Laminated structure

Abstract

To provide a laminated structure which suppresses light coloring development by irradiation with ultraviolet light.SOLUTION: A laminated structure includes a plurality of transparent base materials, and at least one intermediate film provided so as to be interposed between the plurality of transparent base materials, wherein in the intermediate film, the surface of composite tungsten oxide fine particles is formed of an intermediate film composition containing: at least a composite surface-treated composite tungsten oxide fine particles, in which surface-treated composite tungsten oxide fine particles that are coated with a coating film containing one or more selected from a hydrolyzed product of a metal chelate compound, a polymer of a hydrolyzed product of a metal chelate compound, a hydrolyzed product of a metal cyclic oligomer compound, and a polymer of a hydrolyzed product of a metal cyclic oligomer compound are coated with a metal coupling agent; and an ionomer resin.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to laminated structures. [Background technology]

[0002] Conventionally, a type of safety glass proposed for automobiles and the like is one in which a laminated glass is constructed by sandwiching an interlayer film having heat-shielding properties between two sheets of glass, with the aim of blocking incident solar energy through the laminated glass and reducing the cooling load and the heat felt by people.

[0003] For example, Patent Document 1 discloses that fine particles having heat ray shielding properties, such as tungsten oxide fine particles or composite tungsten oxide fine particles, are added to a resin together with a metal coupling agent, an interlayer film is formed from the composition, and this interlayer film is interposed between two laminated sheets selected from sheet glass or the like to form a laminated structure having heat ray shielding properties. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2005 / 087680 Summary of the Invention [Problem to be solved by the invention]

[0005] However, in the laminated structure disclosed in Patent Document 1, the interlayer film may become discolored due to ultraviolet rays contained in sunlight. This is due to the effect of light-induced coloring of the composite tungsten oxide fine particles. For example, when the laminated structure is used in automobile safety glass, even slight coloring can impair safety.

[0006] The present invention has been made in view of the above-mentioned problems, and has an object to provide a technique for suppressing the photocoloration phenomenon caused by ultraviolet irradiation in a laminated structure. [Means for solving the problem]

[0007] One embodiment of the present invention comprises: A plurality of transparent substrates; and at least one intermediate film interposed between the plurality of transparent substrates, The interlayer film is formed from an interlayer film composition containing at least composite surface-treated composite tungsten oxide microparticles, in which the surfaces of composite tungsten oxide microparticles are coated with a coating film containing one or more selected from the group consisting of hydrolysis products of metal chelate compounds, polymers of hydrolysis products of metal chelate compounds, hydrolysis products of metal cyclic oligomer compounds, and polymers of hydrolysis products of metal cyclic oligomer compounds, and the composite surface-treated composite tungsten oxide microparticles are coated with a metal coupling agent, and an ionomer resin. It is a laminated structure. [Effects of the Invention]

[0008] According to the present invention, it is possible to suppress the photocoloration phenomenon caused by ultraviolet irradiation in a laminated structure. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a schematic diagram showing the crystal structure of a composite tungsten oxide having a hexagonal crystal structure. DETAILED DESCRIPTION OF THE INVENTION

[0010] The photocoloration phenomenon in laminated structures is thought to be caused in part by a change in the valence of composite tungsten oxide particles (hereinafter simply referred to as MWO particles) dispersed in the interlayer film between transparent substrates. Specifically, when the interlayer film is irradiated with ultraviolet light, its resin component may decompose, generating hydrogen radicals. These hydrogen radicals may then be doped into the MWO particles, compensating for the charge and changing the valence of the MWO particles. This change in valence can cause fluctuations in the light transmittance of the MWO particles, which can result in coloration of the interlayer film. Another possible cause is that when the interlayer film is exposed to the atmosphere, for example, moisture that penetrates into the interlayer film from the atmosphere may decompose the surface of the MWO particles, causing a change in their light transmittance.

[0011] For this reason, we focused on surface treatment of MWO microparticles to form a coating film on the surface of the MWO microparticles in order to suppress the photocoloration phenomenon. Examples of such coating films include those formed from metal chelate compounds, metal cyclic oligomer compounds, or their hydrolysis products. This coating film can suppress fluctuations in visible light transmittance when the interlayer film is exposed to high-temperature and high-humidity environments. However, these coating films do not sufficiently suppress coloration due to UV irradiation, and there is room for improvement.

[0012] The present inventors have further investigated this issue and found that it is effective to use not only metal chelate compounds and metal cyclic oligomer compounds, but also metal coupling agents such as silane coupling agents for surface treatment. Specifically, they found that it is effective to surface-treat composite tungsten oxide microparticles, in which MWO microparticles are coated with hydrolysis products such as metal chelate compounds, and then surface-treat them with a silane coupling agent to form composite surface-treated composite tungsten oxide microparticles. This allows the coating film formed from hydrolysis products such as metal chelate compounds to be further coated with a metal coupling agent, allowing the coating film to be formed uniformly and firmly on the microparticle surface. Such a coating film surface-treated with a metal coupling agent can suppress photocoloration caused by ultraviolet irradiation in the interlayer film of a laminated structure.

[0013] The present invention was made based on the above findings.

[0014] In the following, surface-treated composite tungsten oxide microparticles in which a coating film is formed on the surface of MWO microparticles by surface-treating them with a metal chelate compound or the like will be simply referred to as surface-treated MWO microparticles, and composite surface-treated composite tungsten oxide microparticles in which these surface-treated MWO microparticles are further surface-treated with a metal coupling agent will be simply referred to as composite surface-treated MWO microparticles.

[0015] <One embodiment of the present invention> Hereinafter, a laminated structure according to one embodiment of the present invention will be described.

[0016] The laminated structure of this embodiment is configured to include a plurality of transparent substrates and at least one interlayer film interposed between the plurality of transparent substrates. The interlayer film is formed from an interlayer film composition containing at least composite surface-treated composite tungsten oxide particles and an ionomer resin. <1> Composite tungsten oxide particles, <2> Surface-treated composite tungsten oxide particles, <3> Composite surface treatment composite tungsten oxide particles, <4> Manufacturing of composite surface-treated composite tungsten oxide particles, <5> an interlayer film composition; <6> Interlayer film, <7> The laminated structure will now be described.

[0017] <1> Composite tungsten oxide particles First, the composite tungsten oxide fine particles before surface treatment will be described.

[0018] Composite tungsten oxide particles (MWO particles) are composed of tungsten oxide (WO3) and an electropositive element (hereinafter referred to as element M) that generates free electrons. x W y O z (where M is an electropositive element, W is tungsten, and O is oxygen) are composite tungsten oxide particles. By controlling the amount of oxygen and adding element M, composite tungsten oxide particles exhibit infrared absorption properties, with particularly strong absorption characteristics around 1000 nm.

[0019] In the MWO fine particles, the element M is not particularly limited as long as it can generate free electrons. From the viewpoint of making the MWO fine particles have a hexagonal crystal structure, the element M is preferably one or more elements selected from the group consisting of Cs, K, Rb, In, Tl, Ba, Li, Ca, Sr, Fe, and Sn.

[0020] Also, the general formula M x W y O z In the composite tungsten oxide represented by the formula: wherein the composition ranges of the element M, tungsten, and oxygen are not particularly limited, but it is preferable that the relationships 0.001≦x / y≦1 and 2.0≦z / y<4 are satisfied.

[0021] Regarding the above composition, first, the value of x / y, which indicates the amount of element M added, will be explained. If the value of x / y is 0.001 or more, a sufficient amount of free electrons is generated in the composite tungsten oxide, and the desired infrared absorption effect can be obtained. The more the amount of element M added, the greater the supply of free electrons and the higher the infrared absorption efficiency, but the effect saturates when the value of x / y is about 1. Furthermore, if the value of x / y is 1 or less, it is possible to avoid the generation of impurity phases in the composite tungsten oxide microparticles, which is preferable.

[0022] Next, the value of z / y, which indicates the control of the amount of oxygen, will be described. For z / y values, M x W y O z In the composite tungsten oxide represented by WyOz, the same mechanism as that of the tungsten oxide represented by WyOz described above also works, and in addition, even when 3.0≦z / y<4 or 2.0≦z / y≦2.2, there is a supply of free electrons due to the amount of element M added. Therefore, 2.0≦z / y<4.0 is preferable, 2.2≦z / y≦3.5 is more preferable, and 2.45≦z / y≦3.5 is even more preferable.

[0023] Furthermore, from the viewpoint of improving transmittance in the visible light region and infrared absorption characteristics, it is preferable that the MWO particles have a hexagonal crystal structure. This point will be explained using Figure 1. Figure 1 is a schematic diagram showing the crystal structure of a composite tungsten oxide having a hexagonal crystal structure.

[0024] In Fig. 1, six octahedra formed by WO6 units, denoted by reference numeral 11, are assembled to form a hexagonal void, and an element M, denoted by reference numeral 12, is arranged in this void to form one unit, and a large number of these units are assembled to form a hexagonal crystal structure. In order to obtain the effect of improving light transmission in the visible light region and improving light absorption in the infrared region, it is sufficient that the composite tungsten oxide microparticles contain the unit structure described with reference to Fig. 1, and the composite tungsten oxide microparticles may be crystalline or amorphous.

[0025] When the composite tungsten oxide microparticles having a hexagonal crystal structure have a uniform crystal structure, the amount of the added element M is preferably 0.2 or more and 0.5 or less, more preferably 0.33, in terms of the value of x / y. When the value of x / y is 0.33, it is believed that the above-mentioned element M is arranged in all of the hexagonal voids.

[0026] The crystal structure of the composite tungsten oxide is not limited to hexagonal, but may be tetragonal or cubic. The absorption position in the infrared region tends to change depending on the crystal structure, with the absorption position tending to shift to the longer wavelength side in the order of cubic < tetragonal < hexagonal. Additionally, the order of lowest absorption in the visible light region is hexagonal, tetragonal, and cubic. Therefore, for applications requiring greater transmission of light in the visible region and greater absorption of light in the infrared region, it is preferable to use a hexagonal composite tungsten oxide. However, the trends in the optical properties described here are merely rough trends, and will vary depending on the type and amount of added element and the amount of oxygen, and the present invention is not limited thereto.

[0027] The crystallite size of the MWO microparticles is not particularly limited, but from the viewpoint of obtaining higher infrared absorption characteristics, it is preferably 1 nm or more and 800 nm or less, more preferably 1 nm or more and 200 nm or less, even more preferably 1 nm or more and 100 nm or less, and most preferably 10 nm or more and 70 nm or less. Here, the crystallite size is measured using X-ray diffraction pattern measurement by powder X-ray diffraction method (θ-2θ method) and analysis by the Rietveld method. The X-ray diffraction pattern can be measured using, for example, a powder X-ray diffractometer "X'Pert-PRO / MPD" manufactured by PANalytical, Spectris Co., Ltd.

[0028] The dispersed particle diameter when MWO microparticles are dispersed in a liquid medium can be appropriately changed depending on the intended use. For example, if transparency is required, the dispersed particle diameter is preferably 800 nm or less. By setting the dispersed particle diameter to 800 nm or less, light is not completely blocked by scattering, and visibility in the visible light range is maintained while efficiently maintaining transparency.

[0029] Furthermore, when transparency in the visible light region is particularly important, it is preferable to further consider scattering by fine particles. From the perspective of reducing scattering by fine particles, the dispersed particle diameter is preferably 200 nm or less, and more preferably 100 nm or less. The reason for this is that if the dispersed particle diameter of the particles is small, scattering of light in the visible light region with wavelengths of 400 nm to 780 nm due to geometric scattering or Mie scattering is reduced, which makes it possible to avoid the interlayer film becoming like frosted glass and losing clear transparency. In other words, when the dispersed particle diameter is 200 nm or less, geometric scattering or Mie scattering is reduced, and the Rayleigh scattering region is reached. In the Rayleigh scattering region, scattered light decreases in proportion to the sixth power of the particle diameter, so scattering decreases as the dispersed particle diameter decreases, improving transparency.

[0030] Furthermore, a dispersed particle size of 100 nm or less is preferable because scattered light is significantly reduced. From the viewpoint of avoiding light scattering, a small dispersed particle size is preferable, and a dispersed particle size of 1 nm or more facilitates industrial production.

[0031] By setting the dispersed particle diameter to 800 nm or less, the haze value of the infrared-absorbing microparticle dispersion in which the composite surface-treated MWO microparticles are dispersed in a liquid medium can be set to 30% or less at a visible light transmittance of 85% or less. If the haze value is greater than 30%, the result will resemble cloudy glass and will not provide clear transparency.

[0032] The dispersed particle size can be measured using an instrument such as ELS-8000 manufactured by Otsuka Electronics Co., Ltd., which is based on the principle of dynamic light scattering.

[0033] <2> Surface-treated composite tungsten oxide particles Next, surface-treated composite tungsten oxide particles (surface-treated MWO particles) obtained by subjecting the above-mentioned MWO particles to a surface treatment using a metal chelate compound or the like will be described.

[0034] Surface-treated MWO microparticles can be obtained by surface-treating MWO microparticles with a metal chelate compound or a metal cyclic oligomer compound. This surface treatment involves hydrolyzing the hydrolysis structure of the metal chelate compound or metal cyclic oligomer compound, and then attaching the resulting hydrolysis product to the surface of the MWO microparticles to form a coating film containing at least one selected from the group consisting of hydrolysis products of metal chelate compounds, polymers of hydrolysis products of metal chelate compounds, hydrolysis products of metal cyclic oligomer compounds, and polymers of hydrolysis products of metal cyclic oligomer compounds. Here, the term "hydrolysis product" refers not only to compounds in which the hydrolysis structure of a metal chelate compound or the like is completely hydrolyzed, but also to partial hydrolysis products in which a portion of the hydrolysis structure is hydrolyzed, and polymers that undergo self-condensation via hydrolysis.

[0035] The coating film may contain unreacted metal chelate compounds or cyclic metal oligomer compounds. For example, in a reaction system in which an organic solvent such as alcohol is present during the formation of a coating film, even if sufficient water is present in the system based on the stoichiometric composition, depending on the type and concentration of the organic solvent, not all of the hydrolysis structures (e.g., alkoxy groups, ether bonds, ester bonds, etc.) of the starting metal chelate compounds or cyclic metal oligomer compounds are hydrolyzed. Therefore, depending on the surface treatment conditions described below, the compounds may remain amorphous after hydrolysis, with carbon C incorporated into their molecules. As a result, the coating film may contain unreacted substances such as metal chelate compounds, but trace amounts are not particularly problematic.

[0036] <2-1> Metal chelate compounds The metal chelate compound used to form the coating film contains a metal and a hydrolysis structure, and forms a hydrolysis product that can adhere to the surface of the MWO microparticles upon hydrolysis. From the viewpoint of improving the chemical stability of the composite surface-treated MWO microparticles, the metal contained in the metal chelate compound preferably contains at least one of Al, Zr, Ti, Si, and Zn. Furthermore, the hydrolysis structure preferably contains one or more selected from an ether bond, an ester bond, an alkoxy group, and an acetyl group. Specifically, the metal chelate compound is preferably any of a metal alkoxide, a metal acetylacetonate, and a metal carboxylate.

[0037] Specifically, the following metal chelate compounds can be used:

[0038] Examples of aluminum-based chelate compounds include aluminum alcoholates such as aluminum ethylate, aluminum isopropylate, aluminum sec-butylate, and mono-sec-butoxyaluminum diisopropylate, or polymers thereof, ethyl acetoacetate aluminum diisopropylate, aluminum tris(ethyl acetoacetate), octyl acetoacetate aluminum diisopropylate, stearyl acetoaluminum diisopropylate, aluminum monoacetylacetonate bis(ethyl acetoacetate), and aluminum tris(acetylacetonate). These compounds are alkoxy-containing aluminum chelate compounds obtained by dissolving aluminum alcoholate in an aprotic solvent, petroleum solvent, hydrocarbon solvent, ester solvent, ketone solvent, ether solvent, amide solvent, or the like, adding β-diketone, β-ketoester, monohydric or polyhydric alcohol, fatty acid, or the like to the solution, heating under reflux, and subjecting the solution to a ligand substitution reaction.

[0039] Examples of zirconia-based chelate compounds include zirconium alcoholates such as zirconium ethylate and zirconium butyrate, or polymers thereof, zirconium tributoxystearate, zirconium tetraacetylacetonate, zirconium tributoxyacetylacetonate, zirconium dibutoxybis(acetylacetonate), zirconium tributoxyethylacetoacetate, and zirconium butoxyacetylacetonate bis(ethylacetoacetate).

[0040] Examples of titanium-based chelate compounds include titanium alcoholates such as methyl titanate, ethyl titanate, isopropyl titanate, butyl titanate, and 2-ethylhexyl titanate, and polymers thereof, titanium acetylacetonate, titanium tetraacetylacetonate, titanium octylene glycolate, titanium ethylacetoacetate, titanium lactate, and titanium triethanolamine.

[0041] As the silicon-based chelate compound, a tetrafunctional silane compound represented by the general formula: Si(OR)4 (where R is the same or different monovalent hydrocarbon group having 1 to 6 carbon atoms) or its hydrolysis product can be used. Specific examples of tetrafunctional silane compounds include tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane, and tetrabutoxysilane. Furthermore, silane monomers (or oligomers) in which some or all of the alkoxy groups of these alkoxysilane monomers have been hydrolyzed to form silanol (Si-OH) groups, and polymers self-condensed through hydrolysis can also be used. Hydrolysis products of tetrafunctional silane compounds include silane monomers in which some or all of the alkoxy groups have been hydrolyzed to form silanol (Si-OH) groups, oligomers of tetramers to pentamers, and polymers (silicone resins) with a weight-average molecular weight (Mw) of about 800 to 8000. Note that not all of the alkoxysilyl groups (Si-OR) in the alkoxysilane monomers are hydrolyzed to form silanols (Si-OH) during the hydrolysis reaction.

[0042] Preferred examples of zinc-based chelate compounds include organic zinc carboxylates such as zinc octylate, zinc laurate, and zinc stearate, acetylacetone zinc chelate, benzoylacetone zinc chelate, dibenzoylmethane zinc chelate, and ethyl acetoacetate zinc chelate.

[0043] Among the above metal chelate compounds, those containing Al are particularly preferred. Al-based metal chelate compounds have a hydrolysis reaction that is not as rapid as Ti-based or Zn-based compounds, but is faster than Zr-based compounds, making it easier to control the hydrolysis reaction and form a uniform coating film on the surface of the MWO microparticles. As a result, the chemical stability of the coating film can be improved. Furthermore, production costs can be reduced and safety is also excellent.

[0044] <2-2> Metallocyclic oligomer compounds The metal cyclic oligomer compound is a cyclic oligomer having a metal and a hydrolyzed structure. From the viewpoint of improving the chemical stability of the composite surface-treated MWO microparticles, it preferably contains any of Al, Zr, Ti, Si, and Zn. Furthermore, the hydrolyzed structure preferably has one or more selected from an ether bond, an ester bond, an alkoxy group, and an acetyl group. Specifically, the metal cyclic oligomer compound is preferably at least one of Al-, Zr-, Ti-, Si-, and Zn-based cyclic oligomer compounds. Among these, cyclic aluminum oligomer compounds such as cyclic aluminum oxide octylate are preferred.

[0045] <2-3> Thickness of the coating film The thickness of the coating film of the surface-treated MWO microparticles is not particularly limited, but is preferably 0.5 nm to 100 nm. A thickness of 0.5 nm or more can improve the chemical stability of the composite surface-treated MWO microparticles, thereby improving their weather resistance. On the other hand, a thickness of 100 nm or less can maintain high optical properties, such as transparency and infrared absorption characteristics, in the interlayer. From the perspective of achieving a high level of both weather resistance and optical properties, the thickness of the coating film is more preferably 0.5 nm to 20 nm, and even more preferably 1 nm to 10 nm. The thickness of the coating film can be measured using a transmission electron microscope; the thickness of the coating film corresponds to the area of the MWO microparticles where there are no lattice fringes (arrangement of atoms in the crystal). The content of the metal chelate compound or cyclic metal oligomer compound that forms the coating film is not particularly limited as long as the above thickness is satisfied, but is preferably 35 parts by mass or more, and more preferably 40 to 150 parts by mass, per 100 parts by mass of MWO fine particles. This content is the content converted into the metal element derived from the metal chelate compound or cyclic metal oligomer compound, and is measured based on ICP atomic emission spectroscopy as shown in the examples below.

[0046] <3> Composite surface treatment composite tungsten oxide particles Next, composite surface-treated composite tungsten oxide particles (composite surface-treated MWO particles) obtained by subjecting the above-mentioned surface-treated MWO particles to a surface treatment using a metal coupling agent will be described.

[0047] Composite surface-treated MWO particles can be obtained by further surface-treating the surface-treated MWO particles with a metal coupling agent. In this surface treatment, the metal coupling agent is deposited on the coating film provided on the surface of the surface-treated MWO particles, forming a coating film containing the metal coupling agent. This allows the coating film to be formed with a uniform thickness and greater strength.

