CN108239540B - Liquid crystal composition and display device thereof - Google Patents

Abstract

The invention discloses a liquid crystal composition with negative dielectric anisotropy. The liquid crystal composition comprises: one or more general formulas I-1 accounting for 20-65% of the total weight of the negative liquid crystal composition Compounds of and/or I-2; one or more compounds of formula II accounting for 10-40% of the total weight of the negative liquid crystal composition; accounting for 13-40% of the total weight of the negative liquid crystal composition One or more compounds of formula III; 20-60% of the total weight of the negative liquid crystal composition of one or more compounds of formula IV. The present invention also discloses a liquid crystal display device comprising the liquid crystal composition of the present invention.

Description

Liquid crystal composition and display device thereof

technical field

The invention relates to a liquid crystal composition, in particular to a liquid crystal composition with suitable clearing point, high optical anisotropy, large dielectric anisotropy, good low temperature stability, high transmittance and small A liquid crystal composition having characteristics such as diffusion area, and a liquid crystal display device comprising the liquid crystal composition.

Background technique

Liquid crystal display elements have developed from clocks and calculators to various household electrical equipment, measuring equipment, automotive panels, word processors, electronic notepads, printers, computers, televisions, and the like. Typical liquid crystal display systems include TN (Twisted Nematic) type, STN (Super Twisted Nematic) type, DS (Dynamic Light Scattering) type, GH (Guest Host) type, IPS (In-Plane Switching) type, OCB (Optically Compensated Birefringence) type, ECB (Voltage Controlled Birefringence) type, VA (Vertical Alignment) type, CSH (Color Super Vertical) type or FLC (Ferric Liquid Crystal) type and the like. In addition, as the driving method of the liquid crystal display device, static driving, multiplexing driving, simple matrix method, active matrix (AM) method driven by TFT (Thin Film Transistor), TFD (Thin Film Diode), etc. may be mentioned.

Among these display systems, the IPS type, the ECB type, the VA type, or the CSH type is characterized by a liquid crystal composition exhibiting a negative value of the dielectric anisotropy Δε. Among these display systems, the VA-type display system by AM driving is used for display elements (eg, televisions, etc.) requiring high-speed response and wide viewing angle.

Liquid crystal materials need to have appropriately high dielectric anisotropy, optical anisotropy, and good low temperature mutual solubility and thermal stability. In addition, the liquid crystal material should also have low viscosity and short response time, low threshold voltage and high contrast ratio. The anisotropic performance index of the composition will be further described based on a commercially available liquid crystal display element. The temperature range of the nematic phase correlates with the operating temperature range of the element. The upper limit temperature of the nematic phase is preferably 70°C or higher, and the lower limit temperature of the nematic phase is preferably -10°C or lower. The viscosity of the composition correlates to the response time of the element. In order to display animations in a component, it is preferable for the component to have a short response time. Therefore, it is preferable that the viscosity of the composition is low, and it is more preferable that the viscosity of the composition is low when the temperature is low.

The optical anisotropy of the composition correlates to the contrast of the element. In order to maximize the contrast ratio of the liquid crystal display element, the product (Δn*d) of the optical anisotropy (Δn) of the liquid crystal composition and the thickness (d) of the liquid crystal layer can be designed to be a fixed value. The appropriate product value depends on the type of operation mode. A suitable value for elements such as TN mode is about 0.45 μm. In this case, a composition having a large optical anisotropy is preferable for an element having a small thickness of the liquid crystal layer.

A liquid crystal display element containing a liquid crystal composition having a large absolute value of dielectric anisotropy can lower the base voltage value, lower the driving voltage, and further reduce power consumption.

The liquid crystal display element containing the liquid crystal composition with lower threshold voltage can effectively reduce the power consumption of display, especially in consumables, such as mobile phones, tablet computers and other portable electronic products, which have longer battery life.

The liquid crystal composition with low viscosity can improve the response speed of the liquid crystal display element. When the response speed of the liquid crystal display element is fast, it is suitable for animation display. Moreover, when injecting a liquid crystal composition into a liquid crystal cell of a liquid crystal display element, the injection time can be shortened, and workability|operativity can be improved.

The prior art discloses liquid crystal compositions with low power consumption and fast response, such as patent document CN102858918A, but there are environmental problems in the prior art (such as the use of chlorine-containing compounds), short service life (such as poor UV or thermal stability) , Low contrast (such as whitening of the display screen in sunlight), and cannot take into account the requirements of LCD TVs, tablet computers, etc., proper optical anisotropy, proper dielectric anisotropy, high voltage holding rate, anti-UV stability and high temperature stability The performance balance problem cannot meet all indicators at the same time.

