WO2018107911A1 - Liquid crystal compound having negative dielectric anisotropy, and application therefor - Google Patents

Abstract

Provided in the present invention is a liquid crystal compound of formula(I) having negative dielectric anisotropy, the liquid crystal compound having a large absolute value of dielectric anisotropy, high optical anisotropy, high-definition bright spots, low viscosity, rapid response speed, high voltage retention, good miscibility, and good optical stability and low-temperature stability. The preparation process for the liquid crystal compound of formula (I) of the present invention has easily obtainable raw materials and a simple and easy to implement synthesis route, and is suitable for large-scale industrial production; also provided in the present invention is a liquid crystal composition containing the liquid crystal compound, the liquid crystal composition having good liquid crystal performance.

Description

Liquid crystal compound with negative dielectric anisotropy and application thereof Technical field

The present invention relates to a liquid crystal compound, particularly a liquid crystal compound having negative dielectric anisotropy and use thereof.

Background technique

The liquid crystal display element can be used in various household electric appliances, measuring machines, automobile panels, word processors, computers, printers, televisions, and the like represented by watches and clocks and electronic calculators. As a night view display mode, in a representative manner, PC (phase change), TN (twist nematic), STN (super twisted nematic), ECB (electrically controlled) can be cited. Birefringence, electronically controlled birefringence, OCB (optically compensated bend), IPS (in-plane switching), VA (vertical alignment), CSH (color super homeotropic) ) and other class patterns. According to the driving method of components, it is divided into PM (passive matrix) type and AM (active matrix) type. PM is divided into static (static) and multiplex (multiplex) types. The AM is classified into a TFT (thin film transistor), a MIM (metal insulator metal), and the like. The types of TFTs are amorphous silicon and polycrystalline silicon. The latter is classified into a high temperature type and a low temperature type according to a manufacturing process. The liquid crystal display element is classified into a reflection type using natural light, a transmission type using a backlight, and a semi-transmissive type using both natural light and backlight depending on the type of the light source.

Among these display modes, the IPS mode, the ECB mode, the VA mode, or the CSH mode are different from the conventional TN mode or the STN mode in that the former uses a liquid crystal material having a negative dielectric anisotropy. Among these display modes, in particular, an AM-driven VA-type display is used in a display element requiring a high-speed and wide viewing angle, and among them, the most desirable one is application to a liquid crystal element such as a television.

Regardless of the display mode, the liquid crystal material used is required to have a low driving voltage, a high response speed, a wide operating temperature range, a large absolute value of negative dielectric anisotropy, a high phase transition temperature, and good mutual solubility. . However, in the prior art, a highly conjugated molecular structure has a tendency to be inferior in compatibility with other liquid crystal materials, and is difficult to be used as a constituent element of a liquid crystal composition having good electrical characteristics. In addition, a liquid crystal compound used as a constituent element of a liquid crystal composition requiring light stability such as a liquid crystal display device of a thin film transistor type is required to have high stability. On the other hand, a liquid crystal display element containing a liquid crystal composition having a large absolute value of dielectric anisotropy can lower the basic voltage value, lower the driving voltage, and further reduce the power consumption.

A large number of hydrogen-substituted liquid crystal compounds on a benzene ring have been studied for a long time as a component of a liquid crystal composition having a negative dielectric anisotropy which can be used for a liquid crystal display element.

Osman, M.A., in Molec. crystals liq. Crystals, 82, 295. discloses a negative dielectric anisotropic compound of the Ref. 1 structure:

Due to the two cyano groups on the side of the compound Ref.1, the molecule has a large negative dielectric anisotropy (literature value -20). This document also indicates that such a side bis-cyano-based negative dielectric anisotropic compound has the following disadvantages: 1) high viscosity; 2) poor mutual solubility with liquid crystal monomers; 3) poor light stability. Due to the above disadvantages, the application of such negative compounds is limited.

