JP2008249770A - Optical filter - Google Patents

Abstract

Provided is a film-like optical filter which has a self-cleaning property and is excellent in near-infrared prevention property, which blocks near-infrared rays which cause malfunction of peripheral electronic equipment generated from a plasma display.
A low refractive index layer and a high refractive index layer are laminated in this order on a film substrate, and the high refractive index layer laminated on the outermost surface is a titanium oxide thin film layer having a thickness of 100 nm or more, At least one of the low refractive index layers is a metal thin film layer, and has a light transmittance of 10% or less for light with a wavelength of 820 nm to 1000 nm and a light transmittance of 50% or more for light with a wavelength of 550 nm. An optical filter in which the amount of iodine in the aqueous KI solution is 10 × 10 ⁻⁵ mol / L or more when the filter is immersed and ultraviolet rays having an intensity in the wavelength range of 360 nm of 800 μW / cm ² are irradiated to the optical filter for 30 minutes.
[Selection] Figure 1

Description

TECHNICAL FIELD The present invention relates to a film-like optical filter having an antifouling function based on an excellent ability to decompose fats and oils. The present invention relates to a film-like optical filter having self-cleaning properties which is effective for the above.
The present invention also relates to an optical filter excellent in preventing near-infrared leakage generated from a plasma display or the like.

  By providing a titanium oxide thin film on the glass, it is transparent to light in the visible light region, has a smooth surface and is not easily soiled, and has a high photocatalytic activity. The cover glass for instrument which has the property is implement | achieved (refer patent document 1).

  Moreover, since a plasma display generates a strong leakage electromagnetic field and near infrared light due to its structure, it is necessary to prevent the leakage electromagnetic field from affecting the human body and other devices. The generated near-infrared light acts on peripheral electronic devices such as cordless phones, causing a problem of causing malfunction. Wavelengths that are particularly problematic include 820 nm, 880 nm, and 980 nm that are used for remote control and transmission optical communication, and it is necessary to cut light in the wavelength range of 820 to 1000 nm, which is the near infrared range. In addition to the plasma display, it is preferable to attach an optical filter that cuts light in this region to light that generates light in the near infrared region.

Therefore, a multilayer thin film in which a metal thin film and a high-refractive-index transparent thin film are laminated is made conductive by preventing the reflection of the high-refractive-index transparent thin film by a metal in a certain wavelength region and the conductivity and optical characteristics of a metal such as silver. It has preferable characteristics in all of its properties, near-infrared cutting ability, and visible light transmittance, and is used. For example, by alternately stacking a metal layer mainly composed of silver and a transparent high refractive index layer, for example, indium oxide, titanium oxide, zinc oxide, and tin oxide, a film having both transparency and the above-mentioned dimming property can be obtained. (See Patent Document 2 and Patent Document 3).
Japanese Patent Laid-Open No. 9-72761 JP-A-10-73719 JP 2001-149790 A

  An object of the present invention is to provide a film-like optical film having excellent near-infrared prevention properties that imparts self-cleaning properties to a film-like optical filter and blocks near-infrared rays that cause malfunction of peripheral electronic devices generated from, for example, a plasma display. Is to provide a filter. Accordingly, it is also an object to save the trouble of performing the antifouling treatment on the outermost surface layer of the optical filter.

  For example, by alternately stacking a metal layer mainly composed of silver and a high refractive index transparent thin film layer (for example, indium oxide, titanium oxide, zinc oxide, tin oxide), it has both transparency and the above-mentioned dimming property. In a film-like optical filter, even though titanium oxide is used as the high refractive index transparent thin film layer as the outermost surface layer, it was not intended to have self-cleaning properties. For the purpose of surface protection, the resurface is often a protective layer such as a transparent resin layer. It has been found that by using titanium oxide as the outermost surface layer, it is possible to achieve both self-cleaning properties and, for example, transparency and the above-mentioned dimming property.

The invention according to claim 1 is a composite layer in which a low refractive index layer and a high refractive index layer are laminated in this order on at least one surface of a film substrate, and the low refractive index layer and the high refractive index layer are formed. Is an optical filter in which one or more are laminated,
The high refractive index layer laminated on the outermost surface is a titanium oxide thin film layer having a thickness of 100 nm or more,
At least one of the low refractive index layers is a metal thin film layer;
The light transmittance for light with a wavelength of 820 nm to 1000 nm is 10% or less,
The light transmittance for light having a wavelength of 550 nm is 50% or more,
When the optical filter is immersed in an aqueous potassium iodide solution and the optical filter is irradiated with ultraviolet rays having an intensity in the wavelength range of 360 nm of 800 μW / cm ² for 30 minutes, the amount of iodine in the aqueous potassium iodide solution is 10 ×. 10 ⁻⁵ mol / L or more,
It is an optical filter characterized by the above.

