JPH05140131A - Cyclic sulfone-based liquid crystalline compound, liquid crystal composition and liquid crystal display device - Google Patents

Abstract

PURPOSE:To obtain a new ferroelectric liquid crystalline compound, excellent in thermal stability, having great spontaneous polarization and most suitable for producing a liquid crystal device having a high speed of response and having an optically active group and cyclic sulfone group. CONSTITUTION:A ferroelectric liquid crystalline compound having an optically active group such as an alkyl, an alkyloxy or an alkyl halide and a cyclic sulfone group such as dioxothiazolidione ring, e.g. a compound expressed by formula I or II. Furthermore, a new ferroelectric liquid crystal composition 7 containing at least one of this ferroelectric liquid crystalline compound is used in a liquid crystal display device having, e.g. polarizing plates 1, substrates 2, transparent electrode films 3, oriented films 4, a sealing material 5 and spacers 6. This ferroelectric liquid crystal has an ultrahigh speed of response due to spontaneous polarization and further is capable of developing a bistable state with memory properties. Visibility angle characteristics are excellent and the ferroelectric liquid crystal is suitable as a high-capacity and large-screen display.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention uses a novel liquid crystal compound, a ferroelectric liquid crystal composition containing at least one kind of the liquid crystal compound, and the ferroelectric liquid crystal composition. The present invention relates to a liquid crystal display device.

[0002]

2. Description of the Related Art Although liquid crystals are widely used as display materials, most of such display elements use TN (Twisted Nema) which uses liquid crystal materials belonging to a nematic phase.
tic) type display method. Since this TN type display system is a light receiving type, it has excellent features such as eyestrain and extremely low power consumption, but it has a slow response speed.
The contrast cannot be obtained depending on the viewing angle, and in order to create a high-definition display element on a large screen, a TFT (Thin
There are drawbacks such as the need to add an active element such as a film transistor. Recently, high-speed responsiveness has been demanded for display devices, and attempts have been made to improve liquid crystal materials in order to meet such demands. However, compared with other light emitting displays (CRT, EL, plasma displays, etc.), the response speed was not sufficient and high-definition display was not possible. A new liquid crystal display system that takes advantage of the characteristics of liquid crystal such as light receiving type and low power consumption, and that replaces the TN type display system that utilizes a nematic phase in order to secure a response speed and high definition comparable to a light emitting display has been proposed. Among them, as one expected to have the above-mentioned excellent characteristics, a display method utilizing the optical switching phenomenon of a ferroelectric liquid crystal (NA.
Clark, S.M. T. Lagerwall, Appl.
Phys. Lett. , 36 , 899 (1980)). Ferroelectric liquid crystal is R. B. Its existence was announced by Meyer et al. (RB Meyer, L. et al.
Libert, L .; Strzelekki, P .; Kil
Ler, J .; de Phys. , 36 , L69 (197
5)), because of the structure of the liquid crystal, a chiral smectic C phase,
Alternatively, it belongs to the chiral smectic H phase. After that, the chiral smectic I phase, the chiral smectic F phase, the chiral smectic G phase, the chiral smectic J phase, and the chiral smectic K phase were further revealed as liquid crystal phases exhibiting ferroelectricity.

Since this ferroelectric liquid crystal has spontaneous polarization, it has a very fast response speed and can exhibit a bistable state with a memory property. Further, it has excellent viewing angle characteristics. Suitable as a large-capacity, large-screen display.

[0004]

However, these ferroelectric liquid crystals have not yet realized a sufficient response speed for displaying a high-definition large screen with a large number of scanning lines at such a high speed that flicker cannot be seen. .. The present invention solves the above drawbacks and provides a novel ferroelectric liquid crystal compound having a high response speed.

[0005]

The response time of a ferroelectric liquid crystal is expressed by the following equation. τ = η / (P _s E). Where τ is the response time, η is the viscosity of the liquid crystal, P _s is the spontaneous polarization of the liquid crystal, E
Represents the strength of the electric field. Therefore, in order to decrease the response time, there are three methods of decreasing the viscosity, increasing the spontaneous polarization, and increasing the electric field strength.
Since the viscosity is a smectic phase, it is difficult to lower the viscosity, and the strength of the electric field is limited by the withstand voltage characteristics of the driver used. Therefore, increasing the spontaneous polarization of the liquid crystal is the best way to reduce the response time.

