Liquid crystal composition and use thereof

Abstract

A liquid crystal composition and a use thereof. The liquid crystal composition comprises at least one compound of general formula I, at least one compound of general formula II, at least one compound of general formula III, and at least one compound of general formula IV, and can also comprise at least one compound of general formula V. The liquid crystal composition exhibits low rotational viscosity, large elastic constant, large optical anisotropy, good low-temperature intersolubility and fast response speed, and can be used in VA, IPS or FFS-mode liquid crystal displays.

Description

A liquid crystal composition and its application

[0001] Cross-references

[0002] This application claims priority to Chinese Patent Application No. 202410665243.0, filed on May 27, 2024, entitled “A Liquid Crystal Composition and Its Application Thereof,” the entire disclosure of which is incorporated herein by reference. Technical Field

[0003] This disclosure relates to the field of liquid crystal materials technology, and in particular to a liquid crystal composition and its application. Background Technology

[0004] With the advancement of the information age, the development of liquid crystal display (LCD) technology, as an application field for information display, is also constantly evolving. People's demands for the performance of LCD displays are increasing, which has also stimulated research interest in liquid crystal materials, making LCD technology a hot topic and driving its continued development.

[0005] From the perspective of formulating liquid crystal compositions for liquid crystal displays, the various properties of materials are interdependent; improving one aspect often leads to changes in others. Therefore, researching various compound combinations has become a key focus in the development of mixed liquid crystal materials, especially now that negative dielectric anisotropic materials are more widely used. However, besides considering the miscibility of liquid crystal compositions, high clearing point, large dielectric anisotropy, low rotational and flow viscosity, and fast response speed are all important properties that enable liquid crystal compositions to meet display requirements.

[0006] Currently, the main problems with LCD monitors are low contrast and slow response time. Improving these two aspects has become a crucial research topic. Studies have found that the elastic constant of the liquid crystal directly and significantly determines the monitor's contrast, while the ratio of the liquid crystal's rotational viscosity to its elastic constant determines the monitor's response speed. Therefore, it is necessary to find ways to reduce the rotational viscosity of the liquid crystal medium while increasing the elastic constant to accelerate the response time. However, practical research has revealed that rotational viscosity and elastic constant are somewhat contradictory parameters; reducing rotational viscosity leads to a decrease in the elastic constant, thus failing to achieve the goal of reducing response time.

[0007] CN112980464A discloses a negative liquid crystal composition, a liquid crystal display element, and a liquid crystal display. By using five compounds in combination, although the ratio of the rotational viscosity to the elastic constant of the liquid crystal composition is reduced, the improvement of the elastic constant itself is small, only reaching 11-14.

[0008] Therefore, developing a liquid crystal material that can both ensure high contrast and accelerate response speed has become an urgent problem to be solved. Summary of the Invention

[0009] To address the aforementioned technical problems, this disclosure provides a liquid crystal composition and its application. The liquid crystal composition has low rotational viscosity, high elastic constant, high optical anisotropy, good low-temperature miscibility, and fast response speed, and can be used for fast-response liquid crystal displays in various display modes.

[0010] In a first aspect, this disclosure provides a liquid crystal composition comprising at least one compound of general formula I, at least one compound of general formula II, at least one compound of general formula III, and at least one compound of general formula IV.

[0011] Among them, R1, R2, R4, R6, and R7 each independently represent an alkyl group with 1-7 carbon atoms or an alkenyl group with 2-7 carbon atoms;

[0012] R3 and R5 each independently represent an alkoxy group with 1-7 carbon atoms or an olefinic group with 2-7 carbon atoms;

[0013] represent In this context, * represents the linking site of a functional group.

