Liquid crystal display device

Abstract

The subject is to shown a liquid crystal display device that has characteristics such as a short response time, a large voltage holding ratio, a low threshold voltage, a large contrast ratio, a long service life and a small flicker rate. The disclosure relates to a liquid crystal display device having an electrode group formed on one or both of a pair of substrates that are opposed to each other, and a plurality of active devices connected to the electrode group, and a liquid crystal alignment film formed on the opposing surfaces of the pair of substrates, and a liquid crystal composition sandwiched in between the pair of substrates, wherein the liquid crystal alignment film includes a polymer having a photodegradable group, and the liquid crystal composition includes at least one compound selected from the group consisting of compounds represented by formula (1) as a first component: ##STR00001##

Claims

1. A liquid crystal display device having an electrode group formed on one or both of a pair of substrates that are opposed to each other, and a plurality of active devices connected to the electrode group, and a liquid crystal alignment film formed on the opposing surfaces of the pair of substrates, and a liquid crystal composition sandwiched in between the pair of substrates, wherein the liquid crystal alignment film comprises a polymer derived from a polyamic acid having a photodegradable group, and the liquid crystal composition comprises at least one compound selected from the group consisting of compounds represented by formula (1) as a first component: ##STR00121## in formula (1), R.sup.1 and R.sup.2 are independently alkyl having 1 to 12 carbons, alkoxy having 1 to 12 carbons, alkenyl having 2 to 12 carbons, alkenyloxy having 2 to 12 carbons or alkyl having 1 to 12 carbons in which at least one hydrogen has been replaced by fluorine or chlorine; ring A and ring C are independently 1,4-cyclohexylene, 1,4-cyclohexenylene, 1,4-phenylene, 1,4-phenylene in which at least one hydrogen has been replaced by fluorine or chlorine, or tetrahydropyran-2,5-diyl; ring B is 2,3-difluoro-1,4-phenylene, 2-chloro-3-fluoro-1,4-phenylene, 2,3-difluoro-5-methyl-1,4-phenylene,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.1 and Z.sup.2 are independently a single bond, ethylene, carbonyloxy or methyleneoxy; a is 0, 1, 2 or 3; b is 0 or 1; and the sum of a and b is 3 or less.

2. The liquid crystal display device according to claim 1, wherein the first component is at least one compound selected from the group consisting of compounds represented by formula (1-1) to formula (1-21): ##STR00122## ##STR00123## in formula (1-1) to formula (1-21), R.sup.1 and R.sup.2 are independently alkyl having 1 to 12 carbons, alkoxy having 1 to 12 carbons, alkenyl having 2 to 12 carbons, alkenyloxy having 2 to 12 carbons or alkyl having 1 to 12 carbons in which at least one hydrogen has been replaced by fluorine or chlorine.

3. The liquid crystal display device according to claim 1, wherein the liquid crystal composition comprises at least one compound selected from the group consisting of compounds represented by formula (2) as a second component: ##STR00124## in formula (2), R.sup.3 and R.sup.4 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 has been replaced by fluorine or chlorine or alkenyl having 2 to 12 carbons in which at least one hydrogen has been replaced by fluorine or chlorine; ring D and ring E are independently 1,4-cyclohexylene, 1,4-phenylene, 2-fluoro-1,4-phenylene or 2,5-difluoro-1,4-phenylene; Z.sup.3 is single bond, ethylene or carbonyloxy; and c is 1, 2 or 3.

4. The liquid crystal display device according to claim 3, wherein the second component is at least one compound selected from the group consisting of compounds represented by formula (2-1) to formula (2-13): ##STR00125## ##STR00126## in formula (2-1) to formula (2-13), R.sup.3 and R.sup.4 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 has been replaced by fluorine or chlorine, or alkenyl having 2 to 12 carbons in which at least one hydrogen has been replaced by fluorine or chlorine.

5. The liquid crystal display device according to claim 1, wherein the liquid crystal composition comprises at least one polymerizable compound selected from the group consisting of compounds represented by formula (3) as an additive component: ##STR00127## in formula (3), ring F and ring I are independently cyclohexyl, cyclohexenyl, phenyl, 1-naphthyl, 2-naphthyl, tetrahydropyran-2-yl, 1,3-dioxane-2-yl, pyrimidine-2-yl, or pyridine-2-yl, and in these rings, at least one hydrogen may be replaced by halogen, alkyl having 1 to 12 carbons, alkoxy having 1 to 12 carbons, or alkyl having 1 to 12 carbons in which at least one hydrogen has been replaced halogen; ring G is 1,4-cyclohexylene, 1,4-cyclohexenylene, 1,4-phenylene, naphthalene-1,2-diyl, naphthalene-1,3-diyl, naphthalene-1,4-diyl, naphthalene-1,5-diyl, naphthalene-1,6-diyl, naphthalene-1,7-diyl, naphthalene-1,8-diyl, naphthalene-2,3-diyl, naphthalene-2,6-diyl, naphthalene-2,7-diyl, tetrahydropyran-2,5-diyl, 1,3-dioxane-2,5-diyl, pyrimidine-2,5-diyl, or pyridine-2,5-diyl, and in these rings, at least one hydrogen may be replaced by halogen, alkyl having 1 to 12 carbons, alkoxy having 1 to 12 carbons, or alkyl having 1 to 12 carbons in which at least one hydrogen has been replaced halogen; Z.sup.4 and Z.sup.5 are independently a single bond or alkylene having 1 to 10 carbons, and in the alkylene, at least one CH.sub.2 may be replaced by O, CO, COO or OCO, and at least one CH.sub.2CH.sub.2 may be replaced by CHCH, C(CH.sub.3)CH, CHC(CH.sub.3) or C(CH.sub.3)C(CH.sub.3), and in these groups at least one hydrogen may be replaced by fluorine or chlorine; P.sup.1, P.sup.2 and P.sup.3 are independently a polymerizable group; Sp.sup.1, Sp.sup.2 and Sp.sup.3 are independently a single bond or alkylene having 1 to 10 carbons, and in the alkylene, at least one CH.sub.2 may be replaced by O, COO, OCO or OCOO, and at least one CH.sub.2CH.sub.2 may be replaced by CHCH or CC, and in these groups at least one hydrogen may be replaced by fluorine or chlorine; d is 0, 1 or 2; e, f and g are independently 0, 1, 2, 3 or 4; and the sum of e, f and g is 1 or more.

6. The liquid crystal display device according to claim 5, wherein in formula (3), P.sup.1, P.sup.2 and P.sup.3 are independently a polymerizable group selected from the group consisting of groups represented by formula (P-1) to formula (P-5): ##STR00128## in formula (P-1) to formula (P-5), M.sup.1, M.sup.2 and M.sup.3 are independently hydrogen, fluorine, alkyl having 1 to 5 carbons or alkyl having 1 to 5 carbons in which at least one hydrogen has been replaced halogen.

7. The liquid crystal display device according to claim 5, wherein the additive component is at least one polymerizable compound selected from the group consisting of compounds represented by formula (3-1) to formula (3-27): ##STR00129## ##STR00130## ##STR00131## in formula (3-1) to formula (3-27), P.sup.4, P.sup.5 and P.sup.6 are independently a polymerizable group selected from the group consisting of groups represented by formula (P-1) to formula (P-3): ##STR00132## in formula (P-1) to formula (P-3), M.sup.1, M.sup.2 and M.sup.3 are independently hydrogen, fluorine, alkyl having 1 to 5 carbons or alkyl having 1 to 5 carbons in which at least one hydrogen has been replaced by fluorine or chlorine; and in formula (3-1) to formula (3-27), Sp.sup.1, Sp.sup.2 and Sp.sup.3 are independently a single bond or alkylene having 1 to 10 carbons, and in the alkylene, at least one CH.sub.2 may be replaced by O, COO, OCO or OCOO, and at least one CH.sub.2CH.sub.2 may be replaced by CHCH or CC, and in these groups at least one hydrogen may be replaced by fluorine or chlorine.

8. The liquid crystal display device according to claim 1, wherein the liquid crystal alignment film comprises a polymer derived from a polyamic acid having at least one photodegradable group selected from the group consisting of groups represented by formula (XI-1) to formula (XI-16): ##STR00133## ##STR00134## in formula (XI-1) to formula (XI-16), R.sup.5, R.sup.6, R.sup.7 and R.sup.8 are independently hydrogen, halogen, alkyl having 1 to 6 carbons, alkenyl having 2 to 6 carbons, alkynyl having 2 to 6 carbons or phenyl; R.sup.9 is hydrogen, alkyl having 1 to 10 carbons or cycloalkyl having 3 to 10 carbons; n.sub.1 is an integer from 1 to 4; when n.sub.1 is 1, Z.sup.6 is SCH.sub.2, and when n.sub.1 is 2, 3 or 4, Z.sup.6 is a single bond, SCH.sub.2 or CH.sub.2S, with the proviso that at least one of Z.sup.6 is SCH.sub.2 or CH.sub.2S; and Z.sup.7 is a group comprising an aromatic ring.

9. The liquid crystal display device according to claim 8, wherein the liquid crystal alignment film comprises a polymer derived from a compound represented by formula (XI-1-1) to formula (XI-1-5), formula (XI-2-1), formula (XI-3-1), formula (XI-6-1), formula (XI-7-1) or formula (XI-10-1): ##STR00135## ##STR00136##

10. The liquid crystal display device according to claim 8, wherein the liquid crystal alignment film comprises a polymer derived by further using at least one compound selected from the group consisting of compounds represented by formula (DI-1) to formula (DI-15): ##STR00137## in formula (DI-1) to formula (DI-7), k is an integer from 1 to 12; G.sup.21 is a single bond, NH, O, S, SS, SO.sub.2, CO, CONH, CON(CH.sub.3), NHCO, C(CH.sub.3).sub.2, C(CF.sub.3).sub.2, O(CH.sub.2).sub.mO, N(CH.sub.3)(CH.sub.2).sub.nN(CH.sub.3), COO, COS or S(CH.sub.2).sub.mS; m is an integer from 1 to 12; n is an integer from 1 to 5; G.sup.22 is a single bond, O, S, CO, C(CH.sub.3).sub.2, C(CF.sub.3).sub.2 or alkylene having 1 to 10 carbons; at least one hydrogen of the cyclohexane ring or the benzene ring may be replaced by fluorine, CH.sub.3, OH, CF.sub.3, CO.sub.2H, CONH.sub.2 or benzyl, and in formula (DI-4), at least one hydrogen of the benzene ring may be replaced by a monovalent group represented by the following formula (DI-4-a) to formula (DI-4-d): ##STR00138## R.sup.10 is hydrogen or CH.sub.3; and a group can be bonded to any one of carbon atoms constituting a ring when the bonding position of the group is not fixed to any one of the carbon atoms, and the bonding position of NH.sub.2 to a cyclohexane ring or a benzene ring is any one of positions excluding the bonding position of G.sup.21 or G.sup.22; and ##STR00139## in formula (DI-8) to formula (DI-12), R.sup.11 and R.sup.12 are independently alkyl having 1 to 3 carbons or phenyl; G.sup.23 is alkylene having 1 to 6 carbons, phenylene or phenylene in which at least one hydrogen has been replaced by alkyl; p is an integer from 1 to 10; R.sup.13 is alkyl having 1 to 5 carbons, alkoxy having 1 to 5 carbons or chlorine; q is an integer from 0 to 3; r is an integer from 0 to 4; R.sup.14 is hydrogen, alkyl having 1 to 4 carbons, phenyl or benzyl; G.sup.24 is CH.sub.2 or NH; G.sup.25 is a single bond, alkylene having 2 to 6 carbons or 1,4-phenylene; s is 0 or 1; a group can be bonded to any one of carbon atoms constituting a ring when the bonding position of the group is not fixed to any one of the carbon atoms; and NH.sub.2 is bonded to any one of the bonding positions on a benzene ring; and ##STR00140## in formula (DI-13) to formula (DI-15), G.sup.31 is a single bond, alkylene having 1 to 20 carbons, CO, O, S, SO.sub.2, C(CH.sub.3).sub.2 or C(CF.sub.3).sub.2; ring K is a cyclohexane ring, a benzene ring or a naphthalene ring, and in these groups at least one hydrogen may be replaced by methyl, ethyl or phenyl; and ring L is a cyclohexane ring or a benzene ring, and in these groups at least one hydrogen may be replaced by methyl, ethyl or phenyl.

11. The liquid crystal display device according to claim 8, wherein the liquid crystal alignment film comprises a polymer derived by further using at least one compound selected from the group consisting of compounds represented by formula (DI-1-3), formula (DI-4-1), formula (DI-5-1), formula (DI-5-5), formula (DI-5-9), formula (DI-5-12), formula (DI-5-22), formula (DI-5-28), formula (DI-5-30), formula (DI-5-31), formula (DI-7-3), formula (DI-9-1), formula (DI-13-1), formula (DI-13-2), formula (DI-14-1) and formula (DI-14-2): ##STR00141## ##STR00142## in formula (DI-1-3), formula (DI-4-1), formula (DI-5-1), formula (DI-5-5), formula (DI-5-9), formula (DI-5-12), formula (DI-5-22), formula (DI-5-28), formula (DI-5-30), formula (DI-5-31), formula (DI-7-3), formula (DI-9-1), formula (DI-13-1), formula (DI-13-2), formula (DI-14-1) and formula (DI-14-2), m is an integer from 1 to 12; n is an integer from 1 to 5; and t is 1 or 2.

12. The liquid crystal display device according to claim 1, wherein the operating mode of the liquid crystal display device is a TN mode, an ECB mode, an OCB mode, an IPS mode, an FFS mode, a PSA mode, or an FPA mode, and the driving mode of the liquid crystal display device is an active matrix mode.

13. The liquid crystal display device according to claim 1, wherein the operating mode of the liquid crystal display device is an IPS mode or an FFS mode, and the driving mode of the liquid crystal display device is an active matrix mode.

14. A liquid crystal composition used for the liquid crystal display device according to claim 1.

15. The liquid crystal composition according to claim 14, wherein at 25 C., the elastic constant (K11) is 11 pN or more and the elastic constant (K33) is 11 pN or more.

16. A liquid crystal display device, wherein the device comprises the liquid crystal composition according to claim 14, and the flicker rate at 25 C. is in the range of 0% to 1%.

17. A liquid crystal alignment film used for the liquid crystal display device according to claim 8.

18. The liquid crystal alignment film according to claim 17, wherein the volume resistivity () at 25 C. is 1.010.sup.14 cm or more.

19. The liquid crystal alignment film according to claim 17, wherein the dielectric constant () at 25 C. is in the range of 3 to 5.

Description

EXAMPLES

(1) The invention will be explained in more detail byway of examples. The invention is not limited to the examples. The invention includes a mixture of the composition in Composition Example M1 and the composition in Composition Example M2. The invention also includes a mixture prepared by mixing at least two compositions in Composition Examples. The invention includes a polyamic acid prepared from a mixture of two tetracarboxylic acid dianhydrides described in Synthetic Examples 2 and 3. The invention includes a polyamic acid prepared from a mixture of at least two starting materials (a diamine, a tetracarboxylic acid dianhydride or its derivatives) described in Synthetic Examples. The same rule applies to examples such as the production of devices. Compounds prepared herein were identified by methods such as NMR analysis. The characteristics of the compounds, the compositions and the devices were measured by the methods described below.

(2) NMR Analysis

(3) A model DRX-500 apparatus made by Bruker BioSpin Corporation was used for measurement. In the measurement of .sup.1H-NMR, a sample was dissolved in a deuterated solvent such as CDCl.sub.3, and the measurement was carried out under the conditions of room temperature, 500 MHz and the accumulation of 16 scans. Tetramethylsilane (TMS) was used as an internal standard. In the measurement of .sup.19F-NMR, CFCl.sub.3 was used as the internal standard, and 24 scans were accumulated. In the explanation of the nuclear magnetic resonance spectra, the symbols s, d, t, q, quin, sex, m and br stand for a singlet, a doublet, a triplet, a quartet, a quintet, a sextet, a multiplet and line-broadening, respectively.

(4) Gas Chromatographic Analysis

(5) A gas chromatograph Model GC-14B made by Shimadzu Corporation was used for measurement. The carrier gas was helium (2 milliliters per minute). The sample injector and the detector (FID) were set to 280 C. and 300 C., respectively. A capillary column DB-1 (length 30 meters, bore 0.32 millimeter, film thickness 0.25 micrometer, dimethylpolysiloxane as the stationary phase, non-polar) made by Agilent Technologies, Inc. was used for the separation of component compounds. After the column had been kept at 200 C. for 2 minutes, it was further heated to 280 C. at the rate of 5 C. per minute. A sample was dissolved in acetone (0.1% by weight), and 1 microliter of the solution was injected into the sample injector. A recorder used was a Model C-R5A Chromatopac Integrator made by Shimadzu Corporation or its equivalent. The resulting gas chromatogram showed the retention time of peaks and the peak areas corresponding to the component compounds.

(6) Solvents for diluting the sample may also be chloroform, hexane and so forth. The following capillary columns may also be used in order to separate the component compounds: HP-1 made by Agilent Technologies Inc. (length 30 meters, bore 0.32 millimeter, film thickness 0.25 micrometer), Rtx-1 made by Restek Corporation (length 30 meters, bore 0.32 millimeter, film thickness 0.25 micrometer), and BP-1 made by SGE International Pty. Ltd. (length 30 meters, bore 0.32 millimeter, film thickness 0.25 micrometer). A capillary column CBP1-M50-025 (length 50 meters, bore 0.25 millimeter, film thickness 0.25 micrometer) made by Shimadzu Corporation may also be used for the purpose of avoiding an overlap of peaks of the compounds.

(7) The proportion of the liquid crystal compounds included in the composition may be calculated according to the following method. The liquid crystal compounds (a mixture) are detected by use of a gas chromatograph (FID). The ratio of peak areas in the gas chromatogram corresponds to the ratio (ratio by weight) of the liquid crystal compounds. When the capillary column described above is used, the correction coefficient of respective liquid crystal compounds may be regarded as 1 (one). Accordingly, the proportion (percentage by weight) of the liquid crystal compounds can be calculated from the ratio of peak areas.

(8) Samples for Measurement

(9) A composition itself was used as a sample when the characteristics of the composition or the device were measured. When the characteristics of a compound were measured, a sample for measurement was prepared by mixing this compound (15% by weight) with mother liquid crystals (85% by weight). The characteristic values of the compound were calculated from the values obtained from measurements by an extrapolation method: (Extrapolated value)=(Measured value of sample)0.85(Measured value of mother liquid crystals)/0.15. When a smectic phase (or crystals) deposited at 25 C. at this proportion, the proportion of the compound to the mother liquid crystals was changed in the order of (10% by weight: 90% by weight), (5% by weight: 95% by weight) and (1% by weight: 99% by weight). The values of the maximum temperature, the optical anisotropy, the viscosity and the dielectric anisotropy regarding the compound were obtained by means of this extrapolation method.

(10) The mother liquid crystals described below were used. The proportion of the component compounds were expressed as a percentage by weight.

(11) ##STR00105##
Measurement Methods

(12) The characteristics were measured according to the following methods. Most are methods described in the JEITA standards (JEITA-ED-2521B) which was deliberated and established by Japan Electronics and Information Technology Industries Association (abbreviated to JEITA), or the modified methods. No thin film transistors (TFT) were attached to a TN device used for measurement.

(13) (1) Maximum Temperature of a Nematic Phase (NI; C.):

(14) A sample was placed on a hot plate in a melting point apparatus equipped with a polarizing microscope and was heated at the rate of 1 C. per minute. The temperature was measured when part of the sample began to change from a nematic phase to an isotropic liquid. A higher limit of the temperature range of a nematic phase may be abbreviated to the maximum temperature.

(15) (2) Minimum Temperature of a Nematic Phase (Tc; C.):

(16) A sample having a nematic phase was placed in glass vials and then kept in freezers at temperatures of 0 C., 10 C., 20 C., 30 C. and 40 C. for 10 days, and then the 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., Tc was expressed as <20 C. A lower limit of the temperature range of a nematic phase may be abbreviated to the minimum temperature.

(17) (3) Viscosity (Bulk Viscosity; ; Measured at 20 C.; mPa.Math.s):

(18) An E-type viscometer made by Tokyo Keiki Inc. was used for measurement.

(19) (4) Viscosity (Rotational Viscosity; 1; Measured at 25 C.; mPa.Math.s):

(20) The measurement was carried out according to the method described in M. Imai, et al., Molecular Crystals and Liquid Crystals, Vol. 259, p. 37 (1995). A sample was poured into a VA device in which the distance between the two glass substrates (cell gap) was 20 micrometers. A voltage in the range of 39 V to 50 V was applied stepwise with an increment of 1 volt to this device. After a period of 0.2 second with no voltage, a voltage was applied repeatedly under the conditions of one rectangular wave alone (rectangular pulse; 0.2 second) and no voltage (2 seconds). The peak current and the peak time of the transient current generated by the applied voltage were measured. The value of rotational viscosity was obtained from these measured values and the calculating equation (8) on page 40 of the paper presented by M. Imai, et al. The value of the dielectric anisotropy necessary for the present calculation was obtained by the method that will be described in item (6).

(21) (5) Optical Anisotropy (Refractive Index Anisotropy; n; Measured at 25 C.):

(22) The measurement was carried out using an Abbe refractometer with a polarizing plate attached to the ocular, using light at a wavelength of 589 nanometers. The surface of the main prism was rubbed in one direction, and then a sample was placed on the main prism. The refractive index (n) was measured when the direction of the polarized light was parallel to that of rubbing. The refractive index (n) was measured when the direction of polarized light was perpendicular to that of rubbing. The value of the optical anisotropy (n) was calculated from the equation: n=nn.

(23) (6) Dielectric Anisotropy (; Measured at 25 C.):

(24) The value of dielectric anisotropy was calculated from the equation: =. Dielectric constants ( and ) were measured as follows.

(25) 1) Measurement of a dielectric constant (): A solution of octadecyltriethoxysilane (0.16 mL) in ethanol (20 mL) was applied to thoroughly cleaned glass substrates. The glass substrates were rotated with a spinner, and then heated at 150 C. for one hour. A sample was poured into a VA device in which the distance between the two glass substrates (cell gap) was 4 micrometers, and then this device was sealed with a UV-curable adhesive. Sine waves (0.5 V, 1 kHz) were applied to this device, and the dielectric constant () in the major axis direction of liquid crystal molecules was measured after 2 seconds.
2) Measurement of a dielectric constant (): A polyimide solution was applied to thoroughly cleaned glass substrates. The glass substrates were calcined, and then the resulting alignment film was subjected to rubbing. A sample was poured into a TN device in which the distance between the two glass substrates (cell gap) was 9 micrometers and the twist angle was 80 degrees. Sine waves (0.5 V, 1 kHz) were applied to this device, and the dielectric constant () in the minor axis direction of liquid crystal molecules was measured after 2 seconds.
(7) Threshold Voltage (Vth; Measured at 25 C.; V):

(26) An LCD evaluation system Model LCD-5100 made by Otsuka Electronics Co., Ltd. was used for measurement. The light source was a halogen lamp. A sample was poured into a PVA device having a normally black mode, in which the distance between the two glass substrates (cell gap) was 4 micrometers and the rubbing direction was antiparallel, and then this device was sealed with a UV-curable adhesive. The voltage to be applied to this device (60 Hz, rectangular waves) was stepwise increased in 0.02 V increments from 0 V up to 20 V. During the increase, the device was irradiated with light in the perpendicular direction, and the amount of light passing through the device was measured. A voltage-transmittance curve was prepared, in which the maximum amount of light corresponded to 100% transmittance and the minimum amount of light corresponded to 0% transmittance. The threshold voltage was expressed as a voltage at 10% transmittance.

(27) (8) Voltage Holding Ratio (VHR-1; Measured at 25 C.; %):

(28) A TN device used for measurement had a polyimide-alignment film, and the distance between the two glass substrates (cell gap) was 5 micrometers. A sample was poured into the device, and then this TN device was sealed with a UV-curable adhesive. A pulse voltage (60 microseconds at 5 V) was applied to this device and the device was charged. A decreasing 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 obtained. Area B was an area without the decrease. The voltage holding ratio was expressed as a percentage of area A to area B.

(29) (9) Voltage Holding Ratio (VHR-2; Measured at 80 C.; %):

(30) The voltage holding ratio was measured by the method described above, except that it was measured at 80 C. instead of 25 C. The results were shown by using the symbol VHR-2.

(31) (10) Voltage Holding Ratio (VHR-3; Measured at 25 C.; %):

(32) The stability to ultraviolet light was evaluated by measuring a voltage holding ratio after irradiation with ultraviolet light. A TN device used for measurement had a polyimide-alignment film and the cell gap was 5 micrometers. A sample was poured into this device, and then the device was irradiated with light for 20 minutes. The light source was an ultra-high-pressure mercury lamp USH-500D (produced by Ushio, Inc.), and the distance between the device and the light source was 20 centimeters. In the measurement of VHR-3, a decreasing voltage was measured for 16.7 milliseconds. A composition having a large VHR-3 has a high stability to ultraviolet light. The value of VHR-3 is preferably 90% or more, and more preferably 95% or more.

(33) (11) Voltage Holding Ratio (VHR-4; Measured at 25 C.; %):

(34) A TN device into which a sample was poured was heated in a constant-temperature bath at 80 C. for 500 hours, and then the stability to heat was evaluated by measuring the voltage holding ratio. In the measurement of VHR-4, a decreasing voltage was measured for 16.7 milliseconds. A composition having a large VHR-4 has a high stability to heat.

(35) (12) Response Time (; Measured at 25 C.; Millisecond):

(36) An LCD evaluation system Model LCD-5100 made by Otsuka Electronics Co., Ltd. was used for measurement. The light source was a halogen lamp. The low-pass filter was set at 5 kHz. A sample was poured into a FFS device assembled in Examples described below. This device was sealed with a UV-curable adhesive. Rectangular waves (60 Hz, 0.5 second) with a voltage where the amount of light passed through the device became maximum were applied to this device. The device was simultaneously irradiated with light in the perpendicular direction, and the amount of light passing through the device was measured. The transmittance was regarded as 100% when the amount of light reached a maximum. The transmittance was regarded as 0% when the amount of light reached a minimum. The response time was expressed as the period of time required for the change from 90% to 10% transmittance (fall time: millisecond). The response time is preferably 60 ms or less, and more preferably 40 ms or less.

(37) (13) Elastic Constants (K11: Splay Elastic Constant, K33: Bend Elastic Constant; Measured at 25 C.; pN):

(38) An elastic constant measurement system Model EC-1 made by Toyo Corporation was used for measurement. A sample was poured into a homeotropic device in which the distance between the two glass substrates (cell gap) was 20 micrometers. An electric charge of 20 volts to 0 volts was applied to this device, and electrostatic capacity and applied voltage were measured. The values of the electrostatic capacity (C) and the applied voltage (V) were fitted to the equation (2.98) and the equation (2.101) in page 75 of the Ekisho Debaisu Handobukku (Liquid Crystal Device Handbook, in English; The Nikkan Kogyo Shimbun, Ltd., Japan), and the value of the elastic constant was obtained from the equation (2.100).

(39) (14) Specific Resistance (; Measured at 25 C.; cm):

(40) A sample of 1.0 milliliter was poured into a vessel equipped with electrodes. A DC voltage (10 V) was applied to the vessel, and the DC current was measured after 10 seconds. The specific resistance was calculated from the following equation. (specific resistance)=[(voltage)(electric capacity of vessel)]/[(DC current)(dielectric constant in vacuum)].

(41) (15) Flicker Rate (Measured at 25 C.; %):

(42) A multimedia display tester 3298F made by Yokogawa Electric Corporation was used for measurement. The light source was LED. A sample was poured into a FFS device assembled in Examples described below. This device was sealed with a UV-curable adhesive. A voltage was applied to the device and a voltage was measured when the amount of light passed through the device reached a maximum. The sensor was approximated to the device while this voltage was applied to the device, and the flicker rate displayed was recorded. The flicker rate is preferably 2% or less, and more preferably 1% or less.

(43) (16) Weight Average Molecular Weight (Mw):

(44) The weight average molecular weight of a polyamic acid was measured by a GPC method using 2695 separation module 2414 differential refractometer made by Waters Corporation, and was expressed in terms of polystyrene equivalents. The resulting polyamic acid was diluted with a phosphoric acid-DMF mixed solution (phosphoric acid/DMF=0.6/100, in weight ratio), giving about approximately 2% by weight concentration of the polyamic acid. A column used was HSPgel RT MB-M made by Waters Corporation, and the measurement was carried out under the conditions of 50 C. of the column temperature and 0.40 mL/min of the current velocity using the mixed solvent as an eluent A TSK standard polystyrene made by Tosoh Corporation was used as the standard polystyrene.

(45) (17) Pretilt Angle:

(46) A spectroscopic ellipsometer M-2000U made by J. A. Woollam Co. Inc. was used for the measurement of pretilt angles.

(47) (18) AC Ghost Images (Brightness Change):

(48) In the liquid crystal display device that will be described below, the brightness-voltage characteristics (B-V characteristics) were measured. This was referred to as brightness-voltage characteristics before stressed [B (before)]. Next, direct current 4.5 V, 60 Hz) was applied for 20 minutes to the device, and no voltages for 1 second, and then the brightness-voltage characteristics (B-V characteristics) were measured again. This was referred to as brightness-voltage characteristics after stressed [B (after)]. The brightness change (B; %) was calculated from these values by the following equation:
B(%)=[B(after)B(before)]/B(before)(equation 1)
These measurements were carried out by referring WO 2000-43833 A. The smaller value of B (%) at a voltage of 0.75 V means a smaller generation of AC ghost images.
(19) Orientational Stability (Stability of Liquid Crystal Orientational Axis):

(49) In the liquid crystal display device that will be described below, the change of a liquid crystal orientational axis in a side of electrode was evaluated. Liquid crystal orientation angle [(before)] before stressed in the side of an electrode was measured, and rectangular waves (4.5 V, 60 Hz) were applied for 20 minutes to the device, and no voltages for 1 second, and then the liquid crystal orientation angle [(after)] in the side of the electrode was measured after 1 second and 5 minutes. The change (, deg.) of the liquid crystal orientation angle after 1 second and 5 minutes was calculated from these values by the following equation:
(deg.)=(after)(before)(equation 2)
These measurements was carried out by referring J. Hilfiker, B. Johs, C. Herzinger, J. F. Elman, E. Montbach, D. Bryant, and P. J. Bos, Thin Solid Films, 455-456, (2004) 596-600. The smaller value of AT means a smaller change ratio of the liquid crystal orientational axis, which means that the stability of liquid crystal orientational axis is better.
(20) Volume Resistivity (; Measured at 25 C.; .Math.cm):

(50) A polyimide film was formed on a glass substrate covered with ITO entirely. Aluminum was deposited to the side of the alignment film on the substrate, which was referred to as an upper electrode (electrode surface area: 0.23 cm.sup.2). A voltage of 3 V was applied between the ITO electrode and the upper electrode, and the volume resistivity was calculated from a current value after 300 seconds.

(51) (21) Permittivity (; Measured at 25 C.):

(52) A polyimide film was prepared on a substrate covered with ITO entirely. Aluminum was deposited to the side of the alignment film on the substrate, which was referred to as an upper electrode (electrode surface area: 0.23 cm.sup.2). A voltage of 3 V was applied between the ITO electrode and the upper electrode, and an AC voltage (1 V, frequency 1 kHz) was applied, and the electric capacity (C) of the film was measured. The permittivity (r) of the film was calculated from this value by the following equation.
=(Cd)/(.sub.0S)(equation 3)
where d is the film thickness of the polyimide film, .sub.0 is permittivity in vacuum, and S is the electrode surface.
(22) Abbreviations:

(53) Abbreviations of Solvents and additives used in Examples are as follows.

(54) Solvent

(55) NMP: N-Methyl-2-pyrrolidone.

(56) BC: Butyl cellosolve (ethylene glycol monobutyl ether).

(57) Additive

(58) Additive (Ad1): Bis[4-(allylbicyclo[2.2.1]hept-5-ene-2,3-dicarboximide)phenyl]methane.

(59) Additive (Ad2): N,N,N,N-Tetraglycidyl-4,4-diaminodiphenylmethane.

(60) Additive (Ad3): 3-Aminopropyltriethoxysilane.

(61) Additive (Ad4): 2-(3,4-Epoxycyclohexyl)ethyltrimethoxysilane.

(62) The compounds described in Examples were expressed in terms of symbols according to the definition in Table 3 described below. In Table 3, the configuration of 1,4-cyclohexylene is trans. The parenthesized number next to a symbolized compound in Example indicates the number of the compound. The symbol () means any other liquid crystal compound. The proportion (percentage) of a liquid crystal compound means the percentages by weight (% by weight) based on the weight of the liquid crystal composition. Last, the values of characteristics of the composition are summarized.

(63) TABLE-US-00003 TABLE 3 Method of 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 FC.sub.nH.sub.2n Fn 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.2CHCnH.sub.2n Vn CmH.sub.2m+1CHCHCnH.sub.2n mVn CF.sub.2CH VFF CF.sub.2CHCnH.sub.2n VFFn CH.sub.2CHCOO AC CH.sub.2C(CH.sub.3)COO MAC 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.mH.sub.2mCHCHC.sub.nH.sub.2n+1 mVn CHCF.sub.2 VFF OCOCHCH.sub.2 AC OCOC(CH.sub.3)CH.sub.2 MAC F F CN C 3) Bonding Group Z.sub.n Symbol C.sub.nH.sub.2n n COO E CHCH V CC T CHCHO VO OCHCH OV CH.sub.2O 1O OCH.sub.2 O1 4) Ring An Symbol 06 H 07 B 08 B(F) 09 B(2F) 0 B(F,F) B(2F,5F) B(2F,3F) B(2F,3CL) B(2F,3F,6Me) dh Dh ch Cro(7F,8F) 5) Examples of Description Example 1. VHBB2 Example 2. 3HHB(2F,3F)O2 0

Composition Example M1

(64) TABLE-US-00004 3-HB(2F,3F)-O2 (1-1) 10% 5-HB(2F,3F)-O2 (1-1) 10% 3-H2B(2F,3F)-O2 (1-3) 8% 5-H2B(2F,3F)-O2 (1-3) 8% 3-HDhB(2F,3F)-O2 (1-13) 5% 3-HBB(2F,3F)-O2 (1-15) 8% 4-HBB(2F,3F)-O2 (1-15) 5% 5-HBB(2F,3F)-O2 (1-15) 5% V-HBB(2F,3F)-O2 (1-15) 5% V2-HBB(2F,3F)-O2 (1-15) 5% 3-HH-4 (2-1) 14% V-HHB-1 (2-5) 11% 3-HBB-2 (2-6) 6% NI = 89.4 C.; Tc<30 C.; n = 0.109; = 3.8; Vth = 2.24 V; = 24.6 mPa .Math. s; VHR-1 = 99.2%; VHR-2 = 98.1%; VHR-3 = 97.9%.

Composition Example M2

(65) TABLE-US-00005 3-HB(2F,3F)-O2 (1-1) 10% V-HB(2F,3F)-O2 (1-1) 7% 3-BB(2F,3F)-O2 (1-5) 7% V2-BB(2F,3F)-O1 (1-5) 7% 3-B(2F,3F)B(2F,3F)-O2 (1-6) 3% 2-HHB(2F,3F)-O2 (1-7) 5% 3-HHB(2F,3F)-O2 (1-7) 10% 3-HBB(2F,3F)-O2 (1-15) 10% V-HBB(2F,3F)-O2 (1-15) 8% 2-HH-3 (2-1) 14% 3-HB-O1 (2-2) 5% 3-HHB-1 (2-5) 3% 3-HHB-O1 (2-5) 3% 3-HHB-3 (2-5) 5% 2-BB(F)B-3 (2-7) 3% NI = 72.5 C.; Tc<20 C.; n = 0.112; = 3.9; Vth = 2.14 V; = 22.8 mPa .Math. s.

Composition Example M3

(66) TABLE-US-00006 3-HB(2F,3F)-O4 (1-1) 6% 3-H2B(2F,3F)-O2 (1-3) 8% 3-H1OB(2F,3F)-O2 (1-4) 5% 3-BB(2F,3F)-O2 (1-5) 10% 3-HHB(2F,3F)-O2 (1-7) 7% V-HHB(2F,3F)-O2 (1-7) 7% V-HHB(2F,3F)-O4 (1-7) 7% 3-HBB(2F,3F)-O2 (1-15) 6% V-HBB(2F,3F)-O2 (1-15) 6% 1V2-HBB(2F,3F)-O2 (1-15) 5% 3-HH-V (2-1) 11% 1-BB-3 (2-3) 6% 3-HHB-1 (2-5) 4% 3-HHB-O1 (2-5) 4% 3-HBB-2 (2-6) 5% 3-B(F)BB-2 (2-8) 3% NI = 87.7 C.; Tc<30 C.; n = 0.129; = 4.4; Vth = 2.17 V; = 26.2 mPa .Math. s.

Composition Example M4

(67) TABLE-US-00007 3-HB(2F,3F)-O2 (1-1) 7% 1V2-HB(2F,3F)-O2 (1-1) 7% 3-BB(2F,3F)-O2 (1-5) 8% 3-HHB(2F,3F)-O2 (1-7) 5% 5-HHB(2F,3F)-O2 (1-7) 4% 3-HH1OB(2F,3F)-O2 (1-10) 5% 2-BB(2F,3F)B-3 (1-11) 4% 2-HBB(2F,3F)-O2 (1-15) 3% 3-HBB(2F,3F)-O2 (1-15) 8% 4-HBB(2F,3F)-O2 (1-15) 5% V-HBB(2F,3F)-O2 (1-15) 8% 3-HH-V (2-1) 27% 3-HH-V1 (2-1) 6% V-HHB-1 (2-5) 3% NI = 78.2 C.; Tc < 30 C.; n = 0.109; = 3.3; Vth = 2.08 V; = 16.3 mPa .Math. s.

Composition Example M5

(68) TABLE-US-00008 3-HB(2F,3F)-O4 (1-1) 15% 3-chB(2F,3F)-O2 (1-2) 7% 2-HchB(2F,3F)-O2 (1-8) 8% 3-HBB(2F,3F)-O2 (1-15) 8% 5-HBB(2F,3F)-O2 (1-15) 7% V-HBB(2F,3F)-O2 (1-15) 5% 3-dhBB(2F,3F)-O2 (1-16) 5% 5-HH-V (2-1) 18% 7-HB-1 (2-2) 5% V-HHB-1 (2-5) 7% V2-HHB-1 (2-5) 7% 3-HBB(F)B-3 (2-13) 8% NI = 98.5 C.; Tc < 30 C.; n = 0.112; = 3.2; Vth = 2.47 V; = 23.5 mPa .Math. s.

Composition Example M6

(69) TABLE-US-00009 3-H2B(2F,3F)-O2 (1-3) 18% 5-H2B(2F,3F)-O2 (1-3) 17% 3-DhHB(2F,3F)-O2 (1-12) 5% 3-HHB(2F,3CL)-O2 (1-18) 5% 3-HBB(2F,3CL)-O2 (1-19) 8% 5-HBB(2F,3CL)-O2 (1-19) 7% 3-HH-V (2-1) 11% 3-HH-VFF (2-1) 7% F3-HH-V (2-1) 10% 3-HHEH-3 (2-4) 4% 3-HB(F)HH-2 (2-9) 3% 3-HHEBH-3 (2-10) 5% NI = 78.2 C.; Tc < 30 C.; n = 0.084; = 2.6; Vth = 2.45 V; = 22.5 mPa .Math. s.

Composition Example M7

(70) TABLE-US-00010 3-H2B(2F,3F)-O2 (1-3) 7% V-HHB(2F,3F)-O2 (1-7) 8% 2-HchB(2F,3F)-O2 (1-8) 8% 3-HH1OB(2F,3F)-O2 (1-10) 5% 2-BB(2F,3F)B-3 (1-11) 7% 2-BB(2F,3F)B-4 (1-11) 7% 3-HDhB(2F,3F)-O2 (1-13) 3% 3-DhH1OB(2F,3F)-O2 (1-14) 4% 4-HH-V (2-1) 15% 3-HH-V1 (2-1) 6% 1-HH-2V1 (2-1) 5% 3-HH-2V1 (2-1) 5% V2-BB-1 (2-3) 5% 1V2-BB-1 (2-3) 5% 3-HHB-1 (2-5) 6% 3-HB(F)BH-3 (2-12) 4% NI = 87.5 C.; Tc < 30 C.; n = 0.115; = 2.0; Vth = 2.82 V; = 17.2 mPa .Math. s.

Composition Example M8

(71) TABLE-US-00011 V-HB(2F,3F)-O2 (1-1) 8% 3-H2B(2F,3F)-O2 (1-3) 10% 3-BB(2F,3F)-O2 (1-5) 10% 2O-BB(2F,3F)-O2 (1-5) 3% 2-HHB(2F,3F)-O2 (1-7) 4% 3-HHB(2F,3F)-O2 (1-7) 7% V-HHB(2F,3F)-O2 (1-7) 5% 2-BB(2F,3F)B-3 (1-11) 6% 2-BB(2F,3F)B-4 (1-11) 6% 3-HDhB(2F,3F)-O2 (1-13) 6% 2-HBB(2F,3F)-O2 (1-15) 5% 3-HBB(2F,3F)-O2 (1-15) 6% 3-dhBB(2F,3F)-O2 (1-16) 4% 3-HH1OCro(7F,8F)-5 (1-21) 4% 3-HH-V (2-1) 11% 1-BB-5 (2-3) 5% NI = 70.9 C.; Tc < 20 C.; n = 0.129; = 4.4; Vth = 1.74 V; = 27.2 mPa .Math. s.

Composition Example M9

(72) TABLE-US-00012 3-HB(2F,3F)-O2 (1-1) 7% V-HB(2F,3F)-O2 (1-1) 8% 3-H2B(2F,3F)-O2 (1-3) 8% 3-BB(2F,3F)-O2 (1-5) 10% 2-HHB(2F,3F)-O2 (1-7) 4% 3-HHB(2F,3F)-O2 (1-7) 7% V-HHB(2F,3F)-O2 (1-7) 6% 3-HDhB(2F,3F)-O2 (1-13) 6% 2-HBB(2F,3F)-O2 (1-15) 5% 3-HBB(2F,3F)-O2 (1-15) 6% V-HBB(2F,3F)-O2 (1-15) 5% V2-HBB(2F,3F)-O2 (1-15) 4% 3-HEB(2F,3F)B(2F,3F)-O2 (1-17) 3% 3-H1OCro(7F,8F)-5 (1-20) 3% 3-HH-O1 (2-1) 5% 1-BB-5 (2-3) 4% V-HHB-1 (2-5) 4% 5-HBBH-3 (2-11) 5% NI = 81.5 C.; Tc < 30 C.; n = 0.122; = 4.7; Vth = 1.76 V; = 31.8 mPa .Math. s.

Composition Example M10

(73) TABLE-US-00013 V-HB(2F,3F)-O4 (1-1) 14% V-H1OB(2F,3F)-O2 (1-4) 3% 3-BB(2F,3F)-O2 (1-5) 10% 3-HHB(2F,3F)-O2 (1-7) 7% V2-HHB(2F,3F)-O2 (1-7) 7% V-HH1OB(2F,3F)-O2 (1-10) 6% V-HBB(2F,3F)-O4 (1-15) 9% 1V2-HBB(2F,3F)-O2 (1-15) 5% 3-HH-V (2-1) 13% 1-BB-3 (2-3) 3% 3-HHB-1 (2-5) 4% 3-HHB-O1 (2-5) 4% V-HBB-2 (2-6) 5% 1-BB(F)B-2V (2-7) 6% 5-HBBH-1O1 () 4% NI = 93.6 C.; Tc < 30 C.; n = 0.125; = 3.9; Vth = 2.20 V; = 29.9 mPa .Math. s.

Composition Example M11

(74) TABLE-US-00014 3-HB(2F,3F)-O4 (1-1) 6% 3-H2B(2F,3F)-O2 (1-3) 8% 3-H1OB(2F,3F)-O2 (1-4) 4% 3-BB(2F,3F)-O2 (1-5) 7% 3-HHB(2F,3F)-O2 (1-7) 10% V-HHB(2F,3F)-O2 (1-7) 7% V-HHB(2F,3F)-O4 (1-7) 7% 3-HBB(2F,3F)-O2 (1-15) 6% V-HBB(2F,3F)-O2 (1-15) 6% 1V2-HBB(2F,3F)-O2 (1-15) 5% 2-HH-3 (2-1) 12% 1-BB-3 (2-3) 6% 3-HHB-1 (2-5) 4% 3-HHB-O1 (2-5) 4% 3-HBB-2 (2-6) 5% 3-B(F)BB-2 (2-7) 3% NI = 92.8 C.; Tc < 20 C.; n = 0.126; = 4.4; Vth = 2.19 V; = 26.0 mPa .Math. s.

Composition Example M12

(75) TABLE-US-00015 3-HB(2F,3F)-O2 (1-1) 5% 1V2-HB(2F,3F)-O2 (1-1) 7% V2-BB(2F,3F)-O2 (1-5) 8% 3-HHB(2F,3F)-O2 (1-7) 5% 5-HHB(2F,3F)-O2 (1-7) 4% 3-HH1OB(2F,3F)-O2 (1-10) 5% 2-BB(2F,3F)B-3 (1-11) 4% 2-HBB(2F,3F)-O2 (1-15) 3% 3-HBB(2F,3F)-O2 (1-15) 8% 4-HBB(2F,3F)-O2 (1-15) 5% V-HBB(2F,3F)-O2 (1-15) 8% 3-HH-V (2-1) 27% 3-HH-V1 (2-1) 6% V-HHB-1 (2-5) 5% NI = 81.7 C.; Tc < 20 C.; n = 0.110; = 3.2; Vth = 2.12 V; = 15.8 mPa .Math. s.

Composition Example M13

(76) TABLE-US-00016 3-HB(2F,3F)-O2 (1-1) 7% 1V2-HB(2F,3F)-O2 (1-1) 7% 3-BB(2F,3F)-O2 (1-5) 8% 3-HHB(2F,3F)-O2 (1-7) 5% 5-HHB(2F,3F)-O2 (1-7) 4% 3-HH1OB(2F,3F)-O2 (1-10) 5% 2-BB(2F,3F)B-3 (1-11) 4% 2-HBB(2F,3F)-O2 (1-15) 3% 3-HBB(2F,3F)-O2 (1-15) 8% 4-HBB(2F,3F)-O2 (1-15) 5% V-HBB(2F,3F)-O2 (1-15) 8% 3-HH-V (2-1) 33% V-HHB-1 (2-5) 3% NI = 76.0 C.; Tc < 30 C.; n = 0.107; = 3.2; Vth = 2.08 V; = 16.0 mPa .Math. s.

Composition Example M14

(77) TABLE-US-00017 3-HB(2F,3F)-O4 (1-1) 6% 3-H2B(2F,3F)-O2 (1-3) 8% 3-H1OB(2F,3F)-O2 (1-4) 4% 3-BB(2F,3F)-O2 (1-5) 7% V-HHB(2F,3F)-O2 (1-7) 7% V-HHB(2F,3F)-O4 (1-7) 7% 3-HH2B(2F,3F)-O2 (1-9) 7% 5-HH2B(2F,3F)-O2 (1-9) 3% 3-HBB(2F,3F)-O2 (1-15) 6% V-HBB(2F,3F)-O2 (1-15) 6% 1V2-HBB(2F,3F)-O2 (1-15) 5% 2-HH-3 (2-1) 12% 1-BB-5 (2-3) 12% 3-HHB-1 (2-5) 4% 3-HHB-O1 (2-5) 3% 3-HBB-2 (2-6) 3% NI = 83.6 C.; Tc < 30 C.; n = 0.122; = 4.4; Vth = 2.13 V; = 22.9 mPa .Math. s.

Composition Example M15

(78) TABLE-US-00018 2-H1OB(2F,3F)-O2 (1-4) 6% 3-H1OB(2F,3F)-O2 (1-4) 4% 3-BB(2F,3F)-O2 (1-5) 3% 2-HH1OB(2F,3F)-O2 (1-10) 14% 3-HBB(2F,3F)-O2 (1-15) 11% V-HBB(2F,3F)-O2 (1-15) 10% V-HBB(2F,3F)-O4 (1-15) 6% 2-HH-3 (2-1) 5% 3-HH-VFF (2-1) 30% 1-BB-3 (2-3) 5% 3-HHB-1 (2-5) 3% 3-HBB-2 (2-6) 3% NI = 77.8 C.; Tc < 20 C.; n = 0.105; = 3.2; Vth = 2.17 V; = 18.9 mPa .Math. s.
1. Preparation of Polyamic Acid Solutions (Component A)

Synthetic Example 1

(79) In a brown four-neck flask 50 mL equipped with a thermometer, a stirrer, an inlet for starting materials and a nitrogen gas inlet, 1.7806 g of diamine (DI-5-12, m=5) and 18.5 g of dry NMP were placed, and stirred to dissolve under a stream of dry nitrogen. Then, 1.2194 g of tetracarboxylic acid dianhydride (XI-1-1) and 18.5 g of dry NMP were added, and the mixture was stirred at room temperature for 24 hours. 10.0 g of BC was added to this reaction mixture to give a polyamic acid solution with a polymer solid content of 6% by weight. The polyamic acid solution was referred to as PAA1. The weight-average molecular weight of the polyamic acid included in PAA1 was 38,000.

Synthetic Examples 2 to 16

(80) Polyamic acid solutions (PAA2) to (PAA16) with a polymer solid content of 6% by weight were prepared according to Synthetic Example 1 except that the type of tetracarboxylic acid dianhydrides and diamines were changed. Polyamic acid solutions (PAA1) to (PAA16) were referred to as component A. Table 4 summarizes the results.

(81) TABLE-US-00019 TABLE 4 Preparation pf polyamic acids (PAA1) to (PAA16) Starting materials of the Polyamic acids Weight Synthetic Polyamic Tetracarboxylic average Examples acids acid dianhydrides Diamines molecular No.. No. (mol %) (mol %) weight 1 PAA1 XI-1-1 (100) DI-5-12 (100) 38,000 (m = 5) 2 PAA2 XI-1-1 (100) DI-5-12 (50) 42,000 (m = 5) DI-4-1 (50) 3 PAA3 XI-1-2 (100) DI-5-12 (100) 41,500 (m = 5) 4 PAA4 XI-1-2 (100) DI-5-12 (50) 35,250 (m = 5) DI-4-1 (50) 5 PAA5 XI-1-3 (100) DI-5-12 (100) 45,650 (m = 5) 6 PAA6 XI-1-3 (100) DI-5-12 (50) 40,420 (m = 5) DI-4-1 (50) 7 PAA7 XI-1-5 (100) DI-5-12 (100) 41,100 (m = 5) 8 PAA8 XI-1-5 (100) DI-5-12 (50) 37,800 (m = 5) DI-4-1 (50) 9 PAA9 XI-1-1 (100) DI-5-12 (80) 45,200 (m = 5) DI-4-d (20) 10 PAA10 XI-1-5 (100) DI-5-12 (80) 38,500 (m = 5) DI-4-d (20) 11 PAA11 XI-1-1 (100) DI-4-1 (80) 42,000 DI-4-d (20) 12 PAA12 XI-1-5 (100) DI-4-1 (80) 35,900 DI-4-d (20) 13 PAA13 XI-1-1 (100) DI-5-28 (100) 45,000 14 PAA14 XI-12 (100) DI-5-28 (100) 47,250 15 PAA15 AN-1-1 (100) DI-5-28 (100) 44,000 16 PAA16 XI-1-1 (100) DI-5-12 (100) 41,200 (m = 2)

2. Preparation of Polyamic Acid Ester Solutions (Component B)

Synthetic Example 17

(82) In a brown four-neck flask 50 mL equipped with a thermometer, a stirrer, an inlet for starting materials and a nitrogen gas inlet, 1.4725 g of diamine (DI-5-12, m=5), 18.5 g of dry NMP and 0.407 g of pyridine as a base were placed, and stirred to dissolve under a stream of dry nitrogen. Then, 1.5275 g of dimethyl-1,3-bis(chlorocarbonyl)-1,3-dimethylcyclobutane-2,4-dicarboxylate and 18.5 g of dry NMP were added, and the mixture was stirred under water-cooling for 6 hours. The pyridine was removed by distillation, and 10.0 g of NMP was added to this reaction mixture to give a polyamic acid ester solution with a polymer solid content of 6% by weight. The polyamic acid ester solution was referred to as PAE1. The weight-average molecular weight of the polyamic acid ester included in PAE1 was 11,000.

Synthetic Examples 18 to 27

(83) Polyamic acid ester solutions (PAE2) to (PAE11) with a polymer solid content of 6% by weight were prepared according to Synthetic Example 17 except that the type of tetracarboxylic acid diester dichlorides and diamines were changed. Polyamic acid ester solutions (PAE2) to (PAE11) were referred to as component B. Table 5 summarizes the results.

(84) TABLE-US-00020 TABLE 5 Preparation of polyamic acid esters (PAE1) to (PAE11) Starting materials of the Polyamic acid esters Weight Polyamic Tetracarboxylic average Synthetic acid acid diester molec- Examples esters dichlorides.sup.1)2) Diamines ular No. No. (mol %) (mol %) weight 17 PAE1 Compound (100) DI-5-12 (100) 11,000 (d-2) (m = 5) 18 PAE2 Compound (100) DI-5-12 (50) 11,250 (d-2) (m = 5) DI-4-1 (50) 19 PAE3 Compound (100) DI-4-1 (100) 12,050 (d-2) 20 PAE4 Compound (100) DI-5-12 (100) 10,200 (d-1) (m = 5) 21 PAE5 Compound (100) DI-5-12 (50) 9,800 (d-1) (m = 5) DI-4-1 (50) 22 PAE6 Compound (100) DI-4-1 (100) 10,500 (d-1) 23 PAE7 Compound (100) DI-4-10 (50) 10,700 (d-2) DI-4-1 (50) 24 PAE8 Compound (100) DI-5-12 (100) 11,050 (d-2) (m = 2) 25 PAE9 Compound (100) DI-5-12 (70) 12,040 (d-2) (m = 2) DI-4-1 (30) 26 PAE10 Compound (100) DI-5-12 (100) 10,030 (d-1) (m =2) 27 PAE11 Compound (100) DI-5-12 (70) 9,900 (d-1) (m = 2) DI-4-1 (30) .sup.1)Compound (d-1): Dimethyl 1,3-bis(chlorocarbonyl)cyclobutan-2,4-dicarboxylate .sup.2)Compound (d-2): Dimethyl 1,3-bis(chlorocarbonyl)-1,3-dimethylcyclobutan-2,4-dicarboxylate

Example 1

(85) Formation of an Alignment Film from the Polyamic Acid

(86) A mixed solvent of NMP/BC=4/1 (ratio by weight) was added to polyamic acid solution (PAA1) with a polymer solid content of 6% by weight prepared in Synthetic Example 1 to give the liquid crystal aligning agent with a polymer solid content of 4% by weight. The liquid crystal aligning agent was applied to a glass substrate with a column spacer and a glass substrate with an ITO electrode, with a spinner (a spin coater 1H-DX2 made by Mikasa Co., Ltd). Incidentally, the film thickness described below was adjusted by changing the rotating rate of the spinner according to the viscosity of liquid crystal aligning agents, which was applied to the following Examples and Comparative Examples. The coating film was heated and dried at 70 C. for 80 seconds on a hot-plate (an EC hot-plate EC-1200N made by As One Corporation). Then, the coating film was heated at 230 C. for 20 minutes in a clean oven (a clean oven PVHC-231 made by Espec Corporation) to form an alignment film with film thickness of 10010 nm. The substrate was vertically irradiated with linearly polarized ultraviolet light via a polarizing plate using Multilight ML-501C/B made by Ushio, Inc. The amount of light was measured with an accumulated UV meter UIT-150 (receiver UVD-5365) made by Ushio, Inc. and the exposure energy was adjusted to be 0.50.1 J/cm.sup.2 at a wavelength of 254 nm by changing the exposure time. After irradiation, the substrate was immersed in ethyl lactate for 3 minutes, and in hyperpure water for 1 minute, and dried at 200 C. for 10 minutes in the clean oven.

(87) Production of Devices

(88) An FFS device was assembled in which two substrates were pasted together, the surfaces of the alignment films were inside, and the directions of linearly polarized ultraviolet light were parallel, and the distance between the substrates was 4 micrometers. An injection inlet for liquid crystals was arranged to the position where the flow direction of liquid crystals was roughly parallel to the linearly polarized ultraviolet light. The liquid crystal composition in Composition Example M1 was injected to this FFS device, and the response time and the flicker rate were measured. Table 6 summarizes the results. Incidentally, the liquid crystal composition in Composition Example M1 is abbreviated to Composition M1. The same rule applies to other liquid crystal compositions.

Examples 2 to 13

(89) A mixed solvent of NMP/BC=4/1 (ratio by weight) was added to each of polyamic acid solutions (PAA2) to (PAA12), prepared in Synthetic Examples 2 to 12 and Synthetic Example 16, with a polymer solid content of 6% by weight to give a liquid crystal aligning agent with a polymer solid content of 4% by weight. The device was produced in a similar manner, and the response time and the flicker rate were measured. Table 6 summarizes the results.

(90) TABLE-US-00021 TABLE 6 Response time and Flicker rate (Part 1) Polyamic Characteristics Examples acids Compositions Response time Flicker rate No. No. No. (ms) (%) 1 PAA1 M1 43.5 0.34 2 PAA2 M2 44.4 0.26 3 PAA3 M3 46.2 0.19 4 PAA4 M4 31.0 0.50 5 PAA5 M5 44.9 0.24 6 PAA6 M7 30.2 0.59 7 PAA7 M8 48.6 0.36 8 PAA8 M9 56.7 0.26 9 PAA9 M10 58.2 0.43 10 PAA10 M11 48.9 0.21 11 PAA11 M12 30.8 0.51 12 PAA12 M13 31.1 0.49 13 PAA16 M14 43.3 0.48

Example 14

(91) Formation of Alignment Films from the Polyamic Acid and the Polyamic Acid Ester

(92) Polyamic acid solution (PAA13) with a polymer solid content of 6% by weight, which is prepared in Synthetic Example 13, and polyamic acid ester solution (PAE1) with a polymer solid content of 6% by weight, which is prepared in Synthetic Example 17, were mixed in the ratio of 7 to 3. A mixed solvent of NMP/BC=4/1 (weight ratio) was added to the mixture to give a liquid crystal aligning agent with a polymer solid content of 4% by weight. The liquid crystal aligning agent was applied to a glass substrate with a column spacer and a glass substrate with an ITO electrode, with a spinner (a spin coater 1H-DX2 made by Mikasa Co., Ltd). Incidentally, the film thickness described below was adjusted by changing the rotating rate of the spinner according to the viscosity of liquid crystal aligning agents, which was applied to the following Examples and Comparative Examples. The coating film was heated and dried at 70 C. for 80 seconds on a hot-plate (an EC hot-plate EC-1200N made by As One Corporation). Then, the coating film was heated at 230 C. for 20 minutes in a clean oven (a clean oven PVHC-231 made by Espec Corporation) to form an alignment film with film thickness of 10010 nm. The substrate was vertically irradiated with linearly polarized ultraviolet light via a polarizing plate using Multilight ML-501C/B made by Ushio, Inc. The amount of light was measured with an accumulated UV meter UIT-150 (receiver UVD-S365) made by Ushio, Inc. and the exposure energy was adjusted to be 0.50.1 J/cm.sup.2 at a wavelength of 254 nm by changing the exposure time. After irradiation, the substrate was immersed in ethyl lactate for 3 minutes, and in hyperpure water for 1 minute, and dried at 200 C. for 10 minutes in the clean oven.

(93) Production of Devices

(94) An FFS device was assembled in which two substrates were pasted together, the surfaces of the alignment films were inside, and the directions of linearly polarized ultraviolet light were parallel, and the distance between the substrates was 4 micrometers. An injection inlet for liquid crystals was arranged to the position where the flow direction of liquid crystals was roughly parallel to the linearly polarized ultraviolet light. The liquid crystal composition in Composition Example M1 was injected in vacuum to this FFS device, and the response time and the flicker rate were measured. Table 7 summarizes the results. Incidentally, the liquid crystal composition in Composition Example M1 is abbreviated to Composition M1. The same rule applies to other liquid crystal compositions.

Examples 15 to 49

(95) Component A was mixed with component B in a manner similar to that in Example 14, and a device was produced in a similar manner. The response time and the flicker rate were measured. Table 7 summarizes the results.

(96) TABLE-US-00022 TABLE 7 Response time and Flicker rate (Part 2) Starting materials of the Aligning agents Characteristics Examples Aligning Component A Component B Compositions Response Flicker No. agents No. (% by weight) (% by weight) No. time (ms) rate (%) 14 PA1 PAA13 (70) PAE1 (30) M1 43.5 0.27 15 PA2 PAA13 (70) PAE2 (30) M2 44.4 0.21 16 PA3 PAA13 (70) PAE3 (30) M3 46.2 0.14 17 PA4 PAA13 (70) PAE4 (30) M4 31.0 0.41 18 PA5 PAA13 (70) PAE5 (30) M5 44.9 0.20 19 PA6 PAA13 (70) PAE6 (30) M8 48.6 0.29 20 PA7 PAA13 (70) PAE7 (30) M10 58.2 0.34 21 PA8 PAA13 (70) PAE8 (30) M11 48.9 0.17 22 PA9 PAA13 (70) PAE9 (30) M12 30.8 0.44 23 PA10 PAA13 (70) PAE10 (30) M13 31.1 0.41 24 PA11 PAA13 (70) PAE11 (30) M14 43.3 0.38 25 PA12 PAA14 (70) PAE1 (30) M1 43.6 0.28 26 PA13 PAA14 (70) PAE2 (30) M2 44.2 0.22 27 PA14 PAA14 (70) PAE3 (30) M3 45.8 0.16 28 PA15 PAA14 (70) PAE4 (30) M4 30.9 0.39 29 PA16 PAA14 (70) PAE5 (30) M5 45.2 0.18 30 PA17 PAA14 (70) PAE6 (30) M8 47.9 0.31 31 PA18 PAA14 (70) PAE7 (30) M10 58.5 0.33 32 PA19 PAA14 (70) PAE8 (30) M11 48.7 0.16 33 PA20 PAA14 (70) PAE9 (30) M12 30.6 0.40 34 PA21 PAA14 (70) PAE10 (30) M13 30.6 0.37 35 PA22 PAA14 (70) PAE11 (30) M14 43.4 0.39 36 PA23 PAA15 (70) PAE1 (30) M1 42.9 0.25 37 PA24 PAA15 (70) PAE2 (30) M2 43.5 0.19 38 PA25 PAA15 (70) PAE3 (30) M3 47.1 0.12 39 PA26 PAA15 (70) PAE4 (30) M4 29.9 0.36 40 PA27 PAA15 (70) PAE5 (30) M5 44.4 0.19 41 PA28 PAA15 (70) PAE6 (30) M8 48.2 0.26 42 PA29 PAA15 (70) PAE7 (30) M10 56.7 0.31 43 PA30 PAA15 (70) PAE8 (30) M11 47.7 0.11 44 PA31 PAA15 (70) PAE9 (30) M12 30.3 0.45 45 PA32 PAA15 (70) PAE10 (30) M13 30.4 0.46 46 PA33 PAA15 (70) PAE11 (30) M14 44.1 0.37 47 PA34 PAA13 (80) PAE8 (20) M6 37.4 0.29 48 PA35 PAA14 (80) PAE8 (20) M7 30.1 0.47 49 PA36 PAA15 (80) PAE8 (20) M9 55.8 0.21

(97) In the third column of Table 6 and the fifth column of Table 7, the type of compositions injected to the FFS devices is described. These are the liquid crystal compositions prepared in Composition Example M1 to Composition Example M14. In these compositions, the maximum temperature (NI) is in the range of 70.9 C. to 98.5 C. The optical anisotropy (n) is in the range of 0.084 to 0.129. The dielectric anisotropy () is in the range of 2.0 to 4.7. The viscosity () is in the range of 15.8 mPa.Math.s to 29.9 mPa.Math.s. Fourteen liquid crystal compositions with different types of characteristics were injected to a liquid crystal display device with different types of alignment films, and then the response time and flicker rate of the device were measured.

(98) In a liquid crystal display device, a shorter response time is desirable. The response time is preferably 60 ms or less, and more preferably 40 ms or less. A smaller flicker rate is desirable. The flicker rate is preferably 2% or less, and more preferably 1% or less. The response time in Examples 1 to 34 was in the range of 29.9 ms to 58.5 ms and the flicker rate was in the range of 0.11% to 0.59%. These values fell within the more desirable ranges. From these results, we now conclude that the values of the response time and the flicker rate came within such a suitable range, although the types of components in the liquid crystal compositions and the alignment films were quite different. This is the first feature of the invention that is worthy of special mention. In the devices in Examples 4, 6 and 11, the flicker rates were 0.5% or more. The response time of these devices were 31.0 ms, 30.2 ms and 30.8 ms, respectively. These findings shows that the flicker rate is small even in the devices that have short response time. This is the second feature of the invention that is worthy of special mention.

INDUSTRIAL APPLICABILITY

(99) The liquid crystal display device of the invention has characteristics such as a short response time, a large voltage holding ratio, a low threshold voltage, a large contrast ratio, a long service life and a small flicker rate. The device thus can be used for a liquid crystal projector, a liquid crystal television and so forth.