JP2008144167A - Liquid crystal medium and liquid crystal display - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an excellent liquid crystal medium related to a liquid crystal medium, a liquid crystal display equipped with the liquid crystal medium, particularly a display addressed to the time sequential multiplexing, and the super twisted nematic (STN) display. <P>SOLUTION: The invention relates to a liquid crystal medium comprising a component A that is a first dielectrically positive component including one or more kinds of compounds having, for example, a benzene ring and a cyclohexane ring in a molecule, and a component B that is a second dielectrically positive component including one or more kinds of compounds having, for example, a benzene ring, a cyclohexane ring and an oxygen-containing hetero-ring in the molecule. Further, the invention relates to a liquid crystal display using these media, particularly TN and STN displays and particularly STN display. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to liquid crystal media and liquid crystal displays comprising these liquid crystal media, in particular to displays addressed by time sequential multiplexing and in particular to Super Twisted Nematic (STN) type displays.

  A liquid crystal display (LCD) is widely used for displaying information. The electro-optic modes used are, for example, twisted nematic (TN) mode, super twisted nematic (STN) mode, optically compensated bend (OCB) mode, and electrically controlled birefringence EC (B). Controlled Birefringence) modes and their various variations and other methods. All of these modes use an electric field that is substantially perpendicular to the substrate and the liquid crystal layer, respectively. In addition to these modes, an electro-optic mode that uses an electric field substantially parallel to the substrate and the liquid crystal layer, respectively. For example, there is an in-plane switching mode (for example, disclosed in German Patent No. 4000451 (Patent Document 1) and European Patent No. 0588568 (Patent Document 2)). . In particular, this electro-optic mode is used in the latest LCDs for desktop monitors, and is being applied to displays for multimedia applications.

  TN and STN displays are widely used, for example, for mobile phones and games. Some of their greatest advantages are low manufacturing costs, relatively low operating voltage requirements, and relatively low power consumption. The liquid crystals of the present invention are preferably used in this type of display.

  For these displays, there is a need for new liquid crystal media with improved properties. In particular, the dielectric anisotropy (Δε) should be high enough to allow a reasonably low operating voltage. Preferably, Δε should be greater than 30, very preferably greater than 45, but is preferably 80 or less, especially 70 or less. Otherwise, the resistivity of the mixture tends to be so low that it is unacceptable even for most STN displays that do not strictly require this point than displays addressed by electrically active elements (AM LCD or AMD). In addition to this parameter, the medium has a reasonably wide range of the nematic phase, the correct range of birefringence (Δn) for the electro-optic effect to exhibit sufficient performance, a somewhat low rotational viscosity and, as mentioned above, at least well Must exhibit a high resistivity.

  The display of the present invention is preferably addressed by time sequential multiplexing, such as, for example, the Orthogonal Waveforms proposed by Alt and Pleshko, but is particularly used in high-speed switch displays It is also addressed by a so-called active addressing. However, the liquid crystals of the present invention can also be beneficially used in displays with other known addressing means.

  Various different display modes using a low molecular weight liquid crystal material together with a polymer material as a composite system, such as a polymer dispersed liquid crystal (PDLC) disclosed in WO 91/05029 (Patent Document 3). ) System, Nematic Curvilinearly Aligned Phase (NCAP) system and Polymer Network (PN) system, or Axially Symmetric Microdomain (ASM) system and others. In contrast, a particularly preferred mode for the present invention is to use the liquid crystal medium as it is, with the liquid crystal medium aligned on the surface. These surfaces are typically pretreated to achieve uniform alignment of the liquid crystal material. The display mode according to the present invention preferably uses an electric field substantially perpendicular to the liquid crystal layer.

  LCDs are used not only for projection displays but also for direct view displays.

A liquid crystal composition suitable for an LCD, particularly an STN display, is known, for example, from US Pat. No. 6,730,372 (Patent Document 4). These compositions, however, have significant drawbacks. Most of these compositions require operating voltages that are too low and / or too high, among other disadvantages. Many of them also have inconveniently long response times.
German Patent No. 4000451 European Patent No. 0588568 International Publication No. 91/05029 Pamphlet US Pat. No. 6,730,372

  Therefore, there is a clear need for liquid crystal media having properties suitable for practical applications, such as a wide nematic phase range, low viscosity, suitable optical anisotropy Δn depending on the display mode used, and particularly high Δε. ing.

