CN107815322B

CN107815322B - Liquid crystal compound, liquid crystal composition and display device

Info

Publication number: CN107815322B
Application number: CN201610825423.6A
Authority: CN
Inventors: 韩文明; 徐爽; 徐海彬; 陈昭远
Original assignee: Jiangsu Hecheng Display Technology Co Ltd
Current assignee: Jiangsu Hecheng Display Technology Co Ltd
Priority date: 2016-09-14
Filing date: 2016-09-14
Publication date: 2021-01-26
Anticipated expiration: 2036-09-14
Also published as: CN107815322A

Abstract

The invention provides a liquid crystal composition and application thereof, wherein the liquid crystal composition comprises: 1-20% by weight of the total liquid crystal composition of at least one compound of formula I; 25-80% by total weight of the liquid crystal composition of at least one compound selected from the group consisting of formula II-1, formula II-2, formula II-3, formula II-4, and combinations thereof; and 20-75% by total weight of the liquid crystal composition of at least one compound selected from the group consisting of formula III-1, III-2, III-3, III-4, and combinations thereof. The liquid crystal composition has proper optical anisotropy, higher clearing point, larger negative dielectric anisotropy, low viscosity and high reliability, is suitable for a liquid crystal display, and meets the requirement of quick response of the liquid crystal display. The invention also provides a compound corresponding to the general formula I-2.

Description

Liquid crystal compound, liquid crystal composition and display device

Technical Field

The present invention relates to a liquid crystal compound and a liquid crystal composition, and more particularly, to a liquid crystal composition having suitable optical anisotropy, a high clearing point, a large negative dielectric anisotropy, a low viscosity, and high reliability, and a liquid crystal display device including the same.

Background

It is well known that compounds of the formula M

Can be used for active matrix addressed electro-optical displays based on the ECB effect, IPS (in plane switching) displays or FFS (fringe field switching) displays.

The principle of the electrically controlled birefringence, the ECB effect or also the DAP (aligned phase distortion) effect was first described in 1971 (M.F. Schieckel and K.Fahrenschon, "Deformation of biological liquid crystals with vertical orientation in electrical fields", applied. Phys. Lett.19(1971), 3912). This is followed by papers from j.f. kahn (appl.phys.lett.20(1972),1193) and g.labrunie and j.robert (j.appl.phys.44(1973), 4869).

The papers of J.Robert, F.Clerc (SID80Digest techn. papers (1980),30), J.Duchene (Displays7(1986),3) and H.Schad (SID82Digest techn. papers (1982),244) show that the liquid-crystalline phase must have a high number of elastic constant ratios K₃/K₁High values of optical anisotropy Deltan and Deltasinum are less than or equal to 0.5, and are suitable for high-information display elements based on the ECB effect. Electro-optical display elements based on the ECB effect have a homeotropic edge alignment (VA technique ═ vertical alignment). Dielectrically negative liquid-crystalline media can also be used in displays which utilize the so-called IPS or FFS effect.

Displays using the ECB effect, as so-called WAN (vertically aligned nematic) displays, are described, for example, in MVA (Multi-Domain vertical alignment, e.g. Yoshide, H. et al, article 3.1: "MAA LCD for Notebook or Mobile PCs.", SID2004International Syspossium, Digest of Technical Papers, XXXV, edition I, pages 6-9, and Liu, C.T. et al, article 15.1: "A46 in TFT LCD HDTV. technical., SID2004International Syosium, Digest of Technical Papers, XXXV, edition II, page 750. 753), PVA (patterned vertical alignment, e.g. Kim, SangSoo, article 15.4:" Super New State of PVA ", PVA of device for the" PVA (PVA of the same, see FIG. 13, High-level of Technical field, see FIG. 13, S.: Sk. S, S. Softx, S. Sk. TM., "FIGS.;, S. Softn. Softx. Sk. Softx. Sk. Softx. et al, see FIGS.;" FIGS. 13. 12. Softx. Sk. Softx. Softs. Sk. In Digest of Technical Papers, XXXV, edition II, page 754757) mode, it has been determined per se that in addition to IPS (in-plane switching) displays (for example: yeo, s.d., paper 15.3: "An LC Display for the TV Application", SID2004International Symposium, Digest of Technical Papers, XXXV, edition II, pages 758 and 759) and the long known TN (twisted nematic) displays, one of the three more recent types of liquid crystal displays of current importance, in particular for TV applications. For example, in Souk, Jun, SID semiar 2004, semiar M6: "Recent Advances in LCD Technology", serum signatures, M6/1 to M6/26, and Miller, Ian, SID serum 2004, serum M7: these techniques are compared in the usual manner in "LCD Television", serum features Notes, M7/1 to M7/32. Although the response time of modern ECB displays has been significantly improved by overdrive (over drive) addressing methods, for example: kim, Hyeon Kyeong et al, article 9.1: "A57 in. Wide UXGA TFT LCD for HDTV Application", SID2004International Symposium, Digest of Technical Papers, XXXV, edition I, page 106 and 109, but obtaining a response time suitable for video, particularly in gray scale switching, is still a problem that is not satisfactorily solved.

