KR20040067482A - Preparation of front filter for plasma display panel - Google Patents

Abstract

PURPOSE: A method is provided to reduce distortions of images by improving the smoothness of a filter and achieve improved yield rate by reducing an inflow of blister. CONSTITUTION: A method comprises a step of stacking an adhesive film(4), a conductive mesh(3), a transparent plastic film(2) deposited with a colorant layer having a near infrared shielding function and a color purity enhancing function, and a mirror finished plate(1) on a transparent glass substrate(5); and a step of vacuum pressing the structure obtained in the previous step. The mirror finished plate is controlled to have a surface roughness of 0.01 to 0.1§­. The mirror finished plate is made of a metal, plastic, or a glass.

Description

Manufacturing method of front filter for plasma display panel {PREPARATION OF FRONT FILTER FOR PLASMA DISPLAY PANEL}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a front filter for a plasma display panel (PDP), and in particular, vacuum thermocompression bonding of a film having a layer having a transparent substrate, a conductive mesh, a near infrared ray blocking function and a light selective absorbing function is performed sequentially. When manufactured by the Vacuum Heat Pressing method, it characterized in that the surface roughness of the mirror plate to determine the smoothness of the rear surface to a specific range.

PDP (Plasma Display Panel) is easier to be enlarged than other display devices, and is considered to have the most suitable characteristics as a high-quality digital television in the future as a thin light emitting display device. However, PDP has a disadvantage that the emission of electromagnetic waves and near infrared rays is high, the surface reflection of the phosphor is high, and the color purity does not reach the cathode ray tube due to the orange light emitted from the encapsulated gas helium.

Therefore, in order to not only prevent harmful effects of human body and malfunction of precision instruments caused by electromagnetic waves and near-infrared rays generated from PDP, but also to reduce surface reflection and improve color purity, the electromagnetic wave blocking, near-infrared blocking, light surface reflection prevention, and color purity improvement functions are provided. The front filter for PDP is adopted.

The field of use of PDP is divided into business and public use according to electromagnetic wave shielding performance. The front filter applied to business (Class A) PDP alternately stacks a metal such as silver and oxides of high refractive index on the back of the substrate to shield electromagnetic and near infrared rays. It is completed by forming an antireflection film on both sides of the substrate or by bonding an antireflection film. On the other hand, for public use (Class B), a conductive mesh is inserted between two transparent substrates to be bonded to each other, and the antireflection film is bonded to the surface thereof, and the film having the near-infrared blocking layer formed on the back surface is bonded to the antireflection film thereon. The formed films are bonded together (see Japanese Patent Application Laid-Open No. 11-74683, Patent Publication No. 1998-064559), or a conductive mesh and an antireflection film are sequentially bonded to a surface of a single transparent substrate such as acrylic or glass, and a near-infrared shielding layer is formed on the back side thereof. A method of bonding the formed film is proposed (Japanese Patent Laid-Open No. 13-134198). In addition, Korean Patent Publication No. 2002-0013743 discloses a method for thermocompression-integrating an optical film such as a conductive mesh and an antireflection film or a near-infrared blocking film on a glass substrate with two types of adhesive layers comprising an adhesive layer and a heat adhesive film.

However, according to the conventional method, the front filter for PDP (Plasma Display Panel) using two transparent substrates has a disadvantage in that it is difficult to reduce the thickness and weight because of the large thickness and weight.

In addition, in the front filter for plasma display panel (PDP), near-infrared cut performance is an important requirement for the purpose of preventing the malfunction of the remote control. In particular, in recent years, the near-infrared rays are increasing as the brightness of the PDP is improved. It also requires a higher level of near-infrared blocking. When an acrylic resin plate is used as the transparent substrate of the front filter for PDP (Plasma Display Panel), the near-infrared cut performance can be imparted by incorporating a copper-based material in the acrylic resin of the substrate material. Since it is weak and there is a danger of thermal deformation, it is not preferable as a transparent substrate of the front optical filter for PDP. For this reason, it is preferable to use the glass substrate excellent in heat resistance as a transparent substrate, and to implement the front surface filter for PDP (plasma display panel) which has favorable near-infrared cut performance.

