JPS63137984A - Ferroelectric liquid crystal device - Google Patents

Abstract

PURPOSE:To obtain the titled device broad in the temperature range for low- temperature operation, with increased quick response capability at low temperatures, good in the orientation state of the liquid crystal layer, outstanding in display characteristics, by using, as the ferroelectric liquid crystal layer, a novel liquid crystal composition containing specific liquid crystal compound. CONSTITUTION:The objective device made up of a base plate, electric voltage- applying means, orientation control layer and ferroelectric liquid crystal layer, using as said ferroelectric liquid crystal layer, a liquid crystal composition containing as a component, a compound of formula I (R1 and R2 are each chain group capable of substitution; A1 and A2 are each six-membered ring-contg. divalent group capable of substitution; X1 and X2 are each divalent chain group). Said compound of the formula I is e.g., a compound of formula II, which can be prepared by reaction, in the presence of NaOH, between p-hydroxy-(2- ethoxypropyloxycarbonyl vinylene)biphenyl and p-propyl benzyl alcohol in THF.

Description

Detailed Description of the Invention [Technical Field] The present invention relates to liquid crystal elements used in display elements, liquid crystal light shutters, etc., and more specifically, to novel ferroelectric liquid crystal compositions with improved response characteristics to electric fields. The present invention relates to a ferroelectric liquid crystal device using a ferroelectric liquid crystal device.

[Background technology]

Conventionally, liquid crystals have been applied as electro-optical elements in various fields. Most of the liquid crystal elements currently in practical use are, for example, M, 5chadt and W, “Applied Physics Letters” by Helfrich.
Vo, 18, No. 4 (1971, 2, 15), P
, 127-128 “Voltage-Dpenden
t 0ptical Activity of
aT w i s t e d N e m a t
i c L i q u i d C ry s t
TN (twisted ne
matic) type liquid crystal.

These are based on the dielectric alignment effect of liquid crystals, and utilize the effect that the average molecular axis direction is oriented in a specific direction due to the dielectric anisotropy of liquid crystal molecules due to an applied electric field. The optical response speed of these devices is said to have a limit of milliseconds, which is too slow for many applications.

To improve the drawbacks of conventional liquid crystal devices, the use of bistable liquid crystal devices has been proposed by C1ark and Lagerwall (Japanese Patent Application Laid-Open No.
6-107216, US Pat. No. 4,367,924, etc.). Bistable liquid crystals are generally chiral smectic C phase (SmC") or H phase (SmH").
) is 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, and thus has a bistable state consisting of a first optically stable state and a second optically stable state.
Unlike the optical modulation elements used in type liquid crystals, for example, the liquid crystal is oriented in a first optically stable state for one electric field vector and in a second optically stable state for the other electric field vector. The liquid crystal is aligned. In addition, this type of liquid crystal
It has a property (bistability) of taking one of the above two stable states in response to an applied electric field and maintaining that state when no electric field is applied.

In addition to the above-mentioned feature of bistability, ferroelectric liquid crystals have the excellent feature of high-speed response. This is because the spontaneous polarization of the ferroelectric liquid crystal and the applied electric field directly act to induce a transition in the orientation state, which is 3 to 4 orders of magnitude faster than the response speed due to the effect of the dielectric anisotropy and the electric field.

In this way, ferroelectric liquid crystals potentially have extremely excellent properties, and by utilizing these properties,
Significant substantial improvements are obtained over many of the problems of conventional TN type devices mentioned above.

In particular, it is expected to be applied to high-speed optical shutters and high-density, large-screen displays.

[Problem to be solved by the invention]

For this reason, extensive research has been conducted on liquid crystal materials with ferroelectric properties used in ferroelectric liquid crystal devices, but the ferroelectric liquid crystal devices reported to date have been able to: ■ widen the temperature range of low-temperature operation; There is hardly anything that satisfies the need to increase high-speed response at low temperatures.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a ferroelectric liquid crystal element which eliminates the above-mentioned drawbacks or disadvantages.

Another object of the present invention is to provide a novel ferroelectric liquid crystal composition. Still another object of the present invention is to provide a ferroelectric liquid crystal element that exhibits bistable monodomain properties and has a good alignment state.

[Means for solving the invention]

According to research by the present inventors, a ferroelectric liquid crystal composition used in a ferroelectric liquid crystal element can be prepared by mixing a liquid crystal compound represented by the following general formula (I); It has been found that the temperature range that gives a vesmectic C phase is expanded, especially on the low temperature side, and that the response speed is improved and the display characteristics are improved.

The present invention will be explained in more detail below. In the following description, both "%" and "part" expressing quantitative ratio are based on weight.

Rl-A, -X, -0-A2-X2-C-R2...
...(I) (wherein R8 represents a branched or straight chain group which may have a substituent.

Preferably, R1 is an alkyl group such as methyl, ethyl, propyl, butyl, pentyl, hexyl, isopropyl, etc., or an alkoxy group such as methoxy, ethoxy, propyloxy, butoxy, 2-methylbutoxy group, which may have a substituent. , acetyl, propionyl, butynyl, valeryl,
Acyl groups such as valmitoyl and 2-methylpropionyl,
Acyloxy groups such as acetyloxy, propionyloxy, butynyloxy, 2-methylpropyloxy, alkoxycarbonyl groups such as methoxycarbonyl, ethoxycarbonyl, butoxycarbonyl, 2-methylbutoxycarbonyl, and methoxycarbonyloxy, ethoxycarbonyloxy, butoxycarbonyloxy , 2-methylbutoxycarbonyloxy, etc., and R2 is an alkyl group such as methyl, ethyl, propyl, butyl, pentyl, hexyl, isopropyl, which may have a substituent, and methoxy, ethoxy, propyl. It is selected from alkoxy groups such as oxy, butoxy, and 2-methylbutoxy.

More preferably, at least one of R1 and R2 represents a chain group having a branched or straight chain alkyl group which may have a substituent having an asymmetric carbon. Further, substituents represented by R1 and R2 include halogen atoms such as fluorine, chlorine, and bromine, methoxy, ethoxy, propyloxy,
Examples include alkoxy groups such as butoxy, trifluoromethane, and cyano groups.

A1 and A2 represent a divalent group having a six-membered ring which may have a substituent. Preferred specific examples of the group having a six-membered ring represented by A and A2 are represented by the following general formula % (wherein A3 and A4 may have a substituent).

It is preferable to select m and n from 0. 1 or 2
and is represented by m tenn = 1 or 2.

Furthermore, the substituents represented by A3 and A4 include fluorine,
Examples include halogen atoms such as chlorine and bromine, alkyl groups such as methyl, ethyl, propyl, and butyl, alkoxy groups such as methoxy, ethoxy, and propoxy, trifluoromethane, and cyano groups. ) Xl and x2 are divalent chain groups, preferably selected from 10CH2C-, and X2 is -
CH=CH-, ]1 -CH2CH2- and -CH2- are preferable.

Below, typical exemplified compound No. of the compound represented by general formula (I) is shown.

Next, typical synthesis examples of the compounds used in the present invention are shown below.

[Synthesis Example 1) P-propylbenzyloxy-P'-(
Synthesis of 2-ethoxypropyloxycarbonylvinylene)biphenyl (compound example (16)) P-hydroxy-(
To a solution of 0.99 g of 2-ethoxypropyloxycarbonylvinylene)biphenyl dissolved in 5 ml of tetrahydrofuran, 0.08 g of sodium hydride and 3 mj2 of tetrahydrofuran were added and stirred. Next, 0.45 g of P-propylbenzyl alcohol was added to 3 g of tetrahydrofuran.
ml was added to the reaction solution, heated under reflux for 2 hours while stirring, and then reacted at room temperature for 6 hours.

