JP4512975B2 - Liquid crystal composition and liquid crystal display element - Google Patents

Description

  The present invention relates to a liquid crystal composition having both a low threshold voltage and steep electro-optical characteristics at the same time and a high response speed, and a liquid crystal display device using the same.

Among liquid crystal display elements, a super twisted nematic liquid crystal display element (hereinafter referred to as STN-LCD) is used as a display device for a wide range of applications, and various characteristics are required with the development of applications.
In particular, in mobile information terminals, it is a very important feature that it can be used for a long time without the need for battery replacement or charging, and for this, the drive voltage of STN-LCD is reduced, that is, liquid crystal Reducing the threshold voltage Vth of the composition is one effective improvement method. In time-division driving for displaying a large amount of information such as images as well as characters, more steep electro-optical characteristics are required. With regard to the images, not only still images but also moving images are becoming popular today, and improvement of response speed is also an important issue. Various improvement methods have been proposed to date for such demands and problems (see Patent Document 1), but they are still insufficient.
On the other hand, a compound having a difluoromethylene group as a linking group constituting the composition of the present invention (see Patent Document 2) and an azine-based compound have already been known (see Patent Document 3). There is no report of a specific liquid crystal composition with improved voltage and steepness, and a liquid crystal composition that achieves a low threshold voltage and steep electro-optical characteristics at the same time and has a fast response speed and a liquid crystal display device using the same are disclosed. It was sought after.

Japanese Patent Laid-Open No. 2001-200254 JP-A-10-204016 JP-A-10-147562 (Example 4)

  The problem to be solved by the present invention is to provide a liquid crystal composition that simultaneously realizes a low threshold voltage and steep electro-optical characteristics, and a liquid crystal display device using the same.

In order to solve the above problems, the present inventor simultaneously achieves a low threshold voltage and steep electro-optical characteristics by simultaneously using the compounds represented by the general formula (I) and the general formula (II). The present invention has been reached based on the knowledge that it is possible.
That is, the present invention provides the general formula (I) as the first component

（式中、R¹は炭素原子数2〜5のアルキル基又は炭素原子数4〜5のアルケニル基を表す。）で表される化合物を1種又は2種以上を含有し、第二成分として、一般式(II)

(In the formula, R ¹ represents an alkyl group having 2 to 5 carbon atoms or an alkenyl group having 4 to 5 carbon atoms.) The compound represented by 1 type or 2 types or more is used as a second component. General formula (II)

（式中、R²及びR³は、炭素原子数2〜5のアルキル基又は炭素原子数4〜5のアルケニル基を表す。）で表される化合物を1種又は2種以上を含有することを特徴とする液晶組成物であり、当該液晶組成物を用いた液晶表示素子を併せて提供する。

(Wherein R ² and R ³ represent an alkyl group having 2 to 5 carbon atoms or an alkenyl group having 4 to 5 carbon atoms) containing one or more compounds represented by And a liquid crystal display element using the liquid crystal composition.

  According to the present invention, a STN-LCD having a significantly improved display quality can be obtained by providing a liquid crystal composition that simultaneously realizes a low threshold voltage and steep electro-optical characteristics and has a high response speed. That is, the STN-LCD of the present invention has very excellent features such as a low driving voltage, high contrast, and high response speed.

(Compound represented by the general formula (I))
Formula (I)

（式中、R¹は炭素原子数2〜5のアルキル基、炭素原子数4〜5のアルケニル基を表す。）で表される化合物を1種又は2種以上含有することを特徴とするが、更に具体的には一般式(I-a)〜(I-c)で表される化合物がより好ましい。

(In the formula, R ¹ represents an alkyl group having 2 to 5 carbon atoms and an alkenyl group having 4 to 5 carbon atoms). More specifically, compounds represented by the general formulas (Ia) to (Ic) are more preferable.

