KR102576512B1 - Polymer dispersed liquid crystal display and manufacturing method thereof - Google Patents

Abstract

The polymer dispersed liquid crystal display according to the present invention includes a first substrate, a first electrode on the first substrate, a second electrode on the first electrode, a second substrate on the second electrode, and between the first electrode and the second electrode. It may include an interposed liquid crystal layer. The liquid crystal layer may include a first region and a second region where liquid crystal droplets are distributed. The average size of liquid crystal droplets in the first area may be larger than the average size of liquid crystal droplets in the second area.

Description

Polymer dispersed liquid crystal display and manufacturing method thereof}

The present invention relates to polymer dispersed liquid crystal displays.

As modern society develops into a highly advanced information age, the importance of the display industry is increasing. Recently, as screen sizes have increased and screen thickness has decreased, flat panel displays (FPDs) such as liquid crystal displays (LCDs), display panels (PDPs), and organic electroluminescent displays (OLEDs) have been widely used.

In a typical liquid crystal display device, white light from the backlight is modulated as it passes through two polarizers and a liquid crystal layer, and the modulated light passes through a color filter to produce color.

These liquid crystal displays are widely used in mobile portable devices, laptops, computer monitors, TVs, etc. due to the advantages of low voltage operation and low power consumption. However, because they use polarizers and color filters to achieve high contrast ratio and color, they suffer from light loss. It is difficult to implement such a large and highly transparent display.

One technical object of the present invention is to provide a polymer dispersed display that has an opaque pattern when no driving voltage is applied and has a transparent window state when a driving voltage is applied.

Another problem that the present invention seeks to solve is to provide a method for manufacturing the polymer dispersed display.

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

The dispersed liquid crystal display of the present invention includes a first substrate, a first electrode on the first substrate, a second electrode on the first electrode, a second substrate on the second electrode, and an intermediate electrode disposed between the first electrode and the second electrode. The liquid crystal layer may include a first region and a second region in which liquid crystal droplets are distributed, and the average size of the liquid crystal droplets in the first region is the average size of the liquid crystal droplets in the second region. May be larger than average size.

The polymer dispersed display according to the present invention can have various patterns of light scattering effects when no driving voltage is applied.

Figure 1 is a conceptual diagram of a polymer dispersed liquid crystal display in a state where no driving voltage is applied.
Figure 2 is a conceptual diagram of a polymer dispersed liquid crystal display in a state in which a driving voltage is applied.
Figure 3 is a flowchart showing a manufacturing method of a polymer dispersed liquid crystal display.
4 to 6 are conceptual diagrams showing a method of manufacturing a polymer dispersed liquid crystal display.
Figures 7a to 7e show an embodiment of a polymer dispersed liquid crystal display from a plan view.

In order to fully understand the configuration and effects of the present invention, preferred embodiments of the present invention will be described with reference to the attached drawings. However, the present invention is not limited to the embodiments disclosed below, but can be implemented in various forms and various changes can be made. However, the description of the present embodiments is provided to ensure that the disclosure of the present invention is complete and to fully inform those skilled in the art of the present invention of the scope of the invention. In the attached drawings, the components are shown enlarged in size for convenience of explanation, and the proportions of each component may be exaggerated or reduced.

Unless otherwise defined, terms used in the embodiments of the present invention may be interpreted as meanings commonly known to those skilled in the art. Hereinafter, the present invention will be described in detail by explaining exemplary embodiments of the present invention with reference to the accompanying drawings.

Figure 1 is a conceptual diagram of a polymer dispersed liquid crystal display in a state where no driving voltage is applied.

Referring to FIG. 1, a first substrate 100 and a second substrate 200 may be provided that are spaced apart from each other. Both the first substrate 100 and the second substrate 200 may include transparent materials. As an example, the first substrate 100 and the second substrate 200 may include at least one of a single layer of glass or a transparent plastic film.

The first electrode 101 may be provided on one side of the first substrate 100 facing the second substrate 200 . A second electrode 201 may be provided on one side of the second substrate 200 facing the first substrate 100 .

Both the first electrode 101 and the second electrode 201 may include a transparent conductive material. As an example, the first electrode 101 and the second electrode 201 are made of indium tin oxide (ITO), indium zinc oxide (IZO), silver nanowire, aluminum, carbon nanotube (CNT), graphene, PEDOT:Pss, It may include a mixture containing at least one of polyaniline and polythiophene. Preferably, the first electrode 101 and the second electrode 201 may be made of indium tin oxide (ITO).

A liquid crystal layer 300 may be interposed between the first electrode 101 and the second electrode 201. The average thickness (T1) of the liquid crystal layer 300 may be 2.5 μm to 100 μm. The liquid crystal layer 300 may include a polymer 301 and a plurality of liquid crystal droplets 302 and 306.

The polymer 301 may include an ultraviolet curable polymer that is cured by ultraviolet rays. The ultraviolet curable polymer may be an amorphous, semicrystalline monomer, or oligomer.

Preferably, the ultraviolet curable polymer is urethane acrylate oligomer (molecular weight, 1000 to 4000), 2(2-ethoxyethoxy) ethyl acrylate (EOEOEA), isobornyl acrylate ( Isobornyl acrylate, IOBA), Triethylopropane triacrylate (TMPTA), Tri(propylene glycol) Diacrylate, TPGDA), Penthaerithritol Triacrylate, PETA), hydroxyethyl acrylate (HEA), Trimethylolpropane Ethoxylate Triacrylate (TMPEOTA), 2-phenoxyethyl acrylate (2-PEA) , Methyl methacrylate (MMA), Methacrylate (MA), tetrahydrofurfuryl acrylate, tripropylene glycol glycerolate diacrylate (Tri(propylene glycol) Glycerolate) Diacrylate, TPGDA), Vinylacrylate (VA), Ethylene glycol dimethacrylate (EGDA), Epoxy acrylate monomer or oligomer (Epoxy acrylate monomer or oligomer), Hexanediol diacrylate ( 1,6-hexandiol diacrylate (HAD), 2-hydroxyethyl methacrylate (2-HEMA), 2-ethylheyxyl acrylate, ethylene glycol diacrylate ( ethylene glycol diacrylate, Trimethylolpropane dially ether, urethane diacrylate, and 2-phenoxyethyl acrylate, Tetrahydrofurfuryl acrylate ) may include at least one of the following.

Each of the liquid crystal droplets 302 and 306 may have a sphere shape. The liquid crystal droplets 302 and 306 may have a weight ratio of 80 to 120 with respect to 100 weight of the polymer 301.

A plurality of liquid crystals may be provided within the liquid crystal droplets 302 and 306. Liquid crystals may have a thin and long rod shape. The flow viscosity (mm- ² /s) of the liquid crystal may be 20 to 100, the refractive index anisotropy may be 0.15 to 0.30, and the dielectric anisotropy (1.0 kHz) may be +2.0 to +40.0.

The liquid crystal layer 300 may include a plurality of first regions P1 and a plurality of second regions P2. A plurality of liquid crystal droplets 302 may be distributed in the first areas P1, and a plurality of liquid crystal droplets 306 may be distributed in the second areas P2.

The average size of the liquid crystal droplets 302 in the first area P1 may be larger than the average size of the liquid crystal droplets 306 in the second area P2. The number of liquid crystal droplets 302 distributed in the first area P1 per unit volume may be less than the number of liquid crystal droplets 306 distributed in the second area P2 per unit volume. Accordingly, the first area P1 may have greater transparency than the second area P2 and turbidity may be reduced.

A power source 400 capable of applying a driving voltage to the first electrode 101 and the second electrode 201 may be provided. In a state where no driving voltage is applied to the first electrode 101 and the second electrode 201, that is, in an open circuit 400a state, an electric field is generated between the first electrode 101 and the second electrode 201. This may not occur. In this case, each liquid crystal in the liquid crystal droplets 302 and 306 may be arranged without a certain orientation.

In the open circuit 400a state, incident light R1 and R2 may be incident on the second substrate 200. The incident light (R1, R2) may strike the liquid crystal in the liquid crystal droplets (302, 306) and be reflected. Since the first area (P1) has greater transparency and lower turbidity than the second area (P2), the incident light (R1) incident on the first area (P1) is greater than the incident light (R2) incident on the second area (P2). Less reflection or scattering may occur. Accordingly, the first area P1 and the second area P2 have different reflectivities and can be distinguished from each other when observed with the naked eye. The transmittance of incident light in the first area P1 and the second area P2 may be 0.01 to 10%.

