JPH0243791B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to pleochroic dyes in organic materials, in particular liquid crystal material solutions, for example for electro-optical display applications. Liquid crystal materials are well-known organic compounds that exhibit a phase known as a liquid crystal phase or mesophase with a degree of molecular alignment that is intermediate between a perfectly ordered crystalline solid state phase and a fully disordered isotropic liquid state phase. It is a substance. Electro-optical devices incorporating liquid crystal materials are well known and widely used as digital displays in applications such as watches, calculators, and digital voltmeters. These devices take advantage of optical contrast when an electric field is applied across a thin insulating film of a suitable liquid crystal material. The molecules of this material (which is in the liquid crystalline phase at the operating temperature) are rearranged by the electric field. This electric field causes a change in the optical properties of the portion of the film, such as a change in the scattering or transmittance of ambient light, upon application of the electric field. Liquid crystal materials have properties that allow the liquid crystal material molecules to force their alignment when other suitable dopants are incorporated into the liquid crystal material. This property forms the basis of so-called "guest-host" devices, such as display devices. In this display device, the host liquid crystal material and the guest material assume identical molecular configurations in the absence of an applied electric field and assume different molecular configurations when an electric field is applied to the materials. The guest substance is usually a pleochroic dye and has molecular absorption properties.
It is a dye whose properties (proper-ties) change with the orientation of the electric vector of light incident on the molecule. Effect of electric field applied to liquid crystal molecules and guest −
Due to the reorientation of the dye molecules as a result of host effects, the orientation of the dye molecules can actually be reversed, so that the off-state (without an applied electric field) and the on-state (with an applied electric field) of a liquid crystal display can be changed. ) The presence of such dyes can be exploited to increase the contrast between As discussed further below, there are several types of liquid crystal effects that can utilize the guest-host effect in electro-optical displays. These effects are determined by the type of liquid crystal material used and the arrangement of the liquid crystal material molecules in the off-state (e.g., as determined by the surface treatment of the substrate used to accommodate the film of liquid crystal material).
It changes depending on. To provide maximum contrast between the on and off states of a guest-host liquid crystal display, it is essential that the guest molecules be as close as possible to the time averaged orientation of the host molecules. However, this can only be achieved to a limited degree due to irregular thermal fluctuations. The degree to which the orientation changes from the ideal target is determined by the following formula: S = 1/2 (3cos ² θ−1) (1) (where cos ² θ is the time average term and Q is the time of the host molecule. is the instantaneous angular orientation of the molecule relative to its average orientation). Determination of the value of the order parameter S is well understood in the art: for example, DLWhite and GN
Taylor's paper “A new absorption mode reflective liquid crystal display device” (Journal of Applied Physics, Vol. 45, pp. 4718-4723)
1974) [“A new absorptive mode
reflective liquid crystal display device”by
DLWhite and GNTaylor in the Journal of
Applied Physics, 1974, 45 , 4718-4723.]. For perfect orientation, the order parameter S is 1 (ie θ is zero). Thus, the pleochroic dye used in the guest-host device should have as high an order parameter as possible (ie less than 1 but as close to 1 as possible) in the liquid crystal host. However, pleochroic dyes also have suitable chemical, photochemical and electrochemical stability, such as stability when exposed to atmospheric contaminants, electric fields (in device operation) and ultraviolet radiation. Must be. The pleochroic dye must not be ionic or have any properties capable of ionizing (otherwise the liquid crystal material would lose its insulating properties and the device could not be used). ). Also, the pleochroic dye must have sufficient solubility in the host material; the concentration of guest pleochroic dye required to achieve the desired effect is usually very small (e.g., less than a few percent dye). However, many pleochroic dyes are nevertheless unsuitable because they are substantially insoluble in liquid crystal materials. British Patent Application No. 2043097A describes the formula: Liquid crystal compositions have been proposed which can contain symmetrical dyes of the formula: where R is hydrogen or a nonionic substituent.
These dyes are proposed for use in liquid crystal materials with positive dielectric anisotropy only in the present UK patent application. In British Patent Application Publication No. 2082196, the formula: (In the formula, R represents an optionally substituted alkyl group or aryl group, and Q represents a halogen, hydroxy group, amino group, alkylamino group, dialkylamino group, arylamino group, nitro group, alkyl group, or aryl group. and y represents an integer from 0 to 4) are proposed for use in liquid crystal materials. Symmetrical dyes of formulas A and B, such as 1,5-bis(phenylthio)anthraquinone and 1,4,5,
Although 8-tetrakis(phenylthio)anthraquinone has high order parameters and adequate stability, its solubility in many liquid crystal materials is usually rather low for practical purposes; especially for use in electro-optical displays. When used, these dyes usually provide somewhat poorer contrast. According to the invention, in a first aspect, the composition for a guest-host liquid crystal device comprises a solution of a liquid crystal material and a pleochroic dye. In this case this pleochroic dye has the formula: {where n is 0 or 2; Q is an alkyl group having 1 to 20 carbon atoms; X is a hydrogen atom, OH, NZ ₁ Z ₂ (Z ₁ and Z ₂ are each a hydrogen atom, phenyl group or an alkyl group having 1 to 4 carbon atoms), or SR [R is an alkyl group having 1 to 4 carbon atoms,

An aryl group of the formula (A is a hydrogen atom, a phenyl group, or an alkyl group or alkoxy group having 1 to 4 carbon atoms),

an aryl group of the formula (B is an alkyl group having 1 to 4 carbon atoms), or

