JPH069961A - Ferroelectric liquid crystal composition and liquid crystal display element - Google Patents

Abstract

PURPOSE:To obtain the title composition capable of high-speed response even in a liquid crystal display element of a small cell thickness by mixing a chiral compound with a mixture comprising a plurality of specified achiral compounds in a specified ratio. CONSTITUTION:The composition comprises a chiral compound {e.g. 5- octyl-2-[4-((2S)-2-fluorooctyloxy)phenyl]pyrimidine} and achiral compounds comprising 5-60wt.%, based on the composition, achiral compound of formula I wherein R<1> and R<2> are each 2-16C alkyl or alkoxyl, one or more of nonadjoining methylene groups of which may be replaced by an oxygen atom and 5-50wt.%, based on the composition, achiral compound of formula II wherein R<3> is 5-15C alkyl; and R<4> is 9-15C alkyl.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ferroelectric liquid crystal composition suitable for large-area, high-density, high-speed display, and particularly for use in a ferroelectric liquid crystal display device having a high response speed. The present invention relates to a dielectric liquid crystal composition and a liquid crystal display device using the ferroelectric liquid crystal composition.

[0002]

2. Description of the Related Art A twisted nematic (TN) type is a typical one which has been widely put into practical use as a display system for liquid crystal display devices. The TN type uses a nematic liquid crystal phase and has problems such as a slow response speed and poor viewing angle characteristics when used for a display, as compared with a display system such as a CRT (Cathode Ray Tube).
Therefore, the display has been limited to a limited number of uses.

Recently, surface-stabilized ferroelectric liquid crystal devices have been developed by Clark and Lagerwall.
22287, US Pat. No. 4,367,924, etc.). In this device, a ferroelectric liquid crystal sandwiched between substrates with a gap of about 2 μm combined with a polarizing plate controls the amount of transmitted light by changing the orientation of the molecular long axis according to the polarity of the applied electric field. It is characterized by high-speed response and bistability.
Moreover, since it is also excellent in viewing angle characteristics, this element is expected to be widely used as a large-capacity and high-density display element.

The above ferroelectric liquid crystal has a chiral smectic C (hereinafter abbreviated as Sc ^* ) as one of liquid crystal phases.
Have a phase. In order to use a ferroelectric liquid crystal as a display device, it has a wide Sc ^* phase (widens the practical temperature range), responds at high speed, and obtains good contrast at the time of display. Has many characteristics such as good bistability and good orientation.

Among the characteristics required for the above display device, it has been attempted to improve a wide range of Sc ^* phases by mixing a liquid crystal compound. As a method for preparing such a composition, for example,
A liquid crystal compound or a liquid crystal mixture (hereinafter, referred to as a smectic C (hereinafter abbreviated as Sc)) phase that does not exhibit ferroelectricity
A method of adding an optically active compound to a base liquid crystal is known (Mol. Cryst. Liq. Cryst., Vol. 89, 327).
(1982)). Here, as the component of the base liquid crystal exhibiting the Sc phase, a liquid crystal compound such as phenylbenzoate type, Schiff base type, biphenyl type, phenylpyrimidine type, phenylpyridine type liquid crystal is used.

In the ferroelectric liquid crystal, it is known that the response time is inversely proportional to the spontaneous polarization value, that is, it is effective to increase the spontaneous polarization value in order to increase the response speed. There is. The compound which is optically active plays a role of exhibiting spontaneous polarization of the ferroelectric liquid crystal composition when used as one component of the ferroelectric liquid crystal composition, and in order to increase the spontaneous polarization of the ferroelectric liquid crystal composition. Development of effective optically active compounds (chiral compounds) is underway. Such chiral compounds are simultaneously chiral nematic (hereinafter referred to as N ^*
It has the property of forming a spiral in the phase or Sc ^* phase. In a ferroelectric liquid crystal display device, it is necessary to orient the liquid crystal molecules in a single direction by using an orientation film, so that it is desirable that the pitch of the helix in the N ^* phase and the Sc ^* phase is long.

By the way, among the compounds effective for exhibiting a large spontaneous polarization, there is one that extremely shortens the pitch of the spiral to be formed. Therefore, when such a compound is used, an additive (hereinafter, sometimes referred to as a pitch canceling agent) that lengthens the pitch of the spiral without reducing spontaneous polarization is added to the liquid crystal composition. ing. The pitch canceling agent must (1) have spontaneous polarization in the same direction as the compound that causes spontaneous polarization or not exhibit spontaneous polarization, and (2) have a direction opposite to the spiral formed by the compound that induces spontaneous polarization. Forming a spiral, (3) the pitch of the spiral is as short as possible,
(4) It is desirable that the liquid crystal composition has physical properties such as not adversely affecting the phase transition. Conventionally, a compound having an optically active 2-methylbutyl group has been proposed as a pitch canceling agent (for example, JP-A-63-26).
However, it was not always sufficiently satisfactory.

