JP2005249854A - Optical filter and plasma display panel - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical filter which can be directly pasted onto a plasma display panel, adds impact resistance to the plasma display panel and has superior transparency. <P>SOLUTION: The optical filter is to be directly pasted on a display surface of the plasma display panel, and has an antiimpact layer having a Shore D hardness of <65. The antiimpact layer has an internal haze of 0.1 to 3.0%, and a thickness of 0.5 to 3.0 mm. The destruction energy by an impact test conducted for the plasma display panel is equal to or greater than 0.5 J when the optical filter is pasted onto the plasma display panel. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an optical filter that can be directly attached to a plasma display panel and can impart impact resistance to the plasma display panel, and a plasma display panel having the optical filter attached thereto.

  In recent years, plasma display devices have been developed and commercialized for use in large thin televisions, thin display applications, and the like. Due to the structure of this plasma display device, near-infrared rays that cause malfunctions to other devices and affect the operation of remote control, and neon light that affects color tone are emitted from the inside of the display, thus blocking them. There is a need. Further, since electromagnetic waves are generated from the plasma display device, it is required to reduce the intensity of electromagnetic wave emission within the standard in consideration of the influence on the human body.

  In view of these requirements, various filters have already been developed for application to plasma display panels. For example, Japanese Patent Application Laid-Open No. 2000-59083 (Patent Document 1) discloses an electromagnetic wave shielding effect, near-infrared cut, and color correction. An optical filter in which antireflection layers are accumulated is disclosed. Such an optical filter is basically required to have excellent transparency.

  On the other hand, the plasma display device is required to be lighter and thinner as the size of the device increases, and the impact resistance of the plasma display panel with an optical filter is increasingly required.

  However, the problem to be solved is how to improve the sufficient impact resistance of the plasma display and how much impact resistance is necessary in the state where the optical filter having each function is combined with the plasma display panel. became. In addition, when a solvent-drying resin is applied to form an impact-resistant layer, fine bubbles cannot be removed from the coating film during drying, so transparency is required for plasma display panels. This optical filter cannot be used because the haze is too high. In addition, in the case of a thermosetting resin, there is a problem that the dye such as a near-infrared absorbing dye or a neon light absorbing dye contained in the filter at the time of heating is altered. Further, the thickness of the impact resistant layer must be reduced in accordance with the demand for thinning the plasma display, but it is necessary to ensure the necessary impact resistance.

  Japanese Patent Application Laid-Open No. 2002-260539 (Patent Document 2) discloses a plasma display panel in which an optical filter having an antireflection film is attached to the front surface of a plasma display via an adhesive layer. Since the optical filter attached to the plasma display panel of Patent Document 2 has improved impact resistance on the adhesive layer, impact resistance and adhesiveness are required. In Example 1 of Patent Document 2, an adhesive sheet formed by melting an acrylic acid copolymer into a sheet shape is attached to an optical filter, and then attached to a plasma display. Moreover, in Example 2 of Patent Document 2, in order to attach a filter to the front surface of the plasma display, transparent thermosetting silicone is used and bonded together by keeping the distance between the display and the filter at 1 mm. However, the method of adhering the optical filter and the plasma display as in Example 2 has a problem in that productivity is poor and yield is low because it requires silicone pouring and heat treatment. Furthermore, the optical filter including the pressure-sensitive adhesive layer of Patent Document 2 does not show any degree of transparency which is a basic requirement of the optical filter itself.

Japanese Patent Laid-Open No. 2002-23649 (Patent Document 3) requires a complicated multilayer structure including a scattering prevention layer, two types of crack prevention layers, and a transparent adhesive layer in order to constitute an impact relaxation laminate. Yes.
JP 2000-59083 A JP 2002-260539 A JP 2002-23649 A

  In view of the problems of the prior art described above, the present invention constitutes an optical filter incorporating a specific impact resistant layer, and has sufficient impact resistance when the optical filter is attached to a plasma display panel. Moreover, it is an object of the present invention to provide a thin optical filter excellent in transparency by preventing bubbles from being contained in the impact resistant layer, and to provide a plasma display panel having the optical filter attached thereto.

  A further object of the present invention is to provide an optical filter having antireflection properties in addition to the optical filter having the above properties.

  A further object of the present invention is to provide an optical filter provided with a near-infrared absorbing resin layer in addition to the optical filter having the above properties.

  A further object of the present invention is to provide an optical filter provided with a neon light absorbing resin layer in addition to the optical filter having the above properties.

  Furthermore, an additional object of the present invention is to provide an optical filter having high transparency in addition to the optical filter having the above properties.

  A further object of the present invention is to provide an optical filter in which static electricity and / or electromagnetic wave noise is suppressed in addition to the optical filter having the above properties.

  A further object of the present invention is to provide a plasma display panel in which an optical filter having the above properties is attached to a display surface.

  The optical filter of the present invention is (1) an optical filter for being directly attached to a display surface of a plasma display panel, and (2) an impact resistant layer having a Shore D hardness of less than 65% in the optical filter. (3) The impact resistant layer has an internal haze of 0.1 to 3.0 and a thickness of 0.5 mm to 3.0 mm. (4) When the optical filter is attached to a plasma display panel The destruction energy by the impact test for the plasma display panel is 0.5 J or more.

  The plasma display panel of the present invention is required to have a Shore D hardness of less than 65 in the optical filter. When the Shower D hardness is 65% or more, the coating film is too hard to exhibit impact resistance. In the present invention, Shower D hardness is defined by ASTM D2240, ISO 868. In addition, since it is difficult to measure if the Shower D hardness is less than 45% (corresponding to less than Shower A hardness 95), the measurement of Shower D hardness less than 45% was measured by Shower A hardness. The Shower A hardness was based on the measuring method by JISK7311-1995.

  The impact resistant layer in the optical filter of the present invention must have a thickness of 0.5 mm to 3.0 mm, and if it is less than 0.5 mm, it can achieve a fracture energy of 0.5 J or more in an impact test. If it exceeds 3.0 mm, haze increases and transparency is lost. The resin used for the impact resistant layer is preferably a polyurethane resin. The reason for this is that a soft resin is usually used as the resin suitable for the impact resistant layer. However, when the impact resistant layer is produced using a soft resin, a depression occurs during the manufacturing process or during handling. The polyurethane resin is preferable because it has a high restoring force when a depression is generated.

  The impact test is performed using the impact test apparatus shown in FIG. 4, and a steel ball 12 (mass 534 g) having a diameter of 9.6 cm to a diameter of 50.8 mm (specified in a steel ball for JIS B1501 ball bearing) is dropped. This was done by measuring the breaking energy at the time. As the test stand 8, a SUS base 9 and a 10 mm thick glass plate 10 bonded together were used. On the test stand 8, a high strain point glass plate (PD-200: trade name, thickness 2.8 mm) manufactured by Asahi Glass Co., Ltd. was placed as the front glass plate 11 for plasma display. PD-200 is a front glass plate 11 for plasma display that is commonly used by plasma display manufacturers. The reason why the front glass plate 11 is directly placed on the test table 8 is to eliminate the cushioning property by the casing of the plasma display.

  The resin used for producing the impact resistant layer in the optical filter of the present invention is preferably a polyurethane-based resin, and more preferably, an oligomer having 1 to 3 (meth) acrylic groups at the terminal is radically polymerized. It is a urethane resin. In this specification, a (meth) acryl group means an acryl group or a methacryl group.

  In the optical filter of the present invention, an antireflection film is preferably provided in the layer structure, and an antireflection film is preferably provided on the outermost layer.

  The optical filter of the present invention preferably has a resin layer containing a near-infrared absorbing compound such that the transmittance in the wavelength range of 800 to 1000 nm is 20% or less in the layer configuration.

