Liquid crystal compounds, compositions containing trifluoromethyl groups on the side chain and their applications

Abstract

The present invention belongs to the field of liquid crystal materials, and relates to a liquid crystal compound, a preparation method thereof and an application thereof. The chemical structural formula of the liquid crystal compound is shown as General Formula I: The liquid crystal compound provided by the present invention and the liquid crystal composition containing the liquid crystal compound of the present invention have large dielectric properties, high reliability and can effectively improve afterimage, and are applicable to displays in VA, FFS or IPS modes.

Description

Technical Field

[0001] The present invention belongs to the field of liquid crystal materials, and particularly relates to a liquid crystal compound containing a side trifluoromethyl group, a liquid crystal composition and their applications. Background Art

[0002] In recent years, with the continuous progress and development of science and technology, liquid crystal display technology (Liquid Crystal Display, LCD) has attracted great attention. Compared with traditional display technologies, TFT-LCD liquid crystal displays not only have many advantages such as small size, light weight, low power consumption, and easy driving, but also can effectively compensate for the disadvantages of traditional display technologies, and are widely used in various consumer electronic products such as mobile phones, TVs, digital cameras, notebooks, and desktop computers.

[0003] New liquid crystal display modes mainly include optically compensated bend mode (OCB), in-plane switching liquid crystal display (IPS), vertical alignment mode (VA), axially symmetric microstructured liquid crystal display (ASM), multi-domain twisted liquid crystal display, etc.

[0004] From the perspective of the preparation of liquid crystal composition materials for liquid crystal displays, the various properties of the materials affect each other, and improving some properties often comes with changes in other properties. According to the positive or negative of the dielectric anisotropy, liquid crystals can be divided into positive dielectric anisotropy liquid crystals and negative dielectric anisotropy liquid crystals. Negative dielectric anisotropy liquid crystals are widely used and have become one of the current research hotspots. On the one hand, to increase the negative dielectric anisotropy, a large amount of large-polarity monomers are usually used, which is more likely to cause ion aggregation and more likely to produce afterimages after backlight burning. However, in addition to considering the negative dielectric anisotropy of liquid crystal compounds, high-definition bright spots, large polarity, low viscosity, good high-temperature resistance, and ultraviolet resistance are also important properties of liquid crystals. To reduce the delay of the display screen, the liquid crystal composition is required to have a high response speed.

[0005] Therefore, developing liquid crystal compounds and liquid crystal compositions with large dielectric anisotropy, good reliability, while maintaining good rotational viscosity and effectively improving afterimages is an urgent problem to be solved in this field. Summary of the Invention

[0006] The liquid crystal compound of the present invention has large dielectric anisotropy, good reliability, while maintaining good rotational viscosity and can effectively improve afterimages. The liquid crystal composition containing the liquid crystal compound of the present invention has large negative dielectric anisotropy, good reliability, small rotational viscosity and can effectively improve afterimages, and can be used to develop low-drive and high-reliability liquid crystal display elements or liquid crystal displays.

[0007] Specifically, the present invention provides the following technical solutions:

[0008] On the one hand, the present invention provides a novel liquid crystal compound, and the liquid crystal compound is shown as Formula I,

[0009]

[0010] wherein, R a and R b each independently represent an alkyl group having 1 to 10 carbon atoms, a halogen-substituted alkyl group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, a halogen-substituted alkoxy group having 1 to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, a halogen-substituted alkenyl group having 2 to 10 carbon atoms, an alkenyloxy group having 3 to 8 carbon atoms or a fluorine-substituted alkenyloxy group having 3 to 8 carbon atoms, and any one or more non-connected -CH2- in the groups represented by R a and R b can be independently substituted by a cyclopentylene group, a cyclobutylene group or a cyclopropylene group;

[0011] n1 and n2 each independently represent 1, 2, 3 or 4.

[0012] On the other hand, the present invention relates to a liquid crystal composition, and the liquid crystal composition contains one or more liquid crystal compounds of the present invention.

[0013] On still another aspect, the present invention relates to a liquid crystal display element or a liquid crystal display, which contains the liquid crystal composition of the present invention, and the liquid crystal display element or the liquid crystal display is an active matrix display element or a display.