また、液晶組成物中で一般式(I)で表される化合物の含有量は5〜25質量%であることが好ましく、5〜15質量%であることが特に好ましい。

In addition, the content of the compound represented by the general formula (I) in the liquid crystal composition is preferably 5 to 25% by mass, and particularly preferably 5 to 15% by mass.

(Compound represented by formula (II))
The liquid crystal composition of the present invention further has a general formula (II) as a second component.

（式中、R²及びR³は、炭素原子数2〜5のアルキル基又は炭素原子数4〜5のアルケニル基を表す。）で表される化合物を1種又は2種以上含有することを特徴とするが、更に具体的には一般式(II-a)〜(II-b)で表される化合物がより好ましい。

(Wherein R ² and R ³ represent an alkyl group having 2 to 5 carbon atoms or an alkenyl group having 4 to 5 carbon atoms) containing one or more compounds represented by More specifically, the compounds represented by the general formulas (II-a) to (II-b) are more preferable.

また、液晶組成物中で、一般式(II)で表される化合物の含有量は5〜25質量%であることが好ましく、5〜20質量%であることが特に好ましい。
（一般式(III)で表される化合物）
本発明の液晶組成物は、更に、一般式(III)

In the liquid crystal composition, the content of the compound represented by the general formula (II) is preferably 5 to 25% by mass, and particularly preferably 5 to 20% by mass.
(Compound represented by the general formula (III))
The liquid crystal composition of the present invention further has a general formula (III)

（式中、R⁴は炭素原子数2〜5のアルキル基、炭素原子数2〜4のアルケニル基を表し、X¹は水素原子又はフッ素原子を表す。）で表される化合物1種又は2種以上を含有することが好ましいが、一般式(III)においてR⁴は炭素原子数2〜4のアルケニル基を表すことがより好ましい。更に具体的には、式(III-a)又は(III-b)で表される化合物が特に好ましい。

Wherein R ⁴ represents an alkyl group having 2 to 5 carbon atoms, an alkenyl group having 2 to 4 carbon atoms, and X ¹ represents a hydrogen atom or a fluorine atom. Although it is preferable to contain a seed or more, it is more preferable that R ⁴ in the general formula (III) represents an alkenyl group having 2 to ⁴ carbon atoms. More specifically, a compound represented by the formula (III-a) or (III-b) is particularly preferable.

また、液晶組成物中で、一般式(III)で表される化合物の含有量は5〜30質量%であることが好ましく、10〜30質量%であることがより好ましく、15〜30質量%であることが特に好ましい。

In the liquid crystal composition, the content of the compound represented by the general formula (III) is preferably 5 to 30% by mass, more preferably 10 to 30% by mass, and 15 to 30% by mass. It is particularly preferred that

(Compound represented by formula (IV))
The liquid crystal composition of the present invention further has the general formula (IV)

（式中、R⁵、R⁶はそれぞれ独立してフッ素置換されていてもよい炭素原子数1〜5のアルキル基、炭素原子数2〜4のアルケニル基、炭素原子数3〜4のアルケニルオキシ基を表し、Z¹は単結合、-CH₂-CH₂-又は-CH=CH-を表し、Aは1,4-フェニレン基又はトランス-1,4-シクロヘキシレン基を表し、qは0又は1を表す。）で表される化合物（以下、化合物(IV)と言う。）で表される化合物を含有することが好ましく、急峻な電気-光学特性及び速い応答速度を得ることができる。
更に具体的には、一般式(IV-a)又は(IV-b)

(In the formula, R ⁵ and R ⁶ are each independently a fluorine-substituted alkyl group having 1 to 5 carbon atoms, an alkenyl group having 2 to 4 carbon atoms, and an alkenyloxy having 3 to 4 carbon atoms. represents a group, Z ¹ is a single bond, -CH ₂ -CH ₂ - or an -CH = CH-, a represents a 1,4-phenylene group or a trans-1,4-cyclohexylene group, q is 0 Or a compound represented by (1)) (hereinafter referred to as compound (IV)) is preferable, and steep electro-optical characteristics and a fast response speed can be obtained.
More specifically, general formula (IV-a) or (IV-b)

（式中、R⁵及びR⁶は先述のとおりである。）で表される化合物を使用することが特に好ましい。

It is particularly preferable to use a compound represented by the formula (wherein R ⁵ and R ⁶ are as described above).

