JP2001123172A - Liquid crystal composition and liquid crystal display element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid crystal composition which has an electric current value controlled without deteriorating various liquid crystal characteristics such as response and has high reliability, and to provide a liquid crystal element which uses the liquid crystal composition and has a high contrast. SOLUTION: This liquid crystal composition containing a compound represented by general formula (I) (R1 is a 1 to 10C alkyl) as the first component and one or more compounds selected from the group consisting of compounds represented by general formulas (II) and (III), concretely compounds represented by general formulas (IV) and (V), and having an N phase upper limit temperature of >=75 deg.C and a Δn of 0.07 to 0.24, and a liquid crystal display element using the liquid crystal composition.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a nematic liquid crystal composition useful as an electro-optical liquid crystal display material, and a liquid crystal display device using the same.

[0002]

2. Description of the Related Art Since liquid crystal displays (LCDs) have appeared as calculator displays, they have progressed from computer development to TN-LCDs (twisted nematic liquid crystal displays) to STN-LCDs. It has responded to the expansion of capacity. STN-L
CDs include Scheffer and others [SID '85 Digest, 120
(1985)] or Kinukawa et al. [SID '86 Digest, 122
Page (1986)], a word processor,
It has begun to spread widely to displays for high information processing such as personal computers. Recently, an active addressing drive method has been proposed for the purpose of improving the response characteristics of an STN-LCD. (Proc. 12th International Display Res
earch Conference p.503 1992)
(Personal Digital Assistance) requires good display characteristics in a wider temperature range. Such a liquid crystal material is required to have a low viscosity, a low driving voltage and a constant value over a wide temperature range, or a driving voltage that does not fluctuate in a frequency range corresponding to various time divisions. I have. However, the response speed and contrast when incorporated into a display element cannot be said to be sufficient, and new liquid crystal compounds or liquid crystal compositions have been proposed at present.

As described above, one of the important characteristics improvement problems of TN-LCD and STN-LCD is improvement of contrast. With the rapid expansion of LCD applications, not only are they used indoors,
Computer mobile terminal display, in-vehicle instrument,
It has been increasingly used outdoors where temperature conditions are severe, such as displays for outdoor use measuring instruments. The decrease in display contrast due to a change in the temperature of the environment in which the LCD is placed has become a problem. In addition, high reliability has been required for outdoor use.

There are various causes for the deterioration of LCD display quality due to a change in ambient temperature. The change is caused by a change in temperature such as an elastic constant and a dielectric constant of a nematic liquid crystal and a change in temperature of an intrinsic pitch of an added chiral substance. Threshold voltage Vth
In order to suppress the temperature change of the chiral substance, a proposal to improve the temperature dependency of the threshold voltage by controlling the temperature change of the specific pitch of the chiral substance (Japanese Patent Laid-Open No. 55-38869) has already been known. Depending on the combination of substances, its effect changes, and by increasing the amount of chiral,
There has been a problem that display characteristics such as response are adversely affected.

However, since the current value increases due to the temperature change of the mobility of the ionic substance contained in the liquid crystal, the effective value voltage applied to the liquid crystal is consumed by the ions, and the contrast and reliability are reduced. No remedy is known. In particular, it is remarkable in a liquid crystal composition containing a large number of compounds having an ester bond in its skeleton, and a liquid crystal composition in which the number of compounds having an ester bond is reduced has been demanded.

[0006] Further, when used in a portable terminal display or the like, the driving voltage is reduced to suppress the power consumption. A low threshold voltage is required for a liquid crystal composition used for such an application. However, when a material for lowering the driving voltage (having a large dielectric anisotropy) is combined, the response is adversely affected. To avoid this effect, the cell thickness of the display element needs to be reduced. When the cell thickness is reduced, it is necessary to combine a material having a large anisotropy of the refractive index in order to make the retardation constant. In other words, the birefringence of the bicyclohexane skeleton
<Phenylcyclohexane skeleton><biphenyl skeleton, and this order is more preferable as a constituent compound of the liquid crystal composition.

