Liquid crystal composition adaptable to a relatively wide operating temperature range and use thereof in devices

Abstract

The present invention relates to a liquid crystal composition and a method for preparing the same that can be used over a relatively wide operating temperature range. The liquid crystal composition is prepared by blending compounds represented by general formulas I, II, III, IV, V, VI, VII, and VIII as raw materials in appropriate ratios to obtain a final liquid crystal composition. The liquid crystal composition simultaneously contains polycyclic, alkynyl, cyano, and ester compounds, and has a high clearing point, large optical anisotropy, a relatively wide operating temperature range, and is suitable for high-temperature environments. The liquid crystal composition of the present invention can be used in a variety of display devices, particularly PDLC devices.

Description

[Technical field]

[0001] The present invention relates to the field of liquid crystal material technology, and in particular to liquid crystal compositions adaptable to a relatively wide operating temperature range and their application in liquid crystal display devices. [Background technology]

[0002] An LCD display is a display that uses liquid crystal as its material. Liquid crystal is an organic compound that is somewhere between a solid and a liquid. When heated, it becomes a transparent liquid, and when cooled, it becomes a crystalline, cloudy solid. An electric field changes the arrangement of the liquid crystal molecules, which affects the change in light passing through it. This change in light can be expressed as a change in brightness by a polarizing plate. In this way, by controlling the electric field, the change in brightness of the light can ultimately be controlled, achieving the purpose of displaying an image.

[0003] In recent years, the application field of liquid crystal compounds has been greatly expanded to various display devices, electro-optical devices, electronic components, sensors, etc. For this reason, many different structures have been proposed, and in particular, in the field of nematic liquid crystals, nematic liquid crystal compounds have been widely applied in the fields of flat panel displays and light control. People's demands for display technology are also increasing, especially in terms of achieving a wide operating temperature, high-speed response, and reduced driving voltage for reduced power consumption. The liquid crystal composition provided by the present invention has the characteristics of having a large optical anisotropy and a high clearing point, and realizes the effect of effectively expanding the operating temperature range. Summary of the Invention

[0004] In order to solve the above problems in the prior art, the present invention provides a liquid crystal composition having large optical anisotropy and a wide temperature range and its application in liquid crystal display devices. The liquid crystal composition of the present invention is a nematic liquid crystal composition, which has large optical anisotropy and at the same time has a high clearing point, and effectively expands the operating temperature range.

[0005] The technical solutions adopted in the present invention are as follows: A liquid crystal composition that can be adapted to a relatively wide operating temperature range, and the raw material components are 1 to 20 parts by weight of a compound represented by general formula I; 15 to 70 parts by weight of a compound represented by general formula II; 0 to 15 parts by weight of a compound represented by general formula III; 0 to 20 parts by weight of a compound having the general formula IV; 1 to 40 parts by weight of a compound having the general formula V; 1 to 40 parts by weight of a compound represented by the general formula VI; 1 to 20 parts by weight of a compound represented by general formula VII; 1 to 20 parts by weight of a compound having general formula VIII; The structures of the above eight compounds are as follows: The structure of the compound having the general formula I is as follows: JPEG0007604494000001.jpg15170R1 and R2 each independently represent an alkyl group having 1 to 7 carbon atoms or an alkenyl group having 2 to 7 carbon atoms; The structure of the compound having the general formula II is as follows: JPEG0007604494000002.jpg23170R3 and R4 each independently represent an alkyl group having 1 to 7 carbon atoms or an alkenyl group having 2 to 7 carbon atoms; The structure of the compound having the general formula III is as follows: JPEG0007604494000003.jpg16170R5 represents an alkoxy group having 1 to 7 carbon atoms, R6 represents an alkyl group having 1 to 7 carbon atoms or an alkenyl group having 2 to 7 carbon atoms, The structure of the compound having the general formula IV is as follows: JPEG0007604494000004.jpg21170R7 represents an alkyl group having 1 to 7 carbon atoms or an alkenyl group having 2 to 7 carbon atoms; The structure of the compound having the general formula V is as follows: JPEG0007604494000005.jpg20170R8 represents an alkyl group having 1 to 7 carbon atoms or an alkenyl group having 2 to 7 carbon atoms; The structure of the compound having the general formula VI is as follows: JPEG0007604494000006.jpg16170R9, R 10 each independently represents an alkyl group having 1 to 7 carbon atoms or an alkenyl group having 2 to 7 carbon atoms, The structure of the compound having the general formula VII is as follows: JPEG0007604494000007.jpg16170R 11 represents an alkoxy group having 1 to 7 carbon atoms, R 12 represents an alkyl group having 1 to 7 carbon atoms or an alkenyl group having 2 to 7 carbon atoms, The structure of the compound having the general formula VIII is as follows: JPEG0007604494000008.jpg15170R 13 , R 14 each independently represents an alkyl group having 1 to 7 carbon atoms or an alkenyl group having 2 to 7 carbon atoms.