The industrial application of this effect in electro-optical display elements requires that the liquid crystal phase must meet a number of requirements. Of particular importance here are chemical resistance to moisture, air and physical influences such as heat, infrared, visible light, ultraviolet radiation and direct and alternating electric fields.

Furthermore, the industrially available liquid crystalline phase requires the characteristics of a liquid crystalline mesophase and low viscosity in a suitable temperature range.

None of the series of compounds having a liquid crystalline mesophase disclosed to date comprises a single compound that meets all these requirements. Thus, mixtures of two to twenty-five, preferably three to eighteen compounds are generally prepared to obtain materials which can be used as liquid crystalline phases. However, since no liquid crystal material having a significantly negative dielectric anisotropy and sufficient long-term stability has been available so far, it has not been possible to easily prepare an optimum phase in this manner.

Matrix liquid crystal displays (MLC displays) are known. Non-linear elements such as active elements (i.e. transistors) that can be used for individual pixel independent switching. Thus, the term "active matrix" is used, wherein two types can be distinguished:

1. a MOS (metal oxide semiconductor) transistor on a silicon wafer as a substrate;

2. a Thin Film Transistor (TFT) on a glass plate as a substrate.

In the case of type 1, the electro-optical effect used is usually a dynamic scattering or guest-host effect. The use of single crystal silicon as a substrate material limits the display size, since even modular assembly of various sub-displays can cause problems at the joints.

In the case of the preferred more promising type 2, the electro-optical effect used is generally the TN effect.

There is a distinction between the two techniques: TFTs containing compound semiconductors such as CdSe, or TFTs based on polycrystalline or amorphous silicon. With respect to the latter technique, intensive work is being performed worldwide.

The TFT matrix is applied to the inside of one glass plate of the display, while the other glass plate carries a transparent counter electrode on its inside. The TFT is very small compared to the size of the pixel electrode and has little adverse effect on the image. The technique can also be generalized for full-color displays where a mosaic of red, green and blue filters can have filter elements arranged in opposition to each switchable pixel.

The term MLC display here encompasses any matrix display with integrated non-linear elements, i.e. in addition to an active matrix also displays with passive elements, such as variable resistors or diodes (MIM ═ metal-insulator-metal).

Such MLC displays are particularly suitable for TV applications (e.g. pocket TVs) or for high-information displays in automobile or aircraft construction. In addition to the problems with respect to the angle dependence of the contrast and the response time, difficulties also arise in MLC displays due to the insufficiently high specific resistance of the liquid-crystal mixture [ TOGASHI, s., SEKIGUCHI, k., TANABE, h., YAMAMOTO, e., sorimahi, k., TAJIMA, e., WATANABE, h., SHIMIZU, h., proc. eurodisplay84, 9 th 1984: a210288 Matrix LCD Controlled by Double Stage diodes Rings, pages 141 and following, Paris: STROMER, M., Proc. Eurodiplacy 84, 9.1984: design of Thin Film Transistors for Matrix Addressing of Television Liquid Crystal display, page 145 and its succeeding pages, Paris ]. With decreasing resistance, the contrast of MLC displays degrades. The specific resistance of the liquid crystal mixture generally decreases over the lifetime of an MLC display due to interaction with the inner surfaces of the display, so a high (initial) resistance is very important for displays which must have an acceptable resistance value over a long operating time.

Thus, there is still a great need for MLC displays having very high specific resistance and at the same time a large operating temperature range, short response times and low threshold voltages, and it is desirable to be able to produce various gray levels with the aid of such displays.

The disadvantages of the MLC-TN displays which are generally used are due to their relatively low contrast, relatively high viewing angle dependence and the difficulty of producing gray levels in these displays.