[0008]

SUMMARY OF THE INVENTION An object of the present invention is to provide a ferroelectric liquid crystal composition capable of high-speed response, particularly a ferroelectric liquid crystal composition capable of high-speed response even in a liquid crystal display device having a small cell thickness. An object is to provide an object and a liquid crystal display device using the same.

[0009]

The present inventors have proposed a ferroelectric liquid crystal composition containing a chiral compound and a non-chiral compound,
The present invention has been completed by finding that the above object can be achieved by using a component containing two specific non-chiral compounds as the non-chiral compound component.

The present invention provides a ferroelectric liquid crystal composition containing a chiral compound and a non-chiral compound, which is represented by the general formula (A):

[0011]

[Chemical 3]

(Wherein R ¹ and R ² are each independently
It represents a linear or branched alkyl group or alkoxy group having 2 to 16 carbon atoms. However, one or more of non-adjacent methylene groups may be substituted with an oxygen atom) is contained in the non-chiral compound (A) in an amount of 5 to 60% by weight based on the liquid crystal composition, and the general formula ( B):

[0013]

[Chemical 4]

(Wherein R ³ represents a straight-chain or branched alkyl group having 5 to 15 carbon atoms, and R ⁴ represents a straight-chain or branched alkyl group having 9 to 15 carbon atoms). The ferroelectric liquid crystal composition is characterized by containing 5 to 50% by weight of the non-chiral compound (B) based on the liquid crystal composition.

According to another aspect of the present invention, two substrates provided with at least a transparent electrode and an alignment film in this order are arranged so that the alignment films face each other, and a liquid crystal is sealed in a space between the alignment films. in the liquid crystal display device comprising Te, the liquid crystal is a ferroelectric liquid crystal composition of the present invention, the alignment film, the pretilt angle at the S _a phase of the ferroelectric liquid crystal composition be 5 degrees or more The liquid crystal display element is characterized in that an insulating layer having a relative dielectric constant of 5 or more is provided between the transparent electrode of at least one of the substrates and the alignment film.

First, the non-chiral compound (A) represented by the general formula (A) will be described. In the general formula (A), R ¹ and R ² each independently represent a linear or branched alkyl group or alkoxy group having 2 to 16 carbon atoms. Further, ^one or more methylene groups which are not adjacent to the alkyl group or alkoxy group represented by R ¹ or R ² may be substituted with an oxygen atom. Preferred examples of the group represented by R ¹ or R ² include ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, dodecyl, undecyl, 7-methoxyheptyl, 8
-Methoxyoctyl, 10-methoxydecyl, pentyloxy, hexyloxy, heptyloxy, octyloxy, nonyloxy, decyloxy, dodecyloxy,
Undecyloxy, 7-methoxyheptyloxy, 8-
Methoxyoctyloxy, 10-methoxydecyloxy, 7-methyloctyl, 8-methylnonyl, 9-methyldecyl, 7-ethylnonyl, 7-methyloctyloxy, 8-methylnonyloxy and the like can be mentioned.

Preferred compounds among the non-chiral compounds (A) include the following compounds.

1- (5-propyl-2-pyridyl) -4
-(5-Pentyl-2-pyrimidinyl) benzene 1- (5-propyl-2-pyridyl) -4- (5-hexyl-2-pyrimidinyl) benzene 1- (5-propyl-2-pyridyl) -4- ( 5-heptyl-2-pyrimidinyl) benzene 1- (5-propyl-2-pyridyl) -4- (5-octyl-2-pyrimidinyl) benzene 1- (5-propyl-2-pyridyl) -4- (5- Nonyl-2-pyrimidinyl) benzene 1- (5-propyl-2-pyridyl) -4- (5-decyl-2-pyrimidinyl) benzene

1- (5-butyl-2-pyridyl) -4-
(5-Pentyl-2-pyrimidinyl) benzene 1- (5-butyl-2-pyridyl) -4- (5-hexyl-2-pyrimidinyl) benzene 1- (5-butyl-2-pyridyl) -4- (5 -Heptyl-2-pyrimidinyl) benzene 1- (5-butyl-2-pyridyl) -4- (5-octyl-2-pyrimidinyl) benzene 1- (5-butyl-2-pyridyl) -4- (5-nonyl) -2-Pyrimidinyl) benzene 1- (5-butyl-2-pyridyl) -4- (5-decyl-2-pyrimidinyl) benzene

1- (5-pentyl-2-pyridyl) -4
-(5-Pentyl-2-pyrimidinyl) benzene 1- (5-pentyl-2-pyridyl) -4- (5-hexyl-2-pyrimidinyl) benzene 1- (5-pentyl-2-pyridyl) -4- ( 5-heptyl-2-pyrimidinyl) benzene 1- (5-pentyl-2-pyridyl) -4- (5-octyl-2-pyrimidinyl) benzene 1- (5-pentyl-2-pyridyl) -4- (5- Nonyl-2-pyrimidinyl) benzene 1- (5-pentyl-2-pyridyl) -4- (5-decyl-2-pyrimidinyl) benzene

1- (5-hexyl-2-pyridyl) -4
-(5-Pentyl-2-pyrimidinyl) benzene 1- (5-hexyl-2-pyridyl) -4- (5-hexyl-2-pyrimidinyl) benzene 1- (5-hexyl-2-pyridyl) -4- ( 5-heptyl-2-pyrimidinyl) benzene 1- (5-hexyl-2-pyridyl) -4- (5-octyl-2-pyrimidinyl) benzene 1- (5-hexyl-2-pyridyl) -4- (5- Nonyl-2-pyrimidinyl) benzene 1- (5-hexyl-2-pyridyl) -4- (5-decyl-2-pyrimidinyl) benzene

1- (5-heptyl-2-pyridyl) -4
-(5-Pentyl-2-pyrimidinyl) benzene 1- (5-heptyl-2-pyridyl) -4- (5-hexyl-2-pyrimidinyl) benzene 1- (5-heptyl-2-pyridyl) -4- ( 5-heptyl-2-pyrimidinyl) benzene 1- (5-heptyl-2-pyridyl) -4- (5-octyl-2-pyrimidinyl) benzene 1- (5-heptyl-2-pyridyl) -4- (5- Nonyl-2-pyrimidinyl) benzene 1- (5-heptyl-2-pyridyl) -4- (5-decyl-2-pyrimidinyl) benzene

1- (5-octyl-2-pyridyl) -4
-(5-Pentyl-2-pyrimidinyl) benzene 1- (5-octyl-2-pyridyl) -4- (5-hexyl-2-pyrimidinyl) benzene 1- (5-octyl-2-pyridyl) -4- ( 5-heptyl-2-pyrimidinyl) benzene 1- (5-octyl-2-pyridyl) -4- (5-octyl-2-pyrimidinyl) benzene 1- (5-octyl-2-pyridyl) -4- (5- Nonyl-2-pyrimidinyl) benzene 1- (5-octyl-2-pyridyl) -4- (5-decyl-2-pyrimidinyl) benzene

1- (5-nonyl-2-pyridyl) -4-
(5-Pentyl-2-pyrimidinyl) benzene 1- (5
-Nonyl-2-pyridyl) -4- (5-hexyl-2-
Pyrimidinyl) benzene 1- (5-nonyl-2-pyridyl) -4- (5-heptyl-2-pyrimidinyl) benzene 1- (5-nonyl-2-pyridyl) -4- (5-octyl-2-pyrimidinyl) Benzene 1- (5-nonyl-2-pyridyl) -4- (5-nonyl-2-pyrimidinyl) benzene 1- (5-nonyl-2-pyridyl) -4- (5-decyl-2-pyrimidinyl) benzene 1 -(5-nonyl-2-pyridyl) -4- (5-undecyl-2-pyrimidinyl) benzene

1- (5-decyl-2-pyridyl) -4-
(5-heptyl-2-pyrimidinyl) benzene 1- (5-decyl-2-pyridyl) -4- (5-octyl-2-pyrimidinyl) benzene 1- (5-decyl-2-pyridyl) -4- (5 -Nonyl-2-pyrimidinyl) benzene 1- (5-decyl-2-pyridyl) -4- (5-decyl-2-pyrimidinyl) benzene 1- (5-decyl-2-pyridyl) -4- (5-undecyl -2-Pyrimidinyl) benzene

1- [5- (6-methylheptyl) -2-
Pyridyl] -4- (5-hexyl-2-pyrimidinyl)
Benzene 1- (5-heptyl-2-pyridyl) -4- [5- (6
-Methylheptyl) -2-pyrimidinyl] benzene 1- [5- (6-methylheptyl) -2-pyridyl]-
4- [5- (7-methyloctyl) -2-pyrimidinyl] benzene

In the ferroelectric liquid crystal composition of the present invention, the content of the non-chiral compound (A) is 5 to 60% by weight, preferably 5 to 30% by weight of the ferroelectric liquid crystal composition.

