JPH093008A - Bicyclic phenyl ester compound and antiferroelectric liquid crystal composition containing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject new compound capable of securing antiferroelectric phase over a wide temperature range through its mixing with an antiferroelectric liquid crystal, also of making smectic-A phase exist, and improving the response rate at lower temperatures, thus useful for e.g. liquid crystal display elements. SOLUTION: This new compound is expressed by the formula (R<1> is a 5-12C straight-chain alkyl; R<2> is a 1-15C straight-chain alkyl; X<1> and X<2> are each H, only one party thereof being F; Y<1> and Y<2> are each H, only one party thereof being F), e.g. 2-fluoro-4-n-decanoyloxybenzoic acid 4-heptyloxycarbonylphenyl, ester. The compound of the formula is obtained by reaction between a compound of the formula R<1> COO-Ph(F)-COCl [Ph(F) is a (2- or 3-site F-substituted) 1,4- phenylene] and a compound of the formula HO-Ph(F)-COOR<2> .

Description

Detailed Description of the Invention

[0001]

The present invention relates to a novel bicyclic phenyl ester compound, an antiferroelectric liquid crystal composition containing the same,
And a liquid crystal display device using the same.

[0002]

2. Description of the Related Art Liquid crystal display devices have been used for various small display devices to date because of their low voltage operability, low power consumption, and thin display capability. However, with the recent application of information and OA-related equipment fields or liquid crystal display elements to the TV field and the expansion of applications, high-performance large-sized liquid crystal display elements with display capacities and display qualities that exceed those of conventional CRT display elements. The demand for is increasing rapidly.

However, as long as the current nematic liquid crystal is used, even an active matrix drive liquid crystal display element used for a liquid crystal television has a large size and a low cost due to the complexity of the manufacturing process and low yield. Is not easy. Also, a simple matrix drive
Even with an STN type liquid crystal display element, it is not always easy to drive a large capacity, and it is difficult to display a moving image due to the limited response time. Further, a narrow viewing angle of a display element using a nematic liquid crystal has become a serious problem. Therefore, it is difficult for a nematic liquid crystal display device to satisfy the demand for the above-described high performance large liquid crystal display device.

In such a situation, a liquid crystal display element using a ferroelectric liquid crystal has attracted attention as a high-speed liquid crystal display element. The surface-stabilized ferroelectric liquid crystal (SSFLC) device announced by Clarke and La Gavar is noted for its unprecedented fast response speed and wide viewing angle, and its switching characteristics are detailed. In order to optimize various physical property constants, many ferroelectric liquid crystals have been synthesized. However, the threshold characteristics are inadequate, the layer structure has a chevron structure, and the contrast is poor. High-speed response is not realized. Alignment control is difficult, which is one of the most important features of SSFLC. There are problems that it is difficult to realize bistability, which is difficult to achieve, and it is difficult to recover the orientation due to mechanical impact, and it is necessary to overcome these problems for practical use.

Separately from this, the development of an element having a switching mechanism different from that of SSFLC is also in progress. Switching between the three stable states of a liquid crystal material having an antiferroelectric phase (hereinafter referred to as an antiferroelectric liquid crystal material) is one of these new switching mechanisms (Japanese Journal of A).
pplied Physics, Vol.27, pp.L729,1988).

The antiferroelectric liquid crystal element has three stable states. That is, as seen in the ferroelectric liquid crystal device, 2
There are two uniform states (Ur, Ul) and a third state. Chandani et al. Reported that this third state is the antiferroelectric phase (Japanese Journal of Applied Physics, Vol. 28,
pp.L1261, 1989, Japanese Journal of AppliedPhysic
s, Vol.28, pp.L1265, 1989). Such switching between the three stable states is the first feature of the antiferroelectric liquid crystal device. A second feature of the antiferroelectric liquid crystal element is that there is a clear threshold value for an applied voltage. Furthermore, it has a memory property, which is the third feature of the antiferroelectric liquid crystal element. By utilizing these excellent characteristics, it is possible to realize a liquid crystal display device having a high response speed and a good contrast.