  The optical filter of the present invention has a resin layer containing a neon light absorbing compound having a maximum absorption wavelength in the wavelength range of neon light 560 to 630 nm in the layer configuration, and the transmittance of the maximum absorption wavelength in the wavelength range is 40. % Or less is desirable.

  As for the optical filter of this invention, it is desirable that the transmittance | permeability of the wavelength range of visible light 380-780 nm is 40% or more.

  The optical filter of the present invention desirably has an electromagnetic wave shielding layer for shielding static electricity and / or electromagnetic wave noise generated from the plasma display device in the layer structure.

  The optical filter of the present invention can be provided with an adhesive layer for adhering to a plasma display panel.

  The plasma display panel of the present invention can be configured by attaching the optical filter of the above-described form to a display surface through an adhesive layer.

  Since the optical filter having the impact resistant layer of the present invention has excellent impact resistance and transparency, the plasma display panel incorporating the optical filter of the present invention has excellent impact resistance and also excellent transparency.

  FIG. 1 is a view showing an example of a laminated structure when an optical filter provided with an impact resistant layer of the present invention is attached to the front surface of a plasma display. Reference numeral 5 denotes an electromagnetic wave shielding layer, which is obtained by processing a metal foil bonded to a transparent substrate with an adhesive into a mesh shape by etching, and has an electromagnetic wave shielding ability. Reference numeral 4 denotes a dye-containing pressure-sensitive adhesive layer, which has the effect of flattening the unevenness of the mesh-like metal (metal mesh) in the electromagnetic wave shielding layer 5 and at the same time filling the steps of the fine unevenness of the adhesive remaining in the recesses by etching. Reference numeral 3 denotes an impact resistant layer, and an antireflection layer 1 is formed on the impact resistant layer 3. Since the polyurethane resin used for the impact resistant layer 3 in the optical filter of the present invention has adhesiveness when heated, the impact resistant layer 3 and the antireflection layer 1 can be directly adhered without interposing an adhesive layer. . The antireflection layer 1 may be formed on the impact resistant layer 3 via an adhesive layer (not shown). The optical filter composed of these layers is attached to the surface of the plasma display panel 7 through the adhesive layer 6.

  FIG. 2 is a diagram showing another example of a laminated structure when the optical filter provided with the impact resistant layer of the present invention is attached to the front surface of the plasma display. In the embodiment of FIG. 2, the impact-resistant layer 3 is sandwiched between the antireflection layer 1 and the electromagnetic wave shielding layer 5, and a dye-containing colorant layer 4 is provided on the unevenness of the metal mesh of the electromagnetic wave shielding layer 5. It is a thing. The optical filter composed of these layers is attached with the dye-containing pressure-sensitive adhesive layer 4 side facing the surface of the plasma display panel 7.

  FIG. 3 is a view showing still another example of a laminated structure in the case where an optical filter provided with an impact resistant layer of the present invention is attached to the front surface of a plasma display. The optical filter of the embodiment of FIG. 3 is prepared as follows. In order to prepare an electromagnetic wave shielding layer 5 formed by etching a metal foil bonded with an adhesive on a transparent substrate into a mesh shape, and to flatten the unevenness of the metal mesh in the electromagnetic wave shielding layer 5, From the electromagnetic wave shielding layer 5 / the dye-containing pressure-sensitive adhesive layer 4 / the anti-reflection layer 1, the dye-containing pressure-sensitive adhesive layer 4 is provided on the electromagnetic wave shielding layer 5, and the anti-reflection layer 1 is further provided on the dye-containing pressure-sensitive adhesive layer 4. A laminate is prepared. On the other hand, a laminate comprising a PET film separator 15 / adhesive layer 6 / PET film separator 15 was prepared, and the electromagnetic wave shielding layer 5 / dye-containing pressure sensitive adhesive layer 4 / antireflection layer with the electromagnetic wave shielding layer 5 side inward. The impact resistant layer 3 is sandwiched between the laminate composed of the layer 1 and the laminate composed of the PET film separator 15 / adhesive layer 6 / PET film separator 15, and the adhesive property of the impact resistant layer 3 is utilized. Thus, an optical filter is obtained by stacking.

  In order to attach the optical filter to the surface of the plasma display panel 7, the outer PET film separator 15 is peeled off and the adhesive layer 6 side is attached to the surface of the plasma display panel 7.

  1 to 3, a dye such as a near-infrared absorbing dye and / or a neon light absorbing dye is contained in the dye-containing pressure-sensitive adhesive layer 4, but it may be contained in any layer constituting the optical filter. Is possible.

  Hereinafter, each layer used for the layer structure of the optical filter when the optical filter of the present invention is applied to a plasma display will be described as an example.

Impact resistant layer :
As the resin used for the impact resistant layer in the optical filter of the present invention, a polyurethane resin is preferably used. Since the resin has adhesiveness when heated, it is suitable for laminating with other layers by heating and pressing. In addition, when using a urethane-based resin obtained by radical polymerization of an oligomer having 1 to 3 (meth) acrylic groups at the terminal, a resin or solvent dissolved in a solvent or monomer is applied and cured by ultraviolet irradiation or the like. A method of forming an impact resistant layer is suitable.

  The polyurethane resin used in the present invention refers to one synthesized by polyaddition of diisocyanate and diol. Examples of the type of urethane-based resin used in the present invention include, as diols, polyester-based polyols, polyether-based polyols, and polycarbonate-based polyols. Isocyanates include tolylene diisocyanate (TDI) and 4,4′-diphenylmethane. Diisocyanate (MDI), xylylene diisocyanate (XDI), hexamethylene diisocyanate (HDI), 4,4′-methylenebiscyclohexyl isocyanate (HMDI), isophorone diisocyanate (IPDI), and various combinations thereof The urethane type resin is mentioned.

(Formation of impact-resistant layer and production of optical filter and sticking to plasma display panel)
The impact-resistant layer can be formed in the optical filter of the present invention by any method, but preferably, an extrusion laminating method, a thick coating method, etc., which will be described below, are mentioned. The impact resistant layer is preferably used in the form of a film. Usually, it is extruded onto a support film to form a support film / urethane resin film laminate structure, or more preferably a protective film (separator film) provided, that is, a support film / urethane resin film / protection film laminate A structure is preferable. As the support film, for example, a film that becomes an antireflection layer, a film that becomes an electromagnetic wave shielding layer, or a laminated film in which a dye-containing adhesive layer of the electromagnetic wave shielding layer is laminated can be applied.

i) Extrusion Laminating Method FIG. 5 is a view showing an example of an extrusion laminating machine for forming a preferable impact resistant layer in the optical filter of the present invention. In order to form the impact resistant layer in the optical filter of the present invention, the extruded polyurethane machine shown in FIG. A laminate having a shock-resistant layer is obtained.

  In one example of a specific manufacturing method for obtaining the optical filter having the layer configuration of FIG. 1, as one film, a separator film 31 is placed in a wound state in the first film supply unit 35, and the other film As a laminated film 34 (transparent substrate film 32 / antireflection layer 1 / protective film 33) composed of the antireflection layer 1 formed on the transparent substrate film 32 and the protective film 33 stuck on the antireflection layer 1. It arrange | positions to the 2nd film supply part 39 in the winding state. While the separator film 31 is unwound from the first film supply unit 35 and the laminated film 34 is unwound from the second film supply unit 39, the polyurethane resin is extruded into a film form from the die 42 of the extrusion laminator. At this time, lamination is performed by passing between the cooling roll 37 and the nip roll 38 while sandwiching the polyurethane resin film between the separator film 31 and the laminated film 34 with the transparent base film 32 side inside. Then, the laminated film 36 having a polyurethane resin as an impact resistant layer is wound around the paper discharge unit 41.

