DE10152831A1 - Liquid crystal composition used in e.g. electrooptical liquid crystal displays, contains a tetra-fluorinated ester - Google Patents

Abstract

A liquid crystal composition based on a mixture of polar compounds of positive dielectric anisotropy contains a tetra-fluorinated ester (I). A liquid crystal composition based on a mixture of polar compounds of positive dielectric anisotropy contains a tetra-fluorinated ester of formula (I). R = 1-12C alkyl, alkoxy or alkenyl with 1 or 2 non-adjacent CH2 groups optionally replaced by -O-, -CH=CH-, -CO-, -OCO- or -COO- such that O atoms are not directly bonded to each other.

Description

The present invention relates to a liquid-crystalline medium, as well its use for electro-optical purposes and this medium containing ads.

Liquid crystals are mainly used as dielectrics in display devices used because the optical properties of such substances by a applied voltage can be influenced. Electro-optical Vorrich Solutions based on liquid crystals are well suited to the expert known and can be based on various effects. Such Vor directions are, for example, cells with dynamic scattering, DAP Cells (upright phase deformation), guest / host cells, TN cells with twisted nematic structure, STN cells ("super twisted nematic "), superbirefringence effect (SBE) cells and OMI cells ("optical mode interference"). The most common display devices are based on the Schadt-Helfrich effect and have a twisted nema table structure.

The liquid crystal materials need a good chemical and thermal Stability and good stability to electric fields and have electromagnetic radiation. Furthermore, the liquid crystal should materials have low viscosity and short in the cells Response times, low threshold voltages and high contrast result.

Furthermore, they should at normal operating temperatures, d. H. in one the widest possible range below and above room temperature have suitable mesophase, for example for the above Cells a nematic or cholesteric mesophase. Because liquid Crystals usually as mixtures of several components to the application It is important that the components are good with each other are miscible. Other properties, such as electrical conductivity, the Dielectric anisotropy and optical anisotropy, depending on Cell type and application area meet different requirements For example, materials for cells should be twisted nematic  Structure a positive dielectric anisotropy and a low elek have trical conductivity.

For example, for matrix liquid crystal displays with integrated ones are not linear elements for switching individual pixels (MFK displays) Media with high positive dielectric anisotropy, broad nematic Phases, relatively low birefringence, very high specific Resistance, good UV and temperature stability and low vapor pressure he wishes.

Such matrix liquid crystal displays are known. As non-linear elements for individual switching of the individual pixels, for example, active elements (ie transistors) can be used. One speaks then of an "active matrix", whereby one can distinguish two types:

• 1. MOS (Metal Oxide Semiconductor) or other diodes on silicon Wafer as a substrate.
• 2. Thin-film transistors (TFT) on a glass plate as a substrate.

The use of monocrystalline silicon as a substrate material be limits the display size, as well as the modular composition various partial displays at the joints leads to problems.

In the promising type 2, which is preferred, as electro optical effect commonly used the TN effect. One differentiates two technologies: TFTs made of compound semiconductors such as CdSe or TFTs based on polycrystalline or amorphous silicon. On The latter technology is being worked on worldwide with great intensity.

The TFT matrix is on the inside of a glass plate of the display applied while the other glass plate on the inside the trans carries a parent counterelectrode. Compared to the size of the pixel Electrode, the TFT is very small and does not disturb the picture practically. These Technology can also be extended for fully color-capable image displays  being a mosaic of red, green and blue filters like this is arranged that each filter element a switchable pixel is opposite.

The TFT displays usually work as TN cells with crossed ones Polarizers in transmission and are backlit.

The term MFK displays here includes any matrix display with integrated nonlinear elements, d. H. in addition to the active matrix also ads with passive elements such as varistors or diodes (MIM = metal-insulator Metal).

Such MFK displays are particularly suitable for TV applications (eg pocket TV) or for high-information displays for computers applications (laptop) and in automotive or aircraft construction. Next Problems with the angular dependence of the contrast and the Switching times result in MFK displays due to difficulties Insufficient high resistivity of the liquid crystal mixtures [TOGASHI, S., SEKIGUCHI, K., TANABE, H., YAMAMOTO, E., SORIMACHI, K., TAJIMA, E., WATANABE, H., SHIMIZU, H., Proc. Eurodisplay 84, Sept. 1984: A 210-288 Matrix LCD Controlled by Double Stage Diode Rings, p. 141 ff, Paris; STROMER, M., Proc. Eurodisplay 84, Sept. 1984: Design of Thin Film Transistor for Matrix Addressing of Tele vision Liquid Crystal Displays, p. 145 ff, Paris]. With decreasing cons The contrast of a MFK display deteriorates and it can Problem of "after image elimination" occur. Because the specific Resistance of the liquid crystal mixture by interaction with the internal surfaces of the display generally over the lifetime MFK display decreases, a high (initial) resistance is very high important to maintain acceptable service life. Especially at low-volt Mixtures were previously not possible, very high specific To realize resistances. Furthermore, it is important that the specific Resistance the smallest possible increase with increasing temperature as well as after temperature and / or UV exposure. Especially after also the low temperature properties of the mixtures from the State of the art. It is required that even at low temperatures  no crystallization and / or smectic phases occur and the tem Temperature dependence of the viscosity is as low as possible. The MFK ads from the prior art thus do not meet today's requirements requirements.

There is thus still a great need for MFK displays very high specific resistance with at the same time big work temperature range, short switching times even at low temperatures and low threshold voltage, these disadvantages are not or only in show a lesser degree.

In TN (Schadt-Helfrich) cells, media are desired which allow the following advantages in the cells:

• - extended nematic phase range (especially to deep temperatures)
• - Switchability at extremely low temperatures (out-door-use, Automobile, avionics)
• - increased resistance to UV radiation (longer life permanently)

With the media available from the prior art It does not allow these benefits while preserving the rest To realize parameters.

For higher-twisted cells (STN), media are required, those higher Multiplexibility and / or lower threshold voltages and / or porridge tern nematic phase ranges (especially at low temperatures) enable. For this purpose, a further expansion of the available standing parameter space (clearing point, transition smectic-nematic or melting point, viscosity, dielectric values, elastic sizes) urgently desired.  

The invention is based, media especially for the task provide MFK, TN, or STN displays similar to those listed above give disadvantages or only to a lesser extent, and preferably at the same time very high resistivities and low thresholds have voltages.

For some applications it would be particularly desirable to have the To further reduce viscosity at low temperatures. This will be even faster switching times achieved.

It has now been found that the objects described above are achieved can be, if one in ads according to the invention media used.

The invention thus relates to a liquid-crystalline medium based on a mixture of polar compounds having a positive dielectric shear anisotropy, characterized in that it contains one or more compounds of the formula I.

where R is an alkyl group having 1 to 12 C atoms, whereby also one or two non-adjacent CH ₂ groups may be replaced by -O-, -CH = CH-, -CO-, -OCO- or -COO-, that O atoms are not directly linked together means.

The compounds of the formula I effect in the inventive Media a reduction in threshold voltage at the same time Optimization of the low-temperature behavior.

The compounds of the formula I have a broad application Area. These compounds can serve as base materials for the most part composed of liquid-crystalline media  are; but it can also be compounds of the formula I liquid crystalline Base materials from other classes of compounds can be added to for example, the dielectric and / or optical anisotropy of a to influence such dielectric and / or its Threshold voltage and / or to optimize its viscosity.

The compounds of the formula I are colorless in the pure state and form liquid-crystalline mesophases in one for electro-optical use conveniently located temperature range. Chemical, thermal and against Light are they stable. The compounds of the formula I are per se known methods as described in the literature (eg in the Standard works such as Houben-Weyl, Methods of Organic Chemistry, Georg Thieme Verlag, Stuttgart) are described, under Reaction conditions known for the said reactions and are suitable. It is also known by itself, not here make use of the variants mentioned.

The invention also provides electro-optical displays (esp STN or MFK displays with two plane-parallel support plates, the with a border forming a cell, integrated nonlinear Elements for switching individual pixels on the support plates and a nematic liquid crystal mixture in the cell with positive dielectric anisotropy and high resistivity), containing such media and the use of these media for electro-optical purposes.

The liquid-crystal mixtures according to the invention enable a be significant extension of the available parameter space. Thus, the achievable combinations of clarification point and viscosity exceed low temperature, thermal and UV stability and dielectric Anisotropy far prior materials of the prior art.

The requirement for a high clearing point, nematic phase at low temperature, high Δε and at the same time low viscosity was so far only insufficiently fulfilled. Although previously known mixtures have comparably high values for the clearing point and for Δε and a favorable birefringence, they still do not have sufficiently low values for the rotational viscosity γ ₁ .

Other mixing systems have comparable viscosities and Values of Δε, however, have only clearing points in the region of 60 ° C.

The liquid-crystal mixtures according to the invention make it possible with Retention of the nematic phase to -20 ° C and preferably to -30 ° C, particularly preferably to -40 ° C, clearing points above 80 °, preferably above 85 °, more preferably above 90 ° C, simultaneously dielek trical anisotropy values Δε ≧ 5, preferably ≧ 7 and a high value to achieve the specific resistance, resulting in excellent STN and MKF displays can be achieved. In particular, the Mixtures characterized by small operating voltages. The TN thresholds are below 2.0 V, preferably below 1.8 V, more preferably <1.6 V.

It is understood that by suitable choice of components of the inventions mixtures according to the invention also have higher clearing points (eg above 110 ° C.) at higher threshold voltage or lower clearing points at low lower threshold voltages to obtain the other beneficial properties can be realized. Likewise, in accordance with little increased viscosities mixtures with larger As and thus lower thresholds are obtained. The MFK invention Ads work preferably in the first transmission minimum Gooch and Tarry [C. H. Gooch and H.A. Tarry, Electron. Lett. 10, 2-4, 1974; C.H. Gooch and H.A. Tarry, Appl. Phys., Vol. 8, 1575-1584, 1975], Here, in addition to particularly favorable electro-optical properties such z. B. high slope of the curve and low angle dependence of the Contrast (DE-PS 30 22 818) at the same threshold voltage as in an analog display in the second minimum a smaller dielectric Anisotropy is sufficient. This can be done using the Mixtures according to the invention in the first minimum significantly higher specific resistances realize than with mixtures with Cyanver bonds. The skilled person can by suitable choice of the individual Components and their proportions by simple routine  the required for a given layer thickness of the MFK display Set birefringence.

The rotational viscosity γ ₁ at 20 ° C is preferably <150 mPa.s, FITS preferred <130 mPa.s. The nematic phase range is preferential, at least 90 °, in particular at least 100 °. Preferably, this range extends at least from -20 ° to + 80 °.

Measurements of the Capacity Holding Ratio (HR) [p. Matsumoto et al., Liquid Crystals 5, 1320 (1989); K. Niwa et al., Proc. SID Conference, San Francisco, June 1984, p. 304 (1984); G. Weber et al., Liquid Crystals 5, 1381 (1989)] have shown that inventive mixtures enthal tend compounds of formula I have a significantly smaller decrease in HR with increasing temperature than analogous mixtures containing instead of the compounds of formula I Cyanophenylcyclohexane the formula

or esters of the formula

In addition, it has been shown that inventive mixtures ent Compounds of formula I have a higher clearing point and higher As have as analogous mixtures containing cyanophenylcyclo hexane of o. g. Formula. Compared to the latter mixtures furthermore, the mixtures according to the invention have a smaller Δn on, which is advantageous for many applications.

The UV stability of the mixtures according to the invention is considerable better, d. H. they show a much smaller decrease in HR UV exposure.

The proportion of the compounds of formula I in the total mixture of Media according to the invention is preferably 2-55%, preferably 3-35%, and more preferably 5-15%.  

The individual compounds of the formulas I to XII and their sub-formulas, which can be used in the media according to the invention are either known, or they can analogously to the known Verbindun be prepared.

Preferred embodiments are given below:
The medium additionally contains one or more compounds selected from the group consisting of the general formulas II to VII:

wherein the individual radicals have the following meanings
R ⁰ n-alkyl, alkoxy, fluoroalkyl, alkenyl or oxaalkenyl having in each case up to 9 C atoms,
Z ¹ CF ₂ O, C ₂ F ₄ or a single bond,
Z ² CF ₂ O, C ₂ F ₄ or C ₂ H ₄ ,
X ⁰ F, Cl, halogenated alkyl, alkenyl or alkoxy having 1 to 6 C atoms,
Y ¹ and Y ^{2 are} each independently H or F, and
r 0, or 1.

The compounds of formula IV are preferably selected from the following group

wherein R ⁰ and X ^{0 have} the meaning given in formula II, R ⁰ particularly preferably n-alkyl having 1 to 8 carbon atoms or alkenyl having 2 to 7 carbon atoms and X ^{0 is} preferably OCF ₃ or F, particularly preferably F , Particular preference is given to compounds of the formulas IVa and IVf;

The compounds of formula VI are preferably selected from the following group

wherein R ⁰ and X ^{0 have} the meaning given in Formei II, R ⁰ particularly preferably n-alkyl having 1 to 8 carbon atoms or alkenyl having 2 to 7 carbon atoms and X ^{0 is} preferably OCF ₃ or F, particularly preferably F , Particular preference is given to compounds of the formula VIa, VIb and VIc;

The compounds of formula VII are preferably selected from the following group

wherein R ⁰ and X ^{0 have} the meaning given in formula II, R ⁰ particularly preferably n-alkyl having 1 to 8 carbon atoms or alkenyl having 2 to 7 carbon atoms and X ^{0 is} preferably OCF ₃ or F, particularly preferably F , Particular preference is given to compounds of the formulas VIIa and VIIb;

The compounds of the formula II are preferably selected from the following group:

wherein R ⁰ and X ^{0 have} the meaning given in formula II, R ⁰ particularly preferably n-alkyl having 1 to 8 carbon atoms or alkenyl having 2 to 7 carbon atoms and X ⁰ particularly preferably F, Cl, CF ₃ , OCF ₃ or OCHF ₂ ;

The medium additionally contains one or more compounds selected from the following group:

wherein R ⁰ , X ⁰ , Y ¹ and Y ^{2 have} the meaning given in formula I, Y ^{3 is} H or F and X ^{0 is} preferably F, Cl, CF ₃ , OCF ₃ , OCHF ₂ , and X ⁰ additionally also alkyl, Oxaalkyl, fluoroalkyl or alkenyl each having 1 to 6 carbon atoms.

The medium contains further compounds, preferably selected from the following group:

wherein R ⁰ and X ^{0 have} the meaning given in formula II, X ⁰ additionally may also mean alkyl, oxaalkyl, fluoroalkyl or alkenyl each having 1 to 6 carbon atoms, and the 1,4-phenylene substituted by CN, chlorine or fluorine could be. Preferably, the 1,4-phenylene rings are mono- or polysubstituted by fluorine atoms.

Particularly preferred are the compounds selected from the following group

wherein R ⁰ and X ^{0 have} the meaning given in formula XV and XVIII, LH or F, preferably F, R ⁰ particularly preferably n-alkyl having 1 to 8 carbon atoms or alkenyl having 2 to 7 carbon atoms, and X ⁰ in formula XVa, XVb and XVIIIa preferably F or Cl, in formula XVc and XVd preferably alkyl or alkoxy having 1 to 6 carbon atoms.

The medium additionally contains one or more compounds selected from the following group:

wherein R ⁰ , Y ¹ , Y ² , X ⁰ and r have the meaning given in formula II, X has one of the meanings given for X ⁰ or CN, and L ¹ and L ^{2 are} each independently H or F.

The compounds are particularly preferably selected from the following group:

in which R ⁰ and X ^{0 have} the meaning given in formulas XIX and XX, R ⁰ particularly preferably n-alkyl having 1 to 8 C atoms or alkenyl having 2 to 7 C atoms, and X ⁰ particularly preferably F, Cl, CF ₃ , OCF ₃ or OCHF ₂ , in particular F, in formula XXd, in particular OCF ₃ .

The medium additionally contains one or more compounds selected from the following group:

wherein R ¹ and R ^{2 are} each independently alkyl or alkoxy having 1 to 8 carbon atoms or alkenyl having 2 to 7 carbon atoms and LH or F.

In the compounds of the formulas XXII, XXIII and XXIV, R ¹ and R ^{2 are} preferably alkyl or alkoxy having 1 to 8 C atoms.

The compounds are particularly preferably selected from the following group:

wherein R ^1a and R ^{2a are} each independently H, CH ₃ , C ₂ H ₅ or nC ₃ H ₇ , alkyl is an alkyl group having 1 to 7 C atoms, s is 0 or 1 and L is H or F.

is preferable

• R ⁰ is straight-chain alkyl or alkenyl having 2 to 7 C atoms;
• The medium contains compounds selected from the formulas II, III, IV, V, VI, VII, XIX, XX, XXI, XXII, XIII and XXIV;
• - The medium contains one or more compounds selected from the formulas VIa, VIb, VIc, VIIa and IVf;
• The weight ratio I: (II + III + IV + V + VI + VII) is preferred 1: 10 to 10: 1;
• The medium consists essentially of compounds selected from the group consisting of the general formulas I to XIII and XIX to XXIV;  
• - The proportion of compounds of formula I is in the total mixture From 2 to 55% by weight, in particular from 3 to 35% by weight, very particularly preferably 5 to 15% by weight;
• - The proportion of compounds of formulas I to VII is taken together at least 50% by weight in the total mixture;
• - The proportion of compounds of formulas II to VII and XIX to XXIV in the total mixture is 30 to 95 wt .-%;
• - The proportion of compounds of formula XIX is in Total mixture less than 28%.

It has been found that even a relatively small proportion of Verbindun gene of formula I in admixture with conventional liquid crystal materials, but in particular special with one or more compounds of formula II, III, IV, V, VI and / or VII to a considerable reduction of Threshold voltage and too low values for the birefringence leads, at the same time broad nematic phases are observed with low transition temperatures smectic-nematic, whereby the storage stability is improved. Particular preference is given to mixtures which, in addition to one or more compounds of the formula I, contain one or more compounds of the formula IV, in particular compounds of the formula IVa, in which X ⁰ denotes F or OCF ₃ . The compounds of formulas I to VII are colorless, stable and well miscible with each other and with other liquid crystal materials.

The term "alkyl" includes straight-chain and branched alkyl groups with 1-7 carbon atoms, in particular the straight-chain groups methyl, Ethyl, propyl, butyl, pentyl, hexyl and heptyl. Groups of 2-5 coals Atoms are generally preferred.

The term "alkenyl" includes straight-chain and branched alkenyl groups having 2-7 carbon atoms, especially the straight-chain groups. Especially alkenyl groups are C ₂ -C ₇ -1E-alkenyl, C ₄ -C ₇ 3E-alkenyl, C ₅ -C ₇ -alkenyl, C ₆ -C ₇ -5-alkenyl and C ₇ -6-alkenyl, in particular C ₂ -C ₇ -1E-alkenyl, C ₄ -C ₇ -EE-alkenyl and C ₅ -C ₇ -alkenyl. Examples of preferred alkenyl groups are vinyl, 1E-propenyl, 1E-butenyl, 1E-pentenyl, 1E-hexenyl, 1E-heptenyl, 3-butenyl, 3E-pentenyl, 3E-hexenyl, 3E-heptenyl, 4-pentenyl, 42-hexenyl, 4E-hexenyl, 42-heptenyl, 5-hexenyl, 6-heptenyl and the like. Groups of up to 5 carbon atoms are generally preferred.

The term "fluoroalkyl" preferably includes straight-chain groups terminal fluorine, d. H. Fluoromethyl, 2-fluoroethyl, 3-fluoropropyl, 4-fluoro butyl, 5-fluoropentyl, 6-fluorohexyl and 7-fluoroheptyl. Other positions However, the fluorine are not excluded.

The term "oxaalkyl" preferably includes straight-chain radicals of the formula CnH _{2n + 1} -O- (CH ₂ ) _m , wherein n and m are each independently 1 to 6. Preferably, n = 1 and m is 1 to 6.

By suitable choice of the meanings of R ⁰ and X ⁰ , the on speaking times, the threshold voltage, the transconductance of the transmission characteristics, etc. can be modified in the desired manner. For example, 1E-alkenyl radicals, 3E-alkenyl radicals, 2E-alkenyloxy radicals and the like generally lead to shorter response times, improved nematic tendencies and a higher ratio of the elastic constants k ₃₃ (bend) and k ₁₁ (splay) compared to alkyl - or alkoxy radicals. 4-Alkenyl radicals, 3-alkenyl radicals and the like generally give lower threshold voltages and smaller values of k ₃₃ / k ₁₁ compared to alkyl and alkoxy radicals.

A -CH ₂ CH ₂ group generally results in higher values of k ₃₃ / k ₁₁ compared to a single covalent bond. Higher values of k ₃₃ / k ₁₁ allow z. B. flatter transmission characteristics in TN cells with 90 ° twist (to achieve shades of gray) and steeper transmission characteristics in STN, SBE and OMI cells (higher multiplexability) and vice versa.

The optimum ratio of the compounds of the formulas I and II + III + IV + V + VI + VI depends largely on the desired  Properties, of the choice of the components of the formulas I, II, III, IV, V, VI and / or VII and the choice of any other existing ones Components off. Suitable proportions within the above specified range can be easily determined on a case-by-case basis.