  Surprisingly, it is possible to realize a liquid crystal medium having a reasonably high Δε, a suitable phase range and Δn, which does not show the disadvantages of the prior art materials, or at least to a lesser extent. I found it.

These improved liquid crystal media of the present application include at least the following components.
Component A which is a first dielectrically positive component comprising one or more compounds of formula I and one or more compounds selected from the group of formulas II and III.

式中、
Ｒ^１、Ｒ^２およびＲ^３は、それぞれ互いに独立に、炭素数１〜７のアルキル、アルコキシ、フッ素化されたアルキルまはたフッ素化されたアルコキシ、炭素数２〜７のアルケニル、アルケニルオキシ、アルコキシアルキルまたはフッ素化されたアルケニルであり、好ましくはＲ^１はアルケニルであり、および
ｍは、０または１である。

Where
R ¹ , R ² and R ³ are each independently of each other alkyl, alkoxy having 1 to 7 carbon atoms, alkoxy, fluorinated alkyl or fluorinated alkoxy, alkenyl having 2 to 7 carbon atoms, alkenyloxy, Alkoxyalkyl or fluorinated alkenyl, preferably R ¹ is alkenyl, and m is 0 or 1.

  A component B which is a second dielectrically positive component comprising one or more compounds of the formula IV.

式中、
Ｒ^４は、式ＩＩでＲ^２に与えられる意味を有し、
Ｚ^４は、−ＣＯ−Ｏ−または単結合であり、

Where
R ⁴ has the meaning given to R ² in formula II;
Z ⁴ is —CO—O— or a single bond,

Ｘ^４は、ＦまたはＯＣＦ_３であり、および
Ｙ^４は、ＨまたはＦである。

X ⁴ is F or OCF ₃ and Y ⁴ is H or F.

  An optional component C, which is a further (third) dielectrically positive component.

  -Component D, which is a dielectrically neutral component as an optional component.

  -Component E, which is a dielectrically negative component as an optional component.

  -Component F which is a chiral component, preferably as an optional component, as an optional component.

  Preferably, the first dielectrically positive component Component A is a dielectrically strong positive compound having a dielectric anisotropy of 20 or more, preferably 30 or more, preferably Formulas I and III, most preferably It comprises one or more compounds of each of formulas I, II and III, more preferably most, even more preferably substantially, most preferably all consisting of them.

  Preferably, the liquid crystal mixture of the present invention comprises one or more compounds of formula III where m is 0 and / or one or more compounds of formula III where m is 1.

  In a preferred embodiment of the present invention, the liquid crystal mixture of the present invention comprises one or more compounds of each of formulas I, II and III.

  Preferably, component B, the second dielectrically positive component, is a dielectrically positive compound having a dielectric anisotropy in the range of 3-19, preferably in the range of 5-16, preferably of formula IV It comprises one or more compounds, more preferably most, even more preferably substantially, most preferably all.

Preferably, the liquid crystal mixture of the present invention comprises one or more compounds of formula IV where X ⁴ is OCF ₃ and Y ⁴ is H.

More preferably, the liquid crystal mixture of the present invention comprises one or more compounds of formula IV where X ⁴ is F and Y ⁴ is F.

  In a preferred embodiment of the invention, the liquid crystal mixture of the invention comprises one or more compounds of formula IV selected from the group of compounds of formulas IVa to IVd.

式中、Ｒ^４は、上で与えられる意味を有する。

In which R ⁴ has the meaning given above.

  In a preferred embodiment of the present invention, the liquid crystal mixture of the present invention comprises one or more compounds of formula IVa.

  In a preferred embodiment of the present invention, the liquid crystal mixture of the present invention comprises one or more compounds of formula IVb and / or one or more compounds selected from the group of compounds of formulas IVc and IVd.

  In a preferred embodiment of the invention, component B, the second dielectrically positive component, preferably comprises one or more of the compounds of formula IV selected from the group of formulas IVa-IVd, more preferably large. The parts more preferably substantially consist of these, most preferably all.

  Preferably, the liquid crystal mixture of the present invention comprises component C which is a further (third) dielectrically positive component. This component has a dielectric anisotropy greater than 3, preferably in the range 3-19, and most preferably 5-15. Component C preferably comprises a dielectrically positive compound, more preferably consists mostly of, more preferably substantially, most preferably all. Preferably, this component preferably comprises one or more of the dielectrically positive compounds of formula V, more preferably most, even more preferably substantially, most preferably all of them.