The ferroelectric liquid crystal compound of the present invention uses a cyclic sulfone group as a polarizing group. Although an ester group is often used as a polarizing group of a conventional ferroelectric liquid crystal compound, a sulfonic group is more stable to heat and hydrolysis than an ester group, and thus the ferroelectric liquid crystal compound of the present invention is more stable. It has excellent thermal stability. In view of the above background, the present invention provides a novel ferroelectric liquid crystal compound and a ferroelectric liquid crystal composition having a large spontaneous polarization and a liquid crystal display device having a high response speed.

That is, the present invention provides a ferroelectric liquid crystal compound having an optically active group and a cyclic sulfone group, and at least one ferroelectric liquid crystal compound having an optically active group and a cyclic sulfone group. The present invention relates to a contained ferroelectric liquid crystal composition and a liquid crystal display device using the composition. The ferroelectric liquid crystal compound of the present invention is a compound which exhibits a ferroelectric phase such as a chiral smectic C phase and has spontaneous polarization by being mixed alone or in a compound or composition showing a smectic phase or a nematic phase. Is.

The ferroelectric liquid crystal composition of the present invention is obtained by adding the compound having an optically active group and a cyclic sulfone group of the present invention to a compound or composition showing a liquid crystal phase such as a nematic phase or a smectic phase. The obtained composition exhibits a ferroelectric phase such as a chiral smectic C phase. Examples of the composition exhibiting a nematic phase or a smectic phase include a phenylpyrimidine liquid crystal composition, a cyanocyclohexane liquid crystal composition, a benzoate ester liquid crystal composition, and a biphenyl liquid crystal composition.

In the ferroelectric liquid crystal compound of the present invention,
The optically active group is essential for developing a chiral smectic phase, and the cyclic sulfone group has a large dipole moment and is suitable for expressing a large spontaneous polarization. In the ferroelectric liquid crystal compound of the present invention, it is sufficient that at least one optically active group and at least one cyclic sulfone group are present in the same molecule, but a plurality of optically active groups or cyclic sulfone groups or both are present in the same molecule. You may.

The compound having an optically active group and a cyclic sulfone group in the ferroelectric liquid crystal composition of the present invention is preferably 0.1 to 50 parts by weight, more preferably 1 to 20 parts by weight. Further, the liquid crystal compound of the present invention contained in the ferroelectric liquid crystal composition may be one kind or plural kinds. The method for synthesizing the cyclic sulfone group in the present invention is not particularly limited, but oxidation of sulfide or sulfoxide with an oxidizing agent such as hydrogen peroxide or organic peracid, and alkylation of sulfinate or sulfonyl chloride. Law, etc.

The optically active group and cyclic sulfone group of the present invention are
Although they are present in the same compound and their positional relationship is not specified, it is more preferable that they are present in close proximity to increase spontaneous polarization. Further, the ring size of the cyclic sulfone group is preferably a 3-membered ring to a 10-membered ring, more preferably a 4-membered ring to a 6-membered ring, from the viewpoint of spontaneous polarization. Also,
The atoms constituting the cyclic sulfone group are mainly carbon atoms, but may include hetero atoms such as nitrogen atom, oxygen atom, sulfur atom and phosphorus atom. In particular, the dioxothiazolidine ring, which is a 5-membered ring derived from cysteine or thioproline (thiazolidine-4-carboxylic acid), has spontaneous polarization due to the presence of an optically active group and a cyclic sulfone group on the same ring. Is higher and more preferable.

