Liquid crystal composition and liquid crystal display element

1. A liquid crystal composition comprising at least one compound selected from a group of compounds represented by formula (1) as a first component, at least one compound selected from a group of compounds represented by formulae (2) to (4) as a second component and at least one compound selected from a group of compounds represented by formulae (5) to (7) as a third component, having a positive dielectric anisotropy, and having a nematic phase:

wherein R 1 is alkyl; R 3 is alkyl or alkenyl; R 4 is alkyl, alkenyl or alkenyl having arbitrary hydrogen substituted by fluorine; R 5 is alkyl or alkoxy; R 6 is alkyl or alkoxymethyl; R 11 and R 12 are alkyls having different carbon numbers; A 1 and A 6 are independently 1,4-cyclohexylene or 1,4-phenylene; A 2 is 1,4-cyclohexylene, 1,3-dioxane-2,5-diyl or 1,4-phenylene; A 3 is 1,4-cyclohexylene, 1,3-dioxane-2,5-diyl, 1,4-phenylene, 2-fluoro-1,4-phenylene or 2,6-difluoro-1,4-phenylene; A 4 is 1,4-cyclohexylene, 1,4-phenylene or 2-fluoro-1,4-phenylene; A 5 is 1,4-phenylene, 2-fluoro-1,4-phenylene or 2,6-difluoro-1,4-phenylene; A 7 is 1,4-phenylene or 2-fluoro-1,4-phenylene; Z 1 is a single bond, —(CH 2 ) 2 —, —CF 2 O— or —COO—; Z 2 is a single bond or —(CH 2 ) 2 —; Z 3 is a single bond or —CF 2 O—; Z 4 is a single bond or —COO—; X 1 and X 2 are independently hydrogen or fluorine; Y 1 is fluorine, chlorine, —OCF 3 or —OCF 2 H; and Y 2 is fluorine or chlorine; and

wherein the second component at least includes a compound selected from a group of compounds represented by formula (3-1):

2. The liquid crystal composition according to claim 1 , wherein a ratio of the first component is in a range of approximately 3% by weight or more and less than approximately 10% by weight, a ratio of the second component is in a range of from approximately 10% to approximately 85% by weight, and a ratio of third component is in a range of from approximately 10% to approximately 80% by weight.

3. The liquid crystal composition according to claim 1 , wherein a ratio of the first component is in a range of from approximately 10% to approximately 50% by weight, a ratio of the second component is in a range of from approximately 10% to approximately 85% by weight, and a ratio of third component is in a range of from approximately 10% to approximately 80% by weight.

4. The liquid crystal composition according to claim 1 , wherein the composition has an optical anisotropy ranging from approximately 0.10 to approximately 0.15.

5. The liquid crystal composition according to claim 2 , wherein the composition has an optical anisotropy ranging from approximately 0.10 to approximately 0.15.

6. The liquid crystal composition according to claim 3 , wherein the composition has an optical anisotropy ranging from approximately 0.10 to approximately 0.15.

7. A liquid crystal composition comprising at least one compound selected from a group of compounds represented by formula (1) as a first component, at least one compound selected from a group of compounds represented by formulae (2-1), (3-1) to (3-6) and (4-1) as a second component and at least one compound selected from a group of compounds represented by formulae (5-1), (5-2), (6-1), (6-2) and (7-1) as a third component, having a positive dielectric anisotropy, and having a nematic phase:

wherein R 1 and R 2 are independently alkyl; R 7 is alkenyl; and R 11 and R 12 are alkyls having different carbon numbers; and

wherein the second component at least includes a compound selected from the group of compounds represented by formula (3-1).

8. The liquid crystal composition according to claim 7 , wherein a ratio of the first component is in a range of approximately 3% by weight or more and less than approximately 10% by weight, a ratio of the second component is in a range of from approximately 10% to approximately 85% by weight, and a ratio of third component is in a range of from approximately 10% to approximately 80% by weight.

9. The liquid crystal composition according to claim 7 , wherein a ratio of the first component is in a range of from approximately 10% to approximately 50% by weight, a ratio of the second component is in a range of from approximately 10% to approximately 85% by weight, and a ratio of third component is in a range of from approximately 10% to approximately 80% by weight.

10. The liquid crystal composition according to claim 7 , wherein the composition has an optical anisotropy ranging from approximately 0.10 to approximately 0.15.

11. The liquid crystal composition according to claim 8 , wherein the composition has an optical anisotropy ranging from approximately 0.10 to approximately 0.15.

12. The liquid crystal composition according to claim 9 , wherein the composition has an optical anisotropy ranging from approximately 0.10 to approximately 0.15.

13. The liquid crystal composition according to claim 1 , wherein the composition further comprises an antioxidant.

14. The liquid crystal composition according to claim 13 , wherein the antioxidant is a compound represented by formula (10):

wherein n is an integer of 1 to 9.

15. A liquid crystal display element comprising the liquid crystal composition according to one of claim 1 .

16. A liquid crystal display element comprising the liquid crystal composition according to one of claim 7 .

17. A liquid crystal display element comprising the liquid crystal composition according to one of claim 13 .