TWI662110B - Liquid crystal composition and display device - Google Patents

Abstract

The invention discloses a liquid crystal composition and a display device thereof. The liquid crystal composition includes at least one compound of the general formula I. The invention also discloses a liquid crystal display device including the liquid crystal composition of the invention. The liquid crystal composition provided by the present invention simultaneously has the characteristics of high absolute value of negative dielectric anisotropy, high optical anisotropy, good low-temperature stability, and fast response speed. The liquid crystal comprising the liquid crystal composition of the present invention The display can meet the needs of low-voltage driving and fast response.

Description

Liquid crystal composition and display device

The present invention relates to the field of liquid crystal materials, and particularly to a liquid crystal composition having negative dielectric anisotropy and a display device thereof.

The liquid crystal display element can be used in various household appliances such as clocks and electronic calculators, measuring devices, automobile panels, word processors, computers, printers, televisions, and the like. According to the type of display mode, it is divided into PC (phase change), TN (twist nematic, twisted nematic), STN (super twisted nematic, super twisted nematic), ECB (electrically controlled birefringence), OCB (optically compensated bend), IPS (in-plane switching), VA (vertical alignment) and other types. According to the driving mode of the device, it is divided into a PM (passive matrix) type and an AM (active matrix) type. PM is divided into static and multiplex types. AM is divided into TFT (thin film transistor, thin film transistor), MIM (metal insulator metal, metal-insulating layer-metal) and other types. The types of TFTs are amorphous silicon and polycrystal silicon. The latter is divided into high temperature type and low temperature type according to the manufacturing process. Liquid crystal display elements are classified into a reflection type using natural light, a transmission type using backlight, and a semi-transmission type using two types of light sources, natural light and backlight, according to the type of light source.

Among these display modes, IPS mode, ECB mode, VA mode, or CSH The mode and the like are different from the TN mode or the STN mode in common use now that the former uses a liquid crystal material having negative dielectric anisotropy. In these display modes, especially the VA mode has a very good dark state contrast compared to the ordinary TN mode, and the contrast depends less on the birefringence of the liquid crystal, the thickness of the liquid crystal layer, and the wavelength of the incident light. It also performs well in wide viewing angles. In addition, in the VA mode, the rubbing process can be omitted to increase the yield. For the VA display mode, the liquid crystal composition is often required to have a larger absolute value of the negative dielectric anisotropy, and it also needs to have a higher clearing point, a lower threshold voltage, and a faster response time. Has good low temperature stability.

However, in the prior art, it is difficult to obtain a liquid crystal composition having both a large optical anisotropy, a large absolute negative dielectric anisotropy, a good low-temperature stability, and a rapid response. A liquid crystal composition having a large absolute value of dielectric anisotropy has a high critical voltage, high power consumption, and relatively slow response speed. Therefore, in order to meet the increasing demand for applications, the memory in the art is continuously improving the liquid crystal compounds with negative dielectric anisotropy.

Object of the invention: In view of the defects of the prior art, an object of the present invention is to provide a liquid crystal composition having a large optical anisotropy, a large absolute negative dielectric anisotropy, a good low-temperature stability, and a fast response, and a display thereof Device.

Technical solution of the present invention: a liquid crystal composition comprising: at least one compound of the general formula I Wherein, R ₁ and R ₂ each independently represent an alkyl or alkoxy group having 1 to 12 carbon atoms or an alkenyl or alkoxy group having 2 to 12 carbon atoms, wherein the alkyl or alkoxy group -CH _{2-, which is} not adjacent to one or more of the alkenyl group or the alkenyloxy group, may be each independently replaced by -O- in such a manner that oxygen atoms are not directly connected.

Further, in some embodiments of the present invention, the compound of the general formula I accounts for 1 to 35 wt% of the total weight of the liquid crystal composition.

Still further, in some embodiments of the present invention, the compound of the general formula I accounts for 5-30 wt% of the total weight of the liquid crystal composition.

Further, in some embodiments of the present invention, R ₂ represents an alkoxy group containing 1 to 12 carbon atoms or an alkenyl group containing 2 to 12 carbon atoms, and the alkoxy group containing 1 to 12 carbon atoms One or more non-adjacent -CH ₂ -groups of an oxy group or an alkenyl group containing 2 to 12 carbon atoms may be independently replaced by -O- each in a manner that the oxygen atoms are not directly connected.

