Liquid crystal composition and use thereof

Abstract

The present application relates to a liquid crystal composition and its application, and further provides a liquid crystal display element or a liquid crystal display comprising the liquid crystal composition. The liquid crystal composition of the present application has a small viscosity at low temperature, a high clearing point, can be used in various display mode devices, can widen the working temperature range of the liquid crystal display device, and can improve the response speed of the liquid crystal display device at low temperature.

Description

Technical Field

[0001] This invention relates to a liquid crystal composition and a liquid crystal display element or liquid crystal display comprising the liquid crystal composition. Background Technology

[0002] Currently, the application fields of liquid crystal compounds have significantly expanded to various display devices, electro-optical devices, electronic components, and sensors, with nematic liquid crystal compounds finding the most widespread application in flat panel displays. Liquid crystal displays use liquid crystal mixtures possessing the required material properties such as operating temperature range, thermal stability, light stability, switching time, and contrast ratio.

[0003] Polymer-dispersed liquid crystals (PDLCs) are produced by mixing low-molecular-weight liquid crystals with prepolymers and then polymerizing them under certain conditions to form micron-sized liquid crystal droplets uniformly dispersed within a polymer network. The dielectric anisotropy of the liquid crystal molecules is then utilized to obtain materials with electro-optical response characteristics, primarily operating between the scattering state and the transparent state. Compared to traditional liquid crystal devices, PDLCs offer many advantages, such as eliminating the need for polarizers and alignment layers, simplifying the fabrication process, and facilitating the fabrication of large-area flexible displays. In recent years, with the increasing application of PDLCs in various fields, the requirements for liquid crystal materials have also become more stringent. Various characteristic parameters of liquid crystal materials, such as optical anisotropy (Δn), dielectric anisotropy (Δε), and clearing point (Cp), all affect the overall performance of PDLCs. The viscosity (η) of the liquid crystal is a crucial parameter affecting the response speed of liquid crystal display devices. Viscosity increases exponentially with decreasing temperature, leading to slower response speeds and even abnormal image display at low temperatures. Lower viscosity at low temperatures ensures normal operation of liquid crystal displays. Summary of the Invention

[0004] The liquid crystal composition provided by this invention exhibits low viscosity (η) at low temperatures and 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 inability to display images properly, thus improving display performance and expanding its application range.

[0005] A liquid crystal composition, by weight, comprising:

[0006] 4% to 12% of one or more compounds represented by general formula I,

[0007] 3% to 9% of one or more compounds represented by general formula II,

[0008] 40%–56% of one or more compounds represented by general formula III,

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

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

[0011] 1% to 7% of one or more compounds represented by general formula VI,

[0012] 3% to 11% of one or more compounds represented by general formula VII,

[0013] 2% to 8% of one or more compounds represented by general formula VIII,

[0014] 4% to 12% of one or more compounds represented by general formula IX;

[0015] The structures of general formulas I to IX are as follows:

[0016]

[0017] 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 Whether they are the same or different, each independently represents C1 to C2. 12 Straight-chain alkyl; R 51 and R 61 Whether they are the same or different, each is represented independently by C1 to C2. 12 Straight-chain alkyl or C2-C 12 Straight-chain alkenyl groups.

[0018] Preferably, in the above 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 Whether the two are the same or different, they each independently represent C2–C5 straight-chain alkyl groups; R 51 and R 61Whether the two are the same or different, they each independently represent C1-C5 straight-chain alkyl groups or C2-C5 straight-chain alkenyl groups.

[0019] Specifically, the C1 to C5 straight-chain alkyl groups are selected from -CH3, -C2H5, -C3H7, -C4H9, and -C5H. 11 .

[0020] Specifically, the straight-chain alkenyl groups of C2 to C5 are selected as -CH=CH2, -CH=CH-CH3, -CH2-CH2-CH=CH2, and -CH2-CH2-CH=CH-CH3.