VA displays have significantly better viewing angle dependence and are therefore used mainly for television sets and monitors. However, there is still a need to improve the response time here. At the same time, some properties such as low temperature stability and reliability must not be compromised. The liquid crystal material is also required to have good performance at low temperature, and particularly, the change of the driving voltage at low temperature relative to the driving voltage at normal temperature is required to be as small as possible.

The invention is based on the object of: a liquid crystal composition is provided which does not have or only to a reduced extent has the above-mentioned disadvantages. In particular, for monitors and televisions it must be ensured that they can operate even at very high and very low temperatures and at the same time have short response times and at the same time improved reliability characteristics, in particular no or significantly reduced image retention after long operating times.

Surprisingly, it is possible to improve the rotational viscosity values and thus the response times if one or more polar compounds according to formula I in the present application are used in liquid-crystalline compositions which are preferably used in VA displays, in particular in liquid-crystalline compositions having a negative dielectric anisotropy. Liquid-crystal mixtures, preferably VA, PS-VA, PSA, IPS and FFS mixtures, having short response times and at the same time good phase solubility properties and good low-temperature properties can be prepared by means of the compounds of the formula I.

Disclosure of Invention

The invention aims to provide a liquid crystal composition, and particularly relates to a liquid crystal composition with appropriate optical anisotropy, higher clearing point, larger negative dielectric anisotropy, low viscosity and high reliability, and a liquid crystal display device comprising the liquid crystal composition.

One aspect of the present invention provides a liquid crystal composition comprising:

at least one compound with a general formula I accounting for 1-20% of the total weight of the liquid crystal composition

Wherein,

R₁and R₂The same or different, each independently represents an alkyl group or an alkoxy group having 1 to 7 carbon atoms, or an alkenyl group or an alkenyloxy group having 2 to 7 carbon atoms;

to represent

The above-mentioned

Upper arbitrary CH₂May be substituted by O; the above-mentioned

Any of the above H may be substituted with F.

In some embodiments of the present invention, the liquid crystal composition may further comprise:

25-75% by weight of the total liquid crystal composition of at least one compound selected from the group consisting of formula II-1, II-2, II-3, II-4 and combinations thereof

And

wherein,

R₃、R₅、R₆、R₇、R₈、R₉and R₁₀The same or different, each independently represents an alkyl group or an alkoxy group having 1 to 7 carbon atoms, or an alkenyl group or an alkenyloxy group having 2 to 7 carbon atoms;

R₄represents H, an alkyl group or an alkoxy group having 1 to 7 carbon atoms, or an alkenyl group or an alkenyloxy group having 2 to 7 carbon atoms.

20-70% by total weight of the liquid crystal composition of at least one compound selected from the group consisting of formula III-1, III-2, III-3, III-4, and combinations thereof

And

wherein,

R₁₁、R₁₂、R₁₃、R₁₄、R₁₅、R₁₆、R₁₇and R₁₈The same or different, each independently represents an alkyl group or an alkoxy group having 1 to 7 carbon atoms, or an alkenyl group or an alkenyloxy group having 2 to 7 carbon atoms.

In some embodiments of the present invention, it is preferred that the at least one compound of formula I comprises from 1 to 20% by weight of the total liquid crystal composition; the at least one compound selected from the group consisting of formula II-1, formula II-2, formula II-3, formula II-4 and combinations thereof comprises 30-65% of the total weight of the liquid crystal composition; and the at least one compound selected from the group consisting of formulas III-1, III-2, III-3, III-4 and combinations thereof accounts for 30 to 60% of the total weight of the liquid crystal composition.

In some embodiments of the present invention, it is preferred that the compound of formula i is selected from one or more compounds of the group consisting of:

and

wherein,

R_1A、R_2A、R_1B、R_2Bthe alkyl groups may be the same or different and each independently represents an alkyl group having 1 to 7 carbon atoms.

