JPH0940960A - Ferrielectric liquid crystal composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a ferrielectric liquid crystal composition desirably used in a liquid crystal display by mixing a liquid crystal compound having a ferrielectric phase in the phase series with a specified phenyl ester compound. SOLUTION: Ninety five (95) to 50mol% liquid crystal compound having a ferrielectric phase in the phase series and represented by formula I (wherein R is a 6-12C linear alkyl; X and Y are each H or either of them is F; A is CF3 or C2 F5 ;(m) is 2-4; (n) is 2-4; and the carbon atom marked with C* is an asymmetrical carbon) is mixed with a phenyl ester compound having a smectic A phase and represented by formula II (wherein R<1> is a 5-12C linear alkyl; R<2> is a 1-15C linear alkyl; X<1> and X<2> are each H or either of them is F; Y<1> and Y<2> are each H or either of them is F; and A<1> is H or CH3 ) to obtain a ferrielectric liquid crystal composition. This composition shows a ferrielectric phase in at least a temperature region of 0-40 deg.C and has at least a smectic A phase on the higher-temperature side of the ferrielectric phase. The threshold voltage of transition from the ferrielectric state to the ferroelectric state is desirably 3V/μm or below.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel liquid crystal compound having a ferri-dielectric phase which is suitable for use in an active matrix type liquid crystal display device driven for each pixel.

[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.
An active matrix (AM) display element, in which a TFT (TFT) or a diode (MIM) is formed and a liquid crystal is independently driven for each pixel, has been proposed and implemented. Although this display method has problems such as difficulty in cost reduction due to low manufacturing yield and difficulty in increasing the screen size, it surpasses the STN display method, which was the mainstream in the past, due to its high display quality, and CRT
The momentum is approaching.

[0004]

However, in such an AM display element, the following problem occurs because a TN (twisted nematic) liquid crystal is used as a liquid crystal material. (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.

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 (1) and (2). There is currently a large barrier to practical use. (1). Ferroelectric liquid crystal has spontaneous polarization, but since spontaneous polarization is always present, screen burn-in is likely to occur 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 measures are required when performing gradation display (for example, a ferroelectric liquid crystal device using monostable;
Keiichi Nito et al., SID'94, Preprint p48), development of advanced practical technology is required.

(2). Since the antiferroelectric liquid crystal has no permanent spontaneous polarization, the problem of image sticking described in (1) above is avoided. At least 10 in AM drive
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.

An object of the present invention is to provide a new material suitable for AM driving capable of solving the above problems, and a liquid crystal compound having a ferrielectric phase is considered as the new material. A liquid crystal compound having a ferrielectric phase (= SCγ *) was first discovered in 4- (4-octyloxyphenyl) benzoic acid-4- (1-methylheptyloxycarbonyl) phenyl (abbreviated as MHPOBC) in 1989. (Japan
ese Journal of Applied Physics, Vol.29, No.1, 199
0, pp.L131-137).

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, the molecular alignment state in the ferrielectric phase is shown in FIG.
FIG. 2 shows the optical response to the triangular wave of the ferrielectric phase. 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 an electric field, FI (+) and FI (-) are equivalent and are considered to coexist. Therefore,
The average optical axis is in the layer normal direction, and is dark 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 is generated 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 ferrielectric phase and a liquid crystal compound having the phase is called a liquid crystal compound having a ferrielectric phase. Also,
A liquid crystal compound and a liquid crystal composition in which the ferrielectric phase has the widest temperature range in the phase series are referred to as a ferrielectric liquid crystal and a ferrielectric liquid crystal composition, respectively.

When the applied voltage is further increased, the phase transitions to the stable ferroelectric phase FO (+) or FO (-) 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, that is, 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. However, the number of liquid crystal compounds having a ferrielectric phase synthesized so far is extremely small, and the composition thereof is also limited. The present invention provides a new ferrielectric composition that can be suitably used for AM driving.

[0016]

According to the present invention, there is provided a compound represented by the following general formula:
A ferrielectric liquid crystal composition obtained by mixing a liquid crystal compound represented by (1) and having a ferrielectric phase in its phase sequence with a phenyl ester compound represented by the following general formula (2). Further, the present invention is an active matrix liquid crystal display device, characterized in that the ferrielectric liquid crystal composition according to claim 1 is sandwiched between substrates on which non-linear active devices such as thin film transistors or diodes are installed for each pixel. is there.

