Liquid crystal composition and use thereof

Abstract

The present invention relates to a liquid crystal composition and a use thereof, and also provides a liquid crystal display element or a liquid crystal display comprising said liquid crystal composition. The liquid crystal composition of the present invention has relatively low viscosity at low temperatures and a high clearing point, can be used in apparatuses having a variety of display modes, can broaden the operating temperature range of a liquid crystal display device, and improves the response speed of a liquid crystal display apparatus at low temperatures.

Description

Liquid crystal composition and application thereof

[0001] Cross-references

[0002] This application claims priority to Chinese patent application No. 202311015236.8, filed on August 11, 2023, entitled “A Liquid Crystal Composition and Its Application,” all disclosures of which are incorporated herein by reference in their entirety. Technical Field

[0003] The present invention relates to a liquid crystal composition and a liquid crystal display element or a liquid crystal display comprising the liquid crystal composition. Background Art

[0004] Currently, the application areas of liquid crystal compounds have significantly expanded to various display devices, electro-optical devices, electronic components, sensors, etc., with nematic liquid crystal compounds being the most widely used in flat-panel displays. Liquid crystal displays use liquid crystal mixtures that possess desired material properties such as operating temperature range, thermal stability, light stability, switching time, and contrast.

[0005] Polymer-dispersed liquid crystal (PDLC) is a material made by mixing low-molecular-weight liquid crystals with prepolymers. Under certain conditions, the mixture undergoes a polymerization reaction, forming micron-sized liquid crystal droplets uniformly dispersed within a polymer network. The dielectric anisotropy of the liquid crystal molecules is then exploited to create a material with electro-optical response properties. It primarily operates between a scattering state and a transparent state. Compared to traditional liquid crystal devices, polymer-dispersed displays offer many advantages, such as the lack of polarizers and alignment layers, simplified fabrication processes, and ease of fabrication into large-area flexible displays. With the increasing application of PDLC in various fields in recent years, the requirements for liquid crystal materials have also become increasingly stringent. Liquid crystal material properties, such as optical anisotropy (Δn), dielectric anisotropy (Δε), and clearing point (Cp), all influence the overall performance of PDLC. The viscosity (η) of the liquid crystal is a key parameter affecting the response speed of liquid crystal displays. Viscosity increases exponentially with decreasing temperature, resulting in slower response times and even display anomalies at low temperatures. A lower viscosity at low temperatures ensures proper operation of the display.

[0006] Summary of the Invention

[0007] The liquid crystal composition provided by the present invention has a low viscosity (η) at low temperatures and a high clearing point, enabling ultra-wide operating temperature range. It is particularly suitable for PDLC displays, overcoming the shortcomings of existing PDLC displays, such as slow low-temperature response and display issues, thereby improving display quality and broadening their application range.

[0008] A liquid crystal composition comprising, by weight:

[0009] 4% to 12% of one or more compounds represented by general formula I,

[0010] 3% to 9% of one or more compounds represented by general formula II,

[0011] 40% to 56% of one or more compounds represented by formula III,

[0012] 4% to 12% of one or more compounds represented by general formula IV,

[0013] 3% to 9% of one or more compounds represented by general formula V,

[0014] 1% to 7% of one or more compounds represented by general formula VI,

[0015] 3% to 11% of one or more compounds represented by general formula VII,

[0016] 2% to 8% of one or more compounds represented by general formula VIII,

[0017] 4% to 12% of one or more compounds represented by formula IX;

[0018] The structures of the general formulas I to IX are as follows:

[0019] Among them, R 11 、R 21 、R 22 、R 31 、R 32 、R 41 、R 52 、R 62 、R 71 、R 81 、R 82 、R 91 and R 92 The same or different, each independently represents C1~C 12 A straight chain alkyl group; R 51 and R 61 The same or different, each independently represents C1~C 12 Straight chain alkyl or C2~C 12 Straight chain alkenyl.

[0020] Preferably, in the above general formulas I to IX, R 11 、R 21 、R 22 、R 31 、R 32 、R 41 、R52 、R 62 、R 71 、R 81 、R 82 、R 91 and R 92 are the same or different, and each independently represents a C2-C5 straight-chain alkyl group; R 51 and R 61 The same or different groups independently represent a C1-C5 straight-chain alkyl group or a C2-C5 straight-chain alkenyl group.

[0021] Specifically, the straight chain alkyl of C1 to C5 is selected from -CH3, -C2H5, -C3H7, -C4H9, -C5H 11 .

