for the substitutents R.sup.1, R.sup.2, L.sup.1, L.sup.2 add L.sup.3.

______________________________________Code furR.sup.1, R.sup.2,L.sup.1, L.sup.2, L.sup.3 R.sup.1 R.sup.2 L.sup.1 L.sup.2 L.sup.3______________________________________nm C.sub.n H.sub.2n+1 C.sub.m H.sub.2m+1 H H HnOm C.sub.n H.sub.2n+1 OC.sub.m H.sub.2m+1 H H HnO.m OC.sub.n H.sub.2n+1 C.sub.m H.sub.2m+1 H H Hn C.sub.n H.sub.2n+1 CN H H HnN.F C.sub.n H.sub.2n+1 CN H F HnF C.sub.n H.sub.2n+1 F H H HnOF OC.sub.n H.sub.2n+1 F H H HnCl C.sub.n H.sub.2n+1 Cl H H HnF.F C.sub.n H.sub.2n+1 F H F HnOmFF C.sub.n H.sub.2n+1 OC.sub.m H.sub.2m+1 F F HnMF C.sub.n H.sub.2n+1 C.sub.m H.sub.2m+1 F H HnCF.sub.3 C.sub.n H.sub.2n+1 CF.sub.3 H H HnOCF.sub.3 C.sub.n H.sub.2n+1 OCF.sub.3 H H HnOCF.sub.2 C.sub.n H.sub.2n+1 OCHF.sub.2 H H HnS C.sub.n H.sub.2n+1 NCS H H HrVsN C.sub.r H.sub.2r+1 -- CN H H H CH.dbd.CH--C.sub.s H.sub.2s --rEsN C.sub.r H.sub.2r+1 -- CN H H H O--C.sub.s H.sub.2s --nNF C.sub.n H.sub.2n+1 CN F H HnAM C.sub.n H.sub.2n+1 COOC.sub.m H.sub.2m+1 H H HnF.F.F C.sub.n H.sub.2n+1 F H F FnCl.F.F C.sub.n H.sub.2n+1 Cl H F FnCF.sub.3.F.F C.sub.n H.sub.2n+1 CF.sub.3 H F FnOCF.sub.3.F.F C.sub.n H.sub.2n+1 OCF.sub.3 H F FnOCF.sub.2.F.F C.sub.n H.sub.2n+1 OCHF.sub.2 H F FnOCF.sub.3.F C.sub.n H.sub.2n+1 OCF.sub.3 H F H______________________________________ TABLE A__________________________________________________________________________ ##STR18## ##STR19## ##STR20## ##STR21## ##STR22## ##STR23## ##STR24## ##STR25## ##STR26## ##STR27## ##STR28## ##STR29## ##STR30## ##STR31## ##STR32## ##STR33## ##STR34## ##STR35## ##STR36## ##STR37## ##STR38## ##STR39## ##STR40## ##STR41## ##STR42## ##STR43##__________________________________________________________________________ TABLE B__________________________________________________________________________ ##STR44## ##STR45## ##STR46## ##STR47## ##STR48## ##STR49## ##STR50## ##STR51## ##STR52## ##STR53## ##STR54## ##STR55## ##STR56## ##STR57## ##STR58## ##STR59## ##STR60## ##STR61## ##STR62## ##STR63## ##STR64## ##STR65## ##STR66## ##STR67## ##STR68## ##STR69## ##STR70## ##STR71##__________________________________________________________________________

EXAMPLE 7

______________________________________S .fwdarw. N [.degree.C.] <40Clearing point [.degree.C.] +103Viscosity (mm.sup.2 s.sup.-1 ] 20.degree. C. 21.DELTA.n (589 nm, 20.degree. C.) +0.0848n.sub.e (589 nm, 20.degree. C.) 1.5559V.sub.(10,0,20) [V] 1.81V.sub.(50,0,20) [V] 2.24V.sub.(90,0,20) [V] 2.83Composition [%]: PCH-5F 5.0 PCH-7F 5.0 CCP-20CF3 8.0 CCP-30CF3 9.0 CCP-50CF3 9.0 ECCP-3F.F 11.0 ECCP-5F.F 10.0 CUP-3F.F 5.0 CUP-5F.F 4.0 CCP-30CF2.F.F 8.0 CCP-50CF2.F.F 14.0 CP-30CF3 6.0 CP-50CF3 6.0______________________________________

EXAMPLE 8

______________________________________S .fwdarw. N [.degree.C.] <-40Clearing point [.degree.C.] +99Viscosity [mm.sup.2 s.sup.-1 ] 20.degree. C. 23.DELTA.n (589 nm, 20.degree. C.) +0.0960n.sub.e (589 nm, 20.degree. C.) 1.5751V.sub.(10,0,20) [V] 1.79V.sub.(50,0,20) [V] 2.21V.sub.(90,0,20) [V] 2.81Composition [%]: PCH-5F 6.0 PCH-7F 6.0 CCP-20CF3 6.0 CCP-30CF3 8.0 CCP-50CF3 7.0 ECCP-3F.F 11.0 ECCP-5F.F 11.0 BCH-3F.F 6.0 CUP-3F.F 7.0 CUP-5F.F 6.0 CCP-30CF2.F.F 7.0 CCP-50CF2.F.F 11.0 CBC-33F 4.0 CBC-55F 4.0______________________________________

EXAMPLE 9

______________________________________S .fwdarw. N [.degree.C.] --Clearing point [.degree.C.] +93Viscosity [mm.sup.2 s.sup.-1 ] 20.degree. C. 21.DELTA.n (589 nm, 20.degree. C.) +0.0772n.sub.e (589 nm, 20.degree. C.) 1.5478V.sub.(10,0,20) [V] 1.82V.sub.(50,0,20) [V] 2.16V.sub.(90,0,20) [V] 2.78Composition [%]: PCH-5F 6.0 CCH-301 6.0 CCH-303 5.0 CCH-501 6.0 CCP-20CF3 6.0 CCP-30CF3 7.0 CCP-40CF3 6.0 CCP-50CF3 7.0 ECCP-3F.F 7.0 ECCP-5F.F 8.0 CUP-3F.F 3.0 CUP-5F.F 4.0 CCP-30CF2.F.F 11.0 CCP-50CF2.F.F 12.0 CP-30CF3 7.0______________________________________

EXAMPLE 10

______________________________________Clearing point [.degree.C.] +102Viscosity [mm.sup.2 s.sup.-1 ] 20.degree. C. --.DELTA.n (589 nm, 20.degree. C.) +0.0970n.sub.e (589 nm, 20.degree. C.) 1.5808V.sub.(10,0,20) [V] 2.15V.sub.(50,0,20) [V] 2.57V.sub.(90,0,20) [V] 3.15Composition [%]: PCH-7F 14.00 CCP-20CF3 5.00 CCP-30CF3 5.00 CCP-40CF3 5.00 CCP-50CF3 5.00 CCP-30CF3 5.00 CCP-50CF3 5.00 BCH-3F.F 14.00 BCH-5F.F 14.00 ECCP-3F 5.00 ECCP-5F 5.00 ECCP-3F.F 9.00 ECCP-5F.F 9.00______________________________________

