TWI886127B - Cholesterol liquid crystal composition and liquid crystal display element - Google Patents

Abstract

The present invention provides a cholesterol liquid crystal composition having positive dielectric anisotropy and a liquid crystal display element using the same, wherein the cholesterol liquid crystal composition contains: a compound represented by general formula (1-1), a compound represented by general formula (1-2), a compound represented by general formula (2-1) as a second component and a second component with neutral dielectricity, and at least two optically active substances whose chiral pitch lengths have temperature dependencies different from each other.

Description

Cholesterol liquid crystal composition and liquid crystal display element

This application invention relates to a cholesterol liquid crystal composition useful as a display element material and a display element using the same.

Liquid crystal display elements using cholesterol (chiral nematic phase) liquid crystal compositions that impart twisted alignment to the liquid crystal phase by adding optically active compounds to the liquid crystal composition have bistability, and can therefore be used in electronic books, electronic labels, display panels, etc. that require extremely low power consumption. The bistability of cholesterol liquid crystal can be achieved by switching the planar state and the focal conic state by applying a pulse voltage. Each state of the planar and focal conic can be maintained even when the voltage is off, so the bistability is also called memory.

The liquid crystal display element using cholesterol liquid crystal shows a specific selective reflection wavelength depending on the chiral pitch when the cholesterol helical axis is perpendicular to the substrate (planar state). The selective reflection wavelength (λ) is determined by the product of the average refractive index (n) and the chiral pitch (P) of the liquid crystal composition. Therefore, when the refractive index of the liquid crystal composition is fixed, the desired selective reflection wavelength can be obtained by adjusting the concentration of the chiral compound and adjusting the chiral pitch P. The half-width of the selective reflection light (△λ) at this time is proportional to the product of the refractive index anisotropy (△n=ne-no) and the chiral pitch of the liquid crystal. However, in order to achieve a bright display, a certain degree of wide half-width is required, so a liquid crystal composition with a large △n must be used. In the above case, the average refractive index of the liquid crystal composition also increases, so in order to adjust to the desired λ, it is necessary to further add a chiral agent to shorten P, but if the amount of chiral compound added is excessively increased, problems such as deterioration of the liquid crystal temperature range of the host liquid crystal and increased viscosity will occur. That is, for the design of cholesterol liquid crystal, a chiral compound that induces a high liquid crystal twisting force of the chiral pitch and has little effect on the host liquid crystal is required, and a host liquid crystal composition with excellent compatibility with such a compound and high △n is required. Furthermore, it is required to have a sufficiently large dielectric anisotropy (△ε) that can be driven by a low voltage as a liquid crystal display element, and good storage properties such as no precipitation in a low temperature environment. For example, Patent Document 1 discloses several cholesterol liquid crystal compositions to solve the above problems.

The chiral pitch length of cholesterol liquid crystal depends on the type or added concentration of the chiral compound, and can be expressed by P=1/(β.c). Here, c is the concentration of the chiral compound in the cholesterol liquid crystal composition, and β is the force of the chiral compound to twist the liquid crystal composition, called the helical twisting power (HTP), which can be calculated using the formula HTP=n/(λ×0.01×c). Here, n is the average refractive index of the liquid crystal composition. The HTP can be used to provide the desired pitch to the liquid crystal composition.

Chiral compounds generally reduce the temperature range of the liquid crystal phase and increase the viscosity. Furthermore, it is known that the chiral pitch length generated by adding chiral compounds has temperature dependence. For example, the compound represented by formula (Chiral-1), which is a chiral compound with asymmetric carbon, shows the following characteristics: when added to a normal liquid crystal composition, the pitch length increases as the temperature changes from room temperature to high temperature, and the change also varies greatly depending on the liquid crystal composition that serves as the host.

