CH673032A5 - - Google Patents

Description

DESCRIPTION

The invention is defined in claims 1, 2, 4 and 12 35 and relates to crystalline, liquid 3,3'-sulfinyl or 3,3'-sulfonyl-di- (4-acyloxy-benzoic acid esters) for glass-like nematic liquid crystals, a process for producing the connections that can be used as anisotropic solid optical media for the production of optical components such as compensators, prisms, plates with optical rotation, polarizers and for thermo-electro-optical memory display.

Glass-like liquid crystals are already known H. Kelker, R. Hätz: Handbook of Liquid Ciystals, Verlag Chemie Weinheim 1980; N. Kirov, M.P. Fontana, N. Afanassieva, Mol. Ciyst. Liq. 45 Cryst. 89, 193 (1982). The glass temperatures are usually far below 0 ° C, e.g. for N- (o-hydroxy-p-methoxybenzylidene) -p-butyl-aniline M. Sorai, S. Seki, Bull. Chem. Soc. Japan 44: 2887 (1971); G.P. Johari, Phil. Magaz. B 46, 549 (1982) at -65 ° C. Substances with such low glass temperatures cannot be used at room temperature in the usual nematic state and as anisotropic solid optical media or for thermo-electro-optical storage displays.

The aim of the invention is anisotropic solid optical media for the production of optical components and for thermo-electro-optical memory displays.

The object of the invention is the use of glass-like nematic liquid crystals, the glass temperature of which is above room temperature.

It has been found that crystalline liquid 3,3'-sulfinyl or 60 3,3'-sulfonyl-di - [(4-acyloxy) benzoic acid esters] of the general formula

> -C00Cn "2n, l r

A ~ ^ ~ Öy ~ CCOC

nH2inl

3rd

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in which

A = _ <2> -C00) z -, CmH2m + 1- <V> -C00-

r1 "Cm ^ 2ra + 1 ~ 'CmH2ni + l0 ~' C", H2m + 1000 "

with x = 1 or 2, z = 1 or 2, n, m = 1 to 10, in mixtures with one another, in mixtures with 4- [4- (4-substituted-benzylideneamino) -naphthyl- (l) - ethyl azo] -benzoic acid, biphenyl-4,4-bis- (4-carbonyloxybenzylidene-malonic acid-di-n-alk-yl ester), 4- (4-alkylcyclohexanoyloxy) -2-methylbenzoic acid (4-substituted phenyl ester) or with other crystalline-liquid or non-crystalline-liquid substances as glass-like nematic liquid crystals with glass temperatures above room temperature as anisotropic solid optical media for the production of optical components such as compensators, prisms, plates with optical rotation, polarizers and for thermo-electro-optical storage displays are.

By producing appropriately oriented layers, optical compensators, prisms and, with the addition of dichroic dyes, polarizers, with twisted orientation, plates with optical rotation and, if appropriate cells, thermo-electro-optical memory displays are used can be produced from these optical media.

The substances are colorless, chemically and thermally stable and can be produced in good purity. They are readily miscible with one another and with other crystalline-liquid substances, the melting points in the mixtures being lowered, but the clearing points being sufficiently high since they correspond approximately to the mean value of the components of the mixture.

The 3,3'-sulfinyl-di (4-acyloxy-benzoic acid ester) and 3,3'-sulfonyl-di (4-acyloxy-benzoic acid ester) according to the invention of the general formula I are, for example, by reaction of carboxylic acid chlorides of the general formula II and III, in which z and m are as defined above, and 3,3'-sulfinyl-di (4-hydroxy-benzoic acid ester) or 3,3'-sulfonyl-di (4-hydroxy-benzoic acid ester) of the general formula IV, in which x and n are as defined above, in a molar ratio of 2: 1 in the presence of organic bases, preferably pyridine.

Cß) H2li! + L

II

III

HO- <0> -C00CnH2n + 1

S0X

HO- £ Ö) -COO <yi2n + 1

IV

It has proven to be advantageous to carry out the reaction in organic solvents, such as benzene or toluene, at temperatures between room temperature and reflux of the solvent. The starting products II, III and IV (only for n = 1) are known and are prepared using known processes (IV according to Denisova, LI; Sorokina, ON; Kondrat'ev, VP: Chim. Farm. Z. 15 [1981] 33) produced.

