KR20040027455A - Method for setting the dispersion of liquid-crystal media, liquid-crystal medium, and electro-optical display containing same - Google Patents

Abstract

PURPOSE: Provided are a liquid crystal medium having a specific dispersity of double refraction for the improvement of color effect, a method for setting dispersity thereof and an electro-optical display containing the same. CONSTITUTION: The nematic liquid crystal medium comprises (a) a component A comprised of a compound having low double refraction(Δn) in the range of 0.080 or less, (b) optionally, a component B comprised of a compound having middle double refraction ranging from 0.081 to 0.149, and (c) a component C having high double refraction in the range of 0.150 or more. The dispersity of such nematic liquid crystal medium is set by selecting individual compounds so that relative dispersity(σΔn/Δn_mix) of double refraction(Δni) thereof is 0.50 or more.

Description

Method of setting the dispersion degree of the liquid crystal medium, liquid crystal medium and an electro-optical display containing the same {METHOD FOR SETTING THE DISPERSION OF LIQUID-CRYSTAL MEDIA, LIQUID-CRYSTAL MEDIUM, AND ELECTRO-OPTICAL DISPLAY CONTAINING SAME}

The present invention relates to a liquid crystal display, in particular a liquid crystal display using an active matrix addressed liquid crystal display (AMD or AMLCD), in particular an active matrix comprising a thin film transistor (TFT) or varistor. The invention also relates to a liquid crystal medium used for this type of display.

This type of AMD can use a variety of negative electronic switching devices. Display devices using three-pole switching elements are most widely used. These are also preferred for the present invention. Examples of three-pole switching elements of this type are MOS (metal oxide silicon) transistors, or TFTs or varistors mentioned above. In the TFT, various semiconductor materials, mainly silicon or optionally cadmium selenide, are used. In particular, polycrystalline silicon or amorphous silicon is used. Unlike three-pole electronic switching devices, a matrix of two-pole switching devices, such as, for example, metal insulator metal (MIM) diodes, ring diodes, or "back-to-back" diodes, is also used by AMD. It can be used to. However, as described in more detail below, they are generally undesirable due to the inferior electro-optic properties obtained by AMD.

Liquid crystals used as dielectrics in this type of liquid crystal display are liquid crystals whose optical properties reversibly change upon application of voltage. Electro-optic displays using liquid crystals as the medium are known to those skilled in the art. These liquid crystal displays utilize various electro-optic effects.

The most widespread conventional display devices use TN effect (torsional nematic, having a twisted nematic structure of about 90 °), STN effect (super-torsional nematic) or SBE effect (super-torsional birefringence effect). In these and similar electro-optic effects, a liquid crystal medium of positive dielectric anisotropy (Δε) is used.

In a typical display device (i.e., including a display device using these effects), the driving voltage should be as low as possible, so that a relatively high dielectric anisotropic liquid crystal medium is used, which is generally composed of a dielectrically positive liquid crystal compound, At most a relatively small / low ratio of genetically neutral compounds.

Unlike the conventional display device using the electro-optic effect which requires a positive dielectric anisotropic liquid crystal medium, for example, ECB effect (electrically controlled birefringence), and its subtypes DAP (matching phase deformation), VAN (vertical) There are also other electro-optic effects using negative dielectric anisotropic liquid crystalline media such as matching nematic) and CSH (color super homeotropic). These are also claims of the present invention.

The recently increasing use of IPS (Planar Switching) effects can use both genetically positive or genetically negative liquid crystal media similar to "guest / host" displays, which may be genetically positive or positive depending on the display mode used. Dyes in genetically negative media can be used. In the case of the liquid crystal display mentioned also in this paragraph, a display using a dielectric negative liquid crystal medium is also a subject matter of the present invention.

A further very promising type of liquid crystal medium is a so-called "axially symmetric microarea" (abbreviated as ASM) display, which is preferably addressed by a plasma arrangement (plasma addressed liquid crystal display, or PALCD). These displays are also claims of the present invention.

The liquid crystal media used in the above-mentioned liquid crystal displays, and all liquid crystal displays utilizing similar effects, are generally liquid crystal compounds having corresponding dielectric anisotropy, i.e., positive dielectric anisotropic compounds in the case of a dielectrically positive medium. , And in the case of a genetically negative medium, it consists mainly of negative dielectric anisotropic compounds and in most cases is very substantially.

In order to achieve a fairly good contrast, the optical retardation, i.e. the product of the birefringence (Δn) of the liquid crystal material and the layer thickness (d) of the liquid crystal layer, should have a value suitable for the particular electro-optic mode used.

The birefringence of the liquid crystal material depends relatively high on the wavelength of the light used. This effect is also known as birefringence dispersion. Due to this effect, the specific individual birefringence value desired for the electro-optic display mode can be set only at a single wavelength.

The degree of dispersion of typical liquid crystal mixtures is described, for example, in Wu, T.S. et al., SPIE Vol. 684, "Liquid Crystals and Spatial Light Modulator Materials" (1986), pp. 69-76. At shorter wavelengths birefringence increases significantly, while at longer wavelengths a certain limit is reached. A widely used form for describing the birefringence wavelength dependence is the development of a polynomial according to the wavenumber, the reciprocal of the reciprocal of the wavelength, which is the Cauchy equation of Eq.

Where

λ is the wavelength,

Δn (λ) is birefringence at wavelength λ,

Δn (∞) is birefringence at infinite wavelength,

A and C are constants.

