KR20030033770A - Liquid crystal having high speed and high temperature using liquid crystal mixture of fluoroisothionate - Google Patents

Abstract

PURPOSE: Provided is a nematic liquid crystal composition having high phase transition temperature of liquid crystals and high response velocity, which can be used for preparing LCD elements. CONSTITUTION: The nematic liquid crystal composition contains: 2-80wt% of a nematic liquid crystal compound represented by the formula 1 or nematic liquid crystal compounds represented by the formula 2 and 3, wherein the weight ratio of the compound represented by the formula 2 and the compound represented by the formula 3 is 1-80:1-80; 20-98wt% of at least one liquid crystal compound selected from the compounds represented by the formula 4, 5, and 6, wherein R2 and R3 are independently or simultaneously C1-C15 alkyl or alkoxy, B is phenyl or cyclohexyl, C is a single bond, -CH2CH2-, or -COO-, X and Y are independently or simultaneously hydrogen or fluoro atom, and Z is hydrogen, -OCF3, or fluoro atom.

Description

LIQUID CRYSTAL HAVING HIGH SPEED AND HIGH TEMPERATURE USING LIQUID CRYSTAL MIXTURE OF FLUOROISOTHIONATE}

The present invention relates to a high speed high temperature liquid crystal using a liquid crystal mixture of fluoroisocyionate, and more particularly, to a high speed high temperature liquid crystal composition including a nematic liquid crystal compound capable of improving phase transition temperature and response speed.

In the field of display, Twist Nematic-Liquid Crystal Display (TN-LCD) has been continuously expanding its scope, and is expanding its scope to notebooks, monitors, home TVs, and small and medium-sized enterprises.

The LCD has a physical advantage of light and thin, but there is a problem that the brightness is weaker than the CRT (Cathod Ray Tube) among the various factors that determine the image quality. In addition, as the LCD-TV market, which is attracting attention as a large market for monitors and new LCDs, is gradually formed and spread, the demand for high brightness and high-speed response technology is emerging as an important matter.

In order to obtain high brightness in LCD, the liquid crystal phase transition temperature must be kept higher than the current due to tube current. In addition, for high-speed response, there is a method of reducing the rotational viscosity of the material or increasing the refractive index of the liquid crystal.

Most LCD products that have been commercialized so far use nematic liquid crystals as TN, IPS, and VA modes, and have a phase transition temperature of about 70 to 80 ° C. and a response speed of about 20 to 30 ms. However, since the phase transition temperature and the response speed are still not satisfactory, the improvement of the response speed and the increase of the phase transition temperature are urgently required to realize TV applications and moving images.

SUMMARY OF THE INVENTION In view of the problems of the prior art as described above, an object of the present invention is to provide a nematic liquid crystal composition having a high phase transition temperature and realizing a high response speed.

Another object of the present invention is to provide an LCD device manufactured by including the high speed high temperature nematic liquid crystal composition.

In order to achieve the above object, the present invention provides a nematic liquid crystal composition comprising a nematic liquid crystal compound represented by the following formula (1).

[Formula 1]

In addition, the present invention provides a nematic liquid crystal composition comprising a nematic liquid crystal compound represented by the following formulas (2) and (3).

[Formula 2]

[Formula 3]

Hereinafter, the present invention will be described in detail.

The inventors of the present invention can solve the problems in the conventional nematic liquid crystal composition, to achieve the high-speed response technology through the development of high-temperature high-speed liquid crystal by increasing the phase transition temperature of the liquid crystal, the refractive index anisotropy, etc. aiming at high brightness and high speed response technology The liquid crystal composition containing the compound of 1 was developed, and this invention was completed.

According to the nematic liquid crystal composition of the present invention, by blending a specific nematic mixture with a key material in a conventional commercial liquid crystal composition, the temperature may be increased by at least 10 ° C. or more, and the response speed may be about 10 ms compared to conventional commercial liquid crystals. .

It is preferable that the nematic liquid crystal composition of this invention contains a 2 or more types of liquid crystal compound.

The nematic liquid crystal composition of the present invention includes the compound of Formula 1. In addition, the nematic liquid crystal composition of the present invention includes the compound of Formula 2 and Formula 3. The amount of the compound of Formula 1 or a mixture of Formulas 2 and 3 is preferably 2 to 80% by weight. At this time, when the amount of the compound of Formula 1 or the mixture of Formulas 2 and 3 is out of the range, there is a problem that a high phase transition temperature and a high response speed cannot be obtained. The mixing ratio of the compounds of Formulas 2 and 3 is preferably used in a weight ratio of 1 to 80: 1 to 80.

