KR101572257B1 - Liquid crystalline medium - Google Patents

Abstract

The present invention relates to a liquid crystal medium comprising a compound of the formula (1) and to a liquid crystal display comprising said medium, in particular to twisted nematic (TN) and very twisted nematic (STN)

Description

Liquid crystal medium {LIQUID CRYSTALLINE MEDIUM}

The present invention relates to a liquid crystal medium and a liquid crystal display comprising the medium, and more particularly to twisted nematic (TN) and very twisted nematic (STN) liquid crystal displays with very short response times and good tilt and angular dependence.

TN displays are described, for example, in M. M. Schadt and W. Helfrich, Appl. Phys. Lett., 18, 127 (1971). STN displays are described, for example, in EP 0 131 216 B1; DE 34 23 993 A1; EP 0 098 070 A2; [M. Schadt and F. Leenhouts, 17th Freiburg Congress on Liquid Crystals (8.-10.04.87); See K. Kawasaki et al., SID 87 Digest 391 (20.6)]; [M. Schadt and F. Leenhouts SID 87 Digest 372 (20.1)]; See K. Katoh et al., Japanese Journal of Applied Physics, Vol. 26, No. 11, L1784-L1786 (1987); F. Leenhous et al., Appl. Phys. Lett. 50 (21), 1468 (1987); H.A. van Sprang and H.G. Koopman, J. Appl. Phys. 62 (5), 1734 (1987)); T.J. Scheffer and J. Nehring, Appl. Phys. Lett. 45 (10), 1021 (1984); Schadt and F. Leenhouts, Appl. Phys. Lett. 50 (5), 236 (1987) and E.P. Rayness, Mol. Cryst. Liq. Cryst. Letters Vol. 4 (1), pp. 1-8 (1986). Here, the term STN refers to any comparatively highly twisted display having a twist angle of 160 to 360 degrees, for example a display device according to Waters et al. (CM Waters et al., Proc. Sco. Inf. Disp LCD (DE-A 35 03 259), SBE-LCD (TJ Scheffer and J. Nehring, Appl. Phys (1985) (3rd International Display Conference, Kobe, Japan) 50 (1987), 236), DST-LCD (EP-A 0 246 842 < RTI ID = 0.0 > ) Or BW-STN-LCD (K. Kawasaki et al., SID 87 Digest 391 (20.6)).

STN displays are characterized by an electro-optic characteristic line and a significantly better slope, better contrast value, and significantly lower angle dependence of the contrast relative to a standard TN display.

Of particular interest are TN and STN displays, especially at relatively low temperatures, with very short response times. In order to achieve a short response time, up to now, the rotational viscosity of the liquid crystal mixture has been optimized primarily using monotropical additives with relatively high vapor pressures. However, the response time achieved is not suitable for all applications.

In order to achieve a steep electro-optic characteristic line in the display according to the invention, the liquid crystal mixture should have a value of the ratio K ₃₃ / K ₁₁ between relatively large elastic moduli and a small value of Δ∈ / ε _⊥ , and anisotropic, ε _⊥ is the perpendicular dielectric constant of the longitudinal molecular axes.

In addition to optimizing the contrast and response time, additional important requirements for mixtures of this type are as follows:

1. Wide d / p window

2. High long-term chemical stability

3. High electrical resistance

4. Low frequency and temperature dependence of threshold voltage

The achieved parameter combinations are particularly suitable for medium and low multiplex STN displays (about 1/64 and 1/16 range, respectively), as well as a high multiplex STN display (having a multiple transmission rate in the range of about 1/400) ) And TN display are still not suitable at all. This may be due, in part, to the fact that the various requirements are influenced in the opposite way by the material parameters.

Thus, TN and STN displays with very short response times, high feature line slopes, good angular dependence of contrast and low threshold voltages, and in particular medium and low multiplex STN displays with a large operating temperature range meeting the above mentioned requirements And it is continuously demanded greatly.

Furthermore, modern applications such as telecommunications require liquid crystal mixtures with high values of dielectric anisotropy DELTA epsilon in order to achieve the requisite low threshold voltages. However, the reduced threshold voltage often leads to an increase in response time.

Therefore, there is a need to provide a liquid crystal mixture having a high positive value of [epsilon] and simultaneously a fast response time.