[0048] <3-1> Metal coupling agents The metal coupling agent is not particularly limited as long as it can adhere to the surface of the coating film formed using a metal chelate compound or a metal cyclic oligomer compound. Examples of the metal coupling agent that can be used include silane coupling agents, titanate coupling agents (titanate coupling agents), and aluminate coupling agents (aluminate coupling agents). The metal coupling agents may be used alone or in combination of two or more.

[0049] The silane coupling agent is not particularly limited, and examples thereof include 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-(2-aminoethylamino)propyldimethoxymethylsilane, trimethoxy[3-(phenylamino)propyl]silane, 3-(2-aminoethylamino)propyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 2-aminopropyltrieth ... -(3,4-epoxycyclohexyl)ethyltrimethoxysilane, bis(3-(triethoxysilyl)propyl)disulfide, bis(3-(triethoxysilyl)propyl)tetrasulfide, vinyltriacetoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, acryltrimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-mercaptopropylmethyldimethoxysilane, and the like can be suitably used.

[0050] The titanate coupling agent is not particularly limited, and examples thereof include tetramethoxytitanium, tetraethoxytitanium, tetraisopropoxytitanium, tetra-normal-butoxytitanium, tetraisobutoxytitanium, tetra-2-ethylhexoxidetitanium, tetrakis(methoxypropoxy)titanium, tetraphenoxytitanium, tetrabenzyloxytitanium, tetraphenylethoxytitanium, tetraphenoxyethoxytitanium, tetranaphthyloxytitanium, tetra-2-ethylhexoxytitanium, and monoethoxytriisopropoxytitanium. , diisopropoxy diisobutoxy titanium, allyloxy (polyethyleneoxy) trisisopropoxy titanium, titanium chloride triisopropoxide, titanium dichloride diethoxide, titanium 2-ethylhexoxide, titanium iodotriisopropoxide, titanium tetramethoxypropoxide, titanium tetramethylphenoxide, titanium n-nonyloxide, titanium tetrastearyl oxide, titanium triisostearoyl monoisopropoxide, etc. can be suitably used.

[0051] The aluminate coupling agent is not particularly limited, but examples that can be suitably used include aluminum ethylate, aluminum isopropylate, aluminum diisopropylate mono-secondary butylate, aluminum secondary butylate, aluminum ethyl acetoacetate diisopropylate, aluminum tris-ethyl acetoacetate, aluminum alkyl acetoacetate diisopropylate, aluminum bis-ethyl acetoacetate monoacetylacetonate, and aluminum tris-acetylacetonate.

[0052] The metal coupling agent preferably includes a silane coupling agent, and more preferably is a silane coupling agent.

[0053] Furthermore, from the viewpoint of further improving the transparency of the interlayer film, it is preferable that the metal coupling agent have at least one of an epoxy group and an amino group as a functional group. By using such a metal coupling agent, functional groups are introduced onto the surface of the composite surface-treated MWO microparticles, and the steric hindrance caused by these functional groups can suppress the aggregation of the composite surface-treated MWO microparticles. In other words, the dispersibility of the composite surface-treated MWO microparticles in the interlayer film can be improved. This can further improve the transparency of the interlayer film.

[0054] Suitable examples of silane coupling agents containing an epoxy group or an amino group in their structure include 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-(2-aminoethylamino)propyltrimethoxysilane, 3-(2-aminoethylamino)propyldimethoxymethylsilane, and trimethoxy[3-(phenylamino)propyl]silane.

[0055] <3-2> Amount of metal coupling agent coating The content of the metal coupling agent in the composite surface-treated MWO microparticles is not particularly limited, but may be adjusted appropriately depending on the visible light transmittance required for the interlayer film and the weather resistance and dispersibility of the composite surface-treated MWO microparticles. The content of the metal coupling agent is preferably 20 parts by mass or more, more preferably 20 to 100 parts by mass, and even more preferably 20 to 60 parts by mass, per 100 parts by mass of the MWO microparticles. This content is measured based on ICP atomic emission spectroscopy, as shown in the examples below.

[0056] <4> Production of composite surface-treated tungsten oxide particles Next, a method for producing composite surface-treated MWO microparticles will be described. Composite surface-treated MWO microparticles can be obtained by surface-treating MWO microparticles with a metal chelate compound or a metal cyclic oligomer compound, followed by further surface-treating with a metal coupling agent. Specifically, the method is as follows.

[0057] <4-1> Preparation process of composite tungsten oxide microparticle dispersion First, a fine powder containing MWO microparticles is added to a liquid medium and dispersed to prepare a MWO microparticle dispersion. Here, the MWO microparticles can be finely ground before being added to the liquid medium. Alternatively, the fine powder can be added to the liquid medium and then subjected to a grinding and dispersion process. This prevents the MWO microparticles from agglomerating and allows the MWO microparticles to be monodispersed in the liquid medium. Monodispersing the MWO microparticles allows for uniform surface treatment of each MWO microparticle during the surface treatment described below, resulting in the formation of a coating film with a uniform thickness. Furthermore, this method prevents the interlayer film from losing transparency due to MWO microparticle agglomerations.

[0058] The liquid medium used in preparing the MWO microparticle dispersion can be, for example, water or an organic solvent. The organic solvent can be selected from a variety of solvents, such as alcohols, ketones, and glycols, as long as they dissolve in water at room temperature. Among these, water is preferred as the liquid medium. As described below, using water as the liquid medium allows for the formation of a high-density coating film.

[0059] Although the amount of MWO microparticles added to the MWO microparticle dispersion is not particularly limited, it is preferable to adjust the dispersion concentration of the MWO microparticles in the liquid medium to 0.01% by mass or more and 80% by mass or less. By adjusting the dispersion concentration to such a level, the pH of the MWO microparticle dispersion can be adjusted to 8 or less, making it easier to maintain the MWO microparticles dispersed in the liquid medium by electrostatic repulsion.

[0060] Specific methods for pulverizing and dispersing powders containing MWO microparticles include, for example, pulverization and dispersion methods using devices such as bead mills, ball mills, sand mills, paint shakers, ultrasonic homogenizers, etc. Among these, pulverization and dispersion methods using media such as beads, balls, or Ottawa sand, such as media agitation mills like bead mills, ball mills, sand mills, and paint shakers, are preferred because they allow the desired dispersed particle size to be reached in a short time.

[0061] <4-2> Preparation process of dispersion for forming coating film Next, a dispersion for forming a coating film is prepared in order to form a coating film on the surface of the MWO fine particles.

[0062] Specifically, a metal chelate compound or a metal cyclic oligomer compound is first prepared as a surface treatment agent for forming a coating film. These may be used as is, or they may be diluted with a solvent to adjust the amount added per unit time when added to the MWO microparticle dispersion. The solvent used for dilution is preferably one that does not react with the surface treatment agent and has high compatibility with the liquid medium contained in the MWO microparticle dispersion. Specifically, alcohols, ketones, glycols, and the like are preferably used.

[0063] Next, a predetermined amount of surface treatment agent is added to the MWO microparticle dispersion over a predetermined period of time. The metal chelate compound or metal cyclic oligomer compound added to the MWO microparticle dispersion undergoes hydrolysis, resulting in a hydrolysis product or its polymer. The hydrolysis product or polymer adheres to the surface of the MWO microparticles, forming a coating film containing at least one of the hydrolysis product and its polymer. This results in a dispersion containing surface-treated MWO microparticles.

[0064] The surface treatment agent is preferably added while stirring and mixing the MWO microparticle dispersion. Stirring and mixing suppresses aggregation of the MWO microparticles and maintains a monodispersed state. This suppresses the formation of a coating film on the surface of MWO microparticle aggregates and allows hydrolysis products or polymers to adhere uniformly and firmly to the surface of each individual MWO microparticle. As a result, the formation of coarse particles that reduce transparency is suppressed, and a dense, high-density coating film can be formed.

[0065] The amount of metal chelate compound or metal cyclic oligomer compound added is preferably 0.05 to 300 parts by weight, and more preferably 0.3 to 150 parts by weight, in terms of metal element relative to 100 parts by weight of MWO microparticles. Adding an amount of 0.1 parts by weight or more improves the chemical stability of the MWO microparticles through the coating film. Adding an amount of 300 parts by weight or less prevents excessive adhesion of hydrolysis products or their polymers to the MWO microparticles. Furthermore, the improvement in moist heat resistance achieved by the surface treatment does not saturate, and the coating effect can be improved. Furthermore, excessive coating of the MWO microparticles with hydrolysis products or polymers can prevent the MWO microparticles from easily granulating with each other through hydrolysis products or the like during medium removal. As a result, the decrease in transparency due to granulation is suppressed, ensuring good transparency. Furthermore, increased production costs due to increased addition amounts and processing times caused by excess metal chelate compound or metal cyclic oligomer compound can be avoided.

[0066] In a MWO microparticle dispersion system using water as the liquid medium, metal chelate compounds, metal cyclic oligomer compounds, their hydrolysis products, and polymers of the hydrolysis products may be decomposed into metal ions immediately after the addition of the surface treatment agent is started, but the decomposition into metal ions stops when the solution becomes saturated.

[0067] Furthermore, when water is used as the liquid medium for the MWO microparticle dispersion, the hydrolysis of metal chelate compounds and metal cyclic oligomer compounds can be carried out more quickly when a surface treatment agent is added, compared to when an organic solvent is used. Therefore, after the hydrolysis reaction of the metal chelate compounds and the like is completed, the polymerization reaction of the generated hydrolysis product can be carried out. This prevents the metal chelate compounds and the like from being incompletely hydrolyzed and being incorporated into the coating film, thereby reducing the amount of carbon contamination originating from unreacted metal chelate compounds and the like. By reducing the amount of carbon contamination, a high-density coating film can be formed.

[0068] Furthermore, the concentration of carbon originating from the unreacted surface treatment agent present in the coating film is not particularly limited, but from the viewpoint of forming a high-density coating film, it is preferably 0.2 mass % or more and 5.0 mass % or less, and more preferably 0.5 mass % or more and 3.0 mass % or less.

[0069] On the other hand, when the MWO microparticle dispersion contains an organic solvent as the liquid medium, the surface treatment agent and pure water can be added dropwise in parallel while the MWO microparticle dispersion is being mixed and stirred. It is preferable to appropriately control the medium temperature, which affects the reaction rate, and the drop rates of the surface treatment agent and pure water. By using an organic solvent as the liquid medium, the amount of water contained in the MWO microparticle dispersion can be reduced.

[0070] <4-3> Treatment process after preparation of dispersion for forming coating film The dispersion containing the surface-treated MWO fine particles obtained by preparing the dispersion for forming a coating film may be used as is in the coating step with a metal coupling agent described below, or may be heat-treated.

