KR20040067483A - Front filter for plasma display panel and preparation thereof - Google Patents

Abstract

PURPOSE: A front filter and a method for manufacturing the same are provided to reduce the weight and thickness of the filter and manufacturing costs. CONSTITUTION: A front filter comprises an adhesive sheet(2) and a conductive mesh film(3) sequentially stacked on a rear surface(1a) of a transparent glass substrate(1), wherein the adhesive sheet contains a colorant having a near infrared shielding function and a color purity enhancing function; and a step of attaching anti-reflection films(4a,4b) on a front surface(1b) of the transparent glass substrate. A method for manufacturing a front filter, comprises a step of disposing a transparent adhesive sheet between a transparent glass substrate and a conductive mesh film, and vacuum heat pressing the resultant structure. The adhesive sheet contains a colorant having a near infrared shielding function and a selective light absorbing function.

Description

Front filter for plasma display panel and manufacturing method thereof {FRONT FILTER FOR PLASMA DISPLAY PANEL AND PREPARATION THEREOF}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a front filter for a PDP and a method for manufacturing the same, and particularly, in the method of vacuum heat pressing through a transparent adhesive sheet between a transparent glass substrate and a conductive mesh film, a near infrared ray blocking function is applied to the adhesive sheet. The manufacturing method of the front filter for PDP characterized by using what the pigment | dye which has and the pigment | dye which has a photoselective light absorption function is used.

PDP is easier to enlarge than other display devices, and is considered to be a thin light emitting display device having the most suitable characteristics as a high quality digital television in the future. 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 blocking 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 a PDP using two transparent substrates has a disadvantage in that thickness and weight are difficult because of the large thickness and weight.

In order to prevent the remote control from malfunctioning in the PDP front filter, near-infrared cut performance is an important requirement. In particular, in recent years, the near-infrared radiation has been increased as the brightness of the PDP is increased. Blocking performance is required. When an acrylic resin plate is used as the transparent substrate of the front filter for a PDP, the near-infrared cut performance can be imparted by incorporating a copper-based material in the acrylic resin of the substrate material. However, the acrylic resin has a problem in terms of heat resistance and is weak to heat and risks of heat deformation. This 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 which is excellent in heat resistance as a transparent substrate, and to implement the PDP front surface filter 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 adhesive. The method is used a lot.

However, even in the above patents, by using a near-infrared blocking film or an anti-reflection film separately and bonding the film to a transparent glass substrate using an adhesive resin or an adhesive, the thinner and lighter the filter, the more complicated the structure, and the complicated structure, the production cost There is a considerable difficulty in lowering.

The present invention is to improve the above problems, in the present invention, the thermal adhesive sheet used in the manufacturing method of the front filter by the vacuum thermocompression method includes a pigment having a near infrared ray blocking function and a pigment having a light selective absorbing function. It is characterized in that, if the optical filter is manufactured according to the present invention, the filter can be made lightweight and thin, and the structure can be simplified to reduce the manufacturing cost.

1 is a cross-sectional view showing the layer configuration of the front filter for PDP (Plasma Display Panel) manufactured according to the present invention,

2 is a cross-sectional view showing the layer structure of the front filter for PDP prepared according to Comparative Example 1. FIG.

* Brief description of the reference numbers

1: Glass substrate 1a: Glass substrate back side

1b: glass substrate front 2: adhesive sheet

3: mesh 3a: mesh cotton

4a, 4b: antireflection film 5: resin film

5a: NIR shielding and selective light absorption layer

In order to achieve the above object, in the present invention, an adhesive sheet and a conductive mesh film containing a pigment having a near infrared ray blocking function and a color purity improving function by selective absorption are sequentially stacked on the rear surface of the transparent glass substrate, and the front surface of the glass substrate. The present invention provides a front filter for a plasma display panel (PDP) having an antireflection film bonded thereto.

In the present invention, the adhesive sheet in the manufacturing method of the front filter for plasma display panel (PDP) comprising a vacuum heat pressing (Vacuum Heat Pressing) between the transparent glass substrate and the conductive mesh film. Provided are a method for producing a front filter for a PDP, which comprises a dye having a near infrared ray blocking function and a dye having a light selective absorbing function.

Hereinafter, the present invention will be described in more detail.

According to the present invention, a transparent glass substrate, a heat-adhesive sheet containing a pigment having a near infrared ray blocking function and a color purity improving function by selective light absorption, a film in which a conductive mesh is formed in a pattern, and a mirror plate are sequentially laminated. Then, the laminate is compressed by a vacuum thermocompression method, and then the antireflection film is integrated on the entire surface of the laminate to complete a front filter for a plasma display panel (PDP).

That is, the characteristic of the present invention is a pigment having a near infrared ray blocking function as the adhesive sheet and a photoselective light absorption function when vacuum heat pressing through a transparent adhesive sheet between the transparent glass substrate and the conductive mesh film as described above. It is to use what contains the pigment which has.

