KR20210063515A - Liquid crystal composition and display device comprising the same - Google Patents

Abstract

Disclosed are a liquid crystal composition and a display device including the same. According to one embodiment, based on 100 parts by weight of a total liquid crystal composition, the liquid crystal composition includes: 19.5 to 24.5 parts by weight of a liquid crystal compound represented by Chemical formula 1; 3.5 to 8.5 parts by weight of a liquid crystal compound represented by Chemical formula 2; 3 to 8 parts by weight of a liquid crystal compound represented by Chemical formula 3; 8.5 to 13.5 parts by weight of a liquid crystal compound represented by Chemical formula 4; 18 to 23 parts by weight of a liquid crystal compound represented by Chemical formula 5; 1 to 6 parts by weight of a liquid crystal compound represented by Chemical formula 6; 11.5 to 16.5 parts by weight of a liquid crystal compound represented by Chemical formula 7; and 15 to 20 parts by weight of a liquid crystal compound represented by Chemical formula 8. Accordingly, electrostatic defects are prevented.

Description

A liquid crystal composition and a display device including the same {LIQUID CRYSTAL COMPOSITION AND DISPLAY DEVICE COMPRISING THE SAME}

The present invention relates to a liquid crystal composition and a display device including the same.

The importance of the display device is increasing with the development of multimedia. In response to this, various types of display devices such as a liquid crystal display (LCD) and an organic light emitting display (OLED) are being used.

Among them, a liquid crystal display device is one of the most widely used flat panel display devices at present, and includes two substrates on which field generating electrodes such as a pixel electrode and a common electrode are formed and a liquid crystal layer interposed therebetween. . A liquid crystal display displays an image by applying a voltage to an electric field generating electrode to generate an electric field in a liquid crystal layer, thereby determining the direction of liquid crystal molecules in the liquid crystal layer and controlling the polarization of incident light.

An object of the present invention is to provide a liquid crystal composition capable of preventing electrostatic defects that may occur during a process, and a display device including the same.

The problems of the present invention are not limited to the problems mentioned above, and other technical problems that are not mentioned will be clearly understood by those skilled in the art from the following description.

The liquid crystal composition according to an embodiment for solving the above problems is 19.5 to 24.5 parts by weight of the liquid crystal compound represented by the following Chemical Formula 1, respectively, 3.5 to 8.5 parts by weight of the liquid crystal compound represented by the following Chemical Formula 2, based on 100 parts by weight of the total liquid crystal composition Parts by weight, 3 to 8 parts by weight of the liquid crystal compound represented by the following formula (3), 8.5 to 13.5 parts by weight of the liquid crystal compound represented by the following formula (4), 18 to 23 parts by weight of the liquid crystal compound represented by the following formula (5), represented by the following formula (6) 1 to 6 parts by weight of the liquid crystal compound, 11.5 to 16.5 parts by weight of the liquid crystal compound represented by the following Chemical Formula 7, and 15 to 20 parts by weight of the liquid crystal compound represented by the following Chemical Formula 8.

[Formula 1]

[Formula 2]

[Formula 3]

[Formula 4]

[Formula 5]

[Formula 6]

[Formula 7]

[Formula 8]

In Formulas 1 to 8, X and Y may each independently be an alkyl group or an alkenyl group having 1 to 7 carbon atoms.

The liquid crystal compound represented by Formula 1 may include a first liquid crystal compound in which X and Y are an alkyl group, and a second liquid crystal compound in which X is selected from an alkyl group or an alkenyl group and Y is the other one.

The content of the second liquid crystal compound may be included in an amount of 18 to 36 parts by weight based on 100 parts by weight of the total liquid crystal compound represented by Formula 1 above.

It may further include a compound represented by the following formula (9).

[Formula 9]

The content of the compound represented by Formula 9 may be 0.2 to 0.5 parts by weight based on 100 parts by weight of the total liquid crystal composition.

The liquid crystal composition may have a phase difference (Δnd) of 310 to 350 nm of the liquid crystal panel, an elastic modulus (K33) of 15 to 18 pN, and satisfy Equation 1 below.

[Equation 1]

6.95 ≤ Rotational viscosity (γ1) / Modulus of elasticity (K33) ≤ 7.35

The liquid crystal composition may have an elastic modulus (K11) of 13.5 to 15.5 pN.

The liquid crystal composition may have a refractive index anisotropy (Δn) of 0.1064 to 0.1068.

The liquid crystal composition may have a dielectric anisotropy (Δε) of -3.1 to -3.5.

The liquid crystal composition may satisfy Equation 2 below.

