TWI808519B - A liquid crystal composition containing pyran and terphenyl and its application - Google Patents

Abstract

The present invention relates to a liquid crystal composition, in particular to a nematic phase liquid crystal composition, more specifically to a liquid crystal composition containing pyran and terphenyl and applications thereof; the liquid crystal composition includes at least one of the compounds represented by the general formula I, at least one of the compounds represented by the general formula II, at least one of the compounds represented by the general formula III, and at least one of the compounds represented by the general formula IV; the liquid crystal composition has low rotational viscosity, large elastic constant and large optical anisotropy, and has low rotational viscosity and elastic constant Ratio, thinner liquid crystal layer thickness, its use in liquid crystal displays can significantly improve the response speed and contrast of liquid crystal displays, and at the same time contain monomers represented by general formula IV, which can effectively improve DC-type afterimages and effectively improve display effects.

Description

A liquid crystal composition containing pyran and terphenyl and its application

The present invention relates to a liquid crystal composition, in particular to a nematic liquid crystal composition, and more particularly to a liquid crystal composition containing pyran and terphenyl and its application; the liquid crystal composition provided by the present invention has fast response time and high contrast, and can improve the response speed and contrast of the liquid crystal display when used in a liquid crystal display.

In recent years, LCD monitors, as the most mainstream displays, have been widely used in various products. Among them, negative LCDs are widely used in mobile phones, notebook computers, tablet computers, computer monitors, TVs, etc. because of their unique high transmittance characteristics.

At present, the main disadvantage of negative liquid crystal displays is the slow response speed. How to improve the response speed has become an important issue for negative liquid crystal displays. Through research, it has been found that the reduction of the ratio of rotational viscosity to elastic constant of liquid crystals can help improve the response speed of liquid crystal molecules, and the increase of optical anisotropy of liquid crystals can help reduce the thickness of the liquid crystal layer of the display panel, thereby improving the response speed of the display.

As users have higher and higher requirements for the display effect of liquid crystal displays, in order to meet high-performance and high-quality display effects, liquid crystal panels tend to use alignment layers (PI) with high impedance characteristics, and high-impedance alignment layers have lower ionic properties, which are very effective for improving flicker and ion-type afterimages of liquid crystal displays.

In view of this, the present invention is proposed.

The present invention aims to provide a liquid crystal composition containing pyran and terphenyl, which has low rotational viscosity, large elastic constant and large optical anisotropy, so as to achieve the purpose of improving the response speed and contrast of liquid crystal displays; at the same time, the liquid crystal composition has negative dielectric anisotropy, has higher transmittance when used in liquid crystal displays, and has the effect of improving the flickering of liquid crystal displays; in addition, the liquid crystal composition can also weaken the RDC effect, and is very effective for improving DC-type afterimages and afterimage recovery.

It is well known in the art that reducing the clearing point of the liquid crystal composition can achieve the purpose of reducing the rotational viscosity, but with the reduction of the clearing point, the upper limit of the display temperature can be reduced, and the liquid crystal composition provided by the present invention has a high clearing point, a low rotational viscosity, a large elastic constant and a large optical anisotropy, and can weaken the RDC effect at the same time, which is very effective for improving DC-type afterimages and afterimage recovery, thereby realizing a liquid crystal display with fast response and better display effect.

Specifically, the liquid crystal composition includes at least one of the compounds represented by the general formula I, at least one of the compounds represented by the general formula II, at least one of the compounds represented by the general formula III, and at least one of the compounds represented by the general formula IV;

Wherein, in general formula I, L ₁ represents S or O; R ₁ represents C ₁ ~C ₁₂ straight-chain alkyl,

、

或

In the general formula II, R ₂ and R ₃ each independently represent a C ₁ ~C ₁₂ straight chain alkyl group, a C ₁ ~C ₁₂ straight chain alkoxy group or a C ₂ ~C ₁₂ straight chain alkenyl group; a represents 0 or 1; A ₁ represents

,

or

In the general formula III, R ₄ and R ₅ each independently represent a C ₁ ~C ₁₂ straight chain alkyl group, a C ₁ ~C ₁₂ straight chain alkoxy group or a C ₂ ~C ₁₂ straight chain alkenyl group;

In the general formula IV, R ₆ and R ₇ each independently represent a C ₁ -C ₁₂ linear alkyl group, a C ₁ -C ₁₂ linear alkoxy group or a C ₂ -C ₁₂ linear alkenyl group; L ₂ , L ₃ , and L ₄ each independently represent H or F.

Using the liquid crystal composition above in a liquid crystal display can effectively improve the response speed and contrast of the liquid crystal display, and improve DC afterimages.

As the preference of the above-mentioned technical scheme, the compound represented by general formula I is selected from one or more of formula I-1 ~ formula I-22:

As the preference of the above-mentioned technical scheme, the compound represented by general formula II is selected from one or more of formula IIA ~ formula IIF:

Wherein, R ₂ and R ₃ each independently represent a C ₁ ~C ₇ straight chain alkyl group, a C ₁ ~C ₇ straight chain alkoxy group or a C ₂ ~C ₇ straight chain alkenyl group;

Preferably, the compound represented by general formula II is selected from one or more of formula IIA1 ~ formula IIF48:

As a preference of the above-mentioned technical scheme, the compound represented by the general formula III is selected from one or more of the formula IIIA ~ formula IIIB;

Wherein, R ₄ and R ₅ each independently represent a straight-chain alkyl group of C ₁ ~C ₇ or a straight-chain alkenyl group of C ₂ ~C ₇ ;

Preferably, the compound represented by general formula III is selected from one or more of formula IIIA1 ~ formula IIIB45:

As the preference of the above-mentioned technical scheme, the compound represented by the general formula IV is selected from one or more of the formulas IVA ~ formula IVB:

Among them, R ₆ represents C ₁ ~ C ₇ straight chain alkyl or C ₂ ~ C ₇ straight chain alkenyl; R ₇ represents C ₁ ~ C ₇ straight chain alkyl or C ₁ ~ C ₇ straight chain alkoxy;

Preferably, the compound represented by general formula IV is selected from one or more of formula IVA1 ~ formula IVB36:

As a preference of the above technical solution, the liquid crystal composition further includes at least one of the compounds represented by the general formula V;

Wherein, R ₈ and R ₉ each independently represent a C ₁ ~C ₁₂ straight-chain alkyl, C ₁ ~C ₁₂ straight-chain alkoxy or C ₂ ~C ₁₂ straight-chain alkenyl; A ₂ , A ₃ each independently represent trans 1,4-cyclohexyl or 1,4-phenylene;

In the present invention, the compound represented by the above-mentioned general formula V is a neutral two-ring structure compound, which has a very low rotational viscosity and is very effective in reducing the rotational viscosity of the liquid crystal composition.

Preferably, the compound represented by general formula V is selected from one or more of formula VA to formula VC:

Wherein, R ₈ and R ₉ each independently represent a straight chain alkyl group of C ₁ ~C ₇ , a straight chain alkoxy group of C ₁ ~C ₇ or a straight chain alkenyl group of C ₂ ~C ₇ ;

More preferably, the compound represented by general formula V is selected from one or more of formula VA1 ~ formula VC24:

As a preference of the above technical solution, the liquid crystal composition further includes at least one of the compounds represented by the general formula VI;

Wherein, R ₁₀ and R ₁₁ each independently represent a C ₁ ~C ₁₂ straight chain alkyl group, a C ₁ ~C ₁₂ straight chain alkoxy group or a C ₂ ~C ₁₂ straight chain alkenyl group; A ₄ represents trans 1,4-cyclohexyl or 1,4-phenylene;

Preferably, the compound represented by general formula VI is selected from one or more of formula VIA ~ formula VIB:

Wherein, R ₁₀ and R ₁₁ each independently represent a straight chain alkyl group of C ₁ ~C ₇ , a straight chain alkoxy group of C ₁ ~C ₇ or a straight chain alkenyl group of C ₂ ~C ₇ ;

More preferably, the compound represented by general formula VI is selected from one or more of formula VIA1 ~ formula VIB63:

The liquid crystal composition of the present invention may contain common antioxidants, ultraviolet absorbers, photostabilizers, infrared absorbers, and the like in addition to the above-mentioned compounds.

As a preferred technical solution, the liquid crystal composition comprises the following components by mass percentage: (1), 1-50% of the compound represented by the general formula I; (2), 5-70% of the compound represented by the general formula II; (3), 1-40% of the compound represented by the general formula III; (4), 1-50% of the compound represented by the general formula IV; (5), 0-70% of the compound represented by the general formula V; Representative compounds.

As a preference of the above technical solution, the liquid crystal composition comprises the following components in mass percentage: (1), 1-30% of the compound represented by the general formula I; (2), 10-70% of the compound represented by the general formula II; (3), 3-30% of the compound represented by the general formula III; (4), 1-30% of the compound represented by the general formula IV; (5), 10-60% of the compound represented by the general formula V; (6), 0-35% of the compound represented by the general formula VI; (2), 15-65% of the compound represented by the general formula II; (3), 4-25% of the compound represented by the general formula III; (4), 1-25% of the compound represented by the general formula IV; (5), 15-55% of the compound represented by the general formula V; (6), 0-30% of the compound represented by the general formula VI; (2), 25-55% of the compound represented by the general formula II; (3), 4-20% of the compound represented by the general formula III; (4), 3-20% of the compound represented by the general formula IV; (5), 20-50% of the compound represented by the general formula V; (6), 0-20% of the compound represented by the general formula VI; The compound represented by the general formula I; (2), 20-70% of the compound represented by the general formula II; (3), 4-20% of the compound represented by the general formula III; (4), 3-20% of the compound represented by the general formula IV; (5), 27-60% of the compound represented by the general formula V; (6), 0-20% of the compound represented by the general formula VI; (2), 30-55% of the compound represented by the general formula II; (3), 4-15% of the compound represented by the general formula III; (4), 3-15% of the compound represented by the general formula IV; (5), 27-46% of the compound represented by the general formula V; (6), 0-10% of the compound represented by the general formula VI; (2), 30-70% of the compound represented by the general formula II; (3), 1-20% of the compound represented by the general formula III; (4), 5-30% of the compound represented by the general formula IV; (5), 20-58% of the compound represented by the general formula V; (6), 0-15% of the compound represented by the general formula VI; The compound represented by general formula I; (2), 30-50% of the compound represented by the general formula II; (3), 1-12% of the compound represented by the general formula III; (4), 9-25% of the compound represented by the general formula IV; (5), 27-46% of the compound represented by the general formula V; (6), 0-12% of the compound represented by the general formula VI; (2), 33-65% of the compound represented by the general formula II; (3), 4-20% of the compound represented by the general formula III; (4), 3-20% of the compound represented by the general formula IV; (5), 15-53% of the compound represented by the general formula V; (6), 0-15% of the compound represented by the general formula VI; The compound represented by I; (2), the compound represented by the general formula II of 33-55%; (3), the compound represented by the general formula III of 6-15%; (4), the compound represented by the general formula IV of 5-15%; (5), the compound represented by the general formula V of 27-46%;

In the liquid crystal composition provided by the present invention, the dielectric anisotropy and rotational viscosity are increased by the compound represented by the general formula I; the dielectric anisotropy and mutual solubility are improved by the compound represented by the general formula II; the elastic constant and the clearing point are improved by the compound represented by the general formula III; the optical anisotropy and dielectric anisotropy are increased by the compound represented by the general formula IV; the rotational viscosity is reduced by adding the compound of the general formula V;

As users have higher and higher requirements for the display effect of liquid crystal displays, in order to meet high-performance and high-quality display effects, liquid crystal panels tend to use alignment layers (PI) with high impedance characteristics, and high-impedance alignment layers have lower ionic properties, which are very effective for improving flicker and ion-type afterimages of liquid crystal displays. The researchers of the present invention found that the addition of the terphenyl single crystal represented by the general formula IV provided by the present invention can weaken the RDC effect, and is very effective in improving DC-type afterimages and restoring afterimages.

The preparation method of the liquid crystal composition of the present invention is not particularly limited, and two or more compounds can be produced by mixing two or more compounds by a conventional method, such as by mixing different components at high temperature and dissolving each other, wherein the liquid crystal composition is dissolved in the solvent used 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 a conventional method, such as dissolving the component with a small content in the main component with a large content at a relatively high temperature, or dissolving each component in an organic solvent, such as acetone, chloroform or methanol, etc. , and then the solutions were mixed to remove the solvent to obtain .

The liquid crystal composition of the present invention has a low rotational viscosity, a large elastic constant and a large optical anisotropy, and further has a low rotational viscosity to elastic constant ratio, and a thinner liquid crystal layer thickness. Its use in a liquid crystal display can significantly improve the response speed and contrast of the liquid crystal display. At the same time, it contains the monomer represented by the general formula IV, which can effectively improve the DC type afterimage and effectively improve the display effect.

The present invention also provides the application of the above-mentioned liquid crystal composition in a liquid crystal display.

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

Unless otherwise specified, percentages in the present invention are percentages by weight; temperature unit is Celsius; Δn represents optical anisotropy (25°C); ε _∥ and ε _⊥ represent parallel and perpendicular dielectric constants (25°C _{, 1000Hz); 22 and} K ₃₃ respectively represent splay, torsion and bending elastic constants (pN, 25°C).

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

Take the following compound structure as an example:

Expressed as: A1OSO1B

Expressed as: 3CPW02

In the following examples, the preparation of the liquid crystal composition adopts the thermal dissolution method, including the following steps: use a balance to weigh the liquid crystal compound according to the weight percentage, and there is no specific requirement for the order of weighing and adding. Usually, the liquid crystal compound is weighed and mixed in order of melting point from high to low, heated and stirred at 60-100°C to make each component melt evenly, filtered, rotary evaporated, and finally packaged to obtain the target sample.

In the following examples, 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.

Example 1

Example 2

Example 3

Example 4

Example 5

Example 6

Example 7

Example 8

Example 9

Example 10

Example 11

Example 12

Example 13

Example 14

Example 15

Example 16

Example 17

Example 18

Example 19

Example 20

Example 21

Example 22

Example 23

Example 24

Example 25

Example 26

Example 27

Example 28

Example 29

Example 30

Example 31

Example 32

Example 33

Comparative example 1

The values of various performance parameters of the liquid crystal compositions obtained in Example 1 and Comparative Example 1 were summarized and compared, see Table 36.

After comparison, it can be seen that compared with Comparative Example 1, the liquid crystal composition provided by Example 1 has lower rotational viscosity, greater optical anisotropy (Δn) and greater elastic constant. Compared with Comparative Example 1, γ1 in Example 1 is reduced by about 17%, Δn is increased by 0.011, and d ² *γ1/K ₂₂ is reduced by about 40%, that is, when used in liquid crystal displays, the response speed can be improved by about 40%. Compared with Comparative Example 1, the Kavg of Example 1 is increased by 0.8, and the increase of _Kavg known in the art can improve the contrast of liquid crystal displays, so the liquid crystal composition provided by the present invention has higher contrast.

It can be seen from the above examples that the liquid crystal composition provided by the present invention has low rotational viscosity, greater optical anisotropy and greater elastic constant, and can effectively improve the response speed and contrast of liquid crystal displays when used in displays. Therefore, the liquid crystal composition provided by the present invention is suitable for liquid crystal display devices, and can significantly improve the response speed and contrast characteristics of the liquid crystal display.

Prepare Host liquid crystal as a matrix, and the specific formula is shown in Table 37.

3PGiWO2 and 3PWP2 were mixed with HOST liquid crystal at a weight ratio of 5%:95% to make mixed liquid crystals, and 3PGiWO2+Host, 3PWP2+Host, and Host were respectively poured into the TN mode test box to test RDC. The specific test method of RDC is: at 60°C, apply 10V DC voltage for 30 minutes, then remove the voltage for 10 minutes and test the residual voltage. The specific experimental results are shown in Table 38:

Experimental results show that 3PGiWO2 and 3PWP2 have lower RDC when used in mixed liquid crystals. According to the above results, the terphenyl-based single crystal represented by the general formula IV can weaken the RDC effect, and is very effective in improving DC-type afterimages and restoring afterimages.

Although the present invention has been described in detail above with general descriptions, specific implementation methods and tests, it will be obvious to those skilled in the art that some modifications or improvements can be made on the basis of the present invention. Therefore, the modifications or improvements made on the basis of not departing from the spirit of the present invention all belong to the protection scope of the present invention.

