TW201414813A - Liquid crystal composition and display comprising same - Google Patents

Abstract

The invention provides a liquid crystal composition. The composition comprises a compound which is shown in the general formula (I) in the specification and accounts for 14-30% of the total weight of the composition, a compound shown in the general formula (II) in the specification and accounts for 2-10% of the total weight of the composition, one or more compounds of groups formed by compounds selected from the free general formulas (IIIa)-(IIId), a compound shown in the general formula (IV) in the specification and accounts for 5-50% of the total weight of the composition and a compound shown in the general formula (V) in the specification and accounts for 2-20% of the total weight of the composition, wherein one or more compounds account for 10-50% of the total weight of the composition. The liquid crystal composition has flat dielectric anisotropy frequency dependence. The invention also provides an active matrix display device comprising the liquid crystal composition.

Description

Liquid crystal composition and active matrix liquid crystal display thereof

The present invention relates to the technical field of materials for display devices, and more particularly to a liquid crystal composition and an active matrix liquid crystal display thereof for producing a nematic of flat dielectric anisotropy, frequency dependence and dielectric integrity. Liquid crystal medium for use in active matrix liquid crystal displays.

Liquid crystal materials generally must have good chemical thermal stability, good stability against electric fields and electromagnetic radiation, and liquid crystal materials also have low viscosity, short response time in the liquid crystal cell, low threshold voltage and high contrast.

In addition, they should also have a mesogenic phase suitable for the above liquid crystal cell at ordinary operating temperatures, i.e., at the widest possible range above and below room temperature, such as a nematic type for the above liquid crystal cell. Crystal phase. Since liquid crystals are generally used as a mixture of a plurality of components, it is important that the components are miscible with each other. Further, in terms of the type and application field of the liquid crystal cell, the liquid crystal material needs to have properties such as electrical conductivity, dielectric anisotropy, and optical anisotropy that must satisfy various requirements. As for the liquid crystal material used in the liquid crystal cell having a twisted nematic structure, it should have positive dielectric anisotropy and low electrical conductivity, while for a matrix liquid crystal display, it is required to have a large positive dielectric. Anisotropic, wide nematic phase, relatively low birefringence, very high resistivity, good light and temperature stability, and low vapor pressure liquid crystal media, the display contains an integrated nonlinear element for switching individual elements, ie MLC monitor.

Since the advent of liquid crystal, its electro-optical effect has been particularly eye-catching. The first practical dynamic scattering effect (DSM) is the use of liquid crystal current body dynamic instability, also known as current effect. Later, the distortion effect (TN), the electronically controlled birefringence effect (ECB), the cholesteric phase-nematic phase transition effect (Ch-N), and the N _p -Ch liquid crystal positive storage effect are another A new type of electro-optical effect - field effect. Under the action of electric field, it has almost no dependence on current, micro power consumption, long life and so on, so it quickly plays an important role in liquid crystal display, such as liquid crystal display in all electronic watches and calculators. The electro-optical properties of such field effect liquid crystals are closely related to dielectric anisotropy. With the wide application of field effect liquid crystals and the development of more application fields in the future, such as matrix display, storage display, color display, TV image display and instant information processing, it is necessary to study the dielectric anisotropy of liquid crystals. . The static and dynamic properties (ie, frequency characteristics) of the special field effect liquid crystal dielectric anisotropy, and its significance for the application of field effect liquid crystal reality.

It can be seen from the above that the dielectric anisotropy of the liquid crystal is subject to frequency dependence. Due to the inappropriate frequency dependence of the dielectric anisotropy Δε, difficulties may arise in these MLC displays, if the display is triggered at a low frequency at a low frequency at which Δε is already low due to the frequency dependence of Δε, then Only a portion of the primitive capacitance is charged during the open time of the transistor gate. The required high voltage is applied to the liquid crystal under constant charging. Thereby, the photoelectric performance of the liquid crystal deteriorates. Therefore, a liquid crystal medium is greatly required in which the frequency dependence of the dielectric constant is as flat as possible even at a low temperature. In order to achieve a short display response time, the mixture must additionally have a small rotational viscosity. In order to be able to use the display even at low temperatures, for example for outdoor, automotive or avionics applications, it is required that the crystallization and/or smectic phase does not occur even at low temperatures, and that the temperature dependence of the viscosity is as low as possible.