[0007]

An object of the present invention is to provide a highly reliable liquid crystal composition in which the current value is suppressed without deteriorating various liquid crystal characteristics such as response and threshold voltage. Another object of the present invention is to provide a high-contrast liquid crystal display device using the liquid crystal composition.

[0008]

Means for Solving the Problems In order to solve the above-mentioned problems, the present invention has examined the liquid crystal compositions using various liquid crystal compounds, and has found the following liquid crystal compositions.

Invention 1 The general formula (I) as the first component

[0010]

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(In the formula, R ¹ represents an alkyl group having 1 to 10 carbon atoms.) The compound contains one or more compounds selected from the group consisting of general formulas (II) and (III) as a second component. )

Embedded image (Wherein, R ² , R ³ , and R ⁴ are each independently an alkyl or alkoxyl group having 1 to 16 carbon atoms, which may be substituted with fluorine, an alkenyl group having 2 to 16 carbon atoms, 3 to 16 alkenyloxy groups, or 1 to 1 carbon atoms
Represents an alkyl group having 1 to 12 carbon atoms substituted with 10 alkoxyl groups, and each of ring A, ring B, ring C, ring D and ring E may be independently substituted with a fluorine atom 1, Four-
Phenylene group, 2-methyl-1,4-phenylene group, 3-methyl-
1,4-phenylene group, naphthalene-2,6-diyl group, phenanthrene-2,7-diyl group, fluorene-2,7-diyl group, trans-1,4-cyclohexylene group, 1,2,3, 4-tetrahydronaphthalene-2,6-diyl group, decahydronaphthalene-2,
6-diyl group, trans-1,3 dioxane-2,5-diyl group,
A pyridine-2,5-diyl group, a pyrimidine-2,5-diyl group, a pyrazine-2,5-diyl group or a pyridazine-2,5-diyl group, l and m are each independently 0, 1 or 2 for Z
¹ , Z ² , Z ³ and Z ⁴ are each independently a single bond, -CH ₂ CH ₂ -,-
_{(CH 2) 4 -, -} OCH 2 -, - CH 2 O- or -C≡C- represents, X ² is a cyano group, a fluorine atom, a chlorine atom, a trifluoromethoxy group, a trifluoromethyl group, difluoromethoxy Group, hydrogen atom, 3,3,3-trifluoroethoxy group, R 'or -OR'
R ′ represents a linear alkyl group having 1 to 12 carbon atoms or a linear alkenyl group having 2 to 12 carbon atoms, and X ¹ and X ³ represent a hydrogen atom, a fluorine atom or a chlorine atom. However, R ⁴ is an alkyl group, X ² is a cyano group, ring D is a 1,4-phenylene group, m
= 0, when Z ⁴ is a single bond, X ¹ and X ³ are not simultaneously fluorine atoms. ) Containing one or two or more compounds selected from the above, furthermore, the maximum temperature of the nematic phase is 75 ° C or more, and the anisotropy of the refractive index (Δn) is in the range of 0.07 to 0.24. Liquid crystal composition.

Invention 2 The content of the compound of the general formula (I) is 5 to 4
Within the range of 0% by mass, the compound represented by the general formula (II) or the general formula (II
The liquid crystal composition according to invention 1, wherein the liquid crystal composition contains one or more compounds selected from the compounds of I), and the content of each of the selected compounds is in the range of 5 to 95% by mass.

Invention 3 As a compound of the general formula (II), ring A and ring B are trans-1,4-cyclohexylene groups,
General formula (II-a) in which Z ¹ and Z ² are single bonds

[0014]

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(Wherein R ⁵ and R ⁶ have the same meanings as R ² and R ³ , ring F represents a 1,4-phenylene group or trans-1,4-cyclohexylene group, and n represents 0 or 1. The liquid crystal composition according to Invention 1 or 2, comprising one or more compounds selected from the group consisting of:

Invention 4 The content of the general formula (I) is in the range of 5 to 40% by mass, and one or more compounds of the general formula (II-a) are contained as the second component. Is 5 to 95% by mass
3. The liquid crystal composition according to Invention 3, wherein

Invention 5 As a compound of the general formula (III), a ring D
Is a trans-1,4-cyclohexylene group, Z ³ and Z ⁴ are a single bond, and m = 1 is a general formula (III-a)

[0018]

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(Wherein R ⁷ represents an alkyl group having 1 to 8 carbon atoms or an alkenyl group having 2 to 8 carbon atoms, and ring G represents 1,4-phenylene group or trans-1,4-cyclohexylene group. X ⁵ represents a cyano group, a fluorine atom, a trifluoromethoxy group or a difluoromethoxy group, and X ⁴ and X ⁶ each independently represent a hydrogen atom or a fluorine atom.) 5. The liquid crystal composition according to any one of inventions 1, 2, 3 and 4, comprising the compound of the formula (1).

Invention 6 When the content of the general formula (I) is in the range of 5 to 40% by mass and one compound of the general formula (III-a)
The liquid crystal composition according to invention 5, wherein the liquid crystal composition contains two or more kinds and has a content of 5 to 95% by mass.

Invention 7 A compound of the formula (I)
Species or more, the content of which is in the range of 5 to 40% by mass, and the general formula (II-b)

[0022]

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Wherein each of R ⁸ and R ⁹ independently represents an alkyl group having 1 to 8 carbon atoms or an alkenyl group having 2 to 8 carbon atoms. In a content of 5 to 40% by mass, further represented by the general formula (II-c)

[0024]

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(In the formula, R ¹⁰ and R ¹¹ each independently represent an alkyl group having 1 to 8 carbon atoms or an alkenyl group having 2 to 8 carbon atoms.) 7. The liquid crystal composition according to any one of Inventions 1 to 6, further comprising a compound having a content of 5 to 60% by mass.

Invention 8 The compound of the general formula (I) described in Invention 1 is
Contains two or more species, the content of which is 5 to 40% by mass
In addition, the compound of the general formula (III-a) contains one or more, and the content is in the range of 5 to 40% by mass, and the general formula (II-b) or the general formula ( II-c) contains one or more compounds, the content of which is 5 to 60
8. The liquid crystal composition according to any one of Inventions 1 to 7, wherein the content is in the range of mass%.

Invention 9 The compound of the general formula (I) according to Invention 1 is
Contains two or more species, the content of which is 5 to 40% by mass
In addition, the compound of the general formula (III-a) contains one or more compounds, and the content thereof is in the range of 5 to 40% by mass, and the general formula (II-b) and the general formula (II-b) II-c)
Contains 1 or more types, each with a content of 5
The liquid crystal composition according to any one of Inventions 1 to 8, wherein the content of the liquid crystal composition is in the range of 4040 mass%.

Invention 10 As the general formula (III) or (III-a) according to the inventions 1 to 9,

[0029]

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Wherein R ¹² represents one or more compounds selected from the group consisting of an alkyl group having 1 to 16 carbon atoms and an alkenyl group having 2 to 8 carbon atoms. Is in the range of 5 to 40% by mass of the invention 1 to 9
The liquid crystal composition according to the above.

Invention 11 As the general formula (III) or (III-a) described in Inventions 1 to 9, the general formula (III-c)

[0032]

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(Wherein R ¹² represents an alkyl group having 1 to 16 carbon atoms or an alkenyl group having 2 to 8 carbon atoms), and contains at least one compound selected from the group consisting of Is in the range of 5 to 40% by mass of the invention 1 to 9
The liquid crystal composition according to the above.

Invention 12 A liquid crystal display device using the liquid crystal composition according to any one of inventions 1 to 11.

Invention 13 A super-twisted nematic (STN) liquid crystal display device using the liquid crystal composition according to any one of inventions 1 to 11 and having a twist angle of 220 ° to 270 °.

