Liquid crystal composition with good frequency dependence and liquid crystal display element

The present invention relates to the technical field of liquid crystal materials. In more particular, the present invention relates to a liquid crystal composition with good frequency dependence and a liquid crystal display element.

With the continuous development of display technologies, thin film transistor liquid crystal display (TFT-LCD) quickly occupies the leading position in the display industry and has been widely used in many fields due of a range of its advantages, such as a high resolution, rich colors, a high contrast ratio, a high brightness, a large viewing angle, a fast response speed, and easy realization of large-area display. In recent years, despite challenges from emerging display technologies such as Organic Light-Emitting Diode (OLED), Quantum Dot Light-Emitting Diode (QLED) and Micro Light-Emitting Diode (Micro-LED), TFT-LCD display technology, thanks to its excellent product performance, complete material system, mature process procedures and obvious price advantages, still has absolute leading edge in many aspects such as ultra-high resolution, large size and touch integration. When evaluating the display effect of a TFT-LCD panel, parameters such as resolution, transmittance, contrast ratio, response time and color gamut are usually considered, while transmittance is directly related to the display effect of the panel and is also a key indicator that can reflect the overall technical level of a panel manufacturer.

A liquid crystal is composed of a variety of liquid crystal monomers, and the properties of liquid crystal materials also influence and restrict each other. For example, the dielectric anisotropy of the liquid crystal materials directly affects the display properties of a liquid crystal device, including threshold voltage, response time, duty cycle, etc. The dielectric anisotropy of the liquid crystal materials mainly depends on the degree of polarization of liquid crystal molecules, which is related to the contribution of factors such as the shape of liquid crystal molecules, the position of polar groups, the permanent dipole moment, the p electron system and the central group, and is also affected by physical factors such as the external environmental temperature and the magnitude of the applied pressure. In addition, the change of the frequency of the applied voltage can change the degree of polarization of liquid crystal molecules, which makes the dielectric anisotropy of the liquid crystal vary. Furthermore, dielectric anisotropy usually has frequency dependence at low temperatures. At a low temperature, when the driving frequency becomes higher, the movement of liquid crystal molecules cannot follow the change of the frequency of the voltage, resulting in poor display. Therefore, the smaller the change of the voltage vs. frequency on the liquid crystal composition, the better the frequency dependence of the liquid crystal composition, and thus the poor display can be solved.

An excellent liquid crystal composition can also bring remarkable display effects on a device, that is, it can realize a fast response time, a fixed threshold voltage, an appropriate transmittance and contrast ratio and other properties, and excellent change rate at high and low temperatures and excellent frequency dependence can in turn solve the problem of transmittance variation when the display is switched between different frequencies.

In order to solve one or more of the technical defects mentioned above, the present invention provides a technical solution, which has an appropriate optical anisotropy, an appropriate dielectric anisotropy, especially a relatively low rotational viscosity, a good low-temperature mutual solubility, a good reliability and surprisingly good frequency dependence.

In order to achieve the above beneficial technical effects, the present invention provides a liquid crystal composition, the liquid crystal composition comprising a compound represented by Formula I, wherein the mass percentage content of the compound represented by Formula I in the liquid crystal composition is not less than 30%; and the liquid crystal composition further comprises one or more compounds represented by Formula II and one or more compounds represented by Formula III

wherein in Formula II,

R 1 and R 2 each independently represent an alkoxy with a carbon atom number of 1-10 or an alkenoxy with a carbon atom number of 2-10; and when R 1 and R 2 each independently represent an alkoxy with a carbon atom number of 2-10 or an alkenoxy with a carbon atom number of 2-10, any one of the hydrogen atoms thereof can be replaced by F.

R 3 represents an alkyl with a carbon atom number of 1-10; and R 3 ′ represents an alkenyl with a carbon atom number of 2-10.

A second object of the present invention is to provide a liquid crystal display element/display comprising the above-mentioned liquid crystal composition. The liquid crystal display element/display mainly has IPS, FFS or VA display mode, especially FFS display mode.

Effects of the Invention

The technical solution provided by the present invention has an appropriate optical anisotropy, an appropriate dielectric anisotropy, especially a relatively low rotational viscosity, a good low-temperature mutual solubility, a good frequency dependence and a good reliability. The liquid crystal composition of the present invention is mainly applied to FFS display mode and to large-, medium- and small-sized liquid crystal displays, and has a wider range of application fields, such as TV, MB, vehicles, PID and medical devices.