In view of the problems of the prior art, it is an object of the present invention to provide a liquid crystal composition and an active matrix liquid crystal display thereof, which are preferably combined with a liquid crystal compound of a specific structure type, so that the composition has good flat dielectric anisotropy. And frequency dependence, in this way, the voltage of the liquid crystal composition decreases with frequency dependence, improves the stability of the liquid crystal display, and has a wider use environment, and has a good promoting effect on improving the low temperature performance of the liquid crystal. Moreover, the present liquid crystal medium has good low temperature storage stability at the same time, and the liquid crystal medium preferably has a nematic phase which is at least -20 ° C to 70 ° C, more preferably from -30 ° C to 75 ° C, most preferably from -30 ° C to 80 ° °C and in particular a temperature range from -40 ° C to 100 ° C is stable.

For the purposes of the present invention, the liquid crystal composition is provided for use in an active matrix liquid crystal display comprising: a compound of the formula I in an amount of from 14% to 30% by weight based on the total weight of the liquid crystal composition a compound of the formula II in an amount of from 2% to 10% by weight based on the total weight of the liquid crystal composition One or more compounds selected from the group consisting of compounds of the formulae IIIa to IIId, which comprise from 10% to 50% by weight based on the total weight of the liquid crystal composition a compound of the formula IV which comprises from 5% to 50% by weight based on the total weight of the liquid crystal composition And a compound of the formula V in an amount of from 2% to 20% by weight based on the total weight of the liquid crystal composition Wherein R ₁₁ , R ₂₁ to R ₂₂ , R ₃₁ to R ₃₄ , R ₄₁ to R ₄₂ , and R ₅₁ to R ₅₂ may be the same or different and are independently selected from the group consisting of H, halogen, C1 to C7 alkyl or alkane. a group consisting of an oxy group and a C ₂ -C ₇ alkenyl group or an alkenyloxy group; X ₁ -X ₃ , Y ₁ -Y ₉ , Z ₁ -Z ₂ may be the same or different and independently of each other H or F; , Y ₂ , Y ₈ may also be a C ₁ ~ C ₇ alkyl or alkoxy group; with Can be the same or different, independently of each other or And One or more of the Hs may be replaced by F independently of each other; wherein with Can also be ;n and m are 0, 1, or 2.

In this embodiment, preferably, the compound of the formula I accounts for 15%-25% of the total weight of the liquid crystal composition; the compound of the formula II accounts for 3%-8% of the total weight of the liquid crystal composition; The compound of the formula III accounts for 20%-40% of the total weight of the liquid crystal composition; the compound of the formula IV accounts for 20%-40% of the total weight of the liquid crystal composition; and the compound of the formula V accounts for The liquid crystal composition has a total weight of 5% to 15%.

Further, the compound of the formula I is selected from the group consisting of one or more of the following compounds: ;and Wherein R _{11 is} selected from the group consisting of C ₁ -C ₅ alkyl or alkoxy groups and C ₂ -C ₅ alkenyl or alkenyloxy groups.

The compound of formula II is selected from the group consisting of one or more of the following compounds: ;and Wherein R _{22 is} selected from the group consisting of C ₁ -C ₅ alkyl or alkoxy groups and C ₂ -C ₅ alkenyl or alkenyloxy groups.

The compound of formula III is selected from the group consisting of one or more of the following compounds: ;and Wherein R ₃₁ to R _{34 are} selected from the group consisting of C ₁ to C ₅ alkyl or alkoxy groups and C ₂ to C ₅ alkenyl groups or alkenyloxy groups.

The compound of formula IV is selected from the group consisting of one or more of the following compounds: ;and Wherein R _{42 is} selected from the group consisting of C ₁ -C ₅ alkyl or alkoxy groups and C ₂ -C ₅ alkenyl or alkenyloxy groups.

The compound of the formula V is selected from the group consisting of one or more of the following compounds: ;and Wherein R _{51 is} selected from the group consisting of C ₁ -C ₅ alkyl or alkoxy groups and C ₂ -C ₅ alkenyl or alkenyloxy groups.

Wherein the compound of formula I is selected from the group consisting of one or more compounds of the group consisting of: ;and The compound of formula II is selected from compounds of one or more of the group consisting of: ;and The compound of formula III is selected from compounds of one or more of the group consisting of: ;and The compound of formula IV is selected from compounds of one or more of the group consisting of: ;and The compound of the formula V is selected from compounds of one or more of the group consisting of: ;and

The present invention determines the liquid crystal medium including the liquid crystal composition by a combination experiment with the above compound, and has a good flat dielectric anisotropy frequency dependence, thereby exhibiting in the liquid crystal composition. The voltage dependence with frequency is reduced, the stability of the liquid crystal display is improved, and the use environment is wider.

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

Fig. 1 is a graph showing the low-temperature-voltage frequency dependency of Preferred Embodiment 1 and Comparative Example 1 of the present invention.

Fig. 2 is a graph showing the low-temperature-voltage frequency dependence of Preferred Embodiment 2 and Comparative Example 2 of the present invention.