The heat-adhesive sheet containing a pigment having the near-infrared blocking function and the color purity improving function by selective light absorption may be manufactured and used on a transparent plastic resin film such as PET having a release layer applied thereto, and the thickness of the heat-adhesive sheet is 10 to 500 μm. Sufficient adhesive strength can be obtained when it is in the range, preferably in the range of 50 to 250 μm. If it is thinner than this, the adhesive strength cannot be secured. If it is thicker than this, the melt flow after heating becomes severe and the surface smoothness is lowered.

Hereinafter, referring to the drawings, FIG. 1 is a cross-sectional view showing a layer structure of a front filter for a PDP (plasma display panel) formed according to the present invention, and FIG. 2 is a cross-sectional view showing a layer structure of a front filter for a PDP formed according to a comparative example. to be.

In FIG. 1, first, the heat adhesive sheet 2 forms a release layer on a transparent plastic base film by a conventional method, and the heat-adhesive coating layer 2 in which the near-infrared blocking pigment | dye and a selective absorbing pigment | dye were contained in the upper layer. It can be prepared by forming the coating layer and then releasing the coating layer from the base film.

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 thermal adhesive coating layer is a heat-adhesive resin containing a near-infrared blocking pigment, a selective light-absorbing pigment, a crosslinking agent, and other additives by melt mixing with a solvent in a mixer such as a kneader at a temperature of, for example, about 100 ℃ and the solution is released The layer is formed by coating on the formed 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 an amount of 0.05 to 3% of the total solids.

Ethylene / vinyl acetate (EVA) copolymerization system, polyamide-based, polyurethane-based, polyester-based, olefin-based, acrylic-based, etc. can be used as the thermal adhesive resin, and among them, EVA-based, excellent transparency and abundant types, many kinds It is more preferable because it is excellent in adhesiveness with the optical film and excellent in change with time and durability. Since the heat-adhesive resin is usually a thermoplastic resin, it can be used by molding into a film by extrusion molding and coating, and the amount used is used in an amount of 10 to 80% with respect to the solvent.

Isocyanate type, melamine type, epoxy type, etc. can be used as a crosslinking agent, and 1-5 weight part with respect to a solution is preferable.

In addition, solvents that may be used in the coating solution include toluene, xylene, acetone, methyl ethyl ketone (MEK), propyl alcohol, isopropyl alcohol, methyl cell solution, ethyl cell solution, dimethyl formamide (DMF) and the like.

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

In addition, a UV blocking agent (for example, Tinuvin-based) and the like may be used as an additive, and if more than 0.5 parts by weight of the solution, more than 90% of the UV light is blocked.

As the coating method, a conventional extrusion molding and coating method may be applied. For example, a comma coating or a die coating may be used.

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 conductive mesh 3 is bonded to the rear surface of the glass 1 by using the adhesive sheet 2 including the near-infrared cutoff and the selective light-absorbing dye prepared above.

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.

For example, the adhesive sheet 2, the patterned metal mesh 3, and the mirror plate 4 (located in contact with the mesh surface 3a of the mesh) are sequentially placed on a glass substrate 1, and a vacuum press is then placed. Heated and pressurized.

In the vacuum thermocompression bonding, 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.

As the mirror plate 4 used for vacuum thermocompression bonding, a material made of metal, plastic, glass, or the like is used, and a surface roughness of 0.01 to 0.1 µm and a thickness of 0.1 to 2 mm can be preferably used. If the surface roughness Ra of the mirror plate is less than 0.01 μm, the surface is so smooth that the air layer interposed between the mirror plate and the optical film does not escape and the air mixing layer remains or appears as a pressed mark in the final filter. 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. 1, after taking out the manufactured laminate, the antireflection film 4b is bonded to at least the front surface 1b of the glass substrate 1 by a roll lamination method, and the front filter for PDP according to the present invention is obtained. Configure.

According to the invention, it is also possible to form another antireflective film 4a on the mesh surface of the mesh film to further reduce light reflection on the surface.

When manufacturing the front filter for PDP (Plasma Display Panel) according to the present invention, the smoothness of the front filter is improved, the distortion of the image is reduced, the bubble mixing or the pressing mark is reduced, so that the mixing or pressing mark of the bubble is reduced, the manufacturing process yield Can improve.

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

Example 1

(Step 1) Preparation of heat-adhesive coating liquid containing near infrared ray blocking and photoselective absorbent pigment

300 ml of methyl ethyl ketone (MEK) and toluene solvent were added in a 1: 1 ratio to a disperser, and 300 g of EVA (ethylene / vinylacetate) resin was completely dissolved at room temperature. 1g of octaphenyltetraazapopyrine and 15g 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 an EVA solution containing a near-infrared light blocking and photoselective absorbing pigment. .

(Step 2) Preparation of EVA film containing near infrared ray blocking and photoselective absorbent pigment

The composition prepared in step 1 was coated by a comma coating method on a high-transparent PET film coated with a release layer having a thickness of 125 μm and then dried at 100 ° C. to have a near infrared ray blocking and photoselective absorption function of about 100 μm. A thermal adhesive resin film was formed.