The present invention relates in particular to TN and STN displays with novel compounds having a high amount of DELTA epsilon, a low threshold voltage, in particular a short response time at low temperatures, and a very good slope, which do not have the above mentioned disadvantages, Medium < / RTI >

It has now been found that this object can be achieved with the liquid crystal medium according to the invention.

The present invention relates to a liquid crystal medium comprising a compound of formula

Formula 1

The results of using the compound of formula 1 in the mixture for TN and STN displays according to the present invention

The slope of the higher electro-optic characteristic lines,

The lower temperature dependence of the operating voltage due to improved frequency dependence,

· Faster response time, especially at low temperatures

Is generated.

The compound of formula (I) increases the dielectric anisotropy and tilt and decreases the temperature dependence of the threshold voltage, and significantly shortens the response time of TN and SNT mixtures in particular.

The mixture according to the invention is furthermore characterized by the following advantages:

- the mixture has a low viscosity,

The mixture has a low threshold voltage and an operating voltage,

The mixture achieves a long shelf life of the display at low temperatures.

The present invention is further

Two outer plates forming a cell with the frame;

A nematic liquid crystal mixture having a positive dielectric anisotropy disposed in the cell;

An electrode layer having alignment layers inside the outer plate;

- an angle of inclination between the major axis of the molecule and the outer plate at the surface of the outer plate of 0 to 30 °;

A twist angle from the alignment layer to the alignment layer of the liquid crystal mixture in said cell having a value of 22.5 to 600 °; And

a) from 15 to 75% by weight of a liquid crystal component A consisting of one or more compounds having a dielectric anisotropy of more than +1.5;

b) 25 to 85% by weight of a liquid crystal component B consisting of one or more compounds having a dielectric anisotropy of -1.5 to +1.5;

c) 0 to 20% by weight of a liquid crystal component D consisting of one or more compounds having a dielectric anisotropy of less than -1.5; And

d) optionally a quantity of optically active component C (such that the ratio between the layer thickness (isolation distance of the outer plates) and the intrinsic pitch of the chiral nematic liquid crystal mixture is about 0.2 to 1.3

Lt; RTI ID = 0.0 >

Characterized in that the nematic liquid crystal mixture is defined as described above and below.

The present invention also relates to TN and STN displays, in particular medium and low multiplex STN displays, containing a liquid crystal mixture according to the invention.

The use of the compounds of formula 1 in the liquid crystal mixtures according to the invention results in TN and STN displays with particularly low rotational viscosity values and high slope and particularly fast response times at low temperatures.

The liquid crystal mixture according to the present invention further comprises, in addition to the compound of formula (1), preferably one or more alkenyl compounds of the formula (2)

In this formula,

A is 1,4-phenylene or trans-1,4-cyclohexylene;

a is 0 or 1;

R ³ is an alkenyl group having 2 to 9 carbon atoms;

R ⁴ is an alkyl group of 1 to 12 carbon atoms which is unsubstituted or mono-substituted by CN or CF ₃ or at least monosubstituted by halogen, wherein one or more CH ₂ groups may also be each independently of the other, -O-, -S-, -CH = CH-, -C≡C-, -CO-, -CO-O-, -O-CO- or -O-CO-O- .

Particularly preferred compounds of formula (2) are those selected from the following formulas (2a) to (2i):

In this formula,

R ^3a and R ^4a independently of one another are H, CH ₃ , C ₂ H ₅ or nC ₃ H ₇ ;

Alkyl is an alkyl group having 1 to 8 carbon atoms.

Especially preferred are compounds of formula (2a) wherein R ^3a and R ^4a are H or CH ₃ , especially compounds of formula (2e), (2f, 2g, 2h and 2i) wherein R ^3a is H or CH ₃ .

The compounds of formulas (1) and (2) having a dielectric anisotropy of -1.5 to +1.5 ("genetically neutral") are part of component B as defined above.

The liquid crystal mixture according to the present invention further comprises, in addition to the compounds of formulas (1) and (2), one or more alkenyl compounds having preferably a positive dielectric anisotropy:

In this formula,

R ³ is an alkenyl group having 2 to 7 carbon atoms;

Q is _{CF 2, OCF 2, CFH,} OCFH or a single bond;

Y is F or Cl;

L ¹ and L ² are independently of each other H or F;

Particularly preferred are compounds of formula 200, wherein L ¹ and / or L ² is F and QY is F or OCF ₃ .

