Background
Negative liquid crystals, which were proposed at the beginning of the 80's last century, are mainly used in VA mode, and have major advantages in high contrast and major disadvantages in small viewing angle and slow response time. With the development of display technology, MVA, PVA, PSVA, and the like technologies have appeared in succession, solving the problems of response time and viewing angle. In recent years, as touch panels become mainstream in the market of mobile devices, IPS and FFS type hard-screen displays have inherent advantages, and both IPS and FFS type displays can use positive liquid crystals and negative liquid crystals, and the positive liquid crystals are aligned along the direction of electric field lines due to the bending electric field existing in the displays, thereby causing bending of molecules and lowering of transmittance; the negative liquid crystal is arranged perpendicular to the direction of the electric field lines, so that the transmittance is greatly improved, and the method is the best method for improving the transmittance and reducing the backlight power consumption at present. However, the response time problem of negative liquid crystals is a significant problem that is currently encountered, and FFS displays using negative liquid crystals have a response time that is 50% or more slower than FFS displays using positive liquid crystals. Therefore, how to increase the response time of the negative liquid crystal is a key issue at present.
Specifically, the response time of the liquid crystal display depends on (d ^2 gamma 1)/Keff ((d is the thickness of the liquid crystal layer, gamma 1 is the rotational viscosity of the liquid crystal, and Keff is the effective elastic constant), so that the purposes of improving the response time can be achieved by reducing the rotational viscosity, reducing the thickness of the liquid crystal layer and improving the elastic constant, the thickness of the liquid crystal layer depends on the design of the liquid crystal display, and the reduction of the rotational viscosity and the thickness of the liquid crystal are most effective for the liquid crystal composition.
Disclosure of Invention
Based on the above background, it is an object of the present invention to provide a negative dielectric nematic liquid crystal composition having a low rotational viscosity, which can effectively reduce the response time of a liquid crystal display; the liquid crystal composition comprises at least one or more compounds of a general formula I, one or more compounds of a general formula II, one or more compounds of a general formula III and one or more compounds of a general formula IV;
the general formula I is specifically as follows:
in the general formula I, R1、R2Each independently represents C1~C12Linear alkyl, linear alkoxy or C2~C12A linear alkenyl group of (a);
the general formula II is specifically:
in the general formula II, R3、R4Each independently represents C1~C12Linear alkyl, linear alkoxy or C2~C12A linear alkenyl group of (a);
the general formula III is specifically:
in the general formula III, R5、R6Each independently represents C1~C12Linear alkyl, linear alkoxy or C2~C12A linear alkenyl group of (a);
the general formula IV is specifically:
in the general formula IV, R7、R8Each independently represents C1~C12Straight-chain alkyl groups and straight-chain alkoxy groups.
The compound of the general formula I provided by the invention is a tricyclic compound containing 2, 3-difluorobenzene, and the compound has larger negative dielectric anisotropy and high clearing point.
Preferably, in the general formula I, R1Represents C2~C5The linear alkyl group of (1); r2Represents C1~C4Linear alkyl or linear alkoxy of (a);
specifically, the compound of the general formula I is one or more of structures shown in formulas I-1 to I-20:
more preferably, the compound of the general formula I is one or more of the formulae I-1, I-2, I-9, I-10, I-11, I-13, I-14, I-15, I-16 and I-18;
further preferably, the compound of the general formula I is one or more of the compounds of the formulae I-10, I-13, I-14, I-15, I-16 and I-18.
The compound represented by the general formula II provided by the invention is a liquid crystal compound with two rings containing a methoxy bridge bond and a 2, 3-difluorobenzene structure, and the compound has large negative dielectric anisotropy and excellent intersolubility.
Preferably, in said formula II, R3Represents C2~C5The linear alkyl group of (1); r4Represents C1~C4Linear alkyl or linear alkoxy of (a);
specifically, the compound of the general formula II is one or more of structures shown in formulas II-1 to II-16:
more preferably, the compound represented by the general formula II is selected from one or more of the formulas II-2, II-6, II-8 and II-14;
further preferably, the compound represented by the general formula II is selected from one or two of the compounds represented by the formulas II-2 and II-6.
The compound of the general formula III provided by the invention is a biphenyl compound containing 2, 3-difluorobenzene in a tricyclic way, and the compound has larger optical anisotropy, larger negative dielectric anisotropy and high clearing point.