  The invention according to claim 2 is the optical filter according to claim 1, wherein the high refractive index layer laminated on the outermost surface is a titanium oxide thin film layer having a film thickness of 100 nm to 3 μm. .

  The invention according to claim 3 is the optical filter according to claim 1 or 2, wherein the metal thin film layer is made of silver and has a thickness of 4 to 30 nm.

The invention according to claim 4, wherein the thickness the low refractive index layer in contact with the titanium oxide thin film layer laminated on the outermost surface as a main component SiO ₂ is a SiO ₂ layer is 1μm or less It is an optical filter in any one of Claims 1-3.

  Invention of Claim 5 is a display formed by bonding the optical filter in any one of Claims 1-4 on the transparent base material.

  According to the present invention, it is possible to provide a film-like optical filter having excellent near-infrared blocking ability and having self-cleaning properties. Further, it is possible to save the trouble of performing the antifouling treatment on the outermost surface layer of the optical filter.

Hereinafter, the present invention will be described in more detail.
The film substrate in the present invention is a transparent polymer film, polyethylene terephthalate, polyethersulfone, polystyrene, polyethylene naphthalate, polyarylate, polyetheretherketone, polycarbonate, polypropylene, polyimide, triacetylcellulose, polymethylmethacrylate However, polyethylene terephthalate is preferably used because it has appropriate heat resistance. Since the base material is a film, a high refractive index layer (high refractive index transparent thin film layer) and a low refractive index layer (metal thin film layer) can be continuously formed by a roll-to-roll method. When this is used, it can be efficiently produced, and since the base material is a film, it is prevented from scattering when the optical film is attached to the glass of the display, so it is also used suitably. it can. In this case, a film base having a thickness of 10 to 250 μm is usually used. This is because if the thickness of the film substrate is too thin, the mechanical strength as the substrate is insufficient, and if it is too thick, the flexibility is insufficient, so that the film substrate is not suitable for being wound with a roll.

  In the optical filter of the present invention, a low-refractive index layer and a high-refractive index layer are laminated in this order on at least one surface of a film substrate, and a composite layer composed of the low-refractive index layer and the high-refractive index layer is 1 The high refractive index layer laminated above and laminated on the outermost surface is composed of a titanium oxide thin film layer. Thereby, antifouling functions, such as fat and oil decomposition, can be added. The film thickness of the high refractive index layer laminated on the outermost surface is preferably in the range of 100 nm to 3 μm, and if it is less than 100 nm, sufficient photocatalytic activity cannot be obtained, and if it exceeds 3 μm, transparency becomes a problem. When transparency is unnecessary, there is no limitation on the upper limit of the thickness.

  For the formation of the titanium oxide thin film layer, any of conventionally known methods such as sputtering, ion plating, ion beam assist, vacuum deposition, and wet coating can be employed. Among these, sputtering is suitable for film thickness control and multilayer lamination, and a metal thin film layer and a high refractive index transparent thin film layer can be formed easily and continuously.

  Moreover, near infrared rays can be cut by using at least one of the low refractive index layers as a metal thin film layer. If the metal thin film layer is thickened, the visible light transmittance is also lowered, and if it is made too thin, the reflection of near infrared light is weakened. Therefore, in order to increase the near-infrared reflectance and visible light transmittance, a laminated structure in which a metal thin film layer is sandwiched between high refractive index layers is formed, and the overall thickness of the metal thin film layer is reduced by stacking one or more layers. May increase.

  The thickness of the metal thin film layer is determined optically and experimentally from conductivity, optical characteristics, etc., and is not particularly limited as long as it has the required characteristics. However, since it is preferable that the thin film is not an island structure but a continuous state from the viewpoint of conductivity or the like, it is desirable that the thickness be 4 nm or more. On the other hand, if the metal thin film layer is too thick, transparency becomes a problem, so 30 nm or less is desirable. Specific examples of the metal thin film include silver, gold, platinum, palladium, nickel, chromium, zinc, zirconium, titanium, tungsten, tin, and the like, or an alloy made of two or more of these materials. Among these, silver is preferably used because it is excellent in conductivity, infrared reflectivity, and visible light transmittance when multilayered. However, since silver is not necessarily excellent in chemical and physical stability, it deteriorates due to environmental pollutants, heat, light, etc., so it is stable to silver, gold, platinum, palladium, indium, tin, etc. An alloy mainly composed of silver containing one or more kinds of metals is also preferably used. However, when other metals are added to silver, the excellent conductivity is hindered. Therefore, if possible, when the metal thin film layer is a multilayer, it is preferable to use one or more layers without forming an alloy of silver. For the formation of the metal thin film layer, any conventionally known method such as sputtering, ion plating, vacuum deposition, or plating can be employed.

  As the high refractive index layer other than the outermost surface formed under the metal thin film layer, as long as it has transparency in the visible range and has the effect of preventing light reflection in the visible range in the metal thin film layer, The material is not particularly limited. Preferably, a high refractive index material having a refractive index with respect to visible light of 1.6 or more, more preferably 1.7 or more is used. Specific materials for forming such a transparent thin film include oxides such as indium, titanium, zirconium, bismuth, tin, zinc, antimony, tantalum, cerium, neodymium, lanthanum, thorium, magnesium, and gallium. Examples thereof include a mixture of oxides and zinc sulfide. These oxides or sulfides can be used as long as they do not significantly change the optical characteristics even if the stoichiometric composition of metal and oxygen or sulfur is different. Among them, indium oxide or a mixture of indium oxide and tin oxide (ITO) can be suitably used because of its high film forming speed and good adhesion to a metal thin film layer in addition to transparency and refractive index. . Further, by using an oxide semiconductor thin film having a relatively high conductivity such as ITO, the electromagnetic wave absorbing layer can be increased and the conductivity of the electromagnetic wave shield can be increased. The thickness of the high refractive index layer is optically designed and experimentally determined from the optical characteristics of the transparent polymer film, the thickness of the metal thin film layer, the optical characteristics, the refractive index of the transparent thin film layer, etc., and is particularly limited. However, it is preferably 5 nm or more and 200 nm or less.

The optical filter has a low refractive index, such as a silicon oxide film, between the high refractive index layer laminated on the outermost surface and the film base material in order to control the transmittance of visible light and near infrared light. A plurality of transparent thin film layers may be included. According to the present invention, by providing a low-refractive-index transparent thin film layer made of a material containing SiO ₂ as a main component and having a thickness of 1 μm or less, a photocatalyst can be obtained by providing the best transparency and preventing material penetration into the titanium oxide thin film. It is possible to ensure the effect of preventing the decrease in action. Such a low refractive index transparent thin film layer made of a material mainly composed of SiO ₂ and having a thickness of 1 μm or less is preferably arranged so as to be in contact with the titanium oxide thin film layer laminated on the outermost surface.

  According to the present invention, the near-infrared cut performance can be preferably achieved by setting the light transmittance for light having a wavelength of 820 nm to 1000 nm to at least 10% or less.

  According to the present invention, the light transmittance for light having a wavelength of 550 nm is 50% or more, and thus visibility is not impaired. Furthermore, the average transmittance in the visible light region is preferably 50% or more.

According to the present invention, when the optical filter is immersed in an aqueous potassium iodide solution and the ultraviolet light having an intensity in the wavelength range of 360 nm of 800 μW / cm ² is irradiated onto the optical filter for 30 minutes from directly above, the iodide is When the amount of iodine in the aqueous potassium solution is 10 × 10 ⁻⁵ mol / L or more, it can efficiently decompose oils and fats such as dirt and oils, and sterilize and antibacterial adhering floating bacteria and molds it can.

By laminating the optical filter of the present invention as described above on a transparent substrate, a configuration for a display that can be suitably used for a plasma display can be achieved.
Examples of the transparent substrate include inorganic compound moldings such as glass and quartz and transparent organic polymer moldings, but organic polymer moldings can be used more suitably because they are light and difficult to break. The organic polymer molded article only needs to be transparent in the visible wavelength region, and specific examples thereof include plastic plates such as polymethyl methacrylate (PMMA), acrylic resin, polycarbonate resin, transparent ABS resin, and the like. Although it can be used, it is not limited to these resins. In particular, PMMA can be suitably used because of its high transparency in a wide wavelength region and high mechanical strength. The thickness of the plastic plate is not particularly limited as long as sufficient mechanical strength and rigidity to maintain flatness without bending are obtained, but it is usually about 1 mm to 10 mm.

  Arbitrary pressure-sensitive adhesives or adhesives can be used for bonding to the transparent substrate. The adhesive or adhesive may be on the sheet or in liquid form as long as it has practical adhesive strength, and is bonded by laminating each member after the adhesive sheet is applied or after application of the adhesive. . The liquid is an adhesive that is cured by being left at room temperature or heated after coating and bonding. Examples of the coating method include a bar coating method, a reverse coating method, a gravure coating method, a die coating method, and a roll coating method. Which one is adopted is selected in consideration of the type of adhesive, viscosity, coating amount, and the like. Although the thickness of an adhesive or an adhesive bond layer is not specifically limited, It is 0.5 micrometer-50 micrometers, Preferably it is 1 micrometer-30 micrometers.

  EXAMPLES Hereinafter, although an Example and a comparative example further demonstrate this invention, this invention is not restrict | limited to the following example.

Example 1
A polyethylene terephthalate film having a thickness of 100 μm is used as a film substrate. From the outermost surface layer, a titanium oxide thin film layer 150 nm, a silver thin film layer 8 nm, a titanium oxide thin film layer 60 nm, a silver thin film layer 12 nm, a titanium oxide thin film layer 50 nm, and a silver thin film layer An optical filter was formed by laminating the film substrate in the order of 12 nm, titanium oxide thin film layer 50 nm, and silver thin film layer 8 nm. The transmittance | permeability with respect to various wavelengths of the optical filter obtained in FIG. 1 is shown.

About the obtained optical filter, the photocatalytic characteristic was investigated in the following ways.
In an aqueous potassium iodide solution produced by an oxidation reaction when an optical filter is immersed in an aqueous potassium iodide solution and ultraviolet light having an intensity of 800 μW / cm ² in a wavelength region of 360 nm is irradiated to the optical filter from directly above for 30 minutes. Analyze the amount of iodine. It shows that the higher the amount of iodine produced, the higher the photocatalytic properties.
(Optical filter of Example 1) About 10 × 10 ⁻⁵ mol / L
(Reference example: commercially available photocatalytic material) 2 to 40 × 10 ⁻⁵ mol / L
A similar self-cleaning effect can be obtained by laminating a plurality of thin film layers under the titanium oxide thin film layer or by providing a thin film layer mainly composed of SiO ₂ under the outermost titanium oxide thin film layer.

Comparative Example 1
A polyethylene terephthalate film 100 μm is used as a base film, and from the outermost surface layer, a titanium oxide thin film layer 15 nm, a silver thin film layer 8 nm, a titanium oxide thin film layer 60 nm, a silver thin film layer 12 nm, a titanium oxide thin film layer 50 nm, a silver thin film layer 12 nm, and an oxide. An optical filter was prepared by laminating a titanium thin film layer of 50 nm and a silver thin film layer of 8 nm on the film substrate in this order. Similar to the examples, the amount of iodine produced was analyzed. As a result, the amount of iodine produced was 2 × 10 ⁻⁵ mol / L or less, and no self-cleaning effect was observed.

  The optical filter of the present invention has an antifouling function based on an excellent ability to decompose fats and oils. Especially, it effectively decomposes fats and oils such as dirt and fats and is effective for sterilization and antibacterial of adhering floating bacteria and mold It is useful for various displays such as a plasma display because of its excellent self-cleaning property and excellent near-infrared leakage prevention property.

It is a figure which shows the transmittance | permeability with respect to various wavelengths of the optical filter obtained in Example 1. FIG.

Claims (5)

An optical filter in which a low refractive index layer and a high refractive index layer are laminated in this order on at least one surface of a film substrate, and one or more composite layers comprising the low refractive index layer and the high refractive index layer are laminated. Because
The high refractive index layer laminated on the outermost surface is a titanium oxide thin film layer having a thickness of 100 nm or more,
At least one of the low refractive index layers is a metal thin film layer;
The light transmittance for light with a wavelength of 820 nm to 1000 nm is 10% or less,
The light transmittance for light having a wavelength of 550 nm is 50% or more,
When the optical filter is immersed in an aqueous potassium iodide solution and the optical filter is irradiated with ultraviolet light having an intensity of 800 μW / cm ² in a wavelength region of 360 nm for 30 minutes, the amount of iodine in the aqueous potassium iodide solution is 10 ×. 10 ⁻⁵ mol / L or more,
An optical filter characterized by that.   2. The optical filter according to claim 1, wherein the high refractive index layer laminated on the outermost surface is a titanium oxide thin film layer having a thickness of 100 nm to 3 [mu] m.   The optical filter according to claim 1, wherein the metal thin film layer is made of silver and has a thickness of 4 to 30 nm. To claim 1, wherein the low refractive index layer in which the contact with the titanium oxide thin film layer laminated on the outermost surface, characterized in that the thickness mainly composed of SiO ₂ is a SiO ₂ layer is 1μm or less The optical filter described.   A display comprising the optical filter according to claim 1 bonded on a transparent substrate.

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