Liquid crystal composition and liquid crystal display device thereof

Abstract

Provided is a liquid crystal composition, comprising: one or more compounds of general formula I accounting for 1-30% of the total weight of the liquid crystal composition; one or more compounds of general formula II accounting for 1-30% of the total weight of the liquid crystal composition; one or more compounds of general formula III accounting for 1-20% of the total weight of the liquid crystal composition; and one or more compounds of general formula IV accounting for 30-80% of the total weight of the liquid crystal composition. The liquid crystal composition has at least one of the following properties: a large specific resistance, a high voltage holding ratio, a suitable optical anisotropy, a large dielectric anisotropy, a small viscosity, a low threshold voltage, etc., and is also green and environmentally friendly. The liquid crystal composition is suitable for use in a liquid crystal display device, enabling the liquid crystal display device to have the following properties: a high voltage holding ratio, a short response time, a high contrast ratio, a low energy consumption, and being green and environmentally friendly, etc. ##STR00001##

Claims

1. A liquid crystal composition, comprising: one or more compounds of general formula I accounting for 5-30% of the total weight of the liquid crystal composition ##STR00124## one or more compounds of general formula II accounting for 1-30% of the total weight of the liquid crystal composition ##STR00125## one or more compounds of general formula III accounting for 1-20% of the total weight of the liquid crystal composition ##STR00126## and one or more compounds of general formula IV accounting for 30-80% of the total weight of the liquid crystal composition ##STR00127## wherein, R, R.sub.4, R.sub.5, R.sub.6 and R.sub.7 are the same or different, and each independently represents an alkyl having 1-7 carbon atoms, an alkoxy having 1-7 carbon atoms or an alkenyl having 2-7 carbon atoms; R.sub.3 represents H, an alkyl having 1-7 carbon atoms, an alkoxy having 1-7 carbon atoms or an alkenyl having 2-7 carbon atoms; ring ##STR00128## represents ##STR00129## ring ##STR00130## and ring ##STR00131## are the same or different, and each independently represents ##STR00132## Y represents CF.sub.3 or OCF.sub.3; X represents F or OCF.sub.2CF=CF.sub.2; L.sub.1 and L.sub.2 are the same or different, and each independently represents H or F; m represents 1, 2 or 3; n represents 1 or 2; when m is 2 or 3, rings ##STR00133## may be the same or different, and each independently represents ##STR00134## when n is 2, rings ##STR00135## may be the same or different, and each independently represents ##STR00136##

2. The liquid crystal composition according to claim 1, wherein the compounds of general formula I are selected from the group consisting of the following compounds: ##STR00137## wherein, R.sub.1, R.sub.2 are the same or different, and each independently represents an alkyl having 1-7 carbon atoms or an alkoxy having 1-7 carbon atoms.

3. The liquid crystal composition according to claim 2, wherein the compounds of general formula IA account for 5-30% of the total weight of the liquid crystal composition.

4. The liquid crystal composition according to claim 2, wherein the compounds of general formula IB account for 5-30% of the total weight of the liquid crystal composition.

5. The liquid crystal composition according to claim 2, wherein the compounds of general formula IA are selected from the group consisting of: ##STR00138## the compounds of general formula IB are selected from the group consisting of: ##STR00139##

6. The liquid crystal composition according to claim 1, wherein the compounds of general formula II are selected from the group consisting of: ##STR00140## ##STR00141## wherein, R.sub.3 represents H, an alkyl having 1-7 carbon atoms or an alkoxy having 1-7 carbon atoms.

