DE2543843A1 - NEMATIC, LIQUID CRYSTAL MIXTURES AND ELECTROOPTIC DEVICE - Google Patents

Description

ING. E. HOFFMANN · DIPL-ING-W-EITLe · DH. REB. NAP. B. HOFFMANN

PATENT LAWYERS
D-8000 MÖNCHEN 81ARABELLASTRASSE 4 - TELEPHONE (0811) 911087 2543843

Composite Case ₂₇ pu * w + / Mv

D / 74444/74445 ^Z7 ^ ^W ~ ' ^y

XEROX CORPORATION
Rochester, NY / USA

Nematic, liquid crystal mixtures
and electro-optical device

The invention relates to nematic liquid crystal compositions and liquid crystal compositions which
a nematic, liquid, crystalline material and a
Contain optically active material and in particular the
Extension of the useful life of such compositions.

When "compositions" are spoken of in the present application, this expression is synonymous with "mass" and "mixture" is used.

Electro-optical systems in which liquid, crystalline
Materials used in contact with an electrode or a photoconductive layer are widely used. However, their use is because of their duration
Operability is limited due to the interaction of the liquid, crystalline material and the electrode or the photoconductive layer. This period of usability is particularly important in the case of cells with a photoconductive

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capable layer limited. Attempts have previously been made to prevent degradation of such devices or to delay. For example, a boundary or insulation layer such as a cellulose nitrate boundary layer has been used, as described in US Pat. No. 3,722,998, or polymeric insulation layers have been used as described in US Pat U.S. Patents 3,795,516 and 3,795,517.

Recently there has been a great deal of interest in the development of materials that are nematic, liquid, crystalline materials align without detrimentally affecting the electro-optical service life of the nematic, liquid, crystalline materials to influence, that is, the length of time during which a nematic, liquid, crystalline material either can be subjected to an electric field or current before the electro-optical properties of the nematic, liquid, crystalline materials.

Known alignment agents include those that are added to the liquid crystalline compositions such as those disclosed in U.S. Patent 3,656,834 and U.S. Patent No. 3,656,834 U.S. Patent 3,803,050. Alignment agents are also those that are typically applied to substrates to affect the alignment of the molecules of a layer of the liquid, crystalline composition, which is then applied to the alignment coating. Known coating alignment means include, for example Silanes like alkoxysilanes for homeotropic alignment and additives and coating materials like them in Volume 61, No. 7, Proceedings of the IEEE, page 828, July 1973, in the article "Surface-Produced Alignment of Liquid Crystals "are described by Kahn, Taylor and Schonhorn for homeotropic and homogeneous alignment. The homeotropic Alignment can also be achieved using the Jannings method described in Volume 21, No. 4 of the Journal of

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Applied Physics, Aug. 15, 1972, in the article "Thin Film Surface Orientation for Liquid Crystals "is described.

In new and growing areas of technology such as liquid crystal imaging, new methods, devices, Means and objects of manufacture found that are used in new ways in the new technology can be. The present invention relates to a new process for the production of an additive which, when in contact with a nematic, liquid, crystalline material, the nematic material will be homeotropically aligned and extends the electro-optical life thereof.

The present invention is therefore based on the object of creating a new alignment means.

According to the invention, a new additive is to be created which, when in contact with a nematic, liquid, crystalline mixture or a crystalline, liquid composition which is an optically active material and a contains nematic, crystalline, liquid material, the electro-optical service life thereof is extended if the composition is in contact with a photoconductor.

According to the invention new liquid crystal compositions that align themselves spontaneously.

According to the invention, new, liquid crystal compositions are to be created which have a prolonged electro-optical Own service life.

The object of the present invention is achieved by adding tributyltin oxide (which is hereinafter abbreviated as TBTO is) in contact with a nematic, liquid, crystalline material or a liquid, crystalline compound

6 Ο 9 8 I β / η ■ < 7 2

Settlement is created, containing a nematic ^, liquid, crystalline material and an optically active material. The homeotropic alignment of nematic liquid crystal materials is also achieved by treating the nematic materials with tributyltin chloride. In use, the tributyltin oxide can be uniformly dispersed within the liquid crystalline material or it can be applied to a suitable substrate and in contact with the liquid, crystalline material to be brought. The tributyltin chloride can either be uniformly dispersed within the nematic, liquid, crystalline material or applied to a suitable substrate and then in contact with the nematic, liquid, crystalline material are brought.

Preferred embodiments of the present invention are illustrated with reference to the accompanying drawings Embodiments explained in more detail. Show in the drawings

Fig. 1 is a partially schematic cross-sectional view of a layer of liquid crystals on top of a Substrate;

Fig. 2 is a partially schematic cross-sectional view of a layer made of the new invention liquid crystal composition on a suitable substrate ;

2A shows a partially schematic cross-sectional view of a layer of nematic, liquid, crystalline Composition in contact with a layer of the advantageous alignment agents of the invention;

3 is a partially schematic view in cross section of an imaging element with pictorial parts; containing the new liquid crystal compositions of the invention;

FIG. 4 is a partially sheared top view of the imaging element as shown in cross section in FIG. 3 is;

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5 is a partially schematic cross-sectional view of a liquid, crystalline, electro-optical Cell;

6 is a partially schematic cross-sectional view of a liquid, crystalline electro-optical cell; wherein an additive is dispersed in the liquid crystal composition;

7 is a partially schematic cross-sectional view of a liquid, crystalline electro-optical Cell wherein the additive is in contact with the liquid crystal composition as a separate layer;

8 is a partially schematic, isometric view of an embodiment of a liquid, crystalline electro-optical imaging cell in which the desired image is obtained through the shape of the liquid, crystalline material is limited as it is limited by the shape of the spacer;

9 is a partially schematic, isometric view of an embodiment of a liquid, crystalline electro-optical imaging cell in which the desired image is defined or limited by the shape of at least one of the electrodes.

