JP4639803B2 - Near infrared absorbing filter and method for producing wave near infrared absorbing film for plasma display - Google Patents

Description

  The present invention relates to an optical filter that absorbs near-infrared rays, particularly a near-infrared absorbing film suitable as a display filter, a method for producing the same, and a near-infrared absorbing filter. Specifically, a near-infrared absorbing film having high transmittance in the visible light region, absorbing near infrared rays, excellent in color tone stability under high temperature and high humidity, and excellent in flatness, a method for producing the same, and near infrared rays It relates to an absorption filter.

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 optical filter using an infrared absorbing film is used.

As a filter having near-infrared absorption ability, (1) a filter containing metal ions such as copper and iron on phosphoric acid glass, and (2) a layer having a different refractive index is laminated to interfere with transmitted light. An interference filter that transmits a specific wavelength, (3) an acrylic resin filter containing a copper ion in a copolymer, and (4) a filter in which a layer in which a dye is dispersed or dissolved in a resin are 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 (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

  However, some of these methods have the ability to sufficiently block the near-infrared rays emitted from the plasma display, but the quality under high temperature and high humidity, especially the color tone and adhesion of the near-infrared absorbing layer. In terms of stability over time, it was insufficient.

  The object of the present invention has been made to solve the above-mentioned problems of the prior art, has high transmittance in the visible light region, absorbs near infrared rays, and is stable in color tone over time under high temperature and high humidity. It is providing the near-infrared absorption film which is excellent in surface property, and its planarity, its manufacturing method, and a near-infrared absorption filter.

  This invention is made | formed in view of said background art, Comprising: The near-infrared absorption film which was able to solve said subject, its manufacturing method, and a near-infrared absorption filter 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 filter characterized by installing the near-infrared absorption film for plasma displays in the front surface of a plasma display, Comprising: The said near-infrared absorption film for plasma displays is a transparent base material On the film, a near-infrared absorption layer obtained by applying a post-cure treatment after coating and drying a coating solution containing a near-infrared absorbing dye having a maximum absorption at a wavelength of 800 to 1200 nm, a resin and an organic solvent was provided. A near-infrared absorbing film for plasma display, wherein the near-infrared absorbing dye contains at least a diimonium salt compound, the post-curing treatment conditions are 25 ° C. or more and 70 ° C. or less and the product of the treatment time (hr) is 1000. It is a near-infrared absorption filter characterized by being (° C. · hr) or more.

2nd invention is a near-infrared absorption filter as described in 1st invention which has an intermediate | middle layer between a transparent base film and a near-infrared absorption layer.

A third invention is the near-infrared absorption filter according to the first or second invention, wherein the intermediate layer contains a crosslinking agent selected from melamine, epoxy, and isocyanate.

The fourth invention is a method of applying a coating solution containing a near-infrared absorbing dye having a maximum absorption at a wavelength of 800 to 1200 nm, a resin, and an organic solvent on a transparent base film, drying the laminate, and laminating a near-infrared absorbing layer, Further, the near-infrared absorbing filter according to any one of the first to third aspects, wherein the adhesive layer is laminated by a transfer method or a direct method and then post-cured.

5th invention post-cure-processes the near-infrared absorption film which apply | coated and dried the coating liquid containing a near-infrared absorption pigment | dye, resin, and an organic solvent on the transparent base film, and formed the near-infrared absorption layer. A method for producing a near-infrared absorbing film for a plasma display, which is installed on the front surface of a plasma display provided with a near-infrared absorbing layer obtained by the method, wherein the near-infrared absorbing dye contains at least a diimonium salt compound, The post-curing treatment conditions are 25 ° C. or more and 50 ° C. or less, and the product of the treatment time (hr) is 1000 (° C. · hr) or more.

  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 the ability to block near-infrared rays can be maintained even when used for a long time, and the change in color tone is greatly reduced, and the plasma display can be used for a long time.

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.