  On the other hand, a laminated film composed of the dye-containing pressure-sensitive adhesive layer 4 / the electromagnetic wave shielding layer 5 is prepared. The electromagnetic wave shielding layer 5 is obtained by laminating a metal mesh layer on a transparent substrate with an adhesive layer interposed therebetween. The separator film 31 of the laminated film 36 obtained in the above process is peeled off and the side on which the impact resistant layer 3 is exposed is laminated with the dye-containing pressure-sensitive adhesive layer 4 of the laminated film 36. Next, a material having a separator film attached to both sides of the pressure-sensitive adhesive layer 6 is prepared. One of the separator films is peeled off to expose the pressure-sensitive adhesive layer 6, and the electromagnetic wave shielding layer 5 of the laminate obtained in the above step is transparent. An optical filter is obtained by attaching to the substrate side.

  Next, the separator film remaining on the pressure-sensitive adhesive layer 6 is peeled off and the obtained optical filter is attached to the surface of the plasma display panel 7. Finally, the protective film 33 on the antireflection layer 1 is peeled off.

ii) Sheet Forming Method FIG. 6 is a schematic view showing an example of a sheet molding machine suitable for forming an impact resistant layer containing a polyurethane resin as an impact resistant layer in the optical filter of the present invention. In FIG. 6, 21-1, 21-2, and 21-3 are hoppers for accommodating the polyurethane-based resin. When producing an impact-resistant layer made of a single urethane resin, the same polyurethane resin is accommodated in three hoppers. Each polyurethane resin supplied from the hoppers 21-1, 21-2, and 21-3 is heated from room temperature to about 150 ° C. and supplied to the die 23, and each resin forming the three layers is about 160 to 200. The laminated sheet 25 is discharged from the three types of manifolds 24-1, 24-2 and 24-3, which are heated to 0 ° C. and combined at the front ends. The discharged laminated sheet 25 is introduced between the three cooling rolls 26-1, 26-2, 26-3, and the laminated sheet 25 cooled to about 30 to 60 ° C. is discharged by the paper discharge device 27. Paper is produced and an impact resistant layer is produced.

  In order to form the optical filter shown in FIG. 8, the impact resistant layer 3 obtained by the above sheet molding method is bonded to the back surface of the antireflection layer 1 through the adhesive layer 6 made of an adhesive, and the reflection is performed. A laminated sheet comprising the prevention layer 1 / adhesive layer 6 / impact resistant layer 3 is obtained. On the other hand, the pressure-sensitive adhesive layer 6 is laminated by applying a pressure-sensitive adhesive to the transparent base material side of the electromagnetic wave shielding layer 5, and the dye-containing pressure-sensitive adhesive is further applied to the metal mesh surface of the electromagnetic wave shielding layer 5. Layer 4 is laminated to obtain a laminated sheet comprising dye-containing pressure-sensitive adhesive layer 4 / electromagnetic wave shielding layer 5 / pressure-sensitive adhesive layer 6. Next, a laminated sheet composed of the antireflection layer 1 / adhesive layer 6 / impact resistant layer 3 obtained in the step, and the dye-containing adhesive layer 4 / electromagnetic wave shielding layer 5 / adhesive layer 6 obtained in the step. 8 is obtained by pressing the laminated sheet comprising the impact-resistant layer 3 and the dye-containing pressure-sensitive adhesive layer 4 so as to face each other.

  It can be affixed to the surface of the plasma display panel 7 using the adhesiveness of the adhesive layer 6 of the optical filter of FIG.

iii) Thick coating method In order to form the impact-resistant layer 3 of the optical filter shown in FIG. 2, the (meth) acrylate group at the terminal is preferably diluted to the back surface of the antireflection layer 1 and preferably diluted to a viscosity suitable for coating. adding a photoinitiator to an oligomer having one to three to coating solution 500g / m ² ~5000g / m ² coating comprising.

  The coating method is preferably a general thick coating method such as lip coating or die coating. The coating film formed on the antireflection layer 1 is irradiated with UV to produce an impact resistant layer 3 made of a tacky urethane resin coating. Since this urethane-based resin coating is sticky, the dye-containing pressure-sensitive adhesive is obtained by applying a dye-containing pressure-sensitive adhesive to the metal mesh side of the electromagnetic wave shielding layer 5 after pasting the electromagnetic wave shielding layer 5 by this adhesiveness. The agent layer 4 is formed to obtain an optical filter. Due to the adhesiveness of the formed dye-containing pressure-sensitive adhesive layer 4, an optical filter can be attached to the surface of the plasma display panel 7 and used.

  FIG. 7 shows an apparatus for forming an impact resistant layer by die coating. The separator film 31 is placed on the first film supply unit 35 in a wound state, and the polyurethane film is discharged from the die coat head 43 while the separator film 31 is being wound, so that the separator film 31 is thickly coated. . Next, the coated film is cured by irradiating ultraviolet rays with UV irradiation devices 44-1 and 44-2, and then a laminate having an adhesive impact resistant layer made of polyurethane resin as an impact resistant layer is applied to the paper output unit 41. Wind up.

  On the other hand, the electromagnetic wave shielding layer 5 is prepared. The impact-resistant layer 3 side of the laminate obtained in the above process is bonded to the electromagnetic wave shielding layer 5 using the adhesiveness of the impact-resistant layer 3, and then a dye-adhesive is applied to the dye-adhesive layer 4 Then, the antireflection layer 1 is formed to obtain an optical filter.

  In order to laminate the optical filter obtained in the above process on the surface of the plasma display panel 7, the dye adhesive layer 4 side is stuck on the surface of the plasma display panel 7.

In order to produce the optical filter shown in FIG. 3, a protective film made of PET film (a separator film is prepared and diluted to a viscosity suitable for coating on one side of the separate film, preferably with a (meth) acrylic group at the end. 1-3 having oligomer (photoinitiator added product) of 500g / m ² ~5500g / m ² to the coating. coating method, for example, lip coating, die coating, etc., typical thick coating coat method is preferable This coating film is irradiated with UV to form a tacky urethane adhesive coating film, which is formed in the same manner as the impact-resistant layer forming apparatus shown in FIG. .

  On the other hand, an electromagnetic wave shielding layer 5 bonded through the antireflection layer 1 and the dye-containing pressure-sensitive adhesive layer 4 is prepared, and formed on the transparent substrate side of the electromagnetic shielding layer 5 and the separator film obtained in the above step. An optical filter is obtained by laminating the impact resistant layer.

  In order to laminate the optical filter obtained in the above process on the surface of the plasma display panel 7, the separator film is peeled off, and the exposed adhesive layer 6 side is stuck on the surface of the plasma display panel 7.

In order to produce the optical filter shown in FIG. 9, a protective film (release film) made of polyethylene terephthalate is prepared, and one side of the protective film, preferably diluted to a viscosity suitable for coating, ) oligomer having 1-3 acrylic group (photoinitiator added product) of 500g / m ² ~5000g / m ² to the coating. As the coating method, for example, a general thick coating method such as lip coating or die coating can be preferably applied, and more specifically, the above-described apparatus for forming an impact resistant layer by die coating in FIG. 7 can be used. . The obtained coating film is irradiated with UV to form an impact resistant layer 3 composed of a coating film of adhesive urethane resin.

  On the other hand, a laminate in which the dye-containing pressure-sensitive adhesive layer 4 is formed on the metal mesh side of the electromagnetic wave shielding layer 5 and the antireflection layer 1 is further formed on the dye-containing pressure-sensitive adhesive layer 4 is prepared. 9 is bonded to the transparent substrate side of the electromagnetic shielding layer 5 and the impact-resistant layer 3 formed on the protective film (release film) made of polyethylene terephthalate obtained in the above step. The optical filter is obtained.

  What peeled off the protective film (release film) of the optical filter obtained at the said process is affixed on the surface of the plasma display panel 7. FIG.

Electromagnetic wave shielding layer :
The electromagnetic wave shielding layer 5 has a laminated structure in which a transparent substrate, an adhesive layer (not shown), and a metal mesh layer are laminated in this order.

(Metal mesh layer)
The metal mesh layer is a partial layer constituting the electromagnetic wave shielding layer 5 having a laminated structure. The metal mesh layer used in the present invention has a function of shielding electromagnetic waves generated from a plasma display or the like. Such a metal mesh layer is formed by laminating a metal foil on a transparent substrate, which will be described later, with an adhesive layer and etching the metal foil into a mesh shape. In the present invention, the metal mesh layer is not particularly limited as long as the metal mesh layer has electromagnetic wave shielding properties. For example, copper, iron, nickel, chromium, aluminum, gold, silver, Stainless steel, tungsten, titanium, or the like can be used. In the present invention, among the above, copper is preferable from the viewpoints of electromagnetic shielding properties, etching processing suitability, and handling properties. Moreover, as a kind of copper foil used, although rolled copper foil, electrolytic copper foil, etc. are mentioned, it is especially preferable that it is electrolytic copper foil. As a result, a uniform metal mesh layer having a thickness of 10 μm or less can be obtained, and when the surface of the metal mesh layer is blackened, the adhesion with chromium oxide or the like is good. Because it can be.

  Here, in the present invention, it is preferable that one side or both sides of the metal foil is blackened. The blackening process is a process of blackening the surface of the metal mesh layer with chromium oxide or the like. In the optical filter, the oxidation-treated surface is arranged to be a surface on the viewer side. The external light on the surface of the optical filter is absorbed by chromium oxide or the like formed on the surface of the metal mesh layer by this blackening treatment, so that it is possible to prevent light from being scattered on the surface of the optical filter and to achieve good transmission. Therefore, the optical filter can be obtained. Such a blackening treatment can be performed by applying a blackening treatment liquid to the metal foil.

As a blackening treatment method, different oxycarboxylic acid compounds such as tartaric acid, malonic acid, citric acid, and lactic acid are added to a CrO ₂ aqueous solution or a chromic anhydride aqueous solution to convert a part of hexavalent chromium into trivalent chromium. The reduced solution or the like can be applied by a roll coating method, an air curtain method, an electrostatic atomization method, a squeeze roll coating method, a dipping method or the like and dried. In addition, this blackening process may be performed after a metal foil is bonded to a transparent substrate with an adhesive layer or an adhesive layer and etched into a mesh shape.

  The black density on the surface of the blackened metal foil is preferably 0.6 or more. This is because the non-visibility can be further improved. Here, the black density is set to the density standard ANSI T as the observation viewing angle 10 °, the observation light source D50, and the illumination type using GRETAG SPM100-11 (trade name, manufactured by KIMOTO Co., Ltd.) of COLOR CONTROL SYSTEM. It is a value measured after white calibration.

  The film thickness of the metal foil is preferably in the range of 1 μm to 100 μm, more preferably in the range of 5 μm to 20 μm. If the film thickness is thicker than the above range, it is difficult to make the pattern line width fine and fine by etching, and if the film thickness is thinner than the above range, sufficient electromagnetic shielding properties cannot be obtained.

  Furthermore, it is preferable that the said metal foil has the 10-point average roughness based on JISB0601 in the range of 0.5 micrometer-10 micrometers. When it is smaller than the above range, even when the blackening treatment is performed, the external light on the surface of the optical filter is specularly reflected, so that the visibility is deteriorated. This is because it becomes difficult to apply the resist or the resist.

  Here, the etching of the metal foil is performed after the metal foil is bonded to the transparent substrate described later via an adhesive layer or an adhesive layer. This etching can be performed by an ordinary photolithography method. For example, the resist can be applied to the surface of the metal foil, dried, and then exposed to light with a pattern plate and developed.

The above-described metal mesh layer used in the present invention preferably has a surface resistance in the range of 10 ⁻⁶ Ω / □ to 5 Ω / □, and more preferably in the range of 10 ⁻⁴ Ω / □ to 3Ω / □. . In general, the electromagnetic wave shielding property can be measured by surface resistance. It can be said that the lower the surface resistance, the better the electromagnetic wave shielding property. Here, the value of the surface resistance is measured by the method described in JIS K7194 “Resistivity test method using 4-probe method of conductive plastic” by a surface resistance measuring device Lorester GP, manufactured by Dia Instruments Co., Ltd. Value.

  The metal mesh layer after the etching treatment is preferably in the range of 50 μm □ to 500 μm □, more preferably in the range of 100 μm □ to 400 μm □, and particularly preferably in the range of 200 μm □ to 300 μm □. Is preferably in the range of 5 μm to 20 μm. When the mesh line width is finer than the above range, disconnection may occur, which is not preferable from the aspect of electromagnetic shielding properties, and when the mesh line width is thicker than the above range, the visible light transmittance is low, for example, This is because the brightness of the plasma display is not preferable.

Transparent substrate:
The transparent substrate is a part of the layers constituting the electromagnetic wave shielding layer 5 having a laminated structure. The transparent substrate used in the present invention is not particularly limited as long as it has transparency and an adhesive layer can be formed. For example, polyethylene terephthalate (PET), polyethylene naphthalate (PEN) ), Etc., polyolefins such as cyclic polyolefin, polyethylene, polypropylene, polystyrene, etc., vinyl resins such as polyvinyl chloride and polyvinylidene chloride, polycarbonate, acrylic resin, triacetyl cellulose (TAC), polyethersulfone, poly A film made of ether ketone and having a light transmittance of 80% or more in the visible region can be mentioned.

  These films may be colored as long as they do not interfere with the object of the present invention, and can be used as a single layer, but may be used as a multilayer film in which two or more layers are combined. Among these, PET is most preferable from the viewpoints of transparency, heat resistance, cost, and handleability. It is desirable that the light transmittance in the visible region is as high as possible. However, since the light transmittance of 50% or more is required for the final product, even when at least two sheets are laminated, the transparent substrate has 80%. This is because it suits the purpose. Since the higher the transmittance, the more transparent substrates can be laminated, the light transmittance is preferably 85% or more, and most preferably 90% or more. Therefore, it is also an effective means to reduce the thickness. It is. The thickness of the transparent substrate is not particularly limited as long as the transparency is satisfied, but is preferably in the range of 12 μm to 300 μm from the viewpoint of workability. If the thickness is less than 12 μm, the film is too flexible, and the metal mesh layer, which is a conductive layer, is easily stretched and wrinkled due to the tension during film formation and processing. . If it exceeds 300 μm, the flexibility of the film decreases, and continuous winding in each step is difficult and unsuitable. Furthermore, when laminating a plurality of sheets, there is a problem that workability is greatly deteriorated.

Adhesive layer:
The adhesive layer is a layer present in the electromagnetic wave shielding layer in the optical filter attached to the front surface of the plasma display panel of FIGS. 1 to 3, and is a layer used for bonding the transparent substrate and the metal foil (see FIG. 1 to 3). The type of the adhesive layer is not particularly limited as long as the adhesive layer is a layer capable of bonding the metal mesh layer and the transparent base material. In the present invention, the metal mesh layer is configured. Since the metal foil and the transparent base material are bonded together via the adhesive layer, and then the metal foil is meshed by etching, the adhesive layer preferably has etching resistance. Specifically, acrylic resin, polyester resin, polyurethane resin, polyvinyl alcohol alone or partially saponified product thereof, vinyl chloride-vinyl acetate copolymer, ethylene-vinyl acetate copolymer, polyimide resin, epoxy resin, polyurethane ester resin Etc. The adhesive layer used in the present invention may be an ultraviolet curable type or a thermosetting type. In particular, an acrylic resin or a polyester resin is preferable from the viewpoints of adhesion to a transparent substrate, compatibility with near-infrared absorbing dyes and / or neon light absorbing dyes, dispersibility, and the like.