In some applications a specific birefringence dispersion of the liquid crystal material is required. In this case, for example, there is an IPS display device. In these displays, the undesirable color effects that occur at various specific viewing angles generally depend on the degree of birefringence dispersion depending on the wavelength of the liquid crystal material used. Although the display uses a compensation layer, for example in many monitor or TV applications, the degree of dispersion of the liquid crystal material is a very essential factor in viewing angle dependence.

Known liquid crystal mixtures do not meet the above requirements, or meet to an inappropriate level.

Accordingly, there has been a continuing need for liquid crystal media that do not have the disadvantages of the media from the prior art or have at least a significantly reduced degree of disadvantage.

It is an object of the present invention to provide a liquid crystal material having a specific degree of birefringence dispersion and to provide a method for obtaining the material.

In fact, virtually all liquid crystal materials used in liquid crystal displays are not individual compounds but mixtures of a plurality of individual compounds. The inventors of the present invention have found that the birefringence dispersion of the liquid crystal mixture can be influenced by the corresponding selection of the compounds used and thus can be selected in the desired manner.

The present specification also sets the dispersion degree of the liquid crystal medium, characterized in that the relative birefringence dispersion (σ _Δn / Δn _mix ) of the individual compounds (Δn _i ) in which the individual compounds are used is 0.50 or more. It is about a method.

The birefringence of the liquid crystal mixture is measured by the birefringence value of the compound used. Approximately, the birefringence of the mixture is obtained as an arithmetic mean which is augmented in each mole fraction with respect to the birefringence values of all the individual compounds used.

In order to obtain a liquid crystal mixture having a given birefringence, when all the individual compounds having birefringence values relatively close to the birefringence values of the mixture are mixed with each other, the birefringence dispersion of the mixture is relatively low. In contrast, however, when a compound in which the birefringence value is significantly different from the birefringence value of the mixture is used, the obtained mixture has a relatively high degree of dispersion. A mixture having a degree of dispersion present between these two extreme forms can be obtained by using a compound having a birefringence value that is significantly different from the birefringence value of the mixture in a proportion corresponding to the concentration of the compound having an average birefringence.

A measure that can be used to characterize the degree of deviation of the birefringence value of a mixture and the birefringence value of an individual compound is the degree of dispersion (σ _Δn ) according to Equation II below.

Where

Δn _i is the birefringence of the compound i,

Δn _mix is the birefringence of the mixture.

Here also, the relative values σ _Δn / Δn _mix are generally suitable for comparing different mixtures. This applies in particular when the mixtures to be compared have significantly different birefringence values.

The liquid crystal mixture according to the invention preferably comprises component A consisting of a low birefringent compound. The birefringence value (Δn) of the compound in this component is in the range of 0.080 or less, preferably 0.070 or less, particularly preferably 0.06 or less.

The liquid crystal mixture according to the invention preferably comprises component B consisting of a compound of intermediate birefringence, with a birefringence value in the range of 0.081 to 0.149, preferably 0.090 to 0.140.

The liquid crystal mixture according to the invention preferably comprises component C consisting of a high birefringent compound having a birefringence value of at least 0.150, preferably at least 0.160, particularly preferably at least 0.170.

The liquid crystal mixture according to the invention preferably has a birefringence value of 0.070 to 0.110, particularly preferably 0.075 to 0.100, very particularly preferably 0.080 to 0.095.

Component A preferably comprises a compound selected from the group consisting of the following compounds, in particular consisting mainly of them, particularly preferably consisting essentially of them completely and very particularly preferably consisting exclusively of these:

Compounds having a cyclohexane ring and a phenyl ring,

A compound having two cyclohexane rings, and

Compounds having three cyclohexane rings,

At least one of the compounds in the compound, preferably one or two non-contiguous groups, preferably two CH ₂ groups in one cyclohexane ring, may be substituted by O.

Component B preferably comprises a compound selected from the group consisting of the following compounds, in particular mainly consisting of them, particularly preferably consisting essentially of them completely and very particularly preferably consisting exclusively of these:

A compound having two cyclohexane rings and one phenyl ring, wherein these compounds can be genetically neutral or genetically positive; and

A compound having one cyclohexane ring and two phenyl rings that are genetically positive.

Component C is preferably a compound having two phenyl rings, which are preferably directly connected to each other, preferably comprising a compound selected from the group consisting of the following compounds, in particular consisting mainly of them, particularly preferably essential And very particularly preferably only exclusively of these:

Compounds having two phenyl rings,

A compound having two phenyl rings and one cyclohexane ring that are genetically neutral, and

Compounds having two phenyl rings and two cyclohexane rings.

Component A preferably comprises a compound selected from the group consisting of compounds of the formulas (1) and (2), in particular consisting mainly of them, particularly preferably consisting essentially of them completely and very particularly preferably substantially Exclusively made of these:

Where

R ¹¹ and R ¹² are each independently of each other alkyl having 1 to 15, preferably 1 to 7 carbon atoms, which are optionally at least monosubstituted by halogen, preferably F, wherein the O atoms are directly So that at least one CH ₂ group is independently of each other at each occurrence so that -O-, -S-, -CH = CH-, , -CO-, -CO-O-, -O-CO- or -O-CO-O-, wherein one of R ¹¹ and R ¹² is alternatively H or F, preferably R ¹¹ is alkyl and R ¹² is alkyl, alkoxy, alkenyl or CF ₃ ,