[Formula]], provided that at least two of the groups X are different -SR groups. When one of the groups in the formula is an alkyl group,
Preferably, the alkyl group has up to 20 carbon atoms, preferably up to 10 carbon atoms. When one of the radicals of the formula is an aryl or cycloalkyl radical, this radical preferably has up to 15 carbon atoms and is preferably a phenyl or cyclohexyl radical, respectively. Preferred compounds within the formula are those of the formula: (In the formula, R ¹ is an aryl group, R ² , Y ¹ to ^{Y 3} and T ¹ to T ⁴ are each independently an alkyl group, aryl group or cycloalkyl group, and X ¹ is each independently H or -NZ ₁ Z ₂ , Q, Z ₁ and
Z ₂ is as defined previously. However, R ¹ and R ² ,
Or, provided that all of the groups represented by Y ¹ to Y ³ or T ¹ to ^{T 4} are not the same. )R,
Any one of R ² , Z ₁ , Z ₂ , Y ¹ to ^{Y 3} or T ¹ to T ⁴
If any one of them is an alkyl group, it is preferred that the alkyl group have 20 or fewer carbon atoms. Any one of R, R ² , Z ₁ , Z ₂ , Y ¹ to ^{Y 3} or
When any one of T ¹ to ^{T 4} is an aryl group, it is preferred that the aryl group has up to 15 carbon atoms. Any one of R, R ² , Z ₁ , Z ₂ , Y ¹ to ^{Y 3} or
The alkyl group represented by any one of T ¹ to ^{T 4} may be branched or straight chain and is preferably a lower alkyl group and more preferably contains 1 to 4 carbon atoms. Preferably, and preferably, the cycloalkyl group is a cyclohexyl group. The aryl group represented by R, R ¹ , R ² , Z ₁ , Z ₂ , any one of Y ¹ to ^{Y 3} or any one of T ¹ to ^{T 4} is a single carbon ring such as phenyl or naphthyl. Preferably, it is an aryl group or a dicarbocyclic aryl group. The alkyl group represented by Q may be branched or straight chain and preferably contains 1 to 20 carbon atoms, more preferably a lower alkyl group. Q
The aryl group represented by is preferably a single carbocyclic aryl group such as phenyl. The alkyl group, aryl group, and cycloalkyl group represented by R, R ¹ , R ² , Z ₁ , Z ₂ , Y ¹ to ^{Y 3} , T ¹ to ^{T 4} , and Q are substituted with a nonionic group. sell. The phenyl group is preferably substituted in the para (4-) position with respect to the bond to the N or S atom or to the anthraquinone nucleus. However, in the case of the methylphenylthio substituent,
Products containing 3-methylphenylthio groups are usually 4
- more soluble than identical products containing methylphenylthio groups. Preferred substituents for alkyl groups are alkoxy, preferably _C1 - _C4 alkoxy, halogeno, preferably chloro, or monocyclic aryl groups such as aryl, preferably phenyl. Aryl groups, such as R ³ , R ⁴ and the following T ⁵ ~
Preferred substituents for T ¹⁰ and cycloalkyl groups are alkyl and alkoxy, preferably lower alkyl and lower alkoxy, more preferably C ₁ -C ₄ alkyl and alkoxy, halogeno preferably chloro, cycloalkyl preferably cyclohexyl and aryl, preferably monocyclic aryl such as phenyl. Throughout this specification, the terms "lower alkyl" and "lower alkoxy" refer to alkyl and alkoxy groups containing 1 to 10 carbon atoms. Among the yellow dyes to red dyes represented by the formula, a preferred class is one in which n is 0, two, three or four of the groups represented by X are -SR groups, and the remaining X is -NZ ₁ Z ₂ or more preferably H. A preferred class of red to blue dyes of the formula are dyes in which two X's are -SR groups and two X's are groups of Q, especially OH or _NH2 groups. In the latter class of dyes,
More preferably, n is 1 or 2 and each Q represents an alkyl group containing up to 20 carbon atoms in the position adjacent to the OH or NH ₂ group. Usually, it is preferred that at least one, preferably all -SR groups are arylthio groups,
Further, a phenylthio group is more preferable. Although the difference between the two aryl groups may lie in the aromatic nucleus, it is preferred that the difference lies in the nature and/or position of the substituents on the aromatic nucleus. Simply two -
When an SR group is present, it is preferred that the -SR group is in the 1- and 5-positions. Asymmetric di-, tri- and tetra(substituted thio)
−Anthraquinones are
They are generally more soluble in liquid crystal materials than the corresponding symmetrical di-, tri- and tetra(substituted thio)anthraquinones, such as those disclosed in GB 2043097A and GB 2082196A. In this specification,
The term "asymmetric" used in reference to poly(substituted thio)-anthraquinones indicates the presence of at least two different substituted thio groups in the molecule, whereas the term "symmetric" in the same relationship indicates the presence of at least two different substituted thio groups in the molecule. The term ``indicates that all of the substituted thio groups in the molecule are the same. However, the present invention encompasses compositions consisting of symmetric poly(substituted thio)anthraquinones and asymmetric poly(substituted thio)anthraquinones as well as mixtures of the pure asymmetric compounds themselves and mixtures thereof. Such compositions contain at least 50% by weight of asymmetric poly(substituted thio)anthraquinones, more preferably at least
Preferably it consists of 75% by weight of these asymmetric compounds. Asymmetric compounds can be obtained in pure form, ie free from the closely related symmetric compounds, by chromatographic separation methods, in particular preparative chromatography or high-pressure liquid chromatography. The main advantage of pure asymmetric compounds over compositions containing mixtures of asymmetric and symmetric compounds is the relatively greater solubility of the asymmetric compounds, which is important in obtaining good contrast in liquid crystal displays, as mentioned above. . However, solubility is one factor among the factors that influence achieving good contrast in liquid crystal displays; another factor is the extinction coefficient of the dye in the liquid crystal material. One useful indicator of a dye's ability to provide good contrast is the product of the molar extinction coefficient and solubility (in moles/units). Liquid crystal composition solutions of dyes for electrical display applications should preferably have a value of this product of at least 500 ^cm-1 , more preferably at least 750 ^cm-1 . Since the molar extinction coefficient of a dye does not vary significantly between liquid crystal materials, calculation of the preferred minimum solubility of a particular dye in any liquid crystal material to obtain good contrast requires
Any preferred product value can be used. Thus, for dyes with a molar extinction coefficient of 11000 cm ² ·moles ^-1 the solubility is preferably at least 4.5 x 10 ^-2 mol/, more preferably at least
It should be 6.8×10 ^-2 mol/. In practice, since the yellow dye of Example 1 has this value for extinction coefficient and has a molecular weight of 480, the solubility (% by weight) of this dye is preferably at least 2.2%, more preferably at least 3.3. %; the actual solubility of this dye in liquid crystal material E43 (see Example 1) is 8.6%. For dyes with a molar extinction coefficient of 16000 cm ² ·moles ^-1 the solubility should preferably be at least 3.1 x 10 ^-2 mol/, more preferably at least 4.6 x 10 ^-2 mol/. In practice, since the red dye of Example 1 has this value for extinction coefficient and has a molecular weight of 650, the solubility (% by weight) of this dye is preferably at least 2%, more preferably at least 3%.
%; the actual solubility of this dye in liquid crystal material E43 is approximately 15%. molar extinction coefficient
For dyes with 20000 cm ² moles ^-1 , the solubility is preferably at least 2.5 x 10 ^-2 mol/,
More preferably, it is at least 3.8×10 ⁻² mol/. In practice, since the violet dye of Example 21 has this value for extinction coefficient and has a molecular weight of 590, the solubility is preferably at least 1.5%,
More preferably it should be at least 2.2%; the actual solubility of this dye in liquid crystal material E43 is
It is 4.6%. Dyes manufactured for liquid crystal displays are preferably free of inorganic substances and other ionizable substances or products that are sensitive to radiation and decompose within the display during operation, which would interfere with the operation of the display. should be as pure as possible. The dye should also preferably be free of non-pleochroic or inferior pleochroic substances such as starting materials, intermediates and by-products. These items do not contribute to the perceived contrast of the display. To obtain the dye in pure form, i.e. substantially free of interfering or harmful substances, the dye is usually subjected to repeated recrystallization from organic solvents such as chloroform and/or chromatographic separation methods. It is desirable to apply Compounds of the formula have extremely high stability in liquid crystal materials and high order parameters, usually above 0.7.
Di(substituted thio)anthraquinones are of particular interest because stable yellow dyes with high order parameters and good solubility have not been available to date.
If the material according to the first aspect is for an application such as in an electro-optical display, the addition of dyes to the liquid crystal material tends to increase the viscosity of the liquid crystal material and thus increase the response time of the display. There is. It is thus desirable to use as little dye as possible (sufficient to provide adequate electro-optic contrast). In this respect, many of the dyes of the formula have very high extinction coefficients and therefore only small amounts, usually less than 7%, are required in the liquid crystal material, so these dyes are of particular importance. The dyes of the formula have been found to exhibit appropriate order parameters and solubility in a variety of liquid crystal materials comprising materials of both positive and negative dielectric anisotropy. In particular, suitable liquid crystal host materials consist of: a clearing above 150°C, preferably such as the materials E ₇ and E ₄₃ marketed by BDH Chemicals Ltd. (Broom Street, Paul, Dorset, UK); one or more compounds (e.g. cyano-P-
(composition is shown below). b Preferably, a mixture of a few percent of one or more high clearing point compounds, such as the substance ZLI1132, mixed with a cyanophenylcyclohexane compound; c Preferably, a few percent of a high clearing point compound, such as the substance ZLI1132; phenylpyrimidine phenyl compounds, such as the substance ROTN30;
A mixture of at least one cyanobiphenyl and at least one cyanophenylpyrimidine compound; d For example, esters containing bicyclo(2,2,2)octane and a benzene ring (which may contain a fluorine substituent) a mixture of. 4-n-alkyl- or alkoxy-forming a 60% to 80% by weight mixture with one or more substances having a high clearing point (nematic to isotropic liquid transition temperature above 100°C) 4-
Cyanobiphenyl and 1-(4'-cyanophenyl)-
A liquid crystal material containing a mixture of approximately equal weight proportions of 4-n-alkyl-cyclohexane has been found to be a particularly suitable host liquid crystal material. Virtually any other liquid crystal material incorporating one or more compounds selected from the following known groups can be used as the host material: however,