  Further, the adhesive layer may contain one or more near infrared absorbing dyes and / or neon light absorbing dyes. In that case, it is preferable that the light transmittance in the near infrared region is 20% or less, particularly 10% or less, and the light transmittance at 570 to 600 nm is 30% or less, especially 25% or less. Furthermore, the hydroxyl value and acid value of the resin must each be 10 or less. Thereby, it is possible to prevent the near-infrared absorbing dye and / or the neon light-absorbing dye from reacting with the reactive group in the resin due to the hydroxyl group and acid contained in the resin, stably absorbing near-infrared light, and / or Alternatively, the neon light absorbing function can be exhibited.

  The transparent substrate and the metal foil for forming the metal mesh layer can be bonded via the adhesive layer by a dry lamination method or the like. Moreover, it is preferable that the film thickness of this adhesive bond layer is in the range of 0.5 μm to 50 μm, especially 1 μm to 20 μm. Thereby, a transparent base material and a metal mesh layer can be firmly bonded, and the transparent base material is prevented from being affected by an etching solution such as iron oxide during etching to form the metal mesh layer. Because it can.

Dye-containing adhesive layer :
As shown in FIGS. 1 to 3, the dye-containing pressure-sensitive adhesive layer 4 used in the optical filter of the present invention is a layer for flattening the unevenness of the above-described metal mesh layer having electromagnetic shielding properties. It has a function of preventing the transparency of the optical filter from being lowered due to the unevenness of the layer. In addition, the etching performed when forming the metal mesh layer can improve the transparency that is deteriorated due to deterioration of the surface of the adhesive layer, and also prevent irregular reflection of the cross section when the metal mesh layer is viewed obliquely. Is possible. The type of the dye-containing pressure-sensitive adhesive layer 4 used in the present invention is not particularly limited as long as it can flatten the unevenness of the metal mesh layer, but in the present invention, the dye-containing pressure-sensitive adhesive layer 4 is not limited. The glass transition temperature (Tg) of the resin used for the agent layer 4 is preferably in the range of 30 ° C to 150 ° C, and more preferably in the range of 40 ° C to 120 ° C. Accordingly, when the resin is dissolved in a solvent and applied onto the metal mesh layer, and the solvent is volatilized and dried, the unevenness formed by the unevenness of the metal mesh layer on the surface is equal to or greater than the Tg of the transparent substrate. This is because, for example, it can be flattened by applying pressure using a mirror roll or the like, and a high-quality optical filter with high transparency can be obtained. The temperature and pressure in the step of flattening the dye-containing pressure-sensitive adhesive layer 4 are appropriately selected depending on the type of the transparent resin, but are usually in the range of 50 ° C. to 170 ° C., and the pressure is linear pressure. it is preferably in the range of ^{0.1kg / cm 2 ~10kg / cm 2} .

  Specific examples of the resin having the above-described properties include acrylic resins, ester resins, polycarbonate resins, urethane resins, cyclic polyolefin resins, polystyrene resins, polyimide resins, or polytetrafluoroethylene. (PTFE), perfluoroalkoxy resin (PFA) made of a copolymer of tetrafluoroethylene and perfluoroalkyl vinyl ether, tetrafluoroethylene and hexafluoropropylene copolymer (FEP), tetrafluoroethylene and perfluoroalkyl vinyl ether and hexafluoropropylene copolymer ( EPE), copolymers of tetrafluoroethylene and ethylene or propylene (ETFE), polychlorotrifluoroethylene resin (PCTFE), ethylene and chlorine Fluoropolymers such as copolymer with trifluoroethylene (ECTFE), vinylidene fluoride resin (PVDF), and vinyl fluoride resin (PVF) can be mentioned. Among them, acrylic resins and ester resins are preferred from the viewpoint of transparency. A resin or a polycarbonate-based resin is preferable. The average molecular weight of the resin is preferably in the range of 500 to 600,000, particularly 10,000 to 400,000. This is because a transparent resin having the above properties can be obtained.

  In this invention, it is preferable that the film thickness of such a pigment | dye containing adhesive layer 4 has the film thickness of the part in which the metal mesh layer is not formed in the range of 10 micrometers-50 micrometers. This is because the unevenness of the metal mesh layer can be flattened. One or more near-infrared absorbing dyes and / or neon light absorbing dyes in the dye-containing pressure-sensitive adhesive layer 4 of the optical filter of the present invention may be contained. In that case, it is preferable that the light transmittance in the near infrared region is 20% or less, particularly 10% or less, and the light transmittance at 570 to 600 nm is 30% or less, especially 25% or less. Furthermore, the hydroxyl value and / or acid value of the resin must be 10 or less, respectively. As a result, it is possible to prevent the near-infrared absorbing dye and / or neon light-absorbing dye from reacting with the hydroxyl group and acid group contained in the resin, and stably absorb near-infrared and / or neon light absorption. The function can be exhibited.

Antireflection layer :
As for the antireflection layer, it is possible to adopt a bocus method by scattering or diffusing light like polished glass. That is, in order to scatter or diffuse light, it is fundamental to roughen the light incident surface. For this roughening treatment, the surface of the substrate is directly roughened by a sandblasting method or an embossing method. A method of providing a roughened layer containing an inorganic filler such as silica or an organic filler such as resin particles in a resin that is cured by radiation, heat, or a combination on the substrate surface; and a sea-island structure on the substrate surface A method of forming a porous film by the above can be mentioned.

As another method for forming the antireflection layer, the surface reflection is suppressed by alternately laminating a material with a high refractive index and a material with a low refractive index, and forming a multilayer (multi-coating). Can be obtained. Usually, the antireflection layer is formed by a vapor phase method or the like in which a low refractive index material typified by SiO ₂ and a high refractive index material such as TiO ₂ or ZrO ₂ are alternately formed by vapor deposition.

In order to improve the antireflection effect, the refractive index of the low refractive index layer is preferably 1.45 or less. Examples of the material having these characteristics include LiF (refractive index n = 1.4), MgF ₂ (refractive index n = 1.4), 3NaF · AlF ₃ (refractive index n = 1.4), AlF ₃ ( Inorganic materials such as refractive index n = 1.4), Na ₃ AlF ₆ (refractive index n = 1.33), SiO ₂ (refractive index n = 1.45) are made into fine particles, and acrylic resin, epoxy resin, etc. Inorganic low-reflective materials, fluorine-based / silicone-based organic compounds, thermoplastic resins, thermosetting resins, radiation-curable resins, and the like can be used.

Furthermore, a material in which a sol obtained by dispersing ultrafine silica particles of 5 to 30 nm in water or an organic solvent and a fluorine-based film forming agent can be used. The sol in which the ultrafine silica particles of 5 to 30 nm are dispersed in water or an organic solvent is obtained by a method of dealkalizing alkali metal ions in alkali silicate salt by ion exchange or the like, or neutralizing alkali silicate salt with mineral acid. A known silica sol obtained by condensing active silicic acid known by the method, etc., a known silica sol obtained by condensing alkoxysilane with hydrolysis in an organic solvent in the presence of a basic catalyst, and the above-mentioned An organic solvent-based silica sol (organosilica sol) obtained by substituting water in the aqueous silica sol with an organic solvent by a distillation method or the like is used. These silica sols can be used in both aqueous and organic solvent systems. In producing the organic solvent-based silica sol, it is not necessary to completely replace water with the organic solvent. The silica sol contains solids 0.5 to 50% strength by weight as SiO _2. Various structures such as a spherical shape, a needle shape, and a plate shape can be used for the structure of the ultrafine silica particles in the silica sol. As the film forming agent, alkoxysilane, metal alkoxide, hydrolyzate of metal salt, or fluorine-modified polysiloxane can be used.

