TW201414818A - Liquid crystal composition and photoelectric display containing thereof - Google Patents

Abstract

The present invention provides a liquid crystal composition used for active matrix addressing photoelectric display that comprises: 10 wt% to 30 wt% of a first liquid crystal compound that is represented by formula (I), 5 wt% to 30 wt% of a second liquid crystal compound that is represented by formula (II), 10 wt% to 40 wt% of a third liquid crystal compound that is represented by formula (III), and 10 wt% to 60 wt% of a forth liquid crystal compound that is represented by formula (IV), based on a total weight of the liquid crystal composition, wherein the definitions of R1 to R7, X1 to X5, Z1, Z2, A, B, C, m, and n are described in specification. The liquid crystal composition provides faster response speed and is more stable at low temperature. The present invention also provides an active matrix addressing photoelectric display containing the liquid crystal composition.

Description

Liquid crystal composition and optoelectronic display device comprising the same

This invention relates to liquid crystal media, to its use for optoelectronic purposes, and to designing optoelectronic display devices comprising such media.

Liquid crystal materials must have good chemical and thermal stability and good stability to electric fields and electromagnetic radiation. In addition, the liquid crystal material should have low viscosity and produce short addressing times, low threshold voltages, and high contrast in the unit cell.

Furthermore, they should have a suitable crystalline phase at the usual operating temperatures, i.e., in the widest possible range above and below room temperature, such as for the nematic or cholesteric liquid crystal phase of the above unit cell. Since liquid crystals are usually formulated from a mixture of various components into a mixture, it is important that these components are easily miscible with each other.

There is a great demand for liquid crystal displays (LCDs), particularly matrix type liquid crystal displays, which have a very high resistivity over a wide operating temperature range, and have short reaction times even at low temperatures and low threshold voltages. In particular, there is a need for LC media for twisted nematic (TN) display cells, which contributes to the following advantages in the cell: expansion The range of the nematic phase (especially extended to low temperatures); the ability to switch at extreme temperatures (outdoor use, automotive, avionics); and enhanced UV radiation resistance (longer product life).

For TV box display applications, LC media with fast response times and low threshold voltages with good low temperature stability (LTS) are required. Also, depending on the thickness of the switchable LC layer, moderate or relatively high birefringence may be required.

In particular, the OCB mode is used for LCD applications in television, and the OCB mode is expected to be applied to displays used in automobiles and other mobile applications.

Liquid crystal compositions for LCDs and in particular for OCB displays are known from, for example, JP 2001-72977 (A) and JP 2003-327964 (A). However, these compositions have major drawbacks in terms of their physical properties. Among other deficiencies, most of them can lead to undesirable LCD performance, such as long reaction times, too low resistivity and/or narrow operating temperature ranges.

Thus, there is a significant need for liquid crystal media having suitable properties for practical applications, such as a wide nematic phase range, a suitably high nematic-isotropic transition temperature (clearing point), high Optical anisotropy, depending on the display used, relatively high dielectric anisotropy and particularly low viscosity.

Accordingly, it is an object of the present invention to provide a liquid crystal composition, particularly a thin film transistor (TFT) type active matrix liquid crystal display, which avoids The above disadvantages are eliminated or the above disadvantages can be alleviated for the TFT type active matrix display, and it is preferable to have a very high resistivity, a low threshold voltage, a low rotational viscosity, a high clearing point, and a wide nematic phase range. Improved LTS and fast switching times. By adjusting the composition, the low-temperature storage performance of the liquid crystal can be optimized, and the composition of the present invention has extremely excellent low-temperature storage stability energy, and the liquid crystal can operate normally in a low-temperature environment.

The invention increases the anthracene ring through the biphenyl liquid crystal structure, and at the same time appropriately fluorinates, achieves good low temperature mutual solubility and large dielectric anisotropy, and cooperates with a medium polarity small viscosity monomer to compensate for the disadvantage of large viscosity. At the same time, in order to complete the present invention, a strong polar liquid crystal compound and another low viscosity neutral liquid crystal compound are added to the liquid crystal composition described above to form a unique composition, which is suitable for use in mixed crystals, and can be remarkably Improve the low temperature mutual solubility of liquid crystal, dielectric anisotropy.