[0014] Because the elastic constant of a liquid crystal composition is positively correlated with its clearing point and negatively correlated with its rotational viscosity, it is impossible to simultaneously achieve high contrast and fast response time in a liquid crystal display. The liquid crystal composition provided in this disclosure overcomes the deficiencies of the prior art by utilizing ① a compound containing dibenzothiophene (i.e., the compound represented by general formula I) with large dielectric and elastic constants; ② a tricyclic negative compound with methoxy bridging bonds (i.e., the compound represented by general formula II) with large elastic constants and large negative dielectric anisotropy, which can further improve the contrast and reduce the driving voltage of the liquid crystal display; ③ a tricyclic negative compound containing cyclohexene (i.e., the compound represented by general formula III) with large elastic constants; and ④ a tricyclic neutral compound (i.e., the compound represented by general formula IV) with high clearing point and good low-temperature solubility. This results in a composition that possesses both a large elastic constant and a low rotational viscosity, thereby enabling the liquid crystal display to achieve both high contrast and fast response speed.

[0015] The following are preferred technical solutions of this disclosure, but are not intended to limit the technical solutions provided by this disclosure. The technical objectives and beneficial effects of this disclosure can be better achieved through the following technical solutions.

[0016] As a preferred technical solution of this disclosure, the content of the compound represented by general formula I is 1-25 wt% by weight, for example, 1 wt%, 5 wt%, 10 wt%, 15 wt%, 20 wt%, or 25 wt%; the content of the compound represented by general formula II is 5-30 wt%, for example, 5 wt%, 10 wt%, 15 wt%, 20 wt%, 25 wt%, or 30 wt%; the content of the compound represented by general formula III is 5-40 wt%, for example, 5 wt%, 10 wt%, 15 wt%, 20 wt%, 25 wt%, 30 wt%, 35 wt%, or 40 wt%; the content of the compound represented by general formula IV is 5-40 wt%, for example, 5 wt%, 10 wt%, 15 wt%, 20 wt%, 25 wt%, 30 wt%, 35 wt%, or 40 wt%, but is not limited to the listed values, and other unlisted values ​​within the above range are also applicable.

[0017] As a preferred technical solution of this disclosure, the compound represented by general formula I is selected from any one or a combination of at least two of the compounds represented by IA1-IA5 and IB1-IB5:

[0018] As a preferred technical solution of this disclosure, the compound represented by general formula II is selected from any one or a combination of at least two of the compounds represented by IIA1-IIA12 and IIB1-IIB8:

[0019] As a preferred technical solution of this disclosure, the compound represented by general formula III is selected from any one or a combination of at least two of the compounds represented by IIIA1-IIIA24 and IIIB1-IIIB24:

[0020] As a preferred technical solution of this disclosure, the compound represented by general formula IV is selected from any one or a combination of at least two of the compounds represented by IVA1-IA48 and IVB1-IB48:

[0021] As a preferred embodiment of this disclosure, the liquid crystal composition further includes at least one compound represented by general formula V.

[0022] R8 and R9 each independently represent an alkyl group with 1-7 carbon atoms or an alkenyl group with 2-7 carbon atoms.

[0023] Furthermore, this disclosure improves the low-temperature solubility of the composition by adding a compound represented by general formula V.

[0024] Preferably, the liquid crystal composition further includes any one or a combination of at least two of the following: antioxidants, ultraviolet absorbers, light stabilizers, or infrared absorbers.

[0025] The antioxidants, ultraviolet absorbers, light stabilizers, and infrared absorbers mentioned above are all conventional choices in the field.

[0026] As a preferred technical solution of this disclosure, the compound represented by general formula V is selected from any one or a combination of at least two of the compounds represented by VA1-VA12, VB1-VB14, and VC1-VC4:

[0027] As a preferred embodiment of this disclosure, the content of the compound represented by general formula I, by weight percentage, is 1-25 wt%, for example, 1 wt%, 5 wt%, 10 wt%, 15 wt%, 20 wt%, or 25 wt%, etc.; the content of the compound represented by general formula II, by weight percentage, is 5-30 wt%, for example, 5 wt%, 10 wt%, 15 wt%, 20 wt%, 25 wt%, or 30 wt%, etc.; and the content of the compound represented by general formula III, by weight percentage, is 5-35 wt%, for example, 5 wt%, 10 wt%, 15 wt%, 20 wt%, or 25 wt%, etc. The content of the compound represented by general formula IV is 5-35 wt%, such as 5 wt%, 10 wt%, 15 wt%, 20 wt%, 25 wt%, 30 wt%, or 35 wt%, etc.; the content of the compound represented by general formula V is 5-50 wt%, such as 5 wt%, 10 wt%, 15 wt%, 20 wt%, 25 wt%, 30 wt%, 35 wt%, 40 wt%, 45 wt%, or 50 wt%, etc., but is not limited to the listed values, and other unlisted values ​​within the above range are also applicable.

