JP3453781B2 - Nematic liquid crystal composition and liquid crystal display device using the same - Google Patents

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 device using the nematic liquid crystal composition.

[0002]

2. Description of the Related Art TN-LCD is a typical liquid crystal display device.
(Twisted nematic liquid crystal display element)
Used in clocks, calculators, electronic organizers, pocket computers, word processors, personal computers, etc. 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 (Super Twisted Nematic) -LCD 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. Therefore, in order to deal with such a display device, new liquid crystal compounds or liquid crystal compositions have been proposed at present.

[0004]

The TN-LCD and STN-LCD have problems such as chemical stability of liquid crystal materials, low voltage drivability and response characteristics of liquid crystal display devices.

For example, an STN-LCD having a large amount of information such as a word processor and a personal computer is required to have a good driving characteristic with a high time division number. However, an increase in the time division number causes an increase in drive voltage, which results in a drive circuit. Have a great influence on. One way to reduce this is

[0006]

[Equation 1]

(Wherein V _th is a threshold voltage, k is a proportional constant, K is an elastic constant, and Δε is a dielectric anisotropy). A method of reducing a driving voltage by using a material is known. However, since many such liquid crystal materials tend to increase the viscosity of the liquid crystal material, it is difficult to obtain good response characteristics or the capacitance component of each pixel is increased. There are problems such as narrowing the possible driving frequency range and causing a crosstalk phenomenon.

On the other hand, in the case of a conventional liquid crystal material that can be driven at a low voltage, it is generally known that the resistance value is low at the prepared initial stage or after an accelerated test by heating or ultraviolet irradiation. Such a low resistance value of the liquid crystal material is not preferable because it causes a flicker of the display screen and a decrease in contrast due to an increase in the number of time divisions.

Further, in order to compensate for the dark image quality due to the increase in the amount of information, it is common to use a backlight as an auxiliary light source in STN-LCD. For this reason, liquid crystal materials used for backlight STN-LCDs are required to have new chemical stability such as heat resistance and light resistance.

In addition to these required characteristics, particularly in the active matrix system, it is important that the leakage current is small and the voltage holding ratio is high in order to obtain uniform and high contrast. In order to obtain such characteristics,
For example, the following compounds have been used.

[0011]

[Chemical 5]

(In the formula, R ⁶ represents a linear alkyl group, an alkenyl group or an alkoxyalkyl group, and X ⁴ represents --O.
It represents CF ₃ , —CF ₃ or —OCHF ₂ , and X ⁵ represents H or F. However, even if these compounds are used, the threshold voltage required for the active matrix system cannot be sufficiently reduced.

The problem to be solved by the present invention is to provide a liquid crystal composition which exhibits liquid crystallinity in a wide temperature range, has a low threshold voltage and has a sufficiently high voltage holding ratio, and uses this liquid crystal composition. Another object of the present invention is to provide a liquid crystal display device which is free from flicker and has excellent contrast.

[0014]

In order to solve the above-mentioned problems, the present invention provides the following nematic liquid crystal compositions.

First, as the first liquid crystal composition of the present invention,
(1) General formula (I)

[0016]

[Chemical 6]

(Wherein R ¹ represents a linear alkyl group having 2 to 7 carbon atoms, and n represents an integer of 0 to 2) and (2) general formula (II) to (IV)

[0018]

[Chemical 7]

(Wherein each R ² independently represents a straight-chain alkyl group having 2 to 7 carbon atoms), and a compound selected from the group consisting of compounds represented by the formula: A nematic liquid crystal composition is provided.