The optically active group of the present invention may be any of those conventionally used in ferroelectric liquid crystal compounds, and examples thereof include the following groups. Alkyl group, alkyloxy group, alkanoyloxy group, alkyloxycarbonyloxy group, halogen-substituted alkyl group, halogen-substituted alkyloxy group, halogen-substituted alkanoyloxy group, halogen-substituted alkyloxycarbonyloxy group, cyano-substituted alkyl group, cyano-substituted alkyl Oxy group, cyano-substituted alkanoyloxy group, cyano-substituted alkyloxycarbonyloxy group,
Alkyloxyalkyl group, alkanoyloxyalkyl group, alkanoyloxyalkyloxy group, alkyloxyalkanoyloxy group, alkyloxycarbonyl group, alkyloxyalkyloxycarbonyl group, halogen-substituted alkyloxyalkyl group, halogen-substituted alkanoyloxyalkyl group, halogen-substituted Alkanoyloxyalkyloxy group, halogen-substituted alkyloxyalkanoyloxy group, halogen-substituted alkyloxycarbonyl group, halogen-substituted alkyloxyalkyloxycarbonyl group, cyano-substituted alkyloxyalkyl group, cyano-substituted alkanoyloxyalkyl group, cyano-substituted alkanoyloxyalkyloxy group Group, cyano-substituted alkyloxyalkanoyloxy group, cyano-substituted alkyloxycarbo Group, cyano-substituted alkyloxy alkyloxycarbonyl group.

The structure other than the optically active group and the cyclic sulfone group in the liquid crystal compound of the present invention is not particularly limited, but it is mainly composed of a skeleton part composed of a cyclic group or a bonding group and an end part composed of a long chain group. ing. As the cyclic group, a phenyl group, a biphenyl group, a terphenyl group, a naphthyl group,
Pyridine group, phenylpyridine group, pyrimidine group, phenylpyrimidine group, pyrazine group, phenylpyrazine group,
Examples thereof include a cyclohexane group, a phenylcyclohexane group, a dioxane group, a phenyldioxane group, an adamantane group, and a phenyladamantane group. Examples of the bonding group include a methylene group, a ketone group, a vinyl group, an acetylene group, an ester group, an ether group, a thioester group, a diazo group and an aminomethylene group. The terminal portion, propyl group, pentyl group, octyl group, decyl group, hexadecyl group, octadecyl group, eicosyl group,
Allyl group, propyloxy group, pentyloxy group, octyloxy group, decyloxy group, hexadecyloxy group, octadecyloxy group, eicosyloxy group, allyloxy group, propylthioxy group, pentylthioxy group, octylthioxy group, Decyltioxy group, hexadecyltioxy group, octadecyltioxy group, eicosyltioxy group, allylthiooxy group, 1,1,1,2,2,2
3,3-heptafluorobutyloxy group, 1,1,1,
2,2,3,3,4,4,5,5-dodecafluorohexyloxy group, and the like. Although depending on the size of the skeleton, the terminal portion preferably has 3 to 20 carbon atoms.

Specific examples of the ferroelectric liquid crystal compound of the present invention are shown below.

[0015]

[Chemical 1]

[0016]

[Chemical 2]

The liquid crystal display device of the present invention will be described below. The structure of the liquid crystal display device of the present invention will be described with reference to FIG. 1 which is an embodiment, but the present invention is not limited to this. In FIG. 1, 1 is a polarizing plate, 2 is a substrate, 3 is a transparent electrode film, 4 is an alignment film, 5 is a sealing material, 6 is a spacer, and 7 is a ferroelectric liquid crystal composition.

As the polarizing plate 1, a film in which a polymer material mainly contains a dichroic material such as iodine or a dye is used. Glass is mainly used as the substrate 2, but plastics such as polyethylene terephthalate, polybutylene terephthalate, polyether sulfone, polycarbonate, and cellulose acetate can also be used. On the substrate 2, tin oxide, indium oxide, and ITO (Indium Ti) are formed by known means such as vapor deposition, sputtering, and CVD.
A transparent electrode film 3 such as n oxide) is provided. The alignment film 4 is made of a polymer material such as polyimide, polyamide, or polyvinyl alcohol, an organic material such as organic silane or organic titanium, or an inorganic material such as silicon oxide.
It is obtained by forming a film on the above. Examples of the film forming method include a spin coating method, a bar coating method, a roll coating method, a dipping method, a vapor deposition method and a sputtering method. A polymer material such as an epoxy resin can be mainly used as the sealing material 5, and the ferroelectric liquid crystal composition 7 is used in the liquid crystal display device.
Is for sealing. The spacer 6 is mainly made of spherical or rod-shaped glass or plastic,
This is for keeping the distance between the substrates constant.