Further, in some embodiments of the present invention, the liquid crystal composition includes at least two compounds of the general formula I.

Further, in some embodiments of the present invention, the compound of the general formula I is selected from compounds of the general formula Ia:

Among them, R ₃ represents an alkyl group containing 1 to 7 carbon atoms or an alkenyl group containing 2 to 7 carbon atoms; n represents an integer of 2 to 6.

Still further, in some embodiments of the present invention, the general formula I-a The compound accounts for 1 to 35 wt% of the total weight of the liquid crystal composition.

Still further, in some embodiments of the present invention, the compound of the general formula I is selected from the group consisting of the following compounds:

Among them, R ₃ represents an alkyl group containing 1 to 7 carbon atoms or an alkenyl group containing 2 to 7 carbon atoms; n represents an integer of 2 to 6.

Still further, in some embodiments of the present invention, the compound of the general formula I is selected from the group consisting of the general formulae I-1 to I-12, and the compound of the general formula I accounts for the liquid crystal composition. 1-35 wt% of the total weight.

Furthermore, in some embodiments of the present invention, the compound of the general formula I is selected from the group consisting of the aforementioned general formulas I-1 to I-12, and the compound of the general formula I accounts for the liquid crystal composition. 5-30wt% of the total weight.

Further, in some embodiments of the present invention, it further comprises at least one compound of the general formula II Wherein, R ₄ and R ₅ each independently represent an alkyl or alkoxy group containing 1 to 12 carbon atoms or an alkenyl or alkoxy group containing 2 to 12 carbon atoms, wherein the alkyl or alkoxy group And one or more non-adjacent -CH ₂ -groups in the alkenyl group or alkenyloxy group may be independently replaced by -O- in a manner that oxygen atoms are not directly connected; a ring Express or , Said One or more of -CH ₂ -may be replaced by -O-, said One or more of H may be replaced by F; Z ₁ represents a single bond, -CH ₂ O-, -CF ₂ O-, or -COO-; m represents 0 or 1.

Further, the compound of the general formula II is selected from the group consisting of the following compounds: Wherein, R ₄₁ and R ₅₁ each independently represent an alkyl or alkoxy group having 1 to 7 carbon atoms or an alkenyl or alkoxy group having 2 to 7 carbon atoms, wherein the alkyl or alkoxy group -CH _{2-, which is} not adjacent to one or more of the alkenyl group or the alkenyloxy group, may be each independently replaced by -O- in such a manner that oxygen atoms are not directly connected.

Still further, the compound of the general formula II-1 is selected from the group consisting of the following compounds:

The compound of the general formula II-2 is selected from the group consisting of the following compounds:

The compound of the general formula II-3 is selected from the group consisting of the following compounds:

The compound of the general formula II-4 is selected from the group consisting of the following compounds:

The compound of the general formula II-5 is selected from the group consisting of the following compounds:

The compound of the general formula II-6 is selected from the group consisting of the following compounds:

Further, in some embodiments of the present invention, it further comprises at least one compound of the general formula III

Wherein, R ₆ and R ₇ each independently represent an alkyl or alkoxy group having 1 to 12 carbon atoms or an alkenyl or alkoxy group having 2 to 12 carbon atoms, wherein the alkyl or alkoxy group And one or more non-adjacent -CH ₂ -groups in the alkenyl group or alkenyloxy group may be independently replaced by -O- in a manner that oxygen atoms are not directly connected; a ring And ring Independent representation or Z ₂ represents a single bond, -CH ₂ O-, -CF ₂ O-, or -COO-; p represents 0 or 1.

Further, the compound of the general formula III is selected from the group consisting of the following compounds: Among them, R ₆₁ and R ₇₁ each independently represent an alkyl or alkoxy group having 1 to 7 carbon atoms or an alkenyl or alkoxy group having 2 to 7 carbon atoms, wherein the alkyl or alkoxy group -CH _{2-, which is} not adjacent to one or more of the alkenyl group or the alkenyloxy group, may be each independently replaced by -O- in such a manner that oxygen atoms are not directly connected.

Still further, the compound of the general formula III-1 is selected from the group consisting of the following compounds:

The compound of the general formula III-2 is selected from the group consisting of the following compounds:

The compound of the general formula III-3 is selected from the group consisting of the following compounds:

The compound of the general formula III-4 is selected from the group consisting of the following compounds:

A liquid crystal display device comprising the above liquid crystal composition.

