JPH1046149A - Preparation of liquid crystal composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prepare a liquid crystal composition showing good switching characteristics in a uniform state and being capable of high-contrast display by mixing a compound purified with active carbon with other components. SOLUTION: A liquid crystal composition containing a plurality of components is prepared by the process which comprises the step of purifying at least one of the above components with 10-50wt.%, based on the component, active carbon and the step of mixing the purified component with the other components. In this process, it is desirable to purify the component with 20-35wt.%, based on the component, active carbon. It is desirable that the purification step comprises alumina column chromatography or/and silica gel column chromatography. It is also desirable that the component purified with at least active carbon is a liquid crystal component which itself shows a smectic phase, and that the liquid crystal composition is one having a chiral smectic phase.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for preparing a liquid crystal composition containing a compound subjected to a purification step of activated carbon treatment, and more particularly to a method of preparing a liquid crystal composition containing a compound subjected to a purification step of activated carbon treatment. The present invention relates to a method for preparing a ferroelectric liquid crystal composition having improved molecular alignment.

[0002]

2. Description of the Related Art Conventionally, the use of a liquid crystal device having bistability has been proposed by Clark and Lagawell.
rwall) (JP-A-56-10).
No. 7216, U.S. Pat. No. 4,367,924). As the bistable liquid crystal, a ferroelectric liquid crystal having a chiral smectic C phase (SmC ^* phase) or an H phase (SmH ^* phase) is generally used.

This ferroelectric liquid crystal has a bistable state consisting of a first optically stable state and a second optically stable state with respect to an electric field. For example, the first optically stable state corresponds to one electric field vector. The liquid crystal is oriented in a stable state, and the liquid crystal is oriented in a second optically stable state with respect to the other electric field vector.
In addition, this type of liquid crystal has a property (bistability) that takes one of the above two stable states in response to an applied electric field and maintains the state when no electric field is applied.

[0004] In addition to the characteristic having bistability as described above, the ferroelectric liquid crystal has an excellent characteristic of high-speed response. This is because the spontaneous polarization of the ferroelectric liquid crystal and the applied electric field act directly to induce a transition of the alignment state.
It is 3 to 4 orders of magnitude faster than the response speed due to the effects of dielectric anisotropy and electric field.

In general, in the case of a liquid crystal element utilizing birefringence of liquid crystal, the transmittance under crossed Nicols is

[0006]

(Equation 1) (Where I ₀ is the incident light intensity, I is the transmitted light intensity, θ _a is the apparent tilt angle defined below, Δn is the refractive index anisotropy, d is the thickness of the liquid crystal layer, and λ is the incident light. .).

[0007] tilt theta _a apparent in the above-mentioned non-helical structure would first and appears as a angle between the average molecular axis directions of liquid crystal molecules in a twisted alignment in a second orientation state. According to the above equation, the tilt angle theta _a such apparent 2
2.5 the maximum of the transmittance when ° angle, it is desirable tilt angle theta _a in a non-helical structure for realizing bistability close as possible to 22.5 °.

However, the alignment method used up to now, particularly the alignment method using a rubbed polyimide film, is applied to the above-mentioned non-helical ferroelectric liquid crystal having a bistable structure disclosed by Clark and Ragawall. When applied, it has the following problems.

That is, the apparent tilt angle θ _a (1/2 of the angle between the molecular axes of the two stable states) in a non-helical ferroelectric liquid crystal obtained by orientation by a conventional rubbed polyimide film. ) Is significantly smaller than the cone angle of the ferroelectric liquid crystal (the half angle of the apex angle of the triangular pyramid shown in FIG. 3). In particular, the apparent tilt angle θ _{a of} a non-helical ferroelectric liquid crystal obtained by orientation by a conventional rubbed polyimide film.
Was generally about 3 ° to 8 °, and the transmittance at that time was at most about 3 to 5%.

The smectic liquid crystal generally has a layer structure, but when the SmA phase transitions to the SmC phase or the SmC ^* phase, the layer interval is reduced, so that the liquid crystal layer denoted by 21 is bent at the center of the upper and lower substrates as shown in FIG. (Chevron structure). As shown in the figure, the direction of bending is in the orientation state (C1 orientation state) portion 22 that appears immediately after the transition from the high-temperature phase to the SmC ^* phase, and in the orientation state that appears in the C1 orientation state when the temperature is further lowered. There are two cases in the case of the portion (C2 alignment state) 23.

Then, when a combination of a specific alignment film having a high pretilt and a liquid crystal is used, the above-mentioned C1 → C2 transition is unlikely to occur, and no C2 alignment state is generated in the liquid crystal material. In addition to the two low-contrast stable states in which the director of the liquid crystal has been twisted between the upper and lower substrates (hereinafter referred to as a splay state), another two high-contrast stable states (hereinafter referred to as a splay state) have been proposed. (Referred to as the uniform state).

These states transition with each other when an electric field is applied. When a weak positive / negative pulse electric field is applied, a transition between the spray 2 states occurs, and when a strong positive / negative pulse electric field is applied, a transition between the uniform 2 states occurs.

When the uniform 2 state is used, a display element which is brighter than the conventional one and has a high contrast can be realized. Therefore, the entire screen is unified to the C1 orientation state as a display element,
In addition, if two high-contrast states in the CI alignment are used as two states for black-and-white display, it is expected that a display with higher quality than before can be realized.