Surprisingly, it has been found that nematic, liquid, crystalline compositions which come into contact with tributyltin oxide or tributyltin chloride, are spontaneously aligned and have a greater tendency to move into a To align orientation in which the major axis of the molecules that contain the liquid, crystalline material, is substantially normal to the plane of the layer of nematic, liquid, crystalline composition.

For example, FIG. 1 is a partially schematic cross-sectional view of a layer of liquid crystalline Material 30 shown on a suitable substrate 31. The liquid, crystalline material that makes up the layer

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represents itself contains a number of adjacent areas 32 and within each area 32 are those individual molecules 33 in a unique locally symmetrical orientation, which is responsible for the orientation of the Molecules in the nematic, liquid, crystalline state is characteristic.

In Fig. 2 is a layer of liquid, crystalline composition including the advantageous alignment means according to the invention shown dispersed therein, wherein any boundaries between regions of molecules of liquid, crystalline material with locally symmetrical orientation are much less precise, and wherein the major number of the individual molecules in the entire layer of liquid, crystalline material in their major axes oriented normal to the plane of the substrate. In Figure 2 is the inventive advantageous alignment means not shown specially. However, these alignment agents are typically present in such small amounts that that the explanation of their effect on the molecules of liquid, crystalline material is sufficient to establish their presence to display.

In Figure 2A there is a layer of nematic, liquid, crystalline Composition shown, which is in contact with a layer 40 of the advantageous invention Alignment means.

The individual molecules 33 of the nematic, liquid, crystalline Compositions are shown in Fig. 2A as being substantially parallel to one another and perpendicular to the plane of the layer 30 of nematic, liquid, crystalline composition.

When the novel alignment agent according to the invention within the nematic, liquid, crystalline composition di-

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If the embodiment of Fig. 2 is omitted, the following procedure may conveniently be used.

The liquid, crystalline materials or mixtures thereof are used along with the advantageous alignment agent in suitable, e.g. organic solvents such as chloroform, trichlorethylene, tetrachlorethylene, petroleum ether, Methyl ethy! Ketone, isopropanol, toluene or similar dissolved. The solution, which contains the liquid, crystalline material and the beneficial additive, is then typically poured, sprayed or otherwise applied onto a suitable substrate. After evaporation of the solvent a thin layer of liquid crystal containing the alignment agent remains on the substrate. Alternatively the liquid, crystalline materials can be mixed together with the alignment agent and applied directly to a suitable substrate by heating the mixed components above the isotropic transition temperature of the liquid, crystalline components and mixing the components can be applied to the substrate prior to application. At room temperature liquid crystals can either be in their natural room temperature state with the advantageous alignment means can be used mixed. In such embodiments according to the invention, where the liquid solutions of the compositions used in electro-optical cells, such compositions can be incorporated into their Able to be injected into these electro-optic cells. Many compositions that are used in accordance with the invention may have viscosities such that the layer of composition has sufficient integrity that it is self-supporting on the substrate, regardless of the orientation of the substrate.

The advantageous alignment means according to the invention are typically to the nematic, liquid, crystalline material in amounts ranging between about 1 and un-

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Given approximately 10% by weight, which amounts are typically sufficient to facilitate the advantageous spontaneous alignment. Any amount below 3/4% that causes alignment can be used. The upper limit is that amount large enough to cause transition to the isotropic state.

The liquid crystal layers of films used in the present In accordance with the invention, preferably have a thickness in the range of about 250 microns or less, although thicker films work satisfactorily in some embodiments of the invention.

If the new alignment means are used as a separate layer, as in the embodiment of Figure 2A, the above procedure can be used to create a layer of nematic, liquid, crystalline composition which does not contain the alignment agent after the layer 40 of the new alignment agent is applied to a suitable substrate has been applied. The layer 40 of alignment agent can conveniently be made by dissolving the alignment agent in an organic solvent such as petroleum ether. It should be noted that tributyl tin oxide and tributyl tin chloride are soluble in most organic solvents. The alignment agent solution and organic solvent may conveniently be applied to a suitable substrate according to any of the methods described above can be applied, and the solvent can evaporate, for example by drying in air, leaving a residual film of alignment agent on the substrate. The relative concentrations of alignment agents or organic solvents are typically described as having Add 1 gram of alignment agent to a volume of organic solvent up to about 30 cubic centimeters. Of course can in a given nematic, liquid, crystalline

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In the composition, the concentration of alignment agent in the organic solvent can be used with which one achieved the desired effect.

For example, in the embodiment of Figure 2A, the butyltin oxide has an aligning effect on an approximately 12.2 / U (1/2 mil) thick layer of N- (p-methoxybenzylidene) -p-butylaniline (hereinafter abbreviated as MBBA), when the coating solution of butyl tin oxide in organic solvent has a concentration of at least about 1 gram of alignment agent in 30 cc of organic solvent. On the other hand, when the electro-optic useful life is to be extended, the incorporation of a layer of butyl tin oxide in organic solvent is very effective. For example, 1 g of butyl tin oxide in 150 ecm petroleum ether, after air-drying on a suitable substrate and incorporation into an electro-optical system with MBBA, extends the electro-optical service life of the MBBA photoconductor system by six times. In the dispersion of Fig. 2, wherein the butyltin oxide is uniformly dispersed in the nematic, liquid, crystalline composition and wherein the objective of extending the electro-optic useful life is to be achieved, the butyltin oxide is typically used in amounts ranging from about 0.1 to about 10 % by weight are added, these amounts typically being sufficient to achieve an extended electro-optical service life. Any amount in excess of 10% by weight can be used as long as there is no transition of the liquid, crystalline material from the nematic to the isotropic state.

