CA1168036A - Liquid crystal materials with pleochroic dyes - Google Patents
Liquid crystal materials with pleochroic dyesInfo
- Publication number
- CA1168036A CA1168036A CA000382632A CA382632A CA1168036A CA 1168036 A CA1168036 A CA 1168036A CA 000382632 A CA000382632 A CA 000382632A CA 382632 A CA382632 A CA 382632A CA 1168036 A CA1168036 A CA 1168036A
- Authority
- CA
- Canada
- Prior art keywords
- formula
- compound
- liquid crystal
- nr1r2
- groups
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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Classifications
-
- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
- C09K19/00—Liquid crystal materials
-
- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09B—ORGANIC DYES OR CLOSELY-RELATED COMPOUNDS FOR PRODUCING DYES, e.g. PIGMENTS; MORDANTS; LAKES
- C09B1/00—Dyes with anthracene nucleus not condensed with any other ring
- C09B1/56—Mercapto-anthraquinones
- C09B1/58—Mercapto-anthraquinones with mercapto groups substituted by aliphatic, cycloaliphatic, araliphatic or aryl radicals
-
- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
- C09K19/00—Liquid crystal materials
- C09K19/04—Liquid crystal materials characterised by the chemical structure of the liquid crystal components, e.g. by a specific unit
- C09K19/06—Non-steroidal liquid crystal compounds
-
- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
- C09K19/00—Liquid crystal materials
- C09K19/52—Liquid crystal materials characterised by components which are not liquid crystals, e.g. additives with special physical aspect: solvents, solid particles
- C09K19/60—Pleochroic dyes
- C09K19/603—Anthroquinonic
Abstract
ABSTRACT OF THE DISCLOSURE
A material suitable for a guest-host liquid crystal device comprises a solution of a liquid crystal material and a pleochroic dye wherein the pleochroic dye comprises at least one compound having a formula:
A material suitable for a guest-host liquid crystal device comprises a solution of a liquid crystal material and a pleochroic dye wherein the pleochroic dye comprises at least one compound having a formula:
Description
6~03~
The present in~ention is concerned with organic materials, in part-icular with pleochroic dyes in solution with liquid crystal materials e.g. for electro-optic display applications.
Liquid crystal materials are well known organic materials which dis-play phases, known as liquid crystal phases or mesophases, having a degree of molecular ordering intermediate between that of the fully ordered crystalline solid state and the fully disordered isotropic liquid state.
Electro-optical devices incorporating liquid crystal materials are well known and widely used as digital displays in such applications as watches, calculators and digital voltmeters. ~hese devices utilise the optical contrast when an electric field is applied across a thin insulating film of suitable liquid crystal material. The mDlecules of the material ~in a liquid crystal phase at the temFerature of operation) are re-orientated by the field causing a change in an optical property of the part of the film where the field is applied, e.g. a change in ambient light scattering or transmissivity.
Liquid crystal materials have the property that their molecules can impose their ordering upon the molec~les of other suitable dopant materials in-corporated within them. Thls property is the basis of so-called "guest-host" de-vices e.g. display devices in which the host liquid crystal material and its guest material have one molecular configuration in the absence of an applied electric field and another molecular configuration when an electric field is applied across the material. me guest material is usually a pleochroic dye, which is a dye whose molecular absorption proFerties vary with the orientation of the electric vector of light incident upon its molecules.
The presence of such a dye can be used to enhance the contrast between the off state~ (with no electric ield applied) and the on state (with electric field applied) of a liquid crystal display because the orientation of the dye Ot~
1 3 ~8Q3~
molecules is in effect switchable by the effect of the applied electric field on -the liquid crystal molecules and by the consequent re-orientation of the dye molecules by the guest-host effect.
As discussed further below there are several kinds of liquid crystal effects which can make use of the g~lest-host effect in electro-uptical displays.
mese vary according to the kind of liquid crystal material used and the con-figuration of its molecules in the oEf state (e.g. as determined by the surface treatm~nts of the substrates e~,ployed to contain the filn of liquid crystal mate-rial).
In order to provide maximum contrast between the on and off states of a guest-host liquid crystal display it is impoxtant that the guest molecules aaopt as closely as possible the time averaged orientation of the host molecules.
Hcwever this is achieved only to a limited degree because of randcm thermal fluctuations. The degree to which the orientation varies from the ideal is mea-sured by a quantity kncwn as the order parameter S which is given by the follow-ing equation:
S = 1/2 (3 cos23 - 1) Equation (1) where cos 3 is a time averaged term and 9 is the instantaneous angular orienta-tion of the m~lecules with respect -to the time averaged orientation of the host molecules~ The determination of the value of the order parameter S is well understood m the art; see for example the paper "A new absorptive mode reflec-tive liquid crystal display device" by D.L. White and G.N. Taylor in the Journal of Applied Physics, 1974, 45 pages 4718 to 4723.
For perfect orientation the order parameter S is unity (that is ~ is zero). mus, pleochroic dyes for use in guest-host devices should have an order parameter in the liquid crystal host as high as possible (i.e. less than one but as near to one as possible). However they must also have adequate chemical, 1 ~ 6~303~
photochemical and electrochemical stability, e.g. stability when exposed to atmospheric contaminants, electric fields (as in device operation) and to ultra--vlolet radiation. They should not be ionic or have any ionisable character (otherwlse the liquid crystal material will lose its insulating nature and con-duct making the device useless). mey must also have sufficient solubility in the host materials; although the concentration of guest pleochroic dye required for the desired effect is generally quite small (e.g. not more than a few per cent of dye) nevertheless many pleochroic dyes are unsuitable becuase they are essentially insoluble in liquid crystal materials.
Selection of a suitable pleochroic dye usually involves a ocmpromise between these various properties.
Although a vast number of dyes are known only a very small proportion of these have been proposed for use with liquid crystal materials owing to the need to achieve a suitable combination of the properties mentioned above.
~r 1 1 6~03~
European Patent Specification No. 210,4A describes a series of anthraquinone'pleochroic dyes suita~,le for use with liquid crystal materials. These dyes, ~hich are commercially available, largely show good stability properties and reasonable solubility. However their order parameters are generally rather low, typically 0.6 in the cyanobiphenyl/terphenyl host material E7, whose composition is given below. (Although two examples of dyes having an order parameter of about 0.7 in E7 are quoted in the said European Specification one of these dyes is relatively unstable and the other is fairly insoluble in liquid crystal materials.) According to the present invention in a firs-t aspect a material suitable for a guest-host liquid crystal device comprises a solution of a liquid crystal material and a pleochroic dye wherein the pleochroic dye comprises at least one compound having a formula:
(Q)y ~ (SR~ Formula (I) wherein: R represents a group selected from optionally substituted alkyl and optionally substituted monocyclic aryl; Q represents a group selected from halo, OH, -NO2, alkyl, aryl and NRlR2, wherein each of Rl and R2 independently represents a group selected from H, alkyl and aryl; x represents an integer from l to 4; and y represents an integer from 0 to 4; x ~ y being in the inclusive range 2 to ~.
,~ It is preferably , - 5 -'.1 4~"' 1 ~ 6~03~
provided that where x = 2~ y = O and R = phenyl or 4-substituted phenyl the liquid crystal material (and the solution) has a negative dielectric anisotropy.
~yes o~ ~ormula (I) other than those ~or which x = 2, y = O and R = phenyl or 4-substituted phenyl may be dissolved, aocording to the first aspeot o~ the invention, in a liquid crystal material having ei-ther a positive or negative dielectric aniso-tropy.
It is well known to those skilled in the liquid crystal art tha-t liquid crystal materials may have either a positive or negative dielectric anisotrcpy. ~xamples of materials, and guest-host devices containing them, having respectively a positive and negative dielectric anisotropy are desoribed below.
Pre~erably~ ~RlR2 is ~HR1 where R1 is H~ monocyclic aryl~ especially phenyl or subs-tituted phenyl, or optionally substituted alkyl oontaining from 1 -to 5 oarbon atoms.
Preferred optional subs-ti-tuen-bs wheie R1 is substitu-~ed alkyl are lowe~ alkoxy~ OH and monooyolio aryl.
~20 Preferably~ R is monooyclic aryl~ especially phenyl or subs-tituted phenyl~
Where R or Q is alkyl i-t preferably contains up to 10 carbon atoms in a straight or branched chain and more preferably contains ~rom 3 -to 10 oarbon a-toms. As optional substitutents there are preferred lower alkoxy, OH ana monocyolic aryl.
Where Q is monooyclic aryl it is preferably phenyl or substituted phenyl.
- Where R~ Q, R1~ R2 or R is substituted phenyl it is preferably substituted by a lower alkyl~ lower alkoxy, halo~ ~2' ~ or ~R1R2 group (where ~R1R2 is as de~ined above) - which may be the same as or different ~rom the afore-mentioned group ~R1R2o ~he substituents are pre~erably in the meta or para position relative to the lir~ wi-th the anthraquinone nucleus. Preferred halo substituents are chloro and bromo.
Within the general class o~ compounds represented by Formula (I) a preferred sub-class o~ dyes may be represented by the formula:
~ (~ )y ~ormuaa (II) B o c wherein each o~ A, B and C independently represents H, -~R or -NR1R2 and ~ and y are as pre~iously de~ined.
Many of the dyes o~ Formula (I)~ particularly those o~
Formula (II)~ ha~e been ~ound to show particularly good stability and reasonable solubility as well as reasonably high order parame-ters in liquid crystal material, eg 4-n-alkyl-or -alkoxy-4t-oyanobiphenyl-based material, making them more attraotive -than the dyes disclosed in European Patent Speci~ioation No 210~A.
Particular mention may be made o:~ dyes o~ Formula (II) wherein y = 0 and wherein o~ the -three groups A, 3 and C two are -SR groups and the third is E particularly where R is aryl;
and o~ dyes o~ Formula (II) wherein y = 0 and of the three groups A, B and C one is -NR1R2 and the o-ther -two are hydrogen or one is hydrogen and the other two are -NR1R2 groups. A
number o~ dyes o~ these forms have been ~ound to show exceptionally high solubility as well as high order parameter in liquid crystal material (as exempli~ied below).
I 1 6803~
Other preferred dyes within the sub-class represented by ~ormula (II) are those in which y = O and A = B = C = ~SR;
A = -SR and 3 = C = ~R1R2; ~ = SR and A = C = -NR1R2;
C = -SR and A = ~ R1R2; A = ~ = C = -NR1R2; A = C = ~ = H;
A = 3 = SR and C = ~R1R2; A = C = -SR and ~ = ~R1R2; and A = ~R1R2 and 3 = C = SR.
Dyes of Formula (II) wherein y = 0~ 3 _ SR~ A = H and C = H are also pre~erred, subject to the proviso that they are used only with liquid crystal materials having a negative dielectric anisotropy Subject to the same proviso, the liquid crystal material (host material) in which -the dye of Formula (I) is dissolved - in the first aspect above is not critical since a dye which shows reasonable solubility in one liquid crystal material is likely to show reasonable solubili-ty in other liquid crystal materials and also a dye which gives an improved order parameter in one liquid crystal material is likely to give an improved order parame-ter in other liquid crystal materials, as most popl~ar liquid cr~s-tal materials have a similar rod-like moleoular shape; however the order parame-ter of any dye will vary to a limited extent from hos-t-to-host.
Suitable host materials include:
a. mixtures having a positive dielectric anisotropy incorporating cyano'biphenyls preferably together with a ~ew per cent o~ a compound having a clearing point (liquid crystal to isotropic liquid transi-tion) above 150C (eg a cyano-p-terphenyl) such as the material E7, marketed by ~DH Chemicals Ltd, o~ 3room Road, Poole, Dorset7 England;
(composition given below.) b. mixtures having a positive dielectric anisotropy incorporating 1-(47-cyanophenyl) 4-alkylcyclohexane compounds preferably together also with a few per cent of a high clearing point compound such as a 1-(4'~cyanob'iphenyl3-4-alk~lcyclohexane compound; eg the material ZLI 1132;
~ 3 ~3~
c. mixtl~es having a positive dielectric anisotropy incorporating at least one cyanobiphenyl and at least one cyanophenylpyrimidine, preferably together also with a few per cent of a high clearing point compound, eg a cyanophenylpyrimidinephenyl compound, eg the material ROTN 30;
d. mixtures incorporating esters, eg containing bicyclo (2,2,2) octane and benzene rings; these generally have a weakly positive or negative dielectric anisotropy but the magnitude o~ the dielectric anisotropy may be enhanced by the addition of a dopant liquid crystal material having a strongly positive or strongly negative dielectric aniso-tropy as appropriate; suitable negative dopants are the dicyano compounds which are specified in claim 2 of 15 ~ UK Patent Application No 2,061,256A;
e. any other liquid crystal material incorporating one or more compounds selected from the following known families (where R = aIk~rl): .
R~;\r~\r Y~ xiv R <~ ~1~ t~-Y1 i R~Y~ xv ~ ~c~ <~Y, iii RO~Y~ xvi ~ ) m=1~2 iv Ro~Y, xvii F~ <,_xl Y
V R~Y~ X\ilii R~<~coo-xj-y, ~ c~7. o_ x1- y; x i ~ `R~
viii ~".~ X- y xx Q~c~ YI
iX RC)~--X--Y, . ~ ~CI
Y~i r~ y` ,~X ' i R~~
xii R~c- ~y I ~CXlli R-~>~-y xiii R.o~ xx~ R~
,, xxY R~COO~>~ -R
xx v'~ R~cl~~ C1~2,~t}-c~
I 1 ~8Q3~;
.
or derivatives of any of the these containing benzene rings wherein the benzine rings contain one or more substituents, eg fluoro;
where~3-is a trans -1,4 substituted cyclohexane rin~
~ i~ ~ 1,4 ~ubstituted bicyclo (2.2.2) octane ring, X1 i~ a 1,4 phenylene group ~ , or a 474 biphenylyl group ~ or a 2,6 naphthyl group ~ j and Ylis CN, or R , or OR or CO. O-X1-Y where Y is CN, or R or OR ; the de~inition of ~ being the ~ame as that of R.