式中、
Ｒ^５は、前記式ＩＩでＲ^２に与えられる意味を有し、

Where
R ⁵ has the meaning given to R ² in formula II above;

好ましくは、

Preferably,

Ｚ^５１およびＺ^５２は、それぞれ互いに独立に、およびＺ^５１が２回存在している場合は、これらもそれぞれ互いに独立に、−ＣＨ_２ＣＨ_２−、−ＣＯＯ−、トランス−ＣＨ＝ＣＨ−、トランス−ＣＦ＝ＣＦ−、−ＣＨ_２Ｏ−、−ＣＦ_２Ｏ−または単結合であり、好ましくはそれらの少なくとも１つは単結合であり、最も好ましくは、存在して場合、それらの少なくとも２つは単結合であり、
Ｘ^５は、Ｆ、Ｃｌ、ハロゲン化されたアルキル、ハロゲン化されたアルコキシ、ハロゲン化されたアルケニルまたはハロゲン化されたアルケニルオキシであり、ただし、ハロゲン化は好ましくはフッ素化および／または塩素化であり、好ましくはフッ素化であり、好ましくはＸ^５はＦ、ＯＣＦ_３またはＯＣＦ_２Ｈであり、
ｎは、０、１または２、好ましくは１または２であり、および
式ＩＶａ〜ＩＶｄの化合物は除外される。

Z ⁵¹ and Z ⁵² are each independently of each other, and when Z ⁵¹ is present twice, they are each independently of each other, —CH ₂ CH ₂ —, —COO—, trans—CH═CH—, Trans-CF═CF—, —CH ₂ O—, —CF ₂ O— or a single bond, preferably at least one of them is a single bond, most preferably at least two of them, if present. One is a single bond,
X ⁵ is F, Cl, halogenated alkyl, halogenated alkoxy, halogenated alkenyl or halogenated alkenyloxy, provided that the halogenation is preferably fluorinated and / or chlorinated. Yes, preferably fluorinated, preferably X ⁵ is F, OCF ₃ or OCF ₂ H;
n is 0, 1 or 2, preferably 1 or 2, and compounds of formula IVa-IVd are excluded.

  Preferably, the liquid-crystal mixture of the invention contains at least one further component in addition to components A and B. This third component may be any one of components C, D and E. Preferably, the third component present is component C or D, particularly preferably component C.

  Obviously, the mixtures according to the invention can also contain four of these components, preferably components A, B, C and D, and optionally all four of these.

  Preferably, the liquid crystal mixture of the present invention contains component D which is a dielectrically neutral component. This component has a dielectric anisotropy in the range of -1.5 to +3. Component D preferably comprises one or more of a dielectrically neutral compound, more preferably most, even more preferably substantially, most preferably all. Preferably, this component preferably comprises one or more of the dielectrically neutral compounds of formula VI, more preferably most, even more preferably substantially, most preferably all.

式中、
Ｒ^６１およびＲ^６２は、それぞれ互いに独立に、前記式ＩＩでＲ^２に与えられる意味を有し、

Where
R ⁶¹ and R ⁶² each independently of one another have the meaning given to R ² in formula II above;

好ましくは、

Preferably,

Ｚ^６１およびＺ^６２は、それぞれ互いに独立に、およびＺ^６１が２回存在している場合は、これらもそれぞれ互いに独立に、−ＣＨ_２ＣＨ_２−、−ＣＯＯ−、トランス−ＣＨ＝ＣＨ−、トランス−ＣＦ＝ＣＦ−、−ＣＨ_２Ｏ−、−ＯＣＨ_２−、−ＣＦ_２Ｏ−、−ＯＣＯ_２−または単結合であり、好ましくはそれらの少なくとも１つは単結合であり、最も好ましくは、存在している場合に、それらの少なくとも２つは単結合であり、および
ｌは、０、１または２である。

Z ⁶¹ and Z ⁶² are each independently of each other, and when Z ⁶¹ is present twice, they are also each independently of each other, —CH ₂ CH ₂ —, —COO—, trans—CH═CH—, Trans-CF═CF—, —CH ₂ O—, —OCH ₂ —, —CF ₂ O—, —OCO ₂ — or a single bond, preferably at least one of them is a single bond, most preferably , When present, at least two of them are single bonds, and l is 0, 1 or 2.

