KR20160140152A - Liquid crystal compound, liquid crystal composition and liquid crystal display comprising the same - Google Patents

Abstract

Provided is a liquid crystal compound which exhibits outstanding low temperature stability and enables the production of a liquid crystal composition showing a high dielectric constant and/or a high refractive index. In addition, the liquid crystal compound also ensures easy production of the liquid crystal composition which is optimized to various liquid crystal display devices due to high specific resistance, such as liquid crystal display devices which are in the mode of TN (twisted nematic), STN (super-twisted nematic), IPS (in-plane switching), FFS (fringe field switching), PLS (plane line switching), AH-IPS (advanced high-performance IPS), ADS (advanced-super dimensional switching), and PSA (polymer sustained alignment).

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal compound, a liquid crystal composition,

The present invention relates to a liquid crystal compound capable of providing a liquid crystal composition exhibiting both high-dielectric anisotropy and low-temperature stability, a liquid crystal composition containing the same, and a liquid crystal display.

The liquid crystal display (LCD) is used in various electronic devices such as a clock, an electronic calculator, a measuring instrument, an automobile panel, a word processor, an electronic notebook, a printer, a computer, and a television. Typical examples of the liquid crystal display include TN (Twist nematic), STN (Super-twisted nematic), IPS (In-plane switching), FFS (Fringe field switching) and VA (Virtical alignment).

The single liquid crystal compound used in such a liquid crystal display device has a molecular weight of about 200 to 600 g / mol and a rod-like molecular structure. The molecular structure of a liquid crystal compound is generally classified into a core group that maintains linearity, a terminal group that has flexibility, and a linkage group that is used for specific purposes. The physical properties of the liquid crystal compound and the composition containing the liquid crystal compound can be controlled by controlling the type of the substituent group introduced into the terminal group. Concretely, flexibility is ensured by introducing a chain group (alkyl, alkoxy or alkenyl group or the like) which is prone to bend at one or both ends, or a polar group (F, CN, OCF ₃ ) Can be introduced to control the physical properties such as the dielectric constant.

The liquid crystal compound used in the above-described liquid crystal display device is required to be capable of low-voltage driving and high-speed response and capable of operating over a wide temperature range. Specifically, in order to drive stably in a wide temperature range, the liquid crystal material is required to exhibit stable physical properties at about -20 占 폚 or lower (low temperature stability) and have a high transparency point. For the low-voltage driving and the high-speed response, the liquid crystal material is required to have a large absolute value of the dielectric anisotropy, a small rotational viscosity, and a suitable modulus of elasticity (K ₁₁ , K ₂₂ , K ₃₃ average value).

The required physical properties of such a liquid crystal material can not be satisfied by using one or two kinds of liquid crystal compounds, and usually 7 to 20 kinds of liquid crystal compounds are mixed and satisfied.

However, such a composition in which a variety of single liquid crystal compounds are mixed has a problem in that when the composition is in a low temperature environment, the compound having a higher melting point among the single liquid crystal compounds contained in the composition is recrystallized and lost its original function.

Accordingly, in order to avoid such recrystallization, a method of introducing a substituent having a long chain or appropriately compounding a substance having a long chain has been introduced. However, in the case of a single liquid crystal compound having a high refractive index anisotropy or a high dielectric anisotropy, the elastic modulus and the rotational viscosity become poor due to the long chain, and thus the response time of the liquid crystal display device is increased. Specifically, the liquid crystal compound represented by the following formula (Q-1) has a high melting point of 86 DEG C, but the liquid crystal compound of the formula (Q-2) in which a longer alkyl chain is introduced into the liquid crystal compound of Q- It has a melting point.

[Chemical formula (Q-1)

[Chemical formula (Q-2)

However, the liquid crystal compound of the formula (Q-1) has a rotational viscosity of 387 mPa · s, whereas the liquid crystal compound of the formula (Q-2) has a rotational viscosity of 411 mPa · s. Accordingly, when the liquid crystal compound of the formula (Q-2) is used, the response speed of the LCD panel is increased.

Therefore, there is an urgent need to develop a technique for improving the low-temperature stability of a liquid crystal composition requiring high-dielectric constant anisotropy.

The present invention provides a liquid crystal compound capable of providing liquid crystal compositions simultaneously exhibiting high anisotropy and low temperature stability.

The present invention also provides a liquid crystal composition and a liquid crystal display device comprising the liquid crystal compound.

Hereinafter, a liquid crystal compound according to a specific embodiment of the present invention, a liquid crystal composition containing the same, a liquid crystal display device, and the like will be described.

According to one embodiment of the present invention, there is provided a liquid crystal compound represented by the following formula (1).

[Chemical Formula 1]

In Formula 1,

Wherein R ¹ is a radical of any one of hydrogen and alkyl of 1 to 15 carbon atoms, or wherein one to three of the radicals are substituted by halogen or one or more -CH ₂ - -O-CO-, -O-CO-O-, -O-CO-O-, -OCO-, -CF ₂ O-, -CH = CH-, -O-,

X ¹ is a radical of any one of F, Cl, CN, NCS and fluoroalkyl of 1 to 5 carbon atoms containing 1 to 3 F, or wherein at least one -CH ₂ - of the radicals is replaced by an oxygen atom Radical,

Y ¹ is H or F,

The A ¹ and A ² rings are each independently any one of rings having the following structure,

Z ¹ is a single _{bond, -CH 2 CH 2 -, -CH} = CH-, -CH 2 O-, -OCH 2 -, -C≡C-, -CH 2 CF 2 -, -CHFCHF-, -CF 2 _{CH 2 -, -CH 2 CHF-,} -CHFCH 2 -, -C 2 F 4 -, -COO-, -OCO-, -CF 2 O- or -OCF ₂ -, and

n is 0 or 1;

The present inventors have found that when a phenyl group substituted with a methyl group is introduced into a liquid crystal compound as in the above formula (1), the cross-linking angle between the rings is increased to reduce the packing density and the melting point of the molecules . It has been found that the liquid crystal compound can exhibit excellent low temperature stability due to such an effect.