[Formula] is trans-1,4-substituted In the case of a chlorohexane ring,

[Formula] is a 1,4-substituted bicyclo(2,2,2)octane ring, and X ₁ is a 1,4-phenylene group

[Formula] or 4,4'biphenylyl group

[Formula] or 2,6 natiflu group

[Formula]; and when Y ¹ is CN, R ₁ or OR ¹ , Y is CN, or R ¹ ,
or OR ¹ or CO.O-X ₁ -Y ¹ ; the definition of R ¹ is the same as the definition of R. the dye/liquid crystal solution contains at least 0.5% by weight of dye;
Preferably it contains about 0.75 to 10% by weight dye, preferably 1 to 5% by weight dye. The concentration of the dye is preferably not too low in order to provide a display with as high a contrast as possible, and preferably not too high in order to provide a display with a slow electro-optic response, but within the preferred range. The exact amount of dye is not critical. A solution of the dye and the liquid crystal material is prepared by simply mixing the dye and the liquid crystal material together, then heating the mixture with stirring at about 80° C. for about 10 minutes, and then allowing the mixture to cool. , can be made in the usual way. Pleochroic dyes of the above formula may be mixed with other dyes, which may or may not be dyes of the formula, in order to improve the spectral absorption properties of the dye when dissolved in a liquid crystal material. . For example, if the dye of the formula is yellow, it may be mixed with a blue dye and a red dye. The relative proportions of dyes mixed together are determined by the desired spectral response.
This spectral response, as determined by the extinction coefficients of the component dye compounds, is an absorption curve that is as flat as possible throughout the visible spectrum.
Additionally, dye mixtures may be used with liquid crystal materials as described above or as described below. According to the invention, in a second aspect, a liquid crystal electro-optic display comprises two electrically insulated substrates, at least one of which is optically transparent; It consists of an electrode on the surface and a film of dielectric material contained between the electrode and the substrate, where the dielectric material is a material according to the first aspect of the invention as described above. The material liquid crystal/dye solution according to the first aspect of the invention can be used in any known electro-optic display as defined in the second aspect.
An example, although this is commonplace for experts in the field of liquid crystals, is a known device that operates by the following effects: a Torsional nematic effect In this case, positive dielectric anisotropy The nematic liquid crystal material film having the nematic liquid crystal material is in an off state. In this state, the liquid crystal molecules (long axes) are either at the inner surface of the device's substrates (usually parallel to each other) or at a small angle to this plane, and prior to assembly the substrate surfaces are e.g. The orientation of the surfaces caused by the unidirectional rubbing process causes them to undergo a helical twist of approximately π/2, oriented from one substrate to the other. This is a twisted “homogeneous tissue” (homogeneous tissue).
texture). Applying an electric field between the electrodes on the inner surface of each substrate to provide an on state causes the liquid crystal molecules to rearrange themselves virtually perpendicular to the inner surface of the substrate in a "homeotropic texture". . Changes in the optical activity (optical power) of this film occur between the on and off states due to molecular rearrangement, and the optical effect observed can be achieved by using a linear polarizer adjacent to one side of the substrate. and polychromatic dyes dissolved in the liquid crystal material. This polarizer has a polarization axis parallel to the direction of the liquid crystal molecules on the inner surface of the adjacent substrate (or, more precisely, parallel to the average axis of the projection of the molecules on the inner surface). The guest-host effect causes the dye to appear relatively dark or colored in the off-state, while appearing bright or weakly colored in the on-state. b Fredericks effect in negative nematic liquid crystals In this case, the nematic liquid crystal material with negative dielectric anisotropy assumes the off state. In this state, the liquid crystal molecules are parallel due to surface treatment on the inner surfaces of the substrates prior to assembly.)
It exists perpendicularly to the inner surface of the substrate (ie, in a homeotropic state). A single polarizer is placed adjacent one substrate with a transmission axis perpendicular to the inner surface. When an electric field is applied between the electrodes on the inner surface of each substrate to provide an on state, rearrangement of the liquid crystal molecules occurs so that they become parallel to the inner surface of the substrate (ie, a homogeneous structure). Incorporation of pleochroic dyes into the liquid crystal material ensures that the off-state appears relatively bright or lightly colored, while the on-state appears dark or strongly colored. The observed effect is enhanced by the presence of Bikoko. c Fredericks Effect in Positive Nematic Liquid Crystals In this case, the nematic liquid crystal material with positive dielectric anisotropy assumes the off state. In this state, due to the treatment of the inner surface of the substrate prior to assembly, the liquid crystal molecules exist approximately in parallel;
in the plane of the inner surface of the substrate (ie, homogeneous structure). A single polarizer is placed adjacent one substrate with a transmission axis parallel to the inner surface of the substrate. When an electric field is applied between the electrodes on the inner surface of each substrate to provide an on state, rearrangement of the liquid crystal molecules occurs, resulting in a homeotropic structure perpendicular to the inner surface of the substrates. Incorporation of pleochroic dyes into the liquid crystal material ensures that the off-state appears relatively dark or strongly colored, while the on-state appears colorless or weakly colored, as in the torsional nematic effect described above. do. The observed effect is enhanced by the presence of a polarizer. d Phase change effect (negative contrast type) In this case, the cholesteric liquid crystal material with positive dielectric anisotropy and long molecular helical pitch, typically 2 μm, assumes the off state. In this case, the liquid crystal molecules are in an irregular helical state or "focal conic texture". Applying an electric field between the electrodes on the inner surface of each substrate to provide an on-state causes the liquid crystal molecules to rearrange so that they become perpendicular to the inner surface of the substrate (i.e., like a positive nematic liquid crystal in the Fredricks effect). , homeotropic tissue). Incorporation of pleochroic dyes into liquid crystal materials results in an off state that appears relatively dark or strongly colored;
A colorless or weakly colored on state is obtained. e Phase change effect (positive contrast type) In this case, the cholesteric liquid crystal material with negative dielectric anisotropy and long molecular helical pitch assumes the on state. In this case, the liquid crystal molecules exist perpendicularly to the inner surface of the substrate, that is, they are in a homeotropic state. When an electric field is applied between the electrodes on the inner surface of each substrate, the molecules are rearranged so that they are in a helical arrangement within the plane of the inner surface of the substrate, that is, a twisted homogeneous structure. Incorporation of pleochroic dyes into liquid crystal materials provides a relatively colorless or weakly colored off state and a relatively dark or strongly colored on state. f Fredericks Effect in Smectic Liquid Crystals In this case, a Smectic A liquid crystal material of positive dielectric anisotropy with a dielectric relaxation frequency fc below about 10 KHz (i.e. the material has a negative dielectric anisotropy above this frequency) ) is in the off state. In this case, the liquid crystal molecules are affected by the Fredericks effect