  When the compound represented by the general formula (IV) is contained, it is preferably contained in 1 to 8 types, more preferably 1 to 4 types. Further, the content is preferably 5 to 50% by mass, more preferably 5 to 40% by mass, and particularly preferably 5 to 30% by mass.

R ⁵ and R ⁶ are more preferably an alkyl group having 1 to 5 carbon atoms or an alkenyl group having 2 to 4 carbon atoms. More specifically, the alkenyl group preferably has the structure of formulas (a) to (c).

（構造式は右端で環に連結しているものとする。）
更に、本発明の液晶組成物は、一般式(V)

(The structural formula shall be connected to the ring at the right end.)
Furthermore, the liquid crystal composition of the present invention has the general formula (V)

（式中、R⁷及びR⁸は、炭素原子数1〜5のアルキル基又はアルコキシル基、炭素原子数2〜4のアルケニル基又は炭素原子数3〜4のアルケニルオキシ基を表し、B及びDは、それぞれ独立的に1,4-フェニレン基、2又は3-フルオロ-1,4-フェニレン基、2,3-ジフルオロ-1,4-フェニレン基、3,5-ジフルオロ-1,4-フェニレン基、2,6-ジフルオロ-1,4-フェニレン基、2又は3-メチル-1,4-フェニレン基、2,3-ジメチル-1,4-フェニレン基、3,5-ジメチル-1,4-フェニレン基、2,6-ジメチル-1,4-フェニレン基又はトランス-1,4-シクロヘキシレン基を表し、r及びsは、それぞれ独立的に0又は1を表し、Z²及びZ³は、それぞれ独立的に単結合、-CH₂-CH₂-、-CH=CH-、-COO-又は-OCO-を表し、X⁴、X⁵、X⁶及びX⁷は、それぞれ独立的にH、F又はCH₃を表す。）で表される化合物を含有することが好ましいが、液晶組成物中における化合物(V)の含有量は、5〜60質量%が好ましいが、5〜40質量%がより好ましく、5〜30質量%が特に好ましい。
一般式(V)の好ましい例は、一般式(V-a)〜(V-m)で表される化合物である。

(Wherein R ⁷ and R ⁸ represent an alkyl group or alkoxyl group having 1 to 5 carbon atoms, an alkenyl group having 2 to 4 carbon atoms, or an alkenyloxy group having 3 to 4 carbon atoms, and B and D Are each independently 1,4-phenylene group, 2 or 3-fluoro-1,4-phenylene group, 2,3-difluoro-1,4-phenylene group, 3,5-difluoro-1,4-phenylene Group, 2,6-difluoro-1,4-phenylene group, 2 or 3-methyl-1,4-phenylene group, 2,3-dimethyl-1,4-phenylene group, 3,5-dimethyl-1,4 Represents a -phenylene group, a 2,6-dimethyl-1,4-phenylene group or a trans-1,4-cyclohexylene group, r and s each independently represent 0 or 1, and Z ² and Z ³ represent Each independently represents a single bond, —CH ₂ —CH ₂ —, —CH═CH—, —COO— or —OCO—, wherein X ⁴ , X ⁵ , X ⁶ and X ⁷ are each independently H , it preferably contains a compound represented by F or CH _3.), Compound in crystal composition content of (V) is preferably 5 to 60 wt%, more preferably from 5 to 40 mass%, particularly preferably 5 to 30 mass%.
Preferable examples of the general formula (V) are compounds represented by the general formulas (Va) to (Vm).

