JP2007057889A - Optical filter and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical filter which is excellent in anti-reflection property, near-infrared ray shielding property, electromagnetic wave shielding property, usage durability, lightness and manufacture/usage convenience. <P>SOLUTION: By joining the near-infrared ray shielding layer of a composite film layer which is obtained by forming an anti-reflection layer on one surface of a transparent base body and forming the near-infrared ray shielding layer on the other surface and the electromagnetic shielding material layer of a stacked body layer which is obtained by separately forming front surface and rear surface adhesive layers respectively on both front surface/rear surfaces of the electromagnetic shielding material layer via the surface adhesive layer, the composite film layer and the stacked body layer are integrated. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

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

  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 a shape such 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, as described in, for example, Japanese Patent Laid-Open No. 10-319859 (Patent Document 1), a PDP device including a light emitting unit is placed 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. In addition, the “direct attachment” filter, which directly attaches the filter to the front glass of the plasma display panel, is constructed by laminating multiple sheets of film, making it impossible to further reduce weight, simplify production processes, and reduce costs. was there.
Japanese Patent Laid-Open No. 10-319859

  The present invention has excellent antireflection properties, near-infrared shielding properties, and electromagnetic wave shielding properties, is excellent in durability and visibility, and is formed into a single film-like laminate, so that it is lightweight. An object of the present invention is to provide an optical filter that is easy to manufacture and handle and is useful for a display surface of a display device such as a plasma display device.

The optical filter of the present invention includes a transparent base material, and a near-infrared shielding layer having an anti-reflection layer formed on the other surface of the transparent base material and having a near-infrared shielding performance. A composite film layer, and an electromagnetic wave shielding material layer and a laminate layer having a front surface and a back surface adhesive layer formed on both the front and back surfaces thereof, and the electromagnetic wave shielding material layer includes the front surface interview The film is bonded to the near-infrared shielding layer via an adhesive layer, and is configured as an integral film-like laminate as a whole.
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 front surface adhesive layer covers the other part of the electromagnetic wave shielding material layer so that the electrode part is exposed, and covers the other part of the electromagnetic wave shielding material layer. Preferably, the back surface adhesive layer covers the entire other surface of the electromagnetic wave shielding material layer.
In the optical filter of the present invention, it is preferable that the surface of the electromagnetic wave shielding material layer is covered with a black metal.
In the optical filter of the present invention, the electromagnetic wave shielding material layer electrode portion includes two or more ground electrode extraction portions, and the ground electrode extraction portions are separated from each other at the peripheral portion of the electromagnetic wave shielding material layer. It is preferable to be provided at a location.
In the optical filter of the present invention, it is preferable that the transparent substrate contains an ultraviolet absorber.
In the method for producing an optical filter of the present invention, an antireflection layer is formed on one surface of a transparent substrate, a near-infrared shielding layer is formed on the other surface to form a composite film layer, and an electromagnetic wave shielding material layer. A front surface and a back surface adhesive layer are respectively formed on the front and back surfaces of each to form a laminated body layer, and the electromagnetic wave shielding material layer of the laminated body is disposed through the front surface adhesive layer, A single film-like laminate is formed as a whole by bonding to the near-infrared shielding layer of the composite film layer.
In the method for producing an optical filter of the present invention, when the front surface adhesive layer of the laminate layer is formed, on the one surface of the electromagnetic wave shielding material layer, the electrode portion is left so as to be exposed to other layers. It is preferable to cover the part, and the back surface adhesive layer covers the entire other surface of the electromagnetic wave shielding layer.

The optical filter of the present invention is excellent in antireflection, near-infrared shielding, electromagnetic wave shielding, durability for use, ease of visual observation of images, is lightweight, and therefore easy to manufacture and handle. It is practically useful as an optical filter for display surfaces of various display devices such as plasma display devices.
In addition, since the optical filter of the present invention is a single film-like laminate, it consumes less resources and is environmentally useful compared to conventional filters in which a plurality of films are stacked. .

  As shown in FIG. 1, the optical filter 1 of the present invention has a transparent substrate 11, an antireflection layer 12 formed on one side thereof, and a near-infrared shielding layer 13 formed on the other side. An electromagnetic wave having a composite film layer 21 and a surface adhesive layer 22 on the front surface excluding the electrode portion 22a and a back surface adhesive layer 23 formed on the entire surface on the back surface. The near-infrared shielding layer 13 and the electromagnetic wave shielding material layer 31 are bonded to each other by the front surface adhesive layer 22 and include a single film-like laminate as a whole. Is formed. At this time, the front surface adhesive layer 22 and the back surface adhesive layer 23 are connected to each other through a mesh opening.