Z ¹¹ and Z ¹² are each independently of the other -CH ₂ -CH _2- , -CF ₂ -CF _2- , -CF ₂ -CH _2- , -CH ₂ -CF _2- , -CH = CH-, -CF = CF-, -CF = CH-, -CH = CF-, -C≡C-, -COO-, -OCO-, -CH 2 O-, -OCH 2 -, -CF 2 O-, -OCF 2 -,-(CH ₂ ) ₄ -or a single bond,

n is 0, 1 or 2,

R ²¹ , R ²² and Z ² are each as defined for the corresponding parameters R ¹¹ , R ¹² and Z ¹¹ in Formula 1, and R ²² is optionally F, Cl, -CF ₃ , -OCF ₂ H or -OCF ₃ ,

In the cyclohexane rings of the formulas (1) and (2), one or two, preferably two non-adjacent CH ₂ groups may be substituted by O atoms, and the phenyl ring of formula (2) by one or two F atoms, Preferably at the ortho-position relative to the R ²² group.

Component A preferably comprises a compound selected from the group consisting of compounds of the formulas (1) and (2) of the following conditions, in particular consisting mainly of them, particularly preferably consisting essentially of them completely and very particularly preferably It consists essentially of these exclusively:

R ¹¹ is n-alkoxy having 1 to 7 carbon atoms,

R ¹² is n-alkoxy having 1 to 7 carbon atoms, alkenyloxy or CF ₃ having 2 to 7 carbon atoms,

Z ¹¹ and Z ¹² are each independently of the other _{-CH 2 -CH 2 -, -CH 2} O-, -OCH 2 -, -CF 2 O-, -OCF 2 -, -COO- - (CH 2) 4 - Or a single bond, preferably -CH ₂ -CH _2- , -CF ₂ O- -COO- or a single bond,

n is 0, 1 or 2, preferably 0 or 1,

R ²¹ is n-alkyl having 1 to 7 carbon atoms, n-alkoxy having 1 to 7 carbon atoms, or alkenyloxy having 2 to 7 carbon atoms,

R ²² is n-alkoxy having 1 to 7 carbon atoms, alkenyloxy having 2 to 7 carbon atoms, n-alkyl having 1 to 7 carbon atoms, F, Cl, -CF ₃ , -OCF ₂ H or -OCF ₃ ,

Z ² is as defined for Z ¹¹ and is preferably a single bond.

Component B preferably comprises a compound selected from the group consisting of the compounds of the following formulas (3) and (4), in particular mainly consisting of them, particularly preferably consisting essentially of them completely and very particularly preferably substantially Exclusively made of these:

Where

R ³¹ and R ³² are each independently of each other as defined above for the corresponding parameters R ²¹ and R ²² in Formula 2,

R ³¹ is preferably n-alkyl having 1 to 7 carbon atoms, n-alkoxy having 1 to 7 carbon atoms, or alkenyloxy having 2 to 7 carbon atoms,

R ³² is preferably n-alkyl or n-alkoxy having 1 to 7 carbon atoms, alkoxyalkyl or alkenyloxy having 2 to 7 carbon atoms, halogen, fluorinated alkyl having 1 to 3 carbon atoms Or alkoxy, or alkenyl or alkenyloxy having 2 or 3 carbon atoms, preferably F, Cl or -OCF ₃ , particularly preferably F or -OCF ₃ , very particularly preferably F,

Z ³¹ and Z ³² are each independently of each other as defined for Z ¹¹ in Formula 2,

L ³¹ and L ³² are each independently H or F,

R ⁴¹ and R ⁴² are each independently of each other as defined above for the corresponding parameters R ²¹ and R ²² in Formula 2,

R ⁴¹ is preferably n-alkyl having 1 to 7 carbon atoms, n-alkoxy having 1 to 7 carbon atoms, or alkenyloxy having 2 to 7 carbon atoms,

R ⁴² is preferably n-alkyl having 1 to 7 carbon atoms, n-alkoxy having 1 to 7 carbon atoms, alkenyloxy having 2 to 7 carbon atoms, halogen, 1 to 3 carbon atoms Fluorinated alkyl or alkoxy having 3 or alkenyl or alkenyloxy having 2 or 3 carbon atoms, preferably F, Cl or -OCF ₃ , particularly preferably F or -OCF ₃ , very particularly preferably Is F,

L ⁴¹ and L ⁴² are each independently H or F,

Z ⁴¹ and Z ⁴² are each independently of each other as defined for Z ¹¹ in Formula 2,

The phenyl ring in the center of formula (4) may be mono-, di- or poly-substituted by the F atom, preferably mono- or di-substituted.

Component C preferably comprises at least one compound, in particular consists mainly of one or more compounds selected from the group consisting of compounds of the formulas (5) to (8), particularly preferably consists essentially of them completely and very particularly preferably Only substantially exclusively:

Where

R ⁵¹ and R ⁵² are each independently of each other as defined above for the corresponding parameters R ²¹ and R ²² in Formula 2,

R ⁵¹ is preferably n-alkyl having 1 to 7 carbon atoms, n-alkoxy having 1 to 7 carbon atoms, or alkenyloxy having 2 to 7 carbon atoms,

R ⁵² is preferably n-alkyl or n-alkoxy having 1 to 7 carbon atoms, alkoxyalkyl or alkenyloxy having 2 to 7 carbon atoms, halogen, fluorinated alkyl having 1 to 3 carbon atoms Or alkoxy, or alkenyl or alkenyloxy having 2 or 3 carbon atoms, preferably F, Cl or -OCF ₃ , particularly preferably F or -OCF ₃ , very particularly preferably F,