[0036]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An example of the present invention will be described below. In the invention 1, one or more compounds selected from the general formula (I) are contained as the first component, and one or two compounds are preferable. In the formula, R ¹ has 2 to 2 carbon atoms.
Represents an alkenyl group of 16 or an alkenyloxy group having 3 to 16 carbon atoms, preferably an alkenyl group having 2 to 16 carbon atoms, more preferably an alkenyl group having 2 to 8 carbon atoms, the following formula (a) ~ The structure of (e) is more preferable,

[0037]

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(It is assumed that the structural formula is connected to the ring at the right end.) Among them, (e) is particularly preferred. Further, the second component contains one or more compounds selected from the general formulas (II) and (III), preferably 3 or more, more preferably 3 to 20 and more preferably 5 to 15 Species are particularly preferred,
More preferably, it contains at least two compounds of the general formula (II). This liquid crystal composition is characterized in that the maximum temperature of the nematic phase is 75 ° C. or higher, preferably 80 ° C. or higher, particularly preferably 85 ° C. or higher. Δn is 0.0
It is characterized by being in the range of 7 to 0.24, but 0.08 to 0.22
Is preferred. R ² , R ³ , and R ⁴ may each independently be fluorine-substituted alkyl or alkoxyl group having 1 to 16 carbon atoms, alkenyl group having 2 to 16 carbon atoms, 3 to 16 carbon atoms An alkenyloxy group, or a C 1-12 carbon atom substituted with a C 1-10 alkoxyl group
Represents an alkyl group, an alkyl group having 1 to 16 carbon atoms, an alkenyl group having 2 to 16 carbon atoms is preferable, an alkyl group having 1 to 8 carbon atoms, an alkenyl group having 2 to 8 carbon atoms is more preferable. Formulas (a) to (e) are particularly preferred as 1 to 5 alkyl groups or alkenyl groups. Ring A, Ring B, Ring
C, ring D and ring E are each independently a 1,4-phenylene group optionally substituted by a fluorine atom, 2-methyl-1,4-
Phenylene group, 3-methyl-1,4-phenylene group, naphthalene-2,6-diyl group, phenanthrene-2,7-diyl group, fluorene-2,7-diyl group, trans-1,4-cyclohexylene group A 1,2,3,4-tetrahydronaphthalene-2,6-diyl group,
Decahydronaphthalene-2,6-diyl group, trans-1,3 dioxane-2,5-diyl group, pyridine-2,5-diyl group, pyrimidine-2,5-diyl group, pyrazine-2,5-diyl Represents a group or a pyridazine-2,5-diyl group, but a 1,4-phenylene group,
Trans-1,4-cyclohexylene group is preferable, and ring A and ring
In B, ring D and ring E, a trans-1,4-cyclohexylene group is more preferable, and in ring C, a 1,4-phenylene group is more preferable. l and m each independently represent 0, 1 or 2, preferably 0 or 1. ^{Z 1, Z 2, Z 3} , Z 4 are each independently a single _{bond, -CH 2 CH 2 -, -} (CH 2) 4 -, - OCH 2 -, - CH 2 O
— Or —C≡C—, but in Z ¹ and Z ² , a single bond or —CH ₂ CH ₂ — is preferable, and a single bond is more preferable. Z ³ , Z ⁴
Is preferably a single bond or -C≡C-, and more preferably a single bond. X ² is a cyano group, a fluorine atom, a chlorine atom,
Represents a trifluoromethoxy group, a trifluoromethyl group, a difluoromethoxy group, a hydrogen atom, a 3,3,3-trifluoroethoxy group, R 'or -OR', and R 'is a straight-chain having 1 to 12 carbon atoms. Represents an alkyl group or a linear alkenyl group of 2 to 12, preferably a cyano group, a fluorine atom, a trifluoromethoxy group, a difluoromethoxy group, a fluorine atom,
A trifluoromethoxy group and a difluoromethoxy group are more preferable, and a fluorine atom is particularly preferable. X ¹ and X ³ represent a hydrogen atom, a fluorine atom or a chlorine atom, preferably a hydrogen atom or a fluorine atom, particularly preferably a fluorine atom.

In the invention 2, the content of the general formula (I) is 5 to 4
0 mass%, preferably 5 to 25 mass%, particularly preferably 5 to 20 mass%, the content of the general formula (II) or general formula (III) is 5 to 95 mass%, 85 mass% is preferred, 25
~ 85% by weight is particularly preferred.

In the invention 4, one or more compounds of the general formula (I) are contained, the content of which is in the range of 5 to 40% by mass, and one compound of the general formula (II-a) is used. Or contains two or more and its content is in the range of 5 to 95% by mass,
One or two compounds of the general formula (I) are contained and the content is preferably 5 to 25% by mass, particularly preferably 5 to 20% by mass,
Contains two or more compounds of the general formula (II-a) and the content is 5 to
It is preferably 95% by mass, more preferably 15 to 85% by mass, and particularly preferably 25 to 85% by mass.

In the invention 6, one or more compounds of the general formula (I) are contained, the content thereof is in the range of 5 to 40% by mass, and the compound of the general formula (III-a) Containing one or more compounds, the content of which is 5 to 95
Although it is in the range of 5% by mass, the compound of the general formula (I) contains one or two kinds, and the content thereof is preferably 5 to 25% by mass, and 5 to 15% by mass.
Mass% is particularly preferred, the content of two or more compounds of the general formula (III-a) is preferably 5 to 95% by mass, more preferably 15 to 85% by mass, and 25 to 85% by mass. Particularly preferred.

In the invention 7, one or more compounds of the general formula (I) are contained, the content of which is in the range of 5 to 40% by mass and which is selected from the general formula (II-b). Contains 5 or more kinds of compounds, the content of which is 5 to 40% by mass
Is preferably in the range of 5 to 25% by mass.
It contains one or more compounds selected from Ic) and the content is in the range of 5 to 60% by mass, preferably 5 to 50% by mass, more preferably 5 to 40% by mass. In the formula
R ⁸ , R ⁹ , R ¹⁰ , and R ¹¹ each independently represent an alkyl group having 1 to 8 carbon atoms or an alkenyl group having 2 to 8 carbon atoms.
(a) to (e) are particularly preferred.

In the invention 8, one or more compounds of the general formula (I) according to the invention 1 are contained, and the content thereof is 5%.
In the range of 40% by mass and the compound of the general formula (III-a)
Contains one or two or more, and its content is 5 to 40% by mass.
And within the general formula (II-b) or (II-c)
Contains one or more compounds, and the content is
Although it is in the range of 5 to 60% by mass, it is preferable that the content of the compound of the general formula (I) is one or two and the content thereof is in the range of 5 to 20% by mass, and the general formula (III-a) Content of 5-35% by mass
Is preferably in the range of 5 to 25% by mass, and the general formula (II-b) or the general formula (II-
Preferably, the content of c) is in the range of 5 to 55% by mass,
More preferably, it is in the range of 5 to 45% by mass.

In the ninth aspect, the compound of the general formula (I) according to the first aspect contains one or more compounds, and the content thereof is 5%.
In the range of 40% by mass and the compound of the general formula (III-a)
Contains one or two or more, and its content is 5 to 40% by mass.
Contains one or more compounds of the general formula (II-b) and the general formula (II-c), and the content thereof is in the range of 5 to 40% by mass, respectively. Compound of formula (I)
It is preferable that the content is in the range of 5 to 20% by mass containing one or two kinds, and contains at least one compound of the general formula (II-b) and the compound of the general formula (II-c), respectively. Is 5 to 20 mass
%, And preferably contains two or more compounds of the general formula (III-a) and the content thereof is in the range of 5 to 25% by mass.

In the invention 10, the general formula (III) described in the invention 1
Or, as the general formula (III-a), contains one or more compounds selected from the general formula (III-b) and the content thereof is
In the range of 5 to 40% by mass, the compound of the general formula (III-b)
It is preferable that it contains 10 to 10 kinds and the content thereof is in the range of 5 to 35% by mass, and it is more preferable that it contains 1 to 5 kinds and the content thereof is in the range of 5 to 30% by mass. Wherein R ¹² has 1 carbon atom
Represents an alkyl group having from 8 to 8 or an alkenyl group having from 2 to 8 carbon atoms, and formulas (a) to (e) are particularly preferable as the alkyl group or alkenyl group having from 1 to 5 carbon atoms.