Preferably, in said formula III, R5Represents C2~C5The linear alkyl group of (1); r6Represents C1~C4Linear alkyl or linear alkoxy of (a);
specifically, the compound of the general formula III is one or more of structures shown in formulas III-1 to III-24:
more preferably, the compound of formula III is one or more of III-1, III-2, III-13, III-14, III-18, III-22;
further preferably, the compound of formula III is one or both of formulae III-13, III-14.
The compound of the general formula IV provided by the invention is a two-ring neutral monomer, has very low rotational viscosity and excellent intersolubility, can effectively reduce the rotational viscosity of a liquid crystal composition, and improves the response time.
In the general formula IV, R7Represents C2~C5The linear alkyl group of (1); r8Represents C1~C5Linear alkyl or linear alkoxy of (a);
specifically, the compound of the general formula IV is one or more of structures shown in formulas IV-1 to IV-60:
more preferably, the compound of formula IV is one or more of formulas IV-4, IV-6, IV-10, IV-11, IV-36, IV-40, IV-44, IV-48, IV-50;
further preferably, the compound of formula IV is one or more of the formulae IV-6, IV-10, IV-11, IV-40, IV-44, IV-50.
The liquid crystal composition further comprises one or more compounds of a general formula V, wherein the general formula V is as follows:
in the general formula V, R9Represents C1~C12Linear alkyl, linear alkoxy or C2~C12A linear alkenyl group of (a);
the compound of the general formula V is a dicyclo fluoroethoxyl compound, has large negative dielectric anisotropy and low rotational viscosity, and can improve the negative dielectric anisotropy of the liquid crystal composition.
Preferably, in said formula V, R9Represents C2~C5The linear alkyl group of (1);
specifically, the compound of the general formula V is one or more of structures shown in formulas V-1 to V-4:
more preferably, the compound of formula V is a compound represented by formula V-2 or V-4;
further preferably, the compound of the general formula V is a compound represented by the formula V-2.
The liquid crystal composition further comprises one or more compounds of a general formula VI, wherein the general formula VI is specifically as follows:
in the general formula VI, R10、R11Each independently represents C1~C12The linear alkyl group of (1); a. the3Represents trans-1, 4-cyclohexyl or 1, 4-phenylene;
preferably, in said formula VI, R10Represents C2~C5The linear alkyl group of (1); r11Represents C1~C3The linear alkyl group of (1); a. the3Represents trans-1, 4-cyclohexyl or 1, 4-phenylene;
specifically, the compound of the general formula VI is one or more of the formulas VI-1 to VI-24:
more preferably, the compound of formula VI is one or more of the formulae VI-2, VI-6, VI-10, VI-14, VI-18, VI-20;
further preferably, the compound of formula VI is one or more of the formulae VI-2, VI-6, VI-14, VI-18.
In order to improve the synergistic effect between the various types of compounds, the present invention preferably provides the liquid crystal composition with a percentage of each component.
Specifically, the liquid crystal composition comprises the following components in percentage by weight:
(1) 10-45% of a compound represented by general formula I;
(2) 1-25% of a compound represented by general formula II;
(3)1 to 25% of a compound represented by the general formula III;
(4) 20-60% of a compound represented by formula IV;
(5)0 to 15% of a compound represented by the general formula V;
(6)0 to 25% of a compound represented by the general formula VI;
or, the liquid crystal composition comprises the following components:
(1) 15-40% of a compound represented by formula I;
(2) 2-20% of a compound represented by general formula II;
(3) 3-20% of a compound represented by the general formula III;
(4) 30-55% of a compound represented by formula IV;
(5)0 to 10% of a compound represented by the general formula V;
(6)0 to 20% of a compound represented by the general formula VI;
preferably, the liquid crystal composition comprises the following components:
(1) 19-36% of a compound represented by general formula I;
(2) 3-16% of a compound represented by general formula II;
(3) 4-17% of a compound represented by general formula III;
(4) 40-53% of a compound represented by formula IV;
(5)0 to 6% of a compound represented by the general formula V;
(6)0 to 15% of a compound represented by the general formula VI;
or, the liquid crystal composition comprises the following components:
(1) 15-40% of a compound represented by formula I;
(2) 2-20% of a compound represented by general formula II;
(3) 3-20% of a compound represented by the general formula III;
(4) 40-55% of a compound represented by formula IV;
(5)0 to 20% of a compound represented by the general formula VI;
preferably, the liquid crystal composition comprises the following components:
(1) 19-36% of a compound represented by general formula I;
