Liquid Crystal Compound, Liquid Crystal Composition and Liquid Crystal Display Element

Abstract

The present invention belongs to the technical field of liquid crystal display. The present invention discloses a liquid crystal compound: the liquid crystal compound has a large negative dielectric anisotropy, which can reach more than -10, a large optical anisotropy, has good low-temperature miscibility, good reliability, and can effectively improve the afterimage of the liquid crystal composition. The present invention also discloses a liquid crystal composition, a liquid crystal display element, and a liquid crystal display including the liquid crystal compound, which are particularly suitable for small and medium-sized displays.

Description

Technical Field

[0001] The present invention relates to the technical field of liquid crystal displays. More specifically, it relates to a liquid crystal compound, a liquid crystal composition and a liquid crystal display component. Background Art

[0002] In recent years, the technological upgrading of liquid crystal display panels has centered around improving image quality and appearance. Especially in the wave of large-size development, consumers have paid increasing attention to image quality. It is expected that the penetration rates of high-tech added-value products such as 8K and Mini LED-backlit TVs will show stable growth. In terms of improving image quality, one of the most important directions is to increase the resolution. Currently, 4K has been popularized, and 8K has become a hot topic in the industry. The launch of 8K products is expected to accelerate the improvement of the product structure and enhance profitability, and panel manufacturers are actively planning 8K products.

[0003] For the liquid crystal materials used in 8K display devices, the requirements are as follows: ① High transmittance: The liquid crystal material has a large negative dielectric anisotropy and a high retardation amount (Δnd) to make up for the reduction in aperture ratio caused by high resolution, thereby compensating for the defect of reduced transmittance; ② High reliability: The liquid crystal material has a high voltage holding ratio, especially still has a high voltage holding ratio after high temperature, ultraviolet light (UV light) and long-term backlight aging to adapt to higher-brightness backlights.

[0004] In order to improve the response speed of negative liquid crystals, the goal is to develop a composition with a lower γ1 / K. At the same time, in order to achieve fast response, a lower cell thickness can be used, and the liquid crystal composition usually has a high retardation amount (Δnd). The resulting problems are as follows: On the one hand, for the improvement of negative dielectric, a large amount of large-polarity monomers are usually used, which is more likely to cause ion aggregation and is more likely to produce afterimages after backlight burning; on the other hand, for the improvement of refractive index anisotropy, a large amount of highly conjugated structures such as biphenyl or terphenyl are usually used, resulting in a significant reduction in the reliability of high temperature, ultraviolet light (UV light) and backlight aging.

[0005] Therefore, it is an urgent technical problem to be solved at present to develop liquid crystal compounds and liquid crystal compositions with a large dielectric anisotropy (Δε), a high refractive index anisotropy (Δn) and high reliability (VHR), especially high reliability for high-temperature aging. Summary of the Invention

[0006] An object of the present invention is to provide a liquid crystal compound, which has a large negative dielectric anisotropy, reaching more than -10, a large optical anisotropy, good low-temperature miscibility, good reliability, and can effectively improve the afterimage of the liquid crystal composition.

[0007] The second object of the present invention is to provide a liquid crystal composition containing the liquid crystal compound, which has large negative dielectric anisotropy, large optical anisotropy, good low-temperature miscibility, good reliability and can effectively solve display defects.

[0008] The third object of the present invention is to provide a liquid crystal display element or a liquid crystal display containing the liquid crystal composition.

[0009] To achieve the above objects, the present invention adopts the following technical solutions:

[0010] The present invention provides a liquid crystal compound, and the liquid crystal compound is shown in Formula I:

[0011]

[0012] Wherein,

[0013] R a represents an alkyl group having 1-10 carbon atoms, a fluorine-substituted alkyl group having 1-10 carbon atoms, an alkoxy group having 1-10 carbon atoms, a fluorine-substituted alkoxy group having 1-10 carbon atoms, an alkenyl group having 2-10 carbon atoms, a fluorine-substituted alkenyl group having 2-10 carbon atoms, an alkenyloxy group having 3-8 carbon atoms or a fluorine-substituted alkenyloxy group having 3-8 carbon atoms;

[0014] X represents O or S;

[0015] Z represents ethylene, methyleneoxy or propyleneoxy;