[Equation 2]

4.3 ≤ modulus of elasticity (K33) / dielectric anisotropy (Δε) ≤ 5.6

In addition, a display device according to an embodiment includes a first substrate including a pixel electrode, a second substrate including a common electrode, and a liquid crystal layer interposed between the first substrate and the second substrate, wherein the liquid crystal The layer is, based on 100 parts by weight of the total liquid crystal composition, 19.5 to 24.5 parts by weight of the liquid crystal compound represented by the following Chemical Formula 1, 3.5 to 8.5 parts by weight of the liquid crystal compound represented by the following Chemical Formula 2, and the liquid crystal compound represented by the following Chemical Formula 3 3 to 8 parts by weight, 8.5 to 13.5 parts by weight of the liquid crystal compound represented by the following Chemical Formula 4, 18 to 23 parts by weight of the liquid crystal compound represented by the following Chemical Formula 5, 1 to 6 parts by weight of the liquid crystal compound represented by the following Chemical Formula 6, It may include a liquid crystal composition comprising 11.5 to 16.5 parts by weight of the liquid crystal compound represented by 7, and 15 to 20 parts by weight of the liquid crystal compound represented by the following Chemical Formula 8.

[Formula 1]

[Formula 2]

[Formula 3]

[Formula 4]

[Formula 5]

[Formula 6]

[Formula 7]

[Formula 8]

In Formulas 1 to 8, X and Y may each independently be an alkyl group or an alkenyl group having 1 to 7 carbon atoms.

The liquid crystal compound represented by Formula 1 may include a first liquid crystal compound in which X and Y are an alkyl group, and a second liquid crystal compound in which X is selected from an alkyl group or an alkenyl group and Y is the other one.

The content of the second liquid crystal compound may be included in an amount of 18 to 36 parts by weight based on 100 parts by weight of the total liquid crystal compound represented by Formula 1 above.

It may further include a compound represented by the following formula (9).

[Formula 9]

The content of the compound represented by Formula 9 may be 0.2 to 0.5 parts by weight based on 100 parts by weight of the total liquid crystal composition.

The liquid crystal composition may have a phase difference (Δnd) of 310 to 350 nm of the liquid crystal panel, an elastic modulus (K33) of 15 to 18 pN, and satisfy Equation 1 below.

[Equation 1]

6.95 ≤ Rotational viscosity (γ1) / Modulus of elasticity (K33) ≤ 7.35

The liquid crystal composition may have an elastic modulus (K11) of 13.5 to 15.5 pN.

The liquid crystal composition may have a refractive index anisotropy (Δn) of 0.1064 to 0.1068.

The liquid crystal composition may have a dielectric anisotropy (Δε) of -3.1 to -3.5.

The liquid crystal composition may satisfy Equation 2 below.

[Equation 2]

4.3 ≤ modulus of elasticity (K33) / dielectric anisotropy (Δε) ≤ 5.6

Details of other embodiments are included in the detailed description and drawings.

According to the liquid crystal composition according to an embodiment, the threshold voltage of the liquid crystal may be increased by increasing the elastic modulus (K33) and decreasing the dielectric anisotropy (Δε). Accordingly, the display device according to an exemplary embodiment may reduce texture defects.

Effects according to the embodiments are not limited by the contents exemplified above, and more various effects are included in the present specification.

1 is an exploded perspective view illustrating a display device according to an exemplary embodiment;
FIG. 2 is a plan view illustrating a layout of a pixel of FIG. 1 ;
Fig. 3 is a cross-sectional view taken along line II' of Fig. 2;
FIG. 4 is an enlarged view of area A of FIG. 3 ;
5 is an image of a display device having a texture defect;
6 and 7 are images of pixels according to dielectric anisotropy.
8 and 9 are images of pixels according to the elastic modulus.

Advantages and features of the present invention, and a method of achieving them will become apparent with reference to the embodiments described below in detail together with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but will be implemented in various forms different from each other, and only these embodiments make the disclosure of the present invention complete, and common knowledge in the technical field to which the present invention pertains. It is provided to completely inform the scope of the invention to the possessor, and the invention is only defined by the scope of the claims.

When elements or layers are referred to as “on” of another element or layer includes all cases of interposing another layer or another element directly on or in the middle of another element. The same reference numerals refer to the same elements throughout the specification. The shapes, sizes, proportions, angles, numbers, etc. disclosed in the drawings for explaining the embodiments are examples, and thus the present invention is not limited to the illustrated matters.

Hereinafter, specific embodiments will be described with reference to the accompanying drawings.

1 is an exploded perspective view illustrating a display device according to an exemplary embodiment;

Referring to FIG. 1 , a display device according to an exemplary embodiment includes a smart phone, a mobile phone, a tablet PC, a personal digital assistant (PDA), a portable multimedia player (PMP), a television, a game console, a wrist watch type electronic device, and a head mounted display. , personal computer monitors, notebook computers, car navigation systems, car dashboards, digital cameras, camcorders, external billboards, electric signs, medical devices, inspection devices, various home appliances such as refrigerators and washing machines, or Internet of Things devices.

A display device according to an exemplary embodiment includes a first substrate 100 , a second substrate 200 facing the first substrate 100 , and a liquid crystal layer interposed between the first substrate 100 and the second substrate 200 . (300) may be included. The liquid crystal layer 300 includes a plurality of liquid crystals LC, and the liquid crystal LC may have negative dielectric anisotropy.

A display device according to an embodiment may include a display area DA and a non-display area NA. The display area DA may be an area in which an image is displayed, and the non-display area NA may be an area surrounding the display area DA and shielded from light. The display area DA includes a plurality of pixels PX. Each of the pixels PX may display one of the primary colors to realize color display. For example, the plurality of pixels PX may include a red pixel R displaying red, a green pixel G displaying green, and a blue pixel B displaying blue. The red pixel R, the green pixel G, and the blue pixel B may be repeatedly arranged in the first direction DR1 and the second direction DR2 and arranged in a matrix form. The gate line GL extends in the first direction DR1 and the data line DL extends in the second direction DR2 to provide a gate driving signal and a data driving signal to each of the plurality of pixels PX. can transmit

FIG. 2 is a plan view showing the layout of the pixel of FIG. 1 , FIG. 3 is a cross-sectional view taken along line II′ of FIG. 2 , and FIG. 4 is an enlarged view of area A of FIG. 3 .

2 and 3 , the first substrate 100 is a substrate on which the switching element 120 for controlling the alignment direction of the liquid crystal LC in the liquid crystal layer 300 is disposed, and the second substrate 200 . may be a counter substrate for sealing the liquid crystal layer 300 together with the first substrate 100 .

The first substrate 100 may include a first insulating substrate 110 , a switching device 120 disposed on the first insulating substrate 110 , and a pixel electrode 150 disposed on the switching device 120 . can

The first insulating substrate 110 may be a transparent insulating substrate. For example, the first insulating substrate 110 may be a glass or plastic substrate. In addition, the first insulating substrate 110 may have flexibility.

The switching element 120 may be disposed on the first insulating substrate 110 . The switching element 120 includes a gate electrode 121 disposed on the first insulating substrate 110 , a semiconductor layer 122 disposed on the gate electrode 121 , and a source disposed spaced apart from each other on the semiconductor layer 122 . It may be a thin film transistor including an electrode 123 and a drain electrode 124 .

The gate electrode 121 is connected to the gate line GL to transmit a gate driving signal. The gate electrode 121 is selected from the group consisting of molybdenum (Mo), aluminum (Al), chromium (Cr), gold (Au), titanium (Ti), nickel (Ni), neodymium (Nd), and copper (Cu). It is formed of any one or an alloy thereof. In addition, the gate electrode 121 is a group consisting of molybdenum (Mo), aluminum (Al), chromium (Cr), gold (Au), titanium (Ti), nickel (Ni), neodymium (Nd), and copper (Cu). It may be a multi-layer made of any one selected from or alloys thereof. For example, the gate electrode 121 may be a double layer of molybdenum/aluminum-neodymium or molybdenum/aluminum.

A gate insulating layer 131 to insulate the gate electrode 121 may be disposed on the gate electrode 121 . The gate insulating layer 131 may be made of silicon oxide (SiOx), silicon nitride (SiNx), or silicon oxynitride (SiOxNy), and may be a single layer or multiple layers thereof.

A semiconductor layer 122 may be disposed on the gate insulating layer 131 . The semiconductor layer 122 may overlap the gate electrode 121 on the gate insulating layer 131 . The semiconductor layer 122 may be formed of a silicon semiconductor or an oxide semiconductor. The silicon semiconductor may include amorphous silicon or crystallized polycrystalline silicon. Here, polycrystalline silicon has high mobility (100 cm 2 /Vs or more), low energy consumption, and excellent reliability, and since oxide semiconductor has low off-current, in this embodiment, it is optional can be used as

A source electrode 123 and a drain electrode 124 spaced apart from each other may be disposed on the semiconductor layer 122 . The source electrode 123 may be connected to the data line DL to transmit a data driving signal, and the drain electrode 124 may be electrically connected to the pixel electrode 150 .

The source electrode 123 and the drain electrode 124 may be formed of a single layer or multiple layers. When the source electrode 123 and the drain electrode 124 are a single layer, molybdenum (Mo), aluminum (Al), chromium (Cr), gold (Au), titanium (Ti), nickel (Ni), neodymium (Nd) and copper (Cu), or an alloy thereof. In addition, when the source electrode 123 and the drain electrode 124 are multi-layered, two layers of copper/titanium or molybdenum/aluminum-neodymium, titanium/aluminum/titanium, molybdenum/aluminum/molybdenum or molybdenum/aluminum-neodymium/molybdenum It may consist of three layers of

A protective layer 133 capable of protecting the switching device 120 may be disposed on the aforementioned switching device 120 . The passivation layer 133 may be formed of an inorganic material, an organic material, or a mixture thereof. When the passivation layer 133 is an inorganic material, it may be formed of a single layer of silicon oxide (SiOx), silicon nitride (SiNx), or silicon oxynitride (SiOxNy) or multiple layers thereof. When the passivation layer 133 is made of an organic material, it may be formed of an organic material such as polyimide, benzocyclobutene series resin, or acrylate series resin. When the passivation layer 133 is a mixture of an inorganic material and an organic material, the organic material may be disposed on the inorganic material to planarize the lower step.

The pixel electrode 150 may be disposed on the passivation layer 133 . The pixel electrode 150 may be connected to the drain electrode 124 through the contact hole 140 and may be controlled by a data driving signal.