（式中、R⁷及びR⁸は先述のとおりである。）
更に、本発明の液晶組成物は、一般式(VI)

(In the formula, R ⁷ and R ⁸ are as described above.)
Furthermore, the liquid crystal composition of the present invention has the general formula (VI)

（式中、R⁹及びR¹⁰は、炭素原子数1〜5のアルキル基又はアルコキシル基、炭素原子数2〜4のアルケニル基又は炭素原子数3〜4のアルケニルオキシ基を表し、Eは、1,4-フェニレン基、2又は3-フルオロ-1,4-フェニレン基、2,3-ジフルオロ-1,4-フェニレン基、3,5-ジフルオロ-1,4-フェニレン基、2,6-ジフルオロ-1,4-フェニレン基、2又は3-メチル-1,4-フェニレン基、2,3-ジメチル-1,4-フェニレン基、3,5-ジメチル-1,4-フェニレン基、2,6-ジメチル-1,4-フェニレン基又はトランス-1,4-シクロヘキシレン基を表し、Z⁴は、単結合、-CH₂-CH₂-、-CH=CH-、-COO-又は-OCO-を表す。）で表される化合物を含有することが好ましく、液晶組成物中における化合物(VI)の含有量は、粘度を低く抑え速い応答速度を得ること、急峻な電気-光学特性を得ることなどの理由から、3〜20質量%が好ましく、3〜15質量%が更に好ましく、3〜10質量%が特に好ましい。
一般式(VI)で表される化合物の好ましい例は、一般式(VI-a)又は(VI-b)で表される化合物である。

(Wherein R ⁹ and R ¹⁰ represent an alkyl group or alkoxyl group having 1 to 5 carbon atoms, an alkenyl group having 2 to 4 carbon atoms, or an alkenyloxy group having 3 to 4 carbon atoms, and E is 1,4-phenylene group, 2 or 3-fluoro-1,4-phenylene group, 2,3-difluoro-1,4-phenylene group, 3,5-difluoro-1,4-phenylene group, 2,6- Difluoro-1,4-phenylene group, 2 or 3-methyl-1,4-phenylene group, 2,3-dimethyl-1,4-phenylene group, 3,5-dimethyl-1,4-phenylene group, 2, Represents a 6-dimethyl-1,4-phenylene group or trans-1,4-cyclohexylene group, Z ⁴ represents a single bond, —CH ₂ —CH ₂ —, —CH═CH—, —COO— or —OCO; The compound (VI) content in the liquid crystal composition is preferably low, the viscosity is kept low, a fast response speed is obtained, and steep electro-optical characteristics are obtained. For reasons such as 3-20% by mass is preferred Ku, more preferably 3 to 15 mass%, particularly preferably from 3 to 10% by weight.
A preferred example of the compound represented by the general formula (VI) is a compound represented by the general formula (VI-a) or (VI-b).

（式中、R⁹及びR¹⁰は先述のとおりである。）

(In the formula, R ⁹ and R ¹⁰ are as described above.)

  The present invention is characterized in that it contains the compounds represented by the general formula (I) and the general formula (II) at the same time, but preferably further contains a compound represented by the general formula (III), It is particularly preferable to simultaneously contain compounds selected from the formulas (IV) to (VI) in order to obtain more excellent effects of the present invention.

  In order to obtain the effect of the present invention, a particularly preferred liquid crystal composition comprises 5 to 15% by mass of the compound represented by the general formula (I), 5 to 20% by mass of the compound represented by the general formula (II), and A liquid crystal composition containing 15 to 25% by mass of the compound represented by the general formula (III).

  In addition to the compounds represented by the general formulas (I) to (VI), ordinary nematic liquid crystals, smectic liquid crystals, cholesteric liquid crystals, chiral agents and the like can be used for the liquid crystal composition used in the present invention. Representative examples of chiral agents include cholesteryl nonanate, C-15, CB-15, S-811, R-811 and the like.