Preferably, -the dye/liquid crystal solution contains at least ~.Sq by weight of the dye and preferably between about 0.~5% and 5~ by weight of the dye or more tpossibly up to 10%
by weight).
Solu-tions of dye and liquid crystal material may be made in a oonventional way simply by mixing the dye and the liquid crystal material together and then heating the mixture at about 80 C with s-tirring for about 10 minutes and then allowing the mixture to cool.
Pleoohroio dyes of ~ormula (I) above may be mixed together with other dyes (whioh may or may not also be of ~ormula (I)) to extend their speo-tral absorption prop0rties (when dissolved in liquid orystal material). For exampletwhere a dye o~
~ormula (I) is a yellow or red dye it may be mixed with a red or yellow dye respeo-tively and a blue dye. Alternatively, where a dye of ~ormula (I) is orange it may be mixed together with a blue dye~ optionally -together with a yellow and/or red dye. ~he relative proportions of the ~yes mixed together are determined by the desired speotral response as determined by the extenotion coefficients of the consti-tuent dye compounds. ~he dye mixture is then used with liquid crystal material as above or as ~ollows.
According to the present invention in a second aspect a liquid crystal electro-optical display includes two electrically insulating substrates at least one of which is optically transparent, electrodes on the inner surfaces of the substrates . .
~ 1 ~803~
.
and a film of dielectric material contained between the electrodes and substrates, wherein the dielectric ma-terial is material according to the first aspect of the invention as defined above.
The liquid crystal/dye solution which is the material according to the first aspect of the invention may be used in any known electro-optical display as defined in the second aspect. Examples~ which will be familiar to those skilled in the liquid crystal art, are the known devices operating by the following effects:
a. THE ~WIS~ED NEMATIC EF~EC~
In this case a film of nematic liquid crystal material of posi-tive dielectric anisotropy has an off state in which (the long axes of) its molecules lie in the plane of the device substrate inner surfaces (which are normally parallel to one another), or at a small angle thereto, and.undergc roughly a ~/2 helical twist in orientation from one subs-trate -to -the other by virtue o~ the orientations at the surfaces caused by treatment~ eg unidirectional rubbing, of -those surfaces prior 20 to assembly. ~his is the -twisted l'homogeneous texture".
Applicaticn of an electric field between the elec-trodes on the respeoti.ve substrate inner surfaces to give -the on s-tate causes re-arrangement of the liquid crys-tal molecules -to lie (with their long axes) effec-tively perpendicular to -the substrate 25 inner surfaces in the "homeotropic texture". A change in optical ac-tivity (rotary power) of the film occurs between the on and off states by virtue of the mol.ecular re-arrangement.
and the optical effect observed can be enhanced by the use of a linear polariser adjacent to one of the substrates and 30 pleochroic dye dissolved in the liquid crystal ma-terial. ~he polariser has its polarisation axis parallel to the direction of the liquid crystal mclecules at the adjacen-t subs-trate inner surface (or, more strictly, parallel tc the average 1 ~ 68 03 G
axis of projection of the molecules on -that surface). ~y the guest-host effect the dye causes the off state to appear relatively dark or strongly colour whereas the on state appears olear or weakly ooloured.
b. ~Hæ ~K~ERICKS~ E~FEC~ EGATIVE ~EMATICS
In this oase a film of nematio liquid orystal material of negative dielec-tric anisotropy has an off state in which its molecules lie perpendicular (ie in the homeo-tropic texture) to the substrate inner surfaces (which are parallel) by virtue of surface treatments to these inner surfaoes prior to assembly. A single polariser is placed adjacent to one substrate with its transmission axis perpendicular to the normal to the inner surfaces. Application of an electric field between the elec-trodes on the respeo-tive substrate inner surfaoes to give -the on state causes re-arrangement of the liquid crystal mcleoules to lie parallel to the substrate inner surfaces (ie in the homogeneous texture). Incorporation of pleochroic dye in the liquid crystal material ensures that the off s-tate appears relatively clear or weakly coloured whereas the on s-ta-te appears dark or s-trongly ooloured. The effeot observed is eMhanoed by the presence of the polariser.
c. THE ~h~ ERICKSZ EFFECT I~ POS~IVE ~EMA~ICS
In this oase a nematio liquid crystal material of positive dieleotrio anisotropy has an off state in which the moleoules lie roughly parallel and in the plane of the substrate inner surfaoes (whioh are parallel) by virtue of treatment of those surfaoes prior to assembly (ie the homogeneous texture).
A single polariser is placed adjacent to one substrate with its transmission axis parallel to the substrate inner surfaces.
Applioation of an electric field between the electrodes on the respeotive substra-te inner sur~aces to give the on state causes re-arrangement of the liquid crystal mclecules tc lie perpendicular to the substrate inner surfaoes~ ie -the homeotropic texture. Incorporation of pleochroic dye in the ~ 1 6803~
liquid crystal material ensures that the off state appears relatively dark or strongly coloured whereas the on state appears colourless or weakly coloured as in the twisted nematio effect above. 'rhe effeot observed is enhanced by the presence of the polariser.
d. 'rHE PHASE CHA~GE Ehh~CT (NEGA'rIVE CON'rRAS'r 'rYPE) In this case a oholesterio liquid crystal material of positive dielectric anisotropy and long molecular helical pitch, typically3 ~m, has an cff state in which its molecules 10 ~ lie in random helices, ie the "fccal conic texture".
Application of an eleotric field between the electrodes on -the respeotive substrate inner surfaces to give the on state causes re-arrangement of -the liquid orystal molecules to lie perpendicular to the substrate inner surfaces (ie the homeotropic texture as for postive nematics in the ~rëedericksz effect). Inoorporation of pleoohroic dye in the Iiquid crystal material gives an of`f s-ta-te which appears relatively dark or strongly ooloured and an on state which appears cclourless or weakly ooloured.
e. ~rHE PHASE CHANGE E~EC'r (POSI~IVE CONTRAS'r ~YPE) In -this case a cholesterio liquid crystal material of negative dieleotric anisotropy and long moleoular helioal pitoh has an off sbate in which its moleoules lie perpendicular -to -the substrate inner surfaces, ie in the homeotropic texture.
Applioation of an eleo-trio field be-tween electrodes on the respec-tive substrate inner surfaces causes re-orienta-tion of the moleoules to lie in the plane of the substrate inner surfaces in a helioal arrangement ie the twisted homogeneous texture. Inoorporation of pleoohroic dye in the liquid crystal material gives an off state which is relatively oolourless or weakly coloured and an on state whioh is relatively dark or strongly oolouredJ
1 16~03G
f. ~HE ~REEDERICKSZ EFFEC~ IN SMECTICS
In this case a smectio A liquid crystal material of positive dielectric anisotropy having a dielectric relaxation frequency fc less than about 10 kHz (ie the material has a negative dielectric anisotropy above this frequency) has an off state in which its molecules lie roughly parallel to the substrate inner surfaces with the molecules at the two inner surfaces parallel as in the Freedericks~ effect (c).
Application of an electric field with a frequency less than fc to give the on state causes re-orientation of the liquid crystal molecules to lie perpendicular to the substrate inner surfaces, is in the homeotropic texture. ~he on state is preserved when the field is removed. Clearing of the on state may be achieved by the application of a high frequency elec-tric field, ie with a frequency> fc. A single polariser is used, as with the ~reedericks~ effect (c) abcve, when the molecular alignmen-t at the two substrate inner surfaces in the off state is parallel. Incorporation of plecchroio dye in the liquid crys-tal ma-terial gives an off s-tate which is relatively dark or strongly coloured and an on state which is clear or weakly ooloured.
Use of the material defined in -the first aspeo-t of the invention above is not limi-ted to eleotro-op-tioal displays (as defined in the seoond aspeot). The material may, in fact, be used in any known application of a dyed liquid crystal material. An example of such a Inon electro-optical' appli-oation is a thermally addressed display in whioh a symbol or oharacter is provided in a smectic or cholesteric material by selective heating of the material eg by a laser (eg He/~e) beam, to produce a localised change in the molecular texture of the material. ~he dye enhances the contrast between the different regions of the display, ie between those which are selectively heated and those which are not heated.
1 3 6gO3~
An-thraquinone dyes falling wi-thin the scope of Formula (I), and Imethods for -their preparation, have been described in the prior art. Thus, methods for the preparation of alpha-phenylthioanthraquinones have been described in United Kingdom Patent Specifioation No 1105568. In general, such methods involve reacting an anthraquinone compound have replaceable subs-tituents in the alpha positioning with a thiophenol in the presenoe of a base and a suitable reaction medium. Beta-phenylthioanthraquirlones may be prepared in an analogous manner.
~or the purposes of the present invention, the anthra-q~inone compounds of Formula (I) should be of ex-tremely high purity as will be obvious to those skilled in the art.
Purification may be effected using oonven-tional methods such as recrystallisation from suitable solven-ts and chromatography.
Examples of the preparation and properties of dye compounds having ~ormula (I) will no~r be given:
EXA~L~ Preparation OI Compound ~o 1: 1,5-bis(phenylthio) anthraquinone~
1,5-Diohloroanthraquinone (100 parts) is added at room temperature with s-tirring to a mixture of dimethylformamide (474 parts), -thiophenol (135 parts) and potassium oarbonate (63 parts). 'rhe suspension is heated at 125C for 3 hours, cooled -to room tempera-ture and then cooled to 5 C for 1 hourO
~he precipita-te is filtered off and washed with a 50/50 mixture of 95% ethanol and 8% sodium hydroxide solution (2 x 250 parts).
The filter cake is then slurried with a further 500 parts of the ethanol/sodium hydroxide solution mix-ture. After stirring at room temperature for 1 hour, the precipitate is filtered off 3o and washed aga.in with ethanollsodium hydroxide solution mixture (5 x 100 parts), followed by water (250 parts) containing glacial acetic acetic acid (25 parts) and finally water (3 x 250 parts). ~he filter--cake is dried at 70 C giving 140.4 parts of 1,5-bis(phenylthio) anthraq~inone, mp (melting point) 256C.
~ ~ ~803~
~s Examples 2-24 the compounds listed in ~able I below having the following general ~ormula:
Rg ~1 7 ~ ~ ~ ormula (III) R~ 3 R~ R4 are each made by a similar method to that described in Example 1 with the appropriate quantity of the appropriate mono-~ di-, tri~ or tetrA_chloro anthraquinone and the appropriate mercaptan.
1 3 6803~
X X ~ X P~
X ~ P~ X ~ X ~q ~' Pi : :
:: :
8 o o o o ~ o ,_ o ~ ~ ~
~ o C\l o ~
o o~
1~ CO 0~ 0 ~ C\l ~ ~ IS~ O
:
O
, ~ P~
V~
V~
.
' O ~ N r~
~ ~ ~ N N N N N
O
~ .
68~3 100 g of -the sodium salt of 1-ni-tro-anthraquinone-5-sulphonic acid is boiled in 500 g water to give a partial solution and oooled to room temperature. 150 g of concentrated sulphTlric acid is added dropwise over 10 minutes and the mixture heated to reflux temperature. 330 g of a mixed sodium chlorate/sodium chloride solution containing 30.8 g sodium chlorate and 33.6 g sodium chloride is added over a period of 6 hours and the mixture refluxed for a further 3 hours~ At the end of this period the mixture is filtered hot~ washed with 800 g of hot wa-ter and dried at 80 C~ ~he product is 1-nitro-5-chloroanthraquinoneO (69.3 g: purity by HPLC 92~o).
A solution of 39.1 g phenyl mercap-tan in 62 ml dime-thyl-formamide containing 16 g potassium carbonate is prepared by heating at 100 C for 2 hours and cooled to 40C. Ethanol (250 ml) and 36.2 g of -the 1-nitro-5-chloroanthraquinone are added and stirred for 16 hours a-t 40C and allowed to cool to room temperature over ~8 hours. ~he product is fil-tered washed with 46~o aqueous ethanol (-l- li-tre) slurried in 40~0 aqueous ethanol (250 ml) s-tirred for 30 minutes, filtered and washed with 100 ml o~ 40~0 aqueous ethanol and ~inally with 2 litre of water. It is then reslurried in 250 ml water? stirred for 30 minutes~ filtered,washed with 250 ml water and 50 ml 20~o aqueous ethanol and dried at 80C~ The product is 1-phenyl-thio-5-chloroanthraquinone (43.9 g purity by HPLC 94.2%) (~ minor amounts o~ dithiophenyl-AQ and dichloro-AQ; AQ =
anthraquinone~
A mixture of 1.75 g 1-phenylthio-5-chloroanthraquinone, 0.4 g n-butylamine and 0.39 g potassium carbonate in 16 ml dimethylformamide is stirred at 120C for 3 hours after which a tlc runout indicates 66~o reactionO A further 0.4 g n-butyl-amine and 0 39 g potassium carbonate are added and reaction at 120C continued for a further 8 hours. The mixture is cooled to room temperature, 20 ml ethanol added it is filtered and then washed with 36 ml 2~ ~aOX/ethanol. The product is reslurried in ~ ~ fi803t~
30 ml of the ~aOH/e-thanol~ stirred for 30 minu-tes 9 fil-tered~
washed with 26 ml ~aOI-I/e-thanol, followed by 50 ml water and 36 ml of 50~0 aqueous ethanol and dried at 50C. This product is reorystallised from 200 ml of ethanol~-reduced -to 20 ml after filtration~ washed with ethanol and dried at 80C. The produot is 1-phenylthio-5-n-butylaminoanthraquinone (.95 g:
m.p. 140-142C).