The compounds of the general formula I are obtained in good yields as colorless, crystalline compounds by the process according to the invention.

An advantage of the invention is that 3,3'-sulfinyl-di- (4-acyloxy-benzoic acid ester) and 3,3'-sulfonyl-di (4-acyloxy-5-benzoic acid ester) of the general formula I by using the easily accessible Carboxylic acid chlorides of the general formulas II and III and the 3,3'-sulfinyl-di (4-hydroxy-benzoic acid ester) or 3,3'-sulfonyl-di (4-hydroxy-benzoic acid ester) of the general formula IV in preparative light are realizable to be realized.

It was further found that homogeneously oriented nematic liquid crystals in the glass state with the addition of one or more dichroic dyes or homogeneously oriented dichroic colored liquid crystals in the glass state are well suited as polarizers.

Compounds of the formula 1,4- [4- (4-substituted-benzylidenamino) naphthyl- (l) -azo] benzoic acid ethyl ester, biphenyl-4,4'-bis- [4-carbonyloxy- benzylidene-malonic acid di-n-alkyl ester] and 4- (4-alkylcyclo-20 hexanoyloxy) -2-methylbenzoic acid (4-substituted phenyl ester) are suitable.

The liquid crystals are oriented at temperatures above the glass temperature in the nematic state with the addition of one or more dyes between solid substrates according to methods known per se and converted into the glass state by rapid cooling, with stable polarizers being formed.

It was also found that nematic liquid crystals in the glass state are outstandingly suitable for producing anisotropic optical media. The nematic liquid crystals 30 are oriented above the glass temperature in the electrical and / or magnetic field or by the action of the adjacent walls and then converted into the glass state by cooling. Either the limiting disks made of glass or other transparent media required for the orientation of the nematic phase remain in the glass state even after transfer, or materials are used for the limitation, which can be dissolved away in a solvent in which the glass phase is insoluble. If the bounding walls have a certain shape, then lenses, io prisms or other bodies can be made directly from the nematic glass-like phases.

For the solution according to the invention, nematic liquid crystals of the compounds of the formula I and of the 4-4- (4-Subst.-benzylidenamino) -naphthyl- (l) -azo-benzoic acid ethyl ester 45 are suitable.

The optical components from the glass-like nematic phases have good mechanical stability and only a very low temperature dependence of the optical properties. They can also be made as large pieces at a relatively low price.

On the one hand, the optical components can be manufactured homogeneously by the nematic phase above the glass state being oriented homogeneously; on the other hand, inhomogeneous optical components are obtainable through inhomogeneous orientation, e.g. twisted 55 orientation, in which the components are given the ability to rotate the plane of polarization of linearly polarized light.

It was also found that thermo-electro-optical memory displays can be realized by using nematic liquid crystals of the compounds according to the invention in the glass-60, which are enclosed between electrically conductive panes and into which information is written and thermally activated and at the same time applying an electrical field can be erased by heating up above the glass temperature without an electrical field, or in which 65 inscriptions and erasures are carried out in the reverse order by these processes.

Another variant is that the dielectric positive nematic layer twists in the cell (mechanical or

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due to the slight addition of cholesteric substances) and between two polarizers.

Further variants consist in that the variants described above for writing or deleting the information are operated with alternating electrical voltages below or above the relaxation frequency of the nematic liquid crystal (dual frequency control). It is also possible to work in such a way that the nematic layers oriented or twisted parallel or perpendicular to the electrodes contain one or more positive dichroic dyes or one or more colored liquid crystals, with no or only one polarizer being necessary.

Further variants consist in that the nematic layers oriented parallel or perpendicular to the electrodes contain one or more negative dichroic dyes or one or more colored liquid crystals, only one polarizer being required; in these cases, dichroic dyes or liquid crystals can be added for two-color display. Likewise, the transmitted light variants described above can be operated with a mirror and then in incident light.

Another possibility is that a negative dielectric nematic substance is excited under the conditions of the dynamic scattering effect above the glass temperature, wherein the excited parts of the display surface in the glass state can serve as a mechanically stable screen.

Practical examples

The invention is to be explained in more detail for the preparation of the substances on the basis of the examples below and the data in the table.

example 1

0.5 g (0.00143 mol) of 3,3'-sulfinyl-di (4-hydroxy-benzoic acid methyl ester) are taken up in 10 ml of dry benzene and 2 ml of dry pyridine are added.