This effect can be expressed particularly when the methyl group is introduced at the 3-position of the terminal phenyl group (the rightmost-marked phenyl group) as shown in the formula (1). If a substituent having 2 or more carbon atoms is introduced at the 3-position of the terminal phenyl group in the above formula (1), the ratio of the molecular long axis to the short axis decreases, resulting in a sharp decrease in the transparent point. On the other hand, when F is introduced at the 3-position of the terminal phenyl group in the above formula (1), the low-temperature stability improving effect can be exhibited, but the positive dielectric constant anisotropy is reduced.

Unless defined otherwise herein, the following terms may be defined as follows.

The halogen may be fluorine (F), chlorine (Cl), bromine (Br) or iodine (I).

Alkyl radicals of 1 to 15 carbon atoms may be straight, branched or cyclic alkyl radicals. Specifically, the alkyl radical having 1 to 15 carbon atoms is a straight chain alkyl radical having 1 to 10 carbon atoms; A straight chain alkyl radical having 1 to 5 carbon atoms; Branched or cyclic alkyl radicals having from 3 to 10 carbon atoms; Or a branched or cyclic alkyl radical having from 3 to 5 carbon atoms. More specifically, the alkyl radical having from 1 to 15 carbon atoms may be methyl, ethyl, n-propyl, iso-propyl, n-butyl, iso-butyl, tert-butyl, n-pentyl, isopentyl or cyclohexyl.

In the alkyl radical having 1 to 15 carbon atoms, at least one -CH ₂ - of the radical is -C≡C-, -CF ₂ O-, -CH═CH-, -O-, -COO-, -OCO- or -OCO-O-. ≪ / RTI > In one example, a methyl radical can be replaced by a vinyl radical (-CH = CH-H) in which -CH ₂ - of the methyl radical (-CH ₂ -H) is replaced by -CH = CH-. Provided that at least one -CH ₂ - of the radicals may be substituted with any of the substituents described above so that the oxygen atoms are not directly connected.

Also, alkyl radicals of 1 to 15 carbon atoms may be replaced by radicals in which one or more of the radicals of the radicals is replaced by a halogen. For example, a methyl radical can be replaced by a perfluoromethyl radical (-CF ₃ ) in which all H of the methyl radical (-CH ₃ ) is replaced by F.

A single bond means that there is no separate atom in the moiety represented by Z < ^{1 &} gt ;. For example, in formula (1), when Z ¹ is a single bond, n is 0, and the A ² ring is a cyclohexylene group, the cyclopentyl group may be directly linked to cyclohexylene.

In Formula 1, R ¹ may be an alkyl radical having 1 to 3 carbon atoms, or a radical in which at least one -CH ₂ - of the alkyl radicals having 1 to 15 carbon atoms is substituted with -CH = CH-. Ten thousand and one R ¹ is 1 to 15 carbon atoms one or more of alkyl radicals of -CH ₂ - if the radicals substituted with a -CH = CH-, rotational viscosity decreases, the number of carbon atoms of R ¹ is an even number in order to optimize the clearing point and increase in modulus of elasticity , It is advantageous to introduce a double bond at the terminal. When the number of carbon atoms in R ¹ is odd, it is advantageous to introduce a double bond to the odd-numbered carbon. For example, in order to optimize the modulus of elasticity and increase the transparency point, R ¹ is selected from the group consisting of -CH═CH ₂ , -CH ₂ -CH ₂ -CH═CH ₂ , -CH═CH-CH ₃ or -CH ₂ -CH ₂ -CH = CH ₂ -CH ₃ . Further, in the liquid crystal compound of Chemical Formula 1, since the terminal group of the central group is a cyclopentyl group, the rotational viscosity can be effectively lowered when R ¹ is hydrogen.

In Formula 1, X ¹ is a polar radical, and may be any of the substituents described above. In particular, for the provision of a low viscosity liquid crystal composition, X ¹ can be F, Cl, CF ₃ or OCF ₃ .

In the above formula (1), the 6-position of the terminal phenyl group, that is, Y ¹ may be hydrogen or fluorine, and a compound in which Y ¹ is fluorine may be used in order to secure a higher dielectric anisotropy.

In formula (I) Z ¹ is a structure of the dielectric anisotropy, the rotation viscosity, can be selected in consideration of the refractive index anisotropy, etc., typically a single bond to secure the various physical properties of the liquid crystal compound is required, or -CF ₂ O-, etc. is selected, .

The structure of the A ¹ and A ² rings in Formula 1 may be selected in consideration of refractive index anisotropy or dielectric anisotropy. If a liquid crystal material having a high refractive index anisotropy is to be provided, a liquid crystal compound in which A ¹ and A ² rings are 1,4-phenylene groups is suitable, and in order to provide a liquid crystal material having a high dielectric anisotropy, A ¹ and A ² rings are F or O The included liquid crystal compounds are suitable.

In one embodiment, the compound of Formula 1 may be any one of the following liquid crystal compounds.

[1-1]

[1-1]

[1-2]

[1-2]

[1-3]

[1-3]

[1-4]

[1-4]

[1-5]

[1-5]

[1-6]

[1-6]

[1-7]

[1-7]

[1-8]

[1-8]

[1-9]

[1-9]

[1-10]

[1-10]

[1-11]

[1-11]

[1-12]

[1-12]

[1-13]

[1-13]

[1-14]

[1-14]

[1-15]

[1-15]

[1-16]

[1-16]

[1-17]

[1-17]

[1-18]

[1-18]

[1-19]

[1-19]

[1-20]

[1-20]

[1-21]

[1-21]

[1-22]

[1-22]

[1-23]

[1-23]

[1-24]

[1-24]

Wherein R < ¹ > is the same as defined in formula (1).

The same symbols written in different formulas herein do not denote homologous substituents. For example, one another does not mean the same symbols 'R ^1' is a substituent of the same kind in different formulas 1-1 to 1-24, although the 'R ^1' hydrogen at 1-1, 'R ^1' 1-2 is methyl Lt; / RTI > In addition, in the formulas of the present specification, the round parenthesis "()" means that it can be substituted with the substituent described in the round parenthesis. More specifically, - (F) means that hydrogen or fluorine can be bonded to the site.