Next, the non-chiral compound (B) represented by the general formula (B) will be described. In the general formula (B),
R ³ represents a linear or branched alkyl group having 5 to 15 carbon atoms, R ⁴ represents a linear or branched alkyl group having 9 to 15 carbon atoms. Among the groups represented by R ³ , preferred examples are n-pentyl group, n-hexyl group, n-heptyl group, n-octyl group, n-nonyl group, n-decyl group, n.
-Dodecyl group, 5-methylhexyl group, 6-methylheptyl group, 7-methyloctyl group, 8-methylnonyl group,
Examples thereof include 9-methyldecyl group and 3,7-dimethyloctyl group. In addition, preferred examples of the group represented by R ⁴ include n-nonyl group, n-decyl group and n-
Dodecyl group, n-tridecyl group, 7-methyloctyl group, 8-methylnonyl group, 9-methyldecyl group, 11-
Examples thereof include a methyldodecyl group and a 3,7-dimethyloctyl group. The non-chiral compound (B) can be synthesized by a known synthesis method (for example, Zaschke H., Wiss.Z. Univ. Halle XXIX.
'80M, H-3, 35 (1980)) for reference.

Specific examples of the non-chiral compound (B) include:
The following compounds may be mentioned.

5-nonyl-2- (4-heptylphenyl) pyrimidine, 5-nonyl-2- (4-octylphenyl) pyrimidine, 5-nonyl-2- (4-nonylphenyl) pyrimidine, 5-nonyl-2 -(4-decylphenyl) pyrimidine, 5-nonyl-2- [4- (8-methylnonyl) phenyl] pyrimidine, 5-nonyl-2-
[4- (9-methyldecyl) phenyl] pyrimidine, 5
-Decyl-2- (4-heptylphenyl) pyrimidine,
5-decyl-2- (4-octylphenyl) pyrimidine, 5-decyl-2- (4-nonylphenyl) pyrimidine, 5-decyl-2- (4-decylphenyl) pyrimidine, 5-decyl-2- [4 -(8-methylnonyl) phenyl] pyrimidine, 5-decyl-2- [4- (9-methyldecyl) phenyl] pyrimidine,

5-dodecyl-2- (4-heptylphenyl) pyrimidine, 5-dodecyl-2- (4-octylphenyl) pyrimidine, 5-dodecyl-2- (4-nonylphenyl) pyrimidine, 5-dodecyl-2 -(4-decylphenyl) pyrimidine, 5-dodecyl-2- [4-
(8-Methylnonyl) phenyl] pyrimidine, 5-dodecyl-2- [4- (9-methyldecyl) phenyl] pyrimidine, 5- (8-methylnonyl) -2- (4-heptylphenyl) pyrimidine, 5- (8- Methylnonyl)-
2- (4-octylphenyl) pyrimidine, 5- (8-
Methylnonyl) -2- (4-nonylphenyl) pyrimidine, 5- (8-methylnonyl) -2- (4-decylphenyl) pyrimidine, 5- (8-methylnonyl) -2-
[4- (8-Methylnonyl) phenyl] pyrimidine, 5
-(8-methylnonyl) -2- [4- (9-methyldecyl) phenyl] pyrimidine,

The content of the non-chiral compound (B) in the ferroelectric liquid crystal composition of the present invention is 5 to 50% by weight, preferably 20 to 40% by weight.

The weight ratio of the non-chiral compound (A) to the non-chiral compound (B) in the ferroelectric liquid crystal composition of the present invention is as follows: non-chiral compound (A): non-chiral compound (B) =
It is preferably in the range of 3: 1 to 1: 5, particularly preferably in the range of 2: 1 to 1: 3.

The ferroelectric liquid crystal composition of the present invention may contain a non-chiral compound other than the non-chiral compound (A) and the non-chiral compound (B). Preferred examples of the non-chiral compound other than the non-chiral compound (A) and the non-chiral compound (B) include the following compounds.

