JP6673219B2 - Laminated film - Google Patents

Description

  The present invention relates to a laminated film.

  Generally, a laminated film in which a high refractive index layer and a low refractive index layer are alternately laminated by adjusting their optical film thickness is theoretically supported to selectively reflect light of a specific wavelength, It is used as a laminated film that transmits visible light and selectively reflects near infrared light. Such a laminated film is used as a reflective film for shielding heat rays used for windows of buildings, members for vehicles, and the like.

  However, in the infrared (heat ray) shielding film in which such a heat ray reflective film is formed on a film, it is sometimes difficult to sufficiently shield the infrared region only with the laminated film in consideration of productivity and optical characteristics. . With respect to such a problem, it is possible to correct transmitted light by providing a layer in which an infrared absorbing agent having an infrared absorbing ability is mixed in the film. As a technique as described above, for example, in Japanese Patent Application Publication No. 2008-528313, an infrared reflective layer in which a first polymer layer and a second polymer layer are alternately laminated, and an infrared reflective layer adjacent to the infrared reflective layer Has proposed an infrared reflective multilayer film including an infrared light absorbing nanoparticle layer that is laminated as follows. Here, the infrared light absorbing nanoparticle layer contains antimony-doped tin oxide (hereinafter, ATO), indium tin oxide (hereinafter, ITO), and the like, which are infrared absorbers.

  Further, Japanese Patent Application Laid-Open No. 2008-200983 discloses a near-infrared ray shielding film having excellent near-infrared ray shielding property and visible light ray transmissivity using cesium-containing composite tungsten oxide (CWO) as an infrared ray absorbing agent.

  As described in JP-T-2008-528313, a multilayer film having a high effect of shielding infrared rays is provided by providing an infrared ray absorbing nanoparticle layer containing an infrared ray absorbent.

  However, as disclosed in JP-T-2008-528313, when the infrared light absorbing nanoparticle layer containing the infrared absorbing agent is exposed to sunlight for a long time under high humidity, discoloration and cracks ( Cracks). It was also found that discoloration occurs when exposed to acid rain for a long time.

  Further, it was found that when CWO was used as in JP-A-2008-200383, the heat ray shielding performance was high, but the color changed when exposed to sunlight for a long time under high humidity. It was also found that discoloration occurs when exposed to acid rain for a long time.

  Therefore, the present invention has been made in view of the above circumstances, in a laminated film having a layer containing an infrared absorber, the occurrence of cracks and discoloration even under a high humidity environment exposed to sunlight, is suppressed, sulfuration resistance An object is to provide an excellent laminated film. Another object of the present invention is to provide a laminated film having a layer containing an infrared absorber, which can maintain an infrared shielding effect even in a high humidity environment exposed to sunlight. Still another object of the present invention is to provide a laminated film having a layer containing an infrared absorber, which can reduce haze even under a high humidity environment exposed to sunlight.

  The present inventors have conducted intensive studies in order to solve the above problems, and as a result, it has been found that the object of the present invention can be achieved by adopting the following configuration.

  That is, the above object of the present invention is solved by the following means.

1. A substrate,
An infrared absorber, a resin, and an infrared absorbing layer containing an antioxidant, disposed on one surface of the base material,
A laminated film in which the surface pH of the surface of the infrared absorbing layer opposite to the substrate is 6.5 or more.

  2. 2. The laminated film according to the above 1, wherein the infrared absorber is a cesium-containing composite tungsten oxide.

  3. 3. The laminated film according to the above 1 or 2, wherein the antioxidant is one or more selected from the group consisting of a phenolic antioxidant and a hindered amine antioxidant.

  4. The laminated film according to any one of the above items 1 to 3, wherein the infrared absorbing layer is obtained by curing a composition containing an ultraviolet curable resin and a photopolymerization initiator.

  5. Any one of the above-described items 1 to 4, further comprising a dielectric multilayer film in which a low-refractive-index layer and a high-refractive-index layer are alternately laminated, and further includes a dielectric multilayer film having at least one reflection peak in a wavelength range of 800 to 1300 nm. The laminated film according to the above.

  Hereinafter, embodiments of the present invention will be described.

  According to the first embodiment of the present invention, a substrate and, disposed on one surface of the substrate, an infrared absorbing agent, a resin, and an infrared absorbing layer containing an antioxidant, A laminated film is provided, wherein the film surface pH of the surface of the infrared absorption layer opposite to the substrate is 6.5 or more.

  ADVANTAGE OF THE INVENTION According to this invention, in the laminated film which has a layer containing an infrared absorber, generation | occurrence | production of a crack and discoloration are suppressed also in a high humidity environment where sunlight shines, and the laminated film excellent in sulfidation resistance is provided.

  The laminated film according to the present invention has an infrared absorbing layer containing an infrared absorbing agent and a resin. Here, as in the technique described in JP-T-2008-528313, a laminated film having an infrared absorbing layer containing an infrared absorbing agent is produced, and the laminated film is exposed to sunlight for a long time under high humidity. It was found that discoloration and cracks occurred.

  When sunlight is irradiated to the infrared absorbing layer containing the infrared absorbing agent, the infrared absorbing agent absorbs infrared rays and is converted into heat. At this time, the resin in the vicinity of the infrared absorbing agent expands at high temperature, but expands and contracts in the resin outside the vicinity, causing distortion inside the infrared absorbing layer. It is presumed that cracks are likely to occur due to repeated expansion and contraction.

  On the other hand, according to the present invention, by adding the antioxidant, the radicals in the resin can be captured and the deterioration of the resin can be prevented. Further, by setting the film surface pH to 6.5 or more, it is possible to moderate the deterioration of the antioxidant and enhance the effect of preventing the deterioration of the resin. As a result, it is considered that the occurrence of cracks can be suppressed.

  In addition, it was found that the transmittance of the infrared absorbing layer containing the infrared absorbing agent was changed by exposure to sunlight or a high humidity environment. For example, infrared absorbers such as ATO and antimony-doped zinc oxide (AZO) have reduced transmittance (color) under sunlight exposure. On the other hand, the transmittance of an infrared absorber such as CWO does not change under exposure to sunlight, but the transmittance increases (decolorizes) under a high humidity environment. As described above, since the transmittance of the infrared absorbing agent changes due to exposure to sunlight or high humidity, discoloration of the laminated film occurs.

  This is because the infrared absorbing agent contained in the infrared absorbing layer changes its electronic state as a result of being exposed to sunlight for a long period of time, resulting in a change in the light absorbing region and discoloration of the infrared absorbing layer (when the infrared absorbing agent is In the case of ATO or AZO, it is presumed to cause coloring. On the other hand, by adding an antioxidant, the electronic state of the infrared absorbing agent can be kept in the initial state, and thus the discoloration of the infrared absorbing layer (when the infrared absorbing agent is ATO, AZO, etc., ) Can be effectively suppressed. Further, it is considered that by setting the film surface pH of the infrared absorbing layer to 6.5 or more, the deterioration of the antioxidant is moderated, and the effect of the antioxidant can be sufficiently obtained.

  Further, when the infrared absorbing layer is irradiated with sunlight, radicals are generated in the resin under the influence of ultraviolet rays, and the resin is deteriorated. At this time, in a high-humidity environment, peroxides are generated due to participation of oxygen and moisture, and the infrared absorbing layer is easily acidified. When the infrared absorber is a cesium-containing composite tungsten oxide, if the periphery of the infrared absorber particles is acidic, cesium is desorbed due to desorption, but the decolorization is suppressed by setting the film surface pH to 6.5 or more. It is thought that we can do it. It is considered that the change in color can be further reduced by adding an antioxidant to suppress the deterioration of the resin.

  Hereinafter, the components of the laminated film of the present invention will be described in detail. In the following, when the low refractive index layer and the high refractive index layer are not distinguished, they are referred to as a “refractive index layer” as a concept including both.

  In this specification, “X to Y” indicating a range means “X or more and Y or less”. Unless otherwise specified, the operation, physical properties, and the like are measured under conditions of room temperature (20 to 25 ° C.) / Relative humidity of 40 to 50% RH.

(Laminated film)
The laminated film according to the present invention has a base material and an infrared absorption layer disposed on one surface of the base material. The infrared absorbing layer may be arranged adjacent to the base material, or another layer (functional layer) may be interposed between the base material and the infrared absorbing layer. Further, it is preferable that the infrared absorbing layer is disposed on a surface on which light is incident, from the viewpoint of the durability of other layers included in the laminated film.

  One of the features of the laminated film of the present invention is that the laminated film has an infrared absorbing layer, and the film surface pH of the surface of the infrared absorbing layer opposite to the substrate is 6.5 or more. Hereinafter, first, the infrared absorbing layer will be described in detail.

[Infrared absorbing layer]
Since the laminated film according to the present invention has the infrared absorbing layer, an infrared shielding effect is provided, and the infrared shielding effect can be improved. The infrared absorbing layer is a layer having an ability to absorb light in the near infrared region having a wavelength of 800 to 2500 nm and includes an infrared absorbing agent, a resin, and an antioxidant. Further, the infrared absorbing layer may contain other additives in order to provide other functions or to improve various characteristics.

  In the laminated film according to the present invention, the film surface pH of the infrared absorbing layer is 6.5 or more. The film surface pH is the pH of the surface of the infrared absorbing layer laminated on the substrate opposite to the surface of the substrate, and the infrared absorbing layer formed by applying a coating solution for the infrared absorbing layer, drying it, or curing it with ultraviolet light. For the film surface of the layer. In this specification, a specific method for measuring the film surface pH is in accordance with the method described in Examples.

  The upper limit of the film surface pH of the infrared absorbing layer is not particularly limited, but is preferably 11 or less because the workability is good. In addition, it has the effect of suppressing acidification of the resin around the infrared absorbing agent due to resin deterioration and suppressing coloring of the infrared absorbing material due to light excitation.

  Suitable film surface pH depends on the type of infrared absorber and antioxidant used and the desired performance. For example, if the film surface pH is 6.5 or more, a neutral to weakly alkaline atmosphere may be used. Deterioration can be moderated, and the effect of suppressing discoloration in a high humidity environment exposed to sunlight is excellent.

  Further, more preferably, the film surface pH of the infrared absorbing layer is 7.5 to 10.5. When the pH of the film surface is 7.5 to 10.5, since the atmosphere is an alkaline atmosphere, the discoloration suppressing effect due to the charge stabilization of the particles of the cesium-containing composite tungsten oxide is particularly excellent. More preferably, the film surface pH of the infrared absorbing layer is 8.5 to 9.5.

  In a preferred embodiment of the present invention, the infrared absorbing layer contains a cesium-containing composite tungsten oxide as an infrared absorbing agent, and the infrared absorbing layer has a film surface pH of 7.5 to 10.5.

  The method for forming the infrared absorbing layer will be described later. The infrared absorbing layer is formed by coating a coating liquid containing an infrared absorbing agent, an antioxidant and a resin, an infrared absorbing agent, an antioxidant, and an active energy ray-curable resin. Any of a film obtained by applying a coating liquid containing a compound (such as an ultraviolet-curable resin) and a photopolymerization initiator and curing by applying ultraviolet light may be used. Here, the film surface pH of the infrared absorbing layer can be controlled by adjusting the pH of the coating solution.

  The thickness of the infrared absorbing layer is preferably 1 μm to 20 μm, more preferably 3 μm to 15 μm. If it is 1 μm or more, the infrared absorbing ability tends to be improved, while if it is 20 μm or less, the crack resistance of the coating film is improved. When the thickness is 1 to 20 μm, the effect of reducing haze can be obtained, and the effect of suppressing discoloration can be further improved while suppressing the occurrence of cracks.

(Infrared absorber)
In the present invention, the infrared absorbing layer contains an infrared absorbing agent. Here, the "infrared absorbing agent" is not particularly limited as long as it has a higher infrared absorbing ability than the resin material constituting the laminated film, and the infrared absorbing agent generally added to a transparent resin is used. Can be used. Here, as the infrared absorbing agent, a solution obtained by dissolving and dispersing 1 part by mass of a compound in 100 parts by mass of a good solvent has a light transmittance of 50% or less in a part or the whole of a near infrared wavelength region of 800 to 2500 nm. And more preferably 30% or less.

  Since the infrared absorbing layer contains the infrared absorbing agent, the infrared absorbing layer absorbs the infrared light. At this time, the infrared absorbing agent absorbs the infrared light and generates heat (heat storage) to expand the resin near the infrared absorbing agent particles. In addition, the resin in a region away from the infrared absorbent particles deteriorates and shrinks, so that distortion occurs and cracks are easily generated. However, according to the present invention, by adding an antioxidant and controlling the film surface pH of the infrared absorbing layer to 6.5 or more, the generation of cracks is effectively suppressed even under irradiation of sunlight. can do.

  In addition, when the infrared absorber is exposed to sunlight for a long time or exposed to high humidity, its light absorption characteristics change, which causes discoloration of the film. However, discoloration (coloring, etc.) is also suppressed by adding an antioxidant and controlling the film surface pH of the infrared absorbing layer to 6.5 or more.

  The infrared absorbing agent contained in the infrared absorbing layer is not particularly limited, and may be an inorganic infrared absorbing agent or an organic infrared absorbing agent.