As the second liquid crystal composition of the present invention, (1)
Compounds represented by general formula (I) and (2) general formula (V)
~ (XVII)

[0021]

[Chemical 8]

(In the formula, each R ³ independently represents a linear alkyl group having 2 to 7 carbon atoms, an alkenyl group or C _j H
_{2j + 1 -O-C k H} 2k - represents, j represents an integer of 1 to 3, k represents an integer of 2 to 5, X ² is F, OCF _3, C
It represents F ₃ or OCHF ₂ , and X ³ represents F or H. And a nematic liquid crystal composition comprising a compound selected from the group consisting of compounds represented by

As the third liquid crystal composition of the present invention,
(1) compound represented by general formula (I), (2) general formula
A compound selected from the group consisting of compounds represented by (II) to (IV) and (3) a compound selected from the group consisting of compounds represented by general formulas (V) to (XVII). A nematic liquid crystal composition is provided.

Further, in each of the first to third nematic liquid crystal compositions, particularly the general formulas (XVIII) to (XXII)

[0025]

[Chemical 9]

[0026] (wherein, R ⁴ is a linear alkyl group having 2 to 7 carbon atoms, an alkenyl group, or _{C p H 2p +1 -O-C} q H 2q
- represents, p represents an integer of 1 to 3, q represents an integer of 2 to 5, R ⁵ is a each independently, 2-7 carbon atoms
Represents a linear alkyl group, an alkenyl group or an alkenyloxy group. And a nematic liquid crystal composition comprising a compound selected from the group consisting of compounds represented by

The present invention further provides a twisted nematic or super twisted nematic liquid crystal display device using the above nematic liquid crystal composition.

Typical examples (Nos. 1 to 3) of the compounds represented by the general formula (I) according to the present invention and their phase transition temperatures are shown in the following Table 1 in the general formulas (II) to (IV). Examples of representative compounds (Nos. 4 to 6) and their phase transition temperatures are shown in Table 2 below, and the compounds of the general formulas (V) to (XVI
Examples of typical compounds represented by I) (No. 7)
~ 29) and their phase transition temperatures are shown in Table 3 below.

In the table below, mp is the temperature at which the crystal phase changes to the liquid crystal phase or the isotropic liquid phase, and cp is the temperature at which the liquid crystal phase changes to the isotropic liquid phase. Respectively.
In addition, each liquid crystal compound was used after being sufficiently purified by removing impurities by methods such as distillation, column purification, and recrystallization.

[0030]

[Table 1]

[0031]

[Table 2]

[0032]

[Table 3]

[0033]

[Table 4]

The characteristic feature of the liquid crystal composition of the present invention is that it contains the compound represented by the general formula (I) as an essential component. It is known that the compound represented by the general formula (I) has an effect of reducing the driving voltage without lowering the voltage holding ratio of the composition, even though the compound has a relatively large dielectric anisotropy of about 15. Has been. However, compounds of general formula (I) are for example

[0035]

[Chemical 10]

(In the formula, R ⁷ and R ⁸ each independently represent an alkyl group, an alkenyl group or an alkoxyl group.)
When mixed with a general-purpose liquid crystal compound represented by, it tends to exhibit a crystal phase or a smectic phase, and it is not possible to prepare a nematic liquid crystal composition that can be driven at a particularly low temperature using the compound of the general formula (I). It was difficult.

The present inventors have studied the combination of the compound represented by the general formula (I) with various liquid crystal compounds, and as a result, selected from the group consisting of the compounds represented by the general formulas (II) to (IV). Compound and / or general formula (V) to (X
It was found that by using a compound selected from the group consisting of compounds represented by VII), a nematic liquid crystal composition that can be used in a wide temperature range can be prepared without impairing the excellent properties of the compound of general formula (I). .

The compounds represented by the general formulas (II) to (IV) used in the nematic liquid crystal composition of the present invention have the effect of reducing the driving voltage without lowering the voltage holding ratio. This effect is due to the fact that each compound of the general formulas (II) to (IV) has a 3,4,5-trifluorophenyl group and has a small elastic constant in spite of a relatively small dielectric anisotropy. Conceivable.

Further, the compounds of general formula (II) ~ (IV), respectively - (CH _{2) 4} - or - (CH _{2) 2} - compatibility since it has a linking group, the other liquid crystal compound It also has excellent vapor pressure temperature characteristics. Therefore, the liquid crystal composition of the present invention is also characterized in that the liquid crystal injection conditions in the manufacturing process of the liquid crystal display panel are relaxed and the uneven injection in the manufacturing process of the large-sized liquid crystal panel is reduced.