In addition, the liquid crystal composition of the present invention includes at least one or more commercially available liquid crystal compounds together with the compound of Formula 1. In addition, the liquid crystal composition of the present invention includes at least one or more liquid crystal compounds together with the compounds of Formulas 2 and 3. It is preferable to use at least one liquid crystal compound selected from the group consisting of compounds represented by the following general formulas (4), (5) and (6) as the commercially available liquid crystal compound. It is preferable that the nematic liquid crystal composition of this invention contains 20 to 98 weight% of a commercial liquid crystal compound.

[Formula 4]

[Formula 5]

[Formula 6]

Wherein R ₂ and R ₃ are each independently or simultaneously an alkyl or alkoxy group having 1 to 15 carbon atoms; B is phenyl or cyclohexyl; C is a single bond, -CH ₂ CH _2- , or -COO-; X and Y are each independently or simultaneously hydrogen or fluoro atoms; Z is hydrogen, -OCF ₃ or a fluoro atom.

The commercially available liquid crystal compound used in the present invention may be used by a combination of the compounds of Formulas 3, 4, and 5, and, for example, a commercially available liquid crystal compound may be selected from four compounds of Formulas 4-6. It is more preferable to divide into groups (G1 to G4) and use them. The composition of the G1 to G4 is preferably mixed with 10 to 25% by weight of G1, 10 to 20% by weight of G2, 30 to 40% by weight of G3 and 20 to 40% by weight of G4. The G1 group is at least two or more compounds selected from the group of compounds represented by Formulas 5 and 6 above; G2 is at least two or more compounds selected from the group of compounds represented by formulas (4) and (5); G3 is at least two or more compounds selected from the group of compounds represented by Formulas 5 and 6; And G4 is at least two or more compounds selected from the group of compounds represented by formula (4).

Such nematic liquid crystal composition of the present invention is excellent in physical properties such as birefringence (Δn), dielectric anisotropy (Δε), in particular, the phase transition temperature is high and the response speed is fast. Accordingly, the high-speed, high-temperature liquid crystal composition of the present invention is a device of various LCD families requiring liquid crystal, preferably a twisted nematic (TN) device device, a super twisted nematic (STN) device device, a thin film transistor-twisted nema It is used to manufacture TFT-TN device, IPS (In plane switching) device device, AOC (Array on color filter), COA (Color filter on array) device device, etc. Branches can obtain LCD.

Hereinafter, the Example and comparative example of this invention are described. However, the following examples illustrate the present invention and do not limit the present invention.

Comparative Example 1

A commercial mixture "TM1" constructed as shown in Table 1 below was prepared (TM1 = G1 + G2 + G3 + G4). The content of each G1 to G4 represents weight percent.

compound Content (% by weight) G1 (X is F) 3.4 10.0 10.4 G2 2.5 2.6 7.4 G3 7.0 3.5 3.97 11.07 G4 20.8 5.36 6.6 5.4

The liquid crystal mixture composed of TM1 of Table 1 is a commercially available liquid crystal, and the response speed of the liquid crystal was measured to be 16 to 18 ms at a cell gap of 4.6 μm, and the phase transition temperature was 80 ° C.

[Examples 1 to 4]

In order to confirm the change in physical properties corresponding to the high temperature high-speed response, the mixed liquid crystal of the compound of formula 1 and the remaining content of the compound of formula 1 having a high phase transition temperature and a high refractive index anisotropy as shown in Table 2 as key ingredients TM1 was mixed and the phase transition temperature, refractive index anisotropy, dielectric anisotropy, and response speed (cell gap 3.77 μm) of the liquid crystals were measured according to the% concentration, and the results are shown in Table 2 below.

[Formula 1]

Content (% by weight) Tni (℃) △ n Δε (20 ° C) Response speed (ms) Comparative Example 1 - 80 0.0773 5.9 16-18 Example 1 14 93 0.0982 7.5 9.7 Example 2 16.7 96 / 98.3 0.1027 (20 ℃) /0.0907 (28 ℃) 7.8 (20 ℃) /6.01 (28 ℃) 10.2 Example 3 20 99 0.1082 8.2 10.3 Example 4 26 104 0.1181 8.9 10.7 ** Denominator: Actual value example-96 ° C (calculated) /98.3°C (actually measured)

In Table 2, all of the Examples 1 to 4 compared to Comparative Example 1 (TM1) without the compound of Formula 1 obtained excellent results, in particular, the response rate was reduced to 56% and phase transition temperature increased to 122% This indicates that it is effective for use as a high speed hot liquid crystal.