Therefore, in order to reduce weight and thickness, recently, a conductive mesh and an optical film (anti-reflective film, near-infrared shielding film) are manufactured on the surface of one glass substrate by a vacuum heat pressing method through an adhesive or an adhesive. The method is used a lot. In the above-mentioned thermocompression bonding method, a method of interposing and heating and pressing members between mirror finished plates made of SUS is referred to (see Japanese Patent Laid-Open No. 13-134198 and Korean Patent Laid-Open No. 2002-13743).

In the present invention, the surface condition of the mirror plate used in the production of the front filter by vacuum thermocompression method affects the smoothness of the front filter and induces bubble mixing or pressing marks, which is an important factor in determining the production yield. PDP (Plasma Display Panel), which can recognize the point and determine the material and surface roughness condition of the used mirror plate to improve the visibility of the filter, reduce the distortion of the phase, and reduce the mixing or pressing marks of bubbles to improve the manufacturing process yield. To provide a front filter manufacturing method for).

1 is a view showing a configuration that is set during the vacuum thermocompression of the front filter for PDP (plasma display panel) to which the present invention is applied,

2 is a cross-sectional view showing the layer structure of the front filter for PDP manufactured according to the present invention.

* Brief description of the reference numbers

1: mirror plate 2: transparent resin film

2a: near infrared ray blocking and selective light absorbing layer 3: mesh

4: adhesive sheet 5: glass substrate

5a: Glass substrate back side 5b: Glass substrate front side

6: antireflection film

In order to achieve the above object, in the present invention, a transparent plastic film coated with a pigment layer having an adhesive film, a conductive mesh, a near infrared ray blocking function and a color purity improving function by selective light absorption on a transparent glass substrate, wherein the pigment layer is applied to the mesh surface. And a mirror plate, which are sequentially laminated, and vacuum thermocompression bonding thereof, wherein the surface roughness Ra of the mirror plate is adjusted in a range of 0.01 to 0.1 μm. Provided is a method of manufacturing a front filter.

Hereinafter, the present invention will be described with reference to the accompanying drawings.

1 is a view showing a laminated configuration during vacuum thermocompression bonding according to the present invention, Figure 2 is a cross-sectional view showing the layer configuration of the front filter for PDP (plasma display panel) formed by the present invention.

Referring to FIG. 1, a layer 2a containing a near infrared ray blocking pigment and a selective light absorbing dye is formed on the surface layer of the transparent plastic resin film 2. Thermoplastic resins such as polyethylene terephthalate (PET), polycarbonate (PC), polymethyl methacrylate (PMMA), triacetate cellulose (TAC) and polyether sulfone (PES) are used as the transparent plastic resin film. 25-250 micrometers is suitable for the thickness of a base film, for example, 80% or more of light transmittance, More preferably, 90% or more is suitable.

The layer 2a may be formed by coating a solution containing a near infrared ray blocking pigment and a selective light absorbing dye on a transparent plastic film. As the near-infrared blocking dye, it is preferable to use a mixed complex of a nickel complex system and a diimmonium-based dye, a dye or an organic dye containing a compound containing copper or zinc ions, and the near-infrared blocking dye is 100 parts by weight of the total solid in the coating solution. It is preferable to use in an amount of 1 to 20 parts by weight on the basis of.

In addition, as the photoselective light-absorbing dye, as described in Korean Patent Laid-Open Publication No. 2001-026838 or 2001-039727, tetraazapophyrin has a metal (M) element in the central group, and any material in the group consisting of ammonia, water, and halogen. It is preferable to use derivative pigment | dye which coordinated with this metal element. The metal M is preferably any one selected from the group consisting of Zn, Pd, Mg, Mn, Co, Cu, Ru, Rh, Fe, Ni, V, Sn, Ti.