  In a preferred embodiment of the present invention, the liquid crystal mixture of the present invention comprises one or more compounds of formula V selected from the group of compounds of formula Va to Vg.

Where
R ⁵ is alkyl having 1 to 7 carbons, alkoxy, fluorinated alkyl or fluorinated alkoxy, alkenyl having 2 to 7 carbons, alkenyloxy, alkoxyalkyl or fluorinated alkenyl,
X ⁵ is, independently of each other, F, Cl, fluorinated alkyl having 1 to 4 carbon atoms or fluorinated alkoxy, or fluorinated alkenyl having 2 to 4 carbon atoms or fluorinated respectively. Alkenyloxy, preferably F, OCF ₃ or OCF ₂ H,
L ^{51 to} L ⁵⁶ are each independently H or F, preferably at least one of them, preferably L ⁵¹ , more preferably two or more of them, preferably L ⁵¹ , L ⁵² and L F is selected from ⁵³ .

  In particular, the formulas Va-1 to Va-4, Vb-1 to Vb-15, Vc-1 to Vc-4, Vd-1 to Vd-8, Ve-1 to Ve-4, Vf-1 to Vf-4 And a liquid crystal mixture containing one or more compounds selected from the group consisting of Vg-1 to Vg-4.

式中、Ｒ^５は、炭素数１〜７のアルキル、アルコキシ、フッ素化されたアルキルまたはフッ素化されたアルコキシ、炭素数２〜７のアルケニル、アルケニルオキシ、アルコキシアルキルまたはフッ素化されたアルケニルである。

In the formula, R ⁵ is alkyl having 1 to 7 carbons, alkoxy, fluorinated alkyl or fluorinated alkoxy, alkenyl having 2 to 7 carbons, alkenyloxy, alkoxyalkyl or fluorinated alkenyl. .

  In a preferred embodiment of the present invention, the liquid crystal mixture of the present invention comprises one or more compounds of formula Vf-4.

  In a further preferred embodiment of the invention, which may be the same as or different from those already mentioned, the liquid-crystal mixtures of the invention comprise compounds of the formulas VIa to VIh, preferably VIa to VId and VIg, most preferably VIa and VIg. Preferably, the selected compound of formula VI is included, more preferably most, even more preferably substantially, most preferably all comprises component D comprising this.

式中、
Ｒ^６１およびＲ^６２は、それぞれ互いに独立に、炭素数１〜７のアルキル、アルコキシ、フッ素化されたアルキルまたはフッ素化されたアルコキシ、炭素数２〜７のアルケニル、アルケニルオキシ、アルコキシアルキルまたはフッ素化されたアルケニルであり、および
Ｌ^６は、ＨまたはＦである。

Where
R ⁶¹ and R ⁶² each independently represent alkyl having 1 to 7 carbons, alkoxy, fluorinated alkyl or fluorinated alkoxy, alkenyl having 2 to 7 carbons, alkenyloxy, alkoxyalkyl or fluorinated. Alkenyl, and L ⁶ is H or F.

  In a preferred embodiment of the present invention, the liquid crystal mixture of the present invention comprises one or more compounds of formula VIg.

  Preferably, the liquid crystal mixture includes one or more compounds selected from the following group of compounds.

The compound of formula VIa, wherein -R ⁶¹ and R ⁶² are alkyl,
The compound of formula VIa, wherein -R ⁶¹ is alkyl and R ⁶² is alkoxy;
The compound of formula VIa, wherein -R ⁶¹ is alkyl and R ⁶² is alkenyl;
The compound of formula VIb, wherein -R ⁶¹ and R ⁶² are alkyl,
The compound of formula VIb, wherein -R ⁶¹ is alkyl and R ⁶² is alkoxy;
The compound of formula VIc, wherein -R ⁶¹ and R ⁶² are alkyl,
The compound of formula VIc, wherein -R ⁶¹ is alkyl and R ⁶² is alkoxy;
The compound of formula VIc, wherein R ⁶¹ is alkyl and R ⁶² is alkenyl, and the compound of formula VId, wherein R ⁶¹ and R ⁶² are alkyl;

-Particularly preferred liquid crystal mixtures comprise one or more compounds of formula VIa in addition to one or more compounds selected from the group of formulas VIb to VId and VIg, particularly preferably R ⁶¹ is alkyl and R ⁶² is alkenyl. A mixture comprising a compound of formula VIa.