Another major feature is that the layer structure is easily switched by an electric field.
(Japanese Journal of Applied Physics, Vol.28, pp.L
119,1989, Japanese Journal of Applied Physics, Vo
l.29, pp.L111, 1990). This makes it possible to manufacture a liquid crystal display element having a very small number of defects and a self-healing ability for alignment, and to realize a liquid crystal element having excellent contrast. Furthermore, it has been proved that the voltage gradation that is almost impossible with the ferroelectric liquid crystal is possible with the anti-ferroelectric liquid crystal, paving the way for full-colorization, and the importance of the anti-ferroelectric liquid crystal is increasing. (Proceedings of the 4th International Conference on Ferroelectric Liquid Crystals, p. 77, 1993).

As described above, the superiority of the antiferroelectric liquid crystal is becoming clear, but further improvement in response speed is desired. The conventionally proposed antiferroelectric liquid crystal has a sufficient response speed to realize a certain level of display element, but when trying to realize a high-definition display element with 800 or more scanning lines, Response speed is still insufficient,
Higher speed is required. Further, as a major problem of all liquid crystal elements, there is a strong dependence of response speed on temperature. This problem is also great in the case of antiferroelectric liquid crystal elements, and reduction in temperature dependence is strongly desired.

In the case of antiferroelectric liquid crystals, there are two switchings from the antiferroelectric state to the ferroelectric state and from the ferroelectric state to the antiferroelectric state. Two switching speeds due to this voltage, that is, a response speed is an important factor that determines the display quality of the display element. In particular, the response speed from the antiferroelectric state to the ferroelectric state (hereinafter referred to as response speed I) is
For example, in simple matrix drive that scans line-sequentially,
Since the writing speed per scan line-line, the number of scan lines forming one screen is determined, which is important. That is, the faster the response speed I is, the more the number of scanning lines can be increased, and the high-definition element can be realized.

Further, the response speed from the ferroelectric state to the antiferroelectric state (hereinafter referred to as response speed II) varies depending on the design of the driving method of the element. For example, it depends on the set voltage of the offset voltage, but if the response speed II is too fast, the ferroelectric state cannot be maintained sufficiently (bright or dark state cannot be maintained), and if it is too slow, the ferroelectric state is changed. The change to the antiferroelectric state (writing from the bright or dark state to the dark or bright cannot be performed) does not occur, which is inconvenient. That is, the response speed II is set to the optimum response speed after determining the driving method. As described above, it is important that the response speed I is fast in order to realize a high-definition device. The conventionally proposed antiferroelectric liquid crystal has a response speed sufficient to realize a certain level of display element,
When attempting to realize a high-definition display device with a large number of scanning lines, the response speed is still insufficient, and it is necessary to further increase the speed.

[0011]

The problem of the antiferroelectric liquid crystal is that the response speed is further improved, as described above.
This is a further improvement in response speed on the low temperature side. further,
It is desirable that the temperature range of the antiferroelectric phase be expanded and that the smectic A phase be present on the high temperature side. Response speed is M. Nak
According to Agawa, antiferroelectric liquid crystals depend on the rotational viscosity of liquid crystal molecules (Masahiro Nakaga
wa, Japanese Journal of Applied Physics, 30,1759 (199
1)). That is, the lower the viscosity, the faster the response speed. Also,
Looking at the change in response speed with respect to temperature, the response speed decreases exponentially at temperatures below room temperature as a boundary. The antiferroelectric liquid crystal is considered to have a high viscosity because the liquid crystal phase is a smectic phase, so that the viscosity increases rapidly at the low temperature side and the response speed decreases rapidly due to the viscous resistance. ing.

As one of the solutions to this problem, a low-viscosity antiferroelectric liquid crystal has been developed, but it has an appropriate tilt angle, a response speed, and an antiferroelectric phase temperature range, and The fact is that antiferroelectric liquid crystals with low viscosity have not been found yet. Another solution is to install a heater on the device. This method
Although it is a reliable solution to the problem, it cannot be said to be a practically advantageous method because it leads to an increase in the cost of manufacturing the display element and the transmittance is reduced by the heater.