As shown in (c), the molecules exist approximately parallel to the inner surface of the substrate together with the molecules on the two parallel inner surfaces. When an electric field is applied at a frequency below fc to provide an on-state, the liquid crystal molecules are rearranged and become perpendicular to the inner surface of the substrate, resulting in a homeotropic structure. The on state is maintained when the electric field is removed. On-state clearing may be achieved by application of a high frequency electric field, ie, a frequency greater than fc. If the molecular alignments on the inner surfaces of the two substrates are parallel in the off-state, a single polarizer is used, as is the case with the Fredericks effect (c) described above. Mixing pleochroic dyes into liquid crystal materials provides a relatively dark or strongly colored off state and a bright or weakly colored on state. The use of the substances defined in the first aspect of the invention above (as defined in the second aspect) is
Not limited to electro-optical displays. This material may be used in virtually any known use of dyed liquid crystal materials. Such “non-electro-optical”
An example of an application is a thermally addressed display. In this display, the material is selectively heated to produce local changes in the molecular structure of the material, e.g. with a laser (e.g. He/Ne).
The beam imparts symbols or letters into the smectic or cholesteric material. The dye enhances the contrast between different areas of the display, ie, areas that are selectively heated and areas that are not heated. Returning to the dyes of the formula used in the material according to the first embodiment, a preferred class of yellow dyes containing two different -SR groups is of the general formula: (In the formula, R ¹ is an aryl group, and R ² is any group represented by R, provided that R ¹
and R ² are not the same). Groups that can be represented by R ² include 1 such as the above-mentioned substituents.
alkyl capable of carrying more than one nonionic substituent;
Consists of aryl and cycloalkyl groups. When R ² is an aryl group, it must be different from the aryl group ^represented by R ¹ . This difference is due to the nature of the aromatic nuclei or substituents on them and/or
or may occur at any position. Useful compounds of this type have the formula: (In the formula, R ³ represents hydrogen or a nonionic substituent,
R ⁴ represents a nonionic substituent, and R ³ consists of a compound (different from R ⁴ in structure and/or position on the phenyl group). formula: (wherein R ³ and R ⁴ have the meanings indicated above,
Particular reference is made to compounds in which R ³ differs in structure from R ⁴ ). Particularly useful compounds of this type are those in which R ³ is hydrogen and R ⁴ is a lower alkyl group,
In particular, it consists of compounds which are t-butyl groups. The dye of formula contains 1 equivalent of thiol R ¹ SH and 1
It can be prepared by reacting an equivalent of thiol R ² SH with one equivalent of 1,5-dihalogenanthraquinone. This reaction is conveniently carried out in a solvent such as dimethylformamide in the presence of an acid binder such as potassium carbonate. The product of this reaction has the formula: as well as is a statistical mixture containing a compound of formula as the main component along with a symmetrical compound of . Compounds of formula are prepared by reacting a 1-halogeno-5-nitroanthraquinone with one equivalent of a first thiol (R ¹ SH) under mild conditions and then converting this product into a second thiol (R ² SH) at a relatively high temperature. SH) No. 1
It can be produced in pure form by reacting with equivalents. As mentioned above, 1,5-bis(phenylthio)
Known symmetric dyes with formula A, such as anthraquinones, have a rather low solubility in liquid crystal materials. Mixtures of two or more compounds of formula A also have low solubility in liquid crystal materials. Surprisingly, the asymmetric dyes of formula A have significantly higher solubility in liquid crystal materials than the symmetric dyes of formula A. Pure asymmetric dyes have higher solubility than the asymmetric products mentioned above which contain symmetric compounds of formula and as impurities. However, these mixtures of asymmetric and symmetric dyes exhibit significantly higher solubility than pure symmetric dyes, giving them commercial utility. A preferred class of red dyes containing four -SR groups, no more than three of which are the same, has the general formula: (In the formula, T ¹ , T ² , T ³ and T ⁴ are each the above-mentioned R
(3 or less groups are the same). Particularly useful compounds of formula XI are those in which each of T ¹ , T ² , T ³ , and T ⁴ is an aryl group, where up to three aryl groups are the same. Differences among these groups may occur in the nature and/or position of the aromatic nuclei or substituents on those nuclei. Useful compounds of this type have the formula: (In the formula, T ⁵ , T ⁶ , T ⁷ , and T ⁸ are as described above,
each independently represents hydrogen or a nonionic substituent, and at least one of T ⁵ , T ⁶ , T ⁷ and T ⁸ differs from the others in either structure or position). formula: Particular mention is made of compounds in which T ⁹ represents hydrogen or a nonionic substituent, T ¹⁰ represents a nonionic substituent, and T ⁹ and T ¹⁰ are not the same.
Particularly useful compounds of this type consist of compounds in which T ⁹ is hydrogen and T ¹⁰ is a lower alkyl group, especially a t-butyl group. ^The dye ^of formula
It may be produced by reacting with 1 equivalent of each of T ³ SH and T ⁴ SH; in this case, T ¹ ,
Three or less of T ² , T ³ and T ⁴ are the same. The reaction is conveniently carried out in a solvent such as dimethylformamide in the presence of an acid binder such as potassium carbonate. In this way, a compound of the formula is a tetrahalogenoanthraquinone and a compound of the formula: Thiol 2 equivalents and formula: 2 equivalents of thiol. The products from these reactions are statistical mixtures consisting mainly of compounds of formula XI, with also relatively small amounts of compounds in which T ¹ , T ² , T ³ and T ⁴ are the same. As mentioned above, symmetrical dyes of Formula B have lower solubility in liquid crystal materials than is normally desired in practice. Surprisingly, asymmetric dyes of formula XI have significantly higher solubility in liquid crystal materials than symmetric dyes of formula. A preferred group of orange dyes of formula 2
Two differently substituted thiols and trichloroanthraquinone may be reacted in the presence of an acid binding agent to yield a composition that is predominantly an asymmetric compound and contains a relatively small amount of a symmetric compound. In some cases,
One thiol is reacted with a nitrodichloroanthraquinone under mild conditions to yield a di-chloroanthraquinone, and a second thiol is reacted with this dichloroanthraquinone intermediate to form a single unsymmetrical tri(substituted thiol). ) Anthraquinones and only small amounts of symmetrical products may be obtained. Prior to _{the -SR} group _, such _a Preferably, a group is introduced. Examples of other suitable compounds of the formula are: 1-phenylthio-5-(naphth-2-ylthio)anthraquinone, 1-phenylthio-5-
(dodecylthio)-anthraquinone, 1-phenylthio-5-(4-nonylphenylthio)anthraquinone, 1-(phenylthio)-4,5,8-tri(cyclohexylthio)anthraquinone, 1-(phenylthio)-4,5 , 8-tri(4-phenyl-phenylthio)anthraquinone, 1-(phenylthio)-4,5,8-tri(4-t-butylphenylthio)-anthraquinone, 1-phenylthio-4-anilino-5- (4-methylphenylthio)anthraquinone, 1-phenylthio-4,