As described above, without generating the C2 orientation state,
In order to realize one orientation state, it is necessary to satisfy the following conditions. That is, as shown in FIG. 3, the directors near the substrate in the C1 orientation and the C2 orientation are respectively shown in FIG.
It is on the cone 31 of (a) and (b). As is well known, rubbing causes the liquid crystal molecules at the interface of the substrate to be inclined relative to the substrate by an angle α (pre-tilt) (the substrate 2 shown in FIG. 3).
0 and an angle formed by the liquid crystal molecules 33), and the direction is a direction in which the liquid crystal molecules lean their heads toward the rubbing direction (the A direction in FIGS. 2 and 3). . From the above, between the cone angle Θ, the pretilt angle α, and the layer tilt angle δ (the angle between the substrate normal 32 and the liquid crystal molecular layer 21 in FIG. 3),

[0015]

## EQU2 ## The relationship of Ｃ + δ> α for the C1 orientation and the relationship of Θ−δ> α for the C2 orientation must be satisfied.

Therefore, the conditions for generating the C1 orientation without generating the C2 orientation are as follows:

[0017]

３−δ <α, that is, Θ <+ δ (I).

Furthermore, from a simple consideration of the torque that is applied to switching at the interface molecules from one position to the other position by an electric field, the conditions under which the switching of interface molecules is likely to occur are as follows.

[0019]

Α> δ (II) is obtained. Therefore, in order to form the C1 orientation state more stably, it is effective to satisfy the relationship of the formula (II) in addition to the relationship of the formula (I).

[0020] (I) and formula (II) conditions result of further advanced experiments under the, the tilt angle theta _a liquid crystal apparent conventional liquid crystal elements which do not satisfy the (I) and formula (II) conditions From about 3 ° to 8 ° in the case, to about 8 ° to 16 ° in the case of the present invention which satisfies the conditions of formulas (I) and (II).

[0021]

It has been empirically obtained that the relational expression of Θ> θ _a > Θ / 2 (III) holds.

As described above, (I), (II) and (I)
It has been found that a display capable of displaying a high-contrast image can be realized if the condition of the formula II) is satisfied (Japanese Patent Laid-Open No. 3-252624).

Further, in order to destabilize and reduce the splay state in the above-mentioned C1 orientation and stabilize the uniform state and obtain good orientation, the rubbing directions of the upper and lower substrates are set to two.
It was found that cross rubbing shifted in the range of 25 to 25 (intersection angle) was also extremely effective.

[0024]

However, there is a part where the alignment improvement only by the cross rubbing is still insufficient, and there are cases where the alignment state is still such that the spray state is stable and the switching characteristics in the uniform state are poor. Existed.

An object of the present invention is to solve the above-mentioned problems and to provide a method for preparing a liquid crystal composition having good switching characteristics in a uniform state and capable of high-contrast display.

[0026]

That is, the present invention relates to a method for preparing a liquid crystal composition containing a plurality of components, wherein at least one of the compounds is used in an amount of 10 to 50% by weight based on the compound. % Of activated carbon, and a step of mixing the purified compound with other components.

In the present invention, 2
The purification is preferably carried out using 0 to 35% by weight of activated carbon. In addition, the purification step preferably includes alumina column chromatography, silica gel column chromatography, alumina column chromatography, and silica gel column chromatography.

It is preferable that at least the compound purified by the activated carbon is a liquid crystal compound exhibiting a smectic phase alone, and the liquid crystal composition is a liquid crystal composition exhibiting a chiral smectic phase.

[0029]

BEST MODE FOR CARRYING OUT THE INVENTION The present inventors have conducted intensive studies in order to solve the above-mentioned problems, and as a result, when a liquid crystal composition containing a compound subjected to a purification step of activated carbon treatment is used, a liquid crystal composition which does not use such a compound is obtained. Compared with the uniform state is stable,
It has been found that the switching characteristics in the uniform state are improved.

The present invention is a method for preparing such a liquid crystal composition, which is a method for preparing a liquid crystal composition containing a plurality of components, wherein at least one of the compounds to be the components is
The method is characterized by comprising a step of purifying the compound using activated carbon in an amount of 10 to 50% by weight, and a step of mixing the purified compound with other components.

In the purification step of the activated carbon treatment, the compound is dissolved in a soluble solvent (eg, methanol, ethanol, acetone, toluene, benzene, hexane, chloroform, etc.), and preferably 10 to 50% by weight based on the compound. Preferably, 20 to 35% by weight of activated carbon is added to add 1 to 6
This is achieved by stirring or standing for 0 minutes and then filtering off the activated carbon. In addition, the purification process of this activated carbon treatment,
It is also possible to combine with alumina column chromatography or silica gel column chromatography.

In the method for preparing a liquid crystal composition of the present invention,
The liquid crystal composition is preferably a ferroelectric liquid crystal composition. As a compound which is a component of the ferroelectric liquid crystal composition and in which the purification step of the activated carbon treatment is effective, a compound represented by the following general formula (I) is given.