[0071] The surface-treated MWO particles can be used as is without further heat treatment to increase the density or chemical stability of the coating film, because the addition of a silicon compound (described below) can enhance heat resistance.

[0072] On the other hand, the dispersion containing the surface-treated MWO microparticles may be heat-treated for the purposes of obtaining the surface-treated MWO microparticles from the dispersion, drying the surface-treated MWO microparticle powder, etc. When heat-treating, care must be taken to ensure that the heat-treating temperature does not exceed the temperature at which the surface-treated MWO microparticles strongly aggregate to form strong aggregates.

[0073] This is because the final composite surface-treated MWO microparticles are often required to be transparent due to the intended use of the laminated structure. The presence of these aggregates results in a high degree of haze when the laminated structure is produced. If heat treatment is performed at a temperature exceeding the temperature at which strong aggregates are formed, the strong aggregates must be disintegrated and redispersed by dry or / and wet methods to ensure the transparency of the infrared-absorbing microparticle dispersion or infrared-absorbing substrate. However, during this disintegration and redispersion, the coating film on the surface of the surface-treated MWO microparticles may be damaged, and in some cases, some of the coating film may peel off, exposing the surface of the microparticles.

[0074] As explained above, the surface-treated MWO microparticles do not require heat treatment after mixing and stirring, so they do not undergo strong aggregation, and therefore dispersion treatment to break down strong aggregations is unnecessary or can be performed in a short time. As a result, the coating film on the surface-treated MWO microparticles of this embodiment remains intact, coating each individual MWO microparticle.

[0075] <4-4> Coating process with metal coupling agent Next, the surface-treated MWO particles having the coating film formed on the surface thereof are subjected to a surface treatment using a metal coupling agent as a surface treatment agent.

[0076] Specifically, first, surface-treated MWO particles with a coating film on their surface are mixed with a liquid medium and a metal coupling agent, and then the mixture is dispersed and crushed. This causes the metal coupling agent to adhere to the coating film present on the surface of the MWO particles. This results in a dispersion containing composite surface-treated MWO particles with a coating film to which the metal coupling agent adheres.

[0077] The resulting dispersion may be used as is, but if necessary, the liquid medium may be evaporated by the drying method described above to form a dispersion powder containing composite surface-treated MWO fine particles.

[0078] The amount of metal coupling agent added is not particularly limited. Preferably, the amount of metal coupling agent added is adjusted appropriately so that the content of the metal coupling agent in the composite surface-treated MWO fine particles is 0.01% by mass or more and 0.50% by mass or less. This improves the chemical stability of the composite surface-treated MWO fine particles while maintaining high transparency in the interlayer film.

[0079] The liquid medium used in the metal coupling agent coating process preferably has a low boiling point and is easily volatilized, from the viewpoint of drying the liquid medium to obtain composite surface-treated MWO microparticles. Specifically, organic solvents with a boiling point of 120°C or less are preferred. By using an easily volatilized organic solvent, the drying time can be shortened, improving the productivity of the composite surface-treated MWO microparticles. Furthermore, the residual organic solvent in the dispersed powder obtained after drying can be reduced. As a result, the generation of bubbles in the interlayer film can be reduced during the production of the interlayer film described below.

[0080] Specifically, toluene, methyl ethyl ketone, methyl isobutyl ketone, butyl acetate, isopropyl alcohol, ethanol, etc. can be suitably used as the liquid medium.

[0081] In this manner, composite surface-treated MWO particles can be obtained.

[0082] <5> Interlayer film composition Next, the interlayer film composition for forming the interlayer film will be described.

[0083] The interlayer film composition of this embodiment contains at least the above-described composite surface-treated MWO particles and an ionomer resin, and optionally contains other additives. The interlayer film composition is obtained by mixing and kneading the composite surface-treated MWO particles, the ionomer resin, and optionally other additives. The ionomer resin and other additives are described below.

[0084] <5-1> Ionomer resin Ionomer resins serve as the base polymer for interlayer film compositions. Ionomer resins can provide high adhesion to transparent substrates. Therefore, when an interlayer film is interposed between transparent substrates in a laminated structure, the adhesion between the interlayer film and the transparent substrates can be improved.

[0085] The ionomer resin is not particularly limited, and various known ionomer resins can be used, and the resin can be selected as desired depending on the intended use of the interlayer film, etc. Known ionomer resins include, for example, ethylene-based ionomers, styrene-based ionomers, ionomer elastomers, perfluorocarbon ionomers, and urethane ionomers. As described above, any ionomer resin can be selected and used depending on the intended use, required performance, etc. From the viewpoint of adhesion to the transparent substrate, it is more preferable that the ionomer resin contains an ethylene-based ionomer, and it is even more preferable that the ionomer resin be an ethylene-based ionomer. The interlayer film composition can contain only one type of ionomer resin, or two or more types of ionomer resins can be used in combination.

[0086] The metal ions contained in the ionomer resin are not particularly limited, and for example, an ionomer resin containing one or more metal ions selected from zinc, magnesium, lithium, potassium, and sodium can be used. In particular, an ionomer resin containing zinc ions can be preferably used.

[0087] Specific examples of ionomer resins include metal element ionomers of ethylene-acrylic acid-acrylic acid ester copolymers, metal element ionomers of ethylene-acrylic acid-methacrylic acid ester copolymers, metal element ionomers of ethylene-methacrylic acid-acrylic acid ester copolymers, metal element ionomers of ethylene-methacrylic acid-methacrylic acid ester copolymers, etc. Note that the metal ions contained in any of the ionomer resins are not particularly limited, and may contain ions of one or more metals selected from, for example, zinc, magnesium, lithium, potassium, and sodium.

[0088] More specifically, examples of ionomer resins that can be preferably used include the Surlyn (registered trademark) series from DuPont, the Hi-Milan (registered trademark) series from Mitsui-DuPont Polychemicals, and the IOTEK (registered trademark) series from ExxonMobil Chemical.

[0089] <5-2> Other additives In addition to the components described above, the interlayer film composition may contain other additives as needed. These other additives will be described below.

[0090] (Metal Coupling Agent) In addition to the surface treatment of the MWO fine particles, a metal coupling agent may be added and dispersed in the interlayer film composition. The metal coupling agents described above can be used. The amount of the metal coupling agent added can be adjusted appropriately within a range that does not impair the chemical stability or optical properties of the interlayer film.

[0091] (dispersant) In order to suppress aggregation of the composite surface-treated MWO microparticles during the interlayer film production process and maintain their dispersibility, the interlayer film composition may contain a dispersant. The dispersant is not particularly limited and can be selected as desired depending on the interlayer film production conditions, etc. For example, a dispersant having a thermal decomposition temperature of 250°C or higher as measured using a differential thermal analyzer (TG-DTA) and having a main chain selected from a urethane main chain, an acrylic main chain, and a styrene main chain, or a main chain in which two or more unit structures selected from urethane, acrylic, and styrene are copolymerized, is preferred. Here, the thermal decomposition temperature is the temperature at which weight loss due to thermal decomposition of the dispersant begins when measured using a TG-DTA in accordance with JIS K7120.

[0092] When the thermal decomposition temperature of the dispersant is 250°C or higher, the decomposition of the dispersant during kneading with the ionomer resin can be suppressed, and problems such as browning of the interlayer film and a decrease in visible light transmittance caused by the decomposition of the dispersant can be suppressed, making it possible to more reliably avoid situations in which the original optical properties cannot be obtained.

[0093] The dispersant preferably has one or more functional groups selected from an amine-containing group, a hydroxyl group, a carboxyl group, or an epoxy group. Dispersants having any of the above functional groups are preferably used because they adsorb to the surface of the composite surface-treated MWO microparticles, prevent the microparticles from aggregating, and allow the surface-treated composite tungsten oxide microparticles to be more uniformly dispersed in the interlayer film.

[0094] Specific examples of dispersants having any of the above functional groups include acrylic-styrene copolymer dispersants having a carboxyl group as the functional group, and acrylic dispersants having an amine-containing group as the functional group. Dispersants having an amine-containing group as the functional group preferably have a molecular weight Mw of 2,000 to 200,000 and an amine value of 5 to 100 mgKOH / g. Furthermore, dispersants having a carboxyl group preferably have a molecular weight Mw of 2,000 to 200,000 and an acid value of 1 to 50 mgKOH / g.

[0095] The amount of dispersant added is not particularly limited, but it is preferable to add 10 to 1,000 parts by mass of dispersant per 100 parts by mass of composite surface-treated MWO microparticles, and it is more preferable to add 30 to 400 parts by mass of dispersant.

[0096] (ultraviolet absorber) An ultraviolet absorber may be added to the interlayer film composition. By including the composite surface-treated MWO fine particles, the interlayer film can mainly block light in the infrared region, but by further including an ultraviolet absorber, it can also block light in the ultraviolet region. This can suppress temperature increases in the region inside the interlayer film and reduce the effects of ultraviolet light.

[0097] Furthermore, when a metal coupling agent is added to the interlayer film composition, the effect of suppressing photodiscoloration by the metal coupling agent and the effect of suppressing photodiscoloration by the ultraviolet absorber can be obtained synergistically, making it possible to further suppress photodiscoloration.

[0098] The ultraviolet absorber is not particularly limited and can be selected as desired depending on the effect it has on the visible light transmittance of the interlayer film, its ultraviolet absorption ability, durability, etc. Examples of ultraviolet absorbers include organic ultraviolet absorbers such as benzophenone compounds, salicylic acid compounds, benzotriazole compounds, triazine compounds, benzotriazolyl compounds, and benzoyl compounds, and inorganic ultraviolet absorbers such as zinc oxide, titanium oxide, and cerium oxide. In particular, it is preferable that the ultraviolet absorber contains one or more compounds selected from benzotriazole compounds and benzophenone compounds. This is because benzotriazole compounds and benzophenone compounds can increase the visible light transmittance of the interlayer film even when added in a concentration sufficient to sufficiently absorb ultraviolet light, and they are highly durable against long-term exposure to strong ultraviolet light.

[0099] Furthermore, it is more preferable that the ultraviolet absorber contains, for example, a compound represented by the following chemical formula 1 and / or chemical formula 2.

[0100] [ka]

[0101] [ka]

[0102] The amount of ultraviolet absorber added is not particularly limited and can be selected as desired depending on the visible light transmittance, ultraviolet shielding ability, and other factors required for the laminated structure. The amount of ultraviolet absorber added is preferably, for example, 0.02% by mass or more and 5.0% by mass or less. This is because a content of ultraviolet absorber of 0.02% by mass or more ensures sufficient absorption of ultraviolet light. Furthermore, a content of 5.0% by mass or less prevents the ultraviolet absorber from precipitating in the interlayer film and does not significantly affect the strength, adhesive strength, or penetration resistance of the film.