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

As shown in Fig. 1, the EVA film 2 and the line width 10 containing a pigment having a near-infrared blocking and a selective light absorption function having a thickness of 100 μm on the rear surface 1a of the glass 1 having a size of 600 x 1000 x 3 mm The copper mesh film 3 of 93% of aperture ratio was laminated | stacked so that the mesh surface 3a may be located in outermost at micrometer and line pitch 300micrometer. The laminated body was completed by putting SUS mirror plate of thickness 1mm which was grind | polished with # 1000 sandpaper on this laminated body, and the surface roughness Ra was mirror-processed to 0.04 micrometer. 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 about 30 minutes, and taken out, and then the antireflection films 4b and 4a were laminated to the front and rear surfaces 1a and 1a of the laminate using a laminator at a speed of 1.0 m / min. It adhered to and completed the front filter for PDP.

Comparative Example 1

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

300 ml of methyl ethyl ketone (MEK) and toluene solvent were added to the reactor in a 1: 1 ratio, and 300 g of poly (methyl methacrylate) was added at room temperature to completely dissolve it. 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 light 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 Fig. 2, a copper mesh having an opening ratio of 93% with an EVA sheet 2 having a thickness of 250 µm and a line width of 10 µm and a line pitch of 300 µm on the rear surface 1a of the glass 600 having a size of 600x1000 mm and 3 mm. (3) and the film (5) prepared in step 2 were laminated so that the layer (5a) containing the near infrared ray blocking and selective light absorption function faces the mesh. The laminated body was completed on this laminated body by placing the 1 mm-thick SUS mirror surface mirror-surface-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 about 30 minutes, and taken out, and then the antireflection films 4b and 4a were laminated to the front and rear surfaces 1a and 1a of the laminate using a laminator at a speed of 1.0 m / min. It adhered to and completed the front filter for PDP.

The front and rear optical filters for the PDP prepared in Examples and Comparative Examples were mounted on the PDP, and then the front and rear luminance was measured using a colorimeter (manufactured by Japan Minolta, model name CS1000). Table 1 shows white light transmittance, near infrared transmittance (850 nm) and Ne light transmittance (590 nm) before and after PDP mounting of the front optical filter for PDP prepared according to Example 1 and Comparative Example 1.

Luminance (cd / cm2) White light transmittance (%) Near infrared ray transmittance (%) Ne light transmittance (%) Before filter installation 104 100 - - Example 1 67.6 55 8.5 29 Comparative Example 1 57.2 53 8.0 28

As described above, the luminance of the front filter manufactured in Example 1 was measured, and the transmittance of the filter was 55%. In addition, the weight of the filter was also reduced by about 5% and the total thickness was also reduced compared to the comparative filter prepared by separately adhering a dye film having a near infrared cut-off and a photoselective light-absorbing layer on a glass of 3mm thickness.

In addition, by simplifying the structure in the manufacturing process it was possible to improve the yield and to realize a low price.

The present invention relates to a method of manufacturing an optical filter by vacuum heat pressing through a transparent adhesive sheet between a transparent glass substrate and a conductive mesh film, wherein the dye having a near infrared ray blocking function and the dye having a light selective absorbing function are By using the included thermal adhesive sheet, the transmittance can be improved by reducing the laminated body that reduces the brightness of the filter by half, and the weight and thickness of the filter can be improved, and the manufacturing cost can be reduced by simplifying the structure.

Claims (8)

Plasma display in which an adhesive sheet containing a pigment having a near infrared ray blocking function and a color purity enhancement function by selective absorption and a conductive mesh film are sequentially stacked on the rear surface of the transparent glass substrate, and an antireflection film is bonded to the front surface of the glass substrate. Front filter for panel (PDP). The method of claim 1, A front filter for a PDP, wherein the near-infrared blocking dye is a dye or an organic dye containing a mixed complex of a nickel complex system and a diimmonium compound, a compound containing copper or zinc ions. The method of claim 1, The near-infrared blocking pigment is contained in the sheet in an amount of 1 to 20% by weight, PDP front filter. The method of claim 1, The photo-selective light-absorbing dye, PDP characterized in that the metal (M) element in the tetraazapopyrine is a derivative pigment formed of a coordination bond with the metal element any one material in the group consisting of ammonia, water and halogen Front filter. The method of claim 1, The front filter for a PDP, characterized in that the photo-selective light-absorbing dye is contained in an amount of 0.05 to 5% by weight in the sheet. The method of claim 1, An antireflection film is further bonded onto a conductive mesh film, wherein the front filter for a PDP is used. A method of manufacturing a front filter for a plasma display panel (PDP) comprising vacuum heat pressing through a transparent adhesive sheet between a transparent glass substrate and a conductive mesh film. A method of producing a front filter for a PDP, comprising using a dye having and a dye having a light selective absorption function. The method of claim 7, wherein Method for producing a front filter for a PDP, characterized in that for use in mirror thermocompression surface roughness of 0.01 to 0.1㎛ range.