The present invention provides a liquid crystal composition with good frequency dependence, the liquid crystal composition comprising a compound represented by Formula I, wherein the mass percentage content of the compound represented by Formula I in the liquid crystal composition is not less than 30%; and the liquid crystal composition further comprises one or more compounds represented by Formula II and one or more compounds represented by Formula III

wherein in Formula II,

R 1 and R 2 each independently represent an alkoxy with a carbon atom number of 1-10 or an alkenoxy with a carbon atom number of 2-10; and when R 1 and R 2 each independently represent an alkoxy with a carbon atom number of 2-10 or an alkenoxy with a carbon atom number of 2-10, any one of the hydrogen atoms thereof can be replaced by F; and

R 3 represents an alkyl with a carbon atom number of 1-10; and R 3 ′ represents an alkenyl with a carbon atom number of 2-10.

As for the liquid crystal composition of the present invention, preferably, the compound represented by Formula II in the above-mentioned liquid crystal composition is selected from the group consisting of compounds represented by Formulas II-A, II-B, II-C, II-D, II-E, II-F, II-G, II-H, and II-I:

As for the liquid crystal composition of the present invention, preferably, the mass content of the above-mentioned compound represented by Formula II in the liquid crystal composition is 3-15%.

As for the liquid crystal composition of the present invention, preferably, the compound represented by Formula III in the above-mentioned liquid crystal composition is selected from the group consisting of compounds represented by Formulas III-A, III-B, III-E, and III-F:

As for the liquid crystal composition of the present invention, further preferably, the above-mentioned compound represented by Formula III is selected from compounds represented by Formula III-A and/or IIIB, and the mass content thereof in the liquid crystal composition is 2-10%, still further preferably 5-10%.

The liquid crystal composition of the present invention preferably further comprises one or more compounds represented by Formula IV:

wherein in Formula IV,

R 4 represents an alkyl with a carbon atom number of 1-10 or an alkenyl with a carbon atom number of 2-10;

R 4 ′ represents an alkyl with a carbon atom number of 1-10 or an alkoxy with a carbon atom number of 1-10; and

represents

As for the liquid crystal composition of the present invention, preferably, the above-mentioned compound represented by Formula IV is selected from the group consisting of compounds represented by the following Formulas IV-1 to IV-56:

As for the liquid crystal composition of the present invention, further preferably, the above-mentioned liquid crystal composition comprises at least three compounds represented by Formula IV.

As for the liquid crystal composition of the present invention, preferably, the above-mentioned liquid crystal composition comprises one or more compounds represented by Formula V:

wherein in Formula V,

R 5 represents an alkyl with a carbon atom number of 1-10 or an alkenyl with a carbon atom number of 2-10;

R 5 ′ represents an alkyl with a carbon atom number of 1-10 or an alkoxy with a carbon atom number of 1-10; and

represents

and

Z 1 represents a single bond, —CH 2 O— or —CH 2 CH 2 —.

As for the liquid crystal composition of the present invention, further preferably, the above-mentioned compound represented by Formula V is selected from the group consisting of compounds represented by the following Formulas V-1 to V-32:

As for the liquid crystal composition of the present invention, preferably, the above-mentioned liquid crystal composition further comprises one or more compounds represented by Formula VI other than the compound represented by Formula I

wherein in Formula VI,

R 6 and R 6 ′ each independently represent an alkyl with a carbon atom number of 1-10, an alkoxy with a carbon atom number of 1-10 or an alkenyl with a carbon atom number of 2-10;

represents

and

n represents 1 or 2 or 3; and when n represents 2 or 3, two or three

may be the same or different.

As for the liquid crystal composition of the present invention, preferably, the above-mentioned compound represented by Formula VI is selected from the group consisting of compounds represented by the following Formulas VI-1 to VI-36:

As for the liquid crystal composition of the present invention, preferably, the above-mentioned liquid crystal composition further comprises one or more compounds represented by Formula VII and/or compounds represented by Formula VIII:

wherein

R 7 , R 7 ′, R 8 and R 8 ′ each independently represent an alkyl with a carbon atom number of 1-10 and an alkoxy with a carbon atom number of 1-10; and

X 1 and X 2 each independently represent H or F.

As for the liquid crystal composition of the present invention, preferably, the above-mentioned compound represented by Formula VII is selected from the group consisting of compounds represented by the following Formulas VII-1 to VII-28:

As for the liquid crystal composition of the present invention, preferably, the above-mentioned compound represented by Formula VIII is selected from the group consisting of compounds represented by the following Formulas VIII-1 to VIII-3:

As for the liquid crystal composition of the present invention, further preferably, the liquid crystal composition comprises 3-5% by mass of the compound represented by Formula VIII-1.

As for the liquid crystal composition of the present invention, preferably, the above-mentioned liquid crystal composition comprises one or more compounds represented by Formula IX:

As for the liquid crystal composition of the present invention, preferably, the above-mentioned compound represented by Formula IX is selected from the group consisting of compounds represented by the following Formulas IX-1 to IX-12:

As for the liquid crystal composition of the present invention, preferably, various functional dopants may also be added to the above-mentioned liquid crystal compound.