The pixel electrode 150 includes a first stem portion 151 , a plurality of branch portions 152 that extend outwardly from the stem portion 151 and are spaced apart from each other with a slit 153 interposed therebetween, and the switching element 120 . It may include an extended part 154 .

The stem part 151 may include a horizontal stem part extending in the first direction DR1 and a vertical stem part extending in the second direction DR2 . The stem 151 may divide the pixel electrode 150 into subregions, that is, domains. The stem portion 151 may have a cross shape, for example. In this case, the pixel electrode 150 may be divided into four subregions by the stem portion 151 . The branch portions 152 positioned in each of the subregions may extend in different directions. For example, as shown in FIG. 2 , the branch part 152 positioned in the subregion in the upper right direction obliquely extends from the stem part 151 in the upper right direction, and the branch part positioned in the subregion in the lower right direction. Reference numeral 152 may extend obliquely from the stem portion 151 in the lower right direction. In addition, the branch 152 positioned in the upper-left sub-region extends obliquely in the upper-left direction from the stem 151 , and the branch 152 positioned in the lower-left sub-region extends from the stem 151 to the lower left. may extend obliquely in the direction. The extension part 154 may extend from the stem part 151 or the branch part 152 to the switching element 120 and may be connected to the drain electrode 124 through the contact hole 140 .

The pixel electrode 150 may include a transparent conductive material through which light may pass. The pixel electrode 150 may be made of Indium Tin Oxide (ITO), Indium Zinc Oxide (IZO), or Indium Tin Zinc Oxide (ITZO), but is not limited thereto. Any material with conductivity can be used.

A first alignment layer 160 may be disposed on the pixel electrode 150 . The first alignment layer 160 may include a vertical alignment group, and may induce initial vertical alignment of the liquid crystals LC in the liquid crystal layer 300 through the vertical alignment group. The first alignment layer 160 may include polyamic acid or polyimide.

Meanwhile, the second substrate 200 includes a second insulating substrate 210 , a light blocking member 220 disposed on the second insulating substrate 210 , a color filter 230 , and a light blocking member 220 and a color filter ( The common electrode 250 disposed on the 230 may be included.

The second insulating substrate 210 may be a transparent insulating substrate such as the first insulating substrate 110 . The light blocking member 220 may be made of a material that blocks transmission of light by absorbing or reflecting light of at least a specific wavelength band. For example, the light blocking member 220 may be a black matrix. The light blocking member 220 may be disposed at a boundary between adjacent pixels to prevent color mixing.

The color filter 230 may include a material that absorbs a specific wavelength band of transmitted light or shifts or converts the wavelength of transmitted light to a specific wavelength. That is, the color filter 230 may selectively transmit only light of a specific wavelength band. 3 illustrates that the light blocking member 220 and the color filter 230 are disposed on the second substrate 200 , at least one of the light blocking member 220 and the color filter 230 is disposed on the first substrate 100 . may be placed in

An overcoat layer 240 may be disposed on the light blocking member 220 and the color filter 230 . The overcoat layer 240 may include an organic material. The overcoat layer 240 may planarize a step difference caused by the components stacked on the second substrate 210 .

A common electrode 250 may be disposed on the overcoat layer 240 . The common electrode 250 may be disposed on a plurality of pixels to apply a common voltage. The common electrode 250 may form a vertical electric field in the liquid crystal layer 300 together with the pixel electrode 150 . The common electrode 250 may form an electric field in the liquid crystal layer 300 together with the pixel electrode 150 to control the alignment direction of the liquid crystal LC. 3 illustrates that the pixel electrode 150 is disposed on the first substrate 100 and the common electrode 250 is disposed on the second substrate 200 , but the pixel electrode 150 and the common electrode 250 are They may be disposed on the same substrate.

A second alignment layer 260 may be disposed on the common electrode 250 . Since the second alignment layer 260 has the same configuration as that of the first alignment layer 160 , the overlapping description will be omitted.

The liquid crystal layer 300 may be disposed between the first substrate 100 and the second substrate 200 . The liquid crystal layer 300 may include a plurality of liquid crystals LC. The liquid crystal composition constituting the liquid crystal layer 300 may have negative dielectric anisotropy. In the initial alignment state, the liquid crystal LC may maintain a stabilized state with its long axis aligned in a direction approximately perpendicular to the alignment surface. In addition, the liquid crystal LC may maintain a stabilized state with a predetermined pre-tilt angle.

The liquid crystal LC having negative dielectric anisotropy may be inclined so that its long axis forms a predetermined angle with respect to the direction of the electric field by the vertical electric field formed by the pixel electrode 150 and the common electrode 250 . As the direction of the long axis of the liquid crystal LC changes, the retardation value changes, and accordingly, the amount of light passing through the liquid crystal layer 300 may be adjusted. In the embodiment, the initial alignment state means an alignment state of the liquid crystal LC in a state in which an electric field is not formed in the liquid crystal layer 300 .