The reaction mixture was then poured into water, neutralized with acetic acid, and extracted with isopropyl ether. The obtained organic layer was dried over sodium sulfate, the solvent was distilled off, and the layer was purified by silica gel column chromatography. (Mobile phase, 5% methanol/
Chloroform) Yield: 0.83 g [Synthesis Example 2'IP-octoxybenzoic acid P'-(2-ethoxypropyl)oxycarbonylphenethyl ester (Compound Example (1))
Synthesis of 3.2 mI of pyridine to 1.0 g of 3-hydroxypropionic acid 2-ethoxypropyl ester! After adding and cooling on ice, 1.0 g of P-octyloxycarboxylic acid chloride was added to 6 m
jl! Add dropwise a toluene solution of
After stirring for 3 hours below, the mixture was stirred at room temperature for 20 hours. After the reaction was completed, the reaction mixture was poured into water, acidified with 1N HCl, and extracted with ethyl acetate. The obtained organic layer was further washed with water, dried over sodium sulfate, the solvent was distilled off, and subjected to silica gel column chromatography (mobile phase,
Purification was performed using hexane: ethyl acetate = 3:1). Although the method for synthesizing a typical compound with a yield of 1.2 g or more has been described, other compounds represented by the general formula (I) were also synthesized in the same manner.

In the compound represented by the general formula (I), -X3niCH-CH-2-CH2CH2-9-CH2-9-O
CH2-, single bond P: 0 or 1, this compound is synthesized as follows.

When p=o (Example: Synthesis Example 1) R, -A, -X, -1+ HO-A2-x2-c-
When R2P=1 (Example: Synthesis Example 2) R, -A, -X, -CI! +HO-A2-X2-C-R
2 The symbols used here are as defined in the previous section.

The liquid crystal element of the present invention has the general formula (I
) is used as a liquid crystal composition containing at least one compound as a compounding component.

Further, the ferroelectric liquid crystal element according to the present invention can be produced by heating the liquid crystal composition in vacuum to an isotropic liquid temperature, sealing it in an element cell, gradually cooling it to form a liquid crystal phase, and returning it to normal pressure. It is desirable to obtain.

Other ferroelectric liquid crystal compounds used in the present invention [Wataru] Combination of the compound of the present invention and one or more of the above-mentioned ferroelectric liquid crystal compounds other than the compound of the present invention (hereinafter abbreviated as ferroelectric liquid crystal material) The ratio is preferably 1 to 500 parts by weight of the compound of the present invention per 100 parts by weight of the ferroelectric liquid crystal material. Also, when using two or more compounds of the present invention, the blending ratio with the ferroelectric liquid crystal material is 1 to 500 parts by weight of the mixture of two or more compounds of the present invention per 100 parts by weight of the above-mentioned ferroelectric liquid crystal material. It is preferable to set it as part.

FIG. 1 is a schematic cross-sectional view of an example of a liquid crystal display element having a ferroelectric liquid crystal layer according to the present invention, for explaining the structure of the ferroelectric liquid crystal element.

In FIG. 1, the number l is a ferroelectric liquid crystal layer, 2 is a glass substrate, 3 is a transparent electrode, 4 is an insulating alignment control film, 5 is a spacer, 6 is a lead wire, 7 is a power source, 8 is a polarizing plate, 9 indicates a light source.

The two glass substrates 2 have In203 and In205, respectively.
n02 or ITO (Indium-Tin 0x
A transparent electrode made of a thin film such as IDE) is coated.

On top of this, a thin film of a polymer such as polyimide is rubbed with gauze or acetate flocked cloth to form an insulating alignment control layer that aligns the liquid crystals in the rubbing direction. Examples of insulating materials include silicon nitride, hydrogen-containing silicon carbide, silicon oxide, boron nitride, hydrogen-containing boron nitride, cerium oxide, aluminum oxide,
Form an inorganic insulating layer of zirconium oxide, titanium oxide, magnesium fluoride, etc., and then apply polyvinyl alcohol, polyimide, polyamideimide, polyesterimide, polyparaxylene, polyester, polycarbonate, polyvinyl acecool, polyvinyl chloride. ,
The insulating alignment control layer may be formed of two layers using an organic insulating material such as polyvinyl acetate, polyamide, polystyrene, cellulose resin, melamine resin, Yulia resin, acrylic resin, or photoresist resin as the alignment control film,
Alternatively, it may be a single layer of an insulating orientation control layer made of an inorganic material or an insulating orientation control layer of an organic material. If this insulating orientation control layer is inorganic, it can be formed by a vapor deposition method, or if it is organic, it can be formed using a solution containing an organic insulating material or its precursor solution (
0.1 to 20% by weight, preferably 0.2 to 10% by weight) in a solvent, and applied by spinner coating method, dip coating method, screen printing method, swige coating method, roll coating method, etc. It can be cured and formed under curing conditions (eg, heating).