EXAMPLE 11

______________________________________Clearing point [.degree.C.] +102Viscosity [mm.sup.2 s.sup.-1 ] 20.degree. C. 20.DELTA.n (589 nm, 20.degree. C.) +0.0952n.sub.e (589 nm, 20.degree. C.) 1.5791V.sub.(10,0,20) [V] 2.05V.sub.(50,0,20) [V] 2.51V.sub.(90,0,20) [V] 3.13Composition [%]: PCH-7F 11.00 CCP-20CF3 5.00 CCP-30CF3 5.00 CCP-40CF3 5.00 CCP-50CF3 5.00 CCP-30CF2.F.F 5.00 CCP-50CF2.F.F 5.00 BCH-3F.F 12.00 BCH-5F.F 12.00 ECCP-3F 8.00 ECCP-5F 7.00 ECCP-3F.F 10.00 ECCP-5F.F 10.00______________________________________

EXAMPLE 12

______________________________________Clearing point [.degree.C.] +73Viscosity [mm.sup.2 s.sup.-1 ] 20.degree. C. --.DELTA.n (589 nm, 20.degree. C.) +0.0879n.sub.e (589 nm,, 20.degree. C.) 1.5688V.sub.(10,0,20) [V] 1.56V.sub.(50,0,20) [V] 1.88V.sub.(90,0,20) [V] 2.32Composition [%]: PCH-5F 8.00 PCH-7F 8.00 CCP-20C-73 5.00 CCP-30CF3 6.00 CCP-40CF3 6.00 CCP-50CF3 6.00 ECCP-3F.F 5.00 ECCP-5F.F 5.00 BCH-3F.F.F 14.00 BCH-5F.F.F 13.00 CCP-3F.F.F 9.00 CCP-5F.F.F 9.00______________________________________

EXAMPLE 13

______________________________________Clearing point [.degree.C.] 95Viscosity [mm.sup.2 s.sup.-1 ] 20.degree. C. --.DELTA.n (589 nm, 20.degree. C.) 0.089n.sub.e (589 nm, 20.degree. C.) 1.567V.sub.(10,0,20) [V] 1.97V.sub.(50,0,20) [V] --V.sub.(90,0,20) [V] 2.86Composition [%]: CP-30CF3 10.00 CP-50CF3 10.00 PCH-5F 8.00 PCH-6F 7.00 PCH-7F 6.00 CCP-20CF3 7.00 CCP-30CF3 7.00 CCP-40CF3 7.00 CCP-50CF3 7.00 ECCP-3F.F 5.00 ECCP-5F.F 5.00 BCH-3F.F 11.00 BCH-5F.F 10.00______________________________________

EXAMPLE 14

______________________________________Clearing point [.degree.C.] +93Viscosity [mm.sup.2 s.sup.-1 ] 20.degree. C. --.DELTA.n (589 nm, 20.degree. C.) +0.0899n.sub.e (589 nm, 20.degree. C.) 1.5765V.sub.(10,0,20) [V] 2.02V.sub.(50,0,20) [V] 2.43V.sub.(90,0,20) [V] 3.00Composition [%]: PCH-5F 11.00 PCH-6F 10.00 CP-3F 10.00 CP-5F 10.00 BCH-3F.F 11.00 BCH-5F.F 11.00 CCP-20CF3 3.00 CCP-30CF3 3.00 CCP-40CF3 3.00 CCP-50CF3 3.00 ECCP-3F.F 13.00 ECCP-5F.F 12.00______________________________________

EXAMPLE 15

______________________________________Clearing point [.degree.C.] +100Viscosity [mm.sup.2 s.sup.-1 ] 20.degree. C. --.DELTA.n (589 nm, 20.degree. C.) +0.0971n.sub.e (589 nm, 20.degree. C.) 1.5823V.sub.(10,0,20) [V] 1.99V.sub.(50,0,20) [V] 2.43V.sub.(90,0,20) [V] 2.96Composition [%]: PCH-7F 12.00 CCP-20CF3 5.00 CCP-30CF3 5.00 CCP-40CF3 5.00 CCP-50CF3 5.00 CCP-30CF2.F.F 3.00 CCP-50CF2.F.F 3.00 BCH-3F.F 14.00 BCH-5F.F 14.00 ECCP-3F 7.00 ECCP-5F 7.00 ECCP-3F.F 10.00 ECCP-5F.F 10.00______________________________________

EXAMPLE 16

______________________________________S .fwdarw. N [.degree.C.] <-40Clearing point [.degree.C.] +100Viscosity [mm.sup.2 s.sup.-1 ] 20.degree. C. 19Viscosity [mm.sup.2 s.sup.-1 ] 0.degree. C. 55Viscosity [mm.sup.2 s.sup.-1 ] -20.degree. C. 276Viscosity [mm.sup.2 s.sup.-1 ] -30.degree. C. 767Viscosity [mm.sup.2 s.sup.-1 ] -40.degree. C. 2609.DELTA.n (589 nm, 20.degree. C.) +0.0929n.sub.e (589 nm, 20.degree. C.) 1.5722V.sub.(10,0,20) [V] 1.95V.sub.(50,0,20) [V] 2.33V.sub.(90,0,20) [V] 2.86Composition [%]: PCH-5F 6.00 PCH-6F 3.00 PCH-7F 5.00 BCH-3F.F 9.00 BCH-5F.F 6.00 CCP-20CF3 8.00 CCP-30CF3 9.00 CCP-40CF3 5.00 CCP-50CF3 8.50 ECCP-3F.F 8.50 ECCP-5F.F 8.50 ECCP-30CF3 2.50 CUP-3F.F 3.50 CUP-5F.F 3.00 CCP-30CF2.F.F 3.50 CCP-50CF2.F.F 5.50 CBC-33F 3.00 CBC-53F 2.50______________________________________

EXAMPLE 17

______________________________________S .fwdarw. N [.degree.C.] --Clearing point [.degree.C.] 83Viscosity [mm.sup.2 s.sup.-1 ] 20.degree. C. --.DELTA.n (589 nm, 20.degree. C.) 0.0884n.sub.e (589 nm, 20.degree. C.) 1.5635V.sub.(10,0,20) [V] 1.41V.sub.(50,0,20) [V] --V.sub.(90,0,20) [V] 2.44Composition [%]: PCH-6F 4.00 PCH-7F 9.00 CCP-20CF3 5.00 CCP-30CF3 5.00 CCP-40CF3 5.00 CCP-50CF3 5.00 ECCP-3F.F 5.00 ECCP-5F.F 5.00 BCH-3F.F 5.00 BCH-5F.F 5.00 CUP-3F.F 6.00 CUP-5F.F 6.00 CCP-30CF2.F.F 15.00 CCP-50CF2.F.F 20.00______________________________________

