KR830001093B1 - Composition for liquid crystal color display element - Google Patents

Abstract

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Description

Composition for liquid crystal color display element

1 is a front view of a combined liquid crystal display device combining the composition of the present invention,

2 is a cross-sectional view taken along the line a-a of FIG.

The present invention relates to a composition for a liquid crystal color display device using an electron optical effect containing a nematic liquid crystal and a dichroic dye. In particular, the present invention relates to a composition for nematic liquid crystal color display device in which at least one dichroic anthraquinone dye of the following structural formula (I) is dissolved, and the composition is a dichroic anthraquinone type of the following structural formula (II). It is preferable to include one or more dyes.

(Ⅰ)

(Ⅰ)

Wherein X and X 'are the same and represent a -NH ₂ or -OH group, R is a linear or branched alkyl group, cyclohexyl group, or structural group of formula -R ₂ -OR ₃ wherein R ₂ is An alkylene group having 1 to ₃ carbon atoms, R ₃ is a linear or branched alkyl group having 1 to 15 carbon atoms).

Wherein R ₁ is a straight or branched chain alkyl group having 5 to 15 carbon atoms.

This composition is used for display devices operated by the electro-optical effect of nematic liquid crystals.

Liquid crystal displays containing dichroic dyes are already known in the liquid crystal art as "guest-host" type displays and are used as displays in watches, portable electronic calculators and televisions.

The theory of this type of display is based on the arrangement of dichroic dye molecules by the arrangement of the molecules of the liquid crystalline material. In particular, liquid crystal molecules change from an "off" state to an "on" state and are oriented by the application of an external stimulus, which is usually an electric field, so that the dichroic dye molecules are also oriented simultaneously. As a result, the light absorption by the dye molecules in both states is changed to enable color display.

This electro-optical effect means liquid crystal color display using the so-called guest-host effect. The guest-host type uses a nematic liquid crystal having positive or negative dielectric anisotropy and a liquid crystal showing a phase transition from the cholesteric phase to the nematic phase upon application of the electric field. It is currently working.

Several kinds of dichroic dyes operating on this theory are known to date, but none of them have been commercially satisfactory. Thus, the development and commercialization of liquid crystal color display devices based on this theory have been partially impeded.

Dichroic dyes used in liquid crystal color displays based on this theory must meet certain basic requirements.

For example, they generally require sufficient colorability, high dichroic ratios to enable high contrast in the absence of voltage or high voltage, sufficient solubility in liquid crystals, good durability and stability, even in small amounts. Do not damage the device if used for a while.

The present invention relates to an anthraquinone type dye of formula (I) or (II) as a dichroic dye that meets these requirements.

The anthraquinone dyes of formula (I) or (II) can be prepared by various methods as described below.

(1) 1,5-dihydroxy-4,8-diamino-anthraquinone-2,6-disulfonic acid (called alizarin sapyrol B) in a sulfuric acid in the presence of boric acid, the alkoxyphenyl compound of formula (III) After reacting with, the boric acid ester group is hydrolyzed and the resulting compound is then desulfonated to prepare.

Wherein R ₁ is as described above.

(2) Method of reacting quinoneimine of 1,5-diamino-4,5-dihydroxy-anthraquinone with a compound of formula III

(3) After reacting 1,5-dihydroxy-4,8-dinitro-anthraquinone with the compound of formula (III) in the presence of boric acid and an acid condensate, the boric acid ester group is hydrolyzed and the nitro group of the compound thus obtained is an amino group. Reduction method.

In this method, the reaction of the boric acid ester of 1,5-dihydroxy-4,8-dinitro anthraquinone with the alkoxyphenyl compound is preferably performed at low temperature. The reaction may be carried out at a temperature of 0 ° C. or lower. The acid condensates used allow the phenyl substitution to proceed fully, especially sulfuric acid at various concentrations, due to economic advantages.

Other usable solvents include phosphoric acid, acetic acid and other organic solvents. Sometimes it is desirable to use mixtures of these solvents.