Reiffenrath et al., Liquid Crystals, 1989, Vol. 5, No. 1, 159-170, propose fluorine-containing negative compounds of Ref. 2, Ref. 3 to avoid the disadvantages of bis-cyano-negative compounds:

Although the side fluorine-containing negative compounds such as Ref.2 and Ref.3 avoid the disadvantages of the bis-cyano-negative compound, the negative dielectric anisotropy value is too small (Ref. 2 dielectric anisotropy literature). The value is -4.1, and the Ref. 3 dielectric anisotropy literature value is -6.0). Therefore, compounds with large negative dielectric side fluorine species still need to be explored.

The researchers have found that liquid crystal host compositions and RM (reactive mesogen) materials disclosed in the prior art still have some drawbacks when used in PSA displays. Therefore, not every soluble RM material is suitable for PSA displays, and it is often difficult to find a more suitable selection criterion than direct PSA testing with pre-tilt measurements. When it is desired to polymerize by means of UV light without the addition of a photoinitiator, which may be advantageous for certain applications, the liquid crystal host composition selection becomes smaller.

Prior art PSA displays often exhibit an undesirable "image sticking" effect in which an image produced in the display is made visible by addressing selected pixels even when the voltage for that pixel has been turned off or when When other pixels have been addressed.

In the PSA display, an image sticking effect may be observed. In such displays, the ambient light or the UV component of the light emitted by the backlight causes spontaneous polymerization of the unreacted RM material. In the addressed pixels, this may change the tilt angle after several address periods, thereby causing a change in transmittance, while in unaddressed pixels, the tilt angle and transmittance remain unaffected.

Therefore, it is desirable to have a PSA display with as few image sticking effects as possible when manufacturing a PSA display to achieve a better display effect.

Therefore, in order to meet the increasing demand for applications, there is a need in the art for liquid crystal compounds that continuously improve negative dielectric anisotropy.

Summary of the invention

OBJECT OF THE INVENTION It is an object of the present invention to provide a negative dielectric anisotropy liquid crystal compound having a large absolute value of dielectric anisotropy, high optical anisotropy, high definition bright spot, and low viscosity. Fast response speed, high voltage retention, good mutual solubility, and good light stability and low temperature stability, so that the polymerizable liquid crystal composition containing the liquid crystal compound has an absolute value of dielectric anisotropy Low threshold voltage, fast response speed, high contrast, good mutual solubility, and good light stability and low temperature stability, while liquid crystal devices comprising the polymerizable liquid crystal composition exhibit little or no occurrence Image residual effect.

Another object of the present invention is to provide a method of synthesizing the above liquid crystal composition.

Still another object of the present invention is to provide a liquid crystal composition comprising the above liquid crystal compound and a display comprising the liquid crystal composition.

Technical Solution: In order to accomplish the above object, the present invention provides a compound having a negative dielectric anisotropy, the compound having the structure of Formula I:

among them,

The R ₁ independently represents a substituted or unsubstituted linear or branched alkyl group of ₁ to 10 carbon atoms, and a substituted or unsubstituted linear or branched alkenyl group of 2 to 10 carbon atoms;

The R ₂ independently represents a substituted or unsubstituted linear or branched alkyl or alkoxy group of 1 to 10 carbon atoms, and a substituted or unsubstituted linear or branched chain of 2 to 10 carbon atoms Alkenyl or alkenyloxy, wherein one or more -CH ₂ - may be substituted by -O-, provided that the oxygen atoms are not directly attached;

The ring A represents a 1,4-phenylene group or a 1,4-cyclohexylene group;

The m represents a positive integer of 1-12;

The n represents 0 or 1;

The p represents 0, 1, or 2.

In some embodiments of the invention, R ₁ independently represents a substituted or unsubstituted straight or branched alkyl group of 1 to 6 carbon atoms, substituted or unsubstituted 2 to 6 carbon atoms Linear or branched alkenyl.

In some embodiments of the invention, the m represents a positive integer from 1 to 6.

In some embodiments of the invention, the m represents a positive integer of 2-6.

In some embodiments of the invention, the m represents a positive integer of 3-6.

