JP4882199B2 - Near infrared absorption filter - Google Patents

Description

  The present invention relates to a near-infrared absorption filter suitable for plasma display applications.

  Near-infrared absorption filters having near-infrared absorption ability have the property of blocking near-infrared light and allowing visible light to pass through, and are used in various applications.

  In recent years, a plasma display that has attracted attention as a thin large-screen display has a problem that an electronic device using a near-infrared remote controller malfunctions due to near-infrared rays emitted from the plasma display. Therefore, a near-infrared absorption filter having a near-infrared absorbing film as a constituent element is arranged on the front surface of the plasma display, and the above-described problems are solved by absorbing near-infrared rays emitted from the display. .

  There are many types of filters that have near-infrared absorption ability, but because the processability and productivity are good and the degree of freedom in optical design is relatively large, the dye is dispersed or dissolved in the resin. Many filters have been proposed in which a layer is laminated on a substrate. (For example, patent documents 1-9).

  Some of these near-infrared absorption filters have the ability to sufficiently block the near-infrared rays emitted from plasma displays, but the characteristics required for near-infrared absorption filters with the spread of plasma displays Is also growing.

  For example, the near-infrared absorption filter has an antireflection function on the outermost surface (the outermost surface opposite to the surface bonded to the plasma display) in order to suppress the occurrence of glare due to reflected light when viewed from an arbitrary angle. Providing the layer which has is performed. As this surface layer, a structure in which a hard coat layer, a high refractive index layer, and a low refractive index layer are laminated in this order and the low refractive index layer is the outermost surface side is generally used.

  However, when a near-infrared absorption filter provided with a surface layer having such a configuration is applied to a plasma display, an iris-like color (interference fringes) is generated on the screen, particularly under the light of a fluorescent lamp. In recent fluorescent lamps, a three-wavelength type has become mainstream from the viewpoint of daylight color reproducibility, and such interference fringes are more likely to occur. In recent years, plasma display panels are required to have a larger screen (larger area), and a higher-class interior is also required. In view of this, reduction of the interference fringes is also an important issue.

  The interference fringes include a refractive index of a base material used for a near infrared absorption filter (for example, 1.62 for polyethylene terephthalate) and a refractive index of the hard coat layer adjacent to the base material (for example, an acrylic hard coat layer). 1.49 etc.) is considered to be caused by a large difference. In the plastic film for optical material of Patent Document 10, specific metal oxide ultrafine particles are dispersed in the hard coat layer formed on the base film to reduce the refractive index difference between the base film and the hard coat layer. By doing so, the generation of interference fringes is reduced.

In addition, with respect to problems related to interference fringes, an optical easy-adhesion film (Patent Document 11) in which the interval between interference fringes generated when light is irradiated from a specific light source is 1 mm or more, and a dark color portion due to light from a specific light source A film having a transparent hard coat layer (Patent Document 12) in which interference fringes having a stripe pitch of 5 mm or less between the light-colored portion and the light-colored portion are present only in an area ratio of 1/10 or less in the specific region, and the reflectance from the back surface of the film is 0.00. An optical polyester film (Patent Document 13) that suppresses interference between front surface reflection and back surface reflection at 1% or less has been proposed.
JP 2002-82219 A JP 2002-214427 A JP 2002-264278 A JP 2002-303720 A JP 2002-333517 A JP 2003-82302 A JP 2003-96040 A JP 2003-114323 A WO97 / 38855 specification JP-A-7-151902 JP 2001-71439 A JP 2002-241527 A JP 2002-210908 A

  However, the technologies disclosed in Patent Documents 10 to 13 have room for improvement. In the plastic film for optical material of Patent Document 10, by adding metal oxide ultrafine particles to the hard coat layer, the original functions of the hard coat layer, such as transparency, chemical resistance, scratch resistance, and antifouling property, can be obtained. It tends to decrease. In addition, the high refractive index layer and the low refractive index layer provided on such a hard coat layer are required to be changed in design with a change in the refractive index of the hard coat layer.

  In addition, since the techniques of Patent Documents 11 and 12 require strict control of the thickness of each layer, there is room for improvement in terms of productivity. In addition, the optical polyester film of Patent Document 13 has a back surface. In order to control the reflectance, it is necessary to provide a coat layer having a specific refractive index and a specific thickness on the surface opposite to the hard coat layer forming surface of the polyester film serving as a base material.

  In addition, as described above, many near-infrared absorption filters have been proposed that have various functions such as anti-reflection and interference fringe suppression functions in addition to near-infrared absorption. For example, as disclosed in Patent Document 9, multi-functional filters are made to be multi-functional by bonding films having respective functions. In this case, for example, in a filter having near infrared absorption ability and antireflection ability, a near infrared absorption film in which a near infrared absorption layer is provided on a base film, and an antireflection film in which an antireflection layer is provided on the base film. In general, bonding is performed via an adhesive or the like, and a large number of layers are formed such as a plurality of substrate films, and many interfaces exist inside.

  In this way, when there are many interfaces inside the filter, the optical characteristics are likely to be lowered, such as a reduction in visible light transmittance. Moreover, the problem of the fall of productivity by bonding a several sheet of film and the fall of the sticking work property to a to-be-adhered body (plasma display) by the total thickness of a filter also arises.

  The present invention has been made in view of the above circumstances, and an object thereof is a near-infrared absorption filter composed of a film that realizes a multilayer while enabling thinning, and interference caused by light incident from the outside. An object of the present invention is to provide a near-infrared absorption filter in which the generation of fringes is suppressed.

  The near-infrared absorption filter of the present invention that can achieve the above-mentioned object is obtained by sequentially laminating a surface layer (A) having an antireflection function, a base film (B), and a near-infrared absorption layer (C). The surface layer (A) has a hard coat layer on the base film (B) side, and the base film (B) includes a polyester film and an adhesion modified layer as constituent elements. And the adhesive modification layer contains an aqueous polyester resin and at least one of a water-soluble titanium chelate compound, a water-soluble titanium acylate compound, a water-soluble zirconium chelate compound, or a water-soluble zirconium acylate compound. It is formed from a coating solution, and is located between the surface layer (A) and the polyester film, and the near-infrared absorbing layer (C) has a wavelength of 800 to 10 The near-infrared absorption region of 0nm and has a gist where those comprising a dye having a maximum absorption.

  It is preferable that the adhesive layer (D) which consists of a transparent adhesive is laminated | stacked on the said near-infrared absorption layer (C) side surface.

  The total thickness of the layers (A) to (D) is preferably 0.05 to 0.2 mm, and the pencil hardness of the surface layer (A) is preferably 1H or more.

  It is also a preferred embodiment when at least one of the layers (A) to (D) contains at least one dye having absorption in the visible light region and has a color tone correction function.

  The polyester film is preferably a biaxially oriented polyester film; substantially does not contain particles; and contains an ultraviolet absorber.

  The coating solution for forming the adhesion modified layer is composed of an aqueous polyester resin, a water-soluble titanium chelate compound, a water-soluble titanium acylate compound, a water-soluble zirconium chelate compound, or a water-soluble zirconium acylate compound. The mixing ratio (mass ratio) with at least one kind is preferably 90/10 to 5/95, and the adhesion-modified layer preferably contains particles.

  In the near-infrared absorption filter of the present invention, an embodiment having a translucent sheet (E) having an electromagnetic wave absorption function is also preferable. In this case, the translucent sheet (E) is the near-infrared absorbing layer (C) of the near-infrared absorbing layer (C) opposite to the base film (B) laminated surface or the adhesive layer (D). ) It is recommended to be laminated on the opposite side of the laminated surface.

  The present invention also includes a plasma display panel having the near infrared absorption filter of the present invention.

  In the present invention, “film” and “sheet” are a concept including each other.

  The near-infrared absorption filter of the present invention is composed of a film that realizes multilayering without bonding a plurality of films, and can be easily thinned, and has good near-infrared absorption ability and antireflection ability, Can secure excellent light transmittance in the visible light region. In addition, thinning can improve the workability of attaching to an adherend (plasma display panel), and is excellent in economic efficiency.

  In addition, since interference fringes due to light incident from the outside can be suppressed, the occurrence of glare, iris colors, etc., particularly when the plasma display is turned off, is suppressed, providing excellent quality. Yes.

  Hereinafter, the near-infrared absorbing film of the present invention will be described in detail.

<Base film (B)>
The base film (B) has a polyester film and an adhesion modified layer as essential components.

  Examples of the material for the polyester film include polyethylene terephthalate (PET), polybutylene terephthalate, polyethylene-2,6-naphthalate, or a copolymer composed mainly of these resin components.

  As the copolymerization component when the polyester is a copolymer, aliphatic dicarboxylic acids such as adipic acid and sebacic acid; terephthalic acid, isophthalic acid, phthalic acid, 2,6-naphthalenedicarboxylic acid, etc. And aromatic dicarboxylic acids such as: polyfunctional carboxylic acids such as trimellitic acid and pyromellitic acid. These polyvalent carboxylic acids may be in the form of esters (for example, alkyl esters such as methyl esters and ethyl esters). Examples of the polyhydric alcohol include aliphatic glycols such as diethylene glycol, 1,4-butanediol, propylene glycol, and neopentyl glycol; alicyclic glycols such as 1,4-cyclohexanedimethanol; and an average molecular weight of 150 to 20000. Polyethylene glycol or the like can be used. In addition, it is desirable that the amount of the copolymer component used is less than 20% by mass in all the constituent components. When the amount of the copolymerization component used is too large, film properties such as film strength, transparency and heat resistance tend to be lowered.

  Among the above resins, a PET film is particularly preferable from the viewpoints of mechanical properties, heat resistance, transparency, economy, and the like.

  The intrinsic viscosity of the polyester pellets used for the polyester film is preferably 0.45 to 0.70 dl / g. If the intrinsic viscosity is too small, the mechanical properties of the film tend to deteriorate. On the other hand, if the intrinsic viscosity is too large, the mechanical properties of the film will be excessive, and during the film production, the increase in the filtration pressure of molten resin filtration (described later) in the extrusion process for removing foreign matters will increase. This is not preferable because high-precision filtration tends to be difficult.

  It is preferable that the polyester film which comprises a base film (B) contains an ultraviolet absorber. Since the near-infrared absorbing dye contained in the near-infrared absorbing layer (C) can be deteriorated by ultraviolet rays, it is included in the external light incident from the surface layer (A) side when the near-infrared absorbing filter is used for a long time. It may be deteriorated by ultraviolet rays, causing a change in the characteristics of the near infrared absorption filter.

  On the other hand, if the base film (B) disposed in the position where the external light hits before the near-infrared absorbing layer (C) when applied to a plasma display, an ultraviolet absorber is contained, Since the ultraviolet ray deterioration of the infrared absorbing dye can be prevented, the characteristic change due to the long-term use of the near infrared ray absorbing filter can be suppressed.

  The ultraviolet absorber is not particularly limited as long as it is a compound having ultraviolet absorbing ability and can withstand the heat applied in the production process of the base film (B) (polyester film).

  UV absorbers are broadly classified into organic UV absorbers and inorganic UV absorbers. From the viewpoint of ensuring transparency, it is desirable to use organic UV absorbers (low molecular type and high molecular type). . Although it does not specifically limit as an organic type ultraviolet absorber (low molecular type), For example, a benzotriazole type, a benzophenone type, a cyclic imino ester type, etc., and these combination are mentioned. However, from the viewpoint of durability, benzotriazole type and cyclic imino ester type are particularly preferable. When two or more kinds of ultraviolet absorbers are used in combination, it is possible to adjust so as to absorb ultraviolet rays having different wavelengths at the same time, so that the ultraviolet absorption effect can be further improved.

  Examples of the benzotriazole ultraviolet absorber include 2- [2′-hydroxy-5 ′-(methacryloyloxymethyl) phenyl] -2H-benzotriazole and 2- [2′-hydroxy-5 ′-(methacryloyloxyethyl). ) Phenyl] -2H-benzotriazole, 2- [2'-hydroxy-5 '-(methacryloyloxypropyl) phenyl] -2H-benzotriazole, 2- [2'-hydroxy-5'-(methacryloyloxyhexyl) phenyl ] -2H-benzotriazole, 2- [2'-hydroxy-3'-tert-butyl-5 '-(methacryloyloxyethyl) phenyl] -2H-benzotriazole, 2- [2'-hydroxy-5'-tert -Butyl-3 '-(methacryloyloxyethyl) phenyl] -2 -Benzotriazole, 2- [2'-hydroxy-5 '-(methacryloyloxyethyl) phenyl] -5-chloro-2H-benzotriazole, 2- [2'-hydroxy-5'-(methacryloyloxyethyl) phenyl] -5-methoxy-2H-benzotriazole, 2- [2'-hydroxy-5 '-(methacryloyloxyethyl) phenyl] -5-cyano-2H-benzotriazole, 2- [2'-hydroxy-5'-( And methacryloyloxyethyl) phenyl] -5-tert-butyl-2H-benzotriazole, 2- [2′-hydroxy-5 ′-(methacryloyloxyethyl) phenyl] -5-nitro-2H-benzotriazole, and the like.