According to another embodiment of the present invention, there is provided a liquid crystal composition comprising the liquid crystal compound represented by the above formula (1). The liquid crystal composition includes a liquid crystal compound having the above-described formula (1) and exhibits excellent low-temperature stability while exhibiting high anisotropy.

The liquid crystal compound of Formula 1 may be included in an amount of 1 to 50 parts by weight based on 100 parts by weight of the total liquid crystal compound contained in the composition.

Meanwhile, in the liquid crystal composition, the liquid crystal compound of Formula 1 may be combined with various liquid crystal compounds known to suit the characteristics of the liquid crystal panel to which the composition is applied.

For example, the liquid crystal composition may include a low viscosity liquid crystal compound represented by the following formula (2) as a matrix first component.

(2)

In Formula 2,

R ²¹ and R ²² are each independently a radical of any one of hydrogen and alkyl of 1 to 15 carbon atoms, or wherein 1 to 3 of the radicals are substituted by halogen or one or more -CH ₂ - It is not connected _{-C≡C-, -CF 2 O-, -CH =} CH-, -O-, -CO-O-, -O-CO- or a radical replaced by a -O-CO-O-,

The A ³ and A ⁴ rings are each independently a 1,4-cyclohexylene group or a 1,4-phenylene group.

As the compound of the formula (2), a compound selected from the liquid crystal compounds having the following structures can be used so that the transparent point, the rotational viscosity, the refractive index anisotropy and the dielectric anisotropy can be advantageously controlled while maintaining a high specific resistance.

[2-1]

[2-1]

[2-2]

[2-2]

[2-3]

[2-3]

[2-4]

[2-4]

In the above formulas, R ²¹ and R ²² are the same as defined in formula (2).

Meanwhile, the liquid crystal composition may include a high temperature liquid crystal compound represented by the following formula (3) as a matrix second component.

(3)

In Formula 3,

R ³¹ and R ³² are each independently a radical of any one of hydrogen and alkyl of 1 to 15 carbon atoms, or wherein 1 to 3 of the radicals are substituted by halogen or one or more -CH ₂ - It is not connected _{-C≡C-, -CF 2 O-, -CH =} CH-, -O-, -CO-O-, -O-CO- or a radical replaced by a -O-CO-O-,

The A ⁵ and A ⁷ rings are each independently a 1,4-cyclohexylene group or a 1,4-phenylene group,

The A ⁶ ring may be a 1,4-cyclohexylene group, a 1,4-phenylene group, a 2-fluoro-1,4-phenylene group, a 3-fluoro- A 4-phenylene group,

o is 1 or 2;

As the compound of the formula (3), a compound selected from the liquid crystal compounds having the following structures can be used so as to advantageously control the transparent point, the rotational viscosity, the refractive index anisotropy and the dielectric anisotropy while maintaining a high specific resistance.

[3-1]

[3-1]

[3-2]

[3-2]

[3-3]

[3-3]

[3-4]

[3-4]

[3-5]

[3-5]

[3-6]

[3-6]

[3-7]

[3-7]

[3-8]

[3-8]

[3-9]

[3-9]

[3-10]

[3-10]

[3-11]

[3-11]

[3-12]

[3-12]

[3-13]

[3-13]

[3-14]

[3-14]

In the above formulas, R ³¹ and R ³² are the same as defined in Formula (3).

Meanwhile, the liquid crystal composition may include a high dielectric constant liquid crystal compound represented by the following formula (4) as a matrix third component.

[Chemical Formula 4]

In Formula 4,

R ⁴¹ is a radical of any one of hydrogen and alkyl of 1 to 15 carbon atoms, or wherein one to three of the radicals are substituted by halogen or one or more -CH ₂ - -O-CO-, -O-CO-O-, -O-CO-O-, -OCO-, -CF ₂ O-, -CH = CH-, -O-,

X ² is a radical of any one of F, Cl, CN, NCS and fluoroalkyl of 1 to 5 carbon atoms including 1 to 3 F or a radical in which one or more of the radicals -CH ₂ - is replaced by an oxygen atom Lt;

Y ² is H, F or methyl group, Y ³ and Y ⁴ are each independently H or F,

A ¹¹ , A ²² and A ³³ are each independently any one of rings having the following structure,

Z ¹¹ , Z ¹² and Z ¹³ each independently represents a single bond, -CH ₂ CH ₂ -, -CH═CH-, -CH ₂ O-, -OCH ₂ -, -C≡C-, -CH ₂ CF ₂ -, -CHFCHF-, -CF ₂ CH ₂ -, -CH ₂ CHF-, -CHFCH ₂ -, -C ₂ F ₄ -, -COO-, -OCO-, -CF ₂ O- or -OCF ₂ - ,

f is 1, 2 or 3, g is 0, 1 or 2, h is 0 or 1, and the sum of f, g and h is 2 or 3.

As the compound of formula (4), compounds selected from liquid crystal compounds having the following structures can be used so as to advantageously control the transparent point, the rotational viscosity, the refractive index anisotropy, and the dielectric anisotropy while maintaining a high specific resistance.

[4-1]

[4-1]

[4-2]

[4-2]

[4-3]

[4-3]

[4-4]

[4-4]

[4-5]

[4-5]

[4-6]

[4-6]

[4-7]

[4-7]

[4-8]

[4-8]

[4-9]

[4-9]

[4-10]

[4-10]

[4-11]

[4-11]

[4-12]

[4-12]

[4-13]

[4-13]

[4-14]

[4-14]

[4-15]

[4-15]

[4-16]

[4-16]

[4-17]

[4-17]

[4-18]

[4-18]

In the above formulas, R ⁴¹ and X ² are the same as defined in formula (4).

Meanwhile, the liquid crystal composition may include a high dielectric constant liquid crystal compound represented by the following formula (5) as a fourth component of the matrix.

