JPH0959640A - Ferrielectric liquid crystal composition and liquid crystal display element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a novel ferrielectric liq. crystal compsn. which can be suitably used for AM drive. SOLUTION: This compsn. is prepd. by mixing a phenyl ester compd. represented by formula I (wherein (m) is an integer of 3-12; (n)is an integer of 1-11; X<1> and X<2> are each H or F provided at least one of them is H; and A is H or CH3 ) with a liq. crystal compd. having a ferrielectric phase and represented by formula II (wherein R 15 a 7-12C linear alkyl; Y<1> and Y<2> are each H or F provided at least one of them is H; and (s) and (t) are each an integer of 2-4).

Description

Detailed Description of the Invention

[0001]

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

[0002]

2. Description of the Related Art Liquid crystal display devices have been used for various small display devices to date because of their low voltage operability, low power consumption, and thin display capability. However, with the recent 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. That is, a large display capacity, full-color display, wide viewing angle, high-speed response, high contrast, etc. are required. Liquid crystal display systems (liquid crystal drive systems) that meet such demands include STN liquid crystal display devices that are currently driven by a simple matrix using a nematic liquid crystal material and TFT or MIM liquid crystal display devices that are driven by an active matrix.

In these display systems, a slow response speed and a narrow viewing angle have recently become serious problems. That is, the response speed is on the order of several tens of ms, and good image quality cannot be obtained when displaying a moving image. In addition, since the display is performed by using the twisted state (twist alignment) of the liquid crystal molecules, the viewing angle is necessarily narrowed. Especially when gradation display is performed, the viewing angle sharply narrows, and depending on the viewing angle,
The contrast ratio, color, etc. will change. Although this problem is being strongly improved at present, the fundamental solution is difficult as long as nematic liquid crystal is used. Therefore, CR
At present, the display quality equal to or higher than T is not obtained.

In order to solve these problems, an AM adopting a ferroelectric liquid crystal or an antiferroelectric liquid crystal instead of the TN liquid crystal.
Panel proposals have also been made in recent years (Japanese Unexamined Patent Publication No.
JP-A-5-150257, JP-A-6-95080, etc.), and these liquid crystals also have the following problems, and there are currently many barriers to practical use. (1) Ferroelectric liquid crystals have spontaneous polarization, but since spontaneous polarization is always present, image sticking easily occurs and driving is difficult. Further, since the ferroelectric liquid crystal can display only binary images of black and white when displaying in the surface stabilization mode,
Gradation display is extremely difficult. Special consideration is required when performing gradation display (for example, ferroelectric liquid crystal device using monostable; Keiichi NITO et.al, SID'94, Preprin
t, p48), which requires the development of advanced practical technology.

(2) Since the antiferroelectric liquid crystal has no permanent spontaneous polarization, the problem of image sticking described in (1) above is avoided. In AM drive, at least 10
A liquid crystal material that can be driven at V or lower is required, but an antiferroelectric liquid crystal generally has a large 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.

A liquid crystal compound having a ferrielectric phase is considered as a new material suitable for AM driving that can solve this problem. A liquid crystal compound having a ferrielectric phase (= SCγ *) was developed in 1989 by 4- (4-octyloxyphenyl) benzoic acid.
-4- (1-methylheptyloxycarbonyl) phenyl (abbreviation
First discovered in MHPOBC (Japanese Journal
of Applied Physics, Vol.29, No.1, 1990, pp.L131-13
7).

MHPOBC has the formula: C ₈ H ₁₇ -O-Ph-Ph-COO-Ph-COO
_{-C * H (CH 3) C} 6 H 13 (Ph in the formula 1,4-phenylene group, C * is an asymmetric carbon, the alkyl group is a straight chain alkyl group) is represented by, the phase sequence is Cr ( 30) SIA * (65) SCA * (118) SCγ * (119) SC * (121) SCα * (12
2) SA (147) I (where Cr is the crystalline phase, SIA * is the chiral smectic IA
Phase, SCA * is the chiral smectic CA phase (antiferroelectric phase),
SCγ * is the chiral smectic Cγ phase (ferrielectric phase), SC * is the chiral smectic C phase (ferroelectric phase),
SCα * indicates a chiral smectic Cα phase, SA indicates a smectic A phase, I indicates an isotropic phase, and parentheses indicate a phase transition temperature (° C). )

In order to explain the state of the liquid crystal in the ferrielectric phase, FIG. 1 shows an example of the state of molecular alignment in the ferrielectric phase, and FIG. 2 shows an example of the optical response of the ferrielectric phase to a triangular wave. In the ferrielectric phase, the molecular arrangement of FI (+) (when the applied voltage is positive) or FI (-) (when the applied voltage is negative) in Fig. 1 is used. In the absence of electric field, FI
Since (+) and FI (-) are equivalent, they are considered to coexist. Therefore, the average optical axis is in the direction of the normal to the layer, and is in a dark state under the conditions of the polarizing plate shown in FIG. 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, in the ferrielectric phase, like the antiferroelectric phase, it is possible to escape from the burn-in phenomenon that occurs in the ferroelectric phase.

When an electric field is applied to the ferrielectric phase, a region having an extinction position at a voltage lower than that at which the ferroelectric state is reached.
(Domain) appears. This region has an optical axis in a direction inclined from the normal direction, though not so much as in the ferroelectric state. This intermediate state is FI (+) or FI
(-) it is conceivable that. In this case, in FIG. 2, not a continuous change in transmitted light intensity between voltages 0 V and 4 V, but a stepwise change in transmitted light intensity should be observed. However, continuous transmitted light intensity was observed in FIG. This is probably because the threshold voltage from FI (+) to FO (+) or from FI (-) to FO (-) is not clear. In the present invention, a liquid crystal phase in which the above intermediate state is always observed is called a ferri-dielectric phase, and a liquid crystal having the widest phase is called a ferri-dielectric liquid crystal or a ferri-dielectric liquid crystal composition.

When the applied voltage is further increased, the ferroelectric phase FO (+) or FO (-), which is in a stable state, undergoes a phase transition depending on the direction of the electric field. That is, FO (+) or FO (-) is the one in which the transmitted light intensity is saturated (the left and right flat portions) in FIG.
It is. 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 (-). As described above, in the ferrielectric phase, the coexistence state of FI (+) and FI (-) is dark and the ferroelectric state is
FO (+) and FO (-) can be used as light.

In the conventional ferroelectric liquid crystal, switching between FO (+) and FO (-) was performed, whereas in the ferrielectric phase, FI was used.
It has a major feature of switching between four states of (+), 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 phase 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. The hysteresis width has a strong tendency to be narrow and has a property suitable for AM driving and gradation display in AM driving. In addition, the threshold voltage, which is the voltage that changes from the ferrielectric state to the ferroelectric state when the ferrielectric phase changes with voltage, tends to be smaller than that in the antiferroelectric phase. It can be said that the dielectric phase is a liquid crystal phase suitable for AM driving.

[0014]

However, the number of liquid crystal compounds having a ferri-dielectric phase and ferri-dielectric liquid crystals synthesized so far is extremely small. Further, the liquid crystal compound having a ferri-dielectric phase and the ferri-dielectric liquid crystal simple substance known in the related art are considered to have a temperature range of the ferri-dielectric phase, a hysteresis, a response speed, and a threshold voltage in consideration of application to an AM driving element. Nothing satisfactory has been found. Generally, the driving voltage in the AM driving element is low, and at least 10
It is necessary to be able to drive at high speed with an applied voltage of V or less. From this point of view, the conventionally obtained ferrielectric liquid crystal alone has a problem in response at a drive voltage of 10 V or less, and improvement in this aspect is strongly desired. The present invention
The present invention has been made from this viewpoint, and provides a new ferrielectric liquid crystal composition excellent in low-voltage drivability that can be suitably used for AM driving.

[0015]

Means for Solving the Problems That is, according to the present invention, a phenyl ester compound represented by the following general formula (1) is mixed with a liquid crystal compound having a ferrielectric phase represented by the following general formula (2). A ferrielectric liquid crystal composition comprising:

[0016]

Embedded image (M in the formula (1) is an integer of 3 to 12, n is an integer of 1 to 11,
X ¹ and X ² are H or one of them is an F atom, A is H or --CH ₃
Group. In formula (2), R is a straight-chain alkyl group having 7 to 12 carbon atoms, Y ¹ and Y ² are H or one of them is an F atom, and s is 2 to 4
, T is an integer from 2 to 4. )

The phenyl ester compound represented by the general formula (1) of the present invention preferably has no liquid crystal phase when A is H atom. When A is CH ₃ , n
Is preferably 4-8.

In the ferrielectric liquid crystal composition of the present invention, when s in the general formula (3) is 4, t is an integer of 2 to 4,
A liquid crystal compound in which R has 7 to 12 carbon atoms, when s is 3,
A liquid crystal compound in which t is an integer of 2 to 4 and R has 9 to 12 carbon atoms, and when s is 2, a liquid crystal compound in which t is 2 and R has 8 and 9 carbon atoms is a ferrielectric phase Is preferred. The mixing amount of the phenyl ester compound represented by the general formula (1) is in the range of 1 to 40 mol%, preferably 10 to 30 mol% of the ferrielectric liquid crystal composition, and particularly at a temperature of 0 ° C. to 40 ° C. ℃ range, more preferably 0 ℃ ~ 50
A ferrielectric liquid crystal composition exhibiting a ferrielectric phase in the range of ° C is preferred.

Further, the threshold voltage at the time of transition from the ferrielectric phase to the ferroelectric phase of the ferrielectric liquid crystal composition is 5
It is preferably V / μm or less, and particularly preferably 3 V / μm or less. Further, the ferrielectric liquid crystal composition of the present invention can be sandwiched between substrates provided with non-linear active elements such as thin film transistors or diodes for each pixel to form an active matrix liquid crystal display element that can be suitably driven in a wide temperature range. , Driving a liquid crystal with a non-linear active element by two ferrielectric states and two ferroelectric states,
And switching to the intermediate state.

The liquid crystal compound having a ferrielectric phase represented by the general formula (2) used in the present invention can be easily produced by the method already shown by the present inventors (JP-A-4-198155). . The outline is as follows. (1) AcO-Ph (F) -COOH + SOCl ₂ → AcO-Ph (F) -COCl (2) (1) + R * OH → AcO-Ph (F) -COOR * (3) (2) + (PhCH ₂ NH ₂ ) → HO-Ph (F) -COOR * (4) R'O-Ph-Ph-COOH + SOCl ₂ → R'O-Ph-Ph-COCl (5) (3) + (4 ) → liquid crystal compound In the formula, Ac is a CH ₃ CO- group, Ph is a 1,4-phenylene group, Ph (F)
Represents a 1,4-phenylene group which may be F-substituted at the 2- or 3-position, R * represents an optically active alcohol residue, and R ′ represents a linear alkyl group.

The above manufacturing method will be briefly described below. (1) is a chlorination reaction of fluorine-substituted or unsubstituted p-acetoxybenzoic acid with thionyl chloride. (2) is esterification by reaction of the chlorinated compound (1) with an optically active alcohol. (3) is the deacetylation of ester (2). (4) is a chlorination reaction of alkyloxybiphenylcarboxylic acid. (5) is the formation of liquid crystal by the reaction of phenol (3) and chlorinated compound (4).

Further, the phenyl ester compound used in the present invention can be easily produced by the method already disclosed by the present inventors (Japanese Patent Application No. 7-967497). The outline is as follows. (a) HO-Ph (X) -COOH + RCOCl → RCOO-Ph (X) -COOH (b) (a) + SOCl ₂ → RCOO-Ph (X) -COCl (c) (b) + ROH → RCOO -Ph (X) -COO-R In the above formula, Ph is 1,4-phenylene group and Ph (X) is 2-
Or a 1,4-phenylene group which may be F-substituted at the 3-position,
R represents a linear alkyl group which may have asymmetric carbon.

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 the formation of the desired product by esterification by reaction of the chlorinated compound (b) with a linear alcohol or an optically active 2-alkanol.

[0024]

INDUSTRIAL APPLICABILITY The present invention can provide an antiferroelectric liquid crystal composition or a ferrielectric liquid crystal composition obtained by mixing a novel phenyl ester compound with it. Further, the novel antiferroelectric liquid crystal composition provided by the present invention has an antiferroelectric phase in a wide temperature range and exhibits a high-speed response, and therefore an antiferroelectric liquid crystal display device having high display quality can be obtained. realizable. In addition, the novel ferrielectric liquid crystal composition provided by the present invention has a ferrielectric phase in a wide temperature range, exhibits a high-speed response, and has no hysteresis, so that an active matrix liquid crystal display device having high display quality can be obtained. realizable.

[0025]

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 In a ferrielectric liquid crystal (2A) represented by the following chemical structural formula,
Phenyl ester compound (1
15 mol% of A) was mixed to prepare a liquid crystal composition. 1A: C ₃ H ₇ -COO-Ph (2F) -COO-CH ₂ CH ₂ CH ₃ (Formula (1); m = 3, A = H, X ¹ = H, X ² = F, n = 2) 2A: C ₉ H ₁₉ -O-Ph-Ph-COO-Ph (3F) -COO-C * H (CF ₃ ) (CH ₂ ) ₄ OC ₂ H ₅ (Formula (3); R = C ₉ H ₁₉ , Y ¹ = H, Y ² = F, s = 4, t = 2)

The liquid crystal phase is identified by texture observation, conoscopic image observation, DSC (differential differential scanning calorimeter) measurement, and a region having an extinction position between the layer normal direction and the optical axis direction of the ferroelectric state ( Confirmation of existence of domain), that is, intermediate state (FI (±))
Was observed. Observation of a conoscopic image is a powerful means for observing a ferrielectric phase. Observation of the conoscopic image was according to the literature (J. Appl. Phys. 31. 793 (1992)). Ordinary parallel alignment cell texture observation, conoscopic observation and DSC measurement, and intermediate state observation, that is, the existence of a region (domain) having an extinction position between the layer normal direction and the ferroelectric state optical axis direction is recognized. Based on the above, the phase series of the liquid crystal composition of this example was determined. The results are shown in Table 1.

Next, the optical response of the obtained ferrielectric liquid crystal was examined. The cell was produced by the following procedure. Insulating film (SiO ₂ ;
A glass substrate with an ITO electrode (thickness: 50 nm) was coated with polyimide (thickness: about 80 nm), and only one of the pair of glass substrates was rubbed. A pair of glass substrates were bonded together via a spacer having a particle diameter of 1.6 μm 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. Thereafter, the liquid crystal was gradually cooled at a rate of 1 ° C./min to parallel align the liquid crystal.

Next, at 30 ° C., ± 10 V was applied to the test cell,
A triangular wave voltage of 50 mHz was applied and driving was performed, and changes in transmitted light were investigated. The minimum transmitted light intensity is 0% and the maximum transmitted light intensity is
Assuming 100%, the threshold voltage I
The threshold voltage was measured with the threshold voltage II defined as the voltage at which the transmitted light intensity becomes 90% when the phase transition from the ferroelectric phase to the ferrielectric phase occurs. The response time was measured by defining the time required for a 90% change in transmitted light intensity when a pulse voltage of 8 V and a frequency of 10 Hz was applied. The results are shown in Table 2.

Examples 2 to 5 The ferrielectric liquid crystal (2A) used in Example 1 was prepared by adding the phenyl ester compound (1B, 1C, 1D,
1E) was mixed in an amount of 15 mol% to prepare a liquid crystal composition. 1B: C ₅ H ₁₁ -COO-Ph (2F) -COO-CH ₂ (CH ₂ ) ₅ CH ₃ (equation (1); m = 5, A = H, X ¹ = H, X ² = F, n = 6) 1C: C ₇ H ₁₅ -COO-Ph (2F) -COO-CH ₂ (CH ₂ ) ₇ CH ₃ (Formula (1); m = 7, A = H, X ¹ = H, X ² = F, n = 8) 1D: C ₅ H ₁₁ -COO-Ph (2F) -COO-CH ₂ (CH ₂ ) ₃ CH ₃ (Formula (1); m = 5, A = H, X ¹ = H, X ² = F, n = 4) 1E: C ₇ H ₁₅ -COO-Ph (2F) -COO-CH ₂ (CH ₂ ) ₃ CH ₃ (Formula (1); m = 7, A = H, X ¹ = H, X ² = F, n = 4)

Example 6 A liquid crystal composition was prepared by mixing 20 mol% of the phenyl ester compound (1G) represented by the following chemical structural formula with the ferrielectric liquid crystal (2A) used in Example 1. 1F: C ₉ H ₁₉ -COO-Ph (2F) -COO-CH ₂ (CH ₂ ) ₅ CH ₃ (Formula (1); m = 9, A = H, X ¹ = H, X ² = F, n = 6) With respect to the compositions of Examples 2 to 6, the results of making the identification of the liquid crystal phase and the other physical property measurements the same as in Example 1 are shown in Tables 1 and 2.

[0031]

[Table 1] Phase series Component Molar ratio Liquid crystal 2A Cr (* 1) SCγ * (89) SA (91) I Example 1 Cr (* 1) SCγ * (73) SA (85) I 2A / 1A = 85 / 15〃 2 Cr (* 1) SCγ * (70) SA (79) I 2A / 1B = 85/15 〃 3 Cr (* 1) SCγ * (70) SA (78) I 2A / 1C = 85/15 〃 4 Cr (* 1) SCγ * (72) SA (81) I 2A / 1D = 85/15 〃 5 Cr (* 1) SCγ * (71) SA (80) I 2A / 1E = 85/15 〃 6 Cr (* 1) SCγ * (64) SA (73) I 2A / 1F = 80/20 Cr is crystalline phase, SCγ * is ferrielectric phase, SA is smectic A phase, I is isotropic phase, and The numbers in parentheses in the phase series indicate the transition temperature (° C). In addition, (* 1) indicates that the melting point was not confirmed by DSC (minimum temperature -50 ° C).

[0032]

[Table 2] Threshold voltage (V / μm) Response time Measurement temperature I II (μsec) (℃) Liquid crystal 3A 1.5 1.4 88 30 Example 1 1.2 1.2 70 30 〃 2 1.4 1.4 70 30 〃 3 1.4 1.4 71 30 〃 4 1.4 1.4 31 30 〃 5 1.4 1.4 80 30 〃 6 1.0 1.0 30 30

Example 7 A ferrielectric liquid crystal (2B) represented by the following chemical structural formula was added:
The phenyl ester compound (1C) obtained in Example 5 above was used in 20
A mol% was mixed to prepare a liquid crystal composition. 2B: C ₉ H ₁₉ -O-Ph-Ph-COO-Ph (3F) -COO-C * H (CF ₃ ) (CH ₂ ) ₃ OC ₂ H ₅ (Formula (2); R = C ₉ H ₁₉ , Y ¹ = H, Y ² = F, s = 3, t = 2) The results of identification of the liquid crystal phase and other physical property measurements performed in the same manner as in Example 1 are shown in Tables 3 and 4.

Examples 8 and 9 and Reference Example 1 In the ferrielectric liquid crystal (2B) used in Example 7, a phenyl ester compound (1G, 1H, 1I) represented by the following chemical structural formula was added.
Were mixed in an amount of 25 mol% to prepare a liquid crystal composition. 1G: C ₉ H ₁₉ -COO-Ph (2F) -COO-CH ₂ (CH ₂ ) ₇ CH ₃ (Formula (1); m = 9, A = H, X ¹ = H, X ² = F, n = 8) 1H: C ₁₀ H ₂₁ -COO-Ph (2F) -COO-CH ₂ (CH ₂ ) ₇ CH ₃ (Formula (1); m = 10, A = H, X ¹ = H, X ² = F, n = 8) 1I: C ₁₀ H ₂₁ -COO-Ph (2F) -COO-CH ₂ (CH ₂ ) ₉ CH ₃ (Formula (1); m = 10, A = H, X ¹ = H, X ² = F, n = 10) Tables 3 and 4 show the results of identification of the liquid crystal phase and other physical property measurements performed in the same manner as in Example 1. In Reference Example 1, the smectic A phase was not present.

[0035]

[Table 3] Phase series component Molar ratio Liquid crystal 2B Cr (40) SCγ * (SA (103) I Example 7 Cr (* 1) SCγ * (72) SA (83) I 2B / 1C = 80 / 20〃 8 Cr (* 1) SCγ * (64) SA (75) I 2B / 1G = 75/25 〃 9 Cr (* 1) SCγ * (55) SA (79) I 2B / 1H = 75/25 Reference Example 1 Cr (* 1) SCγ * (50) I 2B / 1I = 75/25 The descriptions in the table are the same as those in Table 5.

[0036]

[Table 4] Threshold voltage (V / μm) Response time Measurement temperature I II (μsec) (℃) Liquid crystal 3B 1.3 1.2 101 30 Example 7 1.1 1.0 58 30 〃 8 1.1 1.1 23 30 〃 9 1.4 1.4 61 30 Reference example 1 1.3 1.3 54 30

Examples 10 and 11 To the ferrielectric liquid crystal (2A) used in Example 1, the phenyl ester compound (1J, 1K) represented by the following chemical structural formula was added.
A mol% was mixed to prepare a liquid crystal composition. 1J: C ₉ H ₁₉ -COO-Ph-COO-CH ₂ (CH ₂ ) ₇ CH ₃ (Formula (1); m = 9, A = H, X ¹ = H, X ² = H, n = 8) 1K: C ₅ H ₁₁ -COO-Ph-COO-CH ₂ (CH ₂ ) ₃ CH ₃ (Formula (1); m = 5, A = H, X ¹ = H, X ² = H, n = 4)

Examples 11 and 12 Ferrielectric liquid crystal (2C, 2D) represented by the following chemical structural formula
A phenyl ester compound (E1) was mixed with each of 20 mol% to prepare a liquid crystal composition. 2C: C ₉ H ₁₉ -O-Ph-Ph-COO-Ph-COO-C * H (CF ₃ ) (CH ₂ ) ₄ OC ₂ H ₅ (Formula (2); R = C ₉ H ₁₉ ,, Y ¹ = H, Y ² = H, s = 4, t = 2) 2D: C ₈ H ₁₇ -O-Ph-Ph-COO-Ph (3F) -COO-C * H (CF ₃ ) (CH ₂ ) ₂ OC ₂ H ₅ (Formula (2); R = C ₈ H ₁₇ , Y ¹ = H, Y ² = F, s = 2, t = 2) Liquid crystal compositions prepared in Examples 10 to 12 Table 5 and 6 show the results obtained by making the same as Example 1 with respect to the identification and the other physical property measurements.

[0039]

[Table 5] Phase series Component Molar ratio Example 10 Cr (* 1) SCγ * (62) SA (72) I 2A / 1J = 80/20 〃 11 Cr (* 1) SCγ * (55) SA (72 ) I 2A / 1K = 80/20 〃 12 Cr (* 1) SCγ * (60) SA (80) I 2C / 1F = 80/20 〃 13 Cr (* 1) SCγ * (70) SA (85) I 2D / 1F = 80/20 Liquid crystal 2C Cr (41) SCγ * (95) SA (103) I Liquid crystal 2D Cr (58) SCγ * (104) SA (108) I The description in the table is the same as in Table 1. .

[0040]

[Table 6] Threshold voltage (V / μm ) Response time Measurement temperature I II (μsec) (℃) Example 10 1.4 1.1 50 30 〃 11 1.1 1.1 59 30 〃 12 1.1 1.1 48 30 〃 13 2.2 1.5 75 30 LCD 2C 1.8 1.7 165 50 LCD 2D 1.2 1.2 33 50

Example 14 A liquid crystal composition was prepared by mixing 15 mol% of a phenyl ester compound (1F) with a ferrielectric liquid crystal (2E) represented by the following chemical structural formula. 2E: C ₉ H ₁₉ -O-Ph-Ph-COO-Ph (2F) -COO-C * H (CF ₃ ) (CH ₂ ) ₄ OC ₂ H ₅ (Formula (2); R = C ₈ H ₁₇ , Y ¹ = F, Y ² = H, s = 4, t = 2)

Examples 15 and 16 To the ferrielectric liquid crystal (2A) used in Example 1, the phenyl ester compound (1L, 1M) represented by the following chemical structural formula was added.
A mol% was mixed to prepare a liquid crystal composition. 1L: C ₉ H ₁₉ -COO-Ph (2F) -COO-C * H (CH ₃ ) (CH ₂ ) ₄ CH ₃ (Formula (1); m = 9, A = CH ₃ ,, X ¹ = H, X ² = F, n = 5) 1M: C ₉ H ₁₉ -COO-Ph (2F) -COO-C * H (CH ₃ ) (CH ₂ ) ₅ CH ₃ (Formula (1); m = 9, A = CH ₃ , X ¹ = H, X ² = F, n = 6) For the liquid crystal compositions prepared in Examples 14 to 16, the results of identifying the liquid crystal phase and measuring other physical properties were the same as in Example 1. The results are shown in Tables 7 and 8.

[0043]

[Table 7] Phase series Component Molar ratio Example 14 Cr (* 1) SCγ * (56) SA (72) I 2E / 1F = 85/15 Liquid crystal 2E Cr (3) SCγ * (68) SA (87) I Example 15 Cr (* 1) SCγ * (68) SA (75) I 2A / 1L = 90/10 〃 16 Cr (* 1) SCγ * (73) SA (74) I 2A / 1M = 90/10 The description in the table is the same as in Table 1.

[0044]

[Table 8] Threshold voltage (V / μm) Response time Measurement temperature I II (μsec) (℃) Example 14 0.9 0.9 61 30 Liquid crystal 2E 1.2 1.2 33 50 Example 15 1.1 1.1 56 30 〃 16 1.2 1.2 61 30

[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.

FIG. 2 shows an optical response of a ferrielectric phase to a triangular wave.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Teruyo Toyama 22nd Wadai, Tsukuba, Ibaraki Pref. Mitsubishi Gas Chemical Company, Ltd.

Claims (14)

[Claims] 1. A ferrielectric liquid crystal composition obtained by mixing a phenyl ester compound represented by the following general formula (1) with a liquid crystal compound having a ferrielectric phase represented by the following general formula (2). Embedded image (M in the formula (1) is an integer of 3 to 12, n is an integer of 1 to 11,
X ¹ and X ² are H or one of them is an F atom, A is H or --CH ₃
Group. In formula (2), R is a straight-chain alkyl group having 7 to 12 carbon atoms, Y ¹ and Y ² are H or one of them is an F atom, and s is 2 to 4
, T is an integer from 2 to 4. ) 2. The phenyl ester compound according to claim 1, wherein the compound represented by the general formula (1) has no liquid crystal phase. _3. When A in the general formula (1) is CH ₃ , n is 4
The phenyl ester compound according to claim 1, which is an integer of -8. 4. When s in the general formula (2) is 4, t is 2 to
The ferrielectric liquid crystal composition according to claim 1, wherein the integer of 4 and the carbon number of R are 7 to 12. 5. When s in the general formula (2) is 3, t is 2 to
The ferrielectric liquid crystal composition according to claim 1, wherein R is an integer of 4 and has 9 to 12 carbon atoms. 6. The ferrielectric liquid crystal composition according to claim 1, wherein when s in the general formula (2) is 2, the carbon number of R is 8 or 9. 7. The ferrielectric liquid crystal composition according to claim 1, wherein when s in the general formula (2) is 2, t is 2. 8. The ferrielectric liquid crystal composition according to claim 1, wherein the amount of the phenyl ester compound represented by the general formula (1) mixed is in the range of 1 to 40 mol% of the ferrielectric liquid crystal composition. 9. The ferrielectric liquid crystal composition according to claim 1, wherein the amount of the phenyl ester compound represented by the general formula (1) mixed is in the range of 10 to 30 mol% of the ferrielectric liquid crystal composition. 10. The ferrielectric liquid crystal composition according to claim 1, wherein the ferrielectric liquid crystal composition has a ferrielectric phase at least at a temperature of 0 ° C. to 40 ° C. 11. The threshold voltage when the ferrielectric liquid crystal composition transitions from the ferrielectric phase to the ferroelectric phase is 5 V /
The ferrielectric liquid crystal composition according to claim 1, having a thickness of not more than μm. 12. The threshold voltage when the ferrielectric liquid crystal composition transitions from the ferrielectric phase to the ferroelectric phase is 3 V /
The ferrielectric liquid crystal composition according to claim 1, having a thickness of not more than μm. 13. An active matrix liquid crystal display device comprising a ferri-dielectric liquid crystal according to claim 1 sandwiched between substrates provided with a non-linear active device such as a thin film transistor or a diode for each pixel. 14. Driving a liquid crystal using a non-linear active element with two ferrielectric states and two ferroelectric states,
And switching to an intermediate state thereof.
An active matrix liquid crystal display device as described in the above.