Examples of inorganic infrared absorbers that can be included in the infrared absorption layer include tin oxide, antimony-doped tin oxide (ATO), indium-doped tin oxide (ITO), and cesium-containing composite tungsten oxide (cesium-doped tungsten oxide (CWO)). , Lanthanum hexaboride (LaB ₆ ), zinc oxide, antimony-doped zinc oxide (AZO), indium-doped zinc oxide (IZO), gallium-doped zinc oxide (GZO), aluminum-doped zinc oxide, nickel complex compound Is mentioned.

Specific examples of these trade names include, as zinc oxide, Cellnax series (manufactured by Nissan Chemical Industries, Ltd.) and Pazette series (manufactured by Hakusuiteku Co., Ltd.); and as tin oxide, ATO dispersion (SR35M Advanced Nano Products). Co., Ltd.), ITO Dispersion (Mitsubishi Materials Electronic Chemicals), KH Series (Sumitomo Metal Mining); CWO Dispersion (YMF-02A, Sumitomo Metal Mining) as Cesium-Containing Tungsten Oxide; as lanthanum, LaB ₆ dispersion (manufactured by KHF-7AH Sumitomo Metal Mining Co., Ltd.).

Further, as the inorganic infrared absorbing agent, those composed of Cd / Se, GaN, Y ₂ O ₃ , Au, Ag and the like can be used.

  The average particle diameter of the inorganic infrared absorber is preferably from 5 to 150 nm, more preferably from 10 to 120 nm. When the thickness is 5 nm or more, the dispersibility in the resin and the infrared absorptivity are favorably maintained, and when the thickness is 150 nm or less, a decrease in visible light transmittance can be suppressed. The average particle diameter is measured by taking an image with a transmission electron microscope, randomly extracting, for example, 50 particles, measuring the particle diameter, and averaging the particles. When the shape of the particles is not spherical, it is defined as a value calculated by measuring the major axis.

  Examples of organic infrared absorbers that can be included in the infrared absorption layer include conductive polymers such as polyacetylene compounds, polyparaphenylene compounds, polyphenylenevinylene compounds, polypyrroles, polythiophene compounds, and PEDOT-PSS; immonium compounds; phthalocyanine compounds; Conductive carbon materials such as acetylene black, Ketjen Black (registered trademark), and carbon black are exemplified.

  Moreover, as these specific trade names, Denatoron P-502S, P-502RG, Denattron PT-432, NIR-IM1, NIR-AM1 (manufactured by Nagase ChemteX Corporation), Cleios CPP 105D, CPP 134.18D, CPP141D, CPG130.6 (produced by Heraeus), SEPLEGYDA series (produced by Shin-Etsu Polymer), Lumogen series (produced by BASF) and the like.

  Among the above, from the viewpoint of dispersibility in the infrared absorbing layer and infrared absorbing ability, the infrared absorbing agent is antimony-doped tin oxide, indium-doped tin oxide, cesium-containing composite tungsten oxide, lanthanum hexaboride, antimony-doped It is preferable to use one or more selected from the group consisting of zinc oxide, indium-doped zinc oxide, a conductive polymer, and a conductive carbon material. In particular, the infrared absorbent is preferably a cesium-containing composite tungsten oxide. The cesium-containing composite tungsten oxide has excellent optical properties as an infrared absorber, and also has excellent weather resistance, such as being hardly colored even when exposed to sunlight.

The composition of the cesium-containing composite tungsten oxide is not particularly limited, but from the viewpoint of stability, it is generally preferably an oxide represented by the general formula: Cs _x W _y O _z , and Japanese Patent Application Laid-Open No. 2013-64042. And those similar to those described in JP-A-2010-215451 can be used. In the above general formula, Cs is cesium, W is tungsten, and O is oxygen. x, y, and z are such that the composition of tungsten and Cs (the composition of Cs with respect to W, x / y) satisfies the relationship of 0.001 ≦ x / y ≦ 1, and the composition of W and O (the composition of O with respect to W) The composition, z / y) preferably satisfies the relationship of 2.2 ≦ z / y ≦ 3.

  The shape of the cesium-containing composite tungsten oxide is not particularly limited, and may have any structure such as a particle shape, a spherical shape, a rod shape, a needle shape, a plate shape, a column shape, an irregular shape, a scaly shape, and a spindle shape. It is. The size of the cesium-containing composite tungsten oxide particles is not particularly limited. However, when the cesium-containing composite tungsten oxide is in the form of particles, the average particle diameter (average primary particle diameter, diameter) suppresses the reflection of visible light. In addition, the thickness is preferably from 5 to 150 nm, more preferably from 5 to 100 nm, since the heat ray absorbing effect can be ensured, and the haze does not deteriorate due to scattering, and the transparency can be ensured. The average particle diameter is determined by observing the particles themselves or particles appearing on the cross section or surface of the refractive index layer with an electron microscope, measuring the particle diameter of 1,000 arbitrary particles, and calculating the simple average value (number average). Is required. Here, the particle diameter of each particle is represented by a diameter assuming a circle equal to its projected area.

  In addition, the said infrared absorber can be used individually or in combination of 2 or more types.

  The content of the infrared absorbing agent in the infrared absorbing layer is not particularly limited, but from the viewpoint of adjusting physical properties such as film strength and film elasticity and optical properties such as transmittance to desired values, the total mass of the infrared absorbing layer is (In terms of solid content when the total mass of the infrared absorbing layer is 100% by mass), preferably 1 to 80% by mass, more preferably 5 to 70% by mass. When the content is 1% by mass or more, a sufficient infrared absorbing effect can be obtained, and when the content is 80% by mass or less, a sufficient amount of visible light can be transmitted.

(resin)
In the present invention, the infrared absorbing layer contains a resin together with the infrared absorbing agent. As the resin, any of a water-soluble resin and an organic solvent-soluble resin can be used.

  It is preferable to contain a water-soluble resin from the viewpoint of reducing environmental load and process load. The water-soluble resin is not particularly limited, and examples thereof include polyvinyl alcohol-based resins, gelatin, celluloses, thickening polysaccharides, and polymers having a reactive functional group. In this specification, “water-soluble” means a G2 glass filter (maximum pores: 40 to 50 μm) when dissolved in water to a concentration of 0.5% by mass at a temperature at which the substance is most dissolved. Means that the mass of the insoluble matter to be separated by filtration is within 50% by mass of the added polymer.

  On the other hand, from the viewpoint that the effect of humidity fluctuation of the film is reduced, it is preferable to contain an organic solvent-soluble resin. The organic solvent-soluble resin is not particularly limited. However, acrylic resin, urethane-modified acrylic resin, polyurethane resin, polyester resin, melamine resin, polyvinyl acetate, cellulose acetate, polycarbonate, polyacetal, polybutyral, polyamide (nylon) resin, polystyrene Examples of the resin include a resin, a polyimide resin, an ABS resin, polyvinylidene fluoride, and an ultraviolet curable resin.

  Examples of the ultraviolet curable resin include (meth) acrylate, urethane acrylate, polyester acrylate, epoxy acrylate, epoxy resin, and oxetane resin, and these can also be used as a solventless resin composition.

  When the above-mentioned ultraviolet curable resin is used, it is preferable to add a photopolymerization initiator in order to promote curing.

  As a photopolymerization initiator, acetophenones, benzophenones, ketals, anthraquinones, thioxanthones, azo compounds, peroxides, 2,3-dialkyldione compounds, disulfide compounds, thiuram compounds, fluoroamine compounds Are used. Specific examples of the photopolymerization initiator include 2,2′-diethoxyacetophenone, p-dimethylacetophenone, 1-hydroxycyclohexylphenylketone, 1-hydroxydimethylphenylketone, 2-methyl-4′-methylthio-2-mol. Acetophenones such as folinopropiophenone, 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butanone 1, benzoin such as benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, and benzyl dimethyl ketal , Benzophenones such as benzophenone, 2,4'-dichlorobenzophenone, 4,4'-dichlorobenzophenone, and p-chlorobenzophenone; 2,4,6-trimethylbenzoyldiphenylphosphine oxide; Rakinon such, there is such as thioxanthones. These photopolymerization initiators may be used alone, in combination of two or more, or in a eutectic mixture. In particular, it is preferable to use acetophenones in view of the stability of the curable composition, the polymerization reactivity, and the like.

  As such a photopolymerization initiator, a commercially available product may be used. For example, preferable examples include Irgacure (registered trademark) 819, 184, 907, and 651 manufactured by BASF Japan.

  Note that, depending on the type of the resin constituting the infrared absorbing layer, the infrared absorbing layer can be provided with abrasion resistance (hard coat property). Therefore, the infrared absorbing layer also serves as a hard coat layer described later. You may. For example, in a preferred embodiment of the present invention, the infrared absorbing layer is formed by curing a composition containing an ultraviolet curable resin and a photopolymerization initiator. By using the above-mentioned ultraviolet curable resin, a hard coat property can be imparted to the infrared absorbing layer. Here, the hard coat property means that the pencil hardness according to JIS K 5600-5-4 is H or more, preferably 2H or more. The hardness of the hard coat layer or the hardness of the infrared absorption layer also serving as the hard coat layer is preferably from the viewpoint of scratch resistance as long as the layer is not broken or peeled off when an external stress such as bending is applied.

(Antioxidant)
In the present invention, the infrared absorbing layer contains an antioxidant. When the infrared absorbing layer contains an antioxidant, it is possible to capture radicals and prevent deterioration of the resin. Further, it is possible to avoid the occurrence of peroxide due to the involvement of oxygen and water due to the deterioration of the resin and the periphery of the infrared absorbent particles being acidified to cause decolorization.

  The type of antioxidant is not particularly limited, and known antioxidants can be used. Preferred antioxidants include phenolic antioxidants, thiol antioxidants, and phosphite antioxidants. And hindered amine antioxidants.

  Examples of the phenolic antioxidant include 1,1,3-tris (2-methyl-4-hydroxy-5-t-butylphenyl) butane and 2,2′-methylenebis (4-ethyl-6-t-). Butylphenol), tetrakis- [methylene-3- (3 ', 5'-di-tert-butyl-4'-hydroxyphenyl) propionate] methane, 2,6-di-tert-butyl-p-cresol, 4,4 '-Thiobis (3-methyl-6-t-butylphenol), 4,4'-butylidenebis (3-methyl-6-t-butylphenol), 1,3,5-tris (3', 5'-di-t -Butyl-4'-hydroxybenzyl) -S-triazine-2,4,6- (1H, 3H, 5H) trione, stearyl-β- (3,5-di-t-butyl-4-hydroxyphenyl) propionate ,bird Tylene glycol bis [3- (3-t-butyl-5-methyl-4-hydroxyphenyl) propionate], 3,9-bis [1,1-di-methyl-2- [β- (3-t-butyl -4-hydroxy-5-methylphenyl) propionyloxy] ethyl] -2,4,8,10-tetraoxaspiro [5,5] undecane, 1,3,5-trimethyl-2,4,6-tris ( 3,5-di-t-butyl-4-hydroxybenzyl) benzene, octadecyl 3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate and the like. In particular, the phenolic antioxidant preferably has a molecular weight of 550 or more.

  Examples of the thiol-based antioxidant include distearyl-3,3′-thiodipropionate, pentaerythritol-tetrakis- (β-lauryl-thiopropionate) and the like.

  Examples of the phosphite-based antioxidant include tris (2,4-di-t-butylphenyl) phosphite, distearylpentaerythritol diphosphite, and di (2,6-di-t-butylphenyl) pentaerythritol. Diphosphite, bis- (2,6-di-t-butyl-4-methylphenyl) -pentaerythritol diphosphite, tetrakis (2,4-di-t-butylphenyl) 4,4′-biphenylene-diphosphonite And 2,2'-methylenebis (4,6-di-t-butylphenyl) octyl phosphite, 2,2'-methylene bis (4,6-di-t-butylphenyl) 2-ethylhexyl phosphite and the like. .

  Examples of the hindered amine antioxidants include bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate, bis (1,2,2,6,6-pentamethyl-4-piperidyl) sebacate, tetrakis (1,2,2,6,6-pentamethyl-4-piperidyl) -1,2,3,4-butanetetracarboxylate, bis (1,2,2,6,6-pentamethyl-4-piperidyl)- 2- (3,5-di-t-butyl-4-hydroxybenzyl) -2-n-butylmalonate, 1-methyl-8- (1,2,2,6,6-pentamethyl-4-piperidyl) -Sebacate, 1- [2- [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionyloxy] ethyl] -4- [3- (3,5-di-t-butyl-4 -Hydroxyphenyl) Lopionyloxy] -2,2,6,6-tetramethylpiperidine, 4-benzoyloxy-2,2,6,6-tetramethylpiperidine, tetrakis (2,2,6,6-tetramethyl-4-piperidyl)- 1,2,3,4-butane-tetracarboxylate, triethylenediamine, 8-acetyl-3-dodecyl-7,7,9,9-tetramethyl-1,3,8-triazaspiro [4,5] decane- 2,4-dione, and the like.

  In particular, as the hindered amine antioxidant, a hindered amine light stabilizer containing only a tertiary amine is preferable, and specifically, bis (1,2,2,6,6-pentamethyl-4-piperidyl)- Sebacate, bis (1,2,2,6,6-pentamethyl-4-piperidyl) -2- (3,5-di-t-butyl-4-hydroxybenzyl) -2-n-butylmalonate, tetrakis ( 1,2,2,6,6-pentamethyl-4-piperidyl) -1,2,3,4-butanetetracarboxylate or 1,2,2,6,6-pentamethyl-4-piperidinol / tridecyl alcohol And a condensate of 1,2,3,4-butanetetracarboxylic acid.