~ .
A mixture of 3.12 g o~ tert-butyl phenyl mercaptan, 1.30 g potassium carbonate and 10 ml dimethylformamide are stirred at 120 C for 2 hours and cooled to r~om temperature. To t~is are added 3.14 g of 1-n-butylamino-5-chloroanthra~linone, prepared as described below~ and -the reactionmixture refluxed for 5 hours. It is then cooled to room temperature~ 20 ml of ethanol is added and -the product~ 1 n-butylamino-5--tert-butylphenylthio-anthraquinone isola-ted and purified using the me-thod described in the last stage of Example 25. q`he yield of product is 4.3 g in the form of a tar. q'his tar is di`ssolved in -toluene and passed through a silica colurnn using toluene as eluent and the rnain red fraotion oolleoted. After evaporating the toluene the produot is recrystàllised from ethanol and dried to gi~e a yield of 2.5 g of 91.5% purity by ~LC and m.p. 168-9C.
qlhe 1-n~butylamino-5-chloroanthra~inone used above is prepared by heating a mixture of 17 g 1-nitro-5-chloroanthraqulnone~ 5.1 g urea~ 106 ml ethanol and 18.7 g n-butylamine under reflux for 48 hours. After this period 5.1 g urea and 68 ml n-bu-tanol are added and refluxing continued for a further 16 hours. ~he reaction mixture is screened ho-t and -the fil-trates retained. The solid residue is washed wi-th butanol~ fil-tered hot and the filtrate retained.
q`he combined filtrates are cooled to 0C~ filtered after 2 hours a-t 0C and the solid product washed with bu-tanol. A~-ter drying at 80C the yield is 9 g and purity by HPLC is 82.8%.
~e~
A mixture of 2.97 g phenylmercaptan, 1.81 g potassium carbonate and 10 ml dimethylformamide are stirred at 120C for " :
I 1 6~03B
The present in~ention is concerned with organic materials, in part-icular with pleochroic dyes in solution with liquid crystal materials e.g. for electro-optic display applications.
Liquid crystal materials are well known organic materials which dis-play phases, known as liquid crystal phases or mesophases, having a degree of molecular ordering intermediate between that of the fully ordered crystalline solid state and the fully disordered isotropic liquid state.
Electro-optical devices incorporating liquid crystal materials are well known and widely used as digital displays in such applications as watches, calculators and digital voltmeters. ~hese devices utilise the optical contrast when an electric field is applied across a thin insulating film of suitable liquid crystal material. The mDlecules of the material ~in a liquid crystal phase at the temFerature of operation) are re-orientated by the field causing a change in an optical property of the part of the film where the field is applied, e.g. a change in ambient light scattering or transmissivity.
Liquid crystal materials have the property that their molecules can impose their ordering upon the molec~les of other suitable dopant materials in-corporated within them. Thls property is the basis of so-called "guest-host" de-vices e.g. display devices in which the host liquid crystal material and its guest material have one molecular configuration in the absence of an applied electric field and another molecular configuration when an electric field is applied across the material. me guest material is usually a pleochroic dye, which is a dye whose molecular absorption proFerties vary with the orientation of the electric vector of light incident upon its molecules.
The presence of such a dye can be used to enhance the contrast between the off state~ (with no electric ield applied) and the on state (with electric field applied) of a liquid crystal display because the orientation of the dye Ot~
1 3 ~8Q3~
molecules is in effect switchable by the effect of the applied electric field on -the liquid crystal molecules and by the consequent re-orientation of the dye molecules by the guest-host effect.
As discussed further below there are several kinds of liquid crystal effects which can make use of the g~lest-host effect in electro-uptical displays.
mese vary according to the kind of liquid crystal material used and the con-figuration of its molecules in the oEf state (e.g. as determined by the surface treatm~nts of the substrates e~,ployed to contain the filn of liquid crystal mate-rial).
In order to provide maximum contrast between the on and off states of a guest-host liquid crystal display it is impoxtant that the guest molecules aaopt as closely as possible the time averaged orientation of the host molecules.
Hcwever this is achieved only to a limited degree because of randcm thermal fluctuations. The degree to which the orientation varies from the ideal is mea-sured by a quantity kncwn as the order parameter S which is given by the follow-ing equation:
S = 1/2 (3 cos23 - 1) Equation (1) where cos 3 is a time averaged term and 9 is the instantaneous angular orienta-tion of the m~lecules with respect -to the time averaged orientation of the host molecules~ The determination of the value of the order parameter S is well understood m the art; see for example the paper "A new absorptive mode reflec-tive liquid crystal display device" by D.L. White and G.N. Taylor in the Journal of Applied Physics, 1974, 45 pages 4718 to 4723.
For perfect orientation the order parameter S is unity (that is ~ is zero). mus, pleochroic dyes for use in guest-host devices should have an order parameter in the liquid crystal host as high as possible (i.e. less than one but as near to one as possible). However they must also have adequate chemical, 1 ~ 6~303~
photochemical and electrochemical stability, e.g. stability when exposed to atmospheric contaminants, electric fields (as in device operation) and to ultra--vlolet radiation. They should not be ionic or have any ionisable character (otherwlse the liquid crystal material will lose its insulating nature and con-duct making the device useless). mey must also have sufficient solubility in the host materials; although the concentration of guest pleochroic dye required for the desired effect is generally quite small (e.g. not more than a few per cent of dye) nevertheless many pleochroic dyes are unsuitable becuase they are essentially insoluble in liquid crystal materials.
Selection of a suitable pleochroic dye usually involves a ocmpromise between these various properties.
Although a vast number of dyes are known only a very small proportion of these have been proposed for use with liquid crystal materials owing to the need to achieve a suitable combination of the properties mentioned above.
~r 1 1 6~03~
European Patent Specification No. 210,4A describes a series of anthraquinone'pleochroic dyes suita~,le for use with liquid crystal materials. These dyes, ~hich are commercially available, largely show good stability properties and reasonable solubility. However their order parameters are generally rather low, typically 0.6 in the cyanobiphenyl/terphenyl host material E7, whose composition is given below. (Although two examples of dyes having an order parameter of about 0.7 in E7 are quoted in the said European Specification one of these dyes is relatively unstable and the other is fairly insoluble in liquid crystal materials.) According to the present invention in a firs-t aspect a material suitable for a guest-host liquid crystal device comprises a solution of a liquid crystal material and a pleochroic dye wherein the pleochroic dye comprises at least one compound having a formula:
(Q)y ~ (SR~ Formula (I) wherein: R represents a group selected from optionally substituted alkyl and optionally substituted monocyclic aryl; Q represents a group selected from halo, OH, -NO2, alkyl, aryl and NRlR2, wherein each of Rl and R2 independently represents a group selected from H, alkyl and aryl; x represents an integer from l to 4; and y represents an integer from 0 to 4; x ~ y being in the inclusive range 2 to ~.
,~ It is preferably , - 5 -'.1 4~"' 1 ~ 6~03~
provided that where x = 2~ y = O and R = phenyl or 4-substituted phenyl the liquid crystal material (and the solution) has a negative dielectric anisotropy.
~yes o~ ~ormula (I) other than those ~or which x = 2, y = O and R = phenyl or 4-substituted phenyl may be dissolved, aocording to the first aspeot o~ the invention, in a liquid crystal material having ei-ther a positive or negative dielectric aniso-tropy.
It is well known to those skilled in the liquid crystal art tha-t liquid crystal materials may have either a positive or negative dielectric anisotrcpy. ~xamples of materials, and guest-host devices containing them, having respectively a positive and negative dielectric anisotropy are desoribed below.
Pre~erably~ ~RlR2 is ~HR1 where R1 is H~ monocyclic aryl~ especially phenyl or subs-tituted phenyl, or optionally substituted alkyl oontaining from 1 -to 5 oarbon atoms.
Preferred optional subs-ti-tuen-bs wheie R1 is substitu-~ed alkyl are lowe~ alkoxy~ OH and monooyolio aryl.
~20 Preferably~ R is monooyclic aryl~ especially phenyl or subs-tituted phenyl~
Where R or Q is alkyl i-t preferably contains up to 10 carbon atoms in a straight or branched chain and more preferably contains ~rom 3 -to 10 oarbon a-toms. As optional substitutents there are preferred lower alkoxy, OH ana monocyolic aryl.
Where Q is monooyclic aryl it is preferably phenyl or substituted phenyl.
- Where R~ Q, R1~ R2 or R is substituted phenyl it is preferably substituted by a lower alkyl~ lower alkoxy, halo~ ~2' ~ or ~R1R2 group (where ~R1R2 is as de~ined above) - which may be the same as or different ~rom the afore-mentioned group ~R1R2o ~he substituents are pre~erably in the meta or para position relative to the lir~ wi-th the anthraquinone nucleus. Preferred halo substituents are chloro and bromo.
Within the general class o~ compounds represented by Formula (I) a preferred sub-class o~ dyes may be represented by the formula:
~ (~ )y ~ormuaa (II) B o c wherein each o~ A, B and C independently represents H, -~R or -NR1R2 and ~ and y are as pre~iously de~ined.
Many of the dyes o~ Formula (I)~ particularly those o~
Formula (II)~ ha~e been ~ound to show particularly good stability and reasonable solubility as well as reasonably high order parame-ters in liquid crystal material, eg 4-n-alkyl-or -alkoxy-4t-oyanobiphenyl-based material, making them more attraotive -than the dyes disclosed in European Patent Speci~ioation No 210~A.
Particular mention may be made o:~ dyes o~ Formula (II) wherein y = 0 and wherein o~ the -three groups A, 3 and C two are -SR groups and the third is E particularly where R is aryl;
and o~ dyes o~ Formula (II) wherein y = 0 and of the three groups A, B and C one is -NR1R2 and the o-ther -two are hydrogen or one is hydrogen and the other two are -NR1R2 groups. A
number o~ dyes o~ these forms have been ~ound to show exceptionally high solubility as well as high order parameter in liquid crystal material (as exempli~ied below).
I 1 6803~
Other preferred dyes within the sub-class represented by ~ormula (II) are those in which y = O and A = B = C = ~SR;
A = -SR and 3 = C = ~R1R2; ~ = SR and A = C = -NR1R2;
C = -SR and A = ~ R1R2; A = ~ = C = -NR1R2; A = C = ~ = H;
A = 3 = SR and C = ~R1R2; A = C = -SR and ~ = ~R1R2; and A = ~R1R2 and 3 = C = SR.
Dyes of Formula (II) wherein y = 0~ 3 _ SR~ A = H and C = H are also pre~erred, subject to the proviso that they are used only with liquid crystal materials having a negative dielectric anisotropy Subject to the same proviso, the liquid crystal material (host material) in which -the dye of Formula (I) is dissolved - in the first aspect above is not critical since a dye which shows reasonable solubility in one liquid crystal material is likely to show reasonable solubili-ty in other liquid crystal materials and also a dye which gives an improved order parameter in one liquid crystal material is likely to give an improved order parame-ter in other liquid crystal materials, as most popl~ar liquid cr~s-tal materials have a similar rod-like moleoular shape; however the order parame-ter of any dye will vary to a limited extent from hos-t-to-host.
Suitable host materials include:
a. mixtures having a positive dielectric anisotropy incorporating cyano'biphenyls preferably together with a ~ew per cent o~ a compound having a clearing point (liquid crystal to isotropic liquid transi-tion) above 150C (eg a cyano-p-terphenyl) such as the material E7, marketed by ~DH Chemicals Ltd, o~ 3room Road, Poole, Dorset7 England;
(composition given below.) b. mixtures having a positive dielectric anisotropy incorporating 1-(47-cyanophenyl) 4-alkylcyclohexane compounds preferably together also with a few per cent of a high clearing point compound such as a 1-(4'~cyanob'iphenyl3-4-alk~lcyclohexane compound; eg the material ZLI 1132;
~ 3 ~3~
c. mixtl~es having a positive dielectric anisotropy incorporating at least one cyanobiphenyl and at least one cyanophenylpyrimidine, preferably together also with a few per cent of a high clearing point compound, eg a cyanophenylpyrimidinephenyl compound, eg the material ROTN 30;
d. mixtures incorporating esters, eg containing bicyclo (2,2,2) octane and benzene rings; these generally have a weakly positive or negative dielectric anisotropy but the magnitude o~ the dielectric anisotropy may be enhanced by the addition of a dopant liquid crystal material having a strongly positive or strongly negative dielectric aniso-tropy as appropriate; suitable negative dopants are the dicyano compounds which are specified in claim 2 of 15 ~ UK Patent Application No 2,061,256A;
e. any other liquid crystal material incorporating one or more compounds selected from the following known families (where R = aIk~rl): .
R~;\r~\r Y~ xiv R <~ ~1~ t~-Y1 i R~Y~ xv ~ ~c~ <~Y, iii RO~Y~ xvi ~ ) m=1~2 iv Ro~Y, xvii F~ <,_xl Y
V R~Y~ X\ilii R~<~coo-xj-y, ~ c~7. o_ x1- y; x i ~ `R~
viii ~".~ X- y xx Q~c~ YI
iX RC)~--X--Y, . ~ ~CI
Y~i r~ y` ,~X ' i R~~
xii R~c- ~y I ~CXlli R-~>~-y xiii R.o~ xx~ R~
,, xxY R~COO~>~ -R
xx v'~ R~cl~~ C1~2,~t}-c~
I 1 ~8Q3~;
.
or derivatives of any of the these containing benzene rings wherein the benzine rings contain one or more substituents, eg fluoro;
where~3-is a trans -1,4 substituted cyclohexane rin~
~ i~ ~ 1,4 ~ubstituted bicyclo (2.2.2) octane ring, X1 i~ a 1,4 phenylene group ~ , or a 474 biphenylyl group ~ or a 2,6 naphthyl group ~ j and Ylis CN, or R , or OR or CO. O-X1-Y where Y is CN, or R or OR ; the de~inition of ~ being the ~ame as that of R.
Preferably, -the dye/liquid crystal solution contains at least ~.Sq by weight of the dye and preferably between about 0.~5% and 5~ by weight of the dye or more tpossibly up to 10%
by weight).
Solu-tions of dye and liquid crystal material may be made in a oonventional way simply by mixing the dye and the liquid crystal material together and then heating the mixture at about 80 C with s-tirring for about 10 minutes and then allowing the mixture to cool.
Pleoohroio dyes of ~ormula (I) above may be mixed together with other dyes (whioh may or may not also be of ~ormula (I)) to extend their speo-tral absorption prop0rties (when dissolved in liquid orystal material). For exampletwhere a dye o~
~ormula (I) is a yellow or red dye it may be mixed with a red or yellow dye respeo-tively and a blue dye. Alternatively, where a dye of ~ormula (I) is orange it may be mixed together with a blue dye~ optionally -together with a yellow and/or red dye. ~he relative proportions of the ~yes mixed together are determined by the desired speotral response as determined by the extenotion coefficients of the consti-tuent dye compounds. ~he dye mixture is then used with liquid crystal material as above or as ~ollows.
According to the present invention in a second aspect a liquid crystal electro-optical display includes two electrically insulating substrates at least one of which is optically transparent, electrodes on the inner surfaces of the substrates . .
~ 1 ~803~
.
and a film of dielectric material contained between the electrodes and substrates, wherein the dielectric ma-terial is material according to the first aspect of the invention as defined above.
The liquid crystal/dye solution which is the material according to the first aspect of the invention may be used in any known electro-optical display as defined in the second aspect. Examples~ which will be familiar to those skilled in the liquid crystal art, are the known devices operating by the following effects:
a. THE ~WIS~ED NEMATIC EF~EC~
In this case a film of nematic liquid crystal material of posi-tive dielectric anisotropy has an off state in which (the long axes of) its molecules lie in the plane of the device substrate inner surfaces (which are normally parallel to one another), or at a small angle thereto, and.undergc roughly a ~/2 helical twist in orientation from one subs-trate -to -the other by virtue o~ the orientations at the surfaces caused by treatment~ eg unidirectional rubbing, of -those surfaces prior 20 to assembly. ~his is the -twisted l'homogeneous texture".
Applicaticn of an electric field between the elec-trodes on the respeoti.ve substrate inner surfaces to give -the on s-tate causes re-arrangement of the liquid crys-tal molecules -to lie (with their long axes) effec-tively perpendicular to -the substrate 25 inner surfaces in the "homeotropic texture". A change in optical ac-tivity (rotary power) of the film occurs between the on and off states by virtue of the mol.ecular re-arrangement.
and the optical effect observed can be enhanced by the use of a linear polariser adjacent to one of the substrates and 30 pleochroic dye dissolved in the liquid crystal ma-terial. ~he polariser has its polarisation axis parallel to the direction of the liquid crystal mclecules at the adjacen-t subs-trate inner surface (or, more strictly, parallel tc the average 1 ~ 68 03 G
axis of projection of the molecules on -that surface). ~y the guest-host effect the dye causes the off state to appear relatively dark or strongly colour whereas the on state appears olear or weakly ooloured.
b. ~Hæ ~K~ERICKS~ E~FEC~ EGATIVE ~EMATICS
In this oase a film of nematio liquid orystal material of negative dielec-tric anisotropy has an off state in which its molecules lie perpendicular (ie in the homeo-tropic texture) to the substrate inner surfaces (which are parallel) by virtue of surface treatments to these inner surfaoes prior to assembly. A single polariser is placed adjacent to one substrate with its transmission axis perpendicular to the normal to the inner surfaces. Application of an electric field between the elec-trodes on the respeo-tive substrate inner surfaoes to give -the on state causes re-arrangement of the liquid crystal mcleoules to lie parallel to the substrate inner surfaces (ie in the homogeneous texture). Incorporation of pleochroic dye in the liquid crystal material ensures that the off s-tate appears relatively clear or weakly coloured whereas the on s-ta-te appears dark or s-trongly ooloured. The effeot observed is eMhanoed by the presence of the polariser.
c. THE ~h~ ERICKSZ EFFECT I~ POS~IVE ~EMA~ICS
In this oase a nematio liquid crystal material of positive dieleotrio anisotropy has an off state in which the moleoules lie roughly parallel and in the plane of the substrate inner surfaoes (whioh are parallel) by virtue of treatment of those surfaoes prior to assembly (ie the homogeneous texture).
A single polariser is placed adjacent to one substrate with its transmission axis parallel to the substrate inner surfaces.
Applioation of an electric field between the electrodes on the respeotive substra-te inner sur~aces to give the on state causes re-arrangement of the liquid crystal mclecules tc lie perpendicular to the substrate inner surfaoes~ ie -the homeotropic texture. Incorporation of pleochroic dye in the ~ 1 6803~
liquid crystal material ensures that the off state appears relatively dark or strongly coloured whereas the on state appears colourless or weakly coloured as in the twisted nematio effect above. 'rhe effeot observed is enhanced by the presence of the polariser.
d. 'rHE PHASE CHA~GE Ehh~CT (NEGA'rIVE CON'rRAS'r 'rYPE) In this case a oholesterio liquid crystal material of positive dielectric anisotropy and long molecular helical pitch, typically3 ~m, has an cff state in which its molecules 10 ~ lie in random helices, ie the "fccal conic texture".
Application of an eleotric field between the electrodes on -the respeotive substrate inner surfaces to give the on state causes re-arrangement of -the liquid orystal molecules to lie perpendicular to the substrate inner surfaces (ie the homeotropic texture as for postive nematics in the ~rëedericksz effect). Inoorporation of pleoohroic dye in the Iiquid crystal material gives an of`f s-ta-te which appears relatively dark or strongly ooloured and an on state which appears cclourless or weakly ooloured.
e. ~rHE PHASE CHANGE E~EC'r (POSI~IVE CONTRAS'r ~YPE) In -this case a cholesterio liquid crystal material of negative dieleotric anisotropy and long moleoular helioal pitoh has an off sbate in which its moleoules lie perpendicular -to -the substrate inner surfaces, ie in the homeotropic texture.
Applioation of an eleo-trio field be-tween electrodes on the respec-tive substrate inner surfaces causes re-orienta-tion of the moleoules to lie in the plane of the substrate inner surfaces in a helioal arrangement ie the twisted homogeneous texture. Inoorporation of pleoohroic dye in the liquid crystal material gives an off state which is relatively oolourless or weakly coloured and an on state whioh is relatively dark or strongly oolouredJ
1 16~03G
f. ~HE ~REEDERICKSZ EFFEC~ IN SMECTICS
In this case a smectio A liquid crystal material of positive dielectric anisotropy having a dielectric relaxation frequency fc less than about 10 kHz (ie the material has a negative dielectric anisotropy above this frequency) has an off state in which its molecules lie roughly parallel to the substrate inner surfaces with the molecules at the two inner surfaces parallel as in the Freedericks~ effect (c).
Application of an electric field with a frequency less than fc to give the on state causes re-orientation of the liquid crystal molecules to lie perpendicular to the substrate inner surfaces, is in the homeotropic texture. ~he on state is preserved when the field is removed. Clearing of the on state may be achieved by the application of a high frequency elec-tric field, ie with a frequency> fc. A single polariser is used, as with the ~reedericks~ effect (c) abcve, when the molecular alignmen-t at the two substrate inner surfaces in the off state is parallel. Incorporation of plecchroio dye in the liquid crys-tal ma-terial gives an off s-tate which is relatively dark or strongly coloured and an on state which is clear or weakly ooloured.
Use of the material defined in -the first aspeo-t of the invention above is not limi-ted to eleotro-op-tioal displays (as defined in the seoond aspeot). The material may, in fact, be used in any known application of a dyed liquid crystal material. An example of such a Inon electro-optical' appli-oation is a thermally addressed display in whioh a symbol or oharacter is provided in a smectic or cholesteric material by selective heating of the material eg by a laser (eg He/~e) beam, to produce a localised change in the molecular texture of the material. ~he dye enhances the contrast between the different regions of the display, ie between those which are selectively heated and those which are not heated.
1 3 6gO3~
An-thraquinone dyes falling wi-thin the scope of Formula (I), and Imethods for -their preparation, have been described in the prior art. Thus, methods for the preparation of alpha-phenylthioanthraquinones have been described in United Kingdom Patent Specifioation No 1105568. In general, such methods involve reacting an anthraquinone compound have replaceable subs-tituents in the alpha positioning with a thiophenol in the presenoe of a base and a suitable reaction medium. Beta-phenylthioanthraquirlones may be prepared in an analogous manner.
~or the purposes of the present invention, the anthra-q~inone compounds of Formula (I) should be of ex-tremely high purity as will be obvious to those skilled in the art.
Purification may be effected using oonven-tional methods such as recrystallisation from suitable solven-ts and chromatography.
Examples of the preparation and properties of dye compounds having ~ormula (I) will no~r be given:
EXA~L~ Preparation OI Compound ~o 1: 1,5-bis(phenylthio) anthraquinone~
1,5-Diohloroanthraquinone (100 parts) is added at room temperature with s-tirring to a mixture of dimethylformamide (474 parts), -thiophenol (135 parts) and potassium oarbonate (63 parts). 'rhe suspension is heated at 125C for 3 hours, cooled -to room tempera-ture and then cooled to 5 C for 1 hourO
~he precipita-te is filtered off and washed with a 50/50 mixture of 95% ethanol and 8% sodium hydroxide solution (2 x 250 parts).
The filter cake is then slurried with a further 500 parts of the ethanol/sodium hydroxide solution mix-ture. After stirring at room temperature for 1 hour, the precipitate is filtered off 3o and washed aga.in with ethanollsodium hydroxide solution mixture (5 x 100 parts), followed by water (250 parts) containing glacial acetic acetic acid (25 parts) and finally water (3 x 250 parts). ~he filter--cake is dried at 70 C giving 140.4 parts of 1,5-bis(phenylthio) anthraq~inone, mp (melting point) 256C.
~ ~ ~803~
~s Examples 2-24 the compounds listed in ~able I below having the following general ~ormula:
Rg ~1 7 ~ ~ ~ ormula (III) R~ 3 R~ R4 are each made by a similar method to that described in Example 1 with the appropriate quantity of the appropriate mono-~ di-, tri~ or tetrA_chloro anthraquinone and the appropriate mercaptan.
1 3 6803~
X X ~ X P~
X ~ P~ X ~ X ~q ~' Pi : :
:: :
8 o o o o ~ o ,_ o ~ ~ ~
~ o C\l o ~
o o~
1~ CO 0~ 0 ~ C\l ~ ~ IS~ O
:
O
, ~ P~
V~
V~
.
' O ~ N r~
~ ~ ~ N N N N N
O
~ .
68~3 100 g of -the sodium salt of 1-ni-tro-anthraquinone-5-sulphonic acid is boiled in 500 g water to give a partial solution and oooled to room temperature. 150 g of concentrated sulphTlric acid is added dropwise over 10 minutes and the mixture heated to reflux temperature. 330 g of a mixed sodium chlorate/sodium chloride solution containing 30.8 g sodium chlorate and 33.6 g sodium chloride is added over a period of 6 hours and the mixture refluxed for a further 3 hours~ At the end of this period the mixture is filtered hot~ washed with 800 g of hot wa-ter and dried at 80 C~ ~he product is 1-nitro-5-chloroanthraquinoneO (69.3 g: purity by HPLC 92~o).
A solution of 39.1 g phenyl mercap-tan in 62 ml dime-thyl-formamide containing 16 g potassium carbonate is prepared by heating at 100 C for 2 hours and cooled to 40C. Ethanol (250 ml) and 36.2 g of -the 1-nitro-5-chloroanthraquinone are added and stirred for 16 hours a-t 40C and allowed to cool to room temperature over ~8 hours. ~he product is fil-tered washed with 46~o aqueous ethanol (-l- li-tre) slurried in 40~0 aqueous ethanol (250 ml) s-tirred for 30 minutes, filtered and washed with 100 ml o~ 40~0 aqueous ethanol and ~inally with 2 litre of water. It is then reslurried in 250 ml water? stirred for 30 minutes~ filtered,washed with 250 ml water and 50 ml 20~o aqueous ethanol and dried at 80C~ The product is 1-phenyl-thio-5-chloroanthraquinone (43.9 g purity by HPLC 94.2%) (~ minor amounts o~ dithiophenyl-AQ and dichloro-AQ; AQ =
anthraquinone~
A mixture of 1.75 g 1-phenylthio-5-chloroanthraquinone, 0.4 g n-butylamine and 0.39 g potassium carbonate in 16 ml dimethylformamide is stirred at 120C for 3 hours after which a tlc runout indicates 66~o reactionO A further 0.4 g n-butyl-amine and 0 39 g potassium carbonate are added and reaction at 120C continued for a further 8 hours. The mixture is cooled to room temperature, 20 ml ethanol added it is filtered and then washed with 36 ml 2~ ~aOX/ethanol. The product is reslurried in ~ ~ fi803t~
30 ml of the ~aOH/e-thanol~ stirred for 30 minu-tes 9 fil-tered~
washed with 26 ml ~aOI-I/e-thanol, followed by 50 ml water and 36 ml of 50~0 aqueous ethanol and dried at 50C. This product is reorystallised from 200 ml of ethanol~-reduced -to 20 ml after filtration~ washed with ethanol and dried at 80C. The produot is 1-phenylthio-5-n-butylaminoanthraquinone (.95 g:
m.p. 140-142C).
~ .
A mixture of 3.12 g o~ tert-butyl phenyl mercaptan, 1.30 g potassium carbonate and 10 ml dimethylformamide are stirred at 120 C for 2 hours and cooled to r~om temperature. To t~is are added 3.14 g of 1-n-butylamino-5-chloroanthra~linone, prepared as described below~ and -the reactionmixture refluxed for 5 hours. It is then cooled to room temperature~ 20 ml of ethanol is added and -the product~ 1 n-butylamino-5--tert-butylphenylthio-anthraquinone isola-ted and purified using the me-thod described in the last stage of Example 25. q`he yield of product is 4.3 g in the form of a tar. q'his tar is di`ssolved in -toluene and passed through a silica colurnn using toluene as eluent and the rnain red fraotion oolleoted. After evaporating the toluene the produot is recrystàllised from ethanol and dried to gi~e a yield of 2.5 g of 91.5% purity by ~LC and m.p. 168-9C.
qlhe 1-n~butylamino-5-chloroanthra~inone used above is prepared by heating a mixture of 17 g 1-nitro-5-chloroanthraqulnone~ 5.1 g urea~ 106 ml ethanol and 18.7 g n-butylamine under reflux for 48 hours. After this period 5.1 g urea and 68 ml n-bu-tanol are added and refluxing continued for a further 16 hours. ~he reaction mixture is screened ho-t and -the fil-trates retained. The solid residue is washed wi-th butanol~ fil-tered hot and the filtrate retained.
q`he combined filtrates are cooled to 0C~ filtered after 2 hours a-t 0C and the solid product washed with bu-tanol. A~-ter drying at 80C the yield is 9 g and purity by HPLC is 82.8%.
~e~
A mixture of 2.97 g phenylmercaptan, 1.81 g potassium carbonate and 10 ml dimethylformamide are stirred at 120C for " :
I 1 6~03B
2 hours and cooled to room temperature. To this are added 2.07 g 1-nitro-4,5-dichloro-8-anilinoanthraquinone and heating at 120 C
continued for 5 hours. At the end of the reaction period the mixture is cooled to room temperature, diluted with 20 ml ethanol, filtered and the product washed on the filter with 20 ml 50%
aqueous ethanol. The first stage of purification involves reslurrying in 50% aqueous ethanol, 30 ml, stirring for 30 minutes, filtration, washing successively with 10 ml 50~o aqueous ethanol, 30 ml water, and 20 ml ethanol and drying at 80C to give a yield of 2.35 g. The second stage of purification involves dissolution in 100 ml chloroform, passage through a silica column using chloroform as eluent and collecting the blue band, evaporation of the solvent, decantation washing with 30 ml methanol, slurrying in 20 ml of 40/60 petroleum ether, filtration, washing with 20 ml of petroleum ether and drying at 80C. The yield of the product, 1 anilino-4,5,8-triphenylthioanthraquinone, is 2.3 g with m~p. of 289~290C and a purity by HPLC of 97.5%.
The 1-nitro-4,5-dichloro-8-anilinoanthraquinone used as starting material is prepared by stirring a mixture of 10 g of 1~4,5-trichloro-8-nitroanthraquinone, 75 ml "Cellosolve" (Trade Mark) and 7.o3 g aniline for 18 hours at 120C. The product is isolated by cooling to room temperature, filtration, washing with 50 ml ethanol, reslurrying with 50 ml ethanol and filtration, mixing solid with 50 ml 2N HCl filtration, washing acid-free wit~
water (200 ml) and drying at 80C. The crude product, yield 8.6 g, is purified by recrystallisation from chloroform, 50 ml, washing with a further 50 ml of chloroform and drying at 80C.
The yield is 5.9 g, the purity, by HP~C, 90.5~ and the m.p.
216-217C.
continued for 5 hours. At the end of the reaction period the mixture is cooled to room temperature, diluted with 20 ml ethanol, filtered and the product washed on the filter with 20 ml 50%
aqueous ethanol. The first stage of purification involves reslurrying in 50% aqueous ethanol, 30 ml, stirring for 30 minutes, filtration, washing successively with 10 ml 50~o aqueous ethanol, 30 ml water, and 20 ml ethanol and drying at 80C to give a yield of 2.35 g. The second stage of purification involves dissolution in 100 ml chloroform, passage through a silica column using chloroform as eluent and collecting the blue band, evaporation of the solvent, decantation washing with 30 ml methanol, slurrying in 20 ml of 40/60 petroleum ether, filtration, washing with 20 ml of petroleum ether and drying at 80C. The yield of the product, 1 anilino-4,5,8-triphenylthioanthraquinone, is 2.3 g with m~p. of 289~290C and a purity by HPLC of 97.5%.
The 1-nitro-4,5-dichloro-8-anilinoanthraquinone used as starting material is prepared by stirring a mixture of 10 g of 1~4,5-trichloro-8-nitroanthraquinone, 75 ml "Cellosolve" (Trade Mark) and 7.o3 g aniline for 18 hours at 120C. The product is isolated by cooling to room temperature, filtration, washing with 50 ml ethanol, reslurrying with 50 ml ethanol and filtration, mixing solid with 50 ml 2N HCl filtration, washing acid-free wit~
water (200 ml) and drying at 80C. The crude product, yield 8.6 g, is purified by recrystallisation from chloroform, 50 ml, washing with a further 50 ml of chloroform and drying at 80C.
The yield is 5.9 g, the purity, by HP~C, 90.5~ and the m.p.
216-217C.
3 Example ~8 The procedure of Example 27 is repeated except that in place of the 2.97 g of phenylmercaptan there is used 4.49 g of
4-tert-butylmercaptan. After isolation and purification in the 1 3~8~36 same manner the yield of 1-anilino-4,5,8-tri(4'-tert-butyl-phenylthio)anthraquinone is 2.65 g of 91.5% purity by HPLC and m.p. 266-268C.
Example 29 A mixture of 8.96 g of 4-tert-butylphenyl mercaptan, 3.73 g potas6ium-~arbonate and 10 ml dimethylformamide is stirred at 120C for 1 hour and cooled to room temperature. To the mixture is added 3,12 g 1,4,5-trichloanthraquinone ~nd reaction continued for 18 hours at reflux. After cooling to room temperature and dilution with 20 ml ethanol the product is isolated and purified as as described in Example 26 to give 2.1 g of 1,4,5-tri(4'-tert-butyl-phenylthio)-anthraquinone m.p. 228-229C and purity by ~PLC 86.6%.
E _mple 30 A mixture of 3.5 g 1-phenylthio-5-chloroanthraquinone, as prepared in Example 25~ 2.5 ~ anhydrous sodium acetate, 0.15 g cupric acetate, 0.05 g copper powder and 25 g aniline are refluxed at 190C for 16 hours and cooled to room temperature.
~he product is slurried in 200 ml 2N ~CL the liquor decanted and a further 200 ml 2N HCL added. The solid material is separated by filtration, reslurried into 200 ml water and filtered. ~he solid matter is dissolved in 100 ml chloroform, filtered through a silica plug and the filtrate evaporated to dryness. The dry material is then dissolved in 50% toluene/chloroform (100 ml) passed through a silica column using toluene as eluent and main red band is collected and separated from solvent by evaporation.
The purification on a silica column is repeated using toluene alone a~ solvent and the resultant product is mixed with ethanol, filtered and dried at room temperature, yield 2.~ g consi~ting of 71.4% 1-anilino-5-phenylthioanthraquinone and 27.6~ 1,5-bis-phenylthioanthraquinone. This material is boiled in 100 ml of 50:50 chloroform:ethanol until chloroform has evaporated, cooled to room temperature~ filtered, washed with ethanol and dried at I 1 6~03~;
50C. The yield of 1-anilino-5-phenylthioanthraquinone is 1~4 g with m~p~ 210-212C~
~3~
~ mixt~re of 40 g 4y5-dinitrochrysazin~ 800 ml pyridine is stirred and cooled to -30C and 14.6 g thiophenol is added over 5 minutes. The rea~-tion mixture is held at -30C ~or 3 hours~ warmed to room temperature, dil~ted with 800 g water and allowed to s-tand for 16 hours. ~he precipitate is ~iltered~ wa~hed with pyridi~e/water~ water and reslurried and boiled wi-th a dilute solution o~ HCl. After reflltration the ~olid is wa6hed with methanol and extracted twice with methanol.
~he final yield after two recrystallisations from toluene is 12.5 g.
4 g of this product is reduced with 9.6 g sodium sulphidet 9H20 and 1.25 g sulphur in wa-ter a-t 90C ~or 3 hours.
~he product is filtered hot and washed with hot wa~er. ~liS
produot is separated into ~e~en components on a silica column using methanol as eluent and bands 4 and 7 collected. HPLC and Mas~ Spectral c~nalysis show th~se to be essen-tially 1,8-dihydro~y-2,5-di--thiophenyl-4-aminoan-thraquinone (Compound 31) and 1,8-dihydroxy-?-thiophen~l-4,5-diaminoanthraquinone (Compound 12).
Examples of properties of Compound Nos. 1 to 27 will now be given. In relation to the properties the following symbols are u6ed:
~ max = wavel~ngth(s) of maximum absorption (nm) 801 = solubility (weight % measured at 20C~
S = order parameter (measured at 20C) and the following liquid crystal hosts are referred to:
i Host A which is tho commercially available material E7 (having a positive dielectric ani60tropy) supplied by BDH Chemicals Ltd~ Broom Road, Poole, Dor~et, England : this consists of a mixture of cyanobiphenyls and a cyano-p-terphenyl.
J 1 ~8V3~;
ii Host B~ which is the commercially available material E4~
(having h positive dielectric anisotropy) supplied by BDH Chemicals Ltd, this consists of a mixture of cyanobiphenyl6, a cyano-p-terphenyl and a cyanobiphenylcyclohexane compound.
iii Host C, which is the commercially av~ilable material ZLI 11 ~upplied by E Merck Co., Postfach 4119, 6100 Dar~6tadt 1, German Federal Republic; this consi~ts of a mixture having a positive dielectric anisotropy of 1-(4~-cyanophenyl)-4~n-aIkylcyclohexane ~PCX) compounds and a cyanobiphenylcyolohexane compound.
iv Host D, which is the commercially available material ZLI 1565 supplied by E Merck Co; this has a positive dielectric ani~otropy and compri6es ~ainly a mixture of PCH cGmpounds;
v Host E~ which i6 the commercially available material ZLI 1624 supplied by E Merck Co; this has a positive dielectric anisotropy and compriseg mainly a mixture of PCH oompounds;
vi Host ~ which has a composition:
~3~7~Cx~ q sox by weight ~ ~C s~ ~ c ~ q~~ 50% by weight _ This has a weak dielectric anisotropy but may be formed into a m~terial having a negative dielectric anisotropy by the addition of a small amount~eg 10~ by weight,of 'negati~e' dopAnt, eg C~H~4~coo~c-ooC~Js without significantly affecting its other properties.
Properties of Compound~ Nos 1 to 31 (~hich are the products of Example No~ 1 to 31 respectivelv a~ disclosed above) havc been found as listed in ~able II.
An additional property of Compound No 1 i8 as follows:
S in ~ost F = 0.82 I 1 ~8036 Additi,onal properties, o~ Compound No. 2 are as follows:
S in Host A = 0.73 S in Host C = 0.8 S in Host D = 0.7 S in Host E = 0.78 The photostability of Compound Nos. 1 to 27 has been measured using (i) ultra-violet radiation (0.2 mw cm 2 at 20C) and (i) ultra-violet plus visible radiation from a Xenon Arc (1.5 kw at 40C). All of the Compounds showed good photostability at least comparable with the photostability of the anthraquinone dyes dis-closed in the abo~e mentioned European 5pecification. For example, the time taken for the absorbance of Compound No. 2 to fall to 90%
of its original value was greater than 10000 hours for (i) and about 5000 hours for (ii) compared to 600 hours for (i) and 80 hours for (ii) -Eor the compound 1-(4'-n-nonoxyanilino)-4-hydroxyanthra~uinone disclosed in the above mentioned F.uropean Specification.
A suitable dark grey mixture made from dyes including Compounds of Formula (I) is as follows:
Dye Mixture No. 1 Compound No. 1 (yellow) 2.0 parts by weight Compound No. 2 (red) 1.0 parts by weight Dye A (blue) 0.8 parts by weight Where Dye A (as disclosed in our copending Canadian Patent Application No. 382,705~has the following formula:
HO O OH
(CH3)2CHcH2_ ~ CH2CH(CH3~2 I ~ 88(~3~
Table II: Properties of ~e Co ~._ Compound ~o S ~n Host A S in Host ~ Sol in Eost ~ ~ max (nm~
1 0.80 1 447, 455 2 0.8 1 524, 554 3 o.55 595, 638 4 0.56 589, 620 -7 542, 580 6 .57 545, 582 7 o.58 544, 5g2 8 0.61 542, 580 9 0.61 542, 580 o 0~52 53, 580 11 0.61 520, 558 12 0.61 605, 645 13 0.60 9* 445 14 0.51 515 o.60 520 16 0~71 o.78 600, 650 17 0.75 52~, 554 18 .75 524, 554 19 0.73 447, 455 o.78 447. 455 21 o.78 >4.0 5, 518 22 o.78 1.5 565, 605 23 o.78 l.o 500y 520 24 1.5 520 0.72 >4.0 520 26 0.68 >4.0 520 27 0.72 1.5 585, 612 *in Host A
.
~ ~ 6~36 Compound ~o S in Host A S in Host ~ Sol in Host B ~ m~x (nm) 28 0.70 585~ 615 29 0.73 > 4.0 500, 525 3 0.70 3.5 485, 520 31 0.73 Examples of liquid erystal deviees embodying the secoNd aspect of the present invention will now be deseribed with referenee to the aeeompanyin~ drawings in whieh:
Figure 1 is an exploded view of a Fréedericksz effeet display devioe embodying the present invention, Figure 2 is a seetional view of the device shown in Figure 1;
and Figure 3 is a front view of a wateh having a liquid crystal display eonstrueted as shown in Figures 1 and 2.
As shown in Figure 1 a liquid crystal display of the Fréedericksz effeet tpositive nematic) type ineludes a liquid crystal cell 3 comprising two glass slides 4, 5 containing a layer of liquid erystal material 6 which is basically a positive nsmatie mayerial together with a pleochroic dye. Electrodes 7~ ~ eg of tin oxide are arranged on the inner faces of the slides 4, 5, A
brushed aluminiu~ reflector ~7 may be loea~ed behlnd the sllde 5.
7 1 6803~
Prior to assembling the cell 3 the slides 4, 5 (already bearing the electrodes 7, 8) are coated on their inner faces with silicon monoxide or magnesium fluoride. This coating is formed by evaporating a stream of eg silicon monoxide onto the slide at an angle of about 5 to the surface as for example described in UK Patent Specification No 1,454,296. On assembly the slides are arranged with the evaporation direction on the two slides 4, 5 parallel to one another. With such coatings applied liquid crystal molecules at the coated surfaces lie in a single direction (parallel to the evaporation direction) and at an angle of about 25 to 35 typically about 30 to the adjacent slide surface. As a result the liquid crystal molecules lie in a parallel homo-geneous texture as indicated by arrow 13 (Figure 1). The dye molecules in guest-host relationship with the liquid crystal molecules are also roughly in this texture giving a relatively strongly coloured appearance to the cell 3 (which is black or grey if the dye absorbs uniformly throughout the visible spectrum).
A single polariser 1 placed in front of, or behind, the cell 3 (shown in front in Figure 1) with its transmission axis parallel to the alignment direction of the liquid crystal material 6, will enhance the colour of the display in this state, the "off" state.
By this arrangement the electric vector of the incident or refelcted light is confined rou~hly parallel to the transition of the dye molecules.
When a suitable voltage, eg a few volts, (greater than the threshold to give the effect) i6 applied between the electrodes 7 and 8, ie to give the "on" state, the molecules of the liquid crystal material are switched to the homeotropic texture, ie to lie parallel to the electric field along an axis perpendic~lar to the slides 4, 5. The dye molecules are also switched to this I 1 6803~
texture by the guest-host effect and have their long axes essen-tially parallel (ie they are essentially "end-on") to li~ht incident on the cell 3 in a direction perpendicular to the slides l~, 5, effcctively reducing their absorp'ion of ambient light.
This gives the cell 3 a relatively clear or weakly coloured appearance.
If the electrcdes 7 and 8 cover only part of the inner surface of the slides 4 and 5 respectively the entire cell 3 will appear strongly coloured (ie strongly reflects! in the "off"
state whereas in the "on" state only the region of the liquid crystal material 6 between the electrodes 7, 8 will appear clear or weakly coloured in the "on" state the remainder of the cell 3 appearing strongly coloured, ie remaining in the "off" state.
(If the pleochroic dye absorbs uniformly throughout the visible spectrum the strong colouration will appear black or grey.) Thus, by shaping the electrodes 7, 8 into discrete f~cing partsj eg bars of a digit separately connectable to a voltage source (not shown),symbols or letters may be displayed. This may be achieved by photoetching ~in a known way) the layers, eg SnO2, used to form the electrodes 7, 8 prior to assembly.
For example, in the watch display of Figure 3 the electrodes 7, 8 are shaped to provide ~our seven bar numerîc digits to display time; eg the digits are displaying 12.45 as shown in Figure 3. A pulsed period dot P is also included, as in conven-tional watch displays, to indicate operation of the display.
~ xamples of suitable dyed liquid cr~stal material for use asthe ~aterial 6 above are Dye Mixture No 1 (about 1X by weight) defined above dissolved in one of the two hosts Host A and ~o~t B defined above (the thickness of the material 6 layer being 12 ~m).
I ~ 68(~3{~
3o In an alternative device embodying the second aspect of the present invention a cholesteric to nematic phase change effect i8 made in a known way. The method of construction is the same a6 that described above with reference to Figures 1 to 3 except that no MgF2 or SiO coating is applied to the inner surfaces of the electrode bearing slides 4, 5, no polariser 1 is required and the liquid crystal material 6 in this case is essentially a long pitch cholesteric material (having R molecular helical pitch of the order of about 2 ~m containing a pleochroic dye. A suitable material is one of the two hosts Host A and B de~ined abo~e modified by the inclusion of 5~ by weight of CB15 as defined below and containing the Dye Migture No 1 defined above (about 1X by weight) ~the thicknes6 of the material 6 layer again being 12~m).
In the ~Offn state (with no voltage ap~lied) the cell 3 again appearg strongly coloured in this case (as in the Fr~eedericksz ef~ect device). The liquid crystal material 6 in this state i5 in the focal conic texture which compri~es an arrangement of random molecular helicesO The dye molecules take up the same arrangement by the guest-host ef~ect. ~he strong colouration (which may be black or dark grey) is because ambient white light incident on the material 6 via the slide 4 i8 partially absorbed by the dye molecules which are perpendicular or oblique to the light propagation direction~
In the "on" state a voltage (typically 10-15 volts) is applied between the electrodes 7, 8 sufficient to give the homeotropic texture, ie with the liquid crystal molecules between the electrodes 7, 8 es~entially re-orientated to lie perpendicular to the slidee 4, 5. The dye milecules between the elctrodes 7, 8 are re-orientated to this arrangement by the guest-host effect.
~o The region between the electrodes 7, 8 appears clear or weakly coloured in this state (RS with the Fréedericksz effect device) because the dye molecules are ~ssentially "end-on" to ambient light propagating in a direction perpendicular to the cell 3, ie perpendicular to the slides 4, 5 ~via the slide 4).
3 2 3 2 ~ - CN
Example 29 A mixture of 8.96 g of 4-tert-butylphenyl mercaptan, 3.73 g potas6ium-~arbonate and 10 ml dimethylformamide is stirred at 120C for 1 hour and cooled to room temperature. To the mixture is added 3,12 g 1,4,5-trichloanthraquinone ~nd reaction continued for 18 hours at reflux. After cooling to room temperature and dilution with 20 ml ethanol the product is isolated and purified as as described in Example 26 to give 2.1 g of 1,4,5-tri(4'-tert-butyl-phenylthio)-anthraquinone m.p. 228-229C and purity by ~PLC 86.6%.
E _mple 30 A mixture of 3.5 g 1-phenylthio-5-chloroanthraquinone, as prepared in Example 25~ 2.5 ~ anhydrous sodium acetate, 0.15 g cupric acetate, 0.05 g copper powder and 25 g aniline are refluxed at 190C for 16 hours and cooled to room temperature.
~he product is slurried in 200 ml 2N ~CL the liquor decanted and a further 200 ml 2N HCL added. The solid material is separated by filtration, reslurried into 200 ml water and filtered. ~he solid matter is dissolved in 100 ml chloroform, filtered through a silica plug and the filtrate evaporated to dryness. The dry material is then dissolved in 50% toluene/chloroform (100 ml) passed through a silica column using toluene as eluent and main red band is collected and separated from solvent by evaporation.
The purification on a silica column is repeated using toluene alone a~ solvent and the resultant product is mixed with ethanol, filtered and dried at room temperature, yield 2.~ g consi~ting of 71.4% 1-anilino-5-phenylthioanthraquinone and 27.6~ 1,5-bis-phenylthioanthraquinone. This material is boiled in 100 ml of 50:50 chloroform:ethanol until chloroform has evaporated, cooled to room temperature~ filtered, washed with ethanol and dried at I 1 6~03~;
50C. The yield of 1-anilino-5-phenylthioanthraquinone is 1~4 g with m~p~ 210-212C~
~3~
~ mixt~re of 40 g 4y5-dinitrochrysazin~ 800 ml pyridine is stirred and cooled to -30C and 14.6 g thiophenol is added over 5 minutes. The rea~-tion mixture is held at -30C ~or 3 hours~ warmed to room temperature, dil~ted with 800 g water and allowed to s-tand for 16 hours. ~he precipitate is ~iltered~ wa~hed with pyridi~e/water~ water and reslurried and boiled wi-th a dilute solution o~ HCl. After reflltration the ~olid is wa6hed with methanol and extracted twice with methanol.
~he final yield after two recrystallisations from toluene is 12.5 g.
4 g of this product is reduced with 9.6 g sodium sulphidet 9H20 and 1.25 g sulphur in wa-ter a-t 90C ~or 3 hours.
~he product is filtered hot and washed with hot wa~er. ~liS
produot is separated into ~e~en components on a silica column using methanol as eluent and bands 4 and 7 collected. HPLC and Mas~ Spectral c~nalysis show th~se to be essen-tially 1,8-dihydro~y-2,5-di--thiophenyl-4-aminoan-thraquinone (Compound 31) and 1,8-dihydroxy-?-thiophen~l-4,5-diaminoanthraquinone (Compound 12).
Examples of properties of Compound Nos. 1 to 27 will now be given. In relation to the properties the following symbols are u6ed:
~ max = wavel~ngth(s) of maximum absorption (nm) 801 = solubility (weight % measured at 20C~
S = order parameter (measured at 20C) and the following liquid crystal hosts are referred to:
i Host A which is tho commercially available material E7 (having a positive dielectric ani60tropy) supplied by BDH Chemicals Ltd~ Broom Road, Poole, Dor~et, England : this consists of a mixture of cyanobiphenyls and a cyano-p-terphenyl.
J 1 ~8V3~;
ii Host B~ which is the commercially available material E4~
(having h positive dielectric anisotropy) supplied by BDH Chemicals Ltd, this consists of a mixture of cyanobiphenyl6, a cyano-p-terphenyl and a cyanobiphenylcyclohexane compound.
iii Host C, which is the commercially av~ilable material ZLI 11 ~upplied by E Merck Co., Postfach 4119, 6100 Dar~6tadt 1, German Federal Republic; this consi~ts of a mixture having a positive dielectric anisotropy of 1-(4~-cyanophenyl)-4~n-aIkylcyclohexane ~PCX) compounds and a cyanobiphenylcyolohexane compound.
iv Host D, which is the commercially available material ZLI 1565 supplied by E Merck Co; this has a positive dielectric ani~otropy and compri6es ~ainly a mixture of PCH cGmpounds;
v Host E~ which i6 the commercially available material ZLI 1624 supplied by E Merck Co; this has a positive dielectric anisotropy and compriseg mainly a mixture of PCH oompounds;
vi Host ~ which has a composition:
~3~7~Cx~ q sox by weight ~ ~C s~ ~ c ~ q~~ 50% by weight _ This has a weak dielectric anisotropy but may be formed into a m~terial having a negative dielectric anisotropy by the addition of a small amount~eg 10~ by weight,of 'negati~e' dopAnt, eg C~H~4~coo~c-ooC~Js without significantly affecting its other properties.
Properties of Compound~ Nos 1 to 31 (~hich are the products of Example No~ 1 to 31 respectivelv a~ disclosed above) havc been found as listed in ~able II.
An additional property of Compound No 1 i8 as follows:
S in ~ost F = 0.82 I 1 ~8036 Additi,onal properties, o~ Compound No. 2 are as follows:
S in Host A = 0.73 S in Host C = 0.8 S in Host D = 0.7 S in Host E = 0.78 The photostability of Compound Nos. 1 to 27 has been measured using (i) ultra-violet radiation (0.2 mw cm 2 at 20C) and (i) ultra-violet plus visible radiation from a Xenon Arc (1.5 kw at 40C). All of the Compounds showed good photostability at least comparable with the photostability of the anthraquinone dyes dis-closed in the abo~e mentioned European 5pecification. For example, the time taken for the absorbance of Compound No. 2 to fall to 90%
of its original value was greater than 10000 hours for (i) and about 5000 hours for (ii) compared to 600 hours for (i) and 80 hours for (ii) -Eor the compound 1-(4'-n-nonoxyanilino)-4-hydroxyanthra~uinone disclosed in the above mentioned F.uropean Specification.
A suitable dark grey mixture made from dyes including Compounds of Formula (I) is as follows:
Dye Mixture No. 1 Compound No. 1 (yellow) 2.0 parts by weight Compound No. 2 (red) 1.0 parts by weight Dye A (blue) 0.8 parts by weight Where Dye A (as disclosed in our copending Canadian Patent Application No. 382,705~has the following formula:
HO O OH
(CH3)2CHcH2_ ~ CH2CH(CH3~2 I ~ 88(~3~
Table II: Properties of ~e Co ~._ Compound ~o S ~n Host A S in Host ~ Sol in Eost ~ ~ max (nm~
1 0.80 1 447, 455 2 0.8 1 524, 554 3 o.55 595, 638 4 0.56 589, 620 -7 542, 580 6 .57 545, 582 7 o.58 544, 5g2 8 0.61 542, 580 9 0.61 542, 580 o 0~52 53, 580 11 0.61 520, 558 12 0.61 605, 645 13 0.60 9* 445 14 0.51 515 o.60 520 16 0~71 o.78 600, 650 17 0.75 52~, 554 18 .75 524, 554 19 0.73 447, 455 o.78 447. 455 21 o.78 >4.0 5, 518 22 o.78 1.5 565, 605 23 o.78 l.o 500y 520 24 1.5 520 0.72 >4.0 520 26 0.68 >4.0 520 27 0.72 1.5 585, 612 *in Host A
.
~ ~ 6~36 Compound ~o S in Host A S in Host ~ Sol in Host B ~ m~x (nm) 28 0.70 585~ 615 29 0.73 > 4.0 500, 525 3 0.70 3.5 485, 520 31 0.73 Examples of liquid erystal deviees embodying the secoNd aspect of the present invention will now be deseribed with referenee to the aeeompanyin~ drawings in whieh:
Figure 1 is an exploded view of a Fréedericksz effeet display devioe embodying the present invention, Figure 2 is a seetional view of the device shown in Figure 1;
and Figure 3 is a front view of a wateh having a liquid crystal display eonstrueted as shown in Figures 1 and 2.
As shown in Figure 1 a liquid crystal display of the Fréedericksz effeet tpositive nematic) type ineludes a liquid crystal cell 3 comprising two glass slides 4, 5 containing a layer of liquid erystal material 6 which is basically a positive nsmatie mayerial together with a pleochroic dye. Electrodes 7~ ~ eg of tin oxide are arranged on the inner faces of the slides 4, 5, A
brushed aluminiu~ reflector ~7 may be loea~ed behlnd the sllde 5.
7 1 6803~
Prior to assembling the cell 3 the slides 4, 5 (already bearing the electrodes 7, 8) are coated on their inner faces with silicon monoxide or magnesium fluoride. This coating is formed by evaporating a stream of eg silicon monoxide onto the slide at an angle of about 5 to the surface as for example described in UK Patent Specification No 1,454,296. On assembly the slides are arranged with the evaporation direction on the two slides 4, 5 parallel to one another. With such coatings applied liquid crystal molecules at the coated surfaces lie in a single direction (parallel to the evaporation direction) and at an angle of about 25 to 35 typically about 30 to the adjacent slide surface. As a result the liquid crystal molecules lie in a parallel homo-geneous texture as indicated by arrow 13 (Figure 1). The dye molecules in guest-host relationship with the liquid crystal molecules are also roughly in this texture giving a relatively strongly coloured appearance to the cell 3 (which is black or grey if the dye absorbs uniformly throughout the visible spectrum).
A single polariser 1 placed in front of, or behind, the cell 3 (shown in front in Figure 1) with its transmission axis parallel to the alignment direction of the liquid crystal material 6, will enhance the colour of the display in this state, the "off" state.
By this arrangement the electric vector of the incident or refelcted light is confined rou~hly parallel to the transition of the dye molecules.
When a suitable voltage, eg a few volts, (greater than the threshold to give the effect) i6 applied between the electrodes 7 and 8, ie to give the "on" state, the molecules of the liquid crystal material are switched to the homeotropic texture, ie to lie parallel to the electric field along an axis perpendic~lar to the slides 4, 5. The dye molecules are also switched to this I 1 6803~
texture by the guest-host effect and have their long axes essen-tially parallel (ie they are essentially "end-on") to li~ht incident on the cell 3 in a direction perpendicular to the slides l~, 5, effcctively reducing their absorp'ion of ambient light.
This gives the cell 3 a relatively clear or weakly coloured appearance.
If the electrcdes 7 and 8 cover only part of the inner surface of the slides 4 and 5 respectively the entire cell 3 will appear strongly coloured (ie strongly reflects! in the "off"
state whereas in the "on" state only the region of the liquid crystal material 6 between the electrodes 7, 8 will appear clear or weakly coloured in the "on" state the remainder of the cell 3 appearing strongly coloured, ie remaining in the "off" state.
(If the pleochroic dye absorbs uniformly throughout the visible spectrum the strong colouration will appear black or grey.) Thus, by shaping the electrodes 7, 8 into discrete f~cing partsj eg bars of a digit separately connectable to a voltage source (not shown),symbols or letters may be displayed. This may be achieved by photoetching ~in a known way) the layers, eg SnO2, used to form the electrodes 7, 8 prior to assembly.
For example, in the watch display of Figure 3 the electrodes 7, 8 are shaped to provide ~our seven bar numerîc digits to display time; eg the digits are displaying 12.45 as shown in Figure 3. A pulsed period dot P is also included, as in conven-tional watch displays, to indicate operation of the display.
~ xamples of suitable dyed liquid cr~stal material for use asthe ~aterial 6 above are Dye Mixture No 1 (about 1X by weight) defined above dissolved in one of the two hosts Host A and ~o~t B defined above (the thickness of the material 6 layer being 12 ~m).
I ~ 68(~3{~
3o In an alternative device embodying the second aspect of the present invention a cholesteric to nematic phase change effect i8 made in a known way. The method of construction is the same a6 that described above with reference to Figures 1 to 3 except that no MgF2 or SiO coating is applied to the inner surfaces of the electrode bearing slides 4, 5, no polariser 1 is required and the liquid crystal material 6 in this case is essentially a long pitch cholesteric material (having R molecular helical pitch of the order of about 2 ~m containing a pleochroic dye. A suitable material is one of the two hosts Host A and B de~ined abo~e modified by the inclusion of 5~ by weight of CB15 as defined below and containing the Dye Migture No 1 defined above (about 1X by weight) ~the thicknes6 of the material 6 layer again being 12~m).
In the ~Offn state (with no voltage ap~lied) the cell 3 again appearg strongly coloured in this case (as in the Fr~eedericksz ef~ect device). The liquid crystal material 6 in this state i5 in the focal conic texture which compri~es an arrangement of random molecular helicesO The dye molecules take up the same arrangement by the guest-host ef~ect. ~he strong colouration (which may be black or dark grey) is because ambient white light incident on the material 6 via the slide 4 i8 partially absorbed by the dye molecules which are perpendicular or oblique to the light propagation direction~
In the "on" state a voltage (typically 10-15 volts) is applied between the electrodes 7, 8 sufficient to give the homeotropic texture, ie with the liquid crystal molecules between the electrodes 7, 8 es~entially re-orientated to lie perpendicular to the slidee 4, 5. The dye milecules between the elctrodes 7, 8 are re-orientated to this arrangement by the guest-host effect.
~o The region between the electrodes 7, 8 appears clear or weakly coloured in this state (RS with the Fréedericksz effect device) because the dye molecules are ~ssentially "end-on" to ambient light propagating in a direction perpendicular to the cell 3, ie perpendicular to the slides 4, 5 ~via the slide 4).
3 2 3 2 ~ - CN
Claims (49)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A material suitable for a guest-host liquid crystal device comprises a solution of a liquid crystal material and a pleochroic dye wherein the pleochroic dye comprises at least one compound having a formula:
Formula (I) wherein:
R represents a group selected from optionally substituted alkyl and optionally substituted monocyclic aryl;
Q represents a group selected from halo, OH, -NO2, alkyl, aryl and -NR1R2, wherein each of R1 and R2 independently represents a group selected from H, alkyl and aryl;
x represents an integer from 1 to 4; and y represents an integer from 0 to 4;
x + y being in the inclusive range 2 to 8.
Formula (I) wherein:
R represents a group selected from optionally substituted alkyl and optionally substituted monocyclic aryl;
Q represents a group selected from halo, OH, -NO2, alkyl, aryl and -NR1R2, wherein each of R1 and R2 independently represents a group selected from H, alkyl and aryl;
x represents an integer from 1 to 4; and y represents an integer from 0 to 4;
x + y being in the inclusive range 2 to 8.
2. A material as claimed in claim 1 and wherein the group R represents a straight or branched chained alkyl group having up to 10 carbon atoms optionally substituted by a lower alkoxy, OH or monocyclic aryl group.
3. A material as claimed in claim 1 and wherein the group R represents a monocyclic aryl group.
4. A material as claimed in claim 3 and wherein the group R represents a phenyl group optionally substituted in the para or meta position relative to the anthraquinone nucleus by a group selected from lower alkyl, lower alkoxy, halo, NO2, OH and NR1R2 where NR1R2 is as defined in claim 1.
5. A material as claimed in claim 1 and wherein the group NR1R2 is NHR1, where R1 is H, monocyclic aryl or optionally substituted alkyl containing from 1 to 5 carbon atoms.
6. A material as claimed in claim 1 and wherein the said at least one com-pound of Formula (I) has a formula:
Formua (II) wherein each of A, B and C independently represents a group selected from H, -SR, and -NR1R2; Q1 having the same definition as Q; R, R1, R2, Q and y being as de-fined in claim 1.
Formua (II) wherein each of A, B and C independently represents a group selected from H, -SR, and -NR1R2; Q1 having the same definition as Q; R, R1, R2, Q and y being as de-fined in claim 1.
7. A material as claimed in claim 6 and wherein y = 0 and R represents an optionally substituted phenyl group containing in the meta- or para-position re-lative to the anthraquinone nucleus a group selected from one of the following:
H, lower alkyl, lower alkoxy, halo, NO2 and OH.
H, lower alkyl, lower alkoxy, halo, NO2 and OH.
8. A material as claimed in claim 7 and wherein of the three groups A, B
and C two are -SR groups and the third is hydrogen, R being as defined in claim 7.
and C two are -SR groups and the third is hydrogen, R being as defined in claim 7.
9. A material as claimed in claim 7 and wherein of the three groups A, B
and C one is hydrogen and the other two are -NR1R2 groups, R1 and R2 being as de-fined in claim 1.
and C one is hydrogen and the other two are -NR1R2 groups, R1 and R2 being as de-fined in claim 1.
32 A material as claimed in claim 7 and wherein of the three groups A, B and C two are hydrogen and the third is NR1R2, R1 and R2 being as defined in claim 1.
11 A material as claimed in claim 7 and wherein the three groups A, B and C are SR groups, R being as defined in claim 7.
12 A material as claimed in claim 7 and wherein the three groups A, B and C are Ho
13 A material as claimed in claim 7 and wherein the three groups A, B and C are NR1R2 groups, R1 and R2 being as defined in claim 1.
14 A material as claimed in claim 7 and wherein the three groups A, B and C are respectively -SR, NR1R2 and NR1R2 groups, R being as defined in claim 7 and R1 and R2 being as defined in claim 1.
A material as claimed in claim 7 and wherein the three groups A, B and C are respectively -NR1R2, -SR and -NR1R2 , R being as defined in claim 7 and R1 and R2 being as defined in claim 1.
16 A material as claimed in claim 7 and wherein the three groups A, B and C are respectively -NR1R2, -NR1R2 and -SR, R being as defined in claim 7 and R1 and R2 being as defined in claim 1.
17 A material as claimed in claim 7 and wherein the three groups A, B and C are respectively -SR, -SR and -NR1R2, R being as defined in claim 7 and R1 and R2 being as defined in claim 1.
18 A material as claimed in claim 7 and wherein the three groups A, B and C are respectively -SR, -NR1R2 and -SR, R being as defined in claim 7 and R1 and R2 being as defined in claim 1.
19 A material as claimed in claim 7 and wherein the three groups A, B and C are respectively -NR1R2 -SR and -SR, R being as defined in claim 7 and R1 and R2 being as defined in claim 1.
A material as claimed in claim 1 and wherein the compound of Formula (I) has a formula:
21 A material as claimed in claim 1 and wherein the compound of Formula (I) has a formula:
22 A material as claimed in claim 1 and wherein the compound of Formula (I) has a formula:
23 A material as claimed in claim 1 and wherein the compound of Formula (I) has a formula:
24 A material as claimed in claim 1 and wherein the compound of Formula (I) has a formula:
A material as claimed in claim 1 and wherein the compound of Formula (I) has a formula:
26 A material as claimed in claim 1 and wherein the compound of Formula (I) has a formula:
27 A material as claimed in claim 1 and wherein the compound of Formula (I) has a formula:
28 A material as claimed in claim 1 and wherein the compound of Formula (I) has a formula:
29 A material as claimed in claim 1 and wherein the compound of Formula (I) has a formula:
A material as claimed in claim 1 and wherein the compound of Formula (I) has a formula:
31 A material as claimed in claim 1 and wherein the compound of Formula (I) has a formula:
32 A material as claimed in claim 1 and wherein the compound of Formula (I) has a formula:
33 A material as claimed in claim 1 and wherein the compound of Formula (I) has a formula:
34 A material as claimed in claim 1 and wherein the compound of Formula (I) has a formula:
A material as claimed in claim 1 and wherein the compound of Formula (I) has a formula:
36 A material as claimed in claim 1 and wherein the compound of Formula (I) has a formula
37 A material as claimed in claim 1 and wherein the compound of Formula (I) has a formula:
38 A material as claimed in claim 1 and wherein the compound of Formula (I) has a formula:
39 A material as claimed in claim 1 and wherein the compound of Formula (I) has a formula:
40. A material as claimed in claim 1 and wherein the pleochroic dye com-prises a mixture of dyes at least one of which is a compound of Formula (I) as defined in claim 1.
41. A material as claimed in claim 40 and wherein the pleochroic dye in-cludes a mixture of a blue dye and an orange dye, the orange dye being a com-pound of Formula (I).
42. A material as claimed in claim 41 and wherein the mixture also in-cludes a yellow dye or a red dye or both and comprises a neutral coloured mix-ture.
43. A material as claimed in claim 40 and wherein the pleochroic dye com-prises a neutral coloured mixture of a yellow dye, a red dye and a blue dye at least one of which is a compound of Formula (I).
44. A material as claimed in claim l and wherein the liquid crystal mate-rial comprises manily 4-n-alkyl-or alkoxy-4'-cyanobiphenyl compounds.
45. A material as claimed in claim 1 and wherein the liquid crystal mate-rial comprises mainly 1-(4'-cyanophenyl)-4-n-alkyl-cyclohexane compounds.
46. A material as claimed in claim 1 and wherein the liquid crystal mate-rial is suitable for a cholesteric to nematic phase change effect device and com-prises a nematic liquid crystal material together with a chiral agent.
47. A material as claimed in claim 44 and wherein the liquid crystal mate-rial is suitable for a cholesteric to nematic phase change effect device and com-prises a nematic liquid crystal material together with a chiral agent.
48. A material as claimed in claim 45 and wherein the liquid crystal mate-rial is suitable for a cholesteric to nematic phase change effect device and com-prises a nematic liquid crystal material together with a chiral agent.
49 A liquid crystal electro-optical device including two electrically insulating substrates at least one of which is optically transparent, electrodes on the inner surfaces of the substrates and a film of dielectric material contained between the substrates, wherein the improvement comprises the dielectric material being a dyed liquid crystal material as claimed in claim 1.
A liquid crystal device as claimed in claim 49 and wherein the device is a cholesteric to nematic phase change effect device.
51 A liquid crystal device as claimed in claim 49 and wherein the device is a Freedericksz effect device.
52 A liquid crystal device as claimed in claim 49 and wherein the device is a twisted nematic effect device.
A liquid crystal device as claimed in claim 49 and wherein the device is a cholesteric to nematic phase change effect device.
51 A liquid crystal device as claimed in claim 49 and wherein the device is a Freedericksz effect device.
52 A liquid crystal device as claimed in claim 49 and wherein the device is a twisted nematic effect device.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB8024797 | 1980-07-29 | ||
| GB8024797 | 1980-07-29 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1168036A true CA1168036A (en) | 1984-05-29 |
Family
ID=10515118
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000382632A Expired CA1168036A (en) | 1980-07-29 | 1981-07-28 | Liquid crystal materials with pleochroic dyes |
Country Status (11)
| Country | Link |
|---|---|
| US (1) | US4405211A (en) |
| EP (1) | EP0049035B1 (en) |
| JP (1) | JPS5773067A (en) |
| KR (1) | KR840001859B1 (en) |
| AT (1) | ATE16198T1 (en) |
| CA (1) | CA1168036A (en) |
| DD (1) | DD200091A5 (en) |
| DE (1) | DE3172719D1 (en) |
| HK (2) | HK100285A (en) |
| MY (2) | MY8600422A (en) |
| SG (2) | SG66085G (en) |
Families Citing this family (22)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5790080A (en) * | 1980-11-27 | 1982-06-04 | Canon Inc | Liquid crystal display device |
| JPS5792080A (en) * | 1980-11-28 | 1982-06-08 | Canon Inc | Liquid crystal display |
| DE3201120A1 (en) * | 1981-01-17 | 1982-10-21 | Hitachi, Ltd., Tokyo | LIQUID CRYSTAL COMPOSITION |
| JPS57119976A (en) * | 1981-01-17 | 1982-07-26 | Mitsubishi Chem Ind Ltd | Liquid crystal composition |
| DE3276180D1 (en) * | 1981-02-25 | 1987-06-04 | Secr Defence Brit | LIQUID CRYSTAL MATERIALS COMPRISING PLEOCHROIC DYES |
| US4446047A (en) * | 1981-02-25 | 1984-05-01 | Imperial Chemical Industries Plc | Pleochroic anthraquinone dyes |
| EP0059036B1 (en) * | 1981-02-25 | 1987-07-29 | Imperial Chemical Industries Plc | Pleochroic anthraquinone dyes |
| US4464282A (en) * | 1981-02-25 | 1984-08-07 | The Secretary Of State For Defence In Her Britannic Majesty's Government Of The United Kingdom Of Great Britian And Northern Ireland | Organic materials |
| JPS57147575A (en) * | 1981-03-06 | 1982-09-11 | Sumitomo Chem Co Ltd | Liquid crystal display element |
| GB2126601B (en) * | 1982-08-18 | 1986-12-10 | Secr Defence | Guest-host liquid crystal materials |
| EP0103952B1 (en) * | 1982-08-18 | 1988-12-28 | Imperial Chemical Industries Plc | Pleochroic anthraquinone dyes |
| EP0108472B1 (en) * | 1982-08-18 | 1989-12-13 | The Secretary of State for Defence in Her Britannic Majesty's Government of the United Kingdom of Great Britain and | Organic materials for a liquid crystal device |
| DE3244815A1 (en) * | 1982-12-03 | 1984-06-07 | Bayer Ag, 5090 Leverkusen | ANTHRACHINONE DYES, THEIR PRODUCTION AND USE, AND DICHROITIC MATERIAL CONTAINING ANTHRACHINONE DYES |
| JPS59179561A (en) * | 1983-03-29 | 1984-10-12 | Hitachi Ltd | Anthraquinone pigment and liquid crystal composition containing the same |
| JPS6252741U (en) * | 1985-09-17 | 1987-04-02 | ||
| GB9218830D0 (en) * | 1992-09-05 | 1992-10-21 | Smithkline Beecham Plc | Novel compounds |
| JPH06324369A (en) * | 1993-02-05 | 1994-11-25 | Sumitomo Electric Ind Ltd | Third-order nonlinear optical material |
| US6483643B1 (en) * | 1999-04-08 | 2002-11-19 | Larry Zuchowski | Controlled gain projection screen |
| JP4571389B2 (en) * | 2003-11-11 | 2010-10-27 | 富士フイルム株式会社 | Liquid crystal composition, liquid crystal element containing the same, and compound |
| EP2125960B1 (en) * | 2007-02-23 | 2011-01-26 | Basf Se | Transparent colourants and colourant compositions, and their use |
| CN107225716B (en) * | 2017-06-29 | 2022-11-11 | 厦门立扬光学科技有限公司 | Automatic resin lens glue filling device and process |
| CN115427516B (en) | 2020-06-25 | 2024-01-12 | 日本化药株式会社 | Anthraquinone compound, liquid crystal composition for light control comprising same, and light control element |
Family Cites Families (28)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB1507030A (en) * | 1974-10-21 | 1978-04-12 | Secr Defence | Liquid crystal display devices |
| EP0002104B1 (en) * | 1977-10-14 | 1982-10-20 | BDH Chemicals Limited | Pleochroic dyes suitable for use in solution with liquid crystal materials for electro-optic device applications |
| JPS54157786A (en) * | 1978-05-23 | 1979-12-12 | Minnesota Mining & Mfg | Multiicoloring dyestuff and photoelectric display device |
| CH638828A5 (en) * | 1978-12-21 | 1983-10-14 | Bbc Brown Boveri & Cie | LIQUID CRYSTAL MIXTURE. |
| DE2902177A1 (en) * | 1978-12-21 | 1980-07-17 | Bbc Brown Boveri & Cie | LIQUID CRYSTAL MIXTURE |
| US4273929A (en) * | 1979-02-05 | 1981-06-16 | Hoffmann-La Roche Inc. | Heterocyclic compounds |
| US4232950A (en) * | 1979-02-23 | 1980-11-11 | Minnesota Mining And Manufacturing Company | Liquid crystal compositions including pleochroic dye |
| CH645916A5 (en) * | 1979-02-23 | 1984-10-31 | Minnesota Mining & Mfg | PLEOCHROITIC COLORS CONTAINING LIQUID CRYSTALS. |
| US4232949A (en) * | 1979-02-23 | 1980-11-11 | Minnesota Mining And Manufacturing Company | Liquid crystal compositions containing pleochroic dye |
| US4304683A (en) * | 1979-03-16 | 1981-12-08 | Mitsui Toatsu Chemicals, Inc. | Composition for liquid crystal color display element |
| US4360447A (en) * | 1979-03-16 | 1982-11-23 | Mitsui Toatsu Chemicals, Inc. | Composition for liquid crystal color display elements |
| JPS6045677B2 (en) * | 1979-03-23 | 1985-10-11 | 株式会社東芝 | liquid crystal display device |
| CH641828A5 (en) * | 1979-08-17 | 1984-03-15 | Ebauches Sa | LIQUID CRYSTAL COMPOSITION FOR ELECTRO-OPTICAL DEVICE. |
| EP0025809A1 (en) * | 1979-09-21 | 1981-04-01 | BBC Aktiengesellschaft Brown, Boveri & Cie. | Liquid crystals mixture |
| CH642393A5 (en) * | 1979-10-02 | 1984-04-13 | Ebauches Sa | LIQUID CRYSTAL COMPOSITION FOR ELECTRO-OPTICAL DEVICE. |
| JPS5738876A (en) * | 1980-08-21 | 1982-03-03 | Mitsubishi Chem Ind Ltd | Liquid crystal composition |
| GB2065695B (en) * | 1979-10-12 | 1984-07-25 | Hitachi Ltd | Guest-host type liquid crystal composition and liquid crystal display device using the same |
| JPS56100885A (en) * | 1980-01-17 | 1981-08-13 | Mitsui Toatsu Chem Inc | Composition for liquid crystal color display |
| DE3007198A1 (en) * | 1980-02-26 | 1981-09-03 | Siemens AG, 1000 Berlin und 8000 München | PLEOCHROITIC ANTHRACHINONE DYE, METHOD FOR THE PRODUCTION THEREOF AND USE OF THE DYE |
| DE3014933A1 (en) * | 1980-04-18 | 1981-10-29 | Bayer Ag, 5090 Leverkusen | LIQUID CRYSTAL MATERIALS CONTAINING ANTHRACHINONE DYES |
| JPS5790080A (en) * | 1980-11-27 | 1982-06-04 | Canon Inc | Liquid crystal display device |
| JPS5792080A (en) * | 1980-11-28 | 1982-06-08 | Canon Inc | Liquid crystal display |
| DE3046904A1 (en) * | 1980-12-12 | 1982-07-15 | Bayer Ag, 5090 Leverkusen | ANTHRACHINONE DYES, METHOD FOR THE PRODUCTION THEREOF, AND THE USE OF LIQUID CRYSTAL MATERIALS CONTAINING ANTHRACHINONE DYES |
| JPS57117581A (en) * | 1981-01-12 | 1982-07-22 | Sumitomo Chem Co Ltd | Liquid crystal display element |
| JPS57119976A (en) * | 1981-01-17 | 1982-07-26 | Mitsubishi Chem Ind Ltd | Liquid crystal composition |
| JPS57119977A (en) * | 1981-01-17 | 1982-07-26 | Mitsubishi Chem Ind Ltd | Liquid crystal composition |
| GB2094822B (en) * | 1981-02-25 | 1986-03-05 | Ici Plc | Anthraquinone dyes |
| JPS57172971A (en) * | 1981-02-25 | 1982-10-25 | Secr Defence Brit | Substance suitable for guest-host liquid crystal device and liquid crystal electrooptical device |
-
1981
- 1981-07-27 US US06/287,118 patent/US4405211A/en not_active Expired - Lifetime
- 1981-07-28 DE DE8181303471T patent/DE3172719D1/en not_active Expired
- 1981-07-28 CA CA000382632A patent/CA1168036A/en not_active Expired
- 1981-07-28 AT AT81303471T patent/ATE16198T1/en active
- 1981-07-28 KR KR1019810002742A patent/KR840001859B1/en active
- 1981-07-28 EP EP81303471A patent/EP0049035B1/en not_active Expired
- 1981-07-28 JP JP56118396A patent/JPS5773067A/en active Granted
- 1981-07-29 DD DD81232183A patent/DD200091A5/en not_active IP Right Cessation
-
1985
- 1985-09-09 SG SG660/85A patent/SG66085G/en unknown
- 1985-12-06 SG SG933/85A patent/SG93385G/en unknown
- 1985-12-18 HK HK1002/85A patent/HK100285A/en unknown
-
1986
- 1986-02-27 HK HK145/86A patent/HK14586A/en not_active IP Right Cessation
- 1986-12-30 MY MY422/86A patent/MY8600422A/en unknown
-
1987
- 1987-12-30 MY MY223/87A patent/MY8700223A/en unknown
Also Published As
| Publication number | Publication date |
|---|---|
| JPH049830B2 (en) | 1992-02-21 |
| DD200091A5 (en) | 1983-03-16 |
| HK14586A (en) | 1986-03-07 |
| SG66085G (en) | 1986-07-25 |
| DE3172719D1 (en) | 1985-11-28 |
| HK100285A (en) | 1985-12-27 |
| EP0049035B1 (en) | 1985-10-23 |
| MY8600422A (en) | 1986-12-31 |
| KR840001859B1 (en) | 1984-10-23 |
| US4405211A (en) | 1983-09-20 |
| SG93385G (en) | 1986-11-21 |
| ATE16198T1 (en) | 1985-11-15 |
| EP0049035A1 (en) | 1982-04-07 |
| JPS5773067A (en) | 1982-05-07 |
| MY8700223A (en) | 1987-12-31 |
| KR830006402A (en) | 1983-09-24 |
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