A negative liquid crystal composition with high contrast and its application

Abstract

The present invention relates to liquid crystal materials and their application fields, and in particular to a negative liquid crystal composition with high contrast and its application. The liquid crystal composition comprises at least one or more compounds represented by general formulas I to III; in general formula I, R1 represents an alkyl group of 1-7 carbon atoms, an alkoxy group of 1-7 carbon atoms, or an alkenyl group of 2-7 carbon atoms, and R2 represents an alkyl group of 1-7 carbon atoms or an alkenyl group of 2-7 carbon atoms; in general formula II, R3 and R4 each independently represent an alkyl group of 1-7 carbon atoms, an alkoxy group of 1-7 carbon atoms, or an alkenyl group of 2-7 carbon atoms; in general formula III, R5 and R6 each independently represent an alkyl group of 1-7 carbon atoms, an alkoxy group of 1-7 carbon atoms, or an alkenyl group of 2-7 carbon atoms, and n represents 1 or 2, representing one or more of and.

Description

Technical Field

[0001] The present invention relates to liquid crystal materials and their application fields, and in particular to a negative liquid crystal composition with high contrast and its application. Background Art

[0002] With the advancement of the information age, the development of liquid crystal display technology, as a field of liquid crystal applications for information display, is also constantly developing. People's requirements for the performance of liquid crystal displays are getting higher and higher, which has also stimulated people's interest in the research of liquid crystal materials, making liquid crystal technology a hot topic and continuing to develop.

[0003] Currently, liquid crystal displays are developing towards larger sizes, wider viewing angles, higher contrast ratios, and faster responses, and the performance of negative liquid crystals plays a crucial role. IPS and FFS mode displays are widely used in mobile phones, laptops, tablets, computer monitors, and televisions due to their unique hard screen characteristics and very wide viewing angles.

[0004] IPS and FFS display modes, due to their unique planar arrangement of liquid crystals, are prone to light leakage in the dark state, significantly inferior to VA-type displays (MVA, PVA, UV2A, PSVA) in terms of contrast performance. Research has found that the main causes of light leakage in LCD devices are: light scattering (LC scattering), rubbing uniformity, color filter light leakage, and polarization ability. Light scattering accounts for over 60% of the factors affecting light leakage performance.

[0005] According to the scattering coefficient relationship:

[0006]

[0007] Where Δn is the optical anisotropy, n e is the extraordinary refractive index, n o is the ordinary light refractive index, d is the thickness of the liquid crystal cell, K 11 is the splay elastic constant, and γ1 is the rotational viscosity. From this relationship, we can see that LC Scattering is related to K 11 Inversely proportional to the K 11 In this case, light leakage from the liquid crystal material can be reduced.

[0008] According to the contrast formula:

[0009] CR=L255 / L0*100%,

[0010] Here, L255 represents the brightness in the on-state, and L0 represents the brightness in the off-state. It can be seen that the change in L0 significantly affects CR. In the off-state, L0 is not related to the dielectric properties of the liquid crystal molecules, but rather to the LC scattering of the liquid crystal material itself. The smaller the LC scattering, the smaller L0, and thus the higher the contrast ratio.

[0011] In view of this, this application is hereby filed. Summary of the Invention

[0012] The object of the present invention is to provide a negative liquid crystal composition having a larger splay elastic constant and a smaller liquid crystal light scattering coefficient, thereby being able to greatly improve the contrast of liquid crystal displays and solve the above-mentioned defects.

[0013] Based on this, the specific technical solutions of the present invention are as follows:

[0014] The present invention first provides a liquid crystal composition, which comprises at least one or more compounds represented by general formula I, one or more compounds represented by general formula II, and one or more compounds represented by general formula III;

[0015] The structure of the compound represented by the general formula I is:

[0016]

[0017] In the general formula I, R1 represents an alkyl group of 1 to 7 carbon atoms, an alkoxy group of 1 to 7 carbon atoms, or an alkenyl group of 2 to 7 carbon atoms, and R2 represents an alkyl group of 1 to 7 carbon atoms or an alkenyl group of 2 to 7 carbon atoms;

[0018] The structure of the compound represented by the general formula II is:

[0019]

[0020] In the general formula II, R3 and R4 each independently represent an alkyl group having 1 to 7 carbon atoms, an alkoxy group having 1 to 7 carbon atoms, or an alkenyl group having 2 to 7 carbon atoms.

[0021] The structure of the compound represented by the general formula III is:

[0022]

[0023] In the general formula III, R5 and R6 each independently represent an alkyl group of 1 to 7 carbon atoms, an alkoxy group of 1 to 7 carbon atoms, or an alkenyl group of 2 to 7 carbon atoms, and n represents 1 or 2. represent One or more of .