The invention will now be described in connection with specific embodiments. It is to be understood that the following examples are illustrative of the invention and are not intended to limit the invention. Other combinations and various modifications within the inventive concept can be made without departing from the spirit or scope of the invention.

The liquid crystal displays used in the following embodiments are all TN-TFT liquid crystal displays, and have a cell thickness d = 7 μm, and are composed of a polarizer (polarizer), an electrode substrate, and the like. The display is in a normally white mode, that is, when no voltage difference is applied between the row and column electrodes, the observer observes the color of the white primitive. 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:

Taking the following structure as an example, the structure is represented by the code in Table 1: It can be expressed as 3PTGQP3, and it is like: It can be expressed as nCPTPm, where n represents the number of C atoms of the left-end alkyl group, for example, n is "3", which means that the alkyl group is -C ₃ H ₇ ; C in the code represents cyclohexane group; P represents a phenylene group; 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", that is, the alkyl group at the right end is -CH ₃ .

The shorthand codes of the test projects in the examples are respectively expressed as: Among them, the refractive index anisotropy was measured by an Abbe refractometer under a sodium light (589 nm) light source at 20 ° C; the dielectric test box was a TN90 type, and the cell thickness was 7 μm.

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 is described in Organic Syntheses (John Wiley & Sons, Inc), Organic Reactions (Organic Reactions, John Wiley & Sons, Inc) , Comprehensive Organic Synthesis (Pergamon Press), New Experimental Chemistry Lecture (Maruzen) and other publications.

The 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, ultrasonication, suspension, or the like in a predetermined ratio.

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

Comparative Example 1

A comparative liquid crystal composition was prepared according to each compound and weight percentage listed in Table 2, and was filled in the performance test between the two substrates of the liquid crystal display. The test data are as follows:

Example 1

According to the compounds listed in Table 3 and the weight percentages, the liquid crystal composition of the invention was prepared and filled in the performance test between the two substrates of the liquid crystal display. The test data are as follows:

The conventional performance parameters of the composition of Example 1 and Comparative Example 1 were the same, but the components were different, and the weight ratio of each component was also different, resulting in a frequency-dependent difference. Example 1 at normal temperature The frequency dependence of Comparative Example 1 was similar, but at a low temperature, the frequency-dependent difference between Example 1 and Comparative Example 1 was significant, and Example 1 had a significant voltage-frequency dependence, as shown in FIG.

Comparative Example 2

A comparative liquid crystal composition was prepared according to each compound and weight percentage listed in Table 5, and was filled in the performance test between the two substrates of the liquid crystal display. The test data are as follows:

Example 2

The liquid crystal composition of the invention was prepared according to each compound and weight percentage listed in Table 6, and was filled in the performance test between the two substrates of the liquid crystal display. The test data are as follows:

The conventional performance parameters of the composition of Example 2 and Comparative Example 2 were the same. Due to the difference in composition and weight ratio of the composition, the frequency dependence of Example 2 and Comparative Example 2 was similar at normal temperature, but at low temperature, the voltage-frequency dependence of Example 2 was significantly better than that of Comparative Example 2, as shown in the figure. 2 is shown.

Claims (10)