As for the liquid crystal composition of the present invention, preferably, the above-mentioned dopants are mainly antioxidants, light stabilizers, etc.

As for the liquid crystal composition of the present invention, preferably, the mass percentage content of the above-mentioned dopants is preferably between 0.01% and 1%.

As for the liquid crystal composition of the present invention, preferably, the above-mentioned antioxidant is selected from one or more of compounds represented by Formulas T-1 to T-4:

wherein S represents an integer of 1-10.

As for the liquid crystal composition of the present invention, preferably, the compounds represented by Formulas T-1 to T-4 as the above-mentioned antioxidant are selected from the group consisting of compounds represented by Formulas T-1-1 to T-4-6:

As for the liquid crystal composition of the present invention, preferably, the above-mentioned light stabilizer is selected from the group consisting of compounds represented by the following Formulas T-5 and/or T-6:

wherein

S represents an integer of 1-10.

[Liquid Crystal Display Element or Liquid Crystal Display]

The present invention further relates to a liquid crystal display element or liquid crystal display comprising any one of the above-mentioned liquid crystal compositions; and the display element or display is an active matrix display element or display.

The above-mentioned active matrix display element or display can be specifically exemplified by, for example, IPS-TFT or FFS-TFT or VA-TFT liquid crystal display elements or other TFT displays, especially liquid crystal display elements or liquid crystal displays in which FFS-TFT mode is applied.

The liquid crystal display element or liquid crystal display of the present invention comprises the liquid crystal composition disclosed in the present invention. The liquid crystal display element or liquid crystal display of the present invention is mainly applied to the fields of TV, MNT, NB, Mobile, industrial control and vehicles, medical panels, etc.

In order to explain the present invention more clearly, the present invention will be further explained below in conjunction with preferred examples. A person skilled in the art should understand that the following detailed description is illustrative rather than restrictive, and should not limit the scope of protection of the present invention.

In the present invention, the preparation methods are all conventional methods unless otherwise specified, the raw materials used can all be obtained from open commercial channels unless otherwise specified, the percentages all refer to mass percentages, the temperatures are degrees Celsius (° C.), and the specific meanings and test conditions of the other symbols are as follows:

Cp represents the clearing point (° C.) of a liquid crystal, as measured by DSC quantitative method; Δn represents optical anisotropy, with Δn=ne−no, wherein no is the refractive index of ordinary light and ne is the refractive index of extraordinary light, and the test conditions are 25±2° C., 589 nm, and Abbe refractometer test; V10 represents the voltage (V) at which the transmittance changes from 0% to 10% in the normally black mode and at which the transmittance changes from 100% to 90% in the normally white mode and the test conditions are 10±0.5° C. and 0±0.5° C., FFS cell and DMS test; Δε represents dielectric anisotropy, Δε=ε // −ε ⊥ , wherein ε // is the dielectric constant parallel to the molecular axis, and ε ⊥ is the dielectric constant perpendicular to the molecular axis, and the test conditions are 25±0.5° C., 20 μm antiparallel cell, and INSTEC:ALCT-IR1 test; γ 1 represents rotational viscosity (mPa·s), and the test conditions are 25±0.5° C. and −20±0.5° C., 20 μm vertical cell, and INSTEC:ALCT-IR1 test; K 11 is splay elastic constant, K 33 is bend elastic constant, and the test conditions are: 25±0.5° C., INSTEC:ALCT-IR1, and 20 μm antiparallel cell; and

The preparation method for the liquid crystal composition involves: weighing various liquid crystal monomers at a certain ratio and putting the liquid crystal monomers into a stainless steel beaker, placing the stainless steel beaker containing these liquid crystal monomers on a magnetic stirring instrument for heating and melting, adding a magnetic rotor to the stainless steel beaker when most of the liquid crystal monomers in the stainless steel beaker have melted, uniformly stirring the mixture, and cooling the mixture to room temperature to obtain the liquid crystal composition.

The structures of the liquid crystal monomers in the examples of the present invention are represented by codes, and the code representation method for liquid crystal ring structures, terminal groups and linker groups is shown in Tables 1 and 2 below.

For example:

the code of which is CC-Cp-V1;

the code of which is PPY-3-O2;

the code of which is CPY-2-O2;

the code of which is CCY-3-O2;

the code of which is COY-3-O2;

the code of which is CCOY-3-O2;

the code of which is CLY-3-O2;

the code of which is Sb—CpO—O4;

the code of which is Sc—CpO—O4;

the code of which is PGP-Cpr1-2;

the code of which is B-2O—O4;

the code of which is B-CpO—O4

the code of which is CY-3-O2;

the code of which is PP-1-2V.

The following specific examples are used to illustrate the present invention: