JP2006153955A - Optical filter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical filter which is excellent in antireflection property, electromagnetic wave shielding property, near-infrared ray shielding property, durability and visibility clearness and is lightweight. <P>SOLUTION: An antireflection layer is formed on one surface of a transparent support, an electromagnetic wave shielding layer is formed on the other surface, thereupon, a near-infrared ray shielding layer is formed and, further thereupon, an adhesive layer is formed, preferably, leaving a ground electrode lead so as to be exposed. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an optical filter and a method for manufacturing the same. More specifically, the present invention relates to an optical filter used for a display surface of an optical image display device such as a plasma display and a method for manufacturing the same.

  A plasma display device (hereinafter abbreviated as PDP) includes a front glass substrate having display electrodes, bus electrodes, a dielectric layer and a protective layer, a data electrode, a dielectric layer, and a phosphor layer on a stripe barrier rib. A cell is formed by adhering a back glass substrate having an electrode so that the electrodes are orthogonal to each other, and a discharge gas such as xenon is enclosed in the cell. The plasma display device emits light by applying a voltage between the data electrode and the display electrode to cause xenon discharge. When the xenon ions in the plasma state return to the ground state, ultraviolet light is generated. Excites the phosphor layer to emit red (R), green (G), and blue (B) light. In the process of emitting visible light, near infrared light and electromagnetic waves are also generated in addition to the visible light. Therefore, a plasma display device is generally provided with an antireflection film, a near-infrared absorbing film, and a filter provided with an electromagnetic wave cutting function on the front surface of the glass substrate light emitting section.

  The plasma display device has a small installation space as a thin display device, and is considered useful as a wall-mounted display device. However, in the above-described plasma display device, for example, on a PDP device including a light emitting means as described in Japanese Patent Application Laid-Open No. 10-319859 (Patent Document 1), and then on a glass with a certain space therebetween. Since the optical filter means constructed by laminating a film laminate in which several layers of films are laminated together, it cannot be said that sufficient weight reduction has been achieved. In order to hang it on an indoor wall, the wall needs to be sufficiently strong, and it may be necessary to reinforce the wall itself in advance. In addition, there is a drawback that external light is reflected twice on the display surface due to reflection of the front glass portion of the PDP and the front and back surfaces of the optical filter. In general, the main electromagnetic wave shielding film used for optical filters is an etched metal (copper) mesh, or the metal (copper) is exposed on the etched end face. The reflection color of this causes a defect in the color tone of the display image.

Japanese Patent Laid-Open No. 10-319859

  The present invention has excellent antireflection properties, near-infrared shielding properties, and electromagnetic wave shielding properties, has excellent durability and visibility, is lightweight and easy to manufacture and handle, such as a plasma display device, etc. It is an object of the present invention to provide an optical filter that can be used for a display surface of the display device and a manufacturing method thereof.

The optical filter of the present invention includes a transparent substrate, an antireflection layer formed on one surface of the transparent substrate, an electromagnetic wave shielding layer formed on the other surface of the transparent substrate, and the electromagnetic wave shielding layer. The near-infrared shielding layer formed above and the adhesive layer formed on the near-infrared shielding layer are laminated in an integral film form.
In the optical filter of the present invention, the electromagnetic wave shielding layer is preferably made of a metal mesh.
In the optical filter of the present invention, the near-infrared shielding layer is preferably formed by a printing method.
The optical filter of the present invention further includes a ground electrode take-out portion formed on the electromagnetic wave shielding layer, and the earth electrode take-out portion is provided in at least two locations separated from each other in the peripheral portion of the electromagnetic wave shield layer. It is preferable.
In the optical filter of the present invention, it is preferable that the transparent substrate has ultraviolet absorption performance.
In the method for producing an optical filter of the present invention, an antireflection layer is formed on one surface of a transparent substrate, and then an electromagnetic wave shielding layer is formed on the other surface of the transparent substrate. In addition, a near-infrared shielding layer is formed, and an adhesive layer is further formed on the near-infrared shielding layer to form an integral film-like laminate.
In the method for producing an optical filter of the present invention, when the near-infrared shielding layer and the adhesive layer are formed on the electromagnetic shielding layer, at least two edges of the electromagnetic shielding layer that are separated from each other. It is preferable to leave the part without covering as a ground electrode take-out part.

  The optical filter of the present invention is excellent in antireflection, near-infrared shielding, electromagnetic wave shielding, durability for use and ease of visual observation of images, and is lightweight, and therefore easy to manufacture and handle, For example, it is practically useful as an optical filter for the display surface of various display devices such as a plasma display device.

  FIG. 1 shows a longitudinal sectional view (FIG. 1- (a)) of an example of an optical filter of the present invention and a front view (FIG. 1- (b)) when the filter is viewed in a direction A. Yes. 1- (a) and (b), the optical filter 1 was formed on the transparent base material 11, the antireflection layer 12 formed on one surface thereof, and the other surface of the transparent base material 11. The electromagnetic wave shielding layer 13 includes a near infrared shielding layer 14 formed on the electromagnetic shielding layer 13 and an adhesive layer 15 formed on the near infrared shielding layer 14. As shown in FIGS. 1A and 1B, it is preferable that a portion 13 a for forming a ground electrode lead-out portion is formed on the periphery of the electromagnetic wave shielding layer 13.