In some embodiments of the invention, when n is 1 and p is 0, R ₂ independently represents a substituted or unsubstituted linear or branched alkyl group of 1 to 6 carbon atoms, 2 to 6 carbons. A substituted or unsubstituted linear or branched alkenyl group of an atom wherein one or more -CH ₂ - may be substituted by -O-, provided that the oxygen atoms are not directly bonded.

In some embodiments of the invention, the compound of Formula I is selected from the group consisting of the following compounds of Formulas I-1 to I-4:

as well as

among them,

The R ₁ and R ₂ each independently represent a substituted or unsubstituted linear or branched alkyl group of 1 to 6 carbon atoms, and a substituted or unsubstituted linear or branched chain of 2 to 6 carbon atoms Alkenyl.

In some embodiments of the invention, the compound of Formula 1-1 is preferably selected from the group consisting of:

as well as

among them,

The R ₁ represents a substituted or unsubstituted linear or branched alkyl group of _{1 to} 6 carbon atoms, and a substituted or unsubstituted linear or branched alkenyl group of 2 to 6 carbon atoms.

In some embodiments of the invention, the compound of Formula 1-2 is preferably selected from the group consisting of:

as well as

among them,

The R ₁ represents a substituted or unsubstituted linear or branched alkyl group of _{1 to} 6 carbon atoms, and a substituted or unsubstituted linear or branched alkenyl group of 2 to 6 carbon atoms.

In some embodiments of the invention, the compound of Formula I-3 is preferably selected from the group consisting of:

as well as

among them,

The R ₁ represents a substituted or unsubstituted linear or branched alkyl group of _{1 to} 6 carbon atoms, and a substituted or unsubstituted linear or branched alkenyl group of 2 to 6 carbon atoms.

In some embodiments of the invention, the compound of Formula 1-4 is preferably selected from the group consisting of:

as well as

among them,

The R ₁ represents a substituted or unsubstituted linear or branched alkyl group of _{1 to} 6 carbon atoms, and a substituted or unsubstituted linear or branched alkenyl group of 2 to 6 carbon atoms.

Another aspect of the present invention provides a liquid crystal composition comprising the liquid crystal compound of the formula I of the present invention.

In some embodiments of the invention, the liquid crystal composition further comprises one or more compounds of Formula II and/or one or more compounds of Formula III:

among them,

The R ₃ , R ₄ , R ₅ and R ₆ each independently represent -H, -F, a substituted or unsubstituted linear or branched alkyl or alkoxy group of 1 to 10 carbon atoms, 2 a substituted or unsubstituted linear or branched alkenyl or alkenyloxy group of 10 carbon atoms, wherein one or more -CH ₂ - may be substituted by -O-, provided that the oxygen atoms are not directly linked;

The ring A, ring B and ring C each independently represent a 1,4-cyclohexyl group, a 1,4-phenylene group, wherein one or more non-adjacent Hs in the 1,4-phenylene group may be F substituted, one or more non-adjacent -CH ₂ - in 1,4-cyclohexyl may be substituted by -O-;

The Z ₁ represents a single bond, -CH ₂ O-, -OCH ₂ -, -COO-, -OCO- or -CH=CH-;

The a represents 0, 1, or 2, wherein when a represents 0, ring A and ring B are not simultaneously 1,4-cyclohexyl.

In some embodiments of the present invention, the liquid crystal composition further comprises

One or more compounds of formula IV

among them,

The R ₇ and R ₈ each independently represent -H, -F, a substituted or unsubstituted linear or branched alkyl or alkoxy group of 1 to 10 carbon atoms, and a substitution of 2 to 10 carbon atoms. Or unsubstituted linear or branched alkenyl or alkenyloxy, wherein one or more -CH ₂ - may be substituted by -O-, provided that the oxygen atoms are not directly attached;

The ring D and the ring E each independently represent a 1,4-cyclohexyl group, a 1,4-phenylene group, wherein one or more of H in the 1,4-phenylene group may be substituted by F, 1,4- One or more non-adjacent -CH ₂ - in the cyclohexyl group may be substituted by -O-;

The Z ₂ represents a single bond, -CH ₂ O-, -OCH ₂ -, -COO-, -OCO- or -CH=CH-;

The c represents 0 or 1.

