JP2014214137A - Compound, ferroelectric liquid crystal composition using the same and liquid crystal display element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a compound with which birefringence can be reduced while maintaining transmittance, and with which an excellent white display is achieved even when used in a liquid crystal display element with a large cell gap, and to provide a ferroelectric liquid crystal composition using the same and the liquid crystal display element.SOLUTION: A compound having a structure represented by general formula (1) is exemplified (in formula (1), each of R1 and R2 is a straight chain or branched 3-7C alkyl group, however, at least one of R1 and R2 has 5 or more carbon atoms, A is -O-CH2- or -CH2-O-, and each of Z1 and Z2 is independently a fluorine atom or a hydrogen atom, however, at least one of Z1 and Z2 is a fluorine atom).

Description

  The present invention relates to a compound that can be used in a ferroelectric liquid crystal composition, a ferroelectric liquid crystal composition having a small birefringence, and a liquid crystal display element.

  Liquid crystal display elements have been widely used from large displays to portable information terminals because of their thinness and low power consumption, and their development is actively underway. So far, liquid crystal display elements have been developed and put to practical use, such as TN mode, STN multiplex drive, and active matrix drive using thin layer transistors (TFTs) for TN, but these use nematic liquid crystals. In addition, the response speed of the liquid crystal material is as slow as several ms to several tens of ms, and it cannot be said that it is sufficiently compatible with moving image display.

  Ferroelectric liquid crystal is expected to provide a high-performance liquid crystal display element because it has a superior response speed such as a wide viewing angle because it has a response speed as short as μs and is suitable for high-speed devices. .

Since the ferroelectric liquid crystal has a large birefringence, in the liquid crystal display element using the ferroelectric liquid crystal, the cell gap needs to be very narrow as less than 2 μm in order to suppress the occurrence of color shift and obtain a good white display. There is. However, in a narrow cell gap, there is a problem in that the manufacturing yield decreases due to the occurrence of thickness unevenness, color unevenness due to thickness unevenness, display unevenness, and the like.
Therefore, a ferroelectric liquid crystal capable of realizing a good white display even in a liquid crystal display element having a large cell gap is desired.

  For the purpose of providing a liquid crystal display element that enables high-visibility black and white display by preventing coloring due to the birefringence effect, for example, Patent Document 1 discloses that the substrate has birefringence and the optical main axis of the substrate. It has been proposed that the ferroelectric liquid crystal is disposed at an angle of 30 degrees with respect to the normal of the smectic layer and the retardation difference between the substrate and the liquid crystal layer is within a predetermined range.

  Further, although it is not a ferroelectric liquid crystal, it is known that a liquid crystal material is added in order to improve display characteristics with respect to a nematic liquid crystal. For example, Patent Document 2 proposes adding a liquid crystal material having a desired birefringence or a liquid crystal material having a relatively large birefringence.

  Further, in Patent Document 3, although it is not a ferroelectric liquid crystal, it can be mixed with a nematic liquid crystal material so as to have a wide liquid crystal temperature range and maintain a small refractive index anisotropy of the liquid crystal material. For the purpose of providing a cyclohexanedimethyl derivative that raises the I point, a cyclohexanedimethyl derivative having a 3 or 4 ring structure in which a benzene ring and a cyclohexane ring are introduced into the main chain is disclosed.

  Furthermore, Patent Document 4 does not relate to a ferroelectric liquid crystal, but is a practical mixed liquid crystal having an NI point of 65 ° C. or higher by mixing with one or more nematic liquid crystal compounds. In preparing a compound, one benzene ring and two cyclohexane rings were introduced for the purpose of providing a compound that suppresses the increase in viscosity of the mixed liquid crystal to a small extent as compared with the prior art. Nematic liquid crystal compounds of bound cyclohexanecarboxylic acid derivatives are disclosed.

Japanese Patent No. 3225084 JP 2001-34197 A Japanese Patent No. 3402678 Japanese Patent No. 1378148

In Patent Document 1, birefringence is improved by setting the difference in retardation between the substrate of the liquid crystal display element and the liquid crystal layer within a predetermined range, and the birefringence of the ferroelectric liquid crystal itself is not reduced.
In Patent Document 2, a liquid crystal material having a large birefringence is used.
Further, in Patent Document 3, by mixing a cyclohexanedimethyl derivative having a high NI point and a wide liquid crystal temperature range into a nematic liquid crystal material, the anisotropy of the refractive index of the liquid crystal material is kept small, and the liquid crystal temperature range is set. However, there is no disclosure of mixing a cyclohexanedimethyl derivative with a ferroelectric liquid crystal composition.
Furthermore, Patent Document 4 does not describe birefringence.

  In order to reduce the birefringence of the ferroelectric liquid crystal composition, it may be considered to add a material having a small birefringence. However, when a material having a small birefringence is added to the ferroelectric liquid crystal composition, there is a problem that when used in a liquid crystal display element, the drive characteristics are changed, the tilt angle of liquid crystal molecules is reduced, and the transmittance is lowered. .

  The present invention has been made in view of the above problems, and can reduce the birefringence while maintaining the transmittance, and can realize a good white display even in a liquid crystal display element having a large cell gap. The main object of the present invention is to provide a compound that can be used, a ferroelectric liquid crystal composition using the compound, and a liquid crystal display device.

  As a result of various studies on the birefringence of a liquid crystal display element using a ferroelectric liquid crystal, the present inventors have been able to reduce the birefringence by using a compound having a specific structure. The inventors have found that a good white display can be obtained while suppressing the occurrence of light and that the transmittance can be maintained, and the present invention has been completed based on such knowledge.

  That is, this invention provides the compound characterized by having a structure represented by following General formula (1).

(In the above formula (1), R ¹ and R ² are linear or branched alkyl groups having 3 to 7 carbon atoms, provided that at least one of R ¹ and R ² has 5 carbon atoms. That's it.
A is —O—CH ₂ — or —CH ₂ —O—.
Z ¹ and Z ² each independently represent a fluorine atom or a hydrogen atom. However, at least one of Z ¹ and Z ² is a fluorine atom. )

  Since the compound of the present invention has a structure represented by the above formula (1), birefringence can be reduced when added to the ferroelectric liquid crystal composition, and the ferroelectric liquid crystal composition is used. In the liquid crystal display element, even when the cell gap is relatively large, it is possible to suppress the occurrence of color misregistration and obtain a good white display, and the tilt angle of the liquid crystal molecules is not extremely reduced. The transmittance can be maintained.

  The present invention also provides a ferroelectric liquid crystal composition comprising a compound represented by the above formula (1).

  The ferroelectric liquid crystal composition of the present invention can reduce the birefringence by containing the compound represented by the above formula (1), and when used in a liquid crystal display element, the cell gap is large. The occurrence of color misregistration can be suppressed and a good white display can be obtained. In addition, the tilt angle of the liquid crystal molecules is not extremely reduced, and the transmittance of the liquid crystal display element can be maintained.

  Furthermore, the present invention provides a first alignment treatment substrate having a first substrate, a first electrode layer formed on the first substrate, and a first alignment film formed on the first electrode layer; A second alignment substrate having a second substrate, a second electrode layer formed on the second substrate, and a second alignment film formed on the second electrode layer, and the first alignment film And a liquid crystal display element formed between the second alignment films and having a liquid crystal layer containing a ferroelectric liquid crystal composition, wherein the ferroelectric liquid crystal composition is represented by the formula (1). A liquid crystal display element comprising a compound is provided.

  Since the liquid crystal display element of the present invention uses a ferroelectric liquid crystal composition containing the compound represented by the above formula (1), the birefringence of the ferroelectric liquid crystal composition can be reduced, and the cell gap is reduced. Even if it is large, the occurrence of color misregistration can be suppressed and a good white display can be obtained, and the tilt angle of the liquid crystal molecules is not extremely reduced, and the transmittance of the liquid crystal display element can be maintained.

  When the compound represented by the above formula (1) of the present invention is used in a ferroelectric liquid crystal composition, birefringence can be reduced, and the ferroelectric liquid crystal composition can be used in a liquid crystal display device. When used, it is possible to suppress the occurrence of color misregistration and obtain a good white display, and to maintain the transmittance of the liquid crystal display element without extremely reducing the tilt angle of the liquid crystal molecules. There is an effect.

It is a schematic diagram which shows an example of the orientation state of the liquid crystal molecule in this invention. It is a schematic sectional drawing which shows an example of the liquid crystal display element of this invention. It is a chromaticity diagram of the liquid crystal display element in an Example.

  Hereinafter, the compound, ferroelectric liquid crystal composition and liquid crystal display element of the present invention will be described in detail.