The thickness of the insulating alignment layer is usually 50 to 1μ, preferably 100 to 5,000, more preferably 500 to 3
000 people is suitable.

These two glass substrates 2 are kept at an arbitrary distance by a spacer 5. For example, silica beads or alumina beads having a predetermined diameter are used as spacers to sandwich the two glass substrates, and the periphery is covered with a sealing material, for example. There is a method of sealing using an epoxy adhesive.Also, a polymer film or glass fiber may be used as a spacer.The ferroelectric liquid crystal is sealed between them.

The device cell thickness in which the ferroelectric liquid crystal is sealed is generally 0.5
μ to 20 μ, preferably 1 μ to 5 μ.

The transparent electrode 3 is connected to an external power source 7 by a lead wire. Further, a polarizing plate 8 is bonded to the outside of the glass substrate 2.

The device shown in FIG. 1 is of a transmission type, so it is equipped with a light source 9.

FIG. 2 schematically depicts an example of a cell for explaining the operation of a ferroelectric liquid crystal element. 21a and 21b are In203, 5n02 or ITO (Indi
A substrate (glass plate) coated with a transparent electrode made of a thin film such as um-Tin oxide), between which a liquid crystal molecular layer 22 is oriented perpendicular to the glass surface.
*phase or SmH* phase liquid crystal is enclosed. A thick line 23 represents a liquid crystal molecule, and this liquid crystal molecule 2
3 has a dipole moment (P soil) 24 in the direction perpendicular to its molecule. When a voltage higher than a certain threshold is applied between the electrodes on the substrates 21a and 21b, the helical structure of the liquid crystal molecules 23 is unraveled, and the dipole moments (P±) 24 are all directed in the direction of the electric field. The direction can be changed.The liquid crystal molecules 23 have an elongated shape and exhibit refractive index anisotropy in the long axis direction and the short axis direction. It is easily understood that if the device is placed in the same position, it becomes a liquid crystal optical modulation element whose optical characteristics change depending on the polarity of applied voltage.

The liquid crystal cell preferably used in the optical modulation element of the present invention can have a sufficiently thin thickness (for example, 10 μm or less). As the liquid crystal layer becomes thinner, the helical structure of the liquid crystal molecules unravels even when no electric field is applied, as shown in Figure 3, and the dipole moment Pa or Pb is directed upward (34a) or downward (34b). ). When an electric field Ea or Eb of different polarity above a certain threshold value is applied to such a cell by the voltage applying means 31a and 31b as shown in FIG. 3, the dipole moment corresponds to the electric field vector of the electric field Ea or Eb. The liquid crystal molecules change direction upward 34a or downward 34b, and accordingly the liquid crystal molecules are in the first stable state 33a or in the second stable state 33a.
is oriented in one of the stable states 33b.

As mentioned earlier, there are two advantages to using such ferroelectricity as an optical modulation element.

The first is that the response speed is extremely fast, and the second is that the alignment of liquid crystal molecules has bistability. To further explain the second point with reference to FIG. 2, for example, when the electric field Ea is applied, the liquid crystal molecules are oriented in a first stable state 33a, and this state remains stable even when the electric field is turned off. Moreover, when an electric field Eb in the opposite direction is applied, the liquid crystal molecules enter the second stable state 2.
3b and changes the orientation of the molecule, but it remains in this state even after the electric field is turned off. Also, the applied electric field Ea
Alternatively, each previous orientation state is still maintained as long as Eb does not exceed a certain threshold.

The compounds of the present invention will be explained in more detail with reference to Examples below, but the present invention is not limited to these Examples.

Example 1 Two 0.7 m thick glass plates were prepared, and an ITO film was formed on each glass plate to create a voltage application electrode.

Furthermore, SiO2 was deposited on top of this to form an insulating layer.

Silane coupling agent [KBM manufactured by Shin-Etsu Chemical Co., Ltd.] on the glass plate
-602: A 2% isopropyl alcohol solution of IO was applied for 15 seconds at a rotational speed of 200 Orr, p, m for surface treatment. Thereafter, a heat drying treatment was performed at 120° C. for 20 minutes.

Furthermore, a polyimide resin precursor (Toshiku IteSP-510) was placed on a glass plate with an ITO film that had been surface-treated.
% dimethylacetamide solution at rotation speed 2000 r, p,
It was applied for 15 seconds using a spinner. After the film was formed, a heating table baking treatment was performed at 300° C. for 60 minutes. The thickness of the coating film at this time was about 700.

This fired coating is rubbed with acetate flocked cloth, then washed with isopropyl alcohol, and alumina beads with an average particle size of 2 μm are sprinkled on one glass plate, so that the rubbing axes are parallel to each other. Then, glue the glass plates together using an adhesive sealant [Rixon Bond (Chisso)], and leave them together for 60 minutes.
A cell was prepared by heating and drying at 0°C. The cell thickness of this cell was measured using a Bereck phase plate and was found to be approximately 2 μm.

Next, the exemplified compound Nα1 and the ferroelectric liquid crystal compound represented by the following structural formula were mixed in the following parts by weight, and the exemplified compound Nos. 1 and 1 were mixed in the following parts by weight.
5 (hereinafter, the mark * indicates an asymmetric carbon) Under the Tokichi phase, a uniformly mixed liquid state was vacuum injected into the cell prepared by the method described above. 30 at 0.5°C/h from Tokichi phase
A ferroelectric liquid crystal device was created by slowly cooling it to ℃.

Using this ferroelectric liquid crystal element, by applying a peak-to-peak voltage of 20V, the optical response under crossed Nicols is detected and responded from the time the voltage is applied until the amount of transmitted light changes by 90%. The speed (hereinafter referred to as optical response speed) was measured. The results are shown below.

20°C30°C' 40°C370μ5ec
340μ5eC295μSeC Comparative Example 1 A ferroelectric liquid crystal element was created in the same manner as in Example 1, except that the exemplified compound N001 used in Example 1 was not included in the ferroelectric liquid crystal layer, and the optical response speed was measured. did. The results are shown below.

208C30°0 40°C 420μ5eC380μ5eC325μSeC Example 2 Same as Example 1 except that in place of the ferroelectric liquid crystal compound l used in Example 1, a ferroelectric liquid crystal compound represented by the following structural formula was used in each part by weight. A ferroelectric liquid crystal element was prepared by the method described in the following, and the light superimposition portion was heated at 25°0 35°0 50°C600μ in the same manner as in Example 1.
SeC450μSeC200μSeC Comparative Example 2 A ferroelectric liquid crystal element was prepared in the same manner as in Example 2, except that the exemplified compound No. 1 used in Example 2 was not included in the ferroelectric liquid crystal layer, and the same method as in Example 1 was made. The optical response speed was measured using the method described above. I'll show you the results at dusk.

20°025°G 3580 50℃ 60
'C80''C1100μsec 730μsec
510μsec 230μsec 170p
sec 100 μsec Example 3 In place of the ferroelectric liquid crystal compound used in Example 1, a ferroelectric liquid crystal compound represented by the following structural formula was used in each part by weight. A dielectric liquid crystal element was prepared, and the optical response speed was measured in the same manner as in Example 1. The results are shown below.

25°C; 3200μsec 35°C; 260
0 μsec 45°C; 1600 μsec Comparative Example 3 A ferroelectric liquid crystal element was produced in the same manner as in Example 3, except that the ferroelectric liquid crystal layer did not contain Exemplary Compound No. 1 used in Example 3. The optical response speed was measured in the same manner as in Example 1. The results are shown below.

20°C25°C35°C45°C 5400μsec 3600μsec 29
00 p sec 1800 μsec Example 4 The same method as in Example 1 except that the ferroelectric liquid crystal compound shown by the following structural formula was used in each part by weight instead of the ferroelectric liquid crystal compound used in Example 1. A ferroelectric liquid crystal device was prepared in this manner, and the optical response speed was measured in the same manner as in Example 1.

The results are shown below.

55°C; 1007zsec 65°C; 9
0μ5eC70°C; Unmeasurable Comparative Example 4 A ferroelectric liquid crystal element was prepared in the same manner as in Example 4, except that the exemplified compound N001 used in Example 4 was not contained in the ferroelectric liquid crystal layer. The optical response speed was measured in the same manner as in Example 1. The results are shown below.

75°C; Zoo μsec Example 5 The same method as Example 1 was used, except that each part by weight of a ferroelectric liquid crystal compound represented by the following structural formula was used instead of the ferroelectric liquid crystal compound used in Example 1. A ferroelectric liquid crystal device was prepared in this manner, and the optical response speed was measured in the same manner as in Example 1.

The results are shown below.

25°C; 15007zsec 35°C; 13
00 μsec 45°C; 870 μSeC Comparative Example 5 A ferroelectric liquid crystal element was prepared in the same manner as in Example 5 except that the exemplified compound No. 1 used in Example 5 was not included in the ferroelectric liquid crystal layer. The optical response speed was measured in the same manner as in Example 1. The results are shown below.

35°C45°C50°C 1500μsec 1000μsec
800 μsec Example 6 The ferroelectric liquid crystal compound used in Example 1 was replaced with a ferroelectric liquid crystal compound represented by the following structural formula in each part by weight. A liquid crystal device was prepared, and the optical response speed was measured in the same manner as in Example 1.

The results are shown below.

5°C; 750μsec 206C; 500μ
sec 35°C; 430 μsec Comparative Example 6 A ferroelectric liquid crystal element was prepared in the same manner as in Example 6, except that the exemplified compounds No. and 1 used in Example 6 were not contained in the ferroelectric liquid crystal layer. The optical response speed was measured in the same manner as in Example 1. The results are shown below.

5°C20°C35°C 900μsec 560μsec 480μs
ec Example 8 A ferroelectric liquid crystal element was produced in exactly the same manner except that a 2% dimethylacetamide solution of polyimide resin precursor used in Example 1 was replaced with a 32% aqueous solution of polyvinyl alcohol resin (PVA-11 manufactured by Kuraray ■). was created and the optical response speed was measured.

20°C30°C 40°C 380μsec 350μsec 290μs
ec Example 9 A ferroelectric liquid crystal element was created in the same manner as in Example 1, except that the insulating alignment control layer was created only with polyimide resin without using 5iO7 used in Example 1. The optical response speed was measured.

20°C30°C40°C 370 μsec 350 p sec 3
10 μsec Examples 10 to 18 In place of exemplified compound N011 used in Example 2, exemplified compound 2.4.6.9. 12. 14. ■5. A ferroelectric liquid crystal device was prepared in exactly the same manner as in Example 2, except that No. 16 was used in the weight parts shown in Table 1, and the optical response speed was measured. The results are shown in Table 1.

Table 1 [Effects of the invention] The compound of the present invention is a compound that improves and improves the low-temperature operating characteristics, high-speed response, etc. of a ferroelectric liquid crystal element, and by incorporating the compound into a ferroelectric liquid crystal element, We were able to obtain an improved ferroelectric liquid crystal device with a wider temperature range for low-temperature operation, (1) increased high-speed response at low temperatures, and (2) a liquid crystal layer in a good alignment state.