The alkoxy phenyl compound is synthesized by reacting phenol with an alkyl halide or the like in the presence of a base.

The boric acid ester of the 1,5-dihydroxy-4,8-dinitro-anthraquinone and the alkoxyphenyl compound are conveniently used in the same molar amount, and a slight excess of the alkoxyphenyl compound may be used.

As a result, half of the resulting mixture is poured on ice to partially hydrolyze the borates. To complete hydrolysis, boil the water suspension. The anthraquinone compound obtained as a result of having a phenylene substituted group in the 2-position can be easily converted into a blue dye by reducing the nitro group to an amino group. Structural formula (II) compound obtained by this method is especially a dye which has the outstanding dichroic ratio.

(4) 2-4'-hydroxyphenyl anthraquinone derivative obtained by the method (1)-(3) using phenol instead of the compound of formula (III) in the presence of an alkyl halide and a basic catalyst of formula (IV) or The reaction is carried out without a catalyst or under the same conditions as tosyster of formula (V).

R ₂ -Hal (Ⅳ) R ₂ -O-Ts (Ⅴ)

Wherein R ₂ is any branched alkyl group or cyclohexyl group having 1 to 15 carbon atoms, Hal is a halogen atom, and Ts is a tosyl residue.

(5) Reacting 1,5-dihydroxy-4,8-diamino-anthraquinone-disulfonic acid (alizarin sapyrrole B) with a compound of formula III in sulfuric acid in the presence of boric acid, the product is sodium hydrosulfite Treatment with a reducing agent such as to remove the sulfone group, followed by hydrolysis to convert the amino group to a hydroxyl group.

Next, the method of oxidizing the colorless derivative of tetrahydroxy anthraquinone of the structural formula (I) as a result by a well-known method.

Since the resulting crude dye often contains inorganic salts and other impurities, it is preferable to extract or recrystallize with an organic solvent and to purify with thin layer chromatography or column chromatography.

By using the anthraquinone type dye (I) according to the present invention, a clear blue or red color liquid crystal which cannot be obtained with ordinary dichroic dyes can be obtained, and these have a remarkably high dichroic ratio (contrast) and excellent light sensitivity. Has

Typical examples of anthraquinone type dyes (I) are listed in Tables 1 and 2.

Table 1

TABLE 2

The invention is explained in more detail in the drawings. In the figure, the nematic liquid crystal material colored with dye is filled in layer 1 sandwiched between two parallelly placed glass surfaces 2 and 3. Glass surfaces 2 and 3 are spaced from each other by spacers 4 which border the ends of layer 1.

Glass surfaces 2 and 3 have transparent electrodes 5 and 6 on their inner surfaces, respectively. The electrode 5 is also connected to the external line 9 through the contact surface 7, and likewise the electrode 6 is connected to the external lead line 10 through the contact surface 8.

The electrodes 5 and 6 are rectangular in shape and are arranged to face each other. The power supply 12 and switch 11 connected here in series are connected between the external lead lines 9 and 10.

The power source 12 supplies a direct current or low frequency alternating current sufficient to redirect the liquid crystal molecules and the dichroic dye molecules in layer 1, and is arranged on the inner surfaces of the glass surfaces 2 and 3.

Usually 10 to 20 volts is sufficient.

Examples of nematic liquid crystals used in the present invention include 4-cyano-4'-n-pentylbiphenyl 43%, 4-cyano-4'-n-propoxy-biphenyl 17%, 4- It is a mixture consisting of 13% of cyano-4'-n-pentoxybiphenyl, 17% of 4-cyano-4'-n-octoxybiphenyl and 10% of 4-cyano-4'-n-pentylterphenyl. The so-called nematic liquid crystal mixture obtained by adding 3% of clesteryl no nanoate, 3% of cyano-4'-isopentylbiphenyl which is optically active to the mixture can also be used.

In addition to the foregoing examples, biphenyl type liquid crystal phenylcyclohexane type liquid crystal, Schiff base type liquid crystal, ester type liquid crystal, pyrimidine type liquid crystal, tetrazine type liquid crystal, and other nematic liquid crystals having positive or dielectric anisotropy are in the form of single or mixtures. It can be used as the nematic liquid crystal of this invention.