[Chemical Formula 5]

In Formula 5,

R ⁵¹ is hydrogen and having 1 or any of the radicals of alkyl of 1 to 15, or the radical of from one to three H, or is substituted with halogen or one or more -CH ₂ - so as not to directly connect to an oxygen atom -C≡ -O-CO-, -O-CO-O-, -O-CO-O-, -OCO-, -CF ₂ O-, -CH = CH-, -O-,

X ³ is a radical of any one of F, Cl, CN, NCS and fluoroalkyl having 1 to 5 carbon atoms containing 1 to 3 F or a radical in which one or more of the radicals -CH ₂ - is replaced by an oxygen atom Lt;

Y ⁵ and Y ⁶ are each independently H or F,

A ⁵¹ , A ⁵² and A ⁵³ rings are each independently any one of the rings of the following structures,

Z ⁵¹ , Z ⁵² and Z ⁵³ each independently represents a single bond, -CH ₂ CH ₂ -, -CH═CH-, -CH ₂ O-, -OCH ₂ -, -C≡C-, -CH ₂ CF ₂ -, -CHFCHF-, -CF ₂ CH ₂ -, -CH ₂ CHF-, -CHFCH ₂ -, -C ₂ F ₄ -, -COO-, -OCO-, -CF ₂ O- or -OCF ₂ - ,

j is 1, 2 or 3, k is 0, 1 or 2, m is 0 or 1, and the sum of j, k and m is 2 or 3.

As the compound of formula (5), compounds selected from liquid crystal compounds having the following structures can be used so as to advantageously control the transparent point, the rotational viscosity, the refractive index anisotropy and the dielectric anisotropy while maintaining a high specific resistance.

[5-1]

[5-1]

[5-2]

[5-2]

[5-3]

[5-3]

[5-4]

[5-4]

[5-5]

[5-5]

[5-6]

[5-6]

[5-7]

[5-7]

[5-8]

[5-8]

In the above formulas, R ⁵¹ and X ³ are the same as defined in formula (5).

The liquid crystal composition may include at least one of the first to fourth components described above together with the liquid crystal compound of Formula 1 to provide a liquid crystal material having a remarkably excellent low temperature stability and a high dielectric anisotropy.

Meanwhile, the liquid crystal composition may further include various additives commonly used in the art to which the present invention belongs, in addition to the liquid crystal compound.

Specifically, the liquid crystal composition may further include an antioxidant. Examples of such antioxidants include antioxidants selected from the group consisting of compounds represented by the following formulas (6) and (7).

[Chemical Formula 6]

(7)

In the above formulas (6) and (7), R ¹⁹ and R ²⁰ are each independently a radical of any one of hydrogen, alkyl having 1 to 15 carbon atoms and alkoxy having 1 to 15 carbon atoms, or at least one of -CH ₂ - -CF ₂ O-, -O-, -COO- or -OCO-, or in which one or more of the radicals is replaced by halogen, such that the atoms are not directly connected Lt; / RTI >

A ¹³ is cyclohexylene, tetrahydropyranylene, or dioxanylene.

In addition, the liquid crystal composition may further comprise a UV stabilizer. As such UV stabilizer, Hals (Hindered amine light stabilizer) series can be used. As a non-limiting example, UV stabilizers selected from the group consisting of compounds represented by the following general formulas (8) and (9) can be used.

[Chemical Formula 8]

In Formula 8, R ²³ and R ²⁴ are each independently a radical of any one of hydrogen, alkyl having 1 to 15 carbon atoms and alkoxy having 1 to 15 carbon atoms, or at least one of -CH ₂ - Is a radical substituted with -C≡C-, -CH = CH-, -CF ₂ O-, -O-, -COO- or -OCO-, or one or more of the radicals H is replaced by halogen ,

q is an integer of 0 to 12,

[Chemical Formula 9]

In Formula 9, R ²⁵ is a radical selected from the group consisting of hydrogen, alkyl having 1 to 15 carbon atoms and alkoxy having 1 to 15 carbon atoms, or at least one of -CH ₂ - -, -CH = CH-, -CF ₂ O-, -O-, -COO- or -OCO-, or in which at least one of the radicals H is replaced by halogen,

and d is an integer of 0 to 12.

The antioxidant and / or UV stabilizer may be used in an amount of about 1 to 2,000 ppm or about 200 to 500 ppm based on the total weight of the liquid crystal composition.

Further, when the liquid crystal composition is to be used in a STN or TN mode liquid crystal display device, a compound represented by the following formula (10) may be further added to the liquid crystal composition for realizing the spiral structure.

[Chemical formula 10]

The compound represented by Formula 10 is used in an amount of about 0.01 to about 5 parts by weight based on 100 parts by weight of the liquid crystal composition, thereby easily achieving a desired pitch.

A liquid crystal composition having positive dielectric anisotropy can be provided using the liquid crystal compound of Formula 1 according to an embodiment of the present invention. More specifically, it is possible to provide a liquid crystal composition having a dielectric anisotropy of 3 or more, a transparent point of 70 DEG C or more and a refractive index anisotropy of 0.09 or more A liquid crystal composition can be easily provided.

The liquid crystal composition can be used for AM-LCD (Active Matrix-LCD) or PM-LCD (Passive Matrix-LCD), TN (Twist nematic), STN (Super-twisted nematic) plane switching, Fringe field switching (PLS), plane line switching (PLS), advanced high-performance IPS (IPS), advanced superdimensional switching (ADS), and polymer sustained alignment (PSA) Device.

According to another embodiment of the present invention, there is provided a liquid crystal display device including the liquid crystal composition described above. The liquid crystal composition can be applied to a liquid crystal display device through various methods known in the art. Also, the liquid crystal display device may be manufactured by a liquid crystal display device having various modes as described above.

The liquid crystal compound according to one embodiment of the present invention exhibits excellent low temperature stability and can provide liquid crystal compositions having high dielectric constant and / or high refractive index. Further, liquid crystal compositions optimized for various liquid crystal display devices such as TN, STN, IPS, FFS, PLS, AH-IPS, ADS and PSA modes can be more easily provided through a high resistivity .

BRIEF DESCRIPTION OF THE DRAWINGS The above and other objects, features and advantages of the present invention will be more apparent from the following detailed description taken in conjunction with the accompanying drawings, in which: FIG. However, this is provided as an example of the invention, and the scope of the invention is not limited thereto in any sense.

A liquid crystal compound according to one embodiment of the invention was prepared by the following method, and the properties of the liquid crystal compound were evaluated using the method described below.

Then, a liquid crystal composition containing the liquid crystal compound was prepared, and physical properties of the liquid crystal composition were also evaluated by the following methods.