Z ⁵¹ and Z ⁵² are each independently the same as defined for Z ¹¹ in Formula 2,

m is 0 or 1, preferably 1,

R ⁶¹ and R ⁶² are each independently of each other as defined above for the corresponding parameters R ²¹ and R ²² in Formula 2,

R ⁶¹ is preferably n-alkyl having 1 to 7 carbon atoms, n-alkoxy having 1 to 7 carbon atoms, or alkenyloxy having 2 to 7 carbon atoms,

R ⁶² is preferably n-alkyl having 1 to 7 carbon atoms, n-alkoxy having 1 to 7 carbon atoms, alkenyloxy having 2 to 7 carbon atoms, halogen, 1 to 3 carbon atoms Fluorinated alkyl or alkoxy having 3 or alkenyl or alkenyloxy having 2 or 3 carbon atoms, preferably F, Cl or -OCF ₃ , particularly preferably F or -OCF ₃ , very particularly preferably Is F,

Z ⁶¹ , Z ⁶² and Z ⁶³ are each independently of one another as defined for Z ¹¹ in Formula 2, preferably each independently of —CH ₂ —CH ₂ —, —CF ₂ —O—, —O— CF _2- , -CO-O- or a single bond,

o is 0 or 1,

R ⁷¹ and R ⁷² are each independently of each other as defined above for the corresponding parameters R ²¹ and R ²² in Formula 2,

R ⁷¹ is preferably n-alkyl having 1 to 7 carbon atoms, n-alkoxy having 1 to 7 carbon atoms, or alkenyloxy having 2 to 7 carbon atoms,

R ⁷² is preferably n-alkyl having 1 to 7 carbon atoms, n-alkoxy having 1 to 7 carbon atoms, alkenyloxy having 2 to 7 carbon atoms, halogen, 1 to 3 carbon atoms Fluorinated alkyl or alkoxy having 3 or alkenyl or alkenyloxy having 2 or 3 carbon atoms, preferably F, Cl or -OCF ₃ , particularly preferably F or -OCF ₃ , very particularly preferably Is F,

Z ⁷¹ , Z ⁷² and Z ⁷³ are each independently of one another as defined for Z ¹¹ in Formula 2, preferably each independently of —CF ₂ —O—, —O—CF ₂ —, —CO—O -Or a single bond, particularly preferably a single bond,

R ⁸¹ and R ⁸² are each independently of each other as defined above for the corresponding parameters R ²¹ and R ²² in Formula 2,

R ⁸¹ is preferably n-alkyl having 1 to 7 carbon atoms, n-alkoxy having 1 to 7 carbon atoms, or alkenyloxy having 2 to 7 carbon atoms,

R ⁸² is preferably n-alkyl having 1 to 7 carbon atoms, n-alkoxy having 1 to 7 carbon atoms, alkenyloxy having 2 to 7 carbon atoms, halogen, 1 to 3 carbon atoms Fluorinated alkyl or alkoxy having 3 or alkenyl or alkenyloxy having 2 or 3 carbon atoms, preferably F, Cl or -OCF ₃ , particularly preferably F or -OCF ₃ , very particularly preferably Is F,

Z ⁸¹ , Z ⁸² and Z ⁸³ are each independently of one another as defined for Z ¹¹ in Formula 2, preferably each independently of the other -CF ₂ -O-, -O-CF _2- , -CO-O -Or a single bond, particularly preferably a single bond,

The phenyl rings in the formulas (5) to (8) may each independently be mono-, di- or poly-substituted by an F atom, preferably mono- or di-substituted, wherein the compound of Formula 4 is excluded from Formula 6 .

Examples of compounds which are preferred constituents of components A, B and C are shown below.

Component A is preferably represented by the formulas (I-1) to (I-6) and (II-1), preferably (I-1) to (I-4), (I-6) and (II-1), particularly preferably At least one compound selected from the group consisting of compounds of formula I-1, formula I-2 and formula II-1, in particular consisting mainly of them, particularly preferably consisting essentially of them, very particularly preferably Consists essentially of these completely:

I-1

I-2

I-3

I-4

I-5

I-6

II-1

Where

R ¹¹ and R ¹² are each independently of one another being as defined above in Formula 1 and are preferably alkyl, alkenyl, alkoxy or —CF ₃ .

Component B preferably comprises at least one compound selected from the group consisting of the compounds of the following formulas III-1 to III-9 and IV-1 to IV-12, in particular consisting mainly of them, particularly preferably Consists essentially of these completely and very particularly preferably substantially completely:

III-1

III-2

III-3

III-4

III-5

III-6

III-7

III-8

III-9

Where

R ³¹ , R ³² and L ³¹ are each independently of each other as defined above for Formula 3, R ³¹ is preferably alkyl or alkenyl, and R ³² is preferably F, Cl or -OCF ₃ , Particularly preferably F or -OCF ₃ , optionally in formula (III-1) alkyl or alkenyl, L ³¹ is preferably F when R ³² is F and L when R ³² is -OCF ₃ ³¹ is preferably H.

IV-1

IV-2

IV-3

IV-4

IV-5

IV-6

IV-7

IV-8

IV-9

IV-10

IV-11

IV-12

Where

R ⁴¹ , R ⁴² and L ⁴¹ are each independently of each other as defined above for Formula 4, R ⁴¹ is preferably alkyl or alkenyl, and R ⁴² is preferably F, Cl or -OCF ₃ , particularly preferably F or -OCF _3, and R ⁴² is F and L ⁴¹ is preferably is in the case of F, R ⁴² is L ⁴¹ when the -OCF ₃ is preferably H.