  Examples of the cyclic imino ester ultraviolet absorber include 2,2 ′-(1,4-phenylene) bis (4H-3,1-benzoxazinon-4-one), 2-methyl-3,1-benzo. Oxazin-4-one, 2-butyl-3,1-benzoxazin-4-one, 2-phenyl-3,1-benzoxazin-4-one, 2- (1- or 2-naphthyl) -3,1 -Benzoxazin-4-one, 2- (4-biphenyl) -3,1-benzoxazin-4-one, 2-p-nitrophenyl-3,1-benzoxazin-4-one, 2-m-nitro Phenyl-3,1-benzoxazin-4-one, 2-p-benzoylphenyl-3,1-benzoxazin-4-one, 2-p-methoxyphenyl-3,1-benzoxazin-4-one, 2 -O-met Cyphenyl-3,1-benzoxazin-4-one, 2-cyclohexyl-3,1-benzoxazin-4-one, 2-p- (or m-) phthalimidophenyl-3,1-benzoxazin-4-one 2,2 ′-(1,4-phenylene) bis (4H-3,1-benzoxazinon-4-one) 2,2′-bis (3,1-benzoxazin-4-one), 2, 2′-ethylenebis (3,1-benzoxazin-4-one), 2,2′-tetramethylenebis (3,1-benzoxazin-4-one), 2,2′-decamethylenebis (3 1-benzoxazin-4-one), 2,2′-p-phenylenebis (3,1-benzoxazin-4-one), 2,2′-m-phenylenebis (3,1-benzoxazine-4) -On), 2,2 '-( 4,4′-diphenylene) bis (3,1-benzoxazin-4-one), 2,2 ′-(2,6- or 1,5-naphthalene) bis (3,1-benzoxazin-4-one) ), 2,2 ′-(2-methyl-p-phenylene) bis (3,1-benzoxazin-4-one), 2,2 ′-(2-nitro-p-phenylene) bis (3,1- Benzoxazin-4-one), 2,2 ′-(2-chloro-p-phenylene) bis (3,1-benzoxazin-4-one), 2,2 ′-(1,4-cyclohexylene) bis (3,1-benzoxazin-4-one), 1,3,5-tri (3,1-benzoxazin-4-one-2-yl) benzene, 1,3,5-tri (3,1- Benzoxazin-4-one-2-yl) naphthalene, 2,4,6-tri (3,1 Benzoxazin-4-one-2-yl) naphthalene, 2,8-dimethyl-4H, 6H-benzo (1,2-d; 5,4-d ′) bis- (1,3) -oxazine-4, 6-dione, 2,7-dimethyl-4H, 9H-benzo (1,2-d; 5,4-d ′) bis- (1,3) -oxazine-4,9-dione, 2,8-diphenyl -4H, 8H-benzo (1,2-d; 5,4-d ') bis- (1,3) -oxazine-4,6-dione, 2,7-diphenyl-4H, 9H-benzo (1, 2-d; 5,4-d ′) bis- (1,3) -oxazine-4,6-dione, 6,6′-bis (2-methyl-4H, 3,1-benzoxazin-4-one ), 6,6′-bis (2-ethyl-4H, 3,1-benzoxazin-4-one), 6,6′-bis (2-pheny -4H, 3,1-benzoxazin-4-one), 6,6'-methylenebis (2-methyl-4H, 3,1-benzoxazin-4-one), 6,6'-methylenebis (2-phenyl) -4H, 3,1-benzoxazin-4-one), 6,6'-ethylenebis (2-methyl-4H, 3,1-benzoxazin-4-one), 6,6'-ethylenebis (2 -Phenyl-4H, 3,1-benzoxazin-4-one), 6,6'-butylenebis (2-methyl-4H, 3,1-benzoxazin-4-one), 6,6'-butylenebis (2 -Phenyl-4H, 3,1-benzoxazin-4-one), 6,6'-oxybis (2-methyl-4H, 3,1-benzoxazin-4-one), 6,6'-oxybis (2 -Phenyl-4H, 3,1-benzo Oxazin-4-one), 6,6′-sulfonylbis (2-methyl-4H, 3,1-benzoxazin-4-one), 6,6′-sulfonylbis (2-phenyl-4H, 3,1) -Benzoxazin-4-one), 6,6'-carbonylbis (2-methyl-4H, 3,1-benzoxazin-4-one), 6,6'-carbonylbis (2-phenyl-4H, 3 , 1-benzoxazin-4-one), 7,7′-methylenebis (2-methyl-4H, 3,1-benzoxazin-4-one), 7,7′-methylenebis (2-phenyl-4H, 3 , 1-benzoxazin-4-one), 7,7′-bis (2-methyl-4H, 3,1-benzoxazin-4-one), 7,7′-ethylenebis (2-methyl-4H, 3,1-benzoxazin-4-one 7,7′-oxybis (2-methyl-4H, 3,1-benzoxazin-4-one), 7,7′-sulfonylbis (2-methyl-4H, 3,1-benzoxazin-4-one) ), 7,7′-carbonylbis (2-methyl-4H, 3,1-benzoxazin-4-one), 6,7′-bis (2-methyl-4H, 3,1-benzoxazine-4-one) ON), 6,7′-bis (2-phenyl-4H, 3,1-benzoxazin-4-one), 6,7′-methylenebis (2-methyl-4H, 3,1-benzoxazine-4-one) ON), 6,7′-methylenebis (2-phenyl-4H, 3,1-benzoxazin-4-one) and the like.

  Among the ultraviolet absorbers, it is preferable to apply one having a decomposition start temperature equal to or higher than the film forming temperature of the polyester film in terms of suppressing contamination due to the decomposition of the ultraviolet absorber when forming the polyester film. Specifically, it is desirable to use an ultraviolet absorber having a decomposition start temperature of 290 ° C. or higher.

  As described above, the purpose of blending the ultraviolet absorber is to exhibit the action of suppressing the deterioration of the near-infrared absorbing dye contained in the near-infrared absorbing layer (C) by the ultraviolet rays contained in the outside light. is there.

  Specifically, for example, the transmittance at a wavelength of 380 nm or less is preferably 10% or less. The transmittance at a wavelength of 390 nm or less is more preferably 10% or less, and the transmittance at a wavelength of 400 nm or less is particularly preferably 10% or less. The content of the low molecular weight type UV absorber satisfying these characteristics is preferably 0.1 to 4% by mass, more preferably 0.3 to 2% by mass with respect to the constituent resin of the polyester film. preferable. If the amount of the ultraviolet absorber is too small, the ultraviolet absorbing ability is decreased, and if it is too large, the film may be yellowed or the film-forming property of the film may be deteriorated.

  In addition, it is also recommended to use a polymer type UV absorber as it avoids problems caused by bleeding on the filter surface. The polymer type ultraviolet absorber means a polymer having a skeleton useful as an ultraviolet absorber in the side chain. In consideration of compatibility with polyester, polyester ultraviolet absorbers and acrylic polymer ultraviolet absorbers are preferred. For example, polyester has terephthalic acid as a dicarboxylic acid component, ethylene glycol and / or 1,4-butanediol as a diol component as main components, and naphthalenetetracarboxylic acid diimide represented by the general formula (I) as a copolymerization component. A UV-absorbing compound containing naphthalenedicarboxylic acid represented by the general formula (II) ("Novapex U-110" manufactured by Mitsubishi Chemical Corporation) or an acrylic type having a 2- (2-hydroxylphenyl) benzotriazole skeleton in the side chain A polymer ("UVA-1635" manufactured by BASF) is preferable in that it can maintain characteristics such as transparency in addition to the intended ultraviolet absorption characteristics.

  In the above general formula (I), R represents an organic residue (such as an alkylene group), and X represents a hydroxyl group or the like.

  The content of the polymer type ultraviolet absorber is preferably 0.1 to 20% by mass, more preferably 0.5 to 15% by mass with respect to the constituent resin of the polyester film. If the amount of the ultraviolet absorber is too small, the ultraviolet absorbing ability is decreased, and if it is too large, the film may be yellowed or the film-forming property of the film may be deteriorated.

  Although the blending method of the ultraviolet absorber to the polyester film is not limited, it is preferable to blend at the time of polyester polymerization or melt extrusion. In this case, it is a preferred embodiment that a master batch pellet containing an ultraviolet absorber is prepared in advance and added thereby. For example, the following method is illustrated as a preferred embodiment. First, polyester and a UV absorber are blended to prepare a master batch pellet. This master batch pellet is a pellet that does not substantially contain particles for the purpose of imparting slipperiness. The master batch pellets and raw material pellets mixed with virgin polyester pellets are fully vacuum dried, then supplied to an extruder, melt extruded into a film, cooled and solidified on a casting roll to produce an unstretched polyester film. Film.

  At the time of the extrusion, the resin temperature up to the extruder melting part, kneading part, polymer tube, gear pump, filter is 280 to 290 ° C, and the resin temperature up to the polymer tube and flat die is 270 to 280 ° C. For example, when an ultraviolet absorber is blended, it is preferable in terms of preventing sublimation at the die discharge port of the ultraviolet absorber and contamination of the cooling roll.

  In addition, it is desirable to perform high-precision filtration in order to remove foreign substances contained in the polyester at an arbitrary place where the molten polyester is maintained at about 280 ° C. If such foreign matter remains on the base film (B), it will cause optical defects when applied to a plasma display as a near-infrared absorbing filter, and scratches that will cause optical defects when manufacturing a near-infrared absorbing filter. It also becomes a cause of the occurrence of.

  The filter medium used for high-precision filtration of molten polyester is not particularly limited, but if it is a filter medium made of a stainless steel sintered body, aggregates mainly composed of Si, Ti, Sb, Ge, and Cu, and high melting point organic substances It is preferable because of its excellent removal performance. Furthermore, the filter particle size (initial filtration efficiency 95%) of the filter medium is preferably 20 μm or less, and more preferably 15 μm or less. When the filter particle size of the filter medium (initial filtration efficiency 95%) exceeds 20 μm, foreign matters having a size exceeding 20 μm that cause the above-mentioned optical defects and scratches cannot be sufficiently removed. Productivity may be reduced by performing high-precision filtration of molten resin using a filter medium having a filter particle size (initial filtration efficiency of 95%) of 20 μm or less, but there are few protrusions due to coarse particles, and near infrared rays. It is recommended to obtain a film that can suppress the generation of scratches when manufacturing an absorption filter.

  As described above, if the foreign material that remains in the raw material polyester remains, or if an ultraviolet absorber that bleeds out from the molten polyester during film formation and contaminates the die discharge port, etc., adheres to the film, In the stretching process at the time of film formation, the orientation of the polyester molecules is disturbed around the foreign matter and the ultraviolet absorber (hereinafter collectively referred to as “foreign matter”), and optical distortion occurs. Because of this optical distortion, it is recognized as a defect that is considerably larger than the size of the actual foreign matter, and the quality may be significantly impaired. For example, a foreign matter having a size of 20 μm may be optically recognized as a size of 50 μm or more, and may be recognized as an optical defect having a size of 100 μm or more.

  In order to obtain a highly transparent film, a polyester film (for example, a biaxially oriented polyester film) does not substantially contain particles for imparting slipperiness, or is contained in a small amount so that the transparency is not hindered. It is desirable that More preferably, it is the structure which does not contain particle | grains substantially. The phrase “substantially does not contain particles” is intended to exclude a state in which particles are inevitably mixed in a polyester film manufacturing process or the like. For example, in the case of inorganic particles, it means a content that is below the detection limit when inorganic elements are quantified by fluorescent X-ray analysis.

  In addition, as the particle content is low and the transparency of the film is high, optical defects due to minute foreign matters tend to become clearer. Further, as the film becomes thicker, the content of foreign matters per unit area of the film in a plan view tends to be larger than that of a thin film, and this problem is further increased. Therefore, it is preferable to remove foreign matters in the polyester as much as possible, and it is recommended to adopt the various methods described above.

  The obtained unstretched film is stretched 2.5 to 5.0 times in the longitudinal direction (longitudinal direction: traveling direction during production of the laminated film) with a roll heated to 80 to 120 ° C. to obtain a uniaxially oriented film. Subsequently, the end of the film is gripped with a clip and guided to a hot air zone heated to 120 to 150 ° C., stretched 2.5 to 5.0 times in the width direction, and heat treated at 200 to 250 ° C. In the heat treatment step, a relaxation treatment of about 3% in the width direction is performed as necessary to obtain a biaxially oriented film.

  When the base film (B) according to the present invention is composed of a polyester film, the polyester film may include an unstretched polyester film, a uniaxially oriented polyester film, and a biaxially oriented polyester film. Biaxially oriented polyester film is recommended in terms of enhancing the mechanical properties and the like.

The polyester film obtained by the above method preferably has 100 / m ² or less scratches having a depth of 1 μm or more and a length of 3 mm or more present on the surface. The number of scratches is more preferably 30 pieces / m ² or less, and particularly preferably 10 pieces / m ² or less. If the number of scratches is within such a range, problems due to optical defects do not occur.

  As a technique for preventing the occurrence of scratches on the film, (a) the film surface itself or the roll surface, in particular, the roll surface in contact with the film should not cause “defects” that cause scratches; Examples include preventing the film from shifting in the vertical and horizontal directions on the surface. The above-mentioned “defects” refer to all factors that cause fine scratches on the film by coming into contact with the film, such as scratches, deposits, deposits, and foreign matters formed on the roll surface. Therefore, by eliminating these defects, it is possible to reduce the occurrence of scratches on the film surface. In order to prevent the occurrence of the above defects, for example, the following methods can be employed.

  Preheating of the longitudinal stretching process in order to prevent the surface roughness of the roll used at the time of film production from 0.1 μm or less in Ra and to prevent the generation of scratches such as deposits, deposits and foreign matters on the roll surface. There is a method of installing a roll cleaner on the inlet roll and the cooling roll.

  In addition, there is a method in which the degree of cleanliness in the film production process is set to class 1000 or less (1000 particles or less of 0.5 μm or more in a volume per cubic foot). It is preferable to use clean air of class 100 or less for the air cooling device for cooling the anti-roll surface.

  Furthermore, there is a method of cleaning the roll by an operation of scraping off defects on the roll using an abrasive before the film production. In addition, in order to prevent the film from adsorbing dust or the like due to the generation of static electricity and causing a defect, there is a method of providing a static eliminator so that the charge amount of the film becomes ± 1500 V or less in all steps. The process from the casting of the polyester film to the tenter described later is a process in which scratches are likely to occur, and it is possible to contribute to the suppression of the occurrence of defects by laying out this section in a compact manner and setting the passage time to 5 minutes or less.

  About a roll, it can be set as the structure where the fault of a roll surface does not contact a film directly by forming a water film on the roll surface, or setting it as an air floating type roll. Moreover, the adhesion of the defect to a roll surface can be reduced and the defect of a roll surface can be reduced because the oligomer amount which precipitates from a film shall be 1000 ppm or less.

  Further, in the winding process after stretching, the surface on the end side in the width direction of the film is pressed with a roller with a protrusion to form an uneven portion on that portion, and the film on which the uneven portion is formed is wound. The take-up mechanism is configured to be wound in a roll shape, and the protrusion on the roller with the protrusion is formed in a tapered shape, the top of the protrusion is rounded, and the curvature radius of the top surface is 0.4 mm or less. By setting, it is possible to prevent the film and the defect from coming into contact with each other in the film winding device.

  It is also effective as a method for preventing scratches to prevent the film from shifting on the roll surface. For example, the following methods can be employed. For example, by reducing the roll diameter, using a suction roll, electrostatic contact, and using a part nip contact device, etc., it is possible to suppress the occurrence of long scratches by increasing the adhesion of the film to the roll. it can. In particular, reducing the diameter of the roll also subdivides the amount of shift of the film and can contribute to the prevention of long scratches. In addition, many of the scratches increase in length and frequency toward the end in the roll width direction, and it is difficult to obtain a scratch-free portion at the end in the roll width direction. By trimming around the center of the direction, a film with few scratches can be obtained.

  In addition, as a cause of occurrence of longitudinal scratches or lateral scratches, deformations such as expansion and contraction in the longitudinal direction or the lateral direction of the film can be mentioned, respectively. These film deformations are mainly caused by temperature changes in the film. Therefore, for example, by suppressing the temperature change of the film on the roll surface, the amount of film deformation due to such temperature can be reduced, and the occurrence of vertical scratches and horizontal scratches can be prevented. Specifically, the temperature change of the film per roll is 40 ° C. or less, preferably 30 ° C. or less, more preferably 20 ° C. or less, still more preferably 10 ° C. or less, and particularly preferably 5 ° C. or less. Is recommended. Examples of the method for suppressing the temperature change of the film on the roll surface include air cooling between rolls and water cooling through a water tank. Furthermore, the temperature change of the film on the roll surface per roll can be reduced by increasing the number of rolls. Preferably, the number of rolls in the longitudinal stretching step is 10 or more.

  Further, by setting the relationship between the relative speeds of the plurality of rolls to a speed profile that is closest to the amount of deformation due to the temperature and tension of the film, it is possible to reduce the vertical shift of the film. Furthermore, in the coating step of the coating solution for forming an adhesion modified layer, which will be described later, the drying condition is completed at the beginning of the dryer section, and the film is cooled to the outlet so that the film temperature at the dryer outlet is 40 ° C. or lower. Moreover, the shift of the film due to temperature change can be reduced.

  In addition, if the tension during running of the film is too low, the gripping force is lowered and deviation occurs, and if it is too high, the stress deformation becomes large and deviation occurs, so that the optimum tension range is 4.9 to 29.4 MPa. It is preferable to adjust by the driving roll speed and tension adjusting means. Moreover, the shift | offset | difference of the film on a roll surface can be suppressed by making the friction coefficient between the film and roll in the use temperature at the time of manufacture 0.2 or more.

  Furthermore, it is preferable to use a special bearing for the free roll and to set the rotational resistance to 19.6 N or less. For the drive roll, it is preferable to control the rotation spots to 0.01% or less.

