JP2012042918A - Optical filter for display - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical filter for a display which has an adhesive layer containing a near-infrared ray shielding agent and which exerts adequate near-infrared ray shielding effect and suppresses deterioration of the near-infrared ray shielding agent without high cost.SOLUTION: An optical filter for a display comprises an adhesive layer containing: tungsten oxide and/or composite tungsten oxide as a near-infrared ray shielding agent; fine particles with an average particle diameter of 0.1 to 20 μm; and an adhesive.

Description

  The present invention relates to an optical filter for a display used in an image display part of a display such as a plasma display panel (PDP), a cathode ray tube (CRT) display, a liquid crystal display, an organic EL (electroluminescence) display, etc. The present invention relates to an optical filter for display.

  In a display such as a plasma display panel (PDP), an optical filter is usually installed on the front surface (viewer side). The optical filter is used for the purpose of cutting near infrared rays, improving color reproducibility (emission color purity improvement), electromagnetic wave shielding, improving bright contrast (antireflection), protecting the light emitting panel, blocking heat from the light emitting panel, and the like.

  In particular, the near-infrared light emitted from the PDP light-emitting panel needs to be reduced in order to avoid malfunctioning a remote controller used for home television, video, or the like. In addition, the electromagnetic waves emitted by the PDP light-emitting panel must be suppressed in order to avoid adverse effects on the human body and precision equipment. Further, in order to make the light emitted from the light emitting panel of the PDP feel a natural color for human vision, there is a demand for improvement in color reproducibility (light emission color purity improvement) by correction with a filter. Furthermore, it is desirable that the display on the display be visually recognized with sufficient contrast without being hindered by reflection of light from the outside even in a bright place such as a bright room. In addition, even when the display product is directly touched by hand, it is desirable that the heat generated by the light emitting panel of the PDP is cut off in order to avoid a situation where the user is surprised by the high temperature.

  As an optical filter for PDP that meets the above-mentioned purpose, it is generally a function to cut off unnecessary light (light having a wavelength of 560 to 610 nm) due to neon emission for antireflection, near infrared shielding, electromagnetic wave shielding, and color reproducibility improvement. Optical filters having various functions such as (neon cut function) are used. For example, what has a near-infrared shielding function has been developed that includes a cesium-containing tungsten oxide that can shield near-infrared rays in a wide range of wavelengths and has a high visible light transmittance (Patent Document 1). Moreover, what contains a squarylium type compound and azaporphyrin type compound which have the selective absorption function of a specific wavelength as what has a neon cut function is developed (patent document 2).

  In general, an optical filter for PDP is applied to a functional layer having various functions (generally, a coating solution in which the above-described compound or the like is dispersed or dissolved in a thermosetting resin composition, an ultraviolet curable resin composition, or the like is applied on a film. , Cured and formed) a plurality of times and laminated, or an optical filter having one or a plurality of functions is appropriately combined and bonded via an adhesive layer. When the structure of the optical filter becomes complicated in this way, the process of laminating and applying various functional layers and the process of bonding a plurality of optical filters become complicated, which not only increases the manufacturing cost but also increases the optical filter. This will increase the weight and thickness.

  In recent years, optical filters have been required to be lighter and thinner. As a means for that, it is conceivable to reduce the number of functional layers to be laminated in the optical filter and the number of filters to be bonded to simplify the configuration. For example, Patent Document 3 discloses a technique in which a pressure-sensitive adhesive layer contains tungsten oxide and / or composite tungsten oxide useful as a near-infrared shielding agent. By providing a function to the pressure-sensitive adhesive layer that is always used for bonding the optical filter, the configuration of the optical filter can be simplified.

JP 2007-21998 A Japanese Patent Laid-Open No. 2005-92196 JP 2009-271514 A JP 2010-60617 A

  However, as a result of studies by the present inventors, when a near-infrared shielding agent or the like is included in the pressure-sensitive adhesive layer, the near-infrared shielding agent or the like is likely to be deteriorated as compared with the case where it is blended with the above-described thermosetting resin or the like. I knew there was a case. This is considered to be because deterioration of the near-infrared shielding agent or the like is likely to occur due to contact with the pressure-sensitive adhesive component, residue component, decomposition component, or the like in a pressure-sensitive adhesive layer generally having a low glass transition point.

  Patent Document 4 discloses means for stabilizing a dye by using resin fine particles containing a near infrared absorbing dye or the like in a hard coat layer or an adhesive layer. However, in this method, the production of resin fine particles containing a dye is complicated and expensive, and the dispersibility of the dye depends on the dispersibility of the fine particles. The point becomes limited.

  Accordingly, an object of the present invention is an optical filter for a display having a pressure-sensitive adhesive layer containing a near-infrared shielding agent, which exhibits a sufficient near-infrared shielding effect and does not require a high cost. An object of the present invention is to provide an optical filter for display in which deterioration is suppressed.

  An object of the present invention is to provide an optical filter for a display having a pressure-sensitive adhesive layer containing tungsten oxide and / or composite tungsten oxide, fine particles having an average particle size of 0.1 to 20 μm, and a pressure-sensitive adhesive as a near-infrared shielding agent. Achieved by:

  Tungsten oxide and / or composite tungsten oxide (hereinafter also referred to as (composite) tungsten oxide) having high near-infrared absorptivity in the wavelength range of 800 to 1100 nm and high visible light transmittance as a near-infrared shielding agent. Is added to impart a sufficient near-infrared shielding function to the pressure-sensitive adhesive layer. And by mix | blending the microparticles | fine-particles of said average particle diameter, deterioration of (composite) tungsten oxide can be suppressed, without using a complicated means. Although the mechanism of this action is not clear, the presence of fine particles suppresses the decomposition of adhesive components and residue components due to heat, etc., and the contact area between the (composite) tungsten oxide and the adhesive decreases. In addition, it is conceivable that deterioration of the (composite) tungsten oxide due to the decomposition product of the pressure-sensitive adhesive component and the residue component is suppressed, and that fine particles adsorb the decomposition product of the pressure-sensitive adhesive component and the residue component. Moreover, if it is microparticles | fine-particles of the said average particle diameter, the raise of the haze (cloudiness value) of the optical filter for displays will be suppressed.