[0017]

Embedded image (In the formula (1), R is a straight-chain alkyl group having 6 to 12 carbon atoms, X and Y are H atoms or one of them is an F atom, and A is
CF ₃ or C ₂ F ₅ group, m is an integer of 2 to 4, n is an integer of 2 to 4, and C * is an asymmetric carbon. In formula (2), R ¹ is the carbon number
5 to 12 straight-chain alkyl group, R ² is a straight-chain alkyl group having 1 to 15 carbon atoms, X ¹ and X ² are H or one of F, Y ¹ and Y ² are H or one of which is F , A ¹ is H or CH ₃ . )
.

In the ferrielectric liquid crystal composition of the present invention, the liquid crystal compound having the ferrielectric phase of the general formula (1) is 95 to 50 mol%, preferably 90 to 60 mol%, particularly 90% of the composition.
Is selected from the range of up to 70 mol%. In the present invention, when A in the general formula (1) is CF ₃ , X = H, Y = F, and m is 4, the number of carbon atoms in R is 6 to 12 and n is 2 to 4; Is CF ₃ ,
When X = H, Y = H, and m is 4, the carbon number of R is 7 to 12, and n is 2.
When A is CF ₃ , X = F, Y = H, and m is 4, those in which R has 8 to 12 carbon atoms and n is 2 to 4: A is
In CF ₃ , when m is 3, the carbon number of R is 9 to 12, and n is 2
When A is CF ₃ and m is 2, those in which R has 8 or 9 carbon atoms are preferable, and those in which n is 2 can be used as a suitable liquid crystal compound having a ferrielectric phase.

As the compound of the general formula (2) of the present invention, R ¹
Has 8 to 12 carbon atoms, A ¹ is H, and R ² has
An optically active compound having 2 to 10 and having a smectic A phase, A ¹ being CH ₃ and R ² having 3 to 8 carbon atoms is preferable.

The AM drive display element normally uses a backlight. Therefore, the temperature of the display element is at least about 40 ° C. It is also required to operate at a temperature below room temperature. Therefore, the ferrielectric liquid crystal composition of the present invention is preferably a ferrielectric phase in the temperature range of 0 ° C to 40 ° C, particularly -20 ° C to 50 ° C. Further, in the production of practical devices, it is essential to have good orientation,
It is preferable that the ferrielectric liquid crystal composition of the present invention has a smectic A phase on the higher temperature side than the ferrielectric phase.

The driving voltage of the AM driving surface element which has been put into practical use is at least 10 V or less, and the voltage is further reduced significantly. In general, ferrielectric liquid crystal has a low threshold voltage, so it is easy to drive at a low voltage, but the threshold voltage when transitioning from ferrielectric state to ferroelectric state is 5V /
Most preferably, it is less than or equal to μm (cell thickness), and further less than or equal to 3 V / μm.

The liquid crystal compound having a ferri-dielectric phase or the ferri-dielectric liquid crystal composition according to the present invention has high display quality when sandwiched between substrates on which non-linear active elements such as thin film transistors or diodes are installed for each pixel. An active matrix liquid crystal display device can be realized. Then, the driving by the voltage of the liquid crystal using the non-linear active element is
It can be used as an active matrix liquid crystal display device that performs switching to one ferrielectric state, two ferroelectric states, and an intermediate state thereof.

The optically active alcohol used for producing the liquid crystal compound having the ferrielectric phase of the present invention can be easily produced by using the method already disclosed by the present inventors (Japanese Patent Laid-Open No. 4-983 etc.). . The outline of the manufacturing method is as follows. (B) Br (CH ₂ ) _m OC _n H _{2n + 1} + Mg → MgBr (CH ₂ ) _m OC _n H _{2n + 1} (b) (b) + CF ₃ COOH → CF ₃ CO (CH ₂ ) _m OC _n H _{2n + 1} (ha) (b) + (LiAlH ₄ ) → CF ₃ CH (OH) (CH ₂ ) _m OC _n H _{2n + 1} (d) (ha) + CH ₃ COCl → CF ₃ CH (OCOCH ₃ ) (CH ₂ ) _m OC _n H _{2n + 1} (e) (d) + (repose) → (R-) CF ₃ CH (OH) (CH ₂ ) _m OC _n H _{2n + 1} + (S-) CF ₃ CH (OCOCH ₃ ) (CH ₂ ) _m OC _n H _{2n + 1}

The method for producing the optically active alcohol will be briefly described as follows. B) is a Grignard reagent preparation of alkyloxy bromide. B is the production of ketones by the reaction of Grignard reagents with trifluoroacetic acid.
Ha is the production of racemic alcohol by reduction of the ketone. D is the acetylation of racemic alcohol. E is an asymmetric hydrolysis reaction of acetate with lipase. By this reaction, the target optically active alcohol of R-form
An S-form of acetate is obtained.