Due to the temperature dependence of the chiral pitch of cholesterol liquid crystal, the cholesterol liquid crystal composition has the following disadvantages: due to the change of the ambient temperature when driven as an element, the selected reflection wavelength λ shifts and the color changes. That is, considering the influence on the physical properties or stability of the main liquid crystal composition and the ambient temperature in which it is used, the chiral compound and the main liquid crystal composition must be selected in a way that does not cause the above disadvantages as much as possible. However, there is no specific main liquid crystal composition that satisfies the various characteristics required of the cholesterol liquid crystal composition, that is, large dielectric anisotropy, wide operating temperature range, stability at low temperature, desired selective reflection wavelength, high reliability against external light, etc., and can solve the above disadvantages at the same time.

[Prior art literature]

[Patent Literature]

[Patent document 1] Japanese Patent Publication No. 2010-275463

The problem to be solved by the present invention is to provide a cholesterol liquid crystal composition having high dielectric anisotropy (△ε) and refractive index anisotropy (△n), a wide temperature range of cholesterol liquid crystal, stability at low temperatures, high reliability to external stimuli such as heat or light, and small temperature variation in the selected reflection wavelength. In addition, a liquid crystal display element is provided, which uses such cholesterol liquid crystal, has small color variation relative to temperature, has sufficient brightness, a wide operating temperature range, low driving voltage and high reliability.

As a result of diligent research, the inventors and others found that the above problem can be solved by the following cholesterol liquid crystal composition, thereby completing the invention of the present application. The cholesterol liquid crystal composition has positive dielectric anisotropy and includes: a first component with positive dielectricity, a second component with neutral dielectricity, and a third component containing at least two optically active substances with different temperature dependencies of chiral pitch lengths, and contains one or more compounds represented by general formula (1-1) as the first component, one or more compounds represented by general formula (1-2) as the first component, and one or more compounds represented by general formula (2-1) as the second component.

( ^R1 and ^R2 independently represent an alkyl group having 1 to 7 carbon atoms, an alkoxy group having 1 to 7 carbon atoms, or an alkenyl group having 2 to 7 carbon atoms; Ring A represents a 1,4-cyclohexylene group or a 1,4-phenylene group; and ^Y1 to ^Y5 independently represent a hydrogen atom or a fluorine atom.

R ³ and R ⁴ independently represent an alkenyl group having 2 to 7 carbon atoms or an alkenyloxy group, Y ⁶ to Y ¹¹ independently represent a hydrogen atom, a fluorine atom or a methyl group, Z ¹ represents a single bond, -COO- or -CH ₂ CH ₂ -, and a, b and c independently represent 0 or 1).

The present invention can provide a cholesterol liquid crystal composition having more excellent properties than existing cholesterol liquid crystals from the perspective of combining multiple physical properties. That is, it can provide a cholesterol liquid crystal composition having more excellent physical properties such as temperature change of selective reflection wavelength, dielectric anisotropy (△ε) and refractive index anisotropy (△n), cholesterol liquid crystal temperature range, low temperature stability, stability to external stimuli such as heat or light, etc. In addition, especially in the practical temperature range of 0°C to 50°C, the chiral pitch of the liquid crystal composition of the present invention hardly changes, so the selective reflection wavelength dependent on the chiral pitch also does not change. As a result, it is possible to provide a high-quality cholesterol liquid crystal display element that satisfies various characteristics of the cholesterol liquid crystal display element that have been previously required, and furthermore, the color of the reflection state does not substantially change.

The present invention is described in detail below.

The so-called "positive dielectric property" of a liquid crystal compound means that the Δε of the compound is above +3.0, and the so-called "neutral dielectric property" means that the Δε of the compound is -1.5~+1.5. The Δε of each compound can be obtained by extrapolating the Δε value obtained when a certain amount of each compound is added to a certain liquid crystal composition. In addition, "%" in the present invention refers to mass % unless otherwise specified.

The liquid crystal composition of the present invention contains a compound with positive dielectricity as the first component.

