KR20190030842A - Monomer containing reactive mesogens for photoaligning liquid crystal molecules, homogeneous aligning method of liquid crystal using it and liquid crystal display devices comprising the same - Google Patents

Abstract

The present invention relates to an aligning inducing type liquid crystal monomer having a photoreactive group, a method of horizontally aligning liquid crystals using the same, and a liquid crystal display device fabricated using the same. The present invention provides an aligning inducing type liquid crystal monomer having a photoreactive group which includes a chalcone or cinnamic central structure. Also, the present invention provides a method of producing excellent horizontal alignment of liquid crystals without forming a separate alignment layer, by injecting a mixture containing the liquid crystal monomer having photoreactivity and a liquid crystal material commonly used in display into liquid crystal cells; phase-separating the liquid crystal monomer having photoreactivity from the mixture based on irradiation with linearly polarized UV light to form anisotropic polymer layers on inner surfaces of upper substrates and lower substrates of the cells; and inducing the liquid crystal material to horizontally align in a single direction. In addition, the present invention provides a liquid crystal display device which has a response speed and electro-optical properties equivalent to conventional PI-IPS.

Description

TECHNICAL FIELD [0001] The present invention relates to an orientation-inducing liquid crystal monomer having a photoreactive group, a method of horizontally aligning liquid crystal using the same, and a liquid crystal display device manufactured thereby. BACKGROUND OF THE INVENTION [0001] SAME}

The present invention relates to an orientation-inducing liquid crystal monomer having a photoreactive group, a horizontal alignment method of the liquid crystal using the same, and a liquid crystal display device manufactured therefrom, and more particularly to a liquid crystal display comprising a center structure of chalcone or cinnamic Induced liquid crystal monomers having photoreactivity are uniformly aligned in all directions while being photopolymerized by UV light irradiation by linearly polarized light, Inducing type liquid crystal monomer having the photoreactivity and a conventional liquid crystal material are injected into a liquid crystal cell and irradiated with linearly polarized UV light from the outside, And a polymer layer on the inner surface of the upper substrate and the lower substrate of the liquid crystal material, The liquid crystal layer was stably phase-separated by the horizontally aligned liquid crystal layer to confirm the directionality of the excellent liquid crystal and the response speed and the electro-optical property equivalent to that of the conventional liquid crystal cell (PI-IPS) were realized without the polyimide (PI) , Orientation-induced liquid crystal monomers having photoreactive groups, horizontal alignment method of liquid crystal using the same, and liquid crystal display devices manufactured therefrom.

BACKGROUND ART A liquid crystal display (LCD) is thin and light and used for various purposes, and generally includes an array substrate including a pixel array, a counter substrate facing the array substrate, and a liquid crystal layer between the array substrate and the counter substrate, By arranging the liquid crystal molecules of the liquid crystal layer, the light transmittance is changed to display an image.

Recently, many techniques have been proposed in relation to the initial orientation of liquid crystal molecules in the liquid crystal display market.

In the case of a vertical alignment (VA) mode liquid crystal display device, the orientation film is essentially coated in order to arrange the initial liquid crystal direction perpendicular to the substrate.

The coating of the alignment layer is performed by a printing process, which may cause problems in uniformity in application of a large area, an increase in material cost due to a large amount of alignment film material, and an increase in energy cost since a high temperature process is essential.

In addition, since the liquid crystals have no directionality in the initial electric field, the concept of line inclination angle should be introduced. Polymer stabilization (PS) is indispensably required at this time. It is possible to improve the response speed, the direction of liquid crystal and the domain formation by passing through the PS step. In the vertical alignment mode, there is a problem of increase in cost due to the alignment film coating and the execution of the pre-sagging process.

On the other hand, there is a horizontal alignment mode in a liquid crystal display element alignment mode existing as a relative concept of vertical alignment mode. In order to arrange the liquid crystal horizontally in the horizontal alignment mode, the alignment film should be coated first and then thermally stabilized.

Further, in the horizontal alignment mode after the thermal stabilization, a rubbing process is performed to align the liquid crystal in a certain direction by scarring the alignment film in a certain direction.

As a most widely commercialized technique, an orientation method using a polyimide (PI) layer coating and a rubbing process has been applied. Such an orientation technique is applied to a substrate in accordance with the electrostatic problem, rubbing condition of the rubbing cloth, The problem of non-uniformity of orientation in some regions of the substrate remains as a problem to be solved.

In order to solve this problem, there have been reported a technique of mixing nano-sized rods in liquid crystal molecules, an orientation technique using hydrophobic molecules, and an orientation technique using a photo-curable reactive mesogen (RM).

However, it is still difficult to improve the directionality of the liquid crystal, and the response speed and the electro-optic properties of the cell (PI-IPS), which are produced by irradiating polarized UV after alignment film coating of polyimide There is a problem that is not met.

The present inventors have made efforts to improve the conventional problems, and as a result, they have found that when a photo-reactive orientation-inducing liquid crystal monomer including a central structure of chalcone or cinnamic is designed and the compound is irradiated with linearly polarized UV light And a uniform mixture of a liquid crystal monomer and an alignment liquid crystal monomer used in a display is injected between the upper substrate and the lower substrate, Thereby completing the present invention by confirming the directionality of excellent liquid crystal and the response speed and electro-optical property equivalent to that of the conventional PI-IPS.

1. Korean Patent No. 1060829 (Aug. 24, 2011) 2. Korean Patent Publication No. 2016-0101193 (2016.08.24) 3. International Patent Publication No. WO2011-115338 (Sep. 14, 2010)

1.Masanobu Mizusaki, Hiroshi Tsuchiya & Kiyoshi Minoura, LIQUID CRYSTALS, 2017, 44, 1-8.

An object of the present invention is to provide an alignment-inducing liquid crystal monomer having a photoreactive group which is excellent in dispersibility when mixed with a conventional liquid crystal material used in a display, and which realizes homogeneous horizontal alignment property over all regions while being photopolymerized by linearly polarized UV light .

Another object of the present invention is to provide a horizontal alignment method of a liquid crystal using the orientation-induced liquid crystal monomer having the photoreactive group.