More preferably, the compound of formula I-1 is selected from one or more compounds from the group consisting of:

and

more preferably, the compound of formula I-2 is selected from one or more compounds of the group consisting of:

and

in some embodiments of the present invention, it is preferred that the compound of formula II-1 is selected from one or more compounds of the group consisting of:

and

in some embodiments of the present invention, it is preferred that the compound of formula II-2 is selected from one or more compounds of the group consisting of:

and

in some embodiments of the present invention, it is preferred that the compound of formula II-3 is selected from one or more compounds of the group consisting of:

and

in some embodiments of the present invention, it is preferred that the compound of formula II-4 is selected from one or more compounds of the group consisting of:

and

in some embodiments of the present invention, it is preferred that the compound of formula III-1 is selected from one or more compounds of the group consisting of:

and

in some embodiments of the present invention, it is preferred that the compound of formula III-2 is selected from one or more compounds of the group consisting of:

and

in some embodiments of the present invention, it is preferred that the compound of formula III-3 is selected from one or more compounds of the group consisting of:

and

in some embodiments of the present invention, it is preferred that the compound of formula III-4 is selected from one or more compounds of the group consisting of:

and

as a particularly preferred embodiment, said at least one compound of formula i represents from 3 to 18% of the total weight of said liquid crystal composition; the at least one compound selected from the group consisting of formula II-1, formula II-2, formula II-3, formula II-4 and combinations thereof comprises 30-64% of the total weight of the liquid crystal composition; and the at least one compound of the group of formulae III-1, III-2, III-3, III-4, and combinations thereof comprises 33 to 60% of the total weight of the liquid crystal composition.

The liquid crystal composition provided by the invention further comprises one or more additives known to those skilled in the art and described in the literature. For example, 0-15% pleochroic dyes and/or chiral dopants may be added.

The following shows possible dopants which are preferably added to the mixtures according to the invention.

And

in the embodiment of the present invention, it is preferable that the dopant accounts for 0 to 5% by weight of the total weight of the liquid crystal composition; more preferably, the dopant is present in an amount of 0 to 1% by weight based on the total weight of the liquid crystal composition.

The stabilizers which can be added to the liquid crystal composition according to the present invention are mentioned below.

Preferably, the stabilizer is selected from the group consisting of the stabilizers shown below:

in the embodiment of the present invention, it is preferable that the stabilizer accounts for 0 to 5% by weight of the total weight of the liquid crystal composition; more preferably, the stabilizer is 0-1% of the total weight of the liquid crystal composition; as a particularly preferred embodiment, the stabilizer is 0 to 0.1% by weight of the total weight of the liquid crystal composition.

In another aspect, the present invention provides a liquid crystal compound of the general formula I-2:

wherein,

R_1B、R_2Bthe alkyl groups may be the same or different and each independently represents an alkyl group having 1 to 7 carbon atoms.

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

and

in another aspect, the present invention provides a process for the preparation of a compound of formula I-2:

the method comprises the following steps: in an organic solvent, performing suzuki coupling reaction on the iodide shown in the formula 1 and the boric acid compound shown in the formula 2 to obtain the compound shown in the general formula I-2.

In still another aspect, the present invention provides a liquid crystal display device comprising the liquid crystal composition of the present invention.

In still another aspect, the present invention provides a liquid crystal display device comprising the liquid crystal compound of the present invention.

The liquid crystal composition has proper optical anisotropy, higher clearing point, larger negative dielectric anisotropy, low viscosity and high reliability, is suitable for a liquid crystal display, and meets the requirement of quick response of the liquid crystal display.

In the present invention, unless otherwise specified, the proportions are weight ratios, all temperatures are in degrees centigrade, and the thickness of the box selected for the response time data test is 7 μm.

Detailed Description

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

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

TABLE 1 radical structural code of liquid crystal compounds

Compounds of the following formula are exemplified:

the structural formula is represented by the code listed in Table 1, and can be expressed as: nCPUF, where n in the code represents the number of C atoms in the left alkyl group, e.g., n is "3", i.e., the alkyl group is-C₃H₇(ii) a C in the code represents cyclohexane, P in the code represents 1, 4-phenylene, and U in the code represents 3, 5-difluoro-1, 4-phenylene.

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

cp (. degree. C.): clearing points (nematic-isotropic phase transition temperature)

Δ n: optical anisotropy (589nm, 25 ℃ C.)

Δ ε: dielectric anisotropy (1KHz, 25 ℃ C.)

V (25 ℃ C.)/V (-20 ℃ C.): ratio of drive voltages at different temperatures

γ 1: torsional viscosity (mPas, 25 ℃ C.)

Wherein the refractive index anisotropy is measured by using an Abbe refractometer under a sodium lamp (589nm) light source at 20 ℃; the dielectric test cell was of the type TN90, the cell thickness being 7 μm.