Specifically, the physical properties of the liquid crystal compound are defined as the extrapolated values obtained by substituting the measured values of the samples prepared by mixing 10% by weight of the liquid crystal compounds and 90% by weight of the mother liquid crystals, The mother liquid crystal had a transparent point of 78.3 占 폚, a refractive index anisotropy [? N] of 0.1214, a dielectric anisotropy [??] Of 5.0, and a rotational viscosity [? ₁ ] of 57 mPa? S.

[Formula 1]

(Measured value of the sample) - (measured value of the liquid crystal)} / (weight% of the liquid crystal compound) X 100]

(1) Clear point

A sample containing a liquid crystal compound to be measured for a transparent point or a drop of a liquid crystal composition on a slide glass with a dropper was covered with a cover glass to prepare a sample for measuring a transparent point.

The sample prepared above was put into a tool equipped with a METTLER TOLEDO FP90 temperature regulator and the change of the sample was observed by raising the temperature at a rate of 3 ° C / min with the FP82HT hot stage. The temperature at the point where the hole was formed in the sample was recorded, and this operation was repeated three times to derive an average value. This value was defined as a transparent point of the sample or liquid crystal composition.

(2) Refractive Index Anisotropy

The refractive index anisotropy [? N] of the sample or liquid crystal composition was measured with an Abbe refractometer equipped with a polarizing plate on an eyepiece using light having a wavelength of 589 nm at 20 ° C. After rubbing the surface of the primary prism in one direction, the sample or liquid crystal composition to be measured was dropped into the primary prism. Thereafter, the refractive index (n∥) when the direction of the polarized light was parallel to the rubbing direction and the refractive index (n⊥) when the polarizing direction was perpendicular to the rubbing direction were measured. Then, the refractive index anisotropy (? N) was measured by substituting the refractive index value into the equation (2).

[Formula 2]

? N = n? - n?

(3) Dielectric constant Anisotropy

The dielectric anisotropy [??] Of the sample or liquid crystal composition was calculated by substituting? 3 and?? Measured in the following manner into Equation 3.

[Formula 3]

△ = ε∥ - ε⊥

(1) Measurement of dielectric constant??: A vertical alignment agent was applied to the surface of the two glass substrates on which the ITO pattern was formed to form a vertical alignment film. Subsequently, the spacers were coated on one of the two glass substrates so that the vertical alignment films faced each other and the interval (cell gap) between the two glass substrates was 4 占 퐉, and then the two glass substrates were bonded together. The sample or the liquid crystal composition to be measured is injected into the device, and the sample or the liquid crystal composition is sealed with an adhesive which is cured by ultraviolet rays. Subsequently, the device was used in a 4294A instrument manufactured by Agilent, and the dielectric constant?? Of the device was measured at 20 占 폚.

(2) Measurement of dielectric constant??: A horizontal alignment agent was applied to the surface of the two glass substrates on which the ITO pattern was formed to form a horizontal alignment film. Subsequently, the spacers were coated on one of the two glass substrates so that the horizontal alignment films faced each other and the interval (cell gap) between the two glass substrates was 4 占 퐉, and then the two glass substrates were bonded together. The sample or the liquid crystal composition to be measured is injected into the device, and the sample or the liquid crystal composition is sealed with an adhesive which is cured by ultraviolet rays. Thereafter, the device was used in a 4294A instrument manufactured by Agilent, and the dielectric constant?? Of the device was measured at 20 ° C.

(4) Rotational viscosity

A horizontal alignment agent was applied to the surface of the two glass substrates on which the ITO pattern was formed to form a horizontal alignment film. Then, the spacers were coated on any one of the two glass substrates so that the horizontal alignment films faced each other and the interval (cell gap) between the two glass substrates was 20 占 퐉, and then the two glass substrates were bonded together. Then, a sample or a liquid crystal composition was injected into the device and sealed with an adhesive which was cured with ultraviolet rays. Thereafter, using a Model 6254 instrument manufactured by Toyo Corp. equipped with a temperature controller (Model SU-241) manufactured by ESPEC Corp., the rotational viscosity of the device was measured at 20 ° C.

(5) Melting point

A sample or liquid crystal composition to be measured for melting point was placed on a slide glass and covered with a cover glass to prepare a sample for melting point measurement.

The sample prepared above was put into a tool equipped with a METTLER TOLEDO FP90 temperature regulator and the change of the sample was observed by raising the temperature at a rate of 3 ° C / min with the FP82HT hot stage. The temperature at the point where the sample changes from a solid state to a liquid crystal phase showing fluidity was recorded, and this operation was repeated three times to derive an average value. This value was defined as the melting point of the sample at the time of heating.

Then, the change of the sample was observed while lowering the temperature at a rate of 3 ° C / min using the same equipment. The temperature at the point where the sample changes from the liquid crystal to the crystal phase was recorded, and this operation was repeated three times to derive an average value. This value was defined as the melting point at the time of warming of the sample.

(6) Low temperature stability

A 10 mL vial was prepared and 2 mL of a sample or a liquid crystal composition containing a liquid crystal compound to be tested for physical property was injected into the vial. The state of the sample or liquid crystal composition at -25 캜 was observed for 30 days. The low temperature stability was evaluated as a period during which the state of the sample or liquid crystal composition was stably maintained at -25 ° C. In the following, when the sample or the liquid crystal composition maintains a stable state even after 30 days have elapsed, it is indicated as " 30 days or more ".

Manufacturing example  1: Synthesis of liquid crystal compound 1-A1

A mixture of the alcohol compound (A-1-2) (2.3 g, 14.2 mmol), potassium carbonate (3.6 g, 25.9 mmol), tetrabutylammonium bromide (0.42 g, 1.29 mmol) and DMF (50 mL) Lt; RTI ID = 0.0 > 40 C. < / RTI > Then, the bromine compound (A-1-1) (5.8 g, 15 mmol) was dissolved in 50 mL of DMF and added dropwise to the mixture. Then, the obtained mixture was heated to 90 DEG C and reacted for about 2 hours, and then the mixture was cooled in an ice bath. The product was then extracted with toluene from the mixture, which was distilled under reduced pressure to obtain a brown solid. The solid was purified by silica gel column chromatography and recrystallization (using a mixed solvent of hexane and ethyl acetate) to obtain white crystals (4.76 g, 10.3 mol). (Yield: 73%) Mass spectrum: 307, 468 [M ⁺ ]

Manufacturing example  2: Synthesis of liquid crystal compound 1-A2

A mixture of the alcohol compound (A-2-2) (4.1 g, 25.6 mmol), potassium carbonate (6.4 g, 46.6 mmol), tetrabutylammonium bromide (0.75 g, 2.3 mmol) and DMF (70 mL) Lt; RTI ID = 0.0 > 40 C. < / RTI > The bromine compound (A-2-1) (12.9 g, 27 mmol) was dissolved in 70 mL of DMF and added dropwise to the mixture. Then, the obtained mixture was heated to 90 DEG C and reacted for about 2 hours, and then the mixture was cooled in an ice bath. The product was then extracted with toluene from the mixture, which was distilled under reduced pressure to obtain a brown solid. The solid was purified by silica gel column chromatography and recrystallization (using a mixed solvent of hexane and ethyl acetate) to obtain white crystals (10.2 g, 18.1 mol). (Yield 71%) Mass spectrum: 372, 401, 562 [M ⁺ ]

Test Example  One: In the production example  Evaluation of physical properties of prepared liquid crystal compounds

The physical properties of the liquid crystal compounds prepared in Preparation Examples 1 and 2 and the liquid crystal compounds P-1, P-2 and Q-1 having the high dielectric anisotropy were measured by the methods described above, and the results are shown in Table 1.

[액정 화합물 P-1]

[Liquid crystal compound P-1]

[액정 화합물 P-2]

[Liquid crystal compound P-2]

[액정 화합물 Q-1]

[Liquid crystal compound Q-1]

Production Example 1
(1-A1) Production Example 2
(1-A2) Liquid crystal compound P-1 Liquid crystal compound P-2 Liquid crystal compound Q-1 Clear point [℃] 11 113 7 109 99 Δn 0.13 0.21 0.14 0.22 0.20 △ ε 23 30 22 30 31 gamma 1 152 299 132 160 232 Melting point (temperature increase) [캜] 78 90 44 86 73 Melting point (temp.) [℃] <30 38 41 71 58 Low temperature stability More than 30 days More than 30 days More than 30 days 2 days More than 30 days

The melting points of the liquid crystal compounds P-1, P-2 and Q-1, which are the factors affecting the low-temperature stability of the liquid crystal compound, are the melting points at 41 ° C., 71 ° C. and 58 ° C. Respectively. However, the liquid crystal compound according to an embodiment of the present invention has melting points of 30 ° C or lower and 38 ° C, respectively, at the time of low temperature compared to conventional liquid crystal compounds. As a result, it was confirmed that the liquid crystal compound according to one embodiment of the present invention exhibits excellent low temperature stability compared to the conventional liquid crystal compound.

Example  And Comparative Example : Preparation of liquid crystal composition

The liquid crystal compounds used in Examples and Comparative Examples are represented by codes. In the above code, the symbol of the ring constituting the central group of the liquid crystal compound is described in order from the left, and the connecting group connecting the ring of the central group is described in order, and the end group is written on the right side. At this time, there is no separate division mark between the link group of the central group and the link of the center group, but the center group and the end group are distinguished by indicating "- " It is classified. The individual abbreviated symbols (codes) of the substances are summarized in Table 2 below.

Center group Connection group End group rescue sign rescue sign rescue sign rescue sign

A -CF ₂ O- X -C _n H _{2n + 1} n

OK

B -CH ₂ CH ₂ - N -OC _n H _{2n + 1} On -OCF ₃ OCF3

B ' -COO- L

V -F F

C

U1 -CF ₃ CF3

D

3 = 2 -C≡N CN

E

W

F

I

Ia

Referring to Table 2 above, the following code means a liquid crystal compound having the structure shown below.

ACE-3.F:

ACEXE-3.F:

BB-3.V:

BB-3.U1:

According to the composition shown in the following Table 3, the liquid crystal compositions of Examples 1 to 6 including the liquid crystal compound according to one embodiment of the invention and the liquid crystal compositions of Comparative Examples 1 to 4 without the liquid crystal compound according to one embodiment of the invention . The properties of the liquid crystal composition were evaluated and are shown in Table 3.

Code Comparative Example Example One 2 3 4 One 2 3 4 5 6 BB-3.V 36.2 39.9 15.0 22.4 30.8 33.9 30.8 33.9 13.1 20.2 BB-3.U1 9.3 6.9 6.0 7.9 5.9 7.9 5.9 ACE-2.F 2.4 3.6 2.0 3.1 2.0 3.1 ACE-3.F 7.5 7.7 6.4 6.5 6.4 6.5 ACE-5.F 8.0 5.4 6.8 4.6 6.8 4.6 BAA-5.2 4.2 2.2 3.6 1.9 3.6 1.9 BBE-3.F 7.0 7.4 5.5 6.0 6.0 7.9 6.5 BBA-3.OCF3 4.5 6.5 6.0 10.8 3.8 5.5 3.8 5.5 14.0 7.4 BBCE-3.F 2.1 4.3 8.6 1.8 3.7 1.8 3.7 1.8 ACA-2.3 2.6 2.2 2.2 ACA-3.3 1.6 1.4 1.4 BAE-3.F 5.0 7.1 8.0 4.6 4.3 6.0 4.3 6.0 11.3 7.2 BAA-3.2 4.4 4.8 7.0 3.7 4.1 3.7 4.1 3.3 2.7 BBA-V.1 5.2 4.0 11.0 4.4 4.4 6.5 7.2 BAC-3.F 6.6 BCE-3.F 6.0 BBA-3.1 3.7 6.5 7.2 ACA-2.F 6.3 1.8 5.4 5.4 ACA-3.F 5.3 6.0 4.6 4.5 4.5 4.2 1.1 ACA-5.F 1.8 P-1 26.0 25.6 15.7 P-2 8.2 Production Example 1
(1-A1) 15 10 15 10 15.7 26.7 Production Example 2
(1-A2) 5 5 7.2 Low temperature
stability More than 30 days More than 30 days 10 days 8 days More than 30 days More than 30 days More than 30 days More than 30 days More than 30 days More than 30 days Transparent point
[° C] 78.5 75.0 75.1 75.6 68.1 73.4 65.0 70.2 75.6 75.0 Δn 0.1093 0.1183 0.1198 0.1202 0.1119 0.1165 0.1190 0.1238 0.1152 0.1118 Δε 4.5 5.3 11.0 11.0 7.3 7.7 7.7 8.1 11.1 11.3

(The unit of composition in Table 3 is% by weight.)