The liquid crystal layer 300 may further include an ultraviolet curing agent (not disclosed) and a dispersant (not disclosed). The ultraviolet curing agent (undisclosed) may have a weight ratio of 0.5 to 10 weight per 100 weight of the polymer. UV curing agent (undisclosed) is 1-Hydroxy-cyclohexyl-phenyl-ketone (Irgacure 907), 2-methyl-1[4-(methylthio)phenyl]-2 -Morpholinopropane-1-one (2-Methyl-1[4-(methylthio)phenyl]-2-morpholinopropane-1-one, Irgacure 184C), 2-hydroxy-2-methyl-1-phenyl-propane- 1-One (1-Hydroxy-2-methyl-1-phenyl-propane-1-one, Darocur 1173), an initiator mixed with 50 wt% of Irgacure 184C and 50 wt% of benzophenone (Irgacure 500), an initiator containing 20 wt% of Irgacure 184 and 80 wt% of Irgacure 1173 (Irgacure 1000), 2-hydroxy-1-[4-(2-hydroxyethoxy)phenyl] -2-Methyl-1-propanone (2-Hydroxy-1-[4-(2-hydroxyethoxy)phenyl]-2-methyl-1propanone, Irgacure 2959), Methylbenzoylformate (Darocur MBF), alpha, Alpha, alpha-dimethoxy-alpha-phenylacetophenone (Irgacure 651), 2-benzyl-2-(dimethylamino)-1-[4-(4-morpholinyl)phenyl] -1-Butanone (2-Benzyl-2-(dimethylamino)-1-[4-(morpholinyl) phenyl]-1-butanone, Irgacure 369), Irgacure 369 contains 30 wt% and Irgacure 651 contains 70 wt%. wt% mixed initiator (Irgacure 1300), diphenyl (2,4,6-trimethylbenzoyl)-phosphine oxide, Darocur TPO 50 wt % and Darocur 1173 mixed with 50 wt% initiator (Darocur 4265), phosphine oxide, phenyl bis(2,4,6-trimethyl benzoyl, Irgacure 819), 2-hydroxy-2-methyl-1-phenyl-propane-1-one (2-hydroxy-2-methyl-1-phenyl-propane-1-one) (Darocur 1173), Irgacure 819 Initiator mixed with 5 wt% of Irgacure 1173 and 95 wt% of Darocure 1173 (Irgacure 2005), Initiator mixed with 10 wt% of Irgacure 819 and 90 wt% of Darocure 1173 (Irgacure 2010), Irgacure 819 contains 20 wt% Initiator mixed with 80 wt% wt% of Darocure 1173 (Irgacure 2020), bis (eta5-2,4,-cyclopetadien-1-yl) bis[2,6-difluoro-3- (1H-pyrrol-1-yl)phenyl] titanium (Bis(.eta.5-2,4-cyclopentadien-1-yl) bis[2,6-difluoro-3-(1H-pyrrol-1-yl)phenyl ]titanium, Irgacure 784), mixed initiator containing benzophenone (HSP 188), 1-hydroxy-cyclohexylphenyl-ketone (CPA), and 2,4,6,-trimethylbenzoyl-diphenyl-phosphine oxide (2, It may include at least one of 4,6,-trimethylbenzoyl-diphenyl-phosphineoxide) (Darocur TPO).

The polymer dispersed liquid crystal display 1000 may further include an ultraviolet ray blocking layer (not disclosed). The UV blocking layer (not shown) is between the first substrate 100 and the first electrode 101, on the bottom of the first substrate 100, between the second substrate 200 and the second electrode 201, and on the second substrate ( 200) It may be provided at at least one location on the upper surface. The ultraviolet ray blocking layer (not shown) may include at least one of polymer, inorganic material, and ceramic. Ultraviolet rays with a wavelength of 10 nm to 400 nm may be blocked by 50% to 99.9% by the ultraviolet ray blocking layer (not shown).