Thus, the liquid crystal composition of the present invention comprises 10% to 30% by weight of the total liquid crystal composition of the first liquid crystal compound, as shown by the following formula (I); 5% to 30% of the second liquid crystal compound, which has the following formula (II); 10% to 40% of the third liquid crystal compound, as shown by the following formula (III); and 10% to 60% of the fourth liquid crystal compound, as shown by the following formula (IV): Wherein R _{1 to} R ₇ may be the same or different and each independently represents H, halogen, C ₁ -C ₇ alkyl or alkoxy or C ₂ -C ₇ substituted or unsubstituted with at least one halogen Alkenyl; X ₁ -X ₅ may be the same or different and each independently represented as H or F; Z ₁ and Z ₂ may be the same or different and each independently represents -CH ₂ CH ₂ -, -COO-, -OCO -, -CF ₂ O-, -OCF ₂ -, -CH=CH-, -CH=CF-, -CF ₂ CF ₂ - or a single bond; A, B and C may be the same or different and are each independently represented as or ,among them, One or more of the CH ₂ may be independently replaced by O, One or more of the CHs may be independently replaced by N, and One or more H's may be independently substituted by F; and m, n may be the same or different, each independently being 0, 1, or 2; when m is 2, two B's may be the same or different; When 2, the two Cs may be the same or different.

A second object of the present invention is to provide an active matrix addressed photovoltaic display device comprising the liquid crystal composition as described above.

The present invention will be described in detail below. Preferably, the first liquid crystal compound of the formula (I) accounts for 10% to 25% by weight of the total weight of the liquid crystal composition; The liquid crystal compound accounts for 5%-20% of the total weight of the liquid crystal composition; the third liquid crystal compound of the formula (III) accounts for 20%-40% of the total weight of the liquid crystal composition; The fourth liquid crystal compound of the formula (IV) accounts for 20% to 50% by weight based on the total weight of the liquid crystal composition.

Preferably, the first liquid crystal compound of the formula (I) is selected from the group consisting of one or more of the following compounds:

Wherein R ₂ represents an alkyl or alkoxy group of H, F, C ₁ -C ₅ or a C ₂ -C ₅ alkenyl group substituted or unsubstituted with at least one halogen.

Preferably, said R _{3 is} represented by a C ₁ -C ₅ alkyl or alkoxy group or a C ₂ -C ₅ alkenyl group.

Preferably, the third liquid crystal compound of the formula (III) is selected from the group consisting of one or more of the following compounds:

Wherein R ₄ represents a C ₁ -C ₅ alkyl or alkoxy group or a C ₂ -C ₅ alkenyl group.

Preferably, the compound of formula (IV) is selected from the group consisting of one or more of the following compounds:

Wherein R ₆ represents a C ₁ -C ₅ alkyl or alkoxy group or a C ₂ -C ₅ alkenyl group.

More preferably, the first liquid crystal compound of the formula (I) is selected from the group consisting of one or more of the following compounds:

More preferably, the second liquid crystal compound of the formula (II) is selected from the group consisting of one or more of the following compounds:

More preferably, the third liquid crystal compound of the formula (III) is selected from the group consisting of one or more of the following compounds:

More preferably, the fourth liquid crystal compound of the formula (IV) is selected from the group consisting of one or more of the following compounds:

Preferably, the display of the present invention is preferably addressed by an active matrix (Active Matrix LCD: AMD), preferably a matrix of thin film transistors (TFTs). However, the liquid crystal composition of the present invention can also be advantageously applied to displays using other known addressing means.

As described above, the liquid crystal composition of the present invention has high optical anisotropy and dielectric anisotropy, low rotational viscosity, fast reaction speed, and low-temperature storage stability.

The invention will be further illustrated by the following examples, but it should be understood that this embodiment is for illustrative purposes only and should not be construed as Limitations of implementation of the invention.

