JPH1112570A - Antiferroelectric liquid crystal composition having high speed of response and low spontaneous polarization - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject composition exhibiting an antiferroelectric phase in a wide temperature range, having a high speed of response, capable of reducing the intensity of spontaneous polarization by using an antiferroelectric liquid crystal compound having a widened temperature range at a high-temperature side as a component. SOLUTION: This composition preferably contains at least one antiferroelectric liquid crystal compound of the formula [R<1> is a 6-16C alkyl or an alkenyl containing a double bond at the terminal of the formula; CH2 = CH-(CH2 )m ((m) is 4-12); R<2> is a 2-8C alkyl; A<1> to A<3> are each independently a single bond, COO or COS; X<1> to X<4> are each independently H or F; Y is a single bond or an ether bond; * is an asymmetric carbon] having a phase transition temperature changing from an antiferroelectric liquid crystal phase to a ferroelectric liquid crystal phase (or containing a smectic A, a liquid crystal phase at a higher temperature side) at >=50 deg.C and <=120 deg.C in a process of heating, <=130 nC/cm<2> intensity of spontaneous polarization from the phase transition temperature to a low temperature side of 30 deg.C and <=10 μs speed of response.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an antiferroelectric liquid crystal compound exhibiting stable antiferroelectricity at around room temperature and having excellent temperature dependence of response speed which is an indispensable characteristic for display display.

[0002]

2. Description of the Related Art Liquid crystal display devices are 1) low-voltage operable 2).
Since it has excellent features such as low power consumption, 3) thin display, and 4) light receiving type, TN method, STN method,
A guest-host method has been developed and put into practical use. However, those using a nematic liquid crystal which is widely used at present have a response speed of several milliseconds.
It has a drawback as slow as c to several tens of msec, and is subject to various restrictions in application.

In order to solve these problems, the STN method and the active matrix method using thin-layer transistors have been developed. However, the STN type display element has excellent display quality such as display contrast and viewing angle. However, there is a problem that high accuracy is required for controlling the cell gap and the tilt angle, and that the response is slightly slow.

[0004] For this reason, there is a demand for the development of a new liquid crystal display system having excellent responsiveness, and the optical response time is μs
Attempts have been made to develop ferroelectric liquid crystals capable of realizing ultra-high-speed devices as short as c-orders.

[0005] Ferroelectric liquid crystals were introduced in 1975 by Meyer.
DOBMMBC (p-decyloxybenzylidene-p-amino-2-methylbutylcinnamate) was synthesized for the first time (Le Journal de Phys).
sque, 36, 1975, L-69).

Further, in 1980, Clark and Lag
Ferroelectric liquid crystals have attracted a great deal of attention since the reporting of characteristics on display devices such as the fast response time of DOBAMBC in sub-microseconds and memory characteristics by AWall [N. A. Clark, et al. , Appl.
Phys. Lett. 36.899 (1980)].

However, their method has many technical problems for practical use. In particular, there is no material showing a ferroelectric liquid crystal at room temperature, and it is effective for controlling the alignment of liquid crystal molecules indispensable for a display. No practical method has been established.

[0008] Since this report, various attempts have been made from both sides of the liquid crystal material / device, and a display device utilizing switching between two twisted states has been experimentally manufactured. No. 107216, but high contrast and proper threshold characteristics have not been obtained.

From such a viewpoint, other switching schemes have been searched, and a transient scattering scheme has been proposed.
Then, in 1988, the present inventors reported a three-state switching method of a liquid crystal having a tristable state [A.
D. L. Chandani, T .; Hagiwara,
Y. Suzuki et al. , Japan. J. of
Appl. Phys. , 27, (5), L729-L7
32 (1988)].