The liquid crystal compound having a ferrielectric phase in the present invention can be easily produced by the method already disclosed by the present inventors (Japanese Patent Laid-Open No. 3-292388). The outline of the manufacturing method is as follows. (1) AcO-Ph (X, Y) -COOH + SOCl ₂ → AcO-Ph (X, Y) -COCl (2) (1) + (R-) CF ₃ CH (OH) (CH ₂ ) _m OC _n H _{2n + 1} → AcO-Ph (X, Y) -COO-C * H (CF ₃ ) (CH ₂ ) _m OC _n H _{2n + 1} (3) (2) + (Ph-CH ₂ NH ₂ ) → HO-Ph (X, Y) -COO-C * H (CF ₃ ) (CH ₂ ) _m OC _n H _{2n + 1} (4) RO-Ph-Ph-COOH + SOCl ₂ → RO-Ph-Ph- COCl (5) (3) + (4) → target liquid crystal compound Ph is 1,4-phenylene group, Ph (X, Y) is 2- or 3-position (general formula
(1) X or Y) is a 1,4-phenylene group which may be an F atom, and C * is an asymmetric carbon.

The above manufacturing method will be briefly described as follows. 1 is a chlorination reaction of p-acetoxybenzoic acid with thionyl chloride. 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 chlorination of 4'-alkyloxybiphenyl-4-carboxylic acid. 5
Is the production of liquid crystal compounds by the reaction of phenol (3) with chloride (4).

[0027]

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 A liquid crystal composition was prepared by mixing 20 mol% of an optically active compound (2A) represented by the following chemical formula with a ferrielectric liquid crystal (1A) represented by the following chemical formula. 1A ； C ₈ H ₁₇ -O-Ph-Ph-COO-Ph (3F) -COO-C * H (CF ₃ ) (CH ₂ )
₄ OC ₂ H ₅ 2A; C ₉ H ₁₉ -COO-Ph (2F) -COO-Ph-COO-C * H (CH ₃ ) C ₃ H ₇ Ph is 1,4-phenylene group, 1A Ph (3F ) Is an F-substituted 1,4-phenylene group at the 3-position (Y), Ph (2F) of 2A is an F-substituted 1,4-phenylene group at the 2-position (X ² ), and C * is an asymmetric carbon atom. Indicates.

Identification of phases of the prepared liquid crystal composition,
The optical response was investigated. The results are shown in Tables 1 to 4, respectively. The phase is identified by texturer observation, conoscopic image observation, DSC (differential differential scanning calorimeter) measurement, and an area (domain) having an extinction position between the layer normal direction and the optical axis direction of the ferroelectric state. Was confirmed (observation of intermediate state FI (±)). Observation of a conoscopic image is a powerful tool for identifying a ferrielectric phase. Observation of the conoscopic image was according to the literature (J. Appl. Phys. 31, 793 (1992)). The phase sequence of this example was determined by texture observation, conoscopic observation, DSC measurement, and intermediate state FI (±) observation using ordinary parallel alignment cells, and it was confirmed to be a ferrielectric liquid crystal.

The optical response of the obtained ferrielectric liquid crystal composition was examined. The cell was produced by the following procedure. A glass substrate with an insulating film (SiO ₂ , film thickness 50 nm) and ITO electrode was subjected to polyimide coating (film thickness about 80 nm), and then only one of the pair of glass substrates was rubbed. A pair of glass substrates were bonded together through 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.