[0016] represents

[0017] Invention Effect

[0018] After adding a fluorinated alkyl group to the side position of the liquid crystal compound of the present invention, the polarization force in the vertical direction of the liquid crystal molecules becomes larger, the vertical dielectric increases, and the negative dielectric increases; moreover, after adding a fluorinated alkyl group to the side position, 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, and the reliability is relatively better. Cyclopropyl, cyclobutyl and cyclopentyl have unique configurations, which are different from the chair configuration of cyclohexyl, and have better solubility and larger dielectric. The liquid crystal compound of the present invention has large negative dielectric anisotropy, up to more than -10, large optical anisotropy, good low-temperature miscibility, good reliability and can effectively improve afterimages; the liquid crystal composition containing the liquid crystal compound of the present invention also has large negative dielectric anisotropy, large optical anisotropy, good low-temperature miscibility, good reliability and can effectively improve afterimages, and can be used to develop liquid crystal display elements or liquid crystal displays with low driving and fast response. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 The MS mass spectrum showing the compound represented by Formula I-6-1 is presented. DETAILED DESCRIPTION OF THE INVENTION

[0020] The present invention provides a liquid crystal compound, which is represented by Formula Ⅰ as follows:

[0021]

[0022] Wherein,

[0023] R a represents an alkyl group having 1 to 10 carbon atoms, a fluorine-substituted alkyl group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, a fluorine-substituted alkoxy group having 1 to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, a fluorine-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;

[0024] X represents O or S;

[0025] Z represents ethylene, methyleneoxy or propyleneoxy;

[0026] represents

[0027] The liquid crystal compound of the present invention has a large negative dielectric anisotropy, which can reach more than -10, a large optical anisotropy, good low-temperature miscibility, good reliability and can effectively improve the afterimage of the liquid crystal composition.

[0028] Taking as an example, only the fluorinated alkyl substitution at the 1-position can achieve the technical effects of the present invention. The fluorinated alkyl substitutions at the 2, 3, 4, and 5-positions are difficult to synthesize, have high costs, and the performance of the compounds is poor.

[0029] Preferably, the liquid crystal compound of the present invention, the compound represented by the foregoing Formula Ⅰ is selected from the group consisting of the compounds represented by the following Formulas Ⅰ-1 to Ⅰ-16:

[0030]

[0031]

[0032] Wherein,

[0033] R a1Represents an alkyl group having 1 to 10 carbon atoms, a fluorine-substituted alkyl group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, a fluorine-substituted alkoxy group having 1 to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, a fluorine-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.

[0034] For the liquid crystal compound of the present invention, preferably, the compounds represented by the aforementioned Formulas I-1 to I-16 are selected from the group consisting of the compounds represented by the following Formulas I-1-1 to I-16-1:

[0035]

[0036]

[0037] The present invention provides a liquid crystal composition. Preferably, the aforementioned liquid crystal composition contains one or more liquid crystal compounds represented by Formula I.

[0038] For the liquid crystal composition of the present invention, preferably, the aforementioned liquid crystal composition contains one or more compounds represented by Formula II:

[0039]

[0040] Wherein,

[0041] R1 and R2 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] m represents 1 or 2.

[0043] For the liquid crystal composition of the present invention, preferably, the compounds represented by the aforementioned Formula II are selected from the group consisting of the compounds represented by the following Formulas II-1 to II-6:

[0044]

[0045]

[0046] For the liquid crystal composition of the present invention, preferably, the aforementioned liquid crystal composition contains one or more compounds represented by Formula III:

[0047]

[0048] Wherein,

[0049] 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;

[0050] Each independently represents a 1,4-phenylene group or a 1,4-cyclohexylene group.

[0051] In the liquid crystal composition of the present invention, preferably, the compound represented by the aforementioned formula III is selected from the group consisting of the compounds represented by the following formulae III-1 to III-8:

[0052]

[0053] In the liquid crystal composition of the present invention, preferably, the compound represented by the aforementioned formula III must contain the compound represented by formula III-3, and the mass percentage thereof is 5-10%.

[0054] The liquid crystal composition of the present invention preferably further comprises one or more compounds represented by formula IV:

[0055]

[0056] in,

[0057] 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;

[0058] Each independently represents a 1,4-phenylene group, a fluorinated 1,4-phenylene group, or a 1,4-cyclohexylene group.

[0059] In the liquid crystal composition of the present invention, preferably, the compound represented by the aforementioned formula IV is selected from the group consisting of the compounds represented by the following formulas IV-1 to IV-3:

[0060]

[0061] in,

[0062] 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.