It is another object of the present invention to provide a liquid crystal display device in which horizontal alignment of liquid crystal is realized by using orientation-induced liquid crystal monomers having a photoreactive group.

In order to achieve the above object, the present invention provides an orientation-inducing liquid crystal monomer having a photoreactive group represented by the following formula 1:

Equation 1

A-B-C-D-X-Y-Z-Y'-X'-D'-C'-

In the above, A and A 'is a functional group capable of polymerization, each _{independently, CH 2 = CH-, CH 2} = CCl-, CH 2: C (CH 3) -, 4- vinylphenyl (4-vinylphenyl), acrylic acrylate, methacryl, vinyl ether, oxetane, epoxy or thiol-ene groups, and the term "

B and B 'each independently represent -COO-, -O-, -CONH-, -S- or NH, which is a group connecting the functional group A (or A') capable of polymerization and the spacer C (or C ' ,

C and C 'are each independently a spacer represented by - (CH ₂ ) _n - (wherein n is an integer between 1 and 20)

D and D 'are each independently a linking group selected from -O-, -S-, -COO- or -OCO-,

X and X 'each independently represent a substituted or unsubstituted 1,4-phenylene group or a trans-1,4-cyclohexanyl group, Substitution is accomplished by substitution with one or more substituents selected from the group consisting of methyl, ethyl, CN, F, Cl and Br

Y and Y 'are each independently _{-CH 2 -CH 2 -, -CH 2} O-, -OCH 2 -, -OCO-, -COO-, -N = N-, -C = C-, -C = C- and -C = N-, and R <

Z is a chalcone represented by the following formula (2) or a cinnamic central structure represented by the formula (3).

(2)

(3)

Wherein L ₁ to L ₈ are each independently selected from hydrogen, alkyl having 1 to 6 carbon atoms or alkoxy, Cl or F;

The liquid crystal monomer of the present invention has a property of horizontally aligning the liquid crystal in a direction perpendicular to the polarization direction of linearly polarized UV light and has a liquid crystal phase at 25 to 180 ° C.

Accordingly, the present invention is characterized in that a mixture containing the orientation-induced liquid crystal monomer having the photoreactive group and a conventional liquid crystal material is injected into a liquid crystal cell composed of an upper substrate and a lower substrate, and linearly polarized UV light is irradiated, Inducing type liquid crystal monomer having a photoreactive group is phase-separated to form a polymer layer on the inner surface of the upper substrate and the lower substrate of the cell, and the liquid crystal material is horizontally aligned in a single direction .

The weight ratio of the alignment-inducing liquid crystal monomer having a photoreactive group to the mixture is preferably 0.01 to 10 wt%, and the alignment-induced liquid crystal monomer having the photoreactive group may be included in a mixture form of one or more kinds.

Further, the present invention provides a liquid crystal display device in which the horizontal alignment of liquid crystal is realized according to the horizontal alignment method of liquid crystal described above.

INDUSTRIAL APPLICABILITY The present invention provides an orientation-induced liquid crystal monomer having a photoreactive group including a central structure of chalcone or cinnamic. It is therefore an object of the present invention to provide an orientation-induced liquid crystal monomer having a central structure of chalcone or cinnamic, It is possible to provide a method of horizontally aligning the liquid crystal using the horizontal alignment characteristic.

In addition, the present invention relates to a method for manufacturing a liquid crystal display device, which comprises mixing an orientation-induced liquid crystal monomer having a photoreactive group and a conventional liquid crystal material used in a display, injecting the liquid crystal cell into a liquid crystal cell and horizontally aligning the liquid crystal only by linearly polarized UV light, It is possible to provide a liquid crystal display device applicable to all liquid crystal driving information devices such as notebook computers.

Accordingly, the present invention can induce horizontal alignment of the liquid crystal without using a alignment film coating, a heat treatment, a rubbing process, or a polymer stabilization process for introducing a square crystal by using an orientation-inducing liquid crystal monomer having a photoreactive group.

In particular, the liquid crystal display according to the horizontal alignment method of the present invention is characterized in that a liquid crystal monomer having photoreactive properties is separated from a mixture containing a liquid crystal monomer having photoreactivity and a conventional liquid crystal material used for display by linearly polarized UV light irradiation, Thereby forming an anisotropic polymer layer on the inner surface of the upper substrate and the lower substrate of the cell and guiding the liquid crystal material to be horizontally aligned in a single direction so that the direction of the optical axis of the liquid crystal in the upper substrate and the lower substrate can be perfectly matched have. Therefore, it is possible to provide a liquid crystal display device that realizes a response speed and electro-optical property equivalent or superior to the conventional PI-IPS.

1 is a ¹ H NMR spectrum of an orientation-inducing liquid crystal monomer having a chalcone functional group of the present invention,
2 is a FT-IR result of an orientation-inducing liquid crystal monomer having a chalcone functional group of the present invention,
FIG. 3 is a phase transition diagram of the orientation-induced liquid crystal monomer having a chalcone functional group according to the present invention,
4 (a) is an isotropic phase at 150 DEG C, (b) is a nematic phase at 138 DEG C, (c) is an isotropic phase at 150 DEG C, ) Is a Smectic phase at 120 ° C, (d) is a crystalline phase at 25 ° C,
5 is an image of a polarizing microscope before and after polymerization by irradiation of UV light onto a CHRM-IPS cell using orientation-induced liquid crystal monomers having a chalcone functional group of the present invention,
6 is a ¹ H NMR spectrum of the orientation-induced liquid crystal monomer having a cinnamoyl functional group of the present invention,
FIG. 7 shows FT-IR results of the orientation-induced liquid crystal monomer having a cinnamoyl functional group of the present invention,
8 is a result of the phase transition of the orientation-induced liquid crystal monomer having a cinnamoyl functional group according to the present invention with temperature through DSC,
FIG. 9 is an image of a polarizing microscope according to a phase change of the orientation-inversion liquid crystal monomer having a cinnamoyl functional group of FIG. 8, wherein (a) is an isotropic phase at 190 ° C., (b) is a nematic phase at 140 ° C. c) is a Smectic phase at 95 ° C, (d) is a crystalline phase at 50 ° C,
10 is a result of the image before and after the polymerization by UV light irradiation a polarization microscope to CRM-IPS-type liquid crystal cell using inductively monomer orientation with the cinnamoyl functional group of the present invention,
11 schematically shows a cell manufacturing process of the present invention,
12 is a photograph of the inside surface of a substrate after irradiation of UV light with a CHRM-IPS cell using orientation-induced liquid crystal monomers having a chalcone functional group according to the present invention, wherein the left side is a cross section,
13 is an alignment image of the liquid crystal according to the irradiation time and the polarized UV light direction in the CHRM-IPS cell using the orientation-inducing liquid crystal monomer having the chalcone functional group of the present invention,
Figure 14 is a photograph showing an optical switch after the power is applied to the IPS-CHRM cell of the invention before,
And Figure 15 is the transmittance curve of the voltage applied to the CHRM IPS-type liquid crystal cell using inductively monomer orientation with the chalkon functional group of the present invention and IPS cells using a conventional orientation film,
FIG. 16 is a result of comparing and evaluating the response speeds of the IPS cell using the conventional alignment film and the CHRM-IPS cell using the alignment-inducing liquid crystal monomer having the chalcone functional group of the present invention.