  In addition, the liquid crystal mixture according to the invention may comprise a further optional component, component E, which has a negative dielectric anisotropy, preferably a dielectrically negative of formula VII. More preferably, most preferably still substantially, most preferably all of them.

式中、
Ｒ^７１およびＲ^７２は、それぞれ互いに独立に、前記式ＩでＲ^１に与えられる意味を有し、

Where
R ⁷¹ and R ⁷² each independently of one another have the meaning given to R ¹ in formula I above;

Ｚ^７１およびＺ^７２は、それぞれ互いに独立に、−ＣＨ_２ＣＨ_２−、−ＣＯＯ−、トランス−ＣＨ＝ＣＨ−、トランス−ＣＦ＝ＣＦ−、−ＣＨ_２Ｏ−、−ＣＦ_２Ｏ−または単結合であり、好ましくは、これらの少なくとも一方は単結合であり、最も好ましくは、両方が単結合であり、
Ｌ^７１およびＬ^７２は、それぞれ互いに独立して、Ｃ−ＦまたはＮであり、好ましくはこれらの少なくとも一方はＣ−Ｆであり、最も好ましくは、両方がＣ−Ｆであり、および
ｋは、０または１である。

Z ⁷¹ and ^{Z 72} each, independently of one _{another, -CH 2 CH 2 -, -} COO-, trans -CH = CH-, trans _{-CF = CF -, - CH 2} O -, - CF 2 O- or a single A bond, preferably at least one of these is a single bond, most preferably both are single bonds,
L ⁷¹ and L ⁷² are each independently C—F or N, preferably at least one of them is C—F, most preferably both are C—F, and k is 0 or 1.

  Component F, which is a chiral compound that may be used as a chiral component, is each known to those skilled in the art for that chiral component. Such compounds are chiral dopants such as cholesteryl nonanoate (CN) C15 or CB15 available from Merck. Also useful are chiral dopants such as R-811 and S-811, R-1011 and S-1011 or R-5011 and S-5011 (which are pairs of enantiomeric compounds), which are also Merck. Available from the company. According to the latter, the desired twist direction of the cholesteric helix can be selected by using the appropriate enantiomer of the compound.

  Preferably, the liquid crystal medium of the present invention comprises components A to F, in particular compounds selected from the group of compounds of formulas I to VII, more preferably most, most preferably all consisting of these.

  “Including” in this application means that in the context of a composition, the mentioned item, eg a medium or component, contains a specific component or components or compound or components. This means that the total concentration is preferably 10% or more, and most preferably 20% or more.

  In the context, “consists mostly of” means that the item referred to is a particular component (s) or compound (s) 55% or more, preferably 60% or more, most preferably It means to contain 70% or more.

  In the context, “consisting essentially of” means that the item referred to is a particular component (s) or compound (s) of 80% or more, preferably 90% or more, most preferably Means containing 95% or more.

  In the context, “consisting entirely of” means that the item referred to is a particular component (s) or compound (s) of 98% or more, preferably 99% or more, most preferably 100 0.0% is meant to be contained.

  Particularly preferred are liquid crystal media in which component A comprises a compound selected from the group of compounds of formulas I to III, more preferably most, even more preferably substantially, most preferably all.

  Component E preferably comprises one or more compounds selected from the group consisting of compounds of the formula VII, preferably of formulas VIIa to VIIc, more preferably most, most preferably the whole.

式中、Ｒ^７１およびＲ^７２は、それぞれ前記式ＶＩＩで与えられる意味を有する。

In the formula, R ⁷¹ and R ⁷² each have the meaning given by formula VII.

In formulas VIIa-VIIc, R ⁷¹ is preferably an n-alkyl or 1-E-alkenyl group and R ⁷² is preferably n-alkyl or alkoxy.

  Also, in the medium of the present invention, other mesogenic compounds, which are not explicitly mentioned above, can be used arbitrarily and advantageously. Such compounds are known to those skilled in the art.

  Component A is preferably used at a concentration of 40% to 90% of the total mixture, more preferably 50% to 80%, more preferably 55% to 70%, most preferably 60% to 65%.

  Component B is preferably used at a concentration of 5% to 50%, more preferably 7% to 40%, more preferably 10% to 30%, most preferably 15% to 25% of the total mixture.