[0014] Advantages of the Invention

[0015] After adding a fluoroalkyl group to the side position of the liquid crystal compound of the present invention, the polarization force of the liquid crystal molecules in the vertical direction becomes greater, the vertical dielectric increases, and the negative dielectric increases; moreover, after adding the side-position fluoroalkyl group, the solubility of the molecules is improved, and at the same time, the -C-F bond energy is larger than that of the -CN group, the reliability is relatively better, and the display defect caused by afterimages can be effectively improved. The liquid crystal compound of the present invention has a high negative dielectric anisotropy, good reliability and can also effectively improve the display defect caused by afterimages. The liquid crystal composition containing the liquid crystal compound of the present invention has a high negative dielectric anisotropy, good reliability and can also effectively improve the display defect caused by afterimages, and can be used to develop a liquid crystal display element or a liquid crystal display with low drive and high reliability. Description of the Drawings

[0016] Figure 1 The MS mass spectrum of the compound shown in Formula I-1-2 is shown. Detailed Embodiments

[0017] [Liquid Crystal Compound]

[0018] In the first aspect of the present invention, a liquid crystal compound is provided as shown in Formula I:

[0019]

[0020] Wherein, R a and R b each independently represent an alkyl group having 1 to 10 carbon atoms, a halogen-substituted alkyl group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, a halogen-substituted alkoxy group having 1 to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, a halogen-substituted alkenyl group having 2 to 10 carbon atoms, an alkenyloxy group having 3 to 8 carbon atoms or a fluorine-substituted alkenyloxy group having 3 to 8 carbon atoms, and any one or more non-connected -CH2- in the groups represented by R a and R b can be independently substituted by a cyclopentylene group, a cyclobutylene group or a cyclopropylene group;

[0021] n1 and n2 each independently represent 1, 2, 3 or 4.

[0022] The liquid crystal compound of the present invention has high negative dielectric anisotropy and good reliability, and can also effectively improve the display defect caused by image sticking.

[0023] In the liquid crystal compound of the present invention, preferably, the compound shown in Formula I is selected from the group consisting of compounds shown in the following Formulas I-1 to I-6:

[0024]

[0025] Wherein, R a1 , R b1 each independently represent an alkyl group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms or an alkenyl group having 2 to 10 carbon atoms.

[0026] In the liquid crystal compound of the present invention, more preferably, the compounds shown in Formulas I-1 to I-6 of the liquid crystal compound are selected from the group consisting of compounds shown in the following Formulas I-1-1 to I-6-8,

[0027]

[0028]

[0029]

[0030] [Liquid Crystal Composition]

[0031] In the second aspect of the present invention, a liquid crystal composition is provided, and the liquid crystal composition contains one or more of the liquid crystal compounds of the present invention.

[0032] The liquid crystal composition of the present invention, preferably, the aforementioned liquid crystal composition further comprises one or more compounds represented by Formula II,

[0033]

[0034] wherein,

[0035] R1 and R2 each independently represent an alkyl group having 1 to 10 carbon atoms or an alkenyl group having 2 to 10 carbon atoms.

[0036] The liquid crystal composition of the present invention, preferably, the compound represented by the aforementioned Formula II is selected from the group consisting of compounds represented by the following Formula II-1 to II-10,

[0037]

[0038] The liquid crystal composition of the present invention, preferably, the aforementioned liquid crystal composition further comprises one or more compounds represented by Formula III,

[0039]

[0040] wherein,

[0041] R3 and R4 each independently represent an alkyl group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms or an alkenyl group having 2 to 10 carbon atoms;

[0042] represents 1,4-phenylene or 1,4-cyclohexylene.

[0043] The liquid crystal composition of the present invention, preferably, the compound represented by the aforementioned Formula III is selected from the group consisting of compounds represented by the following Formula III-1 to III-6,

[0044]

[0045] The liquid crystal composition of the present invention, preferably, the aforementioned liquid crystal composition further comprises one or more compounds represented by Formula IV,

[0046]

[0047] wherein,

[0048] R5 and R6 each independently represent an alkyl group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms or an alkenyl group having 2 to 10 carbon atoms;

[0049] represents 1,4-phenylene, 1,4-cyclohexylene or 1,4-cyclohexenylene;

[0050] m represents 1 or 2;

[0051] n represents 0 or 1.