When the rubbing method is used to impart the liquid crystal orientation to the orientation film 4, the rubbing may be performed on at least one of the two substrates. When both substrates are rubbed, the rubbing directions may be either parallel or antiparallel to each other in principle. The liquid crystal display device of the present invention can be used for a display, a spatial light modulator, a head for an optical printer, an optical shutter, an optical switch and the like.

[0020]

EXAMPLES Next, the present invention will be described in more detail by way of examples.

[0021]

Example 1 (Synthesis of Ferroelectric Liquid Crystalline Compound (1)) Thionyl chloride (52 mL) was gradually added dropwise to 200 mL of ice-cooled methyl alcohol. After adding 26.6 g of L-thiazolidine-4-carboxylic acid to this solution, the mixture was stirred at room temperature for 10 hours. The mixture was concentrated under reduced pressure, ether was added to the residue for crystallization, and 20 g of L-thiazolidine-4-carboxylic acid methyl ester was obtained.

To 50 mL of a toluene solution containing 2.06 g of the obtained ester, 50 mL of a toluene solution containing 3.75 g of 4-octyloxybenzoyl chloride was slowly added dropwise with stirring, and then about 2 g of triethylamine was added to the solution at room temperature for 1 hour. It was agitated. The reaction solution was washed with diluted hydrochloric acid, dried, and distilled off with toluene to obtain 5.1 g of amide. 50 mL of a methylene chloride solution containing 4.93 g of the obtained amide and 6.90 g of m-chloroperbenzoic acid was stirred at room temperature for 10 hours. The reaction solution was treated with an aqueous solution of sodium sulfite, washed with an aqueous solution of sodium bicarbonate, dried and the solvent was distilled off to obtain 5 g of the liquid crystalline compound (1).

[0023]

Example 2 (Synthesis of Ferroelectric Liquid Crystalline Compound (2)) Synthesis was performed in the same manner as in Example 1 except that n-butyl alcohol was used instead of methyl alcohol in Example 1.

[0024]

Example 3 (Synthesis of Ferroelectric Liquid Crystalline Compound (3))
Synthesis was performed in the same manner as in Example 1 except that 4- (4-octyloxyphenyl) benzoyl chloride was used instead of octyloxybenzoyl chloride.

[0025]

Example 4 (Synthesis of Ferroelectric Liquid Crystalline Compound (4)) The methyl alcohol of Example 1 was changed to n-butyl alcohol, and 4-octyloxybenzoyl chloride was changed to 4- (4-octyloxyphenyl) benzoyl chloride. Synthesis was performed in the same manner as in Example 1 except that

[0026]

Example 5 (Synthesis of Ferroelectric Liquid Crystalline Compound (5)) Thionyl chloride (52 mL) was gradually added dropwise to 200 mL of ice-cooled methyl alcohol. After adding 26.6 g of L-thiazolidine-4-carboxylic acid to this solution, the mixture was stirred at room temperature for 10 hours. The mixture was concentrated under reduced pressure, ether was added to the residue for crystallization, and 20 g of L-thiazolidine-4-carboxylic acid methyl ester was obtained.

To 100 mL of a chloroform solution of 14.7 g of the obtained ester, 16.2 g of octanoyl chloride was added.
50 mL of the chloroform solution of 1 was gradually added dropwise with stirring, about 20 g of triethylamine was added, and the mixture was stirred at room temperature for 1 hour. The reaction solution was washed with diluted hydrochloric acid, dried, and distilled off with chloroform to obtain 25 g of amide. To 500 mL of a methanol solution containing 13.7 g of the obtained amide, 1.1 equivalent of a 1 M sodium hydroxide solution was added, and the mixture was stirred at room temperature for 1 hour. Methanol was distilled off under reduced pressure, water and ether were added to extract unreacted amide. The aqueous layer was adjusted to pH 3 with 2% hydrochloric acid and extracted with ethyl acetate. Wash the organic layer with water,
After drying and concentration under reduced pressure, 10 g of carboxylic acid was obtained.

