Nematic liquid crystal composition and liquid crystal display element using the same

Abstract

The present invention relates to a liquid crystal composition, which is a liquid crystal composition containing a compound represented by General Formula (II-1) as an anti-oxidizing agent for a liquid crystal composition containing the compound represented by General Formula (II-1) and also as a first component, and a compound represented by General Formula (K) as a second component. The compound represented by General Formula (II-1) enables obtainment of a working effect of the anti-oxidizing agent, and therefore it allows provision of a liquid crystal composition containing the anti-oxidizing agent which has improved reliability like low temperature stability, while the high dielectric anisotropy is maintained.

Claims

1. A liquid crystal composition which comprises: a compound represented by General Formula (II): ##STR00056## in General Formula (II), M represents an alkylene group having carbon atom number of 4 to 10; and, a compound represented by General Formula (K): ##STR00057## in General Formula (K), R.sup.k1's each independently represent an alkyl group having carbon atom number of 1 to 10 or an alkenyl group having carbon atom number of 2 to 10, in which one or two or more non-adjacent CH.sub.2 in the group may be each independently substituted with CC, O, CO, COO, or OCO, and one or two or more non-adjacent hydrogen atoms in the group may be each independently substituted with a fluorine atom, ring K.sup.1 and ring K.sup.2 each independently represent a 1,4-cyclohexylene group in which one or two or more non-adjacent CH.sub.2 in the group may be substituted with O or S or a 1,4-phenylene group in which one or two or more non-adjacent CH in the group may be substituted with N, and the hydrogen atoms in the group may be each independently substituted with a cyano group, a fluorine atom, or a chlorine atom, ring K.sup.0 represents a naphthalene-2,6-diyl group or a 1,4-phenylene group in which the hydrogen atoms in the group may be each independently substituted with a fluorine atom, Z.sup.k1 represents OCH.sub.2 or OCF.sub.2, Z.sup.k2, or Z.sup.k3 each independently represents a single bond, CH.sub.2CH.sub.2, (CH.sub.2).sub.4, OCH.sub.2, CH.sub.2O, OCF.sub.2, CF.sub.2O, CH.sub.2CH.sub.2CF.sub.2O, COO, OCO, or CC, n.sup.k1's each independently represent 0, 1, 2, 3, or 4, with the proviso that, when n.sup.k1 is 2 or more, the rings K.sup.2 may be the same as or different from each other, and X.sup.k1, X.sup.k2, X.sup.k3, and X.sup.k4 each independently represent a hydrogen atom or a fluorine atom, and Y.sup.k1's each independently represent a fluorine atom, a cyano group, a trifluoromethyl group, a fluoromethoxy group, a difluoromethoxy group, a trifluoromethoxy group, or a 2,2,2-trifluoroethyl group, wherein the liquid crystal composition has no drop mark in a drop mark evaluation of a liquid crystal display element prepared by the liquid crystal composition by visually evaluating a drop mark appearing white on a black screen of the liquid crystal display element.

2. The liquid crystal composition according to claim 1, wherein the compound represented by General Formula (II) is a compound represented by General Formula (II-a): ##STR00058##

3. The liquid crystal composition according to claim 1, further comprising a polymerizable compound.

4. A liquid crystal display element comprising a first substrate which is provided with a common electrode formed of a transparent conductive material, a second substrate which is provided with a pixel electrode formed of a transparent conductive material and a thin film transistor for controlling a pixel electrode disposed on each pixel, and a liquid crystal composition sandwiched between the first substrate and the second substrate, in which the alignment of liquid crystal molecules in the liquid crystal composition without voltage application is approximately parallel or approximately vertical to the substrate and the liquid crystal composition described in claim 1 is used as the liquid crystal composition of the element.

5. A liquid crystal display element, wherein the liquid crystal display element is produced by polymerization of a polymerizable compound contained in the liquid crystal composition of claim 1 with voltage application or without voltage application.

Description

BRIEF DESCRIPTION OF DRAWINGS

(1) FIG. 1 is a drawing illustrating schematically the constitution of a liquid crystal display element according to the present invention.

(2) FIG. 2 is an enlarged plane view of a region of an electrode layer II which contains a thin film transistor formed on the substrate of FIG. 1.

(3) FIG. 3 is a cross-sectional view of the liquid crystal display element shown in FIG. 1, the cross-sectional view being taken along line III-III in FIG. 2.

DESCRIPTION OF EMBODIMENTS

(4) The present invention relates to a liquid crystal composition which contains,

(5) ##STR00004##

(6) as a first component, an anti-oxidizing agent represented by General Formula (II-1) above, and

(7) ##STR00005##

(8) as a second component, a compound represented by General Formula (K) above.

(9) In General Formula (II-1), M.sup.y represents a hydrocarbon having carbon atom number of 1 to 25 (one or two or more CH.sub.2 in the hydrocarbon may be substituted with O, CO, COO, or OCO such that the oxygen atoms are not in direct contact with each other), a 1,4-phenylene group, or a trans-1,4-cyclohexylene group, in which any hydrogen atom of the 1,4-phenylene group may be substituted with a fluorine atom, X.sup.y's, which may be the same as or different from each other, represent an alkylene group having carbon atom number of 1 to 15 (one or two or more CH.sub.2 in the alkylene group may be substituted with O, CO, COO, or OCO such that the oxygen atoms are not in direct contact with each other), OCH.sub.2, CH.sub.2O, COO, OCO, CF.sub.2O, OCF.sub.2, CF.sub.2CF.sub.2, CHCHCOO, CHCHOCO, COOCHCH, OCOCHCH, CHCH, CC, a single bond, a 1,4-phenylene group, or a trans-1,4-cyclohexylene group in which any hydrogen atom of the 1,4-phenylene group may be substituted with a fluorine atom, and l represents an integer of 2 to 6).

(10) The compound represented by General Formula (II-1) according to the present invention allows obtainment of a working effect of an anti-oxidizing agent, and therefore it is possible to provide a liquid crystal composition which includes the anti-oxidizing agent and has improved reliability like low temperature stability while maintaining high dielectric anisotropy.

(11) In General Formula (II-1), it is preferable that M.sup.y is a hydrocarbon having carbon atom number of 1 to 10 (one or two or more CH.sub.2 in the hydrocarbon may be substituted with O, CO, COO, or OCO such that the oxygen atoms are not in direct contact with each other). Furthermore, it is preferable that X.sup.y is an alkylene group having carbon atom number of 2 to 10 (one or two or more CH.sub.2 in the alkylene group may be substituted with O, CO, COO, or OCO such that the oxygen atoms are not in direct contact with each other), a single bond, a 1,4-phenylene group, or a trans-1,4-cyclohexylene group. Furthermore, l groups of X.sup.y in General Formula (II-1) may be the same as or different from each other, but they are preferably the same as each other. l is preferably an integer of 2 to 4, and more preferably 2.

(12) The compound represented by General Formula (II-1) according to the present invention is preferably a compound represented by the following General Formula (II-2).

(13) ##STR00006##

(14) In the above General Formula (II-2), M.sup.x represents a hydrocarbon having carbon atom number of 1 to 25 (one or two or more CH.sub.2 in the hydrocarbon may be substituted with O, CO, COO, or OCO such that the oxygen atoms are not in direct contact with each other), but it is preferably a hydrocarbon having carbon atom number of 2 to 15 (one or two or more CH.sub.2 in the hydrocarbon may be substituted with O, CO, COO, or OCO such that the oxygen atoms are not in direct contact with each other).

(15) In the above General Formula (II-2), X's each independently represent an alkylene group having carbon atom number of 1 to 15 (one or two or more CH.sub.2 in the alkylene group may be substituted with O, CO, COO, or OCO such that the oxygen atoms are not in direct contact with each other), OCH.sub.2, CH.sub.2O, COO, OCO, CF.sub.2O, OCF.sub.2, CF.sub.2CF.sub.2, CHCHCOO, CHCHOCO, COOCHCH, OCOCHCH, CHCH, CC, a single bond, a 1,4-phenylene group (any hydrogen atom of the 1,4-phenylene group may be substituted with a fluorine atom), or a trans-1,4-cyclohexylene group. However, they are preferably an alkylene group having carbon atom number of 2 to 15 (one or two or more CH.sub.2 in the alkylene group may be substituted with O, CO, COO, or OCO such that the oxygen atoms are not in direct contact with each other), a single bond, a 1,4-phenylene group, or a trans-1,4-cyclohexylene group. Furthermore, four X's in the above General Formula (II-2) may be the same as or different from each other, but they are preferably the same as each other.

(16) In the above General Formula (II-2), a, b, c, and d each independently represent 0 or 1, but a+b+c+d represents 2 or higher. a+b+c+d is more preferably 2 to 4, and more preferably 2.

(17) The anti-oxidizing agent represented by General Formula (II-1) according to the present invention is preferably a hindered phenol derivative which is represented by the following General Formula (II).

(18) ##STR00007##

(19) In General Formula (II), M represents an alkylene group having carbon atom number of 1 to 15 (one or two more CH.sub.2 in the alkylene group may be substituted with O, CO, COO, or OCO such that the oxygen atoms are not in direct contact with each other), OCH.sub.2, CH.sub.2O, COO, OCO, CF.sub.2O, OCF.sub.2, CF.sub.2CF.sub.2, CHCHCOO, CHCHOCO, COOCHCH, OCOCHCH, CHCH, CC, a single bond, 1,4-phenylene group (any hydrogen atom of the 1,4-phenylene group may be substituted with a fluorine atom), or a trans-1,4-cyclohexylene group. However, it is preferably an alkylene group having carbon atom number of 1 to 14. Considering the volatility, a higher carbon atom number is preferred. However, because it is also preferred not to have an excessively high carbon atom number when the viscosity is considered, with regard to M in General Formula (II) according to the present invention, the carbon atom number of 2 to 12 is more preferable, the carbon atom number of 3 to 10 is more preferable, the carbon atom number of 4 to 10 is more preferable, the carbon atom number of 5 to 10 is more preferable, and the carbon atom number of 6 to 10 is more preferable.

(20) The anti-oxidizing agent according to the present invention is particularly preferably compound which is represented by the following Formula (II-a6), Formula (II-a7), Formula (II-a8), Formula (II-a9), or Formula (II-a10).

(21) ##STR00008##

(22) The anti-oxidizing agent according to the present invention preferably coexists with a liquid crystal compound, and it more preferably coexists with a nematic liquid crystal compound (or a nematic liquid crystal composition). In that case, it is preferable that one or more kinds of the anti-oxidizing agent are contained in the liquid crystal composition. The content is preferably 0.001 to 1% by mass, more preferably 0.001 to 0.5% by mass, and particularly preferably 0.01 to 0.3% by mass.

(23) The liquid crystal composition according to the present invention preferably contains one or two or more liquid crystal compound having positive dielectric anisotropy with an absolute value of 4 or higher. The content of the liquid crystal compound is preferably 3% by mass or more but 5% by mass or more, more preferably 10% by mass or more, and particularly preferably 20% by mass or more. More specifically, it is preferably 3% by mass to 70% by mass, more preferably 5% by mass to 60% by mass, even more preferably 10% by mass to 60% by mass, and particularly preferably 20% by mass to 60% by mass. Furthermore, the dielectric anisotropy of the liquid crystal compound indicates a value at 20 C.

(24) As described herein, the liquid crystal composition indicates a composition which contains a liquid crystal compound having positive dielectric anisotropy with an absolute value of 4 or higher, and the anti-oxidizing agent according to the present invention.

(25) The liquid crystal composition containing the compound, which is represented by General Formula (K) and is contained in the liquid crystal composition according to the present invention, and the anti-oxidizing agent is preferable in that it can maintain high dielectric anisotropy () and has excellent reliability.

(26) Thus, it is preferable that the compound represented by General Formula (K) has positive dielectric anisotropy with an absolute value of 4 or higher and the content of the compound in the liquid crystal composition according to the present invention is 3% by mass or more. The content of the compound represented by General Formula (K) in the liquid crystal composition according to the present invention is preferably 1% by mass or more, more preferably, 3% by mass or more, even more preferably 5% by mass or more, and still even more preferably 10% by mass or more. More specifically, it is preferably 3% by mass to 70% by mass, more preferably 5% by mass to 60% by mass, even more preferably 10% by mass to 60% by mass, and still even more preferably 10% by mass to 50% by mass.

(27) One or two or more kinds of the compound represented by General Formula (K) for addition are contained in the liquid crystal composition according to the present invention. Preferably, 1 to 10 kinds of the compound are contained. More preferably 1 to 8 kinds of the compound are contained. Even more preferably 2 to 8 kinds of the compound are contained. Particularly preferably, 2 to 5 kinds of the compound are contained.

(28) In General Formula (K) according to the present invention, R.sup.k1's each independently represent an alkyl group with carbon atom number of 1 to 10 or an alkenyl group with carbon atom number of 2 to 10. However, they are preferably an alkyl group with carbon atom number of 1 to 8 or an alkenyl group with carbon atom number of 2 to 8. More preferably, they are an alkyl group with carbon atom number of 1 to 5 or an alkenyl group with carbon atom number of 2 to 5. Furthermore, one or two or more non-adjacent CH.sub.2 in the group may be each independently substituted with CC, O, CO, COO, or OCO, and one or two or more hydrogen atoms in the group may be each independently substituted with a fluorine atom.

(29) With regard to General Formula (K) according to the present invention, it is preferable that the ring K.sup.1 and ring K.sup.2 are each independently at least one group selected from a group consisting of a 1,4-cyclohexylene group (one or two or more non-adjacent CH.sub.2 in the group may be substituted with O or S), a tetrahydropyran-2,5-diyl group, or a 1,4-phenylene group (one or two or more non-adjacent CH in the group may be substituted with N), a 3-fluoro-1,4-phenylene group, a 3,5-difluoro-1,4-phenylene group, and a dioxane group. More preferably, they are a 1,4-cyclohexylene group or a 1,4-phenylene group, and the hydrogen atoms in the group may be each independently substituted with a cyano group, a fluorine atom, or a chlorine atom.

(30) The ring K.sup.0 represents a naphthalene-2,6-diyl group or a 1,4-phenylene group in which the hydrogen atoms in the group may be each independently substituted with a fluorine atom,

(31) With regard to General Formula (K) according to the present invention, Z.sup.k1, Z.sup.k2, and Z.sup.k3 each independently represent a single bond, CH.sub.2CH.sub.2, (CH.sub.2).sub.4, OCH.sub.2, CH.sub.2O, OCF.sub.2, CF.sub.2O, CH.sub.2CH.sub.2CF.sub.2O, COO, OCO, or CC, but they are preferably a single bond, CH.sub.2CH.sub.2, OCH.sub.2, CH.sub.2O, OCF.sub.2, or CF.sub.2O, and more preferably a single bond, OCH.sub.2, or OCF.sub.2. When explained in greater detail, Z.sup.k1 is preferably OCH.sub.2 or OCF.sub.2, and more preferably OCH.sub.2. Z.sup.k2 and Z.sup.k3 are preferably a single bond, OCH.sub.2, CH.sub.2O, OCF.sub.2 or CF.sub.2O, and more preferably a single bond.

(32) With regard to General Formula (K) according to the present invention, n.sup.k1 represents 0, 1, 2, or 3. It is more preferably 0, 1, or 2. It is more preferably 0 or 1. Furthermore, when n.sup.k1 is 2 or more, the rings K.sup.2 may be the same as or different from each other and Z.sup.k3's may be the same as or different from each other.

(33) With regard to General Formula (K) according to the present invention, X.sup.k1, X.sup.k2, X.sup.k3, and X.sup.k4 each independently represent a hydrogen atom, a chlorine atom, or a fluorine atom, and they are more preferably a hydrogen atom or a fluorine atom.

(34) With regard to General Formula (K) according to the present invention, Y.sup.k1's each independently represent a chlorine atom, a fluorine atom, a cyano group, a trifuloromethyl group, a fluoromethoxy group, a difluoromethoxy group, a trifluoromethoxy group, or a 2,2,2-trifluoroethyl group. They are preferably a fluorine atom, a trifuloromethyl group, a fluoromethoxy group, a difluoromethoxy group, or a trifluoromethoxy, and more preferably a fluorine atom, a trifluoromethoxy group, or a trifuloromethyl group.

(35) The compound represented by General Formula (K) according to the present invention is preferably at least one selected from a group consisting of the compounds that are represented by the following General Formula (K1) and General Formula (K2).

(36) ##STR00009##
(in the above General Formula (K1), R.sup.k1, ring K.sup.1, ring K.sup.2, n.sup.k1, X.sup.k1, X.sup.k2, X.sup.k3, X.sup.k4 Y.sup.k1Z.sup.k1, Z.sup.k2, and Z.sup.k3 are as defined in the above for General Formula (K), and thus further explanations are omitted herein)

(37) ##STR00010##
(in the above General Formula (K2), R.sup.k1, ring K.sup.1, ring K.sup.2, n.sup.k1, X.sup.k1, X.sup.k2, X.sup.k3, X.sup.k4, Y.sup.k1Z.sup.k1, Z.sup.k2 and Z.sup.k3 are as defined in the above for General Formula (K), and thus further explanations are omitted herein). The content of the compound represented by General Formula (K1) in the liquid crystal composition according to the present invention is preferably 1% by mass or more, more preferably, 3% by mass or more, even more preferably 5% by mass or more, and still even more preferably 10% by mass or more. More specifically, it is preferably 3% by mass to 70% by mass, more preferably 5% by mass to 60% by mass, even more preferably 10% by mass to 60% by mass, and still even more preferably 10% by mass to 50% by mass.

(38) The content of the compound represented by General Formula (K2) in the liquid crystal composition according to the present invention is preferably 1% by mass or more, more preferably, 3% by mass or more, even more preferably 5% by mass or more, and still even more preferably 10% by mass or more. More specifically, it is preferably 3% by mass to 70% by mass, more preferably 5% by mass to 60% by mass, even more preferably 10% by mass to 60% by mass, and still even more preferably 10% by mass to 50% by mass.

(39) It is preferable that, in the liquid crystal composition according to the present invention, at least one selected from a group consisting of the compound represent by General Formula (K1) and the compound represent by General Formula (K2) is contained.

(40) It is preferable that, in the liquid crystal composition according to the present invention, at least one compound represented by General Formula (K1) is contained, and more preferably 2 to 5 kinds of the compound are contained.

(41) It is preferable that, in the liquid crystal composition according to the present invention, at least one compound represented by General Formula (K2) is contained, and more preferably 2 to 5 kinds of the compound are contained.

(42) It is also preferable that, in the liquid crystal composition according to the present invention, at least one compound represented by General Formula (K1) is contained and also at least one compound represented by General Formula (K2) is contained.

(43) It is preferable that, in the liquid crystal composition according to the present invention, one or two or more kinds of the compound represented by General Formula (K1) and the compound represented by General Formula (K2) are contained in total. Preferably, 1 to 10 kinds of the compounds are contained. More preferably, 1 to 8 kinds of the compounds are contained. Even more preferably, 2 to 8 kinds of the compounds are contained. Particularly preferably, 2 to 5 kinds of the compounds are contained.

(44) The compound represented by General Formula (K) according to the present invention is preferably a compound selected from a compound group which is represented by the following General Formulae (K11) to (K28). More preferably, it is a compound selected from a compound group which is represented by General Formulae (K11) to (K17) and General Formulae (K25) to (K28). Particularly preferably, it is a compound selected from a compound group which is represented by General Formulae (K11) to (K17).

(45) ##STR00011## ##STR00012## ##STR00013##

(46) In the above General Formulae (K11) to (K28), R.sup.k1, X.sup.k1, X.sup.k2, Z.sup.k2, ring K.sup.2, Z.sup.k3, n.sup.k1, X.sup.k3, X.sup.k4 and Y.sup.k1 are as defined above. However, X.sup.k1 and X.sup.k2 are particularly preferably a fluorine atom, Z.sup.k2 and Z.sup.k3 are particularly preferably a single bond. The ring K.sup.2 is preferably a 1,4-phenylene group, a 3-fluoro-1,4-phenylene group, or a 3,5-difluoro-1,4-phenylene group and particularly preferably a 3,5-difluoro-1,4-phenylene group. n.sup.k1 is preferably 0 or 1, and particularly preferably 1. X.sup.k3 and X.sup.k4 are particularly preferably a fluorine atom, and Y.sup.k1 is preferably a fluorine atom or a trifluoromethoxy group and particularly preferably a fluorine atom.

(47) The content of the compound represented by General Formulae (K11) to (K17) in the liquid crystal composition according to the present invention is preferably 1% by mass or more, more preferably, 3% by mass or more, even more preferably 5% by mass or more, and still even more preferably 10% by mass or more. More specifically, it is preferably 3% by mass to 70% by mass, more preferably 5% by mass to 60% by mass, even more preferably 10% by mass to 60% by mass, and still even more preferably 10% by mass to 50% by mass.

(48) The content of the compound represented by General Formulae (K25) to (K28) in the liquid crystal composition according to the present invention is preferably 1% by mass or more, more preferably, 3% by mass or more, even more preferably 5% by mass or more, and still even more preferably 10% by mass or more. More specifically, it is preferably 3% by mass to 70% by mass, more preferably 5% by mass to 60% by mass, even more preferably 10% by mass to 60% by mass, and still even more preferably 10% by mass to 50% by mass.

(49) It is preferable that, in the liquid crystal composition according to the present invention, one or two or more kinds of the compound represented by General Formulae (K11) to (K17) are contained. Preferably, 1 to 10 kinds of the compound are contained. More preferably, 1 to 8 kinds of the compound are contained. Even more preferably, 2 to 8 kinds of the compound are contained. Particularly preferably, 2 to 5 kinds of the compounds are contained.

(50) It is preferable that, in the liquid crystal composition according to the present invention, one or two or more kinds of the compound represented by General Formulae (K25) to (K28) are contained. Preferably, 1 to 10 kinds of the compound are contained. More preferably, 1 to 8 kinds of the compound are contained. Even more preferably, 2 to 8 kinds of the compound are contained. Particularly preferably, 2 to 5 kinds of the compounds are contained.

(51) The liquid crystal composition according to the present invention may contain, as a liquid crystal compound having positive dielectric anisotropy with an absolute value of 4 or higher, a compound represented by General Formula (N).

(52) ##STR00014##

(53) In the above General Formula (N1), R.sup.n1 represents an alkyl group with carbon atom number of 1 to 10, or an alkenyl group with carbon atom number of 2 to 10, in which one or two or more non-adjacent CH.sub.2 in the group may be each independently substituted with CC, O, CO, COO, or OCO, and one or two or more hydrogen atoms in the group may be each independently substituted with a fluorine atom.

(54) In the above General Formula (N1), the ring N.sup.1 represents a 1,4-cyclohexylene group (one or two or more non-adjacent CH.sub.2 in the group may be substituted with O or S) or a 1,4-phenylene group (one or two or more non-adjacent CH in the group may be substituted with N), and the hydrogen atoms in the group may be each independently substituted with a cyano group or a fluorine atom.

(55) In the above General Formula (N1), Z.sup.n1 and Z.sup.n2 each independently represent a single bond, CH.sub.2CH.sub.2, (CH.sub.2).sub.4, OCH.sub.2, CH.sub.2O, OCF.sub.2, CF.sub.2O, CH.sub.2CH.sub.2CF.sub.2O, COO, OCO, or CC.

(56) In the above General Formula (N1), n.sup.n1 's each independently represent an integer of 0 to 4, with the proviso that, when n.sup.n1 is 2 or more, the rings N.sup.1 may be the same as or different from each other and Z.sup.n1 's may be the same as or different from each other.

(57) In the above General Formula (N1), X.sup.n1, X.sup.n2, X.sup.n3, X.sup.n4, and X.sup.n5 each independently represent a hydrogen atom or a fluorine atom,

(58) In the above General Formula (N1), Y.sup.n1 represents a fluorine atom, a cyano group, a trifuloromethyl group, a fluoromethoxy group, a difluoromethoxy group, a trifluoromethoxy group, or a 2,2,2-trifluoroethyl group, or a fluorine atom, a trifuloromethyl group, a fluoromethoxy group, a difluoromethoxy group, or a trifluoromethoxy group.

(59) The liquid crystal composition according to the present invention also containing the compound represented by General Formula (N) is preferable in that it can maintain high dielectric anisotropy (n) and has excellent reliability.

(60) The content of the compound represented by General Formula (N) in the liquid crystal composition according to the present invention is preferably 0 to 60% by mass, more preferably 1 to 50% by mass, more preferably 1 to 40% by mass, more preferably 5 to 40% by mass, and particularly preferably 10 to 40% by mass.

(61) One or two or more kinds of the compound represented by General Formula (N) are contained in the liquid crystal composition according to the present invention. Preferably, 1 to 10 kinds of the compound are contained. More preferably 1 to 8 kinds of the compound are contained. Even more preferably 2 to 8 kinds of the compound are contained. Particularly preferably, 2 to 5 kinds of the compound are contained.

(62) The compound represented by General Formula (N) according to the present invention is preferably a compound selected from a group consisting of the compounds that are represented by the following General Formula (N1) and General Formula (N2), and it is more preferably a compound represented by General Formula (N2).

(63) ##STR00015##

(64) In the above General Formula (N1) and General Formula (N2), R.sup.n1, ring N.sup.1, Z.sup.n1, n.sup.n1, X.sup.n1, X.sup.n2, X.sup.n4, X.sup.n5 and Y.sup.n1 are as defined above. However, the ring N.sup.1 is preferably a 1,4-cyclohexylene group, a tetrahydropyran-2,5-diyl group, a 1,4-phenylene group, a 3-fluoro-1,4-phenylene group, a 3,5-difluoro-1,4-phenylene group, or a dioxane group. It is more preferably a 1,4-phenylene group, a 3-fluoro-1,4-phenylene group, or a 3,5-difluoro-1,4-phenylene group. Z.sup.n1 is particularly preferably a single bond, and n.sup.n1 is preferably 0 or 1. X.sup.n1 and X.sup.n2 are preferably a hydrogen atom or a fluorine atom. More preferably, at least one of them is a fluorine atom. Particularly preferably, both of them are a fluorine atom. X.sup.n4 and X.sup.n5 are preferably a hydrogen atom or a fluorine atom. More preferably, at least one of them is a fluorine atom. Particularly preferably, both of them are a fluorine atom. Y.sup.n1 is preferably a fluorine atom or a trifluoromethoxy group.

(65) The content of the compound represented by General Formula (N1) in the liquid crystal composition according to the present invention is preferably 0 to 60% by mass, more preferably 1 to 50% by mass, more preferably 1 to 40% by mass, more preferably 5 to 40% by mass, and particularly preferably 10 to 40% by mass.

(66) The content of the compound represented by General Formula (N2) in the liquid crystal composition according to the present invention is preferably 0 to 60% by mass, more preferably 1 to 50% by mass, more preferably 1 to 40% by mass, more preferably 5 to 40% by mass, and particularly preferably 10 to 40% by mass.

(67) The compound represented by General Formula (N) according to the present invention is also preferably a compound represented by the following General Formula (N3).

(68) ##STR00016##

(69) In the above General Formula (N3), R.sup.n1, ring N.sup.1, X.sup.n1, X.sup.n2, X.sup.n4, X.sup.n5 and Y.sup.n1 are as defined above. In the above General Formula (N3), X.sup.1 and X.sup.2 each independently represent a hydrogen atom or a fluorine atom. Preferably, at least one of them is a fluorine atom. Also preferably, both of them are a fluorine atom. In the above General Formula (N3), the ring N.sup.1 represents a 1,4-cyclohexylene group, a tetrahydropyran-2,5-diyl group, a 1,4-phenylene group, a 3-fluoro-1,4-phenylene group, a 3,5-difluoro-1,4-phenylene group, or a dioxane group. It is more preferably a 1,4-phenylene group, a 3-fluoro-1,4-phenylene group, or a 3,5-difluoro-1,4-phenylene group. In the above General Formula (N3), n represents an integer of 0 to 2. It is preferably 0 or 1.

(70) The content of the compound represented by General Formula (N3) in the liquid crystal composition according to the present invention is preferably 0 to 60% by mass, more preferably 1 to 50% by mass, more preferably 1 to 40% by mass, more preferably 5 to 40% by mass, and particularly preferably 10 to 40% by mass.

(71) One or two or more kinds of the compound represented by General Formula (N3) are contained in the liquid crystal composition according to the present invention. Preferably, 1 to 10 kinds of the compound are contained. More preferably 1 to 8 kinds of the compound are contained. Even more preferably 2 to 8 kinds of the compound are contained. Particularly preferably, 2 to 5 kinds of the compound are contained.

(72) The compound represented by the following General Formula (N3) according to the present invention is preferably those of following (N11) to (N14).

(73) ##STR00017##

(74) The content of the compound represented by General Formulae (N11) to (N14) in the liquid crystal composition according to the present invention is preferably 0 to 60% by mass, more preferably 1 to 50% by mass, more preferably 1 to 40% by mass, more preferably 5 to 40% by mass, and particularly preferably 10 to 40% by mass.

(75) As for the liquid crystal compound having positive dielectric anisotropy with an absolute value of 4 or higher which is to be contained in the liquid crystal composition of the present invention, a compound of General Formula (Pa) is also preferable.

(76) ##STR00018##

(77) In the above General Formula (Pa), R.sup.Nc1 represents an alkyl group with carbon atom number of 1 to 8, or an alkenyl group with carbon atom number of 2 to 8, in which one or two or more non-adjacent CH.sub.2 in the group may be each independently substituted with CC, O, CO, COO, or OCO. However, it is preferably an alkyl group with carbon atom number of 1 to 5 or an alkenyl group with carbon atom number of 2 to 5.

(78) In the above General Formula (Pa), the ring P.sup.1, P.sup.2 and P.sup.3 each independently represent a 1,4-cyclohexylene group (one or two or more non-adjacent CH.sub.2 in the group may be substituted with O or S) or a 1,4-phenylene group (one or two or more non-adjacent CH in the group may be substituted with N), and the hydrogen atoms in the group may be each independently substituted with a cyano group, a fluorine atom, or a chlorine atom. However, they are preferably a 1,4-cyclohexylene group, a tetrahydropyran-2,5-diyl group, a 1,4-phenylene group, a 3-fluoro-1,4-phenylene group, or a 3,5-difluoro-1,4-phenylene group.

(79) In the above General Formula (Pa), Z.sup.Nc1, Z.sup.Nc2 or Z.sup.Nc3 each independently represents a single bond, CH.sub.2CH.sub.2, (CH.sub.2).sub.4, OCH.sub.2, CH.sub.2O, OCF.sub.2, CF.sub.2O, COO, OCO, or CC. However, it is more preferably a single bond, CH.sub.2CH.sub.2, CH.sub.2O, or CF.sub.2O. More preferably, any one of Z.sup.Nc1, Z.sup.Nc2 and Z.sup.Nc3 that are present is a single bond. It is also preferable that all of them are a single bond.

(80) In the above General Formula (Pa), n.sup.c1, n.sup.c2 or n.sup.c3 each independently represents 0, 1, or 2. n.sup.c1+n.sup.c2+n.sup.C3 represents 1 to 5. However, it is more preferably 4 or less, and particularly preferably 3 or less.

(81) In the above General Formula (Pa), X.sup.Nc1 and X.sup.Nc2 each independently represent a hydrogen atom or a fluorine atom.

(82) In the above group of General Formula (Pa), Y.sup.Nc1 represents a fluorine atom, a chlorine atom, a cyano group, a trifluoromethyl group, a fluoromethoxy group, a difluoromethoxy group, a trifluoromethoxy group, or a 2,2,2-trifluoroethyl group. However, it is preferably a fluorine atom, a trifuloromethyl group, a fluoromethoxy group, a difluoromethoxy group, or a trifluoromethoxy group. It is more preferably a fluorine atom, a trifuloromethyl group, or a trifluoromethoxy group.

(83) The content of the compound represented by General Formula (Pa) in the liquid crystal composition according to the present invention is preferably 0 to 60% by mass, more preferably 1 to 50% by mass, more preferably 1 to 40% by mass, more preferably 5 to 40% by mass, and particularly preferably 10 to 40% by mass.

(84) One or two or more kinds of the compound represented by General Formula (Pa) are contained in the liquid crystal composition according to the present invention. Preferably, 1 to 10 kinds of the compound are contained. More preferably 1 to 8 kinds of the compound are contained. Even more preferably 2 to 8 kinds of the compound are contained. Particularly preferably, 2 to 5 kinds of the compound are contained.

(85) The compound represented by the General Formula (Pa) according to the present invention is preferably a compound selected from a compound group represented by General Formulae (P01) to (P80).

(86) ##STR00019## ##STR00020## ##STR00021## ##STR00022## ##STR00023## ##STR00024## ##STR00025## ##STR00026## ##STR00027## ##STR00028##

(87) In the above General Formulae (P1) to (P80), R.sup.Nc1 represents an alkyl group with carbon atom number of 1 to 8, or an alkenyl group with carbon atom number of 2 to 8, in which one or two or more non-adjacent CH.sub.2 in the group may be each independently substituted with CC, O, CO, COO, or OCO. However, it is preferably an alkyl group with carbon atom number of 1 to 5 or an alkenyl group with carbon atom number of 2 to 5.

(88) In the above General Formulae (P1) to (P80), Y.sup.Nc2 represents a hydrogen atom, a fluorine atom, a chlorine atom, a cyano group, a trifuloromethyl group, a fluoromethoxy group, a difluoromethoxy group, a trifluoromethoxy group, or a 2,2,2-trifluoroethyl group. However, it is preferably a fluorine atom, a trifuloromethyl group, a fluoromethoxy group, a difluoromethoxy group, or a trifluoromethoxy group. It is more preferably a fluorine atom, a trifuloromethyl group, or a trifluoromethoxy group.

(89) As for the compound represented by General Formula (Pa) according to the present invention, the following compounds can be further exemplified.

(90) ##STR00029## ##STR00030## ##STR00031## ##STR00032##

(91) The liquid crystal composition according to the present invention may contain, as a third component, a compound having dielectric anisotropy () of 1 to +1 (preferably, dielectric anisotropy () of 0.5 to +0.5), in addition to the anti-oxidizing agent or the liquid crystal compound having positive dielectric anisotropy with an absolute value of 4 or higher,

(92) As the third component, there is a compound represented by the following General Formula (L).

(93) ##STR00033##

(94) In the above General Formula (L), R.sup.L1 and R.sup.L2 each independently represent an alkyl group with carbon atom number of 1 to 10, or an alkenyl group with carbon atom number of 2 to 10, in which one or two or more non-adjacent CH.sub.2 in the group may be each independently substituted with CHCH, CC, O, CO, COO, or OCO.

(95) In the above General Formula (L), OL represents 0, 1, 2 or 3, but it is preferably 0, 1 or 2.

(96) In the above General Formula (L), B.sup.L1, B.sup.L2 and B.sup.L3 each independently represent a 1,4-cyclohexylene group (one or two or more non-adjacent CH.sub.2 in the group may be substituted with O or S) or a 1,4-phenylene group (one or two or more non-adjacent CH in the group may be substituted with N and one or two or more hydrogen atoms in the group may be substituted with a cyano group, a fluorine atom, or a chlorine atom).

(97) In the above General Formula (L), L.sup.L1 and L.sup.L2 each independently represent a single bond, CH.sub.2CH.sub.2, (CH.sub.2).sub.4, OCH.sub.2, CH.sub.2O, COO, OCO, OCF.sub.2, CF.sub.2O, CHNNCH, CHCH, CFCF, or CC.

(98) When OL is 2 or 3 and there more than one L.sup.L2, they may be the same as or different from each other. When OL is 2 or 3 and there more than one B.sup.L3, they may be the same as or different from each other. The liquid crystal composition according to the present invention preferably contains one or two or more kinds of the compound represented by General Formula (L). It more preferably contains 1 to 20 kinds of the compound. It even more preferably contains 2 to 10 kinds of the compound.

(99) The compound represented by the above General Formula (L) is preferably a compound selected from a compound group represented by General Formula (III-A) to General Formula (III-J).

(100) ##STR00034##

(101) In the above General Formulae (III-A) to (III-J), R.sup.5 is preferably an alkyl group with carbon atom number of 1 to 10 or an alkenyl group with carbon atom number of 2 to 10, and more preferably an alkyl group with carbon atom number of 1 to 5 or an alkenyl group with carbon atom number of 2 to 5. R.sup.6 is preferably an alkyl group with carbon atom number of 1 to 10, an alkoxyl group with carbon atom number of 1 to 10, an alkenyl group with carbon atom number of 2 to 10, or an alkenyloxy group with carbon atom number of 2 to 10. It is more preferably an alkyl group with carbon atom number of 1 to 5, an alkoxyl group with carbon atom number of 1 to 5, an alkenyl group with carbon atom number of 2 to 5, or an alkenyloxy group with carbon atom number of 2 to 5.

(102) The third component in the liquid crystal composition according to the present invention is more preferably a compound selected from General Formula (III-A), General Formula (III-D), General Formula (III-F), General Formula (III-G), and General Formula (III-H). It is particularly preferably a compound selected from General Formula (III-A), General Formula (III-F), General Formula (III-G), and General Formula (III-H).

(103) Furthermore, with regard to the compound represented by General Formula (III-D), General Formula (III-G), and General Formula (III-H), R.sup.5 is preferably an alkyl group with carbon atom number of 1 to 5 or an alkenyl group with carbon atom number of 2 to 5 and R.sup.6 is preferably an alkyl group with carbon atom number of 1 to 5 or an alkoxy group with carbon atom number of 1 to 5. With regard to the compound represented by General Formula (III-F), it is preferable that R.sup.5 and R.sup.6 are each independently an alkyl group with carbon atom number of 1 to 5 or an alkenyl group with carbon atom number of 2 to 5.

(104) The content of the compound represented by General Formula (L) as the third component is preferably 0 to 80% by mass, more preferably 1 to 60% by mass, even more preferably 3 to 60% by mass, and still even more preferably 10 to 60% by mass.

(105) As a compound represented by the above General Formula (L), one or two or more kinds of the compound represented by General Formulae (VIII-c) to General Formula (VIII-e) may be contained.

(106) ##STR00035##

(107) In the formula, R.sup.51 and R.sup.52 are each independently an alkyl group with carbon atom number of 1 to 5, an alkoxyl group with carbon atom number of 1 to 5, an alkenyl group with carbon atom number of 2 to 5, or an alkenyloxy group with carbon atom number of 2 to 5. X.sup.51 and X.sup.52 are each independently a fluorine atom, a chlorine atom, or a hydrogen atom.

(108) More specific examples thereof include a compound of Formula (V-6.1).

(109) ##STR00036##

(110) As a compound represented by the above General Formula (L), one or two or more kinds of the compound represented by General Formula (V-9.1) to General Formula (V-9.3) may be contained.

(111) ##STR00037##

(112) In the liquid crystal composition of the present invention, in order to manufacture a liquid crystal display element of a PS type, a horizontal electric field type PSA type, or a horizontal electric field type PSVA type, a polymerizable compound can be contained. As the polymerizable compound capable of being used, a photopolymerizable monomer which is polymerized by energy rays such as light and has a liquid crystal skeleton in which a plurality of six-membered rings is connected, for example, biphenyl derivatives and terphenyl derivatives, can be exemplified.

(113) For example, it is preferable to contain a polymerizable compound like biphenyl derivatives and terphenyl derivatives in an amount of 0.01 to 2% by mass.

(114) ##STR00038##

(115) In greater detail, one or two or more kinds of a polymerizable compound represented by the above General Formula (M) are contained in the liquid crystal composition of the present invention.

(116) In General Formula (M), X.sup.201 and X.sup.202 each independently represent a hydrogen atom, a methyl group, or a CF.sub.3 group. The diacrylate derivatives in which both X.sup.201 and X.sup.202 represent hydrogen atoms and dimethacrylate derivatives in which both X.sup.201 and X.sup.202 represent methyl groups are preferable, and compounds in which one of them represents a hydrogen atom, and the other represents a methyl group are also preferable. Although a compound preferred for specific application may be used, in a PSA display element, the polymerizable compound represented by General Formula (M) preferably has at least one dimethacrylate derivative. It is also preferable to have two dimethacrylate derivatives.

(117) Sp.sup.201 and Sp.sup.202 each independently represent a single bond, an alkylene group with carbon atom number of 1 to 8, or a O(CH.sub.2).sub.s (in the formula, s is an integer of 2 to 7 and the oxygen atom is bound to a ring). In a liquid crystal display element of PSA type, at least one of Sp.sup.201 and Sp.sup.202 is preferably a single bond. It is also preferable to have a compound in which all of them are a single bond or one of them is a single bond and the other is an alkylene group with carbon atom number of 1 to 8, or a O (CH.sub.2).sub.s, and in such case, it is preferably an alkylene group with carbon atom number of 1 to 4 and s is preferably 1 to 4.

(118) The ring M.sup.201, ring M.sup.202 and ring M.sup.203 each independently represent a trans-1,4-cyclohexylene group (one or two or more non-adjacent CH.sub.2 in the group may be substituted with O or S), a 1,4-phenylene group (one or two or more non-adjacent CH in the group may be substituted with N), a 1,4-cyclohexylene group, a 1,4-bicyclo[2,2,2]octylene group, a piperidine-1,4-diyl group, a naphthalene-2,6-diyl group, a decahydronaphthalene-2,6-diyl group, or a 1,2,3,4-tetrahydronaphtalene-2,6-diyl group, in which the hydrogen atoms in the group may be each independently substituted with a fluorine atom, a CF.sub.3 group, an alkyl group with carbon atom number of 1 to 10, an alkoxyl group with carbon atom number of 1 to 10, or any one of Formula (R-1) to Formula (R-15).

(119) ##STR00039## ##STR00040##

(120) Z.sup.201 and Z.sup.202 each independently represent OCH.sub.2, CH.sub.2O, COO, OCO, CF.sub.2O, OCF.sub.2, CH.sub.2CH.sub.2, CF.sub.2CF.sub.2, CHCHCOO, CHCHOCO, COOCHCH, OCOCHCH, COOCH.sub.2CH.sub.2, OCOCH.sub.2CH.sub.2, CH.sub.2CH.sub.2COO, CH.sub.2CH.sub.2OCO, COOCH.sub.2, OCOCH.sub.2, CH.sub.2COO, CH.sub.2OCO, CY.sup.1CY.sup.2 (in the formula, Y.sup.1 and Y.sup.2 each independently represent a fluorine atom or a hydrogen atom), CC, or a single bond. However, they are more preferably COO, OCO, CHCHCOO, CHCHOCO, COOCHCH, OCOCHCH, COOCH.sub.2CH.sub.2, OCOCH.sub.2CH.sub.2, CH.sub.2CH.sub.2COO, CH.sub.2CH.sub.2OCO, CC, or a single bond. They are more preferably COO, OCO, CHCHCOO, CHCHOCO, COOCHCH, OCOCHCH, COOCH.sub.2CH.sub.2, OCOCH.sub.2CH.sub.2, CH.sub.2CH.sub.2COO, CH.sub.2CH.sub.2OCO, or a single bond.

(121) n.sup.201 represents 0, 1, or 2, but it is preferably 0 or 1. Meanwhile, when a plurality of each of the ring M.sup.202 and Z.sup.202 are present, each may be the same as or different from each other.

(122) The liquid crystal composition containing a polymerizable compound of the present invention contains at least one kind of the polymerizable compound which is represented by General Formula (M). However, it preferably contains 1 to 5 kinds, and more preferably 1 to 3 kinds. When the content of the polymerizable compound represented by General Formula (M) is low, the force for restricting the alignment of the liquid crystal composition becomes weak. On the other hand, when the content of the polymerizable compound represented by General Formula (M) is excessively high, the energy required for polymerization is increased and the amount of the remaining polymerizable compound without being polymerized is also increased, yielding a cause of having a display defects. Thus, the content is preferably 0.01 to 2.00% by mass, more preferably 0.05 to 1.00% by mass, and particularly preferably 0.10 to 0.50% by mass.

(123) More specifically, when n.sup.201 is 0 in General Formula (M), the ring structure between Sp.sup.201 and Sp.sup.202 preferably has Formula (XXa-1) to Formula (XXa-5). It is more preferable to have Formula (XXa-1) to Formula (XXa-3). It is particularly preferable to have Formula (XXa-1) or Formula (XXa-2). Meanwhile, both ends of the formula should be bonded to Sp.sup.201 or Sp.sup.202.

(124) ##STR00041##

(125) The polymerizable compounds having skeletons as represented by General Formula (M) have a force for restricting the alignment after polymerization which is optimal for a PSA type liquid crystal display element, and as an excellent alignment state is obtained, there is an effect that display unevenness is suppressed or is not generated at all.

(126) Based on the above, as the polymerizable monomer, compounds represented by Formula (XX-1) to General Formula (XX-10) are preferable, and compounds of Formula (XX-1) to Formula (XX-4) are more preferable.

(127) ##STR00042## ##STR00043##

(128) In the formula, Sp.sup.xx represents an alkylene group having carbon atom number of 1 to 8 or O(CH.sub.2).sub.s (in the formula, s represents an integer of 2 to 7 and the oxygen atom is bound to a ring).

(129) Furthermore, the hydrogen atom in the phenyl group in the formula may be substituted with F, Cl, CF.sub.3, CH.sub.3, or any one of Formula (R-1) to Formula (R-15).

(130) When n.sup.201 in General Formula (M) is 1, a polymerizable compound like Formula (M31) to Formula (M48) is preferable.

(131) ##STR00044## ##STR00045## ##STR00046##

(132) The hydrogen atom in the phenyl group and the naphthalene group in the formula may be substituted with F, Cl, CF.sub.3, CH.sub.3, or any one of Formula (R-1) to Formula (R-15).

(133) The polymerizable compounds having skeletons as represented by General Formula (M) have a force for restricting the alignment after polymerization which is optimal for a PSA type liquid crystal display element, and as an excellent alignment state is obtained, there is an effect that display unevenness is suppressed or is not generated at all.

(134) When n.sup.201 in General Formula (M) is 1 and there is a plurality of Formula (R-1) or Formula (R-2), a polymerizable compound like Formula (M301) to Formula (M316) is preferable.

(135) ##STR00047## ##STR00048## ##STR00049##

(136) The hydrogen atom in the phenyl group and the naphthalene group in the formula may be also substituted with F, Cl, CF.sub.3, or CH.sub.3.

(137) As the polymerizable monomer represented by General Formula (M) according to the present invention, polymerizable compounds like Formula (Ia-1) to Formula (Ia-31) are also preferable, for example.

(138) ##STR00050## ##STR00051## ##STR00052## ##STR00053##

(139) The polymerizable compounds having skeletons as represented by General Formula (M) have a force for restricting the alignment after polymerization which is optimal for a PSA type liquid crystal display element, and as an excellent alignment state is obtained, there is an effect that display unevenness is suppressed or is not generated at all.

(140) The liquid crystal composition containing a polymerizable compound which simultaneously contains the first component, the second component, the third component, and General Formula (M) as a polymerizable compound enables obtainment of low viscosity (), low rotational viscosity (.sub.1), and high elastic constant (K.sub.33), and thus high speed response can be achieved by a liquid crystal display element of a PSA type or a PSVA type using the composition.

(141) The liquid crystal display element using the liquid crystal composition of the present invention has significant characteristics of high speed response, and in particular, is useful for the liquid crystal display element for active matrix driving, and can be applied to a liquid crystal display element of a VA type, a PSVA type, a PSA type, an IPS type, or an ECB type.

(142) In the case of adding a polymerizable compound to the liquid crystal composition of the present invention, polymerization proceeds even when a polymerization initiator is not present, however, the polymerization initiator may be contained in order to promote the polymerization. Examples of the polymerization initiator include benzoin ethers, benzophenones, acetophenones, benzyl ketals and acyl phosphine oxides.

(143) The liquid crystal composition of the present invention has 20 C. dielectric anisotropy () of 2.0 to 20.0. However, it is preferably 4.0 to 18.0, more preferably 4.0 to 16.0, and particularly preferably 4.0 to 14.0.

(144) The liquid crystal composition of the present invention has 20 C. refractive index anisotropy (n) of 0.08 to 0.18. However, it is more preferably 0.09 to 0.15 and particularly preferably 0.09 to 0.12. When explained in greater detail, for a case in which it is to respond to a thin cell gap, it is preferably 0.10 to 0.18. For a case in which it is to respond to a thick cell gap, it is preferably 0.08 to 0.10.

(145) The liquid crystal composition of the present invention has 20 C. viscosity () of 10 to 30 mPa.Math.s. However, it is more preferably 10 to 25 mPa.Math.s, and particularly preferably 10 to 20 mPa.Math.s.

(146) The liquid crystal composition of the present invention has 20 C. rotational viscosity (.sub.1) of 50 to 130 mPa.Math.s. However, it is more preferably 50 to 110 mPa.Math.s, and particularly preferably 50 to 90 mPa.Math.s.

(147) The liquid crystal composition of the present invention has a nematic phase-isotropic liquid phase transition temperature (T.sub.ni) of 60 C. to 120 C. However, it is more preferably 70 C. to 110 C., and particularly preferably 70 C. to 100 C.

(148) Hereinafter, in view of the drawings, a liquid crystal display element of horizontal electric field type is explained as one preferred embodiment of the liquid crystal display element according to the present invention, but the liquid crystal display element according to the present invention is not limited thereto.

(149) FIG. 1 schematically shows a structure of a liquid crystal display element. In FIG. 1, components are illustrated in a separated manner for ease of description. As shown in FIG. 1, a liquid crystal display element 10 according to the present invention is a liquid crystal display element of horizontal electric field type (in the drawing, FFS type as an example) including a liquid crystal composition (or a liquid crystal layer 5) sandwiched between a first transparent insulating substrate 2 and a second transparent insulating substrate 7 disposed so as to face each other, which is characterized in that the liquid crystal composition according to the present invention is used as a liquid crystal composition. An electrode layer 3 is formed on a surface of the first transparent insulating substrate 2 on the liquid crystal layer 5 side. A pair of alignment films 4 that are directly in contact with the liquid crystal composition constituting the liquid crystal layer 5 and induce homogeneous alignment are disposed between the liquid crystal layer 5 and the first transparent insulating substrate 2 and between the liquid crystal layer 5 and the second transparent insulating substrate 8. Liquid crystal molecules in the liquid crystal composition are aligned so as to be substantially parallel to the substrates 2 and 7 when no voltage is applied. As shown in FIG. 1 and FIG. 3, the second substrate 7 and the first substrate 2 may be sandwiched between a pair of polarizing plates 1 and 8. In FIG. 1, a color filter 6 is further disposed between the second substrate 7 and the alignment film 4. Furthermore, the liquid crystal display element according to the present invention has the form of so-called color filter-on-array (COA), and a color filter may be formed between an electrode layer containing a thin film transistor and a liquid crystal layer or a color filter may be formed between an electrode layer containing a thin film transistor and the second substrate.

(150) In short, the liquid crystal display element 10 according to the present invention includes the first polarizing plate 1, the first substrate 2, the electrode layer 3 including a thin film transistor, the alignment film 4, the liquid crystal layer 5 containing the liquid crystal composition, the alignment film 4, the color filter 6, the second substrate 7, and the second polarizing plate 8 which are stacked in the order.

(151) The first substrate 2 and the second substrate 7 can be composed of glass or a transparent flexible material such as plastic, and one of the first substrate 2 and the second substrate 7 may be composed of an opaque material such as silicone. Two pieces of the substrates 2 and 7 are bonded to each other with a sealing material or a sealant, such as an epoxy thermosetting composition, disposed in a peripheral region. Further, between them, particulate spacers such as glass particles, plastic particles, or alumina particles or columnar spacers composed of a resin and formed by photolithography may be disposed to maintain the inter-substrate distance.

(152) FIG. 2 is an enlarged plane view of a region of the electrode layer 3 formed on the substrate 2 in FIG. 1, the region being enclosed by line II. FIG. 3 is a sectional view of the liquid crystal display element shown in FIG. 1, the sectional view being taken along line III-III in FIG. 2. As shown in FIG. 2, the electrode layer 3 including a thin film transistor and formed on the surface of the first substrate 2 includes a plurality of gate bus lines 26 for supplying scanning signals and a plurality of data bus lines 25 for supplying display signals, the gate bus lines 26 and the data bus lines 25 intersecting each other so as to form a matrix. Furthermore, FIG. 2 shows only a pair of gate bus lines 25 and a pair of data bus lines 24.

(153) A unit pixel of the liquid crystal display is formed in each of regions surrounded by the plurality of gate bus lines 26 and the plurality of data bus lines 25. In the unit pixel, a pixel electrode 21 and a common electrode 22 are formed. A thin film transistor including a source electrode 27, a drain electrode 24, and a gate electrode 28 is disposed near the intersection of the gate bus lines 26 and the data bus lines 25. The thin film transistor is connected to the pixel electrode 21 as a switching element for supplying display signals to the pixel electrode 21. Furthermore, a common line 29 is disposed so as to be parallel to the gate bus lines 26. The common line 29 is connected to the common electrode 22 to supply common signals to the common electrode 22.

(154) As shown in FIG. 3, a thin film transistor according to a preferred embodiment includes a gate electrode 11 formed on a surface of a substrate 2, a gate insulating layer 12 disposed so as to cover the gate electrode 11 and substantially the entire surface of the substrate 2, a semiconductor layer 13 formed on a surface of the gate insulating layer 12 so as to face the gate electrode 11, a protective film 14 disposed so as to cover part of a surface of the semiconductor layer 17, a drain electrode 16 disposed so as to cover one-side portions of the protective film 14 and the semiconductor layer 13 and so as to be in contact with the gate insulating layer 12 formed on the surface of the substrate 2, a source electrode 17 disposed so as to cover the other-side portions of the protective film 14 and the semiconductor layer 13 and so as to be in contact with the gate insulating layer 12 formed on the surface of the substrate 2, and an insulating protective layer 18 disposed so as to cover the drain electrode 16 and the source electrode 17. A positive electrode oxide film (not shown) may be formed on a surface of the gate electrode 11 for the purpose of, for example, removing a difference in level compared to the gate electrode.

(155) The semiconductor layer 13 may be composed of amorphous silicon, polycrystalline polysilicon, or the like. It is preferable to use a transparent semiconductor film composed of, for example, ZnO, IGZO (InGaZnO), or ITO because harmful effects of photocarriers due to light absorption can be suppressed and the aperture ratio of an element can be increased.

(156) An ohmic contact layer 15 may be disposed between the semiconductor layer 13 and the drain electrode 16 or the source electrode 17 in order to decrease the width and height of a Schottky barrier. The ohmic contact layer may be composed of a material to which an impurity such as phosphorus is added in a high concentration, for example, n type amorphous silicon or n type polycrystalline polysilicon.

(157) The gate bus lines 26, the data bus lines 25, and the common line 29 are preferably metal films. The metal films are preferably composed of Al, Cu, Au, Ag, Cr, Ta, Ti, Mo, W, Ni, or an alloy thereof, and it is more preferable to use a wire of Al or an Al alloy. Furthermore, the insulating protective layer 18 is a layer having an insulating function and is formed of silicon nitride, silicon dioxide, or silicon oxynitride.

(158) In the embodiment shown in FIG. 2 and FIG. 3, the common electrode 22 is a plate-shaped electrode formed on substantially the entire surface of the gate insulating layer 12 whereas the pixel electrode 21 is a comb-shaped electrode formed on the insulating protective layer 18 that covers the common electrode 22. In other words, the common electrode 22 is disposed so as to be closer to the first substrate 2 than the pixel electrode 21, and these electrodes overlap each other with the insulating protective layer 18 disposed therebetween. The pixel electrode 21 and the common electrode 22 are formed of a transparent conductive material such as ITO (indium tin oxide), IZO (indium zinc oxide), or IZTO (indium zinc tin oxide). Since the pixel electrode 21 and the common electrode 22 are formed of a transparent conductive material, the opening area in a unit pixel area is increased, and the aperture ratio and the transmittance are also increased.

(159) For forming a fringe electric field between the pixel electrode 21 and the common electrode 22, the pixel electrode 21 and the common electrode 22 are formed so that the inter-electrode distance: R (also referred to as minimum spacing distance) between the pixel electrode 21 and the common electrode 22 is smaller than the distance: G between the first substrate 2 and the second substrate 7. Note that the inter-electrode distance: R indicates a distance between the electrodes in a direction horizontal to the substrates. FIG. 3 shows an example in which the inter-electrode distance: R is 0 because the plate-shaped common electrode 22 and the comb-shaped pixel electrode 21 overlap each other. To have the minimum spacing distance: R that is smaller than the distance (cell gap) G between the first substrate 2 and the second substrate 7, the fringe electric field E is formed. Thus, in an FFS type liquid crystal display element, a horizontal electric field formed in a direction perpendicular to lines that form a comb-like shape of the pixel electrode 21 and a parabolic electric field can be used. The electrode width: l of a comb-shaped portion of the pixel electrode 21 and the width: m of a gap between comb-shaped portions of the pixel electrode 21 are preferably set in such a manner that all liquid crystal molecules in the liquid crystal layer 5 are driven by the generated electric field. Furthermore, the minimum spacing distance R between the pixel electrode and common electrode can be also adjusted based on (average) film thickness of the gate insulating layer 12. Furthermore, unlike FIG. 3, the liquid crystal display element according to the present invention can be also formed such that the inter-electrode distance: R (also referred to as minimum spacing distance) between the pixel electrode 21 and the common electrode 22 is larger than the distance: G between the first substrate 2 and the second substrate 7 (IPS type). Examples of such case include a structure in which a comb-shaped pixel electrode and a comb-shaped common electrode are approximately formed in an alternating manner in the same plane.

(160) The liquid crystal display element according to the present invention preferably has a liquid crystal display composition of FFS type using a fringe electric field, and as the minimum spacing distance d adjacent to the common electrode 22 and the pixel electrode 21 is shorter than the minimum spacing distance D between the alignment films 4 (inter-substrate distance), a fringe electric field is formed between the common electrode and pixel electrode so that the alignment of liquid crystal molecules both in horizontal direction and vertical direction can be efficiently utilized. In a liquid crystal display element of FFS type like the preferred embodiment of the present invention, when voltage is applied to liquid crystal molecules which are disposed such that the long axis direction is parallel to the alignment direction, an arc-like equipotential line of the electric field is formed between the pixel electrode 21 and the common electrode 22, as high as the top of the pixel electrode 21 and the common electrode 22. Thus, the long axis of the liquid crystal molecules within the liquid crystal layer 5 is aligned along the formed electric field. In particular, in the liquid crystal composition according to the present invention, the long axis of the liquid crystal molecules is aligned along the generated electric field for utilization of the liquid crystal molecules which have a positive dielectric anisotropy.

(161) In the color filter 6, a black matrix (not shown) is preferably formed in regions corresponding to the thin film transistor and a storage capacitor 23 from the viewpoint of preventing the leakage of light.

(162) A pair of alignment films 4 that induce homogeneous alignment are disposed on the electrode layer 3 and the color filter 6 so as to be directly in contact with the liquid crystal composition constituting the liquid crystal layer 5.

(163) The polarizing plate 1 and the polarizing plate 8 can be adjusted so that a satisfactory viewing angle and a high contrast are achieved by adjusting the polarization axis of each of the polarizing plates. They preferably have transmission axes that are perpendicular to each other so that a display element is operated in a normally black mode. In particular, one of the polarizing plate 1 and the polarizing plate 8 is preferably disposed so as to have a transmission axis parallel to the alignment direction of the liquid crystal molecules 30. The product of the refractive index anisotropy n of the liquid crystal and the cell thickness d is preferably adjusted so that the contrast is maximized. Furthermore, a phase difference film may be used to increase the viewing angle.

EXAMPLES

(164) The present invention will now be described below in detail based on Examples, but is not limited to Examples. In the compositions of Examples and Comparative Examples below, % means % by mass.

(165) The properties that were measured in Examples are as follows.

(166) T.sub.ni: nematic phase-isotropic liquid phase transition temperature ( C.)

(167) n: refractive index anisotropy at 20 C.

(168) : dielectric anisotropy at 20 C.

(169) : viscosity (mPa.Math.s) at 20 C.

(170) 1: rotational viscosity (mPa.Math.s) at 20 C.

(171) RT: response rate (msec) at 20 C. (VA cell with cell thickness of 3.5 m)

(172) VHR (Init): voltage holding ratio (%) at 60 C. under conditions including a frequency of 60 Hz and an applied voltage of 1 V

(173) VHR (HEAT): voltage holding ratio (%) at 60 C. under conditions including a frequency of 60 Hz and an applied voltage of 1 V, which is measured after keeping for 48 hours at 100 C.

(174) Drop mark: Drop mark evaluation for the liquid crystal display element was performed, on the basis of the four-level evaluation below, by visually evaluating a drop mark that appeared white on a black screen.

(175) : No drop mark was observed.

(176) : Faint drop mark was observed but the degree of the drop mark was acceptable.

(177) : Drop mark was observed and the degree of the drop mark was unacceptable.

(178) x: Very poor drop mark was observed.

(179) Line afterimage: Line afterimage evaluation for the liquid crystal display element was performed after displaying a particular fixed pattern in a display area for 2000 hours, and visually evaluating, on the basis of the four-level evaluation below, the degree of the line-shaped afterimage occurring in a marginal region of the fixed pattern.

(180) : No line afterimage was observed.

(181) : Faint line afterimage was observed but the degree of the afterimage was acceptable.

(182) : Line afterimage was observed and the degree of the afterimage was unacceptable.

(183) x: Line afterimage at significantly poor level.

(184) (Side Chain)

(185) TABLE-US-00001 -F F fluorine atom F- F fluorine atom -n C.sub.nH.sub.2n+1 linear alkyl group having carbon atom number of n n- C.sub.nH.sub.2n+1 linear alkyl group having carbon atom number of n -On OC.sub.nH.sub.2n+1 linear alkoxyl group having carbon atom number of n nO- C.sub.nH.sub.2n+1O linear alkoxyl group having carbon atom number of n -V CHCH.sub.2 V- CH.sub.2CH -V1 CHCHCH.sub.3 1V- CH.sub.3CHCH -2V CH.sub.2CH.sub.2CHCH.sub.3 V2- CH.sub.3CHCH.sub.2CH.sub.2 -2V1 CH.sub.2CH.sub.2CHCHCH.sub.3 1V2- CH.sub.3CHCHCH.sub.2CH.sub.2
(Linking Group)
CF2O CF.sub.2O
OCF2- OCF.sub.2
-1O CH.sub.2O
O1- OCH.sub.2
COO COO
(Ring Structure)

(186) ##STR00054##

Example 1, Comparative Example 1, and Comparative Example 2

(187) The liquid crystal composition LC-1 (Example 1), liquid crystal composition LC-A (Comparative example 1) and liquid crystal composition LC-B (Comparative example 2) were prepared, and as a result of measuring the physical properties, measuring VHR (Init) and VHR (HEAT), and determining the presence or absence of drop mark and line afterimage, the results as described below are obtained.

(188) TABLE-US-00002 TABLE 1 Comparative Comparative Example 1 example 1 example 2 LC-1 LC-A LC-B Anti-oxidizing agent Formula (II-a8) 0.02 Anti-oxidizing agent Formula (St-1) 0.02 Anti-oxidizing agent Formula (St-2) 0.02 2-Ph2-O1-Cy-Ph2-Ph2-F General formula (K) 2 2 2 3-Ph2-O1-Cy-Ph2-Ph2-F General formula (K) 2 2 2 4-Ph2-O1-Cy-Ph2-Ph2-F General formula (K) 2 2 2 5-Ph2-O1-Cy-Ph2-Ph2-F General formula (K) 2 2 2 3-Cy-Cy-2 General formula (III-A) 6.98 6.98 6.98 3-Cy-Cy-V General formula (III-A) 6 6 6 3-Ph-Ph-1 General formula (III-F) 3 3 3 5-Ph-Ph-1 General formula (III-F) 10 10 10 V-Cy-Cy-Ph-1 General formula (III-G) 4 4 4 3-Cy-Cy-Ph-1 General formula (III-G) 4 4 4 3-Cy-Cy-Ph-3 General formula (III-G) 4 4 4 3-Cy-Ph-Ph-2 General formula (III-H) 2 2 2 V-Cy-Ph-Ph-3 General formula (III-H) 6 6 6 2-Cy-Cy-Ph1-F General formula (Pa) 17 17 17 3-Cy-Cy-Ph1-F General formula (Pa) 17 17 17 2-Cy-Cy-Ph-Ph1-F General formula (Pa) 4 4 4 3-Cy-Cy-Ph-Ph1-F General formula (Pa) 4 4 4 4-Cy-Cy-Ph-Ph1-F General formula (Pa) 4 4 4 Total 100 100 100 Tni [ C.] 103.4 103.2 103.3 Tcn [ C.] 22 22 22 n 0.109 0.109 0.109 [mPa .Math. s] 20.4 20.4 20.4 1 [mPa .Math. s] 125 124 126 5.0 5.0 5.0 VHR (Init) 99.9 99.8 99.8 VHR (HEAT) 99.9 99.5 99.7 Drop mark Line afterimage X

(189) Furthermore, the anti-oxidizing agents (St-1) and (St-2) are compounds represented as follows.

(190) ##STR00055##

(191) A significant difference was found in terms of VHR (HEAT), presence or absence of drop mark, and line afterimage. Based on these results, it was determined that the liquid crystal composition LC-1 of the present invention has a liquid crystal phase in a broad temperature range, low viscosity, and high specific resistance or voltage holding ratio due to good solubility at low temperature, and it is a liquid crystal composition which is stable against heat or light and has a positive . Thus, a liquid crystal display element using the composition can have excellent display quality and hardly exhibits an occurrence of display defects like drop mark or line afterimage.

Example 2 and Example 3

(192) The liquid crystal composition LC-2 (Example 2) and liquid crystal composition LC-3 (Example 3) were prepared, and as a result of measuring the physical properties, measuring VHR (Init) and VHR (HEAT), and determining the presence or absence of drop mark and line afterimage, the results as described below are obtained.

(193) TABLE-US-00003 TABLE 2 Example 2 Example 3 LC-2 LC-3 Anti-oxidizing agent Formula (II-a8) 0.01 0.03 Anti-oxidizing agent Formula (II-a9) 0.01 2-Ph2-O1-Cy-Ph2-Ph2-F General formula (K1) 8 8 3-Ph2-O1-Cy-Ph2-Ph2-F General formula (K1) 5 5 4-Ph2-O1-Cy-Ph2-Ph2-F General formula (K1) 2 2 5-Ph2-O1-Cy-Ph2-Ph2-F General formula (K1) 5 2-Ph2-O1-Cy-Ph2-Np2-F General formula (K2) 2 3-Ph2-O1-Cy-Ph2-Np2-F General formula (K2) 3 3-Ph-Ph1-Ph2-CF2O- General formula (N3) 3 Np2-F 4-Ph-Ph1-Ph2-CF2O- General formula (N3) 3 Np2-F 2-Ph-Ph1-CF2O-Np2-F General formula (N3) 3 3-Ph-Ph1-CF2O-Np2-F General formula (N3) 13 4 3-Cy-Cy-V General formula 29.98 38.97 (III-A) 3-Cy-Cy-V1 General formula 9 (III-A) 3-Ph-Ph-1 General formula 5 (III-F) 5-Ph-Ph-1 General formula 5 (III-F) 3-Cy-Cy-Ph-1 General formula 5 5 (III-G) V-Cy-Ph-Ph-3 General formula 5 5 (III-H) 3-Cy-Cy-COO-Ph-Cy-3 Formula (V-9.1) 3 3-Cy-Cy-Ph1-F General formula (Pa) 12 10 3-Cy-Cy-Ph-Ph1-F General formula (Pa) 1 Total 100 100 Tni [ C.] 71.3 81.4 Tcn [ C.] 42 45 n 0.100 0.108 [mPa .Math. s] 14.8 15.7 1 [mPa .Math. s] 112 129 10.3 10.5 VHR (Init) 99.9 99.8 VHR (HEAT) 99.8 99.8 Drop mark Line afterimage

(194) It was found the VHR (Init) and VHR (HEAT) are sufficiently high, a drop mark is not present, and a line afterimage is not present. Based on these results, it was determined that the liquid crystal compositions LC-2 and LC-3 of the present invention have a liquid crystal phase in a broad temperature range, low viscosity, and high specific resistance or voltage holding ratio due to good solubility at low temperature, and they are a liquid crystal composition which is stable against heat or light and has a positive . Thus, a liquid crystal display element using the composition can have excellent display quality and hardly exhibits an occurrence of display defects like drop mark or line afterimage.

REFERENCE SIGNS LIST

(195) 1, 8 polarizing plate 2 first substrate 3 electrode layer 4 alignment film 5 liquid crystal layer 6 color filter 6G color filter green 6R color filter red 7 second substrate 11 gate electrode 12 gate insulating layer 13 semiconductor layer 14 insulating layer 15 ohmic contact layer 16 drain electrode 17 source electrode 18 insulating protective layer 21 pixel electrode 22 common electrode 23 storage capacitor 24 drain electrode 25 data bus line 27 source bus line 29 common line 30 buffer layer