Example 5

Instead of Formula 1 of Examples 1 to 4, the compounds of Formulas 2 and 3 were used as key materials to measure phase transition temperature, refractive index anisotropy, dielectric anisotropy, and response speed (cell gap 3.75 μm) of the liquid crystal. That is, 79.7 wt% TM1, 10.2 wt% compound of formula 2 and 10.1 wt% compound of formula 3 were mixed. The result is as follows.

[Formula 2]

[Formula 3]

Liquid crystal phase temperature range: -30 ° C to 103 ° C, Δn: 0.0952 (28 ° C), Δε: 6.17 (28 ° C),

Response time: 10.8 ms, Vth: 1.6v (28 ℃), VHR: 98%

In the results, the response speed is reduced to 59% compared to TM1 and the phase transition temperature is increased to 127%, it can be seen that it is effective to use as a high-speed hot liquid crystal. The previously reported NCS mixture has a phase transition temperature, refractive index anisotropy and response rate of Tni: 71 ° C., Δn: 0.15, response rate of 14.6 ms. In this case, low phase transition temperature and high refractive index are difficult to commercialize, and Tni: 95 ° C., When Δn: 0.089 and response speed: 21.3 ms, the response speed is slow, which makes it difficult to apply to high-speed high-temperature liquid crystal for moving picture. On the other hand, the above-described embodiments of the present invention satisfy both of high speed and high temperature corresponding to moving images at the same time, and thus have a high possibility of commercialization.

As described above, the nematic liquid crystal composition according to the present invention has a larger phase transition temperature, refractive index anisotropy, dielectric constant anisotropy, and response speed than a commercially available mixed liquid crystal including the compound of Formula 1 or the compounds of Formulas 2 and 3 above. Is very fast and effective for use in LCD manufacturing.

Claims (10)

A nematic liquid crystal composition comprising the nematic liquid crystal compound represented by Formula 1 below: [Formula 1] Nematic liquid crystal composition comprising a nematic liquid crystal compound represented by the formula (2) and [Formula 2] [Formula 3] The method of claim 1, a) 2 to 80% by weight of the nematic liquid crystal compound represented by Formula 1; And b) 20 to 98% by weight of at least one liquid crystal compound selected from the group consisting of compounds represented by the following formulas (4), (5) and (6): Nematic liquid crystal composition comprising: [Formula 4] [Formula 5] [Formula 6] Wherein R ₂ and R ₃ are each independently or simultaneously an alkyl or alkoxy group having 1 to 15 carbon atoms; B is phenyl or cyclohexyl; C is a single bond, -CH ₂ CH _2- , or -COO-; X and Y are each independently or simultaneously hydrogen or fluoro atoms; Z is hydrogen, -OCF ₃ or a fluoro atom. The method of claim 2, a) 2 to 80% by weight of the nematic liquid crystal compound represented by Formulas 2 and 3; And b) 20 to 98% by weight of at least one liquid crystal compound selected from the group consisting of compounds represented by the following formulas (4), (5) and (6): Nematic liquid crystal composition comprising: [Formula 4] [Formula 5] [Formula 6] Wherein R ₂ and R ₃ are each independently or simultaneously an alkyl or alkoxy group having 1 to 15 carbon atoms; B is phenyl or cyclohexyl; C is a single bond, -CH ₂ CH _2- , or -COO-; X and Y are each independently or simultaneously hydrogen or fluoro atoms; Z is hydrogen, -OCF ₃ or a fluoro atom. The nematic liquid crystal composition according to claim 2 or 4, wherein the mixed weight ratio of the compounds of Formulas 2 and 3 is 1 to 80: 1 to 80. A twisted nematic (TN) device device fabricated comprising the nematic liquid crystal composition of claim 1. A super twisted nematic (STN) device device fabricated comprising the nematic liquid crystal composition of claim 1. A thin film transistor-twist nematic (TFT-TN) device device made by comprising the nematic liquid crystal composition according to claim 1. An in plane switching (IPS) device device prepared by comprising the nematic liquid crystal composition according to claim 1. An array on color filter (AOC) or color filter on array (COA) device device prepared by comprising the nematic liquid crystal composition of claim 1.