  Component C is preferably used at a concentration of 0% to 40%, more preferably 2% to 30%, more preferably 3% to 20%, most preferably 5% to 15% of the total mixture.

  Component D is preferably used at a concentration of 0% to 40%, preferably 0% to 20%, most preferably 5% to 15% of the total mixture.

  Component E is preferably used at a concentration of 0% to 30%, preferably 0% to 20%, most preferably 5% to 15% of the total mixture.

  Component F is preferably used at a concentration of 0% to 10%, preferably 0% to 5%, most preferably 0.5% to 2% of the total mixture.

  Optionally, the medium of the present invention can further comprise a liquid crystal compound in order to adjust the physical properties. Such compounds are known to those skilled in the art. Their concentration in the medium of the present invention is preferably 0% to 30%, more preferably 0% to 20%, most preferably 5% to 15%.

  Preferably, the liquid crystal medium comprises components A, B, C, D, E and F, preferably components A, B, C, D and F in total 50% to 100%, more preferably 70% to 100%, Most preferably, it contains 80% to 100%, especially 90% to 100%, in other words, formulas I, II, III (component A), IV (component B), V (component C), VI (component It contains one or more compounds of D) and VII (component E), more preferably most, most preferably the whole.

  The liquid crystal medium of the present invention is preferably characterized by a clearing point of 70 ° C. or higher, preferably 75 ° C. or higher, more preferably 80 ° C. or higher, especially 85 ° C. or higher.

  Δn of the liquid crystal medium of the present invention is preferably 0.11 or more, more preferably 0.12 or more, more preferably in the range of 0.120 to 0.200, more preferably in the range of 0.120 to 0.180, Most preferably, it is in the range of 0.120 to 0.160 or less, particularly in the range of 0.120 to 0.150.

  Δε at 20 ° C. at 1 kHz of the liquid crystal medium of the present invention is preferably 25.0 or more, more preferably 35.0 or more, more preferably 45 or more, most preferably 55.0 or more, particularly 65.0 or more. is there.

  The nematic phase of the medium according to the invention extends from at least 0 ° C. to 70 ° C., more preferably at least −20 ° C. to 70 ° C., most preferably at least −30 ° C. to 75 ° C., in particular at least −40 ° C. to 80 ° C. Preferably, however, “at least” in the context of the lower limit means that the temperature of the phase transition has spread to at least the lower limit, preferably lower than the lower limit, In the context of the upper limit value, it means that the phase transition temperature has spread to at least the upper limit value, preferably higher than the upper limit value.

  In this application, the term “dielectrically positive” means that the compound or component is Δε> 3.0, and the term “dielectrically neutral” is −1.5 ≦ Δε ≦ 3.0. The term “dielectrically negative” means Δε <−1.5 respectively, where Δε is determined at 20 ° C. at a frequency of 1 kHz. The dielectric anisotropy of a compound is determined from the result of a 10% solution of the individual compound in a nematic host mixture. The volume of the test mixture is determined in both cells with homeotropic and cells with homogeneous orientation. The cell gap for both types of cells is approximately 10 μm. The applied voltage is a square wave with a root mean square value typically between 0.5 V and 1.0 V at room temperature at a frequency of 1 kHz, however it is always below the capacity threshold of the respective test mixture. Selected.

  Mixture ZLI-4792 for dielectrically positive compounds, Mixture ZLI-3086 for dielectrically neutral and dielectrically negative compounds, both from Merck and Germany as host mixtures, respectively Is done. The dielectric constant of a compound is determined from the change in the value of each host compound due to the addition of the compound of interest, and the value is extrapolated to a concentration of 100% of the compound of interest.

  A component having a nematic phase at a measurement temperature of 20 ° C. is measured as it is, and all other points are treated in the same manner as the measurement of the compound.

The term “threshold voltage” in this application means the optical threshold, unless explicitly stated otherwise, and is given for 10% relative contrast (V ₁₀ ), and is also referred to as “saturation voltage”. The term means optical saturation and is given for 90% relative contrast (V ₉₀ ). The capacitive threshold voltage (V ₀ , also called Fredericks threshold V _Fr ) is used only when specifically stated.

  The ranges of parameters given in this application all include limit values unless explicitly stated otherwise.