As another method, it is considered to synthesize a compound having a relatively low viscosity and add it to a liquid crystal composition to reduce the viscosity of the entire composition, thereby attempting to improve the response speed. I think it can be the most realistic solution at the moment. The low viscosity substance used in this method is
As a matter of course, the molecular weight is small. However, when the molecular weight is too small, the additive substance volatilizes with time and the transition temperature from the isotropic phase to the liquid crystal phase of the composition becomes too low, which is inconvenient.

Generally, when an antiferroelectric liquid crystal device as a display is considered, the temperature of the device is considered to be at least about 40 ° C. due to the backlight. Therefore, the upper limit temperature of the antiferroelectric phase must be at least 40 ° C. or higher, and preferably 50 ° C. or higher in order to drive the device normally. Then, it is desirable to allow the smectic A phase to be present on the high temperature side of this temperature in order to practically obtain good orientation. On the low-temperature side, it is necessary that the element can be driven at least at 10 ° C. Therefore, the lower limit temperature of the antiferroelectric phase needs to be at least 0 ° C. The present invention has been made from such a viewpoint, and when the novel bicyclic phenyl ester compound represented by the general formula (1) is mixed with the antiferroelectric liquid crystal, the antiferroelectric phase is formed in a wide temperature range. It was found that the antiferroelectric liquid crystal composition which can be ensured at the same time as the presence of the smectic A phase and at a low temperature can be obtained at a very high speed, and the present invention has been completed.

[0015]

That is, the present invention provides the first aspect.
And a bicyclic phenyl ester compound represented by the following general formula (1).

Embedded image (In the formula, R ¹ is a straight-chain alkyl group having 5 to 12 carbon atoms, R ² is a straight-chain alkyl group having 1 to 15 carbon atoms, X ¹ and X ² are H or either F, Y ¹ or Y. ² is H or one of them is F).

Secondly, at least one bicyclic phenyl ester compound represented by the general formula (1) according to claim 1 is contained in an antiferroelectric liquid crystal or an antiferroelectric liquid crystal composition. Is an antiferroelectric liquid crystal composition. Furthermore, the present invention thirdly provides a simple matrix liquid crystal display device characterized in that the antiferroelectric liquid crystal composition according to claim 7 is sandwiched between substrates in which scanning electrodes and signal electrodes are arranged in a matrix. .

In the present invention, in the bicyclic phenyl ester compound of the general formula (1), R ¹ preferably has 8 to 12 carbon atoms. When the number of carbon atoms is 7 or less, when mixed with an antiferroelectric liquid crystal or an antiferroelectric liquid crystal composition, the viscosity decreasing effect is large and the response speed is remarkably improved, but the tilt angle tends to be largely decreased. Also, when the carbon number is 13 or more, the viscosity itself becomes large, and when added to the antiferroelectric liquid crystal or the antiferroelectric liquid crystal composition, the addition effect on the response speed becomes small.

In the bicyclic phenyl ester compound of the general formula (1), a compound having R ² of 2 to 12 carbon atoms is preferable, and a compound having a smectic A phase is more preferable. The effect of fluorine substitution of the phenyl group is not so dramatic, but in particular, the compound in which Y ² is an F atom and X ¹ , X ² and Y ^{1 are} all H atoms has a higher response speed than the unsubstituted compound. The effect on improvement is great.

The present invention provides an antiferroelectric liquid crystal composition prepared by mixing at least one bicyclic phenyl ester compound represented by the general formula (1) with an antiferroelectric liquid crystal or an antiferroelectric liquid crystal composition. Be implemented. The mixing ratio is selected so that the obtained antiferroelectric liquid crystal composition has an antiferroelectric phase in a temperature range of at least 0 ° C to 40 ° C, more preferably at least in a temperature range of -20 ° C to + 50 ° C. To do. It is difficult to uniquely determine the mixing ratio because the effect differs depending on the type of bicyclic phenyl ester compound or antiferroelectric liquid crystal selected, but it is difficult to determine the mixing ratio of the bicyclic system of general formula (1). The phenyl ester compound is added to the antiferroelectric liquid crystal or the antiferroelectric liquid crystal composition on a weight standard or a molar standard, and the amount of
It can be selected from 70%, preferably 5-60%, especially 10-50%. Further, in practice, it is preferable to use a composition having a smectic A phase on the high temperature side of this antiferroelectric phase. When it does not have a smectic A phase, the orientation is extremely poor and it is difficult to obtain high contrast.

The antiferroelectric liquid crystal in which the bicyclic phenyl ester compound of the general formula (1) of the present invention is mixed has the following general formula:
It is preferable to select from the antiferroelectric liquid crystal of (2).

Embedded image (R ^{3 in the} formula (2) is a linear alkyl group having 4 to 12 carbon atoms, R ⁴ is a linear alkyl group having 1 to 12 carbon atoms, Z is H or F, and A is CH ₃
Or CF ₃ and A is CH ₃ , s = 0 and R ⁴ has 3 carbon atoms.
Linear alkyl group of 10, when A is s = 0 in CF _3, R ⁴ is a linear alkyl group of 4 to 8 carbon atoms, when A is s = 1 at CF _3,
t is an integer of 5 to 8, R ⁴ is a linear alkyl having 1 to 6 carbons, and C * is an asymmetric carbon).

In the antiferroelectric liquid crystal of the general formula (2), R ³
It is preferable that the number of carbon atoms in 6 is 6-10. When the carbon number is 5 or less, the temperature range of the antiferroelectric phase is narrow and the tilt angle is extremely small, which is not suitable for practical use. Also, the carbon number
When it exceeds 10, the viscosity of itself becomes large, and it is necessary to mix a large amount of the bicyclic phenyl ester compound in order to improve the response speed, and other problems such as a decrease in tilt angle occur. In the antiferroelectric liquid crystal of general formula (2), A is CH ₃
When s = 0, an antiferroelectric liquid crystal in which R ⁴ has 4, 6 and 8 carbon atoms is preferable. Further, those having fluorine substitution of the phenyl group (Z in the general formula (2)) exhibit an antiferroelectric phase in a wider temperature range and are therefore preferable. When A is CF ₃ and s = 0, R ⁴ has 6 carbon atoms. When A is CF ₃ and s = 1, t = 5 and 7 and R ⁴ has 2 carbon atoms. Antiferroelectric liquid crystals are preferred.

The antiferroelectric liquid crystal composition of the present invention has an antiferroelectric phase in a wide temperature range and has an improved response speed, particularly an antiferroelectric state to a ferroelectric state. Therefore, the antiferroelectric liquid crystal display element can be suitably driven in a wide temperature range. That is, the anti-ferroelectric liquid crystal composition of the present invention is sandwiched between substrates on which scan electrodes and signal electrodes are arranged in a matrix, and a simple matrix liquid crystal display device is obtained. It is a simple matrix liquid crystal display device that is made by switching between two ferroelectric states.

As the optically active 2-alkanols used in the present invention, commercially available products can be used. In addition, the optically active 1,1,1-trifluoro-7-ethoxy-2-heptanol and 1,1,1-trifluoro-8-ethoxy-2-octanol are obtained by the method already disclosed by the present inventors ( JP 4-983
No.).

The production method of the bicyclic phenyl ester compound of the general formula (1) of the present invention is abbreviated as a reaction formula as follows. (1) R ¹ COCl + HO-Ph (F) -COOH → R ¹ COO-Ph (F) -COOH (2) (1) + SOCl ₂ → R ¹ COO-Ph (F) -COCl (3) AcO -Ph (F) -COOH + SOCl ₂ → AcO-Ph (F) -COCl (4) (3) + HOR ² → AcO-Ph (F) -COOR ² (5) (4) + (Ph-CH ₂ NH ₂ ) → HO-Ph (F) -COOR ² (6) (2) + (5) → target compound In the above, Ph (F), Ph (F) may be F-substituted at the 2 or 3 position. A good 1,4-phenylene group, AcO- is an acetyl group (CH ₃
COO-), R ¹ and R ² are the same as those in the above general formula (1).