Dichroic dyes in the present invention can also be used as single compounds or mixtures. The concentration of the dichroic dye in the liquid crystal material is such that the dye is dissolved in the liquid crystal and the dye molecules are sufficiently oriented according to the alignment of the liquid crystal molecules. In general, suitable dye concentrations are 0.01-20% by weight (preferably 0.01-1% by weight) based on the liquid crystal material.

In the present invention, the dichroic dye may be mixed with other dichroic dyes or non-dichroic dyes or colorants to obtain a desired color.

In the case of making such a liquid crystal display device, the transparent electrode is processed in advance so that the liquid crystal molecules and the dichroic dye molecules are aligned in parallel or perpendicular to the surface of the transparent electrode. Such treatment may, for example, previously coat the electrode with a silicon compound, deposit silicon oxide or with a silicon compound, deposit silicon oxide vapor and then deposit the surface of the transparent electrode with a cotton cloth in a direction. This can be done by rubbing.

When a solution consisting of a nematic liquid crystal having a positive dielectric anisotropy of the present invention and a dichroic dye is filled into a liquid crystal display device which is treated such that the liquid crystal and the dye molecules are aligned in parallel with the surface of the transparent electrode, the display device comprises an electrode portion. The color of the device is such that it disappears when a voltage is applied.

When a solution consisting of a nematic liquid crystal and a dye having a negative dielectric anisotropy of the present invention is filled into a liquid crystal display device in which the liquid crystal and the dye molecules are oriented perpendicular to the surface of the transparent electrode, the display device applies a voltage. When the color of the electrode part appears.

The display devices shown in FIGS. 1 and 2 are designed to see the transmitted light. This device becomes a reflective display device by replacing the glass plate 2 with a non-transparent reflecting plate or by placing the reflecting plate behind the glass plate 2 so that it can be seen from the front of the glass plate 3.

In making the liquid crystal color display device using the dichroic dye of this invention, the kind of liquid crystal and its manufacturing method can be varied. All of these can be classified into display methods based on the guest-host method using the electro-optical effect of nematic liquid crystals.

The following examples typically illustrate the invention. This invention is not limited only to these Examples. All percentages in this example are expressed in increments.

Example 1

25 g of 1,5-polyhydroxy-4,8-dinitro-anthraquinone are dissolved in a solution of 600 g and 48 g of concentrated sulfuric acid at 20 ° C. The solution is cooled to −15 ° C. and 18 g of n-nonylphenyl ether is added dropwise over 30 minutes.

The mixture is reacted vigorously at -15 to -10 [deg.] C. for 2 hours, and the resulting reaction mixture is poured on ice and boiled for 2 hours while stirring the liquid. The product was cooled to 30 ° C. The precipitate is isolated by filtration and washed with water.

The filter cake is dispersed in 300 ml of water and 200 ml of ethanol and 30 g of sodium hydrosulfide 70% solution is added. The mixture is refluxed and stirred for 4 hours to reduce. After a large amount of ethanol is filtered off, the precipitates are separated by filtration and washed with water.

The filter cake is dispersed in 50 ml of 10% aqueous hydrochloric acid and then boiled for 30 minutes. Filter, wash with water and dry. The dried crude dye is placed in a Soxhlet extractor and extracted with benzene. The extract is concentrated and cooled.

The precipitate is separated by filtration, dried, and dissolved in benzene. Purification by column chromatography on a column filled with silica gel (wako Gel C-300, trade name from Wako).

The eluate containing the main product is concentrated and cooled to give 2 g of dark blue microcrystals. This product was identified with Dye No. 4 in Table 1 having the following elemental analysis.