[0052] For the liquid crystal composition of the present invention, preferably, the compound represented by the foregoing formula IV is selected from the group consisting of the compounds represented by the following formulas IV-1 to IV-7,

[0053]

[0054] wherein,

[0055] R5 and R6 each independently represent an alkyl group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, or an alkenyl group having 2 to 10 carbon atoms.

[0056] For the liquid crystal composition of the present invention, preferably, the foregoing liquid crystal composition further comprises one or more compounds represented by formula V,

[0057]

[0058] wherein,

[0059] R7 and R8 each independently represent an alkyl group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, or an alkenyl group having 2 to 10 carbon atoms;

[0060] represents 1,4-phenylene or 1,4-cyclohexylene.

[0061] For the liquid crystal composition of the present invention, preferably, the compound represented by the foregoing formula V is selected from the group consisting of the compounds represented by the following formulas V-1 to V-5,

[0062]

[0063] For the liquid crystal composition of the present invention, preferably, the foregoing liquid crystal composition further comprises one or more compounds represented by formula VI,

[0064]

[0065] wherein,

[0066] R9, R 10 each independently represent an alkoxy group having 1 to 10 carbon atoms or

[0067] For the liquid crystal composition of the present invention, preferably, the compound represented by the foregoing formula VI is selected from the group consisting of the compounds represented by the following formulas VI-1 to VI-5,

[0068]

[0069] [Liquid crystal display element or liquid crystal display]

[0070] The present invention also provides a liquid crystal display element or a liquid crystal display device comprising the above liquid crystal composition.

[0071] Preferably, the aforementioned liquid crystal display element may be an active matrix addressed liquid crystal display element or a passive matrix display element; the liquid crystal display device may be an active matrix addressed liquid crystal display or a passive matrix display.

[0072] Preferably, the active matrix addressed liquid crystal display element is a VA-TFT, FFS-TFT or IPS-TFT liquid crystal display element.

[0073] The liquid crystal display element or the liquid crystal display device of the present invention comprises the liquid crystal compound and the liquid crystal composition of the present invention, and can be used for developing a liquid crystal display element or a liquid crystal display device with low drive and high reliability.

[0074] Examples

[0075] To illustrate the present invention more clearly, the present invention will be further described below in conjunction with preferred embodiments. Those skilled in the art should understand that the content specifically described below is illustrative rather than restrictive, and should not be used to limit the protection scope of the present invention.

[0076] In this specification, unless otherwise specified, percentages are all by mass percentage, temperature is in degrees Celsius (°C), and the specific meanings and test conditions of other symbols are as follows:

[0077] Cp represents the liquid crystal clearing point (°C), tested by DSC quantitative method;

[0078] Δn represents the optical anisotropy, n o is the refractive index of the ordinary light, n e is the refractive index of the extraordinary light, the test conditions are 25 ± 2 °C, 589 nm, tested by an Abbe refractometer;

[0079] Δε represents the dielectric anisotropy, Δε = ε ∥ -ε ⊥ where ε ∥ is the dielectric constant parallel to the molecular axis, ε ⊥ is the dielectric constant perpendicular to the molecular axis, the test conditions are 25 ± 0.5 °C, 20 μm vertical cell, tested by INSTEC: ALCT-IR1;

[0080] γ1 represents the rotational viscosity (mPa·s), the test conditions are 25 ± 0.5 °C, 20 μm vertical cell, tested by INSTEC: ALCT-IR1;

[0081] K 11 is the splay elastic constant, K 33is the flexural elastic constant, and the test conditions are: 25 °C, INSTEC: ALCT-IR1, 20-μm vertical cell;

[0082] VHR represents the voltage holding ratio (%), and the test conditions are 60 ± 2 °C, voltage of ±5 V, pulse width of 10 ms, and voltage holding time of 16.7 ms. The test equipment is a TOYO Model6254 comprehensive liquid crystal performance tester;

[0083] Afterimage: The afterimage of a liquid crystal display device is evaluated in the following four grades by visual inspection of the residual level of the inherent pattern during full-screen uniform display after displaying a specified fixed pattern in the display area for 1000 hours:

[0084] ◎ No residue

[0085] ○ There is a very small amount of residue, which is an acceptable level

[0086] △ There is residue, which is an unacceptable level

[0087] × There is residue, which is quite poor

[0088] The preparation method of the liquid crystal composition is as follows: Weigh each liquid crystal monomer according to a certain ratio and put it into a stainless steel beaker. Place the stainless steel beaker containing each liquid crystal monomer on a magnetic stirring instrument to heat and melt. After most of the liquid crystal monomers in the stainless steel beaker have melted, add a magnetic rotor to the stainless steel beaker, stir the mixture evenly, and cool it to room temperature to obtain the liquid crystal composition.