Any nematic, liquid, crystalline composition, containing a nematic liquid crystalline material in the practice of the present invention use. Typical suitable nematic, liquid, crystalline materials include p-azoxyanisole, p-azoxyphenetol, p-butoxybenzoic acid, p-methoxycinnamic acid, butyl-p-anisylidene

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p-amino-cinnamic acid salt, anisylidene, p-amino-phenyl acetate, p-Ethoxybenzylamino-a-methyl-cinnamic acid, 1,4-bis- (1 - ethoxybenzylidene) -cyclohexanone, 4,4'-dihexyl-oxybenzene, 4,4'-diheptyloxybenzene, Anisal-p-amino-azo-benzene, anisaldazine, a-benzolazo- (anisal-a-naphthylamine), η, η'-nonoxybenztoluidine; Anile of the generic group (p-n-alkoxybenzylidene-p-n-alkylaniline) such as p-methoxy-benzylidene-p'-n-butylaniline; netamic Compounds of the alkoxybenzylidene-aminoalkylphenone group such as methoxybenzylidene-aminobutyrophenone and methoxybenzylidene-amino-valerophenone; Mixtures of the above and others.

The substrate on which the nematic compositions are located and the alignment means of the present invention spontaneously align may include any suitable material and may be in various embodiments in any desired shapes, shapes, or orientations. For example the substrate can contain electrically conductive materials such as copper, brass, aluminum, steel, cadmium, silver, gold, Contain tin or other materials. Similarly, the substrate can be electrical insulation materials such as glass, plastics, Contains paper, ceramic and other suitable insulators. In still other embodiments, a conductive coating can be used applied to an insulator, e.g. NESA glass, which is a partially transparent tin oxide coated glass available from Pittsburgh Plate Glass Co. is to create an electrode. Another such electrode contains aluminized mylar, made from mylar polyester film, available from DuPont, with a thin, semi-transparent aluminum coating. Another such electrode contains mylar coated with copper or copper iodide. Additionally Any other suitable materials can be added to these exemplary substrates and conductive materials be used.

In a further embodiment of the invention can the nematic compositions with a suitable material

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rial, typically a transparent material, can be overlaid or they can be between two layers made of any desired material. For example, a spontaneously oriented or spontaneously orientable nematic composition can be overcoated with a material on a suitable substrate as with Tedlar, a polyvinyl fluoride available from DuPont; a polyethylene film; a polyvinyl chloride film; Mylar, a polyester resin film available from DuPont; thin sheets of glass and sheets, mixtures thereof, and others Overlayers are typically transparent films.

In the present invention, where the nematic, liquid, crystalline compositions spontaneously align, when placed on a substrate, visual differences occur in the liquid, crystalline material in either reflected or transmitted light. For example, nematic material can be in aligned State to be more transparent than the non-aligned state, and the contrast between the aligned and non-aligned Dividing a layer of liquid, crystalline material can be done with polarizers or other contrast enhancement devices be reinforced.

The differential optically reflective and transmissive properties of spontaneously aligned and non-aligned Portions of a layer of liquid crystal compositions may contain an imaging system. For example, as shown in Figures 3 and 4, the imaged element includes a substrate 31, which carries a liquid, crystalline layer 35 which contains imagewise parts 36, which are either the inventive contain or lie on advantageous alignment means and the background portions 37 shown in FIG non-aligned condition. Such imagewise layers of liquid crystals can also be used in

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liquid, crystalline electro-optical cells can be used. For example, these can be liquid, crystalline Compositions can be used in conjunction with a photoconductive substrate as described in U.S. Patent 3,671,231 will.

Provide electro-optic systems using nematic, liquid, crystalline compositions Effects known to be useful. Such effects include, for example, dynamic scattering, as stated in Proceedings of the E.E.E.E., July 1968, in the Article entitled "Dynamic Scattering: A New Electro-Optical Effect in Certain Classes of Nemative Liquid Crystals" Heilmeier, Zanoni and Barton on pages 1162 to 1171 discuss the transition from optical uniaxiality for optical biaxiality, as described in US Pat. No. 3,687,515, and an electric field transition from one optical uniaxial orientation to another optical uniaxial orientation, as in the floating one U.S. Patent Application SN 349,497, filed April 9, 1973 is described. These electro-optic effects are only examples and the applications of the present invention should not be limited to this.

In FIGS. 5 to 8 and 9, the same reference numerals denote the same elements in all figures. In Fig. 5 is schematic shown as a layer 14 of nematic, liquid, crystalline composition between two electrodes is interposed, each electrode containing a substrate 11 coated with a conductive coating 12 is. The layer 14 is formed by spacers 13. Conductive coatings 12 are electrical through the electrical network 15 is connected to a suitable voltage source 16 via electrical lines 17. The spacer 13 is typically chemically inert, transparent, essentially insulating, and has appropriate dielectric properties

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Properties. Materials suitable for use as insulating spacers 13 suitable include cellulose acetate, cellulose triacetate, cellulose acetate butyrate, polyurethane elastomers; Polyethylene, polypropylene, polyester, polystyrene, polycarbonate, polyvinyl fluoride, polytetrafluoroethylene, Polyethylene terephthalate and mixtures thereof. The spacer 13 preferably has a thickness in the range of about 100 microns or less, although thicker spacers can be used satisfactorily.

In FIGS. 5 to 8 and 9, the layer of nematic, liquid, crystalline composition shown as a layer containing the advantageous additive according to the invention (not shown). It should be noted, however, that in all embodiments of the invention the additive be present as a separate layer in contact with the liquid crystalline composition not dispersed therein can.

In the embodiment as shown in FIG. 8, suitable substrates 18 are with conductive coatings 12 coated, and the spacer element 13 has a cavity or a cut-out part 19, which the liquid, Contains crystalline composition. In the embodiment of Fig. 8, an imagewise formed layer of nematic, liquid, crystalline composition has been subjected to the application of tension uniformly across it. This is in contrast to the embodiment of FIG. 5, in which a uniform layer of nematic, liquid crystalline composition is subjected to a voltage applied uniformly across it.