[0103] (light stabilizer) A light stabilizer may be added to the interlayer film composition together with the above-mentioned UV absorber. When the interlayer film is used for a long period of time, the UV absorber may deteriorate, resulting in a decrease in its UV absorption ability. In this regard, by further adding a light stabilizer, it is possible to suppress the deterioration of the UV absorber and maintain the effect of the UV absorber at a high level for a long period of time. As such a light stabilizer, a hindered amine light stabilizer (HALS) can be used.

[0104] The HALS is not particularly limited and can be arbitrarily selected depending on the effect on the visible light transmittance of the interlayer film, compatibility with the ultraviolet absorber, durability, etc. Examples include bis(2,2,6,6-tetramethyl-4-piperidyl)sebacate, bis(1,2,2,6,6-pentamethyl-4-piperidyl)sebacade, 1-[2-[3-(3,5-t-butyl-4-hydroxyphenyl)propionyloxy]ethyl]-4-[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionyloxy]-2,2,6,6-tetramethylpiperidine, 4-benzoyloxy-2,2,6,6-tetramethylpiperidine, 8-acetyl-3-dodecyl-7,7, 9,9-Tetramethyl-1,3,8-triazaspiro[4,5]decane-2,4-dione, 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, tetrakis(2,2,6,6-tetramethyl-4-piperidyl)-1,2,3,4-butanetetracarboxylate, (Mixed 1 ,2,2,6,6-Pentamethyl-4-piperidyl / tridecyl)-1,2,3,4-butanetetracarboxylate, Mixed{1,2,2,6,6-Pentamethyl-4-piperidyl / β,β,β',β'-tetramethyl-3,9-[2,4,8,10-tetraoxaspiro(5,5)undecane]diethyl}-1,2,3,4-butanetetracarboxylate, (Mixed2,2,6,6-Tetramethyl-4-piperidyl / tridecyl)-1,2,3,4-butanetetracarboxylate, Mi xed{2,2,6,6-tetramethyl-4-piperidyl / β,β,β',β'-tetramethyl-3,9-[2,4,8,10-tetraoxaspiro(5,5)undecane]diethyl}-1,2,3,4-butanetetracarboxylate, 2,2,6,6-tetramethyl-4-piperidyl methacrylate, 1,2,2,6,6-pentamethyl-4-piperidyl methacrylate, poly[(6-(1,1,3,3-tetramethylbutyl)imino-1,3,5-triazine-2,4-diyl)][(2,2,6,6-tetramethyl-4-piperidyl)imino]hexamethylene [(2,2,6,6-tetramethyl-4-piperidyl)iminol], dimethyl succinate polymer with-4-hydroxy-2,2,6,6-tetramethyl-1-piperidineethanol (polymerization of dimethyl succinate and 4-hydroxy-2,2,6,6-tetramethyl-1-piperidineethanol), N,N',N'',N'''-tetrakis-(4,6-bis-(butyl-(N-methyl-2,2,6,6-tetramethyl)-2-methyl-1-piperidine) Suitable examples include (methylpiperidin-4-yl)amino)-triazin-2-yl)-4,7-diazadecane-1,10-diamine, a polycondensate of dibutylamine-1,3,5-triazine-N,N'-bis(2,2,6,6-tetramethyl-4-piperidyl-1,6-hexamethylenediamine and N-(2,2,6,6-tetramethylpiperidyl)butylamine, and decanedioic acid bis(2,2,6,6-tetramethyl-1-(octyloxy)-4-piperidinyl)ester.

[0105] The amount of HALS added is not particularly limited and can be selected as desired depending on the visible light transmittance, weather resistance, and other properties required of the interlayer film. The amount of HALS added is preferably, for example, 0.05% by mass or more and 5.0% by mass or less. This is because a HALS content of 0.05% by mass or more allows the effects of adding HALS to be exerted in the interlayer film. Furthermore, a content of 5.0% by mass or less prevents HALS from precipitating in the interlayer film and does not affect the strength, adhesive strength, or penetration resistance of the film.

[0106] (antioxidant) An antioxidant may be added to the interlayer film composition to suppress oxidative degradation of the resin and improve its weather resistance. The antioxidant can suppress oxidative degradation not only of the resin but also of other additives contained in the interlayer film, such as the composite surface-treated MWO fine particles, metal coupling agents, and UV absorbers, thereby improving weather resistance.

[0107] The antioxidant is not particularly limited and can be selected as desired depending on the effect on the visible light transmittance of the interlayer film, the desired durability, etc. For example, phenol-based antioxidants, sulfur-based antioxidants, phosphorus-based antioxidants, etc. can be suitably used. More specifically, 2,6-di-t-butyl-p-cresol, butylated hydroxyanisole, 2,6-di-t-butyl-4-ethylphenol, stearyl-β-(3,5-di-t-butyl-4-hydroxyphenyl)propionate, 2,2'-methylenebis-(4-methyl-6-butylphenol), 2,2'-methylenebis-(4-ethyl-6-t-butylphenol), 4,4'-butylidene-bis-(3-methyl ... 1,3,3-tris-(2-methyl-4-hydroxy-5-t-butylphenol)butane, 1,3,5-trimethyl-2,4,6-tris(3,5-di-t-butyl-4-hydroxybenzyl)benzene, bis(3,3'-t-butylphenol)butyric acid glycol ester, and the like can be suitably used.

[0108] The amount of antioxidant added is not particularly limited and can be selected as desired depending on the visible light transmittance, weather resistance, and other properties required of the interlayer film. The amount of antioxidant added is preferably 0.05% by mass or more and 5.0% by mass or less. This is because an amount of antioxidant added of 0.05% by mass or more allows the antioxidant's effects to be exerted in the interlayer film. Furthermore, an amount of antioxidant added of 5.0% by mass or less prevents the antioxidant from precipitating in the interlayer film and does not significantly affect the strength, adhesive strength, or penetration resistance of the film.

[0109] (plasticizer) In order to improve the adhesion of the interlayer film to the transparent substrate, a plasticizer may be added to the interlayer film composition. As the plasticizer, it is preferable to use one that is generally used for the ionomer resin that constitutes the interlayer film.

[0110] (dye) If desired, the interlayer film composition may contain dye compounds or pigment compounds that are generally used to color resins, such as azo dyes, cyanine dyes, quinoline dyes, perylene dyes, and carbon black, in order to impart any desired color tone.

[0111] (infrared absorbing material) To further improve the infrared shielding ability, an infrared-absorbing substance may be added to the interlayer film composition in addition to the composite surface-treated MWO particles. The other infrared-absorbing substance is not particularly limited, but is preferably a substance that can absorb light in a wavelength range different from that of the composite surface-treated MWO particles used. For example, an infrared-absorbing organic compound can be suitably used. Adding an infrared-absorbing organic compound can achieve even higher infrared shielding ability.

[0112] (Adhesion adjuster) An adhesion modifier may be added to the interlayer film composition to adjust the adhesive strength between the interlayer film and the transparent substrate. The adhesion modifier is not particularly limited, but alkali metal salts and / or alkaline earth metal salts can be suitably used. The acid constituting the alkali metal salt and / or alkaline earth metal salt is not particularly limited, but examples include carboxylic acids such as octylic acid, hexylic acid, butyric acid, acetic acid, and formic acid, and inorganic acids such as hydrochloric acid and nitric acid. Among the alkali metal salts and / or alkaline earth metal salts, magnesium salts of carboxylic acids having 2 to 16 carbon atoms and potassium salts of carboxylic acids having 2 to 16 carbon atoms are preferred.

[0113] The magnesium and potassium carboxylates of organic acids having 2 to 16 carbon atoms are not particularly limited, but examples thereof include magnesium acetate, potassium acetate, magnesium 2-ethylbutyrate, magnesium propionate, potassium propionate, magnesium 2-ethylbutanoate, potassium 2-ethylbutanoate, magnesium 2-ethylhexanoate, and potassium 2-ethylhexanoate. Among these, magnesium 2-ethylbutyrate is preferred due to its high performance as an adhesion modifier. Only one type of adhesion modifier may be added, or two or more types may be added.

[0114] (others) In addition to the above-mentioned additives, surfactants, antistatic agents, etc. may also be added to the interlayer film composition.

[0115] <6> Interlayer The interlayer film is formed from the interlayer film composition described above, and contains composite surface-treated MWO fine particles, an ionomer resin, and, if necessary, other additives.

[0116] The content of the composite surface-treated MWO microparticles in the interlayer film may be appropriately changed depending on the transparency and heat-shielding performance required of the interlayer film. For example, when the laminated structure is used as a window material or the like, a high visible light transmittance is preferable from the viewpoint of maintaining light transmission to the human eye, and a low solar radiation transmittance and photocoloration are preferable from the viewpoint of reducing the incidence of heat due to sunlight. Furthermore, when the laminated structure is used as an agricultural sheet, a high visible light transmittance is preferable from the viewpoint of maintaining the transmittance of visible light necessary for plant growth, and a low solar radiation transmittance is preferable from the viewpoint of reducing the incidence of heat due to sunlight.

[0117] The interlayer film can be produced by molding the above-mentioned interlayer film composition. Here, as an example, a case will be described in which a dispersion containing composite surface-treated MWO fine particles is prepared, this dispersion powder is mixed with an ionomer resin to prepare an interlayer film composition, and then this is molded to produce an interlayer film.

[0118] (Dispersion powder preparation process) First, a dispersed powder containing composite surface-treated MWO particles is prepared.

[0119] Specifically, the dispersant is added to a dispersion containing composite surface-treated MWO microparticles and a liquid medium, and then mixed. If necessary, other additives, such as a metal coupling agent, may be added. The resulting mixture is then subjected to a dispersion and pulverization process to prepare a dispersion containing composite surface-treated MWO microparticles and the dispersant. The liquid medium is then removed from the dispersion, yielding a dispersed powder containing composite surface-treated MWO microparticles and the dispersant. In the dispersed powder, some or all of the dispersant is in contact with the composite surface-treated MWO microparticles.

[0120] The liquid medium used to prepare the dispersion containing the composite surface-treated MWO particles is preferably the organic solvent used in the coating step with the metal coupling agent described above. The dispersion and pulverization treatments may be carried out by the methods described above.

[0121] (Kneading process) The resulting dispersed powder is then mixed with an ionomer resin. If necessary, other additives such as an ultraviolet absorber, HALS, an antioxidant, or an infrared absorbing substance may be added. The resulting mixture is kneaded by a known kneading method to obtain an interlayer film composition containing the composite surface-treated MWO microparticles.

[0122] Other additives such as an ultraviolet absorber may be added when preparing the dispersion liquid described above, or may be added in other steps.

[0123] (molding process) The interlayer film composition thus obtained is then molded to produce an interlayer film. The molding method is not particularly limited, and may be appropriately selected from conventionally known methods depending on the size and shape of the interlayer film, such as its thickness, or the viscosity of the interlayer film composition. For example, extrusion molding or calendar molding may be used.

[0124] The shape of the interlayer is not particularly limited and can be changed appropriately depending on the shape required for the laminated structure. For example, the shape can be a film.

[0125] <7> Laminated structure Next, the laminated structure of this embodiment will be described.

[0126] The laminated structure of this embodiment is configured to include a plurality of transparent substrates and at least one intermediate film interposed between the plurality of transparent substrates.

[0127] The transparent substrate is a member that sandwiches the interlayer film from both sides and has transparency in the visible light region. Examples of the transparent substrate that can be used include glass substrates and resin substrates. The multiple transparent substrates that make up the laminated structure may all be substrates made of the same material, or substrates made of different materials may be combined, for example, a glass substrate and a resin substrate may be combined.

[0128] The resin substrate is appropriately selected depending on the application of the laminated structure. For example, when used in transportation equipment such as automobiles, transparent resins such as polycarbonate resin, acrylic resin, polyester resin, and polyethylene terephthalate resin are preferred from the viewpoint of ensuring transparency for drivers and passengers of the transportation equipment.

[0129] The laminated structure including the intermediate film can be produced, for example, as follows.

[0130] First, an additive solution containing composite surface-treated MWO particles dispersed in a plasticizer is added to an ionomer resin to prepare an interlayer film composition, which is then formed into a sheet to produce an interlayer film. Next, this interlayer film is sandwiched between two laminated sheets of glass or plastic and bonded together to produce a laminated structure.

[0131] Although the example described here is one in which composite surface-treated MWO microparticles are dispersed in a plasticizer, the interlayer film composition may also be prepared by adding a dispersion of composite surface-treated MWO microparticles in an appropriate solvent that is not a plasticizer to an ionomer resin, with the plasticizer being added separately.

[0132] This makes it possible to manufacture a laminated structure having high infrared shielding properties and a small haze value. Furthermore, this method allows for easy manufacturing of a laminated structure, and enables the manufacture of a laminated structure at low production costs.

[0133] Although the above description has been given of a case where a single interlayer film is disposed between transparent substrates, a multilayer film composed of an interlayer film and other films may be formed and then disposed between the transparent substrates. For example, an interlayer film containing composite surface-treated MWO particles may be laminated with a different resin film, and these may be sandwiched between transparent substrates to form a laminated structure. Alternatively, an interlayer film may be sandwiched between resin films, and this laminate may be interposed between transparent substrates to form a laminated structure. The resin film may be an infrared-absorbing layer containing surface-treated MWO particles.

[0134] Specifically, an additive liquid in which the composite surface-treated MWO microparticles are dispersed in a plasticizer is added to an ionomer resin to prepare an interlayer film composition, and this interlayer film composition is formed into a sheet to produce an interlayer film. This interlayer film may be laminated with, for example, another resin film that does not contain the composite surface-treated MWO microparticles, or may be interposed between two resin films that do not contain the composite surface-treated MWO microparticles, and these laminates may be sandwiched between and bonded to two transparent substrates to produce a laminated structure. Instead of dispersing the composite surface-treated MWO particles in a plasticizer, the resin composition may be prepared by adding a dispersion of the particles dispersed in a suitable solvent to an ionomer resin, and then adding the plasticizer separately. This allows for the production of a laminated structure with high infrared shielding properties and a small haze value at low production costs. This method is preferable because it can increase the adhesion between the resin film that does not contain composite surface-treated MWO microparticles and the transparent substrate, thereby appropriately increasing the strength of the laminated structure.

[0135] The laminated structure can be produced by sandwiching the above-mentioned interlayer film between multiple transparent substrates and then laminating them together using a known method. For example, the above-mentioned interlayer film may be sandwiched between two transparent substrates selected from glass substrates or resin substrates, and then laminated together. For example, when there are three or more transparent substrates, an interlayer film may be sandwiched between each of the transparent substrates, and then laminated together. For example, when there are three or more transparent substrates, an interlayer film may be sandwiched between at least one of the transparent substrates, and another resin film may be sandwiched between the remaining transparent substrates, and then laminated together.

[0136] <Effects of this embodiment> According to this embodiment, one or more of the following effects are achieved.

[0137] (a) The laminated structure of this embodiment includes an interlayer film between at least one of a plurality of transparent substrates. This interlayer film contains composite surface-treated MWO particles and an ionomer resin. The composite surface-treated MWO particles are formed by coating the surface of the MWO particles with a metal coupling agent. The surface of the MWO particles is provided with a coating film containing at least one selected from the group consisting of hydrolysis products of metal chelate compounds, polymers of hydrolysis products of metal chelate compounds, hydrolysis products of cyclic metal oligomer compounds, and polymers of hydrolysis products of cyclic metal oligomer compounds. By coating the surface of a coating film formed using a metal chelate compound or the like with a metal coupling agent, the coating film can be formed with a uniform thickness and strength. For example, when the interlayer film is irradiated with ultraviolet light, the resin component decomposes, generating hydrogen radicals. The metal coupling agent can take over the valence change of the MWO particles caused by the hydrogen radicals. Furthermore, the hydrolysis products of the metal chelate compound and the cyclic metal oligomer compound prevent moisture that has penetrated the interlayer film from coming into contact with the MWO particles, thereby suppressing decomposition of the MWO particles. This suppresses fluctuations in the valence and light transmittance of the MWO particles. These composite surface-treated MWO particles have excellent chemical stability and maintain high weather resistance over a long period of time, thereby suppressing the photocoloration of the interlayer film.

[0138] Specifically, the interlayer film was heated to 100 mW / cm 2 with a metal halide lamp as the light source in an environment with a temperature of 60°C and a relative humidity of 35%. 2 When irradiated with ultraviolet light, the color difference ΔE before and after irradiation can be suppressed to 1.5 or less, and photocoloration caused by long-term ultraviolet irradiation can be suppressed.

[0139] (b) Furthermore, by including composite surface-treated MWO microparticles, the interlayer film can reduce solar transmittance while maintaining a high visible light transmittance. Specifically, when composite surface-treated MWO microparticles are added to the interlayer film so that the visible light transmittance is 85%, the transmittance (solar transmittance) for light in the range of 300 nm to 2100 nm can be reduced to 70% or less, achieving high infrared absorption properties.

[0140] (c) The metal chelate compound or metal cyclic oligomer compound preferably contains at least one metal element selected from the group consisting of Al, Zr, Ti, Si, and Zn. Using such a compound allows the coating film to be formed from a hydrolysis product or polymer containing these metal elements. This improves the chemical stability of the composite surface-treated MWO microparticles and further suppresses photocoloration in the interlayer film.

[0141] (d) The thickness of the coating film is preferably 0.5 nm or more and 100 nm or less. By setting the thickness to such a value, the weather resistance of the composite surface-treated MWO fine particles can be further improved.

[0142] (e) The metal coupling agent is preferably a silane coupling agent. The silane coupling agent allows the coating film to be formed at a higher density and more firmly on the surface of the MWO fine particles. This improves the weather resistance of the composite surface-treated MWO fine particles and further suppresses photocoloration in the interlayer film.

[0143] (f) The content of the metal coupling agent in the composite surface-treated MWO fine particles is preferably 20 parts by mass or more per 100 parts by mass of the MWO fine particles, which can further improve the weather resistance of the composite surface-treated MWO fine particles.

[0144] (g) MWO particles are of the general formula M x W y O z(wherein M is one or more elements selected from Cs, K, Rb, In, Tl, Ba, Li, Ca, Sr, Fe, and Sn; W is tungsten; O is oxygen; and 0.001≦x / y≦1, 2.0≦z / y<4.0) and preferably have a hexagonal crystal structure. MWO particles having such a composition and crystal structure can more reliably achieve the effect (b) described above.

[0145] (h) The ionomer resin is preferably an ethylene-based ionomer, which can improve the adhesion of the interlayer film to the transparent substrate.

[0146] (i) The interlayer film preferably contains a metal coupling agent. Adding a metal coupling agent to the composite surface-treated MWO fine particles can further improve the weather resistance of the interlayer film. This significantly reduces the occurrence of photocoloration, even when the laminated structure is exposed to strong ultraviolet light for a long period of time. Furthermore, high transmittance of light in the visible range can be maintained, preventing the interlayer film from losing its appearance or transparency.

[0147] Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments and can be modified in various ways without departing from the spirit of the present invention. [Example]

[0148] The present invention will be described below in more detail with reference to examples, but the present invention is not limited to these examples.

[0149] In this example, composite surface-treated composite tungsten oxide particles were obtained by surface treatment, and then laminated structures were fabricated using these particles and evaluated. Specific examples are described below.

[0150] Example 1 (1) Preparation of composite surface-treated tungsten oxide particles (Preparation of fine particle dispersion) First, as composite tungsten oxide particles, Cs was used, which is 0.33 moles of Cs and 3 moles of O per mole of W. 0.33 WO3 fine particles ("YM-01" manufactured by Sumitomo Metal Mining Co., Ltd.) were prepared.

[0151] Next, Cs 0.33 28 parts by mass of WO3 fine particles and 72 parts by mass of pure water were mixed, and the resulting mixture was placed in a paint shaker containing φ0.3 mm ZrO2 beads and subjected to a pulverization and dispersion treatment for 4 hours.

[0152] In addition, Cs dispersed in the mixed liquid 0.33 The dispersed particle diameter of the WO3 microparticles was measured using a particle size measuring device based on the dynamic light scattering method (Otsuka Electronics Co., Ltd.'s "ELS-8000") and was found to be 140 nm. The particle size measurement settings were a particle refractive index of 1.81 and a non-spherical particle shape. The background was measured using pure water, and the solvent refractive index was set to 1.33. After removing the solvent from the mixture, Cs 0.33 When the WO3 microparticles were measured by powder X-ray diffraction (θ-2θ method) using a powder X-ray diffraction measuring device (X'Pert-PRO / MPD manufactured by PANalytical, Spectris Co., Ltd.), the crystal system was found to be hexagonal and the crystallite diameter was 28 nm.

[0153] Next, pure water was added to the mixture, and Cs 0.33 A particle dispersion liquid with a WO3 particle concentration of 14 mass % was prepared.

[0154] (Preparation of dispersion for forming coating film) Cs 0.33 Prior to the surface treatment of the WO3 microparticles, a surface treatment solution for forming a coating film was prepared. The preparation conditions for the surface treatment solution are summarized in Table 1 below. Specifically, surface treatment solution a was prepared by mixing 29.0 parts by mass of aluminum ethyl acetoacetate diisopropylate, an aluminum-based metal chelate compound, with 71.0 parts by mass of isopropyl alcohol (IPA).

[0155] [Table 1]

[0156] Next, 550 g of the fine particle dispersion prepared above was placed in a beaker, and while stirring with a stirrer, 307 g of surface treatment solution A was added dropwise over 6 hours to prepare a dispersion for forming a coating film. After the dropwise addition of surface treatment solution A, this dispersion for forming a coating film was further stirred at a temperature of 20°C for 24 hours to obtain a matured solution. Next, the liquid medium was evaporated from the matured solution by vacuum fluidized drying, and Cs 0.33 Surface-treated Cs with a coating film formed on the surface of WO3 particles 0.33 WO3 fine particles were obtained.

[0157] (Coating with metal coupling agent) Next, surface treatment Cs 0.33 A mixture of 10 parts by weight of WO3 microparticles, 10 parts by weight of dispersant, 2.0 parts by weight of 3-(2-aminoethyl)aminopropyltrimethoxysilane as a metal coupling agent, and 78.0 parts by weight of butyl acetate as an organic solvent was used. The resulting mixture was loaded into a paint shaker containing 0.3 mm diameter ZrO2 beads and ground and dispersed for 1 hour. The dispersant used had an amine-containing functional group and an acrylic backbone, an amine value of 48 mg KOH / g, and a decomposition temperature of 250°C.

[0158] Next, the pulverized and dispersed mixture is introduced into a vacuum fluidized bed dryer, and the medium is evaporated to obtain the surface-treated Cs. 0.33 A metal coupling agent was applied to the coating film of the WO3 particles, and the coating film was further coated with the metal coupling agent. 0.33 A dispersed powder containing composite surface-treated CWO particles in which WO3 particles were coated with a metal coupling agent was obtained. Surface-treated Cs contained in the obtained dispersed powder 0.33 In WO3 particles, Cs 0.33The content of the metal chelate compound was 42.9 parts by mass, calculated as metal elements, and the content of the metal coupling agent was 28.6 parts by mass, per 100 parts by mass of WO3 microparticles. The content of the metal chelate compound was measured by ICP emission spectroscopy of aluminum, and the content of the metal coupling agent was measured by ICP emission spectroscopy of silicon.

[0159] In addition, the composite surface treatment Cs contained in the above mixture 0.33 The WO3 particles were observed under a transmission electron microscope after removing the solvent, and the volume average particle diameter was measured to be 28 nm. The thickness of the coating film was 2 nm. 0.33 The volume-average particle size of the WO3 microparticles was calculated by measuring the particle sizes of 100 microparticles from an image observed under a transmission electron microscope (HF-2200, manufactured by Hitachi, Ltd.) The thickness of the coating film was determined by determining the area of the composite tungsten oxide microparticles without lattice fringes from an image observed under a transmission electron microscope at 300,000 magnification as the coating film.

[0160] Composite Surface Treatment Cs 0.33 The conditions for producing WO3 microparticles are summarized in Table 2 below.

[0161] [Table 2]

[0162] (2) Preparation of interlayer film composition Next, a composition for forming an interlayer film was prepared using the dispersed powder. Specifically, 0.8 parts by mass of the dispersed powder was mixed with 99.2 parts by mass of an ionomer resin to prepare the interlayer film composition of Example 1. The ionomer resin used was a pellet-shaped ethylene-based ionomer containing zinc as a metal ion ("Himilan 1706" manufactured by DuPont-Mitsui Polychemicals Co., Ltd.).

[0163] (3) Preparation of interlayer and laminated structure Next, the interlayer film composition of Example 1 was fed into a twin-screw extruder set at 200°C and kneaded, and then extruded through a T-die and formed into a 2.3 mm thick sheet using a calendar roll method to produce the interlayer film of Example 1.

[0164] In the interlayer film of Example 1, Cs 0.33 The content of WO3 particles was 0.21 mass%, and Cs 0.33 The content of WO3 fine particles is a value measured by ICP emission spectroscopic analysis of tungsten.

[0165] In addition, the interlayer film of Example 1 was temporarily sandwiched between two sheets of transparent float glass (3 mm thick), heated to 130°C, and pressed under vacuum for 3 minutes to produce the laminated structure of Example 1.

[0166] Example 2 In Example 2, as shown in Table 2, in the coating with the metal coupling agent of Example 1, the amount of the metal coupling agent 3-(2-aminoethyl)aminopropyltrimethoxysilane added was changed from 2.0 parts by mass to 2.5 parts by mass, except that the surface treatment was carried out in the same manner as in Example 1, and an intermediate film and a laminated structure were produced.

[0167] In the interlayer film of Example 2, Cs 0.33 The content of WO3 fine particles was 0.21 mass%. 0.33 The content of the metal chelate compound was 42.9 parts by mass in terms of metal element, the content of the metal coupling agent was 33.3 parts by mass, and the thickness of the coating film was 2 nm, relative to 100 parts by mass of WO3 microparticles.

[0168] Example 3 In Example 3, as shown in Table 2, in the coating with the metal coupling agent in Example 1, the amount of the metal coupling agent, 3-(2-aminoethyl)aminopropyltrimethoxysilane, added was changed from 2.0 parts by mass to 3.0 parts by mass, and surface treatment was performed in the same manner as in Example 1 to prepare an intermediate film and a laminated structure.

[0169] In the interlayer film of Example 3, Cs 0.33 The content of WO3 fine particles was 0.21% by mass. 0.33 The content of the metal chelate compound was 42.9 parts by mass in terms of metal element relative to 100 parts by mass of WO3 fine particles, and the content of the metal coupling agent was 42.9 parts by mass. The thickness of the coating film was 2 nm.

[0170] Example 4 In Example 4, as shown in Table 2, in the preparation of the dispersion for forming a coating film in Example 1, the surface treatment liquid a was changed to the surface treatment liquid b (prepared by mixing 32.8 parts by mass of aluminum ethyl acetoacetate diisopropylate and 67.2 parts by mass of IPA) shown in Table 1, and the surface treatment was performed in the same manner as in Example 1 to prepare an interlayer film and a laminated structure.

[0171] In the interlayer film of Example 4, Cs 0.33 The content of WO3 fine particles was 0.21% by mass. 0.33 The content of the metal chelate compound was 57.1 parts by mass in terms of metal element, the content of the metal coupling agent was 28.6 parts by mass, and the thickness of the coating film was 2 nm, relative to 100 parts by mass of WO3 fine particles.

[0172] Example 5 In Example 5, as shown in Table 2, in the preparation of the dispersion for forming a coating film in Example 2, except that the surface treatment liquid a was changed to the surface treatment liquid b shown in Table 1, surface treatment was performed in the same manner as in Example 2, and an intermediate film and a laminated structure were produced.

[0173] In the interlayer film of Example 5, Cs 0.33 The content of WO3 fine particles was 0.21% by mass. 0.33 The content of the metal chelate compound was 57.1 parts by mass in terms of metal element, the content of the metal coupling agent was 38.1 parts by mass, and the thickness of the coating film was 2 nm, relative to 100 parts by mass of WO3 fine particles.

[0174] Example 6 In Example 6, as shown in Table 2, in the preparation of the dispersion for forming a coating film in Example 3, except that the surface treatment liquid a was changed to the surface treatment liquid b shown in Table 1, surface treatment was performed in the same manner as in Example 3, and an interlayer film and a laminated structure were produced.

[0175] In the interlayer film of Example 6, Cs 0.33 The content of WO3 fine particles was 0.21% by mass. 0.33 The content of the metal chelate compound was 57.1 parts by mass in terms of metal element, the content of the metal coupling agent was 42.9 parts by mass, and the thickness of the coating film was 2 nm, relative to 100 parts by mass of WO3 fine particles.

[0176] Example 7 In Example 7, as shown in Table 2, in the preparation of the dispersion for forming a coating film in Example 1, the surface treatment liquid a was changed to the surface treatment liquid c shown in Table 1 (prepared by mixing 36.3 parts by mass of aluminum ethyl acetoacetate diisopropylate and 63.7 parts by mass of IPA), and the surface treatment was performed in the same manner as in Example 1 to prepare an intermediate film and a laminated structure.

[0177] In the interlayer film of Example 7, Cs 0.33 The content of WO3 fine particles was 0.21% by mass. 0.33 The content of the metal chelate compound was 61.9 parts by mass in terms of metal element, the content of the metal coupling agent was 28.6 parts by mass, and the thickness of the coating film was 2 nm, relative to 100 parts by mass of WO3 fine particles.

[0178] (Comparative Example 1) In Comparative Example 1, a dispersion powder containing composite tungsten oxide fine particles and a metal coupling agent was prepared without performing composite surface treatment. 0.3310 parts by mass each of WO3 microparticles and dispersant were mixed with 2 parts by mass of 3-(2-aminoethyl)aminopropyltrimethoxysilane, a metal coupling agent, and 78 parts by mass of butyl acetate. The resulting mixture was then loaded into a paint shaker containing φ0.3 mm ZrO2 beads and subjected to a pulverization and dispersion treatment for 1 hour to obtain a microparticle dispersion of Comparative Example 1. This microparticle dispersion was then introduced into a vacuum fluidized bed dryer to evaporate the medium, resulting in Cs 0.33 A dispersion powder containing WO3 fine particles was obtained. Next, 0.7 parts by mass of this dispersion powder was thoroughly mixed with 99.3 parts by mass of the ionomer resin to prepare the interlayer film composition of Comparative Example 1. Finally, an interlayer film and a laminated structure were fabricated using this interlayer film composition in the same manner as in Example 1.

[0179] In the interlayer film of Comparative Example 1, Cs 0.33 The content of WO3 fine particles was 0.21% by mass. 0.33 The content of the metal coupling agent was 14.3 parts by mass relative to 100 parts by mass of the WO3 fine particles.

[0180] (Comparative Example 2) In Comparative Example 2, Cs 0.33 The WO3 particles were only surface-treated with a metal chelate compound, and this surface-treated Cs 0.33 An interlayer film and a laminated structure were produced in the same manner as in Example 1, except that the interlayer film composition was prepared by adding WO3 fine particles together with a metal coupling agent to an ionomer resin.