  The low refractive index layer is obtained by diluting the above-described material into a solvent, for example, a wet coating method such as spin coating, roll coating or printing, or a vapor phase method such as vacuum deposition, sputtering, plasma CVD, or ion plating. After being provided on the high refractive index layer and dried, it can be obtained by curing with heat or radiation (in the case of ultraviolet rays, the above-mentioned photopolymerization initiator is used).

  The high refractive index layer is formed by using a binder resin having a high refractive index in order to increase the refractive index, adding ultrafine particles having a high refractive index to the binder resin, or using these in combination. To do. The refractive index of the high refractive index layer is preferably in the range of 1.55 to 2.70.

  As the resin used for the high refractive index layer, any resin can be used as long as it is transparent, and a thermosetting resin, a thermoplastic resin, a radiation (including ultraviolet) curable resin, or the like can be used. Thermosetting resins include phenolic resin, melamine resin, polyurethane resin, urea resin, diallyl phthalate resin, guanamine resin, unsaturated polyester resin, aminoalkyd resin, melamine-urea cocondensation resin, silicon resin, polysiloxane resin, etc. A curing agent such as a crosslinking agent and a polymerization initiator, a polymerization accelerator, a solvent, a viscosity modifier and the like can be added to these resins as necessary.

As ultrafine particles having a high refractive index, for example, ZnO (refractive index n = 1.9), TiO ₂ (refractive index n = 2.3 to 2.7), which can also have an ultraviolet shielding effect, Fine particles of CeO ₂ (refractive index n = 1.95), antimony-doped SnO ₂ (refractive index n = 1.95) or antistatic effect, which can prevent dust adhesion. Examples thereof include fine particles of ITO (refractive index n = 1.95). Other fine particles include Al ₂ O ₃ (refractive index n = 1.63), La ₂ O ₃ (refractive index n = 1.95), ZrO ₂ (refractive index n = 2.05), Y ₂ O _3. (Refractive index n = 1.87). These fine particles are used alone or in combination, and those in the form of a colloid dispersed in an organic solvent or water are good in terms of dispersibility. The particle diameter is 1 to 100 nm, the transparency of the coating film To preferably 5 to 20 nm.

  In order to provide the high refractive index layer, the material described above is diluted with a solvent, for example, provided on a substrate by a method such as spin coating, roll coating, or printing, dried, and then heated or irradiated (in the case of ultraviolet rays, the above-mentioned The photopolymerization initiator may be used for curing.

  Further, the antireflection layer may contain one or more near infrared absorbing dyes and / or neon light absorbing dyes. In that case, the light transmittance in the near-infrared region is 20% or less, particularly 10% or less, and the light transmittance at 570 to 600 nm is preferably 30% or less, particularly 25% or less. Further, the resin must have a hydroxyl value and an acid value that are not more than predetermined values. As a result, it is possible to prevent the near-infrared absorbing dye and / or neon light-absorbing dye from reacting due to the hydroxyl group and acid value contained in the resin, and the near-infrared absorbing ability and / or neon light can be stably stabilized. An absorption function can be exhibited.

Adhesive layer :
The adhesive layer 6 in FIGS. 1 to 3 is a layer for adhering each layer constituting the optical filter. For example, a commercially available double-sided adhesive tape (e.g., CS-9611: trade name, manufactured by Nitto Denko Corporation). ) Can be used.

Preparation of impact-resistant layer (preparation by extrusion laminating machine)
In the extrusion laminating machine of FIG. 5, a separator film 31 (U426: trade name, manufactured by Toray Industries, Inc., PET film separator film, thickness 80 μm) is arranged in the first film supply unit 35 so as to be unwound. Realic 8200UV [trade name, manufactured by Nippon Oil & Fats Co., Ltd., 80 μm thick triacetyl cellulose film (transparent substrate film 32) / 5 μm thick antireflection layer 1/40 μm thick protective film 33 as an antireflection film Film 34] was prepared and arranged so as to be able to be unwound on the second film supply unit 39 shown in FIG.

  While unwinding the separator film 31 from the first film supply unit 35 and simultaneously unwinding the laminated film 34 from the second film supply unit 39, an ether-based urethane resin (T-8190: trade name, DIC Bayer) Polymer Co., Ltd.) is sandwiched between resin films discharged from a die 42 of an extrusion laminating machine and pressed by a cooling roll 37 and a nip roll 38 to form an impact resistant layer 3 between the films, thereby forming a laminated film 36. Got. The impact resistant layer had a Shore A hardness of 90, that is, a Shore D hardness of less than 45. In the laminated film 36, a total of three types of the impact resistant layer 3 having a thickness different from 500 μm, 1500 μm, and 2500 μm were manufactured.

Copper foil (Furukawa Circuit Foil, EXP-WS: trade name, thickness 9 μm) and polyethylene terephthalate film (Toyobo A4300, thickness 100 μm), one side of the electromagnetic wave shielding film is blackened by chromate treatment And dry lamination with a urethane-based adhesive (Tg 20 ° C., average molecular weight 30,000, acid value 1, hydroxyl value 9), and after applying a resist on the copper foil, exposure, development, and etching Then, by removing the resist, an electromagnetic magnetic wave shielding film composed of the electromagnetic wave shielding layer 5 was obtained by forming a metal mesh of 300 μm □ and a line width of 10 μm. In this case, the blackened surface is set to be the viewing side (human side) when the plasma display panel is manufactured.

  Next, a dye-containing pressure-sensitive adhesive layer 4 was formed by applying a dye-containing pressure-sensitive adhesive having the following composition to the blackened surface side of the obtained electromagnetic wave shielding layer. That is, an acrylic ester copolymer obtained by copolymerizing 78.4 wt% of n-butyl acrylate, 19.6 wt% of 2-ethylhexyl acrylate, and 2.0 wt% of acrylic acid was melt-stirred, Absorbent 0.03% by weight (trade name “EEX Color” TX-EX-805K, manufactured by Nippon Shokubai Co., Ltd.) 0.015% by weight, dye (trade name “PS Blue BN”, manufactured by Mitsui Chemicals, Inc.) What added 0.0013 weight% of neon absorption compound (Asahi Denka Co., Ltd. brand name TY-102) 0.0013 weight% was used as a pigment | dye containing adhesive.

Manufacture of optical filter The separator film 31 of the three kinds of laminated films 36 obtained in the step of forming the impact-resistant layer was peeled off, and each impact-resistant layer was replaced with the dye-containing pressure-sensitive adhesive layer 4 obtained in the step of preparing the electromagnetic wave shielding film. The dye-containing pressure-sensitive adhesive layer 4 side of the electromagnetic wave shielding film formed with the adhesive force of the dye-containing pressure-sensitive adhesive layer 4 was bonded together.

  Next, separator film made of PET film (U426: trade name, manufactured by Toray Industries, Inc., thickness 80 μm) / adhesive layer 6 (CS-9611: trade name, manufactured by Nitto Denko Corporation) / separator film made of PET film ( U426: Dye obtained by preparing a pressure-sensitive adhesive sheet comprising a trade name, manufactured by Toray Industries, Inc., having a thickness of 80 μm), and peeling the separator on one side of the pressure-sensitive adhesive sheet to the pressure-sensitive adhesive layer 6 side obtained in the above step Affixed to the transparent substrate side in the three types of laminate having the containing pressure-sensitive adhesive layer 4, and finally, the protective film affixed to the antireflection layer was peeled off to obtain the optical filter shown in FIG. When the thickness of the impact resistant layer of the obtained three types of optical filters with an antireflection film is 500 μm, 1500 μm, and 2500 μm, the haze (with antireflection film) [%] of the impact resistant layer is 1.6 and 2.1, respectively. The internal haze was 0.2%, 0.6%, and 1.9%, respectively.

Manufacturing plasma display panels then peel off the remaining separator film that is attached to the adhesive layer 6 of the three optical filters with antireflection films obtained in the above step in front of the plasma display panel, a plasma display panel One type was affixed to each surface glass to obtain three types of plasma display panels.

  About each obtained plasma display panel, it performed using the impact test apparatus shown in FIG. 4 as an impact test, and the steel ball 12 (mass 534g) with a diameter of 50.8mm (what was prescribed | regulated to the steel ball for ball bearings of JIS B1501) When the thickness of the shock-resistant layer was measured, the plasma display panel was not cracked at 0.5 J and cracked at 0.6 J. When the thickness of the impact resistant layer was 1500 μm, the plasma display panel was not cracked at 0.6 J, but was cracked at 0.7 J. When the thickness of the impact resistant layer was 2500 μm, the plasma display panel was not cracked at 0.8 J, but was cracked at 0.9 J.

  These results are shown in Table 1 below.

  “Haze (with antireflection film)” shown in Table 1 means the entire haze of the entire laminate including the antireflection layer, the impact-resistant layer, the dye-containing pressure-sensitive adhesive layer, and the electromagnetic wave shielding layer. “Inside” ”means haze in a single impact-resistant layer. The haze measurement method was performed according to JIS-K7105-1981.

  The average reflectance of the optical filter with the antireflection film obtained in Example 1 was 0.5%. In addition, the plasma display panel obtained in Example 1 did not generate bubbles or peel off the filter. The near-infrared shielding performance of the optical filter with an antireflection film of Example 1 was 85% or more at a wavelength of 800 to 1200 nm, and the neon light shielding performance was 40% or less at a wavelength of 587 nm.

  As the antireflection layer, a laminated film (Realak 8200UV: trade name, manufactured by Nippon Oil & Fats Co., Ltd.) comprising a triacetyl cellulose film having a thickness of 80 μm / an antireflection layer having a thickness of 5 μm / a protective film having a thickness of 40 μm was prepared. Urethane resin obtained by radical polymerization of an oligomer having 1 to 3 (meth) acrylic groups as a resin for forming an impact resistant layer on the back surface of the antireflection layer (Beamset 502H: trade name, Arakawa Chemical Co., Ltd. ), Having 2 functional groups (ie, 2 acrylic groups), Shower A hardness 65, ie, Shower D hardness of less than 45), 100 parts by mass, and 2 parts by mass of Darocur 1173 manufactured by Ciba Specialty Chemicals as a photoinitiator. Part of the mixture was applied by the die coating method and the coating apparatus shown in FIG. 7 described in the above section “Impact-resistant layer (formation of impact-resistant layer) iii) Thick coating method”, and 240 mJ / cm A laminated film composed of an antireflection layer / impact resistant layer was obtained by UV irradiation with an integrated light amount and curing. The impact resistant layer in the laminated film has adhesiveness.

  Due to this adhesiveness, the impact-resistant layer side of the laminated film obtained in the above step is bonded to the electromagnetic wave shielding layer using the adhesiveness of the impact-resistant layer, and then the dye-adhesive is applied to the dye-adhesive. A layer was formed, and then an antireflection layer was formed to obtain an optical filter.

  Three types of optical filters and plasma display panels each having a thickness of 500 μm, 1500 μm, and 2500 μm of the impact resistant layer of the optical filter obtained in the above steps were obtained. When the thickness of the impact resistant layer in the obtained optical filter is 500 μm, 1500 μm, 2500 μm, the haze (with antireflection film) of the impact resistant layer is 1.8%, 2.2%, 2.9%, The internal haze was 0.3%, 0.9% and 1.8%, respectively.

  The optical filter was affixed to the plasma display panel with the dye adhesive layer side of the optical filter obtained in the above process facing the surface side of the plasma display panel.

  The obtained plasma display panel was subjected to an impact test in the same manner as in Example 1. As a result, when the thickness of the impact-resistant layer was 500 μm, the plasma display panel was not cracked at 0.6 J and cracked at 0.7 J. It was. When the thickness of the impact resistant layer was 1500 μm, the plasma display panel was not cracked at 0.7 J, but was cracked at 0.8 J. When the thickness of the impact-resistant layer was 2500 μm, the plasma display panel was not cracked at 0.9 J, and cracked at 1.0 J.

  These results are shown in Table 1 below.

  The average reflectance of the optical filter with the antireflection film obtained in Example 2 was 0.7%. The plasma display panel obtained in Example 2 did not generate bubbles or peel off the filter. The near-infrared shielding performance of the optical filter with an antireflection film of Example 2 was 85% or more at a wavelength of 800 to 1200 nm, and the neon light shielding performance was 40% or less at a wavelength of 587 nm.

  Urethane resin (Des-460, manufactured by DIC Bayer Polymer Co., Ltd., Shower D hardness 60) is used as the resin for forming the impact-resistant layer. The above-mentioned “impact-resistant layer (formation of impact-resistant layer) ii) Sheet molding method” The sheet was formed by the sheet forming apparatus shown in FIG. 6 described in the column, and three types of impact-resistant layers having thicknesses of 500 μm, 1500 μm, and 2500 μm were obtained.

  The impact resistant layer obtained in the above step was bonded to the back surface of the antireflection layer using an acrylic pressure-sensitive adhesive (CS-9611 manufactured by Nitto Denko Corporation: trade name). On the other hand, an adhesive layer is formed by applying an acrylic adhesive (for example, CS-9611 manufactured by Nitto Denko Corporation) on the transparent substrate side of the electromagnetic wave shielding layer, and further, a pigment-containing adhesive is applied to the metal mesh surface. By doing so, a dye-containing pressure-sensitive adhesive layer was laminated and the optical filter shown in FIG. 8 was obtained.

  The hazes (with antireflection film) of the three types of impact resistant layers having an impact resistant layer thickness of 500 μm, 1500 μm, and 2500 μm of the obtained optical filter with an antireflection film are 1.6%, 2.1%, and 2. The internal haze was 7% and 0.6% and 1.9%, respectively.

  Next, the remaining separator film attached to the adhesive layers of the three types of optical filters with antireflection films obtained in the above process is peeled off from the front surface of the plasma display panel, and one surface glass of each plasma display panel is removed. One type was attached to the total to obtain three types of plasma display panels.

  About each obtained plasma display panel, an impact test was performed in the same manner as in Example 1. As a result, when the thickness of the impact resistant layer was 500 μm, the plasma display panel was not cracked at 0.5 J, and at 0.6 J cracked. When the thickness of the impact resistant layer was 1500 μm, the plasma display panel was not cracked at 0.5 J, but was cracked at 0.6 J. When the thickness of the impact resistant layer was 2500 μm, the plasma display panel was not cracked at 0.7 J, but was cracked at 0.8 J.

  These results are shown in Table 1 below.

  The average reflectance of the optical filter with an antireflection film obtained in Example 3 was 0.7%. In addition, the plasma display panel obtained in Example 3 did not generate bubbles or peel off the filter. The near-infrared shielding performance of the optical filter with an antireflection film of Example 3 was 85% or more at a wavelength of 800 to 1200 nm, and the neon light shielding performance was 40% or less at a wavelength of 587 nm.

In Table 1, OO indicates that the PDP panel is not cracked twice in the two impact resistance tests, and ●● indicates that the PDP panel is cracked twice in the two impact resistance tests. Show.