[0021] Preferably, the compound represented by general formula I is selected from one or more of formulas I-1 to I-3:

[0022]

[0023] The compound represented by general formula II is selected from one or more of formulas II-1 to III-2:

[0024]

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

[0026]

[0027] The compound represented by general formula IV is selected from one or more of formulas IV-1 to IV-3:

[0028]

[0029] The compound represented by general formula V is selected from one or more of formulas V-1 to V-6:

[0030]

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

[0032]

[0033]

[0034] The compound represented by general formula VII is selected from one or more of formulas VII-1 to VII-4:

[0035]

[0036] The compound represented by general formula VIII is selected from one or more of formulas VIII-1 to VIII-5:

[0037]

[0038] The compound represented by general formula IX is selected from one or more of formulas IX-1 to IX-5:

[0039]

[0040] Preferably, the liquid crystal composition provided by the present invention comprises the following components in weight percentage:

[0041] (1) 6% to 11% of one or more compounds represented by general formula I;

[0042] (2) 4% to 7% of one or more compounds represented by general formula II;

[0043] (3) 44% to 51% of one or more compounds represented by general formula III;

[0044] (4) 6% to 10% of one or more compounds represented by general formula IV;

[0045] (5) 4% to 7% of one or more compounds represented by general formula V;

[0046] (6) 2% to 5% of one or more compounds represented by general formula VI;

[0047] (7) 5% to 9% of one or more compounds represented by general formula VII;

[0048] (8) 4% to 7% of one or more compounds represented by general formula VIII;

[0049] (9) 6% to 9% of one or more compounds represented by general formula IX.

[0050] Furthermore, in order to improve the stability of the liquid crystal composition to heat and light, especially ultraviolet light, the liquid crystal composition further includes one or more of ultraviolet absorbers, hindered amine light stabilizers, and hindered phenolic antioxidants; preferably, the ultraviolet absorber is selected from one or more of benzotriazoles, benzophenones, triazines, and benzoic acid esters.

[0051] Furthermore, 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 dyes and anthraquinone dyes.

[0052] Furthermore, the total weight content of each component in the liquid crystal composition is 100%.

[0053] The present invention also includes the application of the above-mentioned liquid crystal composition in a liquid crystal display device, wherein the display mode device is preferably a PDLC type liquid crystal display device or a dye PDLC type liquid crystal display device.

[0054] The present invention also provides a liquid crystal display element or liquid crystal display, comprising the above-mentioned liquid crystal composition; wherein 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.

[0055] The liquid crystal composition of the present invention has low viscosity and high clearing point at low temperatures, and can be used in various display mode devices. It can broaden the operating temperature range of liquid crystal display devices and improve the response speed of liquid crystal display devices at low temperatures. The display mode device is preferably a PDLC type liquid crystal display device or a dye-based PDLC type liquid crystal display device.

[0056] There are no particular limitations 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 and dissolving them together at high temperature. In this case, 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, the liquid crystal composition of the present invention can be prepared by 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.

[0057] All compounds involved in this invention are known compounds, commercially available, or provided by Beijing Bayi Space-Time Liquid Crystal Technology Co., Ltd.

[0058] The compounds represented by general formulas I to IX in this invention:

[0059] Compounds represented by general formula I have high dielectric anisotropy (Δε) and moderate miscibility;

[0060] Compounds represented by general formula II have large optical anisotropy (Δn) and high clearing point (Cp);

[0061] Compounds represented by general formula III have large optical anisotropy (Δn), moderate clearing point (Cp), good miscibility, and excellent overall performance;

[0062] Compounds represented by general formula IV have high dielectric anisotropy (Δε) and good miscibility;

[0063] Compounds represented by general formula V have low optical anisotropy (Δn) and excellent low-temperature miscibility;

[0064] Compounds represented by general formula VI have moderate optical anisotropy (Δn) and good low-temperature miscibility;

[0065] Compounds represented by general formula VII have high dielectric anisotropy (Δe), moderate optical anisotropy (Δn), and excellent low-temperature miscibility.

