JP2023020318A - Laminated structure - Google Patents

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

The present invention relates to a laminated structure.

Conventionally, as safety glass for automobiles, laminated glass is constructed by sandwiching an interlayer film having heat ray shielding performance between two sheets of glass. Some have been proposed for the purpose of alleviating the feeling of heat.

For example, in Patent Document 1, fine particles having heat ray shielding performance such as tungsten oxide fine particles and composite tungsten oxide fine particles are added to a resin together with a metal coupling agent, an intermediate film is formed from the composition, and this intermediate film is formed. It is disclosed that a laminated structure having heat ray shielding performance is constructed by interposing a film between two laminated plates selected from sheet glass or the like.

WO 2005/087680

However, in the laminated structure disclosed in Patent Document 1, the intermediate film may be colored by ultraviolet rays contained in sunlight. This is due to the effect of coloring of the composite tungsten oxide fine particles by light. For example, when the laminated structure is applied to the safety glass of automobiles, even a slight coloring may impair the safety.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a technique for suppressing the photocoloring phenomenon caused by ultraviolet irradiation in a laminated structure.

One embodiment of the present invention is
a plurality of transparent substrates;
and at least one intermediate film interposed between the plurality of transparent substrates,
In the intermediate film, the surface of the composite tungsten oxide fine particles is a hydrolysis product of a metal chelate compound, a polymer of a hydrolysis product of a metal chelate compound, a hydrolysis product of a metal cyclic oligomer compound, or a metal cyclic oligomer compound. Composite surface-treated composite tungsten oxide fine particles obtained by coating the surface-treated composite tungsten oxide fine particles coated with a coating film containing one or more selected from hydrolysis product polymers with a metal coupling agent, and an ionomer Formed from an intermediate film composition containing at least a resin,
It is a combined structure.

According to the present invention, it is possible to suppress the photocoloring phenomenon caused by ultraviolet irradiation in the laminated structure.

FIG. 1 is a schematic diagram showing the crystal structure of a composite tungsten oxide having a hexagonal crystal structure.

It is believed that one of the causes of the photocoloring phenomenon in the laminated structure is the change in the valence of composite tungsten oxide fine particles (hereinafter also simply referred to as MWO fine particles) dispersed in the intermediate film interposed between the transparent substrates. Specifically, when the intermediate film is irradiated with ultraviolet rays, the resin component may be decomposed to generate hydrogen radicals. These hydrogen radicals are doped into the MWO fine particles, and charge compensation may change the valence of the MWO fine particles. Due to the valence change, the light transmittance of the MWO microparticles may fluctuate, resulting in coloration of the intermediate film. Another factor is that when the intermediate film is exposed to the atmosphere, for example, moisture that permeates the intermediate film from the atmosphere decomposes the surface of the MWO fine particles and changes the light transmittance. be done.

For this reason, from the viewpoint of suppressing the photocoloring phenomenon, attention was paid to surface treatment of the MWO fine particles to form a coating film on the surface of the MWO fine particles. Examples of the coating film include those formed from metal chelate compounds, metal cyclic oligomer compounds, or hydrolysis products thereof. According to this coating film, fluctuations in visible light transmittance can be suppressed when the intermediate film is exposed to a high-temperature, high-humidity environment. However, these coating films cannot sufficiently suppress coloration due to ultraviolet irradiation, and there is room for improvement.

The inventors of the present invention have further studied this point, and it is recommended that the surface treatment be performed using not only a metal chelate compound or a metal cyclic oligomer compound, but also a metal coupling agent such as a silane coupling agent. I found out. Specifically, surface-treated composite tungsten oxide fine particles obtained by coating MWO fine particles with a hydrolysis product such as a metal chelate compound are surface-treated with a silane coupling agent to obtain composite surface-treated composite tungsten oxide fine particles. I found something good. As a result, the coating film formed from the hydrolysis product such as the metal chelate compound can be further coated with the metal coupling agent, and the coating film can be uniformly and firmly formed on the fine particle surface. can. According to the coating film surface-treated with the metal coupling agent in this way, it is possible to suppress the photocoloring phenomenon due to ultraviolet irradiation in the intermediate film in the laminated structure.