[0024] The present invention found that the compound represented by general formula I and the compounds represented by general formula II to III can significantly increase the splay elastic constant K of the liquid crystal material. 11 , reducing light leakage of liquid crystal materials and improving the contrast of liquid crystal displays.

[0025] Preferably, the compound of general formula I is selected from one or more of the compounds represented by formulas IA1-IA22 and IB1-IB14:

[0026]

[0027]

[0028] The compound of general formula II provided by the present invention is a compound containing bicyclohexane and has good low-temperature solubility.

[0029] Preferably, the compound represented by the general formula II is selected from one or more of the compounds shown in IIA1-IIA12, IIB1-IIB14, and IIC1-IIC4:

[0030]

[0031]

[0032] The compound of the general formula III provided by the present invention is a neutral compound containing three rings, and the compound has a high clearing point and good low-temperature solubility.

[0033] Preferably, the compound represented by the general formula III is selected from one or more of the compounds shown in IIIA1-IIIA48, IIIB1-IIIB48, and IIIC1-IIIC48:

[0034]

[0035]

[0036]

[0037] The compound represented by general formula IV provided by the present invention is a methoxy-bridged compound, which, when added to the liquid crystal composition, helps to coordinate with the compounds represented by general formula I to general formula III of the present invention, and can further improve the dielectric anisotropy of the liquid crystal composition.

[0038] Preferably, the liquid crystal composition further contains a compound represented by general formula IV:

[0039]

[0040] In the general formula IV, R7 and R8 each independently represent an alkyl group of 1 to 7 carbon atoms, an alkoxy group of 1 to 7 carbon atoms, or an alkenyl group of 2 to 7 carbon atoms, and n represents 1 or 2;

[0041] Preferably, the compound represented by the general formula IV is selected from one or more of the compounds shown in IVA1-IVA12, IVB1-IVB12, IVC1-IVC12, and ICD1-IVD12:

[0042]

[0043]

[0044] The compound of the general formula V provided by the present invention is a compound with negative dielectric anisotropy. The compound has negative dielectric anisotropy.

[0045] Preferably, the liquid crystal composition further contains a compound represented by general formula V,

[0046] The structure of the compound represented by the general formula V is:

[0047]

[0048] In the general formula V, R9, R 10 Each independently represents an alkyl group of 1 to 7 carbon atoms, an alkoxy group of 1 to 7 carbon atoms, or an alkenyl group of 2 to 7 carbon atoms, and n represents 1 or 2. represent One or more of;

[0049] Preferably, the compound represented by the general formula V is selected from one or more of the compounds shown in formulas VA1-VA48, VB1-VB48, VC1-VC48, DD1-DD48, FE1-FE48, and FF1-FF48:

[0050]

[0051]

[0052]

[0053]

[0054]

[0055]

[0056]

[0057]

[0058]

[0059] In order to ensure a more significant synergistic effect between the components in the composition of the present invention and effectively improve the comprehensive application performance of the liquid crystal material, the present invention further optimizes the amount of each component in the liquid crystal material:

[0060] The liquid crystal composition includes the following components in percentage by mass:

[0061] (1) 1-25% of the compound represented by formula I;

[0062] (2) 1 to 50% of the compound represented by formula II;

[0063] (3) 1 to 30% of the compound represented by formula III;

[0064] (4) 1 to 25% of the compound represented by formula IV;

[0065] (5) 1 to 50% of a compound represented by formula V;

[0066] More preferably, the liquid crystal composition comprises the following components in percentage by mass:

[0067] (1) 1-20% of the compound represented by formula I;

[0068] (2) 5 to 50% of the compound represented by Formula II;

[0069] (3) 5 to 30% of the compound represented by formula III;

[0070] (4) 5-25% of the compound represented by formula IV;

[0071] (5) 5 to 50% of the compound represented by formula V;

[0072] Further preferably, the liquid crystal composition comprises the following components in percentage by mass:

[0073] (1) 5-20% of the compound represented by formula I;

[0074] (2) 20-50% of the compound represented by formula II;

[0075] (3) 10-30% of the compound represented by formula III;

[0076] (4) 5-20% of the compound represented by formula IV;

[0077] (5) 20-50% of the compound represented by formula V;

[0078] Most preferably, the liquid crystal composition comprises the following components in percentage by mass:

[0079] (1) 5-15% of the compound represented by formula I;

[0080] (2) 30-45% of the compound represented by formula II;

[0081] (3) 10-25% of the compound represented by formula III;

[0082] (4) 10-20% of the compound represented by formula IV;

[0083] (5) 20-35% of the compound represented by general formula V.

[0084] Preferably, the liquid crystal composition provided by the present invention may further comprise one or more compounds represented by the general formula VI, which has a large elastic constant and a low rotational viscosity, and is very helpful in improving the contrast. The structure of the compound represented by the general formula VI is:

[0085]

[0086] In the general formula VI, R 11 、R 12 Each independently represents an alkyl group of 1 to 7 carbon atoms, an alkoxy group of 1 to 7 carbon atoms, or an alkenyl group of 2 to 7 carbon atoms;

[0087] Preferably, the compound represented by general formula VI is selected from one or more of the compounds shown in VIA1-VIA20, VIB1-VIB18, and VIC1-VIC14:

[0088]

[0089]

[0090]

[0091] Preferably, in the liquid crystal composition, when the total mass percentage of all its components is 100%, the mass content of the compound of formula VI in the composition is 0-30%; preferably 5-25%; more preferably 5-15%.

[0092] In the liquid crystal composition provided by the present invention, the compound represented by general formula I is a compound containing dibenzothiophene, which has a large dielectric constant and a large elastic constant; the compound represented by general formula II is a bicyclohexane compound, which has low rotational viscosity and excellent mutual solubility, and is an indispensable component for fast-response liquid crystal display; the compound represented by general formula III is a tricyclic neutral compound, which has a high clearing point and can effectively improve the clearing point of the liquid crystal composition; the compound represented by general formula IV is a methoxy-bridged dielectric anisotropic compound, which has a large The dielectric anisotropy can effectively reduce the driving voltage of the liquid crystal panel; the compound of general formula V is a negative compound, and its addition to the liquid crystal composition helps to cooperate with the compounds represented by general formula I to general formula IV of the present invention, which can further improve the dielectric anisotropy of the liquid crystal composition; the compound represented by general formula VI is a three-ring compound containing an ethylene bond, which has a large elastic constant and a low rotational viscosity. Its addition to the liquid crystal composition helps to cooperate with the compounds represented by general formula I to general formula IV of the present invention, which can further improve the elastic constant of the liquid crystal composition.

[0093] 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.

[0094] The present invention also provides use of the liquid crystal composition in a liquid crystal display device, preferably in a VA, IPS or FFS mode display.

[0095] Based on the above technical solution, the beneficial effects of the present invention are:

[0096] The liquid crystal composition of the present invention has low rotational viscosity, a large elastic constant, a large optical anisotropy, good low-temperature miscibility, a fast response speed, and a large contrast ratio. It can be used for 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 the liquid crystal display, and is particularly suitable for IPS and FFS mode liquid crystal displays. DETAILED DESCRIPTION

[0097] To make the objectives, technical solutions, and advantages of the present invention more clear, the technical solutions of the present invention are described clearly and completely below. Obviously, the embodiments described are only some of the embodiments of the present invention, not all of them. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0098] Unless otherwise specified, percentages in the present invention are percentages by weight; temperatures are in degrees Celsius; Δn represents optical anisotropy (25°C); Δε represents dielectric anisotropy (25°C, 1000 Hz); γ1 represents rotational viscosity (mPa.s, 25°C); Cp represents the clearing point of the liquid crystal composition (°C); K 11 , K 22 , K 33 represent the splay, torsion, and bending elastic constants (pN, 25°C), respectively.

[0099] In the following examples, the group structures in the liquid crystal compounds are represented by the codes shown in Table 1.

[0100] Table 1: Group structure codes of liquid crystal compounds

[0101]

[0102] Take the following compound structure as an example:

[0103] Expressed as: 4L3OSO3

[0104] Represented as: 4CC1OW01

[0105] 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, then filtered, and finally packaged to obtain the target sample.

[0106] 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.

[0107] Example 1

[0108] Table 2: Weight percentage and performance parameters of each component in the liquid crystal composition

[0109]

[0110] Example 2

[0111] Table 3: Weight percentage and performance parameters of each component in the liquid crystal composition

[0112]

[0113] Example 3

[0114] Table 4: Weight percentage and performance parameters of each component in the liquid crystal composition

[0115]

[0116]

[0117] Example 4

[0118] Table 5: Weight percentage and performance parameters of each component in the liquid crystal composition

[0119]

[0120] Example 5

[0121] Table 6: Weight percentage and performance parameters of each component in the liquid crystal composition

[0122]

[0123] Example 6

[0124] Table 7: Weight percentage and performance parameters of each component in the liquid crystal composition

[0125]

[0126] Example 7

[0127] Table 8: Weight percentage and performance parameters of each component in the liquid crystal composition

[0128]

[0129] Example 8

[0130] Table 9: Weight percentage and performance parameters of each component in the liquid crystal composition

[0131]

[0132]

[0133] Example 9

[0134] Table 10: Weight percentage and performance parameters of each component in the liquid crystal composition

[0135]

[0136] Example 10

[0137] Table 11: Weight percentage and performance parameters of each component in the liquid crystal composition

[0138]

[0139] Example 11

[0140] Table 12: Weight percentage and performance parameters of each component in the liquid crystal composition

[0141]

[0142]

[0143] Example 12

[0144] Table 13: Weight percentage and performance parameters of each component in the liquid crystal composition

[0145]

[0146] Example 13

[0147] Table 14: Weight percentage and performance parameters of each component in the liquid crystal composition

[0148]

[0149] Comparative Example 1

[0150] Table 15: Weight percentage and performance parameters of each component in the liquid crystal composition

[0151]

[0152] The performance parameter values ​​of the liquid crystal compositions obtained in Example 1 and Comparative Example 1 are compared, see Table 16.

[0153] Table 16: Comparison of performance parameters of liquid crystal compositions

[0154] Cp △n Δε <![CDATA[K 11 ]]> <![CDATA[γ1]]> Example 1 119.8 0.100 -3.27 25.96 163.4 Comparative Example 1 123.6 0.099 -3.26 21.06 169.7

[0155] By comparison, it can be seen that the dielectric anisotropy (Δε), clearing point (Cp), optical anisotropy (Δn), and rotational viscosity (γ1) of the liquid crystal mixture of Example 1 are basically the same as those of Comparative Example 1. In this case, the elastic constant (K 11 ) is larger, and the liquid crystal optical scattering coefficient is smaller. This means that in the dark state, the liquid crystal in the embodiment has relatively little light leakage, so the liquid crystal display has a lower brightness value at L0. Therefore, under similar conditions such as driving voltage, the liquid crystal provided by the present invention has a higher contrast.

[0156] Compared with Example 1, the compound represented by Formula I is reduced in Comparative Example 1. However, Example 1 has a larger elastic constant than Comparative Example 1, thus indicating that the compound represented by Formula I is one of the essential components of the liquid crystal composition provided by the present invention.

[0157] As can be seen from the above examples, the liquid crystal compositions provided by the present invention exhibit a large elastic constant, high resistivity, suitable optical anisotropy, good low-temperature miscibility, low rotational viscosity, and excellent light and thermal stability. These compositions can reduce the response time of liquid crystal displays, thereby resolving the issue of slow response speeds. Therefore, the liquid crystal compositions provided by the present invention are suitable for fast-response VA, IPS, and FFS TFT liquid crystal displays, particularly IPS and FFS liquid crystal displays.

[0158] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A liquid crystal composition, characterized in that At least comprising one or more compounds represented by general formula I, one or more compounds represented by general formula II, one or more compounds represented by general formula III, one or more compounds represented by general formula IV and one or more compounds represented by general formula V; The compound of general formula I is selected from one or more of the compounds represented by formulas IA1-IA22 and IB1-IB14: The compound represented by the general formula II is selected from one or more of the compounds shown in IIA1-IIA12, IIB1-IIB14, and IIC1-IIC4: The compound represented by the general formula III is selected from one or more of the compounds shown in IIIA1-IIIA48, IIIB1-IIIB48, and IIIC1-IIIC48: The compound represented by the general formula IV is selected from one or more of the compounds shown in IVA1-IVA12, IVB1-IVB12, IVC1-IVC12, and ICD1-IVD12: The compound represented by the general formula V is one or more selected from the compounds represented by formulas VA1-VA48, VB1-VB48, VC1-VC48, DD1-DD48, FE1-FE48, and FF1-FF48: The liquid crystal composition includes the following components in percentage by mass: (1) 5-15% of the compound represented by formula I; (2) 30-45% of the compound represented by formula II; (3) 10-25% of the compound represented by formula III; (4) 10-20% of the compound represented by formula IV; (5) 20-35% of the compound represented by general formula V.

2. The liquid crystal composition according to claim 1, wherein The liquid crystal composition further contains a compound represented by the general formula VI: In the general formula VI, R 11 、R 12 Each independently represents an alkyl group having 1 to 7 carbon atoms, an alkoxy group having 1 to 7 carbon atoms, or an alkenyl group having 2 to 7 carbon atoms.

3. The liquid crystal composition according to claim 2, wherein the compound represented by general formula VI is one or more selected from the group consisting of VIA1-VIA20, VIB1-VIB18, and VIC1-VIC14:

4. The liquid crystal composition according to claim 3, wherein In the liquid crystal composition, when the total mass percentage of all components is 100%, the mass content of the compound of formula VI in the composition is 5-25%.

5. The liquid crystal composition according to claim 4, characterized in that In the liquid crystal composition, when the total mass percentage of all components is 100%, the mass content of the compound of formula VI in the composition is 5-15%.

6. Use of the liquid crystal composition according to any one of claims 1 to 5 in a liquid crystal display device.

7. Use of the liquid crystal composition according to claim 6 in a liquid crystal display device, characterized in that: Application of the liquid crystal composition in VA, IPS or FFS mode displays.

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