  Among them, a phenolic antioxidant or a hindered amine antioxidant can be particularly preferably used. A phenolic antioxidant or a hindered amine antioxidant has an effect of capturing radicals generated by autoxidation. By using these, the effect of suppressing discoloration even under sunlight exposure can be further improved.

  The antioxidants may be used alone or in combination of two or more. As the antioxidant, a synthetic product or a commercially available product may be used. Examples of commercially available products include, for example, Nocrack (registered trademark) 200, Nocrack (registered trademark) M-17, Nocrack (registered trademark) SP, Nocrack (registered trademark) SP-N, Nocrack (registered trademark) NS-5, Nocrack (registered trademark) NS-6, Nocrack (registered trademark) NS-30, Nocrack (registered trademark) 300, Nocrack (registered trademark) NS-7, Nocrack (registered trademark) DAH (Ouchi Shinko Chemical Industry Co., Ltd. ADK STAB AO-30, ADK STAB AO-40, ADK STAB AO-50, ADK STAB AO-60, ADK STAB AO-616, ADK STAB AO-635, ADK STAB AO-658, ADK STAB AO-80, ADK STAB AO-15, ADK STAB AO -18, ADK STAB 328, ADK STAB AO-37, DECASTAB LA-52, ADEKASTAB LA-57, ADEKASTAB LA-62, ADEKASTAB LA-67, ADEKASTAB LA-63, ADEKASTAB LA-68, ADEKASTAB LA-82, ADEKASTAB LA-87, ADEKASTAB 2112, ADEKASTAB HP-10 (or more, ADEKA Corporation), IRGANOX (registered trademark) 245, IRGANOX (registered trademark) 259, IRGANOX (registered trademark) 565, IRGANOX (registered trademark) 1010, IRGANOX (registered trademark) 1024, IRGANOX (registered trademark) 1035, IRGANOX ( (Registered trademark) 1076, IRGANOX (registered trademark) 1081, IRGANOX (registered trademark) 1098, IRGANOX (registered trademark) 1222, IRGANOX (registered trademark) 1330, IRGA OX (registered trademark) 1425WL, IRGAFOS (registered trademark) 38, IRGAFOS (registered trademark) 168, IRGAFOS (registered trademark) P-EPQ, tinuvin PA144, tinuvin 765, tinuvin 660DF, Chimassorb 2020 (manufactured by BASF Japan Ltd.), Sumilizer ( (Registered trademark) GM, Sumilizer (registered trademark) GA-80 (all manufactured by Sumitomo Chemical Co., Ltd.), and the like.

  Although the content of the antioxidant in the infrared absorbing layer is not particularly limited, it is 0.01 to 10 with respect to the total weight of the infrared absorbing layer (in terms of solid content when the total weight of the infrared absorbing layer is 100% by mass). %, More preferably 0.05 to 3.0% by mass. When the content is 0.01% by mass or more, an excellent antioxidant function can be exhibited. When the content is 10% by mass or less, an antioxidant effect according to the addition amount can be obtained, and excellent optical characteristics can be obtained. Can be obtained.

(Surfactant)
It is preferable to add a surfactant to the infrared absorbing layer for the purpose of exhibiting functions as a leveling agent, a slipping agent, and the like, in addition to the infrared absorbing agent, the antioxidant, and the resin.

  Examples of the surfactant include, but are not particularly limited to, zwitterionic surfactants, cationic surfactants, anionic surfactants, nonionic surfactants, fluorine-based surfactants, and silicon-based surfactants. . Among them, from the viewpoint of uniformity and appearance of the coating film surface, an acrylic surfactant, a silicon surfactant, or a fluorine surfactant is preferable, and a fluorine surfactant is particularly preferable. As the surfactant, a surfactant having a long-chain alkyl group is preferable, and a surfactant having an alkyl group having 6 to 20 carbon atoms is more preferable.

  Examples of zwitterionic surfactants include alkyl betaine, alkyl amine oxide, cocamidopropyl betaine, lauramide propyl betaine, palm kernel fatty acid amidopropyl betaine, cocoamphoacetic acid N, lauroamphoacetate Na, lauramidepropyl hydroxysultaine, lauramide Propylamine oxide, myristamidopropylamine oxide, hydroxyalkyl (C12-14) hydroxyethylsarcosine.

  Examples of the cationic surfactant include an alkylamine salt and a quaternary ammonium salt.

  Examples of the anionic surfactant include an alkyl sulfate, a polyoxyethylene alkyl ether sulfate, an alkylbenzene sulfonate, a fatty acid salt, a polyoxyethylene alkyl ether phosphate, and dipotassium alkenyl succinate.

  Examples of the nonionic surfactant include polyoxyethylene alkyl ether (for example, Emulgen manufactured by Kao Corporation), polyoxyethylene sorbitan fatty acid ester (for example, Leodol TW series manufactured by Kao Corporation), glycerin fatty acid ester, polyoxyethylene fatty acid ester, and polyoxyethylene fatty acid ester. Oxyethylene alkylamines and alkylalkanolamides are exemplified.

  Examples of the fluorinated surfactant include Surflon S-211, S-221, S-231, S-241, S-242, S-243, S-420 (manufactured by AGC Seimi Chemical Co., Ltd.), Megafac F-114, F-410, F-479, F-552, F-553 (manufactured by DIC), FC-430, FC-4430, and FC-4432 (manufactured by 3M).

  Examples of the silicon-based surfactant include BYK-345, BYK-347, BYK-348, and BYK-349 (manufactured by BYK Japan KK).

  The above surfactants can be used alone or in combination of two or more.

  The content of the surfactant in the infrared absorbing layer is not particularly limited, but for the purpose of sufficiently obtaining a function as a leveling agent, a slipping agent, etc., when the total mass of the coating solution for the infrared absorbing layer is 100% by mass. , 0.001 to 0.30% by mass, more preferably 0.005 to 0.10% by mass.

  Further, the content of the surfactant is preferably in the range of 0.005 to 5% by mass relative to the total mass of the infrared absorbing layer (when the total mass of the infrared absorbing layer is 100% by mass), More preferably, it is 0.01 to 3% by mass.

(Other additives)
As described above, in addition to the infrared absorbing agent, the resin and the antioxidant, the infrared absorbing layer may contain a surfactant, but as long as the effects of the present invention are not impaired, further, other components may be used. It may contain additives.

  For example, the infrared absorbing layer may include inorganic nanoparticles as another additive. By including the inorganic nanoparticles, when the infrared absorbing layer is disposed adjacent to the substrate, the adhesion to the substrate is improved, and the scratch resistance of the laminated film can be improved. In the present specification, “inorganic nanoparticles” mean particles composed of an inorganic compound (preferably inorganic oxide) having an average particle size of 200 nm or less as measured by a dynamic scattering method.

There are no particular restrictions on the specific composition of the inorganic nanoparticles, but metal oxides such as SiO ₂ , Al ₂ O ₃ , ZrO ₂ , TiO ₂ , and CeO ₂ that can be used in the dielectric multilayer film described in detail below. Can be used.

  The content of the inorganic nanoparticles in the infrared absorbing layer is not particularly limited, but is preferably from 10 to 80 mass from the viewpoint of adjusting optical properties such as surface hardness and physical properties such as film elastic modulus and transmittance to desired values. %, More preferably 20 to 65% by mass.

(Method of forming infrared absorbing layer)
The method for forming the infrared absorbing layer is not particularly limited as long as the infrared absorbing layer having a film surface pH of 6.5 or more can be formed. It is preferable to use a method (wet method) of preparing a coating solution for the absorbing layer in advance and applying the coating solution.

  The method for preparing the coating solution for the infrared absorbing layer is not particularly limited as long as a specific film surface pH can be obtained. The coating solution for an infrared absorbing layer can be prepared, for example, by adding an infrared absorbing agent, a resin, and other additives such as a surfactant used as needed to a solvent, and mixing with stirring. When using an ultraviolet curable resin, a photopolymerization initiator is further added. At this time, the order of addition of each component is not particularly limited, and each component may be sequentially added and mixed with stirring, or may be added and mixed at once with stirring.

  The pH may be adjusted by using any acidic or basic pH adjuster, for example, an alkali such as sodium carbonate or sodium hydroxide when using an aqueous solvent, and / or an acid such as citric acid, acetic acid or sulfuric acid. The method can be carried out by adding an acid to the coating solution for the infrared absorbing layer.

  As described above, the acidic or basic pH adjuster for adjusting the pH of the membrane surface is not particularly limited. However, when a non-aqueous organic solvent is used, an acid such as a fatty acid, an alkali metal salt, or an alkali dissolved therein is used. When a solution containing a quaternary ammonium salt such as an earth metal salt or a quaternary amine is used, a polymer having a quaternary ammonium salt in the structure or the like is easily adjusted to a desired pH range.

  Further, for example, a complex forming compound such as a chelating reagent may be used.

  The solvent used in the coating solution for the infrared absorbing layer is not particularly limited as long as the resin, the infrared absorbing agent and the antioxidant can be sufficiently dispersed, and various organic solvents and aqueous solvents may be used. Can be.

  Examples of the organic solvent include, but are not particularly limited to, alcohols such as methanol, ethanol, n-propanol and i-propanol, ethyl acetate, butyl acetate, esters such as propylene glycol monomethyl ether acetate, diethyl ether, and propylene glycol. Examples include ethers such as monomethyl ether, amides such as dimethylformamide, and ketones such as acetone, methyl ethyl ketone, and methyl isobutyl ketone. These organic solvents may be used alone or in combination of two or more. Among the organic solvents, esters, ethers, and ketones are preferably used, and ketones are more preferably used, in consideration of the dispersibility of the resin, the infrared absorber, and the antioxidant.

  Examples of the aqueous solvent include, but are not particularly limited to, water and a mixed solvent of water and methanol, ethanol, n-propanol, i-propanol, or ethyl acetate. Among the above aqueous solvents, a mixed solvent of water and methanol, ethanol, n-propanol, or i-propanol is particularly preferable in consideration of the dispersibility of the resin, the infrared absorber, and the antioxidant.

  When a mixed solvent of water and a small amount of an organic solvent is used, the content of water in the mixed solvent is preferably 10 to 60% by mass, and preferably 20 to 50% by mass based on 100% by mass of the whole mixed solvent. Is more preferable.

  The concentration of the resin in the coating solution for the infrared absorbing layer (when a plurality of types of resins are used, the total concentration thereof) is preferably 0.5 to 30% by mass. Further, the concentration of the infrared absorbent in the coating liquid for the infrared absorbing layer is preferably 0.1 to 50% by mass. Further, the concentration of the antioxidant in the coating solution for the infrared absorbing layer is preferably 0.01 to 10% by mass.

  The concentration of the surfactant in the coating solution for the infrared absorbing layer is preferably from 0.005 to 0.30% by mass.

  An infrared absorbing layer can be formed by applying the infrared absorbing layer coating solution prepared as described above. Here, the application method is not particularly limited. For example, it can be formed by a wet method such as coating with a wire bar, spin coating, or dip coating. It is also possible to apply and form a film using a continuous coating apparatus such as a die coater, a gravure coater or a comma coater.

  The conditions for applying and drying the infrared absorbing layer are not particularly limited, and appropriate temperatures and drying times can be adopted to promote curing and crosslinking. In particular, when an ultraviolet curable resin is used as the resin, the irradiation wavelength, illuminance, and light amount of ultraviolet light are also appropriately adjusted.

[Base material]
The laminated film according to the present invention includes a base material for supporting the infrared absorption layer and other optional layers (for example, a dielectric multilayer film). Various resin films can be used as the base material of the laminated film, such as polyolefin films (polyethylene, polypropylene, etc.), polyester films (polyethylene terephthalate (PET), polyethylene naphthalate, etc.), polyvinyl chloride, cellulose acetate, etc. Can be used, and a polyester film is preferable. The polyester film (hereinafter, referred to as polyester) is not particularly limited, but is preferably a film-forming polyester having a dicarboxylic acid component and a diol component as main components.

  The thickness of the substrate used in the present invention is preferably from 10 to 300 μm, particularly preferably from 20 to 150 μm. In addition, two substrates may be stacked, and in this case, the types may be the same or different.

  The base material preferably has a transmittance of 85% or more, and particularly preferably 90% or more, in a visible light region indicated by JIS R3106-1998. When the substrate has the transmittance or higher, it is advantageous in that the transmittance in the visible light region represented by JIS R3106-1998 in the case of forming a laminated film is 50% or more (upper limit: 100%), preferable.

  Further, the substrate using the above resin or the like may be an unstretched film or a stretched film. Stretched films are preferred from the viewpoint of improving strength and suppressing thermal expansion.

  Further, as the substrate of the present invention, in addition to the above-mentioned substrates, a dielectric multilayer film which will be described later and which has self-supporting properties can be used. The dielectric multilayer film having self-supporting properties is not particularly limited, and examples thereof include a dielectric multilayer film produced by a co-extrusion method or a co-salting method.