In the present invention, unless otherwise specified, the ratios are all by weight, all temperatures are in Celsius, and the reaction time data is selected to have a cell thickness of 7 μm.

The liquid crystal displays used in the following embodiments are all TN-TFT liquid crystal display devices, and have a cell thickness d = 7 μm, and are composed of a polarizer (polarizer), an electrode substrate, and the like. The display device is normally white, that is, when no voltage difference is applied between the row and column electrodes, the observer observes the color of the white pixel. The upper and lower polarizer axes on the substrate are at an angle of 90 degrees to each other. The space between the two substrates is filled with an optical liquid crystal material.

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

Take the following structure as an example:

The structure can be expressed as 3PTGQP3 using the code in Table 1, as another example:

It can be expressed as nCPTPm, where n in the code represents the number of C atoms in the left-end alkyl group. For example, n in the code is "3", which means that the left-end alkyl group is -C ₃ H ₇ ; C in the code represents 1,4 - a cyclohexyl group; P in the code represents 1,4-phenylene; T in the code represents an alkynyl group; m in the code represents the number of C atoms of the right-end alkyl group, for example, m is "1", meaning that the right end The alkyl group is -CH ₃ .

The abbreviated codes of the test items in the examples are respectively expressed as: Δn optical anisotropy (589 nm, 20 ° C)

△ ε dielectric anisotropy (1 kHz, 25 ° C)

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

V ₉₀ saturation voltage = characteristic voltage at 90% relative contrast (normal white mode)

V ₁₀ threshold voltage = characteristic voltage at 10% relative contrast (normal white mode)

η flow viscosity (mPa.s at 20 ° C)

Γ1 torsional viscosity (mPa.s at 20 ° C)

K ₁₁ elastic constant ("oblique", pN at 20 ° C)

K ₂₂ elastic constant ("twisted", pN at 20 ° C)

K ₃₃ elastic constant ("bending", pN at 20 ° C)

t _{-30 ° C} low temperature storage time (at -30 ° C)

Among them, the refractive index anisotropy was measured by a Abbe refractometer under a sodium light (589 nm) light source at 20 ° C; the dielectric test box was TN90 type, the box thickness was 7 μm, and the V ₁₀ test condition was C/1 kHz, JTSB 7. 0.

Each component used in the following examples can be synthesized by the inventors of the present application in accordance with a known method, or by a combination of methods in organic synthetic chemistry. These synthetic techniques are conventional, and each of the obtained liquid crystal compounds has been tested to meet the standards of electronic compounds. A method for introducing a target terminal group, a ring structure, and a binding group into a starting material, which is described in Organic Synthesis (Organic Syntheses, John Wiley & Sons) , Inc., organic reaction (Organic Reactions, John Wiley & Sons, Inc), Comprehensive Organic Synthesis (Pergamon Press), New Experimental Chemistry Lecture (Maruzen Co., Ltd.) and other publications.

A liquid crystal composition was prepared in accordance with the ratio of each liquid crystal composition specified in the following examples. The preparation of the liquid crystal composition is carried out according to a conventional method in the art, such as heating, ultrasonic wave, suspension, etc., in a predetermined ratio.

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

<Comparative Example 1>

According to each compound and weight percentage listed in Table 2, a comparative liquid crystal composition was prepared, which was filled between two substrates of a liquid crystal display for characteristic measurement. The test data is also shown in Table 2 below:

<Example 1>

The liquid crystal composition of the present invention was prepared according to each compound and weight percentage listed in Table 3, and was filled in the liquid crystal display between the two substrates for characteristic measurement. The test data is also shown in Table 3 below:

<Example 2>

The liquid crystal composition of the present invention was prepared according to each compound and weight percentage listed in Table 4, and was filled between two substrates of the liquid crystal display for characteristic measurement. The test data is also shown in Table 4 below:

The liquid crystal compositions of the above two application examples have higher optical anisotropy and larger dielectric anisotropy than the comparative examples, and the rotational viscosity is still low, especially excellent low-temperature storage stability, and application of liquid crystal. The temperature range is wider.