0.69 g (0.00286 mol) of 4-n-hexyloxy-benzoic acid chloride, dissolved in 10 ml of dry benzene, are added dropwise. The mixture is heated under reflux for one hour, the solvent is largely stripped off in vacuo and the residue is poured onto ice. 3,3'-sulfinyl-di [4- (4-n-hexyloxy-b enzoyloxy) b enzo es methyl ester] precipitates.

Yield: 0.7 g (65%), recrystallization from ethanol, melting point of the most stable modification: 146 ° C. Clear point: 121 ° C.

Example 2

0.5 g (0.00136 mol) of 3,3'-sulfonyl-di (4-hydroxy-benzoic acid methyl ester) are taken up in 10 ml of dry toluene and 2 ml of dry pyridine are added, whereupon a clear solution forms. 0.65 g (0.00272 mol) of 4-n-hexyloxybenzoic acid chloride, dissolved in 10 ml of dry toluene, are added dropwise, the solution becoming cloudy. The reaction mixture is left to stand at room temperature for 12 hours, the solvent is largely stripped off in vacuo and the residue is poured onto ice. 3,3'-Sulfonyl-di [4- (4-n-hexyloxy-benzoyloxy) benzoic acid methyl ester] precipitates.

Yield: 0.8 g (76%), recrystallization from ethanol, melting point of the most stable modification: 152 ° C. Clarification point: 163 ° C.

The table shows the data of various 3,3'-sulfinyl-di (4-acyloxy-benzoic acid esters) and 3,3'-sulfonyl-di (4-acyloxy-benzoic acid esters).

A in Forraol X x z m n Fp ^ 'Klp.

ISO 210 189

172 110,

• 148 117

146 121

125 118 131 119 109 87 118 77

118 ne

226 217

209 161

174 170

170 159

152. 163 144. 155

139 151

126 116 ОOS 104 100 Ö22) 141 144 102 102 208 218 220 258

^ «♦ l-®-00- 2" 5 l ^ "164

1) Melting point of the most stable crystal modification 35 2) Crystallization of the melt from 90 ° C, liquid-crystalline and solid phase are side by side.

The following examples relate to the application.

40 Example I

The substances of the general formula

Cm '-, 2m + l0- <2>: C00 - ^) - c00

? L

Cn »H2m * l ° - (V-C00 - (^) -co ° CH3

50

with m = 7, 8 and 9 are mixed in an equimolar ratio. The result is a homogeneous mixture with a stable melting point of 121 to 122 ° C and a clearing point of 55 148 ° C.

The glass temperature is above room temperature. If the substance oriented above the melting point due to wall effects, electrical or magnetic fields is rapidly cooled to 0 to 5 ° C., a glass-like nematic phase which is stable at room temperature is obtained, the orientation of which corresponds to the orientation obtained above the melting point. By re-heating to temperatures above 100 ° C, the orientation can be changed and then cooled back down to the glass temperature. The orientation obtained in the glass state is stable for at least several months.

CraH2n, + l- (° -

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Example II

The mixture of Example I is 20 mol% of the substance

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CH3 ° - -CW "N - ^) - N = N- (o) -C0002He

(Transition temperatures of this substance: K 143 N 207 is, Baentsch, dissertation Halle 1931) added. A mixture is obtained which is completely melted at 125 ° C., the clearing point of which is 158 ° C. and which is glass-like nematic at room temperature. The glass temperature is considerably above the room temperature, but below 100 ° C. At temperatures above 100 ° C, the orientation can be changed and is retained if the temperature is quickly cooled to room temperature.

Example III

1% by weight of the dichroic red dye Wolfen 4 is added to the mixture from Example I.

° 2N "-N" N- (°) -N.

CH., OH / *

\

C2H5

given. The mixture is brought in a thin layer (10-50 pm) between two panes of glass, quartz, transparent polymer or other transparent material and at a temperature between 122 ° C and 148 ° C in the nematic state according to methods known per se in magnetic or electrical field or wall effect on appropriately pretreated substrates with a homogeneous orientation, resulting in a layer due to the positive dichroism of the dye, which generates linearly polarized red light. By rapid cooling to 0 to 5 0 C, the nematic layer changes into the nematic glass state, which is stable even at room temperature and has the properties of a colored polarizer.