[0033]

Embedded image R ₁ -A ₁ -X ₁ -A ₂ -X ₂ -A ₃ -R ₂ (I)

In the formula, R ₁ and R ₂ are H, F, CN or a linear, branched or cyclic alkyl group having 1 to 30 carbon atoms (one or two or more of said alkyl groups) -CH ₂ -is -O-,-under the condition that no heteroatom is adjacent.
S-, -CO-, -CH (CN)-, -CH = CH-,
^{-C≡C -, - * CHF -,} - C * H (CF 3) -, -
_{^{C * H (CHF 2) -}} , - C * H (CH 2 F) - shows the can) be replaced with.

A₁, A _Two, A_ThreeIs a single bond, unsubstituted or
One or two substituents (F, Cl, Br, CH₃, CF
₃Or CN), 1,4-phenylene, pyridine
-2,5-diyl, pyrimidine-2,5-diyl, pyra
Gin-2,5-diyl, pyridazine-3,6-diyl,
1,4-cyclohexylene, 1,3-dioxane-2,
5-diyl, 1,3-dithiane-2,5-diyl, thio
Phen-2,5-diyl, thiazole-2,5-dii
, Thiadiazole-2,5-diyl, benzoxazo
-2,5-diyl, benzoxazole-2,6-
Diyl, benzothiazole-2,5-diyl, benzothi
Azole-2,6-diyl, benzofuran-2,5-di
Yl, benzofuran-2,6-diyl, quinoxaline-
2,6-diyl, quinoline-2,6-diyl, 2,6-
Naphthylene, indan-2,5-diyl, 2-alkyl
Indan-2,5-diyl (the alkyl group has 1 carbon atom)
To 18 linear or branched alkyl groups);
Dananone-2,6-diyl, 2-alkylindanone-
2,6-diyl (the alkyl group has 1 to 18 carbon atoms)
Linear or branched alkyl group), coumaran-
2,5-diyl, 2-alkylcoumaran-2,5-dii
(An alkyl group is a straight-chain having 1 to 18 carbon atoms or
A branched alkyl group). However, A
₁, A _Two, A_ThreeIs not a single bond.

X ₁ and X ₂ are a single bond, —COO—, —OCO
_{-, - CH 2 O -,} - OCH 2 -, - CH 2 CH 2 -,
-CH = CH-, -C≡C-. * Indicates optical activity.

The content of the compound subjected to the purification step of the activated carbon treatment contained in the liquid crystal composition of the present invention is usually at least 3% by weight, preferably at least 5% by weight, more preferably at least 10% by weight. is there.

As another liquid crystal compound to be combined with the compound subjected to the purification step of the activated carbon treatment contained in the liquid crystal composition of the present invention, particularly the ferroelectric liquid crystal composition, JP-A-4-272929 (23) To (XII), preferred compounds (IIIa) to (XIId), and more preferred compound (I).
IIaa) to (XIIdb). Compounds (III) to (VI), and preferred compound (IIIa)
~ (VIf), more preferred compound (IIIaa) ~
At least one of R ′ ₁ and R ′ ₂ in (VIfa) is also a compound (VII), (VIII), a preferred compound (VIIa) to (VIIIb), a more preferred compound (VIIIba) or R ′ ₃ in (VIIIbb). , at least one, and compound of R _'4 (I
X) to (XII), preferred compounds (IXa) to (XI)
Id), more preferred compounds (IXba), (XIId)
in _{b) R '5, R'} 6 of at least one of - (C
The compound of H ₂ ) _{EC G} F _{2 G + 1} (E: 0 to 10, G: 1 to 15 integer) can be used in the same manner. Furthermore,
Liquid crystalline compounds represented by the following general formulas (XIII) to (XVIII) can also be used.

[0039]

Embedded image

Here, R ′ ₇ and R ′ ₈ are a hydrogen atom or a linear or branched alkyl group having 1 to 18 carbon atoms, and directly bond to X ^′ ₆ and X ^′ ₉ in the alkyl group. -CH ₂ -
One or two or more non-adjacent —CH ₂ except groups
-Groups are -O-, -CO-, -OCO-, -COO-,-
CH (CN) -, - C (CN) (CH 3) -, may be replaced by.

Further, R ′ ₇ and R ′ ₈ are preferably the following i)
-Viii).

I) a linear alkyl group having 1 to 15 carbon atoms

[0043]

Embedded image p: 0 to 5, q: 2 to 11 Integer Optically active

[0044]

Embedded image r: 0 to 6, s: 0 or 1, t: 1 to 14 integer Optically active

[0045]

Embedded image w: 1 to 15 integers may be optically active

[0046]

Embedded image A: 0 to 2, B: 1 to 15 Integer Optically active

[0047]

Embedded image C: 0 to 2, D: 1 to 15 Integer Optically active

[0048]

Embedded image _{vii) - (CH 2) E} C G F 2G + 1 E: 0~10, G: 1~15 integer

[0049]

Viii) —H N, Q, R, T: 0 or 1 Y ′ ₇ , Y ′ ₈ ,
Y _'9: H or _{F A' 4: Ph, Np} X '6, X' 9: a single bond, -COO -, - OCO -, - O- X '7, X' 8: single bond, -COO- , -OCO-, -C
_{H 2 O -, - OCH 2} -

As a preferred compound of (XIII), (XIII)
IIIa).

[0051]

Embedded image R ′ ₇ -X ^′ _6- [Py2]-[Ph] -OCO- [Tn] -R ′ ₈ (XI IIa)

As a preferred compound of (XVI), (XV
Ia) and (XVIb).

[0053]

Embedded image _{R '7 - [Tz1] -} [Ph] -X' 9 -R '8 (XVI a) R' 7 - [PhY '7] - [Tz1] - [PhY' 8] -X '9 -R _'8 (XVIb)

As a preferred compound of (XVII), (X
VIIa) and (XVIIb).

[0055]

Embedded image _{R '7 - [Boa2] -} [Ph] -O-R' 8 (XVIIa) R '7 - [Boa2] - [Np] -O-R' 8 (XVIIb)

Preferred compounds of (XVIII) include (XVIIIa) to (XVIIIc).

[0057]

Embedded image _{R '7 - [Btb2] -} [Ph] -R' 8 (XVIIIa) R '7 - [Btb2] - [Ph] -O-R' 8 (XVIIIb) R '7 - [Btb2] - _{[Np] -O-R '8} (XVIIIc)

Preferred compounds of (XVIa) and (XVIb) include (XVIaa) to (XVIbc).

[0059]

Embedded image _{R '7 - [Tz1] -} [Ph] -O-R' 8 (XVIaa) R '7 - [Ph] - [Tz1] - [Ph] -R' 8 (XVIba) R '7 - [Ph] - [Tz1] - [Ph] -O-R '8 (XVIbb) R' 7 - [Ph] - [Tz1] - [Ph] -OCO-R '8 (XVIbc)

Ph, Py2, Tn, Tz1, Cy, Bo
The abbreviations of a2 and Btb2 conform to the above definitions, and the other abbreviations indicate the following groups.

[0061]

Embedded image

FIG. 1 is a schematic cross-sectional view showing an example of a liquid crystal layer using a liquid crystal composition of the present invention, for example, a liquid crystal element having a chiral smectic liquid crystal layer, for explaining the structure of a liquid crystal element utilizing ferroelectricity. It is. In FIG.
Is a chiral smectic liquid crystal layer, 2 is a glass substrate, 3 is a transparent electrode, 4 is an alignment layer, 5 is a spacer, 8 is a polarizing plate,
Reference numeral 9 denotes a light source.

Each of the two glass substrates 2 is made of In ₂ O
₃ , a transparent electrode 3 made of a thin film such as SnO ₂ or ITO (Indium-Tin Oxide). A thin film of a polymer such as polyimide is rubbed with a gauze, an acetate flocking cloth, or the like, on which an alignment layer for arranging liquid crystals in the rubbing direction is formed. Examples of the insulating material forming the film include silicon nitride, hydrogen-containing silicon carbide, silicon oxide, boron nitride compound, hydrogen-containing boron nitride, cerium oxide, aluminum oxide, and the like.
An inorganic insulating layer such as zirconium oxide, titanium oxide or magnesium fluoride is formed, and polyvinyl alcohol, polyimide, polyamide imide, polyester imide, polyparaxylene, polyester, polycarbonate, polyvinyl acetal, polyvinyl chloride,
An organic insulating material such as polyvinyl acetate, polyamide, polystyrene, cellulose resin, melamine resin, urea resin, acrylic resin and photoresist resin may be used as an alignment control layer, and the alignment control layer may be formed of two layers, or an inorganic material. It may be an insulating orientation control layer or a single layer of an organic substance insulating orientation control layer. If this alignment layer is inorganic, it can be formed by vapor deposition or the like. If it is organic, a solution in which an organic substance is dissolved or a precursor solution thereof (0.1 to 20% by weight, preferably 0.2 to 10% by weight in a solvent) (% By weight) using a spinner coating method, a dip coating method, a screen printing method, a spray coating method, a roll coating method, or the like, and can be formed by curing under predetermined curing conditions (for example, under heating).

The thickness of the orientation layer is usually from 30 to 1 μm, preferably from 40 to 3000, more preferably from 40 to 3000 μm.
1000 mm is suitable.

The two glass substrates 2 are kept at an arbitrary interval by a spacer 5. For example, there is a method in which silica beads and alumina beads having a predetermined diameter are sandwiched between two glass substrates as spacers, and the periphery is sealed with a sealing material, for example, an epoxy-based adhesive. Alternatively, a polymer film or glass fiber may be used as the spacer. A liquid crystal exhibiting ferroelectricity is sealed between the two glass substrates.

The thickness of the chiral smectic liquid crystal layer 1 in which the chiral smectic liquid crystal is enclosed is generally 0.5
-20 μm, preferably 1-5 μm.

The ferroelectric liquid crystal has an SmC ^* phase (chiral smectic C phase) in a wide temperature range including room temperature (particularly at a low temperature side). A wide margin is desired.

In order to obtain a good uniform orientation and obtain a monodomain state, particularly in the case of a device, the ferroelectric liquid crystal must have an isotropic phase to a Ch phase (cholesteric phase).
It is desirable to have a phase transition series of SmA (smectic phase) -SmC ^* (chiral smectic C phase).

The transparent electrode is connected to an external power supply by, for example, a lead wire. A polarizing plate 8 is attached to the outside of the glass substrate 2. FIG. 1 is a transmission type. Further, a liquid crystal device in which the liquid crystal element includes a liquid crystal element driving circuit and a light source will be described.