[Dielectric multilayer film]
When a light having a specific wavelength (for example, infrared light) is incident, the laminated film of the present invention reflects at least a part of this light to thereby have a shielding effect (and, in the case of infrared light, a heat shielding effect). In order to exhibit (3), it is preferable to further include a dielectric multilayer film in which low refractive index layers and high refractive index layers are alternately laminated. Preferably, the dielectric multilayer film has at least one reflection peak in a wavelength range of 800 to 1300 nm. Here, the dielectric multilayer film may be provided on the opposite side of the infrared absorption layer via the base material, or may be provided on the same side of the base material as the infrared absorption layer.

  In the present embodiment, whether the refractive index layer constituting the dielectric multilayer film is a low refractive index layer or a high refractive index layer is determined by comparing the refractive index with an adjacent refractive index layer. Specifically, when a certain refractive index layer is used as a reference layer, if the refractive index layer adjacent to the reference layer has a lower refractive index than the reference layer, the reference layer is a high refractive index layer (the adjacent layer has a low refractive index). Rate class). On the other hand, if the refractive index of the adjacent layer is higher than that of the reference layer, it is determined that the reference layer is a low refractive index layer (the adjacent layer is a high refractive index layer). Therefore, whether the refractive index layer is a high refractive index layer or a low refractive index layer is a relative one determined by the relationship with the refractive index of the adjacent layer, and a certain refractive index layer is Depending on the relationship, it can be a high refractive index layer or a low refractive index layer.

  The refractive index layer is not particularly limited, but is preferably a known refractive index layer used in the technical field. As a known refractive index layer, for example, a refractive index layer formed using a dry film forming method, a refractive index layer formed by extrusion molding of a resin, and a refractive index layer formed using a wet film forming method Is mentioned. Among them, a wet film forming method is preferably used from the viewpoint of production efficiency.

  As described above, whether a layer is a low-refractive-index layer or a high-refractive-index layer is a relative one determined by the relationship with an adjacent refractive-index layer. The structure of a typical high refractive index layer and low refractive index layer among the refractive index layers will be described below.

(Refractive index layer formed by resin extrusion molding)
In the present invention, the resin that can be used for the alternating high refractive index layer and low refractive index layer is not particularly limited, but it is preferable that at least one layer is birefringent and oriented. For example, those described in JP-T-2008-528313 or those appropriately modified can be used.

  Specific examples include polyethylene terephthalate, a copolymer of polyethylene terephthalate, poly (methyl methacrylate), a copolymer of poly (methyl methacrylate), a copolymer of terephthalic acid-cyclohexanedimethanol-ethylene glycol, polyethylene naphthalate, and a copolymer of polyethylene naphthalate. And the like, but are not limited thereto. Each of the high refractive index layer and the low refractive index layer can use one kind of these resins or a combination of two or more kinds. Examples of suitable resin combinations include those described in US Pat. No. 6,352,761. Using the above resin, a dielectric multilayer film can be formed by a continuous flat film production line by, for example, a coextrusion method.

(Refractive index layer formed using wet film forming method)
In the wet film forming method, the refractive index layer can be formed by a method of sequentially applying and drying a coating solution, a method of applying and drying a coating solution in a multilayer manner, or the like. The refractive index layer of the laminated film according to this embodiment is preferably formed by this wet film forming method, and more preferably formed by a method of applying and drying a coating solution in a multilayer manner.

-High refractive index layer-
The high-refractive-index layer preferably contains metal oxide particles from the viewpoint of easy control of the refractive index, and, if necessary, contains a water-soluble resin, a curing agent, a surfactant, and other additives. You may go out. The metal oxide particles and the water-soluble resin contained in the high refractive index layer are hereinafter referred to as “first metal oxide particles” and “first water-soluble resin” for convenience.

(1) First metal oxide particles The first metal oxide particles are not particularly limited, but are preferably metal oxide particles having a refractive index of 2.0 to 3.0. Specifically, titanium oxide, zirconium oxide, zinc oxide, alumina, colloidal alumina, lead titanate, lead tin, graphite, zinc yellow, chromium oxide, ferric oxide, iron black, copper oxide, magnesium oxide, water Examples include magnesium oxide, strontium titanate, yttrium oxide, niobium oxide, europium oxide, lanthanum oxide, zircon, and tin oxide. Among these, the first metal oxide particles are preferably titanium oxide and zirconium oxide from the viewpoint of forming a transparent, high-refractive-index high-refractive-index layer, and are preferably rutile-type (tetragonal-type) from the viewpoint of improving weather resistance. More preferably, it is titanium oxide.

  The titanium oxide may be in the form of core-shell particles coated with a silicon-containing hydrated oxide. The core-shell particles have a structure in which the surface of titanium oxide particles is covered with a shell made of a silicon-containing hydrated oxide on titanium oxide serving as a core.

  The first metal oxide particles described above may be used alone or in combination of two or more.

  The content of the first metal oxide particles is preferably 15 to 85% by mass with respect to 100% by mass of the solid content of the high refractive index layer, from the viewpoint of increasing the difference in the refractive index from the low refractive index layer. Preferably, it is 20 to 80% by mass, more preferably 30 to 77% by mass.

  Further, the volume average particle diameter of the first metal oxide particles is more preferably 1 to 100 nm, further preferably 3 to 50 nm. When the volume average particle size is 100 nm or less, it is preferable because the haze is small and the visible light transmittance is excellent. In the present specification, the value of the “volume average particle size” is a value measured by the following method. Specifically, an arbitrary 1,000 particles appearing on the cross section or the surface of the refractive index layer are observed with an electron microscope to measure the particle diameter, and the particles having a particle diameter of d1, d2,..., Di,. , Nik ...... Nk metal oxide particles, where the volume per particle is vi, and the volume average particle diameter mv = {(vi · di)} / The average particle size weighted by the volume represented by {(vi)} is calculated.

(2) First Water-Soluble Resin The first water-soluble resin is not particularly limited, but a polyvinyl alcohol-based resin, gelatin, celluloses, thickening polysaccharides, and a polymer having a reactive functional group can be used. . Among these, it is preferable to use a polyvinyl alcohol-based resin.

Polyvinyl alcohol-based resin Examples of the polyvinyl alcohol-based resin include ordinary polyvinyl alcohol (unmodified polyvinyl alcohol) obtained by hydrolyzing polyvinyl acetate, cation-modified polyvinyl alcohol, anion-modified polyvinyl alcohol, nonionic-modified polyvinyl alcohol, and vinyl alcohol. Modified polyvinyl alcohol such as a system polymer is exemplified. The modified polyvinyl alcohol may improve the adhesion, water resistance, and flexibility of the film in some cases.

Gelatin As gelatin, various gelatins which have been widely used in the field of silver halide photographic materials can be used. For example, acid-treated gelatin, alkali-treated gelatin, enzyme-treated gelatin which is subjected to an enzyme treatment in the production process of gelatin, a group having an amino group, imino group, hydroxyl group, or carboxyl group as a functional group in the molecule and capable of reacting therewith And a gelatin derivative treated and modified with a reagent having the following formula:

  When gelatin is used, a hardening agent for gelatin can be added as necessary.

Cellulose As the cellulose, a water-soluble cellulose derivative can be preferably used. For example, water-soluble cellulose derivatives such as carboxymethylcellulose (cellulose carboxymethyl ether), methylcellulose, hydroxymethylcellulose, hydroxyethylcellulose, and hydroxypropylcellulose; carboxylic acid group-containing celluloses such as carboxymethylcellulose (cellulose carboxymethylether) and carboxyethylcellulose; Cellulose derivatives such as cellulose, cellulose acetate propionate, cellulose acetate and cellulose sulfate are exemplified.

Thickening polysaccharide Thickening polysaccharide is a polymer of a saccharide and has many hydrogen bonding groups in the molecule. The thickening polysaccharide has a characteristic that a difference in viscosity between a low temperature and a high temperature is large due to a difference in hydrogen bonding force between molecules due to temperature. Further, when metal oxide fine particles are added to the thickening polysaccharide, the viscosity increases at a low temperature, which is considered to be due to hydrogen bonding with the metal oxide fine particles. The increase in the viscosity is such that the viscosity at 15 ° C. is usually at least 1.0 mPa · s, preferably at least 5.0 mPa · s, more preferably at least 10.0 mPa · s.

  The thickening polysaccharide that can be used is not particularly limited, and includes generally known natural simple polysaccharides, natural complex polysaccharides, synthetic simple polysaccharides, and synthetic complex polysaccharides. For details of these polysaccharides, reference can be made to “Biochemical Encyclopedia (second edition), Tokyo Kagaku Dojin Publishing”, “Food Industry”, Vol. 31, 1988, p.

Polymer having a reactive functional group Examples of the polymer having a reactive functional group include polyvinylpyrrolidone, polyacrylic acid, acrylic acid-acrylonitrile copolymer, potassium acrylate-acrylonitrile copolymer, vinyl acetate-acrylic ester Acrylic resins such as copolymers and acrylic acid-acrylic acid ester copolymers; styrene-acrylic acid copolymers, styrene-methacrylic acid copolymers, styrene-methacrylic acid-acrylic acid ester copolymers, styrene-α Styrene acrylic acid resins such as -methylstyrene-acrylic acid copolymer and styrene-α-methylstyrene-acrylic acid-acrylate copolymer; styrene-sodium styrenesulfonate copolymer, styrene-2-hydroxyethyl acrylate Copolymer, polystyrene -2-hydroxyethyl acrylate-potassium styrene sulfonate copolymer, styrene-maleic acid copolymer, styrene-maleic anhydride copolymer, vinylnaphthalene-acrylic acid copolymer, vinylnaphthalene-maleic acid copolymer, Vinyl acetate-based copolymers such as vinyl acetate-maleic acid ester copolymer, vinyl acetate-crotonic acid copolymer, vinyl acetate-acrylic acid copolymer; and salts thereof. Among these, it is preferable to use polyvinylpyrrolidones and a copolymer containing the same.

  The above-mentioned water-soluble resins may be used alone or in combination of two or more.

  The weight average molecular weight of the first water-soluble resin is preferably from 1,000 to 200,000, more preferably from 3,000 to 40,000. In the present specification, the value of the “weight average molecular weight” is a value measured by gel permeation chromatography (GPC).

  The content of the first water-soluble resin is preferably from 5 to 50% by mass, more preferably from 10 to 40% by mass, based on 100% by mass of the solid content of the high refractive index layer.

(3) Curing Agent The curing agent has a function of forming a hydrogen bond network by reacting with the first water-soluble resin (preferably, a polyvinyl alcohol-based resin) contained in the high refractive index layer.

  The curing agent is not particularly limited as long as it causes a curing reaction with the first water-soluble resin, but is generally a compound having a group capable of reacting with the water-soluble resin or a different group having a water-soluble resin. Compounds that promote the reaction between each other are included.

  As a specific example, when using polyvinyl alcohol as the first water-soluble resin, it is preferable to use boric acid and a salt thereof as a curing agent. Further, a known curing agent other than boric acid and a salt thereof may be used.

  In addition, boric acid and its salt mean oxyacid and its salt which have a boron atom as a central atom. Specific examples include orthoboric acid, diboric acid, metaboric acid, tetraboric acid, pentaboric acid, octaboric acid, and salts thereof.

  The content of the curing agent is preferably 1 to 10% by mass, more preferably 2 to 6% by mass, based on 100% by mass of the solid content of the high refractive index layer.

  In particular, when polyvinyl alcohol is used as the first water-soluble resin, the total amount of the curing agent used is preferably 1 to 600 mg per 1 g of polyvinyl alcohol, and more preferably 100 to 600 mg per 1 g of polyvinyl alcohol. .

(4) Surfactant The surfactant that can be contained in the high refractive index layer is not particularly limited, but the same surfactant that can be added to the infrared absorption layer can be used. Omitted.

(5) Other additives The high refractive index layer may also contain other additives. Other additives include amino acids, emulsion resins, lithium compounds and the like. UV absorbers described in JP-A-57-74193, JP-A-57-87988, and JP-A-62-261476; JP-A-57-74192, JP-A-57-87989 JP-A-59-42993, JP-A-60-72785, JP-A-61-146591, JP-A-1-95091, JP-A-3-13376 and the like; Fluorescent brighteners described in JP-A-59-52689, JP-A-62-280069, JP-A-61-242871, JP-A-4-219266, etc .; sulfuric acid, phosphoric acid PH adjusters such as acetic acid, citric acid, sodium hydroxide, potassium hydroxide and potassium carbonate; antifoaming agents; lubricants such as diethylene glycol; preservatives; antifungal agents; antistatic agents; Known additives such as an antioxidant; a flame retardant; a crystal nucleating agent; an inorganic particle; an organic particle; a viscosity reducing agent; a lubricant; an infrared absorber; a dye; a pigment, and the like may be used as other additives. .

−Low refractive index layer−
The low refractive index layer also preferably contains metal oxide particles from the viewpoint that the control of the refractive index becomes easy. In addition, if necessary, a water-soluble resin, a curing agent, a surfactant, and other additives may be contained. The metal oxide particles and the water-soluble resin contained in the low refractive index layer are hereinafter referred to as “second metal oxide particles” and “second water-soluble resin” for convenience.

(1) Second water-soluble resin As the second water-soluble resin, the same one as the first water-soluble resin can be used.

  At this time, when the high refractive index layer and the low refractive index layer both use a polyvinyl alcohol-based resin as the first water-soluble resin and the second water-soluble resin, the polyvinyl alcohol-based resins having different degrees of saponification are used. It is preferable to use a resin. Thereby, mixing at the interface is suppressed, the infrared reflectance (infrared shielding ratio) becomes better, and the haze can be reduced. In addition, in this specification, the "degree of saponification" means the ratio of the hydroxy group to the total number of acetyloxy groups (derived from raw material vinyl acetate) and hydroxy groups in polyvinyl alcohol.