In the general formula (1-1), ^Y1 and ^Y2 represent hydrogen atoms or fluorine atoms, preferably both are hydrogen atoms. ^Y3 represents hydrogen atoms or fluorine atoms, preferably hydrogen atoms. a represents 0 or 1, and it is also preferred to use a bicyclic compound in which a is 0 and a tricyclic compound in which a is 1 in combination.

In the general formula (1-2), ^Y4 and ^Y5 represent hydrogen atoms or fluorine atoms, and b represents 0 or 1. Preferably, b is 0 and ^Y4 and ^Y5 are both fluorine atoms, or b is 1 and ^Y4 and ^Y5 are both hydrogen atoms. In addition, it is also preferred to use a bicyclic compound in which b is 0 and a tricyclic compound in which b is 1 in combination.

In the general formula (1-1) and the general formula (1-2), ^R1 and ^R2 are each independently preferably an alkyl group having 1 to 7 carbon atoms, and more preferably an alkyl group having 1 to 5 carbon atoms.

The preferred content of the compounds represented by general formula (1-1) and general formula (1-2) is 40% to 75%, more preferably 45% to 70%, and particularly preferably 48% to 68%. The compound represented by general formula (1-1) has a large △ε and a moderate △n, and the compound represented by general formula (1-2) has a large △ε and a high △n. By using these together, it is possible to give the composition very large △ε and △n while maintaining the liquid crystal temperature range or low temperature stability.

In addition, the compound represented by the general formula (1-3) may be added for the purpose of increasing Δε and Δn.

( ^R7 represents an alkyl group having 1 to 7 carbon atoms, an alkoxy group having 1 to 7 carbon atoms, or an alkenyl group having 2 to 7 carbon atoms, ^Y12 to ^Y23 independently represent a hydrogen atom or a fluorine atom, ^X1 represents a fluorine atom, a chlorine atom, -CN, _-NCS , _-CF3 or _-OCF3 , and Z3 ^{and Z4} independently represent a _single bond, _-CH2CH2- , -COO-, _-OCO- , -CH2O-, _-OCH2- , -CF2O-, _-OCF2- or -C≡C-).

When the liquid crystal composition contains the compound represented by the general formula (1-3), the content of the compound represented by the general formula (1-3) is preferably 1% or more, and more preferably 5% or more.

In addition, a compound represented by the general formula (1-4) may be further added. The compound represented by the general formula (1-4) has a moderate Δε and a moderate Δn. By using these together, the liquid crystal temperature range or low-temperature stability can be improved.

[Chemistry 4]

(R ⁹ represents an alkyl group having 1 to 7 carbon atoms, an alkoxy group having 1 to 7 carbon atoms, or an alkenyl group having 2 to 7 carbon atoms; X ² represents a fluorine atom, a chlorine atom, -CN, -NCS, -CF ₃ , or -OCF ₃ ; Ring B and Ring C independently represent a 1,4-cyclohexylene group or a 1,4-phenylene group in which the hydrogen atom may be substituted by a fluorine atom; Z ⁵ represents a single bond, -COO-, -CH ₂ CH ₂ -, -CH=CH-, -FC=CF-, or -C=NN=C-; d represents 1, 2, or 3; when there are a plurality of Ring B and Z ^5, they may be the same or different; and in the general formula (1-4), compounds represented by the general formula (1-1) and the general formula (1-3) are excluded).

Ring C in the general formula (1-4) is preferably a 1,4-phenylene group in which the hydrogen atom may be substituted by a fluorine atom, preferably a 3-fluoro-1,4-phenylene group or a 3,5-difluoro-1,4-phenylene group.

In the general formula (1-4), at least one of the rings B is preferably a 1,4-cyclohexylene group, and the group directly bonded to R ⁹ is preferably a 1,4-cyclohexylene group.

The preferred total content of the first component is 40% to 80%, more preferably 45% to 75%, and most preferably 50% to 70%.