More preferred are compounds of formula 200, wherein R < ³ > is 1E-alkenyl or 3E-alkenyl having 2 to 7, preferably 2,

Very preferred are compounds of formula (200a)

In this formula,

R ^3a is H, CH ₃ , C ₂ H ₅ or nC ₃ H ₇ , especially H or CH ₃ .

Polar compounds of formula (200) having a dielectric anisotropy of greater than +1.5 are part of component A as defined above.

Preferred liquid crystal mixtures comprise at least one compound of component A in a ratio of preferably 15 to 75%, more preferably 20 to 65%. The compound preferably has a dielectric anisotropy of??? +3, more preferably ??? +8, and most preferably ??? +12.

Component A preferably comprises at least one cyano compound selected from the following formulas (3a) to (3i):

In this formula,

R is an alkyl, alkoxy or alkenyl group having from 1 to 12 carbon atoms, in which one or more CH ₂ groups may also independently of one another be replaced by -O-, -CH = CH-, - CO-, -O-CO- or -CO-O-;

L ¹ , L ² , L ³ and L ⁴ independently of one another are H or F.

In these compounds, R is preferably alkyl or alkoxy having 1 to 8 carbon atoms or alkenyl having 2 to 7 carbon atoms.

In particular, L mixture containing the ^first and / or L ² is F, one or more compounds selected from the formula 3b, 3c, 3d and 3e, 3g are also more highly preferred.

R is an alkenyl having 2 to 7 carbon atoms, preferably -alkenyl or 3E-alkenyl, more preferably vinyl, 1E-propenyl, 1E-butenyl, 3E-butenyl or 3E- More preferred are mixtures comprising at least one compound of formula 3c and / or 3d which is 1E-butenyl.

More preferred are mixtures comprising at least one compound of formula ( ^{III) wherein} L < ³ > and L < ⁴ >

A preferred liquid crystal mixture comprises preferably at least 25 to 85% of at least one compound of component B. The compounds of group B are particularly characterized by a low rotational viscosity gamma 1 value.

Component B preferably further comprises at least one compound selected from the group consisting of bicyclic compounds of the following formulas 41 to 49:

And / or tricyclic compounds of the following formulas (410) to (426):

And / or tetracyclic compounds of the formulas (427) to (433), wherein the 1,4-phenylene group in the formulas (410) to (419) and (423 to 433) Substituted:

In this formula,

R ¹ and R ² are independently of each other an alkyl group of 1 to 12 carbon atoms which is unsubstituted or mono-substituted by CN or CF ₃ or at least monosubstituted by halogen, wherein one or more CH ₂ groups are also each independently of the other O -CO-, -O-CO- or -O-CO-, -CO-O-, -O-CO-, -O- -O-; < / RTI >

L is H or F.

Particularly preferred are those compounds of formulas 427 to 433, wherein R ¹ is alkyl and R ² is alkyl or alkoxy, especially alkoxy, each having 1 to 7 carbon atoms. Even more preferred are the compounds of formulas 427 and 433 wherein L is F.

Compounds of formulas 412, 427 and 432 are particularly preferred.

In the compounds of formulas 41 to 433, R ¹ and R ² are particularly preferably straight chain alkyl or alkoxy of 1 to 12 carbon atoms.

Particular preference is given to mixtures according to the invention, preferably comprising at least one compound selected from the group consisting of formula (424) wherein R < ¹ > is an alkenyl of 2 to 7 carbon atoms and very preferably the following formulas (424a) and (424b).

In this formula,

R ^3a is as defined above.

In a more preferred embodiment, the liquid crystal mixture comprises at least one tolan compound selected from the group consisting of the following chemical formulas Ta to Ti:

In this formula,

R ¹ and R ² are as defined in Formula 4 above;

Z ⁴ is -CO-O-, -CH ₂ CH ₂ - or a single bond;

L ¹ to L ⁶ independently of one another are H or F;

Especially preferred are compounds of the formula Ta, Tb and Tc.

In a further preferred embodiment, component A of the liquid crystal mixture according to the invention is preferably at least one 3,4,5-trifluorophenyl compound selected from the following formulas (5a) to (5s):

And / or at least one compound having a polar end group selected from the following formulas (6a) to (6u): < EMI ID =

In this formula,

R is as defined in formula (3);

L ³ and L ⁴ are independently of each other H or F;

Preferably, in the above compound, R is alkyl or alkoxy having 1 to 8 carbon atoms.