To a solution of the obtained carboxylic acid (2.59 g), 4-octyloxyphenol (2.22 g) and dimethylaminopyridine (0.12 g) in methylene chloride (50 mL) was added EDC hydrochloride (2.11 g) under ice cooling, and the mixture was allowed to stand at room temperature for 15 hours. It was agitated. The reaction mixture was concentrated under reduced pressure, water was added, and the mixture was extracted with ethyl acetate. The extract was washed with aqueous sodium hydrogen carbonate and water, dried, concentrated under reduced pressure, purified by chromatography, and ester 4.
7 g was obtained.

Methylene chloride solution 1 consisting of 4.64 g of the obtained ester and 3.80 g of m-chloroperbenzoic acid
50 mL was stirred at room temperature for 10 hours. The reaction solution was treated with an aqueous sodium sulfite solution, washed with an aqueous sodium hydrogen carbonate solution, dried and the solvent was distilled off to obtain 4.5 g of the liquid crystalline compound (5).

[0030]

Example 6 (Manufacturing Method of Liquid Crystal Display Device and Response Time Measurement) A glass substrate with a transparent electrode film (ITO) was spin-coated with a polyimide diluting solution on the electrode film of the substrate and then heated to a thickness of about 500.
A polyimide thin film of A was formed. The polyimide thin film formed on the glass substrate was rubbed in one direction with a flocked cloth. This pair of glass substrates is used as a spacer 2
Using silica particles having a size of μm, the particles were stacked so that the upper and lower rubbing directions were parallel to each other, and the periphery thereof was sealed except for a portion serving as an injection port.

Next, 10% by weight of the ferroelectric liquid crystal compound (1) and the phenylpyrimidine liquid crystal composition ZLI-32 are used.
A ferroelectric liquid crystal composition consisting of 90% by weight of 34B (manufactured by E. Merck) was heated to 120 ° C. to obtain an isotropic phase, which was injected into the cell prepared above from an injection port. This cell is 1.5
It was gradually cooled from 120 ° C. to 30 ° C. over time. By observing with a polarization microscope, it was confirmed that the ferroelectric liquid crystal in the cell was uniformly horizontally aligned. A polarizing plate was attached to this cell in a crossed Nicols manner to form a liquid crystal display device. The structure of the liquid crystal display device at this time is shown in FIG.

A voltage of ± 10 V is applied to the transparent electrode film of the liquid crystal display device.
A rectangular wave of / μm was applied, and the time required for the transmittance to change from 0% to 90% was determined as the response time. The response time at this time was 3.5 milliseconds.

[0033]

Examples 7 to 10 The response time was measured in the same manner as in Example 6 except that the ferroelectric liquid crystal compound was changed from (2) to (5) and the content was changed to the amount shown in Table 1. The results are shown in Table 1 together with Example 6.

[0034]

[Table 1]

[0035]

According to the present invention, it is possible to provide a ferroelectric liquid crystal compound having a large spontaneous polarization, a ferroelectric liquid crystal composition, and a liquid crystal display device having a high response speed.

[Brief description of drawings]

FIG. 1 is a sectional view showing an example of a liquid crystal display device using a ferroelectric liquid crystal composition of the present invention.

[Explanation of symbols] 1 polarizing plate 2 substrate 3 transparent electrode film 4 alignment film 5 sealant 6 spacer 7 ferroelectric liquid crystal composition

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location C09K 19/34 6742-4H G02F 1/13 505

Claims (3)

[Claims] 1. A ferroelectric liquid crystal compound having an optically active group and a cyclic sulfone group. 2. A ferroelectric liquid crystal composition containing at least one ferroelectric liquid crystal compound having an optically active group and a cyclic sulfone group. 3. A liquid crystal display device, wherein the liquid crystal is the ferroelectric liquid crystal composition according to claim 2.