EXAMPLE 18

______________________________________S .fwdarw. N [.degree.C.] --Clearing point [.degree.C.] +83Viscosity [mm.sup.2 s.sup.-1 9 20.degree. C. --.DELTA.n (589 nm, 20.degree. C.) +0.0970n.sub.e (589 nm, 20.degree. C.) 1.5753V.sub.(10,0,20) [V] 1.61V.sub.(50,0,20) [V] 1.93V.sub.(90,0,20) [V] 2.37Composition [%]: PCH-6F 3.00 PCH-7F 9.00 CCP-20CF3 5.00 CCP-30CF3 5.00 CCP-40CF3 5.00 CCP-50CF3 5.00 BCH-3F.F 10.00 BCH-5F.F 10.00 CUP-3F.F 6.00 CUP-5F.F 6.00 CCP-30CF2.F.F 15.00 CCP-50CF2.F.F 20.00 CBC-33F 1.00______________________________________

EXAMPLE 19

______________________________________S .fwdarw. N [.degree.C.] --Clearing point [.degree.C.] +83Viscosity [mm.sup.2 s.sup.-1 9 20.degree. C. 18Viscosity [mm.sup.2 s.sup.-1 9 0.degree. C. 51Viscosity [mm.sup.2 s.sup.-1 9 -20.degree. C. 248Viscosity [mm.sup.2 s.sup.-1 9 -30.degree. C. 693Viscosity [mm.sup.2 s.sup.-1 9 -40.degree. C. 2515.DELTA.n (589 nm, 20.degree. C.) +0.0885n.sub.e (589 nm, 20.degree. C.) 1.5680V.sub.(10,0,20) [V] 1.72V.sub.(50,0,20) [V] 3.10V.sub.(90,0,20) [V] 2.62Composition [%]: PCH-5F 6.00 PCH-6F 6.00 PCH-7F 6.00 CCP-20CF3 8.00 CCP-30CF3 7.00 CCP-50CF3 7.00 ECCP-3F.F 10.00 ECCP-5F.F 10.00 CCP-30CF2.F.F 10.00 CCP-50CF2.F.F 10.00 BCH-3F.F 10.00 BCH-5F.F 10.00______________________________________

EXAMPLE 20

______________________________________S .fwdarw. N [.degree.C.] --Clearing point [.degree.C.] +76Viscosity [mm.sup.2 s.sup.-1 9 20.degree. C. 21Viscosity [mm.sup.2 s.sup.-1 9 0.degree. C. 64.DELTA.n (589 nm, 20.degree. C.) +0.0900n.sub.e (589 nm, 20.degree. C.) 1.5665V.sub.(10,0,20) [V] 1.59V.sub.(50,0,20) [V] 1.92V.sub.(90,0,20) [V] 2.37Composition [%]: PCH-7F 10.00 CCH-303 9.00 CCP-20CF3 8.00 CCP-30CF3 8.00 CCP-50CF3 8.00 BCH-3F.F 8.00 BCH-5F.F 8.00 CUP-3F.F 8.00 CUP-5F.F 8.00 CCP-30CF2.7.F 10.00 CCP-50CF2-7.F 15.00______________________________________

EXAMPLE 21

______________________________________S .fwdarw. N [.degree.C.] --Clearing point [.degree.C.] +92.DELTA.n (589 nm, 20.degree. C.) +0.0928n.sub.e (589 nm, 20.degree. C.) 1.5736V.sub.(10,0,20) [V] 1.68V.sub.(50,0,20) [V] 2.02V.sub.(90,0,20) [V] 2.53Composition [%]: PCH-5F 4.00 PCH-7F 4.00 CCP-20CF3 7.00 CCP-30CF3 7.00 CCP-40CF3 7.00 CCP-50CF3 8.00 ECCP-3F.F 8.00 ECCP-5F.F 8.00 BCH-3F.F.F 14.00 BCH-5F.F.F 13.00 CCP-3F.F.F 9.00 CCP-5F.F.F 9.00 CBC-33F 2.00______________________________________

EXAMPLE 22

______________________________________S.fwdarw.N [.degree.C.] --Clearing point [.degree.C.] +77.DELTA.n (589 nm, 20.degree. C.) +0.0893n.sub.e (589 nm, 20.degree. C.) 1.5704V.sub.(10,0,20) [V] 1.49V.sub.(50,0,20) [V] 1.81V.sub.(90,0,20) [V] 2.22Composition [%]: PCH-5F 8.00 PCH-7F 6.00 CCP-20CF3 6.00 CCP-30CF3 7.00 CCP-40CF3 6.00 CCP-50CF3 6.00 ECCP-3F.F 8.00 ECCP-5F.F 8.00 BCH-3F.F.F 14.00 BCH-5F.F.F 13.00 CCP-3F.F.F 9.00 CCP-5F.F.F 9.00______________________________________

EXAMPLE 23

______________________________________S.fwdarw.N [.degree.C.] --Clearing point [.degree.C.] +86.DELTA.n (589 nm, 20.degree. C.) +0.0954n.sub.e (589 nm, 20.degree. C.) 1.5728V.sub.(10,0,20) [V] 1.59V.sub.(50,0,20) [V] 1.94V.sub.(90,0,20) [V] 2.41Composition [%]: PCH-6F 3.00 PCH-7F 7.00 CCP-20CF3 5.00 CCP-30CF3 5.00 CCP-40CF3 5.00 CCP-50CF3 5.00 ECCP-3F.F 5.00 BCH-3F.F 9.00 BCH-5F.F 9.00 CUP-3F.F 6.00 CUP-5F.F 6.00 CCP-30CF2.F.F 15.00 CCP-50CF2.F.F 20.00______________________________________

EXAMPLE 24

______________________________________S.fwdarw.N [.degree.C.] --Clearing point [.degree.C.] +81Viscosity [mm.sup.2 s.sup.-1 ] 20.degree. C. 23.DELTA.n (589 nm, 20.degree. C.) +0.0914n.sub.e (589 nm, 20.degree. C.) 1.5684V.sub.(10,0,20) [V] 1.64V.sub.(50,0,20) [V] 1.97V.sub.(90,0,20) [V] 2.41Composition [%]: PCH-7F 8.00 CCH-303 8.00 CCP-20CF3 7.00 CCP-30CF3 7.00 CCP-50CF3 7.00 BCH-3F.F 9.00 BCH-5F.F 10.00 CCP-3F.F 7.00 CCP-5F.F 7.00 CCP-30CF2.F.F 15.00 CCP-50CF2.F.F 15.00______________________________________

EXAMPLE 25

______________________________________S.fwdarw.N [.degree.C.] --Clearing point [.degree.C.] +92.DELTA.n (589 rim, 20.degree. C.) +0.0969n.sub.e (589 nm, 20.degree. C.) 1.5684V.sub.(10,0,20) [V] 1.69V.sub.(50,0,20) [V] 2.06V.sub.(90,0,20) [V] 2.55Composition [%]: PCH-6F 6.00 PCH-7F 6.00 CCP-20CF3 4.00 CCP-30CF3 4.00 CCP-50CF3 4.00 BCH-3F.F 6.00 BCH-5F.F 6.00 ECCP-3F.F 8.00 ECCP-5F.F 8.00 CUP-3F.F 8.00 CUP-5F.F 8.00 CCP-30CF3.F.F 10.00 CCP-50CF2.F.F 15.00 CBC-33F 3.00 CBC-55F 4.00______________________________________

EXAMPLE 26

______________________________________S.fwdarw.N [.degree.C.] --Clearing point +92.DELTA.n (589 nm, 20.degree.C.) +0.0929n.sub.e (589 nm, 20.degree. C.) 1.5694V.sub.(10,0,20) [V] 1.80V.sub.(50,0,20) [V] 2.18V.sub.(90,0,20) [V] 2.66Composition [%]: HP-30CF3 5.00 HP-50CF3 5.00 CP-30CF3 8.00 CP-50CF3 8.00 PCH-5F 8.00 PCH-6F 8.00 PCH-7F 8.00 CCP-20CF3 8.00 CCP-30CF3 8.00 CCP-40CF3 8.00 CCP-50CF3 8.00 BCH-3F.F 9.00 BCH-5F.F 9.00______________________________________

EXAMPLE 27

______________________________________S.fwdarw.N [.degree.C.] <-40Clearing point [.degree.C.] +105Viscosity [mm.sup.2 s.sup.-1 ] 20.degree. C. 19Viscosity [mm.sup.2 s.sup.-1 ] 0.degree. C. 57Viscosity [mm.sup.2 s.sup.-1 ] -20.degree. C. 312Viscosity [mm.sup.2 s.sup.-1 ] -30.degree. C. 941Viscosity [mm.sup.2 s.sup.-1 ] -40.degree. C. 3828.DELTA.n (589 nm, 20.degree. C.) +0.0914n.sub.e (589 nm, 20.degree. C.) 1.5777V.sub.(10,0,20) [V] 2.10V.sub.(50,0,20) [V] 2.55V.sub.(90,0,20) [V] 3.15Composition [%]: PCH-5F 7.00 PCH-6F 7.00 PCH-30CF3 8.00 PCH-50CF3 8.00 ECCP-3F 12.00 ECCP-5F 12.00 BCH-3F.F 11.00 BCH-5F.F 11.00 ECCP-3F.F 12.00 ECCP-5F.F 12.00______________________________________

EXAMPLE 28

______________________________________S.fwdarw.N [.degree.C.] --Clearing point [.degree.C.] +83.DELTA.n (589 nm, 20.degree. C.) +0.0903n.sub.e (589 nm, 20.degree. C.) 1.5689V.sub.(10,0,20) [V] 1.88V.sub.(50,0,20) [V] 2.25V.sub.(90,0,20) [V] 2.76Composition [%]: PCH-5F 5.00 PCH-6F 13.00 PCH-7F 7.00 CCP-20CF3 10.00 CCP-30CF3 11.00 CCP-40CF3 10.00 CCP-50CF3 12.00 BCH-3F.F 12.00 BCH-5F.F 12.00 CP-30CF3 4.00 CP-50CF3 4.00______________________________________

EXAMPLE 29

______________________________________S.fwdarw.N [.degree.C.] --Clearing point [.degree.C.] +102.DELTA.n (589 nm, 20.degree. C.) +0.0939n.sub.e (589 nm, 20.degree. C.) 1.5767V.sub.(10,0,20) [V] 2.18V.sub.(50,0,20) [V] 2.59V.sub.(90,0,20,) [V] 3.16Composition [%]: PCH-6F 7.00 PCH-7F 7.00 CCP-20CF3 6.00 CCP-30CF3 6.00 CCP-50CF3 4.00 CP-30CF3 7.00 CP-50CF3 6.00 ECCP-3F 6.00 ECCP-5F 4.00 ECCP-3F.F 13.00 ECCP-5F.F 11.00 BCH-3F.F 12.00 BCH-5F.F 11.00______________________________________

EXAMPLE 30

______________________________________S.fwdarw.N [.degree.C.] --Clearing point [.degree.C.] +103.DELTA.n (589 nm, 20.degree. C.) +0.0928n.sub.e (589 nm, 20.degree. C.) 1.5752V.sub.(10,0,20) [V] 2.30V.sub.(50,0,20) [V] 2.70V.sub.(90,0,20) [V] 3.30Composition [%]: PCH-5F 7.00 PCH-6F 7.00 CP-30CF3 6.00 CP-50CF3 6.00 BCH-3F.F 11.00 BCH-5F.F 11.00 CCP-20CF3 6.00 CCP-30CF3 6.00 CCP-40CF3 4.00 CCP-50CF3 5.00 ECCP-3F.F 10.00 ECCP-5F.F 10.00 ECCP-3F 6.00 ECCP-5F 5.00______________________________________

EXAMPLE 31

______________________________________S.fwdarw.N [.degree.C.] --Clearing point [.degree.C.] +93.DELTA.n (589 nm, 20.degree. C.) +0.0955n.sub.e (589 nm, 20.degree. C.) 1.5845V.sub.(10,0,20) [V] 2.11V.sub.(50,0,20) [V] 2.52V.sub.(90,0,20) [V] 3.08Composition [%]: PCH-5F 10.00 PCH-6F 9.00 CP-30CF3 5.00 CP-50CF3 5.00 BCH-3F.F 13.00 BCH-5F.F 14.00 HP-30CF3 2.00 BCH-32 2.00 ECCP-3F.F 10.00 ECCP-5F.F 10.00 ECCP-3F 10.00 ECCP-5F 10.00______________________________________

EXAMPLE 32

______________________________________S.fwdarw.N [.degree.C.] <-40Clearing point [.degree.C.] 96Viscosity [mm.sup.2 s.sup.-1 ] 20.degree. C. 15Viscosity [mm.sup.2 s.sup.-1 ] 0.degree. C. 41Viscosity [mm.sup.2 s.sup.-1 ] -20.degree. C. 189Viscosity [mm.sup.2 s.sup.-1 ] -30.degree. C. 581Viscosity [mm.sup.2 s.sup.-1 ] -40.degree. C. 1882.DELTA.n (589 nm, 20.degree. C.) 0.0940n.sub.e (589 nm, 20.degree. C.) 1.5733V.sub.(10,0,20) [V] 2.08V.sub.(50,0,20) [V] 2.16V.sub.(90,0,20) [V] 3.01Composition [%]: PCH-5F 10.00 PCH-6F 8.00 PCH-7F 6.00 CCP-20CF3 8.00 CCP-30CF3 12.00 CCP-40CF3 7.00 CCP-50CF3 11.00 BCH-3F.F 12.00 BCH-5F.F 10.00 CCP-30CF3 5.00 CCP-50CF3 5.00 CBC-33F 2.00 CBC-53F 2.00 CBC-53F 2.00______________________________________