The present invention has been made based on the above findings.

In the following, the surface-treated composite tungsten oxide fine particles in which a coating film is formed by surface-treating the surface of the MWO fine particles with a metal chelate compound or the like are simply referred to as the surface-treated MWO fine particles, the surface-treated MWO fine particles, and the surface-treated MWO fine particles. Furthermore, composite surface-treated composite tungsten oxide fine particles that have been surface-treated using a metal coupling agent are also simply referred to as composite surface-treated MWO fine particles.

<One embodiment of the present invention>
A laminated structure according to one embodiment of the present invention will be described below.

The laminated structure of this embodiment includes a plurality of transparent substrates and at least one intermediate film interposed between the plurality of transparent substrates. The intermediate film is formed from an intermediate film composition containing at least composite surface-treated composite tungsten oxide fine particles and an ionomer resin. Below, <1> composite tungsten oxide fine particles, <2> surface-treated composite tungsten oxide fine particles, <3> composite surface-treated composite tungsten oxide fine particles, <4> production of composite surface-treated composite tungsten oxide fine particles, < 5> Intermediate film composition, <6> Intermediate film, and <7> Laminated structure will be described.

<1> Composite Tungsten Oxide Fine Particles First, composite tungsten oxide fine particles before surface treatment will be described.

Composite tungsten oxide fine particles (MWO fine particles) are formed by adding a positive element (hereinafter also referred to as element M) that generates free electrons to tungsten oxide (WO ₃ ), and have the general formula M _x W _y O It is fine particles of composite tungsten oxide represented by _z (where M is a positive element, W is tungsten, and O is oxygen). Composite tungsten oxide fine particles show infrared absorption characteristics by controlling the amount of oxygen and adding the element M, and show strong absorption characteristics especially around 1000 nm.

Moreover, 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 crystal structure of the MWO fine particles hexagonal, the element M is one or more elements selected from Cs, K, Rb, In, Tl, Ba, Li, Ca, Sr, Fe, and Sn. is preferably

In addition, in the composite tungsten oxide represented by the general formula M _x W _y O _z , the composition ranges of the element M, tungsten and oxygen are not particularly limited, but 0.001 ≤ x/y ≤ 1, 2.0 ≤ It is preferable to satisfy the relationship z/y<4.

Regarding the above composition, first, the value of x/y indicating the amount of the element M added will be described.
If the value of x/y is 0.001 or more, a sufficient amount of free electrons are generated in the composite tungsten oxide, and the desired infrared absorption effect can be obtained. As the amount of the element M added increases, the supply amount of free electrons increases, and the infrared absorption efficiency also increases. Also, if the value of x/y is 1 or less, it is possible to avoid the formation of an impurity phase in the composite tungsten oxide fine particles, which is preferable.

Next, the value of z/y indicating the control of the oxygen amount will be explained.
Regarding the value of z/y, in the composite tungsten oxide represented by M _x W _y O _z , the same mechanism as that of the tungsten oxide represented by WyOz described above works. Even when /y<4 and 2.0≦z/y≦2.2, free electrons are supplied depending on the amount of the 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 more preferable.

Moreover, the MWO fine particles preferably have a hexagonal crystal structure from the viewpoint of improving the transparency in the visible light region and the infrared absorption characteristics. This point will be described with reference to FIG. FIG. 1 is a schematic diagram showing the crystal structure of a composite tungsten oxide having a hexagonal crystal structure.

In FIG. 1, six octahedrons formed by WO ₆ units indicated by reference numeral 11 are aggregated to form hexagonal voids, and an element M indicated by reference numeral 12 is arranged in the voids to form one A hexagonal crystal structure is constructed by assembling a number of units. In order to obtain the effect of improving light transmission in the visible light region and improving light absorption in the infrared region, the composite tungsten oxide fine particles should contain the unit structure described with reference to FIG. It does not matter whether the composite tungsten oxide fine particles are crystalline or amorphous.

When the composite tungsten oxide fine particles having a hexagonal crystal structure have a uniform crystal structure, the addition amount of the additive element M is preferably 0.2 or more and 0.5 or less, more preferably 0, in terms of x/y. .33. It is considered that the above-described element M is arranged in all the hexagonal voids because the value of x/y is 0.33.

The crystal structure of the composite tungsten oxide is not limited to hexagonal, and may be tetragonal or cubic. Depending on the crystal structure, the absorption position in the infrared region tends to change, and the absorption position tends to move to the longer wavelength side in the order of cubic < tetragonal < hexagonal. In addition, the order of hexagonal, tetragonal, and cubic crystals has a low absorption in the visible light range. Therefore, it is preferable to use a hexagonal composite tungsten oxide for the purpose of transmitting more light in the visible region and absorbing more light in the infrared region. However, the tendency of the optical characteristics described here is only a rough tendency, and changes depending on the type of additive element, the amount of addition, and the amount of oxygen, and the present invention is not limited to this.

The crystallite diameter of the MWO fine particles 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, and 1 nm or more and 100 nm or less. more preferably 10 nm or more and 70 nm or less. Here, the crystallite size is measured by X-ray diffraction pattern measurement by powder X-ray diffraction method (θ-2θ method) and analysis by 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., or the like.

The dispersed particle size of the MWO microparticles dispersed in the liquid medium can be appropriately changed according to the purpose of use. For example, when transparency is required, the dispersed particle size is preferably 800 nm or less. By setting the dispersed particle size to 800 nm or less, light is not completely blocked by scattering, and visibility in the visible light region can be maintained, and at the same time, transparency can be efficiently maintained.

Moreover, when the transparency in the visible light region is particularly important, it is preferable to further consider the scattering due to the fine particles. From the viewpoint of reducing scattering due to fine particles, the dispersed particle diameter is preferably 200 nm or less, more preferably 100 nm or less. The reason for this is that if the dispersed particle size of the particles is small, the scattering of light in the visible light region with a wavelength of 400 nm to 780 nm due to geometric scattering or Mie scattering is reduced. This is because it is possible to avoid the loss of sufficient transparency. That is, when the dispersed particle diameter is 200 nm or less, the geometric scattering or Mie scattering is reduced, resulting in a Rayleigh scattering region. This is because, in the Rayleigh scattering region, the scattered light is reduced in proportion to the sixth power of the particle diameter, so that as the dispersed particle diameter is reduced, the scattering is reduced and the transparency is improved.

Furthermore, when the dispersed particle size is 100 nm or less, the scattered light is extremely small, which is preferable. From the viewpoint of avoiding light scattering, the smaller the dispersed particle size is, the better. If the dispersed particle size is 1 nm or more, industrial production is easy.

By setting the dispersed particle diameter to 800 nm or less, the haze value of the infrared absorbing fine particle dispersion in which the composite surface-treated MWO fine particles are dispersed in the liquid medium can be 30% or less with a visible light transmittance of 85% or less. can. If the haze is greater than 30%, the glass will look like frosted glass and clear transparency cannot be obtained.

The dispersed particle size can be measured using an ELS-8000 manufactured by Otsuka Electronics Co., Ltd. based on the dynamic light scattering method.

<2> Surface-treated Composite Tungsten Oxide Fine Particles Next, surface-treated composite tungsten oxide fine particles (surface-treated MWO fine particles) obtained by subjecting the MWO fine particles described above to a surface treatment using a metal chelate compound or the like will be described.