The polymer dispersed liquid crystal display 1000 may further include an infrared reflective film (not shown). The infrared reflecting film (not shown) is between the first substrate 100 and the first electrode 101, on the bottom of the first substrate 100, between the second substrate 200 and the second electrode 201, and on the second substrate 200. ) It may be provided at at least one location on the upper surface. The thermal insulation effect of the polymer dispersed liquid crystal display 1000 may be increased by an infrared reflective film (not shown).

Figure 2 is a conceptual diagram of a polymer dispersed liquid crystal display in a state in which a driving voltage is applied. For simplicity of explanation, differences from FIG. 1 are mainly explained.

Referring to FIG. 2, the first electrode 101, the second electrode 201, and the power source 400 may be electrically connected to form a closed circuit 400b. In the closed circuit 400b state, an electric field may be generated between the first electrode 101 and the second electrode 201. The direction of the electric field may be perpendicular to the first electrode 101 and the second electrode 201. The liquid crystals in the liquid crystal droplets 302 and 306 may be aligned in a direction parallel to the electric field. That is, the long axis of the liquid crystal may be parallel to the direction of the electric field.

In a state in which the liquid crystals are aligned, incident light R may be incident on the second substrate 200 . Compared to FIG. 1, the incident light (R) incident on the first region (P1) and the second region (P2) is less reflected in the liquid crystal and can pass through the first substrate 100 through the liquid crystal layer 300. there is. Therefore, in the closed circuit 400b state, the polymer dispersed liquid crystal display 1000 can maintain an overall transparent state. The transmittance of incident light (R) may be about 75% to 95%.

Figure 3 is a flowchart showing a manufacturing method of a polymer dispersed liquid crystal display. 4 to 6 are conceptual diagrams showing a method of manufacturing a polymer dispersed liquid crystal display.

Referring to FIG. 4, a liquid crystal material layer 303 may be inserted between the first electrode 101 and the second electrode 201. As a method of inserting the liquid crystal material layer 303, any one of coating methods such as spin coating, bar coating, screen printing, capillary injection, and one drop filling may be applied.

The liquid crystal material layer 303 may include a polymerized polymer precursor 304 and a plurality of liquid crystal droplets 305. Within the liquid crystal material layer 303, the phases of the polymerized polymer precursor 304 and the liquid crystal droplets 305 may not be distinguished. Therefore, it may be difficult to distinguish between the liquid crystal within the liquid crystal droplets 305 and the polymerized polymer precursor 304.

Referring to FIGS. 3 and 4 , a mask 500 including at least one opening may be provided on the liquid crystal material layer 303 (S100). A single or plural opening may define the first region P1 of the liquid crystal layer 300, which will be described later.

Subsequently, light 600 may be radiated onto the mask 500 (S200). Light 600 may be light of an ultraviolet wavelength. Light 600 passing through one or more openings may react with the polymerizable polymer precursor 304. The polymerizable polymer precursor 304 has the property of being cured into a polymer by ultraviolet rays, and a curing initiator (uninitiated) can accelerate curing. The wavelength of ultraviolet light may be 250 to 400 nm, and energy of 50 to 1000 mJ may be applied when curing the polymer.

Referring to FIGS. 3 and 5 , the mask 500 may be removed (S300). The polymer 301 undergoes phase separation from the liquid crystal droplets 302 and can be distinguished from the liquid crystal within the liquid crystal droplets 302. The area of the liquid crystal layer 300 where the polymer 301 is formed may be the first area (P1).

Next, the liquid crystal material layer 303 can be heat treated using the heat source 700 (S400). Heat treatment may include heat treatment or cooling treatment. Temperature conditions during heat treatment may be -40 degrees to 100 degrees, and preferably -20 degrees to 80 degrees.

During heat treatment, the temperature of the liquid crystal material layer 303 may increase and the dispersibility of the polymerizable polymer precursor 304 and liquid crystal within the liquid crystal material layer 303 may increase. Next, light 600 can be irradiated to the liquid crystal material layer 303 (S500). A reaction may occur in which the polymerized polymer precursor 304 that remained unreacted becomes the polymer 301. In this process, the polymer 301 undergoes phase separation from the liquid crystal droplets 306 and can be distinguished from the liquid crystal within the liquid crystal droplets 306.