[0063] In the liquid crystal composition of the present invention, preferably, the compounds represented by the aforementioned formulas IV-1 to IV-3 are selected from the group consisting of the compounds represented by formulas IV-1-1 to IV-3-2:

[0064]

[0065] In the liquid crystal composition of the present invention, preferably, the compound represented by the aforementioned formula IV must contain the compound represented by formula IV-1-1.

[0066] The liquid crystal composition of the present invention preferably further comprises one or more compounds represented by formula V:

[0067]

[0068] Among them,

[0069] R7 and R8 each independently represent an alkyl group having 1 to 10 carbon atoms, a fluorine-substituted alkyl group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, a fluorine-substituted alkoxy group having 1 to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, a fluorine-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;

[0070] represents 1,4-phenylene, 1,4-cyclohexylene or 1,4-cyclohexenylene;

[0071] n represents 1 or 2.

[0072] 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-6:

[0073]

[0074] Among them,

[0075] R7 and R8 each independently represent an alkyl group having 1 to 10 carbon atoms, a fluorine-substituted alkyl group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, a fluorine-substituted alkoxy group having 1 to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, a fluorine-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.

[0076] Preferably, dopants with various functions can also be added to the liquid crystal compound; in the liquid crystal composition, the mass percentage content of the dopant is preferably between 0.01% and 1%.

[0077] Preferably, the dopant is mainly an antioxidant, a light stabilizer, etc.

[0078] Preferably, the antioxidant is selected from one or more of the compounds represented by the following structural formulas:

[0079]

[0080] Among them, S represents an integer from 1 to 10.

[0081] Preferably, the light stabilizer is

[0082]

[0083] Among them,

[0084] S represents an integer from 1 to 10.

[0085] [Liquid crystal display element or liquid crystal display]

[0086] The present invention also provides a liquid crystal display element or a liquid crystal display comprising the above-mentioned liquid crystal composition.

[0087] Preferably, the aforementioned liquid crystal display element can be an active matrix addressed liquid crystal display element or a passive matrix display element; the liquid crystal display device can be an active matrix addressed liquid crystal display or a passive matrix display.

[0088] Preferably, the active matrix addressed liquid crystal display element is a VA-TFT, FFS-TFT or IPS-TFT liquid crystal display element.

[0089] The liquid crystal display element and the liquid crystal display of the present invention contain a liquid crystal composition composed of the liquid crystal compound of the present invention, and can be used to develop a liquid crystal display element or a liquid crystal display with low driving, high reliability and fast response, and are particularly suitable for small and medium-sized displays.

[0090] Examples

[0091] 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.

[0092] In the present invention, the preparation method is a conventional method unless otherwise specified, the raw materials used can be obtained from public commercial channels unless otherwise specified, the percentages are all by mass percentage, the temperature is in degrees Celsius (°C), and the specific meanings and test conditions of other symbols are as follows:

[0093] Cp represents the liquid crystal clearing point (°C), tested by DSC quantitative method;

[0094] S-N represents the melting point from the crystalline state to the nematic phase of the liquid crystal (°C);

[0095] Δn represents the optical anisotropy, Δn = n e -n o , where n o is the refractive index of the ordinary light, and n e is the refractive index of the extraordinary light, and the test conditions are 25 ± 2 °C, 589 nm, tested by an Abbe refractometer;

[0096] Δε represents the dielectric anisotropy, Δε = ε ∥ -ε ⊥ , where ε ∥ is the dielectric constant parallel to the molecular axis, and ε ⊥is the dielectric constant perpendicular to the molecular axis, and the test conditions are 25 ± 0.5 °C, 20 - micron vertical cell, tested with INSTEC: ALCT - IR1;

[0097] γ1 represents the rotational viscosity (mPa·s), and the test conditions are 25 ± 0.5 °C, 20 - micron vertical cell, tested with INSTEC: ALCT - IR1;

[0098] K 11 is the splay elastic constant, K 33 is the bend elastic constant, and the test conditions are: 25 °C, INSTEC: ALCT - IR1, 20 - micron vertical cell;

[0099] VHR represents the voltage holding ratio (%), and the test conditions are 60 ± 1 °C, voltage of ±5 V, pulse width of 10 ms, voltage holding time of 1.667 ms. The test equipment is TOYO Model6254 liquid crystal performance comprehensive tester;

[0100] Afterimage: The afterimage of a liquid crystal display device is the residual level of the inherent pattern during full - screen uniform display, which is visually evaluated in the following 4 grades after a specified fixed pattern is displayed in the display area for 1000 hours:

[0101] ◎ No residue

[0102] ○ There is a very small amount of residue, which is an acceptable level

[0103] △ There is residue, which is an unacceptable level

[0104] × There is residue, which is quite poor

[0105] Low - temperature observation condition: Pour 1 g of liquid crystal into a 5 - ml clean glass vial, seal it and put it into a - 20 °C low - temperature refrigerator. After 720 h, observe whether crystal precipitation occurs in the liquid crystal.