A. Compound The compound of the present invention has a structure represented by the following general formula (1).

(In the above formula (1), R ¹ and R ² are linear or branched alkyl groups having 3 to 7 carbon atoms, provided that at least one of R ¹ and R ² has 5 carbon atoms. That's it.
A is —O—CH ₂ — or —CH ₂ —O—.
Z ¹ and Z ² each independently represent a fluorine atom or a hydrogen atom. However, at least one of Z ¹ and Z ² is a fluorine atom. )

  That is, the compound of the present invention is represented by the following general formulas (1-1) and (1-2).

(In the above formulas (1-1) and (1-2), R ¹ , R ² , Z ¹ and Z ² are the same as in the above formula (1).)

In general, the liquid crystalline compound has a structure composed of a core part, a terminal chain part, and a spacer part that connects the core part and the terminal chain part, and has a rod-like shape. The liquid crystal compound constituting the ferroelectric liquid crystal composition generally has such a structure and shape. In particular, the liquid crystal compound constituting the ferroelectric liquid crystal composition has a plurality of aromatic rings such as a benzene ring and a pyrimidine ring in the core portion, and the shape tends to be linear. Anisotropy, that is, birefringence increases.
It is also known that birefringence increases as conjugation due to unsaturated bonds increases.

On the other hand, since the compound represented by the above formula (1) has a bent shape rather than a rod shape, the anisotropy of the refractive index is reduced. Further, the compound represented by the above formula (1) has only one benzene ring in the core portion and does not have a plurality of aromatic rings, and therefore has little conjugation due to an unsaturated bond. Therefore, it is estimated that the birefringence becomes small.
Therefore, birefringence can be reduced by adding the compound represented by the above formula (1) to the ferroelectric liquid crystal composition. Therefore, when the ferroelectric liquid crystal composition is used in a liquid crystal display element having a relatively large cell gap, it is possible to suppress the occurrence of color shift and obtain a good white display.

  Further, by adding the compound represented by the above formula (1) to the ferroelectric liquid crystal composition, it is possible to maintain the transmittance of the liquid crystal display element without extremely reducing the tilt angle of the liquid crystal molecules. Become. The reason for this is not clear, but is thought to be as follows. That is, the compound represented by the above formula (1) is considered to be less likely to disturb the chiral smectic C phase of the ferroelectric liquid crystal composition because the benzene ring and the cyclohexane ring are bonded by an ether bond. Therefore, it is presumed that the transmittance of the liquid crystal display element can be maintained without extremely reducing the tilt angle of the liquid crystal molecules.

1. Compounds represented by the above formulas (1-1) and (1-2) In the above formulas (1-1) and (1-2), R ¹ is a linear or branched alkyl group.
R ¹ may have 3 to 7 carbon atoms, but 5 to 7 is particularly preferable, and 5 is particularly preferable. When the carbon number of R ¹ is more than the above range, when added to the ferroelectric liquid crystal composition, the ferroelectric liquid crystal composition may easily develop a liquid crystal phase close to a crystal phase such as a smectic B phase. . When a liquid crystal phase close to a crystal phase such as a smectic B phase is developed, the regularity of the molecular arrangement becomes too high, impact resistance is lowered, the phase sequence becomes complicated, and the liquid crystal molecules are difficult to align. In addition, the tilt performance of the liquid crystal molecules becomes small, and the driving performance such as insufficient brightness may be deteriorated. On the other hand, if the carbon number of R ¹ is less than the above range, the temperature range of the chiral smectic C phase of the ferroelectric liquid crystal composition may be narrowed or the chiral smectic C phase may not be exhibited. When the temperature range of the chiral smectic C phase is narrowed, the tilt angle of the liquid crystal molecules is reduced or the alignment of the liquid crystal molecules is adversely affected. When the number of carbon atoms is in the above range, good driving performance can be obtained without extremely reducing the tilt angle of the liquid crystal molecules.

Incidentally, one of the carbon atoms at least one of R ¹ and described below R ² is 5 or more. The reason for this is the same as when the number of carbon atoms of the above R ¹ is within a predetermined range.

In the above formulas (1-1) and (1-2), R ² is a linear or branched alkyl group.
The carbon number of R ² may be 3 to 7, but 5 to 7 is particularly preferable, and 5 is particularly preferable. The preferable reason that the carbon number of R ² is in the above range is the same as the carbon number of R ¹ described above, and thus description thereof is omitted here.

In the above formulas (1-1) and (1-2), Z ¹ and Z ² each independently represent a fluorine atom or a hydrogen atom, and at least one of Z ¹ and Z ² is a fluorine atom. . Among them, it is preferable that both Z ¹ and Z ² are fluorine atoms. When both Z ¹ and Z ² are fluorine atoms, the phase transition temperature of the chiral smectic C phase is widened, so the compounds represented by the above formulas (1-1) and (1-2) were added. When the ferroelectric liquid crystal composition is used for a liquid crystal display element, the liquid crystal display element can be driven stably at low and high temperatures.

  Specific examples of the compounds represented by the above formulas (1-1) and (1-2) include compounds represented by the following formulas.

2. Synthesis Method The birefringence improving agent of the present invention can be synthesized from an arbitrary raw material compound using a generally known organic synthesis method. Hereinafter, a method for synthesizing the compounds represented by the above formulas (1-1) and (1-2) will be described.

(1) Compound represented by the above formula (1-1) As an example of a method for synthesizing the compound represented by the above formula (1-1), a method for synthesizing a compound represented by the following formula (1-3) Will be described in the first to fifth steps.

(A) First Step Under a nitrogen atmosphere, LiAlH ₄ is added to ice-cooled anhydrous THF and stirred. A 4-trans-pentyl-cyclohexanecarboxylic acid solution dissolved in anhydrous THF is added dropwise thereto, and then the mixture is returned to room temperature and stirred. Next, water and a 15% aqueous solution of NaOH are added to the solution, and the mixture is stirred and insolubles are removed by celite filtration. Subsequently, colorless, oily 4-trans-n-pentyl-cyclohexane-methanol can be obtained by extraction, washing with water, drying, concentration and drying under reduced pressure.

(B) Second Step Under a nitrogen atmosphere, a solution in which 2,3-difluorophenol and the compound obtained in the above “(a) first step” are dissolved in anhydrous THF is prepared, and triphenylphosphine is added to ice. Cool down. Thereto, diisopropyl azodicarboxylate is dropped and stirred. Thereafter, the mixture is returned to room temperature and stirred, followed by extraction, washing with water, drying and concentration to obtain a yellow oily substance. Subsequently, N-hexane is added to the oily substance, and the white solid precipitated at this time is removed by filtration and concentrated. Thereafter, by purifying the obtained residue, 4-trans-n-pentyl-1- (2,3-difluoro-phenoxymethyl) cyclohexane as a white solid can be obtained.

(C) 3rd process Under Ar atmosphere, the solution which melt | dissolved the compound obtained by said "(b) 2nd process" in anhydrous THF was stirred at -40 degrees C or less, and a butyllithium hexane solution was dripped there. And stir. Next, trimethoxyborane is dropped into the resulting solution and stirred. The solution is then allowed to warm to room temperature, acidified by addition of dilute aqueous hydrochloric acid and stirred to extract, dry and concentrate under reduced pressure. Thereafter, N-hexane was added to the obtained residue and the mixture was ice-cooled, and the precipitated crystals were collected by filtration to give 4- (4-trans-n-pentyl-cyclohexylmethyloxy) -2,3- Difluoro-phenylboronic acid can be obtained.

(D) Fourth Step Acetic acid is added to the compound obtained in the above “(c) Third Step”, and then an aqueous peroxide solution is added at room temperature. Next, this solution was stirred, water was added, and the precipitated crystals were collected by filtration to give a pale yellow powder of 4- (4-trans-n-pentyl-cyclohexylmethyloxy) -2,3-difluoro-phenol. Can be obtained.

(E) Fifth Step Under a nitrogen atmosphere, triethylamine is added to a solution obtained by dissolving the compound obtained in the above “(d) fourth step” in anhydrous methylene chloride and ice-cooled. To this solution, a solution obtained by dissolving trans-4-n-pentylcyclohexylcarbonyl chloride in methylene chloride is added dropwise and stirred. The solution is then allowed to warm to room temperature and stirred, extracted, washed with water, dried and concentrated under reduced pressure. Thereafter, methanol is added to the obtained residue, the mixture is stirred at room temperature, and the precipitated crystals are collected by filtration to obtain a compound represented by the above formula (1-3) as a white solid as a final product. it can.

(2) Compound represented by the above formula (1-2) As an example of a method for synthesizing the compound represented by the above formula (1-2), a method for synthesizing the compound represented by the following formula (1-4) Will be described in the first to seventh steps.