(2) 3-16% of a compound represented by general formula II;
(3) 4-17% of a compound represented by general formula III;
(4) 44-53% of a compound represented by formula IV;
(5)0 to 15% of a compound represented by the general formula VI;
or, the liquid crystal composition comprises the following components:
(1) 20-40% of a compound represented by general formula I;
(2) 5-16% of a compound represented by general formula II;
(3) 5-16% of a compound represented by the general formula III;
(4) 35-55% of a compound represented by formula IV;
(5) 1-10% of a compound represented by formula V;
(6)0 to 20% of a compound represented by the general formula VI;
preferably, the liquid crystal composition comprises the following components:
(1) 22-36% of a compound represented by general formula I;
(2) 6-13% of a compound represented by general formula II;
(3) 7-13% of a compound represented by formula III;
(4) 40-52% of a compound represented by formula IV;
(5) 2-6% of a compound represented by formula V;
(6)0 to 15% of a compound represented by the general formula VI;
or, the liquid crystal composition comprises the following components:
(1) 20-40% of a compound represented by general formula I;
(2) 2-20% of a compound represented by general formula II;
(3) 3-20% of a compound represented by the general formula III;
(4) 35-55% of a compound represented by formula IV;
(5)0 to 10% of a compound represented by the general formula V;
preferably, the liquid crystal composition comprises the following components:
(1) 27-36% of a compound represented by formula I;
(2) 3-16% of a compound represented by general formula II;
(3) 4-17% of a compound represented by general formula III;
(4) 40-53% of a compound represented by formula IV;
(5)0 to 6% of a compound represented by the general formula V;
or, the liquid crystal composition comprises the following components:
(1) 15-36% of a compound represented by general formula I;
(2) 5-16% of a compound represented by general formula II;
(3) 3-16% of a compound represented by the general formula III;
(4) 35-53% of a compound represented by formula IV;
(5)0 to 5% of a compound represented by the general formula V;
(6) 1-20% of a compound represented by formula VI;
preferably, the liquid crystal composition comprises the following components:
(1) 19-32% of a compound represented by general formula I;
(2) 8-14% of a compound represented by general formula II;
(3) 5-11% of a compound represented by the general formula III;
(4) 40-48% of a compound represented by formula IV;
(5)0 to 3% of a compound represented by the general formula V;
(6) 5-15% of a compound represented by formula VI;
or, the liquid crystal composition provided by the invention is composed of the following compounds:
(1) 25-40% of a compound represented by formula I;
(2) 2-20% of a compound represented by general formula II;
(3) 3-20% of a compound represented by the general formula III;
(4) 40-55% of a compound represented by formula IV;
preferably, the liquid crystal composition provided by the invention consists of the following compounds:
(1) 28-36% of a compound represented by general formula I;
(2) 3-16% of a compound represented by general formula II;
(3) 4-17% of a compound represented by general formula III;
(4) 44-53% of a compound represented by formula IV;
or, the liquid crystal composition provided by the invention is composed of the following compounds:
(1) 25-40% of a compound represented by formula I;
(2) 5-16% of a compound represented by general formula II;
(3) 5-16% of a compound represented by the general formula III;
(4) 35-55% of a compound represented by formula IV;
(5) 1-10% of a compound represented by formula V;
preferably, the liquid crystal composition provided by the invention consists of the following compounds:
(1) 27-36% of a compound represented by formula I;
(2) 6-13% of a compound represented by general formula II;
(3) 7-13% of a compound represented by formula III;
(4) 40-52% of a compound represented by formula IV;
(5) 2-6% of a compound represented by formula V;
or, the liquid crystal composition provided by the invention is composed of the following compounds:
(1) 15-36% of a compound represented by general formula I;
(2) 5-16% of a compound represented by general formula II;
(3) 3-16% of a compound represented by the general formula III;
(4) 35-53% of a compound represented by formula IV;
(5)0 to 5% of a compound represented by the general formula V;
(6) 1-20% of a compound represented by formula VI;
preferably, the liquid crystal composition provided by the invention consists of the following compounds:
(1) 19-32% of a compound represented by general formula I;
(2) 8-14% of a compound represented by general formula II;
(3) 5-11% of a compound represented by the general formula III;
(4) 40-48% of a compound represented by formula IV;
(5)0 to 3% of a compound represented by the general formula V;
(6) 5-15% of a compound represented by the general formula VI.
As a preferable scheme of the invention, the liquid crystal composition comprises the following components in percentage by weight:
(1) 19-36% of a compound represented by general formula I;
(2) 3-15.5% of a compound represented by general formula II;
(3) 4-16.5% of a compound represented by the general formula III;
(4)32.5 to 52.5% of a compound represented by the general formula IV;
(5)0 to 6% of a compound represented by the general formula V;
(6)0 to 15% of a compound represented by the general formula VI;
preferably, the liquid crystal composition comprises the following components in percentage by weight:
(1) 28-36% of a compound represented by general formula I;
(2) 3-15.5% of a compound represented by general formula II;
(3) 4-16.5% of a compound represented by the general formula III;
(4)32.5 to 52.5% of a compound represented by the general formula IV;
or, the liquid crystal composition comprises the following components in percentage by weight:
(1) 27-36% of a compound represented by formula I;
(2)6.5 to 12.5% of a compound represented by the general formula II;
(3) 7-13% of a compound represented by formula III;
(4)40.5 to 51.5% of a compound represented by the general formula IV;
(5) 2-6% of a compound represented by formula V;
or, the liquid crystal composition comprises the following components in percentage by weight:
(1) 19-27% of a compound represented by formula I;
(2)11.5 to 14% of a compound represented by the general formula II;
(3) 5-8% of a compound represented by the general formula III;
(4) 44.5-47% of a compound represented by formula IV;
(5) 7-15% of a compound represented by formula VI;
or, the liquid crystal composition comprises the following components in percentage by weight:
(1) 22-32% of a compound represented by general formula I;
(2)8.5 to 12.5% of a compound represented by the general formula II;
(3) 7-11% of a compound represented by the general formula III;
(4) 40.5-46.5% of a compound represented by formula IV;
(5) 2-3% of a compound represented by formula V;
(6)5 to 10% of a compound represented by the general formula VI
More preferably, the sum of the compound represented by the general formula II and the compound represented by the general formula III is not more than 20% by weight of the liquid crystal composition;
further preferably, the compound represented by the general formula IV at least comprises a compound represented by IV-50.
The method for preparing the liquid crystal composition of the present invention is not particularly limited, and two or more compounds may be mixed and produced by a conventional method. For example, the liquid crystal composition is prepared by mixing the respective component compounds under high temperature conditions and dissolving them with each other; or dissolving the respective component compounds in a solvent for the compounds, and mixing, and then distilling off the solvent under reduced pressure; or dissolving a component compound with a smaller content in a main component compound with a larger content at a higher temperature; or dissolving the components in organic solvent, mixing the solutions, and removing solvent to obtain liquid crystal composition.
The liquid crystal composition provided by the invention has low rotational viscosity, high Voltage Holding Ratio (VHR), good low-temperature intersolubility and quick response time, is suitable for VA type liquid crystal display devices such as VA/MVA/PVA/PSVA and the like and IPS and FFS mode liquid crystal display devices, and is particularly suitable for MVA/PVA/PSVA mode liquid crystal displays.
Detailed Description
The following examples are intended to illustrate the invention but are not intended to limit the scope of the invention.
Unless otherwise indicated, percentages in the present invention are weight percentages; the temperature units are centigrade; Δ n represents optical anisotropy (25 ℃); Δ ε represents the dielectric anisotropy (25 ℃, 1000 Hz); v10Representative threshold voltage is the change in relative transmittance 10% characteristic voltage (V, 25 ℃); γ 1 represents rotational viscosity (mpa.s, 25 ℃); cp represents the clearing point (. degree. C.) of the liquid crystal composition; k11、K22、K33Respectively representing the splay, twist and bend elastic constants (pN, 25 ℃).
In the following examples, the group structures in the liquid crystal compounds are represented by codes shown in Table 1.
Table 1: radical structure code of liquid crystal compound
Take the following compound structure as an example:
expressed as: 3PWO2F
Expressed as: 3PGIWO2
In the following examples, the liquid crystal composition was prepared by a thermal dissolution method, comprising the steps of: weighing the liquid crystal compound by a balance according to the weight percentage, wherein the weighing and adding sequence has no specific requirements, generally weighing and mixing the liquid crystal compound in sequence from high melting point to low melting point, heating and stirring at 60-100 ℃ to uniformly melt all the components, filtering, performing rotary evaporation, and finally packaging to obtain the target sample.
In the following examples, the weight percentages of the components in the liquid crystal composition and the performance parameters of the liquid crystal composition are shown in the following tables.
Example 1
Table 2: the weight percentage and performance parameters of each component in the liquid crystal composition
Example 2
Table 3: the weight percentage and performance parameters of each component in the liquid crystal composition
Example 3
Table 4: the weight percentage and performance parameters of each component in the liquid crystal composition
Example 4
Table 5: the weight percentage and performance parameters of each component in the liquid crystal composition
Example 5
Table 6: the weight percentage and performance parameters of each component in the liquid crystal composition
Example 6
Table 7: the weight percentage and performance parameters of each component in the liquid crystal composition
Example 7
Table 8: the weight percentage and performance parameters of each component in the liquid crystal composition
Example 8
Table 9: the weight percentage and performance parameters of each component in the liquid crystal composition
Example 9
Table 10: the weight percentage and performance parameters of each component in the liquid crystal composition
Example 10
Table 11: the weight percentage and performance parameters of each component in the liquid crystal composition
Example 11
Table 12: the weight percentage and performance parameters of each component in the liquid crystal composition
Example 12
Table 13: the weight percentage and performance parameters of each component in the liquid crystal composition
Example 13
Table 14: the weight percentage and performance parameters of each component in the liquid crystal composition
Example 14
Table 15: the weight percentage and performance parameters of each component in the liquid crystal composition
Example 15
Table 16: the weight percentage and performance parameters of each component in the liquid crystal composition
Example 16
Table 17: the weight percentage and performance parameters of each component in the liquid crystal composition
Example 17
Table 18: the weight percentage and performance parameters of each component in the liquid crystal composition
Example 18
Table 19: the weight percentage and performance parameters of each component in the liquid crystal composition
Example 19
Table 20: the weight percentage and performance parameters of each component in the liquid crystal composition
Example 20
Table 21: the weight percentage and performance parameters of each component in the liquid crystal composition
Example 21
Table 22: the weight percentage and performance parameters of each component in the liquid crystal composition
Example 22
Table 23: the weight percentage and performance parameters of each component in the liquid crystal composition
Example 23
Table 24: the weight percentage and performance parameters of each component in the liquid crystal composition
Example 24
Table 25: the weight percentage and performance parameters of each component in the liquid crystal composition
Example 25
Table 26: the weight percentage and performance parameters of each component in the liquid crystal composition
Example 26
Table 27: the weight percentage and performance parameters of each component in the liquid crystal composition
Example 27
Table 28: the weight percentage and performance parameters of each component in the liquid crystal composition
Example 28
Table 29: the weight percentage and performance parameters of each component in the liquid crystal composition
Example 29
Table 30: the weight percentage and performance parameters of each component in the liquid crystal composition
Comparative example 1
Table 31: the weight percentage and performance parameters of each component in the liquid crystal composition
The liquid crystal compositions obtained in example 1 and comparative example 1 were compared together for each of their performance parameter values, see table 32.
Table 32: comparison of Performance parameters of liquid Crystal compositions
|
△n
|
△ε
|
Cp
|
γ1
|
K11 |
K22 |
K33 |
Example 1
|
0.100
|
-3.1
|
75
|
83
|
14.6
|
7.3
|
14.6
|
Comparative example 1
|
0.100
|
-3.3
|
76
|
95
|
14.4
|
7.2
|
15.5 |
By comparison, it can be seen that: example 1 provides a liquid crystal composition having a low viscosity as compared to comparative example 1
I.e. with a faster response time.
Example 1 and comparative example 1 were compared at 60 ℃ to test VHR (Voltage holding ratio) and
the test results are as follows:
|
example 1
|
Comparative example 1
|
VHR(initial)
|
84.4%
|
81.2%
|
VHR(After UV)
|
78.6%
|
74.3% |
UV conditions: 365nm, 10j/cm2
VHR test conditions: 1V, 0.5Hz
From the above embodiments, the liquid crystal composition provided by the present invention has low viscosity, high voltage holding ratio, suitable optical anisotropy, good low-temperature intersolubility, large elastic constant, and excellent light stability and thermal stability, and can reduce the response time of the liquid crystal display, thereby solving the problem of slow response speed of the liquid crystal display. Therefore, the liquid crystal composition provided by the invention is suitable for VA display modes such as VA/MVA/PVA/PSVA and the like and IPS and FFS type TFT liquid crystal display devices; particularly, it is suitable for liquid crystal display devices such as MVA, PVA and PSVA.
Although the invention has been described in detail hereinabove by way of general description, specific embodiments and experiments, it will be apparent to those skilled in the art that many modifications and improvements can be made thereto based on the invention. Accordingly, such modifications and improvements are intended to be within the scope of the invention as claimed.