Referring to FIG. 6, an area of the liquid crystal layer 300 containing liquid crystal droplets 306 formed at a higher temperature may be the second area P2. The average size of the liquid crystal droplets 306 in the second region P2 may be smaller than the average size of the liquid crystal droplets 302 in the first region P1 formed at a relatively lower temperature. Additionally, the number of liquid crystal droplets 306 in the second region P2 per unit volume may be greater than the number of liquid crystal droplets 302 in the first region P1 per unit volume. This is because during heat treatment, as the temperature of the liquid crystal material layer 303 increases, phase separation of the polymer 301 and the liquid crystal droplets 306 occurs while the liquid crystal is dispersed.

Although the present invention illustrates a method of manufacturing the first area P1 and the second area P2 as an example, it may further include a third area, a fourth area, a fifth area, etc. As an example, the manufacturing method for forming a third region in addition to the first region and the second region is as follows.

A first region that is a liquid crystal layer can be formed by providing a first mask including at least one opening on the liquid crystal material layer and irradiating light onto the first mask. Subsequently, the first mask may be removed, and a first heat treatment may be performed on the liquid crystal material layer. Again, a second mask can be provided including at least one opening on the liquid crystal material layer. The opening of the second mask may correspond to at least a portion of the closed area of the first mask. By irradiating light on the second mask, a second region, which is a liquid crystal layer, can be formed. Subsequently, the second mask may be removed and the liquid crystal material layer may be subjected to a second heat treatment. By irradiating light to the unreacted liquid crystal material layer, a third region, which is a liquid crystal layer, can be formed.

When irradiating light, the temperature can be differentiated about 2-5 times, and in this case, the second to fifth regions can be formed.

Figures 7a to 7e show an embodiment of a polymer dispersed liquid crystal display from a plan view.

Referring to FIGS. 7A to 7E , as the reflectivity of the first region (P1), second region (P2), and third region (P3) is different, various patterns can be created without a driving voltage being applied.

The present invention not only divides space or protects privacy by making the inside invisible with various reflective patterns when no driving voltage is applied, but can also be used as a colored screen when the image projector is operated. there is. When a driving voltage is applied, it changes to a transparent state and can provide a window state.

Above, embodiments of the present invention have been described with reference to the attached drawings, but those skilled in the art will understand that the present invention can be implemented in other specific forms without changing the technical idea or essential features. You will understand that it exists. Therefore, the embodiments described above should be understood in all respects as illustrative and not restrictive.

100: first substrate 101: first electrode
200: second substrate 201: second electrode
300: Liquid crystal layer 301: Polymer
302, 305, 306: Liquid crystal droplets
400: Power 400a, 400b: Open loop, closed loop
P1, P2: first area, second area
R1, R2: Incident light 500: Mask
600: UV ray 303: Liquid crystal material layer
304: polymer precursor 700: heat source

Claims (10)