Referring to FIG. 4 , the display device according to an exemplary embodiment may be in a polymer stabilized vertical alignment mode (PS-VA mode). The polymer stabilization vertical alignment mode can stabilize the pre-tilt alignment of the liquid crystal (LC) through a polymer network composed of polymers of reactive mesogens (RM). The liquid crystal layer 300 may include a liquid crystal LC and a reactive mesogen RM. Reactive mesogens (RMs) may form a polymer network composed of polymers of reactive mesogens (RMs) through a UV exposure process.

When an electric field is formed in the liquid crystal layer 300 , the liquid crystals LC are inclined in a direction parallel to the longitudinal direction of the branch 152 of the pixel electrode 150 in response to the electric field, and the liquid crystal LC in one pixel The direction in which they are inclined may be in a total of 4 directions. When the liquid crystal layer 300 is irradiated with UV while an electric field is applied, the reactive mesogen undergoes a polymerization reaction to form a polymer network composed of polymers in contact with the first and second alignment layers 160 and 260 described above. The initial alignment direction of the liquid crystals (LC) is determined to have a pretilt in the above-mentioned direction by the polymer network.

The liquid crystal composition constituting the liquid crystal layer 300 according to an embodiment may include a neutral liquid crystal compound and a polar liquid crystal compound including at least one fluorine atom.

The neutral liquid crystal compound may include a liquid crystal compound represented by the following Chemical Formulas 1 to 4.

[Formula 1]

[Formula 2]

[Formula 3]

[Formula 4]

In Formulas 1 to 4, X and Y may each independently be an alkyl group or an alkenyl group having 1 to 7 carbon atoms.

Specifically, each of Formulas 1 to 4 may include an alkyl group or an alkenyl group. When X and Y are both an alkyl group or an alkenyl group, the alkyl group or the alkenyl group may be the same as or different from each other. The alkyl group or the alkenyl group may each have the same number of carbon atoms or may have different carbon numbers.

The liquid crystal compound represented by Formula 1 may be included in an amount of 19.5 to 24.5 parts by weight based on 100 parts by weight of the total liquid crystal composition. When the liquid crystal compound represented by Formula 1 is included in an amount of 19.5 to 24.5 parts by weight based on 100 parts by weight of the total liquid crystal composition, stability of the liquid crystal may be improved.

In particular, the liquid crystal compound represented by Formula 1 may include two types of compounds. For example, a first liquid crystal compound in which X and Y are an alkyl group and a second liquid crystal compound in which X (or Y) is an alkyl group and Y (or X) is an alkenyl group may be included. In this case, based on 100 parts by weight of the total liquid crystal compound represented by Formula 1, 18 to 36 parts by weight of the second liquid crystal compound may be included, and the remaining part by weight may include the first liquid crystal compound. When the second liquid crystal compound is included in 18 to 36 parts by weight based on the liquid crystal compound represented by Formula 1, the viscosity of the liquid crystal composition may be appropriately adjusted.

The liquid crystal compound represented by Formula 2 may be included in an amount of 3.5 to 8.5 parts by weight based on 100 parts by weight of the total liquid crystal composition. When the liquid crystal compound represented by Formula 2 is included in 3.5 to 8.5 parts by weight based on 100 parts by weight of the total liquid crystal composition, refractive index anisotropy (Δn), nematic phase-isotropic transition temperature (Tni), rotational viscosity (γ1) and elastic modulus (K11) , K33) can be improved.

The liquid crystal compound represented by Formula 3 may be included in an amount of 3 to 8 parts by weight based on 100 parts by weight of the total liquid crystal composition. When the liquid crystal compound represented by Formula 3 is included in an amount of 3 to 8 parts by weight based on 100 parts by weight of the total liquid crystal composition, stability of the liquid crystal may be improved.

The liquid crystal compound represented by Formula 4 may be included in an amount of 8.5 to 13.5 parts by weight based on 100 parts by weight of the total liquid crystal composition. When the liquid crystal compound represented by Formula 4 is included in an amount of 8.5 to 13.5 parts by weight based on 100 parts by weight of the total liquid crystal composition, refractive index anisotropy (Δn), nematic phase-isotropic transition temperature (Tni), rotational viscosity (γ1) and elastic modulus (K11) , K33) can be improved.

The liquid crystal compounds represented by Chemical Formulas 1 to 4 described above are neutral liquid crystal compounds, and each may improve the stability of the liquid crystal.

Meanwhile, the polar liquid crystal compound may include a liquid crystal compound represented by the following Chemical Formulas 5 to 8.

[Formula 5]

[Formula 6]

[Formula 7]

[Formula 8]

In Formulas 5 to 8, X and Y may each independently represent an alkyl group or an alkenyl group having 1 to 7 carbon atoms.

Specifically, each of Formulas 5 to 8 may include an alkyl group or an alkenyl group. When X and Y are both an alkyl group or an alkenyl group, the alkyl group or the alkenyl group may be the same as or different from each other. The alkyl group or the alkenyl group may each have the same number of carbon atoms or may have different carbon numbers.

The liquid crystal compound represented by Formula 5 may be included in an amount of 18 to 23 parts by weight based on 100 parts by weight of the total liquid crystal composition. When the liquid crystal compound represented by Formula 5 is included in an amount of 18 to 23 parts by weight based on 100 parts by weight of the total liquid crystal composition, refractive index anisotropy (Δn) and elastic modulus (K11, K33) may be improved.