The total amount of compounds of formulas I to XXIV in the inventions The mixtures according to the invention are not critical. The mixtures can therefore one or more other components included for optimization different properties. The observed effect on the response times and the threshold voltage, however, is generally greater higher is the total concentration of compounds of formulas I to XXIV.

In a particularly preferred embodiment, the inventions to the invention media compounds of formula II to VII (preferably II, III and / or IV, in particular IVa), wherein X ⁰ F, OCF ₃ , OCHF ₂ , F, OCH = CF ₂ , OCF CF ₂ or OCF ₂ -CF ₂ H means. A favorable synergistic effect with the compounds of the formula I leads to particularly advantageous properties. In particular, mixtures containing Ver compounds of the formula I and the formula IVa are characterized by their low threshold voltages.

The structure of the MFK display of polarizers according to the invention, Electrode base plates and electrodes with surface treatment corresponds to the usual for such displays construction. It is the Concept of customary construction here broad and includes all Modifications and modifications of the MFK display, in particular also Matrix display elements based on poly-Si TFT or MIM.

A significant difference of the displays according to the invention to the hitherto customary on the basis of the twisted nematic cell however, in the choice of the liquid crystal parameters of the liquid crystal layer.

The preparation of the liquid crystal which can be used according to the invention Mixtures takes place in a conventional manner. In general, the ge desired amount of components used in lesser amount the components constituting the main component are solved, purpose  moderately at elevated temperature. It is also possible solutions of the Kom components in an organic solvent, e.g. In acetone, chloroform or methanol, and the solvent after mixing to remove again, for example by distillation.

The dielectrics may also other, known in the art and in the Literature described additives contain. For example, 0-15% pleochroic dyes or chiral dopants are added.

In the present application and in the following examples, the structures of the liquid crystal compounds are indicated by acronyms, wherein the transformation into chemical formulas according to following Tables A and B takes place. All radicals C _n H _{2 + 1} and C _m H _{2m + 1} are straight-chain alkyl radicals with n or m C atoms. The coding according to Table B is self-evident. In Table A, only the acronym for the basic body is given. In the individual case, a code for the substituents R ¹ , R ² , L ¹ and L ² follows separately from the acronym for the main body with a dash:

Preferred mixture components are given in Tables A and B.

Table A

Table B

The following examples are intended to illustrate the invention without limiting it. It uses the following abbreviations:
Mp means melting point, clp. = Clearing point. Furthermore, K = crystalline state, N = nematic phase, S = smectic phase and I = isotropic phase. The data between these symbols represent the transition temperatures [° C]. V _10,0,20 denotes the voltage [V] for 10% transmission at 0 ° viewing angle (viewing direction perpendicular to the plate surface) and 20 ° C. t _on denotes the switch-on time and t _off the switch-off time [ms] at an operating voltage corresponding to twice the value of V ₁₀ . Δn denotes the optical anisotropy and n _o the refractive index at 589 nm. Δε denotes the dielectric anisotropy at 1 kHz (Δε = ε _{∥ -ε ┴} , where ε _{∥ denotes} the dielectric constant parallel to the _longitudinal molecular _axes and ε _┴ the dielectric constant perpendicular thereto). γ ₁ means the rotational viscosity [mPa.sec]. The electro-optical data were measured in a TN cell at the 1st minimum (ie at a d.Δn value of 0.5) at 20 ° C, unless expressly stated otherwise. All data above was measured at 20 ° C, unless expressly stated otherwise.

Above and below, percentages are by weight. All Temperatures are given in degrees Celsius.

example 1

Containing a liquid-crystalline medium

CCP 2F.F.F 8.00% CCP 3F.F.F 10.00% CCP 20CF3.F 6:00 am% CCP 40CF3 3:00% CCP 30CF3 8.00% CGU-2-F 11.00% CGU-3-F 11.00% CGU-5-F 5.00% CCZU-2-F 5.00% CCZU-3-F 15.00% CCZU-5-F 5.00% CUZG-3-F 10.00% CC-3-V1 3:00% Clp .: + 72.5 @ S-N transition: -30 Δn: + 0.0902 @ V _10,0,20 : 1,04 @ γ ₁ : 166

has a low threshold voltage and cheap Cryogenic behavior on.