The compounds represented by the general formulas (V) to (XVII) used in the nematic liquid crystal composition of the present invention have an effect of maintaining and improving the above-mentioned characteristics. This general formula (V) ~ (XVI
The compound represented by I) can optimize the elastic constant that plays an important role in display characteristics, and can prepare a nematic liquid crystal composition having an elastic constant ratio (K ₃₃ / K ₁₁ ) according to the application. To do.

Each of the compounds represented by the general formulas (V) to (XVII) is a compound having a medium value of dielectric anisotropy in the range of +4 to +12. It is often difficult to reduce the threshold voltage of the composition to 1.6 V or less even if the compound of 1) is added to the liquid crystal composition. However, these general formulas (V) to (XVII)
A compound selected from the group consisting of compounds represented by the formula (1) and a compound represented by the general formula (I), which is an essential component in the present invention, and additionally a compound represented by the general formulas (II) to (IV) By using a compound selected from the group in combination, a nematic liquid crystal composition that can operate at a sufficiently low driving voltage can be obtained.

More specifically, the compounds represented by the general formulas (V) to (XVII) optimize the birefringence (Δn) of the liquid crystal composition to reduce the color unevenness of the liquid crystal display device and the viewing angle characteristics. It is possible to improve the contrast ratio and the like. Further, it has an effect of expanding the nematic phase temperature range of the composition to the high temperature side and the low temperature side, and can expand the drivable temperature range of the liquid crystal display device. Moreover, since the viscosity of the nematic liquid crystal composition can be lowered, a liquid crystal material having a high-speed response in a wide temperature range can be easily obtained.

Further, a liquid crystal display device capable of forming a larger pretilt angle can be manufactured by using the liquid crystal composition of the present invention. Specifically, a compound selected from the group consisting of the compounds represented by the general formula (I) or the general formulas (II) to (IV) alone has no particular effect on the pretilt angle formed. However, the general formula (V)
In the compounds represented by the formulas (XVII) to (XVII), the compound in which the terminal group R ³ is an alkoxyalkyl group, or the liquid crystal composition containing a relatively large amount of this compound can form a larger pretilt angle, and therefore the compound represented by the general formula (V ) ~ (XVI
Compounds selected from the group consisting of compounds represented by formula (I), compounds represented by formula (I), and further compounds represented by formula (I)
Even when a compound selected from the group consisting of the compounds represented by I) to (IV) is mixed, the effect of improving and maintaining the pretilt angle can be obtained. Due to the effect of improving and maintaining such a pretilt angle, it is possible to remarkably suppress the occurrence of reverse tilt due to the heat radiation of the backlight in the TFT-LCD or the occurrence of stripe domains in the TFT-LCD, thereby improving the yield. it can.

Each of the first to third nematic liquid crystal compositions of the present invention may contain a compound selected from the group consisting of compounds represented by the general formulas (XVIII) to (XXII). A liquid crystal composition having more excellent properties can be obtained.

The compounds represented by the general formulas (XVIII) to (XXII) can extend the temperature range of the nematic phase of the above liquid crystal composition to a low temperature range. Further, since these compounds can reduce the viscosity of the nematic liquid crystal composition, it is possible to obtain a liquid crystal material having a fast response in a wide temperature range.

The content of each compound in the liquid crystal composition of the present invention is preferably such that the compound represented by the general formula (I) is contained in the range of 3 to 40% by weight, and the compound represented by the general formula (II) is contained. In the range of 0 to 15% by weight, the compound of the general formula (III) in the range of 5 to 60% by weight, and the compound of the general formula (IV) in the range of 0 to 20% by weight. V) to (XVII), each of which is selected from the group consisting of compounds represented by 0 to 30% by weight.
It is preferable to contain it in the range of 10 to 80 in total.
It is preferably contained in the range of wt%. When a compound selected from the group consisting of compounds represented by the general formulas (XVIII) to (XXII) is used, the total amount is 0 to 25.
It is preferably contained in the range of wt%.

