JP3255180B2 - Fluorine-substituted liquid crystal material - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a novel antiferroelectric liquid crystal material.

[0002]

2. Description of the Related Art Liquid crystal display devices have been used in various small display devices to date because of their low voltage operation, low power consumption, and thin display. However, with the recent information, the application of liquid crystal display elements to the OA related equipment field, or the television field, and the expansion of applications, the CR
The demand for a high-performance large-sized liquid crystal display device having a display capacity and display quality higher than that of a T display device has been rapidly increasing. However, as long as the current nematic liquid crystal is used, it is not easy to increase the size and cost of the active matrix drive liquid crystal display element used for liquid crystal televisions due to the complexity of the manufacturing process and low yield. Absent. Even with a simple matrix driven STN type liquid crystal display element, large capacity driving is not always easy, and the response time is limited, making it difficult to display moving images. 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.

[0003]

In such a situation, a liquid crystal display device using a ferroelectric liquid crystal material has attracted attention as a high-speed liquid crystal display device. It has been noted that the surface-stabilized ferroelectric liquid crystal (SSFLC) device disclosed by Clark and Lagall has an unprecedented fast response speed and a wide viewing angle, and its switching characteristics are described in detail. Many ferroelectric liquid crystal materials have been manufactured to optimize various physical property constants. However, the threshold characteristics are insufficient, the contrast is poor due to the liquid crystal layer structure having a chevron structure, the high-speed response is not realized, the alignment control of the liquid crystal molecules is difficult, and the maximum of SSFLC is obtained. Due to various factors such as difficulty in realizing bistability, which is one of the features, and the destruction of liquid crystal molecules caused by mechanical shock, and the difficulty in recovering the orientation, it has not been put to practical use. Is the actual situation.

[0004] Apart from this, the development of elements having a switching mechanism different from that of SSFLC is also proceeding at the same time. 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 Applied Physics, Vol. 27, pp. L729, 1988). Antiferroelectric liquid crystal devices (devices using antiferroelectric liquid crystal materials)
Has three stable states. That is, two uniform states (Ur, Ur) seen in the conventional ferroelectric liquid crystal element.
There is another stable third state besides Ul). Chandani et al. Report that this third state is an antiferroelectric phase (Japanese Journal of Applied Physics, Vol. 2
8, pp.L1261, 1989, Japanese Journal of Applied Ph
ysics, 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. Further, it has a memory property, which is the third of the antiferroelectric liquid crystal element.
It is a feature of. By utilizing these excellent features, a liquid crystal display device having a high response speed and good contrast can be realized. Another major feature is that the liquid crystal layer structure is easily switched by an electric field (Japanese Journal of Applied Physics, Vol.2).
8, pp.L119,1989, Japanese Journal of Applied Physi
cs, Vol.29, pp.L111, 1990). This makes it possible to manufacture a liquid crystal display device having extremely few defects and capable of self-healing the orientation, thereby realizing a liquid crystal display device having excellent contrast. An antiferroelectric liquid crystal material that can be used for an element having such excellent performance is disclosed in JP-A-1-213.
390, JP-A-1-316339, JP-A-1-3163
67, JP-A-1-316372, JP-A-2-28128
And Liquid Crystals, Vol. 6, pp. 167, (198
Those described in 9) are known. Due to the short history of research on antiferroelectric liquid crystal materials, the number of antiferroelectric liquid crystal materials known to date is not large compared to ferroelectric liquid crystal materials, but as research progresses, Its number is increasing.

[0005] Many antiferroelectric liquid crystal materials that have been manufactured to date have a melting point that is too high from a practical point of view, and the temperature range of the antiferroelectric phase is much higher than near room temperature. Therefore, it is difficult to put a single liquid crystal material into practical use, and for practical use, a mixture of several or more kinds of liquid crystal materials is required to balance physical properties like other liquid crystal devices. It is desirable that the liquid crystal substance used in such a mixture has properties such that the melting point is as low as possible, the temperature range of the antiferroelectric phase is wide, and the temperature range is as close to room temperature as possible. The present invention has been made under such a demand and provides a novel antiferroelectric liquid crystal material having a low melting point and an extremely wide temperature range of an antiferroelectric phase.

[0006]

According to the present invention, there is provided a compound represented by the following general formula (1):

[0007]

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Wherein R is an aliphatic straight-chain alkyl group having 6 to 14 carbon atoms, X is CH ₃ or CF ₃ , and X is C 3
When H ₃ , L is 0, m is 0, n is 8, and X is CF ₃
In this case, L is 5, m is 1, and n is 2. ) Is a novel antiferroelectric liquid crystal material. An example of the method for producing the antiferroelectric liquid crystal material of the present invention is represented by the following reaction formula.