(A) First Process First, in the presence of benzyl bromide, 2,3-difluorophenol and potassium carbonate are added to DMF, and the mixture is heated and stirred in an Ar atmosphere. Subsequently, oily 2,3-difluorophenylbenzyl ether can be obtained by extraction, washing with water, drying, concentration and drying under reduced pressure.

(B) Second Step In an Ar atmosphere, the compound obtained in the above “(a) First step” is added to THF and stirred at −40 ° C. or lower, and a butyllithium hexane solution is added dropwise thereto. Subsequently, after stirring the solution, dry ice is added and stirred overnight. Subsequently, 4-benzyloxy-2,3-difluorobenzoic acid as a white solid can be obtained by extraction, drying, concentration and recrystallization.

(C) Third Step In an Ar atmosphere, the compound obtained in the above “(b) Second Step” is added to THF and trimethoxyborane, and stirred under ice cooling. Then, a THF solution of borane-dimethylsulfide complex is added dropwise to this solution and stirred overnight at room temperature. Thereafter, the precipitate obtained by pouring this solution into ice water is collected by filtration and dried under reduced pressure, whereby 4-benzyloxy-2,3-difluorobenzyl alcohol as a white solid can be obtained.

(D) Fourth Step In an Ar atmosphere, the compound obtained in the above “(c) Third Step” is added to dichloromethane and stirred at room temperature. To this solution is added dropwise a solution of phosphorus tribromide in dichloromethane, and the mixture is stirred overnight at room temperature. Thereafter, 4-benzyloxy-2,3-difluorobenzyl bromide as a white solid can be obtained by washing with water, drying, concentration and drying under reduced pressure.

(E) Fifth Step Under Ar atmosphere, add the compound obtained in “(d) Fourth Step”, trans-pentylcyclohexanol and sodium hydride to THF and DMF, and heat and stir overnight. . Subsequently, 2,3-difluoro-4- (trans-pentylcyclohexyl) oxymethylphenylbenzyl ether as a white solid can be obtained by extraction, washing with water, drying, concentration and purification.

(F) Step 6 Under a hydrogen atmosphere, the compound obtained in the above “(e) Step 5”, palladium carbon and concentrated hydrochloric acid are added to THF and ethanol, heated and stirred overnight. Thereafter, filtration, concentration and purification can give 2,3-difluoro-4- (trans-pentylcyclohexyl) oxymethylphenol as a white solid.

(G) Seventh step In an Ar atmosphere, the compound obtained in the above "(f) Sixth step", trans-4-pentylcyclohexylcarbonyl chloride and triethylamine are added to dichloromethane and stirred overnight at room temperature. Next, the compound represented by the above formula (1-4) as a white solid can be obtained by extraction, washing with water, drying, concentration, purification and recrystallization.

3. Use The use of the compound represented by the formula (1) is not particularly limited, but it is suitably used as a birefringence improving agent for a ferroelectric liquid crystal composition. When the compound represented by the formula (1) is contained in the ferroelectric liquid crystal composition, the birefringence of the ferroelectric liquid crystal composition can be reduced, and even if the cell gap is large, the color shift is small. In addition, it is possible to obtain a good white display and to maintain the transmittance of the liquid crystal display element without extremely reducing the tilt angle of the liquid crystal molecules.

  Here, when the ferroelectric liquid crystal composition containing the compound represented by the above formula (1) is used in a liquid crystal display element, the compound represented by the above formula (1) is used alone. It is also possible to use a mixture of two or more.

B. Ferroelectric liquid crystal composition The ferroelectric liquid crystal composition of the invention contains a compound represented by the above formula (1).

  According to the ferroelectric liquid crystal composition of the present invention, birefringence can be reduced while maintaining the transmittance by containing the compound represented by the above formula (1).

  Hereinafter, each component in the ferroelectric liquid crystal composition of the present invention will be described.

1. The compound represented by the above formula (1) The compound represented by the above formula (1) will be described.

  The compound represented by the above formula (1) used in the ferroelectric liquid crystal composition of the present invention may be only one type, or two or more types.

  The content of the compound represented by the above formula (1) in the ferroelectric liquid crystal composition of the present invention is particularly limited as long as the birefringence can be reduced without extremely reducing the tilt angle of the liquid crystal molecules. However, it is preferably in the range of 5% by mass to 60% by mass in the ferroelectric liquid crystal composition of the present invention, and more preferably in the range of 10% by mass to 50% by mass. It is particularly preferable that the content be in the range of 10% by mass to 40% by mass. If the content of the compound represented by the above formula (1) is small, the effect of reducing the birefringence may not be sufficiently obtained. On the other hand, if the content of the compound represented by the above formula (1) is large, the viscosity may increase and the response speed may decrease, or the drive voltage may increase. In addition, when the content of the compound is large, the temperature range of the chiral smectic C phase shifts to the high temperature side, the phase transition temperature on the low temperature side approaches room temperature, and the single component in the ferroelectric liquid crystal composition increases. Or may be easily crystallized.

  In addition, about the compound represented by the said Formula (1), since it is the same as that of what was demonstrated in the above-mentioned "A. Compound represented by the said Formula (1)" section, description here is abbreviate | omitted.

2. Chiral Compound The ferroelectric liquid crystal composition of the present invention usually contains a chiral compound.
As the chiral compound used in the present invention, those generally used as a chiral compound of a ferroelectric liquid crystal composition can be used. Note that the chiral compound does not need to have smectic properties and does not need to exhibit liquid crystallinity.

  Among them, the chiral compound is preferably a compound in which two or more benzene rings are directly bonded, and more preferably a compound in which three or more benzene rings are directly bonded. Since the benzene ring has a planar structure, a chiral compound in which two or more benzene rings are directly bonded has a tendency that the benzene ring planes are stacked and oriented. Therefore, the refractive index differs greatly between the direction parallel to the benzene ring plane and the direction perpendicular to the benzene ring plane, and birefringence tends to increase. On the other hand, in the present invention, birefringence can be reduced, which is effective when such a chiral compound is used.

In addition, as a chiral compound in which three or more benzene rings are directly bonded, at least one of a chiral compound A represented by the following general formula (2) and a chiral compound B represented by the following general formula (3): Preferably there is. By containing such a chiral compound, impact resistance can be improved when the ferroelectric liquid crystal composition of the present invention is used in a liquid crystal display device. Ferroelectric liquid crystals have higher molecular ordering than nematic liquid crystals, so if the regularity of molecular orientation is disturbed by impact, it is difficult to return to its original state, that is, it is very vulnerable to external impact. It is preferable that the property is good.
In the present invention, as described above, when the ferroelectric liquid crystal composition contains a chiral compound that improves the impact resistance, it is possible to reduce the birefringence while maintaining the impact resistance. is there.
Chiral compound A and chiral compound B have three or more benzene rings in the core portion, so that birefringence tends to be particularly large. However, as described above, in the present invention, the compound represented by the above formula (1) By adding at least one of the compounds, the birefringence of the ferroelectric liquid crystal composition can be reduced.

  Hereinafter, the chiral compound in the present invention will be described separately for chiral compound A and chiral compound B.

(1) Chiral compound A
The chiral compound A used in the present invention is represented by the following general formula (2).

In the above formula (2), R ¹⁰ is a non-chiral group, and is a saturated or unsaturated alkyl group or alkoxyalkyl group which may be substituted with a halogen atom.
Although carbon number should just be 4-18, 6-18 are preferable especially and 6-12 are more preferable. This is because when the number of carbon atoms is larger than the above range, the synthesis of the chiral compound A becomes difficult and the cost increases. On the other hand, if the number of carbon atoms is less than the above range, the ferroelectric liquid crystal composition may not exhibit a smectic phase. The alkyl group or alkoxyalkyl group may be substituted with a halogen atom or may not be substituted with a halogen atom.
The alkyl group or alkoxyalkyl group is linear or branched.
R ²⁰ is a chiral group, and is a group represented by the following general formula (4).

In the above formula (4), R ³⁰ is a C1-C10 saturated or unsaturated linear, branched or cyclic alkyl group or alkoxyalkyl group which may be substituted with a halogen atom.
In the above formula (4), Y ¹ represents —CH ₃ or a fluorine atom. Y ¹ may be —CH ₃ or a fluorine atom, and among them, —CH ₃ is preferable. This is because the synthesis of the chiral compound A is easy, the chiral compound A can be stably produced, and the ferroelectric liquid crystal composition can be obtained at a low cost.

m is 0 or 1. n is 0 or 1.
In the above formula (4), * indicates a chiral center. When m = 0, the 1st carbon atom becomes a chiral center, and when m = 1, the 2nd carbon atom becomes a chiral center.
In the above formula (4), R ²⁰ is a chiral group. Therefore, in the above formula (4), when Y ¹ is —CH ₃ and n = 0, R ³⁰ is not —CH ₃ .