The surface-treated MWO microparticles are obtained by subjecting the MWO microparticles to surface treatment using a metal chelate compound or a metal cyclic oligomer compound. In this surface treatment, the hydrolysis structure of the metal chelate compound or the metal cyclic oligomer compound is hydrolyzed, and the resulting hydrolysis product is attached to the surface of the MWO fine particles to obtain the hydrolysis product of the metal chelate compound, the metal Forming a coating film containing at least one selected from a polymer of a hydrolysis product of a chelate compound, a hydrolysis product of a metal cyclic oligomer compound, and a polymer of a hydrolysis product of a metal cyclic oligomer compound. be able to. Here, the hydrolysis product is not only a product obtained by hydrolyzing the entire hydrolysis structure of a metal chelate compound or the like, but also a partial hydrolysis product obtained by hydrolyzing a part of the hydrolysis structure, or a hydrolysis reaction. Including polymers that self-condensed through

The coating film may contain unreacted metal chelate compounds and metal cyclic oligomer compounds. For example, in the formation of a coating film, in a reaction system in which an organic solvent such as alcohol is interposed, even if sufficient water is present in the system due to the stoichiometric composition, the organic solvent Depending on the type and concentration of , not all the hydrolysis structures (eg, alkoxy groups, ether bonds, ester bonds, etc.) of the starting metal chelate compound and metal cyclic oligomer compound are hydrolyzed. Therefore, depending on the surface treatment conditions, which will be described later, an amorphous state in which carbon C is incorporated into the molecule may occur even after hydrolysis. As a result, the coating film may contain unreacted substances such as metal chelate compounds.

<2-1> Metal chelate compound The metal chelate compound for forming the coating film has a metal and hydrolysis structure, and forms a hydrolysis product that can adhere to the surface of the MWO microparticles upon hydrolysis. do. The metal contained in the metal chelate compound preferably contains at least one of Al, Zr, Ti, Si and Zn from the viewpoint of improving the chemical stability of the composite surface-treated MWO fine particles. Moreover, as a hydrolyzable structure, it is preferable to have one or more selected from an ether bond, an ester bond, an alkoxy group, and an acetyl group. Specifically, any one of metal alkoxide, metal acetylacetonate and metal carboxylate is preferred.

As the metal chelate compound, specifically, the following compounds can be used.

Examples of aluminum-based chelate compounds include aluminum alcoholates such as aluminum ethylate, aluminum isopropylate, aluminum sec-butylate, mono-sec-butoxyaluminum diisopropylate, and polymers thereof, ethylacetoacetate aluminum diisopropylate, aluminum tris (ethylacetoacetate), octylacetoacetate aluminum diisopropylate, stearylacetoaluminum diisopropylate, aluminum monoacetylacetonate bis(ethylacetoacetate), aluminum tris(acetylacetonate), and the like.
These compounds are prepared by dissolving an aluminum alcoholate in an aprotic solvent, a petroleum solvent, a hydrocarbon solvent, an ester solvent, a ketone solvent, an ether solvent, an amide solvent, etc., and adding β- It is an alkoxy group-containing aluminum chelate compound obtained by adding a diketone, β-ketoester, a monohydric or polyhydric alcohol, a fatty acid, etc., followed by heating under reflux, and performing a ligand substitution reaction.

Zirconia-based chelate compounds include zirconium alcoholates such as zirconium ethylate and zirconium butyrate, or polymers thereof, zirconium tributoxy stearate, zirconium tetraacetylacetonate, zirconium tributoxy acetylacetonate, zirconium dibutoxy bis(acetyl acetonate), zirconium tributoxyethylacetoacetate, zirconium butoxyacetylacetonate bis(ethylacetoacetate), and the like.

Titanium-based chelate compounds include titanium alcoholates such as methyl titanate, ethyl titanate, isopropyl titanate, butyl titanate, and 2-ethylhexyl titanate, polymers thereof, titanium acetylacetonate, titanium tetraacetylacetonate, and titanium octylene glycolate. , titanium ethyl acetoacetate, titanium lactate, titanium triethanolamine, and the like.

