KR20050006627A - Nematic liquid crystal composition - Google Patents

Abstract

PURPOSE: Provided are a nematic liquid crystal composition which is improved in response velocity, refraction anisotropy and phase transition temperature, and a twist nematic (TN) device apparatus, a super twist nematic (STN) device apparatus, a TFT-TN device apparatus, an IPS (in plane switching) device apparatus and a vertically align device apparatus using the composition. CONSTITUTION: The nematic liquid crystal composition comprises a nematic liquid crystal compound represented by the formula 1; and a host mixture, wherein R is CnH2n+1O, CnH2n+1 or CnH2n-1 (wherein n is 1-10); L is a cyclohexylene group, a cyclohexylene-Ph group, a Ph-cyclohexylene group or Ph; a is 0 or 1; M is a cyclohexylene group, a cyclohexylene-Ph group, a Ph-cyclohexylene group or Ph; b is 0 or 1; N is -CF2O-, -CH2CH2-, -C=C- or a triple bond of C-C; c is 0 or 1; X is H, F, Cl, Br, NCS or CN; Y is H, F, Cl, Br, NCS or CN; d is 0 or 1; and Z is NCS, SCN or F.

Description

Nematic liquid crystal composition

The present invention relates to a liquid crystal compound, and more particularly to a nematic liquid crystal composition comprising a nematic liquid crystal compound capable of further improving the phase transition temperature and response speed.

In recent years, with the development of information processing technology and the development of technology of an information processing apparatus that performs information processing, it has become possible to process massive data in a short time. In addition, development of a display device is being performed in various application fields in order to visually express processed data so that a user can recognize it.

In particular, due to the rapid advancement of semiconductor technology, the electronic display device suitable for the new environment, that is, the thin and light, the low driving voltage and the low power consumption of the electronic device, according to the solidification, low voltage and low power of various electronic devices, and the small size and light weight of the electronic device The demand for feature-rich flat panel display devices is growing rapidly.

Among them, the liquid crystal display device has not only low power consumption and low driving voltage, but also a lot of research has been conducted in the past and the image display close to the cathode ray tube (CRT) is rapidly increasing its demand and various electronics. Widely used in devices.

Currently, the liquid crystal display device is expanding to a variety of small and medium display devices as well as notebooks, monitors and home TVs. In particular, 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.

As research on home TVs is being actively conducted, TN (Twist Nematic), IPS (CE), and VA modes have been mentioned as driving methods of home TVs.

However, IPS (CE) and VA mode has the advantage of having a wide viewing angle, but not only difficult to implement a moving image due to the slow response speed, it is difficult to secure the yield in the process, there is a problem that the manufacturing cost is rather high.

On the other hand, TN mode is competitive in securing process yield and manufacturing cost, but has a problem in that the viewing angle is narrow and the response speed is slow. That is, the liquid crystal capable of satisfying the characteristics of the liquid crystal display should have a low viscosity characteristic in order to improve the response speed, and increase the dielectric anisotropy (Δε) in order to lower the driving voltage. It should also have a nematic phase over a wide temperature range and have a birefringence (Δn) value of at least about 0.20 (about 25 ° C.).

However, in general, the response speed of nematic liquid crystals for TN, IPS, and VA modes is about 20 to 30ms, and the response speed of the liquid crystals needs to be shortened to realize smooth video.

The compensation problem for the viewing angle is gradually improved by the development of a compensation film, etc., but the response speed is a problem of the liquid crystal itself is an urgent time to develop the liquid crystal.

In addition, in order to realize a high brightness display using a liquid crystal display device to have the same performance as a conventional CRT, the amount of light of the backlight must be increased. For this reason, high heat is generated by the tube current of the backlight or the like.

In general, a liquid crystal display is manufactured by injecting a liquid crystal between two substrates on which electrodes are formed, and by applying a voltage to the two substrates on which electrodes are formed, liquid crystal present between the substrates selectively transmits or blocks an external light source. A device that displays data visually. In this case, the backlight is very close to the liquid crystal, and the light is directly transmitted. Therefore, heat generated by the tube current of the backlight is transferred to the liquid crystal of the liquid crystal display.

Therefore, a liquid crystal having a high phase transition temperature is needed. However, since the phase transition temperature of nematic liquid crystals for TN, IPS, and VA modes that are currently commercialized is low, about 70 to 80 ° C., high brightness displays are difficult to realize.