The selective light absorbing pigment is preferably used in an amount of 0.01 to 5 parts by weight based on 100 parts by weight of the total solids in the coating composition. If the content of the selective light absorbing pigment is less than 0.01 part by weight, the selective light absorbing function is lowered, and color purity improvement effects cannot be expected. If the content of the light absorbing dye is more than 5 parts by weight, the color balance of the filter is distorted and the transmittance is undesirably undesirable.

In addition to the infrared blocking dye and the selective light-absorbing dye, in order to control the transmittance or whiteness of each wavelength region, azo dye, cyanine dye, diphenylmethane dye, triphenylmethane dye, phthalocyanine dye, xanthene dye, di Phenylene dyes and dyes such as indigo and porphyrin can be added. It is used in amounts of 0.05 to 3% of the total solids in the composition.

The coating composition typically has a solids in the range of 15 to 50% by weight.

The pigments are mixed with a plastic transparent binder and a solvent to prepare a solution and applied onto a transparent plastic film. The plastic transparent binder materials include poly (methyl methacrylate) (PMMA) and polyvinyl alcohol (PVA). ), Polycarbonate (PC), ethylene vinyl acetate (EVA), poly (vinyl butylal) (PVB) polyethylene terephthalate (PET), and transparent plastic resin materials are possible, in an amount of 5 to 40% with respect to the solvent. use.

In addition, solvents that may be used in the pigment-containing coating composition include toluene, xylene, acetone, methyl ethyl ketone (MEK), propyl alcohol, isopropyl alcohol, methyl cellussolve, ethyl cellussolve, dimethylformamide (DMF), and the like. have.

In addition, a stabilizer may be added to the coating composition to improve light resistance. Stabilizers that can be used include radical reaction inhibitors that prevent the fading of pigments that can be used conventionally and are used in conventional amounts.

As the coating method, a conventional coating method may be applied. For example, roll coating, die coating, or spin coating may be used. The coating thickness is preferably about 1 to 20 μm after drying, and more preferably about 2 to 10 μm to achieve near-infrared blocking performance.

In the present invention, as the conductive mesh (3) material, a conductive fiber mesh using metal fibers or metal-coated fibers, a transparent conductive film, a metal mesh patterned by a photolithography process or a screen method, and the like can be used. The mesh can achieve the scattering prevention effect when the filter is damaged, thereby improving safety.

In the present invention, the width of the conductive mesh is in the range of 5 to 50 µm. In addition, if the pitch of the mesh is small, the transmittance is lowered, and if the pitch is too large, the electromagnetic wave blocking performance is lowered. Therefore, the mesh is usually in the range of 50 to 500 µm, preferably 100 to 400 µm. The thickness of the conductive mesh is usually in the range of 1 to 100 mu m, preferably in the range of 5 to 50 mu m.

The plastic film 2 and the conductive mesh 3 coated with the near-infrared cut-off and selective light absorbing layer 2a prepared above are bonded to the glass substrate 5 using the transparent adhesive 4.

Examples of the bonding method include a roll lamination method, a thermal pressing method, a vacuum thermocompression method, and the like, and a vacuum thermocompression method is most preferable to prevent mixing of bubbles in a large area.

As the transparent adhesive for vacuum thermocompression bonding, an adhesive film is usually used. When the thickness of the adhesive film is in the range of 10 to 500 μm, preferably in the range of 50 to 250 μm, sufficient adhesive strength can be obtained. If it is thinner than this, adhesive strength cannot be secured, and if it is thicker than this, the melt flow after heating becomes severe and the surface smoothness falls.

In the bonding process according to the present invention, for example, a transparent adhesive sheet 4 such as EVA or PVB having a thickness of about 50 to 500 μm on the glass substrate 5, a metal mesh 3 having a pattern formed thereon, near-infrared blocking and an optional light absorbing layer. The film 2 (2a) (positioned so that the layer 2a is in contact with the metal mesh 3) is placed in sequence, the mirror plate 1 is laminated thereon, and then heated and pressed in a vacuum press.

