KR100853226B1 - Liquid crystal composition having high-spped and liquid crystal display using the same - Google Patents

Abstract

The present invention relates to a high speed liquid crystal composition and a liquid crystal display device using the same, and more particularly, to a high speed liquid crystal capable of satisfying high speed response characteristics due to high phase transition temperature, including a new nematic liquid crystal compound having high refractive index and high dielectric constant. A composition and a liquid crystal display device using the same.

Nematic liquid crystal compound, high speed high temperature liquid crystal composition, liquid crystal display device

Description

High-speed liquid crystal composition and liquid crystal display device using the same {LIQUID CRYSTAL COMPOSITION HAVING HIGH-SPPED AND LIQUID CRYSTAL DISPLAY USING THE SAME}

The present invention relates to a moving picture-compatible high-speed liquid crystal composition and a liquid crystal display device, and more particularly, high phase transition temperature of the liquid crystal, high birefringence and dielectric constant anisotropy, so that high-speed response speed can be realized, and various liquid crystals such as LCDs are required. The present invention relates to a liquid crystal composition corresponding to a moving picture effective to be applied to a device and a liquid crystal display using the same.

Twist Nematic (TN) -LCD has continued to expand in the field of displays and is expanding into notebooks, monitors as well as home TVs and small and medium-sized. In addition, as the LCD-TV market, which is attracting attention as a large market for monitors and new LCDs, is gradually forming and spreading, the demand for high brightness and high-speed response technology is emerging as an important matter. For high brightness, the phase transition temperature of the liquid crystal should be maintained higher than the current due to the tube current in the backlight. TN, IPS (CE), and VA modes are mentioned as TV-product groups, but IPS (CE), VA, etc. have the advantages of viewing angle, but the slow response speed makes it difficult to cope with moving images.                         

On the other hand, TN mode has a narrow viewing angle, but if it compensates the viewing angle and improves response speed by developing compensation film, it will be the most competitive TV mode in terms of production yield. However, currently commercially available TN liquid crystal has a low phase transition temperature of about 80 ℃.

To solve this problem, the following conditions must be satisfied. First, in order to quickly improve the response speed, the viscosity of the liquid crystal material should be lowered and adjusted in the range of 20 to 25 mm 2 / s. Second, in order to lower the driving voltage, the dielectric anisotropy (Δε) should be increased and adjusted within the range of 10 to 15 (35 ° C, 1kHz). Third, it should have a nematic phase in a wide temperature range, with a preferred nematic phase temperature range of -30 to 80 ° C. Fourth, the birefringence (Δn) value should be 0.20 (25 ° C) or more.

As described above, most of LCD products that have been commercialized so far use nematic liquid crystals as TN, IPS (CE) and VA modes, and have a phase transition temperature of about 70 to 80 ° C. and a response time of about 20 to 30 ms. .

Therefore, in order to realize TV application and moving picture, improvement of response speed and increase of phase transition temperature are urgently required.

Therefore, in order to solve the problems of the prior art as described above, a nematic that can realize a high-speed response technology through the development of high-temperature high-speed liquid crystal by increasing the refractive index anisotropy and increasing the phase transition temperature of the liquid crystal for the purpose of high brightness, high speed response technology It is an object to provide a liquid crystal composition.                         

Another object of the present invention is to provide a liquid crystal display device using the 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]

Wherein R is C _n H _{2n + 1} O, C _n H _{2n + 1} , or C _n H _2n-1 , where n is an integer from 1 to 15;

n is an integer from 1 to 3;

B is phenyl, cyclohexane, phenyl-cyclohexane, cyclohexane-phenyl, a direct single bond (-), -CH ₂ CH _2- , -COO-, -C = C-, or -C≡C-;

X is H, F, Cl, Br, NCS, or SCN;

Y is NCS, SCN or F;

Z is H, F, Cl, Br, NCS, or SCN.)

In addition, the present invention provides a liquid crystal display device comprising the nematic liquid crystal composition described above.

Preferably, the liquid crystal display device is a liquid crystal display device of a twisted nematic (TN), STN, TFT-TN mode, an in plane switching (IPS) mode, or a FFS (Fringe filed switching) liquid crystal display. In addition, the liquid crystal display includes an AOC, COA, or LCOS liquid crystal display, or VA (vertically align) liquid crystal display.

Hereinafter, the present invention will be described in detail.

In the present invention, by manufacturing a key material of high refractive index, high dielectric constant and blended to the host liquid crystal nematic that can increase the temperature by 20 ℃ or more than the conventional commercial liquid crystal and reach the response speed to 70% or less than the conventional liquid crystal It features a liquid crystal composition and a liquid crystal display device using the same.

The liquid crystal compound of the present invention has a high birefringence, a high dielectric constant and a high phase transition temperature, and thus may be used as a new high-speed response liquid crystal composition.

Such a liquid crystal composition of the present invention preferably contains 1 to 100% by weight of a compound selected from the group consisting of the compound of Formula 1.

In addition, the liquid crystal composition of the present invention may further include a compound selected from the group consisting of compounds represented by the following Chemical Formula 2, Chemical Formula 3, Chemical Formula 4, and Chemical Formula 5 together with the compound of Chemical Formula 1.

[Formula 2]

[Formula 3]

R ₂ -A ₁ -B ₁ -X ₁

[Formula 4]

[Formula 5]

(In the above formulas,

R is C _n H _{2n + 1} O, C _n H _{2n + 1} , or C _n H _2n-1 , where n is an integer from 1 to 15;

A is phenyl, cyclohexane, phenyl-cyclohexane, cyclohexane-phenyl, a direct single bond (-), -C = C-, or -C≡C-;

X is H, F, Cl, Br, or NCS;

Y is NCS, SCN or F;

Z is H, F, Cl, Br, or NCS;

Each R ₂ is independently or simultaneously C _n H _{2n + 1} , or C _n H _2n , where n is an integer from 1 to 15;

,

, 또는

이며;A ₁ and B ₁ are each independently or simultaneously

,

, or

Is;

X ₁ is F, CF ₃ , OCF ₃ , CH = CF ₂ , or OCH = CF ₂ ;

또는

이며;A ₂ are each independently or simultaneously

or

Is;

A ₃ , B ₂ and C are each independently or simultaneously F, CF ₃ , OCF ₃ , or H.)

In this case, the content of the nematic liquid crystal compound represented by Formula 1 may be 1 to 90% by weight with respect to the total composition, more preferably 5 to 50% by weight. At this time, when the amount of the chemical formula 1 is less than 1% by weight, the response speed is slow, and when it exceeds 80% by weight, there is a problem that a high phase transition temperature and a high speed response speed cannot be obtained.

The content of at least one liquid crystal compound selected from the group consisting of compounds represented by Formula 2, Formula 3, Formula 4, and Formula 5 is preferably 10 to 99% by weight.

In this case, the compound represented by Formula 3 to 5 is the composition of the parent liquid crystal used to make a new liquid crystal composition with a host mixture. The composition of the host liquid crystal may be arbitrarily mixed and used by dividing a compound selected from the compounds of Formulas 3 to 5 into several groups, for example, G1 is 30 to 40% by weight, G2 is 15 to 20% by weight, and G3 is 10 to 20 wt%, G4 may be composed of 15 to 25% by weight, but is not limited thereto.                     

In addition, the liquid crystal composition of the present invention may be used in addition to the liquid crystal compound of Formula 1 in order to improve the properties of the liquid crystal composition generally known nematic liquid crystal, smectic liquid crystal, cholesteric liquid crystal and the like. However, when a large amount of such liquid crystal compound is added, the characteristics of the liquid crystal composition to be obtained may be reduced. Therefore, the addition amount should be limited in accordance with the required characteristics of the nematic liquid crystal composition.

In addition, the present invention can provide a liquid crystal display device of various LCD products by using the composition as a liquid crystal material to fill a variety of display liquid crystal cells with appropriate additives. For example, an active matrix method liquid crystal display device including the nematic liquid crystal composition, an active matrix method IPS (in-plane switching) liquid crystal display device, and FFS (Fringe filed) Switching type, Simple matrix type Twistnematic liquid crystal display, Simple matrix type Super twist nematic type liquid crystal display, OCB, Thin film transistor Twisted nematic (TFT-TN) liquid crystal display, AOC, COA, or LCOS liquid crystal display, VA (vertically align) liquid crystal display and the like can be manufactured.

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.

Example 1

The composition of the host liquid crystal mixture used as a parent to make a new liquid crystal is shown in Table 1 (G1 + G2 + G3 + G4). Each content represents weight percent.                     

compound sign Content (% by weight) G1

3CCO1 6.6

2CC3 " 5.4

5CC2 " 20.8

5CC3 4.1 G2

2CCP ^OCF3 7.4

2CCP ^FFF 7.0

2CCP ^{F, OCF3} 5.86

2CPFP ^FFF 4.97 G3                                             

2 "CCP ^FF 11.07

3CCP ^OCF3 2.5

3CCP ^FFF 2.5 G4 (X is F)

2esP ^X 3.4

3CPFesP ^X 9.0

3CCesP ^X 9.4

In the case of the host liquid crystal mixture, m.p was −20 ° C., Tni 80 ° C., birefringence (Δn) 0.075, and dielectric anisotropy (Δε) 5.63, and the response speed was 16.2 ms at a cell gap of 4.5 μm as an electro-optic characteristic.

Thereafter, using the host liquid crystal of the composition and mixed 17 to 18% by weight of the compound of formula 1 under the same conditions as in Table 2 to prepare a new liquid crystal. In Table 2, mp is a temperature at which phase transition from a crystal phase to a liquid crystal phase or an isotropic liquid phase, and T _NI represents each temperature at which phase transition from a liquid phase to an isotropic liquid phase. At this time, the birefringence and the dielectric constant of the mixed liquid crystal were measured and the birefringence (Δn) and the dielectric constant of the single liquid crystal compound were determined by extrapolation. Each compound was sufficiently purified by removing impurities using distillation, column purification, and recrystallization.

R n B X Y Z sign m.p T _NI Birefringence (Δn) Dielectric constant anisotropy (Δε) Formula 1a ethyl One - F NCS H 2CPPSF 97.8 192.5 0.302 12 Formula 1b ethyl One - F NCS F 2CPPSFF 49.9 163.8 0.285 15.6

As shown in the results, it can be seen that the compound of Formula 1 of the present invention has improved birefringence and dielectric anisotropy compared to the host.

Example 2

After the composition of the host mixture was changed and the liquid crystal was prepared by adding the compound of Formula 1a as a main essential component, physical properties are shown in Table 3 below.

Formula 1a 17%

Trans, trans-4-ethyl-4'-pentylbicyclohexane 17.43%

Trans, trans-4-propyl-4'-pentylbicyclohexane 3.32%

1-methoxy- (p-trans-4-propylcyclohexyl) benzene 5.81%

Trans, trans-4-propyl-4'-propylbicyclohexane 4.15%

[Trans-4- (trans-4-ethylcyclohexyl) cyclohexyl] trifluoromethoxybenzene 5.81%

[Trans-4- (trans-4-ethylcyclohexyl) cyclohexyl] -1,2,6-trifluorooven zen 5.81%

[Trans-4- (trans-4-ethylcyclohexyl) cyclohexyl] -2-fluoro-1-trifluoromethoxybenzene 3.32%

[Trans-4- (trans-4-ethylcyclohexyl) -2-fluorophenyl] -1,2,6-trifluorobenzene 3.32%

[Trans-4- (trans-4-ethylcyclohexyl) cyclohexyl] -1,2-difluorobenzene 9.13%

[Trans-4- (trans-4-ethylcyclohexyl) cyclohexyl] 4-fluorophenylcarboxylate 3.32%

[4- (trans-4-ethylcyclohexyl) -2-fluorophenyl] 4-fluorophenylcarboxylate 7.47%

[Trans-4- (trans-4-propylcyclohexyl) cyclohexyl] trifluoromethoxybenzene 3.32%

[Trans-4- (trans-4-propylcyclohexyl) cyclohexyl] -1,2,6-trifluorobenzene 3.32%

[Trans-4- (trans-4-propylcyclohexyl) cyclohexyl] 4-fluorophenylcarboxylate 7.47%

T _NI Birefringence (Δn) Dielectric constant anisotropy (Δε) Response speed (ms) V10 (V) V90 (V) 96 0.115 6.68 9 1.5 2.6

As can be seen from the above results, the composition of the present invention has a response speed of about 56%, and a phase transition temperature of about 120%, and a voltage holding ratio of 99.4, which is suitable for use in a 3.6 to 4 μm cell gap. Can be used.

Example 3

In the same manner as in Example 2, but changed the content of the compound of Formula 1a to 7%, 30%, respectively, measured physical properties and the results are shown in Table 4 below.

Content (% by weight) Tni (℃) △ n Δε (20 ° C) 7 87.9 0.0909 6.1 30 113.8 0.1431 7.5

Looking at the results of Table 4, it can be seen that the liquid crystal properties are adjusted according to the amount of addition and the amount of addition can be adjusted according to the use.

Example 4

In order to prepare a new liquid crystal, the compounds of Formulas 2a and 2b having the physical properties shown in Table 5 were used.

R A X Y Z sign m.p T _NI Birefringence (Δn) Dielectric constant anisotropy (Δε) Formula 2a profile Phenyl F NCS H 3CCetPSF 72.9 189 9.8 0.163 Formula 2b profile Phenyl F NCS F 3CCetPSFF 81 175.2 14.2 0.169

In this case, when the compound of Formula 2a is mixed with the host liquid crystal by 7.3%, Tni 88 ° C., birefringence (Δn) 0.0875, dielectric anisotropy (Δε) (20 ° C.) is 6.70, and the response speed is /9.2 ms. (V _th ) was measured at 1.5.

In addition, when the compound of Formula 2a is mixed with the host liquid crystal 17.1% and 26%, respectively, physical properties are as follows. Here, an example of a denominator: actual value is 98 degreeC (calculated value) / 102 degreeC (actual value).

17.1%-Tni 98 ℃ / 102 ℃, birefringence (△ n) 0.1041 (20 ℃) /0.09 (28 ℃), dielectric anisotropy (Δε) 7.76 (20 ℃) /6.01 (28 ℃), response speed / 10.4ms

26%-Tni 108 ℃, birefringence (△ n) 0.1195, dielectric anisotropy (Δε) 8.74 (20 ℃), response speed /10.6ms

In the above results, the response speed is reduced to 65% compared to the host, the phase transition temperature is increased to 127%, the voltage retention is 98%, which can be seen that it is suitable for use in high-speed hot liquid crystal.

Then, using the compound of Formula 2a and 2b together with the compound of Formula 1a and 1b to prepare a novel liquid crystal with the composition as follows.

Formula 1a 1.7%

Formula 1b 2.2%

Formula 2a 2.0%

Formula 2b 2.1%

Trans, trans-4-ethyl-4'-pentylbicyclohexane 19.3%

Trans, trans-4-propyl-4'-pentylbicyclohexane 3.7%                     

1-methoxy- (p-trans-4-propylcyclohexyl) benzene 6.4%

Trans, trans-4-propyl-4'-propylbicyclohexane 4.6%

[Trans-4- (trans-4-ethylcyclohexyl) cyclohexyl] trifluoromethoxybenzene 6.4%

[Trans-4- (trans-4-ethylcyclohexyl) cyclohexyl] -1,2,6-trifluorobenzene 6.4%

[Trans-4- (trans-4-ethylcyclohexyl) cyclohexyl] -2-fluoro-1-trifluoromethoxybenzene 3.7%

[Trans-4- (trans-4-ethylcyclohexyl) -2-fluorophenyl] -1,2,6-trifluorobenzene 3.7%

[Trans-4- (trans-4-ethylcyclohexyl) cyclohexyl] -1,2-difluorobenzene 10.1%

[Trans-4- (trans-4-ethylcyclohexyl) cyclohexyl] 4-fluorophenylcarboxylate 3.7%

[4- (trans-4-ethylcyclohexyl) -2-fluorophenyl] 4-fluorophenylcarboxylate 8.3%

[Trans-4- (trans-4-propylcyclohexyl) cyclohexyl] trifluoromethoxybenzene 3.7%

[Trans-4- (trans-4-propylcyclohexyl) cyclohexyl] -1,2,6-trifluorobenzene 3.7%                     

[Trans-4- (trans-4-propylcyclohexyl) cyclohexyl] 4-fluorophenylcarboxylate 8.3%

Physical properties of the liquid crystal are shown in Table 6 below.

T _NI Birefringence (Δn) Dielectric constant anisotropy (Δε) Response speed (ms) V10 (V) V90 (V) 86.7 0.0892 6.6 10.4 1.5 2.6

As can be seen from the above results, the composition of the present invention has a high birefringence and dielectric constant anisotropy and a fast response speed compared to the host is suitable for use in the cell gap of 4 ㎛.

As described above, in the case of the existing NCS mixture (for example, Tni 95 ° C., Δn 0.089, response speed 21.3 ms), the response speed is slow and it is difficult to apply to a high speed high temperature liquid crystal corresponding to moving images. In contrast, the embodiment of the present invention simultaneously satisfies two types of high speed and high temperature corresponding to moving images, and has a high possibility of commercialization.

As described above, the liquid crystal composition according to the present invention has a higher birefringence (Δn) and a dielectric anisotropy (Δε), a lower threshold voltage (V _th ), and a higher phase transition temperature than a commercially available mixed liquid crystal. It can realize high speed response speed and can drive low voltage, so it can be applied to various devices requiring liquid crystal such as LCD.

Claims (14)

A nematic liquid crystal composition comprising the nematic liquid crystal compound represented by Formula 1 below: [Formula 1]

Wherein R is C _n H _{2n + 1} O, C _n H _{2n + 1} , or C _n H _2n-1 , where n is an integer from 1 to 15; n is an integer from 1 to 3; B is phenyl-cyclohexane, cyclohexane-phenyl, -CH ₂ CH _2- ; X is H, F, Cl, Br, NCS, or SCN; Y is NCS, SCN or F; Z is H, F, Cl, Br, NCS, or SCN. The method of claim 1, A nematic liquid crystal compound represented by Formula 1, and At least one liquid crystal compound selected from the group consisting of compounds represented by the following Chemical Formulas 2, 3, 4 and 5 Nematic liquid crystal composition comprising: [Formula 2]

[Formula 3] R ₂ -A ₁ -B ₁ -X ₁ [Formula 4]

[Formula 5]

In the above formulas, R is C _n H _{2n + 1} O, C _n H _{2n + 1} , or C _n H _2n-1 , where n is an integer from 1 to 15; A is phenyl, cyclohexane, phenyl-cyclohexane, cyclohexane-phenyl, a direct single bond (-), -C = C-, or -C≡C-; X is H, F, Cl, Br, or NCS; Y is NCS, SCN or F; Z is H, F, Cl, Br, or NCS; Each R ₂ is independently or simultaneously C _n H _{2n + 1} , or C _n H _2n , where n is an integer from 1 to 15; A ₁ and B ₁ are each independently or simultaneously

,

, or

Is; X ₁ is F, CF ₃ , OCF ₃ , CH = CF ₂ , or OCH = CF ₂ ; A ₂ are each independently or simultaneously

or

Is; A ₃ , B ₂ and C are each independently or simultaneously F, CF ₃ , OCF ₃ , or H. The method of claim 2, 1 to 80% by weight of the nematic liquid crystal compound represented by Formula 1, and 20 to 99% by weight of at least one liquid crystal compound selected from the group consisting of compounds represented by Formula 2, Formula 3, Formula 4 and Formula 5 Nematic liquid crystal composition comprising a. A liquid crystal display device comprising the nematic liquid crystal composition of claim 1. The liquid crystal display device of claim 4, wherein the liquid crystal display device is a liquid crystal display device of a twist nematic (TN), STN, TFT-TN, In plane switching (IPS), or fringe filed switching (FFS) mode. LCD display device. The liquid crystal display device according to claim 4, wherein the liquid crystal display device is a liquid crystal display device in a vertically aligned (VA) mode. The liquid crystal display device according to claim 4, wherein the liquid crystal display device is an AOC, COA, or LCOS liquid crystal display device. A nematic liquid crystal composition comprising the nematic liquid crystal compound represented by Formula 1 below: [Formula 1]

Wherein R is C _n H _{2n + 1} O, C _n H _{2n + 1} , or C _n H _2n-1 , where n is an integer from 1 to 15; n is an integer from 1 to 3; B is phenyl, cyclohexane, phenyl-cyclohexane, cyclohexane-phenyl, a direct single bond (-), -CH ₂ CH _2- , -COO-, -C = C-, or -C≡C-; X is H, F, Cl, Br, NCS, or SCN; Y is SCN or F; Z is H, F, Cl, Br, NCS, or SCN. The method of claim 8, A nematic liquid crystal compound represented by Formula 1, and At least one liquid crystal compound selected from the group consisting of compounds represented by the following Chemical Formulas 2, 3, 4 and 5 Nematic liquid crystal composition comprising: [Formula 2]

[Formula 3] R ₂ -A ₁ -B ₁ -X ₁ [Formula 4]

[Formula 5]

In the above formulas, R is C _n H _{2n + 1} O, C _n H _{2n + 1} , or C _n H _2n-1 , where n is an integer from 1 to 15; A is phenyl, cyclohexane, phenyl-cyclohexane, cyclohexane-phenyl, a direct single bond (-), -C = C-, or -C≡C-; X is H, F, Cl, Br, or NCS; Y is NCS, SCN or F; Z is H, F, Cl, Br, or NCS; Each R ₂ is independently or simultaneously C _n H _{2n + 1} , or C _n H _2n , where n is an integer from 1 to 15; A ₁ and B ₁ are each independently or simultaneously

,

, or

Is; X ₁ is F, CF ₃ , OCF ₃ , CH = CF ₂ , or OCH = CF ₂ ; A ₂ are each independently or simultaneously

or

Is; A ₃ , B ₂ and C are each independently or simultaneously F, CF ₃ , OCF ₃ , or H. The method of claim 9, 1 to 80% by weight of the nematic liquid crystal compound represented by Formula 1, and 20 to 99% by weight of at least one liquid crystal compound selected from the group consisting of compounds represented by Formula 2, Formula 3, Formula 4 and Formula 5 Nematic liquid crystal composition comprising a. A liquid crystal display device comprising the nematic liquid crystal composition of claim 8. 12. The liquid crystal display of claim 11, wherein the liquid crystal display is a liquid crystal display in a twisted nematic (TN), STN, TFT-TN, In plane switching (IPS) or fringe filed switching (FFS) mode. LCD display device. The liquid crystal display device according to claim 11, wherein the liquid crystal display device is a liquid crystal display device in a vertically aligned (VA) mode. The liquid crystal display device according to claim 11, wherein the liquid crystal display device is an AOC, COA, or LCOS liquid crystal display device.