5-nonyloxy-2- (4-heptylphenyl) pyrimidine, 5- (8-methylnonyl) -2-
(4-octyloxyphenyl) pyrimidine, 5-nonyl-2- (4-octyloxyphenyl) pyrimidine,
5-dodecyl-2- (4-nonyloxyphenyl) pyrimidine, 5-decyl-2- (4'-nonylbiphenyl-
4-yl) pyrimidine, 5-dodecyl-2- (4'-nonylbiphenyl-4-yl) pyrimidine, 5- (8-methylnonyl) -2- (4'-heptylbiphenyl-4-
Il) pyrimidine,

5-dodecyl-2- (4-heptyloxyphenyl) pyridine, 5-dodecyl-2- (4-octyloxyphenyl) pyridine, 5-dodecyl-2- (4
-Nonyloxyphenyl) pyridine, 5-dodecyl-2
-(3-Fluoro-4-octyloxyphenyl) pyridine, 5- (4-heptyloxyphenyl) -2- (4
-Heptylphenyl) pyridine, 5-decyl-2- (4
-Decanoyloxyphenyl) pyridine, 4-octyloxyphenyl 4-decyloxybenzoate, 4-
Octyloxyphenyl 4-decylbenzoate, 4
-Decyloxyphenyl 4-octyl benzoate.

The chiral compound contained in the ferroelectric liquid crystal composition of the present invention is not particularly limited and may be any chiral compound useful as a component of the liquid crystal composition. Many chiral compounds useful as components of liquid crystal compositions are known, and these compounds can be appropriately used as the chiral compound in the ferroelectric liquid crystal composition of the present invention.

Particularly preferred chiral compounds in the ferroelectric liquid crystal composition of the present invention are 5-octyl-2- [4-((2S) -2-fluorooctyloxy) phenyl] pyrimidine, 5- [(2S) -2-
((2S) -2-Propyloxypropanoyloxy)
Propyloxy] -2- (4-octyloxyphenyl) pyrimidine, 5-[(2S) -2-((2S) -2
-Propyloxypropanoyloxy) propyloxy] -2- (4'-heptylbiphenyl-4-yl) pyrimidine, 5-((2S) -2-methylbutyl) -2-
(4'-heptylbiphenyl-4-yl) pyrimidine,
Etc. can be mentioned.

Next, the liquid crystal display device of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a sectional view schematically showing a main part of an embodiment of the liquid crystal display element of the present invention. In FIG. 1, the liquid crystal display device 1 comprises a transparent electrode 3 provided on a substrate 2, an insulating layer 4 provided on the transparent electrode 3, and an alignment film 5 provided on the insulating layer 4, while a transparent electrode 3 is provided on the substrate 6. Is provided with a transparent electrode 7, an insulating layer 8 is provided thereon, and an alignment film 9 is further provided thereon, and the substrate 2 and the substrate 6 face each other with the alignment film 5 and the alignment film 9 therebetween. A ferroelectric liquid crystal composition (hereinafter, may be simply referred to as liquid crystal) 10 of the present invention is enclosed in the void so as to form a void therein.

In the liquid crystal display element 1, the alignment films 5 and 9 have a specific tilt angle, the insulating layers 4 and 8 have a specific dielectric constant, and the liquid crystal 10 is the ferroelectric liquid crystal composition of the present invention. Other than that, it is the same as the conventionally known liquid crystal display element.

That is, as the substrate 2 and the substrate 6, a glass substrate, a transparent heat-resistant resin substrate or the like can be used.
As the transparent electrodes 3 and 7, an ITO film, a SnO ₂ film, I
An n ₂ O ₃ film or the like can be used.

As the insulating layers 4 and 8, 5 or more,
There is no particular limitation as long as it has a relative permittivity of 8 or more. For example, Ta ₂ O ₅ , Al ₂ O ₃ , Hf
A film formed of O ₂ , Y ₂ O ₃ , Nd ₂ O ₃ , ZrO ₂ , TiO ₂ or the like and having a film thickness of 30 to 300 nm is preferable. Such an insulating layer can be formed by a conventionally known film forming method, for example, a vacuum evaporation method by resistance heating, a vacuum evaporation method by electron beam (EB) heating, a sputtering method, an ion plating method, or the like.
Only one of the insulating layers 4 and 8 may be provided.

Further, as the alignment films 5 and 9, the pretilt angle in the S _A phase of the ferroelectric liquid crystal composition of the present invention to be used (the cells for liquid crystal display elements are assembled in antiparallel and liquid crystal is injected, The alignment film is not particularly limited as long as it is an alignment film having a value of 5 degrees or more, preferably 8 degrees or more, obtained by the crystal rotation method at the temperature indicating the S _A phase, and a rubbing-treated polyimide film, a SiO ₂ oblique vapor deposition film, or the like may be used. Can be used. Such an alignment film can be formed by a method known per se.

For example, a polyimide alignment film having the above-mentioned properties is prepared by dissolving a polyamic acid obtained from a diamine (a) and a tetracarboxylic dianhydride (b) as described below in a solvent. It can be formed by preparing a coating liquid for forming, coating the coating liquid on the insulating layer 4 or 8, drying, heat treatment, and then rubbing treatment.