A liquid crystal composition for use in an active matrix liquid crystal display comprising: a compound of the formula I in an amount of from 14% to 30% by weight based on the total weight of the liquid crystal composition a compound of the formula II in an amount of from 2% to 10% by weight based on the total weight of the liquid crystal composition One or more compounds selected from the group consisting of compounds of the formulae IIIa to IIId, which comprise from 10% to 50% by weight based on the total weight of the liquid crystal composition a compound of the formula IV which comprises from 5% to 50% by weight based on the total weight of the liquid crystal composition And a compound of the formula V in an amount of from 2% to 20% by weight based on the total weight of the liquid crystal composition Wherein R ₁₁ , R ₂₁ to R ₂₂ , R ₃₁ to R ₃₄ , R ₄₁ to R ₄₂ , and R ₅₁ to R ₅₂ may be the same or different and are independently selected from the group consisting of H, halogen, C1 to C7 alkyl or alkane. a group consisting of an oxy group and a C ₂ -C ₇ alkenyl group or an alkenyloxy group; X ₁ -X ₃ , Y ₁ -Y ₉ , Z ₁ -Z ₂ may be the same or different and independently of each other H or F; , Y ₂ , Y ₈ may also be a C ₁ ~ C ₇ alkyl or alkoxy group; with Can be the same or different, independently of each other or And One or more of the Hs may be replaced by F independently of each other; wherein with Can also be n and m are 0, 1, or 2. The liquid crystal composition of claim 1, wherein the compound of the formula I accounts for 15% to 25% by weight of the total weight of the liquid crystal composition; the compound of the formula II accounts for 3% of the total weight of the liquid crystal composition - 8%; the compound of the formula III accounts for 20%-40% of the total weight of the liquid crystal composition; the compound of the formula IV accounts for 20%-40% of the total weight of the liquid crystal composition; and the formula V The compound accounts for 0% to 15% of the total weight of the liquid crystal composition. The liquid crystal composition of claim 2, wherein the compound of the formula I is selected from the group consisting of one or more of the following compounds: ;and Wherein R _{11 is} selected from the group consisting of C ₁ -C ₅ alkyl or alkoxy groups and C ₂ -C ₅ alkenyl or alkenyloxy groups. The liquid crystal composition of claim 2, wherein the compound of the formula II is selected from the group consisting of one or more of the following compounds: ;and Wherein R _{22 is} selected from the group consisting of C ₁ -C ₅ alkyl or alkoxy groups and C ₂ -C ₅ alkenyl or alkenyloxy groups. The liquid crystal composition of claim 2, wherein the compound of the formula III is selected from the group consisting of one or more of the following compounds: ;and Wherein R ₃₁ to R _{34 are} selected from the group consisting of C ₁ to C ₅ alkyl or alkoxy groups and C ₂ to C ₅ alkenyl groups or alkenyloxy groups. The liquid crystal composition of claim 2, wherein the compound of the formula IV is selected from the group consisting of one or more of the following compounds: ;and Wherein R _{42 is} selected from the group consisting of C ₁ -C ₅ alkyl or alkoxy groups and C ₂ -C ₅ alkenyl or alkenyloxy groups. The liquid crystal composition of claim 2, wherein the compound of the formula V is selected from the group consisting of one or more of the following compounds: ;and Wherein R _{51 is} selected from the group consisting of C ₁ -C ₅ alkyl or alkoxy groups and C ₂ -C ₅ alkenyl or alkenyloxy groups. The liquid crystal composition according to any one of the preceding claims, wherein the compound of the formula I is selected from the group consisting of one or more of the following compounds: ;and The compound of formula II is selected from compounds of one or more of the group consisting of: ;and The compound of formula III is selected from compounds of one or more of the group consisting of: ;and The compound of formula IV is selected from compounds of one or more of the group consisting of: ;and The compound of the formula V is selected from compounds of one or more of the group consisting of: ;and The liquid crystal composition according to any one of the preceding claims, wherein the liquid crystal composition comprises: 3% of the total weight of the liquid crystal composition of the compound II-1-1; and 7% by weight of the total weight of the liquid crystal composition Compound IV-1-1; compound IIIb-1-1 in an amount of 7% by weight based on the total weight of the liquid crystal composition; compound IIIb-1-2 in an amount of 8% by weight based on the total weight of the liquid crystal composition; % of compound IIIa-1-1; compound IIIa-1-2 in an amount of 7% by weight based on the total weight of the liquid crystal composition; compound IIIc-1-1; 6% by weight based on the total weight of the liquid crystal composition; 5% of the compound IIIc-1-2; 6% of the total weight of the liquid crystal composition of the compound V-3-2; 10% by weight of the total weight of the liquid crystal composition of the compound IIIb-2-1; 11% by weight of the compound IV-2-1; 11% of the total weight of the liquid crystal composition of the compound IIIb-2-2; 8% of the total weight of the liquid crystal composition of the compound I-2-1; and the liquid crystal combination The compound I-1-1 having a total weight of 8%, or the liquid crystal composition comprises: Compound II-1-2 which is 4% by weight based on the total weight of the liquid crystal composition; and Compound II which accounts for 2% by weight of the total weight of the liquid crystal composition Id-2-2; compound IIId-1-2; 6% of the total weight of the liquid crystal composition; compound IIId-1-1; 10% by weight based on the total weight of the liquid crystal composition Compound IIIb-1-2; compound IIIc-1-1 in an amount of 8% by weight based on the total weight of the liquid crystal composition; compound IIIc-1-2 in an amount of 8% by weight based on the total weight of the liquid crystal composition; 5% by weight based on the total weight of the liquid crystal composition Compound IIIc-1-3; compound IIIb-2-1 accounting for 14.5% of the total weight of the liquid crystal composition; compound IV-2-1 accounting for 16.5% of the total weight of the liquid crystal composition; The liquid crystal composition had a total weight of 18% of the compound I-2-1; and 4% of the total weight of the liquid crystal composition of the compound I-2-2. An active matrix display comprising the liquid crystal composition according to any one of claims 1 to 9.