In the embodiment of FIG. 9, the shape of the electrode 21 defines the desired image. The imaging element here contains transparent plates 11, which are supported by spacers 13, which contain an empty area 20, which is filled with a nematic, liquid, crystalline

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Composition is filled and substantially fills the entire space of the spacer elements 13. The desired Image is formed by the shape of the substantially transparent conductive coating 21 that is applied to the inner surface is mounted on one or both of the transparent carrier plates 11 and only in the desired image configuration is appropriate. Both electrodes can easily be made into a matched pair so that they are the same limit desired image, although only a conductive coating need be present in the imagewise configuration. At the Operation of the embodiment illustrated in Figure 9 is the nematic, liquid, crystalline composition subjected to the applied voltage only in the areas which the two electrode surfaces of the substrates 11 have in common are. The alignment means can be provided in an imagewise configuration as a separate layer and together with a uniform layer of nematic, liquid crystalline composition, and the application of voltage uniformly along the nematic layer will give imagewise electro-optic effects due to the imagewise configuration of the alignment means.

Of course, the electro-optic embodiments shown in Figures 5, 8 and 9 are preferred at the dynamic scattering of the nematic, liquid, crystalline composition is used. This is due to, that the alignment agent homeotropically the molecules of the nematic, liquid, crystalline composition aligns, whereby the major axes of the nematic composition are parallel to the direction in which the voltage is applied. If other electro-optical effects besides dynamic scattering are desired, so can the stress in a direction orthogonal to the optical axis of the nematic, liquid, crystalline assemblages

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settlement by means such as those in the US Pat. No. 3,687,515, or the nematic, liquid, crystalline composition can be chosen so that it has a net-negative dielectric anisotropy, which causes the molecules of the composition align themselves perpendicular to the direction in which the voltage was applied.

Typical suitable, nematic, liquid, crystalline materials with negative dielectric anisotropy, which can be used alone or together with nematic, liquid, crystalline materials with a positive dielectric anisotropy, but in amounts which give the mixture a net negative dielectric anisotropy, include: N- (p-methoxybenzylidene) -p-butylaniline (MBBA); p-azoxyanisole (PAA), N- (p-ethoxybenzylidene) -p-butylaniline (EBBA); dl-4- (2-methylhexyl) -4 ^t -ethoxy-a-chloro-trans-stilbene; p-methoxybenzylidene-p'-aminophenyl - ^ - methylvalerate (MBV); p-ethoxybenzylidene-p-aminophenyl-3-methylvalerate; ρ, ρ 'methoxypentytolane (MPT); ρ, ρ'-propoxyheptyltolane (PHT) ;, p, p ^! Dioctoxytolan (DOT), trans-4-butyl-ct-chloro-4'-ethoxystuben, and phase IV and phase V of nematic, liquid, crystalline phases available from EM Laboratories Inc. under the trademark Licristal. the

Phase IV is a eutectic mixture

4 ^H 9 ^{and CH} 3 ° -R-N = ^N - © - ^C 4 ^H 9 » ^the phase V is a mixture of C ₀ Hf-O ~ (z ^) - N = N - ^ wV- Ci ₁ H ₀ and C ₂ H ₅ O - ^) - N = N - <£) - C ₄ H ₉ .

₂ H ₅ O - ^) - N = N - <£) - C ₄ H ₉

It has also been found that liquid, crystalline compositions containing a nematic, liquid, crystalline Material and an optically active material in contact with the tributyltin oxide (TBTO) contain an extended or ver

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have an extended electro-optical service life. The "electro-optical" service life means the number of Imaging cycles that the liquid, crystalline composition can go through with an applied voltage before the image quality is deteriorated.

In Fig. 6 an embodiment is shown, wherein TBTO, 50, in the layer 14 of liquid, crystalline composition is dispersed, and in Fig. 7 the embodiment is shown where a separate layer 40 of TBTO in Is in contact with the layer 14 of liquid crystalline composition.

TBTO can be conveniently applied in layer 14 by dissolving in a suitable solvent, e.g. organic solvents such as chloroform, trichlorethylene, tetrachlorethylene, Petrol ether, methyl ethyl ketone, isopropanol, toluene and others be dispersed. The solution, which contains the liquid, crystalline material and TBTO, is then typically added to a suitable substrate poured, sprayed or otherwise applied. After evaporation of the solvent remains a thin layer of liquid crystal on the substrate. Alternatively, a liquid, crystalline material can be put together mixed with the TBTO and applied directly to a suitable substrate by heating the mixed components over the isotropic transition temperature of the liquid, crystalline Components and mixing the components are applied before application to the substrate. Crystals that are at room temperature are liquid, can be used in their natural room temperature state with the TBTO mixed therein. In the present invention, when such liquid crystalline compositions can be used in electro-optic Cells used, such compositions are injected into place in such electro-optic cells will.

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In the embodiment of FIG. 6, TBTO is typically added to the liquid, crystalline composition in amounts in the range between about 0.1 and about 1 wt. these amounts typically being sufficient. Any effective amount below 0.1% can be used. The upper The limit is the amount that is large enough to cause the transition to the isotropic state.

The liquid crystal layers or films used in the present Invention may be used, preferably have a thickness in the range of about 250 microns or more less, although thicker films are satisfactorily used in some embodiments of the present invention can.

When TBTO is used as a separate layer, as in the embodiment of Figure 7, the above method can be used to produce a layer of liquid crystalline composition that does not contain TBTO and on a layer 40 of TBTO disposed on a suitable substrate. Layer 40 of TBTO can be useful can be created by dissolving the TBTO in an organic solvent such as petroleum ether. It should be noted that tributyl tin oxide is soluble in most organic solvents. The solution from TBTO and organic solvent can be conveniently applied to a suitable substrate according to any of those previously described Process are applied, and the solvent can evaporate as such, for example by air drying, a residual film of TBTO remains on the substrate. The relative concentrations of TBTO to organic solvent are typically characterized in that 1 g of TBTO to a volume of organic solvent up to about 30 ecm is added. Any concentration can be used for a given liquid crystalline composition can be used on TBTO in organic solvent as long as the desired effect is achieved.