  A 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 transparent base film is particularly preferably a biaxially stretched film from the viewpoint of strength and the like. 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 give handling properties (for example, winding property after lamination) to the transparent substrate film, it is preferable to contain 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. Moreover, in order to provide various functions as needed, the film may contain a light-resistant agent (ultraviolet ray inhibitor), a pigment, an antistatic agent, and the like.

  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. 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 the handling properties will be poor, but also heat wrinkles will occur on the film when the drying temperature is increased when forming the near-infrared absorbing layer in order to improve durability as described below. Therefore, the flatness tends to be poor. On the other hand, when the thickness is large, not only is there a problem in terms of cost, but flatness due to curling tends to occur when the material is wound and stored in a roll shape.

(Middle layer)
In the near-infrared absorbing film of the present invention, between the transparent substrate film and the near-infrared absorbing layer, adhesion between the transparent substrate film and the near-infrared absorbing layer, in particular, improved adhesion under high temperature and high humidity, Or it is preferable to provide the intermediate | middle layer which consists of resin or a resin composition for the purpose of the transparency improvement of a transparent base film. In addition, when not including particle | grains in a transparent base 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 preferable to select one or more. Specifically, if the resin constituting the transparent base film and the near-infrared absorbing layer is an ester, it is preferable to select a polyester or polyester urethane having a similar structure.

  In addition, it is a preferable embodiment that the resin has a cross-linked structure because adhesion between the base material and the near-infrared absorbing layer, particularly adhesion under high temperature and high humidity can be improved. In order to crosslink the resin, there are a method in which a crosslinking agent is contained in the resin and then heat-treated to form a crosslinked structure, and a method in which a self-crosslinking graft copolymer resin is heat-treated to form a crosslinked structure. Examples of the crosslinking agent include urea, epoxy, melamine, and isocyanate. In particular, when the resin is whitened or reduced in strength under high temperature and high humidity, the effect is noticeable when a resin having a crosslinked structure is used as a constituent material of the intermediate layer.

  When a resin having no cross-linked structure is used as a constituent material of the intermediate layer, adhesion between the transparent base film and the near-infrared absorbing layer due to deterioration, water absorption, and thermal deformation of the resin in a high temperature / high humidity environment In some cases, the near-infrared absorption layer peels off from the transparent base film, and the function as a filter may not be maintained. By using a resin having a crosslinked structure as a constituent material of the intermediate layer, it is possible to improve the glass transition temperature of the resin constituting the intermediate layer, to reduce water absorption, to reduce deterioration of the resin, and to prevent deterioration of adhesion. it can.

  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.

  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 having a maximum absorption at a wavelength of 800 to 1200 nm on a transparent substrate film. The above-mentioned “mainly containing near-infrared absorbing dye and resin” means that the composition 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 composition is preferably 85% by mass or more, particularly preferably 90% by mass or more.

  The near-infrared absorbing dye is a dye having a maximum absorption in the near-infrared region with a wavelength of 800 to 1200 nm, and is a diimmonium-based, phthalocyanine-based, dithiol metal complex-based, naphthalocyanine-based, azo-based, polymethine-based, anthraquinone-based , 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 main reason for the temporal stability of the color tone under high temperature and high humidity, which is the subject of the present invention, is the deterioration of the diimmonium salt compound represented by the general formula (I) under high temperature and high humidity. When the diimmonium salt compound deteriorates under high temperature and high humidity, the compound changes to a compound having absorption in the vicinity of a wavelength of 420 nm, and the near-infrared absorbing layer changes color. Therefore, the near-infrared absorbing film provided with the near-infrared absorbing layer also changes color. In the present invention, it is important to use a diimmonium salt compound and minimize the deterioration of the diimmonium salt compound in order to improve the near-infrared absorptivity.

  The near-infrared absorbing film of the present invention, in addition to the diimonium salt compound represented by the general formula (I), is used in combination with other near-infrared absorbing dyes for the purpose of expanding the absorption range of the near-infrared region and adjusting the color. It is preferable to do.

  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.