8-di(butylamino)-5-butylthio-anthraquinone and 1-phenylthio-5-cyclopentylthioanthraquinone. Examples of the preparation and properties of dyes of the formula: In these examples, all parts and percentages listed are by weight unless indicated otherwise. The letters 'AQ' are also used to represent anthraquinone and 'MP' is used to indicate the melting point of the product. Example 1 Dimethylformamide (100ml), soda carbonate (12g), thiophenol (10.4ml) and 4-t-
1,4,5,8-tetrachloroanthraquinone (12 g) was added to a stirred mixture of butylphenylthiol (14.8 ml). This reaction mixture was heated to 130-140℃.
and stirred at this temperature for 5 hours. After cooling overnight, filter the reaction product and mix the filter cake several times with 50:50 ethanol and 2N sodium hydroxide solution.
Wash with the mixture. The washed product is then washed with very dilute acetic acid, washed with water until acid free, dried in vacuo at 50°C, dissolved in a minimum amount of boiling toluene, filtered and reconstituted with methanol. It was precipitated, filtered off, washed with methanol and dried at 50°C. The product contained the substituted anthraquinones listed below. Table 1 Component Weight % Tetrakis-(phenylthio)AQ 1% Tris-(phenylthio)-t-butylphenylthio-AQ 19% Bis-(phenylthio)-bis-(t-butylphenylthio)AQ 65% Tris -(t-butylphenylthio)-phenylthio-AQ 11% Tetrakis-(t-butylphenylthio)AQ
The solubility of the 4% product was determined in liquid crystal material E43, marketed by BDH Chemicals, Plame Street, Paul, Dorset, UK. E43 contains the following compounds: The solubility of the product in E43 at 20°C is 14.7%. For comparison, pure 1,
The solubility of 4,5,8-tetrakis-(phenylthio)anthraquinone and that of pure 1,4,5,8-tetrakis-(4-t-butylphenylthio)anthraquinone are <1% and 1.8%, respectively.
It is. Example 2 4-t-Butylphenylthiol was added to an equivalent amount of p-
The procedure of Example 1 was repeated except for substituting methylphenylthiol. Example 3 Thiophenol (2.97g), p-phenylphenylthiol (4.38g) and potassium carbonate (3.73g)
g) in 23 ml of dimethylformamide (DMF).
Stir at 120°C for 1 hour and cool to ambient temperature.
1,4,5,8-tetrachloroanthraquinone (3.46g) was added and the mixture was maintained at 120°C for 4 hours, then cooled to ambient temperature. After adding 20 ml of ethanol, the mixture is processed according to the following procedure.
After filtering and washing with a 50:50 mixture of 2NNaOH and ethanol, the crude product was slurried in 30 ml of the same solvent mixture, stirred for 30 min, filtered and washed successively with caustic soda/ethanol solvent and water. , 80
Dry at °C. The treated product was boiled in 30 ml of chloroform, filtered cold and the liquid was diluted with petroleum ether (100 ml).
~120) was added dropwise into 250ml. After stirring for 1 hour,
The precipitate was filtered, washed with 40-60% petroleum ether and dried at 80°C. The product contained approximately 90% unsymmetrical tetra(substituted thio)anthraquinone, which had both phenylthio and phenylphenylthio groups. The remainder was a symmetrical tetra(substituted thio)anthraquinone with either a phenylthio group or a phenylphenylthio group. Example 4 1.98 g of thiophenol, 2.07 g of cyclohexylthiol and 2.02 g of KOH in 30 ml of ethanol
Stir under reflux for an hour and cool to ambient temperature. 1,
4,5,8-Tetrachloro-AQ (2.31 g) was added and the mixture was stirred at reflux for 16 hours, then cooled to room temperature and processed according to the procedure of Example 3. Dissolve the crude solid in 100 ml of hot chloroform,
It was sieved and soaked in 300 ml of methanol for a period of 5 minutes. The soaked mass was stirred for 30 minutes, the solid filtered off, washed with methanol and dried at 80° C. (yield 2.8 g). The main component of the product was asymmetric tetra(substituted thio) AQs having both cyclohexylthio and phenylthio groups. Example 5 Dimethylformamide (100ml), potassium carbonate (8.0g), thiophenol (thiol 1: 7.0ml)
and 1,5-dichloroanthraquinone (12 g) was added to a stirred mixture of 4-t-butylphenylthiol (thiol 2: 8.0 ml). reaction mixture
It was heated to 130-140°C and held at this temperature for 5 hours. After cooling overnight, filter the reaction product and remove the overcake from ethanol and 2N sodium hydroxide solution.
Washed several times with a 50:50 mixture. The washed product is then washed with very dilute acetic acid, washed free of acid with water, dried in vacuo at 50°C, dissolved in a minimum amount of boiling toluene, filtered and added with methanol. Precipitate again, separate, wash with methanol and incubate at 50°C.
Dry with. The product is 1-(4-t-butylphenylthio)-
Contains 55% 5-phenylthioanthraquinone,
The remainder were two symmetrical 1,5-substituted anthraquinones. The following four similar products were prepared by the method of Example 5, substituting equivalent amounts of the appropriate substituted thiols for 4-t-butylphenylthiol and thiophenol used in Example 5. Example 6 Thiol 1: Thiophenol thiol 2: 3-Methylphenylthiol Main component of the product: 1-phenylthio-5(3-methylphenylthio)AQ (“% in composition” refers to product composition) This abbreviation is also used in the examples below.) % in composition: 48% Example 7 Thiol 1:3-methylphenylthiol Thiol 2:4- Main component of t-butylphenylthiol product: 1-(3-methylphenylthio)-5(4
-t-butylphenylthio)AQ % in composition: 64% Example 8 Thiol 1:3-methylphenylthiolthiol 2:4-methylphenylthiol Main component of product: 1-(3-methylphenylthiol) Nilthio)-5(4
-methylphenylthio)AQ Example 9 Thiol 1: Thiophenolthiol 2: 4-Methylphenylthiol Main component of product: 1-phenylthio-5(4-methylphenylthio)AQ Example 10 4-t -Butylphenylthiol (thiol 2) 73.7g, potassium hydroxide 25g and ethanol
640ml of the mixture was heated at reflux for 1 hour and cooled to room temperature. Add 1-phenylthio to this mixture.
86.5 g of 5-chloroanthraquinone was added over a period of 5 minutes and the mixture was heated to reflux and heated to 16
It was held at reflux temperature for an hour. At the end of this reaction period, the mixture was cooled to room temperature and the solid product was separated and washed with 200 ml of 50% 2N NaOH/ethanol. Further, the crude product was slurried in 200 ml of the same mixed solvent, stirred for 30 minutes, filtered again,
It was washed successively with 100 ml of 50% 2NNaOH/ethanol and 100 ml of water and dried at 80°C. The product was extracted with a 15:1 mixture of 100-120 petroleum ether and chloroform at reflux for 48 hours, after which the chloroform was distilled off. The slurry in petroleum ether was cooled and after 24 hours filtered at room temperature, washed with 100 ml of 40-60 petroleum ether and heated to 80 °C.
It was dried. After repeated recrystallization from methanol, ca.
The product containing % 1-phenylthio-5-(4-t-butylphenylthio)anthraquinone is
It had a melting point of 241°C. The 1-phenylthio-5-chloro-anthraquinone used above was prepared from a mixture of 78 g of thiophenol (thiol 1), 32 g of potassium carbonate and 125 ml of dimethylformamide (previously refluxed at 120° C. for 2 hours and cooled to room temperature). 1-nitro-5-
72.5g of chloroanthraquinone and 500ml of ethanol
was added and heated at 40°C for 16 hours. After cooling and standing for 48 hours, the solid product was filtered, washed with 1 part of 40% ethanol, slurried again in 500 ml of the same solvent, stirred for 30 minutes,
It was washed successively with 200 ml of 40% ethanol water and 1 ml of water. The product was reslurried in 500 ml of water for 300 minutes, filtered, washed with water and finally with 100 ml of ethanol and dried at 80°C. Table 2 shows that in the liquid crystal material E43 described in Example 1,
The solubility of the dyes of Examples 5 and 10 is compared with the solubility of the corresponding symmetrical dye at 20°C.