Δ ∈ | ∈ | — |, where ∈ | is the dielectric constant parallel to the molecular axis and ∈ | is the dielectric constant perpendicular to the molecular axis, test conditions: at 25 ℃ and 1KHz, the test box is TN90 type, and the box thickness is 7 μm.

V (25 ℃): a drive voltage at 25 ℃; v (-20 ℃): -a drive voltage at 20 ℃.

Example 1

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

TABLE 2 liquid crystal composition formulations and their test properties

Example 2

The liquid crystal composition of example 2 was prepared according to the compounds and weight percentages thereof listed in table 3, and filled between two substrates of a liquid crystal display for performance testing, and the test data are shown in the following table:

TABLE 3 liquid crystal composition formula and its test performance

Example 3

The liquid crystal composition of example 3 was prepared according to the compounds and weight percentages thereof listed in table 4, and filled between two substrates of a liquid crystal display for performance testing, and the test data are shown in the following table:

TABLE 4 liquid crystal composition formula and its test performance

Example 4

The liquid crystal composition of example 4 was prepared according to the compounds and weight percentages thereof listed in table 5, and filled between two substrates of a liquid crystal display for performance testing, and the test data are shown in the following table:

TABLE 5 liquid crystal composition formulations and their test properties

As can be seen from the data of example 1, example 2, example 3 and example 4, the liquid crystal composition provided by the present invention has suitable optical anisotropy, a higher clearing point, a larger negative dielectric anisotropy, a low viscosity and high reliability, and can be applied to a liquid crystal display to meet the requirement of fast response of the liquid crystal display.

The above embodiments are merely illustrative of the technical concept and features of the present invention, and the present invention is not limited thereto, and equivalent changes and modifications made according to the spirit of the present invention should be covered thereby.

Claims

1. A liquid crystal composition, comprising:

30-65% by total weight of the liquid crystal composition of at least one compound selected from the group consisting of formula II-1, II-2, II-3, II-4 and combinations thereof

And

30-60% by total weight of the liquid crystal composition of at least one compound selected from the group consisting of formula III-1, III-2, III-3, III-4, and combinations thereof

And

wherein,

R₁and R₂The same or different, each independently represents an alkyl group having 1 to 7 carbon atoms;

R₃、R₅、R₆、R₇、R₈、R₉、R₁₀、R₁₁、R₁₂、R₁₃、R₁₄、R₁₅、R₁₆、R₁₇and R₁₈The same or different, each independently represents an alkyl group or an alkoxy group having 1 to 7 carbon atoms, or an alkenyl group or an alkenyloxy group having 2 to 7 carbon atoms;

R₄represents H, an alkyl group or an alkoxy group having 1 to 7 carbon atoms, or an alkenyl group or an alkenyloxy group having 2 to 7 carbon atoms,

to represent

The above-mentioned

Any of the above H may be substituted with F.

2. The liquid crystal composition of claim 1, wherein the compound of formula i is selected from one or more compounds of the group consisting of:

and

wherein,

3. The liquid crystal composition according to claim 2, wherein the compound of formula i-1 is selected from one or more compounds selected from the group consisting of:

and

and is

The compound of the general formula I-2 is selected from one or more compounds of the group consisting of:

and

4. the liquid crystal composition according to claim 1, wherein the compound of formula ii-1 is one or more compounds selected from the group consisting of:

and

the compound of the general formula II-2 is selected from one or more compounds of the group consisting of:

and

the compound of the general formula II-3 is one or more compounds selected from the group consisting of:

and

and is

The compound of formula II-4 is selected from one or more compounds of the group consisting of:

and

5. the liquid crystal composition according to claim 1, wherein the compound of formula iii-1 is selected from one or more compounds from the group consisting of:

and

the compound of the general formula III-2 is selected from one or more compounds of the group consisting of:

and

the compound of the general formula III-3 is selected from one or more compounds from the group consisting of:

and

and is

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

and

6. the liquid crystal composition of claim 1, wherein the at least one compound of formula i comprises from 3 to 18% by weight of the total liquid crystal composition; the at least one compound selected from the group consisting of formula II-1, formula II-2, formula II-3, formula II-4 and combinations thereof comprises 30-64% of the total weight of the liquid crystal composition; and the at least one compound of the group of formulae III-1, III-2, III-3, III-4, and combinations thereof comprises 33 to 60% of the total weight of the liquid crystal composition.

7. The liquid crystal composition of claim 6, wherein the liquid crystal composition comprises, based on the total weight of the liquid crystal composition:

18% of compound