Liquid crystal composition and liquid crystal display device

Abstract: Liquid crystal compositions are disclosed which have a high optical anisotropy in particular, are excellent in mutual solubility at low temperatures, and have a wide range of a nematic phase while satisfying various properties required for TN-LCD or STN-LCD display mode; and which comprise a first component, second component, and third component, the first component comprising at least one compound expressed by the general formula (1-1) or (1-2) wherein R 1 and R 2 independently represent an alkyl group having 1 to 10 carbon atoms; and rings A, B, and C independently represent 1,4-phenylene provided that at least one of the rings A, B, and C represents 1,4-phenylene in which H at a lateral position is replaced by F.

Description: The present invention relates to a novel nematic liquid crystal composition and a liquid crystal display device comprising the liquid crystal composition. More specifically, the invention relates to a liquid crystal composition suitable for twist nematic (TN) mode or super twist nematic (STN) mode, and relates to a liquid crystal display device comprising the liquid crystal composition. BACKGROUND ART Liquid crystal display devices (LCD) such as a twist nematic LCD (TN-LCD), a supertwist nematic LCD (STN-LCD), and an active matrix LCD (AM-LCD) have been proposed and put to practical use one after another. TN or STN liquid crystals used for such liquid crystal display devices are required (1) to exhibit a nematic liquid crystal phase at a wide range of temperatures including room temperature, (2) to have low threshold voltage to reduce electric power to be consumed, (3) to have low viscosity (η) to shorten response time (τ) as much as possible, (4) to be capable of having suitable optical anisotropy (Δn) depending on the type of liquid crystal display devices, and (5) to be chemically stable. In recent years, it is strongly required to provide LCDs which can cope with dynamic picture images, and various measures have been studied for each of LCD display modes. For instance, it is proposed by G. Bauer reported (Cryst. Liq., 63, 45(1981)) that the product (Δn · d) of the optical anisotropy (Δn) of a liquid crystal material to be filled in a cell multiplied by the thickness of the cell (d) µm is set at a certain value (for example, Δn · d = 0.5 and Δn · d = 1.0) in display modes using a TN liquid crystal, in which the direction of the orientation of liquid crystal molecules is twisted by 90° between the upper and lower substrates, to avoid the occurrence of interference patterns on the cell surface. According to the method, the value of d can be decreased when a liquid crystal material having a large value of Δn is used. When d becomes small, response time (τ) remarkably shortens since τ is directly proportional both to the viscosity (η) of a liquid crystal material and to the square of the cell thickness d. Accordingly, it is very useful for liquid crystal compositions used in such liquid crystal display devices to have a large value of Δn and low viscosity. On the other hand, in the display modes using a super twisted nematic (STN) liquid crystal, in which the direction of the orientation of liquid crystal molecules is twisted by 180 to 270° between the upper and lower substrates, proposed by T. J. Scheffer et al. (Appl. Phy. Lett., 45 (10), 1021 (1984)), the optical path length of birefringence Δn · d is adjusted to a certain value (for example, Δn · d = 0.85) since the modes use particularly interference color by the effect of birefringence for the display. According to the method, the response time (τ) remarkably shortens when a liquid crystal material having a large value of Δn is used, as described above. Thus, it is very useful also for STN liquid crystal compositions to have a large value of Δn. Liquid crystal compositions having a large value of Δn (for example, Δn ≧ 0.18) are required especially for an active addressing driving mode, electrically controlled birefringence mode, and so on. Further, in keeping with the downsizing of products comprising a liquid crystal display device to a portable size, developments of liquid crystal compositions with the object of using them outdoors have come to be conducted. In order to stand outdoor uses, liquid crystal compositions are required to exhibit a nematic phase in a range over that of environmental temperatures at which liquid crystal compositions are ordinarily used. From this point of view, it is principally required that an upper limit value of a nematic phase transition temperature of liquid crystal compositions (clearing point: T NI ) is equal to or higher than 80°C and a lower limit value of the nematic phase transition temperature (T L ) is equal to or below -30°C. As the prior art with the object of using liquid crystal compositions at a wide range of temperatures, some liquid crystal compositions are disclosed in DE 3,921,836 and Laid-open Japanese Patent Publication No. Sho 58-134,046. However, the DE 3,921,836 and Laid-open Japanese Patent Publication No. Sho 58-134,046 have not disclosed at all about a large value of Δn. Besides, the DE 3,921,836 and Laid-open Japanese Patent Publication No. Sho 58-134,046 have not specifically disclosed about the components in liquid crystal compositions and mixing ratio of the components in the compositions necessary for developing the characteristics of liquid crystal compositions. Whereas liquid crystal compositions are diligently studied depending on various purposes, it is the present situation that novel improvements are all the time required. DISCLOSURE OF THE INVENTION An object of the present invention is to provide liquid crystal compositions which have a large value of optical anisotropy (Δn) in particular, is excellent in miscibility at low temperatures, and have a wide range of a nematic phase while satisfying various properties required for TN-LCD or STN-LCD display modes. Other objects and advantages of the present invention will become apparent to those skilled in the art from the following description and appended claims. The present invention in order to achieve the objects described above is summarized as follows: (1) A liquid crystal composition comprising, as a first component, at least one compound expressed by the general formula (1-1) or (1-2) wherein R 1 and R 2 independently represent an alkyl group having 1 to 10 carbon atoms; and rings A, B, and C independently represent 1,4-phenylene provided that at least one of the rings A, B, and C represents 1,4-phenylene in which H at lateral position(s) are replaced by F, comprising, as a second component, at least one compound selected from the group consisting of the compounds expressed by the general formula (2-a), (2-b), (2-c), (2-d), or (2-e) wherein R 3 represents an alkyl group having 1 to 10 carbon atoms or an alkenyl group having 2 to 10 carbon atoms, any one or non-adjacent two or more methylene groups (-CH 2 -) in the alkyl or alkenyl group may be replaced by oxygen atom (-O-); Z 1 represents -COO-, -C 2 H 4 -, or single bond; Z 2 and Z 3 represent -C 2 H 4 - or single bond; Z 4 represents -COO-, -C 2 H 4 -, or single bond; D 1 represents trans-1,4-cycloheyxlene, 1,4-phenylene, or 1,3-dioxane-trans-2,5-diyl; D 2 , D 3 , D 4 , D 6 , and D 7 independently represent trans-1,4-cyclohexylene or 1,4-phenylene; D 5 represents trans-1,4-cyclohexylene or 1,4-phenylene, one H at a lateral position of the 1,4-phenylene may be replaced by F; and q and m are independently 0 or 1, and comprising, as a third component, at least one compound selected from the group consisting of the compounds expressed by the general formula (3) R 4 -G 1 -Z 5 -G 2 -R 5 wherein R 4 and R 5 independently represent an alkyl group having 1 to 10 carbon atoms or an alkenyl group having 2 to 10 carbon atoms, any one or non-adjacent two or more methylene groups (-CH 2 -) in the alkyl or alkenyl group may be replaced by oxygen atom (-O-); G 1 represents trans-1,4-cyclohexylene, 1,4-phenylene, or pyrimidine-2,5-diyl; G 2 represents trans-1,4-cycloheyxlene or 1,4-phenylene; and Z 5 represents -C≡C-, -CH=CH-, -C 2 H 4 -, -COO-, or single bond. (2) The liquid crystal composition recited in paragraph (1) above wherein the amount of the first component is 3 to 30 %, that of the second component is 30 to 70 %, and that of the third component is 10 to 50 %, respectively, based on the total weight of liquid crystal composition. (3) The liquid crystal composition recited in paragraph (1) or (2) above wherein the liquid crystal composition further comprises at least one compound selected from the group consisting of the compounds expressed by the general formula (4) or (5) R 6 ―J 1 ―Z 6 ―J 2 ―Z 7 ―J 3 ―R 7 wherein R 6 represents an alkyl group having 1 to 10 carbon atoms or an alkenyl group having 2 to 10 carbon atoms, any one or non-adjacent two or more methylene groups (-CH 2 -) in the alkyl or alkenyl group may be replaced by oxygen atom (-O-); R 7 represents an alkyl or alkoxy group having 1 to 10 carbon atoms, or alkoxymethyl group having 2 to 10 carbon atoms; J 1 represents trans-1,4-cycloheyxlene, 1,4-phenylene, or pyrimidine-2,5-diyl group; J 2 represents trans-1,4-cycloheyxlene or 1,4-phenylene, one H at a lateral position of the 1,4-phenylene may be replaced by F; J 3 represents trans-1,4-cycloheyxlene, 1,4-phenylene, or pyrimidine-2,5-diyl; Z 6 represents -C 2 H 4 -, -COO-, or single bond; Z 7 represents -C≡C-, -COO-, -CH=CH-, or single bond; and Q 1 represent H or F. (4) The liquid crystal composition recited in any one of paragraphs (1) to (3) above wherein the liquid crystal composition further comprises at least one compound selected from the group consisting of the compounds expressed by the general formula (6) or (7) wherein R 8 represents an alkyl group having 1 to 10 carbon atoms; I represents trans-1,4-cyclohexylene or 1,4-phenylene; Q 2 , Q 3 , and Q 4 independently represent H or F; Z 8 and Z 9 independently represent -COO-, -C 2 H 4 -, or single bond; k is 0 or 1; n is 0, 1, or 2; and X represents F or Cl. (5) A liquid crystal display device comprising a liquid crystal composition recited in any one of paragraphs (1) to (4) above. BEST MODE FOR CARRYING OUT THE INVENTION Now, the liquid crystal compounds constituting the liquid crystal compositions of the present invention are described in more detail. As the compounds of a first component of the liquid crystal compositions of the present invention expressed by the general formula (1-1) or (1-2), the following compounds can preferably be mentioned: In these formulas, R and R' represent an alkyl group having 1 to 10 carbon atoms. Compounds expressed by the general formula (1-1) or (1-2) are excellent in heat stability and chemical stability, and are used for the purpose of adjusting a nematic phase range, adjusting Δn, and/or adjusting viscosity. As the compounds of a second component of the liquid crystal compositions of the present invention expressed by the general formula (2-1), (2-b), (2-c), (2-d), or (2-e), the following compounds can preferably be mentioned: In these formulas, R represents an alkyl group having 1 to 10 carbon atoms or an alkenyl group having 2 to 10 carbon atoms, and R' represents an alkanediyl or alkenediyl. Among these compounds, compounds expressed by one of the formulas (2-a-1), (2-a-2), (2-a-3), (2-a-4), (2-a-5), (2-a-8), (2-b-1), (2-b-2), (2-b-3), (2-c-1), (2-c-4), (2-c-5), (2-c-6), (2-c-9), (2-c-10), (2-c-11), (2-d-1), (2-d-2), (2-e-1), and (2-e-2) are preferably used in particular. These compounds of the second component have a particularly large positive dielectric anisotropy and are used principally for the purpose of lowering threshold voltage and for the purpose of improving steepness which is important as STN characteristic. As the compounds of a third component of the liquid crystal compositions of the present invention expressed by the general formula (3), the following compounds can preferably be mentioned: In these formulas, R and R' independently represent an alkyl group or alkenyl group. Among these, compounds expressed by one of the formulas ((3-1), (3-2), (3-4), (3-5), (3-6), (3-8), (3-9), (3-13), (3-14), (3-18), and (3-19) are more preferably used as compounds of the general formula (3). Compounds of the third component expressed by the general formula (3) are two-ring system compounds having negative or small positive dielectric anisotropy. Compounds of the general formula (3) are used principally for the purpose of reducing viscosity and/or adjusting Δn. As the compounds expressed by the general formula (4) or (5), the following compounds can preferably be mentioned: In these formulas, R and R' independently represent an alkyl group or an alkenyl group. Among these, compounds expressed by one of the formulas (4-1), (4-2), (4-3), (4-5), (4-6), (4-8), (4-9), (4-11), (4-12), (4-14), (4-15), (5-2), and (5-3) are more preferably used as the compound expressed by the general formula (4) or (5) in the present invention. Compounds of the general formula (4) or (5) are three-ring or four-ring system compounds having negative or small positive dielectric anisotropy. Compounds of the general formula (4) are used for the purpose of widening a nematic phase range and/or phase adjusting Δn and viscosity. Compounds of the general formula (5) are used for the purpose of widening a nematic range and/or adjusting Δn. As the compounds expressed by the general formula (6) or (7), the following compounds can preferably be mentioned: In these formulas, R represents an alkyl group. As the compounds of the general formula (6), the compounds expressed by the formula (6-1), (6-2), or (6-3) are more preferably used in the present invention. As the compounds of the general formula (7), the compounds expressed by one of the formulas (7-1), (7-5), (7-6), (7-7), (7-8), (7-9), (7-10), (7-11), (7-12), (7-13), (7-14), (7-15), (7-16), (7-17), (7-18), (7-19), (7-20), (7-21), (7-22), (7-24), (7-28), (7-30), (7-31), and (7-32) are more preferably used in the present invention. Compounds of the general formula (6) or (7) have positive dielectric anisotropy and are used for the purpose of particularly lowering threshold voltage and for the purpose of improving its dependency on temperature. They are also used for the purpose of adjusting viscosity, adjusting Δn, and widening a nematic phase range such as raising a clearing point. Amount of the first component to be used in the present invention is preferably 3 to 30 % by weight and more preferably 5 to 20 % by weight based on the total amount of liquid crystal composition, respectively. When the amount is less than 3 % by weight, the effect of a large value of Δn, which is a principal subject of the present invention, can hardly be achieved, and when it exceeds 30 % by weight, miscibility of liquid crystal compositions at low temperatures sometimes becomes poor. Amount of the second component to be used is preferably 30 to 70 % by weight and more preferably 40 to 70 % by weight based on the total amount of liquid crystal composition, respectively. When the amount is less than 30 % by weight, threshold voltage of liquid crystal compositions sometimes becomes high, and when it exceeds 70 % by weight, the effect of a large value of Δn, which is a principal subject of the present invention, can hardly be achieved. Amount of the third component to be used is preferably 10 to 50 % by weight and more preferably 10 to 40 % by weight based on the total amount of liquid crystal composition, respectively. When the amount is less than 10 % by weight, viscosity of liquid crystal compositions sometimes becomes high, and when it exceeds 50 % by weight, a nematic range of liquid crystal compositions sometimes becomes narrow. Amount of the compounds of the general formula (4) or (5) to be used is preferably less than 40 % by weight and more preferably less than 30 % by weight based on the total amount of liquid crystal composition, respectively. When the amount exceeds 40 % by weight, threshold voltage of liquid crystal compositions sometimes becomes high. Amount of the compounds of the general formula (6) or (7) to be used is preferably less than 40 % by weight and more preferably less than 30 % by weight based on the total amount of liquid crystal composition, respectively. When the amount exceeds 40 % by weight, viscosity of liquid crystal compositions sometimes becomes high. Depending on the purposes of liquid crystal display devices to be used, liquid crystal compositions of the present invention may comprise other compounds in such a suitable range that the objects of the present invention are not spoiled, in addition to the compounds expressed by one of the general formulas (1) to (7), for the purpose of adjusting threshold voltage, a nematic phase range, Δn, dielectric anisotropy, and viscosity. Liquid crystal compositions of the present invention can be produced by methods which are conventional by themselves. In general, methods wherein various components are dissolved each other at a high temperature are employed. Liquid crystal materials of the present invention can be improved and optimized by adding suitable additives depending on intended uses. Such additives are well known in the art and described in the literatures in detail. Usually, a chiral dopant is added to induce a helical structure of liquid crystals and thereby adjust a required twisting angle and avoid a reverse-twist. Further, the liquid crystal compositions of the present invention can be used as ones for guest-host (GH) mode by adding a dichroic dye such as merocyanine type, styryl type, azo type, azomethine type, azoxy type, quinophthalone type, anthraquinone type, or tetrazine type dye. The liquid crystal compositions of the present invention can also be used for a nematic curvilinear aligned phase (NCAP) liquid crystal display device which is prepared by the microencapsulation of a nematic liquid crystal, and for a polymer dispersed liquid crystal display device (PDLCD) represented by a polymer network liquid crystal display device (PNLCD) prepared by forming polymers of three-dimensional reticulated structure in a liquid crystal. In addition, the liquid crystal compositions of the present invention can be used as ones for electrically controlled birefringence (ECB) mode or dynamic scattering (DS) mode. Now, the present invention will be described in more detail with reference to Examples and Comparative Examples. However, it should be understood that the scope of the present invention is by no means restricted by such specific examples. Amount of all compounds in the liquid crystal compositions in Examples and Comparative Examples is indicated in percentage by weight. Further, compounds used in Examples and Comparative Examples are designated according to the definition shown in Table 1 below. In the Examples and Comparative Examples, characteristics of liquid crystal compositions are shown by using an upper limit value of a nematic phase transition temperature (clearing point: T NI ), a lower limit value of a nematic phase transition temperature (T L ), viscosity at 20°C (η 20 ), optical anisotropy at 25°C (Δn), dielectric anisotropy at 25°C (Δε), and threshold voltage at 25°C (V th ). T L point was judged based on the condition of the phase of a sample liquid crystal composition 30 days after the liquid crystal composition was left in freezers kept at 0°C, -10°C, -20°C, and -30°C, respectively. Comparative Example 1 The following liquid crystal composition disclosed in Laid-open Japanese Patent Publication No. Sho 58-134,046 was prepared: 201-HBB-1 15.0 % 3-HB-C 25.5 % 5-HB-C 34.0 % 7-HB-C 25.5 % T NI = 60.7°C -10°C < T C < 0°C η 20 = 24.8 mPa·s Δn = 0.128 V th = 1.66 V This liquid crystal composition was poor in miscibility at low temperatures and narrow in the range of a nematic phase. Besides, its Δn was not sufficiently high and thus this liquid crystal composition is lacking in utility. Comparative Example 2 The following liquid crystal composition disclosed in DE 3,921,836 was prepared: 5-HBB(F)B-3 10.0 % ZLI-1565 (produced by Merck) 90.0 % T NI = 117.0°C -30°C < T L < -20°C η 20 = 17.6 mPa·s Δn = 0.163 Δε = 7.9 V th = 2.63 V Whereas this liquid crystal composition had a high clearing point, its miscibility at low temperature was poor. Thus, the composition is lacking in utility. Besides, its threshold voltage V th was high and thus the liquid crystal composition is lacking in utility even from this point of view. Example 1 5-HBB(F)B-2 10.0 % V2-HB-C 10.0 % 1V2-HB-C 10.0 % 3-HB-C 25.0 % 3-HHB-C 6.0 % 3-HH-4 11.0 % 4-BTB-O2 14.0 % 5-BTB-O1 14.0 % T NI = 81.7°C T L < -30°C η 20 = 17.7 mPa·s Δn = 0.169 Δε = 7.6 V th = 1.89 V This liquid crystal composition was excellent in miscibility at low temperatures, wide in the range of a nematic phase, and high in Δn. Example 2 5-HBB(F)B-3 15.0 % 3O1-BEB(F)-C 10.0 % 2-BEB-C 10.0 % 3-BEB-C 6.0 % 2-HB(F)-C 10.0 % 3-HB(F)-C 12.0 % 2-HHB(F)-C 10.0 % 3-HHB(F)-C 10.0 % 3-HB-O2 12.0 % 2-BTB-1 5.0 % T NI = 81.0°C T L < -30°C η 20 = 44.1 mPa·s Δn = 0.140 Δε = 18.3 V th = 1.06 V Example 3 1O1-HBB-2 5.0 % V2-HB-C 12.0 % 1V2-HB-C 12.0 % 3-HB-C 6.0 % 5-HB-C 10.0 % 2-HHB-C 6.0 % 3-HHB-C 6.0 % 4-HHB-C 6.0 % 5-HHB-C 6.0 % 6-PyB-O5 2.5 % 6-PyB-O6 2.5 % 6-PyB-O7 2.5 % 6-PyB-O8 2.5 % 2-PyB-2 3.4 % 3-PyB-2 3.3 % 4-PyB-2 3.3 % 2-BTB-1 11.0 % T NI = 80.8°C T L < -30°C η 20 = 23.6 mPa·s Δn = 0.154 Δε = 9.0 V th = 1.70 V Example 4 5-HBB(F)B-2 10.0 % 1V2-BEB(F,F)-C 12.0 % 3O1-BEB(F)-C 12.0 % 101-HB-C 12.0 % 2-HHB-C 4.0 % 3-HHB-C 5.0 % 5-HHB-C 7.0 % 1O1-HH-5 5.0 % 3-HEB-O4 3.2 % 4-HEB-O2 2.5 % 5-HEB-O1 2.5 % 3-HEB-O2 2.0 % 5-HEB-O2 1.6 % 4-HEB-O4 3.2 % 3-HHB-1 7.0 % 3-HHB-01 4.0 % 3-H2BTB-2 4.0 % 3-H2BTB-4 3.0 % T NI = 109.3°C T L < -30°C η 20 = 45.0 mPa·s Δn = 0.145 Δε = 20.5 V th = 1.41 V Example 5 5-HBB(F)B-2 5.0 % 2-BB-C 8.0 % 4-BB-C 6.0 % 2-HB-C 10.0 % 3-HB-C 13.0 % 2-HHB-C 4.0 % 3-HHB-C 6.0 % 3-HHEBB-C 2.0 % 3-HBEBB-C 2.0 % 2-BTB-01 12.0 % 3-HHB-3 15.0 % 5-PyB-F 6.0 % 3-PyBB-F 6.0 % 3-HHB-F 5.0 % T NI = 98.2°C T L < -30°C η 20 = 24.7 mPa·s Δn = 0.175 Δε = 10.3 V th = 1.72 V Example 6 5-HBB(F)B-2 5.0 % 301-HBB-2 4.0 % 2-HB(F)-C 11.0 % 3-DB-C 10.0 % 4-HEB-3 1.6 % 4-HEB-4 1.2 % 4-HEB-5 0.7 % 5-HEB-1 0.6 % 5-HEB-5 0.9 % 2-PYB-2 6.7 % 3-PyB-2 6.7 % 4-PyB-2 6.6 % 2-HHB-C 10.0 % 3-HHB-C 5.0 % 3-HHB(F)-C 8.0 % 3-PyBH-2 4.0 % 2-PyBH-3 4.0 % 4-PyBB-3 6.0 % 3-HEBEB-1 2.0 % 5-PyB(F)-F 4.0 % 3-HBB(F,F)-F 2.0 % T NI = 86.1°C T L < -30°C η 20 = 38.2 mPa·s Δn = 0.150 Δε = 10.8 V th = 1.49 V Example 7 5-HBB(F)B-2 10.0 % 5-HBB(F)B-3 5.0 % 2-HB(F)-C 15.0 % 2-HHB(F)-C 13.0 % 3-HHB(F)-C 13.0 % 3O1-HBE(F)-C 2.0 % 3-HB(F)EB(F)-C 2.0 % 2-BTB-01 4.0 % 3-BTB-01 4.0 % 4-BTB-01 4.0 % 4-BTB-02 4.0 % 5-BTB-01 4.0 % 2-HHB(F)-F 3.4 % 3-HHB(F)-F 3.3 % 5-HHB(F)-F 3.3 % 2-H2HB(F)-F 4.0 % 3-H2HB(F)-F 2.0 % 5-H2HB(F)-F 4.0 % T NI = 118.2°C T L < -30°C η 20 = 46.0 mPa·s Δn = 0.163 Δε = 11.5 V th = 1.59 V Example 8 1O1-HBB-4 5.0 % V2-HB-C 12.0 % 1V2-HB-C 11.0 % 1V2-BEB(F,F)-C 11.0 % 5-HBB-C 4.0 % 3-HBEB(F,F)-C 2.0 % 2-BTB-1 8.0 % 4-BTB-O2 8.0 % 5-BTB-O1 6.0 % 3-HH-4 6.0 % 3-HB(F)TB-2 5.0 % 3-HB(F)TB-3 6.0 % 3-HB(F)VB-3 6.0 % 101-HBBH-3 2.0 % 3-HB-CL 3.0 % 3-HHB-CL 5.0 % T NI = 86.4°C T L < -30°C η 20 = 25.1 mPa·s Δn = 0.184 Δε = 12.3 V th = 1.53 V Example 9 5-HBB(F)B-2 7.0 % 3-HB(F)-C 5.0 % 2O1-BEB(F)-C 5.0 % 3O1-BEB(F)-C 10.0 % V-HB-C 10.0 % 1V-HB-C 10.0 % 5-BBB-C 3.0 % 2-BTB-O1 5.0 % 3-HB-O2 5.0 % V2-HH-3 5.0 % V-HH-4 5.0 % V-HHB-1 10.0 % 1V2-HBB-2 10.0 % 3-HHB-1 10.0 % T NI = 84.1°C T L < -30°C η 20 = 23.6 mPa·s Δn = 0.144 Δε = 9.9 V th = 1.43 V According to the present invention, liquid crystal compositions which have a high optical anisotropy in particular, is excellent in miscibility at low temperatures, and have a wide range of a nematic phase while satisfying various properties required for TN-LCD or STN-LCD display modes, can be provided.

Claims: A liquid crystal composition comprising, as a first component, at least one compound expressed by the general formula (1-1) or (1-2) wherein R 1 and R 2 independently represent an alkyl group having 1 to 10 carbon atoms; and rings A, B, and C independently represent 1,4-phenylene provided that at least one of the rings A, B, and C represents 1,4-phenylene in which H at lateral position(s) are replaced by F, comprising, as a second component, at least one compound selected from the group consisting of the compounds expressed by the general formula (2-a), (2-b), (2-c), (2-d), or (2-e) wherein R 3 represents an alkyl group having 1 to 10 carbon atoms or an alkenyl group having 2 to 10 carbon atoms, any one or non-adjacent two or more methylene groups (-CH 2 -) in the alkyl or alkenyl group may be replaced by oxygen atom (-O-); Z 1 represents -COO-, -C 2 H 4 -, or single bond; Z 2 and Z 3 represent -C 2 H 4 - or single bond; Z 4 represents -COO-, -C 2 H 4 -, or single bond; D 1 represents trans-1,4-cyclohexylene, 1,4-phenylene, or 1,3-dioxane-trans-2,5-diyl; D 2 , D 3 , D 4 , D 6 , and D 7 independently represent trans-1,4-cyclohexylene or 1,4-phenylene; D 5 represents trans-1,4-cyclohexylene or 1,4-phenylene, one H at a lateral position of the 1,4-phenylene may be replaced by F; and q and m are independently 0 or 1, and comprising, as a third component, at least one compound selected from the group consisting of the compounds expressed by the general formula (3) R 4 -G 1 -Z 5 -G 2 -R 5 wherein R 4 and R 5 independently represent an alkyl group having 1 to 10 carbon atoms or an alkenyl group having 2 to 10 carbon atoms, any one or non-adjacent two or more methylene groups (-CH 2 -) in the alkyl or alkenyl group may be replaced by oxygen atom (-O-); G 1 represents trans-1,4-cyclohexylene, 1,4-phenylene, or pyrimidine-2,5-diyl; G 2 represents trans-1,4-cyclohexylene or 1,4-phenylene; and Z 5 represents -C≡C-, -CH=CH-, -C 2 H 4 -, -COO-, or single bond. The liquid crystal composition according to claim 1 wherein the amount of the first component is 3 to 30 %, that of the second component is 30 to 70 %, and that of the third component is 10 to 50 %, respectively, based on the total weight of liquid crystal composition. The liquid crystal composition according to claim 1 or 2 wherein the liquid crystal composition further comprises at least one compound selected from the group consisting of the compounds expressed by the general formula (4) or (5) R 6 ―J 1 ―Z 6 ―J 2 ―Z 7 ―J 3 ―R 7 wherein R 6 represents an alkyl group having 1 to 10 carbon atoms or an alkenyl group having 2 to 10 carbon atoms, any one or non-adjacent two or more methylene groups (-CH 2 -) in the alkyl or alkenyl group may be replaced by oxygen atom (-O-); R 7 represents an alkyl or alkoxy group having 1 to 10 carbon atoms, or alkoxymethyl group having 2 to 10 carbon atoms; J 1 represents trans-1,4-cyclohexylene, 1,4-phenylene, or pyrimidine-2,5-diyl group; J 2 represents trans-1,4-cyclohexylene or 1,4-phenylene, one H at a lateral position of the 1,4-phenylene may be replaced by F; J 3 represents trans-1,4-cyclohexylene, 1,4-phenylene, or pyrimidine-2,5-diyl; Z 6 represents -C 2 H 4 -, -COO-, or single bond; Z 7 represents -C≡C-, -COO-, -CH=CH-, or single bond; and Q 1 represent H or F. The liquid crystal composition according to any one of claims 1 to 3 wherein the liquid crystal composition further comprises at least one compound selected from the group consisting of the compounds expressed by the general formula (6) or (7) wherein R 8 represents an alkyl group having 1 to 10 carbon atoms; I represents trans-1,4-cyclohexylene or 1,4-phenylene; Q 2 , Q 3 , and Q 4 independently represent H or F; Z 8 and Z 9 independently represent -COO-, -C 2 H 4 -, or single bond; k is 0 or 1; n is 0, 1, or 2; and X represents F or Cl. A liquid crystal display device comprising a liquid crystal composition defined in any one of claims 1 to 4.

Inventors: HACHIIYA NORIHISA, MATSUSHITA TETSUYA, MURASHIRO KATSUYUKI, NAKAGAWA ETSUO, TAKESHITA FUSAYUKI, HACHIIYA, NORIHISA, MATSUSHITA, TETSUYA, MURASHIRO, KATSUYUKI, NAKAGAWA, ETSUO, TAKESHITA, FUSAYUKI
Applicants: CHISSO CORP, CHISSO CORPORATION
Application year: 1998
Main classification: C09K19
IPC codes: G02F1, C09K19