[0106] The liquid crystal monomer structure in the embodiments of the present invention is represented by codes. The coding methods for the liquid crystal ring structure, end groups, and linking groups are shown in Table 1 and Table 2 below.

[0107] Table 1 Corresponding codes for ring structures

[0108]

[0109]

[0110] Table 2 Corresponding codes for end groups and linking groups

[0111]

[0112]

[0113] Example:

[0114] Its code is Sc-Cp3FO-O4;

[0115] Its code is Sb-Cp3FO-O4;

[0116] Its code is Sb-Cp3FE-O4;

[0117] Its code is Sb-CpO-O4;

[0118] Its code is Sc-CpO-O3;

[0119] Its code is Sc-Cpr3FO-O4;

[0120] Its code is Sc-Cpr2FO-O4;

[0121] Its code is Sc-Cp1FO-O4;

[0122] Its code is COY-3-O2;

[0123] [[ID=3q]] Its code is PP-5-3;

[0124] Its code is CY-3-O2;

[0125] Its code is CC-Cp-V1;

[0126] Its code is PGP-Cpr1-2.

[0127] The liquid crystal compound with the structural formula shown in Formula I in the present invention can be synthesized by the following synthetic route:

[0128] 1) When represents Z represents methyleneoxy, the reaction process is as follows:

[0129]

[0130] Its preparation includes the following steps:

[0131] a. Using as a raw material, in the presence of sulfur tetrafluoride and hydrogen fluoride, a substitution reaction occurs to obtain It should be noted that there is a misspelling in "[[ID=3q]]" in the original text, which is likely a typo and should be "". The above translation is based on the corrected understanding.

[0132] b. Using as a raw material, a substitution reaction occurs in the presence of potassium carbonate to obtain the compound shown in Formula I.

[0133] 2) When represents and Z represents methyleneoxy, the reaction mechanism is as follows:

[0134]

[0135] Its preparation includes the following steps:

[0136] a. Using as a raw material, a substitution reaction occurs in the presence of diethylaminosulfur trifluoride to obtain

[0137] b. Using as a raw material, a substitution reaction occurs in the presence of potassium carbonate to obtain the compound shown in Formula I.

[0138] 3) When represents and Z represents methyleneoxy, using as a raw material, the reaction mechanism is the same as in 2), and Formula I can also be synthesized.

[0139] 4) When represents and Z represents n-propoxy,

[0140] using as a raw material, referring to 1 and 2) for the synthesis process, and Formula I can also be synthesized.

[0141] 5) When represents and Z represents ethyl, using and as raw materials, the synthesis process is as follows, and Formula I can also be synthesized

[0142]

[0143] Its preparation includes the following steps:

[0144] a. Using as a raw material, a substitution reaction occurs in the presence of sulfur tetrafluoride and hydrogen fluoride to obtain

[0145] b. Using as a raw material, a Grignard reaction occurs in the presence of magnesium shavings to obtain

[0146] c. Using As raw materials, in the presence of triethylsilane and boron trifluoride etherate, a substitution reaction occurs to obtain the compound shown in formula I.

[0147] 6) When express When Z represents ethylene, the reaction process is as follows:

[0148] Its preparation comprises the following steps:

[0149] a. As raw material, in the presence of diethylaminosulfur trifluoride, a substitution reaction occurs to obtain

[0150] b. As raw materials, in the presence of magnesium chips, Grignard reaction occurs to obtain

[0151] c. As raw materials, in the presence of triethylsilane and boron trifluoride etherate, a substitution reaction occurs to obtain the compound shown in formula I.

[0152] 7) When express When Z represents ethylene, As the raw material, the reaction process is consistent with the synthesis process 6), and formula I can also be synthesized.

[0153] The present invention refers to the synthesis method of US20150299161 embodiment to synthesize intermediate A The raw materials and reagents in the general synthetic formula can all be purchased through commercial channels. The principles, operating procedures, conventional post-treatments, silica gel column purification, recrystallization and other means of such methods are well known to synthesizers in the art and can fully realize the synthetic process to obtain the target product.

[0154] The reactions in all steps of all the above methods are carried out in a solvent; the solvent is selected from at least one of tetrahydrofuran, N,N-dimethylformamide, ethanol, methanol, dichloromethane, acetone, toluene and deionized water.

[0155] in,

[0156] R a1 represents an alkyl group having 1 to 10 carbon atoms, a fluorine-substituted alkyl group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, a fluorine-substituted alkoxy group having 1 to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, a fluorine-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.

[0157] G represents -OH or -CHO.

[0158] The present invention will be described below with specific embodiments.

[0159] Compound Example

[0160] Preparation of Liquid Crystal Compound I-5-1 in Synthesis Example 1

[0161] The preparation route is as follows:

[0162]

[0163] Specific operating procedures for the preparation:

[0164] Compound 29.8 g (0.1 mol) was cooled to ≤ -60 °C and evacuated. 30 g of hydrogen fluoride and 32.4 g (0.3 mol) of sulfur tetrafluoride were added successively. The reaction system was heated to 40 °C and stirred for 20 h. After the reaction was completed, volatile substances were removed. The reaction solution was diluted with 100 ml of ether. Sodium hydride was added to the organic phase and allowed to stand for a period of time, then washed with deionized water (100 ml), 10% sodium hydroxide (100 ml), and dried over anhydrous sodium sulfate for 1 h. After concentrating the organic phase, it was recrystallized twice with 1 part of petroleum ether and 2 parts of ethanol to obtain a white solid 23.8 g, yield 74%

[0165] Step 2:

[0166] Compound 19.6 g (0.067 mol) and compound 23.8 g (0.074 mol) were dissolved in 250 ml of DMF. 10.2 g (0.074 mol) of anhydrous potassium carbonate was added, and the mixture was heated to 80 °C and stirred for 5 hours. The reaction solution was cooled to 80 - 90 °C, and after the reaction was completed, it was cooled to room temperature. 200 ml of deionized water and 200 ml * 3 of ethyl acetate were added for extraction. The organic phases were combined, washed with 200 ml of deionized water and 200 ml of saturated sodium chloride, dried over anhydrous sodium sulfate for 1 h, the organic phase was rotary evaporated, and recrystallized twice with 2 parts of ethanol and 0.5 part of toluene to obtain 23.7 g of white crystal I-5-1, yield 80%.

[0167] Δn: 0.1233; Δε: -12.5; ε⊥ / Δε: 0.65

[0168] Preparation of Liquid Crystal Compound I-10-1 in Synthesis Example 2

[0169] The preparation route is as follows:

[0170]

[0171] Specific operating procedures for the preparation:

[0172] Step 1:

[0173] Compound 25.6 g (0.1 mol) was dissolved in 300 ml of dichloromethane. While cooling to ≤ 0 °C, 32.2 g (0.2 mol) of diethylaminosulfur trifluoride was added. The reaction system was warmed to room temperature and stirred for reaction for 20 h. After the reaction ended, it was extracted twice with 150 × 2 ml of dichloromethane. The organic phases were combined, washed with saturated sodium carbonate (300 ml) in the organic phase, dried with anhydrous sodium sulfate for 1 h, and after rotary evaporation, recrystallized with ethanol and toluene to obtain a white solid 18 g, yield 70%

[0174] Step 2

[0175] Compound 19.7 g (0.064 mol) and compound 18 g (0.07 mol) were dissolved in 250 ml of DMF. 9.66 g (0.07 mol) of anhydrous potassium carbonate was added, and it was heated to 100 - 110 °C and stirred for reaction for 5 h. The reaction solution was cooled to room temperature, 200 ml of deionized water was added, and it was extracted with 200 ml of ethyl acetate three times, washed with 200 ml of deionized water, washed with 200 ml of saturated sodium chloride, dried with anhydrous sodium sulfate for 1 h, the organic phase was rotary evaporated, and recrystallized twice with 2-fold ethanol and 0.5-fold toluene to obtain 18.9 g of white crystal I-10-1, yield 75%.

[0176] △n: 0.1172; △ε: -12.0; ε⊥ / Δε: 0.63

[0177] Preparation of liquid crystal compound I-9-1 in Synthesis Example 3

[0178] The preparation route is as follows:

[0179]

[0180] Specific operation process of the preparation:

[0181] Step 1:

[0182] Compound 25.4 g (0.1 mol) was dissolved in 300 ml of dichloromethane. While cooling to ≤ 0 °C, 32.2 g (0.2 mol) of diethylaminosulfur trifluoride was added. The reaction system was warmed to room temperature and stirred for reaction for 24 h. After the reaction ended, it was extracted twice with 150 × 2 ml of dichloromethane. The organic phases were combined, washed with saturated carbonic acid (300 ml) in the organic phase, dried with anhydrous sodium sulfate for 1 h, and after rotary evaporation, recrystallized with 2-fold ethanol and 1-fold petroleum ether to obtain a white solid 20.7 g, yield 75%

[0183] Step 2

[0184] Compound 19.8 g (0.068 mol) and compound 20.7 g (0.075 mol) were dissolved in 250 ml of DMF. 16.6 g (0.12 mol) of anhydrous potassium carbonate was added. The mixture was heated to 100 - 110 °C and stirred for reaction for 5 hours. The reaction solution was cooled to room temperature, 200 ml of deionized water and 200 ml of ethyl acetate were added for liquid separation. The organic phases were combined, washed with 200 ml of deionized water and 200 ml of saturated sodium chloride, dried with anhydrous sodium sulfate for 1 h, the organic phase was rotary evaporated, and recrystallized twice with 2 times of ethanol and 0.5 times of toluene to obtain 19.4 g of white crystal I - 9 - 1 with a yield of 72%.

[0185] △n: 0.1323; △ε: -13.5; ε⊥ / Δε: 0.65

[0186] Preparation of Liquid Crystal Compound I - 6 - 1 in Synthesis Example 4

[0187] The preparation route is as follows:

[0188]

[0189] The specific operation process of the preparation:

[0190] Step 1

[0191] Compound 29.8 g (0.1 mol) was cooled to ≤ -60 °C and evacuated to vacuum. 30 g of hydrogen fluoride and 32.4 g (0.3 mol) of sulfur tetrafluoride were added successively. The reaction system was heated to 40 °C and stirred for reaction for 20 h. After the reaction was completed, volatile substances were removed. The reaction solution was diluted with 100 ml of ether. Sodium hydride was added to the organic phase and allowed to stand for a period of time, and then washed with water (200 ml) and 10% sodium hydroxide (200 ml). After concentrating the organic phase, recrystallized twice with 1 time of petroleum ether and 2 times of ethanol to obtain a white solid 23.8 g with a yield of 74%

[0192] Step 2

[0193] Compound 20.64 g (0.067 mol) and compound 23.8 g (0.074 mol) was dissolved in 250 ml of DMF. 10.2 g (0.074 mol) of anhydrous potassium carbonate was added. The mixture was heated to 100 - 110 °C and stirred for reaction for 5 hours. The reaction solution was cooled to room temperature, washed with 200 ml of deionized water, washed with 200 ml of saturated sodium chloride, dried with anhydrous sodium sulfate for 1 h, the organic phase was rotary evaporated, and recrystallized twice with 2-fold ethanol and 0.5-fold toluene to obtain 22.1 g of white crystal I-6-1, with a yield of 72%.

[0194] △n: 0.1223; △ε: -14.0; ε⊥ / Δε: 0.67

[0195] Preparation of Liquid Crystal Compound I-2-1 in Synthesis Example 5

[0196] The preparation route is as follows:

[0197]

[0198] Specific operation process of the preparation:

[0199] Step 1:

[0200] Compound 20.5 g (0.1 mol) was cooled to ≤ -60 °C and evacuated to vacuum. 30 g of HF and 32.1 g (0.3 mol) of SF4 were added successively. The reaction system was heated to 40 °C and stirred for reaction for 20 h. After the reaction ended, volatile substances were removed. The reaction solution was diluted with 100 ml of ether. Sodium hydride was added to the organic phase and allowed to stand for a period of time. Then it was washed with water (200 ml) and 10% sodium hydroxide (200 ml). After concentration, it was recrystallized twice with 1-fold petroleum ether and 2-fold ethanol to obtain a white solid 16.1 g, with a yield of 70%

[0201] Step 2:

[0202] 2 g (0.084 mol) of magnesium shavings was added to a 1 L three-necked flask. 50 ml of tetrahydrofuran was added and stirred under nitrogen protection. Compound 17.71 g (0.077 mol) was dissolved in 100 ml of tetrahydrofuran. Approximately 30 ml of the solution was added to the reaction flask. After the reaction was initiated, the remaining solution was slowly added dropwise. After dropping, it was heated under reflux for 2 hours. Compound 22.4 g (0.07 mol) was dissolved in 100 ml of tetrahydrofuran and dropped into the reaction flask. After dropping, it was heated under reflux for reaction for 2 h. After cooling to ≤ 0 °C, 1 mol / L dilute hydrochloric acid was added dropwise to adjust the pH to 3 - 4. Liquid separation was carried out, and it was extracted with ethyl acetate: 100 ml × 2. The organic phases were combined, dried with anhydrous sodium sulfate for 2 h, the organic phase was rotary evaporated, and then recrystallized with 2-fold petroleum ether and 0.5-fold ethanol to obtain 23.1 g of white solid, with a yield of 70%.