  The sequential biaxial stretching method has been described above, but the stretching method may be a simultaneous biaxial stretching method. Further, it may be a multistage stretching method. Further, when the film is a uniaxially oriented film, only the uniaxial direction needs to be stretched.

  The thickness of the polyester film (preferably biaxially oriented polyester film) constituting the base film (B) is not particularly limited and can be arbitrarily set, but is preferably 0.038 mm or more and 0.188 mm or less. If the thickness is too small, the handleability of the near-infrared absorbing filter is deteriorated, which is not preferable. On the other hand, if the thickness is too large, the handleability of the near-infrared absorption filter and the workability when sticking to an adherend such as a plasma display deteriorate, which is not preferable. In addition, it will not be able to meet the market demand for thin film. The polyester film may have a single layer structure or a multilayer structure (for example, two layers, three layers, four layers, etc.).

  The near-infrared absorption filter of this invention has the structure by which a functional layer is laminated | stacked on both surfaces of a base film (B). Therefore, it is preferable that the surface of the base film (B) is subjected to easy adhesion treatment. That is, the base film (B) according to the present invention has an adhesion modified layer on at least one surface of the polyester film.

  The surface layer (A) provided on one side of the base film (B) has a structure in which a low refractive index layer, a high refractive index layer, and a hard coat layer are laminated in this order from the outermost surface side as will be described later. It is what you have. Since the hard coat layer is obtained by curing a specific curable resin, the difference in refractive index from the base film (B) (polyester film) is large. In a near-infrared absorption filter provided with such an antireflection functional layer, when applied to a plasma display, iris-like colors (interference fringes) appear due to light interference at the layer interface inside the filter. As a method for suppressing the occurrence of the interference fringes, it is preferable to reduce the refractive index difference between the hard coat layer and the base film, and for this purpose, the refractive index of the hard coat layer and the base film are between these layers. It is known that it is effective to introduce a layer having a refractive index intermediate between these refractive indexes.

  The present inventors have repeatedly studied the method of introducing the intermediate refractive index layer, and as the intermediate layer, an aqueous polyester resin, a water-soluble titanium chelate compound, a water-soluble titanium acylate compound, a water-soluble zirconium chelate compound Or a coating layer formed from a coating solution containing at least one water-soluble zirconium acylate compound, is extremely effective in suppressing the occurrence of the interference fringes, and the base film (B) It has been found that it can also contribute to an improvement in adhesion to the surface layer (A) (hard coat layer).

  Further, the base film (B) is provided on the laminated surface of the near-infrared absorbing layer (C) in addition to the adhesion modified layer for the purpose of improving the adhesiveness at the interface with the surface layer (A) and suppressing the interference fringes. It is also desirable to have a layer for improving the adhesion at the interface with the near-infrared absorbing layer (C). In addition, although the layer for the adhesive improvement formed in the laminated surface of a near-infrared absorption layer (C) may have the said interference fringe suppression function, it does not need to have this function. In the present specification, among the layers for improving the adhesiveness of the base film (B), a layer for the purpose of improving the adhesiveness at the interface with the surface layer (A) and suppressing the interference fringes is referred to as “adhesion modification”. The layer is referred to as a “layer”, and a layer that does not have an interference fringe generation suppression function for the purpose of improving the adhesiveness at the interface with the near-infrared absorbing layer (C) is referred to as an “easily adhesive layer”.

  The aqueous polyester resin constituting the adhesion modified layer is soluble in an aqueous solution containing water or a water-soluble organic solvent, for example, alcohol, alkyl cellosolve, ketone solvent, ether solvent, etc. less than 50% by mass or It means a polyester resin having dispersibility. In order to impart water resistance to the polyester resin, a hydrophilic group such as a hydroxyl group, a carboxyl group, a sulfonic acid group, a phosphoric acid group, or an ether group may be introduced into the polyester molecule. From the point of view, introduction of a sulfonic acid group is preferable.

  In the case of introducing a sulfonic acid group, a polyester may be synthesized using a dicarboxylic acid having a sulfonic acid group as a copolymerization component. For the introduction of other hydrophilic groups, a method of synthesizing polyester using a copolymer component having each group can be employed. When using the dicarboxylic acid which has a sulfonic acid group, it is preferable to use in the range of 1-10 mol% among all the acid components for polyester synthesis | combination. If the amount of the dicarboxylic acid having a sulfonic acid group is too small, the polyester resin itself has poor aqueous expression, and the compatibility with a water-soluble titanium or zirconium chelate compound or acylate compound also decreases. A coating layer cannot be obtained. Moreover, when there is too much usage-amount of the dicarboxylic acid which has a sulfonic acid group, the moisture resistance of an adhesion modification layer will fall.

  Examples of the dicarboxylic acid having a sulfonic acid group include sulfoterephthalic acid, 5-sulfoisophthalic acid, 4-sulfonaphthaleneisophthalic acid-2,7-dicarboxylic acid, 5- (4-sulfophenoxy) isophthalic acid, and salts thereof. And so on.

  The aqueous polyester resin preferably has a glass transition temperature (Tg) of 40 ° C. or higher. When Tg is too low, the moisture resistance of the adhesion modified layer is lowered. Further, polyesters having a Tg of less than 40 ° C. tend to have a refractive index that is lowered due to the structure thereof, and the refractive index of the adhesion-modified layer is also lowered.

  In order to synthesize the aqueous polyester resin having Tg as described above, in addition to the copolymer component for introducing the hydrophilic group, an aromatic compound such as terephthalic acid, isophthalic acid, or naphthalenedicarboxylic acid may be used as the polyvalent carboxylic acid component. It is preferable that dicarboxylic acid is a main component. Examples of the polyhydric alcohol include glycols having a relatively small number of carbon atoms such as ethylene glycol, propane glycol, 1,4-butanediol, and neopentyl glycol; aromatic ring-containing diols such as an ethylene oxide adduct of bisphenol A; preferable. Further, there is no particular problem even if a rigid component such as biphenyl or a dicarboxylic acid or diol having a high refractive index atom such as bromine or sulfur is used as a polyester raw material within a range in which the physical properties of the film do not deteriorate.

  The other main component constituting the adhesion modified layer is a water-soluble titanium or zirconium chelate compound or acylate compound. The term “water-soluble” as used herein means solubility in an aqueous solution containing water or a water-soluble organic solvent at less than 50% by mass.

  Examples of water-soluble titanium chelate compounds include diisopropoxybis (acetylacetonato) titanium, isopropoxy (2-ethyl-1,3-hexanediolato) titanium, diisopropoxybis (triethanolaminato) titanium, di -N-butoxybis (triethanolaminato) titanium, hydroxybis (lactato) titanium, ammonium salt of hydroxybis (lactato) titanium, ammonium beloxocitrate ammonium salt and the like. Examples of the water-soluble titanium acylate compound include oxotitanium bis (monoammonium oxalate).

  Examples of the water-soluble zirconium chelate compound include zirconium tetraacetylacetonate, zirconium tributoxyacetylacetonate, and zirconium acetate. Examples of water-soluble zirconium acylate compounds include zirconium tributoxy systemate.

  The adhesion modified layer may be used in combination with an alkyd resin, a polyurethane resin, an acrylic resin, a vinyl resin such as polyvinyl alcohol, or the like as long as the effect is not impaired. Further, a cross-linking agent can be used in a range that does not adversely affect the effect of the adhesion modified layer. Examples of the crosslinking agent that can be used include adducts of urea, melamine, benzoguanamine, and the like with formaldehyde, amino resins such as alkyl ether compounds composed of these adducts and alcohols having 1 to 6 carbon atoms; multifunctional epoxy compounds; A polyfunctional isocyanate compound; a polyfunctional blocked isocyanate compound; a polyfunctional aziridine compound; an oxazoline compound;

  As described above, the adhesion-modified layer is formed using a coating solution for forming an adhesion-modified layer. In the coating solution, an aqueous polyester resin, a water-soluble titanium chelate compound, and a water-soluble titanium acylate are used. The mixing ratio (mass ratio) with at least one of the compound, the water-soluble zirconium chelate compound, or the water-soluble zirconium acylate compound is preferably 90/10 to 5/95.

  The adhesion-modified layer is formed on the surface layer (A) laminated surface side of the substrate film (B). The adhesion-modified layer is formed on both surfaces of the substrate film (B), that is, the surface layer (A). You may form not only between and between near-infrared absorption layers (C). When forming on both surfaces of the base film (B), both surfaces may have the same composition or different compositions.

  In the case where the adhesion modifying layer is provided only between the base film (B) and the surface layer (A), as described above, between the base film (B) and the near-infrared absorbing layer (C) It is preferable to provide a layer (easy-adhesive layer) for improving the adhesion between B) and the near-infrared absorbing layer (C).

  Examples of the resin constituting the easy-adhesion layer include copolymer polyester resin, polyurethane resin, acrylic resin, styrene-maleic acid graft polyester resin, acrylic graft polyester resin, and the like, and at least one of these is used. It is preferable. Among these, copolymer polyester resins, polyurethane resins, and styrene-maleic acid graft polyester resins are particularly preferable because they have excellent adhesiveness.

  The easy-adhesion layer is formed by preparing a coating solution for forming an easy-adhesion layer, and applying and drying this on a polyester film. A method for preparing a coating solution for forming an easy-adhesion layer will be described below by taking a system using a copolyester resin and a polyurethane resin as an example.

  The copolymer polyester resin includes a branched glycol as a constituent component. Examples of the “branched glycol” herein include 2,2-dimethyl-1,3-propanediol, 2-methyl-2-ethyl-1,3-propanediol, and 2-methyl-2-butyl-1 , 3-propanediol, 2-methyl-2-propyl-1,3-propanediol, 2-methyl-2-isopropyl-1,3-propanediol, 2-methyl-2-n-hexyl-1,3- Propanediol, 2,2-diethyl-1,3-propanediol, 2-ethyl-2-n-butyl-1,3-propanediol, 2-ethyl-2-n-hexyl-1,3-propanediol, 2,2-di-n-butyl-1,3-propanediol, 2-n-butyl-2-propyl-1,3-propanediol, 2,2-di-n-hexyl-1,3-propanediol And the like.

  The branched glycol is preferably used in a proportion of 10 mol% or more, more preferably 20 mol% or more in the total polyhydric alcohol. As the polyhydric alcohol other than the branched glycol, ethylene glycol is most preferable. If it is a small amount, diethylene glycol, propylene glycol, butanediol, hexanediol, 1,4-cyclohexanedimethanol and the like may be used.

  As the polyvalent carboxylic acid for synthesizing the copolymer polyester resin, terephthalic acid and isophthalic acid are most preferable. If the amount is small, an aromatic dicarboxylic acid such as diphenylcarboxylic acid or 2,6-naltalenedicarboxylic acid may be added and copolymerized. In order to impart water dispersibility in addition to the polyvalent dicarboxylic acid, it is preferable to use a dicarboxylic acid having a sulfonic acid group in the range of 1 to 10 mol%. Examples of the dicarboxylic acid having a sulfonic acid group include various compounds exemplified as a copolymer component of the aqueous polyester resin of the adhesion-modified layer.

  The polyurethane-based resin is, for example, a resin containing a block type isocyanate group, such as a heat-reactive water-soluble polyurethane in which a terminal isocyanate group is blocked with a hydrophilic group (hereinafter referred to as “block”). Can be mentioned. Examples of the isocyanate group blocking agent include bisulfites, phenols containing sulfonic acid groups, alcohols, lactam oximes, and active methylene compounds. Among the above blocking agents, bisulfites are particularly preferred as those having suitable heat treatment temperature and heat treatment time and widely used industrially.

  The blocked isocyanate group makes the urethane prepolymer hydrophilic or water-soluble. When heat energy is applied in the drying or heat setting process during film production, the blocking agent is removed from the isocyanate group, so that it self-crosslinks to form a network, and the mixed polyester resin is mixed with the network. Immobilize. It also reacts with the terminal groups of the copolyester resin.

  During the preparation of a coating solution for forming an easy adhesion layer, the polyurethane resin is hydrophilic and thus has poor water resistance. However, when the thermal reaction is completed by coating, drying, and heat setting, the hydrophilic group of the polyurethane resin (that is, the block is blocked). Since the agent is removed, a layer with good water resistance is formed.

  The urethane prepolymer used for the polyurethane resin has (1) an organic polyisocyanate having two or more active hydrogen atoms in the molecule, or two active hydrogen atoms in the molecule, and a molecular weight of 200-20. And (2) an organic polyisocyanate having two or more isocyanate groups in the molecule; and (3) a chain extender having at least two active hydrogen atoms in the molecule. The resulting compound has a terminal isocyanate group.

  Generally known as the compound (1) is a compound containing two or more hydroxyl groups, carboxyl groups, amino groups or mercapto groups in the terminal or molecular chain, and particularly preferred compounds include polyether polyols. , Polyester polyol, polyether ester polyol and the like.

  Examples of the polyether polyol include polymers of compounds such as alkylene oxides such as ethylene oxide and propylene oxide; styrene oxide; epichlorohydrin; or random copolymers thereof, block copolymers thereof, and many of these compounds. There are polymers obtained by addition polymerization to a monohydric alcohol.

  Examples of the polyester polyol and the polyether ester polyol mainly include linear or branched compounds. Polyvalent saturated or unsaturated carboxylic acids such as succinic acid, adipic acid, phthalic acid, maleic anhydride, or polyvalent carboxylic acids such as carboxylic acid anhydride, ethylene glycol, diethylene glycol, 1,4-butanediol, Polyalkylene ether glycols such as polyvalent saturated or unsaturated alcohols such as neopentyl glycol, 1,6-hexanediol, trimethylolpropane, relatively low molecular weight polyethylene glycol, relatively low molecular weight polypropylene glycol, Alternatively, it can be obtained by condensing with a polyhydric alcohol such as a mixture of these alcohols. Further examples of polyester polyols include polyesters obtained from lactones and hydroxy acids. In addition, as the polyether ester polyol, polyether esters obtained by adding ethylene oxide, propylene oxide, or the like to previously produced polyesters can also be used.

  Examples of the organic polyisocyanate (2) include isomers of toluylene diisocyanate, aromatic diisocyanates such as 4,4-diphenylmethane diisocyanate; aromatic aliphatic diisocyanates such as xylylene diisocyanate; isophorone diisocyanate, 4,4 -Alicyclic diisocyanates such as dicyclohexylmethane diisocyanate; Aliphatic diisocyanates such as hexamethylene diisocyanate and 2,2,4-trimethylhexamethylene diisocyanate; or trimethylolpropane and the like by mixing these compounds singly or in combination And added polyisocyanates; and the like.

  Examples of the chain extender (3) include glycols such as ethylene glycol, diethylene glycol, 1,4-butanediol and 1,6-hexanediol; polyhydric alcohols such as glycerin, trimethylolpropane and pentaerythritol; ethylenediamine Diamines such as hexamethylenediamine and piperazine; aminoalcohols such as monoethanolamine and diethanolamine; thiodiglycols such as thiodiethylene glycol; water;

  In order to synthesize the urethane polymer, the reaction is usually performed at a temperature of 150 ° C. or lower, preferably 70 to 120 ° C. for 5 minutes to several hours by a single-stage or multi-stage isocyanate polyaddition method using the chain extender. Let The ratio of isocyanate groups to active hydrogen atoms can be freely selected as long as it is 1 or more, but it is necessary that free isocyanate groups remain in the obtained urethane prepolymer. Furthermore, the content of free isocyanate groups may be 10% by mass or less, but considering the stability of the urethane polymer aqueous solution after being blocked, it is preferably 7% by mass or less.