Preferred embodiments of the optical filter for display according to the present invention are as follows.
(1) The fine particles are transparent resin fine particles or silica fine particles. Thereby, the raise of the haze by microparticles | fine-particles can further be suppressed.
(2) The transparent resin fine particles are at least one fine particle selected from the group consisting of crosslinked acrylic resin fine particles, crosslinked styrene resin fine particles, crosslinked (meth) acrylate-styrene copolymer fine particles, and melamine resin fine particles.
(3) The content of the fine particles is 0.1 to 20% by mass based on the nonvolatile content of the pressure-sensitive adhesive layer. Thereby, the deterioration of the (composite) tungsten oxide can be further suppressed, and the adhesive force of the pressure-sensitive adhesive layer is hardly reduced due to the inclusion of fine particles.
(4) The tungsten oxide is represented by the general formula WyOz (W is tungsten, O is oxygen, and 2.2 ≦ z / y ≦ 2.999), and the composite tungsten oxide Is a general formula MxWyOz (where M is H, He, alkali metal, alkaline earth metal, rare earth element, Mg, Zr, Cr, Mn, Fe, Ru, Co, Rh, Ir, Ni, Pd, Pt, Cu, Ag, Au, Zn, Cd, Al, Ga, In, Tl, Si, Ge, Sn, Pb, Sb, B, F, P, S, Se, Br, Te, Ti, Nb, V, Mo, One or more elements selected from Ta, Re, Be, Hf, Os, Bi and I, W represents tungsten, O represents oxygen, and 0.001 ≦ x / y ≦ 1, 2.2 ≦ z / Y ≦ 3).
(5) The pressure-sensitive adhesive is an acrylic resin-based pressure-sensitive adhesive.
(6) For plasma display panels.

  According to the optical filter for display of the present invention, since (composite) tungsten oxide is blended in the pressure-sensitive adhesive layer, a sufficient near-infrared shielding function is obtained with a simplified layer configuration. Further, since the deterioration of the (composite) tungsten oxide is suppressed without increasing the haze of the optical filter by blending the predetermined fine particles, the optical filter for display has high weather resistance without high cost. be able to.

It is a schematic sectional drawing which shows a typical example of the optical filter for displays of this invention. It is a schematic sectional drawing which shows an example of the suitable aspect of the optical filter for displays of this invention.

  The optical filter of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic sectional view showing a typical example of an optical filter for display according to the present invention.

  As shown in FIG. 1, an optical filter for display 20 of the present invention has a (composite) tungsten oxide as a near-infrared shielding agent on the surface of a rectangular transparent plastic film 11 and fine particles having an average particle size of 0.1 to 20 μm. 19 and a pressure-sensitive adhesive layer 12 including a pressure-sensitive adhesive are formed.

  (Composite) tungsten oxide has high near-infrared absorptivity in the wavelength range of 800 to 1100 nm and high visible light transmittance, and thus is useful as a near-infrared shielding agent for optical filters for displays. Usually, when (composite) tungsten oxide is used, a near-infrared shielding layer is separately formed by coating and curing using a coating liquid blended in a thermosetting resin composition or the like. By providing the pressure-sensitive adhesive layer with a near-infrared shielding function as in the present invention, the layer configuration can be simplified. However, when (composite) tungsten oxide is blended in the pressure-sensitive adhesive layer, the (composite) tungsten oxide may be easily deteriorated. This is presumably because, in a pressure-sensitive adhesive layer having a low glass transition point, the near-infrared shielding agent or the like deteriorates due to contact with a pressure-sensitive adhesive component, a residue component, a decomposition component, or the like.

  In the present invention, the deterioration of the (composite) tungsten oxide is suppressed by blending the fine particles 19. Although the mechanism of this action is not clear, the presence of the fine particles 19 in the pressure-sensitive adhesive layer 12 suppresses the decomposition of the pressure-sensitive adhesive component and the residual component due to heat and light, and the (composite) tungsten oxide and the pressure-sensitive adhesive layer. The contact area with the adhesive is reduced, the degradation of the (composite) tungsten oxide due to the decomposition product of the adhesive component and the residue component is suppressed, and the fine particles adsorb the decomposition product of the adhesive component and the residue component. Conceivable.

  If the adhesive layer 12 does not reduce the effect of impairing the stability of the (composite) tungsten oxide, the near-infrared shielding agent other than the (composite) tungsten oxide, a neon cut dye, and a color tone adjusting agent. Further, it may contain a transmittance adjusting agent and the like.

  Further, as shown in FIG. 1, the adhesive layer 12 is generally formed on the surface of a transparent substrate such as a transparent plastic film 11 and bonded to a display panel body such as a PDP, a glass substrate, and another plastic film. Used for However, the optical filter for display of the present invention only needs to have the pressure-sensitive adhesive layer 12 containing (composite) tungsten oxide and the like, and the transparent plastic film 11 may be omitted. For example, release sheets may be provided on both sides of the pressure-sensitive adhesive layer 12 and used as an independent optical filter for display in the form of a pressure-sensitive adhesive sheet.

  Usually, as will be described later, other functional layers having various functions are combined and used as an optical filter for display according to the application.

[Fine particles]
In the present invention, the fine particles 19 may have an average particle diameter of 0.1 to 20 μm as described above. If the average particle diameter is fine, the deterioration suppressing effect of the (composite) tungsten oxide is exhibited, and an increase in haze of the optical filter for display is suppressed. When the average particle size of the fine particles is larger than 20 μm, the haze of the display optical filter 20 may increase due to light scattering. The average particle size of the fine particles 19 is preferably 0.1 to 10 μm, and more preferably 0.5 to 5 μm.

  The fine particles are not particularly limited, and organic or inorganic fine particles can be used as appropriate. Organic fine particles include crosslinked or non-crosslinked acrylic resins (polymethyl methacrylate (PMMA), etc.), styrene resins, (meth) acrylate-styrene copolymers, melamine resins (melamine-formaldehyde condensates (usually) And fine particles such as polycarbonate resin and urethane resin. Examples of the inorganic fine particles include fine particles of silica, alumina, aluminosilicate, kaolinite, calcium carbonate, barium sulfate, glass and the like. These fine particles may have either hydrophobic or hydrophilic surface characteristics, and may be used alone or in combination.

  These fine particles are preferably not reactive with (composite) tungsten oxide so as not to promote deterioration of (composite) tungsten oxide or increase haze.

  In the present invention, since the fine particles do not increase haze more, transparent fine particles are preferable, and transparent resin fine particles or silica fine particles are preferable. Further, the refractive index of the fine particles is preferably close to the refractive index of the pressure-sensitive adhesive (for example, the refractive index difference is about ± 0.1).

  In the case of transparent resin fine particles, those made of a resin having a crosslinked structure are preferable so as not to dissolve in the composition of the pressure-sensitive adhesive layer. That is, fine particles such as a crosslinked acrylic resin, a crosslinked styrene resin, a crosslinked (meth) acrylate-styrene copolymer, and a melamine resin are preferable.

  Examples of the silica fine particles include silica fine particles such as amorphous fumed silica, hydrophobic fumed silica, hydrophilic fumed silica, hydrophobic wet method silica, and hydrophilic wet method silica.

