JPH0959623A - Nematic liquid crystal composition and liquid crystal display using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a nematic liquid crystal composition excellent in visual angle characteristics and useful as an electrooptical display material by incorporating a combination of a plurality of compounds having different constants of dielectric anisotropy in a liquid crystal composition comprising a specified liquid crystal compound. SOLUTION: This nematic liquid crystal composition comprises a liquid crystal compound having a nematic-isotropic liquid transition temperature TN-1 of 75 deg.C or above and a crystalline- or smectic-nematic transition temperature T→N of -10 deg.C, freed from a nitrogen atom and an ester group and containing 40-85wt.% 1st component containing three or more compounds having constants of dielectric anisotropy of -2 to +2 and 15-60wt.% 2nd component containing two or more compounds having a constant of dielectric anisotropy of +7 or above. The 2nd component is desirably contains 15-50wt.% compounds having constants of dielectric anisotropy of +10 or above.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a nematic liquid crystal composition useful as an electro-optical display material and a liquid crystal display using the same.

[0002]

2. Description of the Related Art A typical liquid crystal display element is a TN-LCD.
(Twisted nematic liquid crystal display element)
It is used in watches, calculators, electronic organizers, pocket computers, word processors, personal computers and the like. On the other hand, the amount of information displayed on one screen is increasing with the increase in processing information of OA devices.
ffer) et al. [SID '85 Digest, p. 120 (1985)] or Kinugawa et al. [SID '86 Digest, p. 122 (1986)]
STN-LCD (Super Twisted Nematic Liquid Crystal Display Device) has been developed and is beginning to be widely used in displays for high information processing such as word processors and personal computers.

Further, because of its excellent display quality, an active matrix type liquid crystal display device has been put on the market as an effective one for application fields of displays such as liquid crystal televisions, projector displays and computers. The active matrix display method uses a TFT for each pixel
A switching element such as (thin film transistor) or MIM (metal insulator metal) is used, and it is important in this method that leakage current is small, that is, high voltage holding ratio. (Hereinafter, these active matrix liquid crystal display elements are collectively referred to as TFT-LCD.)

Therefore, in order to deal with such a display device, a new liquid crystal compound or liquid crystal composition is still used, for example, Japanese Patent Laid-Open No. 6-31249, JP-A-5-5017.
No. 35, etc. have been proposed.

[0005]

The TN-LCD and STN-LCD have problems such as chemical stability of liquid crystal materials, operating temperature of liquid crystal display devices and display characteristics.

For example, a high time division number TN-LCD or STN-LCD is used as various displays and has a wide operating temperature.
It is also required that the birefringence index Δn be small and that the response speed be fast for good viewing angle characteristics. However, a liquid crystal material having a wide operating temperature makes it difficult to obtain a good liquid crystal material due to an increase in birefringence Δn and response speed. In addition, when used in an STN-LCD that uses a backlight for the purpose of compensating for dark image quality, chemical stability such as heat resistance and light resistance is newly required.

In addition to these required characteristics, particularly in the active matrix system, it is important to have a small leakage current and a high voltage holding ratio in order to obtain a uniform and high contrast. In order to obtain such characteristics,
For example, the following general formula (a-1)

[0008]

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A compound of the formula (wherein R represents an alkyl group) has been used. However, even if these compounds are used, in order to maintain the nematic liquid crystallinity in a wide temperature range, particularly at a low temperature, the compounds represented by the general formulas (a-2) and (a-3) are further added.

[0010]

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At present, a compound of the formula (wherein R represents an alkyl group) is used in combination.

In addition, in order to obtain a uniform and high-contrast liquid crystal display characteristic, the product of the thickness (d) of the liquid crystal layer of the liquid crystal panel and the birefringence (Δn) of the liquid crystal material (Δn ·
d) is 0.35 to 0.6 (hereinafter, this is referred to as the first minimum), 0.70 to 1.4 (hereinafter, this is referred to as the second minimum), or 1.
It is said that it is preferable to set it to 50 to 2.2 (hereinafter, this is referred to as a third minimum). The thickness (d) used in the current liquid crystal panel manufacturing process is about 4.5.
Since it is more than μm, the birefringence of the liquid crystal material (Δn)
Is required to be 0.07 to 0.10, 0.12 to 0.14, or 0.15 or more. However, a liquid crystal material having a smaller or larger birefringence tends to have a smectic phase or a glass state at a low temperature, which causes a new problem of maintaining nematic liquid crystallinity.