Component C is preferably at least one selected from the group consisting of compounds of the following formulas V-1 to V-3, VI-1 to VI-3, VII-1 and VIII-1 to VIII-3 It comprises compounds, in particular consists mainly of them, particularly preferably consists essentially of them completely and very particularly preferably consists essentially of:

V-1

V-2

V-3

Where

The parameters are as defined in Formula 5,

Each of the phenyl rings may be mono-, di- or polysubstituted by F atoms independently of one another, preferably mono- or di-substituted.

VI-1

VI-2

VI-3

Where

The parameters are as defined in Formula 4,

Each of the phenyl rings may be mono-, di- or polysubstituted by F atoms independently of one another, preferably mono- or di-substituted.

VII-1

Where

The parameters are as defined in Formula 7,

Each of the phenyl rings may be mono-, di- or polysubstituted by F atoms independently of one another, preferably mono- or di-substituted.

VIII-1

VIII-2

VIII-3

Where

The parameters are as defined in Formula 8,

Each of the phenyl rings may be mono-, di- or polysubstituted by F atoms independently of one another, preferably mono- or di-substituted.

The compound of formula (I-1) is preferably selected from the group consisting of the compounds of formula (I-1a) to (I-1e):

I-1a

I-1b

I-1c

I-1d

I-1e

Where

n and m are each independently of each other 1 to 9, preferably 1 to 5, particularly preferably 1 to 3 for an alkyl group, and 2 to 9, preferably 2 to 5, particularly preferred for an alkenyl group Preferably 2 and 3.

The compound of formula (II-1) is preferably selected from the group consisting of the compounds of formula (II-1a) to (II-1d):

II-1a

II-1b

II-1c

II-1d

Where

n and m are each independently of each other 1 to 9, preferably 1 to 5, particularly preferably 1 to 3.

The compound of formula III-1 is preferably selected from the group consisting of compounds of formula III-1a to formula III-1c:

III-1a

III-1b

III-1c

Where

R ³¹ is as defined above in Formula 3, preferably for Formula III-1,

R ³² is alkyl, alkoxy or alkenyl, particularly preferably alkyl having 1 to 3 carbon atoms, vinyl or 1E-alkenyl.

The compound of formula III-2 is preferably selected from the group consisting of the compounds of formula III-2a to formula III-2e:

III-2a

III-2b

III-2c

III-2d

III-2e

Where

R ³¹ is as defined above for Formula 3, preferably Formula III-2, preferably alkyl or alkenyl.

The compound of formula III-9 is preferably selected from the group consisting of the compounds of formula III-9a to formula III-9c:

III-9a

III-9b

III-9c

Where

R ³¹ is as defined for Formula 3, preferably Formula III-8, preferably alkyl or alkenyl.

The compound of formula V-2 is preferably selected from the group consisting of the compounds of formula V-2a to formula V-2c:

V-2a

V-2b

V-2c

Where

The parameters are as defined in formula 5, preferably in formula V-2.

The compound of formula V-3 is preferably selected from the group consisting of the compounds of formulas V-3a to V-3e, preferably of formulas V-3d and V-3e:

V-3a

V-3b

V-3c

V-3d

V-3e

Where

The parameters are as defined in formula 5, preferably in formula V-3.

The compound of formula VI-1 is preferably selected from the group consisting of the compounds of formulas VI-1a to VI-1c:

VI-1a

VI-1b

VI-1c

Where

The parameters are as defined in formula 6, preferably formula VI-1.

The compound of formula VI-2 is preferably selected from the group consisting of the compounds of formula VI-2a and formula VI-2b:

VI-2a

VI-2b

Where

The parameters are as defined in formula 6, preferably in formula VI-2,

R ⁶¹ is alkyl or alkenyl,

R ⁶² is alkyl, alkenyl, F or -OCF ₃ .

The compound of formula (VII-1) is preferably selected from the group consisting of the compounds of formula (VII-1a) to (VII-1e):

VII-1a

VII-1b

VII-1c

VII-1d

VII-1e

Where

The parameters are as defined in formula 7, preferably in formula VII-1,

R ⁷¹ is alkyl or alkenyl,

R ⁷² is alkyl, alkenyl, F or —OCF ₃ , particularly preferably selected from the group consisting of Formula VII-1d and Formula VII-1e,

Especially preferably, R ⁷² is F.

In the present specification, the following definitions apply in connection with the description of the components of the composition.

"Comprising": the concentration of the relevant constituents in the composition is preferably at least 5%, particularly preferably at least 10%, very particularly preferably at least 20%,

“Consisting mainly of”: the concentration of the relevant constituents in the composition is preferably at least 50%, particularly preferably at least 55%, very particularly preferably at least 60%,

“Essentially complete”: the concentration of the relevant constituents in the composition is preferably at least 80%, particularly preferably at least 90%, very particularly preferably at least 95%,

“Substantially completely”: The concentration of the relevant constituents in the composition is preferably at least 98%, particularly preferably at least 99%, very particularly preferably 100.0%.

This applies both to the medium being a composition having these components which may be components and compounds, and to the components and compounds having these components.

Component B preferably consists mainly of one or more compounds selected from the group consisting of the compounds of the formulas (3) and (4), preferably of the formulas (III-1), (III-2) and (4), particularly preferably essentially completely And very particularly preferably substantially completely. In the compound of formula III-1a, R ³² is preferably alkyl, alkenyl or alkoxy. In addition, the right-hand phenyl ring in the compounds of the formulas (3) and (4) is preferably substituted as follows:

or

, Preferably

.