[0089] In the embodiments of the present invention, the structures of liquid crystal monomers are represented by codes. The coding methods for liquid crystal ring structures, end groups, and linking groups are shown in Table 1 and Table 2 below.

[0090] Table 1 Corresponding codes for ring structures

[0091]

[0092] Table 2 Corresponding codes for end groups and linking groups

[0093]

[0094]

[0095] For example:

[0096] Its code is CC-Cp-V1;

[0097] Its code is CPY-2-O2;

[0098] Its code is CCY-3-O2;

[0099] Its code is COY-3-O2;

[0100] Its code is CCOY-3-O2;

[0101] Its code is Sb-CpO-O4;

[0102] Its code is Sc-CpO-O4;

[0103] Its code is DOY-3-O1;

[0104] Its code is DOY-3-O2;

[0105] Its code is CDOY-3-O1;

[0106] Its code is CDOY-3-O3;

[0107] Its code is D2OY-3-O2; the compound represented by formula I of the present invention can be synthesized according to the following scheme:

[0108] Route 1:

[0109]

[0110] Route 2:

[0111]

[0112] in,

[0113] Among them, R a and R b Each independently represents an alkyl group having 1 to 10 carbon atoms, a halogen-substituted alkyl group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, a halogen-substituted alkoxy group having 1 to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, a halogen-substituted alkenyl group having 2 to 10 carbon atoms, an alkenyloxy group having 3 to 8 carbon atoms, or a fluorine-substituted alkenyloxy group having 3 to 8 carbon atoms, and said R a and R b Any one or more unconnected -CH2- in the groups shown may be independently substituted by cyclopentylene, cyclobutylene or cyclopropylene;

[0114] n represents 1, 2, 3, or 4.

[0115] The raw materials and reagents in the synthesis formula can all be obtained through conventional synthesis or commercial channels. The principles, operation processes, conventional post-treatments, silica gel column chromatography, recrystallization purification and other means of such methods are well-known to synthetic personnel in this field and can fully achieve the synthesis process to obtain the target product.

[0116] The reactions of all steps of the above-mentioned all methods are carried out in a solvent; the solvents are all selected from at least one of tetrahydrofuran, N,N-dimethylformamide, ethanol, methanol, dichloromethane, acetone, toluene and deionized water.

[0117] Compound examples

[0118] Synthesis example 1

[0119] The chemical structure of the compound is shown as the following formula I-1-2:

[0120]

[0121] Its preparation route is as follows:

[0122]

[0123] The specific operation process of the preparation:

[0124] Intermediate 1

[0125] Under nitrogen protection, 0.2 mol of 4-trifluoromethylpropylcyclohexane was put into a 1 L three-necked flask, the nitrogen was replaced, 400 ml of THF was added, the temperature was lowered to -75 °C, LDA was added dropwise, after the addition, the temperature was controlled and stirred for 0.5 h, then the temperature was controlled at -75 °C and 0.22 mol of DMF was added dropwise, stirred for 0.5 h, naturally raised to room temperature, 2 M dilute hydrochloric acid was added dropwise to adjust the pH to about 3, 500 ml of EA was added, liquid separation was carried out, the aqueous phase was extracted with 500 ml of EA, the organic phases were combined, washed twice with water, washed once with saturated brine, dried with anhydrous sodium sulfate, concentrated under reduced pressure to remove the solvent, dissolved in hot ethanol, and recrystallized at low temperature to obtain a white solid of Compound 1. GC: 96%, yield Y = 65%.