Claims (10)

A liquid crystal composition containing pyran and terphenyl, characterized in that it includes at least one of the compounds represented by the general formula I, at least one of the compounds represented by the general formula II, at least one of the compounds represented by the general formula III, and at least one of the compounds represented by the general formula IV;

Wherein, in general formula I, L ₁ represents S or O; R ₁ represents C ₁ ~C ₁₂ straight-chain alkyl,

In the general formula II, R ₂ and R ₃ each independently represent a C ₁ ~C ₁₂ straight chain alkyl group, a C ₁ ~C ₁₂ straight chain alkoxy group or a C ₂ ~C ₁₂ straight chain alkenyl group; a represents 0 or 1; A ₁ represents

,

or

In the general formula III, R ₄ and R ₅ each independently represent a C ₁ ~C ₁₂ straight chain alkyl group, a C ₁ ~C ₁₂ straight chain alkoxy group or a C ₂ ~C ₁₂ straight chain alkenyl group; In the general formula IV, R ₆ and R ₇ each independently represent a C ₁ -C ₁₂ linear alkyl group, a C ₁ -C ₁₂ linear alkoxy group or a C ₂ -C ₁₂ linear alkenyl group; L ₂ , L ₃ , and L ₄ each independently represent H or F. The liquid crystal composition containing pyran and terphenyl as described in claim 1, wherein the compound represented by general formula I is selected from one or more of formula I-1 to formula I-22:

The liquid crystal composition containing pyran and terphenyl as described in claim 1, wherein the compound represented by general formula II is selected from one or more of formula IIA~formula IIF:

Wherein, R ₂ and R ₃ each independently represent a C ₁ -C ₇ linear alkyl group, a C ₁ -C ₇ linear alkoxy group or a C ₂ -C ₇ linear alkenyl group. The liquid crystal composition containing pyran and terphenyl as described in Claim 1, wherein the compound represented by the general formula III is selected from one or more of the formulas IIIA to IIIB;

Wherein, R ₄ and R ₅ each independently represent a C ₁ -C ₇ straight-chain alkyl group or a C ₂ -C ₇ straight-chain alkenyl group. The liquid crystal composition containing pyran and terphenyl as described in Claim 1, wherein the compound represented by the general formula IV is selected from one or more of the formulas IVA to IVB:

Among them, R ₆ represents C ₁ ~ C ₇ straight chain alkyl or C ₂ ~ C ₇ straight chain alkenyl; R ₇ represents C ₁ ~ C ₇ straight chain alkyl or C ₁ ~ C ₇ straight chain alkoxy. The liquid crystal composition containing pyran and terphenyl according to any one of claims 1 to 5, wherein the liquid crystal composition further includes at least one of the compounds represented by the general formula V;

Wherein, R ₈ and R ₉ each independently represent a C ₁ ~C ₁₂ straight chain alkyl group, a C ₁ ~C ₁₂ straight chain alkoxy group or a C ₂ ~C ₁₂ straight chain alkenyl group; A ₂ , A ₃ each independently represent trans 1,4-cyclohexyl or 1,4-phenylene. The liquid crystal composition containing pyran and terphenyl as described in claim 6, wherein the liquid crystal composition further includes at least one of the compounds represented by the general formula VI;

Wherein, R ₁₀ and R ₁₁ each independently represent a C ₁ -C ₁₂ linear alkyl group, a C ₁ -C ₁₂ linear alkoxy group or a C ₂ -C ₁₂ linear alkenyl group; A ₄ represents trans 1,4-cyclohexyl or 1,4-phenylene. The liquid crystal composition containing pyran and terphenyl as described in Claim 7, wherein the liquid crystal composition comprises the following components in mass percentage: (1), 1-50% of the compound represented by the general formula I; (2), 5-70% of the compound represented by the general formula II; (3), 1-40% of the compound represented by the general formula III; (4), 1-50% of the compound represented by the general formula IV; (5), 0-70% of the compound represented by the general formula V; 6), the compound represented by the general formula VI of 0～50%. The liquid crystal composition containing pyran and terphenyl as described in Claim 8, wherein the liquid crystal composition comprises the following components in mass percentage: (1), 1-30% of the compound represented by the general formula I; (2), 10-70% of the compound represented by the general formula II; (3), 3-30% of the compound represented by the general formula III; (4), 1-30% of the compound represented by the general formula IV; (5), 10-60% of the compound represented by the general formula V (6), the compound represented by the general formula VI of 0～35%. An application of a liquid crystal composition in a liquid crystal display, comprising the liquid crystal composition described in any one of claims 1 to 9.