The above-mentioned "having three states" refers to a liquid crystal electro-optical device in which a ferroelectric liquid crystal is sandwiched between a first electrode substrate and a second electrode substrate arranged at a predetermined gap. Wherein a voltage for forming an electric field is applied to the first and second electrode substrates, and when a voltage is applied as a triangular wave shown in FIG. 1A, the ferroelectric liquid crystal is applied as shown in FIG. 1D. Has a second stable state in which the molecular orientation has a first stable state (1 in FIG. 1D) when no electric field is applied, and the molecular orientation is different from the first stable state in one electric field direction when an electric field is applied. State (2 in FIG. 1D) and a third molecular orientation stable state (3 in FIG. 1D) different from the first and second stable states in the other electric field direction. The applicant of the present invention discloses a three-stable state, that is, a liquid crystal electro-optical device utilizing the three states.
No. 3-70212 and Japanese Patent Application Laid-Open No. Hei 2-15332.
Published as Issue 2.

The characteristics of the antiferroelectric liquid crystal exhibiting a tristable state will be described in more detail. Clark / Lagerval (C
In the surface-stabilized ferroelectric liquid crystal device proposed by L.Lark-Lagawall, two ferroelectric liquid crystal molecules are uniformly aligned in one direction in the S _* C phase as shown in FIGS. 2 (a) and 2 (b). A state is shown, and the state is stabilized to one of the states depending on the direction of the applied electric field, and the state is maintained even when the electric field is cut off.

However, in practice, the orientation state of the ferroelectric liquid crystal molecules shows a twisted two state in which the director of the liquid crystal molecules is twisted, or shows a Chevron structure in which the layer is bent in a square shape. In the case of the Chevron layer structure, the switching angle becomes small and causes a low contrast, which is a major obstacle for practical use. On the other hand, in the S _* (3) phase in which the “anti” ferroelectric liquid crystal exhibits a tristable state, in the above-mentioned liquid crystal electro-optical device, when there is no electric field, the molecules are reversed in each adjacent layer as shown in FIG. The dipoles of the liquid crystal molecules cancel each other. Therefore, the spontaneous polarization is canceled in the entire liquid crystal layer. The liquid crystal phase exhibiting this molecular arrangement corresponds to 1 in FIG. 1D.

Further, when a voltage sufficiently higher than the threshold value of (+) or (-) is applied, FIGS.
Are arranged in parallel in the same direction. In this state, the dipoles of the molecules are also aligned in the same direction, so that spontaneous polarization occurs and a ferroelectric phase is formed.

That is, in the S _* (3) phase of the “anti” ferroelectric liquid crystal, the “anti” ferroelectric phase in the absence of an electric field and the two ferroelectric phases depending on the polarity of the applied electric field become stable, and the “anti” ferroelectric phase becomes stable. "Switching between three stable states with a DC threshold value between a ferroelectric phase and two ferroelectric phases. Due to the change in the liquid crystal molecule arrangement accompanying the switching, the light transmittance changes in a double hysteresis shown in FIG. This double
As shown in FIG. 4A, a memory effect can be realized by applying a bias voltage to the hysteresis and further superimposing a pulse voltage.

Further, the layer of the ferroelectric phase is stretched by the application of an electric field, thereby forming a bookshelf structure. On the other hand, the "anti" ferroelectric phase in the third stable state has a similar bookshelf structure. Since the layer structure switching by the application of the electric field gives dynamic shear to the liquid crystal layer, alignment defects are improved during driving, and good molecular alignment can be realized. In the "anti-" ferroelectric liquid crystal, image display is performed using both the positive and negative hysteresis alternately, so that the afterimage phenomenon of an image due to accumulation of an internal electric field based on spontaneous polarization can be prevented.

As described above, the "anti" ferroelectric liquid crystal is
It can be said that this is a very useful liquid crystal compound capable of 1) high-speed response, 2) high contrast and a wide viewing angle, and 3) excellent alignment characteristics and a memory effect.

For the liquid crystal phase exhibiting the tristable state of the "anti" ferroelectric liquid crystal, 1) A. D. L. Chandani
et al., Japan J. et al. Appl. Phys., 2
8 , L-1265 (1989), 2) H.E. Orihar
a et al., JapanJ. Appl. Phys.,
29 , L-333 (1990);
Due to its "anti" ferroelectric properties, the S _* CA phase (Antive
rroelectric Sectic C _* phase). The present inventors have defined this liquid crystal phase as the S _* (3) phase because it switches between the three stable states.