[0006] More preferably, the raw material components of the liquid crystal composition are 3 to 15 parts by weight of a compound represented by general formula I; 25 to 60 parts by weight of a compound represented by general formula II; 1 to 15 parts by weight of a compound represented by formula III; 1 to 15 parts by weight of a compound having the general formula IV; 5 to 30 parts by weight of a compound having the general formula V; 5 to 30 parts by weight of a compound represented by the general formula VI; 3 to 18 parts by weight of a compound represented by general formula VII; and 2 to 15 parts by weight of a compound represented by general formula VIII.

[0007] More preferably, the raw material components of the liquid crystal composition are 4 to 10 parts by weight of a compound represented by general formula I; 35 to 50 parts by weight of a compound represented by general formula II; 2 to 10 parts by weight of a compound represented by general formula III; 2 to 10 parts by weight of a compound represented by general formula IV; 10 to 20 parts by weight of a compound having the general formula V; 8 to 25 parts by weight of a compound represented by the general formula VI; 8 to 15 parts by weight of a compound having general formula VII; and 3 to 10 parts by weight of a compound represented by general formula VIII.

[0008] More preferably, the raw material components of the liquid crystal composition are 6 parts by weight of a compound of general formula I; 40 parts by weight of a compound of general formula II; 3 parts by weight of a compound of general formula III; 8 parts by weight of a compound of general formula IV; 16 parts by weight of a compound having the general formula V; 12 parts by weight of a compound of general formula VI; 12 parts by weight of a compound having general formula VII; 3 parts by weight of a compound having general formula VIII.

[0009] The compound having the general formula I is a compound containing an alkynyl group, and the compound has a fast response speed, and the compound having the general formula I is selected from one or more of the compounds represented by the following formulas IA-ID: JPEG0007604494000009.jpg72170The compound having the general formula II is a compound containing an alkynyl group and fluorine, and this compound has a fast response speed. The compound having the general formula II is selected from one or more of the compounds represented by the following formulas IIA to IIC: JPEG0007604494000010.jpg75170The compound having the general formula III is a compound containing a two-ring structure, and this compound has relatively good low-temperature compatibility. The compound having the general formula III is selected from one or more of the compounds represented by the following formulas IIIA to IIIE: The compound having the general formula IV is a compound containing a two-ring structure, and has a large positive dielectric anisotropy. The compound having the general formula IV is selected from one or more of the compounds represented by the following formulas IVA to IVD: The compound having the general formula V is a compound containing a three-ring cyano structure, and has a relatively high clearing point and a large positive dielectric anisotropy. The compound having the general formula V is selected from one or more of the compounds represented by the following formulas VA to VD: The compound having the general formula VI is a compound containing a bicyclic ester group structure, and has very good low-temperature compatibility. The compound having the general formula VI is selected from one or more of the compounds represented by the following formulas VIA to VIC: JPEG0007604494000014.jpg55170The compound having the general formula VII is a compound containing a bicyclic ester group structure, and this compound has very good low-temperature compatibility. The compound having the general formula VII is selected from one or more of the compounds represented by the following formulas VIIA to VIIE: JPEG0007604494000015.jpg91170The compound having the general formula VIII is a compound containing a four-ring structure, and the compound has a high clearing point.The compound having the general formula VIII is selected from one or more of the compounds represented by the following formulas VIIIA to VIIIF. JPEG0007604494000016.jpg95170

[0010] More preferably, the raw material components of the liquid crystal composition further contain 0.1 to 0.5 parts by mass of an ultraviolet absorbing agent.