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 hydrolysis thereof The product can be used. Specific examples of tetrafunctional silane compounds include tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane, tetrabutoxysilane and the like. Furthermore, application of silane monomers (or oligomers) in which part or all of the alkoxy groups of these alkoxysilane monomers are hydrolyzed to form silanol (Si—OH) groups, and polymers that are self-condensed through hydrolysis reactions. is also possible.
Further, the hydrolysis products of the tetrafunctional silane compound include silane monomers in which part or all of the alkoxy groups are hydrolyzed to form silanol (Si—OH) groups, tetra- to pentamer oligomers, and , a polymer (silicone resin) having a weight average molecular weight (Mw) of about 800 to 8000. Note that not all of the alkoxysilyl groups (Si--OR) in the alkoxysilane monomer are hydrolyzed to silanol (Si--OH) in the course of the hydrolysis reaction.

Zinc-based chelate compounds include organic zinc carboxylates such as zinc octoate, zinc laurate, and zinc stearate, zinc acetylacetone chelate, zinc benzoylacetone chelate, zinc dibenzoylmethane chelate, ethyl zinc acetoacetate chelate, and the like. It can be exemplified preferably.

Among the above metal chelate compounds, those containing Al are particularly preferred. According to Al-based metal chelate compounds, the hydrolysis reaction is not as fast as Ti-based and Zn-based compounds, and the hydrolysis reaction is faster than Zr-based compounds. It is easy to form a uniform coating film. As a result, the chemical stability of the coating film can be made higher. Moreover, the production cost can be reduced, and the safety is also excellent.

<2-2> Metal Cyclic Oligomer Compound A metal cyclic oligomer compound is a cyclic oligomer having a metal and a hydrolyzable structure. From the viewpoint of improving the chemical stability of the composite surface-treated MWO fine particles, it is preferable to contain any one of Al, Zr, Ti, Si and Zn. Moreover, as a hydrolyzable structure, it is preferable to have 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-based, Zr-based, Ti-based, Si-based, and Zn-based cyclic oligomer compounds. Among these, cyclic aluminum oligomer compounds such as cyclic aluminum oxide octylate are preferred.

<2-3> Thickness of Coating Film The thickness of the coating film of the surface-treated MWO fine particles is not particularly limited, but is preferably 0.5 nm or more and 100 nm or less. By setting the particle size to 0.5 nm or more, the chemical stability of the composite surface-treated MWO fine particles can be improved, and the weather resistance can be improved. On the other hand, by setting the thickness to 100 nm or less, the intermediate film can maintain high optical properties such as transparency and infrared absorption properties. From the viewpoint of achieving both high levels of weather resistance and optical properties, the thickness of the coating film is more preferably 0.5 nm or more and 20 nm or less, and further preferably 1 nm or more and 10 nm or less. The thickness of the coating film can be measured with a transmission electron microscope, and the thickness of the coating film corresponds to the thickness of the MWO fine particles where there are no lattice fringes (arrangement of atoms in the crystal).
The content of the metal chelate compound and metal cyclic oligomer compound forming the coating film is not particularly limited as long as the above thickness is satisfied. 40 parts by mass or more and 150 parts by mass or less is more preferable. This content is the content in terms of the metal element derived from the metal chelate compound or the metal cyclic oligomer compound, and is measured based on ICP emission spectroscopy as shown in Examples below.

<3> Composite surface-treated composite tungsten oxide fine particles Next, composite surface-treated composite tungsten oxide fine particles (composite surface-treated MWO fine particles) obtained by surface-treating the surface-treated MWO fine particles described above with a metal coupling agent. explain.

