JP2006184532A - Near-infrared absorption film and near-infrared absorption filter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a near-infrared absorption film and a near-infrared absorption filter which have a high transmittance in the visible light region and a low transmittance in the near-infrared region, undergo little change in the quality over time at high temperature and high humidity, and excel in light resistance. <P>SOLUTION: The near-infrared absorption film is obtained by laminating, on a transparent base film, a near-infrared absorption layer mainly made up of two or more near-infrared absorbing dyes including a diimmonium salt compound and a resin, wherein the near-infrared absorption film has a transmittance at 400 nm wavelength of ≤30%. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an optical filter that absorbs near-infrared rays, and particularly to a near-infrared absorbing film suitable as a filter for display. Specifically, the transmittance in the visible light region is high, and the change with time of quality under high temperature and high humidity is small. And it is related with the near-infrared absorption film excellent in light resistance.

An optical filter having near-infrared absorption ability has a property of blocking near-infrared light and allowing visible light to pass therethrough, and is used in various applications.
In recent years, plasma displays have attracted attention as thin large-screen displays. However, there is a problem that electronic devices using a near-infrared remote controller may malfunction due to near infrared rays emitted from the plasma display. An infrared absorbing film is placed and used as a near infrared absorbing filter.

As a near-infrared absorption filter, (1) a filter containing metal ions such as copper or iron on phosphoric acid glass, and (2) a layer having a different refractive index is laminated, and a specific wavelength is set by causing interference with transmitted light. There are proposed an interference filter to transmit, (3) an acrylic resin filter containing copper ions in a copolymer, and (4) a filter in which a layer in which a pigment is dispersed or dissolved in a resin is laminated.
Among these, the filter (4) has good workability and productivity, and has a relatively large degree of freedom in optical design, and various methods have been proposed (for example, see Patent Documents 1 to 9).
JP 2002-82219 A JP 2002-138203 A JP 2002-214427 A JP 2002-264278 A JP 2002-303720 A JP 2002-333517 A JP 2003-82302 A Japanese Patent Laid-Open No. 2003-96040 JP 2003-114323 A

  Some of these methods have the ability to sufficiently block near-infrared rays emitted from a plasma display and have no quality change with time even when used indoors for a long time. However, in a severe environment installed outdoors, sunlight is directly applied to the display, and the near-infrared absorption filter may be discolored.

As a measure for improving the light resistance of the near-infrared absorbing film, a method of laminating an ultraviolet absorbing layer has been proposed (see, for example, Patent Document 10). However, although the multilayer infrared ray absorbing film described in Patent Document 10 has an effect of improving light resistance, it is still insufficient, and further improvement of light resistance is desired.
Japanese Patent No. 3308545

  The object of the present invention is to solve the above-mentioned problems of the prior art. The transmittance in the visible light region is high, the transmittance in the near-infrared region is low, and the aging of the quality under high temperature and high humidity. An object of the present invention is to provide a near-infrared absorbing film and a near-infrared absorbing filter that have little change and are excellent in light resistance.

  This invention is made | formed in view of said background art, Comprising: The near-infrared absorption film which was able to solve said subject, and its manufacturing method are as follows. The “film” in the present invention is a concept including a so-called “sheet”. In addition, a front filter for a plasma display using the near-infrared absorbing film of the present invention is also included in the present invention.

  1st invention is a near-infrared absorption film which laminated | stacked the near-infrared absorption layer containing two or more types of near-infrared absorption pigment | dyes containing a diimmonium salt compound on a transparent base film, Comprising: The transmittance | permeability in wavelength 400nm is It is a near-infrared absorption film characterized by being 30% or less.

  2nd invention is a near-infrared absorption film as described in 1st invention characterized by the transmittance | permeability in wavelength 400nm being 20% or less.

  3rd invention further contains the pigment | dye which has an absorption peak in the wavelength range of 370 nm or more and 400 nm or less in said near-infrared absorption layer, The near-infrared absorption film as described in 1st or 2nd invention characterized by the above-mentioned It is.

  4th invention is a near-infrared absorption film as described in 3rd invention, wherein the pigment | dye which has an absorption peak in the wavelength range of 370 nm or more and 400 nm or less is an indole type compound.

  5th invention is a near-infrared absorption filter characterized by installing the near-infrared absorption film in any one of 1st-4th invention in the front surface of a plasma display.

  When the near-infrared absorbing film according to the present invention is installed as a near-infrared absorbing filter on the front surface of the plasma display, it absorbs unnecessary near-infrared rays emitted from the display in the same manner as a conventional near-infrared absorbing filter, and malfunctions of precision instruments. There is an advantage that a display with little change in color tone with time can be prevented, and a display with little change in color tone can be obtained particularly when installed outdoors.

Hereinafter, the present invention will be described in detail.
(Transparent substrate film)
In the present invention, the transparent substrate film is not particularly limited, but preferably has a total light transmittance of 80% or more and a haze of 2% or less. When the substrate film is inferior in transparency, there is a problem of reducing the luminance of the display. In particular, the haze of the base film is important. When the haze is high, the haze of the near-infrared absorbing film obtained by forming the near-infrared absorbing layer is also high, and the sharpness of the image on the display becomes poor.

  Examples of such transparent substrate films include polyester-based, acrylic-based, cellulose-based, polyethylene-based, polypropylene-based, polyolefin-based, polyvinyl chloride-based, polycarbonate, phenol-based, urethane-based plastic films, and the like. The thing which bonded two or more arbitrary types of these is mentioned. A polyester film having a good balance between heat resistance and flexibility is preferable, and a polyethylene terephthalate film is more preferable.

  The polyester film suitable as a transparent substrate film used in the present invention is an aromatic dicarboxylic acid or ester thereof such as terephthalic acid, isophthalic acid or naphthalenedicarboxylic acid as a dicarboxylic acid component, and ethylene glycol or diethylene glycol as a glycol component. Polyester chips obtained by esterification or transesterification of 1,4-butanediol, neopentyl glycol, etc., and then polycondensation are dried, melted with an extruder, and extruded from a T die into a sheet. It is a film manufactured by extending | stretching the unstretched sheet obtained by carrying out at least 1 axial direction, and then performing a heat setting process and a relaxation process.

  The film is particularly preferably a biaxially stretched film from the viewpoint of strength. Examples of the stretching method include a tubular stretching method, a simultaneous biaxial stretching method, a sequential biaxial stretching method, and the like, but a sequential biaxial stretching method is preferable in view of flatness, dimensional stability, thickness unevenness, and the like. The sequential biaxially stretched film is, for example, roll-stretched in the longitudinal direction at a glass transition temperature (Tg) to (Tg + 30 ° C.) of 2.0 to 5.0 times in the longitudinal direction and then preheated with a tenter 120 Stretch in the width direction 1.2 to 5.0 times at ~ 150 ° C. Furthermore, after biaxial stretching, it can be produced by performing heat setting treatment at a temperature of 220 ° C. or higher (melting point−10 ° C.) and then relaxing by 3 to 8% in the width direction. Further, in order to further improve the dimensional stability in the longitudinal direction of the film, a longitudinal relaxation treatment may be used in combination.

  In order to provide the film with handleability (for example, rollability after lamination), it is preferable to incorporate particles and form protrusions on the film surface. As particles to be included in the film, inorganic particles such as silica, kaolinite, talc, calcium carbonate, zeolite, alumina, etc., heat resistant polymer particles such as acrylic, PMMA, nylon, polystyrene, polyester, benzoguanamine / formalin condensate, etc. Is mentioned.

  From the viewpoint of transparency, the content of particles in the film is preferably small, for example, preferably 1 ppm or more and 1000 ppm or less. Furthermore, it is preferable to select particles having a refractive index close to that of the resin used from the viewpoint of transparency, and silica particles are particularly preferable. Moreover, in order to provide various functions as needed, the film may contain an ultraviolet ray inhibitor, a dye, an antistatic agent, and the like.

  In the present invention, it is preferable to add an ultraviolet absorber to the transparent substrate film. The purpose of containing the ultraviolet absorber is not only to improve the light resistance of the near-infrared absorbing layer that expresses the near-infrared absorbing ability, but also to reduce the strength of the substrate itself, etc. Become. 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.

  The transparent substrate film used in the present invention may be a single layer film or a composite film having two or more layers in which a surface layer and a center layer are laminated. In the case of a composite film, there is an advantage that the functions of the surface layer and the center layer can be designed independently. For example, by containing particles only on the thin surface layer and forming irregularities on the surface, the handling property is maintained, but the thick central layer does not substantially contain particles, so that the composite film as a whole is transparent. Can be further improved. Moreover, there is an advantage that bleeding of the ultraviolet absorber into the surface layer can be prevented by containing the ultraviolet absorber in the intermediate layer. The method for producing the composite film is not particularly limited. However, in consideration of productivity, the raw material for the surface layer and the central layer are extruded from separate extruders, led to one die, and after obtaining an unstretched sheet, at least Lamination by the so-called coextrusion method that is oriented in a uniaxial direction is particularly preferable.

  The thickness of the transparent substrate film varies depending on the material, but when a polyester film is used, the lower limit is preferably 35 μm, more preferably 50 μm. On the other hand, the upper limit of the thickness is preferably 260 μm, more preferably 200 μm. If the thickness is small, not only will the handling properties be poor, but the film will be wrinkled when the drying temperature is increased when forming a near-infrared absorbing layer to improve durability as described below. Therefore, the flatness tends to be poor. On the other hand, when the thickness of the transparent substrate film is large, not only is there a problem in cost, but flatness due to curling tends to occur when the film is wound and stored in a roll shape.

(Middle layer)
The near-infrared absorbing film of the present invention has a structure in which a near-infrared absorbing layer is laminated on a transparent substrate film, but the adhesion between the transparent substrate film and the near-infrared absorbing layer is improved and the transparent substrate film is transparent. For the purpose of improving the properties, it is preferable to provide an intermediate layer. In addition, when not containing particle | grains in a film, high transparency can be obtained, maintaining handling property by providing the intermediate | middle layer containing particle | grains simultaneously at the time of film manufacture.

  Examples of the resin constituting the intermediate layer include polyester resins, polyurethane resins, polyester urethane resins, acrylic resins, melamine resins, and the like, but resins that have good adhesion to the base material and the near-infrared absorbing layer are used. It is important to select one or more types. Specifically, if the resin constituting the base material and the near-infrared absorbing layer is an ester type, it is possible to select a polyester type or a polyester urethane type having a similar structure. preferable.

  The intermediate layer preferably contains a crosslinking agent for the purpose of improving adhesion to form a crosslinked structure. Examples of the crosslinking agent include urea, epoxy, melamine, and isocyanate. In particular, when the resin is whitened under high temperature and high humidity and the strength is lowered, the effect of the crosslinking agent is remarkable. In addition, you may use the graft copolymer resin which has self-crosslinking property as resin, without using a crosslinking agent.

  The intermediate layer may contain various kinds of particles for the purpose of forming irregularities on the surface and improving slipperiness. Examples of the particles to be included in the intermediate layer include inorganic particles such as silica, kaolinite, talc, calcium carbonate, zeolite, and alumina, organic materials such as acrylic, PMMA, nylon, styrene, polyester, and benzoguanamine / formalin condensate. Particles. In addition, it is preferable to select particles having a refractive index close to that of the resin used from the viewpoint of transparency. For example, silica particles are suitable for an intermediate layer having a copolymerized polyester resin as a resin component.

  Furthermore, in order to give various functions to the intermediate layer, a surfactant, an antistatic agent, a dye, an ultraviolet absorber, or the like may be contained.

  The intermediate layer may be a single layer if it has the desired function, but may be laminated in two or more layers as necessary.

  The thickness of the intermediate layer is not particularly limited as long as it has a desired function, but is preferably 0.01 μm or more and 5 μm or less. When the thickness is small, the function as an intermediate layer is hardly exhibited. On the contrary, when the thickness is thick, the transparency tends to be poor.

  As a method for providing the intermediate layer, a coating method is preferable. As the coating method, using a known coating method such as gravure coating method, kiss coating method, dip method, spray coating method, curtain coating method, air knife coating method, blade coating method, reverse roll coating method, etc. It can be provided by an in-line coating method in which a coating layer is provided, or an offline coating method in which a coating layer is provided after film production. Of these methods, the in-line coating method is not only excellent in terms of cost, but by adding particles to the coating layer, it is not necessary to include particles in the transparent substrate film, so the transparency is highly improved. Is preferable.

(Near-infrared absorbing layer)
The near-infrared absorbing film of the present invention is provided with a near-infrared absorbing layer mainly containing a near-infrared absorbing dye and a resin directly or via an intermediate layer on a transparent substrate film. The above “mainly containing near-infrared absorbing dye and resin” means that the near-infrared absorbing layer contains 80% by mass or more of near-infrared absorbing dye and resin. The sum of the contents of the near-infrared absorbing dye and the resin in the near-infrared absorbing layer is preferably 85% by mass or more, and particularly preferably 90% by mass or more.

  The near-infrared absorbing dye is a dye having a maximum absorption in the near-infrared region having a wavelength of 800 to 1200 nm, for example, a diimmonium salt type, a phthalocyanine type, a dithiol metal complex type, a naphthalocyanine type, an azo type, a polymethine type, Examples include anthraquinone, naphthoquinone, pyrylium, thiopyrylium, squarylium, croconium, tetradehycholine, triphenylmethane, cyanine, azo, and aminium compounds. These compounds are used alone or in admixture of two or more, but they have a large absorption in the near infrared region, a wide absorption region, and a high transmittance in the visible light region. It preferably contains a salt compound.

In the formula, R _{1 to} R ₈ may be the same or different and each represents a hydrogen atom, an alkyl group, an aryl group, an alkenyl group, an aralkyl group, or an alkynyl group. R _{9 to} R ₁₂ may be the same or different and each 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. R _{1 to} R ₁₂ which can be bonded to a substituent may have a substituent. X ⁻ represents an anion.

