KR101334755B1 - novel liquid crystal compound, liquid crystal composition and liquid crystal device comprising the same - Google Patents

Abstract

The present invention relates to a liquid crystal compound (S _C liquid crystal compound) having a Schematic C liquid crystal at a wide temperature and a liquid crystal composition and a liquid crystal display device comprising the same. The liquid crystal display device according to the present invention has a fast response speed and a wide viewing angle. It has a low power consumption and is suitable for manufacturing large screen displays.

Description

Novel liquid crystal compound, liquid crystal composition and liquid crystal device comprising the same

The present invention relates to a novel liquid crystal compound, a liquid crystal composition comprising the same, and a liquid crystal display device.

Recently used display apparatuses include liquid crystal displays, plasma displays, light emitting diode displays, electroluminescent displays, and ECD displays.

Among them, a liquid crystal display device is an apparatus for realizing an electric signal on a scope by supplying an electrical signal to a switching element using a liquid crystal compound. The light transmittance is controlled by changing the state of the liquid crystal compound in the switching element corresponding to the electrical signal. Do it.

The liquid crystal included in the liquid crystal display may be classified into a nematic phase, a smectic phase, a cholesteric phase, and the like. Dual nematic liquid crystal has each component molecules arranged in one direction and is arranged randomly at random. Smatic liquid crystals have the same directionality as the nematic liquid crystal and have a layer structure. Randomly arranged. In addition, the cholesteric liquid crystal has a rotational characteristic or a self-rotating structure in which the smectic liquid crystal has a rotational characteristic.

On the other hand, recently, liquid crystal displays require fast response characteristics and wide viewing angle characteristics for moving images.

Accordingly, the smectic liquid crystal has a characteristic called bistable stability, thereby enabling high quality image quality without deterioration of contrast and flaker even when the number of scanning players of the liquid crystal display device increases.

Among ferroelectric liquid crystals, ferroelectric liquid crystals are several hundred times faster than nematic liquid crystals, which prevents blurring of images. For example, Korean Patent Publication No. 1990-016304 provides a liquid crystal compound having a wide operating temperature range, low power consumption, and an improved response speed.

Materials required for the ferroelectric liquid crystal is a smectic C liquid crystal compound having a group chiral (S _C liquid crystal compound) of a chiral smectic liquid crystal compound (S _C ^* liquid crystal compound), smectic C liquid crystal compound (S _C) a chiral group in It can mix and use the liquid crystal compound which it has.

       Therefore, the research on the smetic liquid crystal compound having excellent characteristics is continuing.

Korean Patent Publication No. 1990-016304 (1990.11.13)

The present invention provides a liquid crystal compound and a liquid crystal composition having a smear C phase (S _C ) at a wide temperature.

In addition, the present invention provides a liquid crystal display device having improved response speed and having a wide viewing angle.

The present invention provides a liquid crystal compound represented by the following Chemical Formula 1 having liquid crystallinity even at a wide temperature.

[Formula 1]

NC-BXAO (CH ₂ ) _n- (CF ₂ ) _m F

[In Formula 1,

A and B are (C6-C20) arylene, (C3-C20) cycloalkylene or (C3-C20) heteroallylene,

X is a single bond, -COO-, -OOC-, -CF ₂ O- or -OF ₂ C-.

n and m are integers from 1 to 10.]

Specifically in Formula 1,

A or B is (C6-C20) arylene,

X is a single bond, -COO- or -CF ₂ O-,

 n and m are integers of 2-8.

In addition, in Formula 1, A and B may be phenyl, biphenyl, terphenyl or naphthalene.

More specifically, the liquid crystal compound according to the exemplary embodiment of the present invention may be selected from the following structures, but is not limited thereto.

In another aspect, the present invention provides a liquid crystal composition comprising the liquid crystal compound of Formula 1 and preferably may be included in 5 to 90% of the total weight of the liquid crystal material in the liquid crystal composition.

The present invention also provides a liquid crystal display including the liquid crystal composition.

A liquid crystal compound and a liquid crystal composition according to the invention smectic C (S _C) in a wide temperature A liquid crystal display device having liquid crystal properties and including a liquid crystal composition prepared according to the present invention has a fast response speed, a wide viewing angle, and high efficiency with low power consumption.

Figure 1 shows a graph obtained by differential scanning calorimetry (DSC) measurement of the liquid crystal compound prepared in Example 1,
2 shows the results of observing with an optical microscope when the liquid crystal compounds prepared in Example 1 were respectively heated to (a) 95 ° C. (b) 119 ° C. (c) 161 ° C. (d) 161.7 ° C.,
3 shows a graph obtained by differential scanning calorimetry ((DSC)) measurement of the liquid crystal compound prepared in Example 2. FIG.

The present invention provides a liquid crystal compound represented by the following formula (1).

[Formula 1]

NC-BXAO (CH ₂ ) _n- (CF ₂ ) _m F

[In Formula 1,

A and B are (C6-C20) arylene, (C3-C20) cycloalkylene or (C3-C20) heteroallylene,

X is a single bond, -COO-, -OOC-, -CF ₂ O- or -OF ₂ C-,

n and m are integers from 1 to 10.]

The liquid crystal compound according to the present invention has a smetic C liquid crystal at a wide temperature range and the liquid crystal composition including the liquid crystal compound according to the present invention also has a smetic C liquid crystal at a wide temperature range and has a chiral group. When mixed with an chiral smetic C liquid crystal compound (S _C ^* liquid crystal compound), it may have a ferroelectric liquid crystal, and thus a liquid crystal display including the same may improve response speed by several tens to several hundred times than conventional liquid crystals. Can have

Specifically, in Formula 1, A and B are (C6-C20) arylene, X is a single bond, -COO- or -CF ₂ O-, n and m may be an integer of 2 to 8.

In more detail, in Formula 1, which is a liquid crystal compound of the present invention, A and B may be phenyl, biphenyl, terphenyl, or naphthalene.

The liquid crystal compound according to the exemplary embodiment of the present invention may be selected from the following structures, but is not limited thereto.

The liquid crystal compound according to the present invention contains fluorine and has a cyano group at the terminal to improve linearity, thereby having excellent liquid crystallinity, and exhibiting a Smetic C liquid crystal phenomenon in a wide temperature range. It becomes a (ferroelectric) liquid crystal material. In this case, the response speed and power consumption are low, and the viewing angle characteristics are good.

In another aspect, the present invention provides a liquid crystal composition comprising the liquid crystal compound of Formula 1.

The content of the liquid crystal compound in the liquid crystal composition comprising the liquid crystal compound according to the present invention can be appropriately adjusted in consideration of the properties of the liquid crystal compound used, the viscosity of the composition, the operating temperature and its use.

The liquid crystal composition may be included at 5 to 90% by weight, more preferably 20 to 80% by weight relative to the total weight of the liquid crystal material in the liquid crystal composition.

The liquid crystal composition may be one or a mixture of two or more liquid crystal compounds according to the present invention. Essential conditions for use as a liquid crystal display comprising such a liquid crystal composition

1. The temperature range of liquid crystal should be wide (-20 ~ 80 ℃).

2. Positive dielectric anisotropy should be large to lower driving voltage.

3. Low viscosity to increase response speed.

4. Have appropriate birefringence for viewing angle and contrast control.

.

Several compounds are mixed to obtain these conditions. The basic concept of these blending is as follows.

1. Select a mother liquid crystal having a wide range of liquid crystal phases and a low melting point, and add a liquid crystal compound having a chiral group to form a chiral smear C liquid crystal compound (S _C ^* ).

2. Add a liquid crystal with an appropriate size of electrostatic asymmetry (Δε) to the base liquid crystal so as to match the magnitude of the threshold voltage.

3. Since the upper limit of the liquid crystal temperature should be increased, the liquid crystal of non-liquid crystal transition temperature is added in the high liquid crystal.

By repeating these steps, the mixed liquid crystal optimized for the display device characteristics is blended.

The liquid crystal compound which can be used in combination with the liquid crystal compound of the present invention may be a known nematic liquid crystal compound, a smectic liquid crystal compound and a cholesteric liquid crystal compound, but a chiral liquid crystal compound is more preferable.

The present invention also provides a liquid crystal display containing a liquid crystal composition comprising the liquid crystal compound according to the present invention.

The present invention can be prepared by additionally using additives which can be used by mixing the liquid crystal composition and the liquid crystal display with a known liquid crystal compound such as a conductivity giving agent or a life improving agent.

Hereinafter, an embodiment of the present invention will be described in detail, but it is not intended to limit the present invention.

Example 1 Synthesis of 4- (2-perfluorohexyl) -ethoxy-4'-cyanobiphenyl (F6H2OCB).

1 H , 1 H , 2 H , 2 H -perfluoro-1-octanol (3.64g, 10mmol), 4-cyano-4'-hydroxy-biphenyl (1.95g, 10mmol) and triphenylphosphine (2.62g, 10mmol ) Was dissolved in dry THF (30 mL). To this, dry THF containing diisopropylazodicarboxylate (2cc, 10mmol) dissolved in nitrogen (N ₂ ) gas was added slowly and slowly for 30 minutes at 0 ° C.Then, the solution was added with nitrogen gas, 0 Stirred for 24 hours under temperature conditions. Distilled water (1 mL) was added to terminate the reaction, and the solvent was removed under reduced pressure.

The solvent removed was separated through a column using silica gel (eluent, 5: 1 = hexane: ethylacetate) and recrystallized from ethanol (95%) to yield 5% (0.27 g) of white (white) crystals. Phosphorus 4- (2-perfluorohexyl) -ethoxy-4'-cyanobiphenyl was obtained.

¹ H NMR (CDCl ₃ ) δ (ppm)) 7.7 (quartet, 4H), 7.6 (doublet, 2H), 7.0 (doublet, 2H), 4.3 (triplet, 2H), 3.7 (multiplet, 2H)

As shown in FIG. 1, the transition to the liquid crystal phase was confirmed under a temperature range of about 89.25 ° C. to 161.73 ° C. under differential scanning calorimetry (DSC) measurement (TA DSC Q28, using a condition of 10 ° C./min).

As shown in FIG. 2, an optical microscope (Olympus BX41 polarizing microscope equipped with a Mettler FP82HT hot stage) was observed, and the transition of the liquid crystal phase occurred, and the pattern was Smectic C (S _C ). Able to know.

More specifically, FIG. 2 shows the results of observing with an optical microscope when the liquid crystal compounds prepared in Example 1 were heated to (a) 95 ° C. (b) 119 ° C. (c) 161 ° C. (d) 161.7 ° C., respectively. a) and b) are broken pan shape textures and show characteristics of Smec C (S _C ) liquid crystal. c) Smetic C (S _C ) → Smetic A (S _A ) And d) represents a process of transferring from Smec A (S _A ) to isotropic liquid (I).

Example 2 Synthesis of 4- (2-perfluorooctyl) -ethoxyphenyl-4'-cyanobenzoate (F8H2OPCB)

[Step 1] Preparation of 1- (2-perfluorooctyl) -ethoxy-4-methoxybenzene

4-methoxyphenol (3.1g, 0.025mol), 1 H , 1 H , 2 H , 2 H -perfluoro-1-decanol (11.6g, 0.025mol) and triphenylphosphine (6.55g, 0.025mol) ) was dissolved in dry THF (35 mL). Dry THF dissolved in diisopropylazodicarboxylate (5cc, 0.025mol) was slowly added dropwise slowly for 30 minutes at 0 ° C. under blowing nitrogen (N ₂ ) gas, and then the solution was dropped into nitrogen gas, Mix overnight at 0 ° C. temperature conditions. The reaction was terminated with distilled water (1 mL) and the solvent was removed under reduced pressure.

      [Step 2] 1- (2-perfluorooctyl) -ethoxy-4-hydroxybenzene

After dissolving 1- (2-perfluorooctyl) -ethoxy-4-methoxybenzene (10.0g, 0.022mol) in dichloromethane (50ml), boron tribromide (5.1cc, 0.053mol) A) The dissolved dichloromethane (50 ml) was slowly dropped little by little. After dropping, mix overnight at room temperature. Distilled water was added to terminate the reaction. Extract with 10% NaHCO ₃ solution and recrystallize with toluene.

[Step 3] 4- (2-perfluorooctyl) -ethoxyphenyl-4'-cyanobenzoate

1- (2-perfluorooctyl) -ethoxy-4-hydroxybenzene (0.56g, 0.001mol), 4-cyanobenzoyl chloride (0.26g, 0.001mol) and pyridine (0.16cc, 0.002mol) are derived from chloroform ( 25 ml), and reacted while mixing for about 3 hours, followed by adding a small amount of distilled water to terminate the reaction. Solvent was removed under reduced pressure. The solvent removed was separated through a column using silica gel (eluent, 2.5: 1 = hexane: ethylacetate) and recrystallized from ethanol (95%) to yield 58% (0.4 g) of white (white) crystals. Phosphorus 4- (2-perfluorooctyl) -ethoxyphenyl-4'-cyanobenzoate was obtained.

¹ H NMR (CDCl ₃ ) δ (ppm)) 8.3 (doublet, 2H), 7.8 (doublet, 2H), 7.2 (doublet, 2H), 7.0 (doublet, 2H), 4.3 (triplet, 2H), 2.7 (multiplet , 2H)

As shown in FIG. 3, the transition to the liquid crystal phase was confirmed by differential scanning calorimetry (DSC) measurement under a temperature range of about 129.03 ° C to 189.49 ° C.

Claims (7)

Liquid crystal compound represented by the following formula (1).
[Formula 1]
NC-BXAO (CH ₂ ) _n- (CF ₂ ) _m F
[In the above formula (1)
A and B are (C6-C20) arylene, (C3-C20) cycloalkylene or (C3-C20) heteroallylene,
X is -COO-, -OOC-, -CF ₂ O- or -OF ₂ C-,
n and m are integers from 1 to 10.] The method of claim 1,
A and B are (C6-C20) arylene,
X is -COO- or -CF ₂ O-,
n and m are liquid crystal compounds whose integer is 2-8. The method of claim 2,
A and B are phenyl, biphenyl, terphenyl or naphthalene. The method of claim 3, wherein
A liquid crystal compound selected from the following structures.

A liquid crystal composition comprising the liquid crystal compound of claim 1. 6. The method of claim 5,
The liquid crystal compound is contained in 5 to 90% by weight relative to the total weight of the liquid crystal material in the liquid crystal composition. A liquid crystal display comprising the liquid crystal composition of claim 5.

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