In the invention 11, the general formula (III) described in the invention 1
Or, as the general formula (III-a), contains one or more compounds selected from the general formula (III-c) and the content thereof is
In the range of 5 to 40% by mass, the compound of the general formula (III-c)
It is preferable that it contains 10 to 10 kinds and the content thereof is in the range of 5 to 35% by mass, and it is more preferable that it contains 1 to 5 kinds and the content thereof is in the range of 5 to 30% by mass. Wherein R ¹² has 1 carbon atom
Represents an alkyl group having from 8 to 8 or an alkenyl group having from 2 to 8 carbon atoms, and formulas (a) to (e) are particularly preferable as the alkyl group or alkenyl group having from 1 to 5 carbon atoms.

The above nematic liquid crystal composition is TN-LCD or STN-
Useful for LCDs, but especially useful for STN-LCDs. Further, it can be used for a transmissive or reflective liquid crystal display device. The liquid crystal composition of the present invention may contain a normal nematic liquid crystal, a smectic liquid crystal, a cholesteric liquid crystal, and the like, in addition to the compounds represented by the general formulas (I) to (III-c).

[0048]

EXAMPLES The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples. Further, “%” in the compositions of the following Examples and Comparative Examples means “% by mass”.

The characteristics measured in the examples are as follows. _TNI : Nematic phase-isotropic liquid phase transition temperature (° C) T _{→ N} : Solid phase or smectic phase-nematic phase transition temperature (° C) Vth: Threshold value when a TN-LCD with a cell thickness of 6 μm is constructed Voltage (V) Δε: Dielectric anisotropy Δn: Birefringence η: Viscosity at 20 ° C. (mPa · s) Ir: Vacuum injection of liquid crystal composition into 240 ° twist STN-LCD, 80 ° C., 100 hours Current value after heating (μA / cm ² ) CR: Contrast when liquid crystal composition is vacuum-injected into 240 ° twisted STN-LCD and driven with 1/200 duty, 1/16 bias drive waveform.

The preparation of the STN-LCD display element was performed as follows. Chiral substance "S-811" in nematic liquid crystal composition
(Merck) was added to prepare a mixed liquid crystal, and an STN with a twist angle of 240 degrees was formed by rubbing an organic film of `` Sun Ever 610 '' (manufactured by Nissan Chemical Industries) on the opposing flat transparent electrode. -Injected into LCD display cells. The chiral substance has a specific helical pitch P of the mixed liquid crystal due to the addition of the chiral substance and a cell thickness d of the display cell, Δn · d = 0.85, d / P = 0.50.
Was added so that

The following abbreviations are used for describing the compounds. Terminal n (number) C _n H _{2n + 1} -C trans-1,4-cyclohexylene C / 1,4-cyclohexenediyl P 1,4 phenylene Pm pyrimidine-2,5-diyl E -COO -e -OCO- A -CH ₂ CH ₂ -t -C≡C- CN -C≡N On -OC _n H _{2n + 1} F -F f F atom bound to ortho position of terminal group ndm- C _n H _{2n + 1} -C = C- (CH ₂ ) _m-1 --O (dm) n -O (CH ₂ ) _m-2 -C = CC _n H _{2n + 1} (Example 1, Comparative Example 1) Nematic Liquid crystal composition No. 1

[0052]

Embedded image

Table 1 shows the results of measuring the properties of this composition together with Comparative Example 1.

[0054]

[Table 1]

As shown in Table 1, the liquid crystal composition of Example 1 significantly reduced the current value and improved the contrast as compared with the composition of Comparative Example 1. Made here
Using STN-LCD, a liquid crystal display device having excellent display characteristics was able to be manufactured. (Example 2, Comparative Example 2) Nematic liquid crystal composition No. 2 was prepared.
Example 2 Various properties were measured, and composition and characteristic data of a composition other than the present invention as a comparative composition (Comparative Example
The results are shown in Table 2 together with 2).