Liquid crystal compounds having an "anti" ferroelectric phase S _* (3) exhibiting a tristable state in a phase series are disclosed in JP-A-1-316367, JP-A-1-316372 and JP-A-1-316372, filed by the present inventors. There are JP-A-1-316339, JP-A-2-28128 and JP-A-1-213390 such as Ichihashi. As a liquid crystal electro-optical device utilizing a tristable state, the applicant of the present invention is disclosed in JP-A-2-40625. Kaihei 2-153322
And Japanese Patent Application Laid-Open No. 2-173724.

When an "anti" ferroelectric liquid crystal is applied to a liquid crystal display, 1) operating temperature range, 2) response speed, 3).
It is difficult to satisfy all of spontaneous polarization and 4) hysteresis characteristics etc. with a single liquid crystal, and it is usually prepared as a dozen or more kinds of mixed liquid crystal.

At present, antiferroelectric liquid crystal compounds, which are generally known as antiferroelectric liquid crystal materials, have a large temperature dependence of response speed, and may cause defects such as display unevenness when displayed on a display. There is concern that there is.

Therefore, in order to put an antiferroelectric liquid crystal display panel into practical use, it is necessary to expand the temperature range in which the liquid crystal material exhibits an antiferroelectric phase and reduce spontaneous polarization. Extending the temperature range is indispensable from the viewpoint of using the display in various environments, and reducing spontaneous polarization is necessary to suppress the occurrence of display unevenness on the screen. . In order to overcome the latter problem, we have proposed a method of mixing racemic compounds as disclosed in Japanese Patent Application No. 8-154927. However, in this method, there have been problems such as a decrease in the response speed and a deterioration in the alignment state.

[0022]

SUMMARY OF THE INVENTION According to the present invention, by designing a molecule so that the main skeleton of the compound has four phenyl ring structures, the compound exhibits an antiferroelectric phase more than a conventional antiferroelectric liquid crystal. The use of an antiferroelectric liquid crystal compound with a wider temperature range, especially the higher temperature range, as a component of the antiferroelectric liquid crystal composition makes it possible to increase the temperature range as compared with conventional antiferroelectric liquid crystals. Another object of the present invention is to provide an antiferroelectric liquid crystal composition having a wide temperature range exhibiting an antiferroelectric phase, a high response speed, and a reduced spontaneous polarization.

[0023]

According to the present invention, in the heating process, the temperature of the ferroelectric liquid crystal phase to the ferroelectric liquid crystal phase (or the liquid crystal on the higher temperature side including smectic A) is increased from 50 ° C. to 120 ° C. Phase transition temperature, the magnitude of spontaneous polarization is 130 nC / cm ² or less at a temperature lower by 30 ° C. from the phase transition temperature, and the response speed is 10
μs. The present invention relates to an antiferroelectric liquid crystal composition characterized by the following.

One specific means for obtaining the above-mentioned antiferroelectric liquid crystal composition is a molecular design in which the main skeleton of a conventionally known antiferroelectric liquid crystal compound has a four-phenyl ring structure. Accordingly, an antiferroelectric liquid crystal compound in which the temperature range of the antiferroelectric liquid crystal phase is expanded to a higher temperature side is used.

This antiferroelectric liquid crystal compound has the following general formula (1)

Embedded image [Wherein, R ¹ is an alkyl group having 6 to 16 carbon atoms and an alkenyl group having a terminal double bond represented by the formula CH ₂ −CH— (CH ₂ ) m− (where m is 4 to 12). R ² is an alkyl group having 2 to 8 carbon atoms, A ¹ , A ² and A ³ are a single bond, —COO—
And a group independently selected from the group consisting of -COS-
X ¹ , X ² , X ³ and X ⁴ are elements independently selected from the group consisting of hydrogen and fluorine, Y represents a single bond or an ether bond, and * represents an asymmetric carbon. ].

