KR20080035811A - Polymer substrate with a function of the color filter and method thereof - Google Patents

Abstract

A polymer substrate and a manufacturing method thereof are provided to minimize brightness reduction by forming a color filter layer using a polymer thick film material, whose refractive index is between those of a front polymer film substrate and an anti-diffusion layer. A polymer substrate includes polymer film substrates(1,1'), a color filter layer(102), anti-diffusion layers(2,2'), and transparent electrodes(3,3'). The polymer film substrate is made of one of PMMA(PolyMethylMethAcrylate), PET(PolyEthylene Terephthalate), PC(PolyCarbonate), PES(PolyEtherSulfone), and COC(Cyclic Olefin Copolymer). The color filter layer is coated on one surface of the polymer film substrate. The anti-diffusion layer is made of a first oxide, which is formed by a vacuum deposition on the other surface of the polymer film substrate or on the color filter layer. The transparent electrode is made of a second oxide, which is formed by the vacuum deposition on the anti-diffusion layer. An aliphatic carbon hydrate derivative is mixed with an aromatic carbon hydrate derivative at a rate between 10:1 and 10:2 to form a mixed solvent. A visual ray absorption dye or a visual ray absorption pigment and a polymer are melted in the mixed solvent to form a polymer resin. The polymer resin is applied on a surface of the polymer film substrate at a thickness between 10 um and 100 um. The polymer film substrate is dried at a room temperature.

Description

Polymer substrate with color filter function and its manufacturing method {POLYMER SUBSTRATE WITH A FUNCTION OF THE COLOR FILTER AND METHOD THEREOF}

1 is a cross-sectional view of a general structure of a flexible display.

2 is a cross-sectional view of a general structure of a touch screen.

3 is a cross-sectional view of a conventional polymer substrate.

4 is a cross-sectional view of a polymer substrate having a color filter function of the present invention.

5 is a light transmission characteristic diagram of the polymer substrate (Preparation Example 1) of the present invention.

Explanation of symbols on the main parts of the drawings

1, 1 ': front polymer film substrate 2, 2': diffusion barrier layer

3, 3 ': transparent electrode 4: light emitting layer

5: red phosphor 6: green phosphor

7: blue phosphor 8: metal electrode

8 ': flexible printed circuit 9, 9': back polymer film substrate

10: drive circuit 11, 11 ': display light

100: dot spacer 101: display module

102: color filter layer

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a functional polymer substrate for use in a flexible display or a touch screen and a method of manufacturing the same. The present invention relates to a functional film substrate by coating a polymer resin containing dye or pigment on a surface of a polymer film substrate. In addition, to optimize the transmission spectrum of the light to have the function of the color filter to improve the color purity at the same time.

Generally, the structure of a display device (FIG. 1) that can be applied to a flexible display such as an organic electroluminescent device (OLED), a plastic LCD, and the like, which is known as a next-generation display, has a basic structure as follows. That is, the transparent electrode 3 and the metal electrode 8 formed by the vacuum deposition method or the thick film printing method between the front polymer film substrate 1 and the back polymer film substrate 9 are formed by a vacuum deposition method or a thick film printing method. It consists of the light emitting layer 4 which emits visible light. A diffusion barrier layer 2 is formed between the front polymer film substrate 1 and the transparent electrode 3 so that ions in the polymer film and oxygen or water vapor in the atmosphere are diffused and transferred to the transparent electrode 3 to form a transparent electrode 3. It prevents the electrical characteristics from changing or penetrating into the device to change the characteristics of the device. The light emitting layer 4 basically consists of a red phosphor 5, a green phosphor 6, and a blue phosphor 7 so that a direct current or an alternating current is applied to the transparent electrode 3 and the metal electrode 8 to the driving circuit 10. When applied by the red phosphor 5, the green phosphor 6, and the blue phosphor 7 can be excited and relaxed to give visible light, thereby displaying an image or information. (In the case of the plastic LCD, the tricolor light emitted from the backlight is used instead of the tricolor light generated in the light emitting layer 4. The backlight is located under the device, that is, under the back polymer film substrate 9 of FIG. The driving circuit 10 is an electronic circuit that applies a pulse signal between two electrodes of the flat panel display element for information display, and the display light 11 is generated in the fluorescent layer 4 of the display element. And visible light coming out of the device (red, blue, green and mixed light thereof).