first substrate;
a first electrode on the first substrate;
a second electrode on the first electrode;
a second substrate on the second electrode; and
Comprising a liquid crystal layer interposed between the first electrode and the second electrode,
The liquid crystal layer includes a polymer layer and a first region and a second region where liquid crystal droplets are distributed within the polymer layer,
The average size of the liquid crystal droplets in the first area is larger than the average size of the liquid crystal droplets in the second area,
An ultraviolet blocking film provided at least one of the following: between the first substrate and the first electrode, on the lower surface of the first substrate, between the second substrate and the second electrode, and on the upper surface of the second substrate, and Further comprising an infrared reflective film,
The ultraviolet ray blocking film includes at least one of polymer, inorganic material, and ceramic,
Each of the first electrode and the second electrode extends continuously from the first area toward the second area in plan view, so that each of the first electrode and the second electrode extends from the first area and the second electrode. Vertically overlaps both of the second regions,
The thickness of the liquid crystal layer is 2.5㎛ to 100㎛,
The liquid crystal droplets have a weight ratio of 80 to 120 based on 100 weight of the polymer layer,
The liquid crystal layer further includes an ultraviolet curing agent and a dispersant,
The ultraviolet curing agent has a weight ratio of 0.5 to 10 based on 100 weight of the polymer layer,
The ultraviolet curing agent is 1-Hydroxy-cyclohexyl-phenyl-ketone (Irgacure 907), 2-methyl-1[4-(methylthio)phenyl]-2-morpholino Propane-1-one (2-Methyl-1[4-(methylthio)phenyl]-2-morpholinopropane-1-one, Irgacure 184C), 2-hydroxy-2-methyl-1-phenyl-propane-1-one (1-Hydroxy-2-methyl-1-phenyl-propane-1-one, Darocur 1173), initiator (Irgacure 500) mixed with 50 wt% of Irgacure 184C and 50 wt% of benzophenone ), an initiator containing 20 wt% of Irgacure 184 and 80 wt% of Irgacure 1173 (Irgacure 1000), 2-hydroxy-1-[4-(2-hydroxyethoxy)phenyl]-2- Methyl-1-propanone (2-Hydroxy-1-[4-(2-hydroxyethoxy)phenyl]-2-methyl-1propanone, Irgacure 2959), Methylbenzoylformate (Darocur MBF), alpha, alpha-di Methoxy-alpha-phenylacetophenone (Alpha, alpha-dimethoxy-alpha-phenylacetophenone, Irgacure 651), 2-benzyl-2-(dimethylamino)-1-[4-(4-morpholinyl) phenyl]-1- Butanone (2-Benzyl-2-(dimethylamino)-1-[4-(morpholinyl) phenyl]-1-butanone, Irgacure 369), 30 wt% of Irgacure 369 and 70 wt% of Irgacure 651 mixed Initiator (Irgacure 1300), Diphenyl (2,4,6-trimethylbenzoyl)-phosphine oxide, Darocur TPO), Darocur TPO 50 wt% Initiator mixed with 50 wt% of Cure 1173 (Darocur 4265), phosphine oxide, phenyl bis(2,4,6-trimethyl benzoyl, Irgacure 819) , 2-hydroxy-2-methyl-1-phenyl-propane-1-one (Darocur 1173), Iragacure 819 5 wt % and Darocure 1173 mixed at 95 wt% (Irgacure 2005), Iragacure 819 mixed at 10 wt% and Darocure 1173 at 90 wt% (Irgacure 2010), Irgacure 819 mixed at 20 wt% Darocure 1173 mixed with 80 wt% initiator (Irgacure 2020), bis (eta5-2,4,-cyclopetadien-1-yl) bis[2,6-difluoro-3-(1H- pyrrol-1-yl)phenyl] titanium (Bis(.eta.5-2,4-cyclopentadien-1-yl) bis[2,6-difluoro-3-(1H-pyrrol-1-yl)phenyl]titanium, Irgacure 784), mixed initiator containing benzophenone (HSP 188), 1-hydroxy-cyclohexylphenyl-ketone (CPA), and 2,4,6,-trimethylbenzoyl-diphenyl-phosphine oxide (2,4,6) A polymer dispersed liquid crystal display containing at least one of ,-trimethylbenzoyl-diphenyl-phosphineoxide) (Darocur TPO). According to paragraph 1,
Each of the liquid crystal droplets includes a plurality of liquid crystals,
Each of the liquid crystals has a flow viscosity (mm-2/s) of 20 to 100, a refractive index anisotropy of 0.15 to 0.30, and a dielectric anisotropy of 2.0 to 40.0.
According to paragraph 1,
A polymer dispersed liquid crystal display wherein the number of liquid crystal droplets distributed in the first area per unit volume is less than the number per unit volume of liquid crystal droplets distributed in the second area.
According to paragraph 1,
A polymer dispersed liquid crystal display wherein the first region and the second region have different reflectivities for incident light.
According to paragraph 1,
A polymer dispersed liquid crystal display in which the first region has greater transparency and less haze than the second region.
According to paragraph 1,
Each of the liquid crystal droplets includes a plurality of liquid crystals,
Further comprising a power source connected to the first electrode and the second electrode,
An electric field is generated in the first electrode and the second electrode by the power supply,
In an open circuit state, the liquid crystals are arranged without a certain direction,
A polymer dispersed liquid crystal display in which the long axes of each of the liquid crystals are parallel to the first electrode and the second electrode in a closed circuit state.
delete delete delete delete

Images