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Any liquid crystalline composition containing a nematic, liquid crystalline material and an optically active material can be used in the present invention. Typical suitable nematic, liquid, crystalline materials include p-azoxyanisole, p-azoxyphenetol, p-butoxybenzoic acid, p-methoxycinnamic acid, butyl-panisylidene-p-amino-cinnamic acid salt, p-aminophenyl acetate, p-ethoxybenzylamino-a-methyl- cinnamic acid, 1,4-bis (p-ethoxybenzylidene) cyclohexanone, 4,4 ^f -dihexyloxybenzene, 4,4'-diheptyloxybenzene, anisal-p-aminoazo-benzene, anisaldazine, a-benzolazo- (anisal-α ¹ - naphthylamine), η, η'-nonoxybenztoluidine; Aniles of the generic group (pn-alkoxybenzylidene-pn-alkylanilines) such as p-methoxybenzylidene-p'-n-butylaniline; nematic compounds of the alkoxybenzylidene-aminoalkylphenone group such as methoxybenzylidene-aminobutyrophenone and methoxybenzylideneamino-valerophenone; Mixtures of the above compounds and other compounds.

Typical suitable optically active materials include non-mesomorphs optically active materials and mesomorphic optically active materials. Typical suitable non-mesomorphic optically active materials include derivatives of alcohols such as 1-menthol, 1-linanool, d-mannitol, d-borneol and d-quotes; Derivatives of ketones such as d-camphor, d-3-methylcyclohexanone, 1-methone and 1-6-isopropyl-3-cyclohexanone; Derivatives of carboxylic acids such as d-citronellic acid, 1-citronellic acid, d-chaulmoogric acid, 1-campholic acid, 1-arabonic acid, d-tartaric acid and 1-ascorbic acid; Derivatives of aldehydes like d-citronellal; Derivatives of alkenes such as 1-B-pinane, d-Sylversteren (d-silversterene) and d-Linonen (d-linonene); Derivatives of amines such as 1-2-methylpiperidine; Derivatives of Nitriles such as d-mandelonitrile; Derivatives of amides such as d-hydrocarbamide; and mixtures thereof.

Mixtures of the nematic, liquid, crystalline Material and the optically active, non-mesomorphic material

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can be prepared in organic solvents such as chloroform, petroleum ether, methyl ethyl ketone, etc., which typically evaporated from the mixture, leaving the liquid, crystalline composition. Alternatively the individual components of the liquid, crystalline composition can be directly heated by heating the mixed Components at a temperature above the isotropic transition temperature of the nematic, liquid, crystalline Substance and the melting point of the non-mesomorphic material are mixed.

Typical suitable mesomorphic, optically active materials include liquid, crystalline, optically active materials like liquid crystalline cholesterol materials. Typical suitable cholesterol liquid crystalline materials include Derivatives that are formed during the conversion of cholesterol and inorganic acids, e.g. cholesteryl chloride, Cholesteryl bromide, cholesteryl iodide, cholesteryl nitrate; Esters that act in the implementation of cholesterol and form carboxylic acids, e.g. cholesteryl crotonate, cholesteryl nonanoate, Cholesteryl hexanoate, cholesteryl formate, Cholesteryl chloroformate, cholesteryl propionate, cholesteryl acetate, Cholesteryl valerate, cholesteryl linolate, cholesteryl linolenate, cholesteryl oleate, cholesteryl lucate, cholesteryl butyrate, Cholesteryl caprate, cholesteryl laurate, cholesteryl myristate; Ethers of cholesterol such as cholesteryl decyl ether, Cholesteryl oleyl ether, cholesteryl dodecyl ether; Carbamates and carbonates of cholesterol such as cholesteryl decyl carbonate, Cholesteryl oleyl carbonate, cholesteryl methyl carbonate, cholesteryl ethyl carbonate, cholesteryl butyl carbonate, Cholesteryl docosonyl carbonate, cholesteryl heptyl carbamate; and alkylamides and aliphatic secondary Amines derived from 3β-amino- $ -cholesterol, and Mixtures thereof; Peptides such as poly-γ-benzyl-1-glutamate; Derivatives of ß-sitosterol such as sitosterol chloride; and active amyl esters of cyanobenzylidene-amino-cinnamic acid-salt.

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The alkyl groups in these compounds are typically saturated or unsaturated fatty acids or alcohols with less than about 25 carbon atoms and with unsaturated chains of less than about 5 double-bonded olefinic groups. Aryl groups in the above compounds typically contain substituted benzene ring compounds. Any of the above compounds and mixtures thereof are for the liquid crystalline cholesterol films suitable in the advantageous system according to the invention.

In the embodiments of the present invention where the optical input is in an imagewise configuration intended to change the voltage applied across the nematic liquid crystalline composition in the electro-optical system between the liquid, crystalline composition and the conductive coating a photoconductive layer is provided on one of the electrodes. More specifically, in the embodiments where the Alignment means is provided as a separate layer and not in the nematic, liquid, crystalline composition is dispersed, the layer of alignment agent between the liquid crystalline composition and attached to the photoconductive layer.

Typical suitable photoconductive materials include photoconductive ones inorganic materials and photoconductive organic materials. Typical suitable inorganic photoconductive agents Materials include sensitized zinc oxide, e.g., sensitized by the addition of Rhodamine Dye, available from DuPont; Selenium, selenium alloyed with arsenic such as arsenic triselenide, tellurium, antimony or bismuth; Cadmium sulfide, Cadmium sulfoselenide and many other typical suitable inorganic photoconductive materials found in U.S. Patents 3,121,006 and 3,288,603 can be cited. Typical suitable organic photoconductive materials include

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OWlGiNAL IMSPECTED

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for example the combination of 2,5-bis (p-aminophenyl) -1, 3, 4-oxadiazole, available under the trademark TO 1920 from Kalle & Co., Wiesbaden-Biebrich, and Vinylite VYNS, a copolymer of vinyl chloride and vinyl acetate available from Carbide and Carbon Chemicals Company; and the combination of 2,4,7-trinitro-9-fluorenone with polyvinyl carbazole available under the trademark Luvican 170 from Winter, Wolf and Company, New York, NY. The thickness of the photoconductive layer is not critical to the practice of the present invention. Typical suitable thicknesses are from about 1 to about 100 microns.