Example 2

Containing a liquid-crystalline medium

PCH-5F 8:50% PCH-6 6.80% PCH 7 10.05% CCP 20CF3 6.80% CCP 30CF3 10.20% CCP 40CF3 6:00 am% CCP 50CF3 30.09% BCH 3F.F 10.30% BCH SF.F 8:50% ECCP 30CF3 20.04% ECCP 50CF3 20.04% CBC-33F 1.70% CBC-53F 1.70% CBC-55F 1.70% CUZG-3 15.00% Cl: + 87 @ S-N junction: @ Δn: + 0.0917 @ Δ∈ + 6.40

Example 3

Containing a liquid-crystalline medium

ME2 N.F 4:00% ME3 N.F 4:00% ME5N.F 15.00% ME7N.F 14.00% HP 3N.F 2:00% HP 4N.F 5.00% HP SN.F 5.00% PCH-301 3:00% CCH 303 6:00 am% CCH 501 13.00% CCPC-33 5.00% CCPC-34 6:00 am% CCPC-35 6:00 am% CUZG-3 12:00%

Example 4

Containing a liquid-crystalline medium

FET 3F.F 13.00% FET 5F.F 11.00% GGP-3-Cl 8.00% GGP-5-Cl 14.00% CUZG-2-F 12:00% CUZG-3-F 11.00% PGIGI-3-F 4:00% T-2FF3 12:00% GGP 5-3 10.00% CBC 33 5.00% Clp .: 85.5 @ Δn: 0.1952 @ Δε: + 11.2 @ V ₁₀ : 1.43 @ γ ₁ : 382

Example 5

Containing a liquid-crystalline medium

CCH-34 5.00% CCP 2F.F.F 11.00% CCP 3F.F.F 11.00% CCP 20CF3.F 10.00% CCP 30CF3 8.00% CCP 40CF3 5.00% CGU-2-F 9.00% CGU-3-F 9.00% CGU-5-F 4:00% CPZG-2-OT 2:00% CPZG-3-OT 4:00% CUZG-2-F 9.00% CUZG-3-F 11.00% CBC 33 2:00% Clp .: 71.0 @ Δn: 0.0910 @ V ₁₀ : 1.04 @ γ ₁ : 158

Example 6

Containing a liquid-crystalline medium

CC-3-V1 1:50% CCP 2F.F.F 10.00% CCP 3F.F.F 11.00% CCP 20CF3.F 7:00% CCP 40CF3 8.00% CCP 40CF3 8.00% CGU-2-F 10.00% CGU-3-F 10.00% CGU-5-F 3:00% CCZU-3-F 9.00% CUZG-2-F 10.00% CUZG-3-F 11.00% CBC 33 1:50% Cl: 71.5 @ Δn: 0.0913 @ V ₁₀ : 1.03 @ γ ₁ : 166

Example 7

Containing a liquid-crystalline medium

BCH-32 3:00% CCP 2F.F.F 11.00% CCP 3F.F.F 11.00% CCP 20CF3.F 3:00% BCH 3F.F.F 3:00% CCP 30CF3 8.00% CCP 40CF3 5.00% CGU-2-F 9.00% CGU-3-F 9.00% CCZU-2-F 3:00% CCZU-3-F 12:00% CUZG-2-F 11.00% CUZG-3-F 12:00%

Example 8

Containing a liquid-crystalline medium

CH-3F.F 10.79% BCH SF.F 9.00% ECCP 30CF3 4:50% ECCP 50CF3 4:50% CBC-33F 1.80% CBC-53F 1.80% CBC-55F 1.80% PCH-6F 20.07% PCH-7F 5:40% CCP 20CF3 20.07% CCP 30CF3 10.79% CCP 40CF3 06.30% CCP 50CF3 9.89% PCH-5F 9.00% CUZG-5-F 10.05% Clp .: 90.3 @ Δn: 0.0976 @ Δε: +6.4

Example 9

Containing a liquid-crystalline medium

BCH 3F.F 10.82% BCH 5F.F 9:02% ECCP 30CF3 4:51% ECCP 50CF3 4:51% CBC-33F 1.80% CBC-53F 1.80% CBC-55F 1.80% PCH-6F 22.07% PCH-7F 5:41% CCP 20CF3 22.07% CCP 30CF3 10.82% CCP 40CF3 31.06% CCP 50CF3 9.92% PCH-5F 9:02% CUZG-2-F 9.80% Clp .: 86.6 @ γ ₁ : 132

Example 10

Containing a liquid-crystalline medium

BCH 3F.F 10.79% BCH SF.F 8.99% ECCP 30CF3 4:50% ECCP 50CF3 4:50% CBC-33F 1.80% CBC-53F 1.80% CBC-55F 1.80% PCH-6F 19.07% PCH-7F 5:40% CCP 20CF3 19.07% CCP 30CF3 10.79% CCP 40CF3 29.06% CCP 50CF3 9.89% PCH-5F 8.99% CUZG-2-F 08.10% Clp .: 86.7 @ Δn: 0.0966 @ Δε: +6.4

Example 11

Containing a liquid-crystalline medium

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% CUZG-3-F 8.00% Clp .: 73.0 @ Δn: 0.0924

Example 12

Containing a liquid-crystalline medium

PCH-5F 21.03% CCP-20CF ₂ .FF 07.17% CCP-30CF ₂ .FF 16.03% CCP-50CF ₂ .FF 07.17% CUP 2F.F 5:37% CUP 3F.F 5:37% CBC-33F 5:37% CBC-53F 5:37% CBC-55F 29.05% CUZG-3-F 19.87% Δs: +10.8

Example 13

Containing a liquid-crystalline medium

BCH 3F.F 10.81% BGH SF.F 9:02% ECCP 30CF3 4:51% ECCP 50CF3 4:51% CBC-33F 1.80% CBC-53F 1.80% CBC-55F 1.80% PCH-6F 21.07% PCH-7F 5:41% CCP 20CF3 21.07% CCP 30CF3 10.81% CCP 40GF3 31.06% CCP 50CF3 9.91% PCH-5F 9:01% CUZG-3-F 9.88% Clp .: 89.2 @ γ ₁ : 135

Claims (10)

1. Liquid-crystalline medium based on a mixture of polar compounds having positive dielectric anisotropy, characterized in that it contains one or more compounds of the formula I.
wherein R is an alkyl, alkoxy or alkenyl group having 1 to 12 C atoms, wherein also one or two non-adjacent CH ₂ groups by -O-, -CH = CH-, -CO-, -OCO- or -COO - may be replaced so that O atoms are not directly linked together means. 2. Medium according to claim 1, characterized in that it additionally contains one or more compounds selected from the group consisting of the general formulas II, III, IV, V, VI and VII:
wherein the individual radicals have the following meanings
R ⁰ n-alkyl, alkoxy, fluoroalkyl or alkenyl, each having up to 7 C atoms,
Z ¹ CF ₂ O, C ₂ F ₄ or a single bond,
Z ² CF ₂ O, C ₂ F ₄ or C ₂ H ₄ ,
X ⁰ F, Cl, halogenated alkyl, alkenyl or alkoxy having 1 to 6 C atoms,
Y ¹ and Y ^{2 are} each independently H or F, and
r 0 or 1. 3. Medium according to claim 1 or 2, characterized in that it additionally contains one or more compounds selected from the following group:
wherein R ⁰ , X ⁰ , Y ¹ and Y ^{2 have} the meaning given in claim 2. 4. Medium according to claim 1 to 3, characterized in that it additionally contains one or more compounds selected from the following group:
wherein R ⁰ , X ⁰ , Y ¹ , Y ² and r have the meaning given in claim 2, L ¹ and L ^{2 are} each independently H or F, and X has one of the meanings given for X ⁰ or CN. 5. Medium according to claim 1 to 4, characterized in that it additionally contains one or more compounds selected from the following group:
wherein R ¹ and R ^{2 are} each independently alkyl or alkoxy having 1 to 8 carbon atoms or alkenyl having 2 to 7 carbon atoms and LH or F. 6. Medium according to claim 1 to 5, characterized in that the Proportion of compounds of the formula I in the total mixture 2 to 55 wt .-% is.   7. Medium according to claim 2 to 6, characterized in that the Proportion of compounds of the formulas I to VII together in Total mixture is at least 50 wt .-%. 8. Medium according to claim 2 to 7, characterized in that the Proportion of compounds of the formulas II to VII, and XIX to XXIV in Total mixture is 30 to 95 wt .-%. 9. Use of the liquid-crystalline medium according to claim 1 to 8 for electro-optical purposes. 10. Electro-optical liquid crystal display containing a liquid crystal Lines Medium according to claim 1 to 8.