Particularly preferred are the compounds of formulas 5a, 5b, 5c, 5d, 5m, 5n and 6m, especially the compounds of formulas 5a, 5m, 5n and 6m.

In a further preferred embodiment, the liquid crystal mixture comprises one or more, particularly preferably 1, 2 or 3, heterocyclic compounds of the following general formulas (7a) and / or (7b)

In this formula,

R < ⁶ > and R < ⁷ > are defined as R in formula (3);

Y is F or Cl.

Optionally, the liquid crystal mixture comprises an optically active component C in an amount such that the ratio of the layer thickness (isolation distance between outer plates) to the intrinsic pitch of the chiral nematic liquid crystal mixture is greater than 0.2. One of skill in the art will be able to obtain a number of chiral dopants (some of which are commercially available) for these components, such as cholesteryl nonanoate, S-811, S-1011, S-2011, S-3011, S-4011 or CB15 from Merck KGaA (Darmstadt, Germany). The choice of the dopant is not important in itself.

The proportion of the component C compound is preferably 0 to 10%, more preferably 0 to 5%, particularly 0 to 3%.

The mixtures according to the invention also comprise up to 20% of at least one compound (component D), optionally with a dielectric anisotropy of less than -2.

Where the mixture comprises a compound of component D, it is preferably one or more compounds containing 2,3-difluoro-1,4-phenylene structural units, for example DE-A 38 07 801, 38 07 861, 38 07 863, 38 07 864 and 38 07 908. Particular preference is given to tolans containing such structural units, as disclosed in International Patent Application Publication WO 88/07514.

를 함유하는 2,3-다이시아노하이드로퀴논의 유도체 또는 사이클로헥산 유도체이다.Further known compounds of component D are, for example, those described in DE-A 32 31 707 and DE-A 34 07 013,

Or a cyclohexane derivative containing 2,3-dicyanohydroquinone.

The liquid crystal display according to the present invention preferably does not contain the compound of component D.

The term "alkenyl" in the definition of R and R ¹ to R ⁷ includes straight and branched alkenyl groups, especially straight chain groups. Particularly preferred alkenyl groups are C ₂ -C ₇ -1E-alkenyl, C ₄ -C ₇ -3 E-alkenyl, C ₅ -C ₇ -4-alkenyl, C ₆ -C ₇ -5 -alkenyl and C ₇ -alkenyl, especially C ₂ -C ₇ -1E-alkenyl, C ₄ -C ₇ -3 E-alkenyl and C ₅ -C ₇ -4-alkenyl.

Examples of preferred alkenyl groups are vinyl, 1E-propenyl, 1E-butenyl, 1E-pentenyl, 1E-hexenyl, 1E-heptenyl, 3E-butenyl, 3E-pentenyl, 3E- Heptenyl, 4-pentenyl, 4Z-hexenyl, 4E-hexenyl, 4Z-heptenyl, 5-hexenyl, 6-heptenyl and the like. Groups having up to 5 carbon atoms are generally preferred.

In a particularly preferred embodiment, the liquid crystal mixture comprises

At least one compound selected from the compounds of formulas (2a) to (2i) and / or (200);

At least one compound selected from the following formulas (3a) to (3i);

One or more compounds of formula (424);

At least one compound selected from the formulas Ta to Tc;

- at least one compound selected from the compounds of formulas 412 and / or 427 and / or 432

.

In another particularly preferred embodiment, the liquid crystal mixture comprises

2 to 30%, preferably 4 to 20% of a compound of formula (I);

0 to 30%, preferably 3 to 20% of a compound of formula (424);

From 8 to 70%, preferably from 14 to 60% of compounds of formulas (2a) to (2i) and / or (200);

From 4 to 50%, preferably from 5 to 40%, of a compound of the formula Ta to Tc;

5 to 40%, preferably 10 to 30% of compounds of formulas 3a to 3i;

0 to 20%, preferably 2 to 10% of the compound of formula 412 and / or 427 and / or 432

.

The individual compounds of the above-mentioned individual formulas and sub-formulas thereof, and the compounds according to the invention or further compounds which can be used in TN and STN displays are known or can be prepared analogously to the known compounds.