In the conventional transparent laminated body for optical filters, each functional layer is formed on a separate transparent substrate, and the transparent substrate carrying these functional layers is laminated with a glass panel via an adhesive layer. It was formed by. Further, even in a film-type transparent laminate for optical filters that does not use glass, a filter is configured by laminating a plurality of films with functional layers.
In the optical filter of the present invention, an antireflection layer is formed on one surface of a transparent substrate, and an electromagnetic wave shielding layer (metal mesh layer) is formed on the other surface. By forming a near-infrared shielding layer and an adhesive layer on this, it has the shape of a single film-like laminate, reducing the number of laminated layers, reducing the material cost, and manufacturing It has become possible to reduce the number of steps and realize an optical filter having improved optical properties by realizing high transmittance and low haze.

  Since the optical filter of the present invention has the above-described configuration, the number of transparent base materials and the number of pressure-sensitive adhesive layers that do not contribute to each function and may adversely affect in some cases are reduced. In addition, an integrated optical filter having various functions in combination is configured. Moreover, since there is no bonding step in the production, the number of production steps is reduced, the production yield is improved, the performance of the product is stabilized, and the reliability is also improved. Moreover, since the antireflection layer forms the outermost layer of the optical filter, an excellent antireflection effect can be obtained.

  The optical filter of the present invention is substantially composed of a single film-like laminate, that is, an antireflection layer is formed on one surface of a transparent substrate, and an electromagnetic wave shielding layer (metal mesh layer) is formed on the other surface. The near-infrared shielding layer is formed on the electromagnetic wave shielding layer, and the adhesive layer is formed thereon. In this case, the near-infrared shielding layer is preferably formed from a substance having near-infrared shielding performance and a resin matrix, and the transparent substrate is made of a material having ultraviolet absorption performance, for example, a transparent resin containing an ultraviolet absorber. In the optical filter of the present invention, the near-infrared shielding layer is preferably protected from external light by the ultraviolet absorber-containing transparent base material, so that its performance is achieved. It has excellent durability and weather resistance, and has excellent reliability. Moreover, when using a metal mesh layer as an electromagnetic wave shielding layer, the near-infrared shielding layer fills the space | gap part of the metal mesh of a metal mesh layer, and the transparent laminated body without a space | gap part is obtained.

(Transparent substrate)
As long as the transparent base material used for this invention is a transparent material, there is no limitation in the kind, composition, etc. The material constituting the transparent substrate is preferably generally selected from transparent plastic materials. For example, a plate-like, sheet-like, or film-like polyester-based substrate, triacetyl cellulose substrate, polycarbonate substrate, polyether monkey It can be appropriately selected from a von base material, a polyacrylate base material, a norbornene base material, an amorphous polyolefin base material, etc. Also, there is no particular limitation on the thickness thereof, usually about 50 μm to 10 mm. A film or plate can be used. Among them, a polyethylene terephthalate (hereinafter also referred to as “PET”) substrate is preferably used because of its excellent durability, solvent resistance, productivity, and the like. Moreover, in order to adjust a color tone and the transmittance | permeability, you may use what was colored.

  The optical filter of the present invention is excellent in an antireflection effect, a near infrared shielding effect and an electromagnetic wave shielding effect required for a plasma display. For this reason, the image displayed on the display surface of the plasma display can be observed as a clear image by pasting the optical filter directly on the image display surface of the plasma display.

(About UV shielding properties of transparent substrates)
In the optical filter of the present invention, it is preferable to use an ultraviolet shielding material for the transparent substrate. This is because the near-infrared absorbing dye contained in the near-infrared shielding layer usually has a low resistance to ultraviolet rays, so that the deterioration of the near-infrared absorbing dye can be suppressed by using an ultraviolet shielding material as the transparent substrate. Because it can. As the ultraviolet absorber, for example, benzophenone-based, benzotriazole-based, paraaminobenzoic acid-based, and salicylic acid-based ultraviolet absorbing compounds can be used. Usually, a sufficient effect cannot be obtained unless an ultraviolet absorber is used in an added amount of a certain amount or more. Generally, when an ultraviolet absorber is added to a thin coating layer, the amount of the ultraviolet absorber that can be contained in the coating layer is limited, and it may be difficult to obtain the necessary ultraviolet shielding effect. However, in the optical filter of the present invention, since the near-infrared shielding layer is located inside the transparent substrate, the transparent substrate itself having a larger thickness than the thin coating layer contains an ultraviolet absorber. An optical filter containing a sufficient amount of an ultraviolet absorber can be formed, whereby deterioration of the near infrared absorbing dye can be suppressed and excellent near infrared absorbing performance can be maintained. As the ultraviolet shielding performance of the optical filter, the ultraviolet transmittance is preferably 2% or less in the ultraviolet region of 380 nm or less.

(Near-infrared shielding layer)
In the optical filter of the present invention, the near-infrared shielding performance of the near-infrared shielding layer preferably has a shielding property against near-infrared light in the wavelength range of 800 to 1100 nm. For example, a near-infrared absorbing dye is contained in the resin matrix. It is preferable that it is contained. The near-infrared shielding layer may contain a binder, and a methacrylate-based resin can be used as the binder.
The near-infrared absorbing dye is not particularly limited as long as it has a shielding property against near-infrared rays in the wavelength range of 800 to 1100 nm. For example, diimonium compounds, aluminum compounds, phthalocyanine compounds, organometallic complex compounds , Cyanine compounds, azo compounds, polymethine compounds, quinone compounds, diphenylmethane compounds, triphenylmethane compounds, mercaptonaphthol compounds, etc., and these may be used as a single species. Moreover, you may use what was compounded with the inorganic substance, or may use it in combination of 2 or more types as appropriate.
The diimonium-based compound has a strong absorptivity with a molar extinction coefficient of about 100,000 in the near-infrared region with a wavelength of 850 to 1100 nm, and thus has excellent near-infrared shielding properties. Diimonium compounds have a slight absorption in the visible light region with a wavelength of 400 to 500 nm and exhibit a tan transmission color, but the visible light transmission is superior to other near-infrared absorbing dyes. It is preferable that at least one diimonium-based compound is contained in the near-infrared absorbing dye used in the optical filter of the invention.

  In order for the near-infrared shielding layer to exhibit practically sufficient near-infrared shielding properties, the transmittance of near-infrared light having a wavelength of 850 to 1000 nm is preferably 20% or less. A preferable blending amount of the near-infrared absorbing dye in the near-infrared shielding layer varies depending on the thickness of the adhesive layer. When a diimonium compound is used and the thickness of the near-infrared shielding layer is designed to be about 5 to 50 μm, the composition of the near-infrared absorbing dye compound is added to 100 parts by mass of the transparent resin used as a matrix (binder). The amount is preferably about 0.5 to 5.0 parts by mass. When the blending amount of the near-infrared absorbing dye compound with respect to 100 parts by mass of the transparent matrix resin exceeds 5 parts by mass, segregation of the dye occurs in the obtained near-infrared shielding layer, and the visible light transparency is deteriorated. Sometimes.

When a diimonium compound is used for the near-infrared shielding layer, as the second near-infrared absorbing dye, one or more dyes having an absorption maximum at 750 to 900 nm and substantially no absorption in the visible light region, For example, the ratio between the absorption coefficient at the absorption maximum wavelength and the respective extinction coefficients at wavelengths of 450 nm (center wavelength of blue light), 525 nm (center wavelength of green light) and 620 nm (center wavelength of red light) It is preferable to use together one or two or more near-infrared absorbing dyes that are 5.0 or more, and it is more preferable that the ratio of the extinction coefficients of the second near-infrared absorbing dyes is 8.0 or more. If any of the extinction coefficient ratios is less than 5.0, the wavelength of 450 nm (center wavelength of blue light) and 525 nm (green) when the average transmittance of 850 to 900 nm required for practical use is 20% or less. One of the visible light transmittance at 620 nm (the central wavelength of red light) and the visible light transmittance at 620 nm (red light central wavelength) is less than 60%, and the transmittance in the visible light region may be practically insufficient.
As said 2nd compound for near-infrared absorption dyes which has the said characteristic, a dithiol nickel complex type compound, an indolium type compound, a phthalocyanine type compound, a naphthalocyanine type compound etc. can be used, for example. In particular, phthalocyanine compounds and naphthalocyanine compounds are generally excellent in durability and can be suitably used. However, since naphthalocyanine compounds are more expensive, phthalocyanine compounds are more suitable for practical use. Used for.

  Further, in the optical filter of the present invention, the visible light transmittance at a wavelength of 590 nm is preferably 10% or more lower than the visible light transmittance at wavelengths of 450 nm, 525 nm, and 620 nm. In this case, when the optical filter of the present invention is used, the contrast of a display such as a plasma display is improved, and the color tone correction function is enhanced. In order to reduce the visible light transmittance at a wavelength of 590 nm of the optical filter of the present invention by 10% or more than the visible light transmittance at wavelengths of 450 nm, 525 nm, and 620 nm, selective absorption is performed in the near-infrared shielding layer. It is preferable to contain a coloring material. The colorant that selectively absorbs visible light having a wavelength of 590 nm is not particularly limited as long as it does not adversely affect the compositional alteration of the diimonium compound, but for example, quinacridone pigments, azomethine compounds, cyanine compounds, And porphyrin compounds are preferably used.

(Antireflection layer)
In the optical filter of the present invention, the configuration and composition of the antireflection layer formed on one surface of the transparent substrate are not particularly limited as long as it has a desired antireflection effect, and has a single layer structure. Or may have a plurality of structures. Further, a conductive layer such as an antistatic layer and / or a thin film layer having a function such as antiglare may be further formed on the antireflection layer.
The antireflection layer includes a hard coat layer, a conductive medium refractive index layer laminated on the hard coat layer, a high refractive index layer laminated on the conductive medium refractive index layer, and the high refractive index layer. It is preferably composed of a low refractive index layer laminated thereon.
The antireflection layer having such a configuration is an antireflection layer having conductivity, and can prevent dust from being attached due to static electricity. In addition, since this conductive medium refractive layer has the function of a medium refractive index layer, it is possible to form an antireflection film with three layers of medium refraction, high refraction, and low refraction, thereby providing excellent antireflection. An effect is obtained.

The hard coat layer is formed of a resin component, but preferably contains fine oxide particles. By containing the oxide fine particles, the adhesion to the transparent substrate is improved.
The content of the oxide fine particles in the hard coat layer is preferably 30% by mass to 80% by mass. When the content of the oxide fine powder is less than 30% by mass, the adhesion with the first transparent substrate and the medium refractive index layer is lowered, and the desired pencil hardness and film hardness such as steel wool strength are obtained. It becomes impossible. In addition, when the content of the oxide fine powder is more than 80% by mass, the content of the oxide fine powder becomes excessive, the film strength of the obtained hard coat layer is lowered, and a whitening phenomenon is observed in the obtained hard coat layer. In other words, the problem is that the flexibility of the cured film is lowered and cracks are likely to occur.
Moreover, it is preferable to design so that the refractive index of a hard-coat layer may become the same value as the surface average refractive index of a transparent base material. This is to make the so-called “irregular color irregularity of the surface” inconspicuous by reducing the difference in the amplitude of the reflectance caused by the difference in the average refractive index of the surface of the transparent substrate and the refractive index of the hard coat layer. This is because it can. However, when a PET film with an easy-adhesion layer is used as the transparent substrate, the refractive index of the hard coat layer is preferably the same as or close to the refractive index calculated by the following formula.
N = Np− (Ns−Np) / 2
N: Refractive index of the transparent hard coat layer
Np: Refractive index of PET easy adhesion layer
Ns: Surface average refractive index of PET substrate Also, as oxide fine particles used in the hard coat layer, silicon oxide, aluminum oxide, antimony oxide, tin oxide, zirconium oxide, tantalum oxide, cerium oxide, titanium oxide, etc. The particle diameter of the fine oxide particles is preferably 100 nm or less, which is appropriately used for the reason that a hard coat layer having excellent transparency can be formed without coloring the hard coat layer. This is because, in the case of fine oxide particles having a particle size exceeding 100 nm, the resulting hard coat layer significantly scatters light due to Rayleigh scattering and appears white, resulting in a decrease in transparency.
Examples of the resin component include an ultraviolet curable resin, an electron beam curable resin, and a cationic polymerization resin. Among them, the ultraviolet curable resin is inexpensive and excellently used because it has excellent adhesion to a transparent plastic film. It is done. The ultraviolet curable resin may be a photosensitive resin used in a coating method (wet coating method), and examples thereof include acrylic resins, acrylic urethane resins, silicone resins, and / or epoxy resins. It is preferably used because it does not impair the dispersibility of the oxide fine powder.
In the present invention, the hard coat layer in the antireflection layer is formed by, for example, applying a hard coat layer-forming coating material containing at least an organic resin component, oxide fine particles, and an organic solvent on a transparent substrate, drying, and ultraviolet rays. It is formed by irradiation.
The transparent hard coat layer-forming coating material is, for example, mixed in an organic solvent by an ordinary method using ultrasonic dispersion, a homogenizer, a sand mill, or the like, using a dispersant and the oxide fine particles and a resin component. It can be obtained as a dispersed organic solvent-based paint. The organic solvent can be selected from alcohol-based, glycol-based, acetate-based, and ketone-based solvents, and these may be used alone or in combination of two or more.
And the said hard-coat layer formation coating material is apply | coated to one side of a transparent base material, and it hardens | crosslinks by ultraviolet irradiation etc., and forms a hard-coat layer. The film thickness of the hard coat layer is preferably 0.5 μm to 20 μm, more preferably 0.5 to 2 μm. If the film thickness is 0.5 μm or less, sufficient film hardness may not be achieved, and if it is 20 μm or more, curling of the transparent substrate may be increased.
Various coating methods can be used as the coating method, and can be appropriately selected from, for example, a bar coating method, a gravure coating method, a slit coater method, a roll coater method, and a dip coating method.

The conductive medium refractive index layer formed on the hard coat layer preferably has conductivity and contains fine particles having a medium refractive index and a binder component.
The content of the conductive medium refractive index fine particles in the conductive medium refractive index layer is preferably 50% by mass or more, and more preferably in the range of 70 to 95%. When the content of the conductive medium refractive index fine particles is less than 50% by mass, the surface resistance value of the conductive medium refractive index layer increases, the conductivity deteriorates, and the filler component may decrease. Adhesion with the hard coat layer may be insufficient. On the other hand, when the content of the conductive medium refractive index fine particles exceeds 95% by mass, the content of the binder component is relatively decreased, so that a sufficient amount of the conductive medium refractive index fine particles are retained in the binder matrix. In addition, when another layer is applied on the conductive medium refractive index layer, the film is easily damaged, which may cause poor appearance.
As the conductive medium refractive index fine particles, antimony-containing tin oxide (hereinafter referred to as ATO), tin-containing indium oxide (hereinafter referred to as ITO), aluminum-containing zinc oxide, gold, silver, palladium, and other metal fine particles are transparent. It is preferably used for the reason that it is possible to form a conductive medium refractive index layer excellent in conductivity and conductivity.
The conductive medium refractive index fine particles preferably have an average particle size of 1 to 100 nm. If the average particle size is less than 1 nm, aggregation tends to occur during coating, making uniform dispersion difficult for coating, and further increasing the viscosity of the coating and causing poor dispersion. Also, if the average particle size of the conductive medium refractive index fine particles exceeds 100 nm, the resulting conductive medium refractive index layer remarkably diffuses light due to Rayleigh scattering, so that it appears white and the transparency decreases. There are things to do.
As a binder component, the substance produced | generated from a silicon alkoxide and / or a hydrolysis product is preferable.
In the optical filter of the present invention, the conductive medium refractive index layer uses a conductive medium refractive index layer forming paint containing at least conductive medium refractive index fine particles, silicon alkoxide and / or a hydrolysis product thereof, and an organic solvent. Then, it can be formed by applying and drying on the hard coat layer.
The conductive medium refractive index layer-forming coating material comprises the conductive medium refractive index oxide fine particles, silicon alkoxide and / or a hydrolysis product thereof, and other particles optionally added, using a dispersant. In addition, it can be dispersed in an organic solvent by an ordinary method using an ultrasonic disperser, a homogenizer, a sand mill or the like to obtain an organic solvent-based paint.
The silicon alkoxide can be selected from, for example, tetraalkoxysilane compounds, alkyltrialkoxysilane compounds, and the like, and the organic solvent is selected from alcohols, glycols, acetate esters, ketones, and the like. These may be a single species or a mixture of two or more species.
Then, applying the conductive medium refractive index layer-forming paint on the transparent hard coat layer and drying it at 70 to 130 ° C. for 1 minute or more, for example, to adjust the optical film thickness within the range of 140 ± 30 nm. Is preferred.
When the drying temperature exceeds 130 ° C., it is not preferable because the transparent plastic film used causes thermal deformation. Moreover, if it is less than 70 degreeC, a cure rate will become slow and strength will not express. Also, a curing time of less than 1 minute is not preferable because the film strength is insufficient.
The coating method can be appropriately selected from, for example, a bar coating method, a gravure coating method, a slit coater method, a roll coater method, a dip coating method, and the like.

The high refractive index layer formed on the conductive middle refractive index layer includes, for example, high refractive index oxide fine particles and a binder component.
The content of the high refractive index oxide fine particles in the high refractive index layer is preferably 50% by mass or more, and more preferably 60 to 95% by mass. When the content of the high refractive index oxide fine particles is less than 50%, the content of the binder component is relatively increased and the refractive index is lowered, so that a sufficiently high refractive index cannot be obtained, and the reflectance is excessive. May increase. Further, if the content of the high refractive index oxide fine particles exceeds 95%, the high refractive index oxide fine particles cannot be sufficiently fixed by the binder component, and other components are formed on the transparent high refractive index layer. When applying the layer, scratches are likely to occur, and further appearance defects may occur.
As the high refractive index oxide fine particles, cerium oxide, zinc oxide, zirconium oxide, titanium oxide, tantalum oxide and the like are preferably used for the reason that a high refractive index layer excellent in transparency can be formed.
The average particle size of the high refractive index oxide fine powder is preferably 1 to 100 nm. If the average particle size is less than 1 nm, aggregation tends to occur during coating, making uniform dispersion difficult for coating, and further increasing the viscosity of the coating and causing poor dispersion. In addition, when the average particle size of the high refractive index oxide fine powder exceeds 100 nm, the resulting high refractive index layer remarkably diffuses light due to Rayleigh scattering, so that it appears white, and the transparency is insufficient. May be.
As the binder component, silica derived from silicon alkoxide and / or a hydrolysis product thereof is preferable.
The high refractive index layer is formed by applying and drying on the conductive medium refractive index layer using a transparent high refractive index forming paint containing at least a high refractive index oxide fine particle, a binder component and an organic solvent. It is formed.
The coating material for forming a high refractive index layer includes an ultrasonic disperser using a dispersant for the high refractive index oxide fine powder, silicon alkoxide and / or a hydrolysis product thereof, and optionally added particles. It can be dispersed in an organic solvent by an ordinary method using a homogenizer, a sand mill or the like to obtain an organic solvent-based paint.
The silicon alkoxide can be selected from, for example, tetraalkoxysilane compounds, alkyltrialkoxysilane compounds, and the like, and the organic solvent is selected from alcohols, glycols, acetate esters, ketones, and the like. These may be a single species or a mixture of two or more species.
Then, the high refractive index layer-forming coating material is applied onto the conductive medium refractive index layer, and dried at 70 to 130 ° C. for 1 minute or longer to form a high refractive index layer. The film thickness is preferably set to 1.2 to 2.5 times the optical film thickness of the low refractive index layer. The film thickness design related to anti-reflection so far is to set the film thickness of the high refractive index layer and low refractive index layer to 1/4 of the wavelength (hereinafter referred to as the bottom wavelength) indicating the target minimum reflectance Although generally known, when an antireflection film is produced by this method, the reflectance at the bottom wavelength is the lowest, but the reflectance on the longer wavelength side and the lower wavelength side is increased, The reflected color of the portion becomes strong, and the color reflects a tight blue-purple to red-purple color. Furthermore, it leads to an increase in the visibility reflectance that is an index of the reflectance with the eyes. As a result of studies to suppress the increase in the reflectance on the long wavelength side and the low wavelength side, as described above, the optical film thickness of the low refractive index layer is 1.2 to 2.5 times larger than the conventional design method. I found out that it can be solved by designing.
Regarding the drying temperature, if it exceeds 130 ° C., it may cause thermal deformation depending on the transparent plastic film used. On the other hand, if it is less than 70 ° C., the curing rate is slow and sufficient strength may not be exhibited. Also, if the curing time is less than 1 minute, the film strength may be insufficient.
The coating method can be appropriately selected from, for example, a bar coating method, a gravure coating method, a slit coater method, a roll coater method, a dip coating method, and the like.

The low refractive index layer laminated on the high refractive index layer is a high refractive index coating material for forming a low refractive index layer containing, for example, silicon alkoxide and / or a hydrolysis product thereof, silicone oil, and an organic solvent. It is formed by coating on the rate layer and drying.
The refractive index of the low refractive index layer is preferably 0.1 or more smaller than the refractive index of the high refractive index layer. By providing such a transparent low refractive index layer, the resulting antireflection layer exhibits extremely excellent antireflection properties. The silicon alkoxide used as the coating material for forming the low refractive index layer can be appropriately selected from tetraalkoxysilane compounds and alkyltrialkoxysilane compounds.
Moreover, as said silicone oil, it can use from a dialkyl alkoxysilane compound suitably. Furthermore, the organic solvent can be appropriately selected from alcohols, glycols, acetates, and ketones, and these may be used alone or in combination of two or more. .
When 0.01 to 5.0 mass% of silicone oil is contained in the coating material for forming the transparent refractive index layer, the contact angle of the coating film with water becomes 90 ° or more, water repellency is exhibited, it becomes slippery, The film strength (particularly steel wool strength) of the transparent film with an antireflection film is improved, and antifouling properties can be imparted.
When the content of the silicone oil is less than 0.01% by mass, the silicone oil does not sufficiently bleed on the surface of the transparent low refractive index layer, the contact angle with respect to water becomes less than 90 °, and sufficient water repellency cannot be obtained. The film strength improvement and antifouling property of the transparent film with an anti-reflection / anti-reflection film may not be obtained. If the content exceeds 5.0% by mass, the silicone oil becomes excessive on the surface of the transparent low refractive index layer, so that the contact angle with water exceeds 90 ° and sufficient water repellency is obtained. In order to inhibit the polymerization and curing reaction of the hydrolysis product, the film strength of the transparent film with an antistatic / antireflection film may be reduced.
The low refractive index layer is formed by applying the transparent low refractive index layer coating material on the transparent high refractive index layer and drying it at 70 to 130 ° C. for 1 minute or more to adjust the optical film thickness to 140 nm. Thus, an antistatic / antireflection film having a bottom wavelength of around 600 nm can be produced.
If the drying temperature exceeds 130 ° C, it may cause thermal deformation depending on the transparent plastic film used. On the other hand, if it is less than 70 ° C., the curing rate is slow and strength may not be exhibited. Also, if the curing time is less than 1 minute, the film strength may be insufficient.
The coating method can be appropriately selected from, for example, a bar coating method, a gravure coating method, a slit coater method, a roll coater method, a dip coating method, and the like.
The antistatic / antireflection film prepared by the above method has characteristics such as a good antistatic effect and antireflection property, high film hardness, and antifouling property. The reason is considered as follows.
The presence of a large amount of inorganic compound filler in the transparent hard coat layer, the transparent conductive medium refractive index layer, and the transparent high refractive index layer increases the surface energy of the layer, thereby improving the wettability of each paint on the surface of each layer. It can be remarkably improved, and the adhesiveness between the layers is improved by the effect of improving the wettability, whereby a stronger film strength can be obtained than before.
Furthermore, the transparent low refractive index layer which is the outermost layer contains silicone oil, and the contact angle with water exceeds 90 °, so that water repellency can be imparted. This water repellent effect is sufficiently maintained even when rubbed with a cotton cloth or the like, and higher antifouling properties than before can be obtained. The reason why the antifouling property is maintained is considered that the silicone oil is incorporated in the silica matrix and does not easily ooze out.

(Electromagnetic wave shielding layer)
In the optical filter of the present invention, there is no particular limitation on the configuration and composition of the electromagnetic wave shielding layer formed on the other surface of the transparent substrate, and the electromagnetic filter is formed to have electromagnetic wave shielding properties and image transparency. For example, a metal mesh layer, a transparent conductive film containing a conductive substance, or the like can be used.
For example, the metal mesh layer is formed by laminating a metal mesh on a transparent base material, or etching a metal layer formed by plating a metal such as copper to form a mesh pattern, and a transparent base material. A paste containing a catalyst such as palladium printed in a mesh pattern shape and plated on the surface can be used. Here, as what stuck the metal mesh to the transparent base material, what made the metal mesh or the thing which stuck the mesh which plated the metal on the surface of a fiber is used. For example, as the transparent conductive film layer, a conductive material such as silver formed by vapor deposition, sputtering, or the like is used.
Furthermore, the thickness of the electromagnetic wave shielding layer is preferably 1 to 10 μm. When a metal mesh layer is used as the electromagnetic wave shielding layer, if the thickness of the metal mesh layer is greater than 10 μm, the viewing angle is narrowed and visibility is lowered. Further, even if the surface is blackened, when viewed from an oblique direction, the depth direction of the metal mesh is difficult to be blackened, and the color tone of the metal is exposed, which causes a problem in the color tone of the screen.
Moreover, it is good also considering the edge part of 2 sides which mutually opposes a metal mesh layer as a solid metal film.

(Adhesive layer)
In the optical filter of the present invention, the adhesive layer formed on the near-infrared shielding layer is formed of a transparent adhesive (including an adhesive), and an acrylic resin is used as such an adhesive. it can. When the adhesive layer is formed of a pressure-sensitive adhesive, the adhesive strength between the adhesive layer and the near-infrared shielding layer is preferably 1 to 10 N / 25 mm in the initial stage, more preferably 4 to 8 N / 25 mm. is there. When the adhesive strength is in the range of 1 to 10 N / 25 mm, when the optical filter is adhered to the display surface of the display, it can be sufficiently adhered to practical use, and it is necessary to peel off the optical filter. When this happens, it can be peeled off without any practical difficulty, the expensive display body can be used continuously, and the peeled optical filter can be reused. Further, the adhesive strength increases with time, and the adhesive strength when the equilibrium is reached is more preferably 10 to 15 N / 25 mm.

(Optical filter manufacturing method)
In the optical filter of the present invention, an antireflection layer is formed on one surface of a transparent substrate having ultraviolet absorption performance, and then an electromagnetic wave shielding layer is formed on the back surface thereof. Further, a near infrared shielding layer is formed on the electromagnetic shielding layer by a printing method such as a screen printing method. At this time, it is preferable that the near-infrared shielding layer and the adhesive layer are exposed on the portion where the ground electrode lead-out portion is formed without being covered. Even when a metal mesh is used as the electromagnetic shielding layer, the dye containing ink for forming the near infrared shielding layer is printed on the metal mesh layer by a printing method such as a screen printing method. It is possible to omit the defoaming process and the clearing process. The near-infrared shielding layer and the adhesive layer may contain a coloring material for adjusting the color tone and transmittance of the optical filter.

When the optical filter of the present invention is used, it is directly attached to the image display surface glass of the PDP module, so that the PDP of 42 inch size is approximately 4 kg and 50 inch size PDP compared to the case of using the conventional filter with glass. The weight reduction of about 5 kg can be achieved. In addition, the optical filter itself is substantially composed of a single film-like laminate, so that it is approximately 30% lighter and the optical filter is about 40 mm thicker than conventional two-film filters. % Can be made thinner.
In addition, the number of sheets used as the transparent base material is a minimum, and the amount of adhesive used for bonding is reduced, which enables a significant cost reduction.

1- (a) and (b), when used in the optical filter 1 of the present invention, a part of the peripheral edge of the electromagnetic wave shielding layer 13, for example, the optical filter has a quadrilateral shape, particularly a rectangular shape. Of the four sides, that is, at least two opposite sides (ie, the upper and lower two sides 13a as shown in FIG. 1- (b), or the left and right sides as shown in FIG. The near-infrared shielding layer 14 is formed by a printing method (preferably a screen printing method) so that the ground electrode lead-out portion 13c is exposed at the edge of the two sides 13b), and then an adhesive layer (adhesive) 15) is preferably formed by direct coating such as a gravure method or by laminating a non-carrier film.
The ground electrode take-out portion is effective for converting electromagnetic waves leaked from a display such as a plasma panel into electricity and letting it escape to the casing.

  In the embodiment of the optical filter of the present invention shown in FIG. 2, the left and right two edge portions 13b of the electromagnetic wave shielding layer 13 are formed into a solid metal film in a band shape by treatment such as electroplating or conductive tape. May be. The near-infrared shielding layer 14 is left on the electromagnetic wave shielding layer 13 having the left and right belt-like edge portions 13b formed into a solid metal film so that the upper and lower two edge portions 13a are exposed. May be coated (not shown). In this case, the solid metal film portions exposed at the left, right, upper, and lower four corners of the left and right belt-like edge portions 22b formed into a solid metal film can be used as the ground electrode extraction portion.

  An example of a state in which the optical filter of the present invention is mounted on a display surface of an image display device, for example, an image display surface of a PDP module is shown in FIG. In FIG. 3, it is directly attached to the image display surface, for example, the surface of the image display glass 23 of the PDP module 21, and the peripheral edge thereof is bonded and held to the housing 22 of the module 21. The upper and lower edges of the electromagnetic wave shielding layer 13 are provided with ground electrode take-out portions, and a ground 24 is attached. The ground 24 is directly attached to the housing 22 as shown in FIG. It may be connected or may be electrically connected to the grounding means via a clip, clamp or gasket (not shown).

  The optical filter of the present invention is further illustrated by the following examples.

Example 1
Using a PET film containing an ultraviolet absorber with a thickness of 100 μm as a transparent substrate, an antireflection layer composed of a hard coat layer, a conductive middle refractive index layer, a high refractive index layer, and a low refractive index layer is formed on one side thereof, A protective film made of PET was laminated on the surface. Next, a palladium colloid-containing paste is printed on the opposite surface using a screen having a lattice pattern (mesh shape) of L / S = 30/270 (μm), and this is immersed in an electroless copper plating solution. Then, electroless copper plating was applied, followed by electrolytic copper plating, and further by electrolytic plating of a Ni-Sn alloy to form a mesh-like electromagnetic wave shielding layer. Next, on the surface of the electromagnetic wave shielding layer, the following chemical formula:
_{(CH 3 SO 2) 2 N} -
A diimonium dye containing a diimonium compound having a counter ion represented by the formula (II) and a phthalocyanine dye (trademark: EEXCOLOR IR-10A, manufactured by Nippon Shokubai Co., Ltd.) at a mass ratio of 2: 1; An ink containing an acrylate resin adhesive in an amount of 200 times (mass) with respect to the total mass of the pigment, and further containing an ink containing butyl acetate, cyclohexanone, and toluene as a solvent is printed by a screen printing method and dried. A near-infrared shielding layer was formed. Furthermore, an adhesive layer was applied and formed on the near-infrared shielding layer to produce an optical filter.

  “Total light transmittance”, “Haze value”, “Visibility reflectance”, “Pencil hardness”, “Steel wool hardness”, “Adhesion”, “Spectral transmittance (near infrared part) of the obtained optical filter ”,“ Reliability test (change in transmittance in the near infrared region after 1000 hours at high temperature and high humidity) ”, and“ electromagnetic wave shielding ”were evaluated by the following methods. The evaluation results are shown in Table 1.

(Evaluation methods)
(1) Total light transmittance: measured using a haze meter (manufactured by Nippon Denshoku).
(2) Haze value: measured using a haze meter (manufactured by Nippon Denshoku).
(3) Luminous reflectance: It was measured using a spectrophotometer (V-570 manufactured by JASCO Corporation).
(4) Pencil hardness: With the anti-reflective layer facing up, measure the minimum pencil hardness that will not scratch under a 1 kg load.
did.
(5) Steel wool strength: The number of scratches generated after reciprocating 10 times while applying a load of 250 g / cm ² to # 0000 steel wool with the antireflection layer surface facing upward was measured.
(6) Adhesion: With the antireflection layer facing up, cut 1 cm square sides of the film surface at 1 mm intervals.
The number of remaining squares after the surface was peeled three times with adhesive tape
It was measured.
(7) Spectral transmittance: Using a spectrophotometer (V-570 manufactured by JASCO Corporation), the wavelength of each sample is 850 nm.
The transmittance at 950 nm and 1000 nm was measured.
(8) Reliability:
(I) Each sample was placed in a thermostat set to 80 ° C., and the spectral transmittance after 1000 hours was measured.
(Ii) Each sample was placed in a constant temperature and humidity tester set to 60 ° C. and relative humidity 90%, and the light transmittance after 1000 hours was measured.
(9) Electromagnetic wave shielding property: measured in accordance with KEC method (Kansai Electronics Industry Promotion Center method)
did.

  As apparent from Table 1, the optical filter of the present invention has excellent light transmittance, low haze value, low reflectivity, excellent electromagnetic wave shielding property and near infrared ray shielding property, and practically sufficient hardness and It had adhesion.

  The optical filter of the present invention and the method for producing the same are excellent in antireflection, near-infrared shielding, and electromagnetic shielding, excellent in durability, visibility of visible images, lightweight, and easy to manufacture and handle. For example, it has high practicality as an optical filter of a display device such as a plasma display device.

FIG. 1- (a) is a longitudinal cross-sectional explanatory view showing a laminated structure of an example of the optical filter of the present invention. 1B is an explanatory plan view of the optical filter of FIG. 1A viewed from the direction of arrow A. FIG. Plane | planar explanatory drawing of the other example of the optical filter of this invention. FIG. 3 is a partial cross-sectional explanatory view when the optical filter of the present invention is mounted on the display surface portion of the image display device.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Optical filter 11 Transparent base | substrate 12 Antireflection layer 13 Electromagnetic wave shielding layer 13a An example of the upper and lower edge end exposed part (for earth electrode taking-out parts) of the electromagnetic wave shielding layer 13b Solid band-like part of the electromagnetic wave shielding layer 13c Solid Exposed part of metal film strip (for ground electrode lead-out part)
14 Near-infrared shielding layer 15 Adhesive layer (including adhesive layer)
21 Image display device 22 Case 23 Display surface 24 Ground

Claims (7)

  A transparent substrate, an antireflection layer formed on one surface of the transparent substrate, an electromagnetic wave shielding layer formed on the other surface of the transparent substrate, and a near infrared ray formed on the electromagnetic wave shielding layer An optical filter, wherein a shielding layer and an adhesive layer formed on the near-infrared shielding layer are laminated into an integral film.   The optical filter according to claim 1, wherein the electromagnetic wave shielding layer is made of a metal mesh.   The optical filter according to claim 1, wherein the near-infrared shielding layer is formed by a printing method.   And further including two or more ground electrode lead-out portions formed in the electromagnetic wave shielding layer, wherein the ground electrode lead-out portions are provided in at least two locations separated from each other in the peripheral portion of the electromagnetic wave shielding layer. Item 3. The optical filter according to Item 1 or 2.   The optical filter according to claim 1, wherein the transparent substrate has ultraviolet absorption performance.   Forming an antireflection layer on one surface of the transparent substrate, then forming an electromagnetic shielding layer on the other surface of the transparent substrate, forming a near infrared shielding layer on the electromagnetic shielding layer, Furthermore, the manufacturing method of the optical filter characterized by forming an adhesive layer on the said near-infrared shielding layer, and comprising an integral film-like laminated body.   When forming the near-infrared shielding layer and the adhesive layer on the electromagnetic wave shielding layer, at least two edge portions of the edge portion of the electromagnetic wave shielding layer that are separated from each other are taken out from the ground electrode. The method for producing an optical filter according to claim 6, wherein the optical filter is left as a part without being covered.

Images