Regarding the optical response, the temperature was cooled to 30 ° C., a triangular wave voltage of ± 10 V and 50 mHz was applied to the test cell at the same temperature to drive the test cell, and the change in transmitted light was examined. The minimum transmitted light intensity is 0%,
The maximum transmitted light intensity is 100%, and the threshold voltage I is the voltage at which the transmitted light intensity becomes 90% when the phase transition from the ferrielectric phase to the ferroelectric phase occurs, and the phase transition from the ferroelectric phase to the ferrielectric phase occurs. Sometimes the threshold voltage II is the voltage at which the transmitted light intensity reaches 90%.
And the threshold voltage was measured. Also, 8V, frequency
When the pulse voltage of 10Hz is applied, the transmitted light intensity is 10% to 90
The response time was measured by defining the time required to change to% as the response time.

Examples 2 and 3 20 mol% of the following optically active compound (2B) or 25% of optically active compound (2C) was added to the ferrielectric liquid crystal (1B) obtained in Example 13.
Mol% was mixed to prepare a ferrielectric liquid crystal composition.
The results of measuring the physical properties of the prepared ferrielectric liquid crystal composition in the same manner as in Example 1 are shown in Tables 1 to 4. 1B ； C ₉ H ₁₉ -O-Ph-Ph-COO-Ph (3F) -COO-C * H (CF ₃ ) (CH ₂ )
₄ OC ₂ H ₅ 2B; C ₁₀ H ₂₁ -COO-Ph (2F) -COO-Ph-COO-C * H (CH ₃ ) C ₄ H ₉ 2C; C ₁₀ H ₂₁ -COO-Ph (2F)- COO-Ph-COO-C * H (CH ₃ ) C ₅ H ₁₁

Examples 4 and 5 The following optically active compound (2D) was added to the ferrielectric liquid crystal (1A).
20% by mol (Example 5) of the following optically active compound (2E) was mixed with mol% (Example 4) and the ferrielectric liquid crystal (1B) to prepare a ferrielectric liquid crystal composition. The results of measuring the physical properties of the prepared ferrielectric liquid crystal composition in the same manner as in Example 1 are shown in Tables 1 to 4. 2D ； C ₉ H ₁₉ -COO-Ph (2F) -COO-Ph-COO-C * H (CH ₃ ) C ₆ H ₁₃ 2E ； C ₉ H ₁₉ -COO-Ph-COO-Ph (3F) -COO -C * H (CH ₃ ) C ₇ H ₁₅ Ph (2F) is F-substituted at 2-position (X ² ) and Ph (3F) at 3-position (Y ² ), 1,4-
Shows a phenylene group.

Examples 6 and 7 Ferroelectric liquid crystal compositions (1C) represented by the following chemical formulas were mixed with 20 mol% of each of the following optically active compounds (2F, 2G) to prepare ferrielectric liquid crystal compositions. did. The results of measuring the physical properties of the prepared ferrielectric liquid crystal composition in the same manner as in Example 1 are shown in Tables 1 to 4. 1C ； C ₉ H ₁₉ -O-Ph-Ph-COO-Ph (3F) -COO-C * H (CF ₃ ) (CH ₂ )
₃ OC ₂ H ₅ 2F ； C ₅ H ₁₁ -COO-Ph-COO-Ph (2F) -COO-C * H (CH ₃ ) C ₅ H ₁₁ 2G ； C ₇ H ₁₅ -COO-Ph (2F)- COO-Ph-COO-C * H (CH ₃ ) C ₅ H ₁₁

Examples 8 to 10 Ferroelectric liquid crystal (1B) was mixed with the following optically active compound (2H, 2
20 mol% of each of I and 2J) was mixed to prepare a ferrielectric liquid crystal composition. The results of measuring the physical properties of the prepared ferrielectric liquid crystal composition in the same manner as in Example 1 are shown in Tables 1 to 4.
It was shown to. 2H ； C ₉ H ₁₉ -COO-Ph-COO-Ph-COO-C * H (CH ₃ ) C ₆ H ₁₃ 2I ； C ₁₀ H ₂₁ -COO-Ph-COO-Ph (2F) -COO-C * H (CH ₃ ) C ₈ H ₁₇ 2J; C ₁₀ H ₂₁ -COO-Ph (3F) -COO-Ph-COO-C * H (CH ₃ ) C ₈ H ₁₇