Referring to Table 3, the compositions of Comparative Examples 1 and 2, which are conventional liquid crystal compositions, exhibit a dielectric anisotropy of about 4.5 and 5.3, respectively. However, the liquid crystal composition according to Example 1 To 6 showed an increased dielectric anisotropy from 7.3 to 11.3.

On the other hand, the liquid crystal compositions of Comparative Examples 3 and 4 to which the conventional liquid crystal compounds P1 and P2 for high-permittivity anisotropy were added also exhibited a high dielectric anisotropy of about 11.0. However, the liquid crystal compositions of Comparative Examples 3 and 4 failed to maintain their state at low temperatures of -25 占 폚 for only about 8 to 10 days. In contrast, the liquid crystal compositions of Examples 5 and 6 maintained a stable state for more than 30 days at a low temperature of -25 DEG C, exhibiting a higher dielectric anisotropy relative to the compositions of Comparative Examples 3 and 4. [

Thus, the liquid crystal compound of Formula 1 according to an embodiment of the present invention is expected to satisfy various display requirements more easily by providing a liquid crystal composition exhibiting excellent low-temperature stability while exhibiting high anisotropy.

Claims (16)

A liquid crystal compound represented by the following formula (1)
[Chemical Formula 1]

In Formula 1,
Wherein R ¹ is a radical of any one of hydrogen and alkyl of 1 to 15 carbon atoms, or wherein one to three of the radicals are substituted by halogen or one or more -CH ₂ - -O-CO-, -O-CO-O-, -O-CO-O-, -OCO-, -CF ₂ O-, -CH = CH-, -O-,
X ¹ is a radical of any one of F, Cl, CN, NCS and fluoroalkyl of 1 to 5 carbon atoms containing 1 to 3 F, or wherein at least one -CH ₂ - of the radicals is replaced by an oxygen atom Radical,
Y ¹ is H or F,
The A ¹ and A ² rings are each independently any one of rings having the following structure,

Z ¹ is a single _{bond, -CH 2 CH 2 -, -CH} = CH-, -CH 2 O-, -OCH 2 -, -C≡C-, -CH 2 CF 2 -, -CHFCHF-, -CF 2 _{CH 2 -, -CH 2 CHF-,} -CHFCH 2 -, -C 2 F 4 -, -COO-, -OCO-, -CF 2 O- or -OCF ₂ -, and
n is 0 or 1;
The compound of claim 1, wherein R ¹ is selected from the group consisting of hydrogen, -CH = CH ₂ , -CH ₂ -CH ₂ -CH═CH ₂ , -CH═CH-CH ₃ or -CH ₂ -CH ₂ -CH═CH ₂ -CH ₃ &lt; / RTI &gt; and alkyl having 1 to 3 carbon atoms.
The liquid crystal compound according to claim 1, wherein X ¹ is F, Cl, CF ₃ or OCF ₃ .
The liquid crystal compound according to claim 1, wherein the compound represented by Formula 1 is one of liquid crystal compounds having the following structure:

[1-1]

[1-2]

[1-3]

[1-4]

[1-5]

[1-6]

[1-7]

[1-8]

[1-9]

[1-10]

[1-11]

[1-12]

[1-13]

[1-14]

[1-15]

[1-16]

[1-17]

[1-18]

[1-19]

[1-20]

[1-21]

[1-22]

[1-23]

[1-24]
Wherein R ¹ is independently a radical of any one of hydrogen and alkyl of 1 to 15 carbon atoms or one to three of the radicals are substituted by halogen or one or more -CH ₂ - not connected -C≡C-, -CF is _{2 O-, -CH = CH-, -O-} , -CO-O-, -O-CO- or a radical replaced by a -O-CO-O-.
A liquid crystal composition comprising a liquid crystal compound represented by formula (1) according to claim 1.
A liquid crystal composition comprising the liquid crystal compound represented by the general formula (1) of claim 5 in an amount of 1 to 50 parts by weight based on 100 parts by weight of the total liquid crystal compound.
The liquid crystal composition according to claim 5, further comprising at least one liquid crystal compound selected from the group consisting of the following formulas (2) to (5):
(2)

(3)

[Chemical Formula 4]

[Chemical Formula 5]

In the above formulas 2 to 5,
R ²¹ , R ²² , R ³¹ , R ³² , R ⁴¹ and R ⁵¹ are each independently a radical of any one of hydrogen and alkyl of 1 to 15 carbon atoms, or wherein 1 to 3 of the radicals are substituted by halogen or one or more -CH ₂ - is -C≡C-, -CF from being connected directly to an oxygen atom _{2 O-, -CH = CH-, -O-} , -CO-O-, -O-CO- or - O-CO-O-, &lt; / RTI &gt;
X ² and X ³ are each independently a radical of any of F, Cl, CN, NCS and fluoroalkyl of 1 to 5 carbon atoms containing 1 to 3 F, or at least one of the radicals -CH ₂ - Is a radical substituted with an oxygen atom,
Y ² is H, F or a methyl group, Y ³ to Y ⁶ are each independently H or F,
A ³ , A ⁴ , A ⁵ and A ⁷ are each independently a 1,4-cyclohexylene group or a 1,4-phenylene group,
The A ⁶ ring may be a 1,4-cyclohexylene group, a 1,4-phenylene group, a 2-fluoro-1,4-phenylene group, a 3-fluoro- A 4-phenylene group,
A ¹¹ , A ²² , A ³³ , A ⁵¹ , A ⁵² and A ⁵³ are each independently any one of the rings of the following structures,