Composite surface-treated MWO fine particles are obtained by further subjecting the surface-treated MWO fine particles to a surface treatment using a metal coupling agent. In this surface treatment, a coating film containing a metal coupling agent can be formed by adhering a metal coupling agent onto the coating film provided on the surface of the surface-treated MWO microparticles. Thereby, the coating film can be formed to have a uniform thickness and to be stronger.

<3-1> Metal Coupling Agent The metal coupling agent is not particularly limited as long as it can adhere to the surface of a coating film formed using a metal chelate compound or a metal cyclic oligomer compound. As the metal coupling agent, for example, a silane coupling agent, a titanate coupling agent (titanate coupling agent), an aluminate coupling agent (aluminate coupling agent), or the like can be used. In addition, a metal coupling agent may be used individually by 1 type, and may use 2 or more types together.

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

Titanate-based coupling agents are not particularly limited, but examples include tetramethoxytitanium, tetraethoxytitanium, tetraisopropoxytitanium, tetra-normal butoxytitanium, tetraisobutoxytitanium, tetra-2-ethylhexoxide titanium, Tetrakis(methoxypropoxy)titanium, tetraphenoxytitanium, tetrabenzyloxytitanium, tetraphenylethoxytitanium, tetraphenoxyethoxytitanium, tetranaphthyloxytitanium, tetra-2-ethylhexoxytitanium, monoethoxytriisopropoxytitanium, diisopropoxy Diisobutoxytitanium, Allyloxy(polyethyleneoxy)trisisopropoxytitanium, Titanium chloride triisopropoxide, Titanium dichloride diethoxide, Titanium 2-ethylhexoxide, Titanium iodine triisopropoxide, Titanium tetramethoxypropoxide, Titanium Tetramethylphenoxide, titanium n-nonyloxide, titanium tetrastearyl oxide, titanium triisostearoyl monoisopropoxide and the like can be preferably used.

The aluminate-based coupling agent is not particularly limited, but examples include aluminum ethylate, aluminum isopropylate, aluminum diisopropylate mono-secondary butyrate, aluminum secondary butyrate, aluminum ethylacetoacetate diisopropylate, aluminum tris Ethyl acetoacetate, aluminum alkylacetoacetate diisopropylate, aluminum bisethylacetoacetate monoacetylacetonate, aluminum trisacetylacetonate and the like can be preferably used.

The metal coupling agent preferably contains a silane coupling agent, more preferably a silane coupling agent.

Moreover, from the viewpoint of further improving the transparency of the intermediate film, the metal coupling agent preferably has at least one of an epoxy group and an amino group as a functional group. According to such a metal coupling agent, a functional group is introduced to the surface of the composite surface-treated MWO microparticles, and aggregation of the composite surface-treated MWO microparticles can be suppressed by steric hindrance caused by the functional group. That is, it is possible to improve the dispersibility of the composite surface-treated MWO fine particles in the intermediate film. Thereby, the transparency of the intermediate film can be further improved.

Silane coupling agents containing an epoxy group or an amino group in their structure include, for example, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-(2-aminoethylamino)propyltrimethoxysilane, 3-(2-aminoethylamino)propyldimethoxymethylsilane, trimethoxy[3-(phenylamino)propyl]silane and the like can be preferably used.

<3-2> Coating amount of metal coupling agent In addition, the content of the metal coupling agent in the composite surface-treated MWO fine particles is not particularly limited. It may be changed as appropriate according to the weather resistance and dispersibility of. The content of the metal coupling agent is preferably 20 parts by mass or more, more preferably 20 parts by mass or more and 100 parts by mass or less, and 20 parts by mass or more and 60 parts by mass or less with respect to 100 parts by mass of the MWO fine particles. is more preferred. In addition, this content is measured based on ICP emission spectroscopic analysis, as shown in the examples below.