[0022] Specifically, the C2-C5 straight-chain alkenyl group is selected from -CH=CH2, -CH=CH-CH3, -CH2-CH2-CH=CH2, and -CH2-CH2-CH=CH-CH3.

[0023] Preferably, the compound represented by general formula I is selected from one or more of formulas I-1 to I-3:

[0024] The compound represented by general formula II is selected from one or more of formula II-1 to formula III-2:

[0025] The compound represented by general formula III is selected from one or more of formula III-1 to formula III-4:

[0026] The compound represented by general formula IV is selected from one or more of formula IV-1 to formula IV-3:

[0027] The compound represented by general formula V is selected from one or more of formula V-1 to formula V-6:

[0028] The compound represented by general formula VI is selected from one or more of formulas VI-1 to VI-5:

[0029] The compound represented by general formula VII is selected from one or more of formulas VII-1 to VII-4:

[0030] The compound represented by general formula VIII is selected from one or more of formula VIII-1 to formula VIII-5:

[0031] The compound represented by the general formula IX is selected from one or more of formulas IX-1 to IX-5:

[0032] Preferably, the liquid crystal composition provided by the present invention comprises the following components in percentage by weight:

[0033] (1), 6% to 11% of one or more compounds represented by formula I;

[0034] (2) 4% to 7% of one or more compounds represented by formula II;

[0035] (3) 44% to 51% of one or more compounds represented by formula III;

[0036] (4) 6% to 10% of one or more compounds represented by Formula IV;

[0037] (5) 4% to 7 parts or more of a compound represented by formula V;

[0038] (6) 2% to 5% of one or more compounds represented by formula VI;

[0039] (7), 5% to 9% of one or more compounds represented by formula VII;

[0040] (8), 4% to 7% of one or more compounds represented by formula VIII;

[0041] (9) 6% to 9% of one or more compounds represented by formula IX.

[0042] Furthermore, in order to improve the stability of the liquid crystal composition to heat and light, especially ultraviolet light, the liquid crystal composition also includes one or more of a UV absorber, a hindered amine light stabilizer, and a hindered phenol antioxidant; preferably, the UV absorber is selected from one or more of benzotriazoles, benzophenones, triazines, and benzoates.

[0043] Furthermore, in order to improve the display effect of the liquid crystal display device, the liquid crystal composition may further include one or more dichroic dyes; preferably, the dichroic dyes are selected from one or more of azo and anthraquinone dyes.

[0044] Furthermore, the total weight content of each component in the liquid crystal composition is 100%.

[0045] The present invention also includes the use of the liquid crystal composition in a liquid crystal display device, wherein the display mode device is preferably a PDLC liquid crystal display device or a dye PDLC liquid crystal display device.

[0046] The present invention also provides a liquid crystal display element or a liquid crystal display, comprising the above-mentioned liquid crystal composition; the liquid crystal display element or the liquid crystal display is a PDLC type liquid crystal display device or a dye PDLC type liquid crystal display device.

[0047] The liquid crystal composition of the present invention has low viscosity and a high clearing point at low temperatures and can be used in a variety of display mode devices, thereby broadening the operating temperature range of liquid crystal displays and improving their response speed at low temperatures. The display mode devices are preferably PDLC-type liquid crystal displays or dye-PDLC-type liquid crystal displays.

[0048] There is no particular limitation on the preparation method of the liquid crystal composition of the present invention. It can be produced by mixing two or more compounds using conventional methods, such as by mixing different components at high temperature and dissolving them in each other, wherein the liquid crystal composition is dissolved in a solvent for the compound and mixed, and then the solvent is distilled off under reduced pressure; or the liquid crystal composition of the present invention can be prepared according to conventional methods, such as dissolving a component with a smaller content in a main 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.

[0049] The compounds involved in the present invention are all known compounds and can be purchased commercially or provided by Beijing Bayi Space-Time Liquid Crystal Technology Co., Ltd.

[0050] The compounds represented by general formula I to general formula IX in the present invention are:

[0051] The compound represented by general formula I has high dielectric anisotropy (Δε) and moderate mutual solubility;

[0052] The compound represented by general formula II has a large optical anisotropy (Δn) and a high clearing point (Cp);

[0053] The compound represented by general formula III has large optical anisotropy (△n), moderate clearing point (Cp), good mutual solubility, and excellent comprehensive performance;

[0054] The compound represented by general formula IV has high dielectric anisotropy (Δε) and good mutual solubility;

[0055] The compound represented by general formula V has small optical anisotropy (Δn) and excellent low-temperature miscibility;

[0056] The compound represented by general formula VI has moderate optical anisotropy (Δn) and good low-temperature miscibility;

[0057] The compound represented by general formula VII has high dielectric anisotropy (Δe), moderate optical anisotropy (Δn), and excellent low-temperature miscibility;

[0058] The compound represented by general formula VIII has a moderate clearing point (Cp), moderate optical anisotropy (Δn), and good low-temperature miscibility;

[0059] The compound represented by the general formula IX has a very high clearing point (Cp) and a moderate optical anisotropy (Δn).

[0060] The present invention has the following beneficial effects:

[0061] The inventors conducted extensive research on the optoelectronic and physical properties of existing liquid crystal compounds and unexpectedly discovered that when the nine liquid crystal compounds of general formulas I to IX were selected and combined in specific ratios, they exhibited synergistic effects. The resulting liquid crystal composition has a low viscosity and a high clearing point at low temperatures, can achieve a fast response in low-temperature environments, and has good miscibility with polymers. It is particularly suitable for wide-temperature PDLC displays, can overcome the slow response speed of existing PDLC displays at low temperatures, and can improve low-temperature display effects. DETAILED DESCRIPTION

[0062] The following examples are used to illustrate the present invention but are not intended to limit the scope of the present invention.

[0063] Unless otherwise specified, percentages in the present invention are percentages by weight; temperatures are expressed in degrees Celsius; Δn represents optical anisotropy (25°C); ε ∥ and ε ⊥ Represent the parallel dielectric constant and the perpendicular dielectric constant (25℃, 1000Hz) respectively; △ε represents the dielectric anisotropy (25℃, 1000Hz); Cp represents the clearing point of the liquid crystal composition (℃); η(-20) represents the viscosity at -20℃ (Pa.s); Ton represents the time taken for the liquid crystal display to turn on, Toff represents the time taken for the liquid crystal display to turn off, RT represents the response time, and RT=Ton+Toff.

[0064] In the following examples, the group structures in the liquid crystal compounds are represented by the codes shown in Table 1.

[0065] Table 1: Group structure codes of liquid crystal compounds

[0066] Take the following compound structure as an example:

[0067] Expressed as: 3DUCN

[0068] Expressed as: 3CCEPC2

[0069] In the following embodiments, the liquid crystal compositions are prepared by a thermal dissolution method, which includes the following steps: using a balance to weigh the liquid crystal compounds according to the weight percentage, wherein there is no specific requirement for the order of weighing and adding, and the liquid crystal compounds are usually weighed and mixed in descending order of melting point, heated and stirred at 60-100°C to make the components melt evenly, and then filtered, rotary evaporated, and finally packaged to obtain the target sample.

[0070] In the following examples, the weight percentages of the components in the liquid crystal composition and the performance parameters of the liquid crystal composition are shown in the following table.

[0071] In the following examples, all the components involved are known liquid crystal compounds and can be provided by Beijing Bayi Shikong.

[0072] Example 1

[0073] Example 2

[0074] Example 3

[0075] Example 4

[0076] Example 5

[0077] Example 6

[0078] Example 7

[0079] Comparative Example 1

[0080] The performance parameters of the liquid crystal compositions obtained in Example 1 and Comparative Example 1 are summarized and compared, see Table 2:

[0081] Table 2

[0082] Comparison shows that, compared with Comparative Example 1, with the same level of dielectric anisotropy, optical anisotropy and clearing point, the liquid crystal composition provided by Example 1 has a lower viscosity at a low temperature of -20°C.

[0083] The liquid crystal compositions obtained in Comparative Example 1 and Example 1 were respectively poured into a TN type liquid crystal test box, and the response times were measured at a temperature of -20°C for summary comparison, see Table 3:

[0084] Table 3

[0085] By comparison, it can be seen that compared with Comparative Example 1, the startup time and shutdown time of Example 1 at low temperature (-20°C) are both shorter, and the response speed is faster at low temperature (-20°C).

[0086] Although the present invention has been described in detail above using general explanations, specific embodiments, and experiments, it will be apparent to those skilled in the art that modifications and improvements may be made based on the present invention. Therefore, such modifications and improvements, which do not depart from the spirit of the present invention, are intended to be within the scope of protection claimed herein. Industrial Applicability

[0087] The liquid crystal composition of the present invention has low viscosity and high clearing point at low temperatures, can be used in various display mode devices, can broaden the operating temperature range of liquid crystal display devices, and improve the response speed of liquid crystal display devices at low temperatures.