However, the current technology level of the phosphor for display elements has not reached perfect red, green, and blue reproduction. In particular, the OLED has a wide spectrum of light emitted from the red phosphor 5, the green phosphor 6, and the blue phosphor 7 so that the color purity is degraded. Therefore, a significant improvement in the color purity of the phosphor is required. In the case of LCD, since the tricolor light generated from the backlight is obtained by exciting the phosphor, color purity has a fundamental problem.

As such, the OLED phosphor has its own color purity problem, and in the case of LCD, the phosphor has a fundamental color purity problem.

The color filter is proposed as a method of improving color purity by improving color purity. In the case of a conventional flat panel display device using glass as a substrate, a red color filter, a green color filter, and a blue color filter are formed between the front glass substrate and the transparent electrode by thick film firing using a method such as screen printing or electrophoresis. It is formed by filling a black dielectric between the color filters.

In general, an iron oxide inorganic pigment is used as the material of the red color filter, and a cobalt oxide inorganic pigment is used as the material of the green and blue color filters. In the case of screen printing, the inorganic pigment is mixed with a low-temperature decomposable resin such as ethyl cellulose and an organic solvent such as butyl carbitol acetate to form a paste, followed by three thick film firings of red, green and blue color filters sequentially. To form.

Since the color filter for display elements formed by such a conventional method uses glass as a substrate, it can be manufactured through the high temperature thermal process of three thick film baking. However, in a flexible display using a polymer film as a substrate, the thermal and electrical properties of the front polymer film substrate 1 or the transparent electrode 3 may be changed during the thermal process, and chemical reaction with the transparent electrode 3 may occur. There is a problem that can occur to shorten the life of the device. Therefore, if possible, there is a need for a method capable of securing a color filter layer on the polymer substrate by a low temperature process.

Meanwhile, even in the structure of the touch screen shown in FIG. 2, the front polymer film substrate 1 ′, the diffusion barrier layer 2 ′, and the transparent electrode 3 ′ are made of the same or similar material and structure as in the flexible display. However, the display module 101 is controlled by the flexible printed circuit 8 'formed on the back polymer film substrate 9', and the visible light 11 'is only passed. The dot space 100 serves to separate the front polymer film substrate 1 'and the back polymer film substrate 9'. In such a touch screen, since the display module 101 uses LCD or OLED, the color purity problem of light generated from the above-mentioned phosphor or backlight is still inevitable.

In general, when the color filter layer is formed in a display or a touch screen, the luminance of the device is reduced by 40% or more. Therefore, it is required to minimize the decrease in the luminance of the visible light 11 and 11 ′ exiting the device by maximizing the transmission characteristics of the light passing through the color filter layer.

To do this, it is preferable to use a material having a refractive index value between the refractive indices of the front polymer film substrates 1 and 1 'and the refractive indices of the diffusion barrier layers 2 and 2' as the color filter layer material. This is because the refractive indices of the two boundary materials are n ₁ and n ₂ , respectively, and the light transmittance is T, which is given by T = 1-(n ₁ -n ₂ ) ² / (n ₁ + n ₂ ) ² .

The present invention has a color filter function and has high color light in a conventional polymer substrate composed of a polymer film substrate (1, 1 '), a diffusion barrier layer (2, 21) and a transparent electrode (3, 31) of a touch screen. It is a technique of forming a color filter layer in which transmittance can be realized. That is, a polymer resin is prepared by dissolving a polymer in a solvent containing a dye or a pigment, and the resin is coated on the surface of the polymer film by a low temperature process to form a color filter layer 102 in the form of a functional polymer thick film, thereby providing a good color in the visible region. Brightness by forming a color filter layer 102 with a polymer thick film material having a filter function and at the same time the value of the refractive index is between the refractive index of the front polymer film substrate (1, 1 ') material and the refractive index of the diffusion barrier layer (2, 2'). It has a function to minimize the reduction.

The present invention aims to easily produce a functional polymer substrate in a process free from thermal chemical deformation by manufacturing a color filter layer 102 showing a high transmission optical property as well as a simple substrate. In the present invention using a material that minimizes the decrease in brightness, the polymer polymer is dissolved in a mixed solvent containing dyes or pigments to produce a functional polymer resin having viscosity, and the coating of the functional polymer resin (Bar Coating) and doctor blade ( A thick film is formed on the surface of the polymer film substrate by a method such as doctor blading, spin coating, and micro gravure coating, and then dried at low temperature at room temperature to form a functional polymer thick film to form a color filter layer for a flexible display device. Formed.