  The obtained urethane prepolymer is blocked using a blocking agent (preferably bisulfite). When bisulfite is used, it is mixed with an aqueous bisulfite solution, and the reaction is allowed to proceed with good stirring for about 5 minutes to 1 hour. The reaction temperature is preferably 60 ° C. or lower. Thereafter, it is diluted with water to an appropriate concentration to obtain a heat-reactive water-soluble urethane composition. When this composition is used, it is adjusted to an appropriate concentration and viscosity. When the above composition is heated to about 80 to 200 ° C., the bisulfite of the blocking agent is dissociated and the active isocyanate group is regenerated, so that it is caused by a polyaddition reaction that occurs within or between the prepolymer molecules. A polyurethane polymer is produced or has the property of causing addition to other functional groups.

  Representative examples of the polyurethane resin having a block type isocyanate group include “Elastolon (trade name)” manufactured by Daiichi Kogyo Seiyaku Co., Ltd. Elastolone is an isocyanate group blocked with sodium bisulfite, and is water-soluble because a carbamoylsulfonate group having strong hydrophilicity is present at the molecular end.

  The mass ratio of the copolyester resin (a) and the polyurethane resin (b) when preparing the coating solution for forming an easy adhesion layer is (a) :( b) = 90: 10 to 10:90. It is preferable that (a) :( b) = 80: 20 to 20:80 is more preferable.

  A catalyst may be added to the coating solution for forming the adhesion modified layer or the easy adhesion layer in order to promote the thermal crosslinking reaction. As the catalyst, for example, various chemical substances such as inorganic substances, salts, organic substances, alkaline substances, acidic substances and metal-containing organic compounds are used. Moreover, in order to adjust pH of aqueous solution, you may add an alkaline substance or an acidic substance.

  When an adhesion-modified layer or an easy-adhesion layer is formed on the surface of the polyester film by a coating method, a known anionic or nonionic type is used to increase the wettability to the polyester film and coat the coating solution uniformly. A surfactant can be added and used.

  Examples of the solvent used in the coating solution for forming an adhesion modified layer and the coating solution for forming an easy adhesion layer include water; a mixed solvent of water and alcohols (ethanol, isopropanol, benzyl alcohol, etc.); When using alcohols, it is preferable to make it less than 50 mass% in all the coating liquids. Furthermore, as long as it is less than 10 mass% in all coating liquids, you may mix in the range which can dissolve organic solvents other than alcohol. However, the total amount of alcohols and other organic solvents in the coating solution is less than 50% by mass.

  When an organic solvent containing alcohol is used in an amount not more than the above upper limit value, the drying property is improved upon drying after application of the coating solution, and the effect that the appearance of the coating film is improved as compared with the case of using only water. can get. If the amount of organic solvent containing alcohol exceeds the above upper limit, the solvent evaporation rate will increase, so the concentration change of the coating solution will occur during coating, and the coating solution viscosity will increase and the coating property will decrease. There is a possibility that the appearance of the coating film may be deteriorated, and there is a concern of danger such as a fire.

  In addition, it is recommended that the solid content concentration (excluding particles described later) in the coating solution for forming an adhesion modified layer and the coating solution for forming an easy adhesion layer is 30% by mass or less, more preferably 10% by mass or less. The

  Incidentally, the solution viscosity of the coating solution is preferably 1.0 Pa · s or less. If the solution viscosity is too large, streaky coating thickness spots are likely to occur.

  The adhesion-modified layer and the easy-adhesion layer desirably contain particles that serve as a lubricant for the purpose of imparting easy slipperiness. As described above, in the polyester film, it is preferable to employ a configuration that does not substantially contain particles from the viewpoint of improving transparency. However, when such a configuration is adopted, there arises a problem that handling properties such as slipping property and winding property of the base film (B) are lowered. In order to solve this problem, the adhesion-modified layer and the easy-adhesion layer preferably contain lubricant particles for the purpose of imparting slipperiness, and appropriate protrusions are formed on the surface of these layers. is there.

  Therefore, it is preferable that the adhesion modifying layer forming coating solution and the easy adhesion layer forming coating solution contain particles that serve as a lubricant. Examples of such particles include inorganic particles such as calcium carbonate, calcium phosphate, silica, kaolin, talc, titanium dioxide, alumina, barium sulfate, calcium fluoride, lithium fluoride, zeolite, molybdenum sulfide; Polymethyl methacrylate particles) and organic particles such as calcium oxalate. Among these, when polyester is used as the constituent resin for the adhesion-modified layer and the easy-adhesion layer, silica is preferable because the refractive index with the polyester is relatively close and high transparency can be easily obtained.

  The average particle size of the particles is generally 0.01 to 1.0 μm, more preferably 0.01 to 0.5 μm, and still more preferably 0.01 to 0.1 μm. If the average particle size is too large, the surface of the adhesion-modified layer or the easy-adhesion layer becomes too rough, and the transparency tends to decrease. On the other hand, when the average particle size is too small, the slipperiness may not be sufficiently secured.

  The particle content in the coating solution for forming an adhesion modified layer and the coating solution for forming an easy adhesion layer is generally set so that the content in the layer after coating and drying is 60% by mass or less. Yes, more preferably 50% by mass or less, and still more preferably 40% by mass or less. When there is too much particle content, the adhesive improvement effect by an adhesion modification layer or an easily bonding layer may be impaired.

  Two or more kinds of the above particles may be blended, or the same kind of particles having different average particle diameters may be blended. In any case, it is preferable to adjust so that the average particle diameter of the whole particle and the total content satisfy the above range.

  When applying the coating solution for forming an adhesive modification layer and the coating solution for forming an easy adhesion layer to polyester, it is preferable to remove coarse aggregates of particles in the coating solution. It is recommended to place the filter media to be filtered. The filter medium preferably has a filtration particle size of 25 μm or less (initial filtration efficiency 95%). If the filter particle size is too large, coarse aggregates may not be sufficiently removed. Many coarse agglomerates that could not be removed spread to the adhesion modified layer or the easy adhesion layer when uniaxially or biaxially stretched after coating and drying, and may be recognized as aggregates of 100 μm or more. As a result, many optical defects occur. The type of the filter medium is not particularly limited as long as it has the above performance, and examples thereof include a filament type, a felt type, and a mesh type. The material of the filter medium is not particularly limited as long as it has the above-described performance and does not adversely affect the coating solution. Examples thereof include stainless steel, polyethylene, polypropylene, and nylon.

  Various additives such as an antistatic agent, a pigment, an organic filler, and a lubricant may be mixed in the coating solution for forming an adhesion modified layer and the coating solution for forming an easy adhesion layer as long as the effects thereof are not impaired. Furthermore, since the coating liquid is aqueous, other water-soluble resins, water-dispersible resins, emulsions, and the like may be added to the coating liquid in order to further improve the performance within a range that does not impair the effect.

  In order to apply | coat the coating liquid for adhesion modification layer formation, and the coating liquid for easy-adhesion layer formation to a polyester film, it can carry out by a well-known arbitrary method. Examples include reverse roll coating method, gravure coating method, kiss coating method, roll brush method, spray coating method, air knife coating method, wire barber coating method, pipe doctor method, impregnation / coating method, curtain coating method, etc. The methods can be performed alone or in combination.

  When the polyester film is a biaxially oriented film, the timing of applying the coating liquid may be at the time when the heat setting is completed after the biaxial stretching and the biaxially oriented film is completed. More preferably. More preferably, it is a stage before the crystal orientation of the biaxially oriented film is completed.

For both the adhesion-modified layer and the easy-adhesion layer, the coating amount of the coating solution [the amount of adhesion to the base film (B)] is the running biaxially oriented polyester film (or an intermediate product of the biaxially oriented polyester film). It is preferable to set it as 0.01-5g per m < ² >, and it is more preferable to set it as 0.2-4g.

  For example, in the case where a biaxially oriented polyester film is produced by a sequential biaxial stretching method, and when each of the above coating liquids is applied after uniaxial stretching (uniaxially oriented film) in the production process of the biaxially oriented polyester film, The uniaxially oriented film after coating is guided to a tenter for stretching and heat setting, and heated there, so that a stable coating (adhesion modified layer and easy adhesion layer) is formed by a thermal crosslinking reaction. It becomes a film (B).

  From the viewpoint of further improving the adhesion (adhesion modified layer) of the surface layer (A) to the hard coat layer and the adhesion (adhesion modified layer or easy adhesion layer) to the near infrared absorption layer (C). After applying the coating solution, it is desirable to perform a heat treatment for 1 minute or more at a temperature of 100 ° C. or higher.

  In addition, as an environment for applying the coating solution for forming an adhesion-modified layer or the coating solution for forming an easy-adhesion layer, it is desirable that the cleanliness is class 1000 or less in order to reduce adhesion of dust.

<Surface layer (A)>
The surface layer (A) has an antireflection function, and is provided on the surface of the adhesion modified layer of the base film (B). The “antireflection function” here refers to a function of preventing surface reflection, increasing light transmittance, and preventing “glare”.

  This surface layer (A) usually has a three-layer structure in which a low refractive index layer, a high refractive index layer, and a hard coat layer are laminated in this order from the outermost surface side (opposite surface of the adhesion modified layer). Yes. That is, the reflection of the reflected light at the interface between the low refractive index layer and the high refractive index layer is used to reduce surface reflection, and the hard coat layer prevents damage to the near infrared absorption filter.

  As the hard coat layer, a layer obtained by curing a resin that can be cured by an electron beam or light (such as ultraviolet rays) (hereinafter referred to as “photo-curable resin”) is preferable.

  As the photocurable resin, there are 2 (meth) acryloyl groups in the molecule that can be cured by irradiation with electron beams or light (such as ultraviolet rays), such as known epoxy acrylate (vinyl ester resin), polyester acrylate, urethane acrylate. Resins (oligomers or polymers) having more than one can be used.

  Said photocurable resin is mixed with a reactive diluent, and is used as a photocurable resin composition. The reactive diluent has one or more reactive groups in the molecule, adjusts the viscosity of the photocurable resin composition, contributes to the curing reaction, adherence to other layers, hardness, etc. Has a role to improve. Specifically, aromatic monomers such as styrene, vinyltoluene, divinylbenzene; vinyl acetate; N-vinylpyrrolidone; methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, ethylhexyl (meth) acrylate , Hexanediol (meth) acrylate, (di) ethylene glycol di (meth) acrylate, propylene glycol di (meth) acrylate, tripropylene glycol di (meth) acrylate, trimethylolpropane di (meth) acrylate, trimethylolpropane tri ( (Meth) acrylate, pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol hexa (meth) acrylate, 1,6-hexanedi Ruji (meth) acrylate, include (meth) acrylates such as neopentyl glycol di (meth) acrylate may be used alone or in combination of two or more.

  In addition, when making it harden | cure by light (ultraviolet rays etc.), it is desirable to make a photoinitiator and a photosensitizer contain in a photocurable resin composition. As the photopolymerization initiator, compounds known as photopolymerization initiators such as acetophenones, benzophenones, Michler benzoylbenzoate, α-amyloxime ester, tetramethylthiuram monosulfide, and thioxanthones can be applied. As the photosensitizer, a known compound such as n-butylamine, triethylamine, tri-n-butylphosphine, or the like can be used.

  The photocurable resin composition may contain a solvent for the purpose of adjusting the viscosity. Hydrocarbons such as toluene and xylene; cellosolves such as cellosolve and butylcellosolve; carbitols such as carbitol and butylcarbitol; esters such as cellosolve acetate, carbitol acetate, and propylene glycol monomethyl ether acetate; methyl isobutyl ketone, Ketones such as methyl ethyl ketone; ethers such as diethylene glycol dimethyl ether; and the like.

  The hard coat layer is formed by applying and drying the above-mentioned photocurable resin composition on the base film (B) (on the adhesion modified layer), and curing it by irradiating with an electron beam or light (such as ultraviolet rays). The method should be adopted.

  The low refractive index layer and the high refractive index layer are not particularly limited. It may be an organic layer, an inorganic layer, or an inorganic / organic hybrid layer. As the formation method, a method of depositing a compound constituting the layer mainly by an evaporation method or a sputtering method as a method of forming an inorganic layer, and a method of forming a layer mainly as a method of forming an organic layer. The method of apply | coating and drying the coating liquid containing the compound (resin etc.) to perform is mentioned.

In the case of an inorganic system, the high refractive index layer is, for example, a layer made of ZnO, TiO ₂ , CeO ₂ , SnO ₂ , ZrO ₂ , ITO (indium-tin oxide) or the like (for example, a refractive index of 1.65 or more). It may be formed by vapor deposition or sputtering. The low refractive index layer may be formed of a layer such as MgF ₂ or SiO ₂ by vapor deposition or sputtering.

  In addition, a low refractive index layer and a high refractive index layer can be formed by hydrolytic condensation of a silane compound (organosilane compound). That is, a coating solution containing a silane compound is applied and dried, and is hydrolyzed and condensed to form a layer. The hydrolysis condensation may be performed in a coating solution, or a silane compound that has already been hydrolyzed and condensed may be used. Examples of silane compounds that can be used include γ-aminopropyltrimethoxysilane (and its partially hydrolyzed condensate), tetraethoxysilane, and the like. In order to make a difference in refractive index between the low refractive index layer and the high refractive index layer, the type of silane compound used for each layer may be changed. For example, when γ-aminopropyltrimethoxysilane (and its partially hydrolyzed condensate) is used for the low refractive index layer, tetraethoxysilane may be used for the high refractive index layer.

  Examples of the solvent used for the coating solution include water; a mixed solvent of water and alcohols (such as methanol, ethanol, isopropanol); and the like, and an acid (such as an inorganic acid such as hydrochloric acid) may be added as necessary. After application of the coating solution, drying (and hydrolysis reaction) can be performed to form a low refractive index layer and a high refractive index layer.

  The surface layer (A) desirably has high hardness from the viewpoint of improving scratch resistance. For example, the outermost pencil hardness (pencil hardness measured according to JIS K 5400) is 1H or more. Is desirable. Such hardness can be ensured by adopting each of the exemplified layer configurations.

  Moreover, you may provide another well-known functional layer in the surface side (on the surface of a low-refractive-index layer) of a surface layer (A). For example, an antistatic layer for securing antistatic properties, an antifouling layer having a function of preventing dirt such as fingerprints, sebum, sweat, cosmetics from adhering and easily wiping off even if adhering Is mentioned.

<Near-infrared absorbing layer (C)>
The near-infrared absorbing layer (C) is a layer containing a dye having a maximum absorption wavelength in the near-infrared region of 800 to 1000 nm. The presence of the near-infrared absorbing layer (C) can block near-infrared rays generated by plasma emission when used in a filter for plasma display, so that an effect of suppressing malfunction of a remote controller using near-infrared rays is exhibited. . The near-infrared absorbing layer (C) according to the present invention is formed from a coating solution containing a near-infrared absorbing dye or a resin.

  Near-infrared absorbing dyes include diimmonium, phthalocyanine, dithiol metal complex, naphthalocyanine, azo, polymethine, anthraquinone, naphthoquinone, pyrylium, thiopyrylium, squarylium, croconium, tetradehydride Ocholine-based, triphenylmethane-based, cyanine-based, azo-based, and aminium-based compounds may be used, and these may be used alone or in admixture of two or more. Among them, it is preferable to use a diimmonium compound [the following formula (III)] that has a large absorption in the near infrared region, a wide absorption region, and a high transmittance in the visible region.

(Wherein R _{1 to} R ₈ represent a hydrogen atom, an alkyl group, an aryl group, an alkenyl group, an aralkyl group, and an alkynyl group, and may be the same or different. R _{9 to} R ₁₂ may be different from each other). Represents a hydrogen atom, a halogen atom, an amino group, a cyano group, a nitro group, a carboxyl group, an alkyl group or an alkoxyl group, which may be the same or different, and each of R _{1 to} R ₁₂ binds a substituent. can things which may have a substituent .X ^- represents an anion).
Specific examples of R _{1 to} R _{8 in} the above formula (III) include the following. Examples of the alkyl group include methyl group, ethyl group, n-propyl group, iso-propyl group, n-butyl group, iso-butyl group, tert-butyl group, n-amyl group, n-hexyl group, n-octyl group, Examples include 2-hydroxyethyl group, 2-cyanoethyl group, 3-hydroxypropyl group, 3-cyanopropyl group, methoxyethyl group, ethoxyethyl group, butoxyethyl group. Examples of the aryl group include a phenyl group, a fluorophenyl group, a chlorophenyl group, a tolyl group, diethylaminophenyl, and a naphthyl group. Examples of the alkenyl group include a vinyl group, a propenyl group, a butenyl group, and a pentenyl group. Examples of the aralkyl group include a benzyl group, a p-fluorobenzyl group, a p-chlorophenyl group, a phenylpropyl group, and a naphthylethyl group.

R _{9 to} R ₁₂ in the above formula (III) are hydrogen, fluorine, chlorine, bromine, diethylamino group, dimethylamino group, cyano group, nitro group, methyl group, ethyl group, propyl group, trifluoromethyl. Group, methoxy group, ethoxy group, propoxy group and the like. X ⁻ is fluorine ion, chlorine ion, bromine ion, iodine ion, perchlorate ion, hexafluoroantimonate ion, hexafluorophosphate ion, tetrafluoroborate ion, bis (trifluoromethanesulfonyl) imido ion, etc. Is mentioned. However, the present invention is not limited to the above examples. Some of these are available as commercial products, for example “Kayasorb IRG-022, IRG-023, IRG-024” manufactured by Nippon Kayaku Co., Ltd., “CIR-1080, CIR-1081, CIR-1083” manufactured by Nippon Carlit. , CIR-1085 "and the like can be preferably used.

  In addition to the diimmonium compound represented by the above formula (III), the near-infrared absorbing layer (C) is also preferably added with other near-infrared absorbing dyes for the purpose of expanding the near-infrared absorption range and adjusting the color. . Although it does not specifically limit as near-infrared absorption pigment | dyes other than a diimmonium type compound, For example, the "EEXKARA-IR-1, IR-2, IR-3, IR-4, IR-10, IR-10A by Nippon Shokubai Co., Ltd." Mitsui Chemicals, Inc .: IR-12, IR-14, TXEX-805K, TX-EX807K, TX-EX808K, TX-EX811K, TX-EX813K, Mitsui Chemicals' "MIR-369, MIR-389" Dithiol metal complex compounds such as “SIR-128, SIR-130, SIR-132, SIR-159” manufactured by the company, and “MIR-101, MIR-121” manufactured by Midori Chemical Co., etc. can be suitably used. Furthermore, "TZ-103, TZ-104, TZ-105, TZ-109, TZ-111, TZ-114" manufactured by Asahi Denka Co., Ltd., "CY-9, CY-10" manufactured by Nippon Kayaku Co., Ltd., Yamada Chemical Co., Ltd. "IR-301" manufactured by the company can also be used.

The near-infrared absorbing dye is present to achieve the required near-infrared absorption and transmission in the visible range. For example, on the base material film (B), it is preferable to present at 0.01 g / m ² or more 1.0 g / m ² or less. If the amount of the near-infrared absorbing dye is small, the absorption ability in the near-infrared region may be insufficient, and conversely, if it is large, the transparency in the visible light region is insufficient and the brightness of the plasma display is reduced. May decrease.

  It is recommended that the near-infrared absorbing dye be present on the base film (B) in a state of being dispersed or dissolved in the resin. The resin is not particularly limited as long as the near-infrared absorbing dye can be uniformly dissolved or dispersed, but polyester-based, acrylic-based, polyamide-based, polyurethane-based, polyolefin-based, polycarbonate-based, polystyrene-based, etc. Various synthetic resins, natural polymers such as gelatin and cellulose derivatives can be preferably used. Examples of commercially available resins include “O-PET (manufactured by Kanebo Co., Ltd.)”, “ZEONEX (manufactured by Zeon Corporation)”, “ARTON (manufactured by JSR Corporation)”, and “Optretz (manufactured by Hitachi Chemical Co., Ltd.)” , “Byron (manufactured by Toyobo Co., Ltd.)” and the like. Among these, a polyester resin is preferable because it is excellent in flexibility and adhesion to a substrate. That is, when the resin is hard, minute cracks may occur in the near-infrared absorbing layer (C) in the near-infrared absorbing filter manufacturing process.

  Furthermore, it is desirable that the Tg of the resin be equal to or higher than the guaranteed use temperature of a device (for example, a plasma display) to which the near infrared absorption filter of the present invention is applied. When the Tg of the resin is lower than the guaranteed use temperature of the applicable device, the dyes dispersed in the resin react when the film is used, or the resin absorbs moisture during the period and deteriorates the resin and the dye May go on.

  The Tg of the resin is more preferably 85 ° C. or higher (more preferably 100 ° C. or higher) and 160 ° C. or lower. When the Tg of the resin is below the above range, the interaction between the dye and the resin, the interaction between the dyes, and the like occur, and the frequency of the modification of the dye tends to increase. Further, as will be described later, the near-infrared absorbing layer (C) is formed by a method in which a coating liquid containing a near-infrared absorbing dye, a resin and a solvent is applied onto the base film (B) and dried. If the Tg of the resin exceeds the above range, it is necessary to heat to a high temperature in order to sufficiently remove the solvent, and the base film (B) is wrinkled and the flatness is lowered, or the pigment is deteriorated. It becomes easy. On the other hand, when drying is performed at a low temperature, a prolonged drying time is unavoidable, and productivity tends to be remarkably deteriorated. Moreover, when drying becomes inadequate, the residual amount of the coating liquid solvent in a near-infrared absorption layer (C) will increase. When the residual solvent amount in the near-infrared absorbing layer (C) is increased, the apparent Tg of the resin is lowered, so that the dye is easily modified.

  The content of the near infrared ray absorbing dye in the total amount of the resin and the near infrared ray absorbing dye is preferably 1% by mass or more and 10% by mass or less. If the content of the near-infrared absorbing dye is too small, the layer must be thickened in order to impart the intended near-infrared absorbing ability to the near-infrared absorbing layer (C). Therefore, since the coating amount of the coating liquid for forming the near-infrared absorbing layer (C) also increases, it is necessary to dry at a high temperature and / or for a long time in order to increase the drying efficiency. As a result, when dried at a high temperature, the deterioration of the pigment and the poor flatness of the transparent substrate are likely to occur, and the productivity deteriorates when the drying takes a long time. On the other hand, if the content of the near-infrared absorbing dye is too large, the interaction between the dyes is likely to occur, and even if the amount of residual solvent in the near-infrared absorbing layer (C) is reduced, the dye is denatured over time. It tends to happen.

  In addition, the near-infrared absorption filter of the present invention is formed by forming various functional layers having no other base material, using the base film (B) as a base material, from the viewpoint of ensuring good productivity, It is desirable that various functional layers have excellent formability. That is, even if the surface layer (A) and the adhesion-modified layer can be satisfactorily formed on the well-produced base film (B), if the near-infrared absorbing layer (C) is poorly formed, An intermediate product that has been successfully manufactured becomes a defective product. Therefore, it is desirable to improve the yield of each layer by improving the formability of each layer.

  In order to improve the formability of the near-infrared absorbing layer (C), it is preferable that the coating solution for forming the near-infrared absorbing layer (C) contains a surfactant. The use of a surfactant improves the dispersibility of the near-infrared absorbing dye in the resin, the appearance of the near-infrared absorbing layer (C), in particular dents due to minute bubbles, dents due to adhesion of foreign matter, and repellency during the drying process. Etc. are improved. Furthermore, the surfactant exerts an action of improving the slipperiness of the surface by bleeding on the surface of the near-infrared absorbing layer (C) by coating and drying of the coating solution. Therefore, at the intermediate stage of the manufacturing process of the near-infrared absorbing filter, the surface of the near-infrared absorbing layer (C) or the surface opposite to the layer of the filter may not have surface irregularities formed by the addition of the above-mentioned particles, Handling property becomes good, and such an intermediate product can be wound into a roll.

  As the surfactant, known surfactants (cationic surfactants, anionic surfactants, nonionic surfactants) can be used, but pigments due to the coexistence of surfactants (near infrared absorbing pigments, From the viewpoint of suppressing the deterioration of the neon cut dye), nonionic surfactants having no polar group in the molecule are preferable, and silicon surfactants or fluorosurfactants are more effective for surface activity. Recommended for superiority.

  Silicon-based surfactants include amino silane, acrylic silane, vinyl benzyl silane, vinyl benzilyl amino silane, glycid silane, mercapto silane, dimethyl silane and other silane compounds; polydimethyl siloxane, polyalkoxy siloxane, hydrodiene modified siloxane, vinyl modified siloxane Siloxanes such as siloxane, vitoxy modified siloxane, amino modified siloxane, carboxyl modified siloxane, halogenated modified siloxane, epoxy modified siloxane, methacryloxy modified siloxane, mercapto modified siloxane, fluorine modified siloxane, alkyl group modified siloxane, phenyl modified siloxane, alkylene oxide modified siloxane Compound; and the like.

  Fluorosurfactants include ethylene tetrafluoride; perfluoroalkyl ammonium salt, perfluoroalkyl sulfonic acid amide, sodium perfluoroalkyl sulfonate, perfluoroalkyl potassium salt, perfluoroalkyl carboxylate, perfluoroalkyl sulfone. Perfluoroalkyl compounds such as acid salts, perfluoroalkylethylene oxide adducts, perfluoroalkyltrimethylammonium salts, perfluoroalkylaminosulfonates, perfluoroalkyl phosphates, perfluoroalkylalkyl betaines, perfluoroalkyl halides; Etc.

  In addition, it is preferable that HLB (Hydrophilic-Lypholic-Balance) of surfactant is 2-12. If the HLB is too low, the surface activity may be insufficient and the effect of improving the appearance of the near-infrared absorbing layer (C) may be insufficient. On the other hand, if the HLB is too large, the above-mentioned slipperiness improving effect tends to decrease, and the water absorption of the near-infrared absorbing layer (C) increases, so that the temporal stability of the dye tends to decrease. The above HLB is a W.S. of Atlas Powder. C. Griffin is a parameter named as described above, and is an index indicating the balance between surfactant, hydrophilicity and lipophilicity. The weakest hydrophilicity is defined as 1, and the strongest hydrophilicity is defined as 40. . That is, the higher the HLB, the closer to water solubility, and the lower the HLB, the closer to oil solubility.

  The content of the surfactant in the near-infrared absorbing layer (C) is desirably 0.01% by mass or more and 2% by mass or less. When there is too little content of surfactant, the appearance improvement effect of the near-infrared absorption layer (C) by using surfactant, and the slip improvement effect may become inadequate. On the other hand, if the surfactant content is too high, the water absorption of the near-infrared absorbing layer (C) increases, so that the temporal stability of the near-infrared absorbing dye may be lowered.

  The near-infrared absorbing layer (C) -forming coating solution contains a near-infrared absorbing dye, a resin, and an organic solvent (preferably, a surfactant). The organic solvent is used for the purpose of dissolving or dispersing the pigment and the resin and improving the coating property. From the viewpoint of improving coatability, the coating solution is a method in which a pigment and a resin are separately dissolved or dispersed and then mixed, and further diluted with an organic solvent as necessary to adjust the solid content concentration to an appropriate range. It is preferable to produce by.

  Examples of organic solvents include methanol, ethanol, n-propanol, isopropanol, n-butanol, tridecyl alcohol, cyclohexyl alcohol, 2-methylcyclohexyl alcohol, and the like; ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, propylene glycol , Glycols such as dipropylene glycol and glycerin; ethylene glycol monomethyl ether, ethylene glycol monoethylene ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol butyl ether, ethylene glycol monomethyl ether acetate, ethylene glycol monoether Glycol ethers such as butyl acetate, ethylene glycol monobutyl acetate, diethylene glycol monomethyl acetate, diethylene glycol monoethyl acetate, diethylene glycol monobutyl acetate; esters such as ethyl acetate, isopropyl acetate and n-butyl acetate; acetone, methyl ethyl ketone, methyl isobutyl ketone , Ketones such as cyclohexanone, cyclopentanone, isophorone, diacetone alcohol; and the like. These organic solvents can be used alone or in admixture of two or more.

  Among the organic solvents, ketones excellent in solubility of the dye are suitable, and the amount of ketones with respect to the total amount of organic solvent contained in the coating solution is preferably 30% by mass or more and 80% by mass or less. Organic solvents other than ketones may be selected in consideration of leveling properties and drying properties of the coating liquid.

  The boiling point of the organic solvent is preferably 60 ° C. or higher and 180 ° C. or lower. When the boiling point of the organic solvent is too low, the solid content concentration of the coating solution is likely to change during coating, and the coating thickness may be difficult to stabilize. On the other hand, if the boiling point of the organic solvent is too high, the residual solvent amount in the near-infrared absorbing layer (C) tends to increase, so that the dye stability with time tends to deteriorate.

  As a method for dissolving or dispersing the near-infrared absorbing dye and the resin (and also the surfactant) in the organic solvent, methods such as stirring, dispersion and pulverization under heating can be employed. By heating at the time of dissolution, the solubility of the pigment and the resin can be increased, and appearance defects due to undissolved materials can be prevented. Further, the near-infrared absorbing layer (C) having excellent transparency can be obtained by dispersing or crushing the resin and the pigment in an organic solvent and dispersing the resin and the pigment in the coating solution in a fine particle state having an average particle size of 0.3 μm or less. ) Can be formed. A well-known thing can be used as a disperser or a disintegrator. Specific examples include a ball mill, a sand mill, an attritor, a roll mill, an agitator, a colloid mill, an ultrasonic homogenizer, a homomixer, a pearl mill, a wet jet mill, a paint shaker, a butterfly mixer, a planetary mixer, and a Henschel mixer.

  In addition, when the near-infrared absorbing layer (C) is formed by directly using a coating solution containing foreign matter having a size of 1 μm or more and undissolved matter (collectively referred to as “foreign matter”), a dent or the like is formed around the foreign matter. May occur, resulting in a defect of 100 to 1000 μm size and the appearance may be deteriorated. Therefore, it is preferable to remove foreign matters in the coating solution by filtering with a filter or the like prior to coating. Various types of filters can be suitably used, but it is particularly preferable to use a filter that can remove 99% or more of foreign matters having a size of 1 μm or more.

  It is preferable that the solid content concentration (including the near-infrared absorbing dye and the resin) in the coating solution is 10% by mass or more and 30% by mass or less. More preferably, it is 12 mass% or more and 25 mass% or less. If the solid content concentration of the coating solution is too low, the amount of organic solvent in the coating solution increases, so drying during the formation of the near-infrared absorbing layer (C) takes a long time and productivity deteriorates. When the amount of residual solvent in the absorbent layer (C) increases and the aging stability of the dye tends to deteriorate, especially when stored for a long time under high temperature and high humidity (for example, 60 ° C., relative humidity 95%, 500 hours) In addition, the transmittance and color tone of the film tend to increase. On the other hand, if the solid content concentration of the coating solution is too high, the viscosity of the coating solution becomes large and the leveling property may be insufficient, resulting in a poor appearance of the near-infrared absorbing layer (C).

  Incidentally, the viscosity of the coating solution is preferably adjusted to 10 cps or more and 300 cps or less from the viewpoint of improving the appearance of the near-infrared absorbing layer (C). In order to adjust the viscosity of the coating solution within the above range, the solid content concentration may be adjusted or an organic solvent having a low viscosity may be used. The viscosity of the coating solution is a value measured with a B-type viscometer.

  As a method for applying the near infrared absorbing layer (C) forming coating solution on the base film (B), a gravure coating method, a kiss coating method, a dip method, a spray coating method, a curtain coating method, an air knife coating method, a blade coating. Conventionally used methods such as a method, a reverse roll coating method, a bar coating method, and a lip coating method can be applied. In particular, it is preferable to use an apparatus that employs a gravure coating method capable of more uniform coating, particularly a reverse gravure coating method. In this case, the diameter of the gravure roll of the apparatus is preferably 80 mm or less. When the diameter of the gravure roll is large, wrinkle streaks may occur in the flow direction (film traveling direction).

The coating amount of the coating solution is not particularly limited. For example, the coating amount after drying is 1 g / m ² or more, more preferably 3 g / m ² or more, and 50 g / m ² or less, more preferably 30 g / m ^2. The following is desirable. If the coating amount after drying is too small, the near-infrared absorbing ability may be insufficient, and it is necessary to adjust the near-infrared absorbing ability to a target level by increasing the amount of the near-infrared absorbing dye in the resin. Since the distance between the dyes becomes shorter, the interaction between the dyes becomes stronger, the dyes are likely to deteriorate, and the stability over time tends to be lowered. On the other hand, if the coating amount after drying is too large, the near-infrared absorption ability is sufficient, but the transmittance in the visible light region is lowered, and when applied to a plasma display, the brightness may be lowered. . In order to avoid this, the pigment concentration in the planar view of the near-infrared absorbing layer (C) (the amount of pigment present per unit area in the planar view) is reduced, and the distance between the pigments is increased to make it visible. Although it is conceivable to increase the transmittance in the light region, for that purpose, the thickness of the near-infrared absorbing layer (C) must be increased, and drying after application of the coating liquid tends to be insufficient. As a result, the amount of residual solvent in the near-infrared absorbing layer (C) increases, and the temporal stability of the dye deteriorates. On the other hand, flatness of the substrate deteriorates if sufficient drying is attempted.

  For drying after the coating liquid is applied, a known drying method such as hot air drying or drying with an infrared heater can be adopted, but hot air drying with a high drying speed is preferable.

  Furthermore, it is recommended that the drying process includes the following first drying process, second drying process, and cooling process.

  The first drying step is an initial constant rate drying step after coating. In this step, drying is preferably performed using wind at a temperature of 20 ° C. to 80 ° C. and a wind speed of 2 m / second to 30 m / second. If the initial drying conditions are strict (the temperature of the wind is increased and the amount of air is increased), minute defects such as minute coating omission, minute repellency, and cracks derived from the foam contained in the coating liquid will occur in the near infrared. It becomes easy to generate | occur | produce in an absorption layer (C). On the other hand, if the initial drying conditions are sweet (the temperature of the wind is lowered and the amount of air is reduced), the near-infrared absorbing layer (C) looks good, but it takes a long time to dry and the productivity deteriorates. There is a problem in terms of cost. In addition, it is preferable that the drying time (passage time of a film) in a 1st drying process shall be 10-120 seconds, for example.

  The second drying process is a reduction drying process after the first drying process. In this step, the temperature is higher than that in the first drying step, and the solvent in the near-infrared absorbing layer (C) is reduced. Specifically, it is preferable to dry with a temperature of 120 ° C. or more and 180 ° C. or less. If the temperature of the wind is too low, the amount of solvent in the near-infrared absorbing layer (C) is difficult to decrease. On the other hand, if the temperature of the wind is too high, thermal wrinkles are generated on the transparent substrate, and flatness is likely to be poor, and thermal degradation of the near infrared absorbing dye tends to occur. The drying time (film transit time) is preferably 5 seconds or more and 3 minutes or less (more preferably 1 minute or less). When the drying time is short, the residual solvent in the near-infrared absorbing layer (C) tends to increase. On the other hand, when the drying time is long, productivity is lowered and heat wrinkles are easily generated in the base film (B), which tends to cause poor flatness. In addition, it is recommended that the wind speed in a 2nd drying process shall be 2-50 m / sec, for example.

  The cooling process is the final process of the drying process. In this step, the resin [resin in the near-infrared absorbing layer (C)] is cooled with wind at a temperature equal to or lower than Tg, and the temperature of the base film (B) is set to be equal to or lower than Tg of the resin in a flat state. Is preferred. The temperature of the wind is more preferably Tg-5 ° C, more preferably Tg-10 ° C. When the film leaves the drying furnace at a high temperature, the near-infrared absorbing layer (C) surface becomes slippery when it comes into contact with the film running roll before winding up, In addition to being easily scratched, the film may be curled. In the cooling step, the wind speed is preferably set to 2 to 50 m / second, for example, and the cooling time is preferably set to 5 to 120 seconds, for example.

  It is preferable that the near-infrared absorbing layer (C) does not change the near-infrared transmittance and the visible light transmittance even when it is left under high temperature and high humidity. When the temporal stability under high temperature and high humidity is poor, not only the color tone of the image on the display changes but also the effect of the present invention such as preventing malfunction of the electronic device using the near infrared remote controller may be lost. . In order to improve the temporal stability of the light transmittance, the amount of residual solvent in the near-infrared absorbing layer (C) can be reduced by adjusting the type of solvent used in the coating solution, the thickness of the coating layer, and the drying conditions. Alternatively, this can be achieved by adjusting the dye concentration per unit area in plan view of the near-infrared absorbing layer (C). The amount of residual solvent in the near-infrared absorbing layer (C) (the amount of residual solvent derived from the coating solution) is preferably as small as possible. For example, the total amount of the near-infrared absorbing layer (C) is 3% by mass or less. Is preferred. If the residual solvent is 3% by mass or less, there will be no substantial difference in stability over time. On the other hand, if the drying conditions are excessively strict for the purpose of further reducing the amount of residual solvent, adverse effects such as poor flatness of the film may occur.

  As the appearance of the near-infrared absorbing layer (C), it is desirable that there is no defect having a diameter of 300 μm or more, more preferably 100 μm. The defect of 300 μm or more becomes a bright spot when placed on the front surface of the plasma display, and the defect becomes more prominent. Also, streaks and unevenness of the near infrared absorption layer (C) may become prominent on the front surface of the plasma display and become a problem. The appearance of such a near-infrared absorbing layer (C) can be ensured by adopting the above-mentioned materials, forming methods and forming conditions.

<Adhesive layer (D)>
In the near-infrared absorption filter of this invention, it is also preferable to have an adhesion layer (D) on the near-infrared absorption layer (C) side surface. By this adhesive layer (D), it can be stuck and fixed to the surface of the plasma display panel or a translucent sheet (E) (described later) having an electromagnetic wave absorbing function. The transparent adhesive used for the adhesive layer (D) is not particularly limited, and those known in the art can be used. For example, acrylic adhesives such as butyl acrylate; rubber adhesives; TPE adhesives based on thermoplastic elastomers (TPE) such as SEBS (styrene-ethylene-butadiene-styrene) and SBS (styrene-butadiene-styrene) Agents; and the like.

  It is also a preferred embodiment to provide a known separator film (such as a PET film subjected to silicone treatment) on the surface of the adhesive layer (D).

<Translucent sheet (E)>
It is also preferable that the near-infrared absorption filter of this invention has the translucent sheet | seat (E) which has an electromagnetic wave absorption function. This translucent sheet (E) is provided so as to be positioned between the near-infrared absorbing layer (C) and the plasma display panel. For example, it is a preferable aspect that it is laminated | stacked on the near-infrared absorption layer (C) side through the said adhesion layer (D). In addition, the near-infrared absorbing layer (C) and the translucent sheet (E) are laminated by a method other than the adhesive layer (D), and the adhesive layer (D) is formed on the outermost surface of the translucent sheet (E). A mode of providing is also preferable. The adhesive layer (D) in this case is used for adhering to the plasma display panel.

Although the translucent sheet | seat (E) will not be specifically limited if it has translucency and an electromagnetic wave absorption function, For example, the following are mentioned.
(I) a conductive mesh composed of metal fibers or metal-coated organic fibers;
(Ii) An edging method conductive mesh composite sheet obtained by laminating a metal film on a transparent film and then edging it into a shape such as a lattice shape or a punching metal shape by a technique such as photolithography;
(Iii) a conductive printed mesh composite sheet obtained by pattern-printing a conductive paint on a transparent film;
(Iv) A transparent conductor in which a transparent conductive layer such as a silver thin film or an ITO thin film is laminated on a transparent film.

<Others>
In the near-infrared absorption filter of the present invention, at least one of the layers (A) to (D), that is, the surface layer (A), the base film (B), the near-infrared absorption layer (C), or the adhesive layer (D). It is also a preferred embodiment that one layer contains at least one dye having absorption in the visible light region. For example, since a plasma display emits so-called neon orange light centered around a wavelength of about 600 nm, there is a disadvantage that a bright red color cannot be obtained by mixing an orange color with a red color. This defect can be eliminated by blending a dye having a maximum absorption in a wavelength range of 550 to 620 nm (neon cut dye) into any one of the layers (A) to (D). Such a dye preferably has a sharp absorption at a wavelength of 550 nm to 620 nm, preferably at a wavelength of 570 to 600 nm.

  The transmittance of the near-infrared absorption filter at the maximum absorption wavelength of the neon cut dye is preferably 50% or less, and more preferably 30% or less. When the transmittance in this region is high, neon orange light emitted from the plasma display is not sufficiently absorbed, and color purity may be reduced. In addition, when the absorption in this region is wide, the balance of R, G, and B light may be lost and the contrast may be lowered.

  Specific examples of neon cut dyes include cyanine, squarylium, azomethine, xanthene, oxonol, azo, phthalocyanine, quinone, azulenium, pyrylium, croconium, dithiol metal complex, pyromethene compound And various compounds. Among these, squarylium-based and cyanine-based compounds are preferable because neon orange light has sharp absorption. Although the layer containing a neon cut pigment is not particularly limited, it is a preferred embodiment to be blended in the near infrared absorbing layer (C) together with the near infrared absorbing pigment.

  As the color tone of the near-infrared absorption filter, when expressed in the Lab color system, the a value is preferably -10.0 to +10.0, and the b value is preferably -10.0 to +10.0. If it is this range, even if it installs in the front surface of a plasma display, it becomes a natural color and is preferable.

  The thickness of the near-infrared absorbing filter is not particularly limited and can be set arbitrarily according to market demands, but the total thickness of the (A) layer to (D) layer is preferably 0.05 to 0.2 mm. If the total thickness is too small, the handleability of the near-infrared absorbing filter is deteriorated, which is not preferable. On the other hand, if the total thickness is too large, the handling property of the near-infrared absorbing filter and the workability when sticking to a plasma display are deteriorated, which is not preferable. Moreover, it is desirable to make it into the said upper limit or less also from the surface of the market thin film demand.

  That is, from the viewpoint of the handleability of the near-infrared absorption filter and the workability when sticking to a plasma display, etc., there is a demand from the market to make the near-infrared absorption filter thinner. Since multifunctionalization was achieved by bonding two or more functional films formed with layers, the total thickness of the filter exceeded 0.2 mm. In contrast, in the present invention, by integrating the base film, it was possible for the first time to meet the market demand for thinning the near-infrared absorption filter while ensuring high functionality.

  In the near-infrared absorption filter of the present invention, the order of forming each layer is not particularly limited. For example, after the adhesion modified layer and the surface layer (A) are first formed on the base film (B), [ The formation of the near-infrared absorbing layer (C) may be performed via the easy-adhesion layer formation, and after the formation of the adhesion-modified layer and the near-infrared absorbing layer (C) first, the surface layer (A) is formed, etc. Any order can be employed. In addition to sequentially applying the coating liquid for forming each layer, a plurality of coating liquids can be simultaneously applied using a multilayer coater. However, it is desirable to form the adhesive layer (D) after all of the layers (A) to (D) are formed.

  The near-infrared absorption filter of the present invention is a preferred embodiment that is directly attached to the plasma display panel via the adhesive layer (D), but does not have the adhesive layer (D) or the adhesive layer (D). Of course, it is also possible to stick the thing in which the translucent sheet | seat (E) is laminated | stacked through a plasma display panel. The fixing method in this case is not particularly limited, but it is recommended to use a conventionally known optical adhesive or pressure-sensitive adhesive. In the case of a near-infrared absorbing filter having no adhesive layer (D), the translucent sheet (E) is laminated on the near-infrared absorbing layer (C) via the adhesive layer (D). In the case of the near infrared absorption filter, the translucent sheet (E) surface is adhered to the surface of the plasma display panel.

  Hereinafter, the present invention will be described in detail based on examples. However, the following examples are not intended to limit the present invention, and all modifications made without departing from the spirit of the preceding and following descriptions are included in the technical scope of the present invention. In addition, the evaluation method employ | adopted by the present Example is as follows.

(1) Light transmittance Using a spectrophotometer ("U-3500 type" manufactured by Hitachi, Ltd.), a light having a specific wavelength is irradiated from the near-infrared absorbing layer (C) side within a wavelength range of 200 to 1100 nm. The air permeability is measured as a reference value (blank). The transmittance in the near-infrared region is the average value of the transmittance of wavelengths: 900 to 110 nm, the transmittance in the neon light (neon orange light) region is the average value of the transmittance in the 570 to 600 nm, and in the visible light region. The transmittance is evaluated by the average value of the transmittance at a wavelength of 450 to 700 nm, and the ultraviolet transmittance is a transmittance of 380 nm.

(2) Color tone Color tone is measured by using a color difference meter (“ZE-2000” manufactured by Nippon Denshoku Industries Co., Ltd.), using standard light as D65 light source, viewing angle of 10 degrees, and near infrared absorption layer (C) side. This is performed by irradiating light, and the a value and b value of the Lab display system are obtained.

(3) Stability over time After the near-infrared absorbing filter is left in an atmosphere of 60 ° C. and 95% humidity for 500 hours, the light transmittance of (1) and the color tone of (2) are measured.

The average amount of transmittance in the near-infrared region and the amount of change before and after aging of the average value of transmittance in the visible light region are obtained from the following formula (a), and ranked according to the following criteria.
A: Change in transmittance is less than 5%;
○: The change in transmittance is 5% or more and less than 10%;
Δ: The change in transmittance is 10% or more and less than 20%;
X: The change in transmittance is 20% or more;
Change amount (%) = (| transmittance before processing−transmittance after processing | / transmittance before processing) × 100
(A).

Further, the amount of change in color tone defined by the following formula (b) before and after the aging process is obtained, and ranking is performed according to the following criteria.
A: Change in color tone is less than 1;
○: The change in color tone is 1 or more and less than 2;
Δ: The change in color tone is 2 or more and less than 4;
×: Color change amount is 4 or more change amount = [(a value before processing−a value after processing) ² + (b value before processing−b value after processing) ² ] ^1/2
(B).

(4) Weather resistance About the test sample of a near-infrared absorption filter, an accelerated weather resistance test is performed and evaluated under the following conditions. An irradiation test using an ultraviolet auto fade meter (“FAL-AU-H-BR” manufactured by Suga Test Instruments Co., Ltd.) is performed at a black panel temperature of 63 ° C. for 192 hours, and the maximum absorption in the near infrared region of the test sample before and after the test is performed. Measure transmittance at wavelength. The transmittance before the test T, the transmittance after the test and T _1, these measurements, determine the near infrared absorptivity residual ratio R (%) by the following equation (c). This evaluation is carried out by a method in which a test sample is attached to a SUS plate having a thickness of 2 mm through an adhesive layer (D) and irradiated with ultraviolet rays from the surface layer (A) side.
R (%) = T / T ₁ × 100 (c).

(5) Reflectance of surface layer (A) Using a spectrophotometer ("U-3500 type" manufactured by Hitachi, Ltd.), the 5 ° specular reflection on the surface layer (A) side is measured according to JIS R 3106. The minimum reflectance at a wavelength of 380 to 700 nm is obtained. About the sample of the comparative example which does not laminate | stack a surface layer (A), the surface of a base film (B) is measured.

(6) Surface hardness The surface of the surface layer (A) is evaluated by pencil scratch hardness. The sample is evaluated after conditioning for 2 hours under conditions of temperature: 25 ° C. and relative humidity: 60%. Pencil scratch hardness is measured according to JIS K 5400 using a test pencil specified by JIS S 6006. The pencil hardness of the evaluation result is that of a pencil in which no scratch is recognized at a load of 9.8 N. About the sample of the comparative example which does not laminate | stack a surface layer (A), the surface of a base film (B) is measured.

(7) Interference fringes A near-infrared absorption filter is cut into a size of 10 cm × 15 cm to obtain a measurement sample. The measurement sample is attached to black glossy paper through the adhesive layer (D). With the near-infrared absorption filter surface of this sticking body as the upper surface, the reflected light is visually observed obliquely from above, using a three-wavelength daylight white (“Palook FL 15EX-N 15W” manufactured by Matsushita Electric Works, Ltd.) as a light source. The observation results are ranked according to the following criteria: Note that the observation is performed by five people who are familiar with this evaluation, and the highest rank is the evaluation rank.If the two ranks have the same number, The center of the rank divided into three is adopted, for example, if ◎ and ○ are two each and △ is one, ○ is ◎, if ◎ is one and ○ and △ are two each, ○ Adopt each one.
◎: Iridescent colors are not seen from any angle;
○: A slight iris color can be seen at certain angles;
Δ: A slight iris color is observed;
X: A clear iris-like color is observed.

(8) Adhesiveness of surface layer (A) and near-infrared absorbing layer (C) to base film (B) Adhesiveness is determined by a test method according to the provisions of 8.5.1 of JIS K 5400. That is, 100 grid-like cut scratches reaching the base film (B) from both surfaces are attached using a cutter guide with a gap interval of 2 mm, and cellophane adhesive tape (Nichiban Co., Ltd. “No. 405”, 24 mm width) Is attached to the grid-like cut scratched surface, rubbed with an acrylic plate (“SUMIPEX” manufactured by Sumitomo Chemical Co., Ltd.), and then adhered to the surface. Use d) to determine the adhesion (%). In addition, what peeled off partially by one square shall be the peeled square.
Adhesiveness (%) = (1−number of cells peeled / number of cells evaluated) × 100 (d).

Experiment 1 (Preparation of near infrared absorption filter)
Example 1
<Preparation of base film (B)>
(1) Preparation of UV Absorber-Containing Masterbatch Pellet Dried 2,2 ′-(1,4-phenylene) bis (4H-3,1-benzoxazinon-4-one (“CYASRB UV-” manufactured by Siatech) 3638 ", UV absorber): 10 parts by mass and polyethylene terephthalate (PET) resin containing no particles (" ME553 "manufactured by Toyobo Co., Ltd.): 90 parts by mass, and using a kneading extruder, master batch pellets were mixed. The extrusion temperature at this time was 285 ° C., and the extrusion time was 7 minutes.

(2) Preparation of coating solution for forming an adhesion modified layer Dimethyl terephthalate: 95 parts by mass, dimethyl isophthalate: 95 parts by mass, ethylene glycol: 97 parts by mass, neopentyl glycol: 70 parts by mass, zinc acetate: 0.1 parts by mass Parts and antimony trioxide: 0.1 parts by mass were charged in a reaction vessel, and a transesterification reaction was performed at 180 ° C. over 3 hours. Next, after adding 12.1 mass parts of 5-sodium sulfoisophthalic acid and performing esterification reaction at 240 degreeC over 1 hour, polycondensation reaction was performed and polyester resin was obtained.

  Aqueous dispersion of the polyester resin: 40 parts by mass, 44% by mass of hydroxybis (lactato) titanium solution (“TC310” manufactured by Matsumoto Pharmaceutical Co., Ltd.): 18 parts by mass, water: 150 parts by mass, and isopropanol: 100 parts by mass In addition, 1% by mass of an anionic surfactant with respect to the coating liquid, an aqueous dispersion of spherical colloidal silica fine particles, “Cataloid SI80P” (average particle size: 80 nm) manufactured by Nippon Shokubai Kasei Co., Ltd., and silica with respect to the solid content of the resin It added so that it might become 2 mass%, and it was set as the coating liquid.

(3) Preparation of coating solution for forming an easy adhesion layer Dimethyl terephthalate: 95 parts by mass, dimethyl isophthalate: 95 parts by mass, ethylene glycol: 35 parts by mass, neopentyl glycol: 145 parts by mass, zinc acetate: 0.1 parts by mass And antimony trioxide: 0.1 mass part was prepared to reaction container, and transesterification was performed at 180 degreeC over 3 hours. Next, 6.0 parts by mass of 5-sodium sulfoisophthalic acid was added, an esterification reaction was performed at 240 ° C. for 1 hour, and then a polycondensation reaction was performed to obtain a polyester resin.

  30% by mass aqueous dispersion of the obtained polyester resin: 6.7 parts by mass, 20% by mass aqueous solution of a self-crosslinking polyurethane resin containing an isocyanate group blocked with sodium bisulfite (“Elastron H -3 "): 40 parts by mass, elastron catalyst (Cat 64): 0.5 parts by mass, water: 47.8 parts by mass and isopropanol: 5 parts by mass, and further 1% by mass of an anionic surfactant, 5% by mass of spherical colloidal silica particles (“Snowtex OL” manufactured by Nissan Chemical Industries, Ltd.) was added to prepare a coating solution.

(4) Film formation of base film (B) Pellets containing no particles of PET having an intrinsic viscosity of 0.62 dl / g (“ME553” manufactured by Toyobo Co., Ltd.): 90 parts by mass, prepared in (1) above The master batch pellets: 10 parts by mass were dried at 135 ° C. under reduced pressure (1 Torr) for 6 hours, and then supplied to the extruder. The resin temperature from the extruder melt section, kneading section, polymer tube, gear pump, and filter was 280 ° C., and the polymer tube thereafter was 275 ° C., and the sheet was extruded from the die into a sheet shape. In addition, these PET was filtered using the filter medium (nominal filtration accuracy: 95% of particles having a nominal filtration accuracy of 10 μm or more) at the melting stage. In addition, the resin temperature of the flat die was set to 275 ° C.

  The melt-extruded film-like resin is wound around a casting drum (roll diameter: 400 mm, Ra: 0.1 μm or less) having a surface temperature of 30 ° C. by using an electrostatic application casting method, and is cooled and solidified to obtain an unstretched film. . The discharge rate at this time was 48 kg / hr, and the obtained unstretched film had a width of 300 mm and a thickness of 1400 μm.

  Next, the unstretched film is heated to 100 ° C. using a heated roll group and an infrared heater, and then stretched 3.5 times in the longitudinal direction (running direction) with a roll group having a peripheral speed difference (longitudinal direction). Stretching process) A uniaxially oriented film was obtained. In addition, about all the rolls used at the time of film manufacture, the surface roughness of the roll was managed by Ra and 0.1 micrometer or less, and the roll cleaner was installed in the roll and cooling roll which are located in the preheating inlet of an extending process. The roll diameter in the longitudinal stretching process was 150 mm, and a technique was adopted in which the film was brought into close contact with the roll by means of a suction roll, electrostatic close contact, and part nip contact apparatus.

A coating solution for forming an adhesion-modified layer and a coating solution for forming an easy-adhesion layer, which have been subjected to microfiltration with a felt type polypropylene filter medium having a filtration particle size (initial filtration efficiency of 95%), are each converted into the above uniaxially oriented film by a reverse roll method. It was applied to each side. Subsequently, the end of the film is gripped with a clip, guided to a hot air zone heated to 130 ° C., dried, stretched 4.0 times in the film width direction, and heat treated at 230 ° C. for 5 seconds. A base film (B) on which an adhesion modifying layer and an easy adhesion layer were laminated was obtained by performing a relaxation treatment of 3% in the width direction. The thickness of the obtained base film (B) was 100 μm, and the easy-adhesion layer was 0.01 g / m ² per side in an application amount after drying.

<Formation of surface layer (A)>
An ultraviolet curable hard coat paint ("Seika Beam EXF-01B" manufactured by Dainichi Seika Co., Ltd.) is applied to the surface of the adhesion modified layer of the base film (B) by a reverse coating method so that the film thickness after drying becomes 5 μm. It was applied to. Next, after drying the solvent, ultraviolet rays of 800 mJ / cm ² were irradiated with a high-pressure mercury lamp to cure the resin in the paint, thereby forming a hard coat layer.

  Next, after preparing the coating liquid which consists of partial hydrolysis-condensation product of γ-aminopropyltrimethoxysilane: 5 parts by mass, methanol: 30 parts by mass, ethanol: 30 parts by mass, and isopropanol: 35 parts by mass. The film was coated on the surface of the hard coat layer so as to have a film thickness of 0.02 μm, and dried at 140 ° C. for 20 seconds to form a high refractive index layer.

  Next, 50 parts by mass of ethanol, 20 parts by mass of water, and 4 parts by mass of hydrochloric acid were added to 24 parts by mass of tetraethoxysilane to hydrolyze tetraethoxysilane to prepare a coating solution. This coating solution was applied to the surface of the high refractive index layer so that the film thickness after drying was 0.09 μm, and dried at 140 ° C. for 1 minute to form a low refractive index layer.

Further, perfluorocarbon composed of C ₃ F ₇ — (OC ₃ F ₆ ) ₃₄ —O— (CF ₂ ) ₂ —C ₂ H ₄ —O—CH ₂ Si (OCH ₃ ) _{3 is} formed on the surface of the low refractive index layer. A coating solution obtained by diluting a polyether group-containing silane coupling agent to 0.5% by mass with perfluorohexane was applied and dried at 120 ° C. for 1 minute to form an antifouling layer having a thickness of 8 nm. .

  Thereby, the surface layer (A) laminated | stacked in order of the hard-coat layer / high-refractive-index layer / low-refractive-index layer / antifouling layer was formed in the adhesion modification layer surface of the base film (B).

<Formation of near-infrared absorbing layer (C)>
Solvent, resin, dye and surfactant are mixed in the composition shown in Table 1, and the dye and resin are dissolved under heating (40 ° C.), and then the undissolved material is removed with a filter having a nominal filtration accuracy of 1 μm. A coating solution was prepared. The obtained coating solution had a solid content concentration of 17% by mass and a viscosity of 40 cps.

The coating solution was applied to the surface of the easy-adhesion layer of the base film (B) on which the surface layer (A) was formed so that the coating amount after drying was 8.5 g / m ² . The application was performed by rotating a slanted gravure roll having a diameter of 60 cm in reverse. Then, 40 ° C., 5 m / sec wind for 20 seconds (first drying step), 150 ° C., 20 m / sec wind for 20 seconds (second drying step), and 90 ° C., 20 m / sec wind for 10 seconds. It was allowed to pass for 2 seconds (cooling step) and dried to produce a near infrared absorption filter.

<Formation of adhesive layer (D)>
From the near-infrared absorbing layer (C) of the near-infrared absorbing filter, n-butyl acrylate (78.4% by mass), 2-ethylhexyl acrylate (19.6% by mass), and acrylic acid (2% by mass) A transparent pressure-sensitive adhesive, which is an acrylic ester copolymer, was laminated by a comma coater method so that the film thickness after drying was 0.025 mm. Furthermore, a silicone-treated PET separator film having a thickness of 0.038 mm was laminated on the surface to obtain a composite of a near-infrared absorption filter having a pressure-sensitive adhesive layer (D) and a separator film.

  Table 2 shows the results of the above evaluations on the near infrared absorption filter. Evaluations other than the weather resistance test were performed on a near infrared absorption filter not provided with an adhesive layer (D), and the weather resistance test was performed on a near infrared absorption filter provided with an adhesive layer (D). As can be seen from Table 2, the obtained near-infrared absorption filter has large absorption in the near-infrared region and neon light region, and also has high transmittance in the visible light region. Moreover, the occurrence of interference fringes is also suppressed. Furthermore, the absorption in the ultraviolet region is extremely large, and the stability over time (transmittance characteristics, color tone) and weather resistance are excellent. The appearance of the filter was also good.

  Furthermore, antifouling property evaluation was performed about the surface layer (A) of the near-infrared absorption filter. The antifouling property was evaluated based on the wipeability of an oil-based pen and the wipeability of a fingerprint. The wiping property of the oil-based pen is to draw a line on the surface layer (A) surface with an oil-based pen, and the wiping property of the fingerprint is a non-woven fabric made of cellulose (Asahi Kasei). The product was wiped with “Bencotton M-3”), and the ease of removal was visually determined. Both were completely wiped off.

  Moreover, the total thickness of the (A) layer to the (D) layer of the near-infrared absorption filter obtained in this example is 0.14 mm, and is very thin and possesses the excellent characteristics as described above. And if the separator film of the said composite_body | complex is peeled, it can stick easily to to-be-adhered bodies, such as a plasma display, using the adhesiveness of an adhesion layer (D). As described above, the near-infrared absorbing filter has a thinner thickness than a conventionally known one, and thus has excellent workability for sticking.

Example 2
The surface layer was the same as in Example 1 except that the ultraviolet absorber was changed to a polymeric ultraviolet absorber ("Novapex U-110" manufactured by Mitsubishi Chemical Corporation) and the blending amount was 20 parts by mass. A near-infrared absorption filter having (A), a base film (B) and a near-infrared absorption layer (C) was produced. Furthermore, a near-infrared absorption filter having an adhesive layer (D) was also produced using this near-infrared absorption filter in the same manner as in Example 1. Table 2 shows the evaluation results of these near-infrared absorption filters. As shown in Table 2, it has the same characteristics as the near-infrared absorption filter of Example 1. Moreover, although the same antifouling evaluation as Example 1 was performed, both the wiping property of the oil-based pen and the wiping property of the fingerprint were good.

Example 3
As a coating solution for forming an adhesion-modified layer of the base film (B), an aqueous dispersion of the same polyester resin used in Example 1: 48 parts by mass, a 44% by mass solution of hydroxybis (lactato) titanium (Matsumoto "TC310" manufactured by Pharmaceutical Co., Ltd.): 15 parts by mass, water: 150 parts by mass, and isopropanol: 100 parts by mass, and an anionic surfactant in an amount of 1% by mass with respect to the coating solution, an aqueous dispersion of spherical colloidal silica fine particles (Cataloid SI80P manufactured by Nippon Shokuhin Kasei Co., Ltd., average particle size: 80 nm) was added so that silica was 2% by mass with respect to the resin solid content.

  Near-infrared absorption having a surface layer (A), a base film (B), and a near-infrared absorbing layer (C) in the same manner as in Example 1 except that the coating solution for forming an adhesion-modified layer is changed to the above. A filter was produced. Furthermore, a near-infrared absorption filter having an adhesive layer (D) was also produced using this near-infrared absorption filter in the same manner as in Example 1. Table 2 shows the evaluation results of these near-infrared absorption filters. As shown in Table 2, it has the same characteristics as the near-infrared absorption filter of Example 1. Moreover, although the same antifouling evaluation as Example 1 was performed, both the wiping property of the oil-based pen and the wiping property of the fingerprint were good.

Example 4
As a coating solution for forming an adhesion-modified layer of the base film (B), an aqueous dispersion of the same polyester resin used in Example 1: 12 parts by mass, 80 of diisopropoxybis (triethanolaminato) titanium Mass% solution (“TC400” manufactured by Matsumoto Pharmaceutical Co., Ltd.): 17 parts by mass, water: 150 parts by mass, and isopropanol: 100 parts by mass are mixed, and an anionic surfactant is 1% by mass with respect to the coating liquid, spherical colloidal silica. An aqueous dispersion of fine particles (“Cataloid SI80P” manufactured by Nippon Shokubai Kasei Co., Ltd., average particle size: 80 nm) was added so that silica was 2% by mass with respect to the resin solid content.

  Near-infrared absorption having a surface layer (A), a base film (B), and a near-infrared absorbing layer (C) in the same manner as in Example 1 except that the coating solution for forming an adhesion-modified layer is changed to the above. A filter was produced. Furthermore, a near-infrared absorption filter having an adhesive layer (D) was also produced using this near-infrared absorption filter in the same manner as in Example 1. Table 2 shows the evaluation results of these near-infrared absorption filters. As shown in Table 2, it has the same characteristics as the near-infrared absorption filter of Example 1. Moreover, although the same antifouling evaluation as Example 1 was performed, both the wiping property of the oil-based pen and the wiping property of the fingerprint were good.

Example 5
As the coating solution for forming the adhesion-modified layer of the base film (B), the same polyester resin aqueous dispersion as used in Example 1: 32 parts by mass, zirconium acetate: 10 parts by mass, water: 150 parts by mass and 1 part by mass of isopropanol: 100 parts by mass and further anionic surfactant) based on the coating liquid, aqueous dispersion of spherical colloidal silica fine particles (“Cataloid SI80P” manufactured by Nippon Shokubai Kasei Co., Ltd., average particle size: 80 nm) Was added such that silica was 2% by mass with respect to the resin solid content.

  Near-infrared absorption having a surface layer (A), a base film (B), and a near-infrared absorbing layer (C) in the same manner as in Example 1 except that the coating solution for forming an adhesion-modified layer is changed to the above. A filter was produced. Furthermore, a near-infrared absorption filter having an adhesive layer (D) was also produced using this near-infrared absorption filter in the same manner as in Example 1. Table 2 shows the evaluation results of these near-infrared absorption filters. As shown in Table 2, it has the same characteristics as the near-infrared absorption filter of Example 1. Moreover, although the same antifouling evaluation as Example 1 was performed, both the wiping property of the oil-based pen and the wiping property of the fingerprint were good.

Example 6
Other than the easy adhesion layer on the surface of the base film (B) on the near infrared absorption layer (C) lamination side, an adhesion modified layer was formed (that is, an adhesion modified layer was formed on both sides) Produced the near-infrared absorption filter which has the surface layer (A), the base film (B), and the near-infrared absorption layer (C) like Example 1. Furthermore, a near-infrared absorption filter having an adhesive layer (D) was also produced using this near-infrared absorption filter in the same manner as in Example 1. Table 2 shows the evaluation results of these near-infrared absorption filters. As shown in Table 2, it has the same characteristics as the near-infrared absorption filter of Example 1. Moreover, although the same antifouling evaluation as Example 1 was performed, both the wiping property of the oil-based pen and the wiping property of the fingerprint were good.

Comparative Example 1
The surface layer (A), the base film (B), and the base film (B) are the same as in Example 1 except that the ultraviolet absorber is not added to the base film (B), and the adhesion-modified layer and the easy-adhesion layer are not formed. A near-infrared absorption filter having a near-infrared absorption layer (C) was produced. Furthermore, a near-infrared absorption filter having an adhesive layer (D) was also produced using this near-infrared absorption filter in the same manner as in Example 1. Table 3 shows the evaluation results of these near infrared absorption filters. Since these near-infrared absorption filters are not formed with an adhesion modified layer having a function of suppressing the generation of interference fringes, interference fringes are generated as shown in Table 3. Moreover, since the ultraviolet ray transmittance is high, the near-infrared absorbing dye is greatly deteriorated in ultraviolet ray and has poor weather resistance. Furthermore, adhesion between the surface layer (A) and the base film (B) and between the base film (B) and the near-infrared absorbing layer (C) due to the absence of an adhesion-modifying layer or an easy-adhesion layer. The properties are inferior to those of the near-infrared absorption filter of Example 1.

Comparative Example 2
A near-infrared absorbing filter having a base film (B) and a near-infrared absorbing layer (C) was produced in the same manner as in Example 1 except that the surface layer (A) was not formed. Furthermore, a near-infrared absorption filter having an adhesive layer (D) was also produced using this near-infrared absorption filter in the same manner as in Example 1. Table 3 shows the evaluation results of these near infrared absorption filters. Since these near-infrared absorption filters do not have the surface layer (A), the surface reflectance and the surface hardness are inferior as shown in Table 3. Further, the same antifouling evaluation as in Example 1 was performed, but lines and fingerprints drawn with an oil pen remained after wiping.

Comparative Example 3
A filter having a surface layer (A) and a base film (B) was produced in the same manner as in Example 1 except that the near-infrared absorbing layer (C) was not formed. Furthermore, using this filter, a filter having an adhesive layer (D) was also produced in the same manner as in Example 1. Table 3 shows the evaluation results of these filters. Since these filters do not have the near-infrared absorbing layer (C), the transmittance in the near-infrared region is high as shown in Table 3, and they do not have a basic function as a near-infrared absorbing filter. Further, it does not have a color tone correction function (neon light absorption capability). Therefore, the aging stability test and the weather resistance test were stopped.

Comparative Example 4
The surface layer (A), the base film (B), and the near-infrared absorbing layer (C) were formed in the same manner as in Example 1 except that the base film (B) was not formed with an adhesion-modified layer and an easy-adhesion layer. The near-infrared absorption filter which has was produced. Furthermore, a near-infrared absorption filter having an adhesive layer (D) was also produced using this near-infrared absorption filter in the same manner as in Example 1. Table 3 shows the evaluation results of these near infrared absorption filters. Since these near-infrared absorption filters do not have an adhesion modified layer having a function of suppressing the generation of interference fringes, interference fringes are generated. Furthermore, adhesion between the surface layer (A) and the base film (B) and between the base film (B) and the near-infrared absorbing layer (C) due to the absence of an adhesion-modifying layer or an easy-adhesion layer. The properties are inferior to those of the near-infrared absorption filter of Example 1.

Comparative Example 5
The base film (B) was replaced with an easy-adhesion layer on the surface layer (A) lamination side surface (that is, an easy-adhesion layer was formed on both sides). In the same manner as in Example 1, a near-infrared absorption filter having a surface layer (A), a base film (B), and a near-infrared absorption layer (C) was produced. Furthermore, a near-infrared absorption filter having an adhesive layer (D) was also produced using this near-infrared absorption filter in the same manner as in Example 1. Table 3 shows the evaluation results of these near infrared absorption filters. Since this near-infrared absorption filter is not formed with an adhesion modified layer having a function of suppressing the generation of interference fringes, interference fringes are generated as shown in Table 3.

Experiment 2 (Production of plasma display panel)
Experiment 2-1
Remove the front panel of the plasma display panel ("PDS4211J-H" manufactured by Fujitsu Ltd.), and the near-infrared absorption filter produced in Examples 1 to 6 and Comparative Examples 1 to 5 [with an adhesive layer (D)] It stuck through the adhesion layer (D) and performed various functional evaluation. In the plasma display panel using the near-infrared absorption filter of Examples 1 to 6, the following effects could be confirmed.
(1) Since the antireflection property of the surface is given, the reflection of outside light is suppressed, and the reflection of the fluorescent lamp used for the interior lighting is reduced.
(2) Since the surface hardness is high, it is difficult to be scratched.
(3) Since antifouling property is given, even if it touches with a hand and a fingerprint is attached, it was easily wiped off.
(4) Since the generation of interference fringes is suppressed, no deterioration in image quality due to the interference fringes was observed.
(5) Since it has neon cut performance and has improved color tone, color reproducibility has been improved. Specifically, the red with orange color turned into pure red, the greenish blue with bright blue, and the yellowish white turned into pure white.
(6) Since a near-infrared absorbing effect is given, malfunction of an infrared remote control device installed in the vicinity can be prevented.
(7) Since the weather resistance and stability over time are excellent, the function (6) was stable even after long-term use.

  On the other hand, in the plasma display panel using each near-infrared absorption filter of the comparative example, the following problems were observed. In the case of using the near-infrared absorption filter of Comparative Example 1, since the generation of interference fringes was not suppressed, the image quality of the image was deteriorated due to the interference fringes. Moreover, since the weather resistance is inferior, the frequency of malfunction of the infrared remote control device installed in the vicinity has increased due to long-term use.

  The one using the near-infrared absorption filter of Comparative Example 2 had high surface reflectance, and thus high external light reflection, and there was a reflection of a fluorescent lamp used for room lighting, and the visibility of the screen was low. Moreover, since the surface hardness was low, the surface was easily scratched, and the antifouling property was not imparted, the wiping property of fingerprints adhered when touched by hand was inferior.

  Since the near-infrared absorption filter of Comparative Example 3 did not have near-infrared absorption capability, malfunction of an infrared remote control device installed in the vicinity occurred. Further, since the neon cut property was not imparted, the color reproducibility of the image was inferior.

  In the comparative examples 4 and 5 using the near-infrared absorption filter, the generation of interference fringes was not suppressed, so that the image quality of the image was deteriorated due to the interference fringes.

  Moreover, what used the near-infrared absorption filter of the comparative examples 1 and 4 is the adhesiveness of the interface of a base film (B) and a functional expression layer [surface layer (A) and near-infrared absorption layer (C)]. Thus, partial peeling of the interface occurred due to long-term use, and the image quality was deteriorated.

  Furthermore, since the near-infrared absorption filters of Examples 1 to 6 are thin and have an adhesive layer combined, when the filter is attached in a state where the surface of the plasma display panel is moistened with isopropanol, bubbles are not formed. It was able to stick cleanly while suppressing mixing, and had extremely good workability.

Experiment 2-2
The near-infrared absorption filter obtained in Examples 1 to 6 [without the adhesive layer (D)] was used with the surface of the near-infrared absorption layer (C) as the plasma display panel side, and a plasma display panel (manufactured by Fujitsu Ltd. “ A front panel of “PDS4211J-H” was attached using an optical adhesive, and various functions were evaluated. Results similar to those in Experiment 2-1 were obtained.

Experiment 3 (Preparation of near-infrared absorption filter with electromagnetic wave blocking function)
Conductive mesh [translucent sheet (E) having an electromagnetic wave absorbing function] through the adhesive layer (D) on the near-infrared absorption filter [adhesive layer (D) provided] obtained in Examples 1 to 6 Affixed. The conductive mesh is obtained by plating nickel and copper by an electroless plating method on a mesh in which fibers having a wire diameter of 0.03 mm are knitted in length and width at a density of 135 per 2.54 cm.

  The front panel of the plasma display panel ("PDS4211J-H" manufactured by Fujitsu Ltd.) was removed, and each near-infrared absorption filter having a conductive mesh was adhered using an adhesive, and various functions were evaluated. In addition to the effects confirmed in Experiment 2-1, it was confirmed that an electromagnetic wave shielding effect could also be exhibited.

Claims (17)

A near-infrared absorption filter in which a surface layer (A) having an antireflection function, a base film (B), and a near-infrared absorption layer (C) are sequentially laminated,
The surface layer (A) has a hard coat layer made of a resin having two or more (meth) acryloyl groups in the molecule on the base film (B) side,
The base film (B) includes a polyester film and an adhesion modified layer as constituent elements,
The adhesion modification layer includes an aqueous polyester resin and at least one of a water-soluble titanium chelate compound, a water-soluble titanium acylate compound, a water-soluble zirconium chelate compound, or a water-soluble zirconium acylate compound. It is formed from a liquid and is located between the surface layer (A) and the polyester film,
The near-infrared absorption layer (C) contains a pigment having a maximum absorption in a near-infrared absorption region having a wavelength of 800 to 1000 nm.   The near-infrared absorbing filter according to claim 1, wherein an adhesive layer (D) made of a transparent adhesive is laminated on the near-infrared absorbing layer (C) side surface.   The near-infrared absorption filter according to claim 2, wherein the total thickness of the layers (A) to (D) is 0.05 to 0.2 mm.   The near-infrared absorption filter according to any one of claims 1 to 3, wherein the surface layer (A) has a pencil hardness of 1H or more.   The near-infrared absorption filter according to any one of claims 2 to 4, wherein at least one of the layers (A) to (D) contains at least one dye having absorption in the visible light region.   The near-infrared absorbing filter according to claim 1, wherein the polyester film is a biaxially oriented polyester film. The polyester film is substantially free of particles.
The near-infrared absorption filter according to any one of the above.   The near-infrared absorbing filter according to claim 1, wherein the polyester film contains an ultraviolet absorber.   The near-infrared absorption filter according to claim 8, wherein the decomposition start temperature of the ultraviolet absorber is 290 ° C or higher.   The coating liquid for forming the adhesion modified layer is composed of at least an aqueous polyester resin and a water-soluble titanium chelate compound, a water-soluble titanium acylate compound, a water-soluble zirconium chelate compound, or a water-soluble zirconium acylate compound. The near infrared absorption filter according to any one of claims 1 to 9, wherein a mixing ratio (mass ratio) with one kind is 90/10 to 5/95.   The near-infrared absorption filter according to claim 1, wherein the adhesion modified layer contains particles.   The translucent sheet | seat (E) which has an electromagnetic wave absorption function is laminated | stacked on the opposite surface of the base film (B) lamination | stacking surface of a near-infrared absorption layer (C), Any one of Claims 1-11 The near-infrared absorption filter according to crab.   The translucent sheet | seat (E) which has an electromagnetic wave absorption function is laminated | stacked on the surface opposite to the near-infrared absorption layer (C) lamination | stacking surface of the adhesion layer (D). The near-infrared absorbing filter described in 1.   The near-infrared absorption filter according to any one of claims 1 to 13, wherein the near-infrared absorption layer (C) contains a surfactant.   The aqueous polyester resin contained in the aqueous coating liquid for forming the adhesion modified layer was synthesized using an acid component containing 1 to 10 mol% of a dicarboxylic acid having a sulfonic acid group in the total acid component. The near-infrared absorption filter according to claim 1, wherein the near-infrared absorption filter is used.   The near-infrared absorption filter according to claim 1, wherein the solvent used in the aqueous coating liquid for forming the adhesion-modified layer is water or an aqueous solution containing less than 50% by mass of alcohol. .   A plasma display panel comprising the near-infrared absorption filter according to claim 1.