[0028] Preferably, in the liquid crystal composition, the content of the compound represented by general formula I is 5-20 wt%, for example, 5 wt%, 10 wt%, 15 wt%, or 20 wt%, by weight percentage; the content of the compound represented by general formula II is 10-30 wt%, for example, 10 wt%, 15 wt%, 20 wt%, 25 wt%, or 30 wt%, by weight percentage; the content of the compound represented by general formula III is 10-30 wt%, for example, 10 wt%, 15 wt%, 20 wt%, 25 wt%, or 30 wt%, by weight percentage; the content of the compound represented by general formula IV is 10-30 wt%, for example, 10 wt%, 15 wt%, 20 wt%, 25 wt%, or 30 wt%, by weight percentage; and the content of the compound represented by general formula V is 20-40 wt%, for example, 20 wt%, 25 wt%, 30 wt%, 35 wt%, or 40 wt%, by weight percentage; however, it is not limited to the listed values, and other unlisted values ​​within the above ranges are also applicable.

[0029] More preferably, in the liquid crystal composition, the content of the compound represented by general formula I is 10-15 wt%, for example 10 wt%, 12 wt%, 13 wt%, 14 wt%, or 15 wt%, etc., by weight percentage; the content of the compound represented by general formula II is 15-25 wt%, for example 15 wt%, 17 wt%, 20 wt%, 22 wt%, or 25 wt%, etc.; and the content of the compound represented by general formula III is 15-25 wt%, for example 15 wt%. The content of the compound represented by general formula IV is 15-25 wt%, such as 15 wt%, 17 wt%, 20 wt%, 22 wt%, or 25 wt%, etc.; the content of the compound represented by general formula V is 25-35 wt%, such as 25 wt%, 27 wt%, 30 wt%, 32 wt%, or 35 wt%, etc., but is not limited to the listed values, and other unlisted values ​​within the above range are also applicable.

[0030] In this disclosure, there are no particular limitations on the preparation method of the liquid crystal composition. It can be produced by mixing at least two compounds using conventional methods, such as by mixing different components at high temperature and dissolving them together. Specifically, the liquid crystal composition is dissolved in a solvent used for the compound and mixed, and then the solvent is distilled off under reduced pressure. Alternatively, it can be prepared using conventional methods, such as dissolving a component with a smaller content in a major component with a larger content at a higher temperature, or dissolving each component in an organic solvent, such as acetone, chloroform, or methanol, and then mixing the solutions to remove the solvent.

[0031] In a second aspect, this disclosure provides an application of the liquid crystal composition described in the first aspect, wherein the liquid crystal composition is used in a VA, IPS, or FFS mode liquid crystal display.

[0032] The technical solution provided in this disclosure has the following advantages compared with the prior art:

[0033] The liquid crystal composition described in this disclosure has low rotational viscosity, high elastic constant, high optical anisotropy, good low-temperature miscibility, and fast response speed. It can be used in fast-response liquid crystal displays in various display modes. Its use in VA, IPS, or FFS mode displays can significantly improve the display effect of liquid crystal displays, and it is especially suitable for IPS and FFS mode liquid crystal displays. Detailed Implementation

[0034] To better understand the above-mentioned objectives, features, and advantages of this disclosure, the solutions disclosed herein will be further described below. It should be noted that, unless otherwise specified, the embodiments and features described herein can be combined with each other.

[0035] Numerous specific details are set forth in the following description in order to provide a full understanding of this disclosure, but this disclosure may also be implemented in other ways different from those described herein; obviously, the embodiments in the specification are only some, and not all, of the embodiments of this disclosure.

[0036] Unless otherwise stated, percentages in this disclosure are weight percentages; temperatures are in degrees Celsius.

[0037] Cp represents the liquid crystal clearing point (°C), and the test method is: microthermal analysis.

[0038] Δn represents optical anisotropy (25℃), Δn=n e –n o n o Let n be the refractive index of ordinary light. e The refractive index of unusual light is measured using an Abbe refractometer at 25±2℃ and 589nm.

[0039] Δε represents dielectric anisotropy (25℃, 1000Hz), 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. The test method is: 25±0.5℃, 20-micron vertical cell, INSTEC:ALCT-IR1 test.

[0040] γ1 represents rotational viscosity (mPa·s, 25℃), and the test method is: 25±0.5℃, 20-micron vertical box, INSTEC:ALCT-IR1 test;

[0041] K11, K22, and K33 represent the elastic constants (pN, 25℃) for warp, torsion, and bending, respectively. The test method is: 25℃, 20-micron vertical box, INSTEC:ALCT-IR1 test.

[0042] In the following embodiments, the liquid crystal composition is prepared by a thermal dissolution method, including the following steps: weighing the liquid crystal compound by weight percentage using a balance, wherein there is no specific requirement for the order of weighing and adding, usually weighing and mixing in order of the melting point of the liquid crystal compound from high to low, heating and stirring at 60°C to make the components dissolve evenly, then filtering, and finally encapsulating to obtain the target sample.

[0043] In the following embodiments, the weight percentage of each component in the liquid crystal composition and the performance parameters of the liquid crystal composition are shown in the following tables.

[0044] Example 1

[0045] Table 1

[0046] Example 2

[0047] Table 2

[0048] Example 3

[0049] Table 3

[0050] Example 4

[0051] Table 4

[0052] Example 5

[0053] Table 5

[0054] Example 6

[0055] Table 6

[0056] Example 7

[0057] Table 7

[0058] Example 8

[0059] Table 8

[0060] Example 9

[0061] Table 9

[0062] Example 10

[0063] Table 10

[0064] Example 11

[0065] Table 11

[0066] Example 12

[0067] Table 12

[0068] Example 13

[0069] Table 13

[0070] Example 14

[0071] Table 14

[0072] Example 15

[0073] Table 15

[0074] Example 16

[0075] Table 16

[0076] Comparative Example 1

[0077] Table 17

[0078] Comparative Example 2

[0079] Table 18

[0080] Comparative Example 3

[0081] Table 19

[0082] Comparative Example 4

[0083] Table 20

[0084] Comparative Example 5

[0085] Table 21

[0086] Comparative Example 6

[0087] Table 22

[0088] The performance parameters of the liquid crystal compositions obtained in Examples 1-16 and Comparative Examples 1-6 are compared, as shown in Table 23.

[0089] Table 23

[0090] As shown in Table 23, compared with Comparative Examples 1-6, the dielectric anisotropy (Δε) and optical anisotropy (Δn) of the liquid crystal compositions in Examples 1-16 are basically the same. Under these circumstances, the liquid crystal compositions provided in Examples 1-16 have a larger elastic constant (K11) and a smaller rotational viscosity (γ1), which means that the liquid crystal compositions provided in this disclosure have higher contrast and faster response speed.

[0091] Compared to Example 1, Comparative Example 3 reduced the compound represented by General Formula II, Comparative Example 4 reduced the compound represented by General Formula I, Comparative Example 5 reduced the compound represented by General Formula III, and Comparative Example 6 reduced the compound represented by General Formula IV. Example 1 has a larger elastic constant and a lower rotational viscosity compared to Comparative Examples 3-6. Therefore, it is shown that there is a synergistic relationship between the components in the liquid crystal composition. The compounds represented by General Formula I, General Formula II, General Formula III, and General Formula IV are all essential components of the liquid crystal composition provided in this disclosure, especially the compounds represented by General Formula I and General Formula II.