[0181] Specifically, first, the surface-treated Cs obtained in the preparation of the dispersion for forming the coating film in Example 1 0.33 10 parts by mass of WO3 microparticles, 10 parts by mass of the above dispersant, and 80 parts by mass of butyl acetate were mixed. The resulting mixture was loaded into a paint shaker containing φ0.3 mm ZrO2 beads and subjected to a pulverization and dispersion treatment for 1 hour to obtain a mixture. The resulting mixture was then introduced into a vacuum fluidized bed dryer to evaporate the medium, resulting in a surface-treated Cs. 0.33A dispersion powder containing WO3 fine particles was obtained. Next, 0.8 parts by mass of this dispersion powder was thoroughly mixed with 99.14 parts by mass of the ionomer resin and 0.06 parts by mass of 3-(2-aminoethyl)aminopropyltrimethoxysilane, a metal coupling agent, to prepare the interlayer film composition of Comparative Example 2. Finally, this interlayer film composition was used to fabricate an interlayer film and a laminated structure in the same manner as in Example 1.

[0182] In the interlayer film of Comparative Example 2, Cs 0.33 The content of WO3 fine particles was 0.21% by mass. 0.33 The content of the metal chelate compound was 42.9 parts by mass relative to 100 parts by mass of the WO3 fine particles, and the thickness of the coating film was 2 nm.

[0183] <Evaluation method> The laminated structures of Examples 1 to 7 and Comparative Examples 1 and 2 thus produced were evaluated for visible light transmittance, solar radiation transmittance, and weather resistance by the following methods.

[0184] (Visible light transmittance, solar transmittance) The visible light transmittance (VLT) and solar transmittance (ST) of the laminated structure were measured in accordance with ISO 9050 and JIS R 3106. Specifically, the transmittance was measured using a spectrophotometer (Hitachi High-Tech Corporation's "U-4100") and calculated by multiplying it by a coefficient corresponding to the solar spectrum. The transmittance was measured at 5 nm intervals in the wavelength range of 300 nm to 2100 nm.

[0185] (weather resistance) The weather resistance of the laminated structure was evaluated based on the color difference ΔE before and after ultraviolet irradiation, which is a photocoloring phenomenon that occurs when ultraviolet rays are irradiated onto the interlayer film. Here, the color difference ΔE was calculated by calculating the tristimulus values X, Y, and Z for the D65 standard light source and a light source angle of 10° in accordance with JIS Z 8701 using the L*a*b* color index, and then determining the color difference ΔE from the tristimulus values in accordance with JIS Z 8729. Specifically, in an environment with a temperature of 60°C and a relative humidity of 35%, a metal halide lamp was used as the light source with an intensity of 100 mW / cm. 2The color difference ΔE was measured before and after irradiating the laminated structure with ultraviolet light for 16 hours. The color difference ΔE was calculated from the difference in L*a*b* before and after ultraviolet light irradiation in the L*a*b* color space, as shown in the following formula. ΔE=√((L* a -L* b ) 2 +(a* a -a* b ) 2 +(b* a -b* b ) 2 ) L* a :L* value before irradiation L* b : L* value after irradiation a* a : a* value before irradiation a* b : a* value after irradiation b* a : b* value before irradiation b* b : b* value after irradiation

[0186] In this example, when the visible light transmittance of the laminated structure was set to 85%, if ΔE before and after ultraviolet irradiation was 1.5 or less, the coloring was difficult to see with the naked eye and the structure was judged to have particularly excellent weather resistance. If ΔE was greater than 1.5 and less than 2.3, the coloring was sometimes visible to the naked eye, but the structure was judged to have a certain degree of weather resistance. If ΔE was greater than 2.3, the coloring was easily visible to many people and the structure was judged to have significantly poor weather resistance.

[0187] <Evaluation results> The evaluation results for the Examples and Comparative Examples are summarized in Table 3 below.

[0188] [Table 3]

[0189] As shown in Table 3, the laminated structures of the examples and comparative examples were confirmed to have good heat-shielding properties, as they all had a visible light transmittance (VLT) of 85% before exposure and a solar transmittance (ST) of 65% or more before exposure.

[0190] On the other hand, in terms of weather resistance, the color difference ΔE before and after ultraviolet irradiation in Examples 1 to 7 was 1.5 or less, achieving high weather resistance, whereas the color difference ΔE in Comparative Example 1 was 2.60 and in Comparative Example 2 was 1.71, confirming poor weather resistance.

[0191] In Comparative Example 1, Cs 0.33 The WO3 particles are not surface treated, and a metal coupling agent is added to the interlayer. 0.33 Since the metal coupling agent was simply placed near the WO3 particles, the photocoloration phenomenon could not be sufficiently suppressed.

[0192] In Comparative Example 2, Cs 0.33 The surface of the WO3 particles is treated with a metal chelate compound, and Cs 0.33 By having a metal coupling agent present in the vicinity of the WO3 fine particles, the color difference ΔE was reduced more than in Comparative Example 1, and the photocoloring phenomenon was suppressed, but this was not sufficient.

[0193] In contrast, in Examples 1 to 7, Cs 0.33 It was confirmed that by performing a composite surface treatment on the surface of WO3 microparticles with a metal chelate compound and a metal coupling agent, and then further coating the coating film formed from the hydrolysis product of the metal chelate compound or its polymer with a metal coupling agent, a strong coating film can be formed and the photocoloration phenomenon can be further suppressed.

[0194] As described above, by subjecting the composite tungsten oxide microparticles to a surface treatment using a metal chelate compound or a metal cyclic oligomer compound, and a surface treatment using a metal coupling agent, the chemical stability and weather resistance of the microparticles can be improved, and the photocoloration phenomenon caused by ultraviolet irradiation in the interlayer film can be suppressed.

[0195] <Preferred aspects of the present disclosure> Preferred aspects of the present disclosure are described below.

[0196] (Appendix 1) A plurality of transparent substrates; and at least one intermediate film interposed between the plurality of transparent substrates, The interlayer film is formed from an interlayer film composition containing at least composite surface-treated composite tungsten oxide microparticles, in which the surfaces of composite tungsten oxide microparticles are coated with a coating film containing one or more selected from the group consisting of hydrolysis products of metal chelate compounds, polymers of hydrolysis products of metal chelate compounds, hydrolysis products of metal cyclic oligomer compounds, and polymers of hydrolysis products of metal cyclic oligomer compounds, and the composite surface-treated composite tungsten oxide microparticles are coated with a metal coupling agent, and an ionomer resin. Combined structure.

[0197] (Appendix 2) In Appendix 1, preferably, The metal chelate compound or the metal cyclic oligomer compound contains one or more metal elements selected from Al, Zr, Ti, Si, and Zn.

[0198] (Appendix 3) In Supplementary Note 1 or 2, preferably, The composite tungsten oxide fine particles are represented by the general formula M x W y O z (where M is one or more elements selected from Cs, K, Rb, In, Tl, Ba, Li, Ca, Sr, Fe, and Sn, W is tungsten, O is oxygen, 0.001≦x / y≦1, 2.0≦z / y<4.0), and has a hexagonal crystal structure.

[0199] (Appendix 4) In any one of Supplementary Notes 1 to 3, preferably, The surface-treated composite tungsten oxide fine particles have a crystallite diameter of 1 nm to 800 nm.

[0200] (Appendix 5) In any one of Supplementary Notes 1 to 4, preferably, The metal coupling agent is a silane coupling agent.

[0201] (Appendix 6) In any one of Supplementary Notes 1 to 5, preferably, The content of the metal coupling agent in the composite surface-treated composite tungsten oxide particles is 20 parts by mass or more per 100 parts by mass of the composite tungsten oxide particles.

[0202] (Appendix 7) In any one of Supplementary Notes 1 to 6, preferably, The ionomer resin is an ethylene-based ionomer.

[0203] (Appendix 8) In any one of Supplementary Notes 1 to 7, preferably, The transparent substrate is one or more types selected from plate glass and plastic.

[0204] (Appendix 9) In Appendix 8, preferably, The plastic is at least one selected from polycarbonate resin, acrylic resin, and polyethylene terephthalate resin.

[0205] (Appendix 10) In any one of Supplementary Notes 1 to 9, preferably, The film has one or more interlayer films, The surface-treated composite tungsten oxide particles are dispersed in at least one of the intermediate films.

[0206] (Appendix 11) In any one of Supplementary Notes 1 to 10, preferably, Between the transparent substrates, the intermediate film and at least one infrared absorbing layer containing the surface-treated composite tungsten oxide particles are interposed.

Claims

1. A plurality of transparent substrates; and at least one intermediate film interposed between the plurality of transparent substrates, The interlayer film is formed from an interlayer film composition containing at least composite surface-treated composite tungsten oxide fine particles, in which the surfaces of composite tungsten oxide fine particles are coated with a coating film containing one or more selected from the group consisting of hydrolysis products of metal chelate compounds, polymers of hydrolysis products of metal chelate compounds, hydrolysis products of metal cyclic oligomer compounds, and polymers of hydrolysis products of metal cyclic oligomer compounds, and the composite surface-treated composite tungsten oxide fine particles are coated with a metal coupling agent, and an ionomer resin; the metal chelate compound contains Al as a metal element and is at least one selected from metal acetylacetonates and metal carboxylates, and the metal cyclic oligomer compound contains Al as a metal element; Combined structure.

2. The composite tungsten oxide fine particles are represented by the general formula M ｘ W ｙ O ｚ (wherein M is one or more elements selected from Cs, K, Rb, In, Tl, Ba, Li, Ca, Sr, Fe, and Sn, W is tungsten, O is oxygen, and 0.001≦x / y≦1, 2.0≦z / y<4.0), and has a hexagonal crystal structure. The laminated structure of claim 1 .

3. The crystallite diameter of the surface-treated composite tungsten oxide microparticles is 1 nm to 800 nm. The laminated structure according to claim 1 or claim 2.

4. The metal coupling agent is a silane coupling agent. The laminated structure according to any one of claims 1 to 3.

5. The content of the metal coupling agent in the composite surface-treated composite tungsten oxide microparticles is 20 parts by mass or more per 100 parts by mass of the composite tungsten oxide microparticles. The laminated structure according to any one of claims 1 to 4.

6. The ionomer resin is an ethylene-based ionomer. The laminated structure according to any one of claims 1 to 5.

7. The transparent substrate is one or more selected from plate glass and plastic. The laminated structure according to any one of claims 1 to 6.

8. The plastic is one or more selected from polycarbonate resin, acrylic resin, and polyethylene terephthalate resin. The laminated structure of claim 7.

9. an infrared absorbing layer containing the surface-treated composite tungsten oxide fine particles is interposed between the transparent substrates together with the intermediate film; The laminated structure according to any one of claims 1 to 8.

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