The mixtures according to the invention are characterized by a very low overall response time (t _sum = t _on + t _off ), especially when used in TN and STN displays with large layer thicknesses.

The liquid crystal mixture used in the TN and STN cells according to the present invention is preferably genetically positive and has a? A liquid crystal mixture having?? 5 is preferable.

The transparent point of the liquid crystal mixture according to the present invention is preferably 80 DEG C or higher, more preferably 90 DEG C or higher.

A liquid crystal composition according to the invention have advantageous values for the threshold voltage V _10/0/20 and the rotational viscosity γ1. If a value for the optical path difference d · Δn is predetermined, the value for the layer thickness d is determined by the optical anisotropy Δn. The use of a liquid crystal mixture according to the invention having a relatively high optical anisotropy value, in particular at a relatively high d A n value, is generally preferred, since a relatively small value of d can be chosen to produce a more favorable response time value It is because. However, the liquid crystal display according to the present invention containing a liquid crystal mixture according to the present invention having a smaller value of? N is also characterized by favorable response time values.

Preferably, the liquid crystal mixture according to the invention has a birefringence? N of > 0.12, very preferably? 0.14. More preferably, the liquid crystal mixture according to the present invention has a birefringence? N of < 0.25, very preferably? 0.22.

The liquid crystal mixture according to the present invention is further characterized by the advantageous slope of the electro-optic characteristic line, and can operate at a high multiplex transmission rate, especially at temperatures exceeding 20 占 폚. Further, the liquid crystal mixture according to the present invention has a high stability and an advantageous electric resistance value and a frequency dependency of the threshold voltage. The liquid crystal display according to the present invention has a large operating temperature range and a good angle dependence of contrast.

Polarizer and electrode plate according to the present invention from the electrode base plate so that the preferential alignment (leader) of adjacent liquid crystal molecules in each case is usually twisted from one electrode to another to a value of 160 to 720 [ The structure of the device corresponds to a structure common to display devices of this type. In the present invention, the term "conventional structure" is broadly drawn to include all derivatives and variants of TN and STN cells, especially display devices containing matrix display elements and additional magnets.

The surface inclination angles at the two outer plates may be the same or different. The same inclination angle is preferable. Preferred TN displays have a pre-tilt angle between the major axis of the molecules at the outer plate surface and the outer plate, from 0 to 7, preferably from 0.01 to 5, especially from 0.1 to 2. In the STN display, the preliminary tilt angle is 1 to 30, preferably 1 to 12, especially 3 to 10.

The twist angle of the TN mixture in the cell has a value of 22.5 to 170 DEG, preferably 45 to 130 DEG, particularly 80 to 115 DEG. The twist angle from the alignment layer of the STN mixture in the cell to the alignment layer has a value of 100 to 600 °, preferably 170 to 300 °, particularly 180 to 270 °.

The liquid crystal mixture according to the present invention is useful as a liquid crystal display in cholesteric liquid crystal displays, in particular SSCT ("surface stabilized ") as described in WO 92/19695, U.S. Patents 5,384,067, 5,453,863, 6,172,720 and 5,661,533, Cholesteric texture ") and PSCT (" polymer stabilized cholesteric texture ") displays. A cholesteric liquid crystal display typically includes a cholesteric liquid crystal medium consisting of a nematic component and an optically active component and exhibits significantly higher helical twisting than TN- and STN displays and exhibits selective reflection of circularly polarized light . The reflection wavelength is given by the product of the pitch of the cholesteric helix and the average refractive index of the cholesteric liquid crystal medium.

To this end, one or more chiral dopants are added to the liquid crystal mixture according to the invention, wherein the torsional force and the concentration of the dopant are selected such that the resulting liquid crystal medium has a cholesteric phase at room temperature and preferably a visible spectrum of the electromagnetic spectrum , With a reflection wavelength within the UV or IR range, in particular in the range of 400 to 800 nm.

Suitable chiral dopants are known to those skilled in the art and include, for example, cholesteryl nonanoate (CN), CB15, R / S-811, R / S-1011, R / S- S-4011 and R / S-5011 (Merck KGaa, Darmstadt, Germany). Particularly suitable are dopants of high torsional forces including chiral sugar groups, in particular derivatives of sorbitol, mannitol or iditol, very preferably sorbitol derivatives as disclosed in WO 98/00428. A chondain binaphthyl derivative as disclosed in WO 02/94805, a chiral binaphthol acetal derivative as disclosed in WO 02/34739, a chiral bainaphthol acetal derivative as disclosed in WO 02/06265, More preferred are the same chiral TADDOL derivatives and chiral dopants having at least one fluorinated bond group and a terminal or central chiral group as disclosed in WO 02/06196 and WO 02/06195.