  Although there is no restriction | limiting in particular in the content rate of the microparticles | fine-particles 19, 0.1-20 mass% is preferable on the basis of the non volatile matter of the adhesive layer 12. FIG. Thereby, deterioration of the (composite) tungsten oxide can be further suppressed. When the content of the fine particles 19 is less than 0.1% by mass, the effect may not be obtained. When the content is more than 20% by mass, the adhesiveness of the pressure-sensitive adhesive layer 12 may decrease. The content of the fine particles 19 is more preferably 1 to 10% by mass, and particularly preferably 1 to 5% by mass based on the nonvolatile content of the pressure-sensitive adhesive layer 12.

[Near-infrared shielding agent]
In the present invention, (composite) tungsten oxide is used as a near-infrared shielding agent. The (composite) tungsten oxide is useful in that it has high weather resistance, hardly blocks visible light, and is excellent in the function of blocking near infrared rays (particularly, near infrared rays in the vicinity of 50 to 1150 nm).

  The tungsten oxide is an oxide represented by the general formula WyOz (W is tungsten, O is oxygen, 2.2 ≦ z / y ≦ 2.999), and the composite tungsten oxide is the tungsten oxide. The element M (where M is H, He, alkali metal, alkaline earth metal, rare earth element, Cs, Mg, Zr, Cr, Mn, Fe, Ru, Co, Rh, Ir, Ni, Pd, Pt, Cu, Ag, Au, Zn, Cd, Al, Ga, In, Tl, Si, Ge, Sn, Pb, Sb, B, F, P, S, Se, Br, Te, Ti, Nb, V, Those having a composition added with one or more elements selected from Mo, Ta, Re, Be, Hf, Os, Bi, and I) are preferable. As a result, free electrons are generated in WyOz, including the case of z / y = 3.0, and free electron-derived absorption characteristics are expressed in the near infrared region, which is effective as a near infrared absorbing material near 1000 nm. . In the present invention, composite tungsten oxide is preferable.

In the tungsten oxide fine particles represented by the general formula WyOz (W is tungsten, O is oxygen, 2.2 ≦ z / y ≦ 2.999), the preferable composition range of tungsten and oxygen is When the composition ratio of oxygen is less than 3 and the infrared shielding material is described as WyOz, 2.2 ≦ z / y ≦ 2.999. If the value of z / y is 2.2 or more, it is possible to avoid the appearance of a WO ₂ crystal phase other than the objective in the infrared shielding material, and to obtain chemical stability as a material. Therefore, it can be applied as an effective infrared shielding material. On the other hand, if the value of z / y is 2.999 or less, a required amount of free electrons is generated and an efficient infrared shielding material can be obtained.

  From the viewpoint of stability, the composite tungsten oxide fine particles are generally MxWyOz (where M is H, He, alkali metal, alkaline earth metal, rare earth element, Cs, Mg, Zr, Cr, Mn, Fe, Ru, Co, Rh, Ir, Ni, Pd, Pt, Cu, Ag, Au, Zn, Cd, Al, Ga, In, Tl, Si, Ge, Sn, Pb, Sb, B, F, P, S, One or more elements selected from Se, Br, Te, Ti, Nb, V, Mo, Ta, Re, Be, Hf, Os, Bi, I, W is tungsten, O is oxygen, (0.001 ≦ x / y ≦ 1, 2.2 ≦ z / y ≦ 3) The alkali metal is a group 1 element of the periodic table excluding hydrogen, and the alkaline earth metal is a periodic table. Group 2 elements and rare earth elements are Sc, Y and lanthanoid elements That.

  In particular, from the viewpoint of improving optical characteristics and weather resistance as an infrared shielding material, the M element is one or more of Cs, Rb, K, Tl, In, Ba, Li, Ca, Sr, Fe, and Sn. Some are preferred. The composite tungsten oxide is preferably treated with a silane coupling agent. Excellent dispersibility is obtained, and an excellent infrared cut function and transparency are obtained.

  If the value of x / y indicating the added amount of the element M is larger than 0.001, a sufficient amount of free electrons is generated, and a sufficient infrared shielding effect can be obtained. As the amount of the element M added increases, the supply amount of free electrons increases and the infrared shielding effect also increases, but the value of x / y is saturated at about 1. Moreover, if the value of x / y is smaller than 1, it is preferable because an impurity phase can be prevented from being generated in the fine particle-containing layer.

  Regarding the value of z / y indicating the control of the amount of oxygen, in the composite tungsten oxide represented by MxWyOz, the same mechanism as that of the infrared shielding material represented by WyOz described above works, and z / y = Even in 3.0, since there is a supply of free electrons due to the addition amount of the element M described above, 2.2 ≦ z / y ≦ 3.0 is preferable, and 2.45 ≦ z / y ≦ 3.0 is more preferable. It is.

  Further, when the composite tungsten oxide fine particles have a hexagonal crystal structure, the transmission of the fine particles in the visible light region is improved and the absorption in the near infrared region is improved.

When the cation of the element M is added to the hexagonal void, the transmission in the visible light region is improved and the absorption in the near infrared region is improved. Here, generally, when the element M having a large ionic radius is added, the hexagonal crystal is formed. Specifically, Cs, K, Rb, Tl, In, Ba, Sn, Li, Ca, Sr, When Fe is added, hexagonal crystals are easily formed. Of course, other elements may be added as long as the additive element M is present in the hexagonal void formed by the WO ₆ unit, and is not limited to the above elements.

  When the composite tungsten oxide fine particles having a hexagonal crystal structure have a uniform crystal structure, the addition amount of the additive element M is preferably 0.2 or more and 0.5 or less in terms of x / y, more preferably 0. .33. When the value of x / y is 0.33, it is considered that the additive element M is arranged in all of the hexagonal voids.

  Besides hexagonal crystals, tetragonal and cubic tungsten bronzes also have an infrared shielding effect. These crystal structures tend to change the absorption position in the near infrared region, and the absorption position tends to move to the longer wavelength side in the order of cubic <tetragonal <hexagonal. Further, the accompanying absorption in the visible light region is small in the order of hexagonal crystal <tetragonal crystal <cubic crystal. For this reason, it is preferable to use hexagonal tungsten bronze for applications that transmit light in the visible light region and shield light in the infrared region.

  The particle diameter of the composite tungsten oxide fine particles used in the present invention preferably has a particle diameter (average particle diameter) of 800 nm or less from the viewpoint of maintaining transparency. This is because particles smaller than 800 nm do not completely block light due to scattering, can maintain visibility in the visible light region, and at the same time can efficiently maintain transparency. In particular, when importance is attached to transparency in the visible light region, it is preferable to further consider scattering by particles. When importance is attached to the reduction of scattering by the particles, the particle size is 400 nm or less, preferably 200 nm or less.

  Moreover, it is preferable from the viewpoint of improving weather resistance that the surface of the composite tungsten oxide fine particles of the present invention is coated with an oxide containing one or more of Si, Ti, Zr, and Al.

The composite tungsten oxide fine particles of the present invention are produced, for example, as follows.
The tungsten oxide fine particles represented by the general formula WyOz and / or the composite tungsten oxide fine particles represented by MxWyOz are obtained by heat-treating a tungsten compound starting material in an inert gas atmosphere or a reducing gas atmosphere. Can do.

  The tungsten compound starting material is obtained by dissolving tungsten trioxide powder, tungsten oxide hydrate, tungsten hexachloride powder, ammonium tungstate powder, or tungsten hexachloride in alcohol and then drying. Tungsten oxide hydrate powder, or tungsten oxide hydrate powder obtained by dissolving tungsten hexachloride in alcohol and then adding water to precipitate and drying it, or ammonium tungstate It is preferable that it is at least one selected from a tungsten compound powder obtained by drying an aqueous solution and a metal tungsten powder.

  Here, when producing tungsten oxide fine particles, it is preferable to use tungsten oxide hydrate powder or tungsten compound powder obtained by drying an ammonium tungstate aqueous solution from the viewpoint of the ease of the production process. More preferably, when producing the composite tungsten oxide fine particles, an ammonium tungstate aqueous solution or a tungsten hexachloride solution is further used from the viewpoint that each element can be easily and uniformly mixed when the starting material is a solution. preferable. These raw materials are used and heat-treated in an inert gas atmosphere or a reducing gas atmosphere to obtain tungsten oxide fine particles and / or composite tungsten oxide fine particles having the above-mentioned particle diameter.

  The composite tungsten oxide fine particles represented by the general formula MxWyOz containing the element M are the same as the tungsten compound starting material of the tungsten oxide fine particles represented by the general formula WyOz described above. A tungsten compound contained in the form of a simple substance or a compound is used as a starting material. Here, in order to produce a starting material in which each component is uniformly mixed at the molecular level, it is preferable to mix each material with a solution, and the tungsten compound starting material containing the element M is dissolved in a solvent such as water or an organic solvent. Preferably it is possible. Examples thereof include tungstate, chloride, nitrate, sulfate, oxalate, oxide, and the like containing element M, but are not limited to these and are preferably in the form of a solution.

Here, the heat treatment condition in the inert atmosphere is preferably 650 ° C. or higher. The starting material heat-treated at 650 ° C. or higher has sufficient coloring power and is efficient as near infrared shielding fine particles. An inert gas such as Ar or N ₂ is preferably used as the inert gas. Moreover, as heat treatment conditions in a reducing atmosphere, first, the starting material is heat-treated at 100 to 650 ° C. in a reducing gas atmosphere, and then heat-treated at a temperature of 650 to 1200 ° C. in an inert gas atmosphere. . The reducing gas at this time is not particularly limited, but H ₂ is preferable. When H ₂ is used as the reducing gas, the volume ratio of H ₂ is preferably 0.1% or more, more preferably 2% or more, as the composition of the reducing atmosphere. If it is 0.1% or more, the reduction can proceed efficiently.

The raw material powder reduced with hydrogen contains a magnetic phase and exhibits good near-infrared shielding properties, and can be used as near-infrared shielding particles in this state. However, since hydrogen contained in tungsten oxide is unstable, application may be limited in terms of weather resistance. Therefore, a more stable near-infrared shielding fine particle can be obtained by heat-treating the tungsten oxide compound containing hydrogen at 650 ° C. or higher in an inert atmosphere. The atmosphere during the heat treatment at 650 ° C. or higher is not particularly limited, but N ₂ and Ar are preferable from an industrial viewpoint. By the heat treatment at 650 ° C. or more, a Magneli phase is obtained in the near-infrared shielding fine particles, and the weather resistance is improved.

  The composite tungsten oxide fine particles of the present invention are preferably surface-treated with a coupling agent such as a silane coupling agent, a titanate coupling agent, or an aluminum coupling agent. Silane coupling agents are preferred. Thereby, affinity with binders, such as an intermediate | middle layer, a hard-coat layer, and a heat ray cut layer, becomes favorable, and various physical properties improve other than transparency and heat ray cut property.

  Examples of silane coupling agents include γ-chloropropylmethoxysilane, vinylethoxysilane, vinyltris (β-methoxyethoxy) silane, γ-methacryloxypropyltrimethoxysilane, vinyltriacetoxysilane, γ-glycidoxypropyltrimethoxy. Silane, γ-glycidoxypropyltriethoxysilane, β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, vinyltrichlorosilane, γ-mercaptopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, N-β -(Aminoethyl) -γ-aminopropyltrimethoxysilane and trimethoxyacrylsilane can be mentioned. Vinyltris (β-methoxyethoxy) silane, γ-methacryloxypropyltrimethoxysilane, vinyltriacetoxysilane, and trimethoxyacrylsilane are preferred. These silane coupling agents may be used alone or in combination of two or more. Moreover, it is preferable to use 5-20 mass parts of content of the said compound with respect to 100 mass parts of composite tungsten oxide microparticles | fine-particles.

[Adhesive]
In the present invention, the adhesive may be any resin as long as it is an adhesive resin. For example, acrylic resin, polyester resin, urethane resin, epoxy resin, phenol resin, silicone resin, polyvinyl butyral (PVB) resin, ethylene-vinyl acetate copolymer, ethylene-methyl acrylate copolymer, partially saponified ethylene-vinyl acetate Ethylene copolymers such as copolymers, carboxylated ethylene-vinyl acetate copolymers, ethylene- (meth) acryl-maleic anhydride copolymers, ethylene-vinyl acetate- (meth) acrylate copolymers ( “(Meth) acryl” means “acryl or methacryl”), rubber-based adhesives, thermoplastic elastomers such as SEBS and SBS, and the like. In particular, an acrylic resin adhesive is preferable.

  As the constituent component (monomer) of the preferred acrylic resin, the following (meth) acrylic acid alkyl ester, (meth) acrylic acid alkoxyalkyl ester, aromatic ring-containing monomer, hydroxyl group-containing monomer, monomer having a carboxyl group in the molecule, amino Examples thereof include compounds such as group-containing monomers.

  Preferable examples of (meth) acrylic acid alkyl ester; (meth) acrylate having a linear or branched alkyl group having 1 to 12 carbon atoms in the molecule, for example, methyl (meth) acrylate, ethyl (meta ) Acrylate, propyl (meth) acrylate, isopropyl (meth) acrylate, butyl (meth) acrylate, isobutyl (meth) acrylate, pentyl (meth) acrylate, hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, octyl (meth) ) Acrylate, nonyl (meth) acrylate, decyl (meth) acrylate, dodecyl (meth) acrylate, lauryl (meth) acrylate ((meth) acrylate means both acrylate and methacrylate)In particular, ethyl (meth) acrylate, butyl (meth) acrylate, isobutyl (meth) acrylate, and 2-ethylhexyl (meth) acrylate are preferable.

  Particularly preferred examples of the (meth) acrylic acid alkoxyalkyl ester include methoxyethyl (meth) acrylate and ethoxyethyl (meth) acrylate.

  Preferred examples of aromatic ring-containing monomers (copolymerizable compounds containing an aromatic group in the molecular structure) include: phenyl acrylate, phenoxyethyl (meth) acrylate, benzyl (meth) acrylate, phenoxydiethylene glycol (meth) acrylate, ethylene Examples thereof include oxide-modified nonylphenol (meth) acrylate, hydroxyethylated β-naphthol acrylate, biphenyl (meth) acrylate, styrene, vinyltoluene, α-methylstyrene, and the like. In particular, phenyl acrylate, phenoxyethyl (meth) acrylate, benzyl (meth) acrylate, and phenoxydiethylene glycol (meth) acrylate are preferable.

  Examples of hydroxyl-containing monomers include: 2-hydroxyethyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 6-hydroxyhexyl (meth) ) Acrylate, 1,4-cyclohexanedimethanol mono (meth) acrylate, chloro-2-hydroxypropyl acrylate, diethylene glycol mono (meth) acrylate, allyl alcohol and the like. In particular, 2-hydroxyethyl (meth) acrylate and 4-hydroxybutyl (meth) acrylate are preferable.

  Furthermore, preferable examples of the monomer having a carboxyl group in the molecule include (meth) acrylic acid, 2-carboxyethyl (meth) acrylate, 3-carboxypropyl (meth) acrylate, 4-carboxybutyl (meth) acrylate, and itacon. Examples thereof include acid, crotonic acid, maleic acid, fumaric acid and maleic anhydride. In particular, (meth) acrylic acid is preferred.

  Preferred examples of the amino group-containing monomer include aminoethyl (meth) acrylate, dimethylaminoethyl (meth) acrylate, dimethylaminopropyl (meth) acrylate, vinyl pyridine and the like. In particular, dimethylaminoethyl (meth) acrylate is preferable.

  The monomer component is appropriately employed according to the required physical properties.

  In this invention, the compounding quantity of the preferable structural component (monomer) mixture of an acrylic resin is (meth) acrylic-acid alkylester and / or (meth) acrylic-acid alkoxyalkylester: 4.5-89 mass% (especially 22), for example. .7 to 69% by mass), aromatic ring-containing monomer: 10 to 85% by mass (particularly 30 to 70% by mass), hydroxyl group-containing monomer: 1 to 10% by mass (particularly 0.05 to 0.5% by mass), carboxyl Monomers having groups: 0 to 10% by mass (especially 0 to 5% by mass), and amino group-containing monomers 0 to 0.5% by mass (particularly 0 to 0.3% by mass).

  Other monomers may be mixed in the monomer mixture as necessary. Examples of other monomers include epoxy group-containing (meth) acrylates such as glycidyl (meth) acrylate; acetoacetyl group-containing (meth) acrylates such as acetoacetoxyethyl (meth) acrylate; vinyl acetate, vinyl chloride and ( And (meth) acrylonitrile. The mixing ratio of other monomers can be included at a ratio of 0 to 10% by mass.

  The acrylic resin can be produced by a conventionally known polymerization method such as a solution polymerization method, a bulk polymerization method, an emulsion polymerization method and a suspension polymerization method, but does not contain a polymerization stabilizer such as an emulsifier or a suspending agent. What was manufactured by the polymerization method and the block polymerization method is preferable. Moreover, the weight average molecular weight (Mw) by the gel permeation chromatography (GPC) of the said acrylic polymer is 800,000-1,600,000, Preferably it is 800,000-1,500,000. If the Mw is less than 800,000, the cohesive strength of the pressure-sensitive adhesive is not sufficient even when the curing agent is blended in a suitable range, and foaming tends to occur under high temperature conditions, exceeding 1.6 million. And the stress relaxation property of an adhesive tends to fall. It is preferable that ratio (Mw / Mn) of a weight average molecular weight and a number average molecular weight (Mn) is 10-50. Furthermore, it is suitable that it is 20-50. If the ratio (Mw / Mn) becomes too large, the low molecular weight polymer increases and foaming tends to occur. Conversely, if the ratio (Mw / Mn) becomes too small, the stress relaxation property tends to decrease.

  The acrylic resin (adhesive) is preferably used together with a curing agent. Examples of the curing agent include an epoxy compound-based crosslinking agent, an isocyanate compound-based crosslinking agent, a metal chelate compound-based crosslinking agent, an aziridine compound-based crosslinking agent, and an amino resin-based crosslinking agent. Among them, an epoxy compound-based crosslinking agent having two or more epoxy groups in the molecule, an isocyanate compound-based crosslinking agent having two or more isocyanate groups in the molecule, and an aziridine compound-based crosslinking agent are preferable. A crosslinking agent is preferred.

  Examples of the epoxy compound-based crosslinking agent having two or more epoxy groups in the molecule include 1,3-bis (N, N-diglycidylaminomethyl) cyclohexane, N, N, N ′, N′-tetraglycidyl-m— Xylylenediamine, N, N, N ′, N′-tetraglycidylaminophenylmethane, triglycidyl isocyanurate, m-N, N-diglycidylaminophenyl glycidyl ether, N, N-diglycidyl toluidine, N, N -Compounds having two or more epoxy groups such as diglycidyl aniline, pentaerythritol polyglycidyl ether, 1,6-hexanediol diglycidyl ether are preferred.

  Examples of isocyanate compounds include isocyanate monomers such as tolylene diisocyanate, chlorophenylene diisocyanate, hexamethylene diisocyanate, tetramethylene diisocyanate, isophorone diisocyanate, xylylene diisocyanate, diphenylmethane diisocyanate, hydrogenated diphenylmethane diisocyanate, and the like. Isocyanate compounds, isocyanurates, and burette type compounds obtained by adding these isocyanate monomers with trimethylolpropane and the like, and urethane prepolymer type of addition reaction such as polyether polyol, polyester polyol, acrylic polyol, polybutadiene polyol, polyisoprene polyol, etc. An isocyanate etc. can be mentioned.

  Further, examples of the aziridine compound-based crosslinking agent include trimethylolpropane tri-β-aziridinylpropionate, trimethylolpropane tri-β- (2-methylaziridine) propionate, tetramethylolmethane tri-β-aziridinini. Examples include lupropionate and triethylenemelamine.

  It is preferable that the compounding quantity of the said crosslinking agent is 0.0001-2.0 mass parts with respect to 100 mass parts of acrylic resins as a dry mass part (solid content conversion). However, when using an epoxy compound type crosslinking agent, 0.0001-0.1 mass part is preferable, and 0.001-0.05 mass part is especially preferable.

  In the present invention, the pressure-sensitive adhesive composition has a transparency, visibility, and an effect that does not impair the effects of the present invention. You may mix | blend provision resin, a plasticizer, an antifoamer, a wettability preparation agent, etc.

[Optical filter for display]
FIG. 2 is a schematic sectional view showing an example of a preferred embodiment of the optical filter for display according to the present invention. The display optical filter shown in FIG. 2 is particularly preferably used as an optical filter for a PDP in which high-frequency pulse discharge is performed on a light emitting portion for image display.

  As shown in the figure, in the display optical filter 30, a mesh-like conductive layer 23 is formed over the entire surface of the rectangular transparent plastic film 21. A hard coat layer 24 made of an ultraviolet curable resin composition is formed thereon, and a high refractive index layer 25 and a low refractive index layer 26 are further formed thereon as an antireflection layer. The other surface of the transparent plastic film 21 on which the conductive layer 23 is formed contains (composite) tungsten oxide as a near-infrared shielding agent, fine particles 29 having an average particle diameter of 0.1 to 20 μm, and an adhesive. An agent layer 22 is formed. As described above, by providing a near-infrared shielding function to the pressure-sensitive adhesive layer 22, the layer configuration of the optical filter for display can be simplified, and deterioration of the (composite) tungsten oxide due to heat or the like is suppressed. ing.

  The display optical filter 30 has a conductive layer exposed by removing a functional layer such as a hard coat layer around the display optical filter 30 by laser irradiation or the like in order to conduct electricity from the conductive layer 23 to the outside. Or a structure in which a conductive adhesive tape is sandwiched between conductive layers and grounded to the outside (not shown). Moreover, you may provide a peeling sheet on the adhesive layer 22 for handling property improvement.

  In general, the display optical filter 30 is directly attached to the surface of the PDP via the pressure-sensitive adhesive layer 22, or is attached to a glass plate via the pressure-sensitive adhesive layer 22 and disposed on the front surface of the PDP. The optical filter 30 for display which is a preferred embodiment of the present invention contains (composite) tungsten oxide as a near-infrared shielding agent in the adhesive layer 22, but as described above, heat of the (composite) tungsten oxide, etc. It is an optical filter for a display in which deterioration due to is suppressed and weather resistance is high.

  In general, when the optical filter for display is directly attached to the surface of the PDP, the pressure-sensitive adhesive layer is easily affected by heat generated from the PDP. Even if it exists, degradation of the (composite) tungsten oxide contained in the adhesive layer 22 can be suppressed.

  The display optical filter of the present invention may have any configuration as long as it includes the pressure-sensitive adhesive layer 22, and has a configuration other than that shown in FIG. 2, for example, the layers shown above. The position may be changed as appropriate, or one or both of the antireflection layers (the high refractive index layer 25 and the low refractive index layer 26) may be omitted depending on the application. Furthermore, you may provide functional layers, such as a neon cut layer, a color tone adjustment layer, and a transmittance | permeability adjustment layer.

  Any known material may be used for the optical filter for display of the present invention as long as the effects of the present invention are not impaired. An example of the material used below will be described.

[Transparent plastic film]
The material for the transparent plastic film is not particularly limited as long as it is a transparent plastic film (meaning “transparent to visible light”). For example, polyester [eg, polyethylene terephthalate (PET), polybutylene terephthalate], polymethyl methacrylate (PMMA), acrylic resin, polycarbonate (PC), polystyrene, triacetate resin, polyvinyl alcohol, polyvinyl chloride, polyvinylidene chloride, polyethylene, Examples thereof include ethylene-vinyl acetate copolymer, polyvinyl butyral, metal ion crosslinked ethylene-methacrylic acid copolymer, polyurethane, cellophane and the like. Among these, polyethylene terephthalate (PET), polycarbonate (PC), polymethyl methacrylate (PMMA), etc. are highly resistant to loads during processing (heat, solvent, bending, etc.) and particularly highly transparent. preferable. In particular, PET is preferable because it has excellent processability. You may provide the easily bonding layer for improving the adhesiveness of each functional layer on the surface of a transparent base material. The easy-adhesion layer is, for example, a thermosetting resin such as a copolyester resin and a polyurethane resin, or a metal oxide fine particle such as SiO ₂ , ZrO ₂ , TiO ₂ , or Al ₂ O ₃ , preferably an average. What adjusted the refractive index by mix | blending metal oxide fine particles with a particle size of 1-100 nm is used.

  The thickness of the transparent substrate varies depending on the use of the optical filter and the like, but generally 1 μm to 10 mm, 1 μm to 5 mm, particularly 25 to 250 μm is preferable.

[Conductive layer]
The conductive layer is set so that the surface resistance value of the obtained optical filter is generally 10Ω / □ or less, preferably in the range of 0.001 to 5Ω / □, particularly 0.005 to 5Ω / □. It may be a mesh (lattice) metal conductive layer or a layer obtained by a vapor deposition method (a transparent conductive thin film of metal oxide (ITO or the like)). Further, it may be an alternate laminate of a metal oxide dielectric film such as ITO and a metal layer such as Ag (eg, ITO / silver / ITO / silver / ITO laminate).

  The mesh-like metal conductive layer is made of metal fibers and metal-coated organic fibers made of a metal, or a copper foil layer on a transparent substrate is etched into a mesh to provide openings, on a transparent substrate Examples thereof include a conductive ink printed in a mesh shape. Further, dots are formed on the film surface by a material soluble in the solvent, a conductive material layer made of a conductive material insoluble in the solvent is formed on the film surface, and the film surface is brought into contact with the solvent to form dots and A mesh-like metal conductive layer obtained by removing the conductive material layer on the dots may be used. Examples of the metal conductive material include copper, stainless steel, aluminum, nickel, titanium, tungsten, tin, lead, iron, silver, carbon, or alloys thereof, preferably copper, stainless steel, and nickel.

  In order to improve conductivity, a metal plating layer such as copper or copper alloy may be further provided on the mesh-like metal conductive layer. In order to impart antiglare performance, the surface of the conductive layer may be subjected to blackening treatment prevention by oxidation treatment of a metal film, black plating of a chromium alloy or the like, application of black or dark ink, or the like.

[Hard coat layer]
The hard coat layer is a resin composition layer mainly composed of a synthetic resin such as an acrylic resin layer, an epoxy resin layer, a urethane resin layer, or a silicon resin layer. Usually, the thickness of the hard coat layer is 1 to 50 μm from the transparent substrate surface, and preferably 5 to 20 μm in order to obtain high flatness without increasing the layer thickness. Synthetic resins are generally thermosetting resins such as phenol resins, resorcinol resins, urea resins, melamine resins, epoxy resins, acrylic resins, urethane resins, furan resins, silicone resins, or ultraviolet curable resins, as described above. An ultraviolet curable resin is preferable because it can be cured in a short time and is excellent in productivity. When an ultraviolet curable resin is used, it is used as an ultraviolet curable resin composition (consisting of an ultraviolet curable resin, a photopolymerization initiator, etc.).

  Further, the hard coat layer may contain a small amount of an ultraviolet absorber, an infrared absorber, an anti-aging agent, a paint processing aid, a colorant and the like. In particular, it is preferable to contain an ultraviolet absorber (for example, a benzotriazole-based ultraviolet absorber or a benzophenone-based ultraviolet absorber), whereby yellowing of the filter can be efficiently prevented. The amount thereof is generally 0.1 to 10% by mass, preferably 0.1 to 5% by mass, based on the resin composition.

[Antireflection layer]
Among the antireflection layers, the high refractive index layer is doped with ITO, ATO, Sb ₂ O ₃ , SbO ₂ , In ₂ O ₃ , SnO ₂ , ZnO, and Al in a polymer (preferably UV curable resin). A layer (cured layer) in which conductive metal oxide fine particles (inorganic compounds) such as ZnO and TiO ₂ are dispersed is preferably used. The metal oxide fine particles preferably have an average particle size of 10 to 10,000 nm, preferably 10 to 50 nm. In particular, ITO (especially having an average particle diameter of 10 to 50 nm) is preferable. The film thickness is generally in the range of 10 to 500 nm, preferably 20 to 200 nm.

  Among the antireflection layers, the low refractive index layer is composed of fine particles such as silica and fluororesin, preferably 10 to 40% by weight (preferably 10 to 30% by weight) of hollow silica in the polymer (preferably UV curable resin). A layer dispersed in (hardened layer) is preferable. The film thickness is generally in the range of 10 to 500 nm, preferably 20 to 200 nm. As the hollow silica, those having an average particle diameter of 10 to 100 nm, preferably 10 to 50 nm, and a specific gravity of 0.5 to 1.0, preferably 0.8 to 0.9 are preferable.

  When composed of the hard coat layer and the above two layers, for example, the total thickness of the hard coat layer is 5 to 20 μm, the thickness of the high refractive index layer is 50 to 150 nm, and the thickness of the low refractive index layer is 50 to 50 μm. It is preferable that it is 150 nm.

  In order to form each layer, for example, as described above, the above-mentioned fine particles are blended with a polymer (preferably an ultraviolet curable resin) as necessary, and the obtained coating liquid is made into a transparent material such as the rectangular transparent plastic film. The coating may be applied to the surface of the substrate, then dried, and then cured by irradiation with ultraviolet rays. In this case, each layer may be applied and cured one by one, or all the layers may be applied and then cured together. In the case of continuous processing, the coating surface may be damaged unless it is cured after coating of each layer. Therefore, it is preferable to coat and cure each layer one by one.

  As a specific method of coating, a coating solution in which an ultraviolet curable resin containing an acrylic monomer or the like is made into a solution with a solvent such as toluene, n-hexane, or methyl ethyl ketone is coated with a gravure coater, and then dried. Next, a method of curing with ultraviolet rays can be mentioned. This wet coating method has the advantage that the film can be uniformly formed at high speed at low cost. After this coating, for example, by irradiating with ultraviolet rays and curing, effects of improving adhesion and increasing the hardness of the film can be obtained.

  In the case of ultraviolet curing, many light sources that emit light in the ultraviolet to visible range can be used as the light source, such as ultra-high pressure, high pressure, low pressure mercury lamp, chemical lamp, xenon lamp, halogen lamp, mercury lamp, carbon arc lamp, incandescent lamp. And laser light. The irradiation time cannot be determined unconditionally depending on the type of lamp and the intensity of the light source, but is about several seconds to several minutes. Moreover, in order to accelerate curing, the laminate may be preheated to 40 to 120 ° C. and irradiated with ultraviolet rays.

[Peeling sheet]
When a release sheet is provided on the pressure-sensitive adhesive layer, the release sheet is preferably a transparent polymer having a glass transition temperature of 50 ° C. or higher. Examples of such a material include polyethylene terephthalate, polycyclohexylene terephthalate, and polyethylene naphthalate. Polyester resins such as nylon 46, modified nylon 6T, nylon MXD6, polyamide resins such as polyphthalamide, ketone resins such as polyphenylene sulfide and polythioether sulfone, and sulfone resins such as polysulfone and polyether sulfone. Other polymers such as polyether nitrile, polyarylate, polyether imide, polyamide imide, polycarbonate, polymethyl methacrylate, triacetyl cellulose, polystyrene, polyvinyl chloride, etc. It is possible to use a resin as a main component. Of these, polycarbonate, polymethyl methacrylate, polyvinyl chloride, polystyrene, and polyethylene terephthalate can be suitably used. The thickness is preferably 10 to 200 μm, particularly preferably 30 to 100 μm.

  Hereinafter, the present invention will be described with reference to examples.

[Example 1]
1. Formation of pressure-sensitive adhesive layer (1) Preparation of liquid A The following formulation:
Acrylic adhesive (SK Dyne 2094 (Soken Chemical Co., Ltd.), solid content 25%); 1000 parts by mass Epoxy curing agent (E-AX (Soken Chemical Co., Ltd.), solid content 5%); 5 parts by mass Toluene; Liquid A was prepared by mixing and stirring 100 parts by mass.
(2) Preparation of liquid B Next, using another container, the following formulation:
Cross-linked acrylic resin fine particles (average particle size: 2.6 μm) (Riosphere RSP-3009 (manufactured by cross-linked PMMA) (manufactured by Toyo Ink)); 0.25 parts by mass Cesium tungsten oxide (manufactured by Sumitomo Metal Mining); 7 parts by mass Toluene; 100 parts by mass Methyl ethyl ketone; 100 parts by mass Ethyl acetate; 10 parts by mass were mixed and stirred to prepare Liquid B.
(3) Preparation of pressure-sensitive adhesive composition Subsequently, liquid B was added to liquid A and mixed and stirred for 30 minutes to prepare a pressure-sensitive adhesive composition.
(4) Formation of pressure-sensitive adhesive layer The pressure-sensitive adhesive composition was coated on a separator film (film binder 75E-0010 No. 23 (manufactured by Fujimori Kogyo Co., Ltd.)) using an applicator having a gap of 300 μm, and then in an oven. Drying and heat curing were performed at 100 ° C. for 3 minutes to form an adhesive layer. The thickness of the pressure-sensitive adhesive layer was 23 μm.

2. Production of Optical Filter Sample The pressure-sensitive adhesive layer formed on the separator film was bonded to a PET film (Diafoil T680E100-W07 (Mitsubishi Resin Co., Ltd.) thickness: 100 μm) using a hand roller. Next, the separator film was removed from the pressure-sensitive adhesive layer, and a PET film (same as above) was bonded onto the exposed pressure-sensitive adhesive layer using a hand roller. This PET / adhesive layer / PET laminate was cured in an oven at 40 ° C. for 3 days to prepare an optical filter sample.

[Example 2]
An optical filter sample was produced in the same manner as in Example 1 except that the amount of the crosslinked acrylic resin fine particles in Example 1 (2) was 5.0 parts by mass.

[Example 3]
An optical filter sample was produced in the same manner as in Example 1 except that the amount of the crosslinked acrylic resin fine particles in Example 1 (2) was 62.5 parts by mass.

[Example 4]
Except that the crosslinked acrylic resin fine particles of Example 1 (2) were changed to crosslinked acrylic resin fine particles (average particle size; 20 μm) (Techpolymer SSX-120 (produced by crosslinked PMMA) (produced by Sekisui Plastics Co., Ltd.)). An optical filter sample was prepared in the same manner as in Example 1.

[Example 5]
An optical filter sample was produced in the same manner as in Example 4 except that the amount of the crosslinked acrylic resin fine particles in Example 4 was 5.0 parts by mass.

[Example 6]
An optical filter sample was produced in the same manner as in Example 4 except that the amount of the crosslinked acrylic resin fine particles in Example 4 was 62.5 parts by mass.

[Example 7]
The crosslinked acrylic resin fine particles of Example 1 (2) were converted into melamine resin fine particles (average particle size: 0.1 to 0.3 μm) (Eposter (registered trademark) S (manufactured by melamine-formaldehyde condensate) (manufactured by Nippon Shokubai Co., Ltd.). An optical filter sample was produced in the same manner as in Example 1 except that.

[Example 8]
An optical filter sample was produced in the same manner as in Example 7 except that the blending amount of the melamine resin fine particles in Example 7 was 5.0 parts by mass.

[Example 9]
An optical filter sample was produced in the same manner as in Example 7 except that the blending amount of the melamine resin fine particles in Example 7 was 62.5 parts by mass.

[Example 10]
Except that the crosslinked acrylic resin fine particles of Example 1 (2) were silica fine particles (average particle size; 0.08 to 0.14 μm) (made of amorphous silica) (Seahoster KE-P10 (made by Nippon Shokubai Co., Ltd.)) An optical filter sample was produced in the same manner as in Example 1.

[Example 11]
An optical filter sample was prepared in the same manner as in Example 10 except that the amount of silica fine particles in Example 10 was 5.0 parts by mass.

[Example 12]
An optical filter sample was produced in the same manner as in Example 10 except that the amount of silica fine particles in Example 10 was 62.5 parts by mass.

[Comparative Example 1]
An optical filter sample was produced in the same manner as in Example 1 except that the crosslinked acrylic resin fine particles of Example 1 (2) were not blended.

[Evaluation methods]
(1) Transmittance In order to evaluate the deterioration of the composite tungsten oxide, a storage test (temperature 80 ° C., temperature 60 ° C., humidity 90%) was performed, and the transmittance at a wavelength of 850 nm after the initial and storage tests was measured.
The measurement was performed based on JIS-R-3106 using a spectrophotometer U-4100 (manufactured by Hitachi High-Tech).

[Evaluation results]
Table 1 shows the evaluation results of Examples 1 to 12 and Comparative Example 1.

  As shown in Table 1, Examples 1 to 12 in which fine particles having an average particle diameter of 0.1 to 20 μm were blended showed a change in transmittance after a storage test as compared with Comparative Example 1 in which fine particles were not blended. It was small. Therefore, it was shown that deterioration of the (composite) tungsten oxide blended in the pressure-sensitive adhesive layer according to the present invention is suppressed.

  In addition, this invention is not limited to the structure and Example of said embodiment, A various deformation | transformation is possible within the range of the summary of invention.

  According to the present invention, it is possible to provide an optical filter for a display having a sufficient near-infrared shielding effect, a simplified configuration, low cost, and high weather resistance, which is effective for a PDP or the like.

11, 21 Transparent base material 12, 22 Adhesive layer 19, 29 Fine particles 20, 30 Optical filter for display 23 Conductive layer 24 Hard coat layer 25 High refractive index layer 26 Low refractive index layer

Claims (7)

  An optical filter for display comprising a pressure-sensitive adhesive layer containing tungsten oxide and / or composite tungsten oxide, fine particles having an average particle diameter of 0.1 to 20 μm, and a pressure-sensitive adhesive as a near-infrared shielding agent.   The optical filter for display according to claim 1, wherein the fine particles are transparent resin fine particles or silica fine particles.   The transparent resin fine particles are at least one kind of fine particles selected from the group consisting of cross-linked acrylic resin fine particles, cross-linked styrene resin fine particles, cross-linked (meth) acrylate-styrene copolymer fine particles, and melamine resin fine particles. The optical filter for display as described.   The optical filter for display according to any one of claims 1 to 3, wherein the content of the fine particles is 0.1 to 20% by mass based on the nonvolatile content of the pressure-sensitive adhesive layer. The tungsten oxide is represented by the general formula WyOz (W is tungsten, O is oxygen, and 2.2 ≦ z / y ≦ 2.999), and the composite tungsten oxide is Formula MxWyOz (where M is H, He, alkali metal, alkaline earth metal, rare earth element, Cs, Mg, Zr, Cr, Mn, Fe, Ru, Co, Rh, Ir, Ni, Pd, Pt, Cu , Ag, Au, Zn, Cd, Al, Ga, In, Tl, Si, Ge, Sn, Pb, Sb, B, F, P, S, Se, Br, Te, Ti, Nb, V, Mo, Ta , Re, Be, Hf, Os, Bi, I, one or more elements, W represents tungsten, O represents oxygen, and 0.001 ≦ x / y ≦ 1, 2.2 ≦ z / Any one of Claims 1-4 represented by y <= 3). Optical filter for display according to.   The optical filter for display according to any one of claims 1 to 5, wherein the pressure-sensitive adhesive is an acrylic resin-based pressure-sensitive adhesive.   It is an object for plasma display panels, The optical filter for displays of any one of Claims 1-6.

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