Liquid crystal composition and liquid crystal display device

Abstract

Provided are a liquid crystal composition satisfying at least one of characteristics such as high maximum temperature, low minimum temperature, small viscosity, suitable optical anisotropy and large dielectric anisotropy, or the liquid crystal composition having a suitable balance regarding at least two of the characteristics; and an AM device including the composition. The liquid crystal composition contains a specific compound having small optical anisotropy as a first component, and a specific compound having positive dielectric anisotropy as a second component, and may contain a specific compound having high maximum temperature or small viscosity as a third component, a specific compound having positive dielectric anisotropy as a fourth component, or a specific compound having negative dielectric anisotropy as a fifth component.

Claims

1. A liquid crystal composition that has a nematic phase, and contains at least one compound selected from the group of compounds represented by formula (1) as a first component, and at least one compound selected from the group of compounds represented by formula (2) as a second component: ##STR00037## wherein, in formula (1) and formula (2), R.sup.1 is alkyl having 1 to 12 carbons in which at least one methylene is replaced by oxygen, or alkenyl having 2 to 12 carbons in which at least one methylene is replaced by oxygen; R.sup.2 is 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; R.sup.3 is alkyl having 1 to 12 carbons, alkoxy having 1 to 12 carbons or alkenyl having 2 to 12 carbons, ring A and ring B are independently 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; Z.sup.1 and Z.sup.2 are independently a single bond, ethylene, vinylene, carbonyloxy or methyleneoxy; Z.sup.3 and Z.sup.4 are independently a single bond, ethylene, carbonyloxy or difluoromethyleneoxy; X.sup.1 and X.sup.2 are independently hydrogen or fluorine; Y.sup.1 is fluorine, chlorine, alkyl having 1 to 12 carbons in which at least one hydrogen is replaced by fluorine or chlorine, alkoxy having 1 to 12 carbons in which at least one hydrogen is replaced by fluorine or chlorine, or alkenyloxy having 2 to 12 carbons in which at least one hydrogen is replaced by fluorine or chlorine; a and b are independently 0 or 1; c is 1, 2, 3 or 4, d is 0, 1, 2 or 3, and a sum of c and d is 4 or less.

2. The liquid crystal composition according to claim 1, containing at least one compound selected from the group of compounds represented by formula (1-1) to formula (1-6) as the first component: ##STR00038## wherein, in formula (1-1) to formula (1-6), R.sup.1 is alkyl having 1 to 12 carbons in which at least one methylene is replaced by oxygen, or alkenyl having 2 to 12 carbons in which at least one methylene is replaced by oxygen; and R.sup.2 is 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.

3. The liquid crystal composition according to claim 1, containing at least one compound selected from the group of compounds represented by formula (2-1) to formula (2-14) as the second component: ##STR00039## ##STR00040## wherein, in formula (2-1) to formula (2-14), R.sup.3 is alkyl having 1 to 12 carbons, alkoxy having 1 to 12 carbons or alkenyl having 2 to 12 carbons; X.sup.1, X.sup.2, X.sup.3, X.sup.4, X.sup.5, X.sup.6, X.sup.7, X.sup.8, X.sup.9, X.sup.10, X.sup.11, X.sup.12, X.sup.13 and X.sup.14 are independently hydrogen or fluorine; Y.sup.1 is fluorine, chlorine, alkyl having 1 to 12 carbons in which at least one hydrogen is replaced by fluorine or chlorine, alkoxy having 1 to 12 carbons in which at least one hydrogen is replaced by fluorine or chlorine, or alkenyloxy having 2 to 12 carbons in which at least one hydrogen is replaced by fluorine or chlorine.

4. The liquid crystal composition according to claim 1, wherein a proportion of the first component is in the range of 3% by weight to 40% by weight, and a proportion of the second component is in the range of 10% by weight to 60% by weight, based on the weight of the liquid crystal composition.

5. The liquid crystal composition according to claim 1, containing at least one compound selected from the group of compounds represented by formula (3) as a third component: ##STR00041## wherein, in formula (3), R.sup.4 and R.sup.5 are independently 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; ring C and ring D are independently 1,4-cyclohexylene, 1,4-phenylene, 2-fluoro-1,4-phenylene or 2,5-difluoro-1,4-phenylene; Z.sup.5 is a single bond, ethylene or carbonyloxy; e is 1, 2 or 3; in which, a compound represented by formula (1) is excluded.

6. The liquid crystal composition according to claim 5, containing at least one compound selected from the group of compounds represented by formula (3-1) to formula (3-13) as the third component: ##STR00042## ##STR00043## wherein, in formula (3-1) to formula (3-13), R.sup.4 and R.sup.5 are independently alkyl having 1 to 12 carbons, alkoxy having 1 to 12 carbons, alkenyl having 2 to 12 carbons, alkyl having 1 to 12 carbons in which at least one hydrogen is replaced by fluorine or chlorine, or alkenyl having 2 to 12 carbons in which at least one hydrogen is replaced by fluorine or chlorine.

7. The liquid crystal composition according to claim 5, wherein a proportion of the third component is in the range of 10% by weight to 70% by weight based on the weight of the liquid crystal composition.