Found: C 71.2%, H 6.2%, N 5.4%

Theoretic: C 71.3%, H 6.6%, N 5.7%

Example 2

The reaction was carried out in the same manner as in Example 1 using 16 g of n-octylphenyl ether instead of n-nonylphenyl ether. The crude product is recrystallized from benzene to give dark purple crystals corresponding to the dye number 6 in Table 1. This product is a blue dye having a maximum absorption at wavelengths of 587 μm and 627 μm in toluene solution.

Example 3

The reaction of Example 1 was carried out using 15 g of (4-heptyl) phenyl ether instead of n-nonylphenyl ether. The crude product is dissolved in benzene and passed through a column packed with silica gel powder. The resulting blue solution is evaporated to dryness to obtain a dark blue powder corresponding to dye number 11 in Table 1. This product is a blue dye with maximum absorption at wavelengths 587 mμ and 627 mμ in toluene solution.

Example 4

16 g of boric acid and 50 g of alizarin spirol B are added to 500 g of 95% sulfuric acid, and the mixture is stirred at 50 ° C. for 2 hours. Next, 13 g of phenitol is added at 10 ° C., and the mixture is stirred for 2 hours.

500 ml of water are then added, and the mixture is stirred at 90 ° C for 2 hours.

The precipitate is filtered off and the filter cake is dispersed in 1 liter of water. Caustic soda 45% solution is added dropwise to make alkaline. 20 g of sodium hydrosulfite are added at 80 ° C and reacted for 1 hour. The reaction product is cooled, filtered, washed with water and dried to give 35 g of crude product corresponding to dye number 13 in Table 1.

Recrystallization with ethanol yields dark blue crystals, which are dyes with a maximum absorption at 627 mμ in toluene.

Example 5

16 g of boric acid and 50 g of alizarin spirol B are added to 95% and the mixture is stirred at 50 ° C. for 2 hours.

To this was added 13 g of phenitol at 10 ° C. and stirred for 2 hours. 500 ml of water are added and the mixture is stirred at 90 ° C. for 2 hours.

After filtering out the precipitate, the filter cake was dispersed in 1 L of water, then 250 g of 45% caustic soda water solution was added and the mixture was heated to 98 ° C. Quickly add 105 g of sodium hydrosulfite having a purity of 86% and react for 30 minutes at 104 ° C. After cooling the reaction mixture to 50 ° C., salt is added. After filtering out the precipitate, the filter cake is washed with 2% saline. After filtration, the filter cake was placed in 500 ml of 10% sulfuric acid, stirred at room temperature for 1 hour, filtered, washed with water, and dried under reduced pressure at 50 ° C. to obtain 28 g of a white derivative. Oxidation of this product with hydrogen peroxide in a conventional manner affords 27 g of crude product. The crude product was purified by column chromatography on a chloroform / silica gel system to give dark purple crystals corresponding to dye number 22.

This product is a red dye with a melting point of 249-251 ° C. and a maximum absorption at 538 μm in chloroform solution.

Example 6

In the display device of the type shown in FIGS. 1 and 2, the surfaces of the transparent electrodes 5 and 6 are coated with silicon KF-99 (a brand name of a silicon compound of Shin-Etsu Chemical Co., Ltd.). 0.1 part (weight) of the dye of the dye No. 4 prepared in Example 1 for layer 1 of the label member; 4-cyano-4'-n-pentylbiphenyl 38%, 4-cyano-4'-n-pentoxybiphenyl 8%, 4-cyano-4'-n-heptylbiphenyl 23%, 4- Cyano-4'-heptoxybiphenyl 8%, 4-cyano-4'-n-octoxybiphenyl 10%, 4-cyano-4'-n-pentylterpenphenyl 10% and 4-cyano with optical activity Filled with colored liquid crystals consisting of 9.9 parts (weight) of a liquid crystal mixture consisting of 3% of no-4'-isopentylbiphenyl.

A 10 μm thick plastic film is used as spacer 4.

When the switch 11 is opened, the display device is colored blue. When the switch 11 is closed and an alternating voltage of 32 cycles and 10 volts is applied, the transparent electrodes 5 and 6 facing each other lose their color.