Among them, the following general formula (2)

Embedded image [Wherein, R ¹ is an alkyl group having 6 to 16 carbon atoms and an alkenyl group having a terminal double bond represented by the formula CH ₂ −CH— (CH ₂ ) m− (where m is 4 to 12). A hydrocarbon group selected from the group consisting of: R ² is an alkyl group having 2 to 8 carbon atoms; X ¹ , X ² , X ³ and X ⁴ are elements independently selected from the group consisting of hydrogen and fluorine And * indicates an asymmetric carbon. The anti-ferroelectric liquid crystal composition containing at least one antiferroelectric liquid crystal compound represented by the following formula:

Further, the following general formula (3)

Embedded image [Wherein, R ¹ is an alkyl group having 6 to 16 carbon atoms and an alkenyl group having a terminal double bond represented by the formula CH ₂ −CH— (CH ₂ ) m− (where m is 4 to 12). A hydrocarbon group selected from the group consisting of: R ² represents an alkyl group having 2 to 8 carbon atoms; Y represents a single bond or an ether bond;
Represents an asymmetric carbon. The anti-ferroelectric liquid crystal composition containing at least one antiferroelectric liquid crystal compound represented by the following formula:

In particular, the following general formula (4)

Embedded image [Wherein, R ¹ is an alkyl group having 6 to 16 carbon atoms and an alkenyl group having a terminal double bond represented by the formula CH ₂ −CH— (CH ₂ ) m− (where m is 4 to 12). A hydrocarbon group selected from the group consisting of: R ² represents an alkyl group having 2 to 8 carbon atoms, and * represents an asymmetric carbon. The most preferable is an antiferroelectric liquid crystal composition containing at least one of the antiferroelectric liquid crystal compound represented by the general formula (5) and the antiferroelectric liquid crystal compound represented by the general formula (5).

Embedded image

The antiferroelectric liquid crystal compound represented by the general formulas (1) to (5) accounts for 1 wt% to 70 wt%, preferably 2 wt%, based on the total amount of the antiferroelectric liquid crystal composition of the present invention.
% To 50% by weight.

Among the compounds represented by the general formula (1), those having 4, 6 and 8 carbon atoms in R ² are the most preferred groups, and the following are the groups of 2, 3, 5 and 7.

The positions of X ¹ , X ² and X ³ are represented by the following formulas

Embedded image The position of X ⁴ is preferably represented by the general formula (6)

Embedded image The general formula (7) is also used

Embedded image The position indicated by is also preferable.

Particularly preferred antiferroelectric liquid crystal compounds are exemplified in the following table. However, X ⁴ bonded to the position of the general formula (7) is shown as X ^{5 in the} table.

In the table,-represents a single bond. C ₉ H ₁₇ is CH ₂
= CH-C ₇ H ₁₄ - shows the. C ₁₀ H ₁₉ is CH ₂ = CH-C
₈ H ₁₆ -is shown. C ₁₁ H ₂₁ is _{CH 2 = CH-C 9 H} 18 - shows the. C ₁₂ H ₂₃ is _{CH 2 = CH-C 10 H} 20 - shows the. X ⁵
Indicates that X ⁴ is at the bonding position represented by the general formula (7).

[0034]

[Table 1]

[0035]

[Table 2]

[0036]

[Table 3]

[0037]

[Table 4]

[0038]

[Table 5]

[0039]

[Table 6]

[0040]

[Table 7]

[0041]

[Table 8]

[0042]

[Table 9]

[0043]

[Table 10]

[0044]

[Table 11]

[0045]

[Table 12]

[0046]

[Table 13]

[0047]

[Table 14]

[0048]

[Table 15]

[0049]

[Table 16]

[0050]

[Table 17]

[0051]

[Table 18]

[0052]

[Table 19]

[0053]

[Table 20]

[0054]

[Table 21]

[0055]

[Table 22]

[0056]

[Table 23]

[0057]

[Table 24]

[0058]

[Table 25]

[0059]

[Table 26]

[0060]

[Table 27]