By using the liquid crystal element according to the present invention in a display panel section and employing a data format of image information having scanning line address information shown in FIGS. 4 and 5 and communication synchronization means using a SYNC signal, a liquid crystal display is realized. Implement the device.

In the figure, reference numerals are as follows. Reference Signs List 101 Ferroelectric liquid crystal display device 102 Graphics controller 103 Display panel 104 Scan line drive circuit 105 Information line drive circuit 106 Decoder 107 Scan signal generation circuit 108 Shift register 109 Line memory 110 Information signal generation circuit 111 Drive control circuit 112 GCPU 113 Host CPU 114 VRAM

The generation of image information is performed by the graphics controller 102 of the main unit, and is shown in FIGS.
Are transferred to the display panel 103 according to the signal transfer means shown in FIG. The graphics controller 102
PU (Central Processing Unit, hereinafter abbreviated as GCPU112)
And VRAM (image information storage memory) 114 as a core,
It manages and communicates image information between the host CPU 113 and the liquid crystal display device 101, and this control method is mainly realized on the graphics controller 102. Note that a light source is disposed on the back surface of the display panel.

[0073]

EXAMPLES Hereinafter, the present invention will be described in more detail by way of examples, but the present invention is not limited to these examples.

Example 1 Synthesis of 2- [4- (4-fluorobenzoyloxy) phenyl] -5-dodecylpyrimidine 2.16 g (6.34 mmole) of 2- (4-hydroxyphenyl) -5-dodecylpyrimidine, 4 0.89 g (6.35 mmole) of -fluorobenzoic acid and 50 ml of dichloromethane are put into a 200 ml eggplant flask, 1.31 g (6.35 mmole) of N, N'-dicyclohexylcarbodiimide and 0.11 g of 4-dimethylaminopyridine are stirred at room temperature. Were added successively, and then stirred at room temperature for 3 hours. The precipitated N, N'-dicyclohexylurea was removed by filtration, the filtrate was dried under reduced pressure, and the residue was subjected to silica gel column chromatography (eluent: toluene / ethyl acetate:
Purified by 100/1) and recrystallized with a mixed solvent of toluene and methanol to obtain 2.31 g of colorless crystals (yield: 72.6%).
I got

Acetone was added to 1.50 g of the crystal and the mixture was dissolved under reflux, 0.45 g of activated carbon was added, and the mixture was stirred at room temperature for 5 minutes. After refluxing again, the solution was suction filtered while hot, the activated carbon was removed by filtration, the filtrate was cooled in a freezer, and the precipitated crystals were collected by filtration. Yield: 1.30 g (purification yield by activated carbon treatment: 8
6.7%)

Example 2 90 parts by weight of a liquid crystal composition A having a chiral smectic C phase, and 2- [4] synthesized in Example 1 and treated with activated carbon
-(4-Fluorobenzoyloxy) phenyl] -5-
A liquid crystal composition B was prepared by mixing 10 parts by weight of dodecyl pyrimidine.

On a glass substrate having a transparent electrode, Ti-S
A thin film of i (1/1) is formed by spin coating, and 1% N of polyamic acid LQ1802 manufactured by Hitachi Chemical Co., Ltd. is formed thereon.
The MP solution was applied with a spinner and baked at 270 ° C. for 1 hour. This substrate was rubbed and bonded to another substrate that had been subjected to the same treatment, keeping a 1.5 μm gap so that the rubbing direction was parallel, the cross direction was negative, and the cross angle was 6 °. Liquid crystal composition B was injected to prepare a liquid crystal element. After holding the liquid crystal element at 100 ° C. for 5 hours, the liquid crystal was cooled at a rate of 1 ° C. per minute and observed under a microscope at room temperature. As a result, the C1 orientation was maintained in the initial orientation state, and almost the entire surface was in a uniform state. Crest value 1
When a rectangular pulse of 5 V is applied, the pulse width is 18 μsec.
Switching between uniforms took place.

COMPARATIVE EXAMPLE 1 90 parts by weight of a liquid crystal composition A having a chiral smectic C phase and the non-activated carbon treated 2 synthesized in Example 1
-[4- (4-Fluorobenzoyloxy) phenyl]
Liquid crystal composition C was prepared by mixing 10 parts by weight of -5-dodecylpyrimidine.

A liquid crystal device was prepared in exactly the same manner as in Example 2 except that the liquid crystal composition C was injected, and the initial alignment state and switching were observed in the same manner. C in the initial alignment state
While one orientation was maintained, about 30% was in the spray state and the remaining 70% was in the uniform state. When a rectangular pulse having a peak value of 15 V was applied in the same manner as in Example 2, the switching between the uniform 2 states became difficult due to the stable spray state, and the obtained threshold value was 27 μm.
sec.