The liquid crystal compound represented by Formula 6 may be included in an amount of 1 to 6 parts by weight based on 100 parts by weight of the total liquid crystal composition. When the liquid crystal compound represented by Formula 6 is included in 1 to 6 parts by weight based on 100 parts by weight of the total liquid crystal composition, refractive index anisotropy (Δn), nematic phase-isotropic transition temperature (Tni), rotational viscosity (γ1) and elastic modulus (K11) , K33) can be improved.

The liquid crystal compound represented by Formula 7 may be included in an amount of 11.5 to 16.5 parts by weight based on 100 parts by weight of the total liquid crystal composition. When the liquid crystal compound represented by Formula 7 is included in an amount of 11.5 to 16.5 parts by weight based on 100 parts by weight of the total liquid crystal composition, refractive index anisotropy (Δn) and elastic modulus (K11, K33) may be improved.

The liquid crystal compound represented by Formula 8 may be included in an amount of 15 to 20 parts by weight based on 100 parts by weight of the total liquid crystal composition. When the liquid crystal compound represented by Formula 8 is included in an amount of 15 to 20 parts by weight based on 100 parts by weight of the total liquid crystal composition, refractive index anisotropy (Δn), nematic phase-isotropic transition temperature (Tni), rotational viscosity (γ1) and elastic modulus (K11) , K33) can be improved.

The liquid crystal compounds represented by Chemical Formulas 5 to 8 are polar liquid crystal compounds, and each may improve refractive index anisotropy (Δn) and elastic modulus (K11, K33) of the liquid crystal.

Meanwhile, the liquid crystal composition according to an embodiment may further include a compound represented by the following Chemical Formula 9.

[Formula 9]

The compound represented by Formula 9 is a kind of reactive mesogen, and may include methacrylate having many reactive sites.

The compound represented by Formula 9 may be included in an amount of 0.2 to 0.5 parts by weight based on 100 parts by weight of the total liquid crystal composition. The compound represented by Formula 9 may form a polymer network composed of polymers through a UV irradiation process. Here, the compound represented by Chemical Formula 9 may remain in the liquid crystal layer 300 without forming a polymer network or forming a polymer network.

The liquid crystal composition according to an embodiment may include the liquid crystal compound respectively represented by the above-described Chemical Formulas 1 to 8. In particular, 19.5 to 24.5 parts by weight of the liquid crystal compound represented by Formula 1, 3.5 to 8.5 parts by weight of the liquid crystal compound represented by Formula 2, 3 to 8 parts by weight of the liquid crystal compound represented by Formula 3, and 8.5 to 8 parts by weight of the liquid crystal compound represented by Formula 4 13.5 parts by weight, 18 to 23 parts by weight of the liquid crystal compound represented by Formula 5, 1 to 6 parts by weight of the liquid crystal compound represented by Formula 6, 11.5 to 16.5 parts by weight of the liquid crystal compound represented by Formula 7, and the liquid crystal represented by Formula 8 15 to 20 parts by weight of the compound may be included.

The liquid crystal composition according to the above-described embodiment may have the following physical properties.

The liquid crystal composition may have a phase difference (Δnd) of 310 to 350 nm of the liquid crystal panel, an elastic modulus (K33) of 15 to 18 pN, and satisfy Equation 1 below.

[Equation 1]

6.95 ≤ Rotational viscosity (γ1) / Modulus of elasticity (K33) ≤ 7.35

The liquid crystal composition may have an elastic modulus (K11) of 13.5 to 15.5 pN, refractive index anisotropy (Δn) of 0.1064 to 0.1068, and dielectric anisotropy (Δε) of -3.1 to -3.5.

In addition, the liquid crystal composition may satisfy Equation 2 below.

[Equation 2]

4.3 ≤ modulus of elasticity (K33) / Ι permittivity anisotropy (Δε) Ι ≤ 5.6

The liquid crystal composition may be adjusted so that the refractive index anisotropy has a certain value according to the cell gap within the retardation range of the liquid crystal panel, and the retardation of the liquid crystal panel may be adjusted to have 310 to 350 nm.

The liquid crystal composition having the above composition ratio and physical properties increases the elastic modulus (K33) of the liquid crystal and reduces the dielectric anisotropy (Δε), thereby preventing texture defects.

5 is an image of a display device having a texture defect.

Referring to FIG. 5 , a texture defect may occur in an edge region of a pixel electrode due to static electricity generated during a manufacturing process of a display device. The texture defect is that the liquid crystal is partially rotated by static electricity, and the liquid crystal is not restored, so that the luminance is lowered and horizontal or vertical lines appear.

The texture defect may be weakened when the threshold voltage of the liquid crystal is increased. To this end, referring to Equation 3 below, if the dielectric anisotropy is reduced or the elastic modulus K33 is increased, the threshold voltage may be increased. (Where Vth is the threshold voltage, K is the elastic modulus, ε is the vacuum permittivity, and Δε is the dielectric anisotropy.)

[Equation 3]

Accordingly, the liquid crystal composition according to an embodiment increases the elastic modulus (K33) of the liquid crystal and decreases the dielectric anisotropy (Δε) to increase the threshold voltage, thereby reducing texture defects.

6 and 7 are images of a pixel according to dielectric anisotropy, and FIGS. 8 and 9 are images of a pixel according to an elastic modulus.

Referring to FIG. 6 , in a pixel of a display device including a liquid crystal composition having a dielectric anisotropy (Δε) of 3.7, a texture defect appears at an edge of a pixel electrode. On the other hand, referring to FIG. 7 , in the pixel of the display device including the liquid crystal composition having a dielectric anisotropy (Δε) of 3.1, the texture defect was reduced compared to that of FIG. 6 .

Also, referring to FIG. 8 , in the pixel of the display device including the liquid crystal composition having an elastic modulus (K33) of 10, a texture defect appears at the edge of the pixel electrode. On the other hand, referring to FIG. 9 , the pixel of the display device including the liquid crystal composition having an elastic modulus (K33) of 17 has reduced texture defects compared to FIG. 8 .

Through this, it can be seen that the liquid crystal composition according to an embodiment increases the elastic modulus (K33) of the liquid crystal and decreases the dielectric anisotropy (Δε) to increase the threshold voltage, thereby reducing texture defects.

Hereinafter, Examples and Comparative Examples of the liquid crystal composition according to the above-described embodiment are disclosed.

<Example>

The display device shown in FIG. 3 was manufactured using the liquid crystal composition of Table 1 below.

liquid crystal compound Content (parts by weight)

20.5

22

3.5

6

5.5

11

14

17.5

<Comparative Example> A display device was manufactured in the same manner as in Example except that the liquid crystal composition of Table 2 was used.

liquid crystal compound Content (parts by weight)

25.5

12.7

10.5

12.5

16.8

22

The refractive index anisotropy, dielectric anisotropy, rotational viscosity, elastic modulus (K11, K33), and elastic modulus (K33)/dielectric anisotropy of the liquid crystal compositions prepared according to the aforementioned Comparative Examples and Examples were measured and shown in Table 3 below. In addition, the cell gap and phase difference of the liquid crystal panel are also shown.

Comparative example Example cell gap 2.95 3.15 Liquid crystal panel phase difference (nm) 319 325 Refractive index anisotropy (Δn) 0.1120 0.1066 permittivity anisotropy (Δε) -3.2 -3.3 Rotational viscosity (γ1) 121 118 Modulus of elasticity (K11) 14.9 14.2 Modulus of elasticity (K33) 12.3 16.5 Modulus of elasticity/permittivity anisotropy (K33/Δε) 3.84 5.00

Referring to Table 3, the elastic modulus (K33) of the liquid crystal composition according to the Example increased by about 4.2, and the elastic modulus/dielectric anisotropy (K33/Δε) of the liquid crystal composition according to the Comparative Example increased by about 1.16. A test using an electrostatic induced pad was performed on each of the display devices manufactured according to Examples and Examples, and the texture defect rates are shown in Table 4 below. In this case, the test was performed by rubbing the manufactured display device with an ODF (Oven Robot Arm) to which an electrostatic induction pad of polyimide was attached.

Comparative example Example Modulus of elasticity/permittivity anisotropy (K33/Δε) 3.86 5.00 Texture defect rate (%) 62.5 30.3

Referring to Table 4, the values of elastic modulus/dielectric anisotropy (K33/Δε) increased by 1.14 in the display device of the example, and the texture defect rate was decreased by 32.2%, compared to the comparative example. Here, an increase in the value of the elastic modulus/dielectric anisotropy (K33/Δε) indicates that the dielectric anisotropy (Δε) is decreased or the elastic modulus (K33) is increased. It can be seen that the liquid crystal composition according to the exemplary embodiment can significantly reduce texture defects by increasing the elastic modulus (K33) compared to the comparative example. As described above, the liquid crystal composition according to the exemplary embodiment has an elastic modulus (K33). ) and decrease the dielectric anisotropy (Δε) to increase the threshold voltage of the liquid crystal, thereby reducing texture defects.

Although the embodiments of the present invention have been described with reference to the accompanying drawings, those of ordinary skill in the art to which the present invention pertains can be implemented in other specific forms without changing the technical spirit or essential features of the present invention. You will be able to understand. Therefore, it should be understood that the embodiments described above are illustrative and non-limiting in all respects.