Z ¹¹ , Z ¹² , Z ¹³ , Z ⁵¹ , Z ⁵² and Z ⁵³ each independently represents a single bond, -CH ₂ CH ₂ -, -CH═CH-, -CH ₂ O-, -OCH ₂ - _{≡C-, -CH 2 CF 2 -,} -CHFCHF-, -CF 2 CH 2 -, -CH 2 CHF-, -CHFCH 2 -, -C 2 F 4 -, -COO-, -OCO-, -CF _2- O- or -OCF ₂ -, &lt; / _RTI &gt;
o is 1 or 2,
f is 1, 2 or 3, g is 0, 1 or 2, h is 0 or 1, the sum of f, g and h is 2 or 3,
j is 1, 2 or 3, k is 0, 1 or 2, m is 0 or 1, and the sum of j, k and m is 2 or 3.
The liquid crystal composition according to claim 7, wherein the compound represented by Formula 2 is a compound selected from the following liquid crystal compounds:

[2-1]

[2-2]

[2-3]

[2-4]
Wherein R ²¹ and R ²² are each independently a radical of any one of hydrogen and alkyl of 1 to 15 carbon atoms or wherein one to three of the radicals are substituted by halogen or one or more -CH ₂ - Substituted with -C≡C-, -CF ₂ O-, -CH═CH-, -O-, -CO-O-, -O-CO- or -O-CO-O- so that the atoms are not directly connected Radical.
The liquid crystal composition according to claim 7, wherein the compound represented by Formula 3 is a compound selected from the following liquid crystal compounds:

[3-1]

[3-2]

[3-3]

[3-4]

[3-5]

[3-6]

[3-7]

[3-8]

[3-9]

[3-10]

[3-11]

[3-12]

[3-13]

[3-14]
Wherein R ³¹ and R ³² are each independently a radical of any one of hydrogen and alkyl of 1 to 15 carbon atoms or wherein 1 to 3 of the radicals are substituted by halogen or one or more -CH ₂ - Substituted with -C≡C-, -CF ₂ O-, -CH═CH-, -O-, -CO-O-, -O-CO- or -O-CO-O- so that the atoms are not directly connected Radical.
The liquid crystal composition according to claim 7, wherein the compound represented by Formula 4 is a compound selected from the following liquid crystal compounds:

[4-1]

[4-2]

[4-3]

[4-4]

[4-5]

[4-6]

[4-7]

[4-8]

[4-9]

[4-10]

[4-11]

[4-12]

[4-13]

[4-14]

[4-15]

[4-16]

[4-17]

[4-18]
Wherein R ₁ is independently a radical of any one of hydrogen and alkyl of 1 to 15 carbon atoms or one to three of the radicals are substituted by halogen or one or more -CH ₂ - not connected -C≡C-, -CF is a radical substituted _{2 O-, -CH = CH-, -O-} , -CO-O-, -O-CO- or -O-CO-O-,
X ₁ is a radical of any one of F, Cl, CN, NCS and fluoroalkyl of 1 to 5 carbon atoms containing 1 to 3 F or a radical in which one or more of the radicals -CH ₂ - is replaced by an oxygen atom to be.
The liquid crystal composition according to claim 7, wherein the compound represented by Formula 5 is a compound selected from the following liquid crystal compounds:

[5-1]

[5-2]

[5-3]

[5-4]

[5-5]

[5-6]

[5-7]

[5-8]
Wherein R ⁵¹ is independently a radical of any one of hydrogen and alkyl of 1 to 15 carbon atoms or one to three of the radicals are substituted by halogen or one or more -CH ₂ - not connected -C≡C-, -CF is a radical substituted _{2 O-, -CH = CH-, -O-} , -CO-O-, -O-CO- or -O-CO-O-,
X ³ is a radical selected from the group consisting of F, Cl, CN, NCS and fluoroalkyl having 1 to 5 carbon atoms containing 1 to 3 F or a radical in which at least one of -CH ₂ - to be.
The liquid crystal composition according to claim 5, further comprising an antioxidant selected from the group consisting of compounds represented by the following general formulas (6) and (7)
[Chemical Formula 6]

(7)

In the formulas (6) and (7), R ¹⁹ and R ²⁰ are each independently a radical of any one of hydrogen, an alkyl group having 1 to 15 carbon atoms and an alkoxy group having 1 to 15 carbon atoms, or at least one of -CH ₂ - -CH = CH-, -CF ₂ O-, -O-, -COO- or -OCO- so that the oxygen atoms are not directly connected, or at least one of these radicals is replaced by halogen Lt; / RTI &gt;
A ¹³ is cyclohexylene, tetrahydropyranylene, or dioxanylene.
The liquid crystal composition according to claim 5, further comprising a UV stabilizer selected from the group consisting of compounds represented by the following formulas (8) and (9):
[Chemical Formula 8]

In Formula 8, R ²³ and R ²⁴ are each independently a radical of any one of hydrogen, alkyl having 1 to 15 carbon atoms and alkoxy having 1 to 15 carbon atoms, or at least one of -CH ₂ - Is a radical substituted with -C≡C-, -CH = CH-, -CF ₂ O-, -O-, -COO- or -OCO-, or one or more of the radicals H is replaced by halogen ,
q is an integer of 0 to 12,
[Chemical Formula 9]

In Formula 9, R ²⁵ is a radical selected from the group consisting of hydrogen, alkyl having 1 to 15 carbon atoms and alkoxy having 1 to 15 carbon atoms, or at least one of -CH ₂ - -, -CH = CH-, -CF ₂ O-, -O-, -COO- or -OCO-, or in which at least one of the radicals H is replaced by halogen,
and d is an integer of 0 to 12.
The liquid crystal composition according to claim 5, further comprising a compound represented by the following formula (10):
[Chemical formula 10]

A liquid crystal display comprising the liquid crystal composition according to claim 5.
16. The liquid crystal display device according to claim 15, wherein the liquid crystal display device is a twisted nematic (TN), a super twisted nematic (STN), an in-plane switching (IPS), a fringe field switching (FFS), a planar line switching (PLS) advanced high-performance IPS, Advanced-super-dimensional switching (ADS), or Polymer sustained alignment (PSA) mode.