Example 3 Synthesis of 2- (4-hexyloxyphenyl) -5-nonylpyrimidine 8.00 g (35.6 mmole) of 2- (4-hydroxyphenyl) -5-nonylpyrimidine, 2.35 g of potassium hydroxide And 50 ml of n-butanol was placed in a 200 ml eggplant flask and dissolved by heating. 7.42 g (35.0 mmole) of 1-iodohexane was added, and then 5
Reflux stirring was performed for hours. The solvent was evaporated to dryness under reduced pressure, water was added to the residue, and the mixture was extracted with ethyl acetate. The organic layer was washed with a 5% aqueous sodium thiosulfate solution and then with water, dried over sodium sulfate and the solvent was evaporated under reduced pressure. The residue was purified by silica gel column chromatography (eluent: toluene / ethyl acetate: 100/1), and recrystallized with a mixed solvent of ethyl acetate-methanol to obtain 7.01 g (72.6% yield) of colorless crystals. .

5.00 g of these crystals were purified by alumina column chromatography (eluent: toluene), and ethanol was added to 4.69 g of the residue obtained by evaporating the toluene under reduced pressure, and the mixture was heated and dissolved to give 0.94 g of activated carbon. Was added and stirred at room temperature for 5 minutes. Subsequently, the mixture was refluxed, suction filtered while hot, the activated carbon was removed by filtration, the filtrate was cooled in a freezer, and the precipitated crystals were collected by filtration. 4.10 g (purification yield by alumina column chromatography and activated carbon treatment
0%)

Example 4 80 parts by weight of a liquid crystal composition D having a chiral smectic C phase and 2- (4-hexyloxyphenyl) -5-nonylpyrimidine synthesized in Example 3 and treated with activated carbon and subjected to alumina column chromatography. 20 parts by weight were mixed to prepare a liquid crystal composition E. A liquid crystal device was prepared in exactly the same manner as in Example 2 except that the liquid crystal composition E was injected, and the initial alignment state and switching were observed in the same manner. As a result, the C1 orientation was maintained in the initial orientation state, and almost the entire surface was in a uniform state. When a rectangular pulse having a peak value of 15 V was applied, switching between uniforms occurred with a pulse width of 15 μsec.

Composition of liquid crystal composition D 2- (4-hexyloxyphenyl) -5-octylpyrimidine 56 parts by weight 2- (4-nonyloxyphenyl) -5-octylpyrimidine 30 parts by weight 2- [4- (trans 2-propylcyclohexanecarbonyloxy) phenyl] -5-undecylpyrimidine 2 parts by weight 2- [4- (trans-4-butylcyclohexanecarbonyloxy) phenyl] -5-undecylpyrimidine 2 parts by weight 2- [ 4- (trans-4-pentylcyclohexanecarbonyloxy) phenyl] -5-undecylpyrimidine 4 parts by weight Optically active 2- [4- (2-fluorooctyloxy) phenyl] -5-dodecylpyrimidine 3 parts by weight Optical Active 2- [4- (2-fluorooctyloxy) phenyl] -5-decylpi Mi Jin 3 parts by weight

Comparative Example 2 80 parts by weight of a liquid crystal composition D having a chiral smectic C phase and 2- (4-hexyloxyphenyl) -5-nonyl which had not been treated with activated carbon and subjected to alumina column chromatography synthesized in Example 3. A liquid crystal composition F was prepared by mixing 20 parts by weight of pyrimidine.

A liquid crystal device was prepared in exactly the same manner as in Example 2 except that the liquid crystal composition F was injected, and the initial alignment state and the switch were observed in the same manner. C1 in the initial alignment state
The orientation was maintained, but about 20% was in the splay state and the remaining 80% was in the uniform state. When a rectangular pulse having a peak value of 15 V was applied in the same manner as in Example 2, switchg between the uniform 2 states hardly occurred because the spray state was stable, and the obtained threshold value was 23 μm.
sec.

Example 5 Synthesis of 2- (4-octanoyloxyphenyl) -5-decylpyrimidine 6.00 g (19.2 mmole) of 2- (4-hydroxyphenyl) -5-decylpyrimidine;
77 g (19.2 mmole), dichloromethane 150
ml into a 500 ml eggplant flask, and stirring at room temperature.
4.44 g of N, N'-dicyclohexylcarbodiimide
(21.5 mmole) and 0.14 g of 4-dimethylaminopyridine were sequentially added, followed by stirring at room temperature for 6 hours.
The precipitated N, N'-dicyclohexylurea was removed by filtration, the filtrate was dried under reduced pressure, and the residue was subjected to silica gel column chromatography (eluent: hexane / chloroform: 1/1).
And recrystallized from ethanol to give 6.86 g of colorless crystals
(81.4% yield).

Acetone was added to 3.00 g of the crystal and the mixture was dissolved under reflux, 1.05 g of activated carbon was added, and the mixture was stirred at room temperature for 5 minutes. After refluxing again, the solution was suction filtered while hot, the activated carbon was removed by filtration, the filtrate was cooled in a freezer, and the precipitated crystals were collected by filtration. 2.23 g (purification yield by activated carbon treatment: 7
4.3%)

Example 6 2- (4) liquid crystal composition G having a chiral smectic C phase and 85 parts by weight of the liquid crystal composition synthesized in Example 5 and treated with activated carbon
A liquid crystal composition H was prepared by mixing 15 parts by weight of (octanoyloxyphenyl) -5-decylpyrimidine. A liquid crystal device was prepared in exactly the same manner as in Example 2 except that the crossing angle was 3 ° and the liquid crystal composition H was injected, and the initial alignment state and switching were observed in the same manner. As a result, the C1 orientation was maintained in the initial orientation state, and almost the entire surface was in a uniform state. When a rectangular pulse having a peak value of 15 V was applied, switching between uniforms occurred with a pulse width of 21 μsec.