Component C is preferably predominantly with at least one compound selected from the group consisting of compounds of the formulas V-2 and V-3, preferably of the formulas V-2a, V-2b, V-2c and V-3. And particularly preferably essentially completely, very particularly preferably substantially completely. In the compounds of the formulas V-2a and V-2c, R ⁵² is preferably F and in the compounds of the formula V-2b, R ⁵² is preferably -OCF ₃ . In the compound of formula 5 the preferential phenyl ring is preferably substituted as follows:

, Preferably

.

In a preferred embodiment, the liquid crystal medium according to the invention is based on the whole mixture.

5 to 85%, preferably 10 to 70%, particularly preferably 20 to 60% of component A, preferably a compound selected from compounds of formula 1 and formula 2, particularly preferably of formula 1;

Component B, preferably 0 to 20%, preferably 0 to 12%, particularly preferably 0 to 10%, very particularly preferably compounds selected from compounds of formula 3 and formula 4, particularly preferably of formula 3 0-5%; And

Component C, preferably from 0 to 50%, preferably from 0 to 40%, particularly preferably from 10 to 40%, very particularly preferably from compounds selected from compounds of formulas 5 to 7, 7, particularly preferably of formula 5 5-25%.

The medium according to the invention preferably consists mainly of component A, component B and component C, particularly preferably essentially completely.

In the present invention, the individual compounds are used at concentrations of 1 to 25%, preferably 2 to 20%, particularly preferably 4 to 16%, respectively. The exception is that it is formed by a compound having three phenyl rings, and a compound having four six membered rings. These compounds are each used at a concentration of 0.5 to 15%, preferably 1 to 10%, particularly preferably 1 to 8%, per individual compound. For component A, in particular for the compounds of formulas 1 and 2, in particular formula 1, the preferred concentration limit for the proportion of the individual compounds in the medium is 1 to 20%, preferably 1 to 15%, particularly preferably 3 To 11%, very particularly preferably 8% or less.

In a preferred embodiment, the liquid crystal medium is particularly preferably entirely 40 to 70% of the compound of formula 1; 0-20% of the compound of formula 3, preferably of formula III-2, particularly preferably III-2b; And 10 to 35% of a compound of Formula 5 to Formula 8, preferably of Formula 5 and Formula 7.

In this embodiment, the liquid crystalline medium is particularly preferably in total from 40 to 80% of the compounds of the formula (I-1) and (I-2); And 0 to 5% of the compound of formula 3, preferably of formula III-2, particularly preferably of III-2b.

The liquid crystal medium according to the invention preferably has a nematic phase in each case at least -20 to 70 ° C, particularly preferably at -30 to 80 ° C, very particularly preferably at -40 to 90 ° C.

The term "having a nematic phase" herein means that no smectic phase and crystallization are observed first at lower temperatures than the corresponding temperature, and then also no clearing occurs upon heating from the nematic phase. Measurements at low temperatures are carried out in flowmeter viscometers at corresponding temperatures and confirmed by storage for at least 100 hours in test cells having a layer thickness corresponding to electro-optical applications. At high temperatures, the clearing point is measured in the capillary by conventional methods.

In addition, the liquid crystal medium according to the invention is characterized by the following relatively high optical anisotropy values. The birefringence value is preferably in the range of 0.065 to 0.115, particularly preferably in the range of 0.075 to 0.105, very particularly preferably in the range of 0.080 to 0.105.

In particular, the liquid crystal medium according to the invention has a relatively high optical anisotropy dispersion degree.

The relative birefringence dispersion (σ _Δn / Δn _mix ) of the individual compounds used is preferably 0.50 or more, preferably 0.50 to 0.90, particularly preferably 0.60 or more, preferably 0.60 to 0.90, very particularly preferred Preferably it is 0.70 or more, Preferably it is 0.70 to 0.90.

In addition, the liquid crystal medium according to the present invention has a low threshold voltage (V ₁₀ ) value, preferably a threshold voltage value of 2.00V or less, preferably 1.80V or less.

Their preferred values for the individual physical properties are also measured in each case in combination with each other. Particular preference is given to liquid crystal media having a combination of the properties of a relatively low rotational viscosity γ ₁ and a high transparent point T (N, I) shown in Table 1 below.

parameter T (N, I) / ° C γ ₁ / mPas Preferably ≥90 ≤200 Particularly preferably ≥80 ≤150 Very particularly preferably ≥70 ≤120

In the present specification, "≤" means "less than", preferably "less than", and "≥" means "greater than", preferably "greater than".

In this specification, Represents trans-1,4-cyclohexylene.

As used herein, the term "genetically positive compound" means a compound having Δε greater than 1.5, and the term "genetically neutral compound" means a compound having Δε of -1.5 or more and 1.5 or less, The term totally negative compound "means a compound with Δε less than 1.5. The dielectric anisotropy of the compound dissolves 10% of the compound in the liquid crystal host, at least one test cell having a thickness of 20 μm with homeotropic surface matching, and 1 kHz in at least one test cell having a thickness of 20 μm with homogeneous surface matching. Measure the capacitance of the mixture at. The measurement voltage is typically 0.5 to 1.0 V, but always below the critical capacitance of each liquid crystal mixture.

The host mixture used for the genetically positive compound and the genetically neutral compound is ZLI-4792, and the host mixture used for the genetically negative compound is ZLI-2857, all of which are Merck KGaA, Germany. ) Product. The change in the dielectric constant of the host mixture after addition of the compound to be measured and the extrapolation to 100% of the compound used represent the value of each compound to be measured.

The host mixture used to measure the birefringence of each compound is ZLI-4792, a product of Merck Kaguea (Germany). The birefringence value of each compound to be measured is obtained from the change in the dielectric constant of the host mixture after addition of the compound to be measured and the extrapolation to 100% of the compound used. Birefringence values were measured on samples aligned in a modified Abbe refractometer. The matching agent used is a solution of lecithin available from Merck Cagea. The birefringence values were measured from values of normal and significant refractive indices, all of which were measured on the same matched sample.

Unless explicitly stated otherwise, the term "threshold voltage" generally relates to an optical threshold for contrast ₁₀ V relative to 10%.

Unless expressly stated otherwise, all concentrations herein are in weight percent and relate to the corresponding mixture or mixture component. Unless expressly stated otherwise, all physical properties are described in "Merck Liquid Crystals, Physical Properties of Liquid Crystals" status Nov. 1997, Merck KGaA, Germany, which is measured herein and applied at a temperature of 20 ° C. Δn is measured at a wavelength of 589 nm, and Δε is measured at a frequency of 1 kHz.

If necessary, the liquid crystal medium according to the invention also comprises further additives, for example stabilizers, in conventional amounts. The total amount of these additives used is 0 to 10%, preferably 0.1 to 6%, based on the total amount of the mixture. The concentration of the individual compounds used is preferably 0.1 to 3% each. If concentrations of these and similar additives indicate concentrations and concentration ranges of liquid crystal compounds in the liquid crystal medium, they are ignored.

The composition consists of many, preferably 3 to 30, particularly preferably 6 to 20, very particularly preferably 10 to 16 compounds, which are mixed by conventional methods. In general, the desired amount of components used in similar amounts is dissolved in the components that make up the main constituents, and advantageously at high temperatures. If the temperature selected is above the clearing point of the main constituent, the completion of the dissolution process is particularly easily observed. However, it is also possible to prepare liquid crystal mixtures from conventional methods, for example methods using preliminary mixtures or from multibottle systems.

By means of suitable additives, they can be modified so that the liquid crystal phase according to the invention can be used in any type of ECB VAN, IPS, GH or ASM-PA LCD display which has been disclosed so far.

The following examples are intended to illustrate but not limit the invention. In an embodiment, the melting point T (C, N) of the liquid crystal material, the transition temperature T (S, N) from the smectic (S) onto the nematic (N) and the clearing point T (N, I) are expressed in degrees Celsius. .

Unless explicitly stated otherwise, the above and the following ratios are in weight percent, and unless explicitly stated otherwise, the physical properties are at 20 ° C.

Unless otherwise specified, all above and below ratios are in weight percent, and unless explicitly stated otherwise, all physical properties are values at 20 ° C.

All indicated values for temperature herein are in degrees Celsius, and unless explicitly stated otherwise, all temperature differences are the corresponding difference in degrees Celsius.

In the present specification and the following examples, the structure of the liquid crystal compound is represented by an abbreviation (acronym), and is modified into a chemical formula according to the following Tables 2a to 2b and Tables 3a to 3f. 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. In Tables 3a to 3f the coding is self-explanatory. In Tables 2a to 2b, only acronyms for parent structures are shown. In each case, the acronyms for the parent structure are separated by linking symbols (-) and described before the code for the substituents R ¹ , R ² , L ¹ and L ³ .

The liquid crystal medium according to the invention preferably comprises at least 5, particularly preferably at least 6, very particularly preferably at least 7 compounds selected from the formulas of Tables 2a to 2b and 3a to 3f.

The liquid crystal medium according to the invention preferably comprises at least two, particularly preferably at least three, very particularly preferably at least four compounds, selected from the formulas in Tables 2a to 2b.

The liquid crystal medium according to the invention preferably comprises at least three, particularly preferably at least four, very particularly preferably at least five compounds, selected from the formulas in Tables 3a to 3f.

These compounds are preferably compounds of formula different from these tables.

Example

The following examples are intended to illustrate the invention but do not limit it. Above and below, the percentage is by weight. All temperatures are in degrees Celsius. Δn represents optical anisotropy (589 nm, 20 ° C.), Δε represents dielectric anisotropy (1 kHz, 20 ° C.), HR represents voltage retention (1 V after 5 minutes in an oven at 100 ° C.). , The threshold voltage (abbreviated as HR) V ₀ was measured at 20 ° C.

Comparative Example 1

A liquid crystalline mixture is prepared which consists only of a tricyclic compound in which one or two of the three rings are phenyl rings and the remaining rings are cyclohexyl rings, and a bicyclic compound in which one of the two rings is a phenyl ring and the remainder is a phenyl ring. The composition and physical properties of this mixture are shown in the table below.

The dispersion degree of the liquid crystal medium was measured. The birefringence values at various wavelengths are shown in the table below.

Wavelength / nm n _e n ₀ △ n 436 0.1024 509 1.5959 1.4971 0.0988 546 1.5909 1.4937 0.0972 589 1.5865 1.4911 0.0954 633 1.5890 1.4890 0.0943

Comparative Example 2

As in Comparative Example 1, only tricyclic compounds in which one or two of the three rings are phenyl rings and the remaining rings are cyclohexyl rings, and only bicyclic compounds in which one of the two rings is a phenyl ring and the rest are phenyl rings To produce a liquid crystal medium. The composition and physical properties of this mixture are shown in the table below.

The dispersion degree of the liquid crystal medium was measured. The birefringence values at various wavelengths are shown in the table below.

Wavelength / nm n _e n ₀ △ n 436 1.6049 1.5045 0.1005 509 1.5926 1.4962 0.0964 546 1.5882 1.4934 0.0948 589 1.5838 1.4903 0.0935 633 1.5803 1.4879 0.0926

Example 1

Prepare liquid crystal mixtures according to the teachings of the present invention. This liquid crystal mixture contains a high proportion of tricyclic compounds in which all three rings are phenyl rings, tricyclic compounds in which all three rings are cyclohexyl rings, and bicyclic compounds in which both rings are cyclohexyl rings. . This liquid crystal mixture does not include a tricyclic compound in which one or two of the three rings are phenyl rings and the remaining rings are cyclohexyl rings.

The clearing point and the birefringence of the mixture of this example were set to the corresponding values of the comparative example. The composition and physical properties of this mixture are shown in the table below.

The dispersion degree of the liquid crystal medium was measured. The birefringence values at various wavelengths are shown in the table below.

Wavelength / nm n _e n ₀ △ n 436 0.1118 509 1.5890 1.4887 0.1003 546 1.5836 1.4854 0.0982 589 1.5783 1.4825 0.0958 633 1.5732 1.4802 0.0930

The liquid crystal mixture of this comparative example has a dispersion degree considerably superior to that of the two comparative examples 1 and 2. This, to which the road relative birefringence dispersion of the respective compounds used (σ _{n △} / △ n _mix) are compared with each other are shown in Table.

number Example σ _{△ n} / △ n _mix One Comparative Example 1 0.26 2 Comparative Example 2 0.26 3 Example 1 0.79

According to the present invention provided a liquid crystal material having a specific birefringence dispersion degree by selecting the individual of a compound such that the relative double refraction than 0.50 degree of dispersion (σ _{n △} / △ n _mix) of the individual compounds (△ n _i).

Claims (10)

The individual compounds (△ n _i) relative birefringence dispersion degree (σ _{n △} / △ n _mix) The method of setting the degree of dispersion of the liquid crystal medium, characterized in that the selection of the individual compounds is at least 0.50 of use. a) component A consisting of a compound of low birefringence (Δn) in the range of 0.080 or less, b) optionally, component B consisting of a compound of intermediate birefringence in the range of 0.081 to 0.149, and c) component C consisting of a high birefringent compound in the range of at least 0.150 Nematic liquid crystal medium characterized in that it comprises a. The method according to claim 1 or 2, A nematic liquid crystal medium characterized by a birefringence in the range of 0.070 to 0.110. The method according to any one of claims 1 to 3, A nematic liquid crystal medium comprising component B. The method according to any one of claims 1 to 4, A nematic liquid crystal medium, characterized in that component A consists mainly of a compound selected from the group consisting of compounds of the formulas (1) and (2) Formula 1 Formula 2 Where R ¹¹ , R ¹² , R ²¹ and R ²² are each independently alkyl having 1 to 15 carbon atoms, which are optionally at least monosubstituted by halogen, wherein at least one CH is not linked directly to each other; _Two groups independently of each other in each occurrence are -O-, -S-, -CH = CH-, , -CO-, -CO-O-, -O-CO- or -O-CO-O-, wherein one of R ¹¹ and R ¹² is otherwise H or F, and R ²² is different Is F or Cl, Z ¹¹ , Z ¹² and Z ² are each independently of each other —CH ₂ —CH ₂ —, —CF ₂ —CF ₂ —, —CF ₂ —CH ₂ —, —CH ₂ —CF ₂ —, —CH═CH— , -CF = CF-, -CF = CH-, -CH = CF-, -C≡C-, -COO-, -OCO-, -CH ₂ O-, -OCH _2- , -CF ₂ O-, -OCF ₂ -,-(CH ₂ ) ₄ -or a single bond, n is 0, 1 or 2, One or two non-adjacent CH ₂ groups in the cyclohexane rings of Formula 1 and Formula 2 may be substituted by O atoms, and the phenyl ring of Formula 2 may be substituted by 1 or 2 F atoms. The method according to any one of claims 1 to 5, A nematic liquid crystal medium, characterized in that component B consists mainly of a compound selected from the group consisting of compounds of the formulas (3) and (4): Compound 3 Formula 4 Where R ³¹ , R ³² , R ⁴¹ and R ⁴² are each independently of each other as defined for R ²¹ in claim 6, Z ³¹ , Z ³² , Z ⁴¹ and Z ⁴² are each independently as defined for Z ¹¹ in claim 6. The method according to any one of claims 1 to 6, A nematic liquid crystal medium, characterized in that component C consists mainly of a compound selected from the group consisting of compounds of the formulas (5)-(7) Compound 5 Formula 6 Formula 7 Where R ⁵¹ , R ⁵² , R ⁶¹ , R ⁶² , R ⁷¹ and R ⁷² are each independently of each other as defined for R ²¹ in claim 6, Z ⁵¹ , Z ⁵² , Z ⁶¹ , Z ⁶² , Z ⁶³ , Z ⁷¹ , Z ⁷² and Z ⁷³ are each independently of each other as defined for Z ¹¹ in paragraph 6, m and o are each independently 0 or 1. An electro-optical display device comprising the liquid crystal medium according to claim 1. The method of claim 8, An electro-optic display, characterized in that it is an active matrix display. Use of a liquid crystal medium according to any one of claims 1 to 9 in an electro-optic display.