JP7766522B2 - Liquid crystal composition and liquid crystal display element - Google Patents

Description

The present invention relates to a liquid crystal composition and a liquid crystal display device containing this composition. In particular, it relates to a liquid crystal composition having positive dielectric anisotropy and an AM (active matrix) device containing this composition and having a TN, ECB, OCB, IPS, FFS, or FPA mode.

Liquid crystal display devices are classified based on the operating mode of the liquid crystal molecules, including PC (phase change), TN (twisted nematic), STN (super twisted nematic), ECB (electrically controlled birefringence), OCB (optically compensated bend), IPS (in-plane switching), VA (vertical alignment), FFS (fringe field switching), and FPA (field-induced photo-reactive alignment). Devices are classified based on their driving method, into PM (passive matrix) and AM (active matrix). PMs are further divided into static and multiplex, while AMs are further divided into TFTs (thin film transistors) and MIMs (metal insulator metal). TFTs are classified into amorphous silicon and polycrystalline silicon. The latter are further divided into high-temperature and low-temperature types depending on the manufacturing process. Classification based on the light source includes reflective types that use natural light, transmissive types that use backlight, and semi-transmissive types that use both natural light and backlight.

Liquid crystal display elements contain a liquid crystal composition having a nematic phase. This composition has suitable properties. By improving the properties of this composition, an AM element with good properties can be obtained. The relationship between these properties is summarized in Table 1 below. The properties of the composition will be further explained based on a commercially available AM element. The temperature range of the nematic phase is related to the temperature range in which the element can be used. The preferred upper temperature limit of the nematic phase is about 60°C or higher, and the preferred lower temperature limit of the nematic phase is about -10°C or lower. The viscosity of the composition is related to the response time of the element. A short response time is preferable for displaying moving images with the element. A response time shorter than 1 millisecond is desirable. Therefore, a low viscosity of the composition is preferable. A low viscosity at low temperatures is even more preferable. The elastic constant of the composition is related to the contrast of the element. To increase the contrast of the element, a large elastic constant of the composition is preferable.

The optical anisotropy of a composition is related to the contrast ratio of a device. Depending on the device mode, a large or small optical anisotropy, i.e., an appropriate optical anisotropy, is required. The product (Δn × d) of the optical anisotropy (Δn) of the composition and the cell gap (d) of the device is designed to maximize the contrast ratio. The appropriate value of this product depends on the type of operating mode. For devices in modes such as TN, an appropriate value is approximately 0.45 μm. In this case, a composition with a large optical anisotropy is preferred for devices with a small cell gap. A large dielectric anisotropy in a composition contributes to a low threshold voltage, low power consumption, and a large contrast ratio in the device. Therefore, a large dielectric anisotropy is preferred. A large resistivity in a composition contributes to a large voltage holding ratio and a large contrast ratio in the device. Therefore, a composition with a large resistivity at the initial stage is preferred. A composition with a large resistivity after long-term use is preferred. The stability of a composition to ultraviolet light and heat is related to the life of an LCD device. High stability leads to a long life of the device. These characteristics are desirable for AM elements used in LCD monitors, LCD televisions, etc.

Compositions with positive dielectric anisotropy are used in AM elements having a TN mode. Compositions with negative dielectric anisotropy are used in AM elements having a VA mode. Compositions with positive or negative dielectric anisotropy are used in AM elements having an IPS mode or FFS mode. Compositions with positive or negative dielectric anisotropy are used in polymer sustained alignment (PSA) type AM elements.

Compounds containing a cyano group (cyano compounds) are known to have a large positive dielectric anisotropy. For example, Patent Document 1 discloses a liquid crystal composition containing a cyano compound with an ester bond, and states that liquid crystal display elements using this composition have a very short response time. On the other hand, Patent Document 2 states that liquid crystal compositions containing cyano compounds have a lower voltage holding ratio (VHR) than liquid crystal compositions that do not contain cyano compounds.

In recent years, with the trend toward faster response times for liquid crystal display elements, there has been a demand for liquid crystal compositions with lower rotational viscosity. Furthermore, in order to narrow the cell gap, these compositions must also possess the desired optical anisotropy. To be applicable to liquid crystal display elements, liquid crystal compositions must possess these properties while also having other properties, such as voltage holding ratio, that are suitable for practical use.

Japanese Patent Application Laid-Open No. 2004-204233 International Publication No. 2011-062049

An object of the present invention is to provide a liquid crystal composition that satisfies at least one of the following characteristics: a high upper limit temperature of the nematic phase, a low lower limit temperature of the nematic phase, a small viscosity, a large optical anisotropy, a large positive dielectric anisotropy, a large resistivity, high stability to light, high stability to heat, and a large elastic constant. Another object is to provide a liquid crystal composition that has an appropriate balance between at least two of these characteristics. Another object is to provide a liquid crystal display element containing such a composition. Another object is to provide an AM element that has characteristics such as a short response time, a large voltage holding ratio, a low threshold voltage, a large contrast ratio, and a long lifespan.

The present invention relates to a liquid crystal composition having positive dielectric anisotropy, which contains as component A at least one compound selected from compounds represented by formula (1), as component B at least one compound selected from compounds represented by formula (2), and as component C at least one compound selected from compounds represented by formula (3), and which does not contain a polymerizable compound or a polymer, and a liquid crystal display device containing this composition.


In formula (1), R ¹ is hydrogen, alkyl having 1 to 12 carbon atoms, alkoxy having 1 to 12 carbon atoms, alkenyl having 2 to 12 carbon atoms, alkenyloxy having 2 to 12 carbon atoms, or alkyl having 1 to 12 carbon atoms in which at least one hydrogen is replaced by fluorine or chlorine; X ¹ , X ² , X ³ , X ⁴ , and X ⁵ are hydrogen or fluorine, and at least one of X ¹ , X ² , X ³ , X ⁴ , and X ⁵ is fluorine;
In formula (2), R ² is alkyl having 1 to 12 carbon atoms, alkoxy having 1 to 12 carbon atoms, or alkenyl having 2 to 12 carbon atoms; ring A ¹ and ring A ² are 1,4-phenylene, 2-fluoro-1,4-phenylene, 2,3-difluoro-1,4-phenylene, or 2,6-difluoro-1,4-phenylene; Z ¹ and Z ² are a single bond, ethylene, vinylene, methyleneoxy, carbonyloxy, or difluoromethyleneoxy; X ⁶ and X ⁷ are hydrogen or fluorine; Y ¹ is fluorine, chlorine, alkyl having 1 to 12 carbon atoms in which at least one hydrogen is replaced with fluorine or chlorine, alkoxy having 1 to 12 carbon atoms in which at least one hydrogen is replaced with fluorine or chlorine, or alkenyloxy having 2 to 12 carbon atoms in which at least one hydrogen is replaced with fluorine or chlorine; m is 1, 2, or 3;
In formula (3), R ³ and R ⁴ are alkyl having 1 to 12 carbon atoms, alkoxy having 1 to 12 carbon atoms, alkenyl having 2 to 12 carbon atoms, or alkenyl having 2 to 12 carbon atoms in which at least one hydrogen is replaced by fluorine or chlorine; ring B and ring C are 1,4-cyclohexylene, 1,4-phenylene, 2-fluoro-1,4-phenylene, or 2,5-difluoro-1,4-phenylene; Z ³ is a single bond, ethylene, vinylene, methyleneoxy, or carbonyloxy; and n is 1, 2, or 3.

An advantage of the present invention is to provide a liquid crystal composition that satisfies at least one of the following characteristics: a high upper limit temperature of the nematic phase, a low lower limit temperature of the nematic phase, a small viscosity, a large optical anisotropy, a large positive dielectric anisotropy, a large resistivity, high stability to light, high stability to heat, and a large elastic constant. Another advantage is to provide a liquid crystal composition that has an appropriate balance between at least two of these characteristics. Another advantage is to provide a liquid crystal display element containing such a composition. Another advantage is to provide an AM element that has characteristics such as a short response time, a large voltage holding ratio, a low threshold voltage, a large contrast ratio, and a long lifespan.

The following terms are used in this specification. The terms "liquid crystal composition" and "liquid crystal display element" may be abbreviated as "composition" and "element," respectively. "Liquid crystal display element" is a general term for liquid crystal display panels and liquid crystal display modules. "Liquid crystal compound" is a general term for compounds that have a liquid crystal phase, such as a nematic or smectic phase, and compounds that do not have a liquid crystal phase but are mixed into a composition to adjust properties such as the temperature range, viscosity, and dielectric anisotropy of the nematic phase. These compounds have a six-membered ring, such as 1,4-cyclohexylene or 1,4-phenylene, and their molecules (liquid crystal molecules) are rod-like. "Polymerizable compound" is a compound added to a composition to form a polymer. Liquid crystal compounds containing alkenyl are not classified as polymerizable compounds in this sense.

A liquid crystal composition is prepared by mixing multiple liquid crystal compounds. Additives such as optically active compounds may be added to this liquid crystal composition as needed. The proportion of the liquid crystal compounds, even when additives are added, is expressed as a mass percentage (mass %) based on the mass of the liquid crystal composition without the additives. The proportion of the additives is expressed as a mass percentage (mass %) based on the mass of the liquid crystal composition without the additives. In other words, the proportions of the liquid crystal compounds and additives are calculated based on the total mass of the liquid crystal compounds.

The "maximum temperature of the nematic phase" is sometimes abbreviated as "maximum temperature." The "minimum temperature of the nematic phase" is sometimes abbreviated as "minimum temperature." The expression "increasing the dielectric anisotropy" means that the value increases positively for a composition with positive dielectric anisotropy, and that the value increases negatively for a composition with negative dielectric anisotropy. "Large voltage holding ratio" means that the element has a large voltage holding ratio not only at room temperature but also at temperatures close to the maximum temperature in the initial stage, and that after long-term use it maintains a large voltage holding ratio not only at room temperature but also at temperatures close to the maximum temperature. The characteristics of compositions and elements are sometimes examined by aging tests.

The above compound (1z) will be used as an example. In formula (1z), the symbols α and β enclosed in a hexagon correspond to ring α and ring β, respectively, and represent rings such as six-membered rings and fused rings. When the subscript 'x' is 2, two rings α exist. The two groups represented by the two rings α may be the same or different. This rule applies to any two rings α when the subscript 'x' is greater than 2. This rule also applies to other symbols, such as the bonding group Z. A diagonal line across one side of ring β indicates that any hydrogen on ring β may be replaced with a substituent (-Sp-P). The subscript 'y' indicates the number of replaced substituents. When the subscript 'y' is 0, there is no such replacement. When the subscript 'y' is 2 or greater, multiple substituents (-Sp-P) exist on ring β. In this case, the "may be the same or different" rule also applies. Note that this rule also applies when the symbol Ra is used for multiple compounds.

In formula (1z), for example, an expression such as "Ra and Rb are alkyl, alkoxy, or alkenyl" means that Ra and Rb are independently selected from the group consisting of alkyl, alkoxy, and alkenyl. Here, the group represented by Ra and the group represented by Rb may be the same or different.

At least one compound selected from compounds represented by formula (1z) may be abbreviated as "compound (1z)." "Compound (1z)" means one compound represented by formula (1z), a mixture of two compounds, or a mixture of three or more compounds. The same applies to compounds represented by other formulas. The expression "at least one compound selected from compounds represented by formula (1z) and formula (2z)" means at least one compound selected from the group consisting of compound (1z) and compound (2z).

The expression "at least one 'A'" means that the number of 'A' is arbitrary. The expression "at least one 'A' may be replaced with 'B'" means that when there is one 'A', the position of 'A' is arbitrary, and when there are two or more 'As', their positions can be selected without restriction. The expression "at least one -CH ₂ - may be replaced with -O-" is sometimes used. In this case, -CH ₂ -CH ₂ -CH ₂ - may be converted to -O-CH ₂ -O- by replacing a non-adjacent -CH ₂ - with -O-. However, adjacent -CH ₂ - is not replaced with -O- because this replacement would produce -O-O-CH ₂ - (peroxide).

The alkyl of the liquid crystal compound is linear or branched, and does not include cyclic alkyl. Linear alkyl is preferred to branched alkyl. The same applies to terminal groups such as alkoxy and alkenyl. The configuration of 1,4-cyclohexylene is preferably trans rather than cis in order to increase the maximum temperature. 2-Fluoro-1,4-phenylene is asymmetric, so it exists in left-facing (L) and right-facing (R) configurations.


The same applies to a divalent group such as tetrahydropyran-2,5-diyl, and a bonding group such as carbonyloxy (-COO- or -OCO-).

The present invention includes the following items:

Item 1. A liquid crystal composition having positive dielectric anisotropy, comprising as component A at least one compound selected from compounds represented by formula (1), as component B at least one compound selected from compounds represented by formula (2), and as component C at least one compound selected from compounds represented by formula (3), and containing no polymerizable compound or polymer.


In formula (1), R ¹ is hydrogen, alkyl having 1 to 12 carbon atoms, alkoxy having 1 to 12 carbon atoms, alkenyl having 2 to 12 carbon atoms, alkenyloxy having 2 to 12 carbon atoms, or alkyl having 1 to 12 carbon atoms in which at least one hydrogen is replaced by fluorine or chlorine; X ¹ , X ² , X ³ , X ⁴ , and X ⁵ are hydrogen or fluorine, and at least one of X ¹ , X ² , X ³ , X ⁴ , and X ⁵ is fluorine;
In formula (2), R ² is alkyl having 1 to 12 carbon atoms, alkoxy having 1 to 12 carbon atoms, or alkenyl having 2 to 12 carbon atoms; ring A ¹ and ring A ² are 1,4-phenylene, 2-fluoro-1,4-phenylene, 2,3-difluoro-1,4-phenylene, or 2,6-difluoro-1,4-phenylene; Z ¹ and Z ² are a single bond, ethylene, vinylene, methyleneoxy, carbonyloxy, or difluoromethyleneoxy; X ⁶ and X ⁷ are hydrogen or fluorine; Y ¹ is fluorine, chlorine, alkyl having 1 to 12 carbon atoms in which at least one hydrogen is replaced with fluorine or chlorine, alkoxy having 1 to 12 carbon atoms in which at least one hydrogen is replaced with fluorine or chlorine, or alkenyloxy having 2 to 12 carbon atoms in which at least one hydrogen is replaced with fluorine or chlorine; m is 1, 2, or 3;
In formula (3), R ³ and R ⁴ are alkyl having 1 to 12 carbon atoms, alkoxy having 1 to 12 carbon atoms, alkenyl having 2 to 12 carbon atoms, or alkenyl having 2 to 12 carbon atoms in which at least one hydrogen is replaced by fluorine or chlorine; ring B and ring C are 1,4-cyclohexylene, 1,4-phenylene, 2-fluoro-1,4-phenylene, or 2,5-difluoro-1,4-phenylene; Z ³ is a single bond, ethylene, vinylene, methyleneoxy, or carbonyloxy; and n is 1, 2, or 3.

Item 2. The liquid crystal composition according to item 1, containing, as component A, at least one compound selected from the compounds represented by formulas (1-1) to (1-6):


In formulas (1-1) to (1-6), R ¹ is hydrogen, alkyl having 1 to 12 carbon atoms, alkoxy having 1 to 12 carbon atoms, alkenyl having 2 to 12 carbon atoms, alkenyloxy having 2 to 12 carbon atoms, or alkyl having 1 to 12 carbon atoms in which at least one hydrogen is replaced by fluorine or chlorine.

Item 3. The liquid crystal composition according to item 1 or 2, wherein the proportion of component A is in the range of 1% by mass to 50% by mass.

Item 4. The liquid crystal composition according to any one of items 1 to 3, containing, as component B, at least one compound selected from the compounds represented by formulas (2-1) to (2-11):



In formulas (2-1) to (2-11), R ² is alkyl having 1 to 12 carbon atoms, alkoxy having 1 to 12 carbon atoms, or alkenyl having 2 to 12 carbon atoms.

Item 5. The liquid crystal composition according to any one of items 1 to 4, wherein the proportion of component B is in the range of 1% by mass to 50% by mass.

Item 6. The liquid crystal composition according to any one of items 1 to 5, containing, as component C, at least one compound selected from the compounds represented by formulas (3-1) to (3-13):


In formulas (3-1) to (3-13), R ³ and R ⁴ are alkyl having 1 to 12 carbon atoms, alkoxy having 1 to 12 carbon atoms, alkenyl having 2 to 12 carbon atoms, or alkenyl having 2 to 12 carbon atoms in which at least one hydrogen is replaced by fluorine or chlorine.

Item 7. The liquid crystal composition according to any one of items 1 to 6, wherein the proportion of component C is in the range of 20% by mass to 90% by mass.

Item 8. The liquid crystal composition according to any one of items 1 to 7, containing, as component D, at least one compound selected from the group of compounds represented by formula (4):


In formula (4), R ⁵ is alkyl having 1 to 12 carbon atoms, alkoxy having 1 to 12 carbon atoms, or alkenyl having 2 to 12 carbon atoms; ring D is 1,4-cyclohexylene, 1,4-phenylene, 2-fluoro-1,4-phenylene, 2,3-difluoro-1,4-phenylene, 2,6-difluoro-1,4-phenylene, pyrimidine-2,5-diyl, 1,3-dioxane-2,5-diyl, or tetrahydropyran-2,5-diyl, and at least one of rings D is 1,4-cyclohexylene, pyrimidine-2,5-diyl, 1,3-dioxane-2,5-diyl, or tetrahydropyran-2,5-diyl; Z ⁴ is a single bond, ethylene, vinylene, methyleneoxy, carbonyloxy, or difluoromethyleneoxy; X ⁸ and X ⁹ is hydrogen or fluorine; ^Y2 is fluorine, chlorine, alkyl having 1 to 12 carbon atoms in which at least one hydrogen is replaced by fluorine or chlorine, alkoxy having 1 to 12 carbon atoms in which at least one hydrogen is replaced by fluorine or chlorine, or alkenyloxy having 2 to 12 carbon atoms in which at least one hydrogen is replaced by fluorine or chlorine; and a is 1, 2, 3, or 4.

Item 9. The liquid crystal composition according to any one of items 1 to 8, containing, as component D, at least one compound selected from the group of compounds represented by formulas (4-1) to (4-24):




In formulas (4-1) to (4-24), R ⁵ is alkyl having 1 to 12 carbon atoms, alkoxy having 1 to 12 carbon atoms, or alkenyl having 2 to 12 carbon atoms.

Item 10. The liquid crystal composition according to item 8 or 9, wherein the proportion of component D is in the range of 1% by mass to 50% by mass.

Item 11. The liquid crystal composition according to any one of items 1 to 10, containing, as component E, at least one compound selected from compounds represented by formula (5):


In formula (5), R ⁶ and R ⁷ are hydrogen, alkyl having 1 to 12 carbon atoms, alkoxy having 1 to 12 carbon atoms, alkenyl having 2 to 12 carbon atoms, or alkenyloxy having 2 to 12 carbon atoms; ring E and ring G are 1,4-cyclohexylene, 1,4-cyclohexenylene, tetrahydropyran-2,5-diyl, 1,4-phenylene, 1,4-phenylene in which at least one hydrogen is replaced by fluorine or chlorine, naphthalene-2,6-diyl, naphthalene-2,6-diyl in which at least one hydrogen is replaced by fluorine or chlorine, chroman-2,6-diyl, or 1,4-phenylene in which at least one hydrogen is replaced by fluorine or chlorine. ring F is 2,3-difluoro-1,4-phenylene, 2-chloro-3-fluoro-1,4-phenylene, 2,3-difluoro-5-methyl-1,4-phenylene, 3,4,5-trifluoronaphthalene-2,6-diyl, 7,8-difluorochroman-2,6-diyl, 3,4,5,6-tetrafluorofluorene-2,7-diyl, 4,6-difluorodibenzofuran-3,7-diyl, 4,6-difluorodibenzothiophene-3,7-diyl, or 1,1,6,7-tetrafluoroindan-2,5-diyl; Z is ^{Z 5} and Z ⁶ are a single bond, ethylene, vinylene, methyleneoxy, or carbonyloxy; c is 0, 1, 2, or 3, d is 0 or 1, and the sum of c and d is 3 or less.

Item 12. The liquid crystal composition according to any one of items 1 to 11, comprising, as component E, at least one compound selected from the compounds represented by formulae (5-1) to (5-35):





In formulae (5-1) to (5-35), R ⁶ and R ⁷ are hydrogen, alkyl having 1 to 12 carbon atoms, alkoxy having 1 to 12 carbon atoms, alkenyl having 2 to 12 carbon atoms, or alkenyloxy having 2 to 12 carbon atoms.

Item 13. The liquid crystal composition according to item 11 or 12, wherein the proportion of component E is in the range of 3% by mass to 45% by mass.

Item 14. The liquid crystal composition according to any one of items 1 to 13, which has a nematic phase at least in the range of 0°C to 60°C.

Item 15. A liquid crystal composition according to any one of items 1 to 14, having a maximum temperature of a nematic phase of 60°C or higher, an optical anisotropy at a wavelength of 589 nm (measured at 25°C) of 0.07 or higher, and a dielectric anisotropy at a frequency of 1 kHz (measured at 25°C) of 2 or higher.

Item 16. A liquid crystal display element containing the liquid crystal composition described in any one of items 1 to 15.

Item 17. The liquid crystal display element according to Item 16, wherein the operating mode of the liquid crystal display element is TN mode, ECB mode, OCB mode, IPS mode, FFS mode, or FPA mode, and the driving method of the liquid crystal display element is an active matrix method.

Item 18. Use of the liquid crystal composition according to any one of items 1 to 15 in a liquid crystal display device.

The present invention also includes the following: (a) the above composition containing one compound, two compounds, or three or more compounds selected from additives such as optically active compounds, antioxidants, UV absorbers, quenchers, dyes, antifoaming agents, and polar compounds. (b) an AM element containing the above composition. (c) an element containing the above composition and having a PC, TN, STN, ECB, OCB, IPS, VA, FFS, or FPA mode. (d) a transmission element containing the above composition. (e) use of the above composition as a composition having a nematic phase. (f) use of an optically active composition obtained by adding an optically active compound to the above composition.

The liquid crystal composition of the present invention does not contain a polymerizable compound or polymer, and is therefore different from "Polymer Dispersed Liquid Crystal (PDLC)" and "Polymer Network Liquid Crystal (PNLC)," which are used in switch layers that can electronically switch between a transparent state and a scattering state.

The composition of the present invention will be described in the following order. First, the composition's structure will be described. Second, the main properties of the component compounds and the main effects these compounds have on the composition and device will be described. Third, the combination of component compounds in the composition, their preferred ratios, and the reasons for this will be described. Fourth, the preferred forms of the component compounds will be described. Fifth, preferred component compounds will be shown. Sixth, additives that may be added to the composition will be described. Seventh, methods for synthesizing the component compounds will be described. Finally, the uses of the composition will be described.

First, the composition will be described. This composition contains multiple liquid crystal compounds. This composition may contain additives. Additives include optically active compounds, antioxidants, UV absorbers, quenchers, dyes, defoamers, and polar compounds. This composition is classified into Composition A and Composition B from the perspective of the liquid crystal compounds. Composition A may further contain other liquid crystal compounds, additives, and the like, in addition to liquid crystal compounds selected from Compound (1), Compound (2), Compound (3), Compound (4), and Compound (5). "Other liquid crystal compounds" are liquid crystal compounds different from Compound (1), Compound (2), Compound (3), Compound (4), and Compound (5). Such compounds are mixed into the composition to further adjust its properties.

Composition B consists essentially of liquid crystal compounds selected from compound (1), compound (2), compound (3), compound (4), and compound (5). "Substantially" means that composition B may contain additives, but does not contain other liquid crystal compounds. Composition B has fewer components than composition A. From the perspective of reducing costs, composition B is preferable to composition A. From the perspective of being able to further adjust the properties by mixing other liquid crystal compounds, composition A is preferable to composition B.

Second, the main properties of the component compounds and the main effects these compounds have on the composition and device are described. The main properties of the component compounds are summarized in Table 2. In the symbols in Table 2, L means large or high, M means medium, and S means small or low. The symbols L, M, and S are classifications based on qualitative comparisons between the component compounds, and the symbol 0 (zero) means smaller than S.

The main effects of the component compounds are as follows: Compound (1) increases the dielectric anisotropy and optical anisotropy. Compound (2) increases the optical anisotropy and dielectric anisotropy. Compound (3) decreases the viscosity or increases the maximum temperature. Compound (4) increases the dielectric anisotropy. Compound (5) increases the dielectric constant in the minor axis direction.

Third, the combinations of component compounds in the composition, their preferred ratios, and the rationale for them will be explained. Preferred combinations of component compounds in the composition are Compound (1) + Compound (2) + Compound (3), Compound (1) + Compound (2) + Compound (3) + Compound (4), Compound (1) + Compound (2) + Compound (3) + Compound (5), or Compound (1) + Compound (2) + Compound (3) + Compound (4) + Compound (5). A particularly preferred combination is Compound (1) + Compound (2) + Compound (3).

A preferred ratio of compound (1) is approximately 1% by mass or more for increasing the dielectric anisotropy and the optical anisotropy, and approximately 50% by mass or less for decreasing the minimum temperature. A more preferred ratio is in the range of approximately 1% by mass to approximately 30% by mass. A particularly preferred ratio is in the range of approximately 2% by mass to approximately 15% by mass.

A preferred ratio of compound (2) is approximately 1% by mass or more for increasing the optical anisotropy and the dielectric anisotropy, and approximately 50% by mass or less for decreasing the minimum temperature. A more preferred ratio is in the range of approximately 5% to approximately 30% by mass. A particularly preferred ratio is in the range of approximately 5% to approximately 20% by mass.

A preferred ratio of compound (3) is approximately 20% by mass or more for decreasing the viscosity or increasing the maximum temperature, and approximately 90% by mass or less for increasing the dielectric anisotropy. A more preferred ratio is in the range of approximately 30% by mass to approximately 90% by mass. A particularly preferred ratio is in the range of approximately 50% by mass to approximately 90% by mass.

A preferred ratio of compound (4) is approximately 1% by mass or more to increase the dielectric anisotropy, and approximately 50% by mass or less to decrease the minimum temperature. A more preferred ratio is in the range of approximately 1% by mass to approximately 30% by mass. A particularly preferred ratio is in the range of approximately 1% by mass to approximately 20% by mass.

A preferred proportion of compound (5) is approximately 3% by mass or more to increase the dielectric constant in the minor axis direction, and approximately 45% by mass or less to decrease the minimum temperature. A more preferred proportion is in the range of approximately 3% by mass to approximately 30% by mass. An especially preferred proportion is in the range of approximately 3% by mass to approximately 20% by mass.

Fourth, preferred forms of the component compounds will be described. In formulas (1), (2), (3), (4), and (5), ^R1 is hydrogen, alkyl having 1 to 12 carbon atoms, alkoxy having 1 to 12 carbon atoms, alkenyl having 2 to 12 carbon atoms, alkenyloxy having 2 to 12 carbon atoms, or alkyl having 1 to 12 carbon atoms in which at least one hydrogen is replaced by fluorine or chlorine. Preferred ^R1 is alkyl having 1 to 12 carbon atoms or alkenyl having 2 to 12 carbon atoms. Particularly preferred ^R1 is alkyl having 3 to 5 carbon atoms or alkenyl having 2 to 4 carbon atoms. ^R2 is alkyl having 1 to 12 carbon atoms, alkoxy having 1 to 12 carbon atoms, or alkenyl having 2 to 12 carbon atoms. Preferred ^R2 is alkyl having 1 to 12 carbon atoms to increase stability. ^R3 and ^R4 are alkyl having 1 to 12 carbons, alkoxy having 1 to 12 carbons, alkenyl having 2 to 12 carbons, or alkenyl having 2 to 12 carbons in which at least one hydrogen is replaced by fluorine or chlorine. ^R3 or ^R4 is preferably alkenyl having 2 to 12 carbons for decreasing viscosity, or alkyl having 1 to 12 carbons for increasing stability. ^R5 is alkyl having 1 to 12 carbons, alkoxy having 1 to 12 carbons, or alkenyl having 2 to 12 carbons. ^R5 is preferably alkyl having 1 to 12 carbons for increasing stability. ^R6 and ^R7 are each hydrogen, alkyl having 1 to 12 carbons, alkoxy having 1 to 12 carbons, alkenyl having 2 to 12 carbons, or alkenyloxy having 2 to 12 carbons. Desirable ^R6 or ^R7 is alkyl having 1 to 12 carbons for increasing the stability, alkenyl having 2 to 12 carbons for decreasing the viscosity, or alkoxy having 1 to 12 carbons for increasing the dielectric anisotropy.

Preferred alkyl is methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, or octyl. More preferred alkyl is methyl, ethyl, propyl, butyl, or pentyl to reduce viscosity.

Preferred alkoxy is methoxy, ethoxy, propoxy, butoxy, pentyloxy, hexyloxy, or heptyloxy. To reduce viscosity, more preferred alkoxy is methoxy or ethoxy.