Examples 11 to 14 Ferrielectric liquid crystals (1C) were mixed with the following optically active compounds (2K, 2
20 mol% of each of L, 2M and 2N) was mixed to prepare a ferrielectric liquid crystal composition. Table 1 shows the physical properties of the prepared ferrielectric liquid crystal composition measured in the same manner as in Example 1.
-4 are shown. 2K ； C ₁₀ H ₂₁ -COO-Ph (3F) -COO-Ph (3F) -COO-C * H (CH ₃ ) C
₈ H ₁₇ 2L; C ₁₀ H ₂₁ -COO-Ph (3F) -COO-Ph (2F) -COO-C * H (CH ₃ ) C
₈ H ₁₇ 2M ； C ₁₀ H ₂₁ -COO-Ph (2F) -COO-Ph (3F) -COO-C * H (CH ₃ ) C
₈ H ₁₇ 2N ； C ₁₀ H ₂₁ -COO-Ph (2F) -COO-Ph (2F) -COO-C * H (CH ₃ ) C
₈ H ₁₇

Example 15 The above-mentioned optically active compound (2A) was added to the ferrielectric liquid crystal (1B).
40 mol% was mixed to prepare a ferrielectric liquid crystal composition. The results of measuring the physical properties of the prepared ferrielectric liquid crystal composition in the same manner as in Example 1 are shown in Tables 1 to 4.

Examples 16 to 23 and Comparative Example 1 The following phenyl ester compounds were added to the ferrielectric liquid crystal (1B).
(2P, 2Q, 2R, 2S, 2T, 2U) 25 mol% each, compound
(2P) in an amount of 15 mol%, an optically active compound (2V) in an amount of 30 mol%, and a ferrielectric liquid crystal (1A) in which an optically active compound (2W) in an amount of 20 mol% is mixed to prepare a ferrielectric liquid crystal composition. Prepared. The results of measuring the physical properties of the prepared ferrielectric liquid crystal composition in the same manner as in Example 1 are shown in Tables 1 to 4.

2P; C ₉ H ₁₉ -COO-Ph-COO-Ph (3F) -COO-C ₃ H ₇ 2Q; C ₉ H ₁₉ -COO-Ph-COO-Ph (3F) -COO-C ₅ H ₁₁ 2R ； C ₉ H ₁₉ -COO-Ph-COO-Ph (3F) -COO-C ₇ H ₁₅ 2S ； C ₉ H ₁₉ -COO-Ph-COO-Ph (3F) -COO-C ₈ H ₁₇ 2T C ₉ H ₁₉ -COO-Ph-COO-Ph (3F) -COO-C ₁₁ H ₂₃ 2U; C ₉ H ₁₉ -COO-Ph-COO-Ph-COO-C ₇ H ₁₅ 2V; C ₁₀ H ₂₁ -COO-Ph-COO-Ph (3F) -COO-C * H (CH3) C ₇ H ₁₅ 2W; C ₉ H ₁₉ -COO-Ph-COO-Ph (3F) -COO-C * H (CF ₃ ) (CH ₂ ) ₅
OC ₂ H ₅

[0039]

[Table 1] Phase system Sequence components Molar ratio Example 1 Cr (<-20) SCγ * (75) SA (86) I 1A / 2A = 80 / 20〃 2Cr (<-20) SCγ * (66) SA (77) I 1B / 2B = 80/20 〃 3 Cr (<-20) SCγ * (62) SA (73) I 1B / 2C = 75/25 〃 4 Cr (<-20) SCγ * (69) SA (75) I 1A / 2D = 80/20 〃 5 Cr (<-20) SCγ * (67) SA (74) I 1B / 2E = 80/20 〃 6 Cr (<-20) SCγ * (82) SA (92) I 1C / 2F = 80/20 〃 7 Cr (<-20) SCγ * (79) SA (89) I 1C / 2G = 80/20 〃 8 Cr (<-20) SCγ * (70) SA (78) I 1B / 2H = 80/20 〃 9 Cr (<-20) SCγ * (62) SA (72) I 1B / 2I = 80/20 〃 10 Cr (<-20) SCγ * (60) SA (70) I 1B / 2J = 80/20 〃 11 Cr (<-20) SCγ * (71) SA (81) I 1C / 2K = 80/20 〃 12 Cr (<-20) SCγ * (79) SA (83) I 1C / 2L = 80/20 〃 13 Cr (<-20) SCγ * (74) SA (84) I 1C / 2M = 80/20 〃 14 Cr (<-20) SCγ * (72) SA (85) I 1C / 2N = 80/20 〃 15 Cr (<-20) SCγ * (51) SA (69) I 1B / 2A = 60/40 〃 16 Cr (<-20) SCγ * (79) SA (98) I 1B / 2P = 75/25 〃 17 Cr (<-20) SCγ * (78) SA (92) I 1B / 2Q = 75/25 〃 18 Cr (<-20) SCγ * (81) SA (91) I 1B / 2R = 75/25 〃 19 Cr (<-20) SCγ * (76) SA (87) I 1B / 2S = 75/25 〃 20 Cr (<-20) SCγ * (74) SA (85) I 1B / 2T = 75/25 〃 21 Cr (<-20) SCγ * (84) SA (93) I 1B / 2U = 75/25 〃 22 Cr (<-20) SCγ * (83) SA (95) I 1B / 2P = 85/15 〃 23 Cr (<-20) SCγ * (73) SA (82) I 1B / 2V = 70/30 Comparative Example 1 Cr (<-20) SCγ * (86) SA (93) I 1A / 2W = 80/20 Numerical values in parentheses are phase transition temperature ( ℃), Cr is a crystalline phase, SCγ * is a chiral smectic Cγ phase (ferrielectric phase), SA is a smectic A phase, and I is an isotropic phase.