The above manufacturing method will be briefly described below. (1) is the production of an ester (1) by reacting an aliphatic acid chloride with p-hydroxybenzoic acid whose nucleus may be optionally substituted with fluorine. (2) is the chlorination of ester (1) with thionyl chloride. (3) is the chlorination of acetoxybenzoic acid with thionyl chloride. (4) is the production of ester (4) by reacting the chloride of (3) with an alcohol. (5) is the deacetylation of ester (4) with benzylamine. (6) is the reaction of the chlorinated compound (2) with the deacetylated product (5).

The antiferroelectric liquid crystal (general formula (2)) used in the present invention is manufactured by the following method. (a) AcO-Ph (F) -COOH + SOCl ₂ → AcO-Ph (F) -COCl (b) (1) + HOC * HAR ⁴ → AcO-Ph (F) -COO-C * HAR ⁴ (c ) (2) + (PhCH ₂ NH ₂ ) → HO-Ph (F) -COO-C * HAR ⁴ (d) R ³ O-Ph-Ph-COOH + SOCl ₂ → R ³ O-Ph-Ph-COCl (e) (3) + (4) → antiferroelectric liquid crystal In the above, AcO- may be a CH ₃ COO- group, and Ph (F) may be F-substituted at the 3-position (Z in formula (2)). = H or F) 1,4-phenylene group, R ³ , R ⁴ and A each represent one corresponding to the above general formula (2), C * is an asymmetric carbon, Ph is a phenyl group or 1,
A 4-phenylene group is shown respectively.

The above manufacturing method will be briefly described below. (a) is a chlorination reaction of fluorine-substituted or unsubstituted p-acetoxybenzoic acid with thionyl chloride. (b) is esterification by the reaction of the chlorinated compound (a) with an optically active alcohol. (c) is the deacetylation of the ester of (b). (d) is a chlorination reaction of alkyloxybiphenylcarboxylic acid. (e) is the formation of liquid crystals by the reaction of the deacetylated product of the ester, phenol (c), and the chlorinated product (d).

[0028]

The present invention provides a novel bicyclic phenyl ester compound. When the novel bicyclic phenyl ester compound of the present invention is contained as one component of the antiferroelectric liquid crystal composition, it brings about a high response speed over a wide temperature range, while impairing other properties. Therefore, it is possible to realize an antiferroelectric liquid crystal display element having high display quality over a wide temperature range.

[0029]

Next, the present invention will be described more specifically with reference to examples and comparative examples, but the present invention is of course not limited thereto. Example 1 4-heptyloxycarbonylphenyl-2-fluoro-4-
n-Decanoyloxybenzoate (Formula (1): R ¹ = C ₉ H ₁₉ , X
² = F, X ¹ ,, Y ^1,2 = H, R ² = C ₇ H ₁₅ (E1))

(1) Preparation of 4-decanoyloxy-2-fluorobenzoic acid 15.6 g (0.1 mol) of 4-hydroxy-2-fluorobenzoic acid was dissolved in 140 ml (ml) of dichloromethane. Triethylamine 16 ml, n-decanoic acid chloride 0.1 g (0.11
Mol) and dimethiaminopyridine 0.97 g (0.0079 mol)
Were sequentially added, and the mixture was stirred at room temperature for one day. 10% hydrochloric acid 5
0 ml was added, and the mixture was extracted 3 times with 100 ml of ether. The organic layer was washed 3 times with 100 ml of saline and then dried over anhydrous sodium sulfate. After the solvent was distilled off, the residue was washed with 400 ml of hexane to obtain 25.5 g of the desired product.

(2) Preparation of 4-acetoxy-1-heptyloxycarbonylbenzene 3.5 g of 4-acetoxybenzoic acid was added to 25 ml of thionyl chloride and reacted under reflux for 10 hours. Next, distill off excess thionyl chloride, and then use 10 ml of pyridine and 50 ml of toluene.
Then, 1.5 g of n-heptanol was added dropwise thereto. After dropping, the mixture was heated under reflux for 4 hours and allowed to cool, then dichloromethane 5
The mixture was diluted with 00 ml, and the organic layer was washed with diluted hydrochloric acid, 1N aqueous sodium hydroxide solution and water in this order, and dried over magnesium sulfate.
Further, the solvent was distilled off to obtain 1.7 g of a crude target product.

(3) Production of 4-hydroxy-1-heptyloxycarbonylbenzene 1.7 g of the crude product obtained in (2) was dissolved in 50 ml of ethanol, and 4 g of benzylamine was added dropwise. After further stirring at room temperature for 4 hours, the mixture was diluted with 500 ml of chloroform, washed with diluted hydrochloric acid and water in this order, and dried with magnesium sulfate. After evaporating the solvent, the residue was isolated and purified by silica gel column chromatography to obtain 0.9 g of the desired product.

(4) Preparation of 4-heptyloxycarbonylphenyl-2-fluoro-4-n-decanoyloxybenzoate 0.5 g (0.0017 mol) of 4-decanoyloxybenzoic acid obtained in (1) was added to thionyl chloride. 10 ml was added and the mixture was heated under reflux for 4 hours. Thionyl chloride was distilled off and the obtained acid chloride 0.5
2 g was dissolved in toluene. There, 0.35 g of 4-hydroxy-1-heptyloxycarbonylbenzene obtained in (3) (0.
[0015 mol) and 0.27 g (0.0034 mol) of pyridine were sequentially added, and the mixture was stirred at room temperature for 24 hours. Add 10 ml of water to this and add 30
After stirring for 1 minute, 20 ml of 1N hydrochloric acid was added, and the mixture was extracted twice with 20 ml of dichloromethane. The organic layer was washed with 20 ml of water and then dried over anhydrous sodium sulfate. The solvent was distilled off and the crude product 0.60 g
I got This crude product was purified by column chromatography using silica gel to obtain the desired product (hereinafter referred to as E1)
0.43 g was obtained.

Example 2 3-Fluoro-4-heptyloxycarbonylphenyl-4-
n-Decanoyloxybenzoate (Formula (1): R ¹ = C ₉ H ₁₉ , Y
² = F, X ^1,2 , Y ¹ = H, R ² = C ₇ H ₁₅ (E2)) In Example 1, 4-hydroxy-2-fluorobenzoic acid,
A target product (hereinafter referred to as E2) was obtained in exactly the same manner as in Example 1 except that 4-hydroxybenzoic acid and 2-fluoro-4-benzyloxybenzoic acid were used instead of p-benzyloxybenzoic acid. It was

Examples 3 to 7 3-Fluoro-4-undecyloxycarbonylphenyl-
4-n-decanoyloxybenzoate (Formula (1): R ¹ = C ₉ H ₁₉ ,
Y ² = F, X ^1,2 , Y ¹ = H, R ² = C ₁₁ H ₂₃ (E3)), 3-fluoro-4-
Nonyloxycarbonylphenyl-4-n-decanoyloxybenzoate (Formula (1): R ¹ = C ₉ H ₁₉ , Y ² = F, X ^1,2 , Y ¹ = H,
R ² = C ₉ H ₁₉ (E4)), 3-fluoro-4-propyloxycarbonylphenyl-4-n-decanoyloxybenzoate
(Equation (1): R ¹ = C ₉ H ₁₉ ,, Y ² = F, X ^1,2 , Y ¹ = H, R ² = C ₃ H ₇ (E
5)), 4-nonyloxycarbonylphenyl-2-fluoro-4-n-decanoyloxybenzoate (Formula (1): R ¹ = C ₉ H
₁₉ , X ² = F, X ¹ , Y ^1,2 = H, R ² = C ₉ H ₁₉ (E6)), 4-nonyloxycarbonylphenyl-4-n-decanoyloxybenzoate (formula (1): Production of R ¹ = C ₉ H ₁₉ , X ¹ -Y ² = H, R ² = C ₉ H ₁₉ (E7)). According to Example 1, the above compound (E3-7) was synthesized.