Comparative Example 3 85 parts by weight of a liquid crystal composition G having a chiral smectic C phase, which was not subjected to the activated carbon treatment synthesized in Example 5
A liquid crystal composition I was prepared by mixing 15 parts by weight of (4-octanoyloxyphenyl) -5-decylpyrimidine. A liquid crystal device was prepared in exactly the same manner as in Example 2 except that the liquid crystal composition 1 was injected, and the initial alignment state and switching were observed in the same manner. Although the C1 orientation was maintained in the initial orientation state, about 25% was in the spray state and the remaining 75% was in the splay state.
% Were in uniform. When a rectangular pulse having a peak value of 15 V was applied in the same manner as in Example 2, switching between the uniform 2 states became difficult to occur because the spray state was stable, and the obtained threshold value was 26 μsec.

Example 7 Synthesis of 2- (4-butylphenyl) -5- (4-nonanoyloxyphenyl) thiazole 2- (4-butylphenyl) synthesized in the same manner as in JP-A-4-128274. 5.00 g (16.2 mmol) of -5- (4-hydroxyphenyl) thiazole
e), 2.56 g (16.2 mmole) of nonanoic acid and 120 ml of dichloromethane were put into a 300 ml eggplant flask, and 3.73 g (18.1 mmole) of N, N'-dicyclohexylcarbodiimide and 0.4 ml of 4-dimethylaminopyridine were stirred at room temperature. 12 g were added in sequence, followed by stirring at room temperature for 6 hours. The precipitated N, N'-dicyclohexylurea was removed by filtration, the filtrate was evaporated to dryness under reduced pressure, and the residue was purified by silica gel column chromatography (eluent: hexane / chloroform: 1/1) and recrystallized from ethanol to be colorless. 5.62 g (yield 77.4%) of crystals were obtained.

Acetone was added to 3.00 g of the crystal and dissolved under reflux, 0.90 g of activated carbon was added, and the mixture was stirred at room temperature for 5 minutes. After refluxing again, the solution was suction filtered while hot, the activated carbon was removed by filtration, the filtrate was cooled in a freezer, and the precipitated crystals were collected by filtration. 2.58 g (purification yield 8 by activated carbon treatment)
6.0%)

Example 8 A liquid crystal composition J having a chiral smectic C phase (85 parts by weight) was synthesized in Example 7 and activated carbon treated 2- (4
-Butylphenyl) -5- (4-nonanoyloxyphenyl) thiazole in an amount of 15 parts by weight.
It was created. A liquid crystal device was prepared in exactly the same manner as in Example 2 except that the liquid crystal composition K was injected, and the initial alignment state and switching were observed in the same manner. As a result, the C1 orientation was maintained in the initial orientation state, and almost the entire surface was in a uniform state. When a rectangular pulse with a peak value of 15 V is applied,
Switching between uniforms occurred with a pulse width of 25 μsec.

Comparative Example 4 A liquid crystal composition J having a chiral smectic C phase (85 parts by weight) was mixed with the activated carbon synthesized in Example 7 but not treated with activated carbon 2
Liquid crystal composition L was prepared by mixing 15 parts by weight of-(4-butylphenyl) -5- (4-nonanoyloxyphenyl) thiazole. A liquid crystal device was prepared in exactly the same manner as in Example 2 except that the liquid crystal composition L was injected, and the initial alignment state and switching were observed in the same manner. Although the C1 orientation was maintained in the initial orientation state, about 10% was in the spray state and the remaining 90% was in the uniform state. When a rectangular pulse having a peak value of 15 V was applied in the same manner as in Example 2, switching between the uniform 2 states became difficult to occur because the spray state was stable, and the obtained threshold value was 33 μsec.

Example 9 Synthesis of Optically Active 2- [4- (2-fluorooctyloxy) phenyl] -5-decylpyrimidine Optically Active 2-Fluoro-1-Synthesized by the Method of JP-A-62-93248 Octanol was used in JP-A-63-22.
Optically active 2-fluoro-1-octyl-p-toluenesulfonic acid ester was obtained by the method of JP-A-042.

5.00 g (16.0 mmole) of 2- (4-hydroxyphenyl) -5-nonylpyrimidine, D
Dissolve 15 ml of MF in a 100 ml eggplant flask, and add 0.71 g of 60% oily sodium hydride under ice-cooling and stirring.
(17.8 mmole) was added, followed by stirring at room temperature for 15 minutes. Subsequently, the optically active 2-fluoro-1-
4.84 g of octyl-p-toluenesulfonic acid ester
(16.0 mmole) was added, and the mixture was heated and stirred at 90 ° C. for 5 hours. After completion of the reaction, water was added to the reaction product, and the mixture was extracted with ethyl acetate. The organic layer was washed with water, dried over sodium sulfate and the solvent was evaporated to dryness under reduced pressure. The residue was purified by silica gel column chromatography (eluent: chloroform), and recrystallized from a mixed solvent of hexane and ethanol to obtain 5.21 g of colorless crystals (yield: 73.6).
%).