Hereinafter, the present invention will be described in detail.

The present invention provides an orientation-inducing liquid crystal monomer having a photoreactive group represented by the following formula (1).

Equation 1

A-B-C-D-X-Y-Z-Y'-X'-D'-C'-

In the above, A and A ', B and B, C and C', D and D ', X and X' and Y and Y 'are as defined above and Z is chalcone ) Or a cinnamic central structure represented by the general formula (3).

(2)

(3)

L ₁ to L ₈ are each independently selected from hydrogen, alkyl having 1 to 6 carbon atoms or alkoxy, Cl or F, preferably CH ₃ or C ₂ H ₅ .

The orientation-induced liquid crystal monomers having a photoreactive group according to the present invention are characterized in that the liquid crystal is oriented in a direction perpendicular to the polarization direction of linearly polarized UV light according to the characteristics of a chalcone or cinnamic central structure Orientation.

That is, the above-mentioned central structure has an isomer of trans-cis structure, and the isomerization of the trans-cis structure is activated by the linearly polarized UV light irradiation to increase the arrangement of the central structure in the direction perpendicular to the linearly polarized light, The polymerizable group is photopolymerized with the adjacent photoreactive liquid crystal compound and is tightly bound to improve the thermal and physical stability.

After being irradiated with linearly polarized UV light, the anisotropic polymer layer can be uniformly aligned in a row while being fixed to the trans structure while being cooled to room temperature.

Therefore, it is possible to adjust the horizontal alignment direction of the liquid crystal by adjusting the direction of the polarized UV used for photopolymerization.

The orientation-induced liquid crystal monomer having a photoreactive group is characterized by having a liquid crystal phase at 25 to 180 ° C. Specifically, it has a smectic phase at 27.2 to 130.2 ° C. during cooling and a nematic phase at 130.2 to 142.0 ° C. Phase transition property, and the orientation can be controlled by irradiating linearly polarized UV light at 27 to 130 DEG C for 1 to 30 minutes.

FIG. 3 is a graph showing the phase transition of the orientation-induced liquid crystal monomer having chalcone functional groups according to the temperature through DSC according to a preferred embodiment of the present invention, and FIG. 4 is an image of a polarization microscope according to the phase change of FIG. As a result, (a) shows the isotropic phase at 150 ° C, (b) shows the nematic phase at 138 ° C, (c) shows the smectic C phase at 120 ° C, Phase transition behavior.

FIG. 5 is an image of a polarizing microscope before and after polymerization by irradiation of UV light on a CHRM-IPS cell using orientation-induced liquid crystal monomers having a chalcone functional group of the present invention, wherein (a) Nematic LC phase, which means randomly arranged liquid crystals. On the other hand, (b) shows the image after irradiation with linearly polarized UV light. (C) a case in which the polarizing plate is observed in the direction of 45 degrees with the polarizing plate after being irradiated with linearly polarized UV light, and is observed in the highest transmissive state, so that the liquid crystal material is completely Dark or bright state is observed, which means that uniform horizontal alignment of the liquid crystal is being performed.

Accordingly, the present invention is characterized in that a mixture containing the orientation-induced liquid crystal monomer having the photoreactive group and a conventional liquid crystal material is injected into a liquid crystal cell composed of an upper substrate and a lower substrate, and linearly polarized UV light is irradiated, Inducing type liquid crystal monomer having a photoreactive group is phase-separated to form a polymer layer on the inner surface of the upper substrate and the lower substrate of the cell, and the liquid crystal material is horizontally aligned in a single direction .

FIG. 11 schematically shows a manufacturing process of a cell of the present invention, and does not include a coating film of a separate polyimide layer.

Therefore, the liquid crystal horizontal alignment method of the present invention can induce the alignment of the liquid crystal without coating the alignment layer, heat treatment, rubbing process, or polymer stabilization process for introducing the square.

In the horizontal alignment method of liquid crystal according to the present invention, it is preferable that the mixture contains 0.01 to 10% by weight of the orientation-induced liquid crystal monomer having photoreactivity. When the mixing ratio is less than 0.01% by weight , Orientation is not induced or the light irradiation time is prolonged. If it exceeds 10% by weight, the orientation-induced liquid crystal monomer having photo-reactivity that is phase-separated or unreacted remains as an impurity, there is a problem.

FIG. 12 is a photograph of the inside surface of the substrate after irradiating UV light linearly directed to the CHRM-IPS cell using the orientation-induced liquid crystal monomer having the chalcone functional group, and the left side shows a cross section and the right side shows a surface photograph. Through these cross-sectional and surface photographs, we can see formation of a thin polymer layer on the inner surface of the substrate, which is formed on both the upper and lower substrates and acts as the alignment layer in the LC cell.

Therefore, in the horizontal alignment method of liquid crystal of the present invention, a mixture containing an alignment-inducing liquid crystal monomer having a photoreactive group and a conventional liquid crystal material is injected into a liquid crystal cell composed of an upper substrate and a lower substrate and irradiated with linearly polarized UV light , Alignment-induced liquid crystal monomers having a photoreactive group are aligned in the direction of the inner surface of the upper substrate and the lower substrate while being polymerized by the irradiation, and are adsorbed on the substrate, so that they are naturally disposed on the substrate without any physical or chemical external force. Therefore, it is possible to provide an alignment force to the liquid crystal only by polarized UV light irradiation.

In addition, the alignment-induced liquid crystal monomer having the photoreactive group of the present invention can be thermally and physically stable because the alignment-induced liquid crystal monomer is tightly bound to the adjacent photoreactive group. In particular, the direction of the horizontal alignment of the liquid crystal can be adjusted by adjusting the direction of the polarized UV light used for photopolymerization.

13 is a view showing the orientation time of the UV light and the alignment image of the liquid crystal according to the polarized UV light direction in the CHRM-IPS cell using the orientation-induced liquid crystal monomer having the chalcone functional group of the present invention, and the linearly polarized UV light is irradiated for 3 to 10 minutes It is possible to control the horizontal orientation of the liquid crystal.

Specifically, linearly polarized UV light achieves horizontal alignment by performing light of 365 nm at 10.0 mW / cm 2 intensity at 95 ° C for 1 to 10 minutes, more preferably for 3 minutes in the embodiment of the present invention. Therefore, the time can be remarkably shortened compared to the non-patent article 1 (28 minutes at 3.0 mW / cm 2).

These results show that the orientation-induced liquid crystal monomer having the photoreactive group of the present invention has a liquid crystalline property and thus has high solubility with a common liquid crystal material mixed together and maximizes the rate of phase separation resulting from trans-cis isomerization due to light irradiation , The anchoring energy for capturing the liquid crystal is high, so that it is possible to achieve excellent liquid crystal alignment in a short time.

Further, according to the above-described horizontal alignment method of liquid crystal

An upper substrate and a lower substrate,

A polymer layer aligned in a row on the inner surface of the upper substrate and the lower substrate by polymerizing the alignment-inducing liquid crystal monomer having photoreactivity;

And a liquid crystal layer disposed between the upper substrate and the lower substrate such that the liquid crystal material is horizontally aligned in a single direction. A liquid crystal display device in which horizontal alignment of liquid crystal is realized by adjusting the direction of linearly polarized UV light is provided.

FIG. 14 is a photograph showing the optical switching of the CHRM-IPS cell according to the present invention before and after the power supply, wherein the CHRM-IPS cell according to the polarized UV light irradiation exhibits an electro-optic switching behavior.

In addition, in FIGS. 15 and 16 , the CHRM-IPS cell using the orientation-inductive liquid crystal monomer having the chalcone functional group of the present invention was evaluated and compared with that of conventional PI-IPS cells using polyimide. As a result, The liquid crystal alignment is stably exhibited by forming the polymer layer in a line by aligning the photoreactive liquid crystal compound stably in the direction of the surface inside the upper substrate and the lower substrate, It can be confirmed that it realizes physical properties.

Hereinafter, the present invention will be described in more detail with reference to Examples.

The present invention is intended to more specifically illustrate the present invention, and the scope of the present invention is not limited to these embodiments.

Example 1 Preparation of orientation-induced liquid crystal monomer (CHRM) having chalcone functional group 1

Step 1: Synthesis of 4- (6-acryloyloxyhexyloxy) benzoic acid (3)

16.6 g (0.1 mol) of 4-hydroxybenzoate were mixed with 4 g (0.12 mol) of NaOH and 300 ml of 2-butanone and 15 g (0.1 mol) of NaI and 15 g 0.12 mol) of 6-chlorohexanol was further added and the mixture was heated at 60 DEG C for 10 hours. After cooling, the solvent was removed using an evaporator, and the remaining residue was washed with 300 ml of 0.4 M NaOH and extracted with ether several times to obtain compound (1).

The above compound (1) was added to 300 ml of 0.5 M KOH solution and refluxed for 5 hours. The remaining 6-chlorohexanol was washed with several times of ether, neutralized with hydrochloric acid, The precipitate was recrystallized from ethanol to give compound (2).

To a 500 ml flask was added 22.8 g (0.1 mol) of compound (2) and 13.9 g (0.11 mol) of N, N-dimethylaniline dissolved in 230 ml of 1,4-dioxane, 0.11 mol) was slowly added thereto to arc chloride (acryloyl chloride), and after the pouring ends in water after 2 hours and filtered to recrystallization of the obtained compound (3) with 2-propanol ^{(yield:. 50% 1 h NMR (} 400 MHz _{, DMSO-d 6) δ 12.59} (s, 1H), 7.91-7.83 (d, 2H), 7.03-6.95 (d, 2H), 6.32 (dd, J = 17.2, 2.0 Hz, 1H), 6.17 (dd, J = 17.1, 10.2 Hz, 1H ), 5.93 (dd, J = 10.3, 1.7 Hz, 1H), 4.07 (dt, J = 31.0, 6.6 Hz, 4H), 1.73 (m, J = 6.8 Hz, 2H), 1.64 (m, J = 5.2 Hz, 2H), 1.42 (m, J = 18.9, 11.8, 9.0, 5.3 Hz, 4H).

Step 2: Synthesis of 4,4'-dihydroxy chalcone (4)

4-Hydroxyacetophenone (3.87 mmol), 0.473 g of 4-hydroxybenzaldehyde (3.87 mmol) and 5 mL of ethanol were added to a 25 mL round-bottomed flask and HCl gas was blown into the flask And reacted by ultrasonic at 30 캜 for 30 minutes. The resulting solid was filtered, washed with distilled water and dried in a vacuum oven at 40 ° C for 24 hours. The solids were dissolved in ethanol and then redissolved in distilled water. The obtained solid was dried in a 60 ° C. vacuum oven for 24 hours to obtain a white solid (yield 92%, ¹ H NMR (400 MHz, DMSO-d ₆ ) δ 10.23 , 2H), 8.09-8.00 (m, 2H), 7.75-7.58 (m, 4H), 6.94-6.79 (m, 4H).