(About physical properties of liquid crystal composition)
The nematic phase-isotropic liquid phase transition temperature (hereinafter referred to as Tni) of the liquid crystal composition used in the liquid crystal display device of the present invention is preferably low in order to increase the contrast of STN-LCD. If Tni is too low, the display disappears in an atmosphere of high temperature. Therefore, it is preferably 75 ° C to 130 ° C, more preferably 80 ° C to 120 ° C, more preferably 90 ° C. A temperature of ˜110 ° C. is particularly preferred. Refractive index anisotropy (Δn) is 0.12 to 0.24 for reasons such as keeping the solid phase-nematic phase transition temperature low, obtaining a fast response speed while keeping viscosity low, and steep electro-optical properties. However, 0.13-0.21 is more preferable, and 0.13-0.18 is particularly preferable.
The STN-LCD of the present invention has improved steepness γ compared to the conventional STN-LCD. For this reason, the STN-LCD of the present invention has a high contrast. Specifically, conditional expression (i)

（但し、Vsatは、セル厚d(μm)のSTN-LCDを構成した時の25℃での飽和電圧(V)、すなわち、透過率が10%のときの駆動電圧である。セル厚d(μm)は、Δn・d=0.90の関係式により決定。印加駆動波形は100Hz矩形波。Vthは、セル厚d(μm)のSTN液晶表示素子(STN-LCD)を構成したときの25℃での閾値電圧(V)、すなわち、透過率が90%のときの駆動電圧である。セル厚d(μm)は、Δn・d=0.90の関係式により決定。印加駆動波形は100Hz矩形波。）で表される急峻性γを満たしており、高いコントラストであることを特徴とするSTN-LCDを作製することができる。
更に、本発明のSTN-LCDは低い閾値電圧を有しているという特徴がある。具体的には、条件式(ii)

(However, Vsat is a saturation voltage (V) at 25 ° C. when a STN-LCD having a cell thickness d (μm) is constructed, that is, a drive voltage when the transmittance is 10%. Cell thickness d ( μm) is determined by the relational expression of Δn · d = 0.90, the applied drive waveform is a 100 Hz rectangular wave, and Vth is 25 ° C when a STN liquid crystal display element (STN-LCD) with a cell thickness d (μm) is constructed Threshold voltage (V), that is, a driving voltage when the transmittance is 90% .The cell thickness d (μm) is determined by the relational expression Δn · d = 0.90. The applied driving waveform is a 100 Hz rectangular wave.) An STN-LCD characterized by satisfying the steepness γ expressed by ## EQU2 ## and high contrast can be manufactured.
Furthermore, the STN-LCD of the present invention is characterized by having a low threshold voltage. Specifically, conditional expression (ii)

（但し、Vthはセル厚d(μm)のSTN液晶表示素子(STN-LCD)を構成したときの25℃での閾値電圧(V)、すなわち、透過率が90%のときの駆動電圧である。セル厚d(μm)は、Δn・d=0.90の関係式により決定。印加駆動波形は100Hz矩形波。）で表される閾値電圧Vthを満たすSTN-LCDを作製することができ、好ましくは1.95V以下の閾値電圧を有するSTN-LCDを作成することができる。すなわち、駆動電圧が低いため、携帯情報端末に求められている長時間の使用に対する改善効果が非常に大きい。

(However, Vth is a threshold voltage (V) at 25 ° C. when a STN liquid crystal display element (STN-LCD) having a cell thickness d (μm) is constructed, that is, a drive voltage when the transmittance is 90%. The cell thickness d (μm) is determined by the relational expression of Δn · d = 0.90. The applied drive waveform is a 100 Hz rectangular wave.) An STN-LCD satisfying the threshold voltage Vth represented by An STN-LCD with a threshold voltage of 1.95V or less can be created. That is, since the drive voltage is low, the improvement effect for a long time use required for the portable information terminal is very large.

  When the liquid crystal display device using the liquid crystal composition of the present invention is a super twisted nematic (STN) liquid crystal display device, the twist angle is preferably 180 ° to 270 °, more preferably 220 ° to 260 °, more preferably 230 ° to 250 ° is particularly preferred.

From the above, the STN-LCD of the present invention realizes high contrast and low drive voltage at the same time, 1/32 to 1/480 Duty required for portable information terminals, more preferably 1/64 to 1 / 240Duty time-division drive has very good display characteristics. Further, since the drive voltage is low, the improvement effect for long-term use required for the portable information terminal is very large.
Note that the STN-LCD of the present invention may be any display system such as a transmissive type, a transflective type, and a reflective type.

  EXAMPLES Hereinafter, although an Example is given and this invention is explained in full detail, this invention is not limited to these Examples. Further, “%” in the compositions of the following examples and comparative examples means “mass%”.

In the examples, the measured characteristics are as follows.
Tni: Nematic phase-isotropic liquid phase transition temperature (° C)
Tn: Solid phase or smectic phase-nematic phase transition temperature (° C)
Δn: refractive index anisotropy at 25 ° C
Vth: Threshold at 25 ° C when an STN liquid crystal display element (STN-LCD) with cell thickness d (μm) is constructed
Value voltage (V), that is, a drive voltage when the transmittance is 90%.
The cell thickness d (μm) is determined by the relational expression Δn · d = 0.90.
The applied drive waveform is a 100Hz rectangular wave.
Vsat: Saturation voltage (V) at 25 ° C when STN-LCD with cell thickness d (μm) is constructed.
It represents the driving voltage when the transmittance is 10%.
The cell thickness d (μm) is determined by the relational expression Δn · d = 0.90.
The applied drive waveform is a 100Hz rectangular wave.
γ: Steepness at 25 ° C γ = Vsat / Vth
τ: Response speed (ms) when injected into a 240 ° STN-LCD with a cell thickness of 5.7 μm.
The measurement was performed at 1/128 Duty.

  The STN-LCD was manufactured as follows. A chiral liquid "S-811" (Merck) is added to the nematic liquid crystal composition to prepare a mixed liquid crystal, and an organic film of "Sunever 150" (Nissan Chemical) is rubbed on the opposing flat transparent electrode. Then, it was injected into an STN-LCD with a twist angle of 240 ° on which an alignment film was formed. The chiral agent was added so that the natural helical pitch P of the mixed liquid crystal and the cell thickness d of the display cell were d / P = 0.50 by adding the chiral agent.

The following abbreviations are used in the description of compounds.
-Terminal n (number): -C _n H _{2n + 1} ndm-: C _n H _{2n + 1} -CH = CH- (CH ₂ ) _m-1-
-T-: -C≡C- -ndm:-(C _n H _{2n + 1} -CH = CH- (CH ₂ ) _m-1 )
-F: -F -On: -OC _n H _{2n + 1}
-VO-: -COO- -CN: -C≡N
-Z-: -CH = NN = CH- -CF ₂ O-: -CF ₂ -O-

例えば、以下に示すように略号を用いる。

For example, abbreviations are used as shown below.

(Example 1, Example 2 and Comparative Example 1)
Liquid crystal composition No. 1 (Example 1), No. 2 (Example 2) and liquid crystal composition M1 (Comparative Example 1) were prepared. In addition, STN-LCDs using these liquid crystal compositions were prepared. Table 1 shows the composition ratios of these liquid crystal compositions and the measured characteristics of STN-LCDs using the liquid crystal compositions.

  Liquid crystal compositions No. 1 (Example 1) and No. 2 (Example 2) are the general formulas (Ia), (Ib), (Ic), (II-a) and (III), which are combinations of the present invention. In addition to the compound represented by -a), the compounds represented by the general formulas (IV-a), (IV-b), (Va), (Vb) and (Vm) are contained. Comparing the characteristics with the liquid crystal composition M1 (Comparative Example 1), the STN-LCD of Example 1 has a steep electro-optical characteristic (steepness) although it has a threshold voltage lower than that of Comparative Example 1. STN-LCD with high contrast can be developed. In addition, the STN-LCD of Example 2 also simultaneously satisfies a low threshold voltage (low drive voltage) and steep electro-optical characteristics (high contrast).