150: pixel electrode 160: first alignment layer
250: common electrode 260: second alignment layer
LC: liquid crystal RM: reactive mesogen

Claims (20)

With respect to 100 parts by weight of the total liquid crystal composition, each,
19.5 to 24.5 parts by weight of a liquid crystal compound represented by Formula 1;
3.5 to 8.5 parts by weight of a liquid crystal compound represented by Formula 2;
3 to 8 parts by weight of a liquid crystal compound represented by the following formula (3);
8.5 to 13.5 parts by weight of a liquid crystal compound represented by the following formula (4);
18 to 23 parts by weight of a liquid crystal compound represented by the following Chemical Formula 5;
1 to 6 parts by weight of a liquid crystal compound represented by the following formula (6);
11.5 to 16.5 parts by weight of a liquid crystal compound represented by the following formula (7); and
A liquid crystal composition comprising 15 to 20 parts by weight of a liquid crystal compound represented by the following Chemical Formula 8.
[Formula 1]

[Formula 2]

[Formula 3]

[Formula 4]

[Formula 5]

[Formula 6]

[Formula 7]

[Formula 8]

In Formulas 1 to 8,
X and Y are each independently an alkyl group or alkenyl group having 1 to 7 carbon atoms. The method of claim 1,
The liquid crystal compound represented by Formula 1 is a liquid crystal composition comprising a first liquid crystal compound in which X and Y are an alkyl group, and a second liquid crystal compound in which X is selected from an alkyl group or an alkenyl group and Y is the other one. The method of claim 2,
The content of the second liquid crystal compound is a liquid crystal composition comprising 18 to 36 parts by weight based on 100 parts by weight of the total liquid crystal compound represented by Formula 1. The method of claim 1,
A liquid crystal composition further comprising a compound represented by the following formula (9).
[Formula 9]

The method of claim 4,
The content of the compound represented by Formula 9 is 0.2 to 0.5 parts by weight based on 100 parts by weight of the total liquid crystal composition. The method of claim 1,
The liquid crystal composition has a phase difference (Δnd) of 310 to 350 nm of a liquid crystal panel, an elastic modulus (K33) of 15 to 18 pN, and a liquid crystal composition satisfying Equation 1 below.
[Equation 1]
6.95 ≤ Rotational viscosity (γ1) / Modulus of elasticity (K33) ≤ 7.35 The method of claim 6,
The liquid crystal composition has an elastic modulus (K11) of 13.5 to 15.5 pN. The method of claim 7,
The liquid crystal composition has a refractive index anisotropy (Δn) of 0.1064 to 0.1068. The method of claim 8,
The liquid crystal composition has a dielectric anisotropy (Δε) of -3.1 to -3.5. The method of claim 9,
The liquid crystal composition satisfies Equation 2 below.
[Equation 2]
4.3 ≤ modulus of elasticity (K33) / Ι permittivity anisotropy (Δε) Ι ≤ 5.6 a first substrate including a pixel electrode;
a second substrate including a common electrode; and
a liquid crystal layer interposed between the first substrate and the second substrate;
The liquid crystal layer is
For 100 parts by weight of the total liquid crystal composition, each,
19.5 to 24.5 parts by weight of a liquid crystal compound represented by Formula 1;
3.5 to 8.5 parts by weight of a liquid crystal compound represented by Formula 2;
3 to 8 parts by weight of a liquid crystal compound represented by the following formula (3);
8.5 to 13.5 parts by weight of a liquid crystal compound represented by the following formula (4);
18 to 23 parts by weight of a liquid crystal compound represented by the following Chemical Formula 5;
1 to 6 parts by weight of a liquid crystal compound represented by the following formula (6);
11.5 to 16.5 parts by weight of a liquid crystal compound represented by the following formula (7); and
A display device comprising a liquid crystal composition comprising 15 to 20 parts by weight of a liquid crystal compound represented by the following Chemical Formula 8.
[Formula 1]

[Formula 2]

[Formula 3]

[Formula 4]

[Formula 5]

[Formula 6]

[Formula 7]

[Formula 8]

In Formulas 1 to 8,
X and Y are each independently an alkyl group or alkenyl group having 1 to 7 carbon atoms. The method of claim 11,
The liquid crystal compound represented by Formula 1 includes a first liquid crystal compound in which X and Y are an alkyl group, and a second liquid crystal compound in which X is selected from an alkyl group or an alkenyl group and Y is the other one. The method of claim 12,
The content of the second liquid crystal compound is 18 to 36 parts by weight based on 100 parts by weight of the total liquid crystal compound represented by the formula (1). The method of claim 11,
A display device further comprising a compound represented by the following formula (9).
[Formula 9]

The method of claim 14,
The content of the compound represented by Formula 9 is 0.2 to 0.5 parts by weight based on 100 parts by weight of the total liquid crystal composition. The method of claim 11,
The liquid crystal composition has a phase difference (Δnd) of 310 to 350 nm of the liquid crystal panel, an elastic modulus (K33) of 15 to 18 pN, and a display device satisfying Equation 1 below.
[Equation 1]
6.95 ≤ Rotational viscosity (γ1) / Modulus of elasticity (K33) ≤ 7.35 The method of claim 16,
The liquid crystal composition has an elastic modulus (K11) of 13.5 to 15.5 pN. The method of claim 17,
The liquid crystal composition has a refractive index anisotropy (Δn) of 0.1064 to 0.1068. The method of claim 18,
The liquid crystal composition has a dielectric anisotropy (Δε) of -3.1 to -3.5. The method of claim 19,
The liquid crystal composition is a display device satisfying Equation 2 below.
[Equation 2]
4.3 ≤ modulus of elasticity (K33) / Ι permittivity anisotropy (Δε) Ι ≤ 5.6

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