An object of the present invention for solving the above problems is to provide a nematic liquid crystal composition comprising a nematic liquid crystal compound capable of forming a high-speed high temperature liquid crystal by increasing the refractive anisotropy and the phase transition temperature of the liquid crystal.

The present invention for achieving the above object,

It is providing the nematic liquid crystal composition containing the nematic liquid crystal compound represented by following formula (1), and a host mixture.

In Formula (1), R is one selected from C _n H _{2n + 1} O, C _n H _{2n + 1} , and C _n H _2n-1 , wherein n is 1 to 10. L _a is , , , It is one selected from, wherein a is 0 or 1. M _b is , , , Is one selected from b, where b is 0 or 1. N _c is one selected from —CF ₂ O—, —CH ₂ CH ₂ —, —C═C—, —C≡C—, where c is 0 or 1. X is one selected from H, F, Cl, Br, NCS and CN, and Y _d is one selected from H, F, Cl, Br, NCS and CN, where d is 0 or 1. Z is one selected from NCS, SCN or F.

As such, when the liquid crystal is manufactured by using the liquid crystal composition containing the nematic liquid crystal compound, the phase transition temperature may be increased by about 30 ° C. as compared to the conventional liquid crystal, and the response speed is improved, thereby producing a liquid crystal having high speed and high temperature. can do.

Hereinafter, the present invention will be described in detail.

The liquid crystal composition including the nematic liquid crystal compound of the present invention may form a high-speed high-temperature liquid crystal by increasing the refractive index anisotropy and increasing the phase transition temperature of the liquid crystal for the purpose of high-speed response and high brightness technology. Here, a nematic liquid crystal compound is represented by following formula (1).

In Formula (1), R is one selected from C _n H _{2n + 1} O, C _n H _{2n + 1} , and C _n H _2n-1 , wherein n is 1 to 10. L _a is , , , It is one selected from, wherein a is 0 or 1. M _b is , , , Is one selected from b, where b is 0 or 1. N _c is one selected from —CF ₂ O—, —CH ₂ CH ₂ —, —C═C—, —C≡C—, where c is 0 or 1. X is one selected from H, F, Cl, Br, NCS and CN, and Y _d is one selected from H, F, Cl, Br, NCS and CN, where d is 0 or 1. Z is one selected from NCS, SCN or F.

A more preferable nematic liquid crystal compound of the present invention is, for example, a 3CC-CF ₂ O-PFS compound, in which R is propyl and L _a is , M _b is , N _c is -CF ₂ O-, X is fluorine (F), Y _d is hydrogen (H), and Z is NCS.

Further, as a 5CC-CF ₂ O-PFS compound, in the formula (1), R is pentyl, L _a is , M _b is , N _c is -CF ₂ O-, X is fluorine (F), Y is hydrogen (H), and Z is NCS.

The liquid crystal composition containing the nematic liquid crystal compound described above is composed of a nematic liquid crystal compound and a host mixture. At this time, the host mixture is composed of a G1 + G2 + G3 + G4 mixed material, the response rate of the liquid crystal was measured in 16.2 ms at the cell gap 4.6 ㎛, birefringence is 0.075, dielectric anisotropy 5.6, the phase transition temperature is 80 ℃. .

Wherein Formula (2) is 3CCO1, Formula (3) is 3CC3 ", Formula (4) is 5CC2", Formula (5) is specified as 5CC3, and G1 mixture is 3CC01 (6.6%) + 3CC3 ". (5.4%) + 5CC2 "(20.8%) + 5CC3 (4.1%).

Wherein Formula (6) is 2 "CCP ^FF , Formula (7) is 3CCP ^OCF3 , Formula (8) is 3CCP ^FFF , and G2 is 2" CCP ^FF (11.07%) + 3CCP ^OCF3 (2.5 %) + 3CCP ^FFF (2.5%).

Here, Formula (9) is 2CCesP ^x , Formula (10) is 3CPFesP ^x , Formula (11) is specified as 3CCesP ^x, G3 is 2CCesP ^x (3.4%) + 3CPFesP ^x (9.0%) + 3CCesP ^x (9.4%).

Formula (12) is 2CCP ^OCF3 , Formula (13) is 2CCP ^FFF , Formula (14) is 2CCP ^{F, OCF3} , Formula (15) is 2CPFP ^FFF , G4 is 2CCP ^ocf3 (8.66%) + 2CCP ^FFF (8.0%) + 2CCP ^{F, OCF3} (3.6%) + 2CPFP ^FFF (4.97%).