Throughout this application, unless otherwise stated, all concentrations are given in weight percent and are associated with each complete mixture, all temperatures are given in degrees Celsius, and all temperature differences are also in degrees Celsius. Given. All physical properties were determined or determined by "Merk Liquid Crystals, Physical Properties of Liquid Crystals", Status magazine, November 1997, Merck, Germany, and unless otherwise stated, Given for a temperature of 20 ° C. The optical anisotropy (Δn) is determined at a wavelength of 589.3 nm. The dielectric anisotropy (Δε) is determined at a frequency of 1 kHz. The threshold voltage, as well as other electro-optical properties, were determined in a test cell made in Merck, Germany. The test cell for the determination of Δε had a cell gap of 22 μm. The electrode was a circular ITO electrode with an area of 1.13 cm ² and a guard ring. The alignment layer was lecithin for homeotropic alignment (ε _‖ ) and polyimide AL-1054 manufactured by Nippon Synthetic Rubber Co. for homogeneous alignment (ε _⊥ ). The capacity was determined with a frequency response analyzer Solatron 1260 using a sine wave having a voltage of 0.3 V _rms . The light used in the electro-optic measurement was white light. The configuration used was a device commercially available from Otsukasha, Japan. The characteristic voltage was determined under vertical observation. The threshold (V ₁₀ ) -medium gray (V ₅₀ )-and saturation (V ₉₀ ) voltages were determined at 10%, 50% and 90% relative contrast, respectively.

  The liquid crystal medium according to the present invention can further comprise additives and chiral dopants in conventional concentrations. The total concentration of these further constituents is in the range from 0% to 10%, preferably from 0.1% to 6%, based on the sum of the mixture. The concentration of each individual compound used is preferably in the range of 0.1% to 3%. The concentrations of these and similar additives are not considered in the concentration values and ranges of the liquid crystal components and compounds of the liquid crystal media of the present application.

  The liquid crystal medium of the invention according to the present application consists of several compounds, preferably 3-30, more preferably 8-20, and most preferably 10-16. These compounds are mixed in a conventional manner. As a rule, a given amount of the compound used in a smaller amount is dissolved in the compound used as a larger amount. It is particularly easy to observe the completion of the dissolution process if the temperature exceeds the clearing point of the compound used at the higher concentration. However, other conventional methods, for example the use of so-called pre-mixtures, which can be homologous compounds or eutectic mixtures, or so-called multi-bottle systems where the components themselves are ready-to-use Can also be prepared.

  With the addition of suitable additives, the liquid crystal media according to the invention can be used for all known types of liquid crystal displays, for example liquid crystal media such as TN-, TN-AMD, ECB-AMD, VAN-AMD, IPS and OCB LCDs. It can be modified to be usable in complex systems such as those used as is, especially PDLC, NCAP, PN LCD and especially ASM-PA LCD.

  The melting point T (C, N) of the liquid crystal, the transition T (S, N) from the smectic phase (S) to the nematic (N) phase, and the clearing point T (N, I) are given in degrees Celsius.

In the present application, and particularly in the examples shown below, the structure of the liquid crystal compounds is indicated by abbreviations, also referred to as abbreviations. The conversion from the abbreviation to the chemical formula is performed directly according to Tables A and B below. The groups C _n H _{2n + 1} and C _m H _{2m + 1} are all linear alkyl groups each having n or m carbon atoms. The explanation of Table B is self-explanatory. In Table A, only the abbreviations related to the parent structure are shown. In each case, the abbreviation for this parent structure is followed by a code that is separated by a hyphen to identify the substituents R ¹ , R ² , L ¹ and L ² .

＜表Ａ＞

<Table A>

＜表Ｂ＞

<Table B>

The liquid crystal medium of the present invention is preferably
7 or more, preferably 8 or more compounds selected from the group of compounds in Tables A and B, preferably compounds of different formulas, and / or one or more selected from the group of compounds in Table A, More preferably two or more compounds, preferably three or more compounds, preferably compounds of different formulas, and / or three or more selected from the group of compounds in Table B, more preferably four or more, Preferably it is 5 or more types of compounds, Preferably the compound of a different formula is included.

  In the following table, Table C shows the chiral compounds typically used as chiral dopants in the liquid crystal media of the present invention.

  <Table C>

以下のテーブルであるテーブルＤに、本発明の液晶媒体で安定剤として典型的に使用される化合物を示す。

Table D, below, shows compounds typically used as stabilizers in the liquid crystal media of the present invention.

  <Table D>

  The following examples illustrate the invention without limiting it in any way.