In some embodiments of the present invention, the liquid crystal composition further comprises

One or more compounds of the general formula V

among them,

The R, R ₉ and R ₁₀ each independently represent -H, an alkyl group having 1 to 7 carbon atoms or an alkoxy group;

The Y ₁ and Y ₂ each independently represent a single bond, an acetylenic bond, an alkylene group of 1 to 4 carbon atoms, -O-, -COO-, -OCO-, -OCOO-, -CH ₂ O- or - OCH ₂ -;

The X ₁ and X ₂ each independently represent a single bond, -O-, -COO-, -OCO- or -OCOO-;

The m ₁ and m ₂ each independently represent an integer of 1-6;

The d represents 0 or 1.

In some embodiments of the present invention, the R independently represents _{-H, -CH 3, -CH 2 CH} 3 or -CH ₂ CH ₂ CH _3.

In some embodiments of the invention, R ₉ and R ₁₀ each independently represent -H or -CH ₃ .

In some embodiments of the invention, the Y ₁ and Y ₂ each independently represent a single bond, -O-, -COO-, -OCO-, -OCOO-, -CH ₂ O- or -OCH ₂ -, preferably It is a single bond, -O-, -COO-, -OCO- or -OCOO-.

In some embodiments of the invention, X ₁ and X ₂ each independently represent a single bond, —O—, —COO— or —OCO—.

Another aspect of the present invention provides a display device comprising the liquid crystal composition of the present invention.

Another aspect of the present invention provides an application of the liquid crystal composition of the present invention in VA, FFS, IPS, PSVA display modes.

Advantageous Effects: The liquid crystal compound having the general formula I provided by the present invention has a large absolute value of dielectric anisotropy, high optical anisotropy, high-definition bright spot, and low compared with other negative liquid crystal compounds of the prior art. Viscosity, fast response speed, high voltage retention, good mutual solubility, and good light stability and low temperature stability, the polymerizable liquid crystal composition containing the liquid crystal compound has a dielectric value of a large absolute value Anisotropy, low threshold voltage, fast response speed, high contrast, good mutual solubility, and good light stability and low temperature stability, while including the polymerizable liquid crystal composition exhibiting little or no image sticking Effect; and the preparation process of the liquid crystal compound of the formula I of the invention, the raw material is easy to obtain, the synthesis route is simple and easy, and is suitable for large-scale industrial production.

detailed description

The invention will now be described in connection with specific embodiments. It is to be understood that the following examples are illustrative of the invention and are not intended to limit the invention. Other combinations and various modifications within the inventive concept can be made without departing from the spirit or scope of the invention.

For ease of expression, in the following examples, the group structure of the liquid crystal compound is represented by the codes listed in Table 1:

Table 1 Group structure code of liquid crystal compound

The shorthand code for the test project in the following examples is as follows:

Cp: Clearing point (nematic-isotropic phase transition temperature, °C)

Δn: refractive index anisotropy (589 nm, 20 ° C)

Δε: dielectric anisotropy (1KHz, 25°C)

IS: The residual image of the fixed image has reached an unacceptable level of observation time.

Among them, the refractive index anisotropy was measured at 25 ° C under a sodium light (589 nm) light source using an Abbe refractometer; the dielectric test box was a TN90 type, and the cell thickness was 7 μm.

Δε=ε‖-ε⊥, where ε‖ is the dielectric constant parallel to the molecular axis, ε⊥ is the dielectric constant perpendicular to the molecular axis, test conditions: 25°C, 1KHz, test box is TN90 type, box thickness 7μm.

Afterimage level test: continuously drive the display element with 16V voltage, at a fixed time point, observe whether the residual image of the fixed image reaches an unacceptable level; if the residual image of the fixed image has reached an unacceptable level at the observation time point, it is recorded as IS < "this observation time point", if the residual image of the fixed image does not reach an unacceptable level at the observation time point, it is recorded as IS > "this observation time point".