8. The liquid crystal composition according to claim 1, containing at least one compound selected from the group of compounds represented by formula (4): ##STR00044## wherein, in formula (4), R.sup.6 is alkyl having 1 to 12 carbons, alkoxy having 1 to 12 carbons or alkenyl having 2 to 12 carbons; ring E 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; Z.sup.6 is a single bond, ethylene or carbonyloxy; X.sup.15 and X.sup.16 are independently hydrogen or fluorine; Y.sup.2 is fluorine, chlorine, alkyl having 1 to 12 carbons in which at least one hydrogen is replaced by fluorine or chlorine, alkoxy having 1 to 12 carbons in which at least one hydrogen is replaced by fluorine or chlorine, or alkenyloxy having 2 to 12 carbons in which at least one hydrogen is replaced by fluorine or chlorine; and f is 1, 2, 3 or 4.

9. The liquid crystal composition according to claim 5, containing at least one compound selected from the group of compounds represented by formula (4): ##STR00045## wherein, in formula (4), R.sup.6 is alkyl having 1 to 12 carbons, alkoxy having 1 to 12 carbons or alkenyl having 2 to 12 carbons; ring E 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; Z.sup.6 is a single bond, ethylene or carbonyloxy; X.sup.15 and X.sup.16 are independently hydrogen or fluorine; Y.sup.2 is fluorine, chlorine, alkyl having 1 to 12 carbons in which at least one hydrogen is replaced by fluorine or chlorine, alkoxy having 1 to 12 carbons in which at least one hydrogen is replaced by fluorine or chlorine, or alkenyloxy having 2 to 12 carbons in which at least one hydrogen is replaced by fluorine or chlorine; and f is 1, 2, 3 or 4.

10. The liquid crystal composition according to claim 8, containing at least one compound selected from the group of compounds represented by formula (4-1) to formula (4-16): ##STR00046## ##STR00047## wherein, in formula (4-1) to formula (4-16), R.sup.6 is alkyl having 1 to 12 carbons, alkoxy having 1 to 12 carbons or alkenyl having 2 to 12 carbons.

11. The liquid crystal composition according to claim 8, wherein a proportion of the compound represented by formula (4) is in the range of 5% by weight to 40% by weight based on the weight of the liquid crystal composition.

12. The liquid crystal composition according to claim 1, containing at least one compound selected from the group of compounds represented by formula (5): ##STR00048## wherein, in formula (5), R.sup.7 and R.sup.8 are independently 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; ring G and ring J are independently 1,4-cyclohexylene, 1,4-cyclohexenylene, 1,4-phenylene, 1,4-phenylene in which at least one hydrogen is replaced by fluorine or chlorine, or tetrahydropyran-2,5-diyl; ring I 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 or 7,8-difluorochroman-2,6-diyl; Z.sup.7 and Z.sup.8 are independently a single bond, ethylene, carbonyloxy or methyleneoxy; and g is 1, 2 or 3, h is 0 or 1, and a sum of g and his 3 or less.

13. The liquid crystal composition according to claim 5, containing at least one compound selected from the group of compounds represented by formula (5): ##STR00049## wherein, in formula (5), R.sup.7 and R.sup.8 are independently 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; ring G and ring J are independently 1,4-cyclohexylene, 1,4-cyclohexenylene, 1,4-phenylene, 1,4-phenylene in which at least one hydrogen is replaced by fluorine or chlorine, or tetrahydropyran-2,5-diyl; ring I 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 or 7,8-difluorochroman-2,6-diyl; Z.sup.7 and Z.sup.8 are independently a single bond, ethylene, carbonyloxy or methyleneoxy; and g is 1, 2 or 3, h is 0 or 1, and a sum of g and h is 3 or less.

14. The liquid crystal composition according to claim 8, containing at least one compound selected from the group of compounds represented by formula (5): ##STR00050## wherein, in formula (5), R.sup.7 and R.sup.8 are independently 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; ring G and ring J are independently 1,4-cyclohexylene, 1,4-cyclohexenylene, 1,4-phenylene, 1,4-phenylene in which at least one hydrogen is replaced by fluorine or chlorine, or tetrahydropyran-2,5-diyl; ring I 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 or 7,8-difluorochroman-2,6-diyl; Z.sup.7 and Z.sup.8 are independently a single bond, ethylene, carbonyloxy or methyleneoxy; and g is 1, 2 or 3, h is 0 or 1, and a sum of g and h is 3 or less.

15. The liquid crystal composition according to claim 9, containing at least one compound selected from the group of compounds represented by formula (5): ##STR00051## wherein, in formula (5), R.sup.7 and R.sup.8 are independently 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; ring G and ring J are independently 1,4-cyclohexylene, 1,4-cyclohexenylene, 1,4-phenylene, 1,4-phenylene in which at least one hydrogen is replaced by fluorine or chlorine, or tetrahydropyran-2,5-diyl; ring I 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 or 7,8-difluorochroman-2,6-diyl; Z.sup.7 and Z.sup.8 are independently a single bond, ethylene, carbonyloxy or methyleneoxy; and g is 1, 2 or 3, h is 0 or 1, and a sum of g and h is 3 or less.