In the above formula (2), X ^{1 to} X ⁸ each independently represent —CH ₃ , —CF ₃ , a halogen atom or a hydrogen atom. However, one or more of X ^{1 to} X ⁸ are each independently —CH ₃ , —CF ₃ or a halogen atom.
When all of X ^{1 to} X ⁸ are hydrogen atoms, the solubility of the chiral compound A is lowered, so that the synthesis and purification of the chiral compound A becomes difficult and the cost may increase. On the other hand, when one or more of X ^{1 to} X ⁸ are —CH ₃ , —CF ₃ or a halogen atom as in the present invention, the solubility of the chiral compound A in the solvent increases, Synthesis and purification become possible. In addition, since the steric structure of the chiral compound A is distorted, and this distortion relaxes the molecular arrangement that is too regular, it is considered that high impact resistance can be obtained.

Among ^them, any one or more of ^{X 1 ~X 3, X 5 ~X} 7 is, _-CH 3 each independently is preferably a -CF ₃ or a halogen atom. This is because the chiral compound has better solubility than the X ⁴ and X ⁸ positions when it has a substituent at the X ^{1 to} X ³ and X ^{5 to} X ⁷ positions. This is presumably because the X ⁴ and X ⁸ positions are less distorted by substituents than the other positions.

One benzene ring can have 1 to 4 substituents, and among them, it is preferable to have 1 or 2 substituents. When there is one substituent, the substituent is preferably —CH ₃ , a fluorine atom or a chlorine atom, and more preferably —CH ₃ or a fluorine atom. On the other hand, when there are two substituents, it is preferable that any substituent is a fluorine atom. In this case, as the position of the two substituents, for example, when X ¹ and X ² , or X ³ and X ⁴ are fluorine atoms, the adjacent carbon atoms of the benzene ring are each substituted with a fluorine atom. Preferably it is. When two fluorine atoms are substituted on adjacent carbon atoms of the benzene ring, and the benzene ring is symmetrically substituted, the chiral smectic C phase is stabilized and the tilt angle of the liquid crystal molecules can be increased. Therefore, the transmittance of the liquid crystal display element can be increased. In addition, since two substituents are bonded to a carbon atom located closer, the regularity of the molecular arrangement can be relaxed and crystallization can be suppressed.
Moreover, it is preferable that the chiral compound represented by the said Formula (2) has 1-2 substituents in total.
In the chiral compound represented by the above formula (2), it is preferable that one of the benzene rings to which X ^{1 to} X ⁸ are bonded has a substituent, among which X ¹ , X ² , It is preferable that the benzene ring to which X ⁵ and X ⁶ are bonded has a substituent. This is because, among the three directly bonded benzene rings, the ferroelectric liquid crystal composition is difficult to crystallize because the middle benzene ring has a substituent.
In particular, when the total number of substituents is 1, any one of X ¹ , X ² , X ⁵ , and X ⁶ is preferably —CH ₃ , a fluorine atom, or a chlorine atom, and —CH ₃ or fluorine More preferably it is an atom. When one benzene ring has two substituents and the total number of substituents is 2, X ¹ and X ² or X ⁵ and X ⁶ are preferably fluorine atoms. .

  Specific examples of the chiral compound A represented by the above formula (2) include chiral compounds A represented by the following general formulas (2-1) to (2-4).

In the above formula ^{(2-1) ~ (2-4),} R 11 is a straight, branched or cyclic saturated or unsaturated alkyl group having 1 to 10 carbon atoms, among ^{them, R 11} is straight It is preferably a chain or branched saturated alkyl group or a phenylalkyl group. * Indicates a chiral center, and m is 0 or 1. p is 4 to 18, preferably 6 to 18, and more preferably 6 to 12. In the above formulas (2-1) and (2-2), X ²¹ and X ²² each independently represent —CH ₃ , —CF ₃ or a halogen atom, and among them, —CH ₃ , a fluorine atom or a chlorine atom represents preferable. The positions of X ²¹ and X ²² are the same as the positions of X ^{1 to} X ⁸ described above. One of j and k is 0 and the other is 1.

  Specific examples of the chiral compound A represented by the above formulas (2-1) to (2-4) include the chiral compound A represented by the following formula.

As such a chiral compound A, 1 type may be used independently and 2 or more types may be mixed and used for it.
The chiral compound A can be synthesized, for example, by the method described in International Publication No. 2010/031431.

(2) Chiral compound B
The chiral compound B used in the present invention is represented by the following general formula (3).

In the above formula (3), K ² represents a single bond or a cyclohexane ring. When K ² is a single bond, as represented by the following general formula (3-1), the chiral compound B is obtained by directly bonding four benzene rings. When K ² is a cyclohexane ring, as represented by the following general formula (3-2), the chiral compound B is obtained by directly bonding four benzene rings and one cyclohexane ring. Among these, K ² is preferably a single bond.

In the above formula (3), R ⁴⁰ is a non-chiral group and is a saturated or unsaturated alkyl group or alkoxyalkyl group having 4 to 18 carbon atoms which may be substituted with a halogen atom. Note ^{that R 40} is the same as the ^{R 10} in the formula (2), description thereof is omitted here.

In the above formula (3), R ⁵⁰ is a chiral group having one or more chiral centers, and is a group represented by the above formula (4). In addition, about group represented by the said Formula (4), since it is the same as that of the case of the said chiral compound A, description here is abbreviate | omitted.

In the above formula (3), X ^{9 to} X ²⁰ each independently represent —CH ₃ , —CF ₃ , a halogen atom or a hydrogen atom. However, one or more of X ^{9 to} X ²⁰ are each independently —CH ₃ , —CF ₃ or a halogen atom. Note that the reason why one or more of X ^{9 to} X ²⁰ is —CH ₃ , —CF ₃ or a halogen atom is the same as in the case of X ^{1 to} X ⁸ in the above formula (2). Description of is omitted.

Among ^them, any one or more of ^{X 9 ~X 13, X 15 ~X} 19 is, _-CH 3 each independently is preferably a -CF ₃ or a halogen atom. This is because the chiral compound has better solubility than the X ¹⁴ and X ²⁰ positions when it has a substituent at the X ^{9 to} X ¹³ and X ^{15 to} X ¹⁹ positions. This is presumably because the X ¹⁴ and X ²⁰ positions are less distorted by substituents than the other positions.

Among the three benzene rings to which X ^{9 to} X ²⁰ are bonded, the benzene ring having a substituent can have 1 to 4 substituents, and among them, has 1 to 2 substituents. It is preferable. When one benzene ring has one substituent, the substituent is preferably —CH ₃ , a fluorine atom or a chlorine atom, and more preferably —CH ₃ or a fluorine atom. Moreover, when one benzene ring has two substituents, it is preferable that all the substituents are fluorine atoms. In this case, as the position of the two substituents, for the same reason as in the case of the chiral compound A, for example, when X ¹¹ and X ¹² are fluorine atoms, each adjacent carbon atom of the benzene ring is It is preferable that the fluorine atom is substituted.
In addition, the chiral compound represented by the above formula (3) preferably has 1 to 2 substituents in total.
Furthermore, it is preferable that one benzene ring has a substituent among the benzene rings to which X ^{9 to} X ²⁰ are bonded. Among them, from the viewpoint of suppressing crystallization, a benzene ring located in the middle, specifically, Any of the benzene ring to which X ⁹ , X ¹⁰ , X ¹⁵ and X ¹⁶ are bonded and the benzene ring to which X ¹¹ , X ¹² , X ¹⁷ and X ¹⁸ are bonded preferably has a substituent.
In particular, when the total number of substituents is 1, any one of X ^{9 to} X ²⁰ is preferably —CH ₃ , a fluorine atom or a chlorine atom, and more preferably —CH ₃ or a fluorine atom. . Moreover, when one benzene ring has two substituents and the total number of substituents is 2, X ⁹ and X ¹⁰ , X ¹¹ and X ¹² , X ¹⁵ and X ¹⁶ , or X ¹⁷ And X ¹⁸ is preferably a fluorine atom.

In the above formulas (3-1) and (3-2), R ⁴⁰ , R ⁵⁰ , and X ^{9 to} X ²⁰ are the same as those in the above formula (3).

  Specific examples of the chiral compound B represented by the above formula (3) include chiral compounds B represented by the following general formulas (3-3) to (3-10).