Open switch 11 and the blue color will reappear. When the display device is placed in the light path of the spectroport meter, the maximum absorption wavelength is 641 mμ. When the switch 11 is opened and closed at this wavelength, the absorption ratio is 1:11, which shows excellent dichroism.

Even if the display device is exposed to a wavelength of visible light of 400 mμ or more for a long time, there is no change in color and absorption boiling, and it has the same characteristics as in the manufacture immediately.

Example 7

In the display of the type shown in Figs. 1 and 2, the surfaces of the transparent electrodes 5 and 6 are coated with Silicon KF-99. Layer 1 of this display element was subjected to 0.1 part (weight) of dye No. 15, 38% of 4-cyano-4'-n-pentylbiphenyl, and 8% of 4-cyano-4'-n-pentoxybiphenyl , 4-cyano-4'-n-heptylbiphenyl 23%, 4-cyano-4'-heptoxybiphenyl 8%, 4-cyano-4'-n-octoxybiphenyl 10%, 4-cya Filled with a colored liquid crystal solution of 9.9 parts (weight) of a liquid crystal mixture consisting of 1% of no-4'-n-pentylterpenbiphenyl and 3% of optically active 4-cyano-4'-isopentylbiphenyl.

A 10 μm thick plastic film is used as spacer 4.

When the switch 11 is opened, the display device develops a bright blue color. When the switch 11 is closed and AC 20 volts of frequency 60 is applied, portions of the transparent electrodes 5 and 6 facing each other of the device become almost colorless.

Open switch 11 and the blue color will reappear. When the display device is placed in the light path of the spectrophotometer, the maximum absorption wavelength is 640 mμ. When the switch 11 is opened at this wavelength, the absorption ratio is 1: 7 which shows excellent dichroism.

Even if the display device is irradiated with visible light having a wavelength of 400 mμ or more for a long time, there is no change in color, absorption ratio, etc., and it retains the characteristics of production immediately.

Example 8

In the display device of the type shown in FIGS. 1 and 2, the surface of the transparent electrode is coated with silicon KF-99. Layer 1 of this display element was subjected to 0.1 part (weight) of dye No. 29, 38% of 4-cyano-4'-n-pentylbiphenyl, and 8% of 4-cyano-4'-n-pentoxybiphenyl , 4-cyano-4'-n-heptylbiphenyl 23%, 4-cyano-4'-heptoxybiphenyl 8%, 4-cyano-4'-n-octoxybiphenyl 10%, 4-cya Filled with a colored liquid crystal solution consisting of 9.9 parts (weight) of a liquid crystal mixture consisting of 10% of no-4'-n-pentylterphenyl and 3% of optically active 4-cyano-4'-isopentylbiphenyl. A 10 μm thick plastic film is used as spacer 4.

When the switch 11 is opened, the display is colored in red, and when the switch 11 is closed and an alternating voltage of 20 volts at 60 is applied, the portions of the transparent electrodes 5 and 6 facing each other are almost lost.

Open switch 11 and it will red again. When the above table values are placed in the light path of the spectrophotometer, the maximum absorption wavelength is 544 mμ. When the switch 11 is opened at this wavelength, the absorption ratio is 1: 7 which shows excellent dichroism.

Even if the display element is irradiated with visible light having a wavelength of 400 mμ or more for a long time, there is no color, no absorption boiling, and it has the characteristics of production immediately.

Example 9

In the same manner as in Example 8, a dye of dye number 16 instead of a dye of dye number 29 was used to manufacture a display device.

This display device has a maximum absorption at a wavelength of 640 mμ, and an absorption ratio is 1: 8.

Claims (1)

At least one anthraquinone type dichroic dye having the following structural formula contains 0.01-20% by weight based on the liquid crystal material.

Wherein X and X 'are the same and represent a -NH ₂ or -OH group, R is a straight or branched chain alkyl group, cycloalkyl group or -R ₂ -OR ₃ group having 1-15 carbon atoms, wherein R ₂ is carbon number 1-3 is an alkylene group, R ₃ is a linear or branched alkyl group having 1 to 15 carbon atoms.

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