[0061]

[Table 28]

[0062]

[Table 29]

[0063]

[Table 30]

[0064]

[Table 31]

[0065]

[Table 32]

[0066]

[Table 33]

[0067]

[Table 34]

[0068]

[Table 35]

[0069]

[Table 36]

[0070]

[Table 37]

[0071]

[Table 38]

[0072]

[Table 39]

[0073]

[Table 40]

[0074]

[Table 41]

[0075]

[Table 42]

[0076]

[Table 43]

[0077]

[Table 44]

[0078]

[Table 45]

[0079]

[Table 46]

[0080]

[Table 47]

[0081]

[Table 48]

[0082]

[Table 49]

[0083]

[Table 50]

[0084]

[Table 51]

[0085]

[Table 52]

[0086]

[Table 53]

[0087]

[Table 54]

[0088]

[Table 55]

[0089]

[Table 56]

[0090]

[Table 57]

[0091]

[Table 58]

[0092]

[Table 59]

[0093]

[Table 60]

[0094]

[Table 61]

[0095]

[Table 62]

[0096]

[Table 63]

[0097]

[Table 64]

[0098]

[Table 65]

[0099]

[Table 66]

[0100]

[Table 67]

[0101]

[Table 68]

[0102]

[Table 69]

[0103]

[Table 70]

[0104]

[Table 71]

[0105]

[Table 72]

[0106]

[Table 73]

[0107]

[Table 74]

[0108]

[Table 75]

[0109]

[Table 76]

[0110]

[Table 77]

[0111]

[Table 78]

[0112]

[Table 79]

[0113]

[Table 80]

[0114]

[Table 81]

[0115]

[Table 82]

[0116]

[Table 83]

[0117]

[Table 84]

[0118]

[Table 85]

[0119]

[Table 86]

[0120]

[Table 87]

[0121]

[Table 88]

[0122]

[Table 89]

[0123]

[Table 90]

[0124]

[Table 91]

[0125]

[Table 92]

[0126]

[Table 93]

[0127]

[Table 94]

[0128]

[Table 95]

[0129]

[Table 96]

[0130]

[Table 97]

[0131]

[Table 98]

[0132]

[Table 99]

[0133]

[Table 100]

[0134]

[Table 101]

[0135]

[Table 102]

[0136]

[Table 103]

[0137]

[Table 104]

The above reaction is represented by the following chemical formula.

Embedded image

[0139]

EXAMPLES The present invention will be described below with reference to Examples, Comparative Examples and Production Examples, but the present invention is not limited thereto.

Production Example 1 The following formula (+)-4'-hydroxy-4- (1,1,1-
Synthesis of trifluoro-2-octyloxycarbonyl) biphenyl-4'-decylbiphenyl-4-carboxylate.

Embedded image (+)-4'-Hydroxy-4- (1,1,1-trifluoro-2-octyl) carboxylate biphenyl 0.30
g (0.79 mmol) was dissolved in 100 ml of methyl chloride, and 4'-decyl-3-fluoro-biphenyl-
0.27 g (0.72 mmol) of 4-carboxylic acid chloride
l) and triethylamine (TEA) 0.08 g
(0.75 mmol) and 0.03 g (0.22 mmol) of dimethylaminopyridine (DMAP) were reacted for about 24 hours with stirring at room temperature under a nitrogen atmosphere to obtain a reaction product. This was subjected to silica gel chromatography with a 20: 1 mixed solvent of hexane: ethyl acetate to remove impurities, and 0.40 g (0.5%) of the target compound was recrystallized with ethanol.
6 mmol). Yield 77.6%. Purity 99.7% as measured by liquid chromatography.

The above compound was injected into a cell having a thickness of 2 μm made of glass having a transparent electrode coated with polyimide and subjected to rubbing treatment, and the phase transition temperature observed by a microscope equipped with a hot stage is shown in the following table (hereinafter referred to as phase transition temperature). Were measured in the same manner).

[Table 105]

Preparation Example 2 4'-decyl-3-fluoro-biphenyl- of Preparation Example 1
4'-undecyl-3 in place of 4-carboxylic acid chloride
-Fluoro-biphenyl-4-carboxylic acid chloride
(+)-4'-Hydroxy-4- (1,1,1-trifluoro-2-octylcarbonyl) biphenyl- of the following formula was prepared in the same manner as in Production Example 1 except that 79 mmol was used.
4'-Undecylbiphenyl-4-carboxylate was obtained.

Embedded image

The following Table shows the phase transition temperatures of the compounds purified in the same manner as in Production Example 1.

[Table 106]

Production Example 3 The starting material of Production Example 1 was replaced with (+)-4'-hydroxy-4-
0.79 mmol of biphenyl (1,1,1-trifluoro-2-hexyl) carboxylate and 0.72 mmol of 4'-decyl-3-fluoro-biphenyl-4-carboxylic acid chloride
and (+)-4'-hydroxy-4- (1,1,1-
(Trifluoro-2-hexyloxycarbonyl) biphenyl-4'-decylbiphenyl-4-carboxylate was obtained.

Embedded image

The following Table shows the phase transition temperatures of the compounds purified in the same manner as in Production Example 1.

[Table 107]

Production Example 4 4'-decyl-3-fluoro-biphenyl- of Production Example 3
(+)-4'-Hydroxy-4- (1) of the following formula was prepared in the same manner as in Production Example 3 except that 4-carboxylic acid chloride was replaced with 4'-undecyl-3-fluoro-biphenyl-4-carboxylic acid chloride. , 1,1-trifluoro-2-hexyloxycarbonyl) biphenyl-4'-undecylbiphenyl-4-carboxylate.

Embedded image

The following Table shows the phase transition temperatures of the compounds purified in the same manner as in Production Example 1.

[Table 108]

Production Example 5 The starting material of Production Example 1 was replaced with (+)-4'-hydroxy-4-
0.79 mmol of (1,1,1-trifluoro-2-hexyl) carboxylic acid-2-fluoro-biphenyl and 4 ′
In the same manner as in Production Example 1 except that 0.72 mmol of -nonyl-3-fluoro-biphenyl-4-carboxylic acid chloride was used, (+)-4'-hydroxy-4-
(1,1,1-Trifluoro-2-hexyloxycarbonyl) -2-fluoro-biphenyl-4'-nonylbiphenyl-4-carboxylate was obtained.

Embedded image

The following Table shows the phase transition temperatures of the compounds purified in the same manner as in Production Example 1.

[Table 109]

Production Example 6 Starting material (+)-4'-hydroxy-4-of Production Example 1
0.79 mmol of (1,1,1-trifluoro-2-hexyl) carboxylic acid-2-fluoro-biphenyl and 4 ′
In the same manner as in Production Example 1 except that 0.72 mmol of -nonyl-3-fluoro-biphenyl-4-carboxylic acid chloride was used, (+)-4'-hydroxy-4-
(1,1,1-Trifluoro-2-hexyloxycarbonyl) -2-fluoro-biphenyl-4'-decylbiphenyl-4'-carboxylate was obtained.

Embedded image

The following Table shows the phase transition temperatures of the compounds purified in the same manner as in Production Example 1.

[Table 110]

Production Example 7 Starting material (+)-4'-hydroxy-4- of Production Example 1
0.79 mmol of (1,1,1-trifluoro-2-hexyl) carboxylic acid-2-fluoro-biphenyl and 4 ′
In the same manner as in Production Example 1 except that 0.72 mmol of -nonyl-3-fluoro-biphenyl-4-carboxylic acid chloride was used, (+)-4'-hydroxy-4-
(1,1,1-trifluoro-2-hexyloxycarbonyl) -2-fluoro-biphenyl-4'-undecylbiphenyl-4'-carboxylate was obtained.

Embedded image

The following Table shows the phase transition temperatures of the compounds purified in the same manner as in Production Example 1.