  Among these, a phthalocyanine compound and a dithiol metal complex compound in which the dye itself hardly deteriorates under high temperature and high humidity are preferable. When dyes that are prone to degradation are used, not only does the stability of transmittance in the near-infrared region deteriorate with time, but the diimmonium salt compound degrades by acting as a quencher, and the near-infrared absorbing layer becomes yellow. Discolor. Therefore, the near-infrared absorbing film provided with the near-infrared absorbing layer also turns yellow.

  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.

  Moreover, as said dithiol metal complex type compound, the compound shown by the following general formula (II) is suitable, for example.

In the formula, R ^{13 to} R ¹⁶ may be the same or different and each represents a hydrogen atom, a halogen atom, an alkyl group, an alkoxyl group, an aryl group, an aralkyl group, or an amino group. M represents nickel, copper, cobalt, palladium, or platinum.

Specific examples of R ^{13 to} R ^{16 in} the general formula (II) include halogen atoms such as fluorine, chlorine and bromine; 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 Alkyl groups such as ethoxyethyl group and butoxyethyl group; alkoxyl groups such as methoxy group, ethoxy group, propoxy group and butoxy group; aryl such as phenyl group, fluorophenyl group, chlorophenyl group, tolyl group, diethylaminophenyl and naphthyl group Group: benzyl group, p-fluorobenzyl group, p-chlorophenyl group, phenylpropyl group, naphthylethyl Aralkyl groups such as a group; a dimethylamino group, diethylamino group, dipropylamino group, an amino group, such as a dibutylamino group; and the like. As the dithiol metal complex compound of the general formula (II), for example, commercially available products such as SIR-128, SIR-130, SIR-132, SIR-159 manufactured by Mitsui Chemicals are also suitable.

  Examples of cyanine compounds include TZ-103, TZ-104, TZ-105, TZ-109, TZ-111, TZ-114 manufactured by Asahi Denka, CY-9, CY-10, and CY manufactured by Nippon Kayaku. -20, CY-30, IR-301 manufactured by Yamada Chemical, etc. are preferable.

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 pigment 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 to be sufficiently dried, it is necessary to increase the temperature and / or the time for a long time. 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 and 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. Of these, acrylic resins or polyester resins are preferred because of their 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. In the present invention, the glass transition temperature of the resin is not particularly limited as long as it is equal to or higher than the device use temperature, but is particularly preferably 85 ° C. or higher and 160 ° C. or lower. 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 less than 85 ° C., near-infrared absorbing dyes easily move under high temperature and high humidity, so that the dyes or the dyes and the resin easily interact with each other, and the dyes are not modified. It tends to be prominent. For this reason, the spectral characteristics and color tone of the film tend to change.

  On the other hand, when the glass transition temperature of the resin exceeds 160 ° C., when the resin is dissolved in a solvent and applied on a transparent substrate film, the resin must be heated to a sufficient temperature. As a result, the flatness of the base material due to heat wrinkles, and further the deterioration of the pigment occurs. Moreover, when it dries at low temperature, drying time becomes long and productivity worsens, and productivity becomes bad. In addition, there is a possibility that sufficient drying cannot be performed, so that the solvent remains in the coating film, the apparent glass transition temperature of the resin is lowered as described above, and the dye is likely to be modified.

  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, in particular, dents due to minute bubbles and adhesion of foreign matter, etc., 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.

  Moreover, it is preferable that HLB of surfactant is 2-12. The lower limit value of HLB is preferably 3, particularly preferably 4. On the other hand, the upper limit value of 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 the HLB is most likely to occur in the vicinity of 7 and the initial drying is under mild conditions. Easy to convert. 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 neon cut dye, an organic solvent, and, if necessary, a surfactant on a transparent substrate film. The It is important that the coating solution is further diluted with an organic solvent from the viewpoint of coatability.

  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, diacetone alcohol, etc. These may be used alone or in combination of two or more. Can do.

  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 that it is 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 is large, the frequency of occurrence of ridges 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 absorptive power in the near infrared region 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 step, drying is preferably performed at a temperature of 120 ° C. or higher and 180 ° C. or lower from the viewpoint of increasing the temperature higher than the initial drying and reducing the amount of solvent in the coating film. Particularly preferably, the lower limit is 140 ° C and the upper limit is 170 ° C. When the drying temperature in the rate-decreasing drying step 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.

  On the other hand, when dried at a high temperature, not only the flatness of the transparent base film due to heat wrinkles and the decrease in transparency (white turbidity) due to the precipitation of oligomers from the base material, but also the near-infrared absorbing dye is caused by heat. The problem of deterioration tends to occur. Moreover, it is preferable that the time (drying time) for the coated film to pass through the decreasing rate drying step is 5 seconds or more and 180 seconds or less. When the drying time is short, the amount of solvent remaining in the coating film increases, resulting in poor stability over time. On the other hand, when the drying time is long, not only the productivity becomes poor, but also the substrate due to heat wrinkles. Inferior flatness and transparency decrease (white turbidity) due to oligomer precipitation from the substrate easily occur. The upper limit of the passage time is particularly preferably 30 seconds from the viewpoint of productivity and flatness. Near-infrared absorbing dyes deteriorate due to heat. The passing time is preferably 5 seconds or more and 180 seconds or less. When the time is short, the amount of solvent remaining in the coating film increases, resulting in poor stability over time. On the other hand, when the time is long, not only productivity is deteriorated, but heat wrinkles are generated on the substrate. As a result, the flatness becomes poor. 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 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, when the coated surface comes into contact with the roll surface, the slippage is poor, and not only scratches but also curls may occur.

  In the present invention, it is particularly important to perform a post-cure treatment after applying and drying a coating solution containing a near-infrared absorbing dye, a resin and an organic solvent on a transparent substrate film. By performing post-cure, 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 effect obtained by the post-cure treatment is particularly remarkable when an intermediate layer is provided between the near-infrared absorbing layer and the transparent substrate, and further, when the intermediate layer having a cross-linking agent is effective.

  As a result of detailed analysis of the deterioration of the dye under high temperature and high humidity, not only the inside of the near infrared absorption layer but also the deterioration of the dye at the interface between the near infrared absorption layer and the transparent substrate or intermediate layer is a factor. It was found that the deterioration of the pigments easily occurs in a low-temperature and low-humidity environment than the inside of the near-infrared absorbing layer. By performing the post-cure treatment, it is possible to improve the durability under high temperature and high humidity substantially by causing pigment deterioration at the interface between the near-infrared absorbing layer and the transparent substrate film in advance. 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 later. It is preferable to perform post-cure treatment before and after laminating the adhesive layer on the near-infrared absorbing layer in a subsequent step. In particular, when the adhesive layer is laminated on the near-infrared absorbing layer and subjected to post-cure treatment, the residual solvent in the near-infrared absorbing layer is absorbed by the adhesive layer adjacent to the near-infrared absorbing layer, and in the near-infrared absorbing layer Color stability over time tends to be good. When the post-cure treatment is performed after the antireflection film or the electromagnetic wave prevention film is bonded, the residual solvent amount in the near-infrared absorbing layer is hardly lowered, and the effect of the post-cure treatment is reduced.

(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 with a wavelength of 800 to 1200 nm 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 is impossible 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.

  Since the near-infrared absorbing film of the present invention is suitable for display applications, particularly as a front plate filter of a plasma display, it is preferable that the near-infrared absorbing film has a low haze. Specifically, the haze of the near-infrared absorbing film is preferably 1.5% or less, more preferably 1.0% or less. When the haze is high, the display becomes blurred and the quality is lowered. As a method for lowering the haze, it is preferable to reduce the content of particles in the near-infrared absorbing film, particularly the transparent substrate film. In addition, when applying and drying the near-infrared absorbing layer, when the drying conditions are harsh, oligomers in the transparent base film are deposited on the surface and haze is lowered. It is important to adjust the drying conditions.

  It is important that the near-infrared absorbing film has excellent flatness. When there is a circumferential difference in the width direction in the form of a roll, it is difficult to bond to a glass substrate or the like. In addition, when there are tin-like heat wrinkles in the flow direction, the appearance tends to be poor even after bonding. In order to improve the planarity of the near-infrared absorbing film, drying conditions such as reducing the drying conditions when providing the near-infrared absorbing layer on the transparent substrate film and cooling in a state in which the planarity is maintained are set. It is preferable that the tension in the flow direction of the transparent base film at the time of drying, that is, the winding tension at the time of winding in the roll form after drying, is weakened to the extent that production stability can be maintained.

  The color tone of the near-infrared absorption filter is preferably -10.0 to +10.0 in the a value and -10.0 to +10.0 in the b value when expressed in the Lab color system. 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 good coating film appearance so that there is no defect with a diameter of 300 μm or more, more preferably 100 μm. A defect with a 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 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 near-infrared transmittance and the visible-light transmittance even when left for a long period of time under high temperature and high humidity. When the stability over time at 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 electronic equipment using a near infrared remote controller may not be realized. is there.

  In order to improve the stability over time, it is also effective to reduce the amount of residual solvent in the near-infrared absorbing layer in addition to the post-cure treatment of the present invention. In order to reduce the amount of residual solvent in the near infrared absorbing layer, a method for controlling the type of organic solvent used in the coating liquid for forming the near infrared absorbing layer, the thickness of the coating layer, the drying conditions, etc. A method of adjusting the content of the pigment in the resin constituting the absorption layer is suitable. 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. Further, productivity is reduced by a method that does not perform 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.

<Viscosity of coating solution>
The coating solution was adjusted to 20 ° C. and measured using a B-type viscometer (BL) manufactured by Tokyo Keiki Co., Ltd., at a rotor rotational speed of 60 rpm.

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

<Transmissivity>
Using a spectrophotometer (Hitachi U-3500 type), indoor air was measured as a reference for transmittance.

<Color tone>
Using a color difference meter (manufactured by Nippon Denshoku Industries Co., Ltd., ZE-2000), the near-infrared absorbing layer side is irradiated with light. Measured at viewing angle.

<Color tone stability over time (ΔE)>
It processed for 48 hours in the atmosphere of temperature 80 degreeC and humidity 95%, the color tone of the near-infrared absorption film before and behind a process was measured, and the variation | change_quantity 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)

<Adhesion>
The adhesion was measured by a test method in accordance with the provisions of JIS K 5400 8.5.1. Specifically, after the near-infrared absorbing film was treated in an atmosphere of 80 ° C. and 95% humidity for 48 hours, 100 square scratches were cut from the side where the near-infrared absorbing layer was laminated, and a cutter with a gap interval of 2 mm. Attached using a guide, cellophane adhesive tape (Nichiban "405", 24mm width) is attached to the scratched surface of the grid and rubbed with an acrylic plate (Sumitomo Chemical "Sumipex") to adhere completely Then, the situation when peeled off vertically was observed and observed. Moreover, the same evaluation was performed twice in the same place as needed.
(Double-circle): Although the same location was evaluated twice, adhesiveness did not peel in any case.
○: There was no peeled-off grid, but there was a peeled-off grid at the second time.
(Triangle | delta): Although the peeled square exists, the peeled square is less than 10 squares.
X: The 10th mesh or more peeled.

<Flatness>
A near-infrared absorbing film was placed on a flat table and visually observed under a three-wavelength fluorescent lamp.
○: There is no film floating from the table, and there is no distortion in the shape of the fluorescent lamp reflected on the surface.
Δ: The film does not float from the table, but the shape of the fluorescent lamp reflected on the surface appears distorted.
X: The film is lifted from the table.

Example 1
(Base material)
A polyethylene terephthalate resin having an intrinsic viscosity of 0.62 dl / g is charged into a twin-screw extruder, melt-extruded from a T-die at 290 ° C., and solidified while being applied with static electricity on a cooled rotating metal roll. A stretched sheet was obtained.
Next, the unstretched sheet was heated to 90 ° C. with a roll stretching machine and longitudinally stretched by 3.5 times, and then the coating amount after drying the following coating liquid A on the longitudinally stretched film was 0.5 g / It was applied to both sides so as to be m ^2, and passed for 20 seconds under a hot air of 10 m / second and 120 ° C. to form an intermediate layer. Further, the film was heated by a tenter to 140 ° C. and transversely stretched 3.7 times, and then heat treated while being relaxed by 5% in the width (lateral) direction at 235 ° C. to obtain a film. The obtained biaxially stretched polyethylene terephthalate film having an intermediate layer had a thickness of 100 μm, a total light transmittance of 90.2%, and a haze of 0.5%.

(Composition of coating liquid A for intermediate layer)
・ Ion-exchanged water 50.0% by mass
・ Isopropyl alcohol 28.9% by mass
・ Acrylic-melamine resin 10.0% by mass
(Nippon Carbide Industries, A-08, solid content concentration: 46% by mass)
・ Polyester resin 10.0% by mass
(Toyobo, MD-1250, solid content: 30% by mass)
・ Organic particles (polymethacrylate cross-linked product) 1.0% by mass
(Nippon Shokubai, Eposta MA1001)
・ Surfactant 0.1% by mass
(Paintad 32, manufactured by Dow Corning Co., Ltd.)

(Lamination of near-infrared absorbing layer)
A slanted gravure with a diameter of 60 cm is used so that the coating amount after drying the following coating solution B (solid content concentration: 21.9% by mass, viscosity: 20 cps) on the above intermediate layer is 9.2 g / m ^2. The coating is applied in a reverse mode and dried by passing 20 seconds with hot air of 5 m / second at 40 ° C., 20 seconds with hot air of 20 m / second at 160 ° C., and 10 seconds with hot air of 20 m / second at 90 ° C. A near infrared absorption layer was laminated.

(Coating solution B for near-infrared absorbing layer)
The coating solution B for the near-infrared absorbing layer was prepared so as to have the following mass ratio, and the undissolved material was removed with a filter having a nominal filtration accuracy of 1 μm. 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 39.073 mass%
・ Toluene 37.073 mass%
・ Acrylic resin 20.773 mass%
(Made by Mitsubishi Rayon, BR-80)
・ Diimonium salt compound 0.6588% by mass
(Nippon Carlit, CIR-1085)
-Phthalocyanine compound 0.3668% by mass
(Nippon Shokubai, IR-10A)
・ Silicone-based surfactant 0.0565% by mass
(Dow Corning, Paintad 57; HLB = 6.7)

(Post cure processing)
The near-infrared absorbing film was subjected to a post-cure treatment for 100 hours in an environment of 40 ° C.

  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 color tone stability over time was also good.

Examples 2-6
In Example 1, a near-infrared absorbing film was obtained in the same manner as in Example 1 except that the post-cure treatment was performed under the conditions described in Table 1.
Table 1 shows the physical properties of the obtained near-infrared absorbing film. Examples 2 to 6 were within the scope of the present invention, and the color tone was stable over time.

Comparative Example 1
In Example 1, a near-infrared absorbing film was obtained in the same manner as in Example 1 except that the post-cure treatment was not performed.
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. However, the color tone stability over time was poor.

Comparative Examples 2-4
In Example 1, a near-infrared absorbing film was obtained in the same manner as in Example 1 except that the post-cure treatment was performed under the conditions described in Table 1.

Comparative Example 5
In Comparative Example 1, the coating liquid B was applied, heated at 40 ° C. with hot air of 5 m / second for 20 seconds, heated at 180 ° C. with hot air of 20 m / second for 20 seconds, and further heated at 90 ° C. with hot air of 20 m / second for 10 seconds. A near-infrared absorbing film was obtained in the same manner as Comparative Example 1 except that it was allowed to pass through and dried.
Table 1 shows the physical properties of the obtained near-infrared absorbing film. Since the drying conditions were strengthened to reduce the amount of residual solvent in the near-infrared absorbing layer, the color tone stability over time was good. However, since the drying was strong, the near-infrared absorbing dye deteriorated during drying, and the transmittance at 950 nm was increased, and the flatness of the film was poor due to heat wrinkles.