The fixed observation time points were: 24 hours, 168 hours, 240 hours, 500 hours, and 1000 hours.

The liquid crystal compounds of the general formula I prepared by the following examples were tested for optical anisotropy and clearing points and the extrapolation parameters were determined as follows:

The commercial liquid crystal No. TS023 produced by Jiangsu Hecheng Display Technology Co., Ltd. was selected as the precursor, and the liquid crystal compound represented by Formula I was dissolved in the parent liquid crystal (10% by weight) to test the optical anisotropy of the mixture. Clearing point and dielectric anisotropy, and liquid crystal performance data of the liquid crystal compound represented by Formula I was extrapolated according to a linear relationship according to the ratio added in the matrix.

The parent liquid crystal (host) is obtained by mixing the following compounds in a ratio of 20%:40%:40%:

as well as

The test results of the maternal liquid crystal performance parameters are as follows:

Cp: 112 Δn: 0.08 Δε: 5.0 VHR: 98.1%.

Example 1

The synthetic route of compound I-1-10 is as follows:

1) Synthesis of Compound A2

In a 1 L three-necked flask, 28.4 g of Compound A1, 15.8 g of 2,3-benzeneboronic acid, 42.4 g of anhydrous sodium carbonate, 200 ml of toluene, 200 ml of water, 100 ml of ethanol, and 0.5 g of Pd(PPh ₃ ) _{4 were} added under a nitrogen atmosphere. The mixture was heated to reflux for 6 h, then worked-up, and purified by column chromatography to afford white solid A2, 22.4 g, GC >97%, yield: 83%.

2) Synthesis of Compound A3

In a 500 ml three-necked flask, add 13.5 g of compound A2, 150 ml of anhydrous tetrahydrofuran, cool under nitrogen, cool to -78 ° C, add 21 ml of n-butyllithium (2.4 mol / L of n-hexane solution), continue at -78 ° C, continue After stirring for 1 h, a mixture of 12.6 g of triisobutyl borate and 100 ml of anhydrous tetrahydrofuran was added dropwise, stirring was continued for 1 h, and the temperature was naturally raised to -40 ° C. The reaction solution was poured into a mixture of hydrochloric acid and ice to be hydrolyzed, extracted, and concentrated. 10.6 g of pale yellow solid A3 was obtained, HPLC >95%, yield: 68%.

3) Synthesis of Compound A4

To a 500 ml three-necked flask, 10.6 g of compound A3, 100 ml of dichloromethane, 50 ml of dioxane, 11.5 g of 30% hydrogen peroxide, and stirred for 3 h, and worked up to give 9.5 g of a reddish solid A4, GC >97%, yield : 98%.

4) Synthesis of Compound I-1-10

A 500 ml three-necked flask was charged with 2.9 g of A4, 150 ml of ethanol, 1.2 g of sodium hydroxide, and 1.3 g of 4-chlorobutyl methyl ether, and the mixture was heated under reflux for 3 hours, and then worked up and purified by column chromatography to give 2.4 g of white solid I-1-10. , GC>99%, yield: 81%.

According to the above synthesis method, the compound represented by the following Table 2 can be converted by the compound C and the compound A to obtain the target compound:

Table 2

The liquid crystal properties of the above target compounds are as follows:

Compound	Cp(°C)	△n	△ε
I-1-10	-11.6	0.121	-10.9
I-1-6	-44.2	0.106	-12.2
I-1-2-1	-14.5	0.123	-11.7
I-1-2-2	-38.8	0.11	-11.1

Characterization data of compound I-1-10:

MS: 372 (6%), 258 (47%), 87 (100%).

Characterization data of compound I-1-6:

MS: 358 (93%), 258 (89%), 73 (100%).

Characterization data of compound I-1-2-1:

MS: 344 (93%), 258 (100%), 59 (70%).

Characterization data of compound I-1-2-2:

MS: 358 (94%), 258 (100%), 73 (50%).