In the vacuum thermocompression step, the degree of vacuum is more preferably 100 Torr, in particular 10 Torr or less, the heating temperature is preferably 80 to 200 ° C and more preferably 80 to 130 ° C. 1-10 kgf / cm <^2> is suitable for pressurization amount, and 2-5 kgf / cm <^2> is especially preferable. The mixture is heated and pressurized for about 30 minutes under the vacuum conditions and then cooled under vacuum or in the air. Cooling methods include air cooling, water cooling, oil cooling and the like, but oil productivity is preferable in consideration of productivity.

In the vacuum thermocompression bonding step, in the present invention, metal, plastic, glass or the like having a surface roughness of 0.01 to 0.1 µm and a thickness of 0.1 to 2 mm is used as the mirror plate 1. In the present invention, when the surface roughness Ra of the mirror plate is less than 0.01 μm, the surface is too smooth so that the air layer interposed between the mirror plate and the optical film does not escape and the air mixing layer remains in the final filter or appears as pressed marks. On the contrary, when the surface roughness Ra is larger than 0.1 mu m, the roughness of the mirror plate is transferred to the optical film surface, resulting in distortion of the image.

Referring to FIG. 2, after taking out the manufactured laminate, the conventional antireflection film 6 is bonded to the front surface 5b of the glass substrate 5 by, for example, a roll lamination method, and the PDP according to the present invention. Configure the front filter for

According to the invention, it is also possible to form another antireflective film on the layer on which the near-infrared blocking and selective light absorption functions are formed to further reduce light reflection on the surface.

As described above, according to the present invention, a transparent glass substrate, an adhesive film, a conductive mesh, a transparent plastic film coated with a dye layer having a near infrared ray blocking function and a color purity improving function by selective absorption are sequentially laminated and Ra is placed thereon. After placing the mirror surface plate having a surface roughness in the range of 0.01 to 0.1㎛ and heat-compression by vacuum thermocompression method, the anti-reflection film is fused to the front surface of the mirror plate to complete the front filter for PDP (Plasma Display Panel). According to the manufacturing of the front filter for the plasma display panel (PDP), the smoothness of the front filter is improved, the distortion of the image is reduced, and the bubble mixing or the pressing mark is reduced, thereby reducing the mixing or pressing marks of the bubble, thereby improving the manufacturing process yield. You can.

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

Example 1

(Step 1) Preparation of near infrared ray blocking and photoselective absorbent coating

1000 ml of methyl ethyl ketone (MEK) was added to the reactor, followed by heating, and 300 g of poly (methyl methacrylate) was completely dissolved. 1 g of octaphenyltetraazapopyrine and 15 g of IRG022 (purchased by Nippon Chemical Co., Ltd.) as disclosed in Korean Patent Publication No. 2001-026838 were dissolved therein. 120 mg of Acridine Orange (Aldrich Chemical) was dissolved in 50 ml of isopropyl alcohol (IPA) and slowly added to the solution to prepare a near-infrared blocking and photoselective light absorbing coating.

(Step 2) film preparation with near-infrared light blocking and photoselective light absorbing layer formed

The coating agent prepared in step 1 was roll coated in a micro gravure method on a high transparency PET film having a thickness of 125 μm, and dried at 100 ° C. to form a near infrared ray blocking and photoselective light absorbing layer having a thickness of about 10 μm.

(Step 3) Preparation of the front optical filter for PDP

As shown in Figs. 1 and 2, an EVA sheet 4 having a thickness of 250 µm, a line width of 10 µm, and a line pitch of 300 µm were formed on the rear surface 5a of the glass 5 having a size of 600x1000 mm and 3 mm, and the opening ratio was 93%. The copper mesh 3 and the film 2 prepared in step 2 were laminated so that the layer 2a including near infrared ray blocking and selective light absorption functions faced the mesh. The laminated body was completed on this laminated body by placing the 1.0-mm-thick SUS mirror plate mirror-processed at 0.04 micrometer of surface roughness Ra. The laminate was charged into a vacuum presser, evacuated for 30 minutes to maintain a vacuum degree of 10 Torr, and then pressed and bonded at a pressure of 10 kgf / cm ² at 120 ° C for 30 minutes. After 30 minutes, the vacuum was broken, cooled for 30 minutes, and taken out, and then the antireflection film 6 was adhered to the front surface 5b of the glass at a speed of 1.0 m / min using a laminator, and the front filter for PDP was attached. Completed.