Step 3: Synthesis of 4,4 '- (6-Acryloyloxyhexyloxy) benzoate chalcone (3)

To a 50 ml round-bottom flask was added 0.877 g (3 mmol) of 4- (6-acryloyloxyhexyloxy) benzoic acid (3), 0.721 g (3 mmol) of 4,4'- dihydroxy chalcone (4) and 0.0367 g 4-dimethylaminopyridine (DMAP) and 25 mL of dichloromethane were mixed. After ice-cooling, 0.680 g (3.3 mol) of N, N'-dicyclohexylcarbodiimide (DCC) was added with stirring. After stirring at room temperature for 20 hours, the solid was filtered off and the solvent was distilled off under reduced pressure to obtain a yellow solid. And purified using the following liquid chromatography (EA: DCM: Pet = 1.2: 10: 10). To obtain a white solid in a yield of ^{63% (1 H NMR (400} MHz, Chloroform-d): δ 8.15 (d, J = 8.5 Hz, 2H), 7.96 (d, J = 8.8 Hz, 4H), 7.81 (d J = 16.0 Hz, 1H), 7.55 (d, J = 16.5 Hz, 2H), 7.33 (d, J = 15.6 Hz, 1H), 7.26 (Dt, J = 6.6, 2H), 6.41 (d, J = 17.4 Hz, 2H), 6.13 2.1 Hz, 4H), 4.03 (dt, J = 17.1, 6.4 Hz, 4H), 1.92-1.64 (m, 8H), 1.60-1.38 (m, 8H).

≪ Examples 2 to 5 > Preparation of orientation-induced liquid crystal monomer (CHRM) having chalcone functional groups 2 to 5

Based on the following Table 1 , the reactive group was changed to prepare orientation-induced liquid crystal monomers having chalcone functional groups.

Example 6 Preparation of orientation-induced liquid crystal monomer (CRM) having cinnamoyl functional group 1

Step 1: Synthesis of 4- (tetrahydro-2H-pyran-2-yloxy) phenol (4)

(0.1 mmol) of hydroquinone, 0.951 g (5 mmol) of toluene-4-sulphonic acid and 100 ml of ether and 9.5 ml (0.1 mol) of 3,4-dihydro- And stirred for 30 minutes to prepare a mixture. After stirring, the mixture was further stirred at room temperature for 2 hours, and then filtered while injecting nitrogen gas. Washed twice with 60 mL of a 2 M aqueous NaOH solution and the aqueous solution was collected. Lt; RTI ID = 0.0 > 0-5 C < / RTI > Then 0.5 g of sodium bicarbonate was added to the solution and neutralized with 6.4 ml of acetic acid. The filtered crude compound was washed with 60 ml of water and dried in an oven. The crude compound is chromatographed (EA: Pet = 1: 2 ) was isolated to yield a white powder (4) ^{(yield:. 35% 1 H NMR (} 400 MHz, Chloroform- d) δ 7.01-6.88 (d, 2H), 6.77-6.64 ( d, 2H), 5.44-5.29 (s, 1H), 5.29 (t, J = 3.4 Hz, 1H), 3.96 (dd, J = 12.1, 9.0, 3.2 Hz, 1H ), 3.61 (dd, J = 11.1,2.8, 1.6 Hz, 1H), 2.07-1.89 (m, 2H), 1.93-1.77 (m, 2H), 1.76-1.62 (m, 2H).

Step 2: Synthesis of 4-hydroxyphenyl 4- (6-acryloyloxyhexyloxy) benzoate (6)

5.847 g (20 mmol) of 4- (6-acryloyloxyhexyloxy) benzoic acid (3) and 3.885 g (20 mmol) of 4- (tetrahydro-2H- pyran-2-yloxy) phenol obtained in step 1 of Example 1 4), 0.244 g (2 mmol) of 4-dimethylaminopyridine (DMAP) and 55 ml of dichloromethane was cooled with ice, and 4.54 g (22 mmol) of N, N'-dicyclohexylcarbodi (DCC) was added and stirred. After stirring at room temperature for 20 hours, the mixture was filtered through a pad of silica gel and the solvent was evaporated off to give the crude compound (5). The compound (5) was a clean oil phase and allowed to stand overnight to cure. Recrystallization from ethanol gave a white solid compound (5), and 0.251 g (1 mmol) of pyridinium 4-toluenesulfonate (PPTS) were mixed with 50 ml of ethanol. The mixture was heated at 60 DEG C for 4 hours to obtain a clear solution, to which 180 g of cold water was poured to obtain a solid to give a solid crystal. By filtration and the crystals were washed with water and dried in an oven to give the compound (6) of a white powder ^{(yield:. 75% 1 H NMR (} 400 MHz, DMSO-d 6) δ 9.48 (s, 1H), 8.03 ( d, J = 9.0 Hz, 2H ), 7.13-6.96 (m, 4H), 6.86-6.75 (d, 2H), 6.34 (dd, J = 17.2, 2.0 Hz, 1H), 6.17 (dd, J = 17.4, 10.3 Hz, 1H), 5.93 ( dd, J = 10.3, 1.5 Hz, 1H), 4.10 (dt, J = 15.7, 6.4 Hz, 4H), 1.76 (p, J = 6.5 Hz, 2H), 1.65 (p, J = 6.9 Hz, 2H), 1.52-1.33 (m, 4H).

Step 4: Synthesis of 4- (6-hydroxyhexyloxy) cinnamic acid (7)

1.642 g (10 mmol) of 4-hydroxycinnamic acid was dissolved in 15 ml of ethanol. Then, 1.683 g (30 mmol) of KOH and 0.166 g (1 mmol) of KI were dissolved in 5 ml of water and added dropwise. After the mixed solution was heated at 80 캜 for 10 minutes, 1.708 g (12 mmol) of 6-chlorohexanol was added dropwise to the mixed solution, and the mixture was stirred at 80 캜 for 48 hours. The mixed solution was then poured into water and extracted with ether. The aqueous phase was collected and neutralized with hydrochloric acid until it became weak acid. To give the compound (7) of the filtration of the crude compound of a crystallized white, washed twice with water, dried and recrystallized with ethanol in an oven white powder ^{(yield:. 67% 1 H NMR (} 400 MHz, DMSO- d 6) δ 12.23 (s, 1H), 7.67-7.50 (m, 3H), 6.99-6.92 (d, 2H), 6.37 (d, J = 15.9 Hz, 1H), 4.37 (s, 1H), 4.00 (t, J = 6.5 Hz, 2H), 3.39 (d, J = 6.4 Hz, 2H), 1.81-1.65 (m, 2H), 1.43 (dtd, J = 13.3, 7.6, 7.2, 3.9 Hz, 4H), 1.40-1.29 m, 2H).