[0056]

[Table 2]

As shown in Table 2, the liquid crystal composition of Example 2 also significantly suppressed the current value as compared with the composition of Comparative Example 2,
The contrast has also improved. STN-LCD fabricated here
By using this, a liquid crystal display device exhibiting excellent display characteristics could be produced.

[0058]

By the combination of the liquid crystal materials of the present invention, a liquid crystal composition having a suppressed current value and a high dielectric anisotropy was obtained. When this composition was used for a liquid crystal display device, the contrast and reliability were high and excellent. This liquid crystal display is very practical as STN and TN-LCD.

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Haruyoshi Takatsu 3-6-27 Nakahara, Higashiyamato-shi, Tokyo F-term (reference) 4H027 BA01 BB03 BB04 BD05 BD08 BD09 BD20 BD24 BE04 BE05 CB01 CC04 CD04 CM04 CN01 CT02 CT04 CW02

Claims (13)

[Claims] 1. A compound represented by the general formula (I) as a first component: (Wherein, R ¹ represents an alkyl group having 1 to 10 carbon atoms.) The compound contains one or more compounds selected from the group consisting of general formulas (II) and (III) 2] (Wherein, R ² , R ³ , and R ⁴ are each independently an alkyl or alkoxyl group having 1 to 16 carbon atoms, which may be substituted with fluorine, an alkenyl group having 2 to 16 carbon atoms, 3 to 16 alkenyloxy groups, or 1 to 1 carbon atoms
Represents an alkyl group having 1 to 12 carbon atoms substituted with 10 alkoxyl groups, and each of ring A, ring B, ring C, ring D and ring E may be independently substituted with a fluorine atom 1, Four-
Phenylene group, 2-methyl-1,4-phenylene group, 3-methyl-
1,4-phenylene group, naphthalene-2,6-diyl group, phenanthrene-2,7-diyl group, fluorene-2,7-diyl group, trans-1,4-cyclohexylene group, 1,2,3, 4-tetrahydronaphthalene-2,6-diyl group, decahydronaphthalene-2,
6-diyl group, trans-1,3 dioxane-2,5-diyl group,
A pyridine-2,5-diyl group, a pyrimidine-2,5-diyl group, a pyrazine-2,5-diyl group or a pyridazine-2,5-diyl group, l and m are each independently 0, 1 or 2 for Z
¹ , Z ² , Z ³ and Z ⁴ are each independently a single bond, -CH ₂ CH ₂ -,-
_{(CH 2) 4 -, -} OCH 2 -, - CH 2 O- or -C≡C- represents, X ² is a cyano group, a fluorine atom, a chlorine atom, a trifluoromethoxy group, a trifluoromethyl group, difluoromethoxy Group, hydrogen atom, 3,3,3-trifluoroethoxy group, R 'or -OR'
R ′ represents a linear alkyl group having 1 to 12 carbon atoms or a linear alkenyl group having 2 to 12 carbon atoms, and X ¹ and X ³ represent a hydrogen atom, a fluorine atom or a chlorine atom. However, R ⁴ is an alkyl group, X ² is a cyano group, ring D is a 1,4-phenylene group, m
= 0, when Z ⁴ is a single bond, X ¹ and X ³ are not simultaneously fluorine atoms. ) Containing one or two or more compounds selected from the above, furthermore, the maximum temperature of the nematic phase is 75 ° C or more, and the anisotropy of the refractive index (Δn) is in the range of 0.07 to 0.24. Liquid crystal composition. 2. The compound of the general formula (I) has a content of 5 to 40% by mass.
%, Further contains one or more selected from compounds of the general formula (II) or the general formula (III), the content of the selected compound is in the range of 5 to 95% by mass, respectively. 2. The liquid crystal composition according to claim 1, wherein: 3. The compound of the general formula (II) wherein Ring A and Ring B are trans-1,4-cyclohexylene groups, Z ¹ , Z ²
Is a single bond of the general formula (II-a) (Wherein R ⁵ and R ⁶ represent the same meaning as R ² and R ³ , ring F represents a 1,4-phenylene group or trans-1,4-cyclohexylene group, and n represents 0 or 1. ), Comprising one or more compounds selected from the group consisting of:
Or the liquid crystal composition according to 2. 4. A compound of the general formula (II-a) as a second component having a content of the general formula (I) in the range of 5 to 40% by mass.
4. The liquid crystal composition according to claim 3, wherein the liquid crystal composition contains at least one species and has a content of 5 to 95% by mass. 5. A compound of the general formula (III-a) wherein ring D is a trans-1,4-cyclohexylene group, Z ³ and Z ⁴ are single bonds, and m = 1. ) (Wherein, R ⁷ is an alkyl group having 1 to 8 carbon atoms or 2 to 8
X represents a 1,4-phenylene group or trans-1,4-cyclohexylene group, X ⁵ represents a cyano group, a fluorine atom, a trifluoromethoxy group, a difluoromethoxy group, and X ⁴ , X ⁶ each independently represent a hydrogen atom or a fluorine atom. One or two selected from)
Claim 1, characterized in that it contains more than one compound
5. The liquid crystal composition according to 2, 3 or 4. 6. The content of the general formula (I) is in the range of 5 to 40% by mass, and one or more compounds of the general formula (III-a) are contained, and the content is 5 to 40% by mass. 6. The liquid crystal composition according to claim 5, wherein the content is in a range of 95% by mass. 7. A compound of the formula (I) containing at least one compound of formula (I), the content of which is in the range of 5 to 40% by mass, and of the formula (II-b) (In the formula, R ⁸ and R ⁹ each independently represent an alkyl group having 1 to 8 carbon atoms or an alkenyl group having 2 to 8 carbon atoms.)
One or two or more compounds selected from the group consisting of a compound represented by the general formula (II-c): (Wherein, R ¹⁰ and R ¹¹ each independently represent an alkyl group having 1 to 8 carbon atoms or an alkenyl group having 2 to 8 carbon atoms.) 7. The liquid crystal composition according to claim 1, wherein the content is in the range of 5 to 60% by mass. 8. A compound of the general formula (III-a) containing at least one compound of the general formula (I) according to claim 1 having a content of 5 to 40% by mass. One compound or
Contains two or more, the content is in the range of 5 to 40 mass%,
And a compound of the general formula (II-b) or (II-c)
Contains one or two or more, and its content is 5 to 60% by mass.
The liquid crystal composition according to any one of claims 1 to 7, wherein 9. A compound of the general formula (III-a) containing at least one compound of the general formula (I) according to claim 1 and having a content of 5 to 40% by mass. One compound or
Contains two or more, the content is in the range of 5 to 40 mass%,
In addition, the compound of the general formula (II-b) and the general formula (II-c) contains one or more, and the content thereof is 5 to 40, respectively.
9. The liquid crystal composition according to claim 1, wherein the content is in the range of mass%. 10. A compound represented by the general formula (III-b) represented by the general formula (III) or (III-a) according to claim 1: (In the formula, R ¹² represents an alkyl group having 1 to 16 carbon atoms or an alkenyl group having 2 to 8 carbon atoms.) The liquid crystal composition according to any one of claims 1 to 9, wherein the content is in a range of from about 40% by mass to about 40% by mass. 11. The compound represented by the general formula (III-c) according to claim 1, wherein the compound is represented by the general formula (III) or (III-a): (In the formula, R ¹² represents an alkyl group having 1 to 16 carbon atoms or an alkenyl group having 2 to 8 carbon atoms.) The compound contains one or more compounds selected from the group having a content of 5 to 40 mass
%. The liquid crystal composition according to claim 1, wherein 12. A liquid crystal display device using the liquid crystal composition according to claim 1. 13. A super twisted nematic (STN) liquid crystal display device using the liquid crystal composition according to claim 1 and having a twist angle of 220 ° to 270 °.