That is, the host mixture included in the composition of the present invention comprises about 6.6 wt% 3CCO1, about 5.4 wt% 3CC3 ", about 20.8 wt% 5CC2", about 4.1 wt% 5CC3 based on the total mixture, 11.07 wt% 2 "CCP ^FF , about 2.5 wt% 3CCP ^OCF3 , about 2.5 wt% 3CCP ^FFF , about 3.4 wt% 2CCesP ^x , about 9 wt% 3CPFesP ^x , about 9.4 wt% 3CCesP ^x , and about 8.66 wt% 2CCP ^OCF3 , about 8 wt% 2CCP ^FFF , about 3.6 wt% 2CCP ^{F, OCF3} , about 4.97 wt% 2CPFP ^FFF .

The compounds included in the nematic liquid crystal composition of the present invention are 3CC-CF ₂ O-PFS and 5CC-CF ₂ O-PFS, which are liquid crystal compounds of Formula (1), and the measurement of the birefringence and the dielectric constant is performed by a host (Host ) _mixture) 3CC-CF ₂ O-PFS or 5CC-CF ₂ O-PFS a 17% mixture by mixing a liquid crystal of the birefringence by weight of birefringence of then measuring the dielectric constant of a single crystal compound of the extrapolation (Δn in), The dielectric constant was measured.

The physical properties of 3CC-CF ₂ O-PFS, the nematic liquid crystal compound of the present invention, is about 109 ° C, which is a temperature at which phase transition from a crystal phase to a liquid crystal phase or an isotropic liquid phase, and T _NI is a temperature at which phase transition from a liquid crystal phase to an isotropic liquid phase is weak. It was 206 degreeC. In addition, birefringence (Δn) was about 0.178 and dielectric anisotropy (Δε) was about 12.4.

In addition, the physical properties of the 5CC-CF ₂ O-PFS is the temperature of T _NI to phase transition to an isotropic liquid phase on the liquid crystal approximately 204 ℃, showed the birefringence (Δn) of about 0.172, yiyeotda dielectric anisotropy (△ ε) of about 9.2 .

The liquid crystal composition comprising the nematic liquid crystal compound of the present invention having such a characteristic has a high birefringence (Δn) and a dielectric anisotropy (Δε), and particularly, has a high phase transition temperature and a fast response speed.

Accordingly, the liquid crystal composition of the present invention is a device of various LCD families requiring liquid crystal, such as twisted nematic (TN) device device, super twisted nematic (STN) device device, thin film transistor (TFT) -twist nematic It is used in the manufacture of (TN) device devices, IPS (in plane switching) device devices, and vertically align (VA) device devices to obtain LCDs having properties such as high brightness and high-speed response technology.

Hereinafter, an embodiment of the present invention will be described in detail. Herein, although the present invention has been described with reference to preferred embodiments, the present invention is not limited thereto.

EXAMPLE

Example 1

The nematic liquid crystal composition was prepared by mixing the nematic liquid crystal compound designated 3CC-CF ₂ O-PFS in the host mixture. When the 3CC-CF ₂ O-PFS material is 5% by weight in the liquid crystal composition including the host mixture and the 3CC-CF ₂ O-PFS material, the T _NI of the liquid crystal mixture is about 86.3 ° C and the birefringence (Δn ) Was about 0.0802, and the dielectric anisotropy (Δε) was about 5.9 (about 20 ° C).

Example 2

The nematic liquid crystal composition was prepared by mixing the nematic liquid crystal compound designated 3CC-CF ₂ O-PFS in the host mixture. In the nematic liquid crystal composition comprising the host mixture and the 3CC-CF ₂ O-PFS material, when the 3CC-CF ₂ O-PFS material is 10% by weight, the T _NI of the nematic liquid crystal composition is about 92.6 ° C., The birefringence (Δn) was about 0.0853 and the dielectric anisotropy (Δε) was about 6.3 (about 20 ° C).

Example 3

The nematic liquid crystal composition was prepared by mixing the nematic liquid crystal compound designated 3CC-CF ₂ O-PFS in the host mixture. When the 3CC-CF ₂ O-PFS material is 15% by weight in the nematic liquid crystal composition including the host mixture and the 3CC-CF ₂ O-PFS material, the T _NI of the nematic liquid crystal composition is about 98.9 ° C., The birefringence (Δn) was about 0.0905 and the dielectric anisotropy (Δε) was about 6.6 (about 20 ° C).