Step 5: Synthesis of 4- (6-acryloyloxyhexyloxy) cinnamic acid (8)

1.586 g (6 mmol) of compound (7) and 0.873 g (7.2 mmol) of N, N-dimethylphenol were dissolved in 15 ml of 1,4-dioxane. To avoid undesired thermal polymerization, 2,6- -tert-butyl-4-methylphenol was added in small amounts. The reaction solution was heated to 65 DEG C with stirring and 0.732 g (7.2 mmol) of acroyl chloride was added dropwise to the solution. The mixed solution was heated at 65 DEG C for 3 hours, cooled, and water was poured into the clear solution obtained. The crystalline compound was filtered off with crystallized white, washed with water and dried. The crude compound was recrystallized with ethanol to give a white powder (8) ^{(yield:. 64% 1 H NMR (} 400 MHz, Chloroform- d) δ 7.74 (d, J = 16.0 Hz, 1H), 7.55-7.46 (d, 2H), 6.95-6.86 ( d, 2H), 6.45-6.27 (m, 2H), 6.12 (dd, J = 17.3, 10.4 Hz, 1H), 5.82 (dd, J = 10.4, 1.6 Hz, 1H ), 4.18 (t, J = 6.6 Hz, 2H), 4.00 (t, J = 6.4 Hz, 2H), 1.82-1.65 (m, 4H), 1.58-1.39 (m, 4H).

Step 6: Synthesis of 4- (6-acryloyloxyhexyloxy) benzoyloxy 4- (6-acryloyloxyhexyloxy) cinnamate (CRM)

A mixture of 1.154 g (3 mmol) of compound (6), 0.955 g (3 mmol) of compound (8), 0.0367 g (0.3 mmol) of 4-dimethylaminopyridine (DMAP) and 25 ml of dichloromethane was placed in an ice bath And 0.680 g (3.3 mol) of N, N'-dicyclohexylcarbodiimide (DCC) was added and stirred. After stirring for 20 minutes, the mixture was filtered and the solvent removed to give the crude solid compound as a white solid. The crude compound is chromatographed (EA: DCM: Pet = 1 : 5: 10) is isolated and purified using to give a CRM is the final target compound as a white powder ^{(yield:. 76% 1 H NMR (} 400 MHz , Chloroform- d): δ 8.14 ( d, J = 8.8 Hz, 2H), 7.83 (d, J = 16.0 Hz, 1H), 7.54 (d, J = 8.5 Hz, 2H), 7.34-7.18 (m, 4H ), 6.95 (dd, J = 18.4, 8.6 Hz, 4H), 6.50 (d, J = 15.6 Hz, 1H), 6.41 (d, J = 17.4 Hz, 1H), 6.13 (dd, J = 17.3, 10.5 Hz J = 6.6, 2.1 Hz, 4H), 4.03 (dt, J = 17.1, 6.4 Hz, 4H), 1.92-1.64 (m, 2H), 5.83 (d, J = 10.5 Hz, 8H), 1.60-1.38 (m, 8H).

Examples 7 to 10 Preparation of orientation-inducing liquid crystal monomer (CRM) having cinnamoyl functional groups 2 to 5

Based on the following Table 2 , the reactive groups were changed to prepare orientation-induced liquid crystal monomers having cinnamoyl functional groups.

≪ Example 11 > CHRM-IPS (In-Plane Switching) cell fabrication

(CHNM) having a chalcone functional group prepared in Example 1 and a conventional liquid crystal material (Merck, T _NI = 74.5, DELTA epsilon = -3.2, n = 0.109) CHRM-LC mixture was prepared by mixing in a ratio of 99: 1, maintained for 5 minutes on a 75-ultrasonic shaker for 30 minutes, and kept in a 95 oven for 30 minutes for uniform mixing.

IPS cell fabrication was performed by assembling an IPS glass substrate and an upper glass substrate such that a cell spacing of 5 탆 was maintained, and the IPS glass substrate was a main electrode structure having a pixel electrode and a common electrode (w = 8 탆, l = 8 탆) , And the upper glass substrate is an electrode-free plate glass. The CRM-IPS cell was fabricated by injecting the CHRM-LC mixture into the IPS cell at 95 by capillary action. The linearly polarized UV light was then exposed to the CHRM-LC cell at 95 for 4 minutes, where the UV light source was UHH MT 1000-FF and the exposed polarized UV light was 10 mW cm ^-2 at 365 nm. The fabrication of the CHRM-LC cell is shown in Fig.

≪ Comparative Example 1 > PI-IPS cell fabrication

In order to compare the electro-optical properties of the CHRM-LC cell of Example 11, polyimide (AL-16470 manufactured by JSR Corporation) was rubbed in a conventional IPS cell to produce a PI-IPS cell.

The polyimide-coated IPS substrate and the glass substrate were subjected to rubbing treatment in an axial direction with a velvet cloth and the cell gap between the upper substrate and the upper substrate was adjusted to 5 μm by fixing the rubbing direction at 80 ^° with respect to the electrode direction . At this time, it was injected into the PI-IPS cell at 95 by capillary action using a conventional liquid crystal (LC) material not containing a CHRM monomer.

≪ Experimental Example 1 > Optical analysis of liquid crystal monomers

The synthesis of the orientation-induced liquid crystal monomer having chalcone functional group prepared in Example 1 was confirmed by ¹ H NMR and FT-IR spectroscopic methods.