[Table 111]

The method for measuring the response speed in the present invention is as follows. The compound was injected into a 2 μm-thick cell made of glass with a transparent electrode that had been coated with polyimide and rubbed, and the liquid crystal physical property measurement cell was set on a hot stage. It was arranged in a polarizing microscope equipped with a doubler so as to provide a dark field without an electric field. When the liquid crystal in the cell is in the antiferroelectric phase,
The response time τ can be determined from the change in the relative transmittance of light when a rectangular wave of ± 50 V as shown in FIG. 5 is applied to the cell. τ is the state of the ferroelectric phase (at the end of the rectangular wave voltage on the minus side), the state of the next ferroelectric phase via the state of the antiferroelectric phase (the relative transmittance is 90% by applying the rectangular wave voltage on the plus side) ), And the unit is μsec.

Embodiment 1

Embedded image An antiferroelectric composition was prepared, and the phase transition temperature was examined. As a result, the data shown in the following table were obtained.

[Table 112]

In the case of comparing the antiferroelectric liquid crystal compositions, if the phase transition temperatures are too different, the comparison is usually made at a certain temperature lower than the transition point. In this specification, the point (T _CA ) lower than the antiferroelectric phase transition temperature (TC A) by 30 ° C.
_CA- 30). In the first embodiment, 110.
The response speed and spontaneous polarization at 1-30 = 80.1 (° C.) were examined.

[Table 113]

Embodiment 2

Embedded image An antiferroelectric composition was prepared, and the phase transition temperature was examined. As a result, the data shown in the following table were obtained.

[Table 114]

[0158] The T _CA measurement of response time and spontaneous polarization because it is 106.4 ° C. of the composition of Example 2 was carried out 106.4-30 = 76.4 ℃.

[Table 115]

Comparative Example 1

Embedded image An antiferroelectric composition was prepared, and the phase transition temperature was examined. As a result, the data shown in the following table were obtained.

[Table 116]

[0160] T _CA measurement of response time and spontaneous polarization because it is 81.9 ° C. of the composition of Comparative Example 1 was carried out at 81.9-30 = 51.9 ℃.

[Table 117]

Comparative Example 2

Embedded image An antiferroelectric composition was prepared, and the phase transition temperature was examined. As a result, the data shown in the following table were obtained.

[Table 118]

[0162] Since T _CA of the composition of Comparative Example 2 is 65.1 ° C., the measurement of the response speed and the spontaneous polarization was carried out at 65.1-30 = 35.1 ℃.

[Table 119]

[0163]

[Consideration] In Comparative Example 1, the response speed is satisfied, but the spontaneous polarization is large. In Comparative Example 2, the spontaneous polarization is almost good, but the response speed is slow. However, both Examples 1 and 2 satisfy the requirements of both the response speed and the spontaneous polarization, and it can be seen that they are useful as the base material of the antiferroelectric liquid crystal composition.

[0164]

(1) According to the present invention, the temperature range in which the antiferroelectric phase is exhibited is wider than that of the conventional antiferroelectric liquid crystal composition, and the temperature range on the high temperature side can be expanded. (2) In addition, the antiferroelectric liquid crystal composition of the present invention had a higher response speed than the conventional antiferroelectric liquid crystal composition and was able to reduce the magnitude of spontaneous polarization.

[Brief description of the drawings]

1 (A) shows an applied triangular wave, (B) shows a commercially available nematic liquid crystal, (C) shows a two-state liquid crystal, and (D) shows a tristable state liquid crystal. .

FIG. 2 shows two stable alignment states of ferroelectric liquid crystal molecules proposed by Clark / Lagerval.

FIG. 3 (A) shows three stable alignment states of the “anti” ferroelectric liquid crystal molecules of the present invention, and (B) shows each of (A), (b) and (c) of A. The corresponding three-state switching and the change of the liquid crystal molecule arrangement are shown.

FIG. 4 is an applied voltage-light transmittance characteristic diagram showing that the “anti” ferroelectric liquid crystal molecules change their light transmittance by drawing a double hysteresis with respect to an applied voltage.

