JPH08151579A - Liquid crystal composition and liquid crystal element containing the same - Google Patents

Abstract

PURPOSE: To obtain a non-chiral smectic liquid crystal composition containing a specific quinoxaline compound, etc., a fluorinecontaining compound, exhibiting negative dielectric anisotropy, having smectic C phase (Sc phase) near room temperature and wide Sc phase temperature range and useful for ferroelectric liquid crystal, etc. CONSTITUTION: This nonchiral smectic liquid crystal composition consists essentially of (A1 ) a compound of formula I [R1 is a (halogen substituted)3-20C alkyl, etc.; R2 is a (halogen-substituted) 1-20C alkyl, etc.; A is a single bond, O, etc.; F is halogen; (m) is 0-2] or (A2 ) a compound of formula II [R3 is R1 ; R4 is R2 ; G is F; (n) is (m)] and (B) a compound of formula III [R5 and R6 are each a 1-15C alkyl; X and Y are each a single bond or O; one group of P, Q and R is 2,3-difluoro-1,4-phenylene and other two groups are 1,4-phenylene or 1,4- phenylene and pyrimidin-2,5-diyl) and when the compound contains A1 and B, a ratio of A1 to B is (80-20) to (20-80) and when the compound contains A2 and B, a ratio of A2 to B is (80-20) to (20-80).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel non-chiral smectic liquid crystal composition which can be used in a ferroelectric chiral smectic liquid crystal composition and a liquid crystal device using the same.

[0002]

2. Description of the Related Art With the progress of information society in recent years, various display devices have been used as one of man-machine interfaces.
Its importance is increasing. Among them, flat panel displays, especially liquid crystal displays (LCD),
It has features such as thinness, light weight, low voltage drive, and low power consumption, and has rapidly spread. Among liquid crystal elements represented by a liquid crystal display, a matrix type liquid crystal element having a large amount of information has two driving methods called an active matrix method and a simple matrix method.

In the active matrix system, a thin film transistor or diode such as polysilicon or amorphous silicon is mounted as a non-linear element for each pixel. However, the active matrix method has problems in terms of large area, low price and high density due to complicated manufacturing process and poor yield. Considering price and productivity, the simple matrix method is more preferable. Is influential.

As a simple matrix type liquid crystal element which has been put into practical use at present, a liquid crystal element using TN type / STN type liquid crystal is mainstream. However, the optical response of these liquid crystal elements utilizes the arrangement of average liquid crystal molecule axes in a specific direction based on the dielectric anisotropy of liquid crystal molecules generated when an electric field is applied. Therefore, the limit of the optical response speed of these liquid crystal elements is on the order of milliseconds, which is insufficient considering the increase in the amount of information.

Further, if the number of scanning lines is increased to increase the amount of information, a decrease in contrast ratio and crosstalk cannot be avoided in principle. This is an essential problem due to the fact that TN-type and STN-type liquid crystals do not exhibit a memory property (bistability). In order to improve this, various driving methods such as a dual-frequency driving method, a voltage averaging method, and a multiple matrix method have been proposed, but this is not an essential solution to the problem and it is easy to increase the capacity and density. is not. Further, these liquid crystals have serious problems in view angle restriction and display quality.

With the goal of solving the essential problems of such liquid crystal elements, N.K. A. Clark
And S. T. Lagerwall proposed a liquid crystal device utilizing a liquid crystal having bistability (US Patent No. 4367).
924, JP-A-56-107216, etc.). Ferroelectric liquid crystals exhibiting a chiral smectic C phase are mainly used as liquid crystals exhibiting such bistability.

One of the characteristics of using the ferroelectric liquid crystal is that the ferroelectric liquid crystal exhibits bistability. Bistability means that when a ferroelectric liquid crystal is sandwiched between two glass substrates having transparent electrodes, it has two optically stable states depending on the direction of the applied electric field. The two optically stable states are properties that are maintained even when the applied electric field is removed. Due to such a property, it can be expected that the liquid crystal element using the ferroelectric liquid crystal does not have a decrease in contrast ratio or crosstalk even if the number of scanning lines is increased.