[Table] From the solubility data listed in Table 2, it can be seen that the asymmetric products alone or their mixtures with their symmetric counterparts exhibit significantly higher solubility in liquid crystal media than either the symmetric products or their mixtures. becomes clear. This relatively high solubility is both completely unexpected and of considerable commercial importance in view of the demand for practical liquid crystal displays based on the guest-host effect. The following five similar compositions were prepared in a manner analogous to that of Example 10, substituting equivalent amounts of appropriately substituted thiols for the thiols used in Example 10. Example 11 Thiol 1: Thiophenolthiol 2: 3-methylphenylthiol Main product: 1-phenylthio-5(3-methylphenylthio)AQ % in composition: 81% MP: 227°C Example 12 Thiol 1: Thiophenolthiol 2: 4-methylphenylthiol Main product: 1-phenylthio-5(4-methylphenylthio) AQ % in composition: 83% MP: 269℃ Example 13 Thiol 1: Thiophenol Thiol 2: n-butylthiol Main product: 1-phenylthio-5 (n-butylthio) AQ % in composition: 98% MP: 163°C Example 14 Thiol 1: Thiophenolthiol 2: 4-phenyl phenyl Thiol Main product: 1-phenylthio-5(4-phenylphenylthio)AQ % in composition: 91% Example 15 Thiol 1: Thiophenolthiol 2: Cyclohexylthiol Main product: 1-phenylthio-5- Cyclohexylthio-AQ Example 16 A 20 ml solution of 1.98 g of thiophenol, 2.99 g of 4-t-butylphenylthiol and 2.48 g of potassium carbonate in dimethylformamide was heated to 115°C.
Stirred at this temperature for 1 hour. In this solution, add 1,5
3.28 g of -dinitro-4,8-diamino-AQ was added and the mixture was stirred at 115°C for 8 hours. It was then cooled to room temperature, filtered, washed successively with DMF, water and ethanol, and dried to yield 1.7 g of crude product. The crude product was purified by sieving in hot chloroform and, after cooling, passing through a chromatographic column packed with silica. The column was eluted with chloroform and the main blue band was collected and evaporated to dryness. The dry material was washed with 20 ml of methanol to form a slurry, filtered, washed with methanol and dried at 80°C.
0.2 g of a purified composition containing 63% of -t-butyl-phenylthio)-4,8-diamino-AQ was obtained. 1,5-diamino-AQ-bis-N,N-
1,5-dinitro-4,8-diamino-AQ was prepared from dimethylformidinium chloride. Furthermore, 1,5-diamino-AQ-bis-N,N-dimethyl-formidinium chloride was produced from 1,5-diamino-AQ by the method of Example 2 of German Patent Specification No. 1132931. Example 17 Thiophenol (1.98g), 3-methylphenylthiol (2.33g) and potassium carbonate (2.02g)
g) was stirred in 15 ml DMF at 115° C. for 1 hour and cooled to room temperature. In this mixture, 1,5-dibromo-
4,8 di(methylamino)AQ was added over 5 minutes and the mixture was reheated to 120°C and at this temperature
Stirred for 16 hours. Cool to ambient temperature and ethanol
After adding 25 ml, the crude material was treated as in Example 3 to give a yield of 4.35 g. The treated material was dissolved in chloroform and passed through a silica-packed chromatographic column eluting with chloroform to collect the main red band. After evaporating the chloroform, it was washed with methanol and dried at 80°C. The yield of purified material was 4.09 g;
48.9% 1-phenylthio-5(4-t-butylphenylthio)-4,8-di(methylamino)
It contained AQ. The remainder was two types of symmetric di(substituted thio)AQ. Example 18 A mixture of 1.24 g thiophenol, 1.87 g 4-t-butylphenylthiol and 1.56 g potassium carbonate in 10 ml DMF was stirred at 120° C. for 1 hour and cooled to ambient temperature. 1-nitro-5, in the cooled mixture
Add 1.73 g of 8-dichloro-4-anilino-AQ,
The mixture was stirred at 120°C for 5 hours. After cooling to ambient temperature and adding 27 ml of ethanol and 40 ml of water, the solid was filtered, washed with water and ethanol, and dried to yield 3.55 g of crude material. The crude material was dissolved in chloroform and silica
The main orange band was collected by passing through a packed chromatographic column and eluting with chloroform. After evaporating the solvent, 30 ml of methanol was added and the solid material was filtered, washed with methanol and dried at 50° C. (yield 2.95 g). 65% refined substances
of asymmetric tri(substituted thio)AQ, and the remainder were mainly two types of symmetric tri(substituted thio)AQ. 1-nitro-4-anilino-5,8-dichloro
AQ was prepared according to the following method: 7.83 g of aniline and 75 g of 2-ethoxyethanol.
ml of 1,4,5-trichloro-8-nitroanthraquinone was heated at 120°C for 18 hours. The product was filtered, washed with ethanol, slurried in 50 ml of ethanol, and filtered again. This was then stirred in 50ml of 2NHcl, filtered,
The acid was removed by washing with water and dried at 80°C. The final step of purification was to dissolve the dry material in 50 ml of chloroform.
Consisting of stirring for 20 minutes, filtering, washing with chloroform and drying at 80°C, purity 90.5%.
(determined by HPLC) product (mp216~
217°C) 5.9g was obtained. Example 19 A mixture of 1.48 g thiophenol, 2.24 g 4-t-butylphenylthiol and 1.5 g KOH was refluxed in 15 ml ethanol for 1 hour and cooled to ambient temperature. To this cooled mixture was added 1.5 g of 1,4,5-trichloro-AQ, and the mixture was refluxed for 16 hours. After cooling to ambient temperature, the mixture was processed as described in Example 3. 2.3 g of treated material contains 62% of unsymmetrical tri(substituted thio)AQs, namely di(phenylthio)-(4-t-butylphenylthio)AQ and phenylthiodi(4-t-butylphenylthio).
AQ, and the remainder were mainly two symmetrical tri(substituted thio)anthraquinones. Example 20 0.127 g of thiophenol and 15 ml of ethanol
A mixture of 0.065 g KOH was refluxed for 1 hour and cooled to ambient temperature. 1,5-di(4-
t-Butylphenylthio)-4-chloro-AQ0.66
g was added and the mixture was refluxed for 16 hours before being cooled to ambient temperature. After processing as described in Example 3, the yield of dry material was 0.6 g. This substance is 1,
It contained 78% of 5-di(4-t-butylphenylthio)-4-phenylthio-AQ. 1,5-di(4-t-butylphenylthio)-
4-Chloro-AQ was prepared as follows: A mixture of 2.98 4-tert-butylphenylthiol and 0.51 g KOH in 10 ml ethanol was refluxed for 1 hour and cooled to ambient temperature. To this, 1, 4, 5
-Add 1.56g of trichloro-AQ and heat the mixture at 40°C.
After stirring for 16 hours at room temperature, it was cooled to ambient temperature. After treating the crude material as described in Example 3, it was dissolved in 100 ml of 60-80 petroleum ether and
It was further purified by sieving and passing through a silica-packed chromatographic column, eluting with the same solvent and collecting the intermediate orange band. After evaporating the solvent, washing with methanol, and drying,
The yield of purified material was 0.9g. Example 21 A mixture of 1.1 ml (0.01 mol) of thiophenol and 5.8 g (0.01 mol) of 1,5-dihydroxy-2,6-dinonyl-4,8-dinitro-AQ in 50 ml of pyridine is stirred at room temperature for 30 minutes, It was then immersed in 100ml of water. Concentrated hydrochloric acid (75 ml) was added and the precipitated solid was filtered, washed with water and dried to obtain 6 g of crude material. A portion (3 g) of this was recrystallized from 100-120 petroleum ether to produce the intermediate 1,5-dihydroxy-2,6-dinonyl-4-nitro-8-phenylthio-anthraquinone (the structure was confirmed by mass spectrometry). ) 1.3g was obtained. 0.65 g of the above intermediate and 4-t- in 10 ml of pyridine.
90-95% of a mixture of 0.2g of butylphenylthiol
Stirred at °C for 16 hours, then soaked in 150 ml of dilute Hc.
The precipitated solid was filtered, washed successively with water and ethanol, and dried. This was then recrystallized from 40-60 petroleum ether and the structure was determined by mass spectrometry to be mainly 1,5-dihydroxy-2,6-dinonyl-4(4-t-butylphenylthio)-8-phenylthio-AQ. 0.1g of product consisting of
I got it. 1,5-dihydroxy-2,6-dinonyl-
4,8-dinitro-AQ is a
1,5 according to the method disclosed in No. 2038809A
It was produced by reacting -dihydroxy-AQ with nonanal and nitrating the di-nonyl derivative. Example 22 1,8-dihydroxy-2,7-didodecyl-4,5-dinitro-AQ 6.6 g, thiophenol
A mixture of 1.1 g and 100 ml of pyridine was prepared at ambient temperature.
Stir mixed for an hour and then soaked in 200 ml of water. The precipitated solid was filtered, washed successively with water and methanol, and dried to obtain 4.5 g of crude material. 100−120
After recrystallization from petroleum ether, the product is 1,8
-dihydroxy-2,7-didodecyl-4-phenylthio-5-nitro-AQ (4.15 g; structure confirmed by mass spectrometry). A portion of this intermediate product (3.7 g) was added to 4-t-
65 of butylphenylthiol 0.83g and KOH 0.3g
℃ added to 50 ml of isopropanol solution. After heating the mixture at reflux temperature (83°C) for 3 hours, it was cooled to ambient temperature, filtered, washed successively with isopropanol and methanol, dried and
-120 Recrystallized from petroleum ether. The product (2.75 g) was essentially 1,8-dihydroxy-
2.7-Didodecyl-4-phenylthio-5-(4-
It was t-butylphenylthio)AQ. 1,8-dihydroxy-2,7-didodecyl-4,5-dinitro-AQ is disclosed in British Patent Publication No.
1,8 according to the method disclosed in No. 2038809A
It was produced by reacting -dihydroxy-AQ with dodecanal and nitrating the di-dodecyl derivative. Example 23 A sample of the product prepared according to the method described in Example 1 was tested at a flow rate of 2 ml/min and at ambient temperature (20
Partisil 5U (250×
4.6 mm) through a high-pressure liquid chromatography column. Detection uses an ultraviolet source (254 nm),
Samples corresponding to all peaks in the chromatogram were collected. The collected fractions are identified in Table 3.