From the perspective of the preparation of liquid crystal materials, the properties of liquid crystal materials are mutually restrained, and the improvement of a certain performance index may change other properties. Therefore, the preparation of liquid crystal materials with suitable properties in all aspects often requires creative work.

Liquid crystal materials are an important part of liquid crystal displays. At present, liquid crystal displays have a large market demand in the world. They are mostly used in electronic and electrical products, but their life cycles are short. There are naturally problems such as waste pollution in the short life cycle. Now that the green environmental protection issue has been paid more and more attention by all walks of life, if it can be controlled from the source, that is, the selection of environmentally friendly and green materials in the modulation process of the liquid crystal material, can be extremely effective. Significantly reduces the environmental cost of disposing of discarded LCD monitors. Therefore, the preparation of liquid crystal materials with suitable performance in all aspects, economical, and green environmental protection often requires more creative work.

As a liquid crystal composition having a negative Δε, JPH08104869A discloses a liquid crystal composition comprising the following liquid crystal compounds II-1-3 and II-3-5 having a 2.3-difluorophenylene skeleton.

In addition, JP2001354967A has disclosed a liquid crystal composition including a liquid crystal compound II-4-5 and a liquid crystal compound III-10, but it requires further high-speed response. However, JP2001354967A pointed out that a liquid crystal composition containing an alkenyl compound such as the above-mentioned III-10 has the disadvantage that display defects such as image retention and display unevenness are likely to occur.

WO2007077872A1 discloses a liquid crystal composition obtained by combining a liquid crystal compound of the formula (B) having a substantially zero Δε with a liquid crystal compound II-1-3 and a liquid crystal compound II-4-5. However, in the manufacturing process of a liquid crystal display element, when injecting a liquid crystal composition into a liquid crystal cell, the compound with a low vapor pressure is volatilized by applying an extremely low pressure, so it is considered that the content of the compound with a low vapor pressure cannot be increased.

Moreover, in the production process of the liquid crystal display panel, when the liquid crystal material is dropped, it is in a very low pressure environment, and the air pressure is generally less than 1 Pa, which will cause the low boiling point substances in the liquid crystal material to volatilize. When the contact area between the liquid crystal material and the environment is larger, the compounds with low vapor pressure will volatilize more. Therefore, the larger diffusion area will lead to the loss of low boiling point substances in the production process of the liquid crystal display panel, and the liquid crystal material cannot be better maintained. nature.

SUMMARY OF THE INVENTION

The object of the present invention is to provide a liquid crystal composition with negative dielectric anisotropy, suitable dielectric anisotropy, suitable rotational viscosity, suitable clearing point, high optical anisotropy, good The liquid crystal composition has the characteristics of low temperature mutual solubility, high voltage holding ratio, good high temperature stability, good ultraviolet performance, high transmittance and small diffusion area. The liquid crystal composition of the present invention avoids the influence of the low pressure environment on the liquid crystal composition in the manufacture of the liquid crystal display panel.

In order to accomplish the above object of the invention, the present invention provides a liquid crystal composition, the liquid crystal composition has negative dielectric anisotropy, which comprises:

20-65% of the total weight of the negative liquid crystal composition of one or more compounds of general formula I-1 and/or I-2

10-40% by weight of the total weight of the negative liquid crystal composition of one or more compounds of formula II

13-40% by weight of the total weight of the negative liquid crystal composition of one or more compounds of general formula III

以及

as well as

20-60% by weight of the total weight of the negative liquid crystal composition of one or more compounds of general formula IV

in,

R ₁ , R ₂ , R ₃ , R ₄ , R ₅ , R ₆ , R ₇ and R ₈ are the same or different, and each independently represents a straight-chain or branched chain halogenated or unsubstituted carbon number of 1 to 12 Halogenated alkyl or alkoxy, straight or branched chain halogenated or unhalogenated alkenyl or alkenyloxy having 2 to 12 carbon atoms;

相同或不同，各自独立地表示

所述

中的一个或多个H原子可被F原子取代；

same or different, each independently

said

One or more H atoms in can be replaced by F atoms;

可以相同或不同。a represents 0, 1 or 2, wherein, when a is 2, the ring

Can be the same or different.