The present invention prepares an organic dye solution or an organic pigment solution by dissolving a dye or pigment that absorbs visible light in a mixed solvent of an aliphatic hydrocarbon derivative or an aromatic hydrocarbon derivative, and the organic dye solution or organic pigment solution is acrylic, carbonate, ester A functional polymer substrate is prepared by melting a high molecular polymer such as a mucous functional polymer resin at room temperature and then thickening it to the surface of the polymer film substrate to dry at low temperature at room temperature to form a color filter layer. It is characterized by.

Hereinafter, the manufacturing method of the functional polymer substrate of the present invention (FIG. 4) will be described in detail.

<Production Example  1>

Aliphatic hydrocarbon derivatives such as acetone, chloroform, methyl ethyl ketone, diethylene dioxide, tetrahydrofuran, etc. may be used as visible light absorbing organic dyes such as pyrromethene, porphyrin, or azo. B) an organic dye solution is prepared by dissolving a solvent which is an aromatic hydrocarbon derivative such as chlorbenzene, chlorphenol, toluene, xylene, cyclohexanone and the like in a mixed solvent of two or more predetermined volume ratios. The type or number of dyes used to prepare the organic dye solution may vary depending on the intended use (applied device), and one or more organic dyes may be mixed and used. The volume ratio of the aliphatic hydrocarbon derivative and the aromatic hydrocarbon derivative is preferably 10: 1 to 2. A liquid functional polymer obtained by dissolving PMMA (polymethylmethacrylate), an acrylic polymer copolymer, polycarbonate (PC), or polyester, an ester polymer, in an organic dye solution prepared by dissolving in a mixed solvent. Resin is prepared at room temperature. The concentration of dye in the polymer is in the range of 50 to 10,000 ppm.

In order to smooth the surface of the color filter layer 102 to be formed by using the polymer resin obtained above or to suppress bubbles in the inside, a plasticizer such as dibutyl phthalate or diethyl phthalate and an antifoaming agent such as polyvinyl acetate are added to the organic dye solution. It is added to the polymer resin at a weight ratio of less than 10%.

Functional polymer resins of mucous membranes were coated by PMMA (Polymethylmethacrylate), PET (Polyethylene terephthalate), PET, etc. using Bar Coating, Doctor Blading, Spin Coating, Micro Gravure, etc. After thickening the surface of polymer film substrates (1, 1 ') such as polycarbonate (PC), polyetherethersulfone (PES), and cyclic olefin copolymer (COC) to a thickness of about 10 to 100 microns, Within minutes) to form a color filter layer 102. The diffusion barrier layers 2 and 2 'are formed by vacuum deposition in a thickness range of 30 to 100 nm by a conventional thin film vacuum deposition method such as sputtering or electron beam deposition using an oxide material such as silica (SiO ₂ ), or a silica component. It is formed by a wet film forming process by sol-gel and dip coating using a thick film material containing. The transparent electrode 3 is a conventional thin film vacuum such as sputtering an oxide such as indium tin oxide (In ₂ O ₃ : Sn) and indium zinc oxide (In ₂ O ₃ : ZnO) in a thickness range of 100 to 300 nm, and electron beam deposition. It is formed by vacuum deposition by a vapor deposition method or by a wet film forming process by sol-gel and dip coating using a thick film material containing a transparent electrode component. In view of the light transmittance, considering that the material used as the diffusion barrier layers 2 and 2 'on the polymer substrate (refractive index-1.6) such as PET is generally silica (refractive index-1.4), It is possible to minimize the decrease in luminance due to the difference in refractive index according to the light transmittance formula mentioned above that the refractive index of the color filter layer 102 material formed is about 1.5. Therefore, PMMA, which has a refractive index of about 1.5 in the visible region, is most suitable as the polymer polymer for preparing the polymer resin.

The color filter layer 102 made of a polymer thick film may be formed on the polymer film substrates 1 and 1 'as shown by a dotted line in FIG. Even in this case, the function of the color filter layer is maintained. The light transmittance also has a value of the refractive index between the polymer film substrate (refractive index-1.6) and air (refractive index-1.0) because the color filter layer (refractive index-1.5) can minimize the decrease in luminance by the above formula.