16. The liquid crystal composition according to claim 12, containing at least one compound selected from the group of compounds represented by formula (5-1) to formula (5-22): ##STR00052## ##STR00053## ##STR00054## wherein, in formula (5-1) to formula (5-22), R.sup.7 and R.sup.8 are independently 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.

17. The liquid crystal composition according to claim 12, wherein a proportion of the compound represented by formula (5) is in the range of 2% by weight to 30% by weight based on the weight of the liquid crystal composition.

18. The liquid crystal composition according to claim 1, wherein a maximum temperature of a nematic phase is 70 C. or higher, an optical anisotropy measured at 25 C. at a wavelength of 589 nanometers is 0.07 or more and a dielectric anisotropy measured at 25 C. at a frequency of 1 kHz is 2 or more.

19. A liquid crystal display device, including the liquid crystal composition according to claim 1.

20. The liquid crystal display device according to claim 19, wherein an operating mode in the liquid crystal display device includes a TN mode, an ECB mode, an OCB mode, an IPS mode, an FFS mode or an FPA mode, and a driving mode in the liquid crystal display device includes an active matrix mode.

Description

EXAMPLES

(1) The invention will be described in greater detail by way of Examples. However, the invention is not limited by the Examples. The invention includes a mixture of a composition in Example 1 and a composition in Example 2. The invention also includes a mixture in which at least two compositions in Examples were mixed. The thus prepared compound was identified by methods such as an NMR analysis. Characteristics of the compound and the composition were measured by methods described below.

(2) NMR analysis: For measurement, DRX-500 made by Bruker BioSpin Corporation was used. In .sup.1H-NMR measurement, a sample was dissolved in a deuterated solvent such as CDCl.sub.3, and measurement was carried out under conditions of room temperature, 500 MHz and 16 times of accumulation. Tetramethylsilane was used as an internal standard. In .sup.19F-NMR measurement, CFCl.sub.3 was used as an internal standard, and measurement was carried out under conditions of 24 times of accumulation. In explaining nuclear magnetic resonance spectra obtained, s, d, t, q, quin, sex and m stand for a singlet, a doublet, a triplet, a quartet, a quintet, a sextet and a multiplet, and br being broad, respectively.

(3) Gas chromatographic analysis: For measurement, GC-14B Gas Chromatograph made by Shimadzu Corporation was used. A carrier gas was helium (2 mL per minute). A sample vaporizing chamber and a detector (FID) were set to 280 C. and 300 C., respectively. A capillary column DB-1 (length 30 m, bore 0.32 mm, film thickness 0.25 m; dimethylpolysiloxane as a stationary liquid phase; non-polar) made by Agilent Technologies, Inc. was used for separation of component compounds. After the column was kept at 200 C. for 2 minutes, the column was heated to 280 C. at a rate of 5 C. per minute. A sample was prepared in an acetone solution (0.1% by weight), and then 1 microliter of the solution was injected into the sample vaporizing chamber. A recorder was C-R5A Chromatopac made by Shimadzu Corporation or the equivalent thereof. The resulting gas chromatogram showed a retention time of a peak and a peak area corresponding to each of the component compounds.

(4) As a solvent for diluting the sample, chloroform, hexane or the like may also be used. The following capillary columns may also be used for separating component compounds: HP-1 (length 30 m, bore 0.32 mm, film thickness 0.25 m) made by Agilent Technologies, Inc., Rtx-1 (length 30 m, bore 0.32 mm, film thickness 0.25 m) made by Restek Corporation and BP-1 (length m, bore 0.32 mm, film thickness 0.25 m) made by SGE International Pty. Ltd. A capillary column CBP1-M50-025 (length 50 m, bore 0.25 mm, film thickness 0.25 m) made by Shimadzu Corporation may also be used for the purpose of preventing an overlap of peaks of the compounds.

(5) A proportion of liquid crystal compounds contained in the composition may be calculated by the method as described below. The mixture of liquid crystal compounds is detected by gas chromatograph (FID). An area ratio of each peak in the gas chromatogram corresponds to the ratio (weight ratio) of the liquid crystal compound. When the capillary columns described above were used, a correction coefficient of each of the liquid crystal compounds may be regarded as 1 (one). Accordingly, the proportion (% by weight) of the liquid crystal compounds can be calculated from the area ratio of each peak.

(6) Sample for measurement: When characteristics of a composition were measured, the composition was used as a sample as was. Upon measuring characteristics of a compound, a sample for measurement was prepared by mixing the compound (15% by weight) with a base liquid crystal (85% by weight). Values of characteristics of the compound were calculated, according to an extrapolation method, using values obtained by measurement. (Extrapolated value)={(measured value of a sample)0.85(measured value of abase liquid crystal)}/0.15. When a smectic phase (or crystals) precipitates at the ratio thereof at 25 C., a ratio of the compound to the base liquid crystal was changed step by step in the order of (10% by weight:90% by weight), (5% by weight:95% by weight) and (1% by weight:99% by weight). Values of maximum temperature, optical anisotropy, viscosity and dielectric anisotropy with regard to the compound were determined according to the extrapolation method.

(7) A base liquid crystal described below was used. A proportion of the component compound was expressed in terms of weight percent (% by weight).