When two or more dopants are used, they may represent the same or opposite torsional sense and the same or opposite indication of the linear temperature coefficient of the torsion.

A cholesteric liquid crystal medium comprising a liquid crystal mixture according to the invention as a nematic component and comprising at least one chiral dopant as an optically active component is a further object of the present invention. Still another object of the present invention is cholesteric liquid crystal displays, particularly SSCT- and PSCT-displays, comprising cholesteric liquid crystal media as described above.

The liquid crystal mixtures which can be used according to the invention are prepared in a manner customary in itself, for example by mixing the compounds of the formula (I) with one or more compounds selected from the above-mentioned formulas, and optionally further compounds or additives. In general, the desired amount of component used in lesser amounts is advantageously dissolved in the constituents of the main constituent at elevated temperatures. It is also possible to mix a solution of the above components in an organic solvent, for example acetone, chloroform or methanol, and to remove the solvent again after thorough mixing, for example by distillation. The method for producing the mixture is a further aspect of the present invention.

The dielectrics may also include further additives known in the art and disclosed in the literature. For example, 0 to 15% of a pleochroic dye, nanoparticle, stabilizer or chiral dopant may be added. Suitable dopants and stabilizers are shown in Tables 3 and 4 below.

In the present invention and the following examples, the structure of the liquid crystal compound is expressed acronymically and the conversion into the formula takes place according to Tables 1 and 2. All radicals C _n H _{2n + 1} and C _m H _{2m + 1} are straight-chain alkyl radicals having n and m carbon atoms, respectively. The alkenyl radical has a trans form. The symbols in Table 2 are self explanatory. In Table 1, only the acronyms for the parent structure are shown. In the individual case, the acronyms for the parent structure are followed by the signs shown in the following table for substituents R ¹ , R ² , L ¹ , L ² and L ³ , separated by a dash (-).

The TN and STN displays preferably contain a liquid crystal mixture consisting of one or more compounds from Tables 1 and 2.

Table 3 shows the dopants preferably used in the mixtures according to the invention:

For example, stabilizers which can be added to the mixture according to the invention are shown below:

It will be appreciated that variations on the above embodiments of the invention may still be practiced within the scope of the invention. May be replaced by other features that serve the same, equivalent, or similar purpose, unless the respective features disclosed herein are represented differently. Accordingly, unless otherwise indicated, each feature disclosed is but one example of a comprehensive set of equivalent or similar features.

All of the features disclosed herein may be combined in any combination, provided that at least some of the features and / or steps above are mutually exclusive. In particular, the preferred features of the present invention are applicable to all aspects of the invention and may be used in any combination. Likewise, features disclosed in non-essential combinations can be used separately (without combining).

It will be appreciated that many of the features, particularly particularly preferred embodiments, of the above-described features are, of course, inventive and are not merely part of the embodiments of the invention. May pursue protection independent of or in addition to any of the presently claimed inventions as an alternative thereto.

The following abbreviations are used:

Clp. Transparent point (nematic-isotropic phase transition temperature),

S-N Smectic-Nematic Phase Transition Temperature,

? N optical anisotropy (589 nm, 20 ° C),

Δε dielectric anisotropy (1 kHz, 20 ° C),

僚_{T The} flow viscosity (㎟ · s ^-1 at T / ° C),

? ₁ rotational viscosity (mPa 占 퐏 at 20 占 폚),?

k ₁ Elastic constant ("splay", pN at 20 ° C),

k "elastic constant (" twist ", pN at 20 DEG C)

k ₃ Elastic constant ("bend", pN at 20 ° C),

S characteristic line slope = (1 - V ₉₀ / V ₁₀ ) * 100

d cell spacing (탆),

P cholesteric pitch (占 퐉, at 20 占 폚),

The helical twisting force (탆, at 20 캜) of HTP S-811,

V ₁₀ threshold voltage = 10% characteristic contrast at relative contrast,

V ₅₀ Mid-gray voltage = 50% characteristic voltage at relative contrast,

The characteristic voltage at a relative contrast of V ₉₀ saturation voltage = 90%

τ _on + τ _off at τ response time V (τ _on = τ _off )

τ _on Rise time from 0% to 90% relative contrast,

τ _off decay time from 100% to 10% relative contrast,

M multiplexing ratio, and

B bias ratio.