In the above formulas (3-3) to (3-10), R ¹² is a saturated or unsaturated linear, branched or cyclic alkyl group having 1 to 10 carbon atoms. Among them, R ¹² is saturated. It is preferably a linear or branched alkyl group or a phenylalkyl group. * Indicates a chiral center, m is 0 or 1, and the 1st or 2nd carbon atom is the chiral center. v is 4 to 18, preferably 6 to 18, and more preferably 6 to 12. In the above formulas (3-3), (3-4), (3-7) and (3-8), X ^{31 to} X ³³ each independently represent —CH ₃ , —CF ₃ or a halogen atom, Among these, —CH ₃ , a fluorine atom or a chlorine atom is preferable. The positions of X ^{31 to} X ³³ are the same as the positions of X ^{9 to} X ²⁰ described above. any one or two of r, s, and t are 1, and the rest are 0. In the above formulas (3-5), (3-6), (3-9), and (3-10), y and One z is 1 and the other is 0.

  Specific examples of the chiral compound B represented by the above formulas (3-3) to (3-10) include a chiral compound B represented by the following formula.

As such a chiral compound B, 1 type may be used independently and 2 or more types may be mixed and used for it.
For example, the ferroelectric liquid crystal composition may contain a chiral compound B represented by the above formula (3-1) and a chiral compound B represented by the above formula (3-2).

  The chiral compound B can be synthesized, for example, by the method described in International Publication No. 2010/031431.

(3) Chiral compound A and chiral compound B
When the ferroelectric liquid crystal composition of the present invention contains at least one of the chiral compound A and the chiral compound B, it may contain only the chiral compound A, may contain only the chiral compound B, Chiral compound A and chiral compound B may be contained. Further, when the ferroelectric liquid crystal composition contains the chiral compound A, it may contain one kind of chiral compound A or two or more kinds of chiral compounds A. Similarly, when the ferroelectric liquid crystal composition contains the chiral compound B, it may contain one kind of chiral compound B or may contain two or more kinds of chiral compounds B.

  In particular, the ferroelectric liquid crystal composition of the present invention preferably contains a chiral compound A and a chiral compound B. In addition, the ferroelectric liquid crystal composition of the present invention includes a chiral compound B1 in which four benzene rings represented by the above formula (3-1) are directly bonded and 4 represented by the above formula (3-2). It is also preferable to contain a chiral compound B2 in which one benzene ring and one cyclohexane ring are directly bonded. It is because impact resistance can be effectively improved by containing such two types of chiral compounds.

  When the ferroelectric liquid crystal composition of the present invention contains only the chiral compound A, the content of the chiral compound A in the ferroelectric liquid crystal composition is particularly limited as long as an impact resistance effect is obtained. Is not to be done. When one of the above chiral compounds A is used alone, the content of the chiral compound A is ferroelectric. When two or more of the above chiral compounds A are mixed, each content of two or more of the chiral compounds A is ferroelectric. It is preferable that it is 5 mass% or more in a crystalline liquid crystal composition. Among them, when the chiral compound A is used alone, the content of the chiral compound A is, and when two or more chiral compounds A are mixed, the total content of the two or more chiral compounds A is In the ferroelectric liquid crystal composition, it is preferably in the range of 5% by mass to 35% by mass, and more preferably in the range of 15% by mass to 30% by mass. If the content of the chiral compound A is less than the above range, the desired impact resistance may not be obtained. On the other hand, if the content of the chiral compound A is more than the above range, the ferroelectric liquid crystal composition may be obtained. In some cases, the viscosity becomes high or the crystallized easily, and sufficient impact resistance may not be obtained, and it may be difficult to form a liquid crystal layer when manufacturing a liquid crystal display element. is there.

  When the ferroelectric liquid crystal composition of the present invention contains only the chiral compound B, the content of the chiral compound B in the ferroelectric liquid crystal composition is particularly limited as long as an impact resistance effect is obtained. The content is the same as that of the chiral compound A.

  When the ferroelectric liquid crystal composition of the present invention contains the chiral compound A and the chiral compound B, the total content of the chiral compound A and the chiral compound B in the ferroelectric liquid crystal composition has an impact resistance effect. If it is a grade obtained, it will not specifically limit, It is the same as that of content of the said chiral compound A.

  Further, when the ferroelectric liquid crystal composition of the present invention contains the chiral compound A and the chiral compound B, the content of the chiral compound B in the ferroelectric liquid crystal composition is not less than the content of the chiral compound A. Is preferred. Since the chiral compound A has a tendency to reduce the tilt angle of the liquid crystal molecules when a voltage is applied as compared with the chiral compound B, if the content of the chiral compound A is increased compared to the chiral compound B, the liquid crystal molecules There is a possibility that the tilt angle becomes small and sufficient brightness cannot be obtained. On the other hand, when the chiral compound B is contained in a larger amount than the chiral compound A, the tilt angle of the liquid crystal molecules can be increased and the driving performance can be improved.

3. Host liquid crystal The ferroelectric liquid crystal composition of the present invention may further contain a host liquid crystal.
As the host liquid crystal, those generally used as the host liquid crystal of the ferroelectric liquid crystal composition can be used, and examples thereof include a phenylpyrimidine compound.
Here, since the phenylpyrimidine compound has at least two aromatic rings of a benzene ring and a pyrimidine ring in the core portion, birefringence tends to increase, but in the present invention, the compound represented by the above formula (1) is added. Therefore, the birefringence of the ferroelectric liquid crystal composition can be reduced.
A host liquid crystal may be used individually by 1 type, and 2 or more types may be mixed and used for it.

  The content of the host liquid crystal in the ferroelectric liquid crystal composition is not particularly limited as long as the content of the chiral compound can be within the above range.

4). Ferroelectric liquid crystal composition The ferroelectric liquid crystal composition of the present invention is not particularly limited as long as it exhibits a chiral smectic C (SmC ^* ) phase. As the phase series of the ferroelectric liquid crystal composition, for example, a phase change with a nematic (N) phase-cholesteric (Ch) phase-SmC ^* phase, a phase change with an N phase-SmC ^* phase in the temperature lowering process, Examples thereof include those that change phase with N phase-smectic A (SmA) phase-SmC ^* phase and those that change phase with N phase-Ch phase-SmA phase-SmC ^* phase.

  In addition, as the ferroelectric liquid crystal composition, either one showing bistability or one showing monostability can be used. Among these, a ferroelectric liquid crystal composition exhibiting monostability is preferable. When a ferroelectric liquid crystal composition exhibiting monostability is used, gradation display is achieved by continuously changing the director of the liquid crystal (inclination of the molecular axis) by changing the voltage and analog-modulating the transmitted light intensity. This is because it becomes possible. In particular, when the liquid crystal display element is driven by a field sequential color system, it is preferable to use a ferroelectric liquid crystal composition exhibiting monostability. By using a ferroelectric liquid crystal composition exhibiting monostability, it becomes possible to drive by an active matrix method using TFTs, and also to control gradation by voltage modulation, so that high-definition and high-quality display is possible. This is because it can be realized.

  Note that “showing monostability” means a state in which the state of liquid crystal molecules when no voltage is applied is stabilized in one state. In the ferroelectric liquid crystal composition, as illustrated in FIG. 1, the liquid crystal molecules 25 are tilted from the layer normal z and rotate along a cone ridge having a bottom surface perpendicular to the layer normal z. . In such a cone, the tilt angle of the liquid crystal molecules 25 with respect to the layer normal z is referred to as a tilt angle θ. Thus, the liquid crystal molecules 25 can operate on the cone between two states inclined by a tilt angle ± θ with respect to the layer normal z. Specifically, the expression of monostability refers to a state in which the liquid crystal molecules 25 are stabilized in any one state on the cone when no voltage is applied.

  In addition, the ferroelectric liquid crystal composition only needs to exhibit monostability, and exhibits a half V-shaped switching characteristic in which liquid crystal molecules operate only when a positive or negative voltage is applied. A V-shaped switching characteristic in which liquid crystal molecules operate to the same degree with respect to voltage, asymmetric switching in which the operation of liquid crystal molecules for either positive or negative voltage is larger than the operation of liquid crystal molecules for the other polarity voltage Any of those exhibiting properties can be used.

Such a ferroelectric liquid crystal composition can be variously selected from generally known liquid crystal materials according to required characteristics. In particular, the ferroelectric liquid crystal composition that expresses the SmC ^* phase from the Ch phase without passing through the SmA phase is preferable because the change in the operating characteristics with respect to the voltage is small with respect to the temperature change.

C. Liquid crystal display element The liquid crystal display element of the present invention includes a first base material, a first electrode layer formed on the first base material, and a first alignment film formed on the first electrode layer. A second alignment treatment substrate having a first alignment treatment substrate, a second base material, a second electrode layer formed on the second base material, and a second alignment film formed on the second electrode layer; And a liquid crystal layer formed between the first alignment film and the second alignment film and including the above-described ferroelectric liquid crystal composition.

The liquid crystal display element of the present invention will be described with reference to the drawings.
FIG. 2 is a cross-sectional view showing an example of the liquid crystal display element of the present invention. As illustrated in FIG. 2, the liquid crystal display element 1 is formed on the first base material 2a, the first electrode layer 3a formed on the first base material 2a, and the first electrode layer 3a. The first alignment processing substrate 11a having the first alignment film 4a, the second base material 2b, the second electrode layer 3b formed on the second base material 2b, and the second electrode layer 3b A second alignment treatment substrate 11b having a second alignment film 4b; and a liquid crystal layer 5 formed between the first alignment film 4a and the second alignment film 4b. A dielectric liquid crystal composition is contained.

In the present invention, since the ferroelectric liquid crystal composition contains the compound represented by the above formula (1), the birefringence of the ferroelectric liquid crystal composition can be reduced, so that the cell gap is relatively small. Even if it is large, a good white display can be obtained, and as a result, the yield is improved. In addition, the transmittance of the liquid crystal display element can be maintained without extremely reducing the tilt angle of the liquid crystal molecules. Furthermore, when the ferroelectric liquid crystal composition contains a chiral compound that improves impact resistance, the impact resistance can be maintained.
Hereinafter, each structure in the liquid crystal display element of this invention is demonstrated.

1. Liquid Crystal Layer The liquid crystal layer in the present invention is formed between the first alignment film of the first alignment treatment substrate and the second alignment film of the second alignment treatment substrate, and contains the ferroelectric liquid crystal composition.
The ferroelectric liquid crystal composition has been described in detail in the above-mentioned section “B. Ferroelectric liquid crystal composition”, and thus the description thereof is omitted here.

  The thickness of the liquid crystal layer is preferably in the range of 2.0 μm to 10.0 μm, more preferably in the range of 2.3 μm to 5.0 μm, and still more preferably in the range of 2.5 μm to 3.5 μm. is there. If the thickness of the liquid crystal layer is too thin, defects may be conspicuous due to the inclusion of foreign matters at the time of manufacturing. Conversely, if the thickness of the liquid crystal layer is too thick, the liquid crystal molecules are difficult to align and the contrast may be lowered. It is. The thickness of the liquid crystal layer can be adjusted by a bead spacer, a columnar spacer, a partition wall, or the like.

As a method for forming the liquid crystal layer, a method generally used as a method for manufacturing a liquid crystal cell can be used. For example, a vacuum injection method, a liquid crystal dropping method, or the like can be used.
When aligning the ferroelectric liquid crystal composition, it may be cooled slowly, and it is not necessary to apply a voltage to the liquid crystal layer.

2. 1st orientation processing board The 1st orientation processing board used for the present invention is the 1st base material, the 1st electrode layer formed on the 1st base material, and the 1st orientation formed on the 1st electrode layer. And a film.
Hereinafter, each structure in a 1st orientation processing board | substrate is demonstrated.

(1) 1st alignment film The 1st alignment film used for this invention will not be specifically limited if the alignment control of a ferroelectric liquid-crystal composition is possible, For example, a photo-alignment film, a rubbing alignment Examples thereof include a film and an oblique deposition alignment film. Hereinafter, these alignment films will be described.

(A) Photo-alignment film The photoexcitation reaction used for forming the photo-alignment film can be roughly divided into a photoreaction and a photoisomerization reaction. Examples of the photoreaction include a photodimerization reaction and a photolysis reaction.
As the material, forming method, and thickness of the photo-alignment film, general materials can be applied. For example, JP 2006-350322 A, JP 2006-323214 A, JP 2005-258429 A, The thing as described in Unexamined-Japanese-Patent No. 2005-258428 etc. can be used.

(B) Rubbing alignment film As the material, forming method, and thickness of the rubbing alignment film, general materials can be applied.

(C) Composition of constituent materials of first alignment film and second alignment film In the present invention, it is preferable that the constituent materials of the first alignment film and the second alignment film have different compositions with the liquid crystal layer interposed therebetween. By forming the first alignment film and the second alignment film using materials having different compositions, the polarities of the first alignment film surface and the second alignment film surface can be made different depending on the respective materials. As a result, the polar surface interaction between the ferroelectric liquid crystal composition and the first alignment film is different from the polar surface interaction between the ferroelectric liquid crystal composition and the second alignment film. By appropriately selecting the material in consideration of the surface polarity of the second alignment film, it is possible to suppress the occurrence of alignment defects such as zigzag defects, hairpin defects, and two types of domains having different stable states of liquid crystal molecules when no voltage is applied. Because it can. As a result, contrast can be improved.

In order to make the constituent materials of the first alignment film and the second alignment film have different compositions across the liquid crystal layer, for example, one may be a photo-alignment film and the other a rubbing alignment film.
Further, for example, both are rubbed alignment films, and the composition of the constituent materials of the rubbing alignment film is different; both are the photo-alignment films, and the composition of the constituent materials of the photo-alignment film may be different.

  When the first alignment film and the second alignment film are rubbing alignment films, the composition is changed by changing the skeleton, substituent, side chain, changing the amount of the additive, and the presence or absence of the additive. You can also.

Further, when the first alignment film and the second alignment film are photo-alignment films, for example, by using a photoisomerizable material for one photo-alignment film and a photo-reactive material for the other photo-alignment film, The composition of the constituent material of the alignment film can be different.
Further, when the first alignment film and the second alignment film are photo-alignment films using photoisomerizable materials, the isomerization-reactive skeleton, substituents, side chains, etc. may be changed, or monomolecular compounds and polymerizable monomers may be used. Each can be used, the amount of additive can be changed, or the composition can be changed depending on the presence or absence of the additive.
Furthermore, when the first alignment film and the second alignment film are photo-alignment films using a photo-dimerization type material, the dimerization reaction site, the substituent, the side chain, etc. may be changed, or the additive addition amount may be changed. The composition can be changed depending on the presence or absence of additives.

(2) 1st electrode layer The 1st electrode layer used for this invention will not be specifically limited if it is generally used as an electrode of a liquid crystal display element.

(3) 1st base material The 1st base material used for this invention will not be specifically limited if generally used as a base material of a liquid crystal display element, For example, a glass plate, a plastic plate, etc. are preferable. Can be mentioned.

(4) Other Configurations In the present invention, partition walls or columnar spacers may be formed on the first base material or the second base material. As the partition walls and columnar spacers, general partition walls and columnar spacers can be applied.

  In the present invention, a colored layer may be formed on the first base material or the second base material. When the colored layer is formed, a color filter type liquid crystal display element capable of realizing color display by the colored layer can be obtained. A general layer can be applied as the colored layer.

3. Second alignment treatment substrate The second alignment treatment substrate used in the present invention includes a second base material, a second electrode layer formed on the second base material, and a second orientation formed on the second electrode layer. And a film.

  In addition, about a 2nd base material, a 2nd electrode layer, a 2nd orientation film, and other structures, with the 1st base material in a said 1st orientation processing board | substrate, a 1st electrode layer, a 1st orientation film, and another structure, respectively. Since it is the same, description here is abbreviate | omitted.

4). Method for driving liquid crystal display element As a method for driving the liquid crystal display element of the present invention, the high-speed response of the ferroelectric liquid crystal composition can be used. Therefore, it can be suitably used for a field sequential color system that requires high-speed response.
Further, the driving method of the liquid crystal display element of the present invention is not limited to the field sequential method, and may be a color filter method that performs color display using a colored layer.

As a driving method of the liquid crystal display element of the present invention, an active matrix system using a thin film transistor (TFT) is preferable. This is because by adopting an active matrix system using TFTs, the target pixel can be reliably turned on and off, and a high-quality display becomes possible.
Further, the driving method of the liquid crystal display element of the present invention may be a segment method.

  The present invention is not limited to the above embodiment. The above-described embodiment is an exemplification, and the present invention has substantially the same configuration as the technical idea described in the claims of the present invention, and any device that exhibits the same function and effect is the present invention. It is included in the technical scope of the invention.

  Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples.

[Example 1]
A compound represented by the following formula was synthesized.

First, 40 ml of anhydrous THF was prepared under a nitrogen atmosphere, and 1.57 g (41.4 mmol) of LiAlH ₄ was added to the ice-cooled anhydrous THF, followed by stirring for 15 minutes. Thereto, 5.5 g (27.7 mmol) of 4-trans-pentyl-cyclohexanecarboxylic acid solution dissolved in 20 ml of anhydrous THF was added dropwise over 15 minutes, and then returned to room temperature and stirred for 2 hours. Next, 4 ml of water and 4.5 ml of a 15% aqueous solution of NaOH were added to this solution, and the mixture was stirred for 20 minutes, followed by celite filtration to remove insoluble matters. Subsequently, the filtrate obtained by Celite filtration was extracted with ethyl acetate, and the organic layer was washed with saturated brine and water. Thereafter, the organic layer was dried over MgSO ₄ , concentrated and dried under reduced pressure to obtain colorless and oily 4-trans-n-pentyl-cyclohexane-methanol. The obtained compound was 5.1 g, and the yield was 100%.

Under a nitrogen atmosphere, 2.5 g (19.2 mmol) of 2,3-difluorophenol and 3.9 g (21.2 mmol) of 4-trans-n-pentyl-cyclohexane-methanol were dissolved in 40 ml of anhydrous THF. A solution was prepared, and 11.1 g (42.3 mmol) of triphenylphosphine was added and ice-cooled. Thereto, 8.6 g (42.5 mmol) of diisopropyl azodicarboxylate was added dropwise over 30 minutes and stirred for 2 hours. After returning to room temperature and stirring for 12 hours, this solution was extracted with ethyl acetate, and the organic layer was washed with dilute hydrochloric acid and water. The organic layer was then dried over MgSO ₄ and concentrated to give a yellow oil. Subsequently, N-hexane was added to the oil, and the white solid precipitated at this time was removed by filtration and concentrated. Then, the obtained residue was purified by silica gel column chromatography (developing solution: N-hexane) to give 4-trans-n-pentyl-1- (2,3-difluoro-phenoxymethyl) cyclohexane as a white solid. Got. The obtained compound was 4.1 g, and the yield was 71.9%.

A solution prepared by dissolving 4.0 g (13.5 mmol) of 4-trans-n-pentyl-1- (2,3-difluoro-phenoxymethyl) cyclohexane in 20 ml of anhydrous THF under an Ar atmosphere condition is −40 ° C. or lower. Then, 10 ml (16 mmol) of 1.6 M butyllithium hexane solution was added dropwise over 15 minutes, and the mixture was stirred for 4 hours. Next, 1.68 g (16.2 mmol) of trimethoxyborane was added dropwise to the obtained solution over 10 minutes, followed by stirring for 12 hours. The solution was then allowed to warm to room temperature, acidified by the addition of dilute aqueous hydrochloric acid and stirred for 24 hours, the solution extracted with ethyl acetate, the organic layer dried over MgSO ₄ and concentrated in vacuo. Thereafter, N-hexane was added to the obtained residue and the mixture was ice-cooled, and the precipitated crystals were collected by filtration to give 4- (4-trans-n-pentyl-cyclohexylmethyloxy) -2,3- Difluoro-phenylboronic acid was obtained. The obtained compound was 3.0 g, and the yield was 65.3%.

  To 3.0 g (8.8 mmol) of 4- (4-trans-n-pentyl-cyclohexylmethyloxy) -2,3-difluoro-phenylboronic acid was added 15 ml of acetic acid and then 30% peroxidation at room temperature. 1.5 ml of aqueous solution was added slowly. Next, this solution was stirred for 2 hours, water was added and the precipitated crystals were collected by filtration to give 4- (4-trans-n-pentyl-cyclohexylmethyloxy) -2,3-difluoro as a pale yellow powder. -Phenol was obtained. The obtained compound was 2.7 g, and the yield was 98%.

In a solution of 0.5 g (1.6 mmol) of 4- (4-trans-n-pentyl-cyclohexylmethyloxy) -2,3-difluoro-phenol in 15 ml of anhydrous methylene chloride under conditions of nitrogen atmosphere, 0.3 g of triethylamine was added and ice-cooled. To this solution, a solution of 0.416 g (1.9 mmol) of trans-4-n-pentylcyclohexylcarbonyl chloride dissolved in 5 ml of methylene chloride was added dropwise over 10 minutes and stirred for 20 minutes. Next, this solution was returned to room temperature, stirred for 1 hour, extracted by adding dilute hydrochloric acid and methylene chloride, and the organic layer was washed with water, dried over MgSO ₄ , and concentrated under reduced pressure. Thereafter, methanol was added to the obtained residue, and the mixture was stirred at room temperature for 1 hour, and the precipitated crystals were collected by filtration to obtain a compound represented by the following formula as a white solid as the final product. The obtained compound was 0.69 g, and the yield was 87.6%.

The results of ¹ H-NMR of the obtained compound were as follows.
¹ H NMR (400MHz, CDCl ₃ , TMS): δ (ppm) 0.87-1.095 (m, 12H, CH ₂ + CH ₃ ), 1.17-1.31 (m, 18H, CH ₂ ), 1.50-1.60 (m, 2H , CH ₂ ), 1.61-1.90 (m, 7H, CH ₂ + CH), 2.12-2.14 (m, 2H, CH ₂ ), 2.47-2.545 (m, 1H, CHCO), 3.80 (d, J = 6.4Hz , 2H, ArOCH ₂ ), 6.64-6.69 (m, 1H, arom.H), 6.74-6.79 (m, 1H, arom.H).

[Example 2]
A compound represented by the following formula was synthesized.

First, 5.016 g (38.557 mmol) of 2,3-difluorophenol and 6.421 g (46.460 mmol) of potassium carbonate were added in 30 ml of DMF in the presence of 4.45 ml (37.414 mmol) of benzyl bromide. The mixture was added and stirred at 90 ° C. for 1.5 hours in an Ar atmosphere. It was then extracted with 50 ml dichloromethane and 30 ml water and the dichloromethane layer was washed twice with 300 ml water. Thereafter, the filtrate obtained after filtration by drying with MgSO ₄ was concentrated and dried under reduced pressure to obtain oily 2,3-difluorophenylbenzyl ether. The obtained compound was 8.079 g, and the yield was 95.1%.

Under conditions of Ar atmosphere, 8.066 g (36.627 mmol) of 2,3-difluorophenylbenzyl ether was added to 30 ml of THF, and the mixture was stirred at −40 ° C. or lower, and 24 ml of a 1.65 M butyllithium hexane solution was added thereto. (39.60 mmol) was added dropwise. Then, after stirring this solution for 3 hours, dry ice was added and it stirred overnight. Subsequently, extraction with 100 ml of dichloromethane, 300 ml of water and 5 ml of concentrated hydrochloric acid, drying of the organic layer with MgSO ₄ , concentration of the filtrate obtained after filtration and recrystallization from dichloromethane-hexane gave a white solid. 4-Benzyloxy-2,3-difluorobenzoic acid was obtained. The obtained compound was 2.978 g, and the yield was 30.8%.

  Under conditions of Ar atmosphere, 2.508 g (9.492 mmol) of 4-benzyloxy-2,3-difluorobenzoic acid was added to 15 ml of THF and 7.5 ml of trimethoxyborane, and the mixture was stirred under ice cooling. Next, 10 ml (20 mmol) of a 2M borane-dimethylsulfide complex in THF was added dropwise to the solution, and the mixture was stirred overnight at room temperature. Thereafter, this solution was poured into 200 ml of ice water, and the resulting precipitate was collected by filtration and dried under reduced pressure to obtain white solid 4-benzyloxy-2,3-difluorobenzyl alcohol. The obtained compound was 2.262 g, and the yield was 95.2%.

Under conditions of Ar atmosphere, 2.257 g (9.019 mmol) of 4-benzyloxy-2,3-difluorobenzyl alcohol was added to 20 ml of dichloromethane and stirred at room temperature. To this solution, 11 ml (11 mmol) of 1M phosphorus tribromide in dichloromethane was added dropwise and stirred overnight at room temperature, and then 100 ml of ice water was poured into the solution and separated. Thereafter, the organic layer was washed with 300 ml of water, dried over MgSO ₄ , and the filtrate obtained after filtration was concentrated and dried under reduced pressure to obtain 4-benzyloxy-2,3-difluorobenzyl bromide as a white solid. It was. The obtained compound was 2.562 g, and the yield was 90.7%.

Under conditions of Ar atmosphere, 2.573 g (8.217 mmol) 4-benzyloxy-2,3-difluorobenzyl bromide, 1.400 g (8.221 mmol) trans-pentyl in 15 ml THF and 5 ml DMF. Cyclohexanol and 0.551 g sodium hydride (60% in oil) (0.331 g (13.776 mmol) sodium hydride) were added and stirred overnight at 60 ° C. The solution was then extracted with 30 ml dichloromethane and 300 ml water, the organic layer was washed twice with 300 ml water, dried over MgSO ₄ and the filtrate obtained after filtration was concentrated. Then, the obtained residue was purified by silica gel column chromatography (developing solution: dichloromethane) to obtain 2,3-difluoro-4- (trans-pentylcyclohexyl) oxymethylphenylbenzyl ether as a white solid. The obtained compound was 2.799 g, and the yield was 84.6%.

  Under conditions of hydrogen atmosphere, 2.775 g (6.893 mmol) of 2,3-difluoro-4- (trans-pentylcyclohexyl) oxymethylphenylbenzyl ether, 0.550 g of 10 in 5 ml of THF and 10 ml of ethanol. % Palladium on carbon and 3 drops of concentrated hydrochloric acid were added, and the mixture was stirred overnight at 60 ° C. and filtered. Thereafter, the residue obtained by concentration was purified by silica gel column chromatography (developing solution: dichloromethane) to obtain 2,3-difluoro-4- (trans-pentylcyclohexyl) oxymethylphenol as a white solid. The obtained compound was 1.393 g, and the yield was 64.7%.

Under conditions of Ar atmosphere, 0.402 g (1.287 mmol) of 2,3-difluoro-4- (trans-pentylcyclohexyl) oxymethylphenol, 0.311 g (1.435 mmol) of trans- 4-Pentylcyclohexylcarbonyl chloride and 0.27 ml triethylamine were added and stirred overnight at room temperature. The trans-4-pentylcyclohexylcarbonyl chloride was obtained by reacting the corresponding carboxylic acid with thionyl chloride. The solution was then extracted with 20 ml dichloromethane and 150 ml water, the organic layer was washed with 150 ml water, dried over MgSO ₄ and the filtrate obtained after filtration was concentrated. Thereafter, the obtained residue was purified by silica gel column chromatography (developing solution: dichloromethane), followed by recrystallization from dichloromethane-methanol to obtain a compound represented by the following formula as a white solid. The obtained compound was 0.471 g, and the yield was 74.3%.

The results of ¹ H-NMR of the obtained compound were as follows.
¹ H NMR (400MHz, CDCl ₃ , TMS): δ (ppm) 0.845-1.03 (m, 10H, CH + CH ₂ + CH ₃ ), 1.13-1.35 (m, 20H, CH + CH ₂ ), 1.51-1.685 (m, 2H, CH ₂ ), 1.77-1.89 (m, 4H, CH ₂ ), 2.05-2.16 (m, 4H, CH ₂ ), 2.485-2.565 (m, 1H, CHCO), 3.25-3.33 (m, 1H, OCH), 4.595 (s, 2H, ArCH ₂ O), 6.85-6.89 (m, 1H, arom.H), 7.16-7.21 (m, 1H, arom.H).
The measurement result of MALDI-TOF-MS (matrix: dithranol + TFANa) was m / z = 516.67 ([M + Na] ⁺ ).

[Examples 3 to 10, Comparative Examples 1 to 3]
(Ferroelectric liquid crystal composition)
Using the compounds A to F shown below, a ferroelectric liquid crystal composition was prepared as shown in Table 3 below. In addition, content of host liquid crystal I-III is an equal ratio, respectively.

(Production of liquid crystal display element)
First, resin spacers having a diameter of Φ5.0 μm and a height of 2.0 μm were formed on a glass substrate 1 coated with ITO at a pitch of 0.1 mm. Subsequently, a rubbing alignment film material (SE610: Nissan Chemical Industries, Ltd.) was spin-coated at a rotation speed of 1500 rpm for 30 seconds. Thereafter, the substrate was dried in an oven at 180 ° C. for 30 minutes, and then rubbed.

  Further, a solution of a photoisomerization type photo-alignment film material (LIA012: DIC Corporation) was spin-coated at 1500 rpm for 30 seconds on the glass substrate 2 coated with ITO. Thereafter, after drying in an oven at 100 ° C. for 3 minutes, 2J-polarized exposure processing was performed with a polarizing exposure machine.

  Next, a sealing material was applied in a square frame shape on the substrate. The ferroelectric liquid crystal composition described above was applied to the substrate in the form of dots, and the two substrates were assembled and thermocompression bonded so that the rubbing treatment direction and the polarization treatment direction were perpendicular. Thereafter, the liquid crystal cell was cooled to align the ferroelectric liquid crystal composition. The thickness of the liquid crystal layer was 2.0 μm.

(Evaluation)
1. Chromaticity The birefringence of the liquid crystal display element was evaluated by measuring the chromaticity by installing a lambda vision microspectroscopy system TFCAM-7000 on an Olympus polarizing microscope BX51. First, two polarizing plates in a polarizing microscope were set in a parallel state, chromaticity was measured for an empty cell not filled with a ferroelectric liquid crystal composition, and a standard light source was measured. Thereafter, the two polarizing plates in the polarizing microscope were set in a crossed Nicol state, and the liquid crystal cell filled with the ferroelectric liquid crystal composition was rotated to a position where the amount of transmitted light was maximized. The chromaticity was measured in that state.

2. Tilt angle The angle at which the liquid crystal molecules moved was measured with a polarizing microscope. A liquid crystal cell filled with a ferroelectric liquid crystal composition is placed between two polarizing plates set in a crossed Nicol state, and a positive voltage (10 V) and a negative voltage are based on the position of black display when no voltage is applied. The angle of the liquid crystal molecules that moved when (-10 V) was applied was measured.

3. Transmittance The transmittance of the liquid crystal display element was calculated from the tilt angle.
Here, the transmittance I of the liquid crystal display element is generally obtained by the following formula (a).
I = I ₀ sin ² (2θ) × sin ² (Δnd / λ) (a)
(In the above formula (a), I ₀ : incident light intensity (constant), θ: tilt angle, Δn: birefringence, d: cell gap, λ: wavelength)
In the present embodiment, the term sin ² (2θ) in the above formula (a) is calculated from the tilt angle θ ₁ when a positive voltage is applied and the tilt angle θ ₂ when a negative voltage is applied, and the average is the transmittance. T.
T = {sin ² (2θ ₁ ) + sin ² (2θ ₂ )} / 2 (b)
In the above formula (a), as the term sin ² (2θ) increases, the transmittance I also increases. Therefore, if the transmittance T is large, it can be said that the transmittance of the liquid crystal display element is high.
The evaluation results are shown in Table 4. FIG. 3 shows a chromaticity diagram.

In the chromaticity diagram shown in FIG. 3, the liquid crystal display device using the ferroelectric liquid crystal composition to which the compounds C to F of the present invention of Examples 4, 8, 9, and 10 are added is the same as that of Comparative Example 1. Compared to the liquid crystal display element to which no compound was added, the birefringence was reduced, and it was close to white.
In Examples 3 to 10 using the ferroelectric liquid crystal compositions to which the compounds C to F were added, Comparative Examples 2 and 3 using the ferroelectric liquid crystal compositions to which the compounds A and B were added. Compared with, the tilt angle of the liquid crystal molecules increased and the transmittance increased. From this result, it was found that the carbon number of the ether bond and the alkyl group contributed to the improvement of the transmittance in the structure of the compound of the present invention.
In particular, in Examples 3 to 7 using the ferroelectric liquid crystal composition to which the compound C of the present invention is added, the tilt angle of the liquid crystal molecules can be increased and the transmittance of the liquid crystal display element can be improved. did it.

DESCRIPTION OF SYMBOLS 1 ... Liquid crystal display element 2a ... 1st base material 2b ... 2nd base material 3a ... 1st electrode layer 3b ... 2nd electrode layer 4a ... 1st orientation film 4b ... 2nd orientation film 5 ... Liquid crystal layer 11a ... 1st orientation Processed substrate 11b ... Second alignment processed substrate

Claims (3)

A compound having a structure represented by the following general formula (1):

(In the above formula (1), R ¹ and R ² are linear or branched alkyl groups having 3 to 7 carbon atoms, provided that at least one of R ¹ and R ² has 5 carbon atoms. That's it.
A is —O—CH ₂ — or —CH ₂ —O—.
Z ¹ and Z ² each independently represent a fluorine atom or a hydrogen atom. However, at least one of Z ¹ and Z ² is a fluorine atom. )   A ferroelectric liquid crystal composition comprising the compound according to claim 1. A first alignment treatment substrate having a first substrate, a first electrode layer formed on the first substrate, and a first alignment film formed on the first electrode layer;
A second substrate having a second substrate, a second electrode layer formed on the second substrate, and a second alignment film formed on the second electrode layer;
A liquid crystal display device comprising a liquid crystal layer formed between the first alignment film and the second alignment film and including a ferroelectric liquid crystal composition,
The said ferroelectric liquid crystal composition contains the compound of Claim 1, The liquid crystal display element characterized by the above-mentioned.

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