In some embodiments of the present invention, preferably, the R ₁ , R ₂ , R ₃ , R ₄ , R ₅ , R ₆ , R ₇ and R ₈ are the same or different, and each independently represents a carbon number of 1-5 A straight-chain or branched chain halogenated or unhalogenated alkyl or alkoxy group, or a straight-chain or branched chain halogenated or unhalogenated alkenyl or alkenyl group having 2 to 5 carbon atoms It is further preferred that the R ₁ , R ₃ , R ₅ , R ₆ , R ₇ and R ₈ are the same or different, and each independently represents a straight-chain or branched chain halogenated or unsubstituted carbon atom number of 1-5. A halogenated alkyl or alkoxy group, or a straight-chain or branched-chain halogenated or unhalogenated alkenyl or alkenyloxy group having 2 to 5 carbon atoms; further preferably the R ₂ , R ₄ and R ₆ are the same or different, and each independently represents a straight or branched chain halogenated or unhalogenated alkyl or alkoxy group having 1 to 5 carbon atoms; particularly preferably the R ₂ , R ₄ and R ₆ are the same or different, and each independently represents a straight-chain or branched-chain halogenated or unhalogenated alkoxy group having 1 to 5 carbon atoms.

相同或不同，各自独立地表示

所述

中的一个或多个H原子可被F原子取代，其中，所述

中一个或多个H原子可被F原子取代其取代位不相邻。In some embodiments of the invention, it is preferred that the

same or different, each independently

said

One or more H atoms in can be replaced by F atoms, wherein the

One or more H atoms may be replaced by F atoms whose substitution positions are not adjacent.

In some embodiments of the present invention, it is preferred that the compounds of general formula I-1 and/or I-2 account for 30-60% of the total weight of the negative liquid crystal composition; the compound of general formula II accounts for the negative liquid crystal composition. The compound of general formula III accounts for 13-35% of the total weight of the negative liquid crystal composition; the compound of the general formula IV accounts for 20-50% of the total weight of the negative liquid crystal composition.

In some embodiments of the present invention, it is further preferred that the compounds of general formula I-1 and/or I-2 account for 30-50% of the total weight of the negative liquid crystal composition; the compound of general formula II accounts for the negative liquid crystal The total weight of the composition is 10-30%; the compound of general formula III accounts for 13-30% of the total weight of the negative liquid crystal composition; the compound of the general formula IV accounts for 25-50% of the total weight of the negative liquid crystal composition.

In some embodiments of the present invention, it is further preferred that the compounds of general formula I-1 and/or I-2 account for 30-45% of the total weight of the negative liquid crystal composition; the compound of general formula II accounts for the negative liquid crystal The total weight of the composition is 10-20%; the compound of general formula III accounts for 13-20% of the total weight of the negative liquid crystal composition; the compound of the general formula IV accounts for 30-50% of the total weight of the negative liquid crystal composition.

In some embodiments of the present invention, preferably the compound of general formula I-1 is selected from the group consisting of the following compounds:

In some embodiments of the present invention, it is particularly preferred that the compound of general formula I-1 is selected from the group consisting of the following compounds:

In some embodiments of the present invention, preferably the compound of general formula I-1 accounts for 8-25% of the total weight of the negative liquid crystal composition, more preferably 8-23%; further preferably 8-20%, particularly preferably 8-15%.

In some embodiments of the present invention, it is preferred that the compound of formula I-2 is selected from the group consisting of:

In some embodiments of the present invention, it is particularly preferred that the compound of general formula I-2 is selected from the group consisting of:

In some embodiments of the present invention, preferably the compound of general formula I-2 accounts for 15-40% of the total weight of the negative liquid crystal composition, more preferably 15-35%; further preferably 15-30%, particularly preferably 15-26%.

In some embodiments of the present invention, it is preferred that the compound of general formula II is selected from the group consisting of:

In some embodiments of the present invention, it is particularly preferred that the compound of general formula II is selected from the group consisting of:

In some embodiments of the present invention, it is preferred that the compound of general formula III is selected from the group consisting of:

In some embodiments of the present invention, it is particularly preferred that the compound of general formula III is selected from the group consisting of:

In some embodiments of the present invention, preferably, the compound of general formula IV is selected from one or more compounds selected from the group consisting of:

in,

R ₇ and R ₈ are the same or different, and each independently represents an alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, an alkenyl group having 2 to 5 carbon atoms, or an alkenyl group having 2 to 5 carbon atoms. For 2-5 alkenyloxy.

In some embodiments of the present invention, preferably, the compound of general formula IV-1 is selected from one or more compounds selected from the group consisting of the following compounds:

In some embodiments of the present invention, preferably the compound of general formula IV-1 accounts for 20-45% of the total weight of the negative liquid crystal composition, more preferably 25-42%.