[Brief explanation of the drawing]

Fig. 1 is a schematic cross-sectional view of an example of a liquid crystal display element using the ferroelectric liquid crystal of the present invention, and Figs. 2 and 3 show an example of an element cell to explain the operation of the ferroelectric liquid crystal element. FIG. 2 is a schematic perspective view. In FIG. 1, 1... Ferroelectric liquid crystal layer 2... Glass substrate 3.
...Transparent electrode 4...Insulating alignment control film 5
...Spacer 6...Lead wire 7...
Power supply 8...Polarizing plate 9...Light source
■. ...Incoming light ■...Transmitted light In Fig. 2, 21a...Substrate 21b...Substrate 22
...Ferroelectric liquid crystal layer 23...Liquid crystal molecules 24.
...Dipole moment (P soil) In Figure 3,

Claims (9)

[Claims] (1) In a ferroelectric liquid crystal element that includes a substrate, a voltage application means, an alignment control layer, and a ferroelectric liquid crystal layer, the ferroelectric liquid crystal layer has the following general formula (I) ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼・・・・・・・・・(
A ferroelectric liquid crystal device comprising at least one compound represented by I). (However, in the formula, R_1 and R_2 represent a branched or straight chain group that may have a substituent, and R_1 and R_2 may be the same or different. A_1 and A_2 have a substituent. (A_1 and A_2 may be the same or different, and X_1 and X_2 are divalent chain groups.) (2) In the general formula (I), R_1 is selected from a branched or straight-chain alkyl group, an acyl group, an acyloxy group, an alkoxy group, an alkoxycarbonyl group, and an alkoxycarbonyloxy group, which may have a substituent, R
2. The ferroelectric liquid crystal device according to claim 1, wherein _2 is each selected from a linear or branched alkyl group and an alkoxy group which may have a substituent. (3) The ferroelectric liquid crystal device according to claim 1, wherein in the general formula (I), at least one of R_1 and R_2 has an asymmetric carbon. (4) The ferroelectric liquid crystal device according to claim 1, wherein in the general formula (I), A_1 and A_2 are represented by the following general formula (II). -(A_3)-_m-(A_4)-_n(II) (However, A_3 and A_4 in the formula are ▲Mathematical formulas, chemical formulas, tables, etc.▼, ▲Mathematical formulas, chemical formulas, tables, etc.▼, ▲Mathematical formulas,
There are chemical formulas, tables, etc. ▼, ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼, ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼, ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼, ▲ There are mathematical formulas, chemical formulas, tables, etc. A six-membered ring that may have a substituent represented by ▼, ▲There are mathematical formulas, chemical formulas, tables, etc.▼, ▲There are mathematical formulas, chemical formulas, tables, etc.▼ or ▲There are mathematical formulas, chemical formulas, tables, etc.▼ is a group having m and n are 0, 1 or 2,
and m+n=1 or 2. ) (5) In the above general formula (I), X_1 is ▲There are mathematical formulas, chemical formulas, tables, etc.▼, ▲There are mathematical formulas, chemical formulas, tables, etc.▼, -CH_2CH_2-, ▲There are mathematical formulas, chemical formulas, tables, etc.▼, - CH_2−, ▲There are mathematical formulas, chemical formulas, tables, etc.▼ and ▲There are mathematical formulas, chemical formulas, tables, etc.▼, and X_2
are -CH=CH-, -CH_2CH_2-, and -CH
The ferroelectric liquid crystal element according to claim 1, characterized in that the ferroelectric liquid crystal element is selected from _2-. (6) Ferroelectricity according to claim 1, characterized in that in the general formula (I), the substituents for R_1 and R_2 are selected from a halogen atom, an alkoxy group, a trifluoromethyl group, and a cyano group. liquid crystal element. (7) The substituent of A_1 and A_2 in the general formula (I) is selected from a halogen atom, an alkyl group, an alkoxy group, a trifluoromethyl group, and a cyano group. Ferroelectric liquid crystal element. (8) The ferroelectric liquid crystal device according to claim 1, wherein the ferroelectric liquid crystal device according to claim 1 is a liquid crystal light modulation device. (9) The ferroelectric liquid crystal device according to claim 1, wherein the ferroelectric liquid crystal device according to claim 1 is a liquid crystal display device.