In the ¹ H NMR spectrum of FIG. 1, the proton peak corresponding to the orientation-induced liquid crystal monomer having the chalcone functional group prepared in Example 1 was confirmed, that is, the peak at 5.8-6.5 ppm corresponds to the terminal acrylate functional group , And the peak of 1.3-2.0 ppm (m) was confirmed as the proton peak of the alkyl group and the alkyl spacer was present. Also, the peaks at 7.3 and 7.8 ppm (d) correspond to the chalcone group, and the peaks at 8.1, 7.9, 7.5 and 6.9 ppm (d) confirm the presence of the CRM core unit as identified as aromatic proton peaks .

In the FT-IR spectrum of FIG. 2, 1726 and 1632 cm ^-1 peaks correspond to the conjugated C = O and CH = CH peaks, respectively, from which the presence of a chalcone group in the core unit is supported. Also, the peak of 2893 cm ^-1 observed together over 2941 cm ^-1 was the saturated CH stretching absorption peak corresponding to the alkyl spacer, and the peak observed at 1406-1609 cm ^-1 confirmed the C = C stretching band of the aromatic ring.

From the above spectroscopic results, the synthesis of the orientation-induced liquid crystal monomer having the chalcone functional group of Example 1 was confirmed.

<Experimental Example 2> Phase transition and thermal evaluation of liquid crystal monomers

The alignment-induced liquid crystal monomer having chalcone functional group prepared in Example 1 and the alignment-induced liquid crystal monomer having cinnamoyl functional group prepared in Example 6 were measured using a thermal parallax analyzer (TA Instruments Inc, USA, DSC) The results are shown in Table 3, and FIG. 3 shows the result of phase transitions according to temperature of the orientation-induced liquid crystal monomer having a chalcone functional group by DSC.

From the result of the phase transition temperature measurement of the DSC, the orientation-induced liquid crystal monomer having the chalcone functional group prepared in Example 1 showed a smectic phase between 65.2 and 131.8 ° C and exhibited a smectic phase at 131.8 to 143.9 ° C And showed a nematic phase. On the other hand, during the cooling process, the nematic phase appears at 142.0-130.2 ° C and the smectic phase follows 130.2-27.2 ° C.

The phase transition behavior of the orientation-induced liquid crystal monomer having the above-mentioned chalcone functional group can be confirmed by a polarizing microscope image.

As shown in FIG. 4, (a) shows an isotropic phase at 150 ° C, and (b) shows a planar orientation with a nematic phase at 138 ° C. (c) shows the texture of a typical fan shape at 120 ° C, and (d) shows the crystalline phase at 25 ° C. As a result of evaluation of the thermal properties of the orientation-induced liquid crystal monomer having a chalcone functional group, it means decomposition of an ester group present in the monomer at a primary decomposition temperature of 285 DEG C, and the decomposition of the aryl group in a monomer chain at a secondary decomposition temperature of 421 DEG C. [ Indicating weight loss due to decomposition of alkyl-ether groups.

In addition, orientation-induced liquid crystal monomers having a cinnamoyl functional group prepared in Example 6 exhibited a similar tendency, showing a smectic C phase between 86.8 and 102.6 ° C and exhibiting a smectic C phase at a temperature of 102.6 to 177.4 ° C Showed a nematic phase. On the other hand, during the cooling process, the nematic phase appeared at 175.2 ~ 97.5 ℃ and the Smectic C phase showed 97.5 ~ 57.9 ℃.

<Experimental Example 3> Orientation evaluation of CRM-IPS cell

FIG. 5 is a photograph of a polarizing microscope before and after irradiation of UV light on a CHRM-IPS cell using an orientation-inducing liquid crystal monomer having a chalcone functional group of the present invention, wherein (a) shows a nematic LC , Which means randomly arranged liquid crystals.

On the other hand, in (b), the polarizing plate was positioned and observed in the same direction as the polarized direction irradiated after the polarized UV light, and the image was completely dark. (C) As a result of observation in the direction of the arrow, the highest transmission state was observed.

From the results of FIGS. 5 (b) and 5 (c), it can be observed that the polarized UV light is completely dark or bright without disorder of the liquid crystal material after the irradiation, Means that the polymer in which the orientation-induced liquid crystal monomer having a functional group is polymerized is uniformly aligned in the horizontal direction of the liquid crystal.

11 schematically shows a manufacturing process of a cell according to the present invention. The alignment-induced liquid crystal monomer having a photoreactive group of the present invention has excellent compatibility with a conventional liquid crystal material used in a host display, The cell was irradiated with polarized UV light at 95 [deg.] C set above the T _NI temperature to avoid decomposition of the initial polarized UV light from the liquid crystal material.

When the polarized UV light is absorbed, the alignment-induced liquid crystal monomer having chalcone functional groups is phase-separated from the mixed liquid crystal material to form a polymer layer on the inner surface of the substrate. In this process, the orientation-induced liquid crystal monomer having chalcone functional groups A polymer layer having surface anisotropy was formed due to isomerization phenomenon. During the subsequent cooling to room temperature, the liquid crystal material was arranged by interaction between the optically aligned polymer layers due to the liquid crystal material and the orientation-induced liquid crystal monomer having the photoreactive group.

Thus, after irradiating the polarized UV light, the inner surface of the cell was photographed with a scanning electron microscope (SEM) to confirm whether or not a polymer layer was formed on the inner surface of the substrate.

12 is a photograph of a surface inside the substrate after irradiating polarized UV light to a CHRM-IPS cell using an orientation-inducing liquid crystal monomer having a chalcone functional group of the present invention, the left side being a cross-sectional photograph and the right side being a surface photograph.

As a result, a thin polymer layer was formed on the inner surface of the substrate through cross-section and surface photographs. In addition, the same arrangement as the initial state was confirmed even after the liquid crystal material was injected again onto the removed substrate at 95 캜 and cooled again at room temperature. From these results, it was confirmed that the polymer layer was formed on both the upper and lower substrates and operated as an alignment layer in the LC cell.

<Experimental Example 4> Electrical-optical property evaluation of CHRM-IPS cell

The electro-optical properties of the CHRM-IPS cell prepared in Example 11 and the PI-IPS cell using the conventional polyimide alignment layer of Comparative Example 1 were evaluated and compared.

Fig. 13 shows an alignment image of liquid crystal according to irradiation time upon irradiation of polarized UV light to the CHRM-IPS cell of the present invention. As a result, it can be confirmed that uniform alignment of the liquid crystal occurs during light irradiation for three minutes or more.