<Production Example  2>

Among the contents described in <Preparation Example 1>, instead of visible light absorbing organic dyes such as pyrromethene, porphyrin, or azo, anthraquinone, phthalocyanine, or phthalocyanine The color filter layer 102 can be manufactured by the same process described in <Production Example 1> by using one or more organic pigments such as oxazine and the like, and in this case also in <Production Example 1> The same effect can be obtained.

The polymer substrate of Preparation Example 1 prepared by dissolving the visible light-absorbing organic dye in a mixed solvent in this manner and adding it to PMMA, which is one of the polymer polymers, to thicken the film on the PET film substrate by a low temperature process. As shown in FIG. 5, excellent red (600 nm or more), green (500 nm to 550 nm), and blue (470 nm or less) light transmission characteristics were confirmed in the visible light region having a wavelength of 400 nm to 700 nm. That is, it has a function of selectively passing only three primary colors of light through one color filter layer 102. As a result, the color purity improvement effect in the OLED device and the LCD device adopting the functional polymer substrate of the present invention is largely red (R), green (G), blue (B) as shown in the color coordinate measurement results of Table 1 and Table 2 Improvements were made.

(Table 1) Measurement result of color coordinates of OLED device

Color coordinates of OLED device adopting general transparent substrate (x. Y) Color coordinate (x.y) of OLED device adopting functional polymer substrate of the present invention R (0.608, 0.386) (0.622, 0.371) G (0.246, 0.672) (0.234, 0.677) B (0.165, 0.286) (0.158, 0.275)

(Table 2) Measurement result of color coordinates in LCD device

Color coordinates of LCD element adopting general transparent substrate (x.y) Color coordinate (x.y) of the LCD element employing the functional polymer substrate of the present invention R (0.639, 0.347) (0.653, 0.331) G (0.271, 0.626) (0.244, 0.593) B (0.142, 0.078) (0.140, 0.071)

Claims (7)

Polymer film substrate made of any one of polymethylmethacrylate (PMMA), polyethylene terephthalate (PET), poly carbonate (PC), poly-ethersulfone (PES), cyclic olefin copolymer (COC), A color film layer coated on one surface of the polymer film substrate, A diffusion barrier layer formed of a first oxide formed on the other surface of the polymer film substrate or on the color film layer by vacuum deposition; A polymer substrate comprising a transparent electrode made of a second oxide formed on the diffusion barrier layer by vacuum deposition method, The color filter layer dissolves a visible light absorbing dye or a visible light absorbing pigment and a polymer in a mixed solvent of an aliphatic hydrocarbon derivative and an aromatic hydrocarbon derivative at a ratio of 10: 1 to 2 by volume to form a polymer resin. A polymer substrate formed by coating a thick film with a thickness of 10 µm to 100 µm on the surface and drying at room temperature. The method of claim 1, Polymer substrate, characterized in that the polymer used in the color filter layer is PMMA. The method according to claim 1 or 2, The visible light absorbing dye is a polymer substrate, characterized in that at least one organic dye selected from pyrromethene-based, porphyrin-based, Azo-based. The polymer substrate according to claim 1 or 2, wherein the visible light absorbing pigment is at least one organic pigment selected from anthraquinone, phthalocyanine, and oxazine. The method according to claim 1 or 2, The polymer substrate, characterized in that the first oxide comprises silica. The method according to claim 1 or 2, The second oxide is a polymer substrate, characterized in that containing indium tin oxide or indium zinc oxide. Dissolving a dye or pigment absorbing visible light in a mixed solvent of an aliphatic hydrocarbon derivative and an aromatic hydrocarbon derivative to prepare an organic dye solution or an organic pigment solution, and polymethyl methacryl, which is an acrylic polymer polymer, in an organic dye solution or an organic pigment solution. The process of manufacturing liquid polymer resin by melt | dissolving the polycarbonate which is a rate and a carbonate polymer polymer, or polyester which is an ester polymer copolymer, and this is a polymer film Coating on one surface of the substrate with a thick film and drying at room temperature to form a color filter layer, forming a diffusion barrier layer of silica on the exposed other surface or color filter layer of the polymer film substrate by vacuum deposition, and on the diffusion barrier layer Forming a transparent electrode made of indium tin oxide or indium zinc oxide by vacuum evaporation.

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