[0011] The ultraviolet absorber is one or a mixture of benzotriazoles, benzophenones, triazines, and parabens.

[0012] More preferably, the raw material components of the liquid crystal composition further contain 0.01 to 0.05 parts by mass of an antioxidant.

[0013] The antioxidants are one or more mixtures of hindered phenols, phosphites, and combinations of hindered phenols and phosphites.

[0014] The method for preparing the liquid crystal composition includes the steps of taking each raw material component, adding them in order from the highest melting point to the lowest, dissolving them under heating and stirring conditions, mixing them thoroughly to make them homogeneous, filtering and removing impurities, and then obtaining the liquid crystal composition.

[0015] The heating temperature is 60 to 100°C.

[0016] The preparation method of the liquid crystal composition of the present invention is not particularly limited, and it can be produced by mixing two or more compounds by a conventional method. For example, it can be prepared by a method of mixing different components at a high temperature of 60 to 100 ° C and dissolving them in each other. Here, the liquid crystal composition is dissolved in a solvent 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 a conventional method. For example, a component with a low content is dissolved in a main component with a high content at a higher temperature, or each component is dissolved in an organic solvent such as acetone, chloroform, or methanol, and then the solutions are mixed to remove the solvent, and then the liquid crystal composition is obtained.

[0017] Use of said liquid crystal composition in a liquid crystal display.

[0018] The beneficial effects of the present invention are as follows: The liquid crystal composition of the present invention is prepared by using the compound represented by formula I, the compound represented by formula II, the compound represented by formula III, the compound represented by formula IV, the compound represented by formula V, the compound represented by formula VI, the compound represented by formula VII, and the compound represented by formula VIII as raw materials, and mixing them in an appropriate ratio to finally obtain a liquid crystal composition. The liquid crystal composition simultaneously contains polycyclic, alkynyl, alkynyl cyano, and ester compounds, and has the characteristics of a high clearing point and large optical anisotropy, and has a relatively wide operating temperature range, and can be adapted to high temperature environmental conditions. The liquid crystal composition of the present invention can be applied to various display devices, particularly to PDLC devices. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] The present invention will now be described in detail with reference to specific examples. The following examples are provided to illustrate the present invention and are not intended to limit the scope of the present invention.

[0020] Unless otherwise specified, percentages in the present invention are weight percentages. Temperature units are degrees Celsius. Δn represents optical anisotropy (25°C). Δε (Δε=ε∥-ε⊥) represents dielectric anisotropy (25°C, 1000Hz), and ε∥ and ε⊥ represent parallel and perpendicular dielectric constants (25°C, 1000Hz), respectively. η represents bulk viscosity (mPa·s, 25°C). Cp represents the clearing point (°C) of the liquid crystal composition.

[0021] In the following examples, the group structures in the liquid crystal compounds are represented by the codes shown in Table 1.

[0022] Table 1 - Group structure codes for liquid crystal compounds JPEG0007604494000017.jpg148170

[0023] Take the following compound structure as an example: JPEG0007604494000018.jpg23170 is represented as 3PGUQUF. JPEG0007604494000019.jpg23170 is represented as V2PZUCN.

[0024] In each of the following examples, the weight percentage of each raw material component of the liquid crystal composition and the performance parameters of the liquid crystal composition are shown in the following table.