As compounds represented by general formula (1-1), formula (1-2), formula (1-3) and formula (1-4), preferred examples are compounds represented by the following general formula (1-1-a) to general formula (1-1-d), general formula (1-2-a) to general formula (1-2-d), general formula (1-3-a) to general formula (1-3-f) and general formula (1-4-a) to general formula (1-4-i).

[Chemistry 5]

[Chemistry 6]

(wherein, ^R1 represents the same meaning as ^R1 in formula (1-1), ^R2 represents the same meaning as ^R2 in formula (1-2), and ^R7 represents the same meaning as ^R7 in formula (1-3)).

[Chemistry 7]

(wherein, ^R9 represents an alkyl group having 1 to 7 carbon atoms, an alkoxy group having 1 to 7 carbon atoms, or an alkenyl group having 2 to 7 carbon atoms).

The liquid crystal composition of the present invention contains a dielectrically neutral compound as the second component.

In the general formula (2-1), c is 0 or 1, preferably 0. ^{Y 6} to Y ¹¹ are preferably all hydrogen atoms. ^{R 3} and R ⁴ are independently alkenyl or alkenyloxy groups having 2 to 7 carbon atoms, preferably alkenyl having 2 to 7 carbon atoms, and more preferably a group represented by any one of the following formulas (R1) to (R5). (The black dots in each formula are bonding points, representing the carbon atoms in the ring A or the substituted 1,4-phenylene group in the formula).

The preferred content of the compound represented by general formula (2-1) is 1% to 35%, more preferably 2% to 30%, and particularly preferably 3% to 25%. The compound represented by general formula (2-1) has the effect of suppressing the viscosity of the liquid crystal composition to a low level. In addition, it can not only provide a high △n to the composition while adjusting the upper limit temperature of the liquid crystal phase, but also show extremely good solubility with the first component.

If a large amount of compounds in which Y ⁶ to Y ¹¹ in the general formula (2-1) are hydrogen atoms are used, the viscosity of the composition can be suppressed to a low level. If a compound in which at least one atom is substituted with a methyl group or a fluorine atom is used, the stability of the liquid crystal phase can be further improved.

As compounds represented by general formula (2-1), preferred examples are the following general formulas (2-1-a) to (2-1-e).

[Chemistry 9]

(wherein, ^R3 represents the same meaning as ^R3 in formula (2-1), and ^R4 represents the same meaning as ^R4 in formula (2-1)).

In addition, a compound represented by general formula (2-2) may be added as a second component for the purpose of reducing viscosity or expanding the liquid crystal temperature range.

( ^R5 and ^R6 independently represent an alkyl group having 1 to 7 carbon atoms, an alkoxy group having 1 to 7 carbon atoms, or an alkenyl group having 2 to 7 carbon atoms, Ring B and Ring C independently represent a 1,4-cyclohexylene group or a 1,4-phenylene group in which the hydrogen atom may be substituted by a fluorine atom, ^Z2 represents a single bond, -COO-, _-CH2CH2- , _-CH =CH-, -FC=CF-, or -C=NN=C-, d represents 1, 2, or 3, and when there are plural Ring B and ^Z2, they may be the same or different).

As compounds represented by general formula (2-2), preferred examples are the following general formulas (2-2-a) to (2-2-k).

(wherein, R ⁵ has the same meaning as R ⁵ in formula (2-2), and R ⁶ has the same meaning as R ⁶ in formula (2-2)).

A better example of the compound represented by the general formula (2-2) is a compound represented by the formula (2-2-a), the formula (2-2-b), the formula (2-2-c) or the formula (2-2-d), and a particularly preferred compound is a compound selected from the group of compounds in which R ⁵ is an alkenyl group in the formula (2-2-a) and/or the formula (2-2-d).

The preferred content of the compound represented by general formula (2-2) is 3% or more, more preferably 5% or more, and particularly preferably 7% or more.

In addition, the compound represented by the general formula (2-3) as the second component can not only provide a high △n to the composition while adjusting the viscosity of the liquid crystal composition or the upper limit temperature of the liquid crystal phase, but also show extremely good solubility with the first component.

If a large amount of compounds in which Y ²⁴ to Y ²⁹ in the general formula (2-3) are hydrogen atoms are used, the viscosity of the composition can be suppressed to a low level. If a compound in which at least one atom is substituted with a methyl group or a fluorine atom is used, the stability of the liquid crystal phase can be further improved.

(when c is 0, ^R7 and ^R8 independently represent an alkyl group having 1 to 7 carbon atoms or an alkoxy group having 1 to 7 carbon atoms; when c is 1, ^R7 and ^R8 independently represent an alkyl group having 1 to 7 carbon atoms, an alkoxy group having 1 to 7 carbon atoms, or an alkenyl group or alkenyloxy group having 2 to 7 carbon atoms; Ring A represents a 1,4-cyclohexylene group or a 1,4-phenylene group in which the hydrogen atom may be substituted by a fluorine atom or a methyl _group ; ^Y24 to ^Y29 independently represent a hydrogen atom, a fluorine atom or a methyl group; ^Z1 represents a single bond, -COO- or _-CH2CH2- ; and c represents 0 or 1).

As compounds represented by general formula (2-3), preferred examples are the following general formulas (2-3-a) to (2-3-e).

(wherein, ^R7 has the same meaning as ^R7 in formula (2-3), and ^R8 has the same meaning as ^R8 in formula (2-3)).

The preferred total content of the compounds represented by general formula (2-3) is 10% to 50%, more preferably 15% to 45%, and particularly preferably 20% to 40%.

The preferred total content of the second component is 20% to 55%, more preferably 25% to 50%, and particularly preferably 30% to 45%.

The liquid crystal composition of the present invention contains at least two optically active substances (chiral compounds) with different temperature dependencies of chiral pitch length as the third component. These compounds preferably have a positive chiral pitch temperature dependency on the one hand and a negative chiral pitch temperature dependency on the other hand at the usual temperature of the liquid crystal display element, preferably in the range of 0°C to 50°C. The total content of the third component varies depending on the target selected reflection wavelength, preferably less than 10%, more preferably less than 8%, and particularly preferably less than 6%. There is no particular restriction on the preferred lower limit, but in the case where the liquid crystal torsional force is significantly large, the amount of the third component added to the composition is trace, and there is a situation where the selected reflection wavelength or its temperature dependency deviates due to a slight deviation in the mixing ratio. Although it will be affected by the weighing accuracy of the manufacturing equipment, if the concentration of the third component is approximately 0.1% or more, the composition can be manufactured with high precision regardless of the manufacturing scale.

As a chiral compound, it is preferred to contain one or more compounds represented by the general formula (3).

( ^R8 and ^R9 independently represent an alkyl group having 1 to 7 carbon atoms, an alkoxy group having 1 to 7 carbon atoms, or an alkenyl group having 2 to 7 carbon atoms, Ring D, Ring E, Ring F, and Ring G independently represent 1,4-cyclohexyl or 1,4-phenylene, ^Z5 and ^Z6 independently represent a single bond, -OCO-, or -COO-, and e and f independently represent 0, 1, or 2. When there are multiple Ring D, Ring G, ^Z5 , and ^Z6 , they may be the same or different).

As the compound represented by the general formula (3), preferred examples are the compounds represented by the following formulas (3-1) to (3-4).

The compounds represented by formula (3-1) and formula (3-2) usually have a positive temperature dependence of the chiral pitch length. The compounds represented by formula (3-3) and formula (3-4) usually have a negative temperature dependence of the chiral pitch length. In addition, the compounds represented by formula (3-1) and formula (3-3) are dextrorotatory substances, and the compounds represented by formula (3-2) and formula (3-4) are levorotatory substances. The following table provides a combination of preferred chiral compounds in the present invention. Dextrorotatory and levorotatory can be appropriately selected according to the required specifications of the display element. When adjacent to cholesterol liquid crystal regions adjusted to different selected reflection wavelengths, it is preferred to make the respective optical rotations opposite in advance for the purpose of avoiding color mixing.

The preferred physical property values of the cholesterol liquid crystal composition of the present invention are recorded. In addition, △n and △ε are the values of the main liquid crystal composition before adding the chiral compound.

The preferred range of Δn is 0.10 to 0.40, more preferably 0.15 to 0.35, and particularly preferably 0.20 to 0.30. The preferred range of Δε is 10 to 50, more preferably 15 to 45, and particularly preferably 20 to 40. The preferred range of T _NI is 60°C to 120°C, more preferably 70°C to 110°C, and particularly preferably 80°C to 110°C.

The lower the flow viscosity, the better. There is no special lower limit. If it is below 100mPa.s, a sufficient response speed can be achieved in practical use.

The cholesterol liquid crystal composition of the present invention may further contain additives as needed. For example, ultraviolet (UV) absorbers or antioxidants, hindered amine light stabilizers (HALS), etc. may be added for the purpose of improving stability to external stimuli. The structure is not particularly limited, and various compounds commonly known to be added to liquid crystal compositions, such as benzotriazole-based UV absorbers or hindered phenol-based antioxidants, may be used. In addition, various polymerizable compounds for the purpose of fixing the cholesterol liquid crystal phase may also be included. In the above case, the polymerizable compound is preferably a substance that exhibits liquid crystal properties in the stage before curing. It can also be polymerized and cured by irradiating it with ultraviolet rays or heating it, so that it can be made into a layer that has no fluidity and becomes a state in which the alignment state does not change due to external forces.

[Implementation example]

In the embodiment, compounds other than the optically active substance as the third component are prepared to prepare a nematic phase liquid crystal composition as the main liquid crystal, and various physical property values are measured.

After that, a compound containing a third component is prepared to produce cholesterol liquid crystal.

Regarding the measurement of the selective reflection wavelength, a cell with a gap (GAP) of 3 μm was made using a substrate with a horizontal alignment film, and after injecting liquid crystal, it was heated to above _TNI and slowly cooled to room temperature. After that, the cell surface was pressed with a finger to change to a planar alignment. The temperature dependence of the selective reflection wavelength was measured using the cell.

LCD-5200 (manufactured by Otsuka Electronics) was used for the measurement. The incident light was made to enter from a direction inclined 30° relative to the normal line of the cell, and the selective reflected light in the normal direction was received.

The compositions of the following examples and comparative examples contain each compound in the proportions in the table, and the content is recorded in "mass %". The following abbreviations are used to record the compounds in the examples.

(Ring structure)

Unless otherwise specified, the trans isomer is used.

(Side chain structure and connection structure)

(Physical property value)

Transparent point (℃): The temperature at which the composition changes to the isotropic phase (T _NI )

Melting point (℃): The temperature at which the composition returns from the solid phase to the nematic phase

△n: Refractive index anisotropy of the main liquid crystal composition at 25°C and 589nm

△ε: Dielectric anisotropy of the host liquid crystal composition at 25°C and 1kHz

η(mPa.s): Flow viscosity of the main liquid crystal composition at 20°C

(Implementation Example 1)

The compositions of Example 1 and Comparative Example 1 are shown in Table 3.

Prepare compositions other than the third component in the table below, prepare nematic phase liquid crystal compositions (main liquid crystal compositions), and measure physical property values. In addition, add a compound as a third component of a chiral compound to these main liquid crystal compositions, and prepare a cholesterol liquid crystal composition in such a way that the selective reflection wavelength at 25°C is about 560nm.

The physical property values of each component and the temperature dependence of the selected reflection wavelength are shown below.

Compared with Comparative Example 1, the main liquid crystal composition of Example 1 except the third component has the same _TNI point, low melting point (= wide liquid crystal temperature range), small viscosity (η), large dielectric anisotropy (△ε), and can be driven with a lower voltage.

In addition, it can be seen that the temperature dependence of the selected reflection wavelength of the unit containing the third component cholesterol liquid crystal composition is small, and it is more suitable as a cholesterol material for display elements.

Here, for the cells using the cholesterol liquid crystal compositions of Example 1 and Comparative Example 1, the temperature was changed from 0°C to 50°C, and the color change was visually observed. As a result, the cell injected with the composition of Example 1 did not change, while the cell injected with the composition of Comparative Example 1 changed color with the temperature rise. Furthermore, the low-temperature storage stability of the compositions of Example 1 and Comparative Example 1 was compared. As a result, it can be seen that the composition of Comparative Example 1 was observed to precipitate after 48 hours at -20°C, while the composition of Example 1 still maintained the liquid crystal phase after 240 hours, and the storage stability was also excellent.

(Example 2 to Example 5)

The compositions of Examples 2 to 5 are shown in Table 5.

The host composition other than the third component in the table below was prepared in the same manner as in Example 1 to prepare a nematic phase liquid crystal composition (host liquid crystal composition), and the physical property values were measured. In addition, a compound as the third component of the chiral compound was added to these host liquid crystal compositions to prepare a cholesterol liquid crystal composition in such a way that the selective reflection wavelength at 25°C was about 560nm.

It can be seen that compared with the main liquid crystal composition of Comparative Example 1, the main liquid crystal composition other than the third component of Examples 2 to 5 has a low melting point (= a wide liquid crystal temperature range), a small viscosity (η), a slightly larger dielectric anisotropy (△ε), and can be driven by a low voltage. Furthermore, the temperature dependence of the selective reflection wavelength of the unit containing the cholesterol liquid crystal composition of the third component is small, and it is more suitable as a cholesterol material for display elements.

The temperature of the cell containing the cholesterol liquid crystal composition of Examples 2 to 5 was changed from 0°C to 50°C, and the color change was visually observed. As a result, the cell containing the composition of Examples 2 to 5 did not change.

Furthermore, it can be seen that the compositions of Examples 2 to 5 still maintain a liquid crystal phase after 240 hours, and the storage stability is also excellent.

Claims (8)

A cholesterol liquid crystal composition having positive dielectric anisotropy, comprising: a first component having positive dielectric property, a second component having neutral dielectric property, and a third component containing at least two optically active substances having different temperature dependencies of chiral pitch lengths, and containing one or more compounds represented by the general formula (1-1) as the first component, one or more compounds represented by the general formula (1-2) as the first component, one or more compounds represented by the general formula (2-1) as the second component, and one or more compounds selected from compounds represented by the general formula (2-3).

^R1 and ^R2 are each independently an alkyl group having 1 to 7 carbon atoms, an alkoxy group having 1 to 7 carbon atoms, or an alkenyl group having 2 to 7 carbon atoms, ^Y1 to ^Y5 are each independently a hydrogen atom or a fluorine atom, ^R3 and ^R4 are each independently an alkenyl group having 2 to 7 carbon atoms, or an alkenyloxy group, ^Y6 to ^Y11 are each independently a hydrogen atom, a fluorine atom, or a methyl group, ^Z1 is a single bond, -COO-, or _-CH2CH2- , _a , b, and c are each independently 0 or 1, ^R7 and ^R8 are each independently an alkyl group having 1 to 7 carbon atoms, an alkoxy group having 1 to 7 carbon atoms, or an alkenyl group having 2 to 7 carbon atoms, or an alkenyloxy group, Ring A is a 1,4-cyclohexylene group or a 1,4-phenylene group in which the hydrogen atom may be substituted with a fluorine atom or a methyl group, Y ^{Y 24} to Y ²⁹ independently represent a hydrogen atom, a fluorine atom or a methyl group, and at least one of Y ²⁷ to Y ²⁹ is a methyl group, and the compound represented by the general formula (2-1) is excluded in the general formula (2-3); wherein the dielectric anisotropy (Δε) of the first component having positive dielectric property is greater than +3.0, the dielectric anisotropy (Δε) of the second component having neutral dielectric property is in the range of -1.5 to +1.5, and the third component comprises a combination of compounds represented by the general formula (3-1) and the general formula (3-3), or a combination of compounds represented by the general formula (3-2) and the general formula (3-4),

The cholesterol liquid crystal composition as described in claim 1 further contains one or more compounds represented by the general formula (2-2) as a second component,

^R5 and ^R6 independently represent an alkyl group having 1 to 7 carbon atoms, an alkoxy group having 1 to 7 carbon atoms, or an alkenyl group having 2 to 7 carbon atoms, Ring B and Ring C independently represent a 1,4-cyclohexylene group or a 1,4-phenylene group in which the hydrogen atom may be substituted by a fluorine atom, ^Z2 represents a single bond, -COO-, _-CH2CH2- , _-CH =CH-, -FC=CF-, or -C=NN=C-, d represents 1, 2, or 3, and when there are a plurality of Ring B and Z2 ^, they may be the same or different. The cholesterol liquid crystal composition as claimed in claim 1 further comprises one or more compounds represented by the general formula (1-3) as a first component,

^R7 represents an alkyl group having 1 to 7 carbon atoms, an alkoxy group having 1 to 7 carbon atoms, or an alkenyl group having 2 to 7 carbon atoms, ^Y12 to ^Y23 independently represent a hydrogen atom or a fluorine atom, ^X1 represents a fluorine atom, a chlorine atom, -CN, -NCS, _-CF3 , or _-OCF3 , and ^Z3 and ^Z4 independently represent a single bond, _-CH2CH2- , _-COO- , _-OCO- , _-CH2O- , _-OCH2- , -CF2O-, _-OCF2- , or -C≡C-. The cholesterol liquid crystal composition according to claim 1 contains one or more compounds represented by the general formula (1-1-a) as the compound represented by the general formula (1-1),

^R1 has the same meaning as ^R1 described in claim 1. The cholesterol liquid crystal composition according to claim 1 contains one or more compounds selected from the group of compounds represented by general formula (1-2-a) and general formula (1-2-b) as the compound represented by general formula (1-2),

^R2 has the same meaning as ^R2 described in claim 1. The cholesterol liquid crystal composition as described in claim 1 further contains one or more compounds selected from the compounds represented by the general formula (1-4) as the first component,

R ⁹ represents an alkyl group having 1 to 7 carbon atoms, an alkoxy group having 1 to 7 carbon atoms, or an alkenyl group having 2 to 7 carbon atoms; X ² represents a fluorine atom, a chlorine atom, -CN, -NCS, -CF ₃ , or -OCF ₃ ; Ring B and Ring C independently represent a 1,4-cyclohexylene group or a 1,4-phenylene group in which the hydrogen atom may be substituted by a fluorine atom; Z ⁵ represents a single bond, -COO-, -CH ₂ CH ₂ -, -CH=CH-, -FC=CF-, or -C=NN=C-; d represents 1, 2, or 3; when there are a plurality of Ring B and Z ⁵ , they may be the same or different, respectively; and in the general formula (1-4), compounds represented by the general formula (1-1) and the general formula (1-3) are excluded. The cholesterol liquid crystal composition as described in claim 1, wherein the temperature change of the chiral pitch length in the range of 0°C to 50°C is greater than -1nm/°C and less than +1nm/°C. A liquid crystal display element, wherein a cholesterol liquid crystal composition as described in any one of claim 1 to claim 6 is used.