In the conventional optical filter, each functional layer described above was formed on a separate transparent substrate, and the transparent substrate having these functional layers was laminated on a glass panel via an adhesive layer. . Further, even in a film-type optical filter that does not use glass, a filter is configured by laminating a plurality of transparent films.
In the optical filter of the present invention, a composite film layer in which an antireflection layer is formed on one surface of a transparent substrate and a near infrared shielding layer having a near infrared shielding performance is formed on the other surface, A composite film comprising a laminate layer composed of an electromagnetic wave shielding material layer having a surface adhesive layer on the front surface, if necessary, excluding the electrode portion, and having a back surface adhesive on the entire rear surface. The layers are joined together through the front adhesive layer so that they form the front surface, and as a whole, a single film-like laminate is formed. Reduction, manufacturing process reduction, high transmittance and low haze can be realized, thereby obtaining improved optical properties.

  Since the optical filter of the present invention has the above-described configuration, it does not contribute to each function, and in some cases, the number of base materials that may have an adverse effect and the number of adhesive layers are reduced. An integrated optical filter having a combination of these functions is constructed. Further, in the laminate layer including the electromagnetic wave shielding layer, a surface pressure-sensitive adhesive layer is formed on the front surface of the electromagnetic wave shielding material layer except for the electrode portion, and on the entire surface of the back surface. Since the back surface pressure-sensitive adhesive layer is formed, when the electromagnetic wave shielding material layer is formed of a metal mesh, it does not require defoaming treatment by pressure or vacuum, which has been necessary conventionally, and a bonding step Since there is no number, the number of manufacturing processes is reduced, the manufacturing 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 transparent laminate, an excellent antireflection effect can be obtained.

  The optical filter of the present invention is a composite film comprising a transparent substrate, an antireflection layer formed on one surface thereof, and a near infrared shielding layer formed on the other surface and having near infrared shielding performance. Separately, an electromagnetic wave shielding material layer, a front surface adhesive layer formed on the front surface other than the electrode portion, and an entire surface of the back surface were formed. A laminated body layer having a back surface adhesive layer is joined by the front surface adhesive layer with the front surface facing the composite film side to form a single film-like laminate. At this time, the near-infrared shielding layer is closer to the panel than the transparent base material containing the ultraviolet absorber, and is protected from external light. Therefore, the near-infrared shielding layer has excellent performance durability, weather resistance, and reliability. It becomes. Further, as the electromagnetic wave shielding layer, the front surface has a surface adhesive layer on the portion excluding the electrode portion, and the back surface uses a metal mesh layer having a back surface adhesive layer on the entire surface, Part of the adhesive on the front and back adhesive layers penetrates into the openings of the metal mesh and connects to and fills them, thereby providing an optical filter free of voids.

(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 von base material, polyacrylate base material, norbonnene base material, amorphous polyolefin base material and the like, and the thickness is not particularly limited, usually about 50 μm to 10 mm A film-like or plate-like material 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 optical filter which has the outstanding characteristic can be formed in the display surface of a plasma display by sticking this optical filter directly on the display surface of a plasma display.

(About UV shielding properties of transparent substrates)
Moreover, in the optical filter of this invention, it is preferable to use the material which has ultraviolet-shielding property for a transparent base material. This is because the near-infrared absorbing dye contained in the adhesive layer usually has low resistance to ultraviolet rays, and by using a material having ultraviolet shielding properties as a transparent substrate, deterioration of the near-infrared absorbing dye can be suppressed. is there. Examples of the ultraviolet absorber include ultraviolet absorbing compounds such as benzophenone, benzotriazole, paraaminobenzoic acid, and salicylic acid. Usually, a sufficient effect cannot be obtained unless the ultraviolet absorber is used in an added amount of a certain amount or more. 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 is 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, it is sufficient to contain an ultraviolet absorber in the transparent substrate itself having a larger thickness than the coating layer. The amount of the ultraviolet absorber can be contained, whereby the deterioration of the near infrared absorbing dye can be suppressed and the excellent near infrared absorbing performance can be maintained. As the ultraviolet shielding performance, 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 formed on one side of the transparent substrate preferably has a shielding property against near-infrared rays in the 800 to 1100 nm region, for example, in a resin matrix It is preferable that a near-infrared absorbing dye is contained.
The near-infrared absorbing dye is not particularly limited as long as it has a near-infrared shielding property in the 800 to 1100 nm region. For example, diimonium compounds, aminium compounds, phthalocyanine compounds, organometallic complex compounds, and cyanine compounds , Azo compounds, polymethine compounds, quinone compounds, diphenylmethane compounds, triphenylmethane compounds, mercaptonaphthol compounds, etc., and these may be used as a single species, or Two or more kinds may be used in appropriate combination.
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 the near-infrared absorbing dye used for the transparent laminate of the invention contains at least one diimonium compound.