In summary, the present invention determines a liquid crystal medium including the above liquid crystal composition by a combination experiment with the above compound, and has high optical anisotropy and dielectric anisotropy and a fast reaction by comparison with a comparative example. Time and low temperature storage stability make it possible to achieve the object of the present invention.

The above is only the preferred embodiment of the present invention, and the scope of the present invention is not limited thereto, that is, the simple equivalent changes and modifications made by the scope of the patent application and the patent specification of the present invention, All remain within the scope of the invention patent.

Claims (8)

A liquid crystal composition comprising: 10% to 30% by weight of the total liquid crystal composition of a first liquid crystal compound, represented by the following formula (I); 5% to 30% of a second liquid crystal compound, of the following formula ( II); 10% to 40% of the third liquid crystal compound, as shown by the following formula (III); and 10% to 60% of the fourth liquid crystal compound, as shown by the following formula (IV): Wherein R _{1 to} R ₇ may be the same or different and each independently represents H, halogen, C ₁ -C ₇ alkyl or alkoxy or C ₂ -C ₇ substituted or unsubstituted with at least one halogen Alkenyl; X ₁ -X ₅ may be the same or different and each independently represented as H or F; Z ₁ and Z ₂ may be the same or different and each independently represents -CH ₂ CH ₂ -, -COO-, -OCO -, -CF ₂ O-, -OCF ₂ -, -CH=CH-, -CH=CF-, -CF ₂ CF ₂ - or a single bond; A, B and C may be the same or different and are each independently represented as or ,among them, One or more of the CH ₂ may be independently replaced by O, One or more of the CHs may be independently replaced by N, and One or more H's may be independently substituted by F; and m, n may be the same or different, each independently 0, 1, or 2; when 1m is 2, two B's may be the same or different; When 2, the two Cs may be the same or different. The liquid crystal composition according to claim 1, wherein the first liquid crystal compound of the formula (I) accounts for 10% to 25% by weight of the total weight of the liquid crystal composition; and the second portion of the formula (II) The liquid crystal compound accounts for 5% to 20% by weight of the total weight of the liquid crystal composition; the third liquid crystal compound of the formula (III) accounts for 20% to 40% by weight of the total weight of the liquid crystal composition; The fourth liquid crystal compound of (IV) accounts for 20% to 50% of the total weight of the liquid crystal composition. The liquid crystal composition according to claim 2, wherein the first liquid crystal compound of the formula (I) is selected from the group consisting of one or more of the following compounds: Wherein R ₂ represents an alkyl or alkoxy group of H, F, C ₁ -C ₅ or a C ₂ -C ₅ alkenyl group substituted or unsubstituted with at least one halogen. The liquid crystal composition according to claim 2, wherein the R _{3 is} represented by a C ₁ -C ₅ alkyl group or an alkoxy group or a C ₂ -C ₅ alkenyl group. The liquid crystal composition according to claim 2, wherein the third liquid crystal compound of the formula (III) is selected from the group consisting of one or more of the following compounds: Wherein R ₄ represents a C ₁ -C ₅ alkyl or alkoxy group or a C ₂ -C ₅ alkenyl group. The liquid crystal composition according to claim 2, wherein the compound of the formula (IV) is selected from the group consisting of one or more of the following compounds: Wherein R ₆ represents a C ₁ -C ₅ alkyl or alkoxy group or a C ₂ -C ₅ alkenyl group. The liquid crystal composition according to any one of claims 3 to 6, wherein the first liquid crystal compound of the formula (I) is selected from the group consisting of one or more of the following compounds: The second liquid crystal compound of the formula (II) is selected from the group consisting of one or more of the following compounds: The third liquid crystal compound of the formula (III) is selected from the group consisting of one or more of the following compounds: The fourth liquid crystal compound of the formula (IV) is selected from the group consisting of one or more of the following compounds: An active matrix-addressable photovoltaic display device comprising the liquid crystal composition according to any one of claims 1 to 7.