[Table] In Table 3, Y represents 4-t-butylphenylthio-, and X represents phenylthio-. Fractions 3 and 3a had identical retention periods and were separated by differences in solubility in the eluent. The following compositions were prepared in a manner similar to that of Example 10, substituting equivalent amounts of appropriately substituted thiols for the thiols used in Example 10. Example 24 Thiol 1: Thiophenolthiol 2: 4-methoxyphenylthiol Main product: 1-phenylthio-5-(4-methoxyphenylthio)AQ Example 25 Cyclohexyl with equivalent weight of 4-methoxyphenylthiol The procedure of Example 4 was repeated except for substituting the thiol. The main components of the product are
It is an asymmetric tetra (substituted thio) AQ having a phenylthio group and a 4-methoxy-phenylthio group at the 1, 4, 5, and 8 positions. The products obtained in Examples 1-25 are designated as products 1-25, respectively. Table 4 below shows the properties of products 1 to 25 when dissolved in the liquid crystal material E43 described above. In Table 4 and elsewhere in this specification, the symbols S and λmax. are the order parameters measured at 20°C and the wavelength of maximum absorption (S) measured at 20°C, respectively.
(measured in mm).

Table: When the term 'solubility' is used herein for dye/liquid crystal solutions, solubility is defined as 20°C.
refers to the weight percent of dye in solution measured at It should be noted that in the preparation of materials for practical guest-host applications, the solubility figure is important because: a The dye content in the liquid crystal/dye solution at 20° C. increases. As the temperature increases, the optical properties at 20°C are improved. b If the solubility of a given dye in a given host at 20 °C is relatively large, then the solubility of a dye in a given host at relatively low temperatures is usually relatively large; The higher the dye content in the liquid crystal/dye solution at , the better the optical properties at relatively low temperatures. Additional properties were measured for some of the products mentioned above, and these properties are listed in Tables 5-7 below. In Tables 5-7, the following host liquid crystal materials are mentioned: (1) Host 1, which has the composition: The substance E7 is supplied by BDH Chemical Co., Ltd. (2) Host 2, which has the following composition: The material ZLI 1132 is supplied by the company E Merck consisting of ZLI 1132. (3) Host 3, which is the material ZLI 1695 supplied by E Merck of Darmstadt. This material has a clearing point (nematic to isotropic transition temperature) of 72°C. This material is a mixture containing the compound cyanophenylcyclohexane (PCH). (4) Host 4, which contains phenyl dioxane, is a commercially available substance. This material has a clearing point of 87°C. This substance is a mixture. (5) Host 5, which is the material ZLI 1565 supplied by E-Merk. This material has a clearing point of 85°C. This material is a mixture containing the compound cyanocyclohexylcyclohexane (CCH). (6) Host 6, which is the material ZLI 1624 supplied by E-Merk. This material has a clearing point of 87°C. This material is a mixture containing PCH compounds. (7) Host 7, a material supplied by Hoffmann-La Rossille of Basle
This is ROTN 403. This material has a clearing point of 82°C and is a mixture containing cyanophenylpyrimidine (PPM) compounds. (8) Host 8, which is the material RO TN 430 supplied by Hoffmann La Roche.
This material has a clearing point of 69℃
It is a mixture containing PPM compounds. (9) Host 9, which is the following bicyclo (2, 2,
2) Octane derivatives (UK patent application no. 7926902)
) is a mixture of: (10) host 10

Table This is an example of a host material that itself has a high order parameter. (11) Host 11, which is a mixture of the following compounds expressed in weight percent:

Table This is an example of a host material that itself has a high order parameter. (12) Host 12, which is a mixture of the following compounds expressed in weight percent: Component A: 90% by weight: Component B: 10% by weight:

【table】

【table】

Table: Suitable dark gray dyes for 12 μm cells (see below) made from the above special dyes are as follows: Dye Mixture 1 Product No. 5 2.5% by weight Product No. 1 2.0% by weight Dye No. 30 1.0% by weight Dye number 30 is an example of a dye as disclosed in UK Patent Application No. 8123185 and has the formula: has. Preferred (greyer) dye mixtures are as follows: Dye Mixture 2 Product No. 5 3.1% by weight Product No. 1 2.2% by weight Dye No. 30 1.2% by weight Other suitable mixtures are as follows: Dye Mixture 3 Production Product No. 5 1.7% by weight Product No. 10 1.2% by weight Dye No. 30 0.8% by weight Examples of liquid crystal devices embodying the second aspect of the invention will now be described with reference to the accompanying drawings. As shown in FIG. 1, a Frederik effect (positive nematic) type liquid crystal display includes a liquid crystal cell consisting of two glass slides 4, 5 containing a layer 6 of liquid crystal material. This liquid crystal material is essentially a positive nematic material with pleochroic dyes.
For example, the electrodes 7 and 8 made of tin oxide are connected to the slide 4,
arranged on the inner surface of 5. A brushed aluminum reflector plate 27 may be placed after the slide 5. Before assembling the cell 3, the inner surfaces of the slides 4, 5 (which already support the electrodes 7, 8) are coated with silicon monoxide or magnesium fluoride. This coating is
For example, it is formed by depositing a stream of silicon monoxide onto the slide at an angle of approximately 5° to the slide surface, as disclosed in GB Patent Specification No. 1,454,296. When assembling, two mutually parallel slides 4,
5. Place the slide in accordance with the deposition direction on the top.
With such a coating applied, the liquid crystal molecules on the coated surface are oriented in a single direction (parallel to the direction of deposition) and at an angle of approximately 25° to 35°, typically 30°, to the adjacent slide surface. They exist together. As a result, the liquid crystal molecules exist in a parallel homogeneous organization as shown by arrows 13 (FIG. 1). Dye molecules in a guest-host relationship with liquid crystal molecules are
It is generally present in a homogeneous texture giving Cell 3 a relatively strongly colored appearance (if the dye absorbs uniformly across the visible spectrum, this appearance would be black or gray). In this or "off" state, a single polarizer 1 placed in front or behind the cell 3 (shown in front in FIG. 1) with its transmission axis parallel to the alignment direction of the liquid crystal material 6 Enhances display coloration.
This arrangement confines the electric vector of the incident or reflected light to substantially the same direction as the dye molecules change. When a suitable voltage, e.g. a few volts (greater than the effective threshold) is applied between electrodes 7 and 8 to give an "on" state, the liquid crystal material molecules are converted into a homeotropic organization, i.e. slide 4,
5 lies parallel to the electric field along the axis perpendicular to 5. Due to the guest-host effect, dye molecules are also transformed into this tissue and have long axes substantially parallel to the light incident on the cell 3 in a direction perpendicular to the slides 4, 5 [i.e. The molecules are essentially "end-on"], effectively reducing the absorption of ambient light. This gives Cell 3 a relatively shiny or slightly pigmented appearance. If electrodes 7 and 8 cover only part of the inner surface of slides 4 and 5, respectively, the entire cell 3 appears strongly colored (ie strongly reflective) in the "off" state. In the "on" state, on the other hand, only the area of the liquid crystal material 6 between the electrodes 7, 8 appears bright or weakly colored. In the "on" state, the rest of the cell 3 appears strongly colored; in the "off" state, the rest remains intact. (If the pleochroic dye absorbs uniformly across the visible spectrum, strong coloring will appear black or gray.) In this way, electrodes 7, 8 can be placed in separate dial sections.
For example, symbols or letters may be displayed by being formed into bars of a digit that can be separately connected to a voltage source (not shown). This may be achieved by photoetching (in a known manner) the layer, for example the SnO ₂ used to form the electrodes 7, 8, before assembly. For example, in the clock display of FIG. 3, the electrodes 7, 8 are formed to include four sets of seven number bars to indicate the time; for example, as shown in FIG. ing. As in a normal clock display, a pulsed period dot P is also included to indicate operation of the display. Examples of colored liquid crystal materials suitable for use such as material 6 above include the two hosts E43 as defined above.
Dye mixture 1 as described above dissolved in one of host 1 and host 1
(The thickness of the layer of substance 6 is 12 μm). In an alternative device embodying the second aspect of the invention, the cholesteric to nematic phase change effect is performed in a known manner. The construction method is to coat the inner surfaces of the electrode support slides 4 and 5 with MgF ₂ or
No SiO ₂ coating applied, no need for polarizer 1,
and the liquid crystal material 6 in this case is substantially a long pitch cholesteric material (approximately
The method is the same as the method described above with reference to FIGS. 1 to 3, except that it has a molecular helical pitch of about 2 μm. Dye mixture 1 as defined above (as used in the special Fredericks effect apparatus described with reference to Figures 1-3)
A suitable material is one of the two hosts E43 and Host 1 defined above containing (the layer thickness of material 6 is 12 μm). In the "off" state (with no applied voltage), the cell 3 then appears strongly colored (as in a Fredericks effect device). In this state, the liquid crystal material 6 has a focal conal texture consisting of irregular molecular helical arrangement. The dye molecules adopt the same arrangement due to the guest-host effect. Strongly colored due to the partial absorption of the ambient white light incident on the material 6 through the slide 4 by dye molecules oriented perpendicular or oblique to the direction of light propagation (this coloration is (can be black or dark gray). In the "on" state, sufficient voltage is applied to provide a homeotropic structure, i.e. the liquid crystal molecules between the electrodes 7, 8 are substantially reoriented and the slides 4, 5
(typically 10~
15 volts) is applied between electrodes 7,8. The dye molecules between electrodes 7, 8 are reoriented into this arrangement by the guest-host effect. This is because the dye molecules are essentially "end-on" to the ambient light propagating (through slides 4) perpendicular to the cell 3, i.e. perpendicular to the slides 4, 5. In the state (as per the Fredericks effect device)
The area between electrodes 7, 8 appears shiny or weakly colored. The appropriate host in this case is specified above (96
Weight%) either E43 or host number 1
CB15 (4% by weight) was added. Dye mixture 1 as defined above may be used as guest dye. CB15 is a compound supplied by BDH It is.

[Brief explanation of the drawing]

FIG. 1 is an exploded view of a Fredericks effect display device embodying the present invention, and FIG.
A sectional view of the device shown in the figure, and FIG. 3 a front view of a watch with a liquid crystal display assembled as shown in FIGS. 1 and 2. DESCRIPTION OF SYMBOLS 1... Polarizer, 3... Liquid crystal cell, 4, 5... Slide, 6... Liquid crystal substance, 7, 8... Electrode, 27... Reflection plate.

Claims (1)

[Claims] 1. The pleochroic dye has the formula: {where n is 0 or 2; Q is an alkyl group having 1 to 20 carbon atoms; X is a hydrogen atom, OH, NZ ₁ Z ₂ (Z ₁ and Z ₂ are each a hydrogen atom, a phenyl group or an alkyl group having 1 to 4 carbon atoms), or SR [R is an alkyl group having 1 to 4 carbon atoms, an aryl group of the formula (A is a hydrogen atom, a phenyl group, or is an alkyl group or alkoxy group having 1 to 4 carbon atoms), an aryl group of [formula] (B is an alkyl group having 1 to 4 carbon atoms), or [formula]] A guest consisting of a solution of a pleochroic dye in a liquid crystal material, characterized in that it contains at least one anthraquinone compound represented by - Composition for host liquid crystal device. 2. Composition according to claim 1, characterized in that when the group Q is present as an alkyl group, this alkyl group has 1 to 10 carbon atoms. 3. Claim 1 or 2, characterized in that the group R is a phenyl group or a substituted phenyl group
The composition described in Section. 4 The composition has the formula: (In the formula, R ¹ and R ² are different and have the same meaning as the definition of R in claim 1, but R ¹ is an aryl group.) A composition according to any one of claims 1 to 3. 5. The composition according to claim 4, wherein ^R1 is a phenyl group and ^R2 is a 4-t-butylphenyl group. 6 The composition has the formula: (In the formula, T ¹ , T ² , T ³ and T ⁴ each independently have the same meaning as the definition of R in claim 1,
The composition according to any one of claims 1 to 5, characterized in that the composition contains an anthraquinone compound represented by the following formula (3 or less of T ¹ to T ⁴ are the same). 7 The composition has the formula: (In the formula, T ⁹ is a hydrogen atom and T ¹⁰ is a t-butyl group.)
The composition according to any of paragraph 6. 8 The composition has the formula: (In the formula, Y ¹ , Y ² and Y ³ each independently have the same meaning as the definition of R in claim 1). The composition according to any one of items 1 to 7. 9 A patent characterized in that n is 2, two of the groups represented by X are -SR, the remaining groups are OH or NH ₂ , and R is an aryl group of [Formula] A composition according to claim 1. 10. A patent claim characterized in that two of the groups A composition according to scope item 9. 11 The dye is one of the asymmetric poly(substituted thio)anthraquinone dyes in which there is a thio group substituted with at least two different substituents according to any one of claims 1 to 4, or and one or more symmetrical poly(substituted thio)anthraquinone dyes in which all of the substituted thio groups are identical. The composition according to any one of Item 10. 12. Composition according to claim 11, characterized in that the dye contains at least 50% by weight of one or more asymmetric poly(substituted thio)anthraquinone dyes. 13 The dye has the formula: A composition according to claim 1, characterized in that it contains a compound selected from the group consisting of: 14. An apparatus comprising two electrically insulating substrates, at least one of which is optically transparent, an electrode on an inner surface of the substrates, and a film of dielectric material contained between the substrates; the substance is a solution of a pleochroic dye in a liquid crystal substance, and the pleochroic dye is
formula: {where n is 0 or 2; Q is an alkyl group having 1 to 20 carbon atoms; X is a hydrogen atom, OH, NZ ₁ Z ₂ (Z ₁ and Z ₂ are each a hydrogen atom, a phenyl group or an alkyl group having 1 to 4 carbon atoms), or SR [R is an alkyl group having 1 to 4 carbon atoms, an aryl group of the formula (A is a hydrogen atom, a phenyl group, or is an alkyl group or alkoxy group having 1 to 4 carbon atoms), an aryl group of [formula] (B is an alkyl group having 1 to 4 carbon atoms), or [formula]] A liquid crystal electrochemical device comprising at least one anthraquinone compound represented by the formula } with the proviso that at least two of the groups