The chemical formulas of the target compounds obtained in Examples 1 to 7 are shown below, and their NMR data and the results of identifying the liquid crystal phase are shown in Table 1. The numbers given to the hydrogen atoms in the chemical formula correspond to the hydrogen atom numbers in the NMR data in Table 1.

[0037]

[Table 1] Hydrogen atomic number (ppm) phase series of formula 1 2 3 4 5 6 7 Example 1 (E1) 2.6 7 7 8.2 7.3 8.1 4.4 I (61) SA (33) Cr Example 2 (E2) 2.6 7.2 8.2 7.1 7.1 8 4.4 I (71) SA (37) Cr Example 3 (E3) 2.6 7.3 8.2 7.1 7.1 8 4.4 I (70) SA (37) Cr Example 4 (E4) 2.6 7.3 8.2 7.1 7.1 8 4.4 I (71) SA (37) Cr Example 5 (E5) 2.6 7.3 8.2 7.1 7.1 8 4.4 I (77) SA (44) Cr Example 6 (E6) 2.6 7.0 7.0 8.2 7.3 8.1 4.4 I (68) SA (42) Cr Example 7 (E7) 2.6 7.3 8.3 7.3 8.1 4.4 − I (77) SA (37) Cr

[0038]

Embedded image

Examples 8 to 14 Bicyclic phenyl ester compounds (E1 obtained in Examples 1 to 7)
~ E7) to E1, the antiferroelectric liquid crystal AF1
Anti-ferroelectric liquid crystal compositions were prepared by mixing E3 to E7 in an amount of 30 mol% and E2 in an amount of 35 mol%, and the phase series and response speed were measured. The results are shown in Tables 2 and 3. AF1: nC ₉ H ₁₉ -O-Ph-Ph-COO-Ph (3F) -COO-C * H (CF ₃ ) (C
H ₂ ) ₅ OC ₂ H _{5 In the} formula, Ph is a 1,4-phenylene group, and Ph (3F) is F-substituted at the 3-position.
(Z = F in the formula (2)) 1,4-phenylene group, C * is an asymmetric carbon.

The measurement of physical properties and the like were performed as follows. The phase was identified by texturer observation and DSC (differential differential scanning calorimeter) measurement. The response speed is the liquid crystal cell with ITO electrodes (rubbing processed polyimide thin film) (cell thickness 1.8μ
m) was filled in the isotropic phase. 1 cell per minute
The liquid crystal was aligned in the SA phase by slowly cooling at ℃. The cell was placed between orthogonal polarizing plates so that the layer direction of the liquid crystal was parallel to the analyzer or the polarizer. The response time was defined by defining the time required for the change in transmitted light from 10 to 90% by applying a step voltage of 35 V at a frequency of 10 Hz to the liquid crystal cell, and measuring the response speed.

[0041]

[Table 2] Phase system Ingredients Molar ratio Liquid crystal AF1 I (83) SC * (77) SCA * (<-50) Cr Actual 8 I (85) SA (71) SC * (65) SCA * (<-20 ) Cr AF1 / E1 = 70/30 Actual 9 I (84) SA (73) SC * (65) SCA * (<-20) Cr AF1 / E2 = 65/35 Actual 10 I (79) SA (59) SCA * (<-20) Cr AF1 / E3 = 70/30 Actual 11 I (81) SA (62) SCA * (<-20) Cr AF1 / E4 = 70/30 Actual 12 I (82) SA (70) SCA * (<-20) Cr AF1 / E5 = 70/30 Actual 13 I (82) SA (72) SCA * (<-20) Cr AF1 / E6 = 70/30 Actual 14 I (86) SA (70) SCA * (<-20) Cr AF1 / E7 = 70/30 The value in parentheses in Table 2 indicates the temperature (° C) of the phase transition. In addition, I: isotropic phase, SA: smectic A phase, SC *: chiral smectic C phase (ferroelectric phase), SCA *: antiferroelectric smectic C phase, Cr: crystalline phase, respectively.