[0092] In summary, the liquid crystal composition provided in this disclosure has an elastic constant K11 (pN, 25°C) of 28.9 or higher, a rotational viscosity γ1 of 200 mPa·s (25°C) or lower, and a ratio of rotational viscosity γ1 to elastic constant K11 of 6.26 or lower, resulting in higher contrast and faster response speed.

[0093] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0094] The above description is merely a specific embodiment of this disclosure, enabling those skilled in the art to understand or implement it. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this disclosure. Therefore, this disclosure is not to be limited to the embodiments described herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A liquid crystal composition, characterized in that, Includes at least one compound represented by general formula I, at least one compound represented by general formula II, at least one compound represented by general formula III, and at least one compound represented by general formula IV; Among them, R1, R2, R4, R6, and R7 each independently represent an alkyl group with 1-7 carbon atoms or an alkenyl group with 2-7 carbon atoms; R3 and R5 each independently represent an alkoxy group with 1-7 carbon atoms or an alkenyl group with 2-7 carbon atoms. represent In this context, * represents the linking site of a functional group.

2. The liquid crystal composition according to claim 1, characterized in that, The content of the compound represented by general formula I is 1-25 wt%, the content of the compound represented by general formula II is 5-30 wt%, the content of the compound represented by general formula III is 5-40 wt%, and the content of the compound represented by general formula IV is 5-40 wt%.

3. The liquid crystal composition according to claim 1 or 2, characterized in that, The compound represented by general formula I is selected from any one or a combination of at least two of the compounds represented by IA1-IA5 and IB1-IB5:

4. The liquid crystal composition according to any one of claims 1-3, characterized in that, The compounds represented by general formula II are selected from any one or a combination of at least two of the compounds represented by IIA1-IIA12 and IIB1-IIB8:

5. The liquid crystal composition according to any one of claims 1-4, characterized in that, The compounds represented by general formula III are selected from any one or a combination of at least two of the compounds represented by IIIA1-IIIA24 and IIIB1-IIIB24.

6. The liquid crystal composition according to any one of claims 1-5, characterized in that, The compounds represented by general formula IV are selected from any one or a combination of at least two of the compounds represented by IVA1-IA48 and IVB1-IB48:

7. The liquid crystal composition according to any one of claims 1-6, characterized in that, The liquid crystal composition further includes at least one compound represented by general formula V. R8 and R9 each independently represent an alkyl group with 1-7 carbon atoms or an alkenyl group with 2-7 carbon atoms.

8. The liquid crystal composition according to claim 7, characterized in that, The compound represented by general formula V is selected from any one or a combination of at least two of the compounds represented by VA1-VA12, VB1-VB14, and VC1-VC4:

9. The liquid crystal composition according to claim 7 or 8, characterized in that, The content of the compound represented by general formula I is 1-25 wt%, the content of the compound represented by general formula II is 5-30 wt%, the content of the compound represented by general formula III is 5-35 wt%, the content of the compound represented by general formula IV is 5-35 wt%, and the content of the compound represented by general formula V is 5-50 wt% by weight percentage; preferably, in the liquid crystal composition, the content of the compound represented by general formula I is 5-20 wt%, the content of the compound represented by general formula II is 10-30 wt%, the content of the compound represented by general formula III is 10-30 wt%, the content of the compound represented by general formula IV is 10-30 wt%, and the content of the compound represented by general formula V is 20-40 wt% by weight percentage; More preferably, in the liquid crystal composition, the content of the compound represented by general formula I is 10-15 wt%, the content of the compound represented by general formula II is 15-25 wt%, the content of the compound represented by general formula III is 15-25 wt%, the content of the compound represented by general formula IV is 15-25 wt%, and the content of the compound represented by general formula V is 25-35 wt%, by weight percentage.

10. An application of the liquid crystal composition according to any one of claims 1-9, characterized in that, The liquid crystal composition is used in VA, IPS or FFS mode liquid crystal displays.

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