The problem to be solved by the present invention is to solve the above-mentioned problems, having stable nematic liquid crystallinity at low temperature, and having a birefringence Δn according to the purpose.
Moreover, it is to provide a liquid crystal composition having a sufficiently fast response speed and a high voltage holding ratio, and to provide a liquid crystal display device using the liquid crystal composition.

[0014]

In order to solve the above problems, the present invention is a liquid crystal composition comprising a liquid crystal compound having no nitrogen atom and no ester group, wherein the dielectric anisotropy is -2.
~ The first component containing at least three kinds of +2 compounds is 4
Contains 0 to 85% by weight and has a dielectric anisotropy of +7 or more of +7
The second component containing at least two kinds of the above compounds is used as 15
Content of ˜60% by weight, a nematic phase-isotropic liquid phase transition temperature T _NI is 75 ° C. or higher, and a crystalline phase or a smectic phase-nematic phase transition temperature T → _N is −10 ° C. or lower. A nematic liquid crystal composition is provided.

The liquid crystal composition of the present invention is characterized by comprising a liquid crystal compound having neither a nitrogen atom nor an ester group. Representative compounds having a nitrogen atom include a compound having a cyano group and a compound having a pyrimidine ring, which are excellent in reduction of threshold voltage and compatibility.
The compound having an ester group is useful for obtaining a broad nematic phase. The present invention is to find a liquid crystal composition having the same or improved characteristics as those of the compounds without using these compounds.

The liquid crystal composition of the present invention comprises, as the first component,
A liquid crystal compound having a dielectric anisotropy of −2 to +2 of at least 3 is used.
Or more, and the total amount thereof is in the range of 40 to 85% by weight. As the second component, at least two liquid crystal compounds having a dielectric anisotropy of +7 or more are contained, and the total amount is 15 to 85% by weight.
By constituting in the range of 60% by weight, -10 ℃ ~
Fast response characteristics can be obtained despite the temperature range of the nematic phase wider than + 75 ° C, and it is extremely stable against light, heat, oxygen, moisture, sealing agents, sealing agents, alignment films, etc., and has a high voltage holding ratio. The required liquid crystal display device can be provided.

Among them, it is preferable that the second component contains a compound having a dielectric constant anisotropy of +10 or more in the range of 15 to 50% by weight, and a compound having a dielectric constant anisotropy of +13 or more is 15 to 50% by weight. It is more preferable to contain it in the range of 30% by weight. The first component in this case is 45 to 75% by weight.
Is preferable, and a range of 50 to 70% by weight is more preferable.

The following compounds are preferably used in the above liquid crystal composition. As the liquid crystal compound of the first component, (1) general formulas (I-1) to (I-3)

[0019]

[Chemical 6]

(In the formula, Z ¹¹ , Z ¹² , Z ¹³ and Z ¹⁴ each independently represent -C ₂ H ₄ -or a single bond, and Z ¹⁵ represents-.
C≡C- or a single bond, and R ¹¹ , R ¹² and R ¹³ are each independently a straight chain alkyl group having 2 to 5 carbon atoms,
Represents an alkoxy group, an alkoxyalkyl group, an alkenyl group or an alkenyloxy group, wherein R ¹⁴ , R ¹⁵ and R ¹⁶ are each independently a linear alkyl group having 1 to 10 carbon atoms, an alkoxy group, an alkoxyalkyl group or an alkenyl. A group or an alkenyloxy group, Y ¹¹ , Y ¹² and Y
¹³ are each independently a hydrogen atom, a fluorine atom or -CH
Represents ₃ , and k, l and m are each independently 0 or 1
And the ring A ¹¹ and the ring A ¹² each independently represent a trans-1,4-cyclohexylene group or a 1,4-cyclohexenylene group, and 1,4 in each compound
The hydrogen atom (H) of the -cyclohexylene group may be replaced by a deuterium atom (D). ) A compound selected from the first group consisting of compounds represented by the formula (1) is preferable, and as the liquid crystal compound of the second component, (2) the general formulas (II-1) to (II-3)

[0021]

[Chemical 7]

(In the formula, Z ²¹ and Z ²³ each independently represent a single bond, —C ₂ H ₄ — or —C ₄ H ₈ —, and Z ²² represents —C ₂ H ₄ —.
C ₂ H ₄ — or —C ₄ H ₈ —, Z ²⁴ is a single bond or —
Represents C≡C-, each R ^21, R ²² and R ²³ independently linear alkyl group having 2 to 10 carbon atoms, an alkoxy group, an alkoxyalkyl group, an alkenyl group or an alkenyloxy group, X ²¹ , X ^22, and X ²³ are each independently a fluorine atom, a chlorine atom, —OCF ₃ , or —OCH.
F ₂ or —CF ₃ , Y ²¹ , Y ²² and Y ²³ each independently represent a hydrogen atom or a fluorine atom, and p and q
Each independently represent an integer of 0 or 1, and the hydrogen atom (H) of the 1,4-cyclohexylene group in each compound
May be substituted with a deuterium atom (D). Compounds selected from the second group consisting of compounds represented by

Furthermore, in addition to the first and second components,
(3) General formulas (III-1) to (III-4)

[0024]

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[0025] ^{(wherein, Z 31, Z 32, Z} 33 and Z ³⁵ are each independently a single bond, -C ₂ H ₄ - or -C ₄ H ₈ - represents, Z ³⁴ is a single bond, -C ₂ H ₄ −, −C ₄ H ₈ − or −C≡
C- represents R ³¹ , R ³² , R ³³ , R ³⁴ and R ³⁵ each independently represents a linear alkyl group or alkenyl group having 1 to 5 carbon atoms, and X ³¹ , X ³² and X ³³ each independently a linear alkyl group having 1 to 5 carbon atoms include a fluorine atom, a chlorine atom, -OCF _3, -OCHF ₂ or -CF ₃
Represents Y ³¹ , Y ³² , Y ³³ , Y ³⁴ , Y ³⁵ , Y ³⁶ ,
Y ³⁷ , Y ³⁸ and Y ³⁹ each independently represent a hydrogen atom or a fluorine atom, and r represents an integer of 0, 1 or 2,
The hydrogen atom (H) of the 1,4-cyclohexylene group in each compound may be replaced with a deuterium atom (D). It is preferable to use a compound selected from the third group consisting of the compounds represented by

The liquid crystal composition of the present invention thus obtained is useful for use in an active matrix liquid crystal display device or a twisted nematic or super twisted nematic liquid crystal display device, and has a wide temperature range. It is possible to provide a liquid crystal display device having a smaller change in driving voltage with temperature and a faster response speed at low temperatures.

The dielectric anisotropy Δε of each liquid crystal compound
Mixes the compound to be measured with the liquid crystal material below and injects it into a parallel plate panel, and the electronic machinery industry standard (EIAJED-2
521page29), using the AC bridge method (4192A manufactured by Hewlett-Packard Co.), the sine wave of 1 KHz, the applied voltage of 0.5 V, and the measurement temperature of 20 ° C., the dielectric constant ε∥ of the molecular long axis direction of the mixture and the molecular simple The dielectric constant in the axial direction ε⊥ was measured, the dielectric anisotropy Δε was obtained from the definition of Δε = ε‖−ε⊥, and extrapolation was performed from these values.

[0028]

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(1) General formulas (I-1) to (I
The compound of the first group consisting of the compound represented by the formula (3) is preferably selected from the group of compounds represented by the following general formulas (I-4) to (I-13).