[0066] Compounds represented by general formula VIII have moderate clearing point (Cp), moderate optical anisotropy (Δn), and good low-temperature miscibility;

[0067] Compounds represented by general formula IX have very high clearing point (Cp) and moderate optical anisotropy (Δn).

[0068] The present invention has the following beneficial effects:

[0069] The inventors conducted extensive research on the photoelectric and physical properties of existing liquid crystal compounds and unexpectedly discovered that when nine liquid crystal compounds of general formulas I to IX are combined in a specific ratio, they exhibit synergistic effects. The resulting liquid crystal composition has lower viscosity and higher clearing point at low temperatures, enabling rapid response in low-temperature environments. Furthermore, it exhibits good miscibility with polymers and is particularly suitable for wide-temperature PDLC displays. This overcomes the shortcomings of existing PDLC displays in terms of slow response speed at low temperatures and improves the low-temperature display effect. Detailed Implementation

[0070] The following examples are used to illustrate the present invention, but are not intended to limit the scope of the invention.

[0071] Unless otherwise stated, percentages in this invention are weight percentages; temperature is in degrees Celsius; Δn represents optical anisotropy (25°C); ε ∥ and ε ⊥ Δε represents the parallel dielectric constant and the perpendicular dielectric constant (25℃, 1000Hz), respectively; Δε represents the dielectric anisotropy (25℃, 1000Hz); Cp represents the clearing point of the liquid crystal composition (℃); η(-20) represents the viscosity (Pa.s) at -20℃; 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.

[0072] In the following embodiments, the group structures in the liquid crystal compounds are represented by the codes shown in Table 1.

[0073] Table 1: Group structure codes of liquid crystal compounds

[0074]

[0075]

[0076] Take the following compound structure as an example:

[0077]

[0078] Represented as: 3DUCN

[0079]

[0080] Represented as: 3CCEPC2

[0081] 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 to 100°C to make the components melt evenly, then filtering, rotary evaporating, and finally encapsulating to obtain the target sample.

[0082] 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.

[0083] In the following embodiments, all components involved are known liquid crystal compounds and can be provided by Beijing Bayi Space Technology Co., Ltd.

[0084] Example 1

[0085] category Compound Code Weight percentage (%) Performance parameters Parameter value I 2DUCN 8 Cp 130 II 3CPTP2 6 △n 0.242 III 2UTPP3 25 △ε 11.9 III 4UTPP3 7 η(-20) 1.306 III 5UTPP3 16 IV 3CUCN 8 V 5CC3 6 VI 3CCP1 4 VII 3PEUCN 7 VIII 5CPEP3 5 IX 3CCEPC5 4 IX 3CCEPC3 4

[0086] Example 2

[0087] category Compound Code Weight percentage (%) Performance parameters Parameter value I 2DUCN 4 Cp 132 II 3CPTP2 5 △n 0.243 III 2UTPP3 25 △ε 11.9 III 4UTPP3 7 η(-20) 1.392 III 5UTPP3 16 IV 3CUCN 8 V 4CC3 9 VI 3CCP1 7 VII 3PEUCN 9 VIII 2CPEP3 2 IX 5CCEPC3 4 IX 3CCEPC3 4

[0088] Example 3

[0089]

[0090]

[0091] Example 4

[0092] category Compound Code Weight percentage (%) Performance parameters Parameter value I 2DUCN 7 Cp 129 II 3CPTP2 6 △n 0.242 III 2UTPP3 25 △ε 12.3 III 4UTPP3 5 η(-20) 1.265 III 5UTPP3 16 IV 3CUCN 4 V VCC3 9 VI V2CCP1 4 VII 4PEUCN 11 VIII 2CPEP5 8 IX 3CCEPC2 2 IX 3CCEPC3 3