Example 4

The nematic liquid crystal composition was prepared by mixing the nematic liquid crystal compound designated 3CC-CF ₂ O-PFS in the host mixture. In the nematic liquid crystal composition comprising the host mixture and the 3CC-CF ₂ O-PFS material, when the 3CC-CF ₂ O-PFS material is 17.4% by weight, the T _NI of the liquid crystal composition is about 101.9 ° C. and has a birefringence rate. (Δn) was about 0.094, and the dielectric anisotropy (Δε) was about 6.7 (about, 20 ° C).

Example 5

The nematic liquid crystal composition was prepared by mixing the nematic liquid crystal compound designated 3CC-CF ₂ O-PFS in the host mixture. In the nematic liquid crystal composition comprising the host mixture and the 3CC-CF ₂ O-PFS material, when the 3CC-CF ₂ O-PFS material is 20% by weight, the T _NI of the liquid crystal composition is about 105.2 ° C., and the birefringence is (Δn) was about 0.0956, and the dielectric anisotropy (Δε) was about 7.0 (about, 20 ° C).

Example 6

The nematic liquid crystal composition was prepared by mixing the nematic liquid crystal compound designated 3CC-CF ₂ O-PFS in the host mixture. In the nematic liquid crystal composition comprising the host mixture and the 3CC-CF ₂ O-PFS material, when the 3CC-CF ₂ O-PFS material is 25% by weight, the T _NI of the nematic liquid crystal composition is about 111.3 ° C., The birefringence (Δn) was about 0.1008 and the dielectric anisotropy (Δε) was about 7.3 (about, 20 ° C).

Example 7

The nematic liquid crystal composition was prepared by mixing the nematic liquid crystal compound designated 3CC-CF ₂ O-PFS in the host mixture. In the nematic liquid crystal composition comprising the host mixture and the 3CC-CF ₂ O-PFS material, when the 3CC-CF ₂ O-PFS material is 40% by weight, the T _NI of the nematic liquid crystal composition is about 130 ° C., The birefringence (Δn) was about 0.1162, and the dielectric anisotropy (Δε) was about 8.3 (about, 20 ° C).

Example 8

The nematic liquid crystal composition was prepared by mixing the nematic liquid crystal compound designated 5CC-CF ₂ O-PFS in the host mixture. In the liquid crystal composition comprising the host mixture and the 5CC-CF ₂ O-PFS material, when the 5CC-CF ₂ O-PFS material is 10% by weight, the T _NI of the liquid crystal composition is about 92.4 ° C and the birefringence (Δn ) Was about 0.0847, and dielectric anisotropy (Δε) was about 6.0 (20 ° C).

Example 9

The nematic liquid crystal composition was prepared by mixing the nematic liquid crystal compound designated 5CC-CF ₂ O-PFS in the host mixture. When the 5CC-CF ₂ O-PFS material is 15% by weight in the nematic liquid crystal composition including the host mixture and the 5CC-CF ₂ O-PFS material, the T _NI of the nematic liquid crystal composition is about 98.6 ° C., The birefringence (Δn) was about 0.0896 and the dielectric anisotropy (Δε) was about 6.1 (20 ° C).

Example 10

The nematic liquid crystal composition was prepared by mixing the nematic liquid crystal compound designated 5CC-CF ₂ O-PFS in the host mixture. In the nematic liquid crystal composition including the host mixture and the 5CC-CF ₂ O-PFS material, when the 5CC-CF ₂ O-PFS material is 17.5 wt%, the T _NI of the nematic liquid crystal composition is about 101.7 ° C., The birefringence (Δn) was about 0.093 and the dielectric anisotropy (Δε) was about 7.2 (20 ° C).

Example 11

The nematic liquid crystal composition was prepared by mixing the nematic liquid crystal compound designated 5CC-CF ₂ O-PFS in the host mixture. When the 5CC-CF ₂ O-PFS material is 20% by weight in the nematic liquid crystal composition including the host mixture and the 5CC-CF ₂ O-PFS material, the T _NI of the nematic liquid crystal composition is about 104.8 ° C., The birefringence (Δn) was about 0.0944 and the dielectric anisotropy (Δε) was about 6.3 (20 ° C).

Example 12

The nematic liquid crystal composition was prepared by mixing the nematic liquid crystal compound designated 5CC-CF ₂ O-PFS in the host mixture. When the 5CC-CF ₂ O-PFS material is 40% by weight in the nematic liquid crystal composition including the host mixture and the 5CC-CF ₂ O-PFS material, the T _NI of the nematic liquid crystal composition is about 129.6 ° C., The birefringence (Δn) was about 0.1138 and the dielectric anisotropy (Δε) was about 7.0 (20 ° C).

As such, the physical properties of the liquid crystal composition may be adjusted according to the amount of the nematic liquid crystal compound applied to Examples 1 to 12, and the amount of the mixture may be selectively adjusted according to the liquid crystal device application (TN, IPS, OCB).

Comparative Example

For a conventional nematic liquid crystal composition consisting of the liquid crystal compound is a mixture of NCS and the host, and the phase transition temperature of about 70 ℃ T _NI, birefringence (Δn) is from about 0.15, it has a response time of 14.6ms properties, The phase transition temperature made of the liquid crystal composition is low, and the refractive index is high.

In addition, the nematic liquid crystal composition including NCS, which is a conventional liquid crystal compound, has a T _NI of about 95 ° C., a birefringence (Δn) of about 0.089, and a response speed of 21.3 ms, and is used as a high temperature liquid crystal. It has a hard problem.

On the other hand, the response speed of the liquid crystal of the nematic liquid crystal composition having physical properties of Example 4 of the present invention is 11.8ms, the threshold voltage is 1.6V, the voltage retention is 99.0. This shows that the response speed is reduced to 73% compared to the host mixture, the phase transition temperature is increased to 127%, and the voltage holding ratio is 99.0, which can be used as a high speed liquid crystal for video.

In addition, the response speed of the liquid crystal of the nematic liquid crystal composition having the physical properties of Example 10 is 12 ms, the threshold voltage is 1.5V, and the voltage retention is 99.0. This shows that the response speed is reduced to 75% compared to the host mixture, the phase transition temperature is increased to 127%, and the voltage retention rate is 99.0, which can be used as a high speed liquid crystal for video.

As described above, according to the present invention, the nematic liquid crystal compound applied to the nematic liquid crystal composition can simultaneously satisfy the high-speed response and high temperature characteristics of the moving picture corresponding object that can be commercialized in the TN device.

Accordingly, the liquid crystal composition comprising the nematic liquid crystal compound of the present invention is a device of various LCD families requiring liquid crystal, such as twisted nematic (TN) device device, super twisted nematic (STN) device device, thin film transistor It is used to manufacture (TFT) -Twisted Nematic (TN) device devices, IPS (in plane switching) devices, and vertically align (VA) devices to obtain LCDs with properties such as high brightness and high-speed response technology. .

Claims (9)

The nematic liquid crystal composition containing the nematic liquid crystal compound represented by following formula (1), and a host mixture. (In Formula (1), R is one selected from the group consisting of C _n H _{2n + 1} O, C _n H _{2n + 1} and C _n H _2n-1 , wherein n is 1 to 10 and L _a is , , And Any one selected from the group consisting of a is 0 or 1 and M _b is , , And Any one selected from the group consisting of, b is 0 or 1, N _c is -CF ₂ O-, -CH ₂ CH _2- , -C = C- and -C ≡C- selected from the group consisting of Wherein c is 0 or 1, X is one selected from the group consisting of H, F, Cl, Br, NCS and CN, and Y _d is selected from the group consisting of H, F, Cl, Br, NCS and CN Where d is 0 or 1 and Z is one selected from the group consisting of NCS, SCN and F.) The method according to claim 1, wherein in formula (1), R is propyl, and L _a is And M _b is And N _c is -CF ₂ O-, X is fluorine (F), Y is hydrogen (H), and Z is NCS. The method according to claim 1, wherein in formula (1), R is pentyl, L _a is And M _b is And N _c is -CF ₂ O-, X is fluorine (F), Y is hydrogen (H), and Z is NCS. The nematic liquid crystal composition according to claim 1, wherein the host mixture comprises a compound represented by the following formulas (2) to (15). Twisted nematic (TN) device device comprising the nematic liquid crystal composition of claim 1. A super twisted nematic (STN) device device, comprising the nematic liquid crystal composition of claim 1. A thin film transistor-twist nematic (TFT-TN) device device, comprising the nematic liquid crystal composition of claim 1. IPS (In Plane Switching) device device comprising the nematic liquid crystal composition of claim 1. VA (Vertically Align) device device manufactured by including the liquid crystal composition of claim 1.