[0025] In the following examples, the preparation of the liquid crystal compositions all adopts the hot dissolution method and includes the following steps: Use a balance to weigh out the liquid crystal compounds by weight percentage; There is no special requirement for the order of weighing and adding; Usually, the liquid crystal compounds are weighed and mixed in order from high to low melting point, and then heated and stirred at 60-100°C to dissolve each component uniformly; Then, the target sample is obtained through filtration, rotary evaporation, and final packaging. Example 1

[0026] Table 2 - Weight percentage of each component in the liquid crystal composition and performance parameters of the liquid crystal compound JPEG0007604494000020.jpg86170 <Example 2>

[0027] Table 3 - Weight percentage of each component in the liquid crystal composition and performance parameters of the liquid crystal compound JPEG0007604494000021.jpg85170 <Example 3>

[0028] Table 4 - Weight percentage of each component in the liquid crystal composition and performance parameters of the liquid crystal compound JPEG0007604494000022.jpg84170 <Example 4>

[0029] Table 5 - Weight percentage of each component in the liquid crystal composition and performance parameters of the liquid crystal compound The method for preparing the liquid crystal compound of this embodiment is the same as that of the first embodiment. Example 5

[0030] Table 6 - Weight percentage of each component in the liquid crystal composition and performance parameters of the liquid crystal compound The method for preparing the liquid crystal compound of this embodiment is the same as that of the first embodiment. Example 6

[0031] Table 7 - Weight percentage of each component in the liquid crystal composition and performance parameters of the liquid crystal compound The method for preparing the liquid crystal compound of this embodiment is the same as that of the first embodiment. Example 7

[0032] Table 8 - Weight percentage of each component in the liquid crystal composition and performance parameters of the liquid crystal compound The method for preparing the liquid crystal compound of this embodiment is the same as that of the first embodiment. Example 8

[0033] Table 9 - Weight percentage of each component in the liquid crystal composition and performance parameters of the liquid crystal compound The method for preparing the liquid crystal compound of this embodiment is the same as that of the first embodiment. Example 9

[0034] Table 10 - Weight percentage of each component in the liquid crystal composition and performance parameters of the liquid crystal compound The method for preparing the liquid crystal compound of this embodiment is the same as that of the first embodiment. Example 10

[0035] Table 11 - Weight percentages and performance parameters of each component in the liquid crystal composition The method for preparing the liquid crystal compound of this embodiment is the same as that of the first embodiment. Example 11

[0036] The only difference between this embodiment and Example 1 is that the raw material components further contain an ultraviolet absorbent V001. The other raw material components and the method for preparing the liquid crystal compound are all the same as those in Example 1.

[0037] The raw material components of the liquid crystal composition of this example are shown in Table 12. Table 12 - Amount of each raw material used in liquid crystal compounds JPEG0007604494000030.jpg98170 <Example 12>

[0038] The only difference between this embodiment and Example 1 is that the raw material components further contain a hindered phenol antioxidant 0001. The other raw material components and the preparation method of the liquid crystal compound are all the same as those of Example 1.

[0039] The raw material components of the liquid crystal composition of this example are shown in Table 13. Table 13 - Amount of each raw material used in liquid crystal compounds JPEG0007604494000031.jpg91170〈Comparative example 1〉

[0040] Table 14 - Weight percentage of each component in the liquid crystal composition and performance parameters of the liquid crystal composition The method for preparing the liquid crystal compound of this comparative example was the same as that of Example 1.

[0041] The performance parameters of the liquid crystal compositions obtained in Example 1 and Comparative Example 1 are compared together. See Table 15. Table 15 - Comparison of performance parameters of liquid crystal compositions obtained in Example 1 and Comparative Example 1 JPEG0007604494000033.jpg20170

[0042] As can be seen from Table 15, compared with Comparative Example 1, the optical anisotropy Δn, the dielectric anisotropy Δε, and the bulk viscosity η of the liquid crystal mixture provided in Example 1 are substantially the same, but the clearing point Cp of the liquid crystal mixture provided in Example 1 is higher. This indicates that when the conditions such as driving voltage are similar, the liquid crystal compound of the present invention has a wider temperature operating range and can adapt to high temperature environmental conditions.

[0043] The present invention is not limited to the above-mentioned best embodiment, and anyone can obtain various other forms of products under the teachings of the present invention, but even if any changes are made in its shape or structure, they all have the same or similar technical solutions as those in this application and are included in the protection scope of the present invention.

Claims

1. A liquid crystal composition that can be adapted to a relatively wide operating temperature range, and the raw material components are 6 parts by weight of a compound of general formula I; 40 parts by weight of a compound of general formula II; 3 parts by weight of a compound of general formula III 8 parts by weight of a compound of general formula IV; 16 parts by weight of a compound having the general formula V; 12 parts by weight of a compound of general formula VI; 12 parts by weight of a compound of general formula VII; 3 parts by weight of a compound having general formula VIII, The structures of the above eight compounds are as follows: The structure of the compound having general formula I is as follows: R １ , R ２ each independently represents an alkyl group of 1 to 7 carbon atoms; The structure of the compound having the general formula II is as follows: R ３ , R ４ each independently represents an alkyl group of 1 to 7 carbon atoms; The structure of the compound having the general formula III is as follows: R ５ represents an alkoxy group of 1 to 7 carbon atoms; R ６ represents an alkyl group of 1 to 7 carbon atoms, The structure of the compound having the general formula IV is as follows: R ７ represents an alkyl group of 1 to 7 carbon atoms, The structure of the compound having the general formula V is as follows: R ８ represents an alkyl group of 1 to 7 carbon atoms, The structure of the compound having the general formula VI is as follows: R ９ , R １０ each independently represents an alkyl group of 1 to 7 carbon atoms; The structure of the compound having the general formula VII is as follows: R １１ represents an alkoxy group of 1 to 7 carbon atoms; R １２ represents an alkyl group of 1 to 7 carbon atoms, The structure of the compound having the general formula VIII is as follows: R １３ , R １４ each independently represents an alkyl group having 1 to 7 carbon atoms.

2. The compounds of general formula I are compounds containing an alkynyl group and are selected from one or more of the following compounds: The compound having the general formula II is a compound containing an alkynyl group and fluorine, and is selected from one or more of the following compounds: The compounds of general formula III are compounds containing a bicyclic ring structure and are selected from one or more of the following compounds: The compounds of general formula IV are compounds containing a bicyclic ring structure and are selected from one or more of the following compounds: The compound having the general formula V is a compound containing a tricyclic cyano group structure and is selected from one or more of the following compounds: The compound having the general formula VI is a compound containing a bicyclic ester group structure, and is selected from one or more of the following compounds: The compound having the general formula VII is a compound containing a bicyclic ester group structure, and is selected from one or more of the following compounds:

2. The liquid crystal composition according to claim 1, wherein the compound represented by the general formula VIII is a compound containing a four-ring structure and is selected from one or more of the following compounds:

3. The raw material components further include 0.1 to 0.5 parts by weight of an ultraviolet absorber, 3. The liquid crystal composition according to claim 1, wherein the ultraviolet absorbing agent is one or a mixture of benzotriazoles, benzophenones, triazines, and parabens.

4. The ingredients further include 0.01 to 0.05 parts by weight of an antioxidant; 4. The liquid crystal composition according to claim 1, wherein the antioxidant is one or a mixture of hindered phenols, phosphites, and composite types.

5. A method for preparing the liquid crystal composition according to any one of claims 1 to 4, comprising the steps of: taking each of the raw material components, adding them in order from the one with the highest melting point to the one with the lowest melting point, dissolving them under heating and stirring conditions, thoroughly mixing them to make them homogenous, and then filtering and removing impurities to obtain the liquid crystal composition.

6. 6. The method according to claim 5, wherein the heating temperature is 60 to 100°C.

7. Use of a liquid crystal composition according to any one of claims 1 to 4 in a liquid crystal display.

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