The crystals (3.50 g) were purified by alumina column chromatography (eluent: toluene), and toluene was evaporated to dryness under reduced pressure.
Add an ethanol mixed solvent and heat to dissolve.
0 g was added and the mixture was stirred at room temperature for 5 minutes. Subsequently, the mixture was refluxed, suction filtered while hot, the activated carbon was removed by filtration, the filtrate was cooled in a freezer, and the precipitated crystals were collected by filtration. Yield 3.11
g (88.9% purification yield by alumina column chromatography and activated carbon treatment) (10)

Example 10 90 parts by weight of a liquid crystal composition M having a chiral smectic C layer and optically active 2- [4- (2) synthesized in Example 9 and treated with activated carbon and subjected to alumina column chromatography.
[Fluorooctyloxy) phenyl] -5-decylpyrimidine (10) (10 parts by weight) was mixed to prepare a liquid crystal composition N. A liquid crystal device was prepared in exactly the same manner as in Example 2 except that the crossing angle was 5 ° and the liquid crystal composition N was injected, and the initial alignment state and switching were observed in the same manner. As a result, the C1 orientation is maintained in the initial orientation state,
Almost the entire surface was in a uniform state. When a rectangular pulse having a peak value of 15 V was applied, switching between uniforms occurred with a pulse width of 12 μsec.

Comparative Example 5 90 parts by weight of a liquid crystal composition M having a chiral smectic C layer and the optically active 2- [4] synthesized in Example 9 which were not treated with activated carbon and subjected to alumina column chromatography.
-(2-fluorooctyloxy) phenyl] -5-decylpyrimidine was mixed in an amount of 10 parts by weight to prepare a liquid crystal composition O. A liquid crystal device was prepared in exactly the same manner as in Example 10 except that the liquid crystal composition O was injected, and the initial alignment state and switching were observed in the same manner. C in the initial alignment state
Although one orientation was maintained, about 20% was in the spray state and the remaining 80% was in the uniform state. When a rectangle having a peak value of 15 V was applied in the same manner as in Example 2, switching between the uniform 2 states became difficult because the spray state was stable, and the obtained threshold value was 20 μsec.
Met.

Activated carbon treatment was applied to the purification process from Example 2 and Comparative Example 1, Example 4 and Comparative Example 2, Example 6 and Comparative Example 3, Example 8 and Comparative Example 4, and Example 10 and Comparative Example 5. In any case, the liquid crystal composition containing the compound obtained was unstable in the spray state, the uniform state was stable, and the switching characteristics became better than the liquid crystal composition containing the compound not subjected to the activated carbon treatment. It became.

[0100]

As described above, the liquid crystal composition containing the compound subjected to the purification step of the activated carbon treatment in the present invention, particularly the liquid crystal device using the ferroelectric liquid crystal composition, has high contrast and good switching characteristics. It has an effect. A display device in which the liquid crystal element using the liquid crystal composition of the present invention is used as a display element and combined with a light source, a driving circuit, and the like is a favorable device.

[Brief description of the drawings]

FIG. 1 is a schematic view showing an example of a liquid crystal device using a liquid crystal composition according to the present invention.

FIG. 2 is an explanatory diagram showing C1 and C2 orientations.

FIG. 3 is an explanatory diagram showing a relationship among a cone angle, a pretilt angle, and a layer inclination angle in C1 and C2 orientations.

FIG. 4 is a block diagram showing a liquid crystal device and a graphics controller of the present invention.

FIG. 5 is a timing chart of image information communication between the liquid crystal device of the present invention and a graphic controller.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Chiral smectic liquid crystal layer 2 Glass substrate 3 Transparent electrode 4 Alignment layer 5 Spencer 8 Polarizer 9 Light source 20a, 20b Substrate surface 21 Liquid crystal layer 22 C1 orientation 23 C2 orientation A Rubbing direction 31 Cone 32 Substrate normal 33 Liquid crystal molecule 101 Ferroelectric Liquid crystal display device 102 graphics controller 103 display panel 104 scan line drive circuit 105 information line drive circuit 106 decoder 107 scan signal generation circuit 108 shift register 109 line memory 110 information signal generation circuit 111 drive control circuit 112 GCPU 113 host CPU 114 VRAM

Claims (7)

[Claims] 1. A method for preparing a liquid crystal composition containing a plurality of components, wherein at least one of the compounds as the components is purified using 10 to 50% by weight of activated carbon with respect to the compounds. And a step of mixing the purified compound with other components. 2. The method for preparing a liquid crystal composition according to claim 1, wherein 20 to 35% by weight of activated carbon is used based on the compound. 3. The method for preparing a liquid crystal composition according to claim 1, wherein the purification step includes alumina column chromatography. 4. The method for preparing a liquid crystal composition according to claim 1, wherein the purification step includes silica gel column chromatography. 5. The method for preparing a liquid crystal composition according to claim 1, wherein the purification step includes alumina column chromatography and silica gel column chromatography. 6. The method for preparing a liquid crystal composition according to claim 1, wherein at least the compound purified by activated carbon is a liquid crystalline compound exhibiting a smectic phase. 7. The method for preparing a liquid crystal composition according to claim 1, wherein the liquid crystal composition exhibits a chiral smectic phase.