Another characteristic of the ferroelectric liquid crystal is high-speed response. That is, the optical response of the ferroelectric liquid crystal utilizes the change in the alignment of the liquid crystal molecules caused by the direct interaction between the spontaneous polarization of the ferroelectric liquid crystal and the electric field. It is about 1000 times faster than the optical response in the case.

That is, the ferroelectric liquid crystal device exhibits (1) two optically stable states, and the optically stable state is maintained as it is even after the electric field is removed (bistability). It has an essential feature of switching one optical stable state in microsecond order (fast response). Further, the ferroelectric liquid crystal element has the feature that (3) the liquid crystal molecules respond in a plane parallel to the substrate and the cell thickness is thin, so that the viewing angle dependence of the display is small (wide viewing angle). .

Therefore, the ferroelectric liquid crystal device does not require expensive non-linear elements as in the case of the active matrix system, and is expected as a high quality large display capable of achieving a large display capacity and a high display quality by the simple matrix system. There is.

For this reason, enormous research has been conducted and reported so far on liquid crystal materials exhibiting ferroelectricity. However, even if the final composition is a composition containing a liquid crystal exhibiting ferroelectricity, the liquid crystal material exhibiting ferroelectricity in the chiral dopant method accounts for a small proportion of the whole composition, and The physical properties of the non-chiral matrix composition before adding the dielectric liquid crystal are important. In particular, it is important that the smectic C phase (Sc phase) temperature range is wide and the viscosity is low.

Further, in recent years, it has become necessary from the device side to make the dielectric anisotropy negative. However, a compound having a negative dielectric anisotropy has a high lower limit temperature of the smectic C phase, which leaves a problem in practical use.

[0013]

SUMMARY OF THE INVENTION The present invention uses a compound having a negative dielectric anisotropy and a large absolute value, but has a smectic C phase at a temperature closer to room temperature and has a wide smectic C phase temperature range. An object of the present invention is to provide a non-chiral matrix liquid crystal composition having: and a liquid crystal device using the liquid crystal composition.

[0014]

Means for Solving the Problems As a result of intensive investigations by the present inventors, by combining a specific phenylquinoxaline compound and / or a phenylnaphthalene compound with a specific tricyclic compound, smectic compounds near a room temperature region can be obtained. The inventors of the present invention have found that the C phase temperature range can be widened and have reached the present invention.

The present invention comprises the following inventions. [1] Phenylquinoxaline compound represented by the following general formula (I) and / or phenylnaphthalene compound represented by the following general formula (II)

[Chemical 5][In the formula, R₁And R₃Are each independently a halogen atom
An alkyl group having 3 to 20 carbon atoms which may be substituted with
Or represents an alkoxyalkyl group. R₂And R _FourHaso
Carbon, each of which may be independently substituted with a halogen atom
Alkyl group or alkenyl group of number 1 to 20 or
A C2-C20 optionally substituted by a rogen atom
Represents a lucoxyalkyl group. A is a single bond, -O-, -C
OO-, -OCO-, -C≡C- or -CH = CH-
Represents either F and G represent a halogen atom and are
They may be the same or different. Same benzene
When more than one F or G is substituted on the ring, they are
May be the same or different from each other. m and
n represents the integer of 0-2 each independently. ] And one of the following
General formula (III)

[Chemical 6] [In the formula, R ₅ and R ₆ each independently have 1 to 1 carbon atoms.
5 represents an alkyl group. X and Y each independently represent a single bond or -O-. One of P, Q and R is

[Chemical 7] (In the formula, F represents a fluorine atom), and the remaining two are

Embedded image Selected from the combination of. The P, Q and R are arranged in any order. ] When the compound represented by the formula (1) is an essential component and the molar ratio thereof includes the compounds represented by the formula (I) and the formula (III), [the compound represented by the formula (I)] : [Compound represented by the general formula (III)] = (80
To 20): (20 to 80), and when containing the compounds represented by the general formula (II) and the general formula (III), [compound represented by the general formula (II)]: [general formula (II Compound represented by III)] = (20 to 80) :( 80 to 20) The nonchiral smectic liquid crystal composition.

[2] A liquid crystal device comprising the nonchiral smectic liquid crystal composition according to item [1] sandwiched between a pair of electrode substrates.

Next, the present invention will be described in detail. In the liquid crystal compounds represented by the general formulas (I) and (II),
R ₁ and R ₃ are each independently preferably 5 carbon atoms.
~ 12 alkyl groups. R ₂ and R ₄ are each independently preferably an alkyl group having 5 to 12 carbon atoms. A is preferably -O-, and F and G are preferably fluorine atoms. m and n are preferably 2.

The compound represented by the general formula (I) has the following general formula (IV)

[Chemical 9] [Wherein R ₁ has the same definition as in formula (I), S represents a halogen atom or —OSO ₂
CF ₃ - represents a. ] And the following general formula (V)

[0019]

[Chemical 10] A boron compound represented by the formula [in the formula, R ₂ , A, F and m
Is the same as the definition in the general formula (I). ] Can be obtained by reacting in a base in the presence of a metal catalyst. The compound represented by the general formula (II) is described in JP-A-4-5
It can be synthesized by the method described in Japanese Patent No. 04571.

Specific examples of the liquid crystal compounds represented by the general formulas (I) and (II) are shown below. However, it is not limited to these specific examples.

Hereinafter, in the compounds represented by (I-1) to (I-24) and (II-1) to (II-24), R ₁₁ and R ₂₁ are each independently an alkyl group having 3 to 20 carbon atoms. Represents a group or an alkoxyalkyl group having 3 to 20 carbon atoms. R ₁₂ and R ₂₂ each independently represent an alkyl or alkenyl group having 1 to 20 carbon atoms which may be substituted with a halogen atom, or an alkoxyalkyl group having 2 to 20 carbon atoms which may be substituted with a halogen atom. . F represents a fluorine atom.

[0022]

[Chemical 11]

[0023]

[Chemical 12]

[0024]

[Chemical 13]

[0025]

Embedded image

In the liquid crystal compound represented by the general formula (III), R ₅ and R ₆ are each independently an alkyl group having 6 to 12 carbon atoms. X and Y are preferably -O-. The compound represented by the general formula (III) can be synthesized by the method described in JP-A-2-4725.

Specific examples of the liquid crystal compound represented by the general formula (III) include those shown below. However, it is not limited to these specific examples.
Hereinafter, in the compounds represented by (III-1) to (III-60), R ₃₁ and R ₃₁ each independently represent an alkyl group having 1 to 15 carbon atoms. F represents a fluorine atom.

[0028]

[Chemical 15]

[0029]

Embedded image

[0030]

[Chemical 17]

[0031]

Embedded image

[0032]

[Chemical 19]

The liquid crystal element according to the present invention can be used as various types of liquid crystal elements and display devices. Although the structure of the liquid crystal element is not particularly limited, FIG. 1 shows a schematic view of an example of the ferroelectric liquid crystal element. In FIG. 1, 1
Is a polarizing plate, 2 is a glass substrate, 3 is a transparent electrode, 4 is an insulating alignment control film, 5 is a ferroelectric liquid crystal, and 6 is a spacer.

A surface-stabilized ferroelectric liquid crystal display device can be cited as an example of the liquid crystal element having the structure shown in FIG. This display device is a sealed device in which a ferroelectric liquid crystal is horizontally aligned in a cell in which an interval between two glass substrates 2 is extremely thin. The thickness of the ferroelectric liquid crystal layer 5 is determined only by the distance between the two glass substrates 2 and the thickness of the transparent electrode 3 and the insulating alignment film 4 placed on the glass substrates 2 in the direction of the ferroelectric liquid crystal layer 5. Usually 0.5 to 20
μm, preferably 1 to 5 μm.

The transparent electrode 3 is coated on the glass substrate 2 on the liquid crystal layer side, and its material is usually ITO (Indium).
-Tin Oxide), In ₂ O ₃ and SnO ₂ are used.

An insulating alignment film is provided on the liquid crystal layer side 5 of the transparent electrode 3. At this time, when the alignment film has a sufficient insulating property by itself, only the alignment film may be used, but if necessary, an alignment film and an insulating film may be provided under the alignment film,
Both of them may be used as an insulating alignment film.

As the insulating alignment film, organic substances, inorganic substances,
Known ones such as low molecular weight and high molecular weight can be used. As the polymer substance, for example, polyimide, polyamide, polyamideimide, polyvinyl alcohol, polystyrene, polyester, polyesterimide or various photoresists can be used as required.

When these polymer substances are used as the alignment film, the surface of the alignment film is rubbed in one direction with gauze or acetate flock cloth, if necessary.
By performing a so-called rubbing treatment, the alignment of liquid crystal molecules can be further promoted.

As the insulating film, for example, titanium oxide,
Aluminum oxide, zirconium oxide, silicon oxide, silicon nitride, or the like can be used.

As a method of forming these insulating alignment films and insulating films, an optimum method can be used, if necessary, depending on the substances used. For example, in the case of a polymer substance, the polymer substance or its precursor can be applied by a method such as a screen printing method, a spinner coating method, or a dipping method after being dissolved in a solvent capable of dissolving those materials. . In the case of an inorganic substance, a dipping method, a vapor deposition method, an oblique vapor deposition method or the like can be used.

The thickness of these insulating alignment films is not particularly limited, but is 10Å to 20 μm, preferably 20Å to 1000Å. The two glass substrates 3 on which the insulating alignment film 4 and the transparent electrode 3 are installed are held at a predetermined interval via a spacer 6. As the spacer, beads, fibers or film-like insulating material made of silica, alumina or polymer and having a predetermined diameter or thickness can be used. After sandwiching these spacers 6 between two glass substrates 2 and sealing the periphery with, for example, an epoxy adhesive, a ferroelectric liquid crystal can be enclosed.

Usually, one or two polarizing plates 1 are installed outside the two glass substrates. In the guest-host method in which a dichroic dye is added, one polarizing plate is used, and in the birefringence method, two polarizing plates are used. FIG.
Shows a case where two polarizing plates are used. At this time, the two polarizing plates are in a state in which their polarization axes are orthogonal to each other, that is, in a crossed Nicols state. The transparent electrode 3 is
Appropriate lead wires are connected and connected to an external drive circuit.

[0043]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited thereto.

Example 1 Liquid crystal composition A was prepared by mixing the compounds represented by the general formula (I) and the general formula (III) at the ratio (molar ratio) shown in Table 1.
Was prepared.

[0045]

[Table 1]

This liquid crystal composition A was sandwiched between two glass substrates coated with a transparent electrode and a polyimide alignment film so as to have a gap of 2 μm, and the outside of each of the two glass substrates. A liquid crystal element was prepared by installing two polarizing plates with the polarization plane rotated by 90 °. At this time, the polarization axis on the light incident side was set so as to match the rubbing direction of the polyimide alignment film.

Next, using this liquid crystal element, the temperature was raised to a liquid state and then lowered at a rate of 2.5 ° C./min to identify the phase series. Table 2 shows the temperature range and the lower limit temperature of the Sc phase. In Table 2, the values in parentheses indicate the width of the temperature range (difference between the upper limit and the lower limit of the temperature range). The same applies to the tables below.

[0048]

[Table 2] As is clear from the measurement of the Sc phase temperature range shown in Table 2, from compound (I-1) which is a specific example of compound (I) and compound (III-1) which is a specific example of compound (III), By adjusting the liquid crystal composition A, the Sc phase temperature range is broader and closer to room temperature than in the case of using the compound (I) alone.