In some embodiments of the present invention, preferably, the compound of general formula IV-2 is selected from one or more compounds selected from the group consisting of the following compounds:

In some embodiments of the present invention, preferably, the compound of general formula IV-3 is selected from one or more compounds selected from the group consisting of the following compounds:

In some embodiments of the present invention, preferably, the compound of general formula IV-4 is selected from one or more compounds selected from the group consisting of the following compounds:

In some embodiments of the present invention, preferably, the compound of general formula IV-5 is selected from one or more compounds selected from the group consisting of the following compounds:

In some embodiments of the present invention, preferably, the compound of general formula IV-6 is selected from one or more compounds selected from the group consisting of the following compounds:

Another aspect of the present invention provides a liquid crystal composition with negative dielectric anisotropy, further comprising one or more additives known to those skilled in the art and described in the literature.

Stabilizers which can be added to the mixtures according to the invention, for example, are mentioned below.

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

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

In yet another aspect of the present invention, there is also provided a liquid crystal display, the liquid crystal display comprising the liquid crystal composition provided by the present invention.

By adopting the above-mentioned technical scheme, compared with the prior art, the technical effects obtained by the present invention are:

The negative liquid crystal composition provided by the present invention has suitable dielectric anisotropy, suitable rotational viscosity, suitable clearing point, high optical anisotropy, good low temperature mutual solubility, high voltage holding ratio, The liquid crystal composition has the characteristics of good high temperature stability, good UV performance, high transmittance and small diffusion area. The liquid crystal composition of the present invention avoids the influence of the low pressure environment on the liquid crystal composition in the manufacture of the liquid crystal display panel.

Unless otherwise specified, the ratios described in the present invention are weight ratios, all temperatures are degrees Celsius, and the test temperature for voltage holding ratio (VHR) is 60°C.

Detailed ways

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 inventive concept can be made without departing from the spirit or scope of the inventions.

The liquid crystal displays used in the following embodiments are all negative liquid crystal display devices, with cell thickness d=4 μm, and are composed of polarizers (polarizers), electrode substrates and other parts. The display device is in normally white mode, ie when no voltage difference is applied between the row and column electrodes, the observer observes a white pixel color. The upper and lower polarizer axes on the substrate are at a 90-degree angle to each other. The space between the two substrates is filled with optical liquid crystal material.

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:

Table 1 Group Structure Codes of Liquid Crystal Compounds

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

If the structural formula is represented by the codes listed in Table 2, it can be expressed as: 2PWP3, 2 in the code means the left end is -C ₂ H ₅ , 3 means the right end is -C ₃ H ₇ ; Cyclohexylene; W represents 2,3-difluoro-1,4-phenylene.

The abbreviated code names of the test items in the following examples are as follows:

Δn: Optical anisotropy (589nm, 25°C)

Δε: Dielectric constant anisotropy (1KHz, 25℃)

Cp clearing point (°C, nematic-isotropic phase transition temperature)

T: transmittance (DMS 505 box thickness 6μm)

T-30℃: Low temperature stability (-30℃ storage time)

D: Diffusion area (mm2, 5μL)

Among them, the optical anisotropy was measured using an Abbe refractometer under a sodium lamp (589 nm) light source at 25° C.; the dielectric test cell was a VA type with a cell thickness of 6 μm.

Δε=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℃, 1KHz, the test cell is VA type, the cell thickness 6μm.

Test conditions for transmittance:

The transmittance of the dimming device was tested with DMS 505, and the cell thickness of the dimming device was 6 μm.

The diffusion area refers to the area formed on the glass after 5 μL of liquid crystal is freely diffused on the glass for 2 hours.

The components used in the following examples can be synthesized by known methods or obtained through commercial channels. These synthesis techniques are conventional, and each of the resulting liquid crystal compounds has been tested to meet electronic compound standards.

The liquid crystal compositions were prepared according to the proportions of the liquid crystal compositions specified in the following examples. The preparation of the liquid crystal composition is carried out according to conventional methods in the art, such as heating, ultrasonic waves, suspension, etc., by mixing in a prescribed ratio.

Comparative example 1 (CN103215046A embodiment M53)

The liquid crystal composition of Comparative Example 1 was prepared according to the compounds and weight percentages listed in Table 2, and it was filled between the two substrates of the liquid crystal display for performance testing. The test data are shown in the following table:

Table 2 Liquid crystal composition formula and its test performance

Example 1

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

Table 3 Liquid crystal composition formula and its test performance

Comparing Example 1 and Comparative Example 1, it can be found that the negative liquid crystal composition of the present invention has greater dielectric anisotropy, smaller diffusion area, greater transmittance and better low temperature mutual solubility .