EXAMPLE 33

______________________________________S.fwdarw.N [.degree.C.] --Clearing point [.degree.C.] 96.DELTA.n (589 nm, 20.degree. C.) 0.0923n.sub.e (589 nm, 20.degree. C.) 1.5656V.sub.(10,0,20) [V] 1.52V.sub.(50,0,20) [V] --V.sub.(90,0,20,) [V] 2.33Composition [%]: PCH-5F .00 PCH-7F 5.00 CCP-20CF3 6.00 CCP-30CF3 6.00 CCP-50CF3 5.00 ECCP-3F.F 5.00 BCH-3F.F 4.00 BCH-5F.F 4.00 CCP-20CF2.F.F 17.00 CCP-30CF2.F.F 19.00 CCP-50CF2.F.F 21.00 CUP-3F.F 4.00 CUP-5F.F 4.00______________________________________

EXAMPLE 34

______________________________________S.fwdarw.N [.degree.C.] --Clearing point [.degree.C.] +106.DELTA.n (589 nm, 20.degree. C.) +0.0928n.sub.e (589 nm, 20.degree. C.) 1.5752V.sub.(10,0,20) [V] 2.42V.sub.(50,0,20) [V] 2.89V.sub.(90,0,20) [V] --Composition [%]: PCH-5F 7.00 PCH-6F 7.00 CP-30CF3 10.00 CP-50CF3 10.00 BCH-3F.F 11.00 BCH-5F.F 11.00 CCP-20CF3 3.00 CCP-30CF3 3.00 CCP-40CF3 3.00 CCP-50CF3 3.00 ECCP-3F 6.00 ECCP-5F 6.00 ECCP-3F.F 10.00 ECCP-5F.F 10.00______________________________________

EXAMPLE 35

______________________________________S.fwdarw.N [.degree.C.] --Clearing point [.degree.C.] +103.DELTA.n (589 nm, 20.degree. C.) +0.0932n.sub.e (589 nm, 20.degree. C.) 1.5731V.sub.(10,0,20) [V] 2.11V.sub.(50,0,20) [V] 2.52V.sub.(90,0,20) [V] 3.07Composition [%]: PCH-6F 7.00 PCH-7F 6.00 CCP-20CF3 7.00 CCP-30CF3 7.00 CCP-40CF3 7.00 CCP-50CF3 7.00 CP-30CF3 6.00 CP-50CF3 6.00 ECCP-3F.F 13.00 ECCP-5F.F 11.00 BCH-3F.F 12.00 BCH-5F.F 11.00______________________________________

EXAMPLE 36

______________________________________S.fwdarw.N [.degree.C.] --Clearing point [.degree.C.] +100.DELTA.n (589 nm, 20.degree. C.) +0.0924n.sub.e (589 nm, 20.degree. C.) 1.5733V.sub.(10,0,20) [V] 2.06V.sub.(50,0,20) [V] 2.45V.sub.(90,0,20) [V] 2.96Composition [%]: PCH-6F 7.00 PCH-7F 8.00 CCP-20CF3 7.00 CCP-30CF3 7.00 CCP-40CF3 7.00 CCP-50CF3 7.00 ECCP-3F 5.00 ECCP-5F 3.00 ECCP-3F.F 13.00 ECCP-5F.F 11.00 BCH-3F.F 10.00 BCH-5F.F 4.00 HP-30CF3 6.00 HP-50CF3 5.00______________________________________

EXAMPLE 37

______________________________________S.fwdarw.N [.degree.C.] <-40Clearing point [.degree.C.] 96Viscosity [mm.sup.2 s.sup.-1 ] 20.degree. C. 15Viscosity [mm.sup.2 s.sup.-1 ] 0.degree. C. 41Viscosity [mm.sup.2 s.sup.-1 ] -20.degree. C. 189Viscosity [mm.sup.2 s.sup.-1 ] -30.degree. C. 581Viscosity [mm.sup.2 s.sup.-1 ] -40.degree. C. 1882.DELTA.n (589 nm, 20.degree. C.) 0.0940n.sub.e (589 nm, 20.degree. C.) 1.5733V.sub.(10,0,20) [V] 2.08V.sub.(50,0,20) [V] 2.16V.sub.(90,0,20) [V] 3.01Composition [%]: PCH-5F 10.00 PCH-6F 8.00 PCH-7F 6.00 CCP-20CF3 8.00 CCP-30CF3 12.00 CCP-40CF3 7.00 CCP-50CF3 11.00 BCH-3F.F 12.00 BCH-5F.F 10.00 CP-30CF3 5.00 CP-50CF3 5.00 CBC-33F 2.00 CBC-53F 2.00 CBC-55F 2.00______________________________________

EXAMPLE 38

______________________________________S.fwdarw.N [.degree.C.] --Clearing point [.degree.C.] +95.DELTA.n (589 nm, 20.degree. C.) +0.0902n.sub.e (589 nm, 20.degree. C.) 1.5774V.sub.(10,0,20) [V] 2.40V.sub.(50,0,20) [V] 2.84V.sub.(90,0,20) [V] 3.50Composition [%]: PCH-5F 11.00 PCH-6F 11.00 CP-30CF3 8.00 CP-50CF3 8.00 BCH-3F.F 8.00 BCH-5F.F 8.00 BCH-32 3.00 BCH-52 3.00 ECCP-3F.F 10.00 ECCP-5F.F 10.00 ECCP-3F 10.00 ECCP-5F 10.00______________________________________

EXAMPLE 39

______________________________________S.fwdarw.N [.degree.C.] --Clearing point [.degree.C.] +92.DELTA.n (589 nm, 20.degree. C.) +0.0958n.sub.e (589 nm, 20.degree. C.) 1.5859V.sub.(10,0,20) [V] 2.17V.sub.(50,0,20) [V] 2.61V.sub.(90,0,20) [V] 3.25Composition [%]: PCH-5F 10.00 PCH-6F 9.00 CP-30CF3 4.00 CP-50CF3 4.00 BCH-3F.F 13.00 BCH-5F.F 14.00 BCH-32 3.00 ECCP-3F.F 11.00 ECCP-5F.F 11.00 ECCP-3F 11.00 ECCP-5F 10.00______________________________________

EXAMPLE 40

______________________________________S.fwdarw.N [.degree.C.] --Clearing point [.degree.C.] +91.DELTA.n (589 nm, 20.degree. C.) +0.0871n.sub.e (589 nm, 20.degree. C.) 1.5758V.sub.(10,0,20) [V] 2.14 (1st)V.sub.(50,3,20) [V] 2.59V.sub.(90,0,20) [V] 3.21Composition [%]: PCH-5F 11.00 PCH-6F 11.00 CP-3F 8.00 CP-5F 8.00 ECCP-3F 7.00 ECCP-5F 7.00 BCH-3F.F 10.00 BCH-5F.F 10.00 ECCP-3F.F 14.00 ECCP-5F.F 14.00______________________________________