[Comparative Example 1]
Polyether-based resin (Des KA-8333, manufactured by DIC Bayer Polymer Co., Ltd., Shower D hardness 66, Shower A hardness 98) is used as the resin for forming the impact resistant layer. Ii) Sheets were formed by the sheet forming apparatus shown in FIG. 6 described in the section of “Sheet forming method” to obtain three types of impact-resistant layers having thicknesses of 500 μm, 1500 μm, and 2500 μm, respectively. When the thickness of the impact resistant layer in the obtained optical filter is 500 μm, 1500 μm, 2500 μm, the haze (with antireflection film) of the impact resistant layer is 1.4%, 1.8%, 2.4%, The internal haze was 0.4%, 0.8% and 1.4%, respectively.

  A total of three types of plasma display panels were obtained using the obtained optical filters in the same manner as in Example 3.

The obtained plasma display panel was subjected to an impact test in the same manner as in Example 1. As a result, when the thickness of the impact resistant layer was 500 μm, the plasma display panel was not cracked at 0.2J, and cracked at 0.3J. It was. When the thickness of the impact resistant layer was 1500 μm, the plasma display panel was not cracked at 0.3 J, but was cracked at 0.4 J. When the thickness of the impact resistant layer was 2500 μm, the plasma display panel was not cracked at 0.3 J, but was cracked at 0.4 J.
These results are shown in Table 2 below.

[Comparative Example 2]
Acrylic resin (U-4HA, manufactured by Shin-Nakamura Chemical Co., Ltd., tetrafunctional molecular weight 598, acrylic equivalent 149, hard coat type, non-yellowing type, pencil hardness 7H after curing, resin for forming the impact resistant layer A sheet is formed by the sheet forming apparatus shown in FIG. 6 described in the section of “Impact Resistant Layer (Impact Resistant Layer Formation) ii) Sheet Forming Method”. Three types of impact resistant layers having thicknesses of 500 μm, 1500 μm and 2500 μm were obtained. When the thickness of the impact resistant layer in the obtained optical filter is 500 μm, 1500 μm, 2500 μm, the haze (with antireflection film) of the impact resistant layer is 1.7%, 2.1%, 2.8%, The internal haze was 0.3%, 0.8% and 1.5%, respectively.

  The optical filter was affixed to the plasma display panel with the dye adhesive layer side of the optical filter obtained in the above process facing the surface side of the plasma display panel.

The obtained plasma display panel was subjected to an impact test in the same manner as in Example 1. As a result, when the impact-resistant layer had a thickness of 500 μm, the plasma display panel was not cracked at 0.1 J and cracked at 0.2 J. It was. When the thickness of the impact-resistant layer was 1500 μm, the plasma display panel was not cracked at 0.2J, but was cracked at 0.3J. When the thickness of the impact resistant layer was 2500 μm, the plasma display panel was not cracked at 0.2 J, but was cracked at 0.3 J.
These results are shown in Table 2 below.

[Comparative Example 3]
An acrylic pressure-sensitive adhesive sheet having an electromagnetic wave shielding layer bonded with an antireflection layer via a dye-containing pressure-sensitive adhesive layer, and having a protective film (release film) made of polyethylene terephthalate on the PET surface side of the electromagnetic wave shielding layer The surface where the adhesive of Nitto Denko Corporation CS-9611 (trade name) is exposed was bonded to obtain an optical filter. The obtained optical filter is not formed with an impact resistant layer.

  The protective film in the obtained optical filter was peeled off, and the exposed acrylic pressure-sensitive adhesive sheet was attached to the surface of the plasma display panel. FIG. 10 shows a laminated structure of the plasma display panel of Comparative Example 3 in which an optical filter without an impact resistant layer is disposed on the front surface of the plasma display panel.

  The obtained plasma display panel was subjected to an impact test in the same manner as in Example 1. As a result, the plasma display panel was not cracked at 0.1J, but was cracked at 0.2J. These results are shown in Table 2 below.

In Table 2, OO indicates that the PDP panel is not broken twice in the two impact resistance tests, and ●● indicates that the PDP panel is cracked twice in the two impact resistance tests. Show.

  The optical filter of the present invention can impart impact resistance to a plasma display panel when attached to the front surface of the plasma display.

It is a figure which shows an example of the laminated structure at the time of arrange | positioning the optical filter of this invention in the front surface of a plasma display. It is a figure which shows another example of the laminated structure at the time of arrange | positioning the optical filter of this invention in the front surface of a plasma display. It is a figure which shows another example of the laminated structure at the time of arrange | positioning the optical filter of this invention in the front surface of a plasma display. It is a figure which shows an impact test apparatus. It is the schematic which shows an example of the extrusion laminating machine suitable for forming the impact resistant layer containing a polyurethane-type resin as an impact resistant layer in the optical filter of this invention. It is the schematic which shows an example of the sheet molding machine suitable for forming the impact resistant layer containing a polyurethane-type resin as an impact resistant layer in the optical filter of this invention. It is the schematic which shows another example of the sheet molding machine suitable for forming the impact resistant layer containing a polyurethane-type resin as an impact resistant layer in the optical filter of this invention. It is a figure which shows another example of the laminated structure at the time of arrange | positioning the optical filter of this invention in the front surface of a plasma display. It is a figure which shows another example of the laminated structure at the time of arrange | positioning the optical filter of this invention in the front surface of a plasma display. It is a figure which shows an example of the laminated structure at the time of arrange | positioning the optical filter without an impact-resistant layer as a comparative example on the front surface of a plasma display.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Antireflection layer 3 Impact-resistant layer 4 Dye containing adhesive layer 5 Electromagnetic wave shielding layer 6 Adhesive layer 7 Plasma display panel 8 Test stand 9 Base 10 Glass plate 11 Front glass plate 12 Steel ball 15 Separator 21-1, 21-2 , 21-3 Hopper 23 Dies 24-1, 24-2, 24-3 Manifold 25 Laminated sheet 26-1, 26-2, 26-3 Cooling roll 27 Discharge device 31 Separator film 32 Transparent substrate film 33 Protective film 34 Laminated Film 35 First Film Supply Unit 36 Laminated Film 37 Cooling Roll 38 Nip Roll 39 Second Film Supply Unit 41 Paper Discharge Unit 42 Die 43 Die Coat Heads 44-1, 44-2 UV Irradiation Device

Claims (9)

(1) An optical filter for being directly attached to a display surface of a plasma display panel,
(2) The optical filter has an impact resistant layer having a Shower D hardness of less than 65,
(3) The impact resistant layer has an internal haze of 0.1% to 3.0%, a thickness of 0.5 mm to 3.0 mm,
(4) An optical filter characterized in that when the optical filter is affixed to a plasma display panel, the breaking energy by an impact test on the plasma display panel is 0.5 J or more.   The optical filter according to claim 1, wherein the resin used to produce the impact resistant layer is a polyurethane resin.   The optical filter according to claim 2, wherein the polyurethane resin is a urethane resin obtained by radical polymerization of an oligomer having 1 to 3 (meth) acryl groups at a terminal.   The optical filter according to claim 1, 2 or 3, wherein the optical filter has a resin layer containing a near-infrared absorbing compound and has a transmittance in the wavelength range of 800 to 1000 nm of 20% or less.   5. The resin layer comprising a neon light absorbing compound having a maximum absorption wavelength in a wavelength range of neon light of 560 to 630 nm, wherein the transmittance of the maximum absorption wavelength in the wavelength range is 40% or less. 1. An optical filter according to item 1.   The optical filter according to any one of claims 1 to 5, wherein transmittance in a wavelength range of visible light of 380 to 780 nm is 40% or more.   The optical filter according to any one of claims 1 to 6, further comprising an electromagnetic wave shielding layer that shields static electricity and / or electromagnetic noise generated from the plasma display device.   The optical filter according to any one of claims 1 to 7, further comprising an adhesive layer for adhering to the plasma display panel.   A plasma display panel comprising the optical filter according to claim 1 attached to a display surface through an adhesive layer.

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