(Example 3, Example 4 and Comparative Example 2)
Liquid crystal composition No. 3 (Example 3), No. 4 (Example 4) and liquid crystal composition M2 (Comparative Example 2) were prepared. In addition, STN-LCDs using these liquid crystal compositions were prepared. Table 2 shows the composition ratios of these liquid crystal compositions and the measured characteristics of STN-LCDs using the liquid crystal compositions.

Liquid crystal compositions No. 3 (Example 3) and No. 4 (Example 4) are the general formulas (Ia), (Ib), (Ic), (II-a) and (III) which are combinations of the present invention. In addition to the compound represented by -a), it contains compounds represented by general formulas (IV-a), (IV-b), (Va), (Vb) and (VI-a). Comparing the characteristics with the liquid crystal composition M2 (Comparative Example 2), the STN-LCD of Example 3 has a steep electro-optical characteristic (though it has a low threshold voltage as in Comparative Example 2). Steepness γ) can be obtained. In other words, it has become possible to develop an STN-LCD that simultaneously satisfies a low threshold voltage (low drive voltage) and steep electro-optical characteristics (high contrast). In addition, the liquid crystal composition of Example 4 satisfies both a low threshold voltage (low driving voltage) and steep electro-optical characteristics (high contrast) at the same time, and further has a higher response speed than Comparative Example 2.

Claims (8)

As the first component, the general formula (I)

(In the formula, R ¹ represents an alkyl group having 2 to 5 carbon atoms or an alkenyl group having 4 to 5 carbon atoms.) The compound represented by 1 type or 2 types or more is used as a second component. General formula (II)

(Wherein R ² and R ³ represent an alkyl group having 2 to 5 carbon atoms or an alkenyl group having 4 to 5 carbon atoms) containing one or more compounds represented by A liquid crystal composition characterized by the above. The liquid crystal composition according to claim 1, comprising 5 to 25% by mass of the compound represented by the general formula (I) and 5 to 25% by mass of the compound represented by the general formula (II). Further, as the third component, the general formula (III)

(In the formula, R ⁴ represents an alkyl group having 2 to 5 carbon atoms, an alkenyl group having 2 to 4 carbon atoms, and X ¹ represents a hydrogen atom or a fluorine atom.) The liquid crystal composition according to claim 2, comprising two or more kinds, the content of which is 5 to 30% by mass. The liquid crystal composition according to claim 1, wherein a nematic phase-isotropic liquid phase transition temperature is 75 ° C. to 130 ° C., and a refractive index anisotropy (Δn) is 0.12 to 0.24. A liquid crystal display element using the liquid crystal composition according to claim 1. The liquid crystal display element according to claim 5, wherein the twist angle is 180 to 270 °. Steepness γ is (i)

(However, Vsat is a saturation voltage (V) at 25 ° C. when a STN-LCD having a cell thickness d (μm) is constructed, that is, a drive voltage when the transmittance is 10%. Cell thickness d ( μm) is determined by the relational expression of Δn · d = 0.90, the applied drive waveform is a 100 Hz rectangular wave, and Vth is 25 ° C. when a STN liquid crystal display element (STN-LCD) with a cell thickness d (μm) is constructed. Threshold voltage (V), that is, a driving voltage when the transmittance is 90% .The cell thickness d (μm) is determined by the relational expression Δn · d = 0.90. The applied driving waveform is a 100 Hz rectangular wave.) The liquid crystal display element of Claim 6 satisfy | filling the conditional expression represented by these. The threshold voltage Vth is (ii)

(However, Vth is a threshold voltage (V) at 25 ° C. when a STN liquid crystal display element (STN-LCD) having a cell thickness d (μm) is constructed, that is, a drive voltage when the transmittance is 90%. 8. The liquid crystal display element according to claim 6, wherein the cell thickness d (μm) is determined by a relational expression of Δn · d = 0.90. The applied drive waveform is a 100 Hz rectangular wave.