[0030]

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(In the formula, R ¹¹ , R ¹² , R ¹³ , R ¹⁴ , R ¹⁵ and R ¹⁶ have the same meanings as in formulas (I-1) to (I-3).)

No. (1-
The compounds 1) to (1-21), their phase transition temperatures and dielectric anisotropy Δε are shown in Table 1 below. In addition, each liquid crystal compound,
Impurities were removed by a method such as distillation, column purification, and recrystallization, and a sufficiently purified product was used.

[0033]

[Table 1]

(In the table, C is a crystalline phase, S is a smectic phase, N is a nematic phase, and I is an isotropic liquid phase.)

Preferred compounds in the first group are those in which the side chain groups R ^{11 to} R ¹³ are an alkyl group or an alkenyl group, and the side chain group R ^{14 is}
To R ¹⁶ are alkyl groups, alkoxy groups, alkenyl groups or alkenyloxy groups. In this case, it is preferable that the number of carbon atoms is smaller, and the side chain group R ¹¹ to R
The total number of carbon atoms of R ¹³ and the side chain groups R ^{14 to} R ¹⁶ is preferably 4 to 8. More preferably, the side chain groups R ^{11 to} R ¹³ contain at least one compound having an alkenyl group. In this case, CH ₂ = CH- or CH ₂ = CH-CH ₂ -
CH ₂ - is particularly preferred. By doing so, it has been found that a wider nematic phase can be obtained by combining the second component, especially the compound selected from the second group of the present invention. To make the birefringence relatively small, general formula (I-1)
Alternatively, (I-2) may be used, and more specifically, the compound represented by the general formula (I-
4) to (I-9) are preferable. In order to make the birefringence relatively large, the general formula (I-3) may be used, and more specifically, the general formulas (I-10) to (I-13) are preferable. It is preferable to use these in combination for the medium birefringence. In any of these cases, the number of components of 3 to 15 types can be used as the first component, but the number of components of 3 to 10 types is preferable and 3 to
Seven types of components are more preferable.

(2) General formula (II-1) to
The compound selected from the second group consisting of the compound represented by (II-3) is preferably selected from the compound group represented by the following general formulas (II-4) to (II-13).

[0037]

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(In the formula, R ²¹ , R ²² and R ²³ are represented by the general formula (II
-1) to (II-3) have the same meanings. )

No. (2-
The compounds 1) to (2-13), their phase transition temperatures, and the dielectric anisotropy Δε are shown in Table 2 below. In addition, each liquid crystal compound,
Impurities were removed by a method such as distillation, column purification, and recrystallization, and a sufficiently purified product was used.

[0040]

[Table 2]

(In the table, C is a crystalline phase, S is a smectic phase, N is a nematic phase, and I is an isotropic liquid phase.)

Preferred compounds in the second group are those in which the side chain groups R ^{21 to} R ²³ are an alkyl group or an alkenyl group and have a smaller number of carbon atoms, and 2 to 5 are preferred. More preferably, the side chain groups R ^{21 to} R ²³ contain at least one compound having an alkenyl group. In this case, CH ₂ = CH- or _{CH 2 = CH-CH 2 -CH} 2 - is particularly preferred. The dielectric anisotropy Δε is 7 or more, preferably 10 or more, more preferably 13 or more, and 1
Particularly preferred is 5 or more. More specifically, the general formula (II-
Compounds represented by 4) and (II-8) to (II-13) are particularly preferable. By doing so, it was found that a broader nematic phase can be obtained by combining the first component, especially the compound selected from the first group of the present invention. In order to make the birefringence relatively small, the general formula (II-1) or (II-2) may be used, and more specifically, the general formulas (II-4) to (II-8) are preferable. To make the birefringence relatively large, the general formula (II
-3) is preferably used, and more specifically, general formula (II-9) to
(II-13) is preferable. It is preferable to use these in combination for the medium birefringence. In any of these cases,
Although the number of components of 2 to 10 types can be used as the second component, the number of components of 3 to 10 types is preferable, and the number of components of 3 to 6 types is more preferable.

The present invention further includes (3) the general formula (III-1) to
By combining a compound selected from the third group consisting of the compounds represented by (III-4) with the above liquid crystal composition, for example, an increase in threshold voltage or response speed can be suppressed without impairing other characteristics. It has been found that the nematic phase-isotropic liquid phase transition temperature (T _NI ) can be efficiently improved and a nematic liquid crystal composition that can be used in a high temperature range can be prepared. Further, it has the effect of inducing and expanding the nematic phase even at low temperature, and therefore, long-term preservation of nematic liquid crystallinity at low temperature is expected. Furthermore, the birefringence ((△
Since n) can be optimized, the viewing angle characteristics and the contrast ratio of the liquid crystal display device can be improved.

(3) General formula (III-1) according to the present invention
Of the compounds selected from the third group consisting of the compounds of (III-4), the compounds of Nos. (3-1) to (3-9) as typical compounds and their transition temperatures and dielectric anisotropies Δ ε is the third
It is shown in the table. Here, the compounds of No. (3-1) to (3-3) belong to the first component, and the compounds of No. (3-4) to (3-6) belong to the second component. And No. (3-7) to (3-
The compound of 9) belongs to other components. In addition, each liquid crystal compound was used after being sufficiently purified by removing impurities by methods such as distillation, column purification, and recrystallization.

[0045]

[Table 3]

(In the table, C is a crystalline phase, S is a smectic phase, N is a nematic phase, and I is an isotropic liquid phase.)

The liquid crystal composition of the present invention is further characterized in that among the compounds represented by the general formulas (I-1) to (III-4) selected from the first group, the second group and the third group, The point is that one or more compounds may contain a compound in which one or more hydrogen atoms (H) of the 1,4-cyclohexylene group in each compound are replaced with deuterium atoms. Such a liquid crystal composition has a property of stabilizing a nematic phase at a low temperature, and in particular, the nematic liquid crystallinity can be preserved for a longer period even when stored at a low temperature. The present inventors have confirmed the effects of a compound having a cyclohexane ring substituted with a deuterium atom, in Japanese Patent Application Nos. 5-104144 and 5-18273.
As has been made clear in the specification of No. 4, etc., the present invention further enhances this effect. That is, due to this characteristic, the liquid crystal composition of the present invention can have nematic properties for a long time even when stored at low temperature.

Furthermore, the liquid crystal composition of the present invention is recognized as a liquid crystal compound in order to improve other characteristics of the liquid crystal composition in addition to the compounds of the general formulas (I-1) to (III-4). Ordinary nematic liquid crystal, smectic liquid crystal, cholesteric liquid crystal and the like may be contained.

The liquid crystal composition of the present invention thus obtained has a crystalline phase at a nematic phase-isotropic liquid phase transition temperature (T _NI ) of 80 ° C. or higher, as shown in Examples described later. Alternatively, the smectic phase-nematic phase transition temperature (T → _N ) has a nematic phase in a wide temperature range of about −20 ° C. or lower, and 0.
It was possible to obtain characteristics showing a birefringence Δn of 080 or more, a threshold voltage V _{th of about} 2.0 V and a response of 25 ms or less.

The nematic liquid crystal composition of the present invention is
When the heating acceleration test and the ultraviolet irradiation acceleration test shown in the examples described later were performed, it has a high voltage holding ratio of 99% or more even after each acceleration test, and is chemically stable and has a high resistance value. It was confirmed.

As described above, the nematic liquid crystal composition of the present invention is a liquid crystal composition which exhibits liquid crystallinity in a wide temperature range and has a sufficiently high voltage holding ratio, which does not cause flicker and is excellent in contrast. It has become possible to provide a liquid crystal display device. Further, when an active matrix liquid crystal display device was produced, a liquid crystal display device having excellent contrast without producing flicker could be produced.
Furthermore, when TN-LCD and STN-LCD liquid crystal display panels were manufactured, it was confirmed that display was possible in a wide range of drive frequencies.

[0052]

The present invention will be described in detail below with reference to examples.
The present invention is not limited to these examples. In the examples, the meanings of the symbols of the measured characteristics are as follows.

T _NI : Nematic phase-isotropic liquid phase transition temperature (° C.) T → _N : Crystal phase or smectic phase-nematic phase transition temperature (° C.) V _th : TN-LCD having a liquid crystal layer thickness d of 6 μm Threshold voltage (V) Δε: Dielectric anisotropy Δn: Birefringence η: Viscosity at 20 ° C. (cp) τ _r = τ _d : Time at which rise and fall of liquid crystal become equal (Ms) Further, in the accelerated test of the composition, 2 g of the liquid crystal composition was put into an ampoule tube, deaerated under vacuum, and then subjected to nitrogen substitution treatment and sealed.
The test was conducted at 180 ° C. for 1 hour for heating promotion test and for 10 hours for ultraviolet irradiation promotion test “SUNTEST” (manufactured by Original Hanau). The specific resistance and voltage holding ratio of the liquid crystal composition were measured before and after the accelerated test.

(Example 1)

[0055]

[Chemical 12]

A nematic liquid crystal composition (4-1) comprising
Was adjusted and various properties of this composition were measured. The results were as follows. T _NI : 105.6 ° C. T → _N : −35. C. V _th : 2.29 V Δε: 5.1 Δn: 0.124 η: 17.1 c. p. τ _r = τ _d : 14.9 ms Specific resistance before test: 5.8 × 10 ¹⁵ Ω c
Specific resistance after m heating acceleration test: 6.3 × 10 ¹⁴ Ω c
m Specific resistance after UV irradiation acceleration test: 5.3 × 10 ¹⁴ Ω c
m Voltage holding ratio before test: 99.9% (Measuring temperature 80 ° C) Voltage holding ratio after heating accelerated test: 99.7% (Measuring temperature 80 ° C) Voltage holding ratio after ultraviolet irradiation accelerated test: 99.7% ( A measurement temperature of 80 ° C.) An active matrix liquid crystal display device using the nematic liquid crystal composition (4-1) as a constituent material was manufactured, and it was confirmed that the leakage current was small and flicker did not occur.

The nematic liquid crystal composition (4-1)
A liquid crystal composition was prepared by adding a chiral substance "S-811" (manufactured by Merck & Co., Inc.) to. On the other hand, an organic film of "SAN EVER 150" (manufactured by Nissan Kagaku Co., Ltd.) is rubbed on the opposing flat transparent electrodes to form an alignment film, and STN-LCD with a twist angle of 220 degrees is formed.
A display cell was produced. The liquid crystal composition was injected into this cell to form a liquid crystal display device, and the display characteristics were measured.
As a result, the threshold voltage is low, high time division characteristics are excellent,
ST with improved display screen flickering and crosstalk
A liquid crystal display device exhibiting N-LCD display characteristics was obtained.

(Comparative Example 1)

[0059]

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A comparative liquid crystal (a-4) consisting of was prepared and various properties of this composition were measured. The results were as follows. T _NI : 106.7 ° C. T → _N : +17. C. V _th : 2.21 V Δε: 5.6 Δn: 0.080 η: 25.7 c. p. τ _r = τ _d : 30.8 ms Specific resistance before test: 7.8 × 10 ¹³ Ω c
Specific resistance after m heating acceleration test: 5.3 × 10 ¹³ Ω c
m Specific resistance after UV irradiation acceleration test: 5.0 × 10 ¹³ Ω c
m Voltage holding ratio before test: 99.1% (Measuring temperature 80 ℃) Voltage holding ratio after heating acceleration test: 98.2% (Measuring temperature 80 ℃) Voltage holding ratio after UV irradiation acceleration test: 98.3% ( (Measurement temperature: 80 ° C.) When this comparative liquid crystal (a-4) is compared with Example 1, T
_Although the characteristics of _NI , V _th , and Δε are almost the same, the liquid crystal composition of Example 1 has a viscosity of 35% and a response speed of 5%.
The reduction was 0%, the specific resistance was improved by about one digit, and the voltage holding ratio was close to 100%. This is △
This is due to the difference in whether or not the compound corresponding to the compound having an anisotropy of dielectric constant of n−2 to +2 and the compound corresponding to the compound having anisotropy of dielectric constant of +7 or more are contained. It was confirmed that the composition was superior.

(Example 2)

[0062]

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A nematic liquid crystal composition (4-2) consisting of
Was prepared and various properties of this composition were measured. The results were as follows. T _NI : 87.9 ° C. T → _N : −30. C. V _th : 2.50 V Δε: 3.5 Δn: 0.115 η: 13.2 c. p. τ _r = τ _d : 15.3 ms

(Example 3)

[0065]

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A nematic liquid crystal composition (4-3) consisting of
Was prepared and various properties of this composition were measured. The results were as follows. T _NI : 104.9 ° C. T → _N : −25. ° C V _th : 2.40 V Δε: 4.6 Δn: 0.104 τ _r = τ _d : 18.3 ms

(Example 4)

[0068]

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A nematic liquid crystal composition (4-4) consisting of
Was prepared and various properties of this composition were measured. The results were as follows. T _NI : 100.3 ° C. T → _N : −30. C V _th : 2.33 V Δε: 4.6 Δn: 0.093 τ _r = τ _d : 22.9 ms

(Example 5)

[0071]

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A nematic liquid crystal composition (4-5) consisting of
Was prepared and various properties of this composition were measured. The results were as follows. T _NI : 81.0 ° C. T → _N : −27. V C _th : 2.46 V Δε: 3.3 Δn: 0.092 τ _r = τ _d : 15.2 ms

(Example 6)

[0074]

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A nematic liquid crystal composition (4-6) consisting of
Was prepared and various properties of this composition were measured. The results were as follows. T _NI : 88.6 ° C. T → _N : −40. ° C V _th : 1.85 V Δε: 4.3 Δn: 0.077 τ _r = τ _d : 26.0 ms Specific resistance before test: 4.9 × 10 ¹³ Ω c
Specific resistance after m heating acceleration test: 1.2 × 10 ¹³ Ω c
m Specific resistance after UV irradiation acceleration test: 1.1 × 10 ¹³ Ω c
m Voltage holding ratio before test: 99.7% (Measuring temperature 80 ° C) Voltage holding ratio after heating acceleration test: 99.2% (Measuring temperature 80 ° C) Voltage holding ratio after ultraviolet irradiation acceleration test: 99.3% ( (Measurement temperature 80 ℃)

(Example 7)

[0077]

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A nematic liquid crystal composition consisting of (4-7)
Was prepared and various properties of this composition were measured. The results were as follows. T _NI : 90. 1 ° C. T → _N : −30. ° C V _th : 1.95 V Δε: 4.1 Δn: 0.085 τ _r = τ _d : 21.3 ms

[0079]

According to the present invention, the birefringence index Δ according to the use
n is obtained, and a nematic liquid crystal composition exhibiting a high-speed response and exhibiting a nematic phase in a wide temperature range is obtained. Further, it has the effect of maintaining nematic liquid crystallinity during long-term low temperature storage, has a high voltage holding ratio, and has high chemical stability.

Therefore, the liquid crystal display device of the present invention using this is excellent in viewing angle characteristics, can improve the flickering of the display screen and the crosstalk phenomenon, and has a large amount of information.
Good drive and display characteristics can be obtained with STN-LCD or active matrix type.

Claims (7)