EXAMPLE 41

______________________________________S.fwdarw.N [.degree.C.] --Clearing point [.degree.C.] +88.DELTA.n (589 nm, 20.degree. C.) +0.0891n.sub.e (589, nm, 20.degree. C.) 1.5754V.sub.(10,0,20) [V] 1.98 (1st)V.sub.(50,0,20) [V] 2.39V.sub.(90,0,20) [V] 2.96Composition [%]: PCH-5F 12.00 PCH-6F 11.00 CP-3F 9.00 CP-5F 9.00 BCH-3F.F 11.00 BCH-5F.F 11.00 CCP-20CF3 3.00 CCP-30CF3 3.00 CCP-40CF3 3.00 CCP-50CF3 3.00 ECCP-3F.F 13.00 ECCP-5F.F 12.00______________________________________

EXAMPLE 42

______________________________________S.fwdarw.N[.degree.C.] --Clearing point [.degree.C.] 85.DELTA.n (589 nm, 20.degree. C.) 0.089n.sub.e (589 nm, 20.degree. C.) 1.569V.sub.(10,0,20) [V] 1.90V.sub.(50,0,20) [V] --V.sub.(90,0,20) [V] 2.83Composition [%]: CP-30CF3 10.00 PCH-5F 9.00 PCH-6F 7.20 PCH-7F 7.20 CCP-20CF3 8.10 CCP-30CF3 8.10 CCP-40CF3 8.10 CCP-50CF3 8.10 ECCP-3F.F 5.40 ECCP-5F.F 5.40 BCH-3F.F 11.70 BCH-5F.F 11.70______________________________________

EXAMPLE 43

______________________________________S.fwdarw.N [.degree.C.] --Clearing point [.degree.C.] +107Viscosity [mm.sup.2 s.sup.-1 ] 20.degree. C. 18Viscosity [mm.sup.2 s.sup.-1 ] 0.degree. C. 53Viscosity [mm.sup.2 s.sup.-1 ] -20.degree. C. 268Viscosity [mm.sup.2 s.sup.-1 ] -30.degree. C. 782Viscosity [mm.sup.2 s.sup.-1 ] -40.degree. C. 3174.DELTA.n (589 nm, 20.degree. C.) +0.0956n.sub.e (589 nm, 20.degree. C.) 1.5758V.sub.(10,0,20) [V] 2.00V.sub.(50,0,20) [V] 2.42V.sub.(90,0,20) [V] 2.97Composition [%]: PCH-5F 6.00 PCH-6F 6.00 CCP-20CF3 5.00 CCP-30CF3 6.00 CCP-40CF3 4.00 CCP-50CF3 5.00 BCH-3F.F 12.00 BCH-5F.F 12.00 ECCP-3F.F 12.00 ECCP-5F.F 12.00 CP-30CF3 10.00 CP-50CF3 10.00______________________________________

EXAMPLE 44

______________________________________S.fwdarw.N [.degree.C.] --Clearing point [.degree.C.] +104Viscosity [mm.sup.2 s.sup.-1 ] 20.degree. C. 18Viscosity [mm.sup.2 s.sup.-1 ] 0.degree. C. 53Viscosity [mm.sup.2 s.sup.-1 ] -20.degree. C. 272Viscosity [mm.sup.2 s.sup.-1 ] -30.degree. C. 789Viscosity [mm.sup.2 s.sup.-1 ] -40.degree. C. 3010.DELTA.n (589 nm, 20.degree. C.) +0.0954n.sub.e (589 nm, 20.degree. C.) 1.5786V.sub.(10,0,20) [V] 2.09V.sub.(50,0,20) [V] 2.53V.sub.(90,0,20) [V] 3.13Composition [%]: PCH-5F 6.00 PCH-6F 6.00 CCP-20CF3 6.00 CCP-30CF3 5.00 CCP-40CF3 4.00 CCP-50CF3 5.00 BCH-3F.F 12.00 BCH-5F.F 12.00 ECCP-3F.F 12.00 ECCP-5F.F 12.00 ECCP-3F 5.00 ECCP-5F 5.00 CP-30CF3 5.00 CP-50CF3 5.00______________________________________

EXAMPLE 45

______________________________________S.fwdarw.N [.degree.C.] --Clearing point [.degree.C.] 109.DELTA.n (589 nm, 20.degree. C.) 0.094n.sub.e (589 nm, 20.degree. C.) 1.571V.sub.(10,0,20) [V] 2.18V.sub.(50,0,20) [V] --V.sub.(90,0,20) [V] --Composition [%]: CP-30CF3 10.00 CP-50CF3 10.00 PCH-5F 8.00 PCH-6F 6.40 PCH-7F 4.80 CCP-20CF3 6.40 CCP-30CF3 9.60 CCP-40CF3 5.60 CCP-50CF3 8.80 BCH-3F.F 9.60 BCH-5F.F 8.00 ECCP-30CF3 4.00 ECCP-50CF3 4.00 CBC-33F 1.60 CBC-53F 1.60 CBC-55F 1.60______________________________________

EXAMPLE 46

______________________________________S.fwdarw.N [.degree.C.] --Clearing point [.degree.C.] +100.DELTA.n (589 nm, 20.degree. C.) +0.0944n.sub.e (589 nm, 20.degree. C.) 1.5750V.sub.(10,0,20) [V] 1.94V.sub.(50,0,20) [V] 2.33V.sub.(90,0,20) [V] 2.87Composition [%]: PCH-5F 10.00 PCH-6F 9.00 CCP-20CF3 6.00 CCP-30CF3 7.00 CCP-40CF3 5.00 CCP-50CF3 7.00 BCH-3F.F 8.00 BCH-5F.F 8.00 ECCP-3F.F 11.00 ECCP-5F.F 11.00 CCP-30CF2.F.F 5.00 CCP-50CF2.F.F 4.00 CBC-33F 5.00 CBC-55F 4.00______________________________________

EXAMPLE 47

______________________________________S.fwdarw.N [.degree.C.] --Clearing point [.degree.C.]: +101.DELTA.n (589 nm, 20.degree. C.) +0.0942n.sub.e (589 nm, 20.degree. C.) 1.5769V.sub.(10,0,20) [V] 2.15V.sub.(50,0,20) [V] 2.56V.sub.(90,0,20) [V] 3.11Composition [%]: PCH-5F 7.00 PCH-6F 7.00 CUP-3F.F 2.00 CCP-20CF3 6.00 CCP-30CF3 6.00 CCP-40CF3 5.00 CCP-50CF3 6.00 BCH-3F.F 10.00 BCH-5F.F 9.00 ECCP-3F.F 11.00 ECCP-5F.F 11.00 CCP-30CF2.F.F 4.00 CCP-50CF2.F.F 3.00 CP-30CF3 5.00 CP-50CF3 5.00 CBC-33F 3.00______________________________________