Example IV

The dye in Example III is replaced by other liquid crystal soluble dichroic dyes e.g. Methyl red, anthrachi non-dyes, azo dyes, replaced, making polarizers of the appropriate color accessible. By mixing several dyes, polarizers are obtained which linearly polarize the entire visible spectrum and thus generate white polarized light.

All of the dyes mentioned in Examples III and IV are also soluble in the mixture mentioned in Example II and give corresponding polarizers.

Example V

4,4'-bis- (4-carbonyloxybenzylidene-malonic acid-di-n-alkyl esters) of the general formula are also used for the production of polarizers

(- (7) .coo- (ô) -CH-C

/ \

COOG "H,

n2n + l

C00Cn "2n + l with n = 1 to 4 can be used, all of which solidify glass-like nematic at room temperature.

Example VI

A nematic substance that enters the glass phase at temperatures above room temperature is filled in between two panes, which are kept at a defined distance by spacers, in the nematic state above the glass temperature. By applying a magnetic field with a strength of at least about 0.2 Tesla, the nematic substance is oriented homogeneously so that, depending on the direction of the magnetic field, the nematic director is oriented parallel or perpendicular to the limiting disks, which is perpendicular to a cut through the nematic optically uniaxial medium or paral-5 lei corresponds to the optical axis. By tilting the magnetic field relative to the disks, all orientations in between can also be achieved. The oriented nematic liquid crystal is now converted into the glass state by cooling, the orientation of the nematic liquid crystal being retained unchanged. Due to the glassy consistency of the nematic liquid crystal, however, the mechanical properties become quite stable, the deformability is low, and due to the constant degree of order of the nematic phase, the temperature dependence of the optical properties such as optical refractive indices, birefringence and dispersion is low.

The panes used to manufacture the component can be made of glass, quartz, solid crystals, polymer films or other materials, which must be transparent or non-transparent depending on the desired direction of radiation.

Example VII

The orientation of the nematic liquid crystal above 25 glass temperature is done by electric fields. For this purpose, the panes of the arrangement in Example VI are coated on the inside with an electrically conductive layer, e.g. Tin dioxide, coated and generated by applying an electrical field, preferably alternating field, a voltage above the threshold voltage of the nema-3o table liquid crystal, a homogeneous orientation. If the nematic liquid crystal has a positive dielectric anisotropy, an orientation of the optical axis parallel to the electric field is obtained, with a negative dielectric anisotropy an orientation perpendicular thereto. By applying magnetic and electrical fields simultaneously, the orientation effect can be strengthened or weakened depending on the relative orientation of the two fields.

Example VIII

40 The orientation of the nematic liquid crystal above the glass transition temperature is determined according to known methods J. Cognard: Mol. Ciyst. Liq. Cryst. Suppl. 1 (1982) by the action of the limiting disks. For this purpose, panes are used on which layers of solid substrates such as SiO are vapor-deposited obliquely at an angle of 45 to 80 ° E. Guyon, P. Pieranski, M. Boix: Lett. Appi. Closely. Sci. 1.19 (1973) or which are rubbed homogeneously in a certain direction, or the surfaces of which are pretreated with long-chain alcohols or other organic substances. The nematic director orientates himself parallel to the surface of the panes. Using this process, homogeneous layers up to layer thicknesses of approx. 0.2 mm can be produced.

If the panes are steamed at an angle of over 85 ° or pretreated with lecithin, carboxylic acids, silanols or other special substances, layers up to 0.2 mm thick can be produced, the director of which is uniaxial.

After the appropriate orientation above the glass temperature, the preparations are brought into the glass state by cooling, as in Example VI.

Example IX

If obliquely steamed or rubbed or coated with special chemical substances 65 disks are used to manufacture the preparation, which orient the director of the nematic phase above the glass temperature parallel to the substrate, but the preferred directions of the two disks are rotated at an angle to each other, a layer is formed , Which

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the plane of polarization of linearly polarized light rotates by exactly the angle through which the preferred directions of the two disks are rotated. After the preparation has cooled below the glass transition temperature, a mechanically stable component is created which, regardless of the temperature and the dispersion, rotates the plane of polarization of linearly polarized light by a certain angle and is suitable as an optical component for the construction of optical devices due to this property.