  However, the physical properties of the compositions explain to those skilled in the art what properties can be achieved and to what extent they can be varied. In particular, the various combinations of properties that can be preferably achieved are thus clarified for the person skilled in the art.

<Example 1>
A liquid crystal mixture having the composition and properties given in the following table is realized.

この混合物は、好ましい値のΔｎおよび高い値のΔεを有し、ＳＴＮモードで動作するディスプレイに非常に良く適している。

This mixture has a preferred value of Δn and a high value of Δε and is very well suited for displays operating in STN mode.

<Example 2>
A liquid crystal mixture having the composition and properties given in the following table is realized.

この混合物は、好ましい値のΔｎおよび高い値のΔεを有しており、ＳＴＮモードで動作するディスプレイに非常に良く適している。

This mixture has a preferred value of Δn and a high value of Δε and is very well suited for displays operating in STN mode.

Claims (10)

-Component A which is a first dielectrically positive component comprising one or more compounds of formula I and one or more compounds selected from the group of formulas II and III;
A liquid crystal medium comprising a second dielectrically positive component B comprising one or more compounds of the formula IV.

(Where
R ¹ , R ² and R ³ are each independently of each other alkyl, alkoxy having 1 to 7 carbon atoms, alkoxy, fluorinated alkyl or fluorinated alkoxy, alkenyl having 2 to 7 carbon atoms, alkenyloxy, Alkoxyalkyl or fluorinated alkenyl, and m is 0 or 1; )

(Where
R ⁴ has the meaning given to R ² in formula II;
Z ⁴ is —CO—O— or a single bond,

X ⁴ is F or OCF ₃ and Y ⁴ is H or F. ) 2. A liquid-crystal medium according to claim 1, comprising a dielectrically positive component A comprising one or more compounds of the formula I in which R ¹ is alkenyl. 3. Liquid crystal medium according to claim 1 or 2, characterized in that it comprises a component C which is a third dielectrically positive component comprising one or more compounds of the formula V given in the description.

(Where
R ⁵ has the meaning given to R ² in formula II above;

Z ⁵¹ and Z ⁵² are each independently of each other, and when Z ⁵¹ is present twice, they are each independently of each other, —CH ₂ CH ₂ —, —COO—, trans—CH═CH—, Trans-CF═CF—, —CH ₂ O—, —CF ₂ O— or a single bond,
X ⁵ is F, Cl, halogenated alkyl, halogenated alkoxy, halogenated alkenyl or halogenated alkenyloxy,
n is 0, 1 or 2, and the compounds of formulas IVa-IVd are excluded. ) 4. A liquid crystal medium according to claim 1, comprising a component D which is a dielectrically neutral component comprising one or more compounds of the formula VI given in the description.

(Where
R ⁶¹ and R ⁶² each independently of one another have the meaning given to R ² in formula II above;

Z ⁶¹ and Z ⁶² are each independently of each other, and when Z ⁶¹ is present twice, they are also each independently of each other, —CH ₂ CH ₂ —, —COO—, trans—CH═CH—, Trans-CF═CF—, —CH ₂ O—, —OCH ₂ —, —CF ₂ O—, —OCO ₂ — or a single bond, and l is 0, 1 or 2. ) 5. A liquid crystal medium according to claim 1, comprising a component E which is a dielectrically negative component comprising one or more compounds of the formula VII given in the description.

(Where
R ⁷¹ and R ⁷² each independently of one another have the meaning given to R ¹ in formula I above;

Z ⁷¹ and ^{Z 72} each, independently of one _{another, -CH 2 CH 2 -, -} COO-, trans -CH = CH-, trans _{-CF = CF -, - CH 2} O -, - CF 2 O- or a single Is a bond,
L ⁷¹ and L ⁷² are each independently C—F or N, and k is 0 or 1. ) The liquid crystal medium according to claim 1, comprising at least one compound of the formula IV selected from the group of compounds of the formulas IVa to IVd.

(Wherein R ⁴ has the meaning given in claim 1).   7. A liquid crystal medium according to claim 1, comprising one or more compounds of the formula III given in claim 1.   A liquid crystal display comprising the liquid crystal medium according to claim 1.   9. The liquid crystal display according to claim 8, wherein the liquid crystal display is an STN display.   Use of the liquid crystal medium according to any one of claims 1 to 7 in a liquid crystal display.