Example 2 Liquid crystal composition B was prepared by mixing the compounds represented by the general formula (II) and the general formula (III) in the proportions shown in Table 3.

[0050]

[Table 3]

This liquid crystal composition B was sandwiched between two glass substrates coated with a transparent electrode and a polyimide alignment film so as to have a gap of 2 μm, and the outside of each of the two glass substrates. A liquid crystal element was prepared by installing two polarizing plates with the polarization plane rotated by 90 °. At this time, the polarization axis on the light incident side was set so as to match the rubbing direction of the polyimide alignment film.

Next, using this liquid crystal element, the temperature was raised to a liquid state, and then the temperature was lowered at a rate of 2.5 ° C./min to identify the phase series. Table 4 shows the temperature range and the lower limit temperature of the Sc phase.

[0053]

[Table 4]

As is clear from the measurement of the Sc phase temperature range shown in Table 4, compound (II-1) which is a specific example of compound (II) and compound (III-1) which is a specific example of compound (III). By adjusting the liquid crystal composition B consisting of (1)), the Sc phase temperature range is broader and closer to room temperature than in the case of using the compound (II) alone.

[0055]

INDUSTRIAL APPLICABILITY The liquid crystal composition of the present invention has a Sc phase at a temperature closer to room temperature and has a wide Sc phase temperature range while using a compound having a negative dielectric anisotropy and a large absolute value. Is practical.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of an example of a liquid crystal element using a liquid crystal composition.

[Explanation of symbols]

 1. Polarizer 2. Glass substrate 3. Transparent electrode 4. Insulating alignment film 5. Ferroelectric liquid crystal phase 6. spacer

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Naoyuki Takano 4-5-3 Kitahama, Chuo-ku, Osaka City, Osaka Prefecture Sumitomo Chemical Co., Ltd. (72) Inventor Yukari Fujimoto 2-10-1, Tsukahara, Takatsuki City, Osaka Prefecture No. Sumitomo Kagaku Kogyo Co., Ltd. (72) Inventor Masayoshi Minai 2-10-1 Tsukahara, Takatsuki City, Osaka Prefecture Sumitomo Kagaku Kogyo Co., Ltd.

Claims (2)

[Claims] 1. A phenylquino represented by the following general formula (I):
Xaline compound and / or represented by the following general formula (II)
Phenylnaphthalene compound embedded image[In the formula, R₁And R₃Are each independently a halogen atom
An alkyl group having 3 to 20 carbon atoms which may be substituted with
Or represents an alkoxyalkyl group. R₂And R _FourHaso
Carbon, each of which may be independently substituted with a halogen atom
Alkyl group or alkenyl group of number 1 to 20 or
A C2-C20 optionally substituted by a rogen atom
Represents a lucoxyalkyl group. A is a single bond, -O-, -C
OO-, -OCO-, -C≡C- or -CH = CH-
Represents either F and G represent a halogen atom and are
They may be the same or different. Same benzene
When more than one F or G is substituted on the ring, they are
May be the same or different from each other. m and
n represents the integer of 0-2 each independently. ] And one of the following
General formula (III)[In the formula, R_FiveAnd R₆Each independently has 1 to 1 carbon atoms
5 represents an alkyl group. X and Y are each independently a single
Represents a bond or -O-. Any one of P, Q and R
Tsuga(In the formula, F represents a fluorine atom), and the remaining two
IsSelected from the combination of. The order of P, Q and R is random
It is the same. ] The compound represented by
Is represented by the general formula (I) and the general formula (III)
And a compound represented by the formula (I)
Object]: [compound represented by the general formula (III)] = (80
~ 20): (20 to 80), which is the same as the general formula (II).
When the compound represented by the general formula (III) is included, [general
Compound represented by formula (II)]: [in general formula (III)
Compound represented] = (20 to 80): (80 to 20)
A non-chiral smectic liquid crystal composition. 2. A liquid crystal device comprising the nonchiral smectic liquid crystal composition according to claim 1 sandwiched between a pair of electrode substrates.