[Claims] 1. A liquid crystal composition comprising a liquid crystal compound having neither a nitrogen atom nor an ester group has a dielectric anisotropy of −
40 to 85% by weight of the first component containing at least 3 or more compounds of 2 to +2, and 15 to 60% by weight of the second component of at least two compounds having a dielectric anisotropy of +7 or more. , Nematic phase-isotropic liquid phase transition temperature T
_NI is 75 ° C or higher, crystalline phase or smectic phase-
A nematic liquid crystal composition having a nematic phase transition temperature T → _N of −10 ° C. or lower. 2. The second component has a dielectric anisotropy of +1.
The nematic liquid crystal composition according to claim 1, containing 0 to 50% by weight of a compound. 3. The first component is (1) the general formula (I-1) to (I-
3) [Chemical 1] (In the formula, Z ¹¹ , Z ¹² , Z ¹³ and Z ¹⁴ each independently represent —C ₂ H ₄ — or a single bond, Z ¹⁵ represents —C≡C— or a single bond, and R ¹¹ , R ¹² and R ¹³ each independently represent a linear alkyl group having 2 to 5 carbon atoms, an alkoxy group, an alkoxyalkyl group, an alkenyl group or an alkenyloxy group, and R ¹⁴ , R ¹⁵ and R ¹⁶ are each independently Represents a linear alkyl group having 1 to 10 carbon atoms, an alkoxy group, an alkoxyalkyl group, an alkenyl group or an alkenyloxy group, wherein Y ¹¹ , Y ¹² and Y ¹³ are each independently a hydrogen atom, a fluorine atom or- CH ₃ is represented, k, l and m are each independently an integer of 0 or 1, and ring A ¹¹ and ring A ¹² are each independently a trans-1,4-cyclohexylene group or 1,4-cyclohexene. Represents a cenylene group However, the hydrogen atom (H) of the 1,4-cyclohexylene group in each compound may be substituted with a deuterium atom (D).), Which is a compound selected from the first group. The nematic liquid crystal composition according to claim 1 or 2. 4. The second component is (2) general formulas (II-1) to (II
-3) [Chemical 2] (In the formula, Z ²¹ and Z ²³ are each independently a single bond, -C
₂ H ₄ — or —C ₄ H ₈ —, Z ²² represents —C ₂ H ₄ — or —C ₄ H ₈ —, Z ²⁴ represents a single bond or —C≡C—, R ²¹ , R ²² and R ²³ each independently represent a linear alkyl group having 2 to 10 carbon atoms, an alkoxy group, an alkoxyalkyl group, an alkenyl group or an alkenyloxy group, and X ²¹ , X ²² and X ²³ are each independently. to fluorine atom, chlorine atom, -OCF _3, -OCHF ₂ or -CF
₃ , each of Y ²¹ , Y ²² and Y ²³ independently represents a hydrogen atom or a fluorine atom, p and q each independently represent an integer of 0 or 1, and
The hydrogen atom (H) of the 4-cyclohexylene group may be replaced with a deuterium atom (D). 4. The nematic liquid crystal composition according to claim 1, which is a compound selected from the second group consisting of compounds represented by 5. (3) General formulas (III-1) to (III-4): (In the formula, Z ³¹ , Z ³² , Z ³³ and Z ³⁵ each independently represent a single bond, —C ₂ H ₄ — or —C ₄ H ₈ —, and Z ³⁴ represents a single bond, —C ₂ H ₄ Represents —, —C ₄ H ₈ — or —C≡C—, and R ³¹ , R ³² , R ³³ , R ³⁴ and R ³⁵ are each independently a straight chain alkyl group or alkenyl having 1 to 5 carbon atoms. Represents a group, X ³¹ , X ³² and X ³³ each independently represent a linear alkyl group having 1 to 5 carbon atoms, a fluorine atom, a chlorine atom, —OCF ₃ , —OCHF ₂ or —CF ₃ ;
Y ³¹ , Y ³² , Y ³³ , Y ³⁴ , Y ³⁵ , Y ³⁶ , Y ³⁷ , Y ³⁸ and Y ³⁹ each independently represent a hydrogen atom or a fluorine atom, and r represents an integer of 0, 1 or 2. The hydrogen atom (H) of the 1,4-cyclohexylene group in each compound may be replaced with a deuterium atom (D). 5. A nematic liquid crystal composition according to claim 1, which contains a compound selected from the third group consisting of the compounds represented by 6. An active matrix liquid crystal display device using the nematic liquid crystal composition according to claim 1. 7. A twisted nematic or super twisted nematic liquid crystal display device using the nematic liquid crystal composition according to any one of claims 1, 2, 3, 4 and 5.