Comparative Example 2 (Example 2 of CN104342165A)

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

Table 4 Liquid crystal composition formula and its test performance

Example 2

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

Table 5 Liquid crystal composition formula and its test performance

Comparing Example 2 and Comparative Example 2, it can be found that the negative liquid crystal composition of the present invention has greater dielectric anisotropy, smaller diffusion area, greater transmittance and better low temperature mutual solubility .

Comparative example 3 (CN105176543A embodiment M98)

The liquid crystal composition of Comparative Example 3 was prepared according to the compounds and weight percentages listed in Table 6, and it was filled between the two substrates of the liquid crystal display for performance testing. The test data are shown in the following table:

Table 6 Liquid crystal composition formula and its test performance

Example 3

The liquid crystal composition of Example 3 is prepared according to the compounds and weight percentages listed in Table 7, and it is filled between the two substrates of the liquid crystal display for performance testing. The test data are shown in the following table:

Table 7 Liquid crystal composition formula and its test performance

Comparing Example 3 and Comparative Example 3, it can be found that the negative liquid crystal composition of the present invention has greater dielectric anisotropy, smaller diffusion area, greater transmittance and better low temperature mutual solubility .

It can be seen from the above comparative examples and examples that the negative liquid crystal composition of the present invention has larger absolute value of dielectric anisotropy, higher optical anisotropy, appropriately higher clearing point, higher penetration The higher dielectric anisotropy and the higher optical anisotropy can make the liquid crystal composition of the present invention suitable for display devices with more cell thickness, more The large transmittance enables the liquid crystal display device using the liquid crystal composition of the present invention to have a clearer display effect in an environment with strong light, and the good low temperature stability enables the liquid crystal composition of the present invention to be applied in a lower temperature environment On the display device used in the liquid crystal display device, and the smaller diffusion area, the liquid crystal composition of the present invention can better keep the composition unchanged during the production process of the liquid crystal display device.

The above embodiments are only intended to illustrate the technical concept and characteristics of the present invention, and their purpose is to allow those who are familiar with the technology to understand the content of the present invention and implement it, and cannot limit the scope of protection of the present invention. Equivalent changes or modifications made should be covered within the protection scope of the present invention.

Claims (9)

1. A liquid crystal composition having negative dielectric anisotropy, comprising:

one or more compounds of formula I-1 in an amount of 8 to 25% by weight based on the total weight of the negative liquid crystal composition and one or more compounds of formula I-2 in an amount of 15 to 21% by weight based on the total weight of the negative liquid crystal composition

One or more compounds of formula II in an amount of 10-40% by weight based on the total weight of the negative liquid crystal composition

13-16% by weight of one or more compounds of the general formula III based on the total weight of the negative liquid crystal composition

And

20-60% of one or more compounds of formula IV by weight of the total negative liquid crystal composition

Wherein R is₃Represents a linear or branched, halogenated or unhalogenated alkyl or alkoxy group having 2 to 4 carbon atoms;

R₄、R₅、R₆、R₇and R₈The alkyl or alkoxy groups are the same or different and each independently represents a linear or branched, halogenated or unhalogenated alkyl or alkoxy group having 1 to 12 carbon atoms;

R₁、R₂the alkyl or alkoxy groups are the same or different and each independently represents a linear or branched, halogenated or unhalogenated alkyl or alkoxy group having 1 to 12 carbon atoms;

are the same or different and each independently represents

The above-mentioned

One or more H atoms in (a) may be substituted by F atoms;

a represents 0, 1 or 2, wherein, when a is 2, the ring

May be the same or different.

2. The negative dielectric anisotropy liquid crystal composition of claim 1, wherein the compound of formula i-1 is selected from the group consisting of:

and

3. the negative dielectric anisotropy liquid crystal composition of claim 1, wherein the compound of formula i-2 is selected from the group consisting of:

4. the negative dielectric anisotropy liquid crystal composition of claim 1, wherein the compound of formula ii is selected from the group consisting of:

5. the negative dielectric anisotropy liquid crystal composition of claim 1, wherein the compound of formula iii is selected from the group consisting of:

and

6. the negative dielectric anisotropy liquid crystal composition according to claim 1, wherein the compound of formula iv is one or more compounds selected from the group consisting of:

wherein,

R₇and R₈The same or different, each independently represents an alkyl group having 1 to 5 carbon atoms or an alkoxy group having 1 to 5 carbon atoms.

7. A liquid crystal composition having negative dielectric anisotropy comprising the liquid crystal composition according to any one of claims 1 to 6, characterized in that the liquid crystal composition further comprises one or more additives.

8. A liquid crystal display comprising the liquid crystal composition according to any one of claims 1 to 6.

9. A liquid crystal display comprising the liquid crystal composition having negative dielectric anisotropy according to claim 7.