[0126] Intermediate 2

[0127] Under nitrogen protection, 0.11 mol of lithium aluminum hydride and THF were put into a 1 L three-necked flask, the temperature was lowered to 0 °C, 0.1 mol of Intermediate 1 was dissolved in THF, and slowly added dropwise into the reaction flask, and reacted at room temperature for 0.5 hours. After the reaction was completed, the temperature was lowered, and it was poured into ice water while stirring, 500 ml of EA was added, the organic phase was adjusted to weak acid in terms of pH, washed once with saturated brine, dried and evaporated to dryness, and directly put into the next step, HPLC: 95%, yield Y = 90%.

[0128] Intermediate 3

[0129] Add 0.08 mol of compound 2, 0.12 mol of p-toluenesulfonyl chloride, 0.12 mol of triethylamine and 0.3 L of DCM into a 1 L three-necked flask, displace with N₂ three times, and react at 50 °C for 6 hours. After the reaction is completed, wash the system three times with water, once with saturated brine, dry, concentrate under reduced pressure to remove the solvent, dissolve in hot ethanol, and perform recrystallization by freezing to obtain compound 3, HPLC: 98%, yield Y = 75%.

[0130] Compound I-1-2

[0131] Charge 0.02 mol of 3, 0.022 mol of 4-methyl-2,3-difluorophenol, and 0.025 mol of anhydrous potassium carbonate into a 500 ml three-necked flask. Use DMF as the solvent and react at 120 °C for 3 hours under N₂ protection. After the reaction is completed, add water for liquid separation, extract the aqueous phase with EA, combine the organic phases, wash three times with water, once with saturated brine, dry with anhydrous sodium sulfate, filter, concentrate the filtrate, dissolve in 5 times of toluene at 45 °C, pass through a 30 g silica gel column, wash the column with 3 times of toluene, concentrate, dissolve in 3 times of toluene and 3 times of ethanol by heating, freeze in a -20 °C refrigerator for 4 h, filter by suction, and perform recrystallization three times more by the same method, then air dry to obtain the white solid compound I-1-2, HPLC: 99.9%, yield Y = 54%.

[0132] △n: 0.0462; △ε: -21.4; γ1: 545 mPa·s; Cp: -70.3 °C

[0133] Synthesis Example 2

[0134] The structural formula of the compound is shown as formula I-3-2 below:

[0135]

[0136] Its preparation route is as follows:

[0137]

[0138] The specific operation process of the preparation:

[0139] Intermediate 4

[0140] Under N₂ protection, charge 0.2 mol of 4-methyl-2,3-difluorophenol, 0.25 mol of bromopropanol, and 0.3 mol of triphenylphosphine into a 1 L three-necked flask, displace with nitrogen, add 400 ml of THF, cool down to 0 °C, and dropwise add 0.3 mol of DIAD. After the dropping is completed, stir at room temperature for 2 h. After the reaction is completed, pour the system into water, perform liquid separation, extract the aqueous phase with EA twice, dry the organic phase, concentrate and spin dry, perform recrystallization twice with toluene and ethanol, filter by suction to obtain the white solid of compound 4. GC: 96%, yield Y = 62%.

[0141] Compound I-3-2

[0142] Under nitrogen, 0.05 mol of 4-trifluoromethylpropylcyclohexane was added to a 500 ml three-necked flask. The nitrogen atmosphere was replaced, 200 ml of THF was added, and the temperature was lowered to -75°C. LDA was added dropwise. After addition, the mixture was stirred for 0.5 h. 0.06 mol of intermediate 4 was added dropwise at -75°C again. The mixture was stirred for 0.5 h and allowed to warm to room temperature. 2 M dilute hydrochloric acid was added dropwise to adjust the pH to approximately 3. 300 ml of EA was added, and the layers were separated. The aqueous phase was extracted with 300 ml of EA. The organic phases were combined, washed twice with water and once with saturated brine, dried over anhydrous sodium sulfate, concentrated under reduced pressure to remove the solvent, dissolved in ethanol, and recrystallized at low temperature to obtain compound 1 as a white solid. GC: 99%, yield Y = 55%.

[0143] △n: 0.0433; △ε: -18.2; γ1: 3650mPa.s; Cp: -55.5℃

[0144] Synthesis example 3

[0145] The structural formula of the compound is shown in Formula 1-4-2 below:

[0146]

[0147] The preparation route is as follows:

[0148]

[0149] Specific operation process of preparation:

[0150] Intermediate 1

[0151] Using 4'-trifluoromethyl-4-propylbicyclohexane as raw material, intermediate 1 was synthesized in reference to Example 1.

[0152] Intermediate 2

[0153] Reference Example 1 Synthesis of Intermediate 2

[0154] Intermediate 3

[0155] Reference Example 1 Synthesis of Intermediate 4

[0156] Compound I-4-2

[0157] Reference Example 1 Synthesis of Compound I-4-2

[0158] △n: 0.0786; △ε: -24.4; γ1: 1650mPa.s; Cp: 95.5℃

[0159] Comparative compounds:

[0160]

[0161] Composition Examples

[0162] Example 1

[0163] The formulation of the liquid crystal composition and the corresponding properties are shown in Table 3 below.

[0164] Table 3 Formulation and Corresponding Properties of the Liquid Crystal Composition in Example 1

[0165]

[0166] Comparative Example 1

[0167] The formulation of the liquid crystal composition and the corresponding properties are shown in Table 4 below.

[0168] Table 4 Formulation and Corresponding Properties of the Liquid Crystal Composition in Comparative Example 1

[0169]

[0170]

[0171] Comparative Example 2

[0172] Replace DOY-3-O2, CDOY-3-O2, and DOY-3-O1 in Example 1 with Formula D1, D2, and D3 respectively as Comparative Example 2, and the performance parameters are as follows

[0173] The formulation of the liquid crystal composition and the corresponding properties are shown in Table 5 below.

[0174] Table 5 Formulation and Corresponding Properties of the Liquid Crystal Composition in Comparative Example 2

[0175]

[0176]

[0177] Example 2

[0178] The formulation of the liquid crystal composition and the corresponding properties are shown in Table 6 below.

[0179] Table 6 Formulation and Corresponding Properties of the Liquid Crystal Composition in Example 2

[0180]

[0181] Example 3

[0182] The formulation of the liquid crystal composition and the corresponding properties are shown in Table 7 below.

[0183] Table 7 Formulation and Corresponding Properties of the Liquid Crystal Composition in Example 3

[0184]

[0185]

[0186] Example 4

[0187] The formulation of the liquid crystal composition and the corresponding properties are shown in Table 8 below.

[0188] Table 8 Formulation of the liquid crystal composition and the corresponding properties in Example 4

[0189]

[0190] Example 5

[0191] The formulation of the liquid crystal composition and the corresponding properties are shown in Table 9 below.

[0192] Table 9 Formulation of the liquid crystal composition and the corresponding properties in Example 5

[0193]

[0194]

[0195] Example 6

[0196] The formulation of the liquid crystal composition and the corresponding properties are shown in Table 10 below.

[0197] Table 10 Formulation of the liquid crystal composition and the corresponding properties in Example 6

[0198]

[0199] Example 7

[0200] The formulation of the liquid crystal composition and the corresponding properties are shown in Table 11 below.

[0201] Table 1 Formulation of the liquid crystal composition and the corresponding properties in Example 7

[0202]

[0203]

[0204] Comparative Example 3

[0205] The formulation of the liquid crystal composition and the corresponding properties are shown in Table 12 below.

[0206] Table 12 Formulation of the liquid crystal composition and the corresponding properties in Comparative Example 3

[0207]

[0208] Table 13 Afterimage and reliability tests of the liquid crystal composition

[0209]

[0210]

[0211] The reliability of the liquid crystal composition is evaluated through initial and high-temperature aging tests followed by VHR testing. The smaller the change in VHR data of the liquid crystal composition before and after the high-temperature test, the stronger its high-temperature resistance. Therefore, the high-temperature resistance is judged by comparing the differences in VHR data of each embodiment before and after the test. The display temperature range of the liquid crystal composition is determined by its clearing point and low-temperature storage conditions. The higher the clearing point and the lower the low-temperature storage temperature of the liquid crystal composition, the wider the display temperature range.

[0212] In the above experiments, the liquid crystals of the embodiments and the comparative liquid crystals were respectively filled in test pieces for testing. VHR represents the voltage holding ratio (%). The test conditions were 60±1°C, a voltage of ±5V, a pulse width of 10ms, and a voltage holding time of 1.667ms. The test equipment was a TOYO Model6254 comprehensive liquid crystal performance tester. The initial VHR value was the data obtained by testing a test piece without any treatment. The VHR value after high-temperature aging was obtained by testing the test piece filled with liquid crystal after being placed in a high-temperature oven at 100°C for 1 hour. Compared with the comparative example, the change in VHR of the liquid crystal of the embodiment after high-temperature aging was significantly smaller than that of the comparative liquid crystal, indicating that the liquid crystal composition of the present invention has strong high-temperature resistance and thus strong resistance to external environmental damage during operation.