[0203] Step 3:

[0204] Compound 23.1 g (0.049 mol) was dissolved in 300 ml of dichloromethane. Under nitrogen protection, the temperature was lowered to -20 - 30 °C, and 14.21 g (0.12 mol) of triethylsilane was added dropwise. After the addition was complete, 17.05 g (0.12 mol) of boron trifluoride diethyl etherate was added dropwise. After the addition was complete, the mixture was stirred at room temperature for 5 h. The pH was adjusted to 7 - 8 with saturated sodium bicarbonate solution. The organic phase was washed with water (100 g × 2), dried over 50 g of anhydrous sodium sulfate for 1 h, and the organic phase was rotary evaporated and then recrystallized from ethanol to obtain 13.4 g of white crystal I-2, with a yield of 60%.

[0205] △n: 0.1100; △ε: -10.3; ε⊥ / Δε: 0.61

[0206] The liquid crystal composition provided by the embodiment of the present invention is prepared by weighing various types of monomers according to the designed mass percentages, heating to the clearing point with stirring in a beaker, maintaining for 30 minutes, cooling to room temperature, and then testing various parameters under the test conditions.

[0207] The following specific examples are used to illustrate the present invention.

[0208] Composition Example

[0209] Example 1

[0210] The formulation and corresponding properties of the liquid crystal composition are shown in Table 3 below.

[0211] Table 3 Formulation and Corresponding Properties of the Liquid Crystal Composition of Example 1

[0212]

[0213] Comparative Example 1

[0214] The formulation and corresponding properties of the liquid crystal composition are shown in Table 4 below.

[0215] Table 4 Formulation and Corresponding Properties of the Liquid Crystal Composition of Comparative Example 1

[0216]

[0217]

[0218] Example 2

[0219] The formulation and corresponding properties of the liquid crystal composition are shown in Table 5 below.

[0220] Table 5 Formulation and Corresponding Properties of the Liquid Crystal Composition of Example 2

[0221]

[0222] Comparative Example 2

[0223] The formulation of the liquid crystal composition and the corresponding properties are shown in Table 6 below.

[0224] Table 6 Formulation and Corresponding Properties of the Liquid Crystal Composition of Comparative Example 2

[0225]

[0226]

[0227] Example 3

[0228] The formulation of the liquid crystal composition and the corresponding properties are shown in Table 7 below.

[0229] Table 7 Formulation and Corresponding Properties of the Liquid Crystal Composition of Example 3

[0230]

[0231] Comparative Example 3

[0232] The formulation of the liquid crystal composition and the corresponding properties are shown in Table 8 below.

[0233] Table 8 Formulation and Corresponding Properties of the Liquid Crystal Composition of Comparative Example 3

[0234]

[0235] Example 4

[0236] The formulation of the liquid crystal composition and the corresponding properties are shown in Table 9 below.

[0237] Table 9 Formulation and Corresponding Properties of the Liquid Crystal Composition of Example 4

[0238]

[0239]

[0240] Example 5

[0241] The formulation of the liquid crystal composition and the corresponding properties are shown in Table 10 below.

[0242] Table 10 Formulation and Corresponding Properties of the Liquid Crystal Composition of Example 5

[0243]

[0244] Example 6

[0245] The formulation of the liquid crystal composition and the corresponding properties are shown in Table 11 below.

[0246] Formulation of the liquid crystal composition of Example 6 and corresponding properties

[0247]

[0248]

[0249] Example 7

[0250] The formulation of the liquid crystal composition and the corresponding properties are shown in Table 12 below.

[0251] Table 12 Formulation of the liquid crystal composition of Example 7 and corresponding properties

[0252]

[0253] Comparative Example 4

[0254] In Comparative Example 4, Sc-Cp3FO-O4, Sb-Cp3FO-O3, and Sc-Cpr1FO-O4 in Example 7 were respectively replaced with D1, D2, and D3.

[0255]

[0256] The formulation of the liquid crystal composition and the corresponding properties are shown in Table 13 below.