In order for the near-infrared shielding layer to exhibit practically sufficient near-infrared shielding properties, it is preferable that the transmittance of near-infrared light having a wavelength of 900 to 1000 nm is 20% or less. The preferred blending amount of the near-infrared absorbing dye in the resin layer having near-infrared shielding performance varies depending on the thickness of the layer, but a diimonium compound is used, and the thickness of the adhesive layer is 5 to 50 μm. When designing to the extent, the blending amount of the near-infrared absorbing dye compound is preferably about 0.5 to 5.0 parts by mass with respect to 100 parts by mass of the transparent resin used as the matrix. 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.
In addition, when a diimonium compound is used, in order to impart practically sufficient durability to the obtained adhesive layer having near-infrared shielding performance, a compound having a melting point of 190 ° C. or higher is used as the diimonium compound. It is preferable. Those having a melting point lower than 190 ° C are likely to be altered under high temperature and high humidity, but those having a melting point of 190 ° C or higher have good practical durability in combination with the selection of a suitable matrix resin type described below. The resin layer which has near-infrared shielding performance which has can be obtained.

Furthermore, it is preferable to use a near-infrared absorptive dye having a wavelength of 850 to 900 nm, or a near-infrared absorbing dye having a wavelength of 850 to 900 nm, in order to develop a practically sufficient near-infrared shielding property in the near-infrared shielding layer. For this purpose, for example, when a diimonium compound is used, as the second near-infrared absorbing dye, one or more kinds having an absorption maximum at 750 to 900 nm and substantially no absorption in the visible light region. The ratio of the absorption coefficient at the absorption maximum wavelength to the respective absorption 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), for example, It is preferable to use one or two or more near-infrared absorbing dyes, each of which is 5.0 or more, and the ratio of the extinction coefficients is more preferably 8.0 or more. When any one of the extinction coefficient ratios is less than 5.0, when the average transmittance of 850 to 900 nm required for practical use is 20% or less, the wavelength is 450 nm (the central wavelength of blue light), 525 nm ( Either the visible light transmittance at 620 nm (center wavelength of green light) or 620 nm (center wavelength of red light) is less than 60%, and the transmittance in the visible light region may be practically insufficient.
It has an absorption maximum at 750 to 900 nm, the absorption coefficient at the absorption maximum wavelength, and each 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) Examples of the second near-infrared absorbing dye compound whose ratio to the extinction coefficient is 5.0 or more include dithiol nickel complex compounds, indolium compounds, phthalocyanine compounds, naphthalocyanine compounds, and the like. It is done. 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.

  As the matrix resin for near-infrared absorbing dye, for example, an acrylic resin and a methacrylic resin can be used, and it is preferable to use a transparent resin having a glass transition point of 60 ° C. or higher. As for, it is desirable that it is either an acrylic resin or a methacrylic resin. If the glass transition point of the transparent resin is less than 60 ° C, the resin softens when exposed to a high temperature of 60 ° C or higher for a long time, and at the same time, the dye in the near-infrared shielding layer, particularly the diimonium dye compound, is altered. For this reason, the color balance of the transparent laminate may be impaired, and the long-term stability may be deteriorated, for example, the near-infrared shielding property may be lowered. On the other hand, when the glass transition point is 60 ° C. or higher, thermal deterioration of the dye, particularly a dye made of a diimonium compound, can be suppressed in the obtained near-infrared shielding layer. When the above resin is used, when the near infrared shielding layer is laminated and bonded to the electromagnetic shielding layer via the adhesive layer, the dye in the near infrared shielding layer is deteriorated, the near infrared shielding layer is distorted or peeled off. Etc. can be prevented. Examples of the resin that satisfies the above requirements include polyester resins, acrylic resins, methacrylic resins, etc., but acrylic resins that are excellent in dyeing properties (fixing properties) of diimonium compounds that are basic dyes. It is preferable to use a resin and / or a methacrylic resin.

  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 the other surface of the transparent substrate are not limited, and may have a single-layer structure or a plurality of structures. Good. A thin film layer having a function such as a conductive layer such as an antistatic layer and / or an antiglare layer 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 intensity | 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 the 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 at 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 visual observation. As a result of studying to suppress the increase of 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, the front surface has an adhesive on the portion excluding the electrode portion, and the back surface has no limitation on the configuration and composition of the electromagnetic shielding layer having the adhesive on the entire surface, and the electromagnetic shielding properties. It may be formed so as to have image transparency, for example, a metal-plated fiber, a metal foil-etched mesh sandwiched with an adhesive, or an adhesive-impregnated one. Can be used. However, the electrode surface of the front surface must not have an adhesive. This is because if the adhesive adheres to the electrode portion on the surface, the electricity converted from the electromagnetic wave by the electromagnetic wave shielding layer cannot be taken out by the ground.
For example, the electromagnetic wave shielding material layer is formed by etching a metal layer formed by plating a metal such as copper into a mesh pattern shape, or etching a metal foil such as copper into a mesh pattern shape. Those formed, or those obtained by plating a metal on the surface of a fiber, or a paste containing a catalyst after mesh pattern printing on a film, plating, and removing the film are 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, you may form a solid metal film in the edge part of 2 sides which mutually opposes an electromagnetic wave shielding material layer.

(Adhesive layer)
In the optical filter of the present invention, the front surface and the back surface adhesive layer formed on both the front and back surfaces of the electromagnetic wave shielding layer are each formed of a transparent adhesive (including an adhesive), and such an adhesive. For example, a silicon-based resin or an acrylic resin can be used. When the front surface and back surface adhesive layers are formed of a pressure-sensitive adhesive, the pressure-sensitive adhesive strength is preferably 1 to 10 N / 25 mm in the initial stage, and more preferably 4 to 8 N / 25 mm. . When the adhesive strength is in the range of 1 to 10 N / 25 mm, when the optical filter is adhered to the surface of the PDP panel, it is possible to hold the adhesive sufficiently for practical use, and it is necessary to peel off the optical filter. Sometimes, it can be peeled off without any particular difficulty in practical use, 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 at the time when equilibrium is reached is more preferably 10 to 15 N / 25 mm. When the electromagnetic wave shielding material layer is formed of a metal mesh, it is preferable that a part of each of the front surface and the back surface adhesive layer penetrates into the opening of the metal mesh and is connected to each other.

(General manufacturing method)
The optical filter of the present invention is a film in which an antireflection layer is formed on a transparent substrate containing an ultraviolet absorber, and then a near infrared shielding layer is formed on the back surface thereof. The back surface is laminated with an electromagnetic wave shielding layer having an adhesive on the entire surface with the front side facing the film. The electromagnetic wave shielding layer may be a full-face mesh or the peripheral part may be a solid part, but the part corresponding to the ground electrode part does not have an adhesive. Since the adhesive is formed directly on the metal mesh without using a film such as a PET film, it requires a process of defoaming and clearing by pressure or vacuum, which was necessary when using a metal mesh film. do not do.

  If the optical filter of the present invention is used, it is possible to significantly reduce the weight of the PDP by attaching it directly to the front glass of the PDP panel. Moreover, since it consists essentially of a single film, it is possible to significantly reduce costs and save resources by reducing the film used as the substrate and the pressure-sensitive adhesive used for bonding.

  As shown in FIG. 2, the electromagnetic wave shielding layer-containing laminate layer 35 used in the optical filter of the present invention is a front surface adhesive formed on a portion of the electromagnetic wave shielding material layer 31 excluding the electrode portion 22a on the front surface. The back surface adhesive layer 23 is formed on the entire back surface of the electromagnetic wave shielding material layer 31. Here, the front surface adhesive layer 22 and the back surface adhesive layer 23 are connected and integrated with each other through the opening of the metal mesh 31. Also, FIG. 3 shows a front view of the optical filter of the present invention. As shown in FIG. 4, a form in which the metal electrode portion 23a formed as a solid metal film is provided on the four sides of the electromagnetic wave shielding material layer 31, or As shown in FIG. 5, a configuration may be adopted in which electrode portions 24 a formed into a solid metal film are provided on the two opposing sides.

  FIG. 6 shows a configuration (cross section) when the transparent laminated optical filter of the present invention is mounted on a PDP. The optical filter of the present invention is directly attached to the display surface 53 of the PDP panel 51 via a back surface adhesive layer. The electrode portion 22a that is not covered with the front surface adhesive layer is attached in a conductive manner via an electrode grounding portion 52 for taking out the electrode or a gasket (not shown).

  The transparent laminate of the present invention will be further described with reference to the following examples, but these examples do not limit the present invention.

Example 1
A PET film having a thickness of 100 μm was used as a transparent substrate, and an antireflection layer composed of a hard coat layer and a low refractive index layer was formed on one side thereof. Next, the near-infrared absorbing dye and matrix resin are dissolved or dispersed in a solvent on the opposite side, and a near-infrared shielding layer is formed using the resulting solution to create an anti-reflection / infrared shielding film. did. Next, the mesh foil obtained by etching the copper foil is oxidized, the surface is blackened, and in addition, a part of the front surface is secured as an electrode. A front surface adhesive layer made of an agent was bonded, and a back surface adhesive layer made of a non-carrier pressure-sensitive adhesive was also bonded to the entire back surface to create an electromagnetic wave shielding layer-containing laminate. These antireflection / near-infrared shielding layer-containing composite films and electromagnetic wave shielding layer-containing laminates were bonded and integrated using a single wafer laminator 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: The minimum pencil hardness was measured with the antireflection layer surface facing up and not scratching under a load of 750 g.
(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) Adhesiveness: With the anti-reflective layer side up, cut each side of the 1 cm square of the film surface at 1 mm intervals, and measure the number of cells remaining after the surface has been peeled three times with adhesive tape. It was measured.
(7) Spectral transmittance: The transmittance of each sample at wavelengths of 850 nm, 950 nm, and 1000 nm was measured using a spectrophotometer (V-570 manufactured by JASCO Corporation).
(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 according to the KEC method (Kansai Electronics Industry Promotion Center method).

(Test results)
According to the test results of Example 1, the optical filter of the present invention has excellent transmittance, low reflectivity, electromagnetic wave shielding, near-infrared shielding and strength, and is excellent in measurement and durability. Was confirmed.

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

Cross-sectional explanatory drawing of an example of the optical filter of this invention. Cross-sectional explanatory drawing of the laminated body layer of the optical filter of this invention. Front explanatory drawing of the optical filter of this invention. Front explanatory drawing of other examples of the optical filter of this invention. Front explanatory drawing of other examples of the optical filter of this invention. FIG. 4 is a partial cross-sectional explanatory diagram when the optical filter of the present invention is mounted on a PDP.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Optical filter 11 Transparent base material 12 Antireflection layer 13 Near-infrared shielding layer 21 Composite film layer 22 Front surface adhesive layer 23 Back surface adhesive layer 31 Electromagnetic wave shielding material layer 22 (a) Upper and lower sides of electromagnetic wave shielding material layer Edge exposed part (electrode extraction part)
23 (a) Solid metallized strip electrode extraction part of electromagnetic wave shielding material layer 35 Laminate layer 51 PDP
52 Electrode grounding part 53 Display surface 54 Case

Claims (8)

  A near-infrared shield substantially consisting of a single substrate, wherein a transparent substrate and an antireflection layer formed on one surface thereof are formed on the other surface of the transparent substrate and have near-infrared shielding performance A composite film layer including a layer, and an electromagnetic wave shielding material layer and a laminate layer having a front surface and a back surface adhesive layer formed on both front and back surfaces thereof, the electromagnetic wave shielding material layer, An optical filter, which is bonded to the near-infrared shielding layer via a front surface adhesive layer, and is configured as an integral film-like laminate as a whole.   The optical filter according to claim 1, wherein the electromagnetic wave shielding layer is made of a metal mesh.   The front surface adhesive layer is coated on the one surface of the electromagnetic wave shielding material layer, covering the other part so that the electrode portion is exposed, and adhered to the near infrared shielding layer, The optical filter according to claim 1, wherein the back surface adhesive layer covers the entire other surface of the electromagnetic wave shielding material layer.   The optical filter according to claim 1, wherein a surface of the electromagnetic wave shielding material layer is covered with a black metal.   The electromagnetic wave shielding material layer electrode portion includes two or more ground electrode take-out portions, and the ground electrode take-out portions are provided in at least two locations that are separated from each other in the peripheral portion of the electromagnetic wave shielding material layer. Item 5. The optical filter according to Item 1.   The optical filter according to claim 1, wherein the transparent substrate contains an ultraviolet absorber.   An antireflection layer is formed on one surface of the transparent substrate, a near-infrared shielding layer is formed on the other surface, and a composite film layer is formed. And a back surface adhesive layer is formed to form a laminated body layer, and the electromagnetic wave shielding material layer of the laminated body is bonded to the near infrared shielding layer of the composite film layer through the front surface adhesive layer. Then, the manufacturing method of the optical filter characterized by including forming a single film-like laminate as a whole.   When forming the front surface adhesive layer of the laminate layer, the other surface of the electromagnetic wave shielding material layer is covered so that the electrode portion is exposed, and the back surface adhesion is performed. The method for producing an optical filter according to claim 7, wherein the agent layer covers the entire other surface of the electromagnetic wave shielding layer.

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