7. The liquid crystal composition according to claim 6, wherein the compounds of general formula II-1 are selected from the group consisting of: ##STR00142## the compounds of general formula II-2 are selected from the group consisting of: ##STR00143## the compounds of general formula II-3 are selected from the group consisting of: ##STR00144## the compounds of general formula II-4 are selected from the group consisting of: ##STR00145## the compounds of general formula II-5 are selected from the group consisting of: ##STR00146## the compounds of general formula II-6 are selected from the group consisting of: ##STR00147## the compounds of general formula II-7 are selected from the group consisting of: ##STR00148## the compounds of general formula II-8 are selected from the group consisting of: ##STR00149## the compounds of general formula II-9 are selected from the group consisting of: ##STR00150## the compounds of general formula II-10 are selected from the group consisting of: ##STR00151## the compounds of general formula II-11 are selected from the group consisting of: ##STR00152## the compounds of general formula II-12 are selected from the group consisting of: ##STR00153## the compounds of general formula II-13 are selected from the group consisting of: ##STR00154##

8. The liquid crystal composition according to claim 1, wherein the compounds of general formula III are selected from the group consisting of: ##STR00155## wherein, R.sub.5 represents an alkyl having 1-5 carbon atoms or an alkenyl having 2-5 carbon atoms.

9. The liquid crystal composition according to claim 8, wherein the compounds of general formula III-1 are selected from the group consisting of: ##STR00156## the compounds of general formula III-2 are selected from the group consisting of: ##STR00157## the compounds of general formula III-3 are selected from the group consisting of: ##STR00158## the compounds of general formula III-4 are selected from the group consisting of: ##STR00159## the compounds of general formula III-5 are selected from the group consisting of: ##STR00160##

10. The liquid crystal composition according to claim 1, wherein the compounds of general formula IV are selected from the group consisting of: ##STR00161## wherein, R.sub.6 and R.sub.7 are the same or different, and each independently represents an alkyl having 1-7 carbon atoms, an alkoxy having 1-7 carbon atoms or an alkenyl having 2-7 carbon atoms.

11. The liquid crystal composition according to claim 10, wherein the compounds of general formula IV-1 are selected from the group consisting of: ##STR00162## ##STR00163## the compounds of general formula IV-2 are selected from the group consisting of: ##STR00164## ##STR00165## the compounds of general formula IV-3 are selected from the group consisting of: ##STR00166## the compounds of general formula IV-4 are selected from the group consisting of: ##STR00167## ##STR00168##

12. The liquid crystal composition according to claim 1, wherein the compounds of general formula I account for 5-20% of the total weight of the liquid crystal composition; the compounds of general formula II account for 10-30% of the total weight of the liquid crystal composition; the compounds of general formula III account for 1-10% of the total weight of the liquid crystal composition; the compounds of general formula IV account for 45-75% of the total weight of the liquid crystal composition.

13. A liquid crystal display device, the device comprises the liquid crystal composition of claim 1.

14. The liquid crystal composition according to claim 2, wherein the compounds of general formula I account for 5-20% of the total weight of the liquid crystal composition; the compounds of general formula II account for 10-30% of the total weight of the liquid crystal composition; the compounds of general formula III account for 1-10% of the total weight of the liquid crystal composition; the compounds of general formula IV account for 45-75% of the total weight of the liquid crystal composition.

15. The liquid crystal composition according to claim 5, wherein the compounds of general formula I account for 5-20% of the total weight of the liquid crystal composition; the compounds of general formula II account for 10-30% of the total weight of the liquid crystal composition; the compounds of general formula III account for 1-10% of the total weight of the liquid crystal composition; the compounds of general formula IV account for 45-75% of the total weight of the liquid crystal composition.

16. The liquid crystal composition according to claim 6, wherein the compounds of general formula I account for 5-20% of the total weight of the liquid crystal composition; the compounds of general formula II account for 10-30% of the total weight of the liquid crystal composition; the compounds of general formula III account for 1-10% of the total weight of the liquid crystal composition; the compounds of general formula IV account for 45-75% of the total weight of the liquid crystal composition.

17. The liquid crystal composition according to claim 8, wherein the compounds of general formula I account for 5-20% of the total weight of the liquid crystal composition; the compounds of general formula II account for 10-30% of the total weight of the liquid crystal composition; the compounds of general formula III account for 1-10% of the total weight of the liquid crystal composition; the compounds of general formula IV account for 45-75% of the total weight of the liquid crystal composition.

18. The liquid crystal composition according to claim 10, wherein the compounds of general formula I account for 5-20% of the total weight of the liquid crystal composition; the compounds of general formula II account for 10-30% of the total weight of the liquid crystal composition; the compounds of general formula III account for 1-10% of the total weight of the liquid crystal composition; the compounds of general formula IV account for 45-75% of the total weight of the liquid crystal composition.

19. A liquid crystal display device, the device comprises the liquid crystal composition of claim 2.

20. A liquid crystal display device, the device comprises the liquid crystal composition of claim 12.

Description

DETAILED DESCRIPTION OF THE EMBODIMENTS

(1) The invention will be described in conjunction with embodiments hereinbelow. It should be noted that the following embodiments are merely examples of the invention and intended to illustrate the invention instead of limiting it. Various combinations and modifications may be made to the illustrative embodiment without departing from the spirit or scope of the invention.

(2) To facilitate the description, in the following embodiments, codes listed in table 1 will be used to represent the group structures of the liquid crystal compositions:

(3) TABLE-US-00001 TABLE 1 Codes for group structures in liquid crystal compounds Unit structure of the group code Name of the group C 1,4-cyclohexylene P 1,4-phenylene G 2-fluoro-1,4-phenylene U 2,5-difluoro-1,4-phenylene C(5) Cyclopentyl 0 C(O) Monooxycyclopentyl D Dioxanyl I Indenyl OCF.sub.3 OCF.sub.3 Trifluoromethoxy COO E Carboxy F F Fluoro substituent CF.sub.2O Q Difluoromethyleneoxy O O Oxy substituent C.sub.nH.sub.2n+1 or C.sub.mH.sub.2m+1 n or m Alkyl CHCH V Vinyl CH.sub.2CH.sub.2 2 Ethylene

(4) Take a compound of the following structural formula as an example:

(5) ##STR00123##

(6) With the codes listed in table 1, the formula may be denoted as: nCGUF, in which n represents the number of carbon atoms in the left alkyl. For example, if n is 2, then the alkyl is C2H5. C represents cyclohexyl, G represents 2-fluoro-1,4-phenylene, U represents 2,5-difluoro-1,4-phenylene and F represents fluoro substituent.

(7) In the following embodiments, the abbreviated designations for the test subjects are as follows:

(8) Cp: clear point (nematic-isotropic phase transition temperature, C.)

(9) n: optical anisotropy (589 nm, 25 C.)

(10) : dielectric anisotropy (1 KHz, 25 C.)

(11) : flow viscosity (mm.sup.2.Math.s.sup.1, 25 C., unless specified otherwise)

(12) V.sub.10 threshold voltage (the characteristic voltage at relative contrast ratio of 10%)

(13) t.sub.30 C. low temperature storage life (at 30 C.)

(14) : specific resistance (25 C., e10.Math..Math.cm)

(15) VHR (initial): initial voltage holding ratio (%)

(16) VHR (UV): voltage holding ratio after being irradiated with UV light for 20 minutes (%)

(17) VHR (high temperature): voltage holding ratio after being held at 150 C. for 1 h (%)

(18) Wherein, the optical anisotropy was measured with Abbe refractometer, under sodium light source (589 nm), at 25 C.; the test conditions for V.sub.10: C/1 KHZ, JTSB7.0;

(19) =, in which, is the dielectric constant parallel to the molecular axis, is the dielectric constant perpendicular to the molecular axis, the test conditions: 25 C., 1 KHz, the test cell model TN90, cell gap: 7 m;

(20) Specific resistance (; measured at 25 C.; , cm)

(21) 1.0 ml liquid crystal was injected into the cell and an AC voltage of 10V was applied. The DC current was measured subsequent to having applied the voltage for ten seconds. The specific resistance was calculated.

(22) was calculated according to the following equation:
(specific resistance)={(voltage)(cell capacity)}/{(DC current)(dielectric constant in vacuum)}

(23) VHR (initial) was measured with a LC Material Characteristics Measurement System Model 6254; test temperature: 60 C., voltage: 5V, frequency: 6 Hz;

(24) VHR (UV) was measured with the LC Material Characteristics Measurement System Model 6254 following irradiating the liquid crystal with light with a wavelength of 365 nm, an energy of 6000 mJ/cm2 for 20 minutes, test temperature: 60 C., voltage: 5V, frequency: 6 Hz;

(25) VHR (high temperature) was measured with the LC Material Characteristics Measurement System Model 6254, the measurement was conducted after the liquid crystal was held at 150 C. for 1 h, test temperature: 60 C., voltage: 5V, frequency: 6 Hz;

(26) The components employed in the following embodiments may be synthesized via known methods or commercially available. The synthesis techniques are conventional and the resultant liquid crystal compounds comply with the related standards.

(27) Liquid crystal compositions were prepared according to the formulas specified in the following embodiments. The preparations were conducted according to the conventional methods of the art, such as mixing the ingredients in specified proportion by heating, supersonic, suspension, etc.

(28) The liquid crystal compositions of the following embodiments were prepared and studied. The compositions and properties of the liquid crystal compositions are illustrated below.

Comparative Example 1

(29) The liquid crystal composition of Comparative Example 1 was prepared as per the compounds and their respective weight percentages listed in table 2. The liquid crystal composition was injected between the liquid crystal display substrates and tests were conducted. The test results are as follows:

(30) TABLE-US-00002 TABLE 2 Formulation of liquid crystal composition and performances tested Code of Test result of performance component Content, % parameters 3CPO2 2.5 Cp 88 5CPUF 2 n 0.096 3CPP2 6 7.1 2CCUF 11.5 23 3CCUF 11 V.sub.10 1.56 3PGP2 5 t.sub.30 C. <400 h 3CCGF 5 VHR (initial) 93 5CCGF 5.5 VHR (UV) 90 2CCPUF 3.5 VHR (high 94 temperature) 3CCPUF 4 4000 3CCV1 8 3CCV 26 3CCEPC4 5 3CCEPC5 5 Total 100

Comparative Example 2

(31) The liquid crystal composition of Comparative Example 2 was prepared as per the compounds and their respective weight percentages listed in table 3. The liquid crystal composition was injected between the liquid crystal display substrates and tests were conducted. The test results are as follows:

(32) TABLE-US-00003 TABLE 3 Formulation of liquid crystal composition and performances tested Code of Test result of performance component Content, % parameters 3CPUF 2 Cp 85 2CCUF 6 n 0.095 3CCUF 8 7.3 3CCQUF 16 21 VCCP1 3 V.sub.10 1.52 3CCV 2 t.sub.30 C. <400 h 3PUQUF 19 VHR (initial) 95 3CCEPC3 4 VHR (UV) 91 3CCEPC4 3 VHR (high 96 temperature) 2CCPOCF.sub.3 10 5000 3CCPOCF.sub.3 10 2CCQUF 14 2PGP3 3 Total 100

Example 1

(33) The liquid crystal composition of Example 1 was prepared as per the compounds and their respective weight percentages listed in table 4. The liquid crystal composition was injected between the liquid crystal display substrates and tests were conducted. The test results are as follows:

(34) TABLE-US-00004 TABLE 4 Formulation of liquid crystal composition and performances tested Code of Code of Test result of performance component structure Content, % parameters 3PGPC2 / 3 Cp 90 3PGP2 III-3-1 4 n 0.111 1PGP2V III-1-5 3 8 3CCV2F / 8 14 VCCP1 IV-3-1 8 V.sub.10 1.35 3CPP2 IV-4-5 5 t.sub.30 C. >500 h 3CPO2 IV-2-18 6 VHR (initial) 98 3CCV IV-1-12 32 VHR (UV) 94 3CCV1 IV-1-16 8 VHR (high 97.5 temperature) 2IPGQUF II-10-1 4 12000 3PUQUF II-5-2 5 5PGUQUF II-8-4 5 3PGUQPCF.sub.3 I A-3 4 4PGUQPCF.sub.3 I A-4 5 Total 100

Example 2

(35) The liquid crystal composition of Example 2 was prepared as per the compounds and their respective weight percentages listed in table 5. The liquid crystal composition was injected between the liquid crystal display substrates and tests were conducted. The test results are as follows:

(36) TABLE-US-00005 TABLE 5 Formulation of liquid crystal composition and performances tested Code of Code of Test result of performance component structure Content, % parameters 3PGPC2 / 3 Cp 93 VCCP1 IV-3-1 8 n 0.113 3CPP2 IV-4-5 5 7.9 3CPO2 IV-2-18 6 13 3PGP2 III-3-1 4 V.sub.10 1.36 3PGP4 III-3-3 4 t.sub.30 C. >500 h 3CCV IV-1-12 30 VHR (initial) 97 3CCV1 IV-1-16 11 VHR (UV) 93 3CCQUF II-1-2 5 VHR (high 96 temperature) 2IPUQUF II-11-1 5 15000 4IPGUQUF II-13-3 6 5IPGUQUF II-13-4 2 3DCQUF II-3-2 2 3PGUQPCF.sub.3 I A-3 4 4PGUQPCF.sub.3 I A-4 5 Total 100

Example 3

(37) The liquid crystal composition of Example 3 was prepared as per the compounds and their respective weight percentages listed in table 6. The liquid crystal composition was injected between the liquid crystal display substrates and tests were conducted. The test results are as follows:

(38) TABLE-US-00006 TABLE 6 Formulation of liquid crystal composition and performances tested Code of Code of Test result of performance component structure Content, % parameters 3PGP2 III-3-1 2 Cp 92 3PGP4 III-3-3 5 n 0.109 3CCP2 IV-3-9 5 8.5 3CPO2 IV-2-18 6 12 VCCP1 IV-3-1 6 V.sub.10 1.31 2CPP3 IV-4-2 6 t.sub.30 C. >500 h 3CCV IV-1-12 30 VHR (initial) 98 3CCV1 IV-1-16 11 VHR (UV) 95 3IPUQUF II-11-2 5 VHR (high 97 temperature) 2IPUQUF II-11-1 5 14000 3PGUQUF II-8-2 6 4PGUQUF II-8-3 2 5PGUQUF II-8-4 2 3PGUQPOCF.sub.3 I B-3 4 2PGUQPOCF.sub.3 I B-2 5 Total 100

Example 4

(39) The liquid crystal composition of Example 4 was prepared as per the compounds and their respective weight percentages listed in table 7. The liquid crystal composition was injected between the liquid crystal display substrates and tests were conducted. The test results are as follows:

(40) TABLE-US-00007 TABLE 7 Formulation of liquid crystal composition and performances tested Code of Code of Test result of performance component structure Content, % parameters 3CPO2 IV-2-18 15 Cp 90 3CCP1 IV-3-8 3 n 0.108 3PGP2 III-3-1 2 7.8 3PGP4 III-3-3 2 11 VCCP1 IV-3-1 6 V.sub.10 1.41 3CCV IV-1-12 36 t.sub.30 C. >500 h 3CCV1 IV-1-16 11 VHR (initial) 98 3IPUQUF II-11-2 5 VHR (UV) 93 2IPUQUF II-11-1 5 VHR (high 97 temperature) 3DCQUF II-3-2 4 17000 4DUQUF II-4-3 4 3PGUQPOCF.sub.3 I B-3 5 2PGUQPOCF.sub.3 I B-2 2 Total 100

Example 5

(41) The liquid crystal composition of Example 5 was prepared as per the compounds and their respective weight percentages listed in table 8. The liquid crystal composition was injected between the liquid crystal display substrates and tests were conducted. The test results are as follows:

(42) TABLE-US-00008 TABLE 8 Formulation of liquid crystal composition and performances tested Code of Code of Test result of performance component structure Content, % parameters 3PGP2 III-3-1 5 Cp 93 3PGP4 III-3-3 5 n 0.109 3CPP2 IV-4-5 6 7.9 3CPP4 IV-4-7 6 12 3CP2 IV-2-5 3 V.sub.10 1.38 VCCP1 IV-3-1 7 t.sub.30 C. >500 h 3CCV IV-1-12 35 VHR (initial) 98 3CPO1 IV-2-14 5 VHR (UV) 94 2IPUQUF II-11-1 6 VHR (high 97 temperature) 3IPGUQUF II-13-2 6 15000 3DCQUF II-3-2 3 4DUQUF II-4-3 3 3PGUQPOCF.sub.3 I B-3 5 3PGUQPCF.sub.3 I A-3 5 Total 100

Example 6

(43) The liquid crystal composition of Example 6 was prepared as per the compounds and their respective weight percentages listed in table 9. The liquid crystal composition was injected between the liquid crystal display substrates and tests were conducted. The test results are as follows:

(44) TABLE-US-00009 TABLE 9 Formulation of liquid crystal composition and performances tested Code of Code of Test result of performance component structure Content, % parameters 3PGP2 III-3-1 4 Cp 93 3PGP4 III-3-3 5 n 0.113 VCCP1 IV-3-1 10 8.4 3CCV IV-1-12 35 13 3IPUQUF II-11-2 5 V.sub.10 1.3 2IPGUQUF II-13-1 5 t.sub.30 C. >500 h 3PUQUF II-5-2 6 VHR (initial) 97 3CCQUF II-1-2 6 VHR (UV) 94 4DUQUF II-4-3 3 VHR (high 97.5 temperature) 3CC2 IV-1-2 4 13000 2PGUQPOCF.sub.3 I B-2 4 3PGUQPOCF.sub.3 I B-3 4 2PGUQPCF.sub.3 I A-2 4 3PGUQPCF.sub.3 I A-3 5 Total 100

Example 7

(45) The liquid crystal composition of Example 7 was prepared as per the compounds and their respective weight percentages listed in table 10. The liquid crystal composition was injected between the liquid crystal display substrates and tests were conducted. The test results are as follows:

(46) TABLE-US-00010 TABLE 10 Formulation of liquid crystal composition and performances tested Code of Code of Test result of performance component structure Content, % parameters 3PGP2 III-3-1 3 Cp 92 3PGP4 III-3-3 3 n 0.114 VCCP1 IV-3-1 12 8.5 3CCV IV-1-12 35 12 3C(5)CCQUF II-6-3 4 V.sub.10 1.27 3C(O)PUQUF II-7-3 4 t.sub.30 C. >500 h 3PUQUF II-5-2 8 VHR (initial) 96.5 3CCQUF II-1-2 7 VHR (UV) 93.5 4DUQUF II-4-3 4 VHR (high 97 temperature) 3CC2 IV-1-2 5 15000 2PGUQPOCF.sub.3 I B-2 5 3PGUQPOCF.sub.3 I B-3 3 2PGUQPCF.sub.3 I A-2 3 3PGUQPCF.sub.3 I A-3 4 Total 100

(47) To achieve the environmental friendliness, the invention forgoes the chlorine monomer for difluoroether monomers which have improved voltage holding ratio relative to ordinary medium-polarity monomers. As shown by the comparison between the Examples and the Comparative Examples, the inventive liquid crystal composition has a large specific resistance, a high clear point, a suitable optical anisotropy, a suitable dielectric anisotropy, a small viscosity, an improved low temperature storage stability, and is suitable for display device, enabling better voltage holding ratio, better display contrast ratio, fast response, lower power consumption.

(48) The embodiments described above are merely descriptive of the concept and characteristics of the invention such that those skilled in the art may practice the invention, and are not intended to limit the scope of the invention. It is therefore intended that the following claims cover all equivalent modifications and variations as fall within the scope of this invention.