The optical input includes a wavelength of exposure that is actinic to the photoconductive material. The wavelength of the irradiation lies within the fundamental absorption band of the photoconductive used Materials.

The following examples illustrate the invention without restricting it. The parts and percentages are provided not otherwise specified, expressed by weight.

example 1

Various samples of nematic liquid crystalline compositions containing the nematic liquid crystalline material MBBA doped with varying amounts of bis (tri-n-butyl) tin oxide available from M and T Chemicals, Inc., Rahway, NJ , are prepared and separately applied to a thin film on separate standard microscope slides. Compositions containing approximately 1, 2, and 3 weight percent tributyltin oxide do not show homeotropic orientation. Samples containing from about 5 to about 12 % by weight tributyltin oxide show homeotropic orientation. Samples containing tributyltin oxide in amounts greater than about 12 wt. 96 show isotropism or isotropism.

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example

Three samples of nematic, liquid, crystalline composition, containing N- (p-ethoxybenzylidene) -p-butylaniline (hereinafter abbreviated as EBBA) and 15, 23 and 40% by weight Tributyl tin oxide of Example 1 (hereinafter abbreviated as TBTO) are prepared. The samples are separated on a thin film on separate microscope slides. The samples, which contain 15 and 23 wt.% TBTO, showed a homeotropic alignment. The sample, which is 40 wt.% Contains TBTO, shows isotropism or isotropism (isotropism).

Examples 1 and 2 show that TBTO aligns nematic, liquid, crystalline materials homeotropically when it uniformly dispersed therein to form a nematic, liquid, crystalline composition. Generally stated, it has been observed that the higher the nematic to isotropic transition temperature, the greater it is Amount of alignment agent, expressed by weight, that can be incorporated without a transition from takes place from the nematic to the isotropic state.

Example 3

Three samples of nematic liquid crystalline compositions containing the nematic liquid crystalline materials MBBA and approximately 1, 3 and 5 weight percent tributyltin chloride are prepared and each separate sample is streaked in a thin film on separate standard microscope slides. Containing tributyltin% sample, approximately 1 wt., Does not exhibit homeotropic and homeotropic orientation. The sample, which contains approximately 3% by weight tributyltin chloride, shows partial orientation. The sample, which contains approximately 5 % by weight of tributyltin chloride, shows isotropism or isotropism.

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ORfGiNAL INSPECTED

Example 3 illustrates that tributyltin chloride is uniform in a nematic, liquid, crystalline material to form a nematic, liquid, crystalline composition which has an increased tendency to adopt a homeotropic orientation when it is placed on a substrate.

Example 4

About 1 g of TBTO becomes every five quantities of petroleum ether, viz about 30 ecm, 60 ecm, 90 ecm, 120 ecm and 150 ecm, given. Each of the sample solutions is placed separately in a thin film on a separate microscope slide and can air dry. The organic solvent, i.e. petroleum ether, evaporates during air drying and a thin residual film of TBTO remains on the microscope slide. Subsequent to the Air dry, 1 drop of MBBA is placed on the TBTO coated microscope slide. A homeotropic Alignment is obtained on the sample from a concentration of approximately 1 g of the agent in 30 ecm of solvent was produced. The remaining samples show no homeotropic alignment.

Example 4 illustrates that the alignment agent can be used as a separate layer in contact with the nematic, liquid, crystalline material can be provided and that thereby the nematic material is aligned homeotropically.

B is ρ i el 5

An electro-optical system containing a photoconductive layer is fabricated as follows. Two electrodes are made by placing 2 "2" (5.08 χ 5.08 cm) glass slides coated with conductive coatings made of indium oxide. The indium oxide coating on one of the electrodes

! NSPECTED

2 b 4 ^ 8 4

is overcoated with arsenic triselenide to a thickness of approximately 8 microns using vacuum evaporation processes used. A Tedlar spacer approximately 1.27 cm (1/2 mil) thick is placed on the arsenic triselenide layer and the other electrode is applied with the indium oxide coating in contact with the spacer. The effective clearance void has an area of approximately 7 cm. The nematic, liquid, crystalline material MBBA is placed in the space. The indium oxide coatings are electrically connected to an approximately 100 volt source. After applying tension along the dynamic scattering occurs in the nematic material. The voltage is released and the sample is observed. After about 3 1/2 hours the dynamic deteriorates Scattering.

The following procedure is repeated except that MBBA is mixed with TBTO "to produce a nematic, liquid, to produce a crystalline composition containing approximately 1.6 wt.% TBTO. After using about 100 V direct current, dynamic scattering is observed. The tension is left on and a dynamic spread is observed. After about 12 hours, the dynamic scatter deteriorates.

Example 6

The procedures described in Example 5 are repeated, in each case with and without addition of TBTO to the nematic, liquid, crystalline material, except that a nematic, dynamic scattering mixture is used for the MBBA is substituted. The nematic, liquid, crystalline composition is Dynamic Scattering Mixture No. 1, available from Eastman Chemical Co., Inc. Rochester, N.Y. and has the following properties:

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- ²⁵ - 2bU843

Catalog number: 11643

Name: Nematic Mixture, Dynamic Scattering, I Typical Batch Values:

nematic range: 9 "to 99 ° C dielectric anisotropy (at 0.05 V, 1.0 kHz, 25 ° C)

Ε _± / ί II = 1.32 7

Specific resistance (at 35.4 V ^ ₀ , 500 Hz, 23 ⁰ C):

2.9 x 10 ⁹ ohm-cm threshold voltage: 8.1 V "__ (60 Hz sine wave)

Initial transmission: 80% (homogeneous alignment)

When tested without the TBTO, dynamic scatter was observed during approximately 10 hours and 10 minutes before decomposition or deterioration observed. In the attempt in which the nematic, liquid, crystalline composition TBTO dispersed therein became dynamic scattering for about 37 hours before deterioration observed.

Examples 5 and 6 explain that TBTO is uniform in a nematic, liquid, crystalline composition can be dispersed, with an extension of the electro-optical useful life of the composition.