Above and below, all temperatures are given in degrees Celsius. Percent is weight percent. All values relate to 20 [deg.] C unless otherwise indicated. The display has a twist of 240 degrees and is addressed with a multiplex transmission ratio of 1/64 and a bias of 1/7, unless otherwise indicated. The optical delay is 0.85 mu m and the d / P ratio is 0.52 unless otherwise indicated.

The present invention will now be described in more detail with reference to the following examples, which are for illustrative purposes only and do not limit the scope of the invention.

The liquid crystal mixtures provided in the following examples are prepared and investigated as such. STN displays are then prepared and examined, each containing one of these liquid crystal mixtures. The respective compositions and corresponding results are shown below.

Example 1

Example 2

Example 3

Example 4

Example 5

Example 6

Example 7

Example 8

Example 9

Example 10

Example 11

Example 12

Example 13

Example 14

Example 15

Example 16

Example 17

Example 18

Example 19

Example 20

Example 21

Example 22

Example 23

Example 24

Example 25

Example 26

Example 27

Example 28

Example 29

Example 30

Example 31

Example 32

Example 33

Example 34

Claims (12)

A compound of formula

One; At least one compound of formula 2:

2 [In the above formula, A is 1,4-phenylene or trans-1,4-cyclohexylene; a is 0 or 1; R ³ is an alkenyl group having 2 to 9 carbon atoms; R ⁴ is an alkyl group of 1 to 12 carbon atoms which is unsubstituted or mono-substituted by CN or CF ₃ or at least monosubstituted by halogen, wherein one or more CH ₂ groups may also be each independently of the other, -O-, -S-, -CH = CH-, -C≡C-, -CO-, -CO-O-, -O-CO- or -O-CO-O- ]; And At least one compound selected from the following formulas (3a) to (3i):

[In the above formula, R is an alkyl, alkoxy or alkenyl group having from 1 to 12 carbon atoms, in which one or more CH ₂ groups may also independently of one another be replaced by -O-, -CH = CH-, - CO-, -O-CO- or -CO-O-; L ¹ , L ² , L ³ and L ⁴ independently of one another are H or F; And a liquid crystal layer. The method according to claim 1, A liquid crystal medium characterized in that it further comprises at least one compound selected from the following formulas (424a) and (424b):

In this formula, R ^3a is H, CH ₃ , C ₂ H ₅ or nC ₃ H ₇ ; Alkyl is an alkyl group having 1 to 8 carbon atoms. delete delete The method according to claim 1, A liquid crystal medium characterized in that it further comprises at least one compound selected from the following formulas (Ta) to Tc:

In this formula, R ¹ and R ² are independently of each other an alkyl group of 1 to 12 carbon atoms which is unsubstituted or mono-substituted by CN or CF ₃ or at least monosubstituted by halogen, wherein one or more CH ₂ groups are also each independently of the other O -CO-, -O-CO- or -O-CO-, -CO-O-, -O-CO-, -O- -O-. &Lt; / RTI &gt; The method according to claim 1, A liquid crystal medium characterized in that it further comprises at least one compound selected from the following formulas (412), (427) and (432)

In this formula, R ¹ and R ² are independently of each other an alkyl group of 1 to 12 carbon atoms which is unsubstituted or mono-substituted by CN or CF ₃ or at least monosubstituted by halogen, wherein one or more CH ₂ groups are also each independently of the other O -CO-, -O-CO- or -O-CO-, -CO-O-, -O-CO-, -O- -O-; &lt; / RTI &gt; L is H or F. The method according to claim 1, 2 to 30% of a compound of the formula 1:

One; 0 to 30% of a compound of the formulas 424a and / or 424b:

[In the above formula, R ^3a is H, CH ₃ , C ₂ H ₅ or nC ₃ H ₇ ; Alkyl is an alkyl group having 1 to 8 carbon atoms; From 8 to 70% of compounds of the formulas (2a) to (2i) and / or (200)