Data for representative compounds of the compound of the formula I-1 are provided in Example 1, by the liquid crystal compounds I-1-10, I-1-6, I-1-2-1 and I in Example 1. As can be seen from the data of -1-2-2, the liquid crystal compound of the formula I-1 has a large absolute value of dielectric anisotropy and a high optical anisotropy.

Example 2

The synthetic route for compound I-4-6 is as follows:

1) Synthesis of Compound B1

In a 500 ml three-necked flask, 8.1 g of compound A2, 150 ml of dichloromethane was added, and the mixture was cooled to 0 ° C under a nitrogen atmosphere, and a mixture of 15 g of boron tribromide and 30 ml of dichloromethane was added dropwise, and after the addition was completed, the temperature was naturally raised to room temperature. Stirring was continued for 8 h, and work-up gave a white solid, Compound B1, 5.4 g, GC >97%, yield: 74%.

2) Synthesis of Compound B2

In a 500 ml three-necked flask, 5.4 g of compound B2, 150 ml of ethanol, 2.7 g of sodium hydroxide, and 2.9 g of 4-chloropropyl methyl ether were added, and the mixture was heated under reflux for 3 hours, and then worked up and purified by column chromatography to yield 5.4 g of white solid B2. GC>99%, yield: 77%.

3) Synthesis of Compound B3

In a 250 ml three-necked flask, 5.4 g of compound B2, 80 ml of anhydrous tetrahydrofuran were added, and the temperature was lowered to -78 ° C under nitrogen atmosphere, and 7.5 ml of n-butyllithium (2.4 mol/L in n-hexane solution) was added dropwise, at -78 ° C. Continue stirring for 1 h, add 4.7 g of boric acid three The mixture of isobutyl ester and 50 ml of anhydrous tetrahydrofuran was stirred for 1 h, and the temperature was naturally raised to -40 ° C. The reaction mixture was poured into a mixture of hydrochloric acid and ice to be hydrolyzed, extracted, and concentrated to obtain 4.3 g of pale yellow solid B3. >95%, yield: 70%.

4) Synthesis of Compound B4

In a 500 ml three-necked flask, 4.3 g of compound B3, 100 ml of dichloromethane, 50 ml of dioxane, 4.1 g of 30% hydrogen peroxide, and stirred for 3 h, and worked up to give 3.9 g of a reddish solid B4, GC >97%, yield : 98%.

5) Synthesis of compound I-4-6

A 250 ml three-necked flask was charged with 1.1 g of B4, 80 ml of ethanol, 0.4 g of sodium hydroxide, 0.66 g of 4-chloromethylethylcyclohexane, and heated under reflux for 3 h, then worked up and purified by column chromatography to yield 1.0 g of white solid. I-4-6, GC>99%, yield: 66%.

According to the above synthesis method, the compound represented by the following Table 3 can be converted by the compound C and the compound A to obtain the target compound:

table 3

The liquid crystal properties of the above target compounds are as follows:

Compound	Cp	△n	△ε
I-4-6	46.4	0.109	-10.5
I-4-7	64.7	0.111	-10.6
I-4-8	65.1	0.111	-9.8

Characterization data of compound I-4-6:

MS: 454 (37%), 330 (42%), 258 (33%), 73 (100%).

Characterization data of compound I-4-7:

MS: MS: 468 (33%), 330 (42%), 258 (33%), 73 (100%).

Characterization data of compound I-4-8:

MS: 482 (43%), 330 (51%), 258 (34%), 73 (100%).

The data of a representative compound of the compound of the formula I-4 is provided in Example 2, and the data of the liquid crystal compounds I-4-6, I-4-7 and I-4-8 in Example 2 can be seen. The liquid crystal compound of the formula I-4 has a large absolute value of dielectric anisotropy, a high optical anisotropy and a suitably high clearing point.