[0093] Example 5

[0094] category Compound Code Weight percentage (%) Performance parameters Parameter value I 3DUCN 8 Cp 132 II 5CPTP2 3 △n 0.241 III 2UTPP3 25 △ε 11.9 III 4UTPP3 9 η(-20) 1.431 III 5UTPP3 16 IV 5CUCN 8 V VCC5 8 VI VCCP1 1 VII 3PEUCN 7 VIII 3CPEP5 3 IX 3CCEPC5 6 IX 3CCEPC3 6

[0095] Example 6

[0096]

[0097]

[0098] Example 7

[0099] category Compound Code Weight percentage (%) Performance parameters Parameter value I 5DUCN 8 Cp 128 II 3CPTP2 3 △n 0.254 III 2UTPP3 28 △ε 12.1 III 3UTPP3 10 η(-20) 1.362 III 5UTPP3 18 IV 3CUCN 8 V 5CC3 5 VI 3CCP2 4 VII 3PEUCN 7 VIII 5CPEP3 2 IX 3CCEPC5 3 IX 3CCEPC3 4

[0100] Comparative Example 1

[0101] category Compound Code Weight percentage (%) Performance parameters Parameter value I 2DUCN 6 Cp 129 II 3CPTP2 5 △n 0.242 III 2UTPP3 20 △ε 12 III 4UTPP3 10 η(-20) 3.256 III 5UTPP3 13 \ 3PEGCN 4 VII 3PEUCN 6 VII 5PEUCN 5 \ 5CEPO2 13 VIII 3CPEP3 5 VIII 5CPEP3 6 IX 3CCEPC5 3 IX 3CCEPC3 4

[0102] The performance parameters of the liquid crystal compositions obtained in Example 1 and Comparative Example 1 are summarized and compared, as shown in Table 2.

[0103] Table 2

[0104] Performance parameters Cp △n △ε η(-20) Example 1 130 0.242 11.9 1.306 Comparative Example 1 129 0.242 12 3.256

[0105] Comparison shows that, compared with Comparative Example 1, under the same level of dielectric anisotropy, optical anisotropy and clearing point, the liquid crystal composition provided in Example 1 has a lower viscosity at a low temperature of -20°C.

[0106] The liquid crystal compositions obtained in Comparative Example 1 and Example 1 were respectively filled into TN-type liquid crystal test cells, and the response times were measured at -20°C and summarized for comparison. See Table 3 for details.

[0107] Table 3

[0108] Performance parameters Ton(ms) Toff(ms) RT(ms) Example 1 1187.6 921.8 2109.4 Comparative Example 1 2479.0 2183.2 4662.2

[0109] The comparison shows that, compared with Comparative Example 1, Example 1 has shorter start-up and shutdown times at low temperature (-20℃) and faster response speed at low temperature (-20℃).

[0110] Although the present invention has been described in detail above with general descriptions, specific embodiments, and experiments, modifications or improvements can be made to it, which will be obvious to those skilled in the art. Therefore, all such modifications or improvements made without departing from the spirit of the present invention fall within the scope of protection claimed by the present invention.

Claims

1. A liquid crystal composition, characterized in that, By weight, the liquid crystal composition comprises: 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%–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 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 general formulas I to 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 Whether they are the same or different, each independently represents C1 to C2. 12 Straight-chain alkyl; R 51 and R 61 Whether they are the same or different, each is represented independently by C1 to C2. 12 Straight-chain alkyl or C2-C 12 Straight-chain alkenyl groups.

2. The liquid crystal composition according to claim 1, characterized in that, In 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 Whether the two are the same or different, they each independently represent C2–C5 straight-chain alkyl groups; R 51 and R 61 Whether the two are the same or different, they each independently represent C1-C5 straight-chain alkyl groups or C2-C5 straight-chain alkenyl groups.