Example 2

In Example 1, the surface was roughened by using a coextruded microporous white film (Toray® E60L) having a surface roughness Ra of 0.08 μm and a thickness of 188 μm. A filter was prepared.

Comparative Example 1

In Example 1, the front filter was manufactured by the same manufacturing method as in Example 1 using SUS301H having a surface roughness Ra of 0.5 μm and a thickness of 1 mm as a mirror plate.

Comparative Example 2

In Example 1, the front surface filter was manufactured by the same manufacturing method as Example 1 using SUS301H having a surface roughness Ra of 0.3 μm and a thickness of 1 mm as a mirror plate.

Comparative Example 3

In Example 1, the front surface filter was manufactured by the same manufacturing method as Example 1 using the white opacity film (Diafoil, W400) whose surface roughness Ra is 0.3 micrometer and 250 micrometers in thickness as a mirror plate.

Comparative Example 4

In Example 1, the front surface filter was manufactured by the same manufacturing method as Example 1 using PET films (SKC, SH31) having a surface roughness Ra of 0.005 μm and a thickness of 188 μm as a mirror plate.

The appearance inspection of the prepared front optical filters for PDP was carried out under reflected light and transmitted light. Reflected light was installed 1m vertically from the filter, inspected from the filter side, and the filter was installed with black background. The reflected light had a normal diffused fluorescent lamp with a color temperature of 6500K incident on the filter and had an illuminance of about 500 Lux ± 10% at the inspection position. The transmitted light was installed 1m below the filter and inspected from the filter side. The filter was installed in front of the white diffused light source emitted at 250 cd / m ² and the inspector was placed perpendicular to the test surface.

Table 1 shows the visual visual inspection results of the front optical filter for PDP prepared according to Examples 1 and 2 and Comparative Examples 1, 2 and 3.

The smoothness of the filter was 5mm apart on the PDP panel at a distance of 1m after the filter was mounted, and the inspection angle was displayed at 60 degrees on the left and right of the vertical plane, indicating the degree of distortion of the image. The bubble mixing and pressing marks indicated the number of things having a diameter of 1 mm or more.

In Table 1,? Indicates that there is no distortion of the screen at all by visual inspection, and? Indicates that the distortion of the screen is severe over the entire surface when the distortion of the screen is minute.

As described above, the front filter manufactured by the method of Example 1 and Example 2, compared to the case of using a mirror plate having a surface roughness outside the scope of the present invention according to Comparative Examples 1 to 4, image inspection and visual As a result of the visual inspection, there was no distortion of the image and there was no bubble indentation or depression mark in the bubble.

The present invention is to improve the smoothness of the filter by determining the material and surface roughness conditions of the mirror plate used in the manufacturing method of the front filter by the vacuum thermocompression method to reduce the distortion of the phase and to reduce the mixing or pressing marks of the bubble Yield can be improved.

Claims (2)

A transparent plastic film coated with a pigment layer having an adhesive film, a conductive mesh, a near infrared ray shielding function and a color purity improving function by selective absorption, and a mirror plate are sequentially laminated on the transparent glass substrate. In the manufacturing method of the front filter for a plasma display panel (PDP) comprising vacuum-pressing it, the surface roughness Ra of a mirror surface plate is adjusted to the range of 0.01-0.1 micrometer, The manufacture of the front filter for PDP Way. The method of claim 1, The front filter for PDP, characterized in that the material of the mirror plate is metal, plastic or glass.