[0009]

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[0010] The 4-
Acetoxy-2-fluorobenzoic acid can be produced, for example, by using m-fluorophenol as a starting material by the following method.

[0011]

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[0012]

According to the present invention, a novel antiferroelectric liquid crystal material can be provided. The novel antiferroelectric liquid crystal material provided by the present invention has a low melting point, a wide temperature range of an antiferroelectric phase, and provides a liquid crystal display device having a high-speed response alone or in a composition. Can be used.

[0013]

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 3-Fluoro-4- (1-methylnonyloxycarbonylphenyl) 4'-octyloxybiphenyl-4-carboxylate [In the general formula (1), R = nC ₈ H ₁₇ , X = CH ₃ ,
L = 0, m = 0, n = 8)

1) Production of 4- (4'-n-octyloxy) biphenylcarboxylic acid (1)

[0016]

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10.5 g of 4- (4'-hydroxy) biphenylcarboxylic acid, 14.0 n-octyl bromide
g, 6.5 g of potassium hydroxide in 1500 m of ethanol.
1 and water (200 ml) and reacted under reflux for 10 hours. Further, 500 ml of water was added and stirred for 3 hours. After the completion of the reaction, concentrated hydrochloric acid was added to make the mixture acidic.
0 ml was distilled off and cooled to room temperature to obtain a white solid. This was sufficiently washed with water and then recrystallized from chloroform to obtain 12.0 g of the desired product (1) as white crystals.

2) Preparation of 4-acetoxy-2-fluorobenzoic acid (2)

[0019]

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2-fluoro-4-hydroxybenzoic acid 4
g and 8 g of acetic anhydride were placed in a two-neck flask and mixed. Five drops of sulfuric acid were added under water cooling. After the exotherm subsided, the mixture was heated at 80 ° C for 30 minutes. Then the reaction mixture is poured into cold water,
The precipitated crystals were filtered. The crystals were dried in a vacuum and used in the next step. The yield was 4.2 g.

3) 4-acetoxy-2-fluoro-1-
(1-methylnonyloxycarbonyl) benzene (3)
Manufacturing of

[0022]

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1.2 g of 4-acetoxy-2-fluorobenzoic acid was added to 20 ml of thionyl chloride and reacted under reflux for 5 hours. Next, after removing excess thionyl chloride, 3 ml of pyridine, 20 ml of toluene, R-(-)-
A mixture of 0.6 g of 2-decanol was added dropwise. 1 after dripping
The mixture was stirred day and night at room temperature, diluted with 50 ml of dichloromethane, and the organic layer was washed with diluted hydrochloric acid, a 1N aqueous solution of sodium hydroxide and water in that order, and dried over sodium sulfate. The solvent is distilled off, and the crude target product is purified by silica gel column chromatography using hexane / ethyl acetate as a solvent (3).
1.3 g was obtained.

4) 2-fluoro-4-hydroxy- (1
-Methylnonyloxycarbonyl) benzene (4)

[0025]

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1.3 g of the above compound (3) was added to ethanol
And benzylamine (0.8 g) was added dropwise. After stirring at room temperature for one day, the mixture was diluted with 50 ml of dichloromethane, washed with diluted hydrochloric acid and water in that order, and dried over sodium sulfate. After evaporating the solvent, the residue was isolated and purified by silica gel column chromatography to obtain 1.0 g of the desired product (4).

5) Preparation of 3-fluoro-4- (1-methylnonyloxycarbonylphenyl) -4'-n-octyloxybiphenyl-4-carboxylate (5)

[0028]

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To 0.9 g of the compound (1), 10 ml of thionyl chloride was added, and the mixture was heated under reflux for 5 hours. After distilling off excess thionyl chloride, 2 ml of pyridine and 15 ml of toluene
After adding l, 0.6 g of the above compound (4) was added dropwise,
The reaction was carried out at room temperature overnight. After completion of the reaction, the reaction mixture was diluted with 50 ml of dichloromethane, washed with diluted hydrochloric acid, a 1N aqueous solution of sodium carbonate and water in that order, and the organic layer was dried over sodium sulfate. Next, after the solvent was distilled off, the residue was isolated by silica gel chromatography to obtain 1.1 g of the desired product (5). FIG. 1 shows the NMR spectrum of the target product (5). The phases were identified by texture observation and DSC measurement. The melting point was measured by DSC, and the value was 36 ° C. The phase sequence of this liquid crystal material (5) was as follows. In this liquid crystal material, an antiferroelectric phase was observed. 23 ° C 115 ° C 117 ° C 135 ° C Crystal ← SX ← SCA * ← SC * ← SA ← Isotropic phase SA is a smectic A phase, SC * is a chiral smectic C phase, SCA * is an antiferroelectric phase, and SX is It shows an unidentified smectic phase.