EXAMPLE 48

______________________________________S.fwdarw.N [.degree.C.] --Clearing point [.degree.C.] 83.DELTA.n (589 nm, 20.degree. C.) 0.093n.sub.e (589 nm, 20.degree. C.) 1.574V.sub.(10,0,20) [V] 1.81V.sub.(50,0,20) [V] --V.sub.(90,0,20) [V] --Composition [%]: HP-30CF3 5.00 HP-50CF3 5.00 PCH-5F 9.00 PCH-6F 7.20 PCH-7F 7.20 CCP-20CF3 8.10 CCP-30CF3 8.10 CCP-40CF3 8.10 CCP-50CF3 8.10 ECCP-3F.F 5.40 ECCP-5F.F 5.40 BCH-3F.F 11.70 BCH-5F.F 11.70______________________________________

EXAMPLE 49

______________________________________S.fwdarw.N [.degree.C.] --Clearing point [.degree.C.] 101.DELTA.n (589 nm, 20.degree. C.) 0.0975n.sub.e (589 nm, 20.degree. C.) 1.5797V.sub.(10,0,20) [V] 2.04V.sub.(50,0,20) [V] 2.42V.sub.(90,0,20) [V] 2.94Composition [%]: PCH-6F 7.00 PCH-7F 7.00 CCH-502 2.00 CCP-20CF3 6.00 CCP-30CF3 6.00 CCP-40CF3 6.00 CCP-50CF3 6.00 ECCP-3F.F 11.00 ECCP-5F.F 11.00 BCH-3F.F 8.00 BCH-5F.F 8.00 CUP-3F.F 3.00 CUP-5F.F 3.00 CCP-30CF2.F.F 4.00 CCP-50CF2.F.F 4.00 CBC-33F 4.00 CBC-53F 4.00______________________________________

EXAMPLE 50

______________________________________S.fwdarw.N [.degree.C.] --Clearing point [.degree.C.] +101Viscosity [mm.sup.2 s.sup.-1 ] 20.degree. C. 17Viscosity [mm.sup.2 s.sup.-1 ] 0.degree. C. 50Viscosity [mm.sup.2 s.sup.-1 ] -20.degree. C. 230Viscosity [mm.sup.2 s.sup.-1 ] -30.degree. C. SmecticViscosity [mm.sup.2 s.sup.-1 ] -40.degree. C. --.DELTA.n (589 nm, 20.degree. C.) +0.0941n.sub.e (589 nm, 20.degree. C.) 1.5733V.sub.(10,0,20) [V] 2.04V.sub.(50,0,20) [V] 2.49V.sub.(90,0,20) [V] 3.07Composition [%]: PCH-5F 10.00 PCH-6F 10.00 CCP-20CF3 6.00 CCP-30CF3 7.00 CCP-40CF3 5.00 CCP-50CF3 7.00 BCH-3F.F 8.00 BCH-5F.F 7.00 ECCP-3F 2.00 ECCP-3F.F 12.00 ECCP-5F.F 12.00 CCP-30CF2.F.F 3.00 CCP-50CF2.F.F 3.00 CBC-33F 4.00 CBC-53F 4.00______________________________________

EXAMPLE 51

______________________________________S.fwdarw.N [.degree.C.%] --Clearing point [.degree.C.] +102Viscosity [mm.sup.2 s.sup.-1 ] 20.degree. C. 16Viscosity [mm.sup.2 s.sup.-1 ] 0.degree. C. 47Viscosity [mm.sup.2 s.sup.-1 ] -20.degree. C. 222Viscosity [mm.sup.2 s.sup.-1 ] -30.degree. C. 634Viscosity [mm.sup.2 s.sup.-1 ] -40.degree. C. Sm.DELTA.n (589 nm, 20.degree. C.) +0.0876n.sub.e (589 nm, 20.degree. C.) 1.5631V.sub.(10,0,20) [V] 2.10 (1st)V.sub.(50,0,20) [V] 2.54V.sub.(90,0,20) [V] 3.11Composition [%]: PCH-5F 8.00 PCH-6F 8.00 CP-3F 5.00 CP-5F 5.00 BCH-3F.F 7.00 BCH-5F.F 7.00 CCP-20CF3 8.00 CCP-30CF3 7.00 CCP-40CF3 7.00 CCP-50CF3 7.00 ECCP-3F.F 9.00 ECCP-5F.F 8.00 CCP-30CF2.F.F 7.00 CCP-50CF2.F.F 7.00______________________________________

EXAMPLE 52

______________________________________PCH-5F 5% T.sub.NI 92.degree. C.PCH-7F 6% .DELTA.n 0.091CCP-30CF3 12% V.sub.10 1.50 VCCP-50CF3 11% tilt angle .crclbar. 3.7.degree.CCP-30CF3.F 11%CCP-50CF3.F 10%BCH-30CF3.F 12%BCH-3F.F.F 11%CCP-3F.F.F 12%CCP-5F.F.F 9%______________________________________

EXAMPLE 53

______________________________________PCH-5F.F 11% T.sub.NI 85.degree. C.CCP-3F.F 12% .DELTA.n 0.086CCP-5F.F 11% V.sub.10 1.45 VCCP-3F.F.F 11% tilt angle .crclbar. 3.8.degree.CCP-5F.F.F 10%BCH-3F.F 12%BCH-5F.F 10%BCH-3F.F.F 12%BCH-5F.F.F 10%______________________________________

EXAMPLE 54

______________________________________EPCH-5F.F 5% T.sub.NI 88.degree. C.EPCH-7F.F 6% .DELTA.n 0.083CCP-3F.F 10% tilt angle .crclbar. 4.3.degree.CCP-5F.F 11%CCP-30CF3 12%CCP-50CF3 10%BCH-3F.F 11%BCH-5F.F 12%CCP-30CF2.F.F 9%CCP-50CF2.F.F 14%______________________________________

Claims

1. A nematic liquid-crystal composition comprising:

8 to 70% by weight of one or more compounds from group 1: ##STR72## wherein R.sup.1 is a straight-chain alkyl group of 2 to 5 carbon atoms,

E.sup.1 is ##STR73## L is H or F, and Q is OCF.sub.2, OCFH, OCFCl or a single bond;

8to 60% by weight of one or more compounds from group 2: ##STR74## wherein R.sup.2 is a straight-chain alkyl group of 2 to 5 carbon atoms,

E.sup.2 is ##STR75## and L, in each case, is H or F; and

8to 40% by weight of one or more compounds from group 3 selected from formulae 3a-3f: ##STR76## wherein R.sup.3 is a straight-chain alkyl group of 2 to 5 carbon atoms.