[0040]

[Table 2] Phase series liquid crystal 1A Cr (46) SCγ * (95) SA (98) I Liquid crystal 1B Cr (<-10) SCγ * (89) SA (91) I Liquid crystal 1C Cr (34) SCγ * ( 101) SA (103) I 2A Cr (-12) SA (27) I 2B Cr (5) SA (22) I 2C Cr (0) SA (21) I 2D Cr (-7) SA (5) I 2E Cr (12) SC * (22) SA (26) I 2F Cr (1) SA (16) I 2P Cr (57) SA (77) I 2Q Cr (61) SA (72) I 2R Cr (66) SA (70) I 2S Cr (60) SA (70) I 2T Cr (40) SA (70) I 2U Cr (29) SA (69) I 2V Cr (16) SC * (23) SCγ * (26) SA (28) I 2W Cr (30) SCA * (79) SC * (83) SA (92) I Descriptions are the same as in Table 21. SC * indicates the chiral smectic C phase (ferroelectric phase) and SCA * indicates the chiral smectic CA phase (antiferroelectric phase). Note that 2G to 2N in the general formula (2) did not have a liquid crystal phase.
These melting points (freezing points) are 2G (33), 2H (27), 2I, respectively.
It was (20), 2J (23), 2K (33), 2L (21), 2M (20), 2N (33) (in parentheses indicates temperature (° C)).

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[Table 3] Threshold voltage Response time Temperature I II (μsec) (℃) Component Molar ratio Example 1 2.6 2.0 88 30 1A / 2A = 80/20 〃 2 1.2 1.2 58 〃 1B / 2B = 80/20 〃 3 1.4 1.4 77 〃 1B / 2C = 75/25 〃 4 1.6 1.6 58 〃 1A / 2D = 80/20 〃 5 1.4 1.4 65 〃 1B / 2E = 80/20 〃 6 2.2 2.2 72 〃 1C / 2F = 80 / 20 〃 7 2.0 2.0 65 〃 1C / 2G = 80/20 〃 8 1.9 1.8 86 〃 1B / 2H = 80/20 〃 9 1.2 1.2 69 〃 1B / 2I = 80/20 〃 10 1.1 1.0 84 〃 1B / 2J = 80/20 〃 11 1.3 1.3 68 〃 1C / 2K = 80/20 〃 12 1.8 1.8 76 〃 1C / 2L = 80/20 〃 13 2.0 2.0 70 〃 1C / 2M = 80/20 〃 14 1.8 1.8 79 〃 1C / 2N = 80/20 〃 15 1.5 1.2 79 〃 1B / 2A = 60/40 〃 16 1.3 1.3 68 〃 1B / 2P = 75/25 〃 17 1.4 1.3 68 〃 1B / 2Q = 75/25 〃 18 1.3 1.3 65 〃 1B / 2R = 75/25 〃 19 1.2 1.1 63 〃 1B / 2S = 75/25 〃 20 1.0 1.0 59 〃 1B / 2T = 75/25 〃 21 1.1 1.1 65 〃 1B / 2U = 75/25 〃 22 1.3 1.3 64 〃 1B / 2P = 85/15 〃 23 2.0 2.0 73 〃 1B / 2V = 70/30 Comparative example 1 2.0 1.8 133 〃 1A / 2W = 80/20 threshold voltage: unit / Μm

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[Table 4] Threshold voltage: Unit V / μm

As is clear from Tables 1 to 4, by mixing a phenyl ester compound (2A to 2V) with a liquid crystal compound having a ferri-dielectric phase in the phase sequence (particularly, a ferri-dielectric liquid crystal), it is practical. Has a temperature range of ferrielectric phase,
It is understood that a composition having a smectic A phase on its high temperature side and having an improved response time is obtained.