[0042]

[Table 3] Response speed I: Switching time from antiferroelectric state to ferroelectric state (unit, μsec) Response speed II: Switching time from ferroelectric state to antiferroelectric state (unit, μsec)

As is clear from Tables 2 and 3, liquid crystal AF1 does not have a smectic A phase, but a composition having a smectic A phase was obtained by mixing a bicyclic phenyl ester compound. The antiferroelectric phase was maintained over a wide temperature range, and the response time I at 10 ℃ was also improved.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Maki Ito 22, Wadai, Tsukuba, Ibaraki Pref.

Claims (15)

[Claims] 1. A bicyclic phenyl ester compound represented by the following general formula (1): Embedded image (In the formula, R ¹ is a straight-chain alkyl group having 5 to 12 carbon atoms, R ² is a straight-chain alkyl group having 1 to 15 carbon atoms, X ¹ and X ² are H or either F, Y ¹ or Y. ² is H or one of them is F). 2. The bicyclic phenyl ester compound according to claim ¹ , wherein R ¹ of the general formula (1) has 8 to 12 carbon atoms. 3. The bicyclic phenyl ester compound according to claim 1, wherein R ² of the general formula (1) has 2 to 12 carbon atoms. 4. The bicyclic phenyl ester compound according to claim 3, wherein the bicyclic phenyl ester compound represented by the general formula (1) has a smectic A phase. 5. A compound represented by the general formula (1) according to claim 1,
An antiferroelectric liquid crystal composition containing at least one ring-type phenyl ester compound in an antiferroelectric liquid crystal or an antiferroelectric liquid crystal composition. 6. The antiferroelectric liquid crystal composition is at least
The antiferroelectric liquid crystal composition according to claim 5, which has an antiferroelectric phase in the temperature range of 0 to 40 ° C. 7. The antiferroelectric liquid crystal composition according to claim 5, wherein the antiferroelectric liquid crystal composition has at least a smectic A phase on the high temperature side of the antiferroelectric phase. 8. The antiferroelectric liquid crystal composition according to claim 5, wherein the antiferroelectric liquid crystal is represented by the following general formula (2). Embedded image (R ^{3 in the} formula (2) is a linear alkyl group having 4 to 12 carbon atoms, R ⁴ is a linear alkyl group having 1 to 12 carbon atoms, Z is H or F, and A is CH ₃
Or CF ₃ and A is CH ₃ , s = 0 and R ⁴ has 3 carbon atoms.
Linear alkyl group of 10, when A is s = 0 in CF _3, R ⁴ is a linear alkyl group of 4 to 8 carbon atoms, when A is s = 1 at CF _3,
t is an integer of 5 to 8, R ⁴ is a linear alkyl having 1 to 6 carbons, and C * is an asymmetric carbon). 9. The antiferroelectric liquid crystal composition according to claim 8, wherein R ^{3 in} the general formula (2) has 6 to 10 carbon atoms. 10. The antiferroelectric liquid crystal composition according to claim 8, wherein when A of the general formula (2) is CH ₃ and s = 0, the carbon number of R ⁴ is 4,6,8. 11. The antiferroelectric liquid crystal composition according to claim 8, wherein when A in the general formula (2) is CF ₃ and s = 0, the carbon number of R ⁴ is 6. 12. The antiferroelectric liquid crystal composition according to claim 8, wherein when A in the general formula (2) is CF ₃ and s = 1, t = 5, 7 and R ⁴ has 2 carbon atoms. . 13. The antiferroelectric liquid crystal composition has an antiferroelectric phase in a temperature range of at least 0 to 40 ° C., and has at least a smectic A phase on the high temperature side of the antiferroelectric phase. The antiferroelectric liquid crystal composition according to claim 8. 14. A simple matrix liquid crystal display device comprising the antiferroelectric liquid crystal composition according to claim 7 sandwiched between substrates in which scanning electrodes and signal electrodes are arranged in a matrix. 15. The simple matrix liquid crystal display according to claim 14, wherein the simple matrix liquid crystal display device is driven by a voltage by switching between one antiferroelectric state and two ferroelectric states. element.