FIG. 14 is a photograph showing optical switching in a CHRM-IPS cell before and after power is applied, in which the left side is 0 V and the right side is 8 V voltage. As a result, the CHRM-IPS cell according to the polarized UV light irradiation showed a favorable electro-optic switching behavior.

The orientation properties of the CHRM-IPS cell fabricated in Example 11 and the PI-IPS cell fabricated in the conventional polyimide alignment layer (rubbing) of Comparative Example 1 were evaluated and compared.

FIG. 15 is a graph showing a transmittance (V-T) curve according to the voltage application of the conventional PI-IPS cell and the CHRM-IPS cell using the alignment induction type liquid crystal monomer having the chalcone functional group of the present invention. These results indicate that the orientation capacity of the polymer layer oriented by the polarized UV light irradiation of the present invention and the conventional rubbing treated polyimide layer are the same.

In addition, as a result of evaluating the response time between the conventional PI-IPS cell and the CHRM-IPS cell of the present invention, as shown in FIG. 16, both cases showed the same result. From these results, the conventional PI-IPS cell and the CRM-IPS cell of the present invention showed the same electro-optic switching behavior.

Accordingly, the present invention provides a liquid crystal display device comprising a liquid crystal cell (CHRM-IPS or CRM-IPS) composed of an upper substrate and a lower substrate, and a liquid crystal material, By irradiating linearly polarized UV light, it is possible to induce the horizontal alignment of the liquid crystal without the alignment film coating and heat treatment, and the polymer stabilization process for the rubbing process or the introduction of the pre-exposure square.

As described above, the present invention provides a method of horizontally aligning liquid crystals by irradiating linearly polarized UV light to a mixture containing orientation-induced liquid crystal monomers having photo-reactivity and conventional liquid crystal materials used in displays.

Accordingly, the present invention does not require a rubbing process after coating a common polyimide (PI) as a conventional alignment method, which simplifies the manufacturing process and can reduce the manufacturing cost. In addition, compared with the optical alignment process used in recent years, a process such as pre-application of a photo alignment layer and production of a photo alignment layer is not required, and the manufacturing process is simple and the manufacturing cost is reduced. In addition, in the alignment method using the rubbing or general light alignment process, it is difficult to have a uniform orientation force in all regions of the substrate due to the abrasion state of the rubbing cloth, the electrode structure state of the substrate, and the mis- The liquid crystal is not aligned in some regions and light leakage occurs in the initial dark state. However, in the case of using the alignment-induced liquid crystal monomer having photoreactivity, the liquid crystal material is mixed with a conventional liquid crystal material, Since the alignment is induced by the irradiation, uniform horizontal alignment can be controlled over the entire area, and since the alignment directions of the upper and lower substrates can be exactly matched, a perfect dark state without initial light spots can be realized.

While the invention has been shown and described with reference to certain exemplary embodiments thereof, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention as defined by the appended claims.

Claims (7)

An orientation-inducing liquid crystal monomer having a photoreactive group represented by the following formula 1;
Equation 1
ABCDXYZ-Y'-X'-D'-C'-B'-A '
In the above, A and A 'is a functional group capable of polymerization, each _{independently, CH 2 = CH-, CH 2} = CCl-, CH 2: C (CH 3) -, 4- vinylphenyl (4-vinylphenyl), acrylic acrylate, methacryl, vinyl ether, oxetane, epoxy or thiol-ene groups, and the term &quot;
B and B 'each independently represent -COO-, -O-, -CONH-, -S- or NH, which is a group connecting the functional group A (or A') capable of polymerization and the spacer C (or C ' ,
C and C 'are each independently a spacer represented by - (CH ₂ ) _n - (wherein n is an integer between 1 and 20)
D and D 'are each independently a linking group selected from -O-, -S-, -COO- or -OCO-,
X and X 'each independently represent a substituted or unsubstituted 1,4-phenylene group or a trans-1,4-cyclohexanyl group, Substitution is effected with one or more substituents selected from the group consisting of methyl, CN, F, Cl and Br
Y and Y 'are each independently _{-CH 2 -CH 2 -, -CH 2} O-, -OCH 2 -, -OCO-, -COO-, -N = N-, -C = C-, -C = C- and -C = N-, and R &lt;
Z is a chalcone represented by the following formula (2) or a cinnamic central structure represented by the formula (3).
(2)

(3)

Wherein L ₁ to L ₈ are each independently selected from hydrogen, alkyl having 1 to 6 carbon atoms or alkoxy, Cl or F; The alignment-induced liquid crystal monomer according to claim 1, wherein the liquid crystal monomer aligns the liquid crystal in the vertical direction with respect to the polarization direction of the UV-ray that is linearly polarized. The orientation-induced liquid crystal monomer according to claim 1, wherein the liquid crystal monomer has a liquid crystal phase at 25 to 180 ° C. A liquid crystal cell comprising an orientation-inducing liquid crystal monomer having the above-mentioned photoreactive group and a conventional liquid crystal material is injected into a liquid crystal cell composed of an upper substrate and a lower substrate, and linearly polarized UV light is irradiated,
According to the above investigation, alignment-induced liquid crystal monomers having a photoreactive group from the mixture are phase-separated and aligned in a polymer layer on the inner surface of the upper substrate and the lower substrate of the cell, and a liquid crystal which induces the liquid crystal material to be horizontally aligned in a single direction Horizontal alignment method. The horizontal alignment method according to claim 4, wherein the weight ratio of the orientation-induced liquid crystal monomer having a photoreactive group to the mixture is 0.01 to 10% by weight. The horizontal alignment method according to claim 4, wherein the mixture contains at least one orientation-inducing liquid crystal monomer having a photoreactive group. According to the horizontal alignment method of liquid crystal according to any one of claims 4 to 6,
An upper substrate and a lower substrate,
A polymer layer aligned in a row and being formed by polymerizing orientation-induced liquid crystal monomers having photoreactivity on inner surfaces of the upper substrate and the lower substrate;
And a liquid crystal layer in which a liquid crystal material is horizontally aligned in a single direction between the upper substrate and the lower substrate.

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