Example 7

The procedure of Example 5 is repeated except that TBTO is not in the nematic, liquid, crystalline Material MBBA is dispersed but onto the photoconductive arsenic triselenide layer by air drying is applied from a solution of the agent and the organic solvent. There will be five electro-optic cells made, each with a coating of TBTO on the photo-

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ORIGINAL INSPECTED

conductive layer that is formed when air-drying at different concentrations of agents dissolved in petroleum ether. The five solutions each contain approximately 1 g of TBTO dissolved in one of the following volumes of petroleum ether: approximately 30, 60, 90, 120 and 150 ecm.

For each of the separated electro-optic cells, 1 drop is made from a particular concentration of TBTO solution on the arsenic triselenide photoconductive layer and 1 drop of the same concentration of solution on the given free indium oxide coating (the second electrode).

These drops are almost instantly absorbed and uniformly on the surfaces to which they are applied in doing so, a substantially uniform coating of TBTO is applied over the surfaces to which they are applied, educated. The electro-optic cell is then sandwiched to create the structure formed in Example 5.

The indium oxide coatings are electrically connected using approximately 100 volts DC. When using direct current voltage Dynamic scattering occurs and is observed without deterioration during the following time periods:

TBTO coating Dynam. Scattering without

Solution concentration deterioration or decomposition

1 g / 30 ecm 72 hours

1 g / 60 ecm 67 hours

1 g / 90 ecm 72 hours

1 g / 120 ecm 22 hours

1 g / 150 ecm 22 hours

Example 8

The procedure of Example 7 is repeated except that the nematic, liquid, crystalline material

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the previously described Dynamic Scattering Mixture No. 1, available from Eastman Chemical Co., Inc., is instead that MBBA is used. The same five concentrations of TBTO coating solutions are used to make five electro-optic Cells to manufacture. Otherwise the procedure described in Example 7 is followed in all details. With all five resulting electro-optic cells, dynamic scattering occurs without deterioration observed for a time from about 53 to about 68 hours.

The results obtained in Examples 7 and 8 are very favorable compared to the relatively low one electro-optical service life of the nematic, liquid, crystalline compositions. For example, MBBA owns without TBTO a service life of about 3 1/2 hours and the dynamic scatter mix has a useful life of approximately 10 hours and 10 minutes.

Example 9

An electro-optical system containing a photoconductive layer is fabricated as follows. Two electrodes are made by coating approximately 2 »x2" xi / 4 »(2» x2 "xi / 4») glass plates with conductive indium oxide coatings An approximately 12.25 micron (1/2 mil) thick Tedlar spacer is placed on top of the photoconductive layer and a void area of approximately 6 cm is obtained 7596 Dynamic Scattering Mixture No. 11643 (Nemativ Mixture, Dynamic Scattering, I), available from Eastman Kodak Co., and containing approximately 25% cholesteryl oleyl carbonate, is made by simply mixing.

6 0 9 8 I 6/0 9 7 2

Bis (tri-n-butyl) tin oxide, available from M and T Chemicals, Inc., is added in an amount equal to 1% by weight of the resulting composition. The resulting composition is heated to the isotropic transition temperature of approximately 100 ^° C. and then poured into the empty space. The second electrode is placed over the spacer with the indium oxide coating in contact with the liquid, crystalline composition.

The indium oxide coating is electrical with variable voltage sources tied together. The mapping is done by applying approximately 110 V DC and configuring one image at a time Irradiation of about 4850 Å wavelength at an intensity of about 50 erg / sec for about 1.3 seconds on the photoconductive layer. The deletion takes place by applying 400 V peak up to AC peak at a frequency of 2 kHz for approximately 2 seconds.

An electro-optic useful life of at least about 44,000 imaging cycles will result in no image quality degradation obtain.

Typical batch values:

nematic range: 9 to 99 ° C dielectric anisotropy (at 0.05 V "", 1.0 kHz,

25 ° C) ^pp

= 1.32 = 1.65

specific resistance (at 35.4 V ^ ₀ , 500 Hz, 23 ° C)

Q ^TmS

2.9 x 10 ^ ohm-cm

Threshold voltage: 8.1 V " _mo (60 Hz sine wave) initial transmission: 80% (homogeneous alignment)

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Example 10

Example 9 is repeated except that the tributyltin oxide is omitted. The electro-optical service life is only about 7000 imaging cycles.

While specific components, proportions, arrangements and conditions are preferred in the above description Embodiments of the invention used may include other suitable materials than those given above have been used with equally good results, and the system can be varied to suit the characteristics of the Synergistically influencing, strengthening or otherwise modifying the system according to the invention. Any changes the details, materials, stages, arrangements of parts and uses have only been described to illustrate the nature of the present invention.

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Claims (6)