Example 24 The light transmittance when no voltage was applied was set to 0, assuming that the light transmittance when only the polarizing plate is arranged is 0% and the light transmittance when the state is changed to the ferroelectric state is 100%. The ferrielectric liquid crystal composition and the ferrielectric liquid crystal (1B) were measured. The liquid crystal cell used was one in which an alignment film was applied to both surfaces of the substrate and rubbed. As a result, the light transmittance was 0.9% in Example 63 and 3.6% in liquid crystal 1B, and a great effect was observed not only in the response speed but also in improving the orientation.

[Brief description of drawings]

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

FIG. 2 is a diagram showing an optical response to a triangular wave voltage in a ferrielectric phase of MHPOBC.

Front page continued (72) Inventor Maki Ito 22 Wadai, Tsukuba, Ibaraki Mitsubishi Gas Chemical Co., Ltd.

Claims (14)

[Claims] 1. A ferrimeric compound obtained by mixing a phenyl ester compound represented by the following general formula (2) with a liquid crystal compound represented by the following general formula (1) and having a ferrielectric phase in its phase sequence. Dielectric liquid crystal composition. Embedded image (In the formula (1), R is a straight-chain alkyl group having 6 to 12 carbon atoms, X and Y are H atoms or one of them is an F atom, and A is
CF ₃ or C ₂ F ₅ group, m is an integer of 2 to 4, n is an integer of 2 to 4, and C * is an asymmetric carbon. In formula (2), R ¹ is the carbon number
5 to 12 straight-chain alkyl group, R ² is a straight-chain alkyl group having 1 to 15 carbon atoms, X ¹ and X ² are H or one of F, Y ¹ and Y ² are H or one of which is F , A ¹ is H or CH ₃ . )
. 2. The ferrielectric liquid crystal composition has a ferrielectric phase in a temperature range of at least 0 to 40 ° C., and has at least a smectic A phase on the high temperature side of the ferrielectric phase. The ferrielectric liquid crystal composition described. 3. The ferrielectric liquid crystal composition according to claim 1, wherein the threshold voltage at the time of transition from the ferrielectric state to the ferroelectric state is 3 V / μm or less. 4. A in the general formula (1) is CF ₃ , and X is H and Y.
2. The ferrielectric liquid crystal composition according to claim 1, wherein R is 6 to 12 when F is m and 4 is m. 5. A in the general formula (1) is CF ₃ , and X is H and Y.
2. The ferrielectric liquid crystal composition according to claim 1, wherein when R is H and m is 4, the carbon number of R is 7-12. 6. In the general formula (1), A is CF ₃ and X is F and Y.
2. The ferrielectric liquid crystal composition according to claim 1, wherein when R is H and m is 4, the carbon number of R is 8-12. 7. The ferrielectric liquid crystal composition according to claim 1, wherein when A in the general formula (1) is CF ₃ and m is 3, the carbon number of R is 9 to 12. 8. The ferrielectric liquid crystal composition according to claim 1, wherein when A in the general formula (1) is CF ₃ and m is 2, the carbon number of R is 8 or 9. 9. The ferrielectric liquid crystal composition according to claim 1, wherein the phenyl ester compound represented by the general formula (2) has a smectic A phase. 10. The ferrielectric liquid crystal composition according to claim ¹ , wherein R ^{1 in} the general formula (2) has 8 to 12 carbon atoms. 11. The ferrielectric liquid crystal composition according to claim 1, wherein A ^{1 in the} general formula (2) is H and R ² has 2 to 10 carbon atoms. 12. The ferrielectric liquid crystal composition according to claim 1, wherein A ^{1 in the} general formula (2) is CH ₃ , and R ² is an optically active compound having 3 to 8 carbon atoms. 13. An active matrix liquid crystal display device, wherein a ferrielectric liquid crystal composition according to claim 1 is 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.
The active matrix liquid crystal display element described.