Example X

If optical components are to be produced which no longer contain any bounding walls or panes, then for the purpose of orienting the nematic liquid crystal above the glass temperature according to Example VI-IX not insoluble panes, but rather bounding panes made of a material which is in a solvent in which is used the liquid crystal does not dissolve, is soluble. Water-soluble materials such as polyvinyl alcohol, NaCl, KBr are then preferably used. The oriented preparation is cooled below the glass temperature as in the previous examples. Then the walls delimiting the glassy liquid crystal are detached.

Example XI

Optical components of a certain shape such as lenses, prisms, etc. can be produced by the limiting disks having a corresponding shape, so that the nematic phase adapts to the desired shape after being oriented in the electrical and / or magnetic field above the glass transition temperature, which after cooling below the glass temperature is maintained. After mechanical removal or dissolution of the limiting disks, an optical component of the desired shape is then obtained.

Since the nematic liquid crystals can also be mechanically processed in the glass state (sawing, cutting, bending, drilling), components of the desired shape can also be obtained by mechanical processing.

Example XII

Any pure nematic or nematic mixture whose glass temperature is above room temperature and below the clarification temperature can serve as the nematic material for the processes described in Example VI-XI.

In particular, the mixture according to Example I has proven to be very suitable.

Example XEH

Instead of the mixture given in Example I, the mixture according to Example II can also be used. The occurring dielectric anisotropy Ae is negative, i.e. in the electric field (20 V / 50 Hz at 100 ° C) the substance is oriented perpendicular to the direction of the field.

Example XIV

The memory display can be realized by an arrangement of the following type:

Two glass panes vapor-coated on the inside with electrically conductive tin dioxide, which had previously been treated with a dilute solution of lecithin, are brought to a distance of 10 μm by means of spacers. The space between the glass panes is filled with a nematic mixture according to Example II.

The mixture has the following properties: melting up to 125 ° C, clearing point 158 ° C, Ae <0, glass transition temperature about 60 ° C.

At room temperature, this mixture is nematic in the glass state and uniaxial, i.e. dark between crossed polarizers. The information is written in by point-by-point heating using a laser or mechanical point-by-point heating, with the nematic being briefly

Mixture preferably heated to about 120 to 130 ° C above the glass temperature and at the same time an electrical voltage (50 V, 0 to 100 Hz) is applied. The resulting reorientation to a lying nematic layer, which remains in the glass state even after 5 cooling, is noticeable by a brightening between crossed polarizers. The information written in can be deleted again by briefly heating the glass temperature either locally or over a large area without an electric field, as a result of which the uniaxial, homeotropic initial state is reached. The information written in (depending on the type of heating, point by point, in the form of characters, pictures or even large areas) can be stored for any length of time and can be made visible by lighting from behind or in projection. If a mirror is placed behind the arrangement, the memory display is suitable for reflected light operation. The reproduction in different colors is possible by not applying the saturation voltage for writing the information, but lower values.

20 As with black-and-white information, the colored information is deleted by briefly heating it above the glass temperature without applying any voltage. The information is also written selectively by means of the applied voltage if the electrodes have a specific shape and the voltage therefore does not act in the entire area and is simultaneously heated above the glass temperature in the entire area. Here, too, is extinguished by briefly heating above the glass temperature without applying the voltage.

30 It is also possible to write the information in such a way that the entire surface is initially reoriented above the glass temperature by applying a voltage, and the selective re-orientation is carried out by selectively heating individual areas. This makes it particularly easy to write in entire images of negatives or 35 projections.

Example XV

The following mixture is brought between two glass panes which have been obliquely vaporized with tin dioxide and SiO at an angle of 50 to 75 ° and which are fixed at a distance of 4 to 10 μm.

45

50

CsH170. (7) -COQ-g) -COOCHj t. so2

-eoo- fr) -COOCHg C4H9-0 -COO- <V> -COO.® ~ CN

85 mol%

CH ".

15 mol.- '

The mixture has the following properties:

55 Melting 130 ° C, clearing point 154 ° C, glass temperature about 75 ° C Ae> 0.

The mixture is oriented in the nematic state lying in relation to the glass panes; this orientation is maintained at -60 even in the glassy nematic phase at room temperature. The preparation is bright in a 45 ° position between crossed polarizers. By briefly heating as described in Example XIV and simultaneously applying a voltage of 50 V / 30 Hz, the reorientation into the home-tropical orientation, i.e. Registered information, reached. 65 To extinguish, briefly heat up without electrical voltage.

Color reproduction is achieved by applying lower voltages when writing. The colors follow

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the tensions:

As in Example XIV, you can also selectively write in via the voltage or by first reorienting the entire surface above the glass temperature with the voltage applied and selectively heating individual areas. As previously explained, the display can be operated in transmitted light or incident light.

By attaching a compensator in the subtraction or addition position, the path difference in the lightened state of the cell can be changed as desired.

Example XVI

A storage display is implemented by the following arrangement:

A glass pane with a vapor-deposited electrode is treated in such a way that the nematic layer is oriented parallel to the surface, the other electrode in such a way that the nematic layer is oriented homeotropically (erected uniaxially). This arrangement is also known as a P-N cell from DD patent 117013.

If the substance of Example II (negative dielectric anisotropy) is introduced, the transparent (light-white or colored) state can be written in by heating above the glass transition temperature and simultaneous application of electrical voltage, which state returns to a less transparent state by heating without electrical voltage . This state is expediently compensated for by a compensator in the subtraction position for darkness between crossed polarizers.

If the substance of Example XV (positive dielectric anisotropy) is introduced, the various colors are first run through by heating above the glass temperature and simultaneous application of increasing voltages, and finally the state of darkness between crossed polarizers is reached, that is, by heating without electrical voltage returns to the initial state. The path difference can be increased or decreased by adding a compensator.

As explained in examples XIV and XV, here too, in the cell, an initial state is created by heating to above the glass temperature and simultaneous application of voltages in the entire area, in which the information is written in certain areas by selective heating.

The display can be operated in transmitted light and in reflection. The stored information can be kept for any length of time.

Example XVII

A cell with a twisted nematic layer is used and the substance from Example XV (positive dielectric anisotropy) is used. In the initial state, the cell in the nematic state and in the nematic glass state has the ability to rotate the plane of polarization of linearly polarized light by the twist angle of the nematic layer (preferably 90 °): i.e. brightening occurs between crossed polarizers, darkness between polarizers twisted relative to one another by the twist angle. The information is written in by heating above the glass temperature and simultaneous application of a voltage of 50 V / 30 Hz, i.e. the layer is twisted and there is darkness between crossed polarizers and brightness between twisted polarizers. After cooling, this state is saved below the glass temperature. The initial state is reached by heating above the glass temperature without electrical voltage.

If a positive dichroic dye is added to the substance, then a color display is made with only one or no polarizer, with the addition of e.g. 1% methyl red reached a red representation of the information.

Dye mixtures, anthraquinone dyes and various azo dyes are also suitable for achieving other colors.

Example XVIII

If the substance in Example II is a positive dichroic dye, e.g. 1% methyl red, added, in the arrangement described in Example XIV a colored representation of the information is achieved with or without a polarizer. Dye mixtures can also be used to achieve other colors.

Example XIX

If the substance in Example XV is used as a positive dichroic dye 1% methyl red or as a negative dichroic dye 5% 3-n-propyl-6- [4- (4-n-hexylbenzoyloxy) phenyl] -1,2,4,5- tetrazine, a colored representation of the information is achieved. The simultaneous addition of positive and negative di-chroic dyes gives two-color representations of the information. Dye mixtures are also suitable for achieving other colors.

Example XX

The displays of examples XV, XVII and XIX can be operated for writing or erasing with frequencies below (0 to 100 Hz) or above the relaxation frequency (10 to 100 kHz) of the nematic substances while heating above the glass temperature (dual frequency control).

Example XXI

A layer of 10 (im in the dielectric negative anisotropic substance of Example II is placed between two glass panes coated with tin dioxide. By applying 20 V direct voltage or low-frequency alternating voltage (below 50 Hz), the dynamic scattering effect is induced at 100 to 130 ° C., ie the information is written in. The information is erased by heating above the glass temperature without electrical voltage.

The information can also be electrically written in by appropriately shaped electrodes if the entire surface is heated above the glass temperature at the same time.

An initial state is also established by heating the entire layer above the glass transition temperature and simultaneously applying the voltage throughout the layer and cooling. If the glass temperature is exceeded again selectively without an electrical field, the information is written in.

The nematic phase, which has been cooled to below the glass transition temperature and is in the state of dynamic scattering, can be used as a focusing screen; the higher the voltage used for excitation, the stronger the light scatter and the fine grain of the scatter plate.

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Claims (13)

673 032 PATENT CLAIMS 1. Crystalline liquid 3,3'-sulfinyl or 3,3'-sulfonyl-di- (4-acyloxy-benzoic acid esters) of the general formula —COO-C II, P- »• so.; n + l A- / oVcOO-cnH n 2ri + l where A = R ^ - ^ - COO) ^, CmH2m + 1-0-COO- ßl = CmH2m + l- 'CmH2m + l0-' Cn, H2m + 1C00- withx = 1 or 2; z = 1 or 2; n, m = 1 to 10 mean. 2. A process for the preparation of new crystalline liquid 3,3'-sulfmyl-di (4-acyloxy-benzoic acid ester) and 3,3'-sulfonyl-di (4-acyloxy-benzoic acid ester) according to claim 1, characterized in that carboxylic acid chlorides the general formula C «H2n + i-t0- (f} -C0> z-Cl or «H2n, + l - \ ^> - C0C1 ' in which z and m have the meaning given in claim 1 and 3,3'-sulfmyl-di- (4-hydroxy-benzoic acid ester) or 3,3'-sulfonyl-di (4-hydroxy-benzoic acid ester) of the general formula H ° - ^) - C00CnH2n + 1 SO x HO- / oV-COOC_H, n 2n + l in which x and n have the meaning given in claim 1, are reacted in a molar ratio of 2: 1 in organic solvents in the presence of organic bases. 3. The method according to claim 2, characterized in that the reactants are reacted in benzene or toluene at temperatures between room temperature and reflux of the solvent. 4. Glassy nematic liquid crystal mixtures, characterized in that they contain crystalline liquid sulfinyl or sulfonyl benzene esters according to claim 1 in mixtures with one another or in mixtures with other crystalline liquid or non-crystalline liquid substances. 5. Glass-like nematic liquid crystal mixtures according to claim 4, characterized by the addition of one or more dichroic dyes or homogeneously oriented dichroic liquid crystals in the glass state. 6. Glass-like nematic liquid crystal mixtures according to claim 4 for thermo-electro-optical memory displays, characterized by a substance with negative dielectric anisotropy, consisting of a mixture of 80 mol% 3,3'-sulfonyl-di- [4- (4-n -octyloxybenzoyloxy) -benzoic acid methyl ester] and 20 mol% of 4- [4- (4-methoxybenzylidenamino) -naphthyl- (l) -azo-benzoic acid ethyl ester. 7. Glassy nematic liquid crystal mixtures after Claim 4 for thermo-electro-optical memory displays, characterized by a substance with positive dielectric anisotropy, consisting of a mixture of 85 mol% of 3,3'-sulfonyl-di- [4- (4-n-octyloxybenzoyloxy) benzoic acid methyl ester] and 5 15 mol% of 4- (4-n-Bu1ylcyclohexanoyloxy) -2-methylbenzoic acid [4-cyanophenyl ester]. 8. Glass-like nematic liquid crystal mixtures according to claims 4 and 5 for thermo-electro-optical memory displays, characterized in that the nematic layers Contain 10 or more positive dichroic dyes or colored liquid crystals. 9. Glass-like nematic liquid crystal mixtures according to claims 4 and 5 for thermo-electro-optical memory displays, characterized in that the nematic layers Contain 15 or more negative dichroic dyes or colored liquid crystals. 10. Glass-like nematic liquid crystal mixtures according to claims 4 and 5 for thermo-electro-optical memory displays, characterized in that they are positive and negative at the same time Contain 20 dichroic dyes or colored liquid crystals. 11. Glass-like nematic liquid crystal mixtures according to claim 4, characterized by the addition of the compounds 4- [4- (4-substituted benzylidenamino) naphthyl- (l) -azo] -benzoic acid, ethyl ester, biphenyl-4,4'-bis - [4-carbonyloxybenzylidene - 25 malonic acid di-n-alkyl ester], or 4- (4-alkylcyclohexanoyl-oxy) -2-methyl-benzoic acid (4-subst. Phenyl ester) as other crystalline liquid substances. 12. Optical components containing glass-like nematic liquid crystal mixtures according to claim 4. 30th