200 [In the above formula, R ^3a and R ^4a independently of one another are H, CH ₃ , C ₂ H ₅ or nC ₃ H ₇ ; Alkyl is an alkyl group having 1 to 8 carbon atoms; R ³ is an alkenyl group having 2 to 7 carbon atoms; Q is _{CF 2, OCF 2, CFH,} OCFH or a single bond; Y is F or Cl; L ¹ and L ² independently of one another are H or F; From 4 to 50% of compounds of the formulas Ta to Tc:

[In the above formula, R ¹ and R ² are independently of each other an alkyl group of 1 to 12 carbon atoms which is unsubstituted or mono-substituted by CN or CF ₃ or at least monosubstituted by halogen, wherein one or more CH ₂ groups are also each independently of the other O -CO-, -O-CO-, or -O-CO-, -CO-O-, -O-CO-, -O- -O-; &lt; / RTI &gt; 5 to 40% of compounds of the formulas (3a) to (3i):

[In the above formula, R is an alkyl, alkoxy or alkenyl group having from 1 to 12 carbon atoms, in which one or more CH ₂ groups may also independently of one another be replaced by -O-, -CH = CH-, - CO-, -O-CO- or -CO-O-; L ¹ , L ² , L ³ and L ⁴ independently of one another are H or F; And 0 to 20% of a compound of the following formula 412 and / or 427 and / or 432:

[In the above formula, R ¹ and R ² are independently of each other an alkyl group of 1 to 12 carbon atoms which is unsubstituted or mono-substituted by CN or CF ₃ or at least monosubstituted by halogen, wherein one or more CH ₂ groups are also each independently of the other O -CO-, -O-CO- or -O-CO-, -CO-O-, -O-CO-, -O- -O-; &lt; / RTI &gt; L is H or F; And a liquid crystal layer. A method for using a liquid crystal medium according to any one of claims 1, 2 and 5 to 7 for electro-optic purposes. An electro-optical liquid crystal display comprising a liquid crystal medium according to any one of claims 1, 2 and 5 to 7. Two outer plates forming a cell with the frame; A nematic liquid crystal mixture having a positive dielectric anisotropy disposed in the cell; An electrode layer having an alignment layer inside the outer plate; An angle of inclination between the long axis of the molecule and the outer plate at the outer plate surface of 0 to 30 °; A twist angle from the alignment layer to the alignment layer of the liquid crystal mixture in the cell having a value of 22.5 to 600 °; And a) from 15 to 75% by weight of liquid crystal component A consisting of at least one compound having a dielectric anisotropy greater than +1.5; b) 25 to 85% by weight of a liquid crystal component B consisting of at least one compound having a dielectric anisotropy of -1.5 to +1.5; c) 0 to 20% by weight of a liquid crystal component D consisting of at least one compound having a dielectric anisotropy of less than -1.5; And d) optionally an optically active component C in an amount such that the ratio between the layer thickness (isolation distance of the outer plates) and the intrinsic pitch of the chiral nematic liquid crystal mixture is between 0.2 and 1.3, And a nematic liquid crystal mixture characterized by being a medium according to any one of claims 5-7. A TN (twisted nematic) liquid crystal display. delete Two outer plates forming a cell with the frame; A nematic liquid crystal mixture having a positive dielectric anisotropy disposed in the cell; An electrode layer having alignment layers inside the outer plate; An angle of inclination between the long axis of the molecule and the outer plate at the outer plate surface of 0 to 30 °; A twist angle from the alignment layer to the alignment layer of the liquid crystal mixture in the cell having a value of 22.5 to 600 °; And a) from 15 to 75% by weight of a liquid crystal component A consisting of at least one compound having a dielectric anisotropy greater than +1.5; b) 25 to 85% by weight of liquid crystal component B consisting of one or more compounds having dielectric anisotropy of -1.5 to +1.5; c) 0 to 20% by weight of liquid crystal component D consisting of one or more compounds having dielectric anisotropy of less than -1.5; And d) optionally an optically active component C in an amount such that the ratio between the layer thickness (isolation distance of the outer plates) and the intrinsic pitch of the chiral nematic liquid crystal mixture is between 0.2 and 1.3, And a liquid crystal medium according to any one of claims 5 to 7, characterized in that the nematic liquid crystal mixture STN (very wobbly nematic) liquid crystal display.