Example 7
In Example 1, the near-infrared absorption film was obtained like Example 1 except having formed the intermediate | middle layer using the following coating liquid C.
(Composition of coating liquid C for intermediate layer)
・ Ion-exchanged water 50.0% by mass
・ Isopropyl alcohol 28.9% by mass
-Melamine-containing self-crosslinking acrylic resin 20.0% by mass
(Nippon Carbide Industries, A-08, solid content concentration: 46% by mass)
・ Organic particles (polymethacrylate cross-linked product) 1.0% by mass
(Nippon Shokubai, Eposta MA1001)
・ Surfactant 0.1% by mass
(Paintad 32, manufactured by Dow Corning Co., Ltd.)

Example 8
In Example 1, the near-infrared absorption film was obtained like Example 1 except having formed the intermediate | middle layer using the following coating liquid D.
(Composition of coating solution D for intermediate layer)
・ Ion-exchanged water 50.0% by mass
・ Isopropyl alcohol 28.9% by mass
・ Isocyanate-containing self-crosslinking urethane resin 20.0% by mass
(Daiichi Kogyo Seiyaku, H-3, solid concentration: 40% by mass)
・ Organic particles (polymethacrylate cross-linked product) 1.0% by mass
(Nippon Shokubai, Eposta MA1001)
・ Surfactant 0.1% by mass
(Paintad 32, manufactured by Dow Corning Co., Ltd.)

Example 9
In Example 1, a near-infrared absorbing film was obtained in the same manner as in Example 1 except that the intermediate layer was formed using the following coating liquid E.
(Composition of coating liquid E for intermediate layer)
・ Ion-exchanged water 50.0% by mass
・ Isopropyl alcohol 28.9% by mass
・ Isocyanate-containing self-crosslinking urethane resin 10.0% by mass
(Daiichi Kogyo Seiyaku, H-3, solid concentration: 40% by mass)
・ Polyester resin 10.0% by mass
(Toyobo, MD-1250, solid content: 30% by mass)
・ Organic particles (polymethacrylate cross-linked product) 1.0% by mass
(Nippon Shokubai, Eposta MA1001)
・ Surfactant 0.1% by mass
(Paintad 32, manufactured by Dow Corning Co., Ltd.)

Example 10
In Example 1, a near-infrared absorbing film was obtained in the same manner as in Example 1 except that the intermediate layer was formed using the following coating solution F.
(Composition of coating solution F for intermediate layer)
・ Ion-exchanged water 50.0% by mass
・ Isopropyl alcohol 28.9% by mass
・ Polyester resin 20.0% by mass
(Toyobo, MD-1250, solid content: 30% by mass)
・ Organic particles (polymethacrylate cross-linked product) 1.0% by mass
(Nippon Shokubai, Eposta MA1001)
・ Surfactant 0.1% by mass
(Paintad 32, manufactured by Dow Corning Co., Ltd.)

Comparative Example 6
In Example 10, a near-infrared absorbing film was obtained in the same manner as in Example 10 except that the post-cure treatment was not performed.

  Table 2 shows the physical properties of the near-infrared absorbing films obtained in Examples 7 to 10 and Comparative Example 6. When an intermediate layer having a crosslinking agent was used, the adhesion was good and the color tone was stable over time. When an intermediate layer having no crosslinking agent was used, there was a slight problem in adhesion, but the color tone stability over time was good. In Comparative Example 6, no post-cure was performed, and since no cross-linking agent was present in the intermediate layer, the color tone was stable over time, but the adhesion was poor.

Example 11
On the polyethylene terephthalate film (Toyobo Co., Ltd., E7002) subjected to the release treatment, the following adhesive layer forming coating solution G was applied so that the coating amount after drying was 25 g / m ² , at 100 ° C. Dried for 1 minute. Next, the pressure-sensitive adhesive layer was pressure-bonded to the near-infrared absorbing layer side of the near-infrared absorbing film before the post-cure treatment of Example 1, and the pressure-sensitive adhesive layer was laminated. Next, post-curing treatment was performed for 100 hours in an environment of 40 ° C. to obtain a near-infrared absorbing film with an adhesive layer.
(Composition of the coating solution G for forming the adhesive layer)
・ Acrylic acid ester 96.00 mass%
(Nippon Carbide Industries, KP-1420, solid content 40% by mass)
・ Melamine resin 2.0% by mass
(Nippon Carbide Industries, CK-300)
・ Melamine resin 2.0% by mass
(Nippon Carbide Industries, CK-902)

Example 12
In Example 11, a near-infrared absorbing film was obtained in the same manner as in Example 11 except that the post-cure treatment was performed in an environment of 40 ° C. for 200 hours.

Example 13
In Example 11, a near-infrared absorbing film was obtained in the same manner as in Example 11 except that the post-cure treatment was performed for 1000 hours in an environment of 40 ° C.

Comparative Example 7
In Example 11, a near-infrared absorbing film was obtained in the same manner as in Example 11 except that the post cure treatment was not performed.

Comparative Example 8
In Example 11, a near-infrared absorbing film was obtained in the same manner as in Example 11 except that the post-cure treatment was performed in an environment of 40 ° C. for 20 hours.

  Table 3 shows the physical properties of the near-infrared absorbing films obtained in Examples 11 to 13 and Comparative Examples 7 and 8. When a pressure-sensitive adhesive layer is formed on the near infrared absorption layer, the temporal stability of the color tone becomes poor, but the temporal stability of the color tone is improved as compared with the case where the pressure-sensitive adhesive layer is not laminated by post-cure treatment.

  The near-infrared absorbing film of the present invention has high transmittance in the visible light region, low transmittance in the near-infrared region, good color tone stability over time under high temperature and high humidity, and excellent flatness. By installing it on the front of the plasma display, it is possible to express a good image, and it is possible to prevent malfunction of precision equipment for a long time using a near infrared remote controller, which contributes to the industry.

Claims (5)

A near-infrared absorbing filter, characterized in that a near-infrared absorbing film for plasma display is installed on the front surface of the plasma display,
After the near-infrared absorbing film for plasma display is applied on a transparent substrate film and coated with a coating solution containing a near-infrared absorbing dye having a maximum absorption at a wavelength of 800 to 1200 nm, a resin, and an organic solvent, and then dried. A near-infrared absorbing film for a plasma display provided with a near-infrared absorbing layer obtained by processing, wherein the near-infrared absorbing dye contains at least a diimonium salt compound, and the post-cure processing conditions are 25 ° C. or more and 70 A near-infrared absorption filter characterized by having a product of 1000 (° C. · hr) or more at a temperature equal to or lower than ° C. and a treatment time (hr). The near-infrared absorption filter according to claim 1, further comprising an intermediate layer between the transparent substrate film and the near-infrared absorption layer. The near-infrared absorbing filter according to claim 1 or 2, wherein the intermediate layer contains a crosslinking agent selected from melamine, epoxy, and isocyanate. A coating solution containing a near-infrared absorbing dye, resin, and organic solvent having a maximum absorption at a wavelength of 800 to 1200 nm is coated on a transparent substrate film, dried, and a near-infrared absorbing layer is laminated, and further an adhesive layer is transferred. Alternatively, the near-infrared absorption filter according to any one of claims 1 to 3, wherein the post-cure treatment is performed after laminating by the direct method. A near-infrared absorbing layer obtained by applying a coating solution containing a near-infrared absorbing dye having a maximum absorption at a wavelength of 800 to 1200 nm, a resin, and an organic solvent on a transparent substrate film, drying, and then post-curing. A near-infrared absorbing film for plasma display, which is installed on the front surface of a plasma display provided with the above-mentioned, wherein the near-infrared absorbing dye contains at least a diimonium salt compound, and the heat treatment conditions for the post-cure treatment Is 25 ° C. or more and 50 ° C. or less, and the product of the treatment time (hr) is 1000 (° C. · hr) or more.