The liquid crystal composition of the present invention has the general formulas (I) to (X
In addition to the compound of XII), in order to improve other properties of the liquid crystal composition, a usual nematic liquid crystal, smectic liquid crystal, cholesteric liquid crystal or the like recognized as a liquid crystal compound may be contained. Typical examples of such liquid crystal compounds are given below.

[0048]

[Chemical 11]

(In the formula, R ⁹ and R ¹⁰ each independently represent an alkyl group, an alkenyl group or an alkoxyl group,
X ⁶ and X ⁷ each independently represent H or F. The liquid crystal composition of the present invention is chemically very stable and has a high resistance value, as shown in Examples described later. Therefore, it is possible to display in a wide range of driving frequencies.

The superiority of the liquid crystal composition of the present invention will be shown below. First, a mixed liquid crystal (a) is used as a base liquid crystal composed of a currently widely used compound.

[0051]

[Chemical 12]

(In the above, "wt%" means "wt%". The same applies hereinafter). Then, 80% by weight of this mixed liquid crystal (a) and No. 1 in Table 1 above. Compound 2 of 2
A liquid crystal composition No. 30 consisting of 0% by weight was prepared. In addition, for comparison, No. 3,4 in place of compound 2
-Formulas (b), (c) and (d) having a difluorophenyl group

[0053]

[Chemical 13]

Liquid crystal compositions (e), (f) and (g) were prepared in the same manner by using 20% by weight of each of the compounds of the above. For each of these compositions, the nematic phase-
TN-LC with isotropic liquid phase transition temperature (T _NI ) and cell thickness 6μm
The threshold voltage (V _th ) and the dielectric anisotropy (Δε) when D was formed were measured. The results are shown in Table 4 below.

[0055]

[Table 5]

From Table 4, nematic liquid crystal composition No. 1 containing the compound represented by the general formula (I). It can be seen that No. 30 has a very low driving voltage as compared with the comparative mixed liquid crystals (e), (f) and (g). Further, as shown in Examples described later, when a heating acceleration test and an ultraviolet irradiation acceleration test were performed on these liquid crystal compositions, the nematic liquid crystal composition No. It was confirmed that 30 had a high voltage holding ratio of 98% or more after each accelerated test.

Further, this liquid crystal composition No. When an active matrix liquid crystal display device was manufactured using No. 30, it was possible to manufacture a liquid crystal display device with excellent contrast without causing flicker.

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, has a low threshold voltage, and has a sufficiently high voltage holding ratio, and flicker occurs. Instead, it is possible to provide a liquid crystal display device having excellent contrast.

[0059]

The present invention will be described in detail below with reference to examples.
The invention is not limited to these examples. In addition, "wt%" in the compositions of the following Examples and Comparative Examples
Means "% by weight".

The specific resistance of the composition was determined by placing 2 g of the liquid crystal composition in an ampoule tube, degassing under vacuum, and then enclosing it after a treatment of nitrogen substitution, 150 ° C. for 1 hour of heating acceleration test, and 10 hours of ultraviolet ray irradiation. The specific resistance of the liquid crystal composition after the irradiation acceleration test "SUNTEST" (manufactured by Original Hanau) was measured.

In the examples, the symbols of the measured characteristics have the following meanings. T _NI : Nematic phase-isotropic liquid phase transition temperature (° C.) Δε: Dielectric anisotropy Δn: Birefringence V _th : Threshold voltage (V when a TN-LCD with a cell thickness of 6 μm is formed )

(Example 1)

[0063]

[Chemical 14]

A nematic liquid crystal composition No. 31
Was prepared and various properties of this composition were measured. The results were as follows. T _NI : 86.0 ° C. Δε: 10.3 Δn: 0.101 V _th : 1.59 V Specific resistance before test: 7.5 × 10 ¹³ Ω · c
m Specific resistance after accelerated heating test: 5.6 × 10 ¹³ Ω ・ c
m Specific resistance after UV irradiation acceleration test: 3.0 × 10 ¹³ Ω ・ c
m Voltage holding ratio before test: 99.6% Voltage holding ratio after heating accelerated test: 98.7% Voltage holding ratio after ultraviolet irradiation accelerated test: 98.3% This nematic liquid crystal composition No. When an active matrix liquid crystal display device having 31 as a constituent material was manufactured, it was confirmed that the leakage current was small and flicker did not occur.

(Example 2)

[0066]

[Chemical 15]

A nematic liquid crystal composition No. 32
Was prepared and various properties of this composition were measured. The results were as follows. T _NI : 78.6 ° C. Δε: 10.7 Δn: 0.103 V _th : 1.4 V

(Example 3)

[0069]

[Chemical 16]

A nematic liquid crystal composition No. 33
Was prepared and various properties of this composition were measured. The results were as follows. T _NI : 85.5 ° C. Δε: 8.5 Δn: 0.103 V _th : 1.59 V

(Example 4)

[0072]

[Chemical 17]

A nematic liquid crystal composition No. 34
Was prepared and various properties of this composition were measured. The results were as follows. T _NI : 85.5 ° C. Δε: 9.5 Δn: 0.118 V _th : 1.70 V

(Example 5)

[0075]

[Chemical 18]

A nematic liquid crystal composition No. 35
Was prepared and various properties of this composition were measured. The results were as follows. T _NI : 102.1 ° C. Δε: 7.1 Δn: 0.114 V _th : 2.03 V

(Example 6)

[0078]

[Chemical 19]

A nematic liquid crystal composition No. 36
Was prepared and various properties of this composition were measured. The results were as follows. T _NI : 98.8 ° C. Δε: 7.3 Δn: 0.113 V _th : 1.89 V

(Embodiment 7)

[0081]

[Chemical 20]

A nematic liquid crystal composition No. 37
Was prepared and various properties of this composition were measured. The results were as follows. T _NI : 100.1 ° C. Δε: 8.8 Δn: 0.126 V _th : 1.77 V

(Embodiment 8)

[0084]

[Chemical 21]

A nematic liquid crystal composition No. 38
Was prepared and various properties of this composition were measured. The results were as follows. T _NI : 110.4 ° C. Δε: 8.2 Δn: 0.131 V _th : 1.96 V

(Example 9)

[0087]

[Chemical formula 22]

A nematic liquid crystal composition No. 39
Was prepared and various properties of this composition were measured. The results were as follows. T _NI : 90.0 ° C. Δε: 9.7 Δn: 0.124 V _th : 1.59 V

(Example 10)

[0090]

[Chemical formula 23]

A nematic liquid crystal composition No. 40
Was prepared and various properties of this composition were measured. The results were as follows. T _NI : 94.4 ° C. Δε: 9.8 Δn: 0.133 V _th : 1.70 V

(Embodiment 11)

[0093]

[Chemical formula 24]

A nematic liquid crystal composition No. 41
Was prepared and various properties of this composition were measured. The results were as follows. T _NI : 93.2 ° C. Δε: 7.8 Δn: 0.082 V _th : 1.67 V

(Example 12)

[0096]

[Chemical 25]

A nematic liquid crystal composition No. 42
Was prepared and various properties of this composition were measured. The results were as follows. T _NI : 111.2 ° C. Δε: 7.7 Δn: 0.104 V _th : 1.96 V

(Example 13)

[0099]

[Chemical formula 26]

A nematic liquid crystal composition No. 43
Was prepared and various properties of this composition were measured. The results were as follows. T _NI : 81.6 ° C. Δε: 9.1 Δn: 0.102 V _th : 1.56 V

(Example 14)

[0102]

[Chemical 27]

A nematic liquid crystal composition No. 44
Was prepared and various properties of this composition were measured. The results were as follows. T _NI : 92.5 ° C. Δε: 7.3 Δn: 0.093 V _th : 1.75 V

(Example 15)

[0105]

[Chemical 28]

A nematic liquid crystal composition No. 45
Was prepared and various properties of this composition were measured. The results were as follows. T _NI : 131.2 ° C. Δε: 7.0 Δn: 0.109 V _th : 2.12 V

(Example 16)

[0108]

[Chemical 29]

A nematic liquid crystal composition No. 46
Was prepared and various properties of this composition were measured. The results were as follows. T _NI : 128.4 ° C. Δε: 7.4 Δn: 0.108 V _th : 2.07 V

(Example 17) A composition (h) comprising a compound represented by the general formula (I)

[0111]

[Chemical 30]

Composition (i) comprising a compound represented by the general formula (III)

[0113]

[Chemical 31]

And a composition (j) comprising a compound represented by the general formula (IX)

[0115]

[Chemical 32]

Each was prepared. Various nematic liquid crystal compositions were prepared by appropriately mixing two or three kinds of the three kinds of compositions with different composition ratios. The nematic phase-isotropic liquid phase transition temperature (T _NI ), the threshold voltage (V _th ), the crystalline phase or the smectic phase-nematic phase transition temperature ( _TN ) of these compositions was measured to obtain the composition ratio. The relationship between T _NI is shown in FIG. 1, the relationship between the composition ratio and V _th is shown in FIG. 2, and the relationship between the composition ratio and T _N is shown in FIG.

From FIG. 1, compositions (h), (i) and / or
It can be understood that the T _NI of the nematic liquid crystal composition of the present invention containing (j) as a constituent is in the range of 90 ° C to 105 ° C in a wide range of composition ratios. Further, it can be understood from FIG. 2 that _Vth is in the range of 1.5 to 1.7 V with the same composition ratio, and a low voltage is possible.

Further, from FIG. 3, the composition (h) was added in an amount of 3 to 2
The nematic liquid crystal composition containing 5% by weight, 22 to 40% by weight of the composition (i) and 40 to 63% by weight of the composition (j) has T _{N in} the range of approximately -70 ° C to -40 ° C. Moreover, since it is clear from FIG. 1 that T _{NI at the} same composition ratio is around 100 ° C., it can be understood that the nematic liquid crystal composition of the present invention exhibits a nematic phase in a wide temperature range.

(Example 18)

[0120]

[Chemical 33]

A nematic liquid crystal composition No. 47
Was prepared and various properties of this composition were measured. The results were as follows. T _NI : 84.0 ° C. Δε: 7.5 Δn: 0.086 V _th : 1.39 V

(Example 19)

[0123]

[Chemical 34]

A nematic liquid crystal composition No. 48
Was prepared and various properties of this composition were measured. The results were as follows. T _NI : 86.5 ° C. Δε: 7.5 Δn: 0.086 V _th : 1.31 V

This nematic liquid crystal composition No. A chiral substance "S-811" (manufactured by Merck) was added to 48 to prepare a mixed liquid crystal. On the other hand, an organic film of "SAN EVER 150" (manufactured by Nissan Kagaku Co., Ltd.) was rubbed on the opposing flat transparent electrodes to form an alignment film, and a STN-LCD display cell with a twist angle of 220 degrees was produced. The above-mentioned mixed liquid crystal was injected into this cell to construct a liquid crystal display device, and display characteristics were measured. As a result, the STN-LCD has a low threshold voltage, excellent high time division characteristics, and improved display screen flicker and crosstalk.
A liquid crystal display device having display characteristics was obtained.

(Example 20)

[0127]

[Chemical 35]

A nematic liquid crystal composition No. 49
Was prepared and various properties of this composition were measured. The results were as follows. T _NI : 95.3 ° C. Δε: 7.9 Δn: 0.098 V _th : 1.51 V

(Example 21)

[0130]

[Chemical 36]

A nematic liquid crystal composition No. Fifty
Was prepared and various properties of this composition were measured. The results were as follows. T _NI : 106.5 ° C. Δε: 6.6 Δn: 0.099 V _th : 1.66 V

(Example 22)

[0133]

[Chemical 37]

A nematic liquid crystal composition No. 51 consisting of
Was prepared and various properties of this composition were measured. The results were as follows. T _NI : 93.1 ° C. Δε: 6.8 Δn: 0.091 V _th : 1.76 V

(Example 23)

[0136]

[Chemical 38]

A nematic liquid crystal composition No. 52
Was prepared and various properties of this composition were measured. The results were as follows. T _NI : 99.5 ° C. Δε: 7.8 Δn: 0.119 V _th : 1.87 V

[0138]

The nematic liquid crystal composition of the present invention exhibits a nematic phase in a wide temperature range, has a low threshold voltage,
It has a high voltage holding ratio and high chemical stability. Therefore, the liquid crystal display device of the present invention using this can improve the flickering of the display screen and the crosstalk phenomenon,
Good drive characteristics and display characteristics can be obtained in TN-LCD, STN-LCD or active matrix method with a large amount of information.

[Brief description of drawings]

FIG. 1 is a composition ratio and nematic characteristics of a liquid crystal composition of the present invention.
Phase-isotropic liquid phase transition temperature T _NIShows the relationship of (℃)
It is a chart.

FIG. 2 is a chart showing the relationship between the composition ratio and the threshold voltage V _th (V) in the liquid crystal composition of the present invention.

FIG. 3 is a chart showing the relationship between the composition ratio and the crystal phase or smectic phase-nematic phase transition temperature T _N (° C.) in the liquid crystal composition of the present invention.

─────────────────────────────────────────────────── ─── Continuation of front page (56) Reference JP-A-4-234828 (JP, A) JP-A-60-155142 (JP, A) JP-A-2-233626 (JP, A) JP-A-58- 80635 (JP, A) Special table 5-500830 (JP, A) Special table 5-500681 (JP, A) (58) Fields surveyed (Int.Cl. ⁷ , DB name) C09K 19/30-19 / 46

Claims (6)

(57) [Claims] 1. A general formula (I): (Wherein R ¹ represents a linear alkyl group having 2 to 7 carbon atoms, and n represents an integer of 0 to 2), and (2) general formulas (II) to (IV). [Chemical 2] (In the formula, each R ² independently represents a linear alkyl group having 2 to 7 carbon atoms.) A nematic liquid crystal composition containing a compound selected from the group consisting of compounds object. 2. A general formula (I): (Wherein R ¹ represents a linear alkyl group having 2 to 7 carbon atoms, and n represents 1 ), and (2) the general formulas (V) to (XVII): (In the formula, each R ³ independently represents a linear alkyl group having 2 to 7 carbon atoms, an alkenyl group, or CjH2j + 1-O-CkH2k.
- represents, j represents an integer of 1 to 3, k represents an integer of 2 to 5, X ² is F, OCF _3, CF ₃ or OCHF ₂
And X ³ represents F or H. ) A nematic liquid crystal composition containing a compound selected from the group consisting of compounds represented by 3. A compound selected from the group consisting of (1) a compound represented by the general formula (I), (2) a compound represented by the general formula (II) to (IV), and (3). A nematic liquid crystal composition comprising a compound selected from the group consisting of compounds represented by formulas (V) to (XVII) according to claim 2. 4. General formulas (XVIII) to (XXII): (In the formula, R ⁴ is a linear alkyl group having 2 to 7 carbon atoms,
Represents an alkenyl group or CpH2p + 1-O-CqH2q-,
p represents an integer of 1 to 3, q represents an integer of 2 to 5, and each R ⁵ independently represents a linear alkyl group having 2 to 7 carbon atoms, an alkenyl group or an alkenyloxy group. 4. The nematic liquid crystal composition according to claim 1, which contains a compound selected from the group consisting of compounds represented by 5. An active matrix type liquid crystal display device using the nematic liquid crystal composition according to claim 1. 6. A twisted nematic or super twisted nematic liquid crystal display device using the nematic liquid crystal composition according to claim 1.