6) A liquid crystal cell (cell thickness: 3 μm) having an ITO electrode and having a rubbed polyimide thin film was filled with the liquid crystal substance (5) in an isotropic phase. The cell was gradually cooled at 1.0 ° C./min to align the liquid crystal in the SA phase. The cell is placed between the orthogonal polarizing plates so that the liquid crystal layer direction is parallel to the analyzer or the polarizer, and a ± 40 V, 0.2 Hz triangular wave voltage is applied to the cell, and the change in the amount of transmitted light is measured by photomultiplier. It was measured with a pliers. As a result, a response history of double hysteresis peculiar to the antiferroelectric phase was observed in a temperature range of 115 ° C. to 25 ° C. FIG. 2 shows the optical response history of this liquid crystal material (5) at 40 ° C. As described above, the antiferroelectric liquid crystal material (5) obtained in Example 1 had a low melting point and exhibited antiferroelectricity over a wide range including around room temperature, although it was partially supercooled.

Comparative Example 1 4- (1-methylnonyloxycarbonylphenyl)
Production of 4'-octyloxybiphenyl-4-carboxylate

4- (1-methylnonyloxycarbonylphenyl) 4'-octyloxy was prepared in the same manner as in Example 1 except that 4-acetoxy-2-fluorobenzoic acid was used in place of 4-acetoxy-2-fluorobenzoic acid. Biphenyl-4-carboxylate was prepared. FIG. 3 shows the NMR spectrum of the target product. The phases were identified by texture observation and DSC measurement. Melting point measurement is D
Performed by SC. The phase sequence of this liquid crystal material was as follows. In this liquid crystal material, an antiferroelectric phase was recognized, and the phase sequence was as follows. The melting point was 67 ° C. 32 ℃ 65 ℃ 112 ℃ 114 ℃ 142 ℃ Crystal ← SX ← SCA * ← SC * ← SA ← Isotropic Phase

Example 2 3-Fluoro-4- (1-methylnonyloxycarbonylphenyl) 4'-heptyloxybiphenyl-4-carboxylate [In the general formula (1), R = nC ₇ H ₁₅ , X = CH ₃ ,
L = O, m = 0, n = 8)

The procedure of Example 1 was repeated, except that n-heptylbromide was used instead of n-octylbromide, to give 3-fluoro-4- (1-methylnonyloxycarbonylphenyl) 4'-he Petroxybiphenyl-4-carboxylate was prepared. FIG. 4 shows the NMR spectrum of the target product. The phases were identified by texture observation and DSC measurement. The melting point was measured by DSC. The phase sequence of this liquid crystal material was as follows. In this liquid crystal material, an antiferroelectric phase was recognized, and the phase sequence was as follows. The melting point was 70 ° C. The liquid crystal material of Example 1 was obtained because R was C ₇ H _15.
However, the temperature range of the antiferroelectric phase was expanded.

Example 3 3-Fluoro-4- (1-trifluoromethyl-6-ethoxyhexyloxycarbonylphenyl) 4'-octyloxybiphenyl-4-carboxylate [In the general formula (1), R = nC ₈ H ₁₇ , X = CF ₃ , L = 5, m = 1, n = 2)
Manufacturing of

Example 1 was repeated using R-(-)-1,1,1, -trifluoromethyl-7-ethoxy-2-heptanol instead of R-(-)-2-decanol in Example 1. 3-Fluoro-4- (1-trifluoromethyl-6-ethoxyhexyloxycarbonylphenyl) 4'-octyloxybiphenyl-4-carboxylate was produced in exactly the same manner. FIG. 5 shows the NMR spectrum of the obtained liquid crystal substance. The phases were identified by texture observation and DSC measurement. Melting point measurement is D
Performed by SC. The phase sequence of this liquid crystal material was as follows. In this liquid crystal material, an antiferroelectric phase was recognized, and the phase sequence was as follows. The melting point was 82 ° C. 25 ℃ 88.6 ℃ 89 ℃ Crystal ← SX ← SCA * ← SA ← Isotropic Phase Some of the antiferroelectric phase of this liquid crystal material was in a supercooled state, but the antiferroelectric phase exists in a wide temperature range including room temperature. did.

Comparative Example 2 Preparation of 4- (1-trifluoromethyl-6-ethoxyhexyloxycarbonylphenyl) 4'-octyloxybiphenyl-4-carboxylate

The procedure of Example 3 was repeated, except that 4-acetoxybenzoic acid was used instead of 4-acetoxy-2-fluorobenzoic acid, to give 4- (1-trifluoromethyl-7-ethoxyhexyl). (Oxycarbonylphenyl) 4'-octyloxybiphenyl-4-carboxylate was prepared. FIG. 6 shows the NMR spectrum of the obtained liquid crystal substance. The phases were identified by texture observation and DSC measurement. The melting point was measured by DSC. The phase sequence of this liquid crystal material was as follows. In this liquid crystal material, an antiferroelectric phase was recognized, and the phase sequence was as follows. The melting point was 59 ° C.