When R _{1 to} R _{8 in} the general formula (I) are (a) an alkyl group, (b) an aryl group, (c) an alkenyl group, and (d) an aralkyl group, the following functional groups can be exemplified.
(A) Alkyl group: methyl group, ethyl group, n-propyl group, iso-propyl group, n-butyl group, iso-butyl group, t-butyl group, n-amyl group, n-hexyl group, n-octyl Group, 2-hydroxyethyl group, 2-cyanoethyl group, 3-hydroxypropyl group, 3-cyanopropyl group, methoxyethyl group, ethoxyethyl group, butoxyethyl group and the like.
(B) Aryl group: phenyl group, fluorophenyl group, chlorophenyl group, tolyl group, diethylaminophenyl group, naphthyl group and the like.
(C) Alkenyl group: vinyl group, propenyl group, butenyl group, pentenyl group and the like.
(D) Aralkyl group: benzyl group, p-fluorobenzyl group, p-chlorophenyl group, phenylpropyl group, naphthylethyl group and the like.

Moreover, as the (e) halogen atom, (f) amino group, (g) alkyl group, and (h) alkoxyl group of R _{9 to} R _{12 in} the general formula (I), the following functional groups can be exemplified. .
(E) Halogen atom: fluorine, chlorine, bromine and the like.
(F) Amino group: diethylamino group, dimethylamino group and the like.
(G) Alkyl group: methyl group, ethyl group, propyl group, trifluoromethyl group and the like.
(H) Alkoxyl group: methoxy group, ethoxy group, propoxy group and the like.

Examples of X ⁻ in the above general formula (I) include fluorine ion, chlorine ion, bromine ion, iodine ion, perchlorate ion, hexafluoroantimonate ion, hexafluorophosphate ion, and tetrafluoroboric acid. Anions such as ions and bis (trifluoromethanesulfonyl) imido ions.

  A commercially available product can be used as the diimmonium salt compound represented by the general formula (I). For example, Kayasorb IRG-022, IRG-023, IRG-024, K-1030, K-1032 (manufactured by Nippon Kayaku Co., Ltd.), CIR-1080, CIR-1081, CIR-1083, CIR-1085, CIR- RL (manufactured by Nippon Carlit) is suitable.

  The light resistance which is the subject of the present invention is mainly due to light degradation of the above diimmonium salt compound, and the diimmonium salt compound is changed to a compound having an absorption at a wavelength of around 420 nm due to degradation, and the near infrared ray The absorption film changes color. In the present invention, a diimmonium salt compound is used in order to improve near-infrared absorptivity. However, it is important to minimize the deterioration of the diimmonium salt compound.

  In the near-infrared absorbing layer of the near-infrared absorbing film of the present invention, in addition to the diimonium salt compound represented by the above general formula (I), for the purpose of expanding the absorption region of the near-infrared region and adjusting the color tone, It is preferable to use a near infrared absorbing dye in combination.

  Other near-infrared absorbing dyes that can be used in combination with the diimmonium salt compounds include phthalocyanine compounds, dithiol metal complex compounds, cyanine compounds, naphthalocyanine compounds, squarylium salt compounds, pyrylium salt compounds, thioperyllium compounds. Compounds, croconium compounds, indoaniline chelate dyes, indonaphthol chelate dyes, azo dyes, azo chelate dyes, aminium salt dyes, quinone dyes, anthraquinone dyes, polymethine dyes, triphenylmethane dyes, etc. Can be mentioned. Of these, phthalocyanine compounds and dithiol metal complex compounds, which are less deteriorated at high temperatures and high humidity, are preferable. When dyes that tend to deteriorate are used, not only does the stability over time of the transmittance in the near-infrared region become poor, but the diimmonium salt compound acts as a quencher and deteriorates, and the near-infrared absorbing film becomes yellow. Discolor.

  For example, a commercial item can be used for the phthalocyanine compound. Specifically, Excolor IR-1, IR-2, IR-3, IR-4, IR-10, IR-10A, IR-12, IR-14, TXEX-805K, TXEX-809K, TXEX-810K, TXEX-811K, TXEX-812K, TXEX-813K, TXEX-814K (manufactured by Nippon Shokubai Co., Ltd.), MIR-369, MIR-389 (manufactured by Mitsui Chemicals, Inc.) and the like are suitable.

In the present invention, in order to control the target absorption in the near-infrared region and the transmittance in the visible light region, the amount of the near-infrared-absorbing dye is 0.01 g / in any surface in the thickness direction of the near-infrared absorbing layer. it is preferable to adjust to exist in m ² or more 1.0 g / m ² or less. When the amount of the near-infrared absorbing dye per unit area is small, the absorbing ability in the near-infrared region tends to be insufficient. On the other hand, when the amount of the near-infrared absorbing dye per unit area is large, the transparency in the visible light region is insufficient, and the brightness of the display tends to decrease.

  The near-infrared absorbing pigment content in the near-infrared absorbing layer is preferably 1% by mass or more and 10% by mass or less based on the resin. The upper limit of the content of the near-infrared absorbing dye is more preferably 8% by mass, and particularly preferably 6% by mass with respect to the resin. Further, the lower limit of the content of the near-infrared absorbing dye is more preferably 2% by mass, and particularly preferably 3% by mass with respect to the resin.

  When the amount of the near-infrared absorbing dye in the resin is small, it is necessary to increase the coating amount of the near-infrared absorbing layer in order to achieve the target near-infrared absorbing ability. In this case, if the coating film is sufficiently dried, it is necessary to increase the temperature and / or the time for a long time, and the deterioration of the pigment and the poor flatness of the base material are likely to occur. In particular, when a diimmonium salt compound is used as a near-infrared absorbing dye, the diimmonium salt compound is easily denatured at high temperatures or high humidity, and absorption in the near-infrared region is reduced or a part of the visible light region is reduced. The transmittance tends to decrease, and the color tone tends to change easily. On the other hand, when the amount of the near-infrared absorbing dye in the resin is large, the distance between the dyes in the resin becomes shorter. For this reason, the interaction between the dyes becomes strong, and even if the residual solvent is reduced, the dyes are likely to be denatured over time.

  In the present invention, the near-infrared absorbing dye is laminated on the transparent substrate film by a coating method as a composition dispersed or dissolved in the resin. The resin is not particularly limited as long as it can dissolve or disperse the near-infrared absorbing dye uniformly. Polyester, acrylic, polyamide, polyurethane, polyolefin, and polycarbonate resins can be preferably used. Among these resins, polyester resins or acrylic resins are preferable from the viewpoint of excellent adhesion to the substrate. In the case where the resin is hard, microcracking may occur in the coating film in the post-processing step, so it is preferable to introduce a flexible component into the resin molecular skeleton. Furthermore, the glass transition temperature of the resin is preferably equal to or higher than the guaranteed use temperature of the equipment to be used.

  When the glass transition temperature of the resin forming the near-infrared absorbing layer is equal to or lower than the device operating temperature, the dyes dispersed in the resin react with each other, or the resin absorbs moisture or the like in the outside air. And the deterioration of the binder resin increases. Moreover, in this invention, although the glass transition temperature of the said resin will not be specifically limited if it is more than apparatus use temperature, 85 to 160 degreeC is preferable. In addition, the said glass transition temperature is made to heat up at 10 degree-C / min over the temperature range of 25-300 degreeC using a differential scanning calorimeter (the Seiko Instruments Inc. make, DSC6200) based on JIS-K7121. , Means the extrapolated glass transition onset temperature obtained from the DSC curve.

  When the glass transition temperature of the resin is lower than 85 ° C., near-infrared absorbing dyes and neon cut dyes easily move under high temperature and high humidity. The denaturation tends to be remarkable. For this reason, the spectral characteristics and color tone of the film tend to easily change.

  On the other hand, when the glass transition temperature of the resin exceeds 160 ° C., if the resin is dissolved in a solvent and applied on a transparent substrate film, the drying temperature must be increased if sufficient drying is attempted. . When the drying temperature is increased, the frequency of occurrence of poor flatness of the substrate due to heat wrinkles and further deterioration of the dye increases. Moreover, when it dries at low temperature, drying time becomes long and productivity falls. In addition, the coating layer (near infrared absorption layer) may not be sufficiently dried, and the solvent tends to remain in the coating film. Therefore, as described above, the apparent glass transition temperature of the resin is lowered, and the modification of the dye is likely to occur.

  In the near-infrared absorbing film of the present invention, it is important that the transmittance at a wavelength of 400 nm is 0% or more and 30% or less, and preferably 0% or more and 20% or less. By reducing the transmittance at a wavelength of 400 nm, not only can the deterioration of the diimmonium salt compound be suppressed, but even if it deteriorates, the amount of change in color tone is reduced. This is because the diimmonium salt compound is particularly easily deteriorated by light in the vicinity of a wavelength of 400 nm. Therefore, by reducing the transmittance at a wavelength of 400 nm, it is possible to prevent deterioration of the diimmonium salt compound and suppress a change in color tone. In addition, when the diimmonium salt compound is deteriorated, it changes to a dye having absorption in the vicinity of a wavelength of 390 to 430 nm. Can do.

  The method for adjusting the transmittance at a wavelength of 400 nm can be achieved by a method in which a dye having absorption near a wavelength of 400 nm is contained in the near infrared absorption layer. As the dye having absorption in the vicinity of a wavelength of 400 nm, a dye having an absorption peak at a wavelength of 370 nm to 400 nm, more preferably a wavelength of 380 nm to 400 nm is preferable so as to reduce the influence on the visible region. As such a dye, compounds such as benzotriazole, benzophenone, cyclic imino ester, indole, and azomethine can be used. Of these, indole compounds and azomethine compounds are preferred because they do not promote deterioration of diimmonium salt compounds under high temperature and high humidity.

  The content of the dye for adjusting the transmittance at a wavelength of 400 nm in the near infrared absorption layer varies depending on the absorption ability of the dye, but is preferably 10% by mass or more and 1000% by mass or less with respect to the diimmonium salt compound. When the content of the pigment is small, the effect of improving the light resistance is small. On the other hand, when the content is large, not only the strength of the near-infrared absorbing layer is lowered but also the film is easily colored yellow.

  In this invention, a near-infrared absorption layer is formed by apply | coating and drying the coating liquid containing a near-infrared absorption pigment | dye, resin, and an organic solvent on a transparent base film. At this time, it is preferable to contain a surfactant in the coating solution. By including the surfactant, the coating appearance of the near-infrared absorbing layer, particularly dents due to minute bubbles, dents due to adhesion of foreign matters, and repellency in the drying process are improved. Furthermore, the surfactant is bleed and localized on the surface of the near-infrared absorbing layer by applying and drying the surfactant under specific conditions. As a result, not only the durability of the surface of the near-infrared absorbing layer is improved, but also the surface of the near-infrared absorbing layer is provided with slipperiness, and handling is possible without forming surface irregularities on the near-infrared absorbing layer or / and the opposite surface. It becomes easy to wind in a roll shape.

  As the surfactant, known cationic, anionic and nonionic surfactants can be preferably used, but have a polar group from the viewpoint of suppressing the deterioration of the near-infrared absorbing dye due to the interaction with the near-infrared absorbing dye. Nonionic type is preferable, and further, a silicone type or fluorine type surfactant having excellent surface activity is preferable.

  Examples of silicone surfactants include dimethyl silicone, amino silane, acrylic silane, vinyl benzyl silane, vinyl benzilyl amino silane, glycid silane, mercapto silane, dimethyl silane, polydimethyl siloxane, polyalkoxy siloxane, hydrodiene modified siloxane, vinyl modified siloxane, Vitroxy 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, etc. .

  Fluorosurfactants include ethylene tetrafluoride, perfluoroalkyl ammonium salt, perfluoroalkyl sulfonic acid amide, sodium perfluoroalkyl sulfonate, perfluoroalkyl potassium salt, perfluoroalkyl carboxylate, perfluoroalkyl sulfone. Acid salts, perfluoroalkyl ethylene oxide adducts, perfluoroalkyl trimethyl ammonium salts, perfluoroalkyl amino sulfonates, perfluoroalkyl phosphate esters, perfluoroalkyl alkyl compounds, perfluoroalkyl alkyl betaines, perfluoroalkyl halides, etc. Is mentioned.

  The content of the surfactant is preferably 0.01% by mass or more and 2.00% by mass or less with respect to the resin constituting the near infrared absorption layer. When the surfactant content is low, the effect of improving the appearance of the coating film and imparting slipperiness is insufficient. Conversely, when the surfactant content is high, the near-infrared absorbing layer absorbs moisture. In some cases, the deterioration of the pigment may be promoted.

  In the present invention, the HLB of the surfactant is preferably 2 or more and 12 or less. The lower limit value of HLB is preferably 3, particularly preferably 4. On the other hand, the upper limit value of the HLB is preferably 11, particularly preferably 10. When a surfactant with a low HLB is used, the surface of the near-infrared absorbing layer becomes water-repellent and can suppress deterioration of the near-infrared absorbing dye even when stored for a long time in a high-temperature / high-humidity environment. It is possible to easily provide slipperiness. On the other hand, when a surfactant having an HLB that is too low is used, the leveling property is insufficient due to insufficient surface activity. On the other hand, when a surfactant with too high HLB is used, not only the slip property of the near-infrared absorbing layer is insufficient, but also the near-infrared absorbing layer easily absorbs moisture, and the temporal stability of the dye is poor. It becomes.

  In addition, HLB is a value that WCGriffin of Atlas Powder, Inc. in the United States named Hydorophil Lyophile Balance and indexed the balance between hydrophilic group and lipophilic group contained in the surfactant molecule as a characteristic value. . The lower the HLB, the more lipophilic, and the higher the HLB, the higher the hydrophilicity.

  The localization of the surfactant on the surface of the near-infrared absorbing layer varies depending on the type of resin used and the solvent, but it is most likely to occur when HLB is most likely near 7 and the initial drying is mild. Easy to exist. The degree of localization of the surfactant on the surface of the near-infrared absorbing layer is, for example, comparing the content of the surfactant in the near-infrared absorbing layer with the amount of the surfactant on the surface of the near-infrared absorbing layer. Can be confirmed. For example, in the case of a silicone-based surfactant, the near-infrared absorbing layer is obtained by comparing the amount of Si in the near-infrared absorbing layer quantified by chemical analysis with the amount of Si on the surface of the near-infrared absorbing layer quantified by ESCA analysis. The degree of localization of the surfactant on the surface of the surface can be confirmed.

  In the present invention, the near-infrared absorbing layer is laminated by applying and drying a coating liquid containing a resin, a near-infrared absorbing dye, a surfactant, and an organic solvent on a transparent substrate film. From the viewpoint of coatability, it is important to further dilute with an organic solvent.

  Examples of the organic solvent include (1) alcohols such as methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, tridecyl alcohol, cyclohexyl alcohol, 2-methylcyclohexyl alcohol, and (2) ethylene glycol. , Glycols such as diethylene glycol, triethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, glycerin, (3) 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 Glycol ethers such as ether acetate, ethylene glycol monoethyl acetate, ethylene glycol monobutyl acetate, diethylene glycol monomethyl acetate, diethylene glycol monoethyl acetate, diethylene glycol monobutyl acetate, (4) ethyl acetate, isopropylene acetate, n-butyl acetate, etc. Examples include esters, (5) ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, cyclopentanone, isophorone, and diacetone alcohol. Moreover, you may use these organic solvents individually or in mixture of 2 or more types.

  Preferably, ketones having excellent dye solubility are contained in an amount of 30% by mass to 80% by mass with respect to the total organic solvent used in the coating solution, and other organic solvents are considered in view of leveling properties and drying properties. It is preferable to select. The boiling point of the organic solvent is preferably 60 ° C. or higher and 180 ° C. or lower. When the boiling point is low, the solid content concentration of the coating solution changes during coating, and the coating thickness is difficult to stabilize. On the other hand, when the boiling point is high, the amount of the organic solvent remaining in the coating film increases and the temporal stability becomes poor.

  Examples of the method for dissolving or dispersing the near-infrared absorbing dye and the resin in the organic solvent include stirring, dispersion, or pulverization under heating. By heating, the solubility of the pigment and the resin can be improved, and the deterioration of the coating appearance due to undissolved substances can be suppressed. Moreover, it becomes possible to form a coating layer having excellent transparency by dispersing or pulverizing the resin and the pigment and dispersing them in the coating solution in the form of fine particles having a size of 0.3 μm or less. A well-known thing can be used as a disperser or a grinder. Examples thereof 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.

  If there is contamination or undissolved material having a size of 1 μm or more in the coating solution, the appearance after coating becomes poor. Therefore, it is necessary to remove it with a filter or the like before coating. Various filters can be suitably used as the filter, but it is preferable to use a filter having a filtration performance capable of removing 99% or more of foreign matters having a size of 1 μm. When a coating solution containing contaminants and undissolved substances having a size of 1 μm or more is applied and dried, a dent or the like is generated around the coating solution, which may cause a defect of 100 to 1000 μm in size.

  The solid content concentration of the resin and the pigment contained in the coating solution is preferably 10% by mass or more and 30% by weight. When the solid content concentration is low, it takes time to dry after coating, resulting in poor productivity and an increase in the amount of solvent remaining in the coating film, resulting in poor temporal stability. On the other hand, when the solid content concentration is high, the viscosity of the coating solution becomes high and the leveling property is insufficient, resulting in a poor coating appearance. The viscosity of the coating solution is preferably 10 cps or more and 300 cps or less from the viewpoint of coating appearance, and it is preferable to adjust the solid content concentration with an organic solvent so as to be in this range.

  In the present invention, as a method for applying the near infrared absorption layer on the transparent substrate film, gravure coating method, kiss coating method, dip method, spray coating method, curtain coating method, air knife coating method, blade coating method, reverse roll coating Conventionally used methods such as a method, a bar coat method, and a lip coat method can be applied. Among these, a gravure coating method that can be applied uniformly, particularly a reverse gravure method is preferable. The diameter of the gravure is preferably 80 mm or less. When the diameter of the gravure is large, the frequency of undulation streaks in the flow direction increases.

The coating amount of the near infrared absorbing layer after drying is not particularly limited, but the lower limit is preferably 1 g / m ² , more preferably 3 g / m ² , and the upper limit is preferably 50 g / m ² , more preferably 30 g / m. ² . When the coating amount after drying is small, the near-infrared absorbing power tends to be insufficient. Therefore, when the amount of the near-infrared absorbing dye in the resin is increased, the distance between the dyes is shortened, so that the interaction between the dyes is strengthened.

  As a result, the deterioration of the dye is likely to occur, and the temporal stability becomes poor. Conversely, when the coating amount after drying is large, the near-infrared absorbing ability is sufficient, but the transparency in the visible light region is lowered, and the brightness of the display is lowered. Therefore, if the amount of the near-infrared absorbing dye in the resin is reduced, the optical characteristics can be adjusted, but drying tends to be insufficient. As a result, the temporal stability of the dye becomes poor due to the residual solvent in the coating film. On the other hand, when the drying is sufficient, the flatness of the substrate becomes poor.

As a method for applying the coating liquid on the transparent substrate film and drying, known hot air drying, an infrared heater and the like can be mentioned, but hot air drying with a high drying speed is preferable.
In the initial constant rate drying stage after coating, drying is preferably performed at 20 ° C. or more and 80 ° C. or less using hot air of 2 m / sec or more and 30 m / sec. The lower limit of the drying temperature is more preferably 30 ° C. When the initial drying is performed strongly (the hot air temperature is high and the hot air volume is large), the surfactant is less likely to be localized on the surface. As a result, not only is it difficult to improve durability and impart slipperiness to the near-infrared absorbing layer, but also minute defects of the coating film such as fine foam removal, fine repellency and cracks are likely to occur. Conversely, when initial drying is weakened (the hot air temperature is low and the hot air volume is small), the coating appearance is good. However, it takes time to dry and there are problems in terms of productivity (cost) as well as problems such as brushing. When a surfactant is not added to the near-infrared absorbing layer forming coating solution, the above minute defects are likely to occur, and the initial drying needs to be considerably weakened.

  In the reduction drying process, it is important to increase the temperature higher than the initial drying and reduce the amount of solvent in the coating film, and a preferable temperature is 120 ° C. or higher and 180 ° C. or lower. Particularly preferably, the lower limit is 140 ° C and the upper limit is 170 ° C. When the drying temperature is low, the amount of solvent in the coating film is difficult to decrease and becomes a residual solvent, resulting in insufficient stability of the dye over time. Conversely, when dried at a high temperature, not only the flatness of the base material is likely to deteriorate due to heat wrinkles, but also the near-infrared absorbing dye, particularly the diimmonium salt compound, is likely to be deteriorated by heat. Moreover, it is preferable that the passage time (drying time) of the film after coating in the decreasing rate drying step is 5 seconds or more and 180 seconds or less. When the passage time is short, the amount of solvent remaining in the coating film increases. As a result, the temporal stability becomes poor. On the other hand, when the passage time is long, not only the productivity is deteriorated, but heat wrinkles are generated on the base material, and the flatness is easily deteriorated. The upper limit of the passage time is particularly preferably 30 seconds from the viewpoint of productivity and flatness.

  In the final drying step (cooling step), it is preferable to set the hot air temperature to be equal to or lower than the glass transition temperature of the resin constituting the wavelength selective absorption layer and to cool the actual temperature of the substrate to be equal to or lower than the glass transition temperature of the resin in a flat state. . When leaving the drying furnace at a high temperature that exceeds the glass transition temperature of the resin that constitutes the wavelength selective absorption layer, the slipperiness becomes poor when the coated surface comes into contact with the roll surface, and scratches are generated. In addition to curling, curling or the like may occur.

  In this invention, it is preferable to perform a post-cure process after apply | coating and drying the coating liquid containing a near-infrared absorption pigment | dye, resin, and an organic solvent on a transparent base film. By performing the post-cure treatment, it is possible to reduce the durability of the near-infrared absorbing film, particularly the change in color tone under high temperature and high humidity. The above-mentioned effect by the post-cure treatment is particularly remarkable when an intermediate layer is provided between the near-infrared absorbing layer and the transparent base material, and further, it is significantly effective in the case of an intermediate layer having a crosslinking agent.

  As a result of detailed analysis of dye deterioration under high temperature and high humidity, the deterioration of the dye not only inside the near infrared absorption layer but also at the interface between the near infrared absorption layer and the transparent substrate or intermediate layer is a factor. It was found that the dye deterioration in the glass was more likely to occur in a low temperature and low humidity environment than in the near infrared absorption layer. By performing the post-cure treatment, pigment deterioration at the interface between the near-infrared absorbing layer and the transparent substrate film is caused in advance, and the durability under high temperature and high humidity can be substantially improved. Furthermore, the residual solvent in the near infrared absorbing layer can be reduced to improve the durability inside the near infrared absorbing layer.

  As heating conditions for the post-cure treatment, it is important that the treatment is performed in an environment of 25 ° C. or more and 70 ° C. or less, and the product of the treatment temperature (° C.) and the treatment time (hr) is 1000 (° C. · hr) or more. is there. When the treatment temperature is less than 25 ° C., it is difficult to obtain the effect of improving the durability even if the treatment is performed for a long time. On the other hand, when the processing temperature is higher than 70 ° C., blocking and film planarity are likely to occur when the post-curing treatment is performed in a roll form.

  The post-cure treatment may be performed after laminating the near-infrared absorbing layer on the transparent substrate film, but in the subsequent process, the adhesive layer is laminated on the near-infrared absorbing layer, and the antireflection film or electromagnetic wave preventing film is bonded. You can go after.

(Near infrared absorption filter)
In the present invention, the near-infrared absorption filter is a filter having a low transmittance in the near-infrared region with a wavelength of 800 to 1200 nm and a high transmittance in the visible light region with a wavelength of 400 to 800 nm. The transmittance in the near infrared region is preferably as low as possible, specifically 40% or less, more preferably 30% or less. When the transmittance of the near-infrared region is high, when the near-infrared absorbing film of the present invention is used as a constituent member of the front filter of the plasma display, the absorption of the near-infrared emitted from the plasma display is insufficient, It becomes difficult to prevent malfunction of an electronic device using a near infrared remote controller. Further, when used as a display filter, the visible light region has a higher transmittance, preferably 50% or more, more preferably 60% or more. When the transmittance in the visible light region is low, the color of the display is hindered and an image with low luminance is obtained.
The adjustment of the transmittance can be controlled by the kind of the above-mentioned near-infrared absorbing dye and the abundance of the near-infrared absorbing dye per unit area.

  When the color tone of the near-infrared absorbing filter is 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 adjustment of the color tone of the near-infrared absorbing filter can be controlled by mixing the kind of the above-mentioned near-infrared absorbing dye, the amount of the near-infrared absorbing dye per unit area, and further mixing other color correcting dyes. In addition, when laminating a colored adhesive layer and other functional layers (antireflection layer, electromagnetic wave absorbing layer, ultraviolet absorbing layer, etc.) on the front or back surface of the near infrared absorbing filter described later, the natural color is included. It is preferable to adjust the color tone of the near infrared absorption filter.

  The near-infrared absorbing layer of the present invention preferably has a coating film appearance that does not have a defect with a maximum diameter of 300 μm or more, more preferably 100 μm. A defect having a maximum diameter of 300 μm or more is detected as a bright spot when it is installed on the front surface of the plasma display and an image is displayed, and the defect becomes noticeable. A defect having a maximum diameter of 100 μm or more and less than 300 μm may be emphasized by the lens effect by bonding such as adhesive processing, and must be controlled so as not to exist in the near infrared absorption layer as much as possible. Also, streaks, unevenness, etc. with a thin coating layer become prominent on the front surface of the display and become a problem.

  It is preferable that the near-infrared absorption filter does not change the transmittance of near-infrared rays and the transmittance of visible light even when left for a long period of time 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 for preventing malfunction of the electronic device using the near infrared remote controller cannot be obtained. There is.

  To further improve the stability over time, in addition to the post-cure treatment, by controlling the type of organic solvent used in the coating solution for forming the near infrared absorption layer, the thickness of the coating layer, the drying conditions, It is preferable to use a method for reducing the amount of residual solvent in the near infrared absorbing layer. Moreover, the residual solvent amount in the near-infrared absorbing layer can also be reduced by adjusting the content of the pigment in the resin constituting the near-infrared absorbing layer. The amount of residual solvent in the near infrared absorption layer is preferably as small as possible, and is preferably controlled to 3% by mass or less. If the amount of residual solvent in the near-infrared absorbing layer is 3% by mass or less, there is substantially no difference in stability over time. However, in order to further reduce the amount of residual solvent, for example, if drying is performed under severe conditions, problems such as poor planarity of the filter and alteration of the dye may occur. In addition, productivity is reduced by a method that does not use heat treatment such as drying under reduced pressure.

  In the present invention, for the purpose of blocking harmful electromagnetic waves emitted from the display, a conductive layer may be provided directly or via an adhesive on the same surface as the near infrared absorbing layer or on the opposite surface. The conductive layer may be either a metal mesh or a conductive thin film. When a metal mesh is used, the conductive layer preferably has a metal mesh conductive layer with an aperture ratio of 50% or more. This is because, when the aperture ratio of the metal mesh is low, the electromagnetic shielding property is good, but the light transmittance is likely to be lowered. As the metal mesh, a metal foil having a high electrical conductivity is etched to form a mesh, a woven mesh using metal fibers, or a metal plating on the surface of polymer fibers. And attached fibers. The metal used for the electromagnetic wave absorbing layer is not particularly limited as long as it has high electrical conductivity and good stability, but is not particularly limited, but from the viewpoint of workability, cost, etc., preferably copper, nickel, Tungsten or the like is preferable.

  In order to further increase the visible light transmittance, it is preferable to use a metal oxide as the material of the conductive layer. In order to improve the electrical conductivity of the transparent conductive layer, it is preferable to use a multilayer film composed of a repeating structure of three or more layers of metal oxide / metal / metal oxide. By making the metal multi-layered, conductivity can be obtained while maintaining high visible light transmittance. The metal oxide may be any metal oxide as long as it has high conductivity and high visible light transmittance. Examples thereof include tin oxide, indium oxide, indium tin oxide (ITO), zinc oxide, titanium oxide, and bismuth oxide. The metal layer used in the present invention is preferably gold, silver, and a compound containing them from the viewpoint of conductivity.

  Furthermore, when the conductive layer is multi-layered, for example, when the number of repeated layers is 3, the thickness of the silver layer is preferably 50 to 200 mm, more preferably 50 to 100 mm. When the film thickness is thicker than this, the light transmittance decreases, and when it is thin, the resistance value tends to increase. Further, the thickness of the metal oxide layer is preferably 100 to 1000 mm, more preferably 100 to 500 mm. When the thickness of the metal oxide layer exceeds 1000 mm, the color tone tends to change due to coloring. On the other hand, when the thickness of the metal oxide layer is less than 100 mm, the resistance value tends to be high. Furthermore, in the case of multi-layering to three or more layers, for example, in the case of five layers such as metal oxide / silver / metal oxide / silver / metal oxide, the thickness of the central metal oxide is other than that It is preferable that it is thicker than the thickness of the metal oxide layer. By doing in this way, the light transmittance of the whole multilayer film can be improved.

  In the present invention, an antireflection layer or an antiglare layer may be provided directly or via an adhesive on the same surface as the near infrared absorbing layer of the near infrared absorbing film or on the opposite surface.

  In the present invention, an antireflection film or an electromagnetic wave prevention film may be bonded to the near infrared ray absorbing film through an adhesive layer. As the adhesive layer, known ones can be used, but when laminating on the near-infrared absorbing layer, it is preferable to use an adhesive that does not contain a crosslinking agent such as isocyanate or melamine. When a pressure-sensitive adhesive containing a crosslinking agent such as isocyanate or melamine is used, the crosslinking agent causes dye deterioration at the interface between the pressure-sensitive adhesive layer and the near-infrared absorbing layer, and the durability tends to decrease. In addition, when performing a post-cure process after laminating | stacking an adhesion layer, the fall of durability resulting from an adhesive can be suppressed.

  As a method of providing the adhesive layer on the near-infrared absorbing film, a transfer method in which the adhesive layer is applied and dried on the release film and then bonded to the near-infrared absorbing film to form an adhesive layer, and the adhesive is applied to the near-infrared absorbing film. There are two types of direct methods, coating and drying. Preferably, the transfer method is less prone to problems such as poor planarity of the near-infrared absorbing film.

  In the near-infrared absorbing filter, a layer having an ultraviolet absorbing ability may be provided for the purpose of improving light resistance. In order to impart ultraviolet absorbing ability, an ultraviolet absorber may be added to any one of the near infrared absorbing layer, the transparent substrate film, the pressure-sensitive adhesive, the antireflection layer, and the antiglare layer. The near-infrared absorbing filter having this ultraviolet absorbing layer is particularly preferably disposed on the front surface of the display so that the ultraviolet absorbing layer is on the surface side (the side opposite to the display side) of the near infrared absorbing layer. As the UV absorber, known organic UV inhibitors and inorganic UV inhibitors can be used.

  Next, examples and comparative examples of the present invention will be shown. The characteristic value measurement method and effect evaluation method used in the present invention are as follows.

<Total light transmittance, haze>
Using a haze meter (Nippon Denshoku Industries, NDH2000), the total light transmittance and haze were measured.

<Transmissivity>
It measured using the spectrophotometer (the Hitachi make, U-3500 type | mold). The indoor air was used as a reference for the transmittance.

<Absorption peak>
The amount of the dye was adjusted so that the transmittance of the absorption peak was in the range of 10 to 30%, and the dye was dissolved in a mixed solvent of methyl ethyl ketone and toluene (1: 1 by mass ratio). Using a spectrophotometer (manufactured by Hitachi, Ltd., U-3500 type), the light transmittance of this solution was measured at intervals of 1 nm wavelength to obtain absorption peaks. The indoor air was used as a reference for the transmittance.

<Color tone>
Using a color difference meter (manufactured by Nippon Denshoku Industries Co., Ltd., ZE-2000), the near-infrared absorption layer side is irradiated with light, and the a color value and b value of the Lab color system are used as the standard light using a C light source. Measurements were made at a 2 degree viewing angle.

<Stability over time>
The near-infrared absorbing film was treated in an atmosphere of 80 ° C. and 95% humidity for 48 hours, the color tone before and after the treatment was measured, and the change in color tone was measured from the following formula (1).

Change amount = √ ((a value before processing−a value after processing) ² + (b value before processing−b value after processing) ² )
... (1)

<Light resistance>
In accordance with JIS L-0843, ultraviolet light was irradiated for 48 hours from the transparent substrate film side in an environment with a black panel temperature of 63 ° C. and a humidity of 50% RH. The color tone before and after irradiation with ultraviolet rays was measured, and the amount of change in color tone was measured according to the above equation (1).

Example 1
The following is applied so that the coating amount after drying is 9.2 g / m ² on one side of a transparent base film made of a biaxially stretched polyester film (Toyobo, A4300, thickness 100 μm) having coating layers on both sides. Coating solution A (solid content concentration: 21.9 mass%, viscosity: 20 cps) was applied by a reverse method using a diagonal gravure with a diameter of 60 cm. Next, the coated film is dried by passing it through hot air of 5 m / sec at 40 ° C. for 20 seconds, hot air of 20 m / sec at 160 ° C. for 20 seconds, and further for 10 seconds with hot air of 20 m / sec at 90 ° C. Then, a near-infrared absorbing layer was laminated.

(Coating liquid A for near-infrared absorbing layer)
Organic solvent, resin, near-infrared absorbing dye, dye having an absorption peak in the wavelength range of 370 nm to 400 nm, and surfactant are prepared so as to have the following mass ratio, and undissolved with a filter having a nominal filtration accuracy of 1 μm Was removed to prepare a coating solution A. Since the resin is difficult to dissolve, it was dissolved in advance in an organic solvent under heating, and after cooling to room temperature, the dye was added and stirred to dissolve. The absorption peak of the following indole compounds has a wavelength of 390 nm.
・ Methyl ethyl ketone 38.773 mass%
・ Toluene 38.773 mass%
-Acrylic resin 21.000% by mass
(Made by Mitsubishi Rayon, BR-80)
・ Diimonium salt compound 0.666% by mass
(Nippon Carlit, CIR-RL)
・ Phthalocyanine compound 0.371% by mass
(Nippon Shokubai, IR-10A)
・ Indole compound 0.360% by mass
(Orient Chemical, UA-3902)
・ Silicon surfactant 0.057% by mass
(Dow Corning, Paintad 57; HLB = 6.7)

  Table 1 shows the physical properties of the obtained near-infrared absorbing film. A film having strong absorption in the near infrared region and high transmittance in the visible light region was obtained. Moreover, stability over time and light resistance were also good.

Example 2
In Example 1, a near-infrared absorbing film was obtained in the same manner as in Example 1 except that the following coating solution B was used.

(Coating solution B for near-infrared absorbing layer)
Organic solvent, resin, near-infrared absorbing dye, dye having an absorption peak in the wavelength range of 370 nm to 400 nm, and surfactant are prepared so as to have the following mass ratio, and undissolved with a filter having a nominal filtration accuracy of 1 μm Was removed to prepare a coating liquid B. Since the resin is difficult to dissolve, it was dissolved in advance in an organic solvent under heating, and after cooling to room temperature, the dye was added and stirred to dissolve. The absorption peak of the following indole compounds has a wavelength of 390 nm.
・ Methyl ethyl ketone 38.863 mass%
・ Toluene 38.863 mass%
-Acrylic resin 21.000% by mass
(Made by Mitsubishi Rayon, BR-80)
・ Diimonium salt compound 0.666% by mass
(Nippon Carlit, CIR-RL)
・ Phthalocyanine compound 0.371% by mass
(Nippon Shokubai, IR-10A)
・ Indole compound 0.180% by mass
(Orient Chemical, UA-3902)
・ Silicon surfactant 0.057% by mass
(Dow Corning, Paintad 57; HLB = 6.7)

  Table 1 shows the physical properties of the obtained near-infrared absorbing film. A film having strong absorption in the near infrared region and high transmittance in the visible light region was obtained. Moreover, stability over time and light resistance were also good.

Example 3
In Example 1, a near-infrared absorbing film was obtained in the same manner as in Example 1 except that the following coating solution C was used.

(Coating liquid C for near-infrared absorbing layer)
Organic solvent, resin, near-infrared absorbing dye, dye having an absorption peak in the wavelength range of 370 nm to 400 nm, and surfactant are prepared so as to have the following mass ratio, and undissolved with a filter having a nominal filtration accuracy of 1 μm Was removed to prepare a coating liquid C. Since the resin is difficult to dissolve, it was dissolved in advance in an organic solvent under heating, and after cooling to room temperature, the dye was added and stirred to dissolve. The absorption peak of the following indole compounds has a wavelength of 390 nm.
・ Methyl ethyl ketone 38.503 mass%
・ Toluene 38.503 mass%
-Acrylic resin 21.000% by mass
(Made by Mitsubishi Rayon, BR-80)
・ Diimonium salt compound 0.666% by mass
(Nippon Carlit, CIR-RL)
・ Phthalocyanine compound 0.371% by mass
(Nippon Shokubai, IR-10A)
・ Indole compound 0.900% by mass
(Orient Chemical, UA-3902)
・ Silicon surfactant 0.057% by mass
(Dow Corning, Paintad 57; HLB = 6.7)

  Table 1 shows the physical properties of the obtained near-infrared absorbing film. A film having strong absorption in the near infrared region and high transmittance in the visible light region was obtained. Moreover, stability over time and light resistance were also good.

Example 4
In Example 1, a near-infrared absorbing film was obtained in the same manner as in Example 1 except that the following coating solution D was used.

(Coating liquid D for near-infrared absorbing layer)
Organic solvent, resin, near-infrared absorbing dye, dye having an absorption peak in the wavelength range of 370 nm to 400 nm, and surfactant are prepared so as to have the following mass ratio, and undissolved with a filter having a nominal filtration accuracy of 1 μm Was removed to prepare a coating liquid D. Since the resin is difficult to dissolve, it was dissolved in advance in an organic solvent under heating, and after cooling to room temperature, the dye was added and stirred to dissolve. The absorption peak of the following indole compounds has a wavelength of 396 nm.
・ Methyl ethyl ketone 38.773 mass%
・ Toluene 38.773 mass%
-Acrylic resin 21.000% by mass
(Made by Mitsubishi Rayon, BR-80)
・ Diimonium salt compound 0.666% by mass
(Nippon Carlit, CIR-RL)
・ Phthalocyanine compound 0.371% by mass
(Nippon Shokubai, IR-10A)
・ Indole compound 0.360% by mass
(Orient Chemical, UA-3901)
・ Silicon surfactant 0.057% by mass
(Dow Corning, Paintad 57; HLB = 6.7)

Comparative Example 1
In Example 1, a near-infrared absorbing film was obtained in the same manner as in Example 1 except that the following coating solution E was used.

(Coating liquid E for near-infrared absorbing layer)
An organic solvent, a resin, a near-infrared absorbing dye, and a surfactant were prepared so as to have the following mass ratio, and undissolved substances were removed with a filter having a nominal filtration accuracy of 1 μm to prepare a coating liquid E. Since the resin is difficult to dissolve, it was dissolved in advance in an organic solvent under heating, and after cooling to room temperature, the dye was added and stirred to dissolve.
・ Methyl ethyl ketone 38.953 mass%
・ Toluene 38.953 mass%
-Acrylic resin 21.000% by mass
(Made by Mitsubishi Rayon, BR-80)
・ Diimonium salt compound 0.666% by mass
(Nippon Carlit, CIR-RL)
・ Phthalocyanine compound 0.371% by mass
(Nippon Shokubai, IR-10A)
・ Silicon surfactant 0.057% by mass
(Dow Corning, Paintad 57; HLB = 6.7)

  Table 1 shows the physical properties of the obtained near-infrared absorbing film. A film having strong absorption in the near infrared region and high transmittance in the visible light region was obtained. The stability over time was good, but the light resistance was poor.

  The near-infrared absorbing film of the present invention has low transmittance in the near-infrared region, high transmittance in the visible light region, little change in quality over time under high temperature and high humidity, and excellent light resistance. By installing this near-infrared absorbing film on the front of the plasma display and using it as a near-infrared absorbing filter, it is possible not only to prevent malfunction of precision equipment using a near-infrared remote controller, but also to display good images for a long time. Therefore, there is little change in quality over time, which can greatly contribute to high reliability of the plasma display.

Claims (5)

  A near-infrared absorbing film in which a near-infrared absorbing layer mainly composed of two or more kinds of near-infrared absorbing pigments containing a diimmonium salt compound and a resin is laminated on a transparent substrate film, and has a transmittance of 30 at a wavelength of 400 nm. % Near-infrared absorbing film characterized by being less than or equal to%.   2. The near-infrared absorbing film according to claim 1, wherein the transmittance at a wavelength of 400 nm is 20% or less.   The near-infrared absorbing film according to claim 1 or 2, wherein the near-infrared absorbing layer further contains a dye having an absorption peak in a wavelength range of 370 nm to 400 nm.   The near-infrared absorbing film according to claim 3, wherein the dye having an absorption peak in a wavelength range of 370 nm to 400 nm is an indole compound.   A near-infrared absorbing filter comprising the near-infrared absorbing film according to claim 1 installed on the front surface of a plasma display.