Comparative example 1

The liquid crystal compositions of Comparative Example 1 were prepared according to the respective compounds and weight percentages listed in Table 4, and were filled in the performance test between the two substrates of the liquid crystal display. The test data are shown in the following table:

Table 4 liquid crystal composition formula and its test performance

99.7% of the composition of Table 4 was mixed with 0.3% of the compound V-1 to form a polymerizable liquid crystal composition M1, and M1 was injected into the test box to irradiate UV light (UV lamp parameters, 365 nm: 60 mW/cm2, 313 nm) : 0.4 mw/cm 2 ) 3 minutes, the residual image level was tested, and the result was: IS < 168 hours.

Example 3

The liquid crystal composition of Example 3 was prepared according to each compound and weight percentage listed in Table 5, and was filled in the performance test between the two substrates of the liquid crystal display. The test data is shown in the following table:

Table 5 liquid crystal composition formula and its test performance

99.7% of the composition of Table 5 was mixed with 0.3% of the compound V-1 to form a polymerizable liquid crystal composition M2, and M2 was injected into the test box, and UV light was irradiated for 3 minutes to test the afterimage level. Results: IS> 500 hours.

Example 4

The liquid crystal composition of Example 4 was prepared according to each compound and weight percentage listed in Table 6, and was filled in the performance test between the two substrates of the liquid crystal display. The test data are shown in the following table:

Table 6 liquid crystal composition formula and its test performance

99.7% of the composition of Table 6 was mixed with 0.3% of the compound V-1 to form a polymerizable liquid crystal composition M3, and M3 was injected into the test box, and UV light was irradiated for 3 minutes to test the afterimage level. Results: IS> 500 hours.

Example 5

90% of the liquid crystal composition of Table 4 in Comparative Example 1, 9.7% of I-1-10, and 0.3% of V-1 were mixed to form a mixture M4, and M4 was injected into the test box, and UV light was irradiated for 3 minutes to test. Its residual image level, the result: IS> 240 hours.

It can be seen from the data of Example 1 and Example 2 that the compound of the present invention has a large absolute value of dielectric anisotropy, a suitably high clearing point, and a suitably high optical anisotropy, and can be applied to a liquid crystal composition. .

It can be seen from the data of Comparative Example 1, Example 3 and Example 4 that the polymerizable liquid crystal composition comprising the compound of the formula I of the present invention does not reach an unacceptable image after a fixed time point of 500 h. To the extent that the polymerizable liquid crystal composition of the compound of the formula I of the present invention is not contained, at a fixed time point of 168 h, the afterimage of the fixed image has reached an unacceptable level.

It can be seen from the data of Comparative Example 1 and Example 5 that the compound of the formula I of the present invention is added to the polymerizable liquid crystal composition described in Comparative Example 1 to form the polymerizable liquid crystal combination of Example 5. Therefore, the afterimage of the fixed image has reached an unacceptable degree of the residual image of the fixed image from 168h, and the residual image of the fixed image has not reached an unacceptable extent until 240 hours. Therefore, the compound of the present invention can effectively improve the afterimage of the fixed image. That is, the inclusion of the polymerizable liquid crystal composition exhibits little image sticking effect.

The above is only a preferred embodiment of the present invention, and is not intended to limit the scope of the present invention. Although the present invention has been disclosed in the above preferred embodiments, it is not intended to limit the present invention. A person skilled in the art can make some modifications or modifications to equivalent embodiments by using the above-disclosed technical contents without departing from the technical scope of the present invention. It is still within the scope of the technical solution of the present invention to make any simple modifications, equivalent changes and modifications to the above embodiments.

Industrial applicability

The liquid crystal compound according to the present invention can be applied to the field of liquid crystals.