(2) Second Metal Oxide Particles The second metal oxide particles are not particularly limited, but it is preferable to use silica (silicon dioxide) such as synthetic amorphous silica and colloidal silica, and acidic colloidal silica sol It is more preferable to use In addition, from the viewpoint of further reducing the refractive index, hollow fine particles having voids inside the particles can be used as the second metal oxide particles, and hollow fine particles of silica (silicon dioxide) are particularly preferably used. .

  Colloidal silica may have its surface cationically modified, or may have been treated with Al, Ca, Mg, Ba or the like.

  Further, the second metal oxide particles may be surface-coated with a surface coating component.

  The second metal oxide particles (preferably silicon dioxide) contained in the low refractive index layer of the present invention have an average particle size (number average; diameter) of preferably 3 to 100 nm, and more preferably 3 to 50 nm. Is more preferable. In the present specification, the “average particle diameter (number average; diameter)” of the metal oxide fine particles is determined by observing the particles themselves or the particles appearing on the cross section or surface of the refractive index layer with an electron microscope, and measuring 1,000 particles. Is measured as a simple average value (number average). Here, the particle diameter of each particle is represented by a diameter assuming a circle equal to its projected area.

  The content of the second metal oxide particles in the low refractive index layer is preferably from 0.1 to 85% by mass, and more preferably from 30 to 80% by mass, based on 100% by mass of the total solid content of the low refractive index layer. Is more preferably 45 to 75% by mass.

  The above-mentioned second metal oxide may be used alone or in combination of two or more kinds from the viewpoint of adjusting the refractive index.

(3) Curing Agent, Surfactant, and Other Additives As the curing agent, surfactant, and other additives, the same ones as in the high refractive index layer can be used, and the description is omitted here.

  In a dielectric multilayer film in which high-refractive-index layers and low-refractive-index layers having the above configuration are alternately laminated, at least one of the high-refractive-index layer and the low-refractive-index layer uses a wet film forming method. Preferably, both the high refractive index layer and the low refractive index layer are refractive index layers formed by a wet film forming method. Further, at least one of the high refractive index layer and the low refractive index layer preferably contains metal oxide particles. That is, the laminated film of the present invention further includes a dielectric multilayer film in which a low refractive index layer and a high refractive index layer are alternately laminated, and the low refractive index layer or the high refractive index layer contains metal oxide particles. It is preferable to include.

  More preferably, both the high refractive index layer and the low refractive index layer contain metal oxide particles.

  In the laminated film according to the present invention, it is preferable to design a large difference in the refractive index between the low refractive index layer and the high refractive index layer from the viewpoint that the infrared reflectance can be increased with a small number of layers. In this embodiment, in at least one of the laminates composed of the low refractive index layer and the high refractive index layer, the difference in refractive index between the adjacent low refractive index layer and high refractive index layer is preferably 0.1 or more. It is more preferably 0.3 or more. When there are a plurality of laminates of the high refractive index layer and the low refractive index layer, it is preferable that the difference in the refractive index between the high refractive index layer and the low refractive index layer in all the laminates is within the above preferable range. However, even in this case, the refractive index layers constituting the uppermost layer and the lowermost layer of the dielectric multilayer film may have a configuration outside the above-mentioned preferable range.

  As the optical characteristics of the laminated film of the present embodiment, the transmittance in the visible light region indicated by JIS R3106-1998 is preferably 50% or more, preferably 75% or more, more preferably 85% or more, and the wavelength 900 nm. It is preferable to have a region having a reflectance of more than 50% in a region of 〜1400 nm.

  In general, in the infrared shielding film, the infrared region of the incident spectrum of the sun's direct light is related to an increase in the indoor temperature, and by blocking this, the increase in the indoor temperature can be suppressed. Based on the weighting factor described in Japanese Industrial Standard JIS R3106-1998, when the total energy in the entire infrared region from the shortest wavelength (760 nm) to the longest wavelength (3200 nm) of the infrared ray is assumed to be 100, each energy is from 760 nm. Looking at the accumulated energy up to the wavelength, the total energy from 760 nm to 1300 nm occupies about 75% of the entire infrared region. Therefore, shielding this wavelength region is the most efficient energy saving effect in summer due to heat ray shielding. The infrared shielding film of the present invention has an optical film thickness of a dielectric multilayer film such that the dielectric multilayer film has a reflection peak (maximum value) exceeding 50% in a near infrared wavelength region of 800 to 1300 nm. And a unit are preferably designed, and more preferably, the dielectric multilayer film is designed so as to have a reflection peak having a maximum reflectance of about 80% or more in the region.

  The number of refractive index layers (the total number of high refractive index layers and low refractive index layers) of the dielectric multilayer film is preferably from 6 to 50, and more preferably from 8 to 40, from the above viewpoint. More preferably, it is more preferably 9 to 31 layers, and particularly preferably 11 to 30 layers. It is preferable that the number of the refractive index layers of the dielectric multilayer film be in the above range since excellent heat shielding performance and transparency, suppression of film peeling and cracking, and the like can be realized. When the dielectric multilayer film has a plurality of high refractive index layers and / or low refractive index layers, the high refractive index layers and / or the low refractive index layers are different even if they are the same. It may be something.

  The thickness per layer of the high refractive index layer is preferably from 20 to 800 nm, more preferably from 50 to 500 nm. Further, the thickness of one layer of the low refractive index layer is preferably 20 to 800 nm, more preferably 50 to 500 nm.

  Here, when measuring the thickness per layer, the composition may change continuously without having a clear interface at the boundary between the high refractive index layer and the low refractive index layer. In such an interface region where the composition continuously changes, when the maximum refractive index−the minimum refractive index = Δn, the point of the minimum refractive index between two layers + Δn / 2 is regarded as a layer interface.

  When the high refractive index layer and the low refractive index layer contain metal oxide particles, the above composition can be observed from the concentration profile of the metal oxide particles. The metal oxide concentration profile is obtained by performing etching from the surface in the depth direction using a sputtering method, sputtering the surface at 0 nm with an XPS surface analyzer at a rate of 0.5 nm / min, It can be seen by measuring the ratio. Alternatively, the laminated film may be cut, and the cut surface may be confirmed by measuring the atomic composition ratio with an XPS surface analyzer.

  The XPS surface analyzer is not particularly limited, and any model can be used. As the XPS surface analyzer, for example, ESCALAB-200R manufactured by VG Scientific can be used. The measurement is performed at an output of 600 W (acceleration voltage 15 kV, emission current 40 mA) using Mg for the X-ray anode.

[Adhesive layer]
The laminated film according to the present invention may further have an adhesive layer. This adhesive layer is usually provided on the surface opposite to the infrared absorbing layer via the base material, and may further be provided with a known release paper (separator). The constitution of the adhesive layer is not particularly limited, and for example, any of a dry laminating agent, a wet laminating agent, an adhesive, a heat sealing agent, a hot melt agent and the like are used. As the adhesive, for example, a polyester resin, a urethane resin, a polyvinyl acetate resin, an acrylic resin, a nitrile rubber, or the like is used.

  The thickness of the adhesive layer is preferably from 1 to 100 μm, more preferably from 3 to 50 μm. If it is 1 μm or more, the adhesiveness tends to be improved, and a sufficient adhesive strength can be obtained. Conversely, if the thickness is 100 μm or less, not only the transparency of the laminated film is improved, but also after the laminated film is attached to the window glass, cohesive failure does not occur between the adhesive layers when peeled off, and the adhesive remains on the glass surface. Tend to disappear.

  The method for forming the pressure-sensitive adhesive layer is not particularly limited, but separately from the substrate on which the infrared absorbing layer is formed, a coating liquid for a pressure-sensitive adhesive layer is applied to release paper (separator) and dried to form a pressure-sensitive adhesive layer. Thereafter, a method of bonding the adhesive layer and the dielectric multilayer film or the base material is preferable.

[Hard coat layer]
The laminated film of the present invention has a hard coat layer containing a resin that is cured by heat, ultraviolet light, or the like on the uppermost layer on the side opposite to the side having the adhesive layer of the base material, as a surface protective layer for enhancing abrasion resistance. They may be stacked. In particular, when the infrared absorbing layer does not also function as a hard coat layer, it is preferable that the infrared absorbing layer further has a hard coat layer.

  Examples of the cured resin used in the hard coat layer include a thermosetting resin and an ultraviolet-curable resin, but an ultraviolet-curable resin is preferable because of easy molding, and among them, those having a pencil hardness of at least 2H are preferable. More preferred. Such curable resins can be used alone or in combination of two or more.

  In addition, as such an ultraviolet-curable resin, those similar to the ultraviolet-curable resin that can be used as the resin described in the section of [Infrared absorbing layer] above can be used, and a detailed description thereof is omitted. I do.

  The thickness of the hard coat layer is preferably from 0.1 to 50 μm, more preferably from 1 to 20 μm, from the viewpoint of improving the hard coat property and the transparency of the laminated film.

  The method for forming the hard coat layer is not particularly limited. For example, after preparing a coating solution for the hard coat layer containing each of the above components, the coating solution is applied by a wire bar or the like, and the coating solution is cured by heat and / or UV. And forming a hard coat layer.

[Other functional layers]
The laminated film according to the present invention may have a layer (other functional layer) other than the above-described layer. For example, an intermediate layer can be provided as another layer. Here, the “intermediate layer” means a layer between the base material and the infrared absorption layer or a layer between the base material and the dielectric multilayer film.

  Examples of the constituent material of the intermediate layer include a polyester resin, a polyvinyl alcohol resin, a polyvinyl acetate resin, a polyvinyl acetal resin, an acrylic resin, and a urethane resin. A substance having low additive compatibility and a low Tg is preferably used.

[Production method of laminated film]
The method for producing the laminated film is not particularly limited, and any method may be used as long as an infrared absorbing layer containing an infrared absorbing agent, a resin, and an antioxidant and having a film surface pH of 6.5 or more can be formed. Can be Here, since the method of forming the infrared absorbing layer, the dielectric multilayer film, the adhesive layer, and the hard coat layer itself has already been described above, a detailed description of the method of manufacturing each layer (multilayer film) is omitted here.

  As a method of manufacturing a laminated film, for example, the following method is used. (1) forming a dielectric multilayer film on one surface of the base material (the surface opposite to the surface on which the separator and the adhesive layer are arranged), forming an infrared absorbing layer on the dielectric multilayer film, Thereafter, if necessary, a method of forming a hard coat layer on the infrared absorption layer; (2) forming a dielectric multilayer film on one surface of the base material (the surface on which the separator and the adhesive layer are arranged); Thereafter, a method of forming an infrared absorbing layer on the other surface of the base material and, if necessary, forming a hard coat layer on the infrared absorbing layer. In any of the above production methods (1) and (2), it is preferable that the infrared absorbing layer also serves as the hard coat layer, since the step of forming the hard coat layer can be omitted.

[Application of laminated film]
The laminated film according to the present invention can be applied to a wide range of fields. For example, as a window sticking film such as a heat ray reflecting film that imparts a heat ray reflecting effect, and a film for an agricultural greenhouse, etc. Used for the purpose of enhancing weather resistance. Further, it is suitably used as a laminated film for automobiles sandwiched between glass such as laminated glass for automobiles.

  Hereinafter, the present invention will be described specifically with reference to Examples, but the present invention is not limited thereto. In the examples, “parts” or “%” may be used, but “parts by mass” or “% by mass” is used unless otherwise specified.

<< Preparation of laminated film >>
<Example 1>
(Preparation of coating liquid 1 for infrared absorption layer)
The following materials were mixed and stirred at room temperature for 30 minutes to prepare a coating liquid 1 for an infrared absorbing layer.

Acryt 8UA-301 (urethane-modified acrylic polymer: manufactured by Taisei Fine Chemical Co., Ltd.) 633 parts by mass YMF-02A (cesium-containing composite tungsten oxide (Cs _0.33 WO ₃ ), solids: 28.7% by mass, particle concentration: 18.5) % By mass, average particle diameter 15 nm, refractive index 1.66: manufactured by Sumitomo Metal Mining Co., Ltd.) 294 parts by mass ADK STAB AO-80 (phenolic antioxidant: manufactured by ADEKA Corporation) 3.9 parts by mass Acritt 1SX-1065 ( Quaternary ammonium salt type antistatic polymer: manufactured by Taisei Fine Chemical Co., Ltd.) 6.4 parts by mass methyl ethyl ketone 62 parts by mass.

(Preparation of Coating Solution 1 for Adhesive Layer)
The following materials were mixed and stirred at room temperature for 30 minutes to prepare a coating solution 1 for an adhesive layer.

Coponyl N-2147 (acrylic adhesive: Nippon Synthetic Chemical Co., Ltd.) 638 parts by mass Tinuvin 477 (hydroxyphenyltriazine-based ultraviolet absorber: BASF Japan Ltd.) 20 parts by mass Coronate HX (crosslinking agent: Nippon Polyurethane Industry Co., Ltd.) 0.7 parts by mass 341 parts by mass of ethyl acetate.

(Production of laminated film 1)
Using a gravure coater, the infrared absorbing layer coating liquid 1 prepared above was applied onto a 50 μm thick polyethylene terephthalate (PET) film (A4300 manufactured by Toyobo) as a base material, and dried at a drying zone temperature of 100 ° C. for 1 minute. It dried and the infrared absorption layer was formed.

  Further, using a die coater, the adhesive layer coating solution 1 prepared above was applied to a separator (NS-23MA: manufactured by Nakamoto Pax Co., Ltd.), dried at 80 ° C. for 1 minute, and then the infrared absorbing layer prepared above The PET surface and the adhesive layer surface of the film laminated with were laminated to produce a laminated film 1. The thickness of the infrared absorbing layer of the laminated film 1 was 5 μm, and the thickness of the adhesive layer was 10 μm.

(Measurement of membrane pH)
Using a pH meter having a Surface electrode attached to METTLER TOLEDO's FiveEasy FE20 (equivalent performance equipment), 0.6 ml of pure water was dropped on the surface of the infrared absorbing layer, and after 60 seconds, the pH of the water droplet was measured with the pH meter. It was measured.

  The film surface pH of the infrared absorbing layer of the laminated film 1 was 6.5.

<Example 2>
(Preparation of coating liquid 2 for infrared absorption layer)
6.4 parts by mass of 1SX-1065 of the infrared absorbing layer coating solution 1 was changed to 2.8 parts by mass of Chelesto MZ-8 (organic solvent-soluble chelating agent, pH 7.6: manufactured by Chilesto Co., Ltd.). Except for the above, a coating solution 2 for an infrared absorbing layer was prepared in the same procedure.

(Preparation of laminated film 2)
A laminated film 2 was prepared in the same manner as the laminated film 1 except that the infrared absorbing layer coating liquid 2 was used instead of the infrared absorbing layer coating liquid 1.

  When the film surface pH of the infrared absorption layer of the laminated film 2 was measured in the same manner as described above, the film surface pH was 7.5.

<Example 3>
(Preparation of coating liquid 3 for infrared absorption layer)
In the same procedure, except that 6.4 parts by mass of 1SX-1065 of the coating liquid 1 for the infrared absorbing layer was changed to 2.8 parts by mass of TBAB-100A (tetrabutylammonium bromide: manufactured by Lion Corporation). Infrared absorbing layer coating solution 3 was prepared.

(Production of laminated film 3)
A laminated film 3 was prepared in the same manner as the laminated film 1 except that the infrared absorbing layer coating liquid 3 was used instead of the infrared absorbing layer coating liquid 1.

  When the film surface pH of the infrared absorbing layer of the laminated film 3 was measured in the same manner as described above, the film surface pH was 9.0.

<Example 4>
(Preparation of coating liquid 4 for infrared absorption layer)
The 1SX-1065 6.4 parts by weight of the infrared-absorbing layer coating liquid 1, CHELEST _{400 (EDTA · 4Na · 4H 2} O, pH11.2: CHELEST Corp.) except that it was changed to 2.8 parts by weight In the same manner, coating solution 4 for an infrared absorbing layer was prepared.

(Production of laminated film 4)
A laminated film 4 was produced in the same manner as the laminated film 1 except that the infrared absorbing layer coating liquid 4 was used instead of the infrared absorbing layer coating liquid 1.

  When the film surface pH of the infrared absorbing layer of the laminated film 4 was measured in the same manner as described above, the film surface pH was 11.0.

<Comparative Example 1>
(Preparation of coating solution 5 for infrared absorption layer)
The following materials were mixed and stirred at room temperature for 30 minutes to prepare a coating liquid 5 for an infrared absorbing layer.

Acryt 8UA-301 (urethane-modified acrylic polymer: manufactured by Taisei Fine Chemical Co., Ltd.) 656 parts by mass YMF-02A (cesium-containing composite tungsten oxide (Cs _0.33 WO ₃ ), solid content 28.7 mass%, particle concentration 18.5) Mass%, average particle diameter 15 nm, refractive index 1.66: manufactured by Sumitomo Metal Mining Co., Ltd.) 294 parts by mass 50 parts by mass of methyl ethyl ketone.

(Preparation of laminated film 5)
A laminated film 5 was produced in the same manner as the laminated film 1, except that the infrared absorbing layer coating liquid 1 was used instead of the infrared absorbing layer coating liquid 1.

  When the film surface pH of the infrared absorbing layer of the laminated film 5 was measured in the same manner as described above, the film surface pH was 5.5.

<Comparative Example 2>
(Preparation of coating liquid 6 for infrared absorption layer)
The following materials were mixed and stirred at room temperature for 30 minutes to prepare a coating liquid 6 for an infrared absorbing layer.

Acryt 8 UA-301 (urethane-modified acrylic polymer: manufactured by Taisei Fine Chemical Co., Ltd.) 643 parts by mass YMF-02A (cesium-containing composite tungsten oxide (Cs _0.33 WO ₃ ), solids 28.7 mass%, particle concentration 18.5) % By mass, average particle diameter 15 nm, refractive index 1.66: manufactured by Sumitomo Metal Mining Co., Ltd.) 294 parts by mass ADK STAB AO-80 (phenolic antioxidant: manufactured by ADEKA Corporation) 3.9 parts by mass methyl ethyl ketone 59 parts by mass.

(Production of laminated film 6)
A laminated film 6 was produced in the same manner as the laminated film 1, except that the infrared absorbing layer coating liquid 6 was used instead of the infrared absorbing layer coating liquid 1.

  When the film surface pH of the infrared absorbing layer of the laminated film 6 was measured in the same manner as described above, the film surface pH was 5.5.

<Comparative Example 3>
(Preparation of coating solution 7 for infrared absorption layer)
The following materials were mixed and stirred at room temperature for 30 minutes to prepare a coating liquid 7 for an infrared absorbing layer.

Acryt 8UA-301 (urethane-modified acrylic polymer: manufactured by Taisei Fine Chemical Co., Ltd.) 646 parts by mass YMF-02A (cesium-containing composite tungsten oxide (Cs _0.33 WO ₃ ), solids 28.7% by mass, particle concentration 18.5) % By mass, average particle diameter: 15 nm, refractive index: 1.66: Sumitomo Metal Mining Co., Ltd.) 294 parts by mass: Cherest MZ-8 (organic solvent-soluble chelating agent, pH 7.6: manufactured by Kyrest Co., Ltd.) 2.8 mass Parts: 56 parts by mass of methyl ethyl ketone.

(Production of laminated film 7)
A laminated film 7 was prepared in the same manner as the laminated film 1 except that the infrared absorbing layer coating liquid 7 was used instead of the infrared absorbing layer coating liquid 1.

  When the film surface pH of the infrared absorbing layer of the laminated film 7 was measured in the same manner as described above, the film surface pH was 7.5.

<Comparative Example 4>
(Preparation of coating liquid 8 for infrared absorption layer)
The following materials were mixed and stirred at room temperature for 30 minutes to prepare a coating liquid 8 for an infrared absorbing layer.

Acryt 8UA-301 (urethane-modified acrylic polymer: manufactured by Taisei Fine Chemical Co., Ltd.) 911 parts by mass ADK STAB AO-80 (phenol-based antioxidant: manufactured by ADEKA Corporation) 3.9 parts by mass Cherest MZ-8 (organic solvent soluble type) Chelating agent, pH 7.6: manufactured by Kyrest Co.) 2.8 parts by mass 82 parts by mass of methyl ethyl ketone.

(Preparation of laminated film 8)
A laminated film 8 was produced in the same manner as the laminated film 1 except that the infrared absorbing layer coating liquid 8 was used instead of the infrared absorbing layer coating liquid 1.

  When the film surface pH of the infrared absorbing layer of the laminated film 8 was measured in the same manner as described above, the film surface pH was 7.5.

<Example 5>
(Preparation of coating solution 9 for infrared absorption layer)
In the same procedure, except that Adekastab AO-80 of the infrared absorbing layer coating liquid 2 was changed to Adekastab AO-50 (phenolic antioxidant: manufactured by ADEKA Corporation), the infrared absorbing layer coating liquid 9 was used. Was prepared.

(Production of laminated film 9)
A laminated film 9 was prepared in the same manner as the laminated film 2 except that the infrared absorbing layer coating liquid 9 was used instead of the infrared absorbing layer coating liquid 2.

  When the film surface pH of the infrared absorbing layer of the laminated film 9 was measured in the same manner as described above, the film surface pH was 7.5.

<Example 6>
(Preparation of coating liquid 10 for infrared absorption layer)
The infrared absorbing layer coating solution 10 was prepared in the same procedure except that ADK STAB AO-80 of the infrared absorbing layer coating solution 2 was changed to Tinuvin PA144 (a hindered amine-based antioxidant: manufactured by BASF Japan Ltd.). Prepared.

(Preparation of laminated film 10)
A laminated film 10 was produced in the same manner as the laminated film 2 except that the infrared absorbing layer coating liquid 10 was used instead of the infrared absorbing layer coating liquid 2.

  When the film surface pH of the infrared absorbing layer of the laminated film 10 was measured in the same manner as described above, the film surface pH was 7.5.

<Example 7>
(Preparation of coating liquid 11 for infrared absorption layer)
In the same procedure, except that ADK STAB AO-80 of the infrared absorbing layer coating liquid 2 was changed to Tinuvin 765 (hindered amine antioxidant: manufactured by BASF Japan Co., Ltd.), the infrared absorbing layer coating liquid 11 was prepared. Prepared.

(Production of laminated film 11)
The laminated film 11 was produced in the same manner as the laminated film 2 except that the infrared absorbing layer coating liquid 11 was used instead of the infrared absorbing layer coating liquid 2.

  When the film surface pH of the infrared absorption layer of the laminated film 11 was measured in the same manner as described above, the film surface pH was 7.5.

<Example 8>
(Preparation of coating liquid 12 for infrared absorption layer)
In the same procedure, except that ADK STAB AO-80 of the infrared absorbing layer coating liquid 2 was changed to Tinuvin 660DF (a hindered amine antioxidant: manufactured by BASF Japan Co., Ltd.), the infrared absorbing layer coating liquid 12 was prepared. Prepared.

(Preparation of laminated film 12)
A laminated film 12 was produced in the same manner as the laminated film 2 except that the infrared absorbing layer coating liquid 12 was used instead of the infrared absorbing layer coating liquid 2.

  When the film surface pH of the infrared absorbing layer of the laminated film 12 was measured in the same manner as described above, the film surface pH was 7.5.

<Example 9>
(Preparation of coating liquid 13 for infrared absorption layer)
Infrared absorbing layer coating liquid 13 was prepared in the same procedure except that ADK STAB AO-80 of infrared absorbing layer coating liquid 2 was changed to Chimassorb 2020FDL (a hindered amine-based antioxidant: manufactured by BASF Japan Co., Ltd.). did.

(Production of laminated film 13)
A laminated film 13 was produced in the same manner as the laminated film 2, except that the infrared absorbing layer coating liquid 13 was used instead of the infrared absorbing layer coating liquid 2.

  When the film surface pH of the infrared absorbing layer of the laminated film 13 was measured in the same manner as described above, the film surface pH was 7.5.

<Example 10>
(Preparation of coating solution 14 for infrared absorption layer)
In the same procedure, except that ADK STAB AO-80 of the infrared absorbing layer coating liquid 2 was changed to ADK STAB 2112 (phosphite-based antioxidant: manufactured by ADEKA Corporation), the infrared absorbing layer coating liquid 24 was prepared. Prepared.

(Production of laminated film 14)
A laminated film 14 was produced in the same manner as the laminated film 2 except that the infrared absorbing layer coating liquid 14 was used instead of the infrared absorbing layer coating liquid 2.

  When the film surface pH of the infrared absorbing layer of the laminated film 14 was measured in the same manner as described above, the film surface pH was 7.5.

<Example 11>
(Preparation of coating solution 15 for infrared absorption layer)
Except that ADK STAB AO-80 of the infrared absorbing layer coating liquid 2 was changed to ADK STAB HP-10 (phosphite antioxidant: manufactured by ADEKA Corporation), the coating procedure for the infrared absorbing layer was performed in the same procedure. 15 were prepared.

(Preparation of laminated film 15)
A laminated film 15 was prepared in the same manner as the laminated film 2, except that the infrared absorbing layer coating liquid 15 was used instead of the infrared absorbing layer coating liquid 2.

  When the film surface pH of the infrared absorbing layer of the laminated film 15 was measured in the same manner as described above, the film surface pH was 7.5.

<Example 12>
(Preparation of laminated film 16)
An ultraviolet-curable hard coat layer was formed on the infrared absorbing layer of the laminated film 9 produced above, to produce a laminated film 16.

The hard coat layer was coated with a gravure coater using a hard coat liquid UV-3701 (manufactured by Toagosei Co., Ltd.), dried at a drying temperature of 90 ° C., and coated with a high-pressure mercury lamp at an integrated light quantity of 300 mJ / cm ^2. The layer was cured, and a hard coat layer was formed so that the dry film thickness became 2 μm.

<Example 13>
(Production of laminated film 17)
The hard coat liquid UV-3701 was applied on a 23 μm-thick polyethylene terephthalate film (A4300 manufactured by Toyobo) using a gravure coater, dried at a drying temperature of 90 ° C., and then integrated with a high-pressure mercury lamp to obtain an integrated light quantity of 300 mJ / cm. As No. ² , the coating layer was cured, and a hard coat layer was formed so that the dry film thickness became 2 μm. The adhesive layer coating solution 1 prepared above was further applied to the surface of the film opposite to the hard coat layer using a die coater, and dried at 80 ° C. for 1 minute to obtain an adhesive layer (dry film thickness: 10 μm). I got Thereafter, the surface of the infrared absorbing layer of the laminated film 9 produced above was bonded to the surface of the adhesive layer of the film formed with the hard coat layer produced above, whereby a laminated film 17 was produced.

<Comparative Example 5>
(Preparation of coating liquid 18 for infrared absorption layer)
The following materials were mixed and stirred for 30 minutes to prepare a coating liquid 18 for an infrared absorbing layer.

Acryt 8UA-301 (urethane-modified acrylic polymer: manufactured by Taisei Fine Chemical Co., Ltd.) 638 parts by mass ATO dispersion (manufactured by Advanced Nano Products: 35% by mass MIBK dispersion) 238 parts by mass ADK STAB AO-50 (phenolic antioxidant: ADEKA CORPORATION Ltd.) 3.9 parts by weight CHELEST _{400 (EDTA · 4Na · 4H 2} O, pH11.2: Chelest Corp.) 1.4 parts by weight Methyl ethyl ketone 115 parts by weight.

(Preparation of laminated film 18)
A laminated film 18 was produced in the same manner as the laminated film 1 except that the infrared absorbing layer coating liquid 18 was used instead of the infrared absorbing layer coating liquid 1.

  When the film surface pH of the infrared absorbing layer of the laminated film 18 was measured in the same manner as described above, the film surface pH was 5.5.

<Example 14>
(Preparation of coating solution 19 for infrared absorption layer)
The following materials were mixed and stirred at room temperature for 30 minutes to prepare a coating solution 19 for an infrared absorbing layer.

Acryt 8UA-301 (urethane-modified acrylic polymer: manufactured by Taisei Fine Chemical Co., Ltd.) 633 parts by mass ATO dispersion (manufactured by Advanced Nano Products: 35% by mass MIBK dispersion) 238 parts by mass ADK STAB AO-50 (phenolic antioxidant: ADEKA CORPORATION Ltd.) 3.9 parts by weight CHELEST _{400 (EDTA · 4Na · 4H 2} O, pH11.2: Chelest Corp.) 2.8 parts by weight Methyl ethyl ketone 115 parts by weight.

(Preparation of laminated film 19)
A laminated film 19 was prepared in the same manner as the laminated film 1 except that the infrared absorbing layer coating liquid 19 was used instead of the infrared absorbing layer coating liquid 1.

  When the film surface pH of the infrared absorbing layer of the laminated film 19 was measured in the same manner as described above, the film surface pH was 7.5.

<Example 15>
(Preparation of coating solution 20 for infrared absorption layer)
The following materials were mixed and stirred at room temperature for 30 minutes to prepare a coating solution 20 for an infrared absorbing layer.

Acryt 8UA-301 (urethane-modified acrylic polymer: manufactured by Taisei Fine Chemical Co., Ltd.) 633 parts by mass ATO dispersion (manufactured by Advanced Nano Products: 35% by mass MIBK dispersion) 238 parts by mass ADK STAB AO-50 (phenolic antioxidant: ADEKA CORPORATION Ltd.) 3.9 parts by weight CHELEST _{400 (EDTA · 4Na · 4H 2} O, pH11.2: Chelest Corp.) 5.6 parts by weight Methyl ethyl ketone 115 parts by weight.

(Preparation of laminated film 20)
A laminated film 20 was prepared in the same manner as the laminated film 1, except that the infrared absorbing layer coating liquid 20 was used instead of the infrared absorbing layer coating liquid 1.

  When the film surface pH of the infrared absorbing layer of the laminated film 20 was measured in the same manner as described above, the film surface pH was 10.0.

<Example 16>
(Preparation of coating liquid 21 for infrared absorption layer)
The following materials were mixed and stirred at room temperature for 30 minutes to prepare a coating liquid 21 for an infrared absorbing layer.

Aronix M-305 (pentaerythritol triacrylate / pentaerythritol tetraacrylate: manufactured by Toagosei Co., Ltd.) 149 parts by mass Purple UV-7600B (urethane acrylate UV curable resin: manufactured by Nippon Synthetic Chemical Co., Ltd.) 70 parts by mass YMF-02A (Cesium-containing composite tungsten oxide (Cs _0.33 WO ₃ ), solid content: 28.7% by mass, particle concentration: 18.5% by mass, average particle size: 15 nm, refractive index: 1.66: manufactured by Sumitomo Metal Mining Co., Ltd.) Parts by mass ADK STAB AO-50 (phenolic antioxidant: manufactured by ADEKA Corporation) 4.9 parts by mass Chelesto MZ-8 (organic solvent-soluble chelating agent, pH 7.6: manufactured by Kirest Co., Ltd.) 7.0 parts by mass Irgacure 819 (photopolymerization initiator: BASF Japan Ltd.) Parts by mass: Fentgent 650A (fluorine surfactant: manufactured by Neos Co., Ltd.) 0.1 part by mass 4-methyl-2-pentanone 386 parts by mass.

(Production of laminated film 21)
The infrared absorbing layer coating solution 21 prepared above was applied to a 50 μm-thick polyethylene terephthalate film (A4300 manufactured by Toyobo Co., Ltd.) using a gravure coater, and dried at a drying zone temperature of 100 ° C. for 1 minute. Was used to cure the coating layer at an integrated light quantity of 300 mJ / cm ² to form an infrared absorbing layer.

  Further, using a die coater, the adhesive layer coating solution 1 prepared above was applied to a separator (NS-23MA: manufactured by Nakamoto Pax Co.) and dried at 80 ° C. for 1 minute to form an adhesive layer. Then, the polyethylene terephthalate surface and the adhesive layer surface of the film on which the infrared absorbing layer was formed as described above were adhered to each other to produce a laminated film 21. The thickness of the infrared absorbing layer was 5 μm, and the thickness of the adhesive layer was 10 μm.

  When the film surface pH of the infrared absorption layer of the laminated film 21 was measured in the same manner as described above, the film surface pH was 7.5.

<Example 17>
(Preparation of coating liquid 22 for infrared absorption layer)
The following materials were mixed and stirred at room temperature for 30 minutes to prepare a coating liquid 22 for an infrared absorbing layer.

Aronix M-305 (pentaerythritol triacrylate / pentaerythritol tetraacrylate: manufactured by Toagosei Co., Ltd.) 150 parts by mass Purple UV-7600B (urethane acrylate UV curable resin: manufactured by Nippon Synthetic Chemical Co., Ltd.) 70 parts by mass YMF-02A (Cesium-containing composite tungsten oxide (Cs _0.33 WO ₃ ), solid content: 28.7% by mass, particle concentration: 18.5% by mass, average particle size: 15 nm, refractive index: 1.66: manufactured by Sumitomo Metal Mining Co., Ltd.) Parts by mass ADK STAB AO-50 (phenolic antioxidant: manufactured by ADEKA Corporation) 4.9 parts by mass TBAB-100A (tetrabutylammonium bromide: manufactured by Lion Corporation) 5.3 parts by mass Irgacure 819 (photopolymerization initiator: BASF Japan Co., Ltd.) 15 quality Parts by mass: Fentgent 650A (fluorinated surfactant: manufactured by Neos Co., Ltd.) 0.1 part by mass 386 parts by mass of 4-methyl-2-pentanone.

(Production of laminated film 22)
A laminated film 22 was prepared in the same manner as the laminated film 21 except that the infrared absorbing layer coating liquid 22 was used instead of the infrared absorbing layer coating liquid 21.

  When the film surface pH of the infrared absorbing layer of the laminated film 22 was measured in the same manner as described above, the film surface pH was 9.0.

<Comparative Example 6>
(Preparation of coating liquid 23 for infrared absorption layer)
The following materials were mixed and stirred at room temperature for 30 minutes to prepare a coating liquid 23 for an infrared absorbing layer.

Aronix M-305 (pentaerythritol triacrylate / pentaerythritol tetraacrylate: manufactured by Toagosei Co., Ltd.) 20 parts by mass Violet UV-7600B (urethane acrylate UV curable resin: manufactured by Nippon Synthetic Chemical Co., Ltd.) 105 parts by mass Cellnax CX -Z410BK (AZO dispersion, solid content concentration: 40%, particle diameter: 80 to 120 nm: manufactured by Nissan Chemical Industries, Ltd.) 507 parts by mass ADK STAB AO-50 (phenolic antioxidant: manufactured by ADEKA Corporation) 4.9 parts by mass _{400 (EDTA · 4Na · 4H 2} O, pH11.2: Chelest Corp.) 1.8 parts by mass Irgacure 819 (photopolymerization initiator manufactured by BASF Japan Ltd.) 15 parts by weight Ftergent 650A (fluorine surfactant : Made by Neos Co., Ltd.) 0.1 parts by mass 4-346 parts by mass of 4-methyl-2-pentanone.

(Production of laminated film 23)
A laminated film 23 was produced in the same manner as the laminated film 21 except that the infrared absorbing layer coating liquid 23 was used instead of the infrared absorbing layer coating liquid 21.

  When the film surface pH of the infrared absorbing layer of the laminated film 23 was measured in the same manner as described above, the film surface pH was 6.2.

<Example 18>
(Preparation of coating solution 24 for infrared absorption layer)
The following materials were mixed and stirred at room temperature for 30 minutes to prepare a coating liquid 24 for an infrared absorbing layer.

Aronix M-305 (pentaerythritol triacrylate / pentaerythritol tetraacrylate: manufactured by Toagosei Co., Ltd.) 15 parts by mass Purple UV-7600B (urethane acrylate UV curable resin: manufactured by Nippon Synthetic Chemical Co., Ltd.) 105 parts by mass Celnax CX -Z410BK (AZO dispersion, solid content concentration: 40%, particle diameter: 80 to 120 nm: manufactured by Nissan Chemical Industries, Ltd.) 507 parts by mass ADK STAB AO-50 (phenolic antioxidant: manufactured by ADEKA Corporation) 4.9 parts by mass MZ-8 (organic solvent-soluble chelating agent, pH 7.6: manufactured by Kyrest Co., Ltd.) 7.0 parts by mass Irgacure 819 (photopolymerization initiator: manufactured by BASF Japan Ltd.) 15 parts by mass Futagent 650A (fluorine-based interface) Activator: Neos Corporation) 0 1 part by weight of 4-methyl-2-pentanone 346 parts by weight.

(Production of laminated film 24)
A laminated film 24 was prepared in the same manner as the laminated film 21 except that the infrared absorbing layer coating liquid 24 was used instead of the infrared absorbing layer coating liquid 21.

  When the film surface pH of the infrared absorbing layer of the laminated film 24 was measured in the same manner as described above, the film surface pH was 7.0.

<Example 19>
(Preparation of coating liquid 25 for infrared absorption layer)
The following materials were mixed and stirred at room temperature for 30 minutes to prepare a coating liquid 25 for an infrared absorbing layer.

Aronix M-305 (pentaerythritol triacrylate / pentaerythritol tetraacrylate: manufactured by Toagosei Co., Ltd.) 15 parts by mass Purple UV-7600B (urethane acrylate UV curable resin: manufactured by Nippon Synthetic Chemical Co., Ltd.) 105 parts by mass Celnax CX -Z410BK (AZO dispersion, solid content concentration: 40%, particle diameter: 80 to 120 nm: manufactured by Nissan Chemical Industries, Ltd.) 507 parts by mass ADK STAB AO-50 (phenolic antioxidant: manufactured by ADEKA Corporation) 4.9 parts by mass _{400 (EDTA · 4Na · 4H 2} O, pH11.2: Chelest Corp.) 7.0 parts by mass Irgacure 819 (photopolymerization initiator manufactured by BASF Japan Ltd.) 15 parts by weight Ftergent 650A (fluorine surfactant : Made by Neos Co., Ltd.) 0.1 parts by mass 4-346 parts by mass of 4-methyl-2-pentanone.

(Production of laminated film 25)
A laminated film 25 was prepared in the same manner as the laminated film 21 except that the infrared absorbing layer coating liquid 25 was used instead of the infrared absorbing layer coating liquid 21.

  When the film surface pH of the infrared absorbing layer of the laminated film 25 was measured in the same manner as described above, the film surface pH was 10.5.

<Example 20>
(Preparation of coating liquid L1 for low refractive index layer)
430 parts by mass of a 10% by mass aqueous solution of colloidal silica (Snowtex OXS, manufactured by Nissan Chemical Industries, Ltd.), 150 parts by mass of a 3% by mass aqueous solution of boric acid, 85 parts by mass of water, polyvinyl alcohol (JP-45, Povar Co., Ltd., polymerization degree 4500, saponification degree 88 mol%) 4 mass% aqueous solution 300 mass parts, and surfactant 5 mass% aqueous solution (softazoline LSB-R, Kawaken Fine Chemical Co., Ltd.) 3 mass parts at 45 ° C. The coating liquid L1 was added in this order, and finished to 1000 parts by mass with pure water to prepare a coating liquid L1 for a low refractive index layer.

(Preparation of coating liquid H1 for high refractive index layer)
To 10 L (liter) of an aqueous suspension (TiO ₂ concentration: 100 g / L) in which titanium dioxide hydrate was suspended in water, 30 L of an aqueous sodium hydroxide solution (concentration: 10 mol / L) was added under stirring. After raising the temperature to 5 ° C. and aging for 5 hours, the base-treated titanium compound was obtained by neutralizing with hydrochloric acid, filtering and washing with water. In the above reaction (treatment), titanium dioxide hydrate used was obtained by thermally hydrolyzing an aqueous solution of titanium sulfate according to a known method.