2. A nematic liquid-crystal composition according to claim 1, wherein said composition contains one or more compounds from each of groups 1 a and 1b: ##STR77## wherein R.sup.1 is a straight-chain alkyl group of 2 to 5 carbon atoms;

L is H or F; and

Q is OCF.sub.2, OCFH, OCFCl or a single bond.

3. A nematic liquid-crystal composition according to claim 1, wherein said composition contains one or more compounds of the following formula: ##STR78## wherein R.sup.2 is a straight-chain alkyl group of 2 to 5 carbon atoms; and

L is H or F.

4. A nematic liquid crystal composition according to claim 2, wherein Q is a single bond and L is F.

5. A composition according to claim 1, wherein said composition contains more than 12% by weight of one or more compounds of group 1.

6. A composition according to claim 1, wherein said composition contains one or more compounds of group 1 wherein L is F and Q is a single bond.

7. A nematic liquid-crystal composition comprising:

8 to 70% by weight of one or more compounds from group 1: ##STR79## wherein R.sup.1 is a straight-chain alkyl group of 2 to 5 carbon atoms,

E.sup.1 is ##STR80## L is H or F, and Q is OCF.sub.2, OCFH, OCFCl or a single bond;

8to 60% by weight of one or more compounds from group 2: ##STR81## wherein R.sup.2 is a straight-chain alkyl group of 2 to 5 carbon atoms,

E.sup.2 is ##STR82## and L, in each case, is H or F; and

8to 40% by weight of one or more compounds from group 3 selected from formulae 3a-3f: ##STR83## wherein R.sup.3 is a straight-chain alkyl group of 2 to 5 carbon atoms; and

wherein said composition contains one or more compounds of group 1 wherein Q is OCF.sub.2, OCFH or OCFCl and L is H or F.

8. A nematic liquid-crystal composition comprising:

8 to 70% by weight of one or more compounds from group 1: ##STR84## wherein R.sup.1 is a straight-chain alkyl group of 2 to 5 carbon atoms,

E.sup.1 is ##STR85## L is H or F, and Q is OCF.sub.2, OCFH, OCFCl or a single bond;

8to 60% by weight of one or more compounds from group 2: ##STR86## wherein R.sup.2 is a straight-chain alkyl group of 2 to 5 carbon atoms,

E.sup.2 is ##STR87## and L, in each case, is H or F; and

8to 40% by weight of one or more compounds from group 3 selected from formulae 3a-3f: ##STR88## wherein R.sup.3 is a straight-chain alkyl group of 2 to 5 carbon atoms; and

said composition further comprises one or more compounds of group 0 ##STR89## wherein R.sup.0 is a straight-chain alkyl of 2 to 5 carbon atoms,

E.sup.0 is --(CH.sub.2).sub.4 --, --(CH.sub.2).sub.2 --, --CO--O-- or a single bond,

L is H or F, and

Q is OCF.sub.2, OCFH, OCFCl, CF.sub.2 or a single bond.

9. A composition according to claim 1, wherein said composition contains 30-60 wt. % of compounds of group 1.

10. A composition according to claim 1, wherein said composition contains 12-40% of compounds of group 2.

11. A composition according to claim 1, wherein said composition contains 12-30 wt. % of compounds of group 3.

12. A composition according to claim 8, wherein said composition contains 5-30% of compounds of group 0.

13. A composition according to claim 8, wherein said composition contains 5-30 wt. % of compounds of group 0, 30-60 wt. % of compounds of group 1, 12-40 wt. % of compounds of group 2, and 12-30 wt. % of compounds of group 3.

14. A composition according to claim 13, wherein said composition contains 10-25% of compounds of group 0, 35-55 wt. % of compounds of group 1, 15-25 wt. % of compounds of group 2, and 15-25 wt. % of compounds of group 3.

15. A composition according to claim 1, wherein said composition contains at least 60% of compounds of groups 1, 2 and 3.

16. A composition according to claim 1, wherein said composition contains 8-70 wt. % of compounds of group 1.

17. A composition according to claim 1, wherein said composition contains 8-60 wt. % of compounds of group 2.

18. A composition according to claim 1, wherein said composition contains 8-40 wt. % of compounds of group 3.

19. A composition according to claim 1, wherein said compositions contains 8-70 wt. % of compounds of group 1, 8-60 wt. % of compounds of group 2, and 8-40 wt. % of compounds of group 3.

20. A composition according to claim 7, wherein said composition comprises 8-70 wt. % of one or more compounds from group 1, 8-60 wt. % of one or more compounds from group 2, and 8-40 wt. % of one or more compounds from group 3.

21. A composition according to claim 8, wherein said composition comprises 8-70 wt. % of one or more compounds from group 1, 8-60 wt. % of one or more compounds from group 2, and 8-40 wt. % of one or more compounds from group 3.

22. A composition according to claim 7, wherein said composition further contains one or more compounds of group 1 wherein L is F and Q is a single bond.

23. A composition according to claim 22, wherein the weight ratio of compounds of group 1 wherein L is F and Q is a single bond to the compounds of group 1 wherein Q is OCF.sub.2, OCFH or OCFCl and L is H or F is .gtoreq.1.

24. A composition according to claim 23, wherein said weight ratio is .gtoreq.2:1.

25. A composition according to claim 8, wherein said composition contains one or more compounds of group 0 wherein E.sup.0 is --(CH.sub.2).sub.2 -- or a single bond, Q is a single bond and one L group is H and the other L group is H or F.

26. A nematic liquid-crystal composition according to claim 6, wherein said composition contains one or more compounds from each of groups 1 a and 1b: ##STR90## wherein R.sup.1 is a straight-chain alkyl group of 2 to 5 carbon atoms;

L is H or F; and

Q is OCF.sub.2, OCFH, OCFCl or a single bond.

27. A nematic liquid-crystal composition comprising:

8 to 70% by weight of one or more compounds from group 1: ##STR91## wherein R.sup.1 is a straight-chain alkyl group of 2 to 5 carbon atoms,

E.sup.1 is ##STR92## L is H or F, and Q is OCF.sub.2, OCFH, OCFCl or a single bond;

8to 60% by weight of one or more compounds from group 2: ##STR93## wherein R.sup.2 is a straight-chain alkyl group of 2 to 5 carbon atoms,

E.sup.2 is ##STR94## and L, in each case, is H or F; and

said composition contains at least one compound of formulae 3a-3f ##STR95## wherein R.sup.3 is a straight-chain alkyl group of 2 to 5 carbon atoms.

28. A nematic liquid-crystal composition comprising:

8 to 60% by weight of one or more compounds from group 2: ##STR96## wherein R.sup.2 is a straight-chain alkyl group of 2 to 5 carbon atoms,

E.sup.2 is ##STR97## and L, in each case, is H or F; and

said composition contains at least one compound of formulae 3a-3f ##STR98## wherein R.sup.3 is a straight-chain alkyl group of 2 to 5 carbon atoms.