<4> Production of composite surface-treated composite tungsten oxide fine particles Next, a method for producing composite surface-treated MWO fine particles will be described. The composite surface-treated MWO microparticles are obtained by subjecting the MWO microparticles to a surface treatment using a metal chelate compound or a metal cyclic oligomer compound, followed by a surface treatment using a metal coupling agent. Specifically, it is as follows.

<4-1> Step of Preparing Composite Tungsten Oxide Fine Particle Dispersion First, a fine particle powder containing MWO fine particles is added to a liquid medium and dispersed to prepare an MWO fine particle dispersion. Here, the MWO fine particles are preferably pulverized in advance and then added to the liquid medium. Alternatively, after adding the fine particle powder to the liquid medium, it is preferable to perform the pulverization and dispersion treatment. Thereby, aggregation of the MWO fine particles can be suppressed, and the MWO fine particles can be monodispersed in the liquid medium. By monodispersing the MWO microparticles, it becomes possible to uniformly surface-treat each of the MWO microparticles and form a coating film having a uniform thickness during the surface treatment described below. In addition, it is possible to suppress deterioration of the transparency of the intermediate film due to aggregates of MWO fine particles.

For example, water or an organic solvent can be used as the liquid medium used when preparing the MWO fine particle dispersion. As the organic solvent, for example, alcohol-based, ketone-based, and glycol-based solvents that dissolve in water at room temperature can be used, and various solvents can be selected. Among these, water is preferable as the liquid medium. As will be described later, by using water as the liquid medium, the coating film can be formed with high density.

In the MWO fine particle dispersion liquid, the amount of the MWO fine particles added is not particularly limited, but it is preferable to adjust the concentration of the MWO fine particles dispersed in the liquid medium to be 0.01% by mass or more and 80% by mass or less. By setting such a dispersion concentration, the pH of the MWO fine particle dispersion liquid can be set to 8 or less, and the state in which the MWO fine particles are dispersed in the liquid medium by electrostatic repulsion can be easily maintained.

Specific methods for pulverizing and dispersing powder containing MWO fine particles include, for example, pulverizing and dispersing methods using devices such as bead mills, ball mills, sand mills, paint shakers, and ultrasonic homogenizers. Among them, the time to reach the desired dispersed particle size is short when pulverizing and dispersing with a medium stirring mill such as a bead mill, ball mill, sand mill, paint shaker, etc., using medium media such as beads, balls, and Ottawa sand. Therefore, it is preferable.

<4-2> Step of Preparing Coating Film-Forming Dispersion Liquid Next, a coating film-forming dispersion liquid is prepared in order to form a coating film on the surfaces of the MWO fine particles.

Specifically, first, a metal chelate compound or a metal cyclic oligomer compound is prepared as a surface treatment agent for forming a coating film. These may be used as they are, or may be diluted with a solvent to adjust the amount added per hour when added to the MWO fine particle dispersion. As the solvent used for dilution, a solvent that does not react with the surface treatment agent and has high compatibility with the liquid medium contained in the MWO fine particle dispersion is preferred. Specifically, alcohol-based, ketone-based, glycol-based, and the like can be preferably used.

Subsequently, a predetermined amount of surface treatment agent is added to the MWO fine particle dispersion liquid over a predetermined period of time. A metal chelate compound or a metal cyclic oligomer compound is added to the MWO fine particle dispersion and hydrolyzed to form a hydrolysis product or a polymer thereof. A coating film containing at least one of the hydrolysis product and the polymer is formed by the adhesion of the hydrolysis product and the polymer to the surface of the MWO microparticles. Thereby, a dispersion liquid containing the surface-treated MWO fine particles is obtained.

The addition of the surface treatment agent is preferably carried out while stirring and mixing the MWO fine particle dispersion. Aggregation of the MWO fine particles can be suppressed by stirring and mixing, and a monodispersed state can be maintained. As a result, the formation of a coating film on the surfaces of aggregates of MWO fine particles can be suppressed, and the hydrolysis product or polymer can be uniformly and firmly adhered to the surfaces of individual MWO fine particles. As a result, it is possible to suppress the formation of coarse particles that reduce transparency and form a dense and high-density coating film.