Claims (8)

1. A liquid crystal compound having a negative dielectric anisotropy, the compound having the structure of Formula I:

   

   among them,

   The R ₁ independently represents a substituted or unsubstituted linear or branched alkyl group of ₁ to 10 carbon atoms, and a substituted or unsubstituted linear or branched alkenyl group of 2 to 10 carbon atoms;

   The R ₂ independently represents a substituted or unsubstituted linear or branched alkyl or alkoxy group of 1 to 10 carbon atoms, and a substituted or unsubstituted linear or branched chain of 2 to 10 carbon atoms Alkenyl or alkenyloxy, wherein one or more -CH ₂ - may be substituted by -O-, provided that the oxygen atoms are not directly attached;

   The ring A represents a 1,4-phenylene group or a 1,4-cyclohexylene group;

   The m represents a positive integer of 1-12;

   The n represents 0 or 1;

   The p represents 0, 1, or 2.
2. The negatively dielectric anisotropic liquid crystalline compound according to claim 1, wherein the compound of the formula I is selected from the group consisting of the following compounds of the formulae I-1 to I-4:

   

   

   as well as

   

   among them,

   The R ₁ and R ₂ each independently represent a substituted or unsubstituted linear or branched alkyl group of 1 to 6 carbon atoms, and a substituted or unsubstituted linear or branched chain of 2 to 6 carbon atoms Alkenyl.
3. A liquid crystal composition comprising the liquid crystal compound according to any one of claims 1 to 2.
4. The liquid crystal composition according to claim 3, wherein the liquid crystal composition further comprises one or more compounds of the formula II and/or one or more compounds of the formula III:

   

   among them,

   The R ₃ , R ₄ , R ₅ and R ₆ each independently represent -H, -F, a substituted or unsubstituted linear or branched alkyl or alkoxy group of 1 to 10 carbon atoms, 2 a substituted or unsubstituted linear or branched alkenyl or alkenyloxy group of 10 carbon atoms, wherein one or more -CH ₂ - may be substituted by -O-, provided that the oxygen atoms are not directly linked;

   The ring A, ring B and ring C each independently represent a 1,4-cyclohexyl group, a 1,4-phenylene group, wherein one or more non-adjacent Hs in the 1,4-phenylene group may be F substituted, one or more non-adjacent -CH ₂ - in 1,4-cyclohexyl may be substituted by -O-;

   The Z ₁ represents a single bond, -CH ₂ O-, -OCH ₂ -, -COO-, -OCO- or -CH=CH-;

   The a represents 0, 1, or 2, wherein when a represents 0, ring A and ring B are not simultaneously 1,4-cyclohexyl.
5. The liquid crystal composition according to claim 3, wherein the liquid crystal composition further comprises:

   One or more compounds of formula IV

   

   among them,

   The R ₇ and R ₈ each independently represent -H, -F, a substituted or unsubstituted linear or branched alkyl or alkoxy group of 1 to 10 carbon atoms, and a substitution of 2 to 10 carbon atoms. Or unsubstituted linear or branched alkenyl or alkenyloxy, wherein one or more -CH ₂ - may be substituted by -O-, provided that the oxygen atoms are not directly attached;

   The ring D and the ring E each independently represent a 1,4-cyclohexyl group, a 1,4-phenylene group, wherein one or more of H in the 1,4-phenylene group may be substituted by F, 1,4- One or more non-adjacent -CH ₂ - in the cyclohexyl group may be substituted by -O-;

   The Z ₂ represents a single bond, -CH ₂ O-, -OCH ₂ -, -COO-, -OCO- or -CH=CH-;

   The c represents 0 or 1.
6. The liquid crystal composition according to claim 3, wherein the liquid crystal composition further comprises:

   One or more compounds of the general formula V

   

   among them,

   The R, R ₉ and R ₁₀ each independently represent -H, an alkyl group having 1 to 7 carbon atoms or an alkoxy group;

   The Y ₁ and Y ₂ each independently represent a single bond, an acetylenic bond, an alkylene group of 1 to 4 carbon atoms, -O-, -COO-, -OCO-, -OCOO-, -CH ₂ O- or - OCH ₂ -;

   The X ₁ and X ₂ each independently represent a single bond, -O-, -COO-, -OCO- or -OCOO-;

   The m ₁ and m ₂ each independently represent an integer of 1-6;

   The d represents 0 or 1.
7. A display device comprising the liquid crystal composition of claim 3.
8. A display device comprising the liquid crystal composition according to any one of claims 4-6.