FIG. 5A shows a relationship between applied voltage and time, and FIG.
Is a graph showing a response state of liquid crystal molecules when the applied voltage is applied.

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[Procedure amendment]

[Submission date] September 25, 1997

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Name of invention

[Correction method] Change

[Correction contents]

Patent application title: Antiferroelectric liquid crystal composition having fast response speed and small spontaneous polarization

Continued on the front page (72) Inventor Noriko Yamakawa 2-3-2 Daiba, Minato-ku, Tokyo Inside Showa Shell Sekiyu KK

Claims (6)

[Claims] 1. The method according to claim 1, wherein the temperature is not lower than 50 ° C.
It has a phase transition temperature at which the temperature changes from an antiferroelectric liquid crystal phase to a ferroelectric liquid crystal phase (or a liquid crystal phase containing higher temperature including smectic A) below 30 ° C., and 30 ° C. from the phase transition temperature.
On the low temperature side, the magnitude of the spontaneous polarization is 130 nC / cm ²
And a response speed of 10 μs. An antiferroelectric liquid crystal composition characterized by the following. 2. The following general formula (1): [Wherein, R ¹ is an alkyl group having 6 to 16 carbon atoms and an alkenyl group having a terminal double bond represented by the formula CH ₂ −CH— (CH ₂ ) m− (where m is 4 to 12). R ² is an alkyl group having 2 to 8 carbon atoms, A ¹ , A ² and A ³ are a single bond, —COO—
And X ¹ , X ² , X ³ and X ⁴ are independently selected from the group consisting of hydrogen and fluorine, and Y is a single bond or an ether. Represents a bond, and * represents an asymmetric carbon. 2. The antiferroelectric liquid crystal composition according to claim 1, comprising at least one antiferroelectric liquid crystal compound represented by the following formula: 3. The following general formula (2): [Wherein, R ¹ is an alkyl group having 6 to 16 carbon atoms and an alkenyl group having a terminal double bond represented by the formula CH ₂ −CH— (CH ₂ ) m− (where m is 4 to 12). A hydrocarbon group selected from the group consisting of: R ² is an alkyl group having 2 to 8 carbon atoms; X ¹ , X ² , X ³ and X ⁴ are elements independently selected from the group consisting of hydrogen and fluorine And * indicates an asymmetric carbon. 2. The antiferroelectric liquid crystal composition according to claim 1, comprising at least one antiferroelectric liquid crystal compound represented by the following formula: 4. The following general formula (3): [Wherein, R ¹ is an alkyl group having 6 to 16 carbon atoms and an alkenyl group having a terminal double bond represented by the formula CH ₂ −CH— (CH ₂ ) m− (where m is 4 to 12). A hydrocarbon group selected from the group consisting of: R ² represents an alkyl group having 2 to 8 carbon atoms; Y represents a single bond or an ether bond;
Represents an asymmetric carbon. 2. The antiferroelectric liquid crystal composition according to claim 1, comprising at least one antiferroelectric liquid crystal compound represented by the following formula: 5. The following general formula (4): [Wherein, R ¹ is an alkyl group having 6 to 16 carbon atoms and an alkenyl group having a terminal double bond represented by the formula CH ₂ −CH— (CH ₂ ) m− (where m is 4 to 12). A hydrocarbon group selected from the group consisting of: R ² represents an alkyl group having 2 to 8 carbon atoms, and * represents an asymmetric carbon. 2. The antiferroelectric liquid crystal composition according to claim 1, comprising at least one antiferroelectric liquid crystal compound represented by the following formula: 6. The following general formula (5): [Wherein, R ¹ is an alkyl group having 6 to 16 carbon atoms and an alkenyl group having a terminal double bond represented by the formula CH ₂ −CH— (CH ₂ ) m− (where m is 4 to 12). A hydrocarbon group selected from the group consisting of: R ² represents an alkyl group having 2 to 8 carbon atoms, and * represents an asymmetric carbon. 2. The antiferroelectric liquid crystal composition according to claim 1, comprising at least one antiferroelectric liquid crystal compound represented by the following formula: