JPH0959636A - Liquid crystal composition - Google Patents

Abstract

(57) Abstract: A liquid crystal composition suitable for use in an active matrix type or a simple matrix type liquid crystal display device is provided. A liquid crystal obtained by mixing an antiferroelectric liquid crystal represented by the following general formula (1) with a ferrielectric liquid crystal represented by the following chemical formula (2) and an optically active compound represented by the following general formula (3). Composition. Embedded image (In the formula, R and R ′ are linear alkyl groups, m is an integer of 5 or more, and n is
Is an integer of 1 or more, X, Y, Z are fluorine atoms or hydrogen atoms, p is an integer of 4 or more, and C * is an asymmetric carbon. )

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal composition suitable for use in an active matrix type liquid crystal display element or a simple matrix type liquid crystal display element driven for each pixel, and a liquid crystal display element using the composition. Regarding

[0002]

2. Description of the Related Art Liquid crystal display devices (LCDs) are already becoming popular mainly in portable devices as flat panel displays replacing conventional CRT displays. Along with the recent expansion of functions of personal computers and word processors and the increase in processing information, LCDs are required to have higher functions, that is, a large display capacity, full-color display, wide viewing angle, high-speed response, and high contrast. There is.

As a liquid crystal display system (liquid crystal driving system) that meets such demands, a thin film transistor is provided for each pixel of a screen.
(TFT) or diode (MIM) is formed, and the active matrix (AM) display element, which is the method to drive the liquid crystal independently for each pixel, and the STN using the simple matrix drive method.
A display element is implemented. Although the AM display method has problems such as difficulty in cost reduction due to low manufacturing yield and difficulty in increasing screen size, the high display quality surpasses the STN display method, which has been the mainstream in the past, and the CRT. The momentum is approaching.

Conventionally, T was used as a liquid crystal material for AM display elements.
Since N (Twisted Nematic) liquid crystal is used,
The following problems have occurred. (1) TN liquid crystal is a nematic liquid crystal, and its response speed is generally slow (several tens of ms), and good image quality cannot be obtained when displaying moving images. (2) The display angle is narrow because display is performed by using the twisted state (twist alignment) of liquid crystal molecules. Especially when performing gradation display,
The viewing angle sharply narrows. That is, the contrast ratio, color, and the like change depending on the viewing angle of the display. Further, a liquid crystal display device driven by a simple matrix can be produced at a lower cost than an AM drive device, but in addition to the problems (1) and (2) above, it is difficult to drive a large capacity and display a moving image. There are problems such as.

In order to solve these problems, an AM using a ferroelectric liquid crystal or an antiferroelectric liquid crystal instead of a TN liquid crystal has been proposed.
Panel proposals have been made in recent years (JP-A-5-249502, JP-A-5-150257, JP-A-6-95080, etc.), but these liquid crystals also have the following problems (3) and (4). There is currently a large barrier to practical use. (3) Ferroelectric liquid crystal has spontaneous polarization, but since spontaneous polarization is always present, image sticking easily occurs and driving is difficult. Further, since the ferroelectric liquid crystal can only display black and white in binary, in principle, gradation display is extremely difficult. Special attention is required when performing gradation display (for example, a ferroelectric liquid crystal device using monostable; Ke
iichi Nito et al., SID'94, Preprint p48), development of advanced practical technology is required.

(4) Since the antiferroelectric liquid crystal has no permanent spontaneous polarization, the problem of image sticking described in (3) above is avoided. At least 10V for AM drive
Although a liquid crystal material to be driven below is required, an antiferroelectric liquid crystal generally has a high threshold voltage and is difficult to drive at a low voltage. In addition, there is a problem that gradation display is difficult due to a history (hysteresis) in optical response. Also,
Even in a liquid crystal display device driven by a simple matrix,
The high threshold voltage of the antiferroelectric liquid crystal (meaning a large driving voltage) increases the load on the driving IC, and it has been desired to lower the threshold voltage.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to provide a new material having an extremely low threshold voltage suitable for AM driving and simple matrix driving which can solve the above problems. A liquid crystal having a ferrielectric phase can be considered as a new material suitable for AM driving. The ferrielectric liquid crystal having the ferrielectric phase (= SCγ * phase) was introduced in 1989,
It was first discovered in 4- (1-methylheptyloxycarbonyl) phenyl 4- (4-octyloxyphenyl) benzoate (abbreviated as MHPOBC) (Japanese Journal of Applied Ph
ysics, Vol.29, No.1, 1990, pp.L131-137).

The structural formula of MHPOBC and its phase sequence are as follows. MHPOBC formula: C ₈ H ₁₇ O-Ph-Ph-COO-Ph-COO-C * H (CH ₃ ) C ₆ H ₁₃ (Ph in the formula is a 1,4-phenylene group, C * is an asymmetric carbon, (Alkyl groups are straight-chain alkyl groups) Phase series: I (147) SA (122) SCα * (121) SC * (119) SCγ * (11
8) SCA * (65) SIA * (30) Cr (where SA is the smectic A phase, SCα * is the chiral smectic Cα phase, SC * is the chiral smectic C phase (ferroelectric phase), and SCγ * is the ferrielectric phase ( (Chiral smectic Cγ phase), SCA * is chiral smectic CA phase (antiferroelectric phase), SIA * is chiral smectic IA phase, Cr is crystalline phase, and phase transition temperature (° C) is shown in parentheses.)

In order to explain the ferrielectric liquid crystal, FIG. 1 shows the state of molecular alignment in the ferrielectric phase, and FIG. 2 shows the optical response to the triangular wave of the ferrielectric phase. In FIG. 2, although a difference is recognized between the voltage changing from the ferrielectric state to the ferroelectric state and the voltage changing from the ferroelectric state to the ferrielectric state, the alignment condition (type of alignment film, thickness Now, the difference can be eliminated by optimizing the type and thickness of the insulating film. Figure 1 for ferrielectric phase
FI (+) (when the applied voltage is positive) or FI (-) (when the applied voltage is negative) are arranged in the molecular array. In the absence of an electric field, FI (+) and FI (-) are equivalent and therefore coexist. Therefore, the average optical axis is in the layer normal direction, and
It becomes a dark state under the conditions of the polarizing plate shown in. This state corresponds to the state where the transmitted light intensity is 0 when the voltage is 0 in FIG.

Further, FI (+) and FI (-) each have spontaneous polarization, as is clear from the molecular arrangement state, but in these coexisting states, the spontaneous polarizations cancel each other out, so the average spontaneous polarization is zero. Becomes For this reason, the ferrielectric liquid crystal escapes the image sticking phenomenon observed in the ferroelectric liquid crystal, like the antiferroelectric liquid crystal.

When an electric field is applied to the ferrielectric phase, the ferroelectric phase FO (+) or FO (-) is in a stable state depending on the direction of the electric field.
Phase transition to. That is, in FIG. 2, the transmitted light intensity is 0.
FO (+) or FO (-) is a saturated state (flat part on the left and right). It can be seen from FIG. 1 that in this ferroelectric state FO (+) or FO (-), a larger spontaneous polarization is developed than in the ferrielectric state FI (+) or FI (-). The larger the spontaneous polarization is, the faster the response speed becomes, but the faster response is exhibited. Under the conditions of the polarizing plate shown in FIG. 1, both ferroelectric states are bright. As described above, in the ferrielectric phase, the coexistence state of FI (+) and FI (-) is dark, and the ferroelectric state FO
(+) And FO (-) can be used as light.

In the conventional ferroelectric liquid crystal, switching was performed between FO (+) and FO (-), whereas in the ferrielectric liquid crystal,
It has a major feature of switching between four states of FI (+), FO (+), FO (-) and FI (-). However, all of the display principles utilize the birefringence of liquid crystal, and it is possible to manufacture a display element having a small viewing angle dependency.

As shown in FIG. 2, the ferrielectric liquid crystal generally has a small difference between the voltage changing from the ferrielectric state to the ferroelectric state and the voltage changing from the ferroelectric state to the ferrielectric state. That is, the hysteresis width tends to be narrow, and the characteristics are suitable for AM driving and gradation display in AM driving. In addition, the threshold voltage, which is the voltage at which the ferrielectric liquid crystal changes from the ferrielectric state to the ferroelectric state, tends to be smaller than that of the antiferroelectric liquid crystal. It can be said that the ferrielectric liquid crystal is suitable for AM driving. However, the number of ferrielectric liquid crystals synthesized to date is extremely small,
Further, the conventionally known ferrielectric liquid crystal has not been found to be satisfactory in terms of hysteresis and threshold voltage when the application to an AM driving element is considered.

Also in the case of a simple matrix driving material, development of a liquid crystal material having a low threshold voltage and a sufficient response speed is an essential item from the viewpoint of a driving IC. As a method of lowering the threshold voltage of the antiferroelectric liquid crystal, the present inventors have already mixed the ferridielectric liquid crystal with the antiferroelectric liquid crystal in JP-A-6-184536, and thus the low threshold voltage It has been clarified that an antiferroelectric liquid crystal composition that is is obtained. However, this method is not always satisfactory in terms of response speed.

The fast response of the response speed is important in the following points. As shown in FIG. 3, in the case of antiferroelectric liquid crystal, there is a clear optical history with respect to the voltage, and there are two states from the antiferroelectric state to the ferroelectric state and from the ferroelectric state to the antiferroelectric state. There is switching. The two switching speeds by the voltage, that is, the response speed, are one of the major factors that determine the display quality of the device.

For example, in simple matrix driving, line-sequential scanning is performed, and the response speed from the antiferroelectric to the ferroelectric state is the writing speed per scanning line, so the number of scanning lines forming one screen is determined. It will be. That is, the faster the response speed, the more the number of scanning lines can be increased, and a high-definition element can be realized. In addition, the response speed from the ferroelectric state to the antiferroelectric state changes depending on the design of the driving method of the device. Generally, this speed is set to an optimum value after determining the driving method. In AM driving as well, it is required that writing is completed by one pulse instead of cumulative response, so the response speed from the ferrielectric state to the ferroelectric state is important. In the present invention, therefore, attention has been paid to the response speed from the antiferroelectric state to the ferroelectric state and from the ferrielectric state to the ferroelectric state.

As described above, the present invention is excellent in hysteresis, threshold voltage and response speed characteristics for AM driving by adding a certain kind of optically active compound to a mixture of antiferroelectric liquid crystal and ferrielectric liquid crystal. It is to provide a new ferrielectric liquid crystal composition that can be suitably used. Further, the present invention can be suitably used as a material for driving a simple matrix by adding a kind of an optically active compound to a mixture of an antiferroelectric liquid crystal and a ferrielectric liquid crystal, which has a low threshold voltage and a high speed response. To provide a material showing.

[0018]

Means for Solving the Problems That is, the present invention provides an antiferroelectric liquid crystal represented by the following general formula (1)
Ferrielectric liquid crystal represented by (2) and the following general formula (3)
A liquid crystal composition obtained by mixing an optically active compound represented by:

[0019]

Embedded image (In the formula, R and R ′ are linear alkyl groups, m is an integer of 5 or more, and n is
Is an integer of 1 or more, X, Y, Z are fluorine atoms or hydrogen atoms, p is an integer of 4 or more, and C * is an asymmetric carbon).

In the present invention, an antiferroelectric liquid crystal in which R in the general formula (1) has 6 to 10 carbon atoms is preferably used (Examples 1 to 8, 9 to 14). Also, m in the general formula (1) is
The range of 5 to 6 and the range of n are preferably 2 to 3, particularly m =
5, an antiferroelectric liquid crystal with n = 2 is particularly suitable. An optically active compound in which R'in the general formula (3) has 8 to 12 carbon atoms is preferable (Examples 1 to 8 and 9 to 14). Also, the general formula (3)
The optically active compounds in which p is an even number of 4 to 10 are preferable (Examples 1 to 8 and 9 to 14).

The liquid crystal composition of the present invention can be prepared by adjusting the composition ratio so that it has a ferrielectric phase or an antiferroelectric phase in the temperature range practically required. The composition is 20 to 70 mol% of antiferroelectric liquid crystal represented by general formula (1), 5 to 50 mol% of ferrielectric liquid crystal represented by chemical formula (2), and represented by general formula (3). The optically active compound is preferably selected from the range of 10 to 40 mol%.

The AM driving material preferably has a ferrielectric phase, and the simple matrix driving material preferably has an antiferroelectric phase (Example 1).
~ 9 and Examples 10-14). The liquid crystal composition according to the present invention is used by sandwiching it between two electrode substrates provided with an alignment film and an insulating film. At that time, the alignment of the liquid crystal molecules in the sandwiched condition gives a display quality. The quality of the orientation is extremely important because it becomes one factor for determining. Therefore, the liquid crystal composition preferably has a chiral smectic C phase or a smectic A phase on the high temperature side of an antiferroelectric phase or a ferrielectric phase, more preferably a smectic A phase (all examples).

The AM driving material preferably has a ferri-dielectric phase, and the ferri-dielectric phase is at least in a temperature range of 0 to 40 ° C., and particularly the ferri-dielectric phase is at least in a temperature range of −20 to + 50 ° C. The liquid crystal composition having is preferable.
Further, the threshold voltage when the ferrielectric phase transitions from the ferrielectric state to the ferroelectric state is 5 V / μm or less, especially 2
V / μm or less is preferable. An active matrix liquid crystal display device in which the liquid crystal composition having the ferri-dielectric phase is sandwiched between substrates provided with a non-linear active device such as a thin film transistor or a diode for each pixel can be suitably manufactured. The active matrix liquid crystal display element is configured by driving the liquid crystal by the voltage of the active element by switching to two ferrielectric states, two ferroelectric states, and an intermediate state thereof.

On the other hand, a simple matrix driving material preferably has an antiferroelectric phase (Examples 10 to 1).
4) A liquid crystal composition having an antiferroelectric phase at least in the temperature range of 0 to 40 ° C., particularly preferably having an antiferroelectric phase in the temperature range of −20 ° C. to + 50 ° C. is preferred. The threshold voltage when the antiferroelectric phase transitions from the antiferroelectric state to the ferroelectric state is preferably 10 V / μm or less, and particularly preferably 5 V / μm or less. A simple matrix liquid crystal display device in which the liquid crystal composition having the antiferroelectric phase is sandwiched between substrates on which scanning electrodes and signal electrodes are arranged on a matrix can be suitably manufactured. Is a simple matrix liquid crystal display device which is configured to switch driving by a voltage between 1 and 2 antiferroelectric states.

The antiferroelectric liquid crystal of the present invention can be easily produced by the method already disclosed by the present inventors (JP-A-3-198155). The outline of the manufacturing method is as follows. (B) AcO-Ph (3X) -COOH + SOCl ₂ → AcO-Ph (3X) -COCl (b) (b) + HOC * H (CF ₃ ) (CH ₂ ) _m OC _n H _{2n + 1} → AcO -Ph (3X) -COOC * H (CF ₃ ) (CH ₂ ) _m OC _n H _{2n + 1} (ha) (b) + Ph-CH ₂ NH ₂ → HO-Ph (3X) -COOC * H (CF ₃ ) (CH ₂ ) _m OC _n H _{2n + 1} (d) RO-Ph-Ph-COOH + SOCl ₂ → RO-Ph-Ph-COCl (e) (b) + (d) → target liquid crystal compound In the formula, Ph is 1,4-phenylene group, Ph (3X) is 3-
1,4-phenylene group optionally substituted with F at position, C * represents an asymmetric carbon.

The above manufacturing method will be briefly described as follows. (A) shows the chlorination reaction of p-acetoxybenzoic acid with thionyl chloride. (B) shows the formation of an ester by the reaction between the chloride (a) and the optically active alcohol. (C) shows the deacetylation of the ester (b). (D) Chlorination of 4'-alkyloxybiphenyl-4-carboxylic acid. (E)
Is a reaction for forming a target liquid crystal compound by the reaction of (C) and (D).

The ferrielectric liquid crystal of the present invention can be easily manufactured by the method already disclosed by the present inventors (JP-A-3-292388). The outline of the manufacturing method is as follows. (1) AcO-Ph-Ph-COOH + SOCl ₂ → AcO-Ph-Ph-COCl (2) (1) + CF ₃ C * H (OH) (CH ₂ ) ₅ OC ₂ H ₅ → AcO-Ph- Ph-COO-C * H (CF ₃ ) (CH ₂ ) ₅ OC ₂ H ₅ (3) (2) + Ph-CH ₂ NH ₂ → HO-Ph-Ph-COO-C * H (CF ₃ ) ( CH ₂ ) ₅ OC ₂ H ₅ (4) RO-Ph-COOH + LiAlH ₄ → RO-Ph-CH ₂ 0H (5) (3) + (4) + (triphenylphosphine / diethylazykarbonic acid) → purpose Liquid Crystal Compound In the above formula, Ph represents a 1,4-phenylene group and C * represents an asymmetric carbon.

The above manufacturing method will be briefly described as follows. (1) is chlorination of 4'-alkyloxybiphenyl-4-carboxylic acid. (2) is the formation of an ester by the reaction of chloride (1) with an optically active alcohol. (3) is deacetylation of ester <2>. (4) is the reduction of the carboxyl group of p-acetoxybenzoic acid. (5) is (3)
This is a reaction for forming the target liquid crystal compound by the reaction between (4) and (4).

The optically active compound of the present invention can be easily produced by the method already disclosed by the present inventors (Japanese Patent Application No. 7-13856). The outline of the manufacturing method is as follows. (a) HO-Ph (2Y) -COOH + RCOCl → RCOO-Ph (2Y) -COOH (b) (a) + SOCl ₂ → RCOO-Ph (2Y) -COCl (c) AcO-Ph (3Z)- COOH + SOCl ₂ → AcO-Ph (3Z) -COCl (d) (c) + R * OH → AcO-Ph (3Z) -COOR * (e) (d) + Ph-CH ₂ NH ₂ → HO-Ph (3Z) -COOR * (f) (b) + (e) → optically active compound of interest In the above formula, Ph is a 1,4-phenylene group, Ph (2Y), Ph
(3Z) is a 1,4-phenylene group appropriately F-substituted at the 2-position or the 3-position,
R * OH indicates an optically active alcohol.

The above manufacturing method will be briefly described as follows. (a) is the formation of an ester by the reaction of p-hydroxybenzoic acid with an acid chloride. (b) is the chlorination of (a) with thionyl chloride. (c) is chlorination of p-acetoxybenzoic acid with thionyl chloride. (d) is esterification by the reaction of (c) with a linear alcohol. (e) is
Deacetylation of (d) with benzylamine. (f)
Is esterification by reaction of (b) and (e).

[0031]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited thereto. Example 1 An antiferroelectric liquid crystal represented by the following chemical formula (1A) was added with a ferrielectric liquid crystal represented by the above chemical formula (2) and a pharmaceutically active compound represented by the following chemical formula (3A) in an amount of 45, 25 and 30 mol%, respectively. A liquid crystal composition was prepared by mixing in a ratio. 1A: C ₆ H ₁₃ -O-Ph-Ph-COO-Ph (3F) -COO-C * H (CF ₃ ) (CH ₂ ) ₅ OC ₂ H ₅ 3A: C ₉ H ₁₉ -COO-Ph-COO -Ph-COO-C * H (CH ₃ ) C ₆ H _{13 In the} formula, Ph is a 1,4-phenylene group, Ph (3F) is a 1,4-phenylene group substituted with fluorine at the 3-position, and C * is Indicates asymmetric carbon.

The results of identifying the phases of the obtained liquid crystal composition are shown in Table 1. As is clear from Table 1, the temperature range of the ferrielectric phase of the composition obtained was preferable as a practical material. Phase identification is by texture observation,
It was performed by observing a conoscopic image and measuring DSC (differential differential scanning calorimeter). Table 2 shows the results of examining the optical response of the obtained liquid crystal composition at 30 ° C. From Table 2, it is understood that the liquid crystal composition having the ferrielectric phase (ferrielectric liquid crystal composition) has an extremely low threshold voltage and exhibits high-speed response. This composition can be driven at a voltage of 8 V and exhibits a high-speed response, and thus can be suitably used for a TFT driving element.

The optical response was measured by the following procedure.
A glass substrate provided with an ITO electrode and an insulating film (SiO ₂ , film thickness of about 50 nm) was subjected to polyimide coating (film thickness of about 80 nm), and then only one of the pair of glass substrates was rubbed. Particle size 1.6μm
A pair of glass substrates were bonded to each other via the spacer to prepare a test cell. The cell thickness was 2 μm. The liquid crystal was heated to a temperature at which the liquid crystal was in an isotropic phase, and the liquid crystal was injected into the test cell by a capillary phenomenon. Thereafter, the liquid crystal was gradually cooled at a rate of 1 ° C./min to align the liquid crystal in parallel, and further cooled to 30 ° C. A triangular wave voltage of ± 10 V and 50 mHz was applied to the test cell to drive it, and the change in transmitted light was examined. The threshold voltage I is the voltage at which the transmitted light intensity reaches 90% due to the phase transition from the ferrielectric phase to the ferroelectric phase, and the threshold voltage is 10% due to the phase transition from the ferroelectric phase to the ferrielectric phase. The threshold voltage was measured by defining the voltage at which it decreased as the threshold voltage II. FIG. 2 shows the optical response history with respect to the applied voltage. Also, 8
When the pulse voltage of V and frequency of 10Hz is applied, the transmitted light intensity becomes 0.
The response time was measured by defining the time required to change from 90% to 90% as the response time.

Examples 2 and 3 Liquid crystals were prepared by mixing the composition ratios of 1A / 2 / 3A = 50/25/25 (Example 2) and 30/40/30 (Example 3) in Example 1. A composition was prepared. The phase series, threshold voltage, and response time of the prepared liquid crystal composition were determined in the same manner as in Example 1, and the results are shown in Table 1 and Table 2, respectively. The temperature range of the ferrielectric phase of the obtained composition was preferable as a practical material. In addition, since it can be driven with a voltage of 8 V and exhibits a high-speed response, TF
It can be suitably used for a T drive element.

[0035]

[Table 1] Phase Sequence Component Molar% Example 1 I (72) SA (58) SCγ * (<-20) Cr 1A / 2 / 3A = 45/25/30 1A I (105) SA (102) SCA * (8) SX (4) Cr 2 I (71) SCα * (70) SCγ * (50) Cr 3A I (-1) SCA * (-25) Cr Example 2 I (76) SA (63) SCγ * (<-20) Cr 1A / 2 / 3A = 50/25/25 Example 3 I (67) SA (54) SCγ * (<-20) Cr 1A / 2 / 3A = 30/40/30 Above phase In the series, I is isotropic phase, SA is smectic A
Phase, SCA * is an antiferroelectric phase, SX is an unidentified phase, SCα * is a chiral smectic Cα phase, SCγ * is a ferrielectric phase, and Cr is a crystalline phase.

[0036]

[Table 2] Threshold voltage (V / μm) Response time Measurement temperature I II (μsec) (℃) Example 1 1.6 0.5 41 30 1A 7.7 (* 1) 3.8 (* 1) * 2 30 2 − − − * 3 3A − − − * 4 Example 2 1.9 0.6 95 30 Example 3 1.7 0.5 62 30 * 1; Measured under the condition of ± 35 V, 1 Hz. * 2: Since the threshold voltage is as high as 7.7V / μm, it does not respond with an applied voltage of 8V. * 3, * 4: Cannot be measured at 30 ° C.

Examples 4 to 6 Ferroelectric liquid crystal (2) and an optically active compound represented by the following chemical formula (3B, 3C) were added to the antiferroelectric liquid crystal represented by the following chemical formula (1B, 1C) at 37.5, 25 and 37.5 mol% were mixed to prepare a liquid crystal composition. 1B: C ₈ H ₁₇ -O-Ph-Ph-COO-Ph (3F) -COO-C * H (CF ₃ ) (CH ₂ ) ₅ OC ₂ H ₅ 1C: C ₉ H ₁₉ -O-Ph-Ph -COO-Ph (3F) -COO-C * H (CF ₃ ) (CH ₂ ) ₅ OC ₂ H ₅ 3B: C ₉ H ₁₉ -COO-Ph (2F) -COO-Ph-COO-C * H ( CH ₃ ) C ₆ H ₁₃ 3C: C ₉ H ₁₉ -COO-Ph (2F) -COO-Ph-COO-C * H (CH ₃ ) C ₈ H _{17 In the} formula, Ph is a 1,4-phenylene group, Ph (2F) is a 1,4-phenylene group substituted with fluorine at the 2-position, Ph (3F) is a 1,4-phenylene group substituted with fluorine at the 3-position, and C * is an asymmetric carbon.

The results of measuring the physical properties and the like of the obtained liquid crystal composition in the same manner as in Example 1 are shown in Tables 3 and 4, respectively. The temperature range of the ferrielectric phase of the obtained composition is preferable as a practical material, and it can be driven at a voltage of 8 V and exhibits a high-speed response, and thus can be suitably used for a TFT driving element.

[0039]

[Table 3] Phase Sequence Component Molar% Example 4 I (58) SA (43) SCγ * (<-20) Cr 1B / 2 / 3B = 37.5 / 25 / 37.5 Example 5 I (56) SA (43 ) SCγ * (<-20) Cr 1C / 2 / 3B = 37.5 / 25 / 37.5 Example 6 I (55) SA (42) SCγ * (<-20) Cr 1C / 2 / 3C = 37.5 / 25 / 37.5 1B I (90) SCA * (<-20) Cr 1C I (83) SC * (77) SCA * (<-50) Cr 3B I (5) SA (-29) Cr 3C I (19) SA (< -6) Cr

[0040]

[Table 4] Threshold voltage (V / μm) Response time Measurement temperature I II (μsec) (° C) Example 4 1.2 0.5 66 30 Example 5 1.0 0.5 64 30 Example 6 1.0 0.5 65 30 1B 4.2 ( * 1) 2.4 (* 1) * 2 30 1C 4.5 (* 1) 1.1 (* 1) * 2 30 * 1; Measured at ± 35V, 1Hz. * 2: Measurement cannot be performed because the threshold voltage is high.

Examples 7 to 9 and Comparative Example 1 An antiferroelectric liquid crystal (1C) or an antiferroelectric liquid crystal represented by the following chemical formula (1D) is added to a ferrielectric liquid crystal (2) and a chemical formula (3A).
Alternatively, a liquid crystal composition was prepared by mixing optically active compounds represented by the following chemical formulas (3D, 3E, 3F) in the proportions of 45, 25 and 30 mol%, respectively. 1D: C ₈ H ₁₇ -O-Ph-Ph-COO-Ph-COO-C * H (CF ₃ ) (CH ₂ ) ₅ OC ₂ H ₅ 3D: C ₉ H ₁₉ -COO-Ph-COO-Ph ( 3F) -COO-C * H (CH ₃ ) C ₆ H ₁₃ 3E: C ₁₀ H ₂₁ -COO-Ph (2F) -COO-Ph (3F) -COO-C * H (CH ₃ ) C ₈ H ₁₇ 3F: C ₁₀ H ₂₁ -COO-Ph (3F) -COO-Ph (3F) -COO-C * H (CH ₃ ) C ₈ H _{17 In the} formula, Ph is a 1,4-phenylene group, Ph (2F) Is a 1,4-phenylene group substituted with fluorine at the 2-position, Ph (3F) is a 1,4-phenylene group substituted with fluorine at the 3-position, and C * is an asymmetric carbon.

The results of measuring the physical properties of the obtained liquid crystal composition in the same manner as in Example 1 are shown in Tables 5 and 6, respectively. Among the obtained compositions, the ones of the examples have a temperature range of the ferri-dielectric phase which is preferable as a practical material.
Since it can be driven by the voltage of 3 and shows a high-speed response, it can be suitably used for a TFT driving element. However, the composition of Comparative Example 1 had a problem that the upper limit temperature of the ferrielectric phase was 39 ° C., which was slightly low, and it was a problem as a practical material.

[0043]

[Table 5] Phase series Component Molar% Example 7 I (60) SA (52) SCγ * (<-20) Cr 1C / 2 / 3D = 45/25/30 Example 8 I (54) SA (43 ) SCγ * (<-20) Cr 1C / 2 / 3E = 45/25/30 Comparative Example 1 I (51) SA (39) SCγ * (<-20) Cr 1C / 2 / 3F = 45/25/30 Example 9 I (71) SA (56) SCγ * (<-0) Cr 1D / 2 / 3A = 45/25/30 1D I (100) SA (93) SCA * (47) Cr 3D I (27) SA (21) SC * (19) SCA * (-7) SX (-38) Cr 3E I (19) SA (13) SCA * (1) Cr 3F I (1) SA (-7) Cr

[0044]

[Table 6] Threshold voltage (V / μm) Response time Measurement temperature I II (μsec) (° C) Example 7 1.2 0.4 81 30 Example 8 0.8 0.2 63 30 Comparative example 1 0.9 0.2 71 30 Example 9 1.4 0.3 69 30

Example 10 An antiferroelectric liquid crystal (1B) was mixed with a ferrielectric liquid crystal (2) and an optically active compound represented by the following chemical formula (3G) at a ratio of 60, 10 and 30 mol%. A liquid crystal composition was prepared. _{3G: C 10 H 21 -COO-} Ph-COO-Ph-COO-C * H (CH 3) C 6 H 13 in formula C * is an asymmetric carbon. Table 7 shows the results of identifying the phases of the obtained liquid crystal composition in the same manner as in Example 1. In addition, the results obtained by examining the optical response at 30 ° C by the following procedure are shown in Table 8.
It was shown to. Furthermore, FIG. 3 shows the optical response history with respect to the applied voltage.

The cell was manufactured by the following procedure, and the characteristics were measured under the following conditions. On a glass substrate with ITO electrodes,
An alignment film (polyimide, film thickness: about 30 nm) was coated, and only one of the pair of glass substrates was rubbed. Particle size
A pair of glass substrates were bonded via a 1.6 μm spacer to form a test cell. The cell thickness was 2 μm. The liquid crystal was heated to a temperature at which the liquid crystal was in an isotropic phase, and the liquid crystal was injected into the test cell by a capillary phenomenon. Then, the liquid crystal was aligned in parallel by slow cooling at a rate of 1 ° C./minute, and further cooled to 30 ° C. to measure the physical properties. Next, a ± 25 V, 1 Hz triangular wave voltage was applied to the test cell to drive it, and the change in transmitted light was examined. The threshold voltage I at which the transmitted light intensity changes from 0% to 90% by the phase transition from the antiferroelectric phase to the ferroelectric phase, and the threshold value by the phase transition from the ferroelectric phase to the antiferroelectric phase Threshold voltage when the voltage decreases from 100% to 90%
It was defined as II and the threshold voltage was measured. The response time was measured by defining the time required for the transmitted light intensity to change from 0% to 90% by applying a pulse voltage of 35 V and a frequency of 10 Hz.

Examples 11 to 14 and Comparative Example 2 An antiferroelectric liquid crystal (1A, 1B, 1C) or an antiferroelectric liquid crystal represented by the following chemical formula (1F), a ferrielectric liquid crystal (2) and an optically active substance were used. A liquid crystal composition was prepared by mixing the compound (3A, 3B) or an optically active compound represented by the following chemical formula (3H, 3I, 3J). Table 7 shows each composition component and composition ratio (mol%). 3H: C ₁₀ H ₂₁ -COO-Ph-COO-Ph-COO-C * H (CH ₃ ) C ₄ H ₉ 3I: C ₁₁ H ₂₃ -COO-Ph (2F) -COO-Ph-COO-C * H (CH ₃ ) C ₆ H ₁₃ 3J: C ₁₀ H ₂₁ -COO-Ph-COO-Ph-COO-C * H (CH ₃ ) C ₈ H ₁₇ 1E: C ₈ H ₁₇ -O-Ph-Ph- COO-Ph (3F) -COO-C * H (CF ₃ ) (CH ₂ ) ₇ OC ₂ H _{5 In the} formula, Ph is a 1,4-phenylene group, and Ph (3F) is a fluorine-substituted 1 at the 3-position. 4-phenylene group, C * represents an asymmetric carbon.

The temperature range of the antiferroelectric phase of the composition obtained from Table 7 was preferable as a practical material. Also,
From Table 8, the compositions of Examples 10-14 have low threshold voltage,
It was a material exhibiting high-speed response. From these, Example 10
The compositions of -14 were materials suitable for use in simple matrix drives. On the other hand, as shown in Table 8, the composition of Comparative Example 2 had a problem in high-speed response.

[0049]

[Table 7] Phase Sequence Component Molar% Example 10 I (68) SA (62) SC * (57) SCA * (<-30) Cr 1B / 2 / 3G = 60/10/30 〃 11 I (71 ) SA (61) SC * (60) SCA * (<-20) Cr 1B / 2 / 3H = 55/15/30 〃 12 I (61) SA (53) SC * (47) SCA * (<-20 ) Cr 1C / 2 / 3I = 60/10/30 〃 13 I (64) SA (57) SC * (54) SCA * (<-20) Cr 1B / 2 / 3J = 55/15/30 〃 14 I (63) SA (55) SC * (50) SCA * (<-20) Cr 1C / 2 / 3B = 60/10/30 Comparative Example 2 I (61) SA (50) SCγ * (47) SCA * ( <-20) Cr 1E / 2 / 3A = 45/25/30 3G I (28) SA (22) SCA * (12) Cr 3H I (30) SA (22) SCγ * (18) SCA * (<- 10) Cr 3I I (25) SA (15) SCA * (13) Cr 3J I (21) SA (13) SCA * (12) Cr 1E I (79) SA (78) SCA * (30) SIA * ( <-40) Cr

[0050]

[Table 8] Threshold voltage (V / μm) Response time Measurement temperature I II (μsec) (℃) Example 10 3.0 0.4 23 30 〃 11 3.5 0.4 23 30 〃 12 3.2 0.4 26 30 〃 13 3.0 0.3 25 30〃 14 3.2 0.4 17 30 Comparative example 2 3.3 0.4 205 30 1E 7.9 (* 1) 4.3 (* 1) * 2 30 * 1; Measured at ± 35V, 1Hz. * 2: The threshold voltage was too high to measure.

[Brief description of drawings]

FIG. 1 is a diagram showing a molecular arrangement of a ferrielectric phase. FI
(+) And FI (-) indicate a ferrielectric state, and FO (+) and FO (-) indicate a ferroelectric state.

2 is a diagram showing an optical response of the liquid crystal composition of Example 1 to a triangular wave voltage. FIG.

3 is a diagram showing an optical response to the liquid crystal composition of Example 10. FIG.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Maki Ito 22 Wada, Tsukuba, Ibaraki Mitsubishi Gas Chemical Co., Ltd.

Claims (20)

[Claims] 1. An antiferroelectric liquid crystal represented by the following general formula (1), a ferrielectric liquid crystal represented by the following chemical formula (2) and an optically active compound represented by the following general formula (3) are mixed. A liquid crystal composition comprising: Embedded image (In the formula, R and R ′ are linear alkyl groups, m is an integer of 5 or more, and n is
Is an integer of 1 or more, X, Y, Z are fluorine atoms or hydrogen atoms, p is an integer of 4 or more, and C * is an asymmetric carbon). 2. The liquid crystal composition according to claim 1, wherein R in the general formula (1) has 6 to 10 carbon atoms. 3. The liquid crystal composition according to claim 1, wherein m in the general formula (1) is an integer of 5. 4. The liquid crystal composition according to claim 1, wherein R ′ in the general formula (3) has 8 to 12 carbon atoms. 5. The liquid crystal composition according to claim 1, wherein p in the general formula (3) is an even number of 4 to 10. 6. The antiferroelectric liquid crystal represented by the general formula (1) is 20 to 70 mol%, and the ferrielectric liquid crystal represented by the chemical formula (2) is 5 to 50 mol%. The liquid crystal composition according to claim 1, wherein the optically active compound represented by (3) is 10 to 40 mol%. 7. The liquid crystal composition according to claim 1, wherein the liquid crystal composition has a ferrielectric phase at least in a temperature range of 0 to 40 ° C. 8. The liquid crystal composition according to claim 1, wherein the liquid crystal composition has a ferrielectric phase at least in a temperature range of −20 ° C. to + 50 ° C. 9. A chiral smectic C phase or a smectic A phase on the high temperature side of the ferrielectric phase.
Or the liquid crystal composition according to item 8. 10. The liquid crystal composition according to claim 7, wherein a threshold voltage when the ferrielectric phase transitions from the ferrielectric state to the ferroelectric state is 5 V / μm or less. 11. The liquid crystal composition according to claim 7, wherein the threshold voltage when the ferrielectric phase transitions from the ferrielectric state to the ferroelectric state is 2 V / μm or less. 12. A liquid crystal composition according to claim 7,
An active matrix liquid crystal display device characterized by being sandwiched between substrates on which a non-linear active device such as a thin film transistor or a diode is installed for each pixel. 13. The liquid crystal display element according to claim 12, wherein the liquid crystal is driven by the voltage of the nonlinear active element by switching to two ferrielectric states, two ferroelectric states, and an intermediate state thereof. 14. The liquid crystal composition according to claim 1, wherein the liquid crystal composition has an antiferroelectric phase at least in a temperature range of 0 to 40 ° C. 15. The liquid crystal composition according to claim 1, wherein the liquid crystal composition has an antiferroelectric phase at least in a temperature range of −20 ° C. to + 50 ° C. 16. A chiral smectic C phase or a smectic A phase on the high temperature side of the antiferroelectric phase.
The liquid crystal composition according to 4 or 15. 17. The liquid crystal composition according to claim 14, wherein the threshold voltage when the antiferroelectric phase transitions from the antiferroelectric state to the ferroelectric state is 10 V / μm or less. 18. The liquid crystal according to claim 14 or 15, wherein when the liquid crystal composition has an antiferroelectric phase, the threshold voltage when transitioning from an antiferroelectric state to a ferroelectric state is 5 V / μm or less. Composition. 19. A simple matrix liquid crystal display device, wherein the liquid crystal composition according to claim 14 or 15 is sandwiched between substrates in which scanning electrodes and signal electrodes are arranged on a matrix. 20. The liquid crystal display device according to claim 19, wherein the driving by the voltage of the simple matrix liquid crystal device is switched between one antiferroelectric state and two ferroelectric states.