Example 4 3-Fluoro-4- (1-trifluoromethyl-8-ethoxyoctyloxycarbonylphenyl) ^4' -octyloxybiphenyl-4-carboxylate [In the general formula (1), R = nC ₈ H ₁₇ , X = CF ₃ , L = 7, m = 1, n = 2)
Manufacturing of

R-(-)-1,1,
Exactly the same as Example 1 using R-(-)-1,1,1, -trifluoromethyl-9-ethoxy-2-nonanol instead of 1, -trifluoromethyl-7-ethoxy-2-heptanol To give 3-fluoro-4- (1-trifluoromethyl-8-ethoxyoctyloxycarbonylphenyl) ^4' -octyloxybiphenyl-4-carboxylate. FIG. 7 shows the NMR spectrum of the obtained compound. The phase was identified by texture observation and DSC measurement. Melting point measurement is DS
C. The phase sequence of this liquid crystal material was as follows. In this liquid crystal material, an antiferroelectric phase was observed. The melting point was 86 ° C.

In place of 4- (4'-n-octyloxy) biphenylcarboxylic acid in Example 3 , 4- (4'-
n-hexyloxy) biphenylcarboxylic acid (Example 5), 4- (4'-n-nonyloxy) biphenylcarboxylic acid (Example 6), 4- (4'-n-decyloxy)
Biphenylcarboxylic acid (Example 7), 4- (4'-n-
In the general formula (1), R = n-C ₆ H ₁₃ , n-C ₉ H ₁₉ , n-C in the same manner as in Example 3 using (tetradecyloxy) biphenylcarboxylic acid (Example 8).
₁₀ H _21, to prepare a liquid crystal material of n-C ₁₄ H _23. The NMR spectra of these liquid crystal substances are shown in FIGS. Further, the phase series of these liquid crystal substances was determined in the same manner as in Example 3 . The results are shown in Table 1. The melting points of the liquid crystal materials were 55 ° C., unknown, 26 ° C., and 60 ° C.

[0042]

[Table 1] Phase series in Examples 5 to 8  Example R-phase sequencenumber 4 ℃ 7 ℃ 100 ℃ 104 ℃ 5 nC₆H₁₃ Crystal ← SX ← SCA * ← SA ← Isotropic phase  ? 82 ℃ 83 ℃ 6 nC₉H₁₉ Crystal ← SCA * ← SA ← Isotropic phase  -6 ℃ 80 ℃ 7 nC_TenH_{twenty one} Crystal ← SCA * ← Isotropic phase  21 ℃ 70 ℃ 8 nC₁₄H₂₉ Crystal ← SCA * ← Isotropic phase

[Brief description of the drawings]

FIG. 1 is a diagram showing N of the liquid crystal substance (5) obtained in Example 1.
It is a figure showing an MR spectrum.

FIG. 2 is a diagram showing an optical response history of a liquid crystal material (5) obtained in Example 1.

FIG. 3 is a view showing an NMR spectrum of the liquid crystal substance obtained in Comparative Example 1.

FIG. 4 is a diagram showing an NMR spectrum of the liquid crystal substance obtained in Example 2.

FIG. 5 is a diagram showing an NMR spectrum of the liquid crystal substance obtained in Example 3.

FIG. 6 is a diagram showing an NMR spectrum of the liquid crystal substance obtained in Comparative Example 2.

FIG. 7 is a diagram showing an NMR spectrum of the liquid crystal substance obtained in Example 4.

FIG. 8 is a diagram showing an NMR spectrum of the liquid crystal substance obtained in Example 5.

FIG. 9 is a diagram showing an NMR spectrum of the liquid crystal substance obtained in Example 6.

FIG. 10 shows the NM of the liquid crystal substance obtained in Example 7.
It is a figure showing an R spectrum.

FIG. 11 shows the NM of the liquid crystal substance obtained in Example 8.
It is a figure showing an R spectrum.

──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-3-123759 (JP, A) JP-A-61-210056 (JP, A) JP-A-1-261493 (JP, A) JP-A 63-123 27590 (JP, A) European Patent Application Publication 422996 (EP, A2) (58) Fields investigated (Int. Cl. ⁷ , DB name) C07C 69/94 C09K 19/20 CA (STN) REGISTRY (STN)

Claims (1)

(57) [Claims] 1. The following general formula (1): (Wherein, R is an aliphatic linear alkyl group having 6 to 14 carbon atoms,
X is CH ₃ or CF ₃ , and when X is CH ₃ , L
Is 0, m is 0, n is 8. When X is CF ₃ , L is 5, m is 1, and n is 2. A novel antiferroelectric liquid crystal material represented by).