3. The liquid crystal composition according to claim 2, characterized in that, The C1-C5 straight-chain alkyl groups are selected from -CH3, -C2H5, -C3H7, -C4H9, and -C5H. 11 The straight-chain alkenyl groups of C2 to C5 are selected from -CH=CH2, -CH=CH-CH3, -CH2-CH2-CH=CH2, and -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 formulas I-1 to I-3: And / or, the compound represented by general formula II is selected from one or more of formulas II-1 to III-2: And / or, the compound represented by general formula III is selected from one or more of formulas III-1 to III-4: And / or, the compound represented by general formula IV is selected from one or more of formulas IV-1 to IV-3: And / or, the compound represented by general formula V is selected from one or more of formulas V-1 to V-6: And / or, the compound represented by general formula VI is selected from one or more of formulas VI-1 to VI-5: And / or, the compound represented by general formula VII is selected from one or more of formulas VII-1 to VII-4: And / or, the compound represented by general formula VIII is selected from one or more of formulas VIII-1 to VIII-5: And / or, the compound represented by general formula IX is selected from one or more of formulas IX-1 to IX-5:

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

6. The liquid crystal composition according to any one of claims 1-4, characterized in that, The liquid crystal composition further includes one or more of the following: ultraviolet absorbers, hindered amine light stabilizers, and hindered phenolic antioxidants.

7. The liquid crystal composition according to claim 5, characterized in that, The liquid crystal composition further includes one or more of the following: ultraviolet absorbers, hindered amine light stabilizers, and hindered phenolic antioxidants.

8. The liquid crystal composition according to claim 6, characterized in that, The ultraviolet absorber is selected from one or more of benzotriazoles, benzophenones, triazines, and benzoic acid esters.

9. The liquid crystal composition according to claim 7, characterized in that, The ultraviolet absorber is selected from one or more of benzotriazoles, benzophenones, triazines, and benzoic acid esters.

10. The liquid crystal composition according to any one of claims 1-4, characterized in that, The liquid crystal composition may also include one or more dichroic dyes.

11. The liquid crystal composition according to claim 5, characterized in that, The liquid crystal composition may also include one or more dichroic dyes.

12. The liquid crystal composition according to claim 6, characterized in that, The liquid crystal composition may also include one or more dichroic dyes.

13. The liquid crystal composition according to claim 7, characterized in that, The liquid crystal composition may also include one or more dichroic dyes.

14. The liquid crystal composition according to claim 8, characterized in that, The liquid crystal composition may also include one or more dichroic dyes.

15. The liquid crystal composition according to claim 9, characterized in that, The liquid crystal composition may also include one or more dichroic dyes.

16. The liquid crystal composition according to claim 10, characterized in that, The dichroic dye is selected from one or more of azo dyes and anthraquinone dyes.

17. The liquid crystal composition according to any one of claims 11 to 15, characterized in that, The dichroic dye is selected from one or more of azo dyes and anthraquinone dyes.

18. The liquid crystal composition according to any one of claims 1-4, characterized in that, The total weight content of all components in the liquid crystal composition is 100%.

19. The liquid crystal composition according to claim 5, characterized in that, The total weight content of all components in the liquid crystal composition is 100%.

20. The liquid crystal composition according to claim 6, characterized in that, The total weight content of all components in the liquid crystal composition is 100%.

21. The liquid crystal composition according to any one of claims 7 to 9, characterized in that, The total weight content of all components in the liquid crystal composition is 100%.

22. The liquid crystal composition according to claim 10, characterized in that, The total weight content of all components in the liquid crystal composition is 100%.

23. The liquid crystal composition according to any one of claims 11 to 16, characterized in that, The total weight content of all components in the liquid crystal composition is 100%.

24. The liquid crystal composition according to claim 17, characterized in that, The total weight content of all components in the liquid crystal composition is 100%.

25. The use of the liquid crystal composition according to any one of claims 1-8 in a liquid crystal display device; wherein the liquid crystal display device is a PDLC type liquid crystal display device or a dye PDLC type liquid crystal display device.

26. A liquid crystal display element or liquid crystal display, characterized in that, The liquid crystal composition includes any one of claims 1-8; 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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