[0213] In summary, the liquid crystal compound of the present invention has a high negative dielectric anisotropy, good reliability, and appropriate optical anisotropy while maintaining good rotational viscosity and can effectively improve afterimages. The liquid crystal composition containing the liquid crystal compound of the present invention has a large negative dielectric anisotropy, good reliability, and appropriate optical anisotropy and can effectively improve afterimages, and can be used to develop low-driving and high-reliability liquid crystal display elements or liquid crystal displays.

[0214] Obviously, the above embodiments of the present invention are merely examples for clearly explaining the present invention and are not limitations on the implementation manners of the present invention. For those of ordinary skill in the art, other different forms of changes or modifications can be made based on the above description. It is impossible to list all the implementation manners here. Any obvious changes or modifications derived from the technical solutions of the present invention still fall within the protection scope of the present invention.

Claims

1. A liquid crystal compound, characterized in that: The structural formula of the liquid crystal compound is shown in Formula I. Among them, R a and R b Each independently represents an alkyl group having 1 to 10 carbon atoms, a halogen-substituted alkyl group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, a halogen-substituted alkoxy group having 1 to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, a halogen-substituted alkenyl group having 2 to 10 carbon atoms, an alkenyloxy group having 3 to 8 carbon atoms, or a fluorine-substituted alkenyloxy group having 3 to 8 carbon atoms, and said R a and R b Any one or more unconnected -CH2- in the groups shown may be independently substituted by cyclopentylene, cyclobutylene or cyclopropylene; n1 and n2 each independently represent 1 or 2.

2. The liquid crystal compound according to claim 1, wherein The structural formula of the compound shown in Formula I is specifically selected from one or more of the following Formulas I-1, I-2, I-4, and I-5. Among them, R a1 、R b1 Each independently represents an alkyl group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, or an alkenyl group having 2 to 10 carbon atoms.

3. The liquid crystal compound according to claim 2, characterized in that The compounds represented by formula I-1, I-2, I-4 and I-5 are selected from the group consisting of compounds represented by formula I-1-1 to I-2-8, I-4-1 to I-5-8 below, 4. A liquid crystal composition, characterized in that The liquid crystal composition comprises one or more liquid crystal compounds according to any one of claims 1 to 3.

5. The liquid crystal composition according to claim 4, characterized in that The liquid crystal composition further comprises one or more compounds represented by formula II, in, R1 and R2 each independently represent an alkyl group having 1 to 10 carbon atoms or an alkenyl group having 2 to 10 carbon atoms.

6. The liquid crystal composition according to claim 5, characterized in that The liquid crystal composition further comprises one or more compounds represented by formula III, in, R3 and R4 each independently represent an alkyl group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, or an alkenyl group having 2 to 10 carbon atoms; represents 1,4-phenylene or 1,4-cyclohexylene.

7. The liquid crystal composition according to claim 6, wherein The liquid crystal composition further comprises one or more compounds represented by formula IV, in, R5 and R6 each independently represent an alkyl group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, or an alkenyl group having 2 to 10 carbon atoms; represents 1,4-phenylene, 1,4-cyclohexylene or 1,4-cyclohexenylene; m represents 1 or 2; n represents 0 or 1.

8. The liquid crystal composition according to claim 7, wherein The liquid crystal composition further comprises one or more compounds represented by formula V, in, R7 and R8 each independently represent an alkyl group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, or an alkenyl group having 2 to 10 carbon atoms; represents 1,4-phenylene or 1,4-cyclohexylene.

9. The liquid crystal composition according to claim 8, characterized in that The liquid crystal composition further comprises one or more compounds represented by formula VI, in, R9, R 10 Each independently represents an alkoxy group having 1 to 10 carbon atoms or 10 . A liquid crystal display element or liquid crystal display comprising the liquid crystal composition according to claim 4 , wherein the liquid crystal display element or liquid crystal display is an active matrix display element or display.

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