[0257] Table 13 Formulation of the liquid crystal composition of Comparative Example 4 and corresponding properties

[0258]

[0259] Comparative Example 5

[0260] The formulation of the liquid crystal composition and the corresponding properties are shown in Table 14 below.

[0261] Table 14 Formulation of the liquid crystal composition of Comparative Example 5 and corresponding properties

[0262]

[0263] [[ID=5S]]

[0264] Table 15 Afterimage and reliability tests of the liquid crystal composition

[0265]

[0266]

[0267] 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 before and after the high-temperature test of the liquid crystal composition, the stronger its high-temperature resistance. Therefore, the high-temperature resistance is judged by comparing the VHR data differences of each example before and after the test. The display temperature range of the liquid crystal composition is determined by the clearing point and low-temperature storage conditions of the liquid crystal composition. The higher the clearing point and the lower the low-temperature storage temperature of the liquid crystal composition, the wider the display temperature range.

[0268] In the above experiments, the liquid crystals of the examples and the comparative examples were respectively filled in test pieces for testing. VHR represents the voltage holding ratio (%). The test conditions were 60 ± 1 °C, the voltage was ±5 V, the pulse width was 10 ms, and the voltage holding time was 1.667 ms. 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 example after high-temperature aging was significantly smaller than that of the liquid crystal of the comparative example, 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.

[0269] In summary, the liquid crystal compound of the present invention has a large negative dielectric anisotropy, reaching more than -10, a large optical anisotropy, good low-temperature miscibility, good reliability, and can effectively improve afterimages. The liquid crystal composition containing the liquid crystal compound of the present invention also has a large negative dielectric anisotropy, a large optical anisotropy, good low-temperature miscibility, good reliability, and can effectively improve afterimages, and can be used to develop low-drive and fast-response liquid crystal display elements or liquid crystal displays.

[0270] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, rather than limitations on the implementation manners of the present invention. For those of ordinary skill in the art, other different forms of changes or variations can be made based on the above description. It is impossible to enumerate all the implementation manners here. Any obvious changes or variations 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 liquid crystal compound is represented by Formula I: Wherein, R a represents an alkyl group having 1 to 10 carbon atoms, a fluorine-substituted alkyl group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, a fluorine-substituted alkoxy group having 1 to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, a fluorine-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; X represents O or S; Z represents ethylene or methoxy; indicate 2. The liquid crystal compound according to claim 1, wherein The compound represented by Formula I is selected from the group consisting of the compounds represented by the following Formulae I-1 to I-12: Wherein, R a1 represents an alkyl group having 1 to 10 carbon atoms, a fluorine-substituted alkyl group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, a fluorine-substituted alkoxy group having 1 to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, a fluorine-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.

3. The compound according to claim 2, wherein The compounds represented by Formulae I-1 to I-12 are selected from the group consisting of the compounds represented by the following Formulae I-1-1 to I-12-2:

4. A liquid crystal composition, characterized in that, The liquid crystal composition contains one or more liquid crystal compounds as described in any one of Claims 1-3.

5. The liquid crystal composition according to claim 4, wherein, The liquid crystal composition contains one or more compounds represented by Formula II: Wherein, R1 and R2 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; m represents 1 or 2.

6. The liquid crystal composition according to claim 5, characterized in that, The liquid crystal composition contains one or more compounds represented by Formula III: Wherein, 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; Each independently represents 1,4-phenylene or 1,4-cyclohexylene.

7. The liquid crystal composition according to claim 6, characterized in that, The liquid crystal composition further contains one or more compounds represented by Formula IV: Wherein, 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; Each independently represents 1,4-phenylene, fluorinated 1,4-phenylene or 1,4-cyclohexylene.

8. The liquid crystal composition according to claim 7, characterized in that, The liquid crystal composition further contains one or more compounds represented by Formula V: Wherein, R7 and R8 each independently represent an alkyl group having 1 to 10 carbon atoms, a fluorine-substituted alkyl group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, a fluorine-substituted alkoxy group having 1 to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, a fluorine-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; represents 1,4-phenylene, 1,4-cyclohexylene or 1,4-cyclohexenylene; n represents 1 or 2.

9. A liquid crystal display element, which contains the liquid crystal composition as described in any one of Claims 4-8, and the liquid crystal display element is an active matrix display element or a passive matrix display element.

10. A liquid crystal display, which contains the liquid crystal composition as described in any one of Claims 4-8, and the liquid crystal display is an active matrix display or a passive matrix display.

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