[0045]

[Chemical 5]

[0046]

[Chemical 6]

The polyimide alignment film generally has a thickness of 5 to 20.
0 nm, particularly preferably 10 to 50 nm, and S
The film thickness of the iO ₂ obliquely vapor-deposited alignment film is generally 5 to 100 nm,
It is particularly preferably 5 to 50 nm.

The thickness (cell gap) of the liquid crystal display element 1 for enclosing the liquid crystal is generally 1 to 6 μm, preferably 1 to 2 μm. In such a thin cell gap liquid crystal display element. However, the liquid crystal display device using the ferroelectric liquid crystal composition of the present invention exhibits extremely excellent high-speed response.

The liquid crystal display device of the present invention may be of a segment type display system or a matrix type display system, and may be of either black and white or color, and as required. Furthermore, a color filter, a black mask, a protective layer, a heater, etc. may be provided.

[0050]

EXAMPLES The present invention will be described below with reference to examples. However, the invention is not limited by the following examples.

Liquid crystal intermediate mixtures 1-5 used in the examples
Have the compositions shown in Tables 1 to 5 below.

[0052]

[Table 1]

[0053]

[Table 2]

[0054]

[Table 3]

[0055]

[Table 4]

[0056]

[Table 5]

[Example 1] Ferroelectric liquid crystal compositions having the compounds shown in Table 6 and their composition ratios were prepared.

[0058]

[Table 6]

The above ferroelectric liquid crystal composition was sandwiched between two glass plates and the phase texture pattern was observed by a polarization microscope. As a result, the phase transition temperature was confirmed as follows.

Next, this liquid crystal composition was subjected to parallel alignment treatment by applying polyimide as an alignment film and rubbing the surface thereof, and a thickness of 2 μm provided with a transparent glass electrode.
It is poured into a cell of m, gradually cooled, and aligned to form a liquid crystal element.
This is sandwiched between two orthogonal polarizing plates, ± 10V, 50
When a rectangular wave of Hz was applied, the time required for the transmitted light intensity to change from 0% to 90% (response time τ) was measured. As a result, τ at 35 ° C. was 78 μsec.

The rotational viscosity coefficient (η) of this liquid crystal at 35 ° C., obtained from the half-width of the polarization reversal current when a rectangular wave was applied, was 141 mPasec. In addition, the spontaneous polarization P obtained from the area of the peak of the polarization reversal current when a triangular wave is applied
s was 13.8 nCcm ^-2 .

Further, the tilt angle θ obtained by examining the movement angle (2θ) of the extinction position when a direct current of 100 V was applied and its polarity was inverted was 22.3 ° at 35 ° C.

Further, after applying a DC voltage of 10 V, the voltage was set to 0 and it was observed whether or not the alignment state upon application was maintained. It was confirmed that the same optical intensity as that at the time of application was obtained even when the voltage was 0, and the alignment state did not change. Therefore,
It was found that the composition of the present invention has excellent bistability (memory property).

The ferroelectric liquid crystal composition of the present invention has a high response speed, a low rotational viscosity coefficient, and excellent bistability. Further, as indicated by N ^* → S _A of the above phase transition temperature,
Since it has both S _A and N ^* phases, and the S _A phase was observed with a polarization microscope, a uniform two-dimensional phase was confirmed,
It was found that the orientation was also excellent.

[Example 2] Ferroelectric liquid crystal compositions having the compounds shown in Table 7 and their composition ratios were prepared.

[0066]

[Table 7]

With respect to the above ferroelectric liquid crystal composition, the phase transition temperature, the response time at 35 ° C., the rotational viscosity coefficient, the spontaneous polarization and the tilt angle were measured in the same manner as in Example 1, and the following values were obtained. Got 90.0-94.0 ° C 84.1-85.1 ° C 55.8 ° C Iso → N ^* → S _A → S _C ^* τ = 54 μs, η = 150 mPas, P
s = 13.1 nCcm ⁻² , θ = 17.1 °

[Example 3] Ferroelectric liquid crystal compositions having the compounds shown in Table 8 and their composition ratios were prepared.

[0069]

[Table 8]

With respect to the above ferroelectric liquid crystal composition, the phase transition temperature, the response time at 35 ° C., the rotational viscosity coefficient, the spontaneous polarization and the tilt angle were measured in the same manner as in Example 1, and the following values were obtained. Got 85.3-90.3 ℃ 81.1 ℃ 64.8 ℃ Iso → N ^* → S _A → S _C ^* τ = 69μs, η = 174mPas, P
s = 16.0 nCcm ⁻² , θ = 21.0 °

[Example 4] Ferroelectric liquid crystal compositions having the compounds shown in Table 9 and their composition ratios were prepared.

[0072]

[Table 9]

With respect to the above ferroelectric liquid crystal composition, the phase transition temperature, the response time at 45 ° C., the rotational viscosity coefficient, the spontaneous polarization and the tilt angle were measured in the same manner as in Example 1, and the following values were obtained. Got 85.5-90.0 ° C 81.5-83.4 ° C 56.5 ° C Iso → N ^* → S _A → S _C ^* τ = 56 μs, η = 143 mPas, P
s = 12.1 nCcm ⁻² , θ = 17.3 °

[Example 5] Ferroelectric liquid crystal compositions having the compounds shown in Table 10 and their composition ratios were prepared.

[0075]

[Table 10]

With respect to the above ferroelectric liquid crystal composition, the phase transition temperature, the response time at 45 ° C., the rotational viscosity coefficient, the spontaneous polarization and the tilt angle were measured in the same manner as in Example 1, and the following values were obtained. Got τ = 63 μs, η = 140 mPas, P
s = 12.7 nCcm ⁻² , θ = 18.7 °

Example 6 Compounds shown in Table 11 and ferroelectric liquid crystal compositions having the composition ratios thereof were prepared.

[0078]

[Table 11]

With respect to the above ferroelectric liquid crystal composition, the phase transition temperature, the response time at 45 ° C., the rotational viscosity coefficient, the spontaneous polarization and the tilt angle were measured in the same manner as in Example 1, and the following values were obtained. Got 78-86.5 ℃ 70.0 ℃ 68.5 ℃ Iso → N ^* → S _A → S _C ^* τ = 78μs, η = 115mPas, P
s = 16.7 nCcm ⁻² , θ = 27.3 °

[Example 7] Glass substrate (thickness: 1.1 m
A transparent electrode of ITO (thickness: 150 nm) was formed on m), and an insulating layer made of Ta ₂ O ₅ (thickness: 100 nm) was formed on the transparent electrode by an electron beam vacuum deposition method. The relative permittivity of this insulating layer was measured by using an LCR meter (Yokogawa Hewlett) on a test piece formed by forming a Ta ₂ O ₅ layer on a copper plate under the same conditions as above and placing another copper plate on this layer. -It was 22 when measured by Packard Co., Ltd.).

On this insulating layer, 10% by weight of N-methyl polyamic acid obtained by dehydration condensation from equimolar amounts of the diamine (a-1) and tetracarboxylic dianhydride (b-1). 20 parts by weight of pyrrolidone solution and diluent for coating liquid (mixture of 20% by weight of N-methylpyrrolidone, 40% by weight of ethylene glycol monobutyl ether and 40% by weight of diethylene glycol monoethyl ether) 80
The coating liquid for alignment film obtained by mixing with 1 part by weight was applied using a spinner, and the coating film was dried at 295 ° C. for 1 hour to form a polyimide alignment film. The surface of the polyimide alignment film was rubbed with a nylon raised cloth.

The two substrates having the transparent electrode, the insulating layer and the alignment film obtained as described above are faced inward so that the rubbing surfaces of the alignment film are antiparallel to each other, The cells were pasted together using an adhesive mixed with a 3 μm spacer to prepare a cell for pretilt angle measurement with a cell gap of 3 μm.

The ferroelectric liquid crystal composition prepared in Example 3 was poured into this cell for measuring pretilt angle, and S at 70 ° C.
_{When the} pretilt angle in phase _A was measured by a crystal rotation method using a polarizing microscope manufactured by Nippon Kogaku Co., Ltd., the pretilt angle was 22 °.

Two substrates, each having the transparent electrode, the insulating layer and the alignment film, obtained as described above were faced to the inside so that the rubbing surfaces of the alignment film were in parallel so that the rubbing directions were parallel to each other. The cells were pasted together using an adhesive mixed with the spacer to prepare a cell for a liquid crystal display device having a cell gap of 1.9 μm.

The ferroelectric liquid crystal composition prepared in Example 3 was injected into the cell for liquid crystal display device and kept at 45 ° C. to obtain the waveform shown in FIG. 2 (where V _S = ± 42 V, τ _S = 1
An electric field of 4 μsec) was applied and the switching state was observed using a polarization microscope. As a result, a clear switching operation with a high contrast ratio was observed.

Example 8 The ferroelectric liquid crystal composition prepared in Example 6 was injected into the liquid crystal display cell prepared in the same manner as in Example 7 and kept at 45 ° C. Figure 2
Waveform (where V _S = ± 42 V, τ _S = 21 μse
When an electric field of c) was applied and the switching state was observed using a polarization microscope, a clear switching operation with a high contrast ratio was observed.

[Embodiment 9] In the same manner as in Embodiment 7, a transparent electrode made of ITO and Ta ₂ O are formed on a glass substrate.
_An insulating layer consisting of ₅ is formed and S is formed on the insulating layer by an oblique evaporation method at an evaporation angle of 83 ° instead of the polyimide alignment film.
An iO ₂ alignment film (film thickness: 25 nm) was formed.

Two substrates, each having the transparent electrode, the insulating layer and the alignment film obtained as described above, were faced to the inside so that the deposition directions of SiO ₂ were anti-parallel, and 3 μm. The pre-tilt angle measuring cell having a cell gap of 3 μm was manufactured by using an adhesive mixed with the spacer of FIG.

The ferroelectric liquid crystal composition prepared in Example 5 was injected into this cell for measuring pretilt angle, and S at 70 ° C.
_{When the} pretilt angle in phase _A was measured by the crystal rotation method using a polarizing microscope manufactured by Nippon Kogaku Co., Ltd., the pretilt angle was 9 °.

Two pieces of the substrate having the transparent electrode, the insulating layer and the alignment film obtained as described above were replaced with SiO 2 as the alignment film.
_The cells for liquid crystal display element having a cell gap of 1.9 μm were prepared by facing inwardly so that the vapor deposition directions of ₂ were parallel to each other and using an adhesive mixed with a spacer of 2 μm.

The ferroelectric liquid crystal composition prepared in Example 5 was injected into the above cell for liquid crystal display device and kept at 45 ° C. to obtain the waveform shown in FIG. 2 (where V _S = ± 42 V, τ _S = 9
An electric field of (μsec) was applied and the switching state was observed using a polarization microscope. As a result, clear switching operation with a high contrast ratio was observed.

[Example 10] The ferroelectric liquid crystal composition prepared in Example 4 was injected into the cell for liquid crystal display device produced in the same manner as in Example 9 and kept at 45 ° C. The waveform shown in FIG. 2 (however, V _S = ± 42 V, τ _S = 10 μs)
When an electric field of ec) was applied and a switching state was observed using a polarization microscope, a clear switching operation with a high contrast ratio was recognized.

[0093]

EFFECT OF THE INVENTION The ferroelectric liquid crystal composition of the present invention has the remarkable effects of being capable of high-speed response and being excellent in orientation, especially in a liquid crystal display device having a small cell thickness.

[Brief description of drawings]

FIG. 1 is a sectional view schematically showing a main part of an embodiment of a liquid crystal display element of the present invention.

FIG. 2 shows a waveform applied to a liquid crystal display element for observing a switching state in Example 7.

[Explanation of symbols]

 1 Liquid crystal display element 2 Substrate 3 Transparent electrode 4 Insulating layer 5 Alignment film 6 Substrate 7 Transparent electrode 8 Insulating layer 9 Alignment film 10 Ferroelectric liquid crystal composition

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kazunori Kamikawa, Fuji Ono-sato, Fujinomiya-shi, Shizuoka 200 Fuji Photo Film Co., Ltd.

Claims (2)

[Claims] 1. A ferroelectric liquid crystal composition comprising a chiral compound and a non-chiral compound, which is represented by the general formula (A): (In the formula, R ¹ and R ² each independently have 2 to 1 carbon atoms.
6 represents a linear or branched alkyl group or alkoxy group. However, one or more of non-adjacent methylene groups may be substituted with an oxygen atom) is contained in the non-chiral compound (A) in an amount of 5 to 60% by weight based on the liquid crystal composition, and the general formula ( B): (Wherein R ³ represents a straight-chain or branched alkyl group having 5 to 15 carbon atoms, and R ⁴ represents a straight-chain or branched alkyl group having 9 to 15 carbon atoms). Compound (B)
5 to 50% by weight based on the liquid crystal composition, a ferroelectric liquid crystal composition. 2. A liquid crystal display in which two substrates having at least a transparent electrode and an alignment film provided in this order are arranged so that the alignment films face each other, and liquid crystal is sealed in a space between the alignment films. in the element, the liquid crystal is ferroelectric liquid crystal composition according to claim 1, the alignment film, and a pretilt angle at S _a phase of the ferroelectric liquid crystal composition 5 degrees or more, A liquid crystal display device comprising an insulating layer having a relative dielectric constant of 5 or more provided between the transparent electrode and the alignment film of at least one of the substrates.