Claims

1. A liquid crystal composition, characterized in that: The liquid crystal composition comprises, by weight: 4% to 12% of one or more compounds represented by general formula I, 3% to 9% of one or more compounds represented by general formula II, 40% to 56% of one or more compounds represented by general formula III, 4% to 12% of one or more compounds represented by general formula IV, 3% to 9% of one or more compounds represented by general formula V, 1% to 7% of one or more compounds represented by general formula VI, 3% to 11% of one or more compounds represented by the general formula VII, 2% to 8% of one or more compounds represented by general formula VIII, 4% to 12% of one or more compounds represented by general formula IX; The structures of the general formula I to general formula IX are as follows: Among them, R 11 , R 21 , R 22 , R 31 , R 32 , R 41 , R 52 , R 62 , R 71 , R 81 , R 82 , R 91 and R 92 The same or different, each independently represents C1~C 12 A straight chain alkyl group; R 51 and R 61 The same or different, each independently represents C1~C 12 Straight chain alkyl or C2~C 12 Straight chain alkenyl.

2. The liquid crystal composition according to claim 1, characterized in that: In the general formulas I to IX, R 11 , R 21 , R 22 , R 31 , R 32 , R 41 , R 52 , R 62 , R 71 , R 81 , R 82 , R 91 and R 92 are the same or different, and each independently represents a C2-C5 straight-chain alkyl group; R 51 and R 61 The same or different, each independently represents a C1-C5 straight-chain alkyl group or a C2-C5 straight-chain alkenyl group.

3. The liquid crystal composition according to claim 2, characterized in that: The C1-C5 straight chain alkyl is selected from -CH3, -C2H5, -C3H7, -C4H9, -C5H 11 ; The C2~C5 straight-chain alkenyl group is selected from -CH=CH2, -CH=CH-CH3, -CH2-CH2-CH=CH2, -CH2-CH2-CH=CH-CH3.

4. The liquid crystal composition according to claim 1, characterized in that: The compound represented by general formula I is selected from one or more of formula I-1 to formula I-3: And / or, the compound represented by general formula II is selected from one or more of formula II-1 to formula III-2: And / or, the compound represented by general formula III is selected from one or more of formula III-1 to formula III-4: And / or, the compound represented by general formula IV is selected from one or more of formula IV-1 to formula IV-3: And / or, the compound represented by general formula V is selected from one or more of formula V-1 to formula V-6: And / or, the compound represented by general formula VI is selected from one or more of formula VI-1 to formula VI-5: And / or, the compound represented by general formula VII is selected from one or more of formula VII-1 to formula VII-4: And / or, the compound represented by general formula VIII is selected from one or more of formula VIII-1 to formula VIII-5: And / or, the compound represented by the general formula IX is selected from one or more of formula IX-1 to formula IX-5:

5. The liquid crystal composition according to any one of claims 1 to 4, characterized in that: Contains the following components in weight percentage: (1), 6% to 11% of one or more compounds represented by general formula I; (2), 4% to 7% of one or more compounds represented by Formula II; (3), 44% to 51% of one or more compounds represented by Formula III; (4), 6% to 10% of one or more compounds represented by Formula IV; (5) 4% to 7% or more of a compound represented by general formula V; (6), 2% to 5% of one or more compounds represented by Formula VI; (7), 5% to 9% of one or more compounds represented by formula VII; (8), 4% to 7% of one or more compounds represented by formula VIII; (9), 6% to 9% of one or more compounds represented by the general formula IX.

6. The liquid crystal composition according to any one of claims 1 to 5, characterized in that: The liquid crystal composition further comprises one or more of an ultraviolet absorber, a hindered amine light stabilizer, and a hindered phenol antioxidant; preferably, the ultraviolet absorber is selected from one or more of benzotriazoles, benzophenones, triazines, and benzoates.

7. The liquid crystal composition according to any one of claims 1 to 6, characterized in that: The liquid crystal composition may further include one or more dichroic dyes; preferably, the dichroic dyes are selected from one or more of azo dyes and anthraquinone dyes.

8. The liquid crystal composition according to any one of claims 1 to 7, characterized in that: The total weight content of each component in the liquid crystal composition is 100%.

9. Use of the liquid crystal composition according to any one of claims 1 to 8 in a liquid crystal display device; the display mode device is a PDLC liquid crystal display device or a dye PDLC liquid crystal display device.

10. A liquid crystal display element or a liquid crystal display, characterized in that: The invention comprises the liquid crystal composition according to any one of claims 1 to 8; the liquid crystal display element or liquid crystal display is a PDLC type liquid crystal display device or a dye PDLC type liquid crystal display device.

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