(8) ##STR00020##

(9) Measuring method: Characteristics were measured according to the methods described below. Most of the measuring methods are applied as described in the Standard of Japan Electronics and Information Technology Industries Association (hereinafter abbreviated as JEITA) (JEITA ED-2521B) discussed and established by JEITA, or modified thereon. No thin film transistor (TFT) was attached to a TN device used for measurement.

(10) (1) Maximum temperature of nematic phase (NI; C.): A sample was placed on a hot plate in a melting point apparatus equipped with a polarizing microscope, and heated at a rate of 1 C. per minute. Temperature when part of the sample began to change from a nematic phase to an isotropic liquid was measured.

(11) (2) Minimum temperature of nematic phase (T.sub.C; C.): Samples each having a nematic phase were put in glass vials and kept in freezers at temperatures of 0 C., 10 C., 20 C., 30 C. and 40 C. for 10 days, and then liquid crystal phases were observed. For example, when the sample maintained the nematic phase at 20 C. and changed to crystals or a smectic phase at 30 C., T.sub.c was expressed as T.sub.c<20 C.

(12) (3) Viscosity (bulk viscosity; ; measured at 20 C.; mPa.Math.s): For measurement, a cone-plate (E type) rotational viscometer made by Tokyo Keiki Inc. was used.

(13) (4) Viscosity (rotational viscosity; 1; measured at 25 C.; mPa.Math.s): Measurement was carried out according to a method described in M. Imai et al., Molecular Crystals and Liquid Crystals, Vol. 259, p. 37 (1995). A sample was put in a TN device in which a twist angle was 0 degrees and a distance (cell gap) between two glass substrates was 5 micrometers. Voltage was applied stepwise to the device in the range of 16 V to 19.5 V at an increment of 0.5 V. After a period of 0.2 second with no voltage application, voltage was repeatedly applied under conditions of only one rectangular wave (rectangular pulse; 0.2 second) and no voltage application (2 seconds). A peak current and a peak time of transient current generated by the applied voltage were measured. A value of rotational viscosity was obtained from the measured values and calculation equation (8) described on page 40 of the paper presented by M. Imai et al. A value of dielectric anisotropy required for the calculation was determined using the device by which the rotational viscosity was measured and by a method described below.

(14) (5) Optical anisotropy (refractive index anisotropy; n; measured at 25 C.): Measurement was carried out by an Abbe refractometer with a polarizing plate mounted on an ocular, using light at a wavelength of 589 nanometers. A surface of a main prism was rubbed in one direction, and then a sample was added dropwise onto the main prism. A refractive index (n) was measured when a direction of polarized light was parallel to a direction of rubbing. A refractive index (n) was measured when the direction of polarized light was perpendicular to the direction of rubbing. A value of optical anisotropy was calculated from an equation: n=nn.

(15) (6) Dielectric anisotropy (; measured at 25 C.): A sample was put in a TN device in which a distance (cell gap) between two glass substrates was 9 micrometers and a twist angle was 80 degrees. Sine waves (10 V, 1 kHz) were applied to the device, and after 2 seconds, a dielectric constant () of liquid crystal molecules in a major axis direction was measured. Sine waves (0.5 V, 1 kHz) were applied to the device, and after 2 seconds, a dielectric constant () of liquid crystal molecules in a minor axis direction was measured. A value of dielectric anisotropy was calculated from an equation: =.

(16) (7) Threshold voltage (Vth; measured at 25 C.; V): For measurement, an LCD-5100 luminance meter made by Otsuka Electronics Co., Ltd. was used. A light source was a halogen lamp. A sample was put in a normally white mode TN device in which a distance (cell gap) between two glass substrates was 0.45/n (m) and a twist angle was 80 degrees. A voltage (32 Hz, rectangular waves) to be applied to the device was stepwise increased from 0 V to 10 Vat an increment of 0.02 V. On the occasion, the device was irradiated with light from a direction perpendicular to the device, and an amount of light transmitted through the device was measured. A voltage-transmittance curve was prepared, in which the maximum amount of light corresponds to 100% transmittance and the minimum amount of light corresponds to 0% transmittance. A threshold voltage is expressed in terms of a voltage at 90% transmittance.

(17) (8) Voltage holding ratio (VHR-1; measured at 25 C.; %): A TN device used for measurement had a polyimide alignment film, and a distance (cell gap) between two glass substrates was 5 micrometers. A sample was put in the device, and then the device was sealed with an ultraviolet-curable adhesive. A pulse voltage (60 microseconds at 5 V) was applied to the TN device and the device was charged. A decaying voltage was measured for 16.7 milliseconds with a high-speed voltmeter, and area A between a voltage curve and a horizontal axis in a unit cycle was determined. Area B is an area without decay. A voltage holding ratio is expressed in terms of a percentage of area A to area B.

(18) (9) Voltage holding ratio (VHR-2; measured at 80 C.; %): A voltage holding ratio was measured according to procedures identical with the procedures described above except that measurement was carried out at 80 C. in place of 25 C. The thus obtained value was expressed in terms of VHR-2.

(19) (10) Voltage holding ratio (VHR-3; measured at 25 C.; %): Stability to ultraviolet light was evaluated by measuring a voltage holding ratio after a device was irradiated with ultraviolet light. A TN device used for measurement had a polyimide alignment film and a cell gap was 5 micrometers. A sample was injected into the device, and the device was irradiated with light for 20 minutes. A light source was an ultra high-pressure mercury lamp USH-500D (made by Ushio, Inc.), and a distance between the device and the light source was 20 centimeters. In measurement of VHR-3, a decaying voltage was measured for 16.7 milliseconds. A composition having large VHR-3 has large stability to ultraviolet light. A value of VHR-3 is preferably 90, or more, and further preferably 95% or more.

(20) (11) Voltage holding ratio (VHR-4; measured at 25 C.; %): Stability to heat was evaluated by measuring a voltage holding ratio after a TN device into which a sample was injected was heated in a constant-temperature bath at 80 C. for 500 hours. In measurement of VHR-4, a decaying voltage was measured for 16.7 milliseconds. A composition having large VHR-4 has large stability to heat.

(21) (12) Response time (; measured at 25 C.; ms): For measurement, an LCD-5100 luminance meter made by Otsuka Electronics Co., Ltd. was used. A light source was a halogen lamp. A low-pass filter was set to 5 kHz. A sample was put in a normally white mode TN device in which a distance (cell gap) between two glass substrates was 5.0 micrometers and a twist angle was 80 degrees. A voltage (rectangular waves; 60 Hz, 5 V, 0.5 second) was applied to the device. On the occasion, the device was irradiated with light from a direction perpendicular to the device, and an amount of light transmitted through the device was measured. The maximum amount of light corresponds to 100% transmittance, and the minimum amount of light corresponds to 0% transmittance. A rise time (r; millisecond) was expressed in terms of time required for a change from 90% transmittance to 10% transmittance. A fall time (f; millisecond) was expressed in terms of time required for a change from 10% transmittance to 90% transmittance. A response time was expressed by a sum of the rise time and the fall time thus determined.

(22) (13) Elastic constant (K; measured at 25 C.; pN): For measurement, HP4284A LCR Meter made by Yokogawa-Hewlett-Packard Co. was used. A sample was put in a horizontal alignment device in which a distance (cell gap) between two glass substrates was 20 micrometers. An electric charge of 0 V to 20 V was applied to the device, and electrostatic capacity and applied voltage were measured. The measured values of electrostatic capacity (C) and applied voltage (V) were fitted to equation (2.98) and equation (2.101) on page 75 of Liquid Crystal Device Handbook (Ekisho Debaisu Handobukku in Japanese; Nikkan Kogyo Shimbun, Ltd.), and values of K11 and K33 were obtained from equation (2.99). Next, K22 was calculated using the previously determined values of K11 and K33 in equation (3.18) on page 171. Elastic constant K was expressed in terms of a mean value of the thus determined K11, K22 and K33.

(23) (14) Specific resistance (; measured at 25 C.; cm): Into a vessel equipped with electrodes, 1.0 milliliter of sample was injected. A direct current voltage (10 V) was applied to the vessel, and a direct current after 10 seconds was measured. Specific resistance was calculated from the following equation: (specific resistance)={(voltage)(electric capacity of a vessel)}/{(direct current)(dielectric constant of vacuum)}.

(24) (15) Helical pitch (P; measured at room temperature; m): A helical pitch was measured according to a wedge method. Refer to page 196 in Handbook of Liquid Crystals (Ekisho Binran in Japanese) (issued in 2000, Maruzen Co., Ltd.). A sample was injected into a wedge cell and left to stand at room temperature for 2 hours, and then a gap (d2d1) between disclination lines was observed by a polarizing microscope (trade name: MM40/60 Series, Nikon Corporation). A helical pitch (P) was calculated according to the following equation in which an angle of the wedge cell was expressed as : P=2(d2d1)tan .

(25) (16) Dielectric constant (; measured at 25 C.) in minor axis direction: A sample was put in a TN device in which a distance (cell gap) between two glass substrates was 9 micrometers and a twist angle was 80 degrees. Sine waves (0.5 V, 1 kHz) were applied to the device, and after 2 seconds, a dielectric constant () of liquid crystal molecules in the minor axis direction was measured.

(26) Examples of composition were described below. The component compounds were represented using symbols according to definitions in Table 3 described below. In Table 3, the configuration of 1,4-cyclohexylene is trans. A parenthesized number next to a symbolized compound represents a chemical formula to which the compound belongs. A symbol () means any other liquid crystal compound. A proportion (percentage) of the liquid crystal compound is expressed in terms of weight percent (% by weight) based on the weight of the liquid crystal composition. Values of the characteristics of the composition were summarized in a last part.

(27) TABLE-US-00003 TABLE 3 Method for Description of Compounds using Symbols R(A.sub.1)Z.sub.1 . . . Z.sub.n(A.sub.n)R 1) Left-terminal Group R Symbol C.sub.nH.sub.2n+1 n- C.sub.nH.sub.2n+1O nO C.sub.mH.sub.2m+1OC.sub.nH.sub.2n mOn CH.sub.2CH V C.sub.nH.sub.2n+1CHCH nV CH.sub.2CHC.sub.nH.sub.2n Vn C.sub.mH.sub.2m+1CHCHC.sub.nH.sub.2n mVn CF.sub.2CH VFF CF.sub.2CHC.sub.nH.sub.2n VFFn FC.sub.nH.sub.2n Fn 2) Right-terminal Group R Symbol C.sub.nH.sub.2n+1 -n OC.sub.nH.sub.2n+1 On CHCH.sub.2 V CHCHC.sub.nH.sub.2n+1 Vn C.sub.nH.sub.2nCHCH.sub.2 nV C.sub.nH.sub.2nCHCHC.sub.mH.sub.2m+1 nVm CHCF.sub.2 VFF COOCH.sub.3 EMe F F Cl CL OCF.sub.3 OCF3 CF.sub.3 CF3 CN C 3) Bonding Group Z.sub.n Symbol C.sub.nH.sub.2n n COO E CHCH V CC T CF.sub.2O X CH.sub.2O 1O 4) Ring Structure A.sub.n Symbol H Dh dh B B(F) B(2F) B(F,F) B(2F,5F) G 0 Py B(2F,3F) ch 5) Examples of Description Example 1 3-HHV1 Example 2 3-HHBCL Example 3 4-GB(F)B(F,F)XB(F,F)F Example 4 2OHHHV

Example 1

(28) TABLE-US-00004 2O-HHH-V (1-1) 10% 3-HHXB(F,F)-F (2-2) 6% 3-BB(F,F)XB(F,F)-F (2-4) 17% 3-HBBXB(F,F)-F (2-7) 5% 4-BB(F)B(F,F)XB(F,F)-F (2-10) 10% 3-HH-V (3-1) 40% 3-HBB(F,F)-F (4-8) 5% 3-BB(F)B(F,F)-F (4-12) 3% 3-HHBB(F,F)-F (4-14) 4%

(29) NI=75.6 C.; Tc<20 C.; =11.2 mPa.Math.s; n=0.099; =8.3; Vth=1.38 V; 1=61.7 mPa.Math.s.

Comparative Example 1

(30) The composition in Example 1 contains compound (1-1) being a first component. For comparison, a composition in which a compound being the first component in Example 1 was used in place of compound (3) similar thereto was taken as Comparative Example 1.

(31) TABLE-US-00005 3-HHH-V (3) 10% 3-HHXB(F,F)-F (2-2) 6% 3-BB(F,F)XB(F,F)-F (2-4) 17% 3-HBBXB(F,F)-F (2-7) 5% 4-BB(F)B(F,F)XB(F,F)-F (2-10) 10% 3-HH-V (3-1) 40% 3-HBB(F,F)-F (4-8) 5% 3-BB(F)B(F,F)-F (4-12) 3% 3-HHBB(F,F)-F (4-14) 4%

(32) NI=80.3 C.; Tc<0 C.; =12.4 mPa.Math.s; n=0.100; =8.6; Vth=1.44 V; 1=63.1 mPa.Math.s.

Example 2

(33) TABLE-US-00006 2O-HHH-V (1-1) 3% 3O-HHH-V (1-1) 3% 2O-HHHVH-V (1-4) 3% 5-HXB(F,F)-F (2-1) 3% 3-HHXB(F,F)-F (2-2) 3% 3-BB(F,F)XB(F,F)-F (2-4) 13% 3-HBBXB(F,F)-F (2-7) 4% 3-dhBB(F,F)XB(F,F)-F (2-8) 3% 4-BB(F)B(F,F)XB(F,F)-F (2-10) 6% 3-HH-V (3-1) 32% 1V2-HH-3 (3-1) 3% 7-HB-1 (3-2) 3% 1-BB(F)B-2V (3-7) 3% 2-BB(F)B-2V (3-7) 3% 3-HB-CL (4-1) 3% 3-HGB(F,F)-F (4-6) 3% 2-HBEB(F,F)-F (4-10) 3% 3-BB(F)B(F,F)-F (4-12) 3% 3-HHBB(F,F)-F (4-14) 3%

(34) NI=74.8 C.; Tc<20 C.; =10.9 mPa.Math.s; n=0.103; =7.3; Vth=1.48 V; 1=59.2 mPa.Math.s.

Example 3

(35) TABLE-US-00007 2O-HHH-V (1-1) 4% 3O-HHH-V (1-1) 3% 1-HHXB(F,F)-F (2-2) 3% 3-HHXB(F,F)-F (2-2) 3% 3-BB(F,F)XB(F,F)-F (2-4) 12% 3-HBBXB(F,F)-F (2-7) 3% 3-GB(F)B(F,F)XB(F,F)-F (2-9) 3% 4-BB(F)B(F,F)XB(F,F)-F (2-10) 6% 3-HH-V (3-1) 33% 1V2-HH-1 (3-1) 3% 3-HB-O2 (3-2) 3% 3-BB(F)B-5 (3-7) 3% 3-BB(F)B-2V (3-7) 3% 5-HB-CL (4-1) 3% 4-HGB(F,F)-F (4-6) 3% 3-HBEB(F,F)-F (4-10) 3% 3-HHBB(F,F)-F (4-14) 3% 4-GBB(F)B(F,F)-F (4-16) 3% 1O1-HBBH-5 () 3%

(36) NI=82.1 C.; Tc<20 C.; =14.1 mPa.Math.s; n=0.105; =7.4; Vth=1.47 V; 1=76.6 mPa.Math.s.

Example 4

(37) TABLE-US-00008 2O-HHH-V (1-1) 3% 3-HHXB(F,F)-CF3 (2-2) 3% 3-BB(F,F)XB(F,F)-F (2-4) 17% 3-HBBXB(F,F)-F (2-7) 4% 4-GB(F)B(F,F)XB(F,F)-F (2-9) 3% 4-BB(F)B(F,F)XB(F,F)-F (2-10) 8% 3-HH-V (3-1) 32% 5-HH-V (3-1) 3% 5-HB-O2 (3-2) 3% 2-BB(F)B-5 (3-7) 3% 5-B(F)BB-2 (3-8) 3% 5-HBB(F)B-2 (3-13) 3% 7-HB(F,F)-F (4-2) 3% 5-HGB(F,F)-F (4-6) 3% 3-HBB(F,F)-F (4-8) 3% 5-HBEB(F,F)-F (4-10) 3% 3-HHBB(F,F)-F (4-14) 3%

(38) NI=70.7 C.; Tc<20 C.; =15.0 mPa.Math.s; n=0.107; =9.2; Vth=1.31 V; 1=81.8 mPa.Math.s.

Example 5

(39) TABLE-US-00009 3O-HHH-V (1-1) 3% 4O-HVHHH-V (1-6) 3% 3-GB(F,F)XB(F,F)-F (2-3) 3% 3-BB(F,F)XB(F,F)-F (2-4) 11% 3-HBBXB(F,F)-F (2-7) 5% 5-GB(F)B(F,F)XB(F,F)-F (2-9) 5% 4-BB(F)B(F,F)XB(F,F)-F (2-10) 10% 3-HH-V (3-1) 32% 4-HH-V (3-1) 3% 1-BB-3 (3-3) 3% 2-BB(F)B-3 (3-7) 3% 5-B(F)BB-3 (3-8) 4% 3-HHB-OCF3 (4-3) 3% 3-GHB(F,F)-F (4-7) 3% 3-HBB(F,F)-F (4-8) 3% 3-GB(F)B(F,F)-F (4-11) 3% 3-BB(F)B(F,F)-F (4-12) 3%

(40) NI=71.5 C.; Tc<20 C.; =15.4 mPa.Math.s; n=0.111; =10.0; Vth=1.24 V; 1=83.9 mPa.Math.s.

Example 6

(41) TABLE-US-00010 1O-HHH-V (1-1) 3% 2O-H2HHH-V (1-5) 2% 3-HHXB(F,F)-F (2-2) 4% 3-BB(F,F)XB(F,F)-F (2-4) 15% 3-BB(F,F)XB(F)-OCF3 (2-4) 3% 3-HBBXB(F,F)-F (2-7) 4% 4-GBB(F,F)XB(F,F)-F (2-9) 3% 4-BB(F)B(F,F)XB(F,F)-F (2-10) 8% 3-HH-V (3-1) 34% 3-HH-VFF (3-1) 3% 1-BB-5 (3-3) 3% V-HBB-2 (3-6) 3% 3-HB(F)HH-5 (3-9) 3% 5-HBB(F)B-3 (3-13) 3% 1-HHB(F,F)-F (4-4) 3% 4-GHB(F,F)-F (4-7) 3% 3-GBB(F)B(F,F)-F (4-16) 3%

(42) NI=77.4 C.; Tc<20 C.; =15.7 mPa.Math.s; n=0.104; =8.7; Vth=1.35 V; 1=85.7 mPa.Math.s.

Example 7

(43) TABLE-US-00011 2O-HHH-V (1-1) 5% 3O-HHH-V (1-1) 3% 3-HHXB(F,F)-F (2-2) 3% 3-BB(F,F)XB(F,F)-F (2-4) 13% 3-BB(2F,3F)XB(F,F)-F (2-4) 3% 3-HBBXB(F,F)-F (2-7) 3% 5-GBB(F,F)XB(F,F)-F (2-9) 3% 4-BB(F)B(F,F)XB(F,F)-F (2-10) 7% 3-HH-V (3-1) 26% 3-HH-V1 (3-1) 8% V2-BB-1 (3-3) 3% 3-HBB-2 (3-6) 3% 3-HHEBH-3 (3-10) 3% 2-HHB(F,F)-F (4-4) 3% 5-GHB(F,F)-F (4-7) 3% 3-HBB(F,F)-F (4-8) 3% 3-BB(F)B(F,F)-F (4-12) 2% 3-BB(F)B(F,F)-CF3 (4-13) 3% 3-HBB(2F,3F)-O2 (5-10) 3%

(44) NI=79.0 C.; Tc<20 C.; =16.1 mPa.Math.s; n=0.105; =8.5; Vth=1.38 V; 1=88.0 mPa.Math.s.

Example 8

(45) TABLE-US-00012 1O-HHH-V (1-1) 3% 2O-HHH-V (1-1) 3% 3O-HHH-V (1-1) 3% 3-HHXB(F,F)-F (2-2) 4% 3-BB(F,F)XB(F,F)-F (2-4) 15% 3-HHB(F,F)XB(F,F)-F (2-5) 3% 3-HBBXB(F,F)-F (2-7) 4% 3-BB(F)B(F,F)XB(F,F)-F (2-10) 3% 4-BB(F)B(F,F)XB(F,F)-F (2-10) 8% 3-HH-5 (3-1) 3% 3-HH-V (3-1) 30% 1V2-BB-1 (3-3) 3% V-HHB-1 (3-5) 3% 3-HHEBH-4 (3-10) 3% 3-HHB(F,F)-F (4-4) 3% 2-HBB(F,F)-F (4-8) 3% 2-HHBB(F,F)-F (4-14) 3% 3-HHBB(F,F)-F (4-14) 3%

(46) NI=88.9 C.; Tc<20 C.; =16.6 mPa.Math.s; n=0.105; =8.5; Vth=1.38 V; 1=90.7 mPa.Math.s.

Example 9

(47) TABLE-US-00013 2O-HHH-V (1-1) 3% 3O-HHH-V (1-1) 3% 4O-HHH-V (1-1) 3% 3-HHXB(F,F)-F (2-2) 3% 3-BB(F,F)XB(F,F)-F (2-4) 12% 3-HGB(F,F)XB(F,F)-F (2-6) 3% 3-HBBXB(F,F)-F (2-7) 3% 4-BB(F)B(F,F)XB(F,F)-F (2-10) 7% 5-BB(F)B(F,F)XB(F,F)-F (2-10) 3% 3-HH-4 (3-1) 3% 3-HH-V (3-1) 33% 3-HHEH-3 (3-4) 3% 3-HHB-3 (3-5) 3% V2-HHB-1 (3-5) 3% 3-HHEBH-5 (3-10) 3% 4-HHB(F,F)-F (4-4) 3% 3-HBB(F,F)-F (4-8) 3% 3-BB(F)B(F,F)-F (4-12) 3% 3-HHB(F)B(F,F)-F (4-15) 3%

(48) NI=91.7 C.; Tc<20 C.; =14.4 mPa.Math.s; n=0.098; =7.3; Vth=1.49 V; 1=78.5 mPa.Math.s.

Example 10

(49) TABLE-US-00014 3O-HHH-V (1-1) 3% 4O-HHH-V (1-1) 3% 2O-HHH2H-V (1-3) 2% 3-HHXB(F,F)-F (2-2) 4% 3-BB(F,F)XB(F,F)-F (2-4) 14% 3-HBBXE(F,F)-F (2-7) 4% 5-HBBXB(F,F)-F (2-7) 3% 4-BB(F)B(F,F)XB(F,F)-F (2-10) 8% 3-BB(F)B(F,F)XB(F)-F (2-10) 3% 2-HH-5 (3-1) 3% 3-HH-V (3-1) 32% 2-HHB-1 (3-5) 3% 3-HHB-O1 (3-5) 3% 3-HBBH-5 (3-11) 3% 3-HHEB(F,F)-F (4-5) 3% 5-HBB(F,F)-F (4-8) 3% 3-BB(F)B(F,F)-F (4-12) 3% 4-HHBB(F,F)-F (4-14) 3%

(50) NI=90.5 C.; Tc<20 C.; =16.7 mPa.Math.s; n=0.105; =7.8; Vth=1.44 V; 1=90.9 mPa.Math.s.

Example 11

(51) TABLE-US-00015 1O-HHH-V (1-1) 3% 2O-HHH-V (1-1) 4% 4O-HHH-VFF (1-1) 2% 3-HHXB(F,F)-F (2-2) 4% 3-BB(F,F)XB(F,F)-F (2-4) 15% 3-HBBXB(F,F)-F (2-7) 4% 3-HBB(F,F)XB(F,F)-F (2-7) 3% 4-BB(F)B(F,F)XB(F,F)-F (2-10) 8% 3-BB(F,F)XB(F)B(F,F)-F (2-12) 3% 2-HH-3 (3-1) 7% 3-HH-V (3-1) 29% 3-HHB-1 (3-5) 3% 5-HB(F)BH-3 (3-12) 3% 2-HGB(F,F)-F (4-6) 3% 3-HB(F)B(F,F)-F (4-9) 3% 3-BB(F)B(F,F)-F (4-12) 3% 5-HHBB(F,F)-F (4-14) 3%

(52) NI=79.2 C.; Tc<20 C.; =15.3 mPa.Math.s; n=0.101; =8.8; Vth=1.36 V; 1=83.5 mPa.Math.s.

(53) The minimum temperatures (Tc) of nematic phase of the composition in Comparative Example 1 was 0 C. or less. On the other hand, the minimum temperature of nematic phase of the composition in Example 1 was 20 C. or less. Thus, the composition in Examples was found to have a lower minimum temperature of nematic phase in comparison with the composition in Comparative Examples. Accordingly, the liquid crystal composition of the invention is concluded to have superb characteristics.

INDUSTRIAL APPLICABILITY

(54) A liquid crystal composition of the invention can be used in a liquid crystal projector, a liquid crystal television and so forth.