Claims ι 'J y electro-optical device, characterized in that it has a between two electrodes contains nematic, liquid, crystalline composition in contact with a material selected from the group which contains tributyl tin oxide and tributyl tin chloride. 2. Apparatus according to claim 1, characterized in that the material selected from the group is uniformly dispersed within the liquid crystalline composition. 3. Apparatus according to claim 1, characterized in that the material selected from the group is available in layer configuration. 4. ■ Device according to claim 3, characterized in that g ek e η η draws that the layer of material is in an imagewise configuration. 5. Device according to claim 1, characterized in that g e k e η η that the electrodes are in an imagewise configuration. 6. Apparatus according to claim 1, characterized in that the nematic, liquid, crystalline Composition exists in an imagewise configuration. 7. Method for homeotropic alignment of a nematic, liquid, crystalline composition, characterized in that one (a) creates a substrate and (b) on the substrate, a nematic, liquid, crystalline composition in contact with a material 6098 16/0972 - 31 - 2 Η 4 3 8 4 3 selected from the group consisting of tributyl tin oxide and tributyl tin chloride. 8. The method according to claim 7, characterized in that the material selected from the group is uniformly dispersed within the liquid crystalline composition. 9. The method according to claim 7, characterized in that the material selected from the group is available in layer configuration. 10. The method according to claim 9, characterized in that g e k e η n.-draws that the material selected from the group is in an imagewise configuration. 11. The method according to claim 7, characterized in that the nematic, liquid, crystalline Composition is in an imagewise configuration. 12. A method of providing a nematic, liquid, crystalline composition with an image, thereby g e ■ indicates that one (a) between two electrodes the nematic,
brings liquid, crystalline composition into contact with a material selected from the group which
Contains tributyltin oxide and tributyltin chloride, and (b) applying a voltage along the composition, the optical properties of the neraatic,
liquid, crystalline composition in the fields
change of which are subjected to the applied voltage, being either nematic, liquid, crystalline
Composition or applied voltage are in an imagewise configuration. 609816 / ei 972 INSPECTED 13 · The method according to claim 12, characterized in that the nematic, liquid, crystalline Composition is created in an imagewise configuration, 14. The method according to claim 12, characterized in that the voltage is in an imagewise configuration is created. 15 · The method according to claim 12, characterized in that the material selected from the group is uniformly dispersed in the nematic liquid crystalline composition. 16. The method according to claim 12, characterized in that the material selected from the group is present in layer configuration. 17. The method according to claim 12, characterized in that between the electrodes and the nematic, liquid, crystalline composition, a layer of photoconductive material is provided and that at in carrying out step (b), the photoconductive material is irradiated with actinic radiation in an imagewise configuration will. 18. The method according to claim 17 »characterized in that the photoconductive material arsenic triselenide contains. 19. A method for providing a nematic, liquid, crystalline composition with an image, characterized in that one (a) between two electrodes a nematic ,, brings liquid, crystalline composition into contact with an imagewise formed layer of material which from selected from the group consisting of tributyltin oxide and tributyl 609816/097 2 contains chloride, and (b) applying a voltage across the nematic, liquid, crystalline composition, the optical Properties of the nematic, liquid, crystalline composition at least in the areas thereof which are imagewise shaped layer of material that is selected from the group, change when they match the applied voltage. 20. The device according to claim 1, characterized in that between one of the electrodes and the nematic, liquid, crystalline composition is provided with a layer of photoconductive material. 21. The device according to claim 20, characterized in that the photoconductive material arsenic triselenide contains. 22. Nematic, liquid, crystalline composition, characterized in that it is a nematic, liquid crystalline material and tributyltin oxide, the oxide being present in an amount equal to sufficient to extend the electro-optical useful life of the nematic, liquid, crystalline material. 23. Nematic, liquid, crystalline composition, characterized in that it is at least contains approximately 0.1% by weight of tributyltin oxide and a nematic, liquid, crystalline material. 24. Composition according to claim 23, characterized in that that the tributyltin oxide in an amount up to about 10% by weight, based on the nematic, liquid, crystalline composition, is present. 6098 1 6/0972 25. Liquid, crystalline composition, characterized in that it is a mixture of nematic, liquid, crystalline material and an optically active material and tributyltin oxide, the Oxide is present in an amount effective to increase the electro-optic useful life of the mixture of nematic, To extend liquid, crystalline material and optically active material. 26. Nematic, liquid, crystalline composition, characterized in that it is a mixture of nematic, liquid, crystalline material and an optically active material and at least about 0.1% by weight Contains tributyl tin oxide. 27 · Composition according to claim 26, characterized in that the tributyltin oxide in one Amount up to about 10% by weight, based on the liquid, crystalline composition, is present. 28. Composition according to claim 251, characterized in that the optically active material a liquid, crystalline cholesterol material. is. 29. Composition according to claim 25, characterized in that the optically active material is a non-mesomorphic material. 30. Electro-optical device, characterized in that it is between two electrodes tributyltin oxide in contact with a mixture of a nematic, liquid, crystalline material and an optically active Contains material. 31. The device according to claim 30, characterized in that the oxide is uniform within the Mixture is dispersed. 6 0 9 8 16/0972 - 35 - 2643843 32. Apparatus according to claim 30, characterized in that g e k e η η indicates that the oxide is in a layered configuration. 33. Apparatus according to claim 32, characterized in that the layer of tributyltin oxide in image-wise configuration is available. 34. Apparatus according to claim 6, characterized in that the electrodes are in an image-wise configuration are present. 35. Apparatus according to claim 30, characterized in that the mixture of nematic, liquid, crystalline material and optically active material is present in an imagewise configuration. 36. Process for a mixture of nematic, liquid, crystalline material and optically active material to be provided with a picture, characterized in that one (a) between two electrodes brings the mixture into contact with tributyltin oxide and (b) applying a voltage across the mixture, wherein the optical properties of the mixture are reflected in the surfaces change of those subjected to the applied voltage, either the mixture or the voltage in an imagewise fashion Configuration is available. 37. The method according to claim 36, characterized in that the mixture is in an imagewise configuration present. ' 38. The method according to claim 36, characterized in that the voltage is in an imagewise configuration is created. 6098 16/0972 39 · Method according to claim 36, characterized in that g e k e η η ζ It is certain that the tributyltin oxide is uniformly dispersed throughout the mixture. 40. The method according to claim 36, characterized in that the tributyltin oxide is in a layer configuration is provided. 41. The method according to claim 36, characterized in that between one of the electrodes and the Mixture, a layer of photoconductive material is provided and that further in step (b) the photoconductive Material is irradiated with actinic radiation in an imagewise configuration. 42. The method according to claim 41, characterized in that the photoconductive material arsenic triselenide contains. 43 · Method of using a mixture of nematic, liquid, crystalline material and optically active material to provide a picture, thereby marked, that he (a) a layer of tributyltin oxide between two electrodes in a pictorial configuration in contact with the mixture creates and (b) applying a voltage across the mixture, the optical properties being nematic, liquid, crystalline Composition at least in the areas thereof which are the imagewise formed layer of tributyltin oxide change when subjected to the applied tension. 6 0 98 16 / 097-2 Blank page