Further, the liquid crystal composition further comprises one or more additives known to those skilled in the art and described in the literature.

The following mentions, for example, stabilizers which can be added to the mixture according to the invention.

Preferably, the stabilizer is selected from the stabilizers shown below.

In the embodiment of the present invention, preferably, the stabilizer accounts for 0-5 wt% of the total weight of the liquid crystal composition; more preferably, the stabilizer accounts for 0-1 wt% of the total weight of the liquid crystal composition. ; As a particularly preferred solution, the stabilizer accounts for the total weight of the liquid crystal composition 0.01-0.1wt%.

According to another aspect of the present invention, a liquid crystal display is provided, which includes the liquid crystal composition provided by the present invention.

The liquid crystal composition provided by the present invention simultaneously has the characteristics of high absolute value of negative dielectric anisotropy, high optical anisotropy, good low-temperature stability, and fast response speed. The liquid crystal comprising the liquid crystal composition of the present invention The display can meet the needs of low-voltage driving and fast response.

The present invention will be described below with reference to specific embodiments. It should be noted that the following embodiments are examples of the present invention, and are only used to illustrate the present invention, but not to limit the present invention. Other combinations and various modifications within the concept of the present invention may be made without departing from the spirit or scope of the present invention.

Unless otherwise specified in the present invention, the ratios are all weight ratios, and all temperatures are in degrees Celsius.

For ease of expression, in the following examples, the group structure of the liquid crystal composition is represented by the codes listed in Table 1:

Take a compound of the following structural formula as an example:

If the structural formula is expressed by the codes listed in Table 1, it can be expressed as: nCCGF, n in the code represents the number of C atoms of the left alkyl group, for example, n is "3", which means that the alkyl group is -C ₃ H ₇ ; C in the code represents cyclohexane, G represents 2-fluoro-1,4-phenylene, and F represents fluorine.

The abbreviated code of the test project in the following examples is as follows: Cp (° C) Clearing point (nematic-isotropic phase transition temperature)

△ n optical anisotropy (589nm, 25 ℃)

△ ε dielectric anisotropy (1KHz, 25 ℃)

γ1 Rotational viscosity (mPa * s, at 25 ° C)

t (-30 ℃) Low-temperature storage time (h, at -30 ℃)

Among them, the optical anisotropy was measured using an Abbe refractometer under a sodium light (589 nm) light source at 25 ° C.

△ ε = ε _∥ -ε _⊥ , where ε _∥ is the dielectric constant parallel to the molecular axis, ε _⊥ is the dielectric constant perpendicular to the molecular axis, test conditions: 25 ° C, 1KHz, test box is TN90 type, box 7 μm thick.

γ1 was obtained by testing using a TOYO6254 liquid crystal physical property evaluation system; the test temperature was 25 ° C and the test voltage was 90V.

Each component used in the following examples can be synthesized by a known method, or can be obtained through a commercial route. These synthetic techniques are conventional, and the resulting liquid crystal compounds have been tested to comply with electronic compound standards.

A liquid crystal composition was prepared according to the compounding ratio of each liquid crystal composition specified in the following examples. The preparation of the liquid crystal composition is performed according to a conventional method in the art, for example, heating, ultrasonic wave, suspension, etc. are used to prepare the liquid crystal composition according to a prescribed ratio.

The liquid crystal compositions given in the following examples were prepared and studied. The composition and performance parameter test results of each liquid crystal composition are shown below.

Comparative Example 1

The liquid crystal composition of Comparative Example 1 was formulated according to the compounds and weight percentages listed in Table 2. The liquid crystal composition was filled between two substrates of a liquid crystal display for performance testing. The test data is shown in the following table: Table 2 Liquid crystal composition formula and Its test performance

Example 1

The liquid crystal composition of Example 1 was prepared according to the compounds and weight percentages listed in Table 3, which was filled between two substrates of the liquid crystal display for performance testing. The test data is shown in the following table:

Example 2

The liquid crystal composition of Example 2 was formulated according to the compounds and weight percentages listed in Table 4, which was filled between the two substrates of the liquid crystal display for performance testing. The test data is shown in the following table:

Example 3

The liquid crystal composition of Example 3 was prepared according to the compounds and weight percentages listed in Table 5. The liquid crystal composition was filled between two substrates of a liquid crystal display for performance testing. The test data is shown in the following table:

Example 4

The liquid crystal composition of Example 4 was formulated according to the compounds and weight percentages listed in Table 6, which was filled between the two substrates of the liquid crystal display for performance testing. The test data is shown in the following table:

Example 5

The liquid crystal composition of Example 5 was prepared according to the compounds and weight percentages listed in Table 7. The liquid crystal composition was filled between two substrates of a liquid crystal display for performance testing. The test data is shown in the following table: Table 7 Liquid crystal composition formula and Its test performance

From the data of the above examples, it can be known that the liquid crystal composition provided by the present invention has the characteristics of high absolute negative dielectric anisotropy, high optical anisotropy, good low-temperature stability, and fast response speed. The liquid crystal display containing the liquid crystal composition of the present invention can meet the requirements of low voltage driving and fast response.

The above embodiments are only for explaining the technical concept and characteristics of the present invention, and the purpose thereof is to let those familiar with the technology understand and implement the content of the present invention, but not to limit the protection scope of the present invention. Equivalent changes or modifications should be covered within the scope of protection of the present invention.

Claims (10)

A liquid crystal composition comprising: at least one compound of the general formula I Wherein, R ₁ and R ₂ each independently represent an alkyl or alkoxy group having 1 to 12 carbon atoms or an alkenyl or alkoxy group having 2 to 12 carbon atoms, wherein the alkyl or alkoxy group And one or more non-adjacent -CH ₂ -groups in the alkenyl group or the alkenyloxy group may be independently replaced by -O- in a manner that oxygen atoms are not directly connected, and the compound of the general formula I contains at least one From Wherein R ₃ represents an alkyl group having 1 to 7 carbon atoms or an alkenyl group containing 2 to 7 carbon atoms; and n represents an integer of 2-6. The liquid crystal composition according to item 1 of the scope of the patent application, wherein R ₂ represents an alkoxy group containing 1-12 carbon atoms or an alkenyl group containing 2-12 carbon atoms, and the group contains 1-12 One or more non-adjacent -CH ₂ -groups of the alkoxy group of the carbon atom or the alkenyl group containing 2 to 12 carbon atoms may be independently replaced by -O- each in a manner that the oxygen atoms are not directly connected. The liquid crystal composition according to item 2 of the patent application scope, wherein the liquid crystal composition comprises at least two compounds of the general formula I. The liquid crystal composition according to item 3 of the scope of application for a patent, wherein the compound other than the general formula Ia in the general formula I is selected from the group consisting of the following compounds: The liquid crystal composition according to item 1 of the patent application range, wherein the compound of the general formula I accounts for 1 to 35 wt% of the total weight of the liquid crystal composition. The liquid crystal composition according to item 5 of the scope of patent application, wherein the compound of the general formula I accounts for 5-30% by weight of the total weight of the liquid crystal composition. The liquid crystal composition according to item 1 of the scope of the patent application, wherein the compound of the general formula I-a accounts for 1 to 35 wt% of the total weight of the liquid crystal composition. The liquid crystal composition according to item 7 of the patent application scope, further comprising at least one compound of the general formula II Wherein, R ₄ and R ₅ each independently represent an alkyl or alkoxy group having 1 to 12 carbon atoms or an alkenyl or alkoxy group having 2 to 12 carbon atoms, wherein the alkyl or alkoxy group And one or more non-adjacent -CH ₂ -groups in the alkenyl group or alkenyloxy group may be independently replaced by -O- in a manner that oxygen atoms are not directly connected; Express or , Said One or more of -CH ₂ -may be replaced by -O-, said One or more of H may be substituted by F; Z ₁ represents a single bond, -CH ₂ O-, -CF ₂ O-, or -COO-; and m represents 0 or 1. The liquid crystal composition according to item 1 of the patent application scope, further comprising at least one compound of the general formula III Wherein, R ₆ and R ₇ each independently represent an alkyl or alkoxy group having 1 to 12 carbon atoms or an alkenyl or alkoxy group having 2 to 12 carbon atoms, wherein the alkyl or alkoxy group And one or more non-adjacent -CH ₂ -groups in the alkenyl group or alkenyloxy group may be independently replaced by -O- in a manner that oxygen atoms are not directly connected; And ring Independent representation or Z ₂ represents a single bond, -CH ₂ O-, -CF ₂ O-, or -COO-; p represents 0 or 1. A liquid crystal display device comprising the liquid crystal composition according to any one of claims 1 to 9 of the scope of patent application.