Preferred alkenyls are vinyl, 1-propenyl, 2-propenyl, 1-butenyl, 2-butenyl, 3-butenyl, 1-pentenyl, 2-pentenyl, 3-pentenyl, 4-pentenyl, 1-hexenyl, 2-hexenyl, 3-hexenyl, 4-hexenyl, and 5-hexenyl. More preferred alkenyls are vinyl, 1-propenyl, 3-butenyl, and 3-pentenyl to reduce viscosity. The preferred configuration of -CH=CH- in these alkenyls depends on the position of the double bond. For reducing viscosity, trans is preferred for alkenyls such as 1-propenyl, 1-butenyl, 1-pentenyl, 1-hexenyl, 3-pentenyl, and 3-hexenyl. Cis is preferred for alkenyls such as 2-butenyl, 2-pentenyl, and 2-hexenyl.

Preferred alkenyloxy groups are vinyloxy, allyloxy, 3-butenyloxy, 3-pentenyloxy, and 4-pentenyloxy. To reduce viscosity, more preferred alkenyloxy groups are allyloxy and 3-butenyloxy.

Preferred examples of alkyl in which at least one hydrogen is replaced by fluorine or chlorine include fluoromethyl, 2-fluoroethyl, 3-fluoropropyl, 4-fluorobutyl, 5-fluoropentyl, 6-fluorohexyl, 7-fluoroheptyl, and 8-fluorooctyl. More preferred examples are 2-fluoroethyl, 3-fluoropropyl, 4-fluorobutyl, and 5-fluoropentyl, in order to increase the dielectric anisotropy.

Preferred examples of alkenyl in which at least one hydrogen is replaced by fluorine or chlorine include 2,2-difluorovinyl, 3,3-difluoro-2-propenyl, 4,4-difluoro-3-butenyl, 5,5-difluoro-4-pentenyl, and 6,6-difluoro-5-hexenyl. More preferred examples are 2,2-difluorovinyl and 4,4-difluoro-3-butenyl, which are used to reduce viscosity.

Ring ^A1 and ring ^A2 are 1,4-phenylene, 2-fluoro-1,4-phenylene, 2,3-difluoro-1,4-phenylene, or 2,6-difluoro-1,4-phenylene. Preferred ring ^A1 is 1,4-phenylene for decreasing the viscosity. Preferred ring ^A2 is 2-fluoro-1,4-phenylene or 2,6-difluoro-1,4-phenylene for increasing the dielectric anisotropy.

Ring B and ring C are 1,4-cyclohexylene, 1,4-phenylene, 2-fluoro-1,4-phenylene, or 2,5-difluoro-1,4-phenylene. Preferred ring B or ring C is 1,4-cyclohexylene for decreasing the viscosity or increasing the maximum temperature, and 1,4-phenylene or 2-fluoro-1,4-phenylene for increasing the optical anisotropy or decreasing the minimum temperature.

Ring D is 1,4-cyclohexylene, 1,4-phenylene, 2-fluoro-1,4-phenylene, 2,3-difluoro-1,4-phenylene, 2,6-difluoro-1,4-phenylene, pyrimidine-2,5-diyl, 1,3-dioxane-2,5-diyl, or tetrahydropyran-2,5-diyl, and at least one of rings D is 1,4-cyclohexylene, pyrimidine-2,5-diyl, 1,3-dioxane-2,5-diyl, or tetrahydropyran-2,5-diyl. Preferred ring D is 1,4-cyclohexylene for increasing the maximum temperature. When two or more rings D are present, 1,4-phenylene is also preferred for increasing the optical anisotropy, and 1,3-dioxane-2,5-diyl, 2-fluoro-1,4-phenylene, or 2,6-difluoro-1,4-phenylene is also preferred for increasing the dielectric anisotropy.

or

and preferably

is.

Ring E and Ring G are 1,4-cyclohexylene, 1,4-cyclohexenylene, tetrahydropyran-2,5-diyl, 1,4-phenylene, 1,4-phenylene in which at least one hydrogen has been replaced with fluorine or chlorine, naphthalene-2,6-diyl, naphthalene-2,6-diyl in which at least one hydrogen has been replaced with fluorine or chlorine, chroman-2,6-diyl, or chroman-2,6-diyl in which at least one hydrogen has been replaced with fluorine or chlorine. Preferred examples of 1,4-phenylene in which at least one hydrogen has been replaced with fluorine or chlorine include 2-fluoro-1,4-phenylene, 2,3-difluoro-1,4-phenylene, and 2-chloro-3-fluoro-1,4-phenylene. An example of naphthalene-2,6-diyl in which at least one hydrogen is replaced by fluorine or chlorine is 3,4,5-trifluoronaphthalene-2,6-diyl. An example of chroman-2,6-diyl in which at least one hydrogen is replaced by fluorine or chlorine is 7,8-difluorochroman-2,6-diyl. Desirable ring E or ring G is 1,4-cyclohexylene for decreasing the viscosity, tetrahydropyran-2,5-diyl for increasing the dielectric anisotropy, or 1,4-phenylene for increasing the optical anisotropy.

Ring F is 2,3-difluoro-1,4-phenylene, 2-chloro-3-fluoro-1,4-phenylene, 2,3-difluoro-5-methyl-1,4-phenylene, 3,4,5-trifluoronaphthalene-2,6-diyl, 7,8-difluorochroman-2,6-diyl, 3,4,5,6-tetrafluorofluorene-2,7-diyl (FLF4), 4,6-difluorodibenzofuran-3,7-diyl (DBFF2), 4,6-difluorodibenzothiophene-3,7-diyl (DBTF2), or 1,1,6,7-tetrafluoroindan-2,5-diyl (InF4).


Desirable ring F is 2,3-difluoro-1,4-phenylene for decreasing the viscosity, and 4,6-difluorodibenzofuran-3,7-diyl for increasing the dielectric anisotropy.

^Z1 and ^Z2 are each a single bond, ethylene, vinylene, methyleneoxy, carbonyloxy, or difluoromethyleneoxy. Preferred ^Z1 is a single bond for decreasing the viscosity. Preferred ^Z2 is a single bond for decreasing the viscosity, and difluoromethyleneoxy for increasing the dielectric anisotropy. ^Z3 is a single bond, ethylene, vinylene, methyleneoxy, or carbonyloxy. Preferred ^Z3 is a single bond for decreasing the viscosity. ^Z4 is a single bond, ethylene, vinylene, methyleneoxy, carbonyloxy, or difluoromethyleneoxy. Preferred ^Z4 is a single bond for decreasing the viscosity, and difluoromethyleneoxy for increasing the dielectric anisotropy. ^Z5 and ^Z6 are each a single bond, ethylene, vinylene, methyleneoxy, or carbonyloxy. Preferred ^Z5 or ^Z6 is a single bond for decreasing the viscosity, ethylene for increasing the elastic constant, or methyleneoxy for increasing the dielectric constant in the minor axis direction.

Divalent groups such as methyleneoxy are asymmetric. In methyleneoxy, —CH ₂ O— is preferred to —OCH ₂ —. In carbonyloxy, —COO— is preferred to —OCO—. In difluoromethyleneoxy, —CF ₂ O— is preferred to —OCF ₂ —.

^X1 , ^X2 , ^X3 , ^X4 , and ^X5 are hydrogen or fluorine, and at least one of ^X1 , ^X2 , ^X3 , ^X4 , and ^X5 is fluorine. In order to increase the dielectric anisotropy, at least two of ^X1 , ^X2 , ^X3 , ^X4 , and ^X5 are preferably fluorine. In order to decrease the minimum temperature, at least one of ^X1 , ^X2 , and ^X3 is preferably fluorine. ^X6 , ^X7 , ^X8 , and ^X9 are hydrogen or fluorine. Preferred ^X6 , ^X7 , ^X8 , or ^X9 is fluorine in order to increase the dielectric anisotropy.

^Y1 and ^Y2 are fluorine, chlorine, alkyl having 1 to 12 carbon atoms in which at least one hydrogen is replaced by fluorine or chlorine, alkoxy having 1 to 12 carbon atoms in which at least one hydrogen is replaced by fluorine or chlorine, or alkenyloxy having 2 to 12 carbon atoms in which at least one hydrogen is replaced by fluorine or chlorine. Desirable ^Y1 or ^Y2 is fluorine, alkyl having 1 to 12 carbon atoms in which at least one hydrogen is replaced by fluorine or chlorine, or alkoxy having 1 to 12 carbon atoms in which at least one hydrogen is replaced by fluorine or chlorine in order to increase the dielectric anisotropy. A preferred example of alkyl having at least one hydrogen replaced by fluorine or chlorine is trifluoromethyl. A preferred example of alkoxy having at least one hydrogen replaced by fluorine or chlorine is trifluoromethoxy.

m is 1, 2, or 3. Preferred m is 1 to decrease the viscosity, and 2 or 3 to increase the dielectric anisotropy. n is 1, 2, or 3. Preferred n is 1 to decrease the viscosity, and 2 or 3 to increase the maximum temperature. a is 1, 2, 3, or 4. Preferred a is 1 or 2 to decrease the viscosity, and 3 or 4 to increase the dielectric anisotropy. c is 0, 1, 2, or 3, d is 0 or 1, and the sum of c and d is 3 or less. Preferred c is 1 or 2, and preferred d is 0 or 1.

Fifth, preferred component compounds are shown. Preferred compound (1) is compound (1-1) to compound (1-6) described in item 2. It is preferred that at least one of component A is compound (1-1), compound (1-4), compound (1-5), or compound (1-6).

Preferred compounds (2) are compounds (2-1) to (2-11) described in item 4. In these compounds, it is preferable that at least one of component B is compound (2-1), compound (2-2), compound (2-4), compound (2-6), or compound (2-7). It is preferable that at least two of component B are a combination of compound (2-1) and compound (2-2), compound (2-1) and compound (2-4), compound (2-1) and compound (2-6), compound (2-2) and compound (2-6), compound (2-2) and compound (2-7), compound (2-4) and compound (2-6), compound (2-4) and compound (2-7), or compound (2-6) and compound (2-7).

Preferred compounds (3) are compounds (3-1) to (3-13) described in item 6. Among these compounds, it is preferable that at least one of the components C is compound (3-1), compound (3-3), compound (3-5), compound (3-6), compound (3-7), compound (3-8), compound (3-10), or compound (3-13). It is even more preferable that at least one of the components C is compound (3-1), compound (3-3), compound (3-6), or compound (3-8). It is preferable that at least two of the components C are a combination of compound (3-1) and compound (3-3), compound (3-1) and compound (3-6), compound (3-1) and compound (3-8), compound (3-3) and compound (3-6), compound (3-3) and compound (3-8), or compound (3-6) and compound (3-8).

Preferred compounds (4) are compounds (4-1) to (4-24) described in item 9. In these compounds, it is preferable that at least one of component D is compound (4-2), compound (4-4), compound (4-8), compound (4-14), compound (4-15), compound (4-20), or compound (4-23).

Preferred compounds (5) are compounds (5-1) to (5-35) described in item 12. In these compounds, it is preferable that at least one of component E is compound (5-1), compound (5-2), compound (5-3), compound (5-6), compound (5-8), compound (5-9), compound (5-10), compound (5-14), or compound (5-16).

Sixth, additives that may be added to the composition are described. Such additives include optically active compounds, antioxidants, UV absorbers, quenchers, dyes, antifoaming agents, and polar compounds. Optically active compounds are added to the composition for the purpose of inducing a helical structure of the liquid crystal molecules and imparting a twist angle. Examples of such compounds are compounds (6-1) to (6-5). The preferred proportion of the optically active compound is about 5% by mass or less. A more preferred proportion is in the range of about 0.01% by mass to about 2% by mass.

An antioxidant such as compounds (7-1) to (7-3) may be further added to the composition to prevent a decrease in resistivity due to heating in the atmosphere, or to maintain a high voltage holding ratio not only at room temperature but also at temperatures close to the upper limit temperature after the element has been used for an extended period of time.

Compound (7-2) has low volatility, so it is effective in maintaining a high voltage holding ratio not only at room temperature but also at temperatures close to the upper limit temperature after the device has been used for an extended period of time. The preferred antioxidant ratio is approximately 50 ppm or more to achieve this effect, and approximately 600 ppm or less to avoid lowering the upper limit temperature or raising the lower limit temperature. A more preferred ratio is in the range of approximately 100 ppm to approximately 300 ppm.

Preferred examples of ultraviolet absorbers include benzophenone derivatives, benzoate derivatives, and triazole derivatives. Light stabilizers such as sterically hindered amines are also preferred. Preferred examples of light stabilizers include compounds (8-1) to (8-16). The preferred ratio of these absorbers and stabilizers is approximately 50 ppm or more to achieve their intended effect, and approximately 10,000 ppm or less to avoid lowering the maximum temperature or raising the minimum temperature. A more preferred ratio is in the range of approximately 100 ppm to approximately 10,000 ppm.

A quencher is a compound that prevents decomposition of a liquid crystalline compound by receiving light energy absorbed by the liquid crystalline compound and converting it into thermal energy. Preferred examples of quenchers include compounds (9-1) to (9-7). The preferred proportion of these quenchers is approximately 50 ppm or more to achieve their effect, and approximately 20,000 ppm or less to avoid raising the minimum temperature. A more preferred proportion is in the range of approximately 100 ppm to approximately 10,000 ppm.

To make the composition compatible with GH (guest-host) mode devices, a dichroic dye such as an azo dye or an anthraquinone dye is added to the composition. The preferred dye content is between about 0.01% and about 10% by weight. To prevent foaming, an antifoaming agent such as dimethyl silicone oil or methylphenyl silicone oil is added to the composition. The preferred antifoaming agent content is between about 1 ppm or more to achieve its intended effect and about 1000 ppm or less to prevent display defects. A more preferred content is between about 1 ppm and about 500 ppm.

Polar compounds are organic compounds that have polarity. This does not include compounds with ionic bonds. Atoms such as oxygen, sulfur, and nitrogen are more electronegative and tend to carry a partial negative charge. Carbon and hydrogen tend to be neutral or carry a partial positive charge. Polarity arises from the uneven distribution of partial charges among different atoms in a compound. For example, polar compounds have at least one of the following moieties: -OH, -COOH, -SH, _-NH2 , >NH, >N-.

Seventh, the synthesis methods for the component compounds are described. These compounds can be synthesized by known methods. Examples of synthesis methods are as follows: Compound (1-1) is synthesized by the method described in JP-A-10-114733. Compound (2-4) is synthesized by the method described in JP-A-10-251186. Compound (3-1) is synthesized by the method described in JP-A-59-176221. Compound (4-2) is synthesized by the method described in JP-A-2-233626. Antioxidants are commercially available. Compound (5-1) is synthesized by the method described in JP-T-2-503441. Compound (7-1) is available from Sigma-Aldrich Corporation. Compounds (7-2) and others are synthesized by the method described in U.S. Patent No. 3,660,505.

Compounds for which no synthetic method is described can be synthesized by methods described in textbooks such as Organic Syntheses (John Wiley & Sons, Inc.), Organic Reactions (John Wiley & Sons, Inc.), Comprehensive Organic Synthesis (Pergamon Press), and New Experimental Chemistry Lectures (Maruzen). Compositions can be prepared from compounds obtained in this way by known methods. For example, the component compounds can be mixed and dissolved by heating.

Finally, the uses of the composition are described. This composition primarily has a lower limit temperature of about -10°C or less, an upper limit temperature of about 60°C or more, and an optical anisotropy ranging from about 0.07 to about 0.20. By controlling the ratio of the component compounds or by mixing other liquid crystal compounds, a composition having an optical anisotropy ranging from about 0.08 to about 0.25 may be prepared. By trial and error, a composition having an optical anisotropy ranging from about 0.10 to about 0.30 may also be prepared. Elements containing this composition have a large voltage holding ratio. This composition is suitable for AM elements. This composition is particularly suitable for transmissive AM elements. This composition can be used as a composition having a nematic phase, or as an optically active composition by adding an optically active compound.

This composition can be used in AM devices. It can also be used in PM devices. This composition can be used in AM devices and PM devices with modes such as PC, TN, STN, ECB, OCB, IPS, FFS, VA, and FPA. Use in AM devices with TN, OCB, IPS, or FFS modes is particularly preferred. In AM devices with IPS or FFS modes, the alignment of the liquid crystal molecules may be parallel or perpendicular to the glass substrate when no voltage is applied. These devices may be reflective, transmissive, or semi-transmissive. Use in transmissive devices is preferred. It can also be used in amorphous silicon TFT devices or polycrystalline silicon TFT devices. This composition can also be used in NCAP (nematic curvilinear aligned phase) devices fabricated by microencapsulating it, and PD (polymer dispersed) devices in which a three-dimensional network polymer is formed within the composition.

The present invention will be described in more detail using examples. The present invention is not limited by these examples. The present invention includes a mixture of the composition of Example 1 and the composition of Example 2. The present invention also includes a mixture of at least two of the compositions of the examples. The synthesized compounds were identified by methods such as NMR analysis. The properties of the compounds, compositions, and devices were measured by the methods described below.

NMR analysis: A DRX-500 manufactured by Bruker Biospin was used for the measurements. ¹ H-NMR measurements were performed using a sample dissolved in a deuterated solvent such as CDCl ₃ at room temperature at 500 MHz with 16 accumulations. Tetramethylsilane was used as the internal standard. ¹⁹ F-NMR measurements were performed using CFCl ₃ as the internal standard with 24 accumulations. In the description of nuclear magnetic resonance spectra, s means singlet, d means doublet, t means triplet, q means quartet, quin means quintet, sex means sextet, m means multiplet, and br means broad.

Gas chromatographic analysis: A Shimadzu GC-14B gas chromatograph was used for the measurements. The carrier gas was helium (2 mL/min). The sample vaporizer was set to 280°C, and the detector (FID) was set to 300°C. To separate the component compounds, an Agilent Technologies Inc. DB-1 capillary column (length 30 m, inner diameter 0.32 mm, film thickness 0.25 μm; stationary liquid phase dimethylpolysiloxane; nonpolar) was used. The column was held at 200°C for 2 minutes and then heated to 280°C at a rate of 5°C/min. The sample was prepared as an acetone solution (0.1% by mass), and 1 μL of this solution was injected into the sample vaporizer. A Shimadzu C-R5A Chromatopac or equivalent was used as the recorder. The resulting gas chromatogram showed the retention times and peak areas of the peaks corresponding to the component compounds.

Solvents such as chloroform and hexane may be used to dilute the sample. The following capillary columns may be used to separate the component compounds: Agilent Technologies Inc.'s HP-1 (length 30 m, inner diameter 0.32 mm, film thickness 0.25 μm), Restek Corporation's Rtx-1 (length 30 m, inner diameter 0.32 mm, film thickness 0.25 μm), and SGE International Pty. Ltd.'s BP-1 (length 30 m, inner diameter 0.32 mm, film thickness 0.25 μm). Shimadzu Corporation's CBP1-M50-025 capillary column (length 50 m, inner diameter 0.25 mm, film thickness 0.25 μm) may also be used to prevent compound peak overlap.

The proportion of liquid crystal compounds contained in a composition may be calculated using the following method. A mixture of liquid crystal compounds is analyzed by gas chromatography (FID). The peak area ratio in the gas chromatogram corresponds to the proportion of liquid crystal compounds. When the capillary column described above is used, the correction coefficient for each liquid crystal compound can be considered to be 1. Therefore, the proportion (mass %) of liquid crystal compounds can be calculated from the peak area ratio.

Measurement sample: When measuring the properties of a composition or device, the composition was used as the sample as is. When measuring the properties of a compound, a measurement sample was prepared by mixing the compound (15% by mass) with mother liquid crystals (85% by mass). The compound's property value was calculated by extrapolation from the measured value. (Extrapolated value) = {(Measured value of sample) - 0.85 x (Measured value of mother liquid crystals)} / 0.15. When a smectic phase (or crystals) precipitated at 25°C at this ratio, the ratio of compound to mother liquid crystals was changed in the following order: 10% by mass:90% by mass, 5% by mass:95% by mass, and 1% by mass:99% by mass. The maximum temperature, optical anisotropy, viscosity, and dielectric anisotropy values for the compound were determined by this extrapolation method.

The following base liquid crystals were used: The proportions of the component compounds are shown in mass %.

Measurement methods: Characteristics were measured using the following methods. Many of these were methods described in the JEITA standard (JEITA ED-2521B) established by the Japan Electronics and Information Technology Industries Association (JEITA), or modified versions of these methods. No thin-film transistors (TFTs) were attached to the TN elements used for the measurements.

(1) Maximum temperature of nematic phase (NI; °C): A sample was placed on the hot plate of a melting point measurement device equipped with a polarizing microscope and heated at a rate of 1 °C/min. The temperature at which part of the sample changed from a nematic phase to an isotropic liquid was measured. The maximum temperature of the nematic phase is sometimes abbreviated as "maximum temperature."

(2) Minimum temperature of nematic phase (T _C ; °C): A sample having a nematic phase was placed in a glass bottle and stored in a freezer at 0°C, -10°C, -20°C, -30°C, and -40°C for 10 days, after which the liquid crystal phase was observed. For example, when a sample remained in a nematic phase at -20°C and changed to a crystalline or smectic phase at -30°C, T _C was recorded as <-20°C. The minimum temperature of the nematic phase is sometimes abbreviated as "minimum temperature."

(3) Viscosity (bulk viscosity; η; measured at 20°C; mPa·s): Measurement was performed using an E-type rotational viscometer manufactured by Tokyo Keiki Co., Ltd.

(4) Viscosity (rotational viscosity; γ1; measured at 25°C; mPa·s): Measurement was performed according to the method described in M. Imai et al., Molecular Crystals and Liquid Crystals, Vol. 259, 37 (1995). A sample was placed in a TN device with a twist angle of 0° and a cell gap of 5 μm between the two glass substrates. A voltage was applied to this device in steps of 0.5 V increments ranging from 16 V to 19.5 V. After a 0.2-second period without voltage application, a single rectangular wave (rectangular pulse; 0.2 seconds) and no voltage application (2 seconds) were repeated. The peak current and peak time of the transient current generated by this voltage application were measured. The rotational viscosity value was obtained from these measurements and equation (10) described on page 40 of the paper by M. Imai et al. The dielectric anisotropy value required for this calculation was determined using the element used to measure the rotational viscosity, using the method described below.

(5) Optical anisotropy (refractive index anisotropy; Δn; measured at 25°C): Measurements were performed using light with a wavelength of 589 nm using an Abbe refractometer with a polarizing plate attached to an eyepiece. After rubbing the surface of the main prism in one direction, a sample was dropped onto the main prism. The refractive index n∥ was measured when the direction of polarized light was parallel to the rubbing direction. The refractive index n⊥ was measured when the direction of polarized light was perpendicular to the rubbing direction. The optical anisotropy value was calculated using the formula Δn = n∥ - n⊥.

(6) Dielectric anisotropy (Δε; measured at 25°C): A sample was placed in a TN device with a cell gap of 9 μm between two glass substrates and a twist angle of 80 degrees. A sine wave (10 V, 1 kHz) was applied to the device, and the dielectric constant (ε∥) in the long axis direction of the liquid crystal molecules was measured after 2 seconds. A sine wave (0.5 V, 1 kHz) was applied to the device, and the dielectric constant (ε⊥) in the short axis direction of the liquid crystal molecules was measured after 2 seconds. The value of dielectric anisotropy was calculated using the formula Δε = ε∥ - ε⊥.

(7-1) Threshold voltage (Vth(25); measured at 25°C; V): Measurements were performed using an LCD5200 luminance meter manufactured by Otsuka Electronics Co., Ltd. A halogen lamp was used as the light source. A sample was placed in an FFS element with a cell gap of 3.2 μm between the two glass substrates. The voltage (32 Hz, square wave) applied to the element was increased in steps of 0.01 V from 0 V to 10 V. During this time, light was irradiated perpendicularly onto the element, and the amount of light transmitted through the element was measured. A voltage-transmittance curve was created in which the maximum amount of light represented 100% transmittance and the minimum amount represented 0% transmittance. The threshold voltage was expressed as the voltage at which transmittance reached 95%.

(7-2) Threshold voltage (Vth(-30); measured at -30°C; V): Same as (7-1) except measured at -30°C.

(8) Voltage holding ratio (VHR-1; measured at 25°C; %): The TN element used for measurement had a polyimide alignment film, and the distance between the two glass substrates (cell gap) was 5 μm. After the sample was placed into this element by vacuum injection, the injection port was sealed with an ultraviolet-curing adhesive. A pulse voltage (1 V for 60 microseconds) was applied to the TN element to charge it. The decaying voltage was measured for 166.7 milliseconds with a high-speed voltmeter, and the area A between the voltage curve and the horizontal axis in the unit cycle was calculated. Area B was the area when there was no decay. The voltage holding ratio was expressed as the percentage of area A to area B.

(9) Voltage holding ratio (VHR-2; measured at 60°C; %): The voltage holding ratio was measured using the same procedure as above, except that the temperature was 60°C instead of 25°C. The obtained value was expressed as VHR-2.

(10) Voltage holding ratio (VHR-3; measured at 60°C; %): After irradiation with ultraviolet light, the voltage holding ratio was measured to evaluate stability against ultraviolet light. The TN element used for the measurement had a polyimide alignment film and a cell gap of 5 μm. A sample was injected into this element, and ultraviolet light of 5 mW/ ^cm2 was irradiated for 167 minutes. The light source was a black light F40T10/BL (peak wavelength 369 nm) manufactured by Eye Graphics Co., Ltd., and the distance between the element and the light source was 5 mm. In measuring VHR-3, the decaying voltage was measured over a period of 166.7 milliseconds. Compositions with a large VHR-3 have high stability against ultraviolet light.

(11) Voltage holding ratio (VHR-4; measured at 60°C; %): A TN element injected with the sample was heated in a constant temperature bath at 120°C for 20 hours, after which the voltage holding ratio was measured to evaluate thermal stability. In measuring VHR-4, the voltage decay over a period of 166.7 milliseconds was measured. Compositions with a large VHR-4 have high thermal stability.

(12) Voltage holding ratio (VHR-5; measured at 60°C; %): A TN device injected with the sample was left standing above a backlight for two weeks, and then the voltage holding ratio was measured to evaluate stability against backlight. In measuring VHR-5, the voltage decayed over a period of 166.7 milliseconds. Compositions with a large VHR-5 have high stability against backlight.

(13) Response time (τ; measured at 25°C; ms): Measurements were performed using an LCD5200 luminance meter manufactured by Otsuka Electronics Co., Ltd. The light source was a halogen lamp. The low-pass filter was set to 5 kHz. The sample was placed in an FFS element with a cell gap of 3.2 μm between two glass substrates. A square wave (60 Hz, Vth(25), 0.5 sec) was applied to the element. Light was irradiated perpendicularly to the element, and the amount of light transmitted through the element was measured. The maximum amount of light was considered to be 100% transmittance, and the minimum amount of light was considered to be 0% transmittance. The rise time (τr; milliseconds) was the time required for the transmittance to change from 90% to 10%. The fall time (τf; milliseconds) was the time required for the transmittance to change from 10% to 90%. The response time is expressed as the sum of the rise time and fall time calculated in this way.

(14) Elastic constant (K; measured at 25°C; pN): Measurements were performed using a Yokogawa-Hewlett-Packard HP4284A LCR meter. A sample was placed in a horizontally aligned device with a cell gap of 20 μm between two glass substrates. A charge of 0 to 20 volts was applied to this device, and the capacitance and applied voltage were measured. The measured capacitance (C) and applied voltage (V) values were fitted using equations (2.98) and (2.101) on page 75 of the "Liquid Crystal Device Handbook" (Nikkan Kogyo Shimbun), and the values of K11 and K33 were obtained from equation (2.99). Next, K22 was calculated using equation (3.18) on page 171 of the same publication using the previously determined values of K11 and K33. The elastic constant was expressed as the average value of K11, K22, and K33 determined in this way.

(15) Specific resistance (ρ; measured at 25°C; Ωcm): 1.0 mL of sample was poured into a container equipped with electrodes. A DC voltage (10 V) was applied to the container, and the DC current was measured after 10 seconds. The specific resistance was calculated using the following formula: (Specific resistance) = {(Voltage) × (Capacity of container)} / {(DC current) × (Dielectric constant of vacuum)}.

(16) Helical pitch (P; measured at room temperature; μm): The helical pitch was measured using the wedge method. See "Liquid Crystal Handbook," p. 196 (published in 2000 by Maruzen). The sample was poured into a wedge-shaped cell and allowed to stand at room temperature for two hours. The distance between the disclination lines (d2 - d1) was then observed using a polarizing microscope (Nikon Corporation, product name MM40/60 series). The helical pitch (P) was calculated using the following formula, where the angle of the wedge cell is represented as θ: P = 2 x (d2 - d1) x tan θ.

(17) Dielectric constant in the minor axis direction (ε⊥; measured at 25°C): A sample was placed in a TN device with a cell gap of 9 μm between two glass substrates and a twist angle of 80 degrees. A sine wave (0.5 V, 1 kHz) was applied to this device, and the dielectric constant (ε⊥) in the minor axis direction of the liquid crystal molecules was measured after 2 seconds.

(18) Frequency dependence of dielectric anisotropy (F10; measured at -20°C): A sample was placed in a TN device with a cell gap of 9 μm between two glass substrates and a twist angle of 80 degrees. A sine wave (0.5 V, 20 Hz, 50 Hz, 100 Hz, 1 kHz, 5 kHz, 10 kHz, 50 kHz, 100 kHz, 500 kHz, and 1000 kHz) was applied to this device, and the dielectric constant (ε⊥) in the minor axis direction of the liquid crystal molecules was measured after 2 seconds. F10 was defined as the frequency at which the dielectric anisotropy decreased by 10% compared to the dielectric anisotropy at 20 Hz. A larger F10 indicates smaller frequency dependence.

Examples of compositions are shown below. Component compounds are represented by symbols based on the definitions in Table 3 below. In Table 3, the configuration for 1,4-cyclohexylene is trans. The number in parentheses after each symbolized compound indicates the chemical formula to which the compound belongs. The symbol (-) indicates other liquid crystal compounds. The proportion (percentage) of the liquid crystal compound is the mass percentage (mass %) based on the mass of the liquid crystal composition without additives. Finally, the property values of the compositions are summarized.

[Comparative Example 1]
A composition not containing compound (1) was prepared.
3-BB(F)B(F,F)-CF3 (2-2) 5%
3-BB(F)B(F,F)XB(F,F)-F (2-6) 3%
4-BB(F)B(F,F)XB(F,F)-F (2-6) 7%
3-HH-V (3-1) 38%
3-HH-V1 (3-1) 7%
V2-BB-1 (3-3) 6%
V-HBB-2 (3-6) 6%
1-BB(F)B-2V (3-8) 8%
2-BB(F)B-2V (3-8) 11%
3-BB(F)B-2V (3-8) 9%
NI=82.0°C; Tc<-10°C;Δn=0.147;Δε=3.3; γ1=47.0 mPa·s; τ=16.5ms; VHR-1=99.5%.

[Comparative Example 2]
A composition containing no compound (1) but a cyano compound other than compound (1) was prepared.
1V2-BEB(F,F)-C (-) 5%
3-BB(F)B(F,F)-CF3 (2-2) 3%
3-HH-V (3-1) 39%
3-HH-V1 (3-1) 7%
V2-BB-1 (3-3) 3%
V-HBB-2 (3-6) 6%
2-BB(F)B-3 (3-8) 6%
2-BB(F)B-5 (3-8) 6%
1-BB(F)B-2V (3-8) 8%
2-BB(F)B-2V (3-8) 11%
3-BB(F)B-2V (3-8) 6%
NI=81.4°C; Δn=0.147; Δε=3.1; VHR-1=70.0%.

[Example 1]
3-BB(F)B(F,F)-C (1-6) 5%
3-BB(F)B(F,F)-CF3 (2-2) 4%
3-BB(F)B(F,F)XB(F,F)-F (2-6) 2%
3-HH-V (3-1) 39%
3-HH-V1 (3-1) 7%
V2-BB-1 (3-3) 8%
V-HBB-2 (3-6) 6%
1-BB(F)B-2V (3-8) 8%
2-BB(F)B-2V (3-8) 11%
3-BB(F)B-2V (3-8) 10%
NI=79.8°C; Tc<-10°C;Δn=0.148;Δε=3.2; γ1=42.3 mPa·s; τ=14.6ms; VHR-1=99.0%.

[Example 2]
3-BB(F)B-C (1-1) 5%
3-BB(F)B(F,F)-CF3 (2-2) 4%
3-BB(F)B(F,F)XB(F,F)-F (2-6) 3%
4-BB(F)B(F,F)XB(F,F)-F (2-6) 3%
3-HH-V (3-1) 39%
3-HH-V1 (3-1) 7%
V2-BB-1 (3-3) 8%
V-HBB-2 (3-6) 6%
1-BB(F)B-2V (3-8) 8%
2-BB(F)B-2V (3-8) 11%
3-BB(F)B-2V (3-8) 6%
NI=81.1°C; Tc<-10°C;Δn=0.148;Δε=3.4; γ1=45.6 mPa·s; τ=15.6 ms; VHR-1=99.4%.

The results of Comparative Example 1, Comparative Example 2, Example 1, and Example 2 are summarized in Table 4.

It can be seen that the compositions of Examples 1 and 2 have a smaller rotational viscosity (γ1) and a shorter response time (τ) than the composition of Comparative Example 1, and a larger voltage holding ratio (VHR-1) than the composition of Comparative Example 2. It can also be seen that the compositions of Examples 1 and 2, despite containing a cyano compound, have a voltage holding ratio equivalent to that of the composition of Comparative Example 1, which does not contain a cyano compound.

[Example 3]
3-BBB(F)-C (1-3) 2%
3-BB(F)B(F,F)-CF3 (2-2) 4%
3-BB(F)B(F,F)XB(F,F)-F (2-6) 3%
4-BB(F)B(F,F)XB(F,F)-F (2-6) 6%
3-HH-V (3-1) 39%
3-HH-V1 (3-1) 6%
V2-BB-1 (3-3) 8%
V-HBB-2 (3-6) 6%
1-BB(F)B-2V (3-8) 8%
2-BB(F)B-2V (3-8) 11%
3-BB(F)B-2V (3-8) 7%
NI=80.6°C; Tc<0°C;Δn=0.146;Δε=3.6; γ1=45.6 mPa·s; τ=15.5ms; VHR-1=99.1%.

[Example 4]
3-BBB(F,F)-C (1-5) 2%
3-BB(F)B(F,F)-CF3 (2-2) 4%
3-BB(F)B(F,F)XB(F,F)-F (2-6) 3%
4-BB(F)B(F,F)XB(F,F)-F (2-6) 5%
3-HH-V (3-1) 39%
3-HH-V1 (3-1) 6%
V2-BB-1 (3-3) 8%
V-HBB-2 (3-6) 6%
1-BB(F)B-2V (3-8) 8%
2-BB(F)B-2V (3-8) 11%
3-BB(F)B-2V (3-8) 8%
NI=80.4°C; Tc<-10°C;Δn=0.148;Δε=3.4; γ1=43.3 mPa·s; τ=15.0 ms; VHR-1=98.9%.

[Example 5]
5-BBB(F,F)-C (1-5) 5%
3-BB(F)B(F,F)-CF3 (2-2) 4%
3-BB(F)B(F,F)XB(F,F)-F (2-6) 4%
3-HH-V (3-1) 39%
3-HH-V1 (3-1) 8%
V2-BB-1 (3-3) 8%
V-HBB-2 (3-6) 5%
1-BB(F)B-2V (3-8) 8%
2-BB(F)B-2V (3-8) 11%
3-BB(F)B-2V (3-8) 8%
NI=80.4°C; Tc<0°C;Δn=0.147;Δε=3.4; γ1=41.8 mPa·s; τ=14.5ms; VHR-1=99.0%.

[Example 6]
3-BB(F)B(F)-C (1-4) 5%
3-BB(F)B(F,F)-CF3 (2-2) 4%
3-BB(F)B(F,F)XB(F,F)-F (2-6) 4%
3-HH-V (3-1) 40%
3-HH-V1 (3-1) 7%
V2-BB-1 (3-3) 7%
V-HBB-2 (3-6) 6%
1-BB(F)B-2V (3-8) 8%
2-BB(F)B-2V (3-8) 11%
3-BB(F)B-2V (3-8) 8%
NI=81.1°C; Tc<-10°C;Δn=0.146;Δε=3.2; γ1=42.3 mPa·s; τ=15.2 ms; VHR-1=99.0%.

[Example 7]
3-BB(F)B(F)-C (1-4) 5%
3-BB(F)B(F,F)-CF3 (2-2) 4%
3-BB(F)B(F,F)XB(F,F)-F (2-6) 3%
3-HH-V (3-1) 43%
3-HH-V1 (3-1) 6%
V2-BB-1 (3-3) 2%
1V2-BB-1 (3-3) 6%
V-HBB-2 (3-6) 5%
1-BB(F)B-2V (3-8) 8%
2-BB(F)B-2V (3-8) 12%
1-B2BB-2V (3-9) 6%
NI=78.9°C; Δn=0.142; Δε=2.6; γ1=42.0 mPa·s; τ=14.9ms; VHR-1=99.0%.

[Example 8]
3-BB(F)B(F)-C (1-4) 5%
3-BB(F)B(F,F)-CF3 (2-2) 4%
3-BB(F)B(F,F)XB(F,F)-F (2-6) 3%
3-HH-V (3-1) 40%
3-HH-V1 (3-1) 6%
V2-BB-1 (3-3) 2%
1V2-BB-1 (3-3) 6%
V-HBB-2 (3-6) 5%
1-BB(F)B-2V (3-8) 8%
2-BB(F)B-2V (3-8) 12%
1-B2BB-2V (3-9) 6%
3-dhBB(F,F)XB(F,F)-F (4-21) 3%
NI=81.5°C; Δn=0.145; Δε=3.3; γ1=45.0 mPa·s; τ=15.8 ms; VHR-1=99.0%.

[Example 9]
3-BB(F)B(F)-C (1-4) 4%
1-BB(F)B(F,F)-C (1-6) 1%
3-BB(F)B(F,F)-CF3 (2-2) 4%
3-BB(F)B(F,F)XB(F,F)-F (2-6) 3%
4-BB(F)B(F,F)XB(F,F)-F (2-6) 3%
3-HH-V (3-1) 39%
3-HH-V1 (3-1) 7%
V2-BB-1 (3-3) 8%
V-HBB-2 (3-6) 6%
1-BB(F)B-2V (3-8) 8%
2-BB(F)B-2V (3-8) 11%
3-BB(F)B-2V (3-8) 6%
NI=80.8°C; Δn=0.149; Δε=4.4; γ1=46.0 mPa·s; τ=16.1 ms; VHR-1=99.0%.

[Example 10]
3-BB(F)B(F)-C (1-4) 6%
3-BB(F)B(F,F)XB(F,F)-F (2-6) 4%
4-BB(F)B(F,F)XB(F,F)-F (2-6) 4%
3-HH-V (3-1) 45%
V2-BB-1 (3-3) 8%
1-BB-3 (3-3) 4%
1-BB(F)B-2V (3-8) 11%
2-BB(F)B-2V (3-8) 10%
3-BB(F)B-2V (3-8) 8%
NI=75.7°C; Δn=0.150; Δε=3.4; γ1=43.4 mPa·s; τ=15.2 ms; VHR-1=99.0%.

[Example 11]
3-BB(F)B-C (1-1) 3%
3-BB (2F) B-C (1-2) 2%
3-BB(F)B(F,F)-CF3 (2-2) 4%
3-BB(F)B(F,F)XB(F,F)-F (2-6) 3%
4-BB(F)B(F,F)XB(F,F)-F (2-6) 3%
3-HH-V (3-1) 39%
3-HH-V1 (3-1) 7%
V2-BB-1 (3-3) 8%
V-HBB-2 (3-6) 6%
1-BB(F)B-2V (3-8) 8%
2-BB(F)B-2V (3-8) 11%
3-BB(F)B-2V (3-8) 6%
NI=82.3°C; Δn=0.148; Δε=3.4; γ1=46.0 mPa·s; τ=15.8 ms; VHR-1=99.1%.

[Example 12]
3-BB(F)B-C (1-1) 5%
3-BB(F)B(F,F)-CF3 (2-2) 4%
3-BB(F,F)XB(F,F)-F (2-4) 2%
3-BB(F)B(F,F)XB(F,F)-F (2-6) 4%
3-HH-V (3-1) 39%
3-HH-V1 (3-1) 6%
V2-BB-1 (3-3) 8%
V-HBB-2 (3-6) 6%
1-BB(F)B-2V (3-8) 9%
2-BB(F)B-2V (3-8) 11%
3-BB(F)B-2V (3-8) 6%
NI=80.9°C; Δn=0.148; Δε=3.3; γ1=46.0 mPa·s; τ=15.8 ms; VHR-1=99.3%.

[Example 13]
3-BB(F)B-C (1-1) 5%
3-BB(F)B(F,F)-F (2-1) 2%
3-BB(F)B(F,F)-CF3 (2-2) 4%
3-BB(F)B(F,F)XB(F,F)-F (2-6) 4%
3-HH-V (3-1) 39%
3-HH-V1 (3-1) 7%
V2-BB-1 (3-3) 8%
V-HBB-2 (3-6) 6%
1-BB(F)B-2V (3-8) 8%
2-BB(F)B-2V (3-8) 11%
3-BB(F)B-2V (3-8) 6%
NI=81.2°C; Δn=0.148; Δε=3.3; γ1=46.0 mPa·s; τ=15.8 ms; VHR-1=99.3%.

It can be seen that the compositions of Examples 3 to 13 also have a smaller rotational viscosity (γ1) and shorter response time (τ) than the composition of Comparative Example 1, and a larger voltage holding ratio (VHR-1) than the composition of Comparative Example 2.

The liquid crystal composition of the present invention can be used in LCD monitors, LCD televisions, etc.

Claims (14)

A liquid crystal composition having positive dielectric anisotropy, comprising as component A at least one compound selected from compounds represented by formula (1), as component B at least one compound selected from compounds represented by formula (2), and as component C at least one compound selected from compounds represented by formula (3), wherein the proportion of component C is in the range of 20% by mass to 90% by mass, and the composition does not contain a polymerizable compound or a polymer.


In formula (1), R ¹ is hydrogen, alkyl having 1 to 12 carbon atoms, alkoxy having 1 to 12 carbon atoms, alkenyl having 2 to 12 carbon atoms, alkenyloxy having 2 to 12 carbon atoms, or alkyl having 1 to 12 carbon atoms in which at least one hydrogen is replaced by fluorine or chlorine; X ¹ , X ² , X ³ , X ⁴ , and X ⁵ are hydrogen or fluorine, and at least one of X ¹ , X ² , X ³ , X ⁴ , and X ⁵ is fluorine;
In formula (2), R ² is alkyl having 1 to 12 carbon atoms, alkoxy having 1 to 12 carbon atoms, or alkenyl having 2 to 12 carbon atoms; ring A ¹ and ring A ² are 1,4-phenylene, 2-fluoro-1,4-phenylene, 2,3-difluoro-1,4-phenylene, or 2,6-difluoro-1,4-phenylene; Z ¹ and Z ² are a single bond, ethylene, vinylene, methyleneoxy, carbonyloxy, or difluoromethyleneoxy; X ⁶ and X ⁷ are hydrogen or fluorine; Y ¹ is fluorine, chlorine, alkyl having 1 to 12 carbon atoms in which at least one hydrogen is replaced with fluorine or chlorine, alkoxy having 1 to 12 carbon atoms in which at least one hydrogen is replaced with fluorine or chlorine, or alkenyloxy having 2 to 12 carbon atoms in which at least one hydrogen is replaced with fluorine or chlorine; m is 1, 2, or 3;
In formula (3), R ³ and R ⁴ are alkyl having 1 to 12 carbon atoms, alkoxy having 1 to 12 carbon atoms, alkenyl having 2 to 12 carbon atoms, or alkenyl having 2 to 12 carbon atoms in which at least one hydrogen is replaced by fluorine or chlorine; ring B and ring C are 1,4-cyclohexylene, 1,4-phenylene, 2-fluoro-1,4-phenylene, or 2,5-difluoro-1,4-phenylene; Z ³ is a single bond, ethylene, vinylene, methyleneoxy, or carbonyloxy; and n is 1, 2, or 3. 2. The liquid crystal composition according to claim 1, comprising, as component A, at least one compound selected from the compounds represented by formulas (1-1) to (1-6):


In formulas (1-1) to (1-6), R ¹ is hydrogen, alkyl having 1 to 12 carbon atoms, alkoxy having 1 to 12 carbon atoms, alkenyl having 2 to 12 carbon atoms, alkenyloxy having 2 to 12 carbon atoms, or alkyl having 1 to 12 carbon atoms in which at least one hydrogen is replaced by fluorine or chlorine. The liquid crystal composition according to claim 1 or 2, wherein the proportion of component A is in the range of 1% by mass to 50% by mass. 4. The liquid crystal composition according to claim 1, comprising, as component B, at least one compound selected from the compounds represented by formulas (2-1) to (2-11):



In formulas (2-1) to (2-11), R ² is alkyl having 1 to 12 carbon atoms, alkoxy having 1 to 12 carbon atoms, or alkenyl having 2 to 12 carbon atoms. The liquid crystal composition according to any one of claims 1 to 4, wherein the proportion of component B is in the range of 1% by mass to 50% by mass. 6. The liquid crystal composition according to claim 1, comprising, as component C, at least one compound selected from the compounds represented by formulas (3-1) to (3-13):


In formulas (3-1) to (3-13), R ³ and R ⁴ are alkyl having 1 to 12 carbon atoms, alkoxy having 1 to 12 carbon atoms, alkenyl having 2 to 12 carbon atoms, or alkenyl having 2 to 12 carbon atoms in which at least one hydrogen is replaced by fluorine or chlorine. The liquid crystal composition according to claim 1 , comprising, as component D, at least one compound selected from the group of compounds represented by formula (4):


In formula (4), R ⁵ is alkyl having 1 to 12 carbon atoms, alkoxy having 1 to 12 carbon atoms, or alkenyl having 2 to 12 carbon atoms; ring D is 1,4-cyclohexylene, 1,4-phenylene, 2-fluoro-1,4-phenylene, 2,3-difluoro-1,4-phenylene, 2,6-difluoro-1,4-phenylene, pyrimidine-2,5-diyl, 1,3-dioxane-2,5-diyl, or tetrahydropyran-2,5-diyl, and at least one of rings D is 1,4-cyclohexylene, pyrimidine-2,5-diyl, 1,3-dioxane-2,5-diyl, or tetrahydropyran-2,5-diyl; Z ⁴ is a single bond, ethylene, vinylene, methyleneoxy, carbonyloxy, or difluoromethyleneoxy; X ⁸ and X ⁹ is hydrogen or fluorine; ^Y2 is fluorine, chlorine, alkyl having 1 to 12 carbon atoms in which at least one hydrogen is replaced by fluorine or chlorine, alkoxy having 1 to 12 carbon atoms in which at least one hydrogen is replaced by fluorine or chlorine, or alkenyloxy having 2 to 12 carbon atoms in which at least one hydrogen is replaced by fluorine or chlorine; and a is 1, 2, 3, or 4. 8. The liquid crystal composition according to claim 1 , comprising, as component D, at least one compound selected from the group of compounds represented by formulas (4-1) to (4-24):




In formulas (4-1) to (4-24), R ⁵ is alkyl having 1 to 12 carbon atoms, alkoxy having 1 to 12 carbon atoms, or alkenyl having 2 to 12 carbon atoms. 9. The liquid crystal composition according to claim 7 , wherein the proportion of component D is in the range of 1% by mass to 50% by mass. 10. The liquid crystal composition according to claim 1 , which has a nematic phase at least in the range of 0°C to 60°C. 11. The liquid crystal composition according to claim 1, wherein the maximum temperature of a nematic phase is 60°C or higher, the optical anisotropy at a wavelength of 589 nm (measured at 25°C) is 0.07 or higher, and the dielectric anisotropy at a frequency of 1 kHz (measured at 25°C) is 2.0 or higher. A liquid crystal display device comprising the liquid crystal composition according to claim 1 . 13. The liquid crystal display element according to claim 12 , wherein the operation mode of the liquid crystal display element is TN mode, ECB mode, OCB mode, IPS mode, FFS mode, or FPA mode, and the driving method of the liquid crystal display element is an active matrix method. Use of the liquid crystal composition according to any one of claims 1 to 11 in a liquid crystal display device.