The base-treated titanium compound was suspended in pure water so as to have a TiO ₂ concentration of 20 g / L, and 0.4 mol% of citric acid was added to the amount of TiO ₂ with stirring to raise the temperature. When the liquid temperature reached 95 ° C., concentrated hydrochloric acid was added so that the hydrochloric acid concentration became 30 g / L, and the mixture was stirred for 3 hours while maintaining the liquid temperature.

  When the pH and the zeta potential of the obtained titanium oxide sol aqueous dispersion were measured, the pH was 1.4 and the zeta potential was +40 mV. Further, when the particle size was measured by using Zetasizer Nano manufactured by Malvern, the volume average particle size was 35 nm, and the monodispersity was 16%.

  1 kg of pure water was added to 1 kg of a 20.0% by mass aqueous titanium oxide sol dispersion containing rutile-type titanium oxide particles having a volume average particle diameter of 35 nm.

2 kg of pure water was added to 0.5 kg of the 10.0% by mass aqueous titanium oxide sol dispersion obtained above, and then heated to 90 ° C. Thereafter, 1.3 kg of an aqueous solution of silicic acid having a SiO ₂ concentration of 2.0% by mass was gradually added, and then the obtained dispersion was subjected to a heat treatment at 175 ° C. for 18 hours in an autoclave, followed by further concentration. An aqueous sol dispersion of 20.0% by mass of silica-modified titanium oxide particles of titanium oxide having a rutile structure and a coating layer of SiO ₂ was obtained.

  Next, 320 parts by mass of a 20.0% by mass sol aqueous dispersion of silica-modified titanium oxide particles, 120 parts by mass of a 1.92% by mass aqueous solution of citric acid, and 20 parts by mass of a 10% by mass polyvinyl alcohol solution (PVA-103; 300, saponification degree 99 mol%, manufactured by Kuraray Co., Ltd.), 100 parts by mass of a 3% by mass aqueous solution of boric acid, 350 parts by mass of a 4% by mass solution of polyvinyl alcohol (manufactured by Kuraray Co., PVA-124, polymerization degree 2400, saponification degree 88 mol%) ), And 1 part by mass of a 5% by mass solution of a surfactant (Softazoline LSB-R, manufactured by Kawaken Fine Chemical Co., Ltd.) are added in order at 45 ° C., and finished to 1000 parts by mass with pure water to obtain a coating solution for a high refractive index layer. H1 was prepared.

(Production of laminated film 26)
The thickness of the low-refractive-index layer coating liquid L1 and the high-refractive-index layer coating liquid H1 obtained above was heated to 45 ° C. using a slide hopper coating apparatus capable of 9-layer coating. On a 50 μm-thick polyethylene terephthalate film (A4300 manufactured by Toyobo), the lowermost layer and the uppermost layer are low-refractive-index layers, and the other layers are alternately alternately dried. A total of 9 layers were simultaneously coated so that each layer had a thickness of 130 nm. The mixed region (mixed layer) between layers and the measurement (confirmation) of the film thickness were confirmed by cutting the laminated film (dielectric multilayer film sample) and cutting the cut surface with a high refractive index material (TiO 2) using an XPS surface analyzer. By measuring the amount of ₂ ) and the low refractive index material (SiO ₂ ), it was confirmed that the thickness of each layer described above was secured.

  Immediately after the application, a cool air of 5 ° C. was blown to set. At this time, even if the surface was touched with the finger, the time (set time) until the finger did not stick was 5 minutes.

  After the setting was completed, the substrate was dried by blowing hot air at 80 ° C. to produce a dielectric multilayer unit having nine layers. The refractive index of the high refractive index layer formed as described above was 1.95, and the refractive index of the low refractive index layer was 1.45.

  Next, using a gravure coater, the infrared absorbing layer coating solution 9 prepared above was applied to the surface of the polyethylene terephthalate film opposite to the dielectric multilayer unit, and dried at a drying temperature of 100 ° C. for 1 minute to obtain an infrared ray. An absorption layer was formed.

  Further, the adhesive layer coating solution 1 prepared above was applied to a separator (NS-23MA: manufactured by Nakamoto Pax Co.) using a die coater and dried at 80 ° C. for 1 minute to form an adhesive layer. Then, the surface of the dielectric multilayer unit and the surface of the adhesive layer of the film on which the infrared absorbing layer was formed as described above were bonded to each other to form a laminated film 26. The thickness of the infrared absorbing layer of the laminated film 26 was 5 μm, and the thickness of the adhesive layer was 10 μm.

  When the film surface pH of the infrared absorbing layer of the laminated film 26 was measured in the same manner as described above, the film surface pH was 7.5.

<Example 21>
(Production of laminated film 27)
A laminated film 27 was produced in the same manner as in the production of the laminated film 26, except that the infrared absorbing layer coating liquid 2 was used instead of the infrared absorbing layer coating liquid 9.

  When the film surface pH of the infrared absorbing layer of the laminated film 27 was measured in the same manner as described above, the film surface pH was 7.5.

<Comparative Example 7>
(Preparation of coating liquid 28 for infrared absorption layer)
The following materials were mixed and stirred at room temperature for 30 minutes to prepare a coating liquid 28 for an infrared absorbing layer.

Sartomer SR399E (manufactured by Sartomer Japan KK) 100 parts by mass YMF-01 (cesium-containing composite tungsten oxide (Cs _0.33 WO ₃ ): manufactured by Sumitomo Metal Mining Co., Ltd.) 500 parts by mass Irgacure 127 (photopolymerization initiator: BASF Japan Co., Ltd.) 5 parts by mass Toluene 100 parts by mass (Preparation of laminated film 28)
One surface of a 25 μm thick polyethylene terephthalate film (trade name “PET25T600EW07” manufactured by Mitsubishi Chemical Polyester Film Co., Ltd.) is coated with the infrared absorbing layer coating solution 28 prepared above using a gravure coater, and the coating layer is dried. It was dried at an interval temperature of 70 ° C. for 1 minute. Thereafter, the coating layer was cured with an integrated light amount of 125 mJ / cm ² using a high-pressure mercury lamp to form an infrared absorbing layer.

  Further, using a die coater, the adhesive layer coating solution 1 prepared above was applied to a separator (NS-23MA: manufactured by Nakamoto Pax Co.) and dried at 80 ° C. for 1 minute to form an adhesive layer.

  Next, the PET surface and the adhesive layer surface of the film on which the infrared absorbing layer was formed were attached to each other to produce a laminated film 28. The thickness of the infrared absorbing layer of the laminated film 28 was 4 μm, and the thickness of the adhesive layer was 10 μm.

  When the film surface pH of the infrared absorbing layer of the laminated film 28 was measured in the same manner as described above, the film surface pH was 6.0.

≫Evaluation of laminated film≫
The following evaluation was performed about the laminated film produced above. The results are shown in Tables 1 and 2 below.

<Evaluation of weather resistance>
As an accelerated weather resistance tester, a xenon weather meter using a xenon lamp was used, and at 180 mW / cm ^{2 of} illuminance, temperature of 40 ° C. and humidity of 50% RH, water jet was repeatedly performed for 18 minutes during irradiation for 120 minutes, Thereafter, irradiation was performed for 2000 hours (weather resistance test). Thereafter, measurement of discoloration, observation of the presence or absence of cracks, and measurement of haze were performed by the following methods.

(Measurement of discoloration)
The laminated film samples after weathering test described above, the transmittance was measured with a spectrophotometer Hitachi U-4100 equivalent ^{performance, L} * in the L ^* a * ^{b *} color ^space, a *, calculates ^{b *,} The change ΔE in the color space (after the weather resistance test) − (before the weather resistance test (initial)) was calculated. ΔE may be 3.5 or less, preferably less than 3, and particularly preferably less than 2.

(Observation of cracks)
The outermost layer on the infrared absorption layer side of the laminated film sample of 15 cm × 5 cm (75 cm ² ) is visually observed, the number of cracks is counted, and the evaluation is made based on the average value of 10 laminated film samples according to the following criteria. did.

◎: 0 pieces,
○: 1 to 5,
○ △: 6 to 10,
Δ: 11 to 25,
×: 26 or more.

  Note that ○, ○, ○ △, and Δ can be used without any practical problems.

(Haze measurement)
Based on ISO 14782, the average value of 15 cm × 5 cm (75 cm ² ) of the laminated film sample measured with a haze meter (NDH-7000, manufactured by Nippon Denshoku Industries Co., Ltd.) was defined as a haze measurement value. The haze value of the heat shielding film is preferably 1.5% or less.

<Evaluation of heat insulation>
The transmittance and 5 ° reflectance (%) of the measurement sample were measured using a spectrophotometer (using an integrating sphere, manufactured by Hitachi, Ltd., product name: U-4000 type). Next, in accordance with the method described in JIS R3106, the measured values and the solar reflectance weighting factor were subjected to arithmetic processing to determine the solar reflectance and the solar transmittance, and further the solar heat gain (Tts).

  The smaller the value of Tts, the better the heat shielding property.

  The rate of change in the thermal insulation was determined by calculating Tts after the above-mentioned weather resistance test, and (Tts after the weather resistance test-Tts before the weather resistance test) / (Tts before the weather resistance test) × 100 (%). Was determined.

<Acid rain resistance>
The laminated film prepared above was immersed in a 5% aqueous solution of ammonium sulfate at 30 ° C. for 7 days. Then, a laminated film adhered to the glass film, the transmittance was measured with a spectrophotometer Hitachi U-4100 equivalent ^{performance, L} * in the L ^* a * ^{b *} color ^space, a *, calculates ^{b *,} The change ΔE in the color space (after immersion in an aqueous solution of ammonium sulfate) − (before immersion) was calculated.

：: less than ΔE 1,
○ △: ΔE 1 or more and less than 2,
Δ: ΔE 2 or more and less than 3,
×: ΔE 3 or more.

  In addition, ○, ○ △, and Δ can be used without any practical problem.

  Tables 1 and 2 show the above evaluation results.

  According to the above Tables 1 and 2, when the infrared absorbing layer contains an infrared absorbing agent and an antioxidant and has a film surface pH of 6.5 or more, the infrared absorbing layer is excellent in infrared shielding performance, hardly discolors, and is free from cracks. It was shown that a laminated film in which the increase in haze was suppressed by suppressing discoloration was small. Further, when the pH of the film surface is set to 6.5 or more, acidification of the film occurs at a portion where the film is exposed to the acid rain, and it is possible to suppress the infrared absorbing layer from being deteriorated.

  On the other hand, when the film surface pH of the infrared absorbing layer is less than 6.5 as in the laminated films 5, 6, 18, 23, and 28, the film is easily discolored under high humidity and exposure to sunlight, and cracks are generated. Cheap. It was also found that the infrared shielding performance was reduced. Further, discoloration occurred after immersion in the ammonium sulfate aqueous solution.

  If the infrared absorbent is CWO, it has excellent infrared shielding performance and a high effect of suppressing discoloration. In particular, when the film surface pH is 7.5 to 10.5 and the infrared absorbent is CWO, the effects of the invention can be more remarkably obtained.

  Comparing the results of the laminated films 9 to 15, it is understood that the use of a phenol-based or hindered amine-based antioxidant as the antioxidant has an excellent effect of suppressing discoloration under high humidity and exposure to sunlight.

  Moreover, it was found that the shielding effect can be further improved by further providing the multilayer film with the dielectric multilayer film as in the multilayer films 26 and 27.

  In the laminated films 21, 22, 24, and 25 provided with the infrared absorbing layer having the hard coat property, the surface scratch resistance was further improved.

  This application is based on Japanese Patent Application No. 2014-245412 filed on December 3, 2014, the disclosure of which is incorporated by reference in its entirety.

Claims (6)

A substrate,
An infrared absorber, a resin, and an infrared absorbing layer containing an antioxidant, disposed on one surface of the base material,
The infrared absorber is a cesium-containing composite tungsten oxide,
A laminated film in which the surface pH of the surface of the infrared absorbing layer opposite to the substrate is 8.5 or more . A substrate,
An infrared absorber, a resin, and an infrared absorbing layer containing an antioxidant, disposed on one surface of the base material,
The infrared absorber is a cesium-containing composite tungsten oxide,
Wherein Ri der film surface pH of the substrate opposite the surface 6.5 or more infrared-absorbing layer,
A laminated film , wherein the infrared absorbing layer has a quaternary ammonium salt (not included in the polymer structure), or ethylenediaminetetraacetic acid or a salt thereof . The laminated film according to claim 2, wherein the quaternary ammonium salt (not included in the polymer structure) is tetrabutylammonium bromide. The laminated film according to any one of claims 1 to 3, wherein the antioxidant is at least one selected from the group consisting of a phenolic antioxidant and a hindered amine antioxidant. The laminated film according to any one of claims 1 to 4 , wherein the infrared absorbing layer is obtained by curing a composition containing an ultraviolet curable resin and a photopolymerization initiator. And a low refractive index layer and the high refractive index layer stacked alternately, further comprising a dielectric multilayer film having at least one reflection peak in the wavelength region of 800～1300Nm, any one of claims 1 to 5 3. The laminated film according to item 1.