The amount of the metal chelate compound or metal cyclic oligomer compound to be added is preferably 0.05 parts by mass or more and 300 parts by mass or less, and 0.3 parts by mass or more and 150 parts by mass in terms of metal element, with respect to 100 parts by mass of the MWO fine particles. Part or less is more preferable. By setting the addition amount to 0.1 parts by mass or more, the coating film can improve the chemical stability of the MWO microparticles. On the other hand, by setting the addition amount to 300 parts by mass or less, it is possible to suppress excessive adhesion of the hydrolysis products and their polymers to the MWO fine particles. In addition, the improvement in moist heat resistance due to the surface treatment does not saturate, and an improvement in the covering effect can be expected. Furthermore, it is possible to prevent the MWO microparticles from easily granulating each other through the hydrolysis product or the like when the medium is removed due to an excessive coating amount of the hydrolysis product or polymer on the MWO microparticles. can. As a result, deterioration of transparency due to granulation can be suppressed, and good transparency can be ensured. Moreover, it is possible to avoid an increase in production cost due to an increase in the amount of addition and treatment time due to an excess of the metal chelate compound or metal cyclic oligomer compound.

In the MWO fine particle dispersion system using water as the liquid medium, the metal chelate compound, the metal cyclic oligomer compound, their hydrolysis products, and the polymers of the hydrolysis products contain metal ions immediately after the addition of the surface treatment agent. However, the decomposition to metal ions ends when the aqueous solution becomes saturated.

In addition, when water is used as the liquid medium for the MWO fine particle dispersion, hydrolysis of the metal chelate compound and the metal cyclic oligomer compound can be performed more quickly than when an organic solvent is used when the surface treatment agent is added. can be done. Therefore, after the hydrolysis reaction of the metal chelate compound or the like is completed, the polymerization reaction of the produced hydrolysis product can proceed. As a result, it is possible to prevent the metal chelate compound from being completely hydrolyzed and taken into the coating film, and to reduce the amount of carbon derived from the unreacted metal chelate compound. By reducing the amount of carbon mixed in, the coating film can be formed at a high density.

In addition, the concentration of carbon derived from the unreacted surface treatment agent present in the coating film is not particularly limited, but from the viewpoint of forming the coating film at a high density, it is 0.2% by mass or more and 5.0% by mass. % or less, more preferably 0.5 mass % or more and 3.0 mass % or less.

On the other hand, when the MWO fine particle dispersion contains an organic solvent as a liquid medium, it is preferable to parallel drop pure water together with the surface treatment agent while mixing and stirring the MWO fine particle dispersion. At this time, it is preferable to appropriately control the medium temperature, which affects the reaction rate, and the dropping rate 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 fine particle dispersion can be reduced.

<4-3> Treatment Step after Preparation of Coating Film-Forming Dispersion The dispersion containing the surface-treated MWO fine particles obtained by preparing the coating film-forming dispersion is coated with a metal coupling agent described below. It may be used in the process as it is or may be heat-treated.

The surface-treated MWO microparticles may be used as they are without the need for further heat treatment to increase the density and chemical stability of the coating film. This is because heat resistance can be exhibited by adding a silicon compound, which will be described later.

On the other hand, the dispersion liquid containing the surface-treated MWO fine particles may be heat-treated for the purpose of obtaining the surface-treated MWO fine particles from the dispersion liquid, the purpose of drying the powder of the surface-treated MWO fine particles, and the like. In the case of heat treatment, attention should be paid so that the heat treatment temperature does not exceed the temperature at which the surface-treated MWO fine particles strongly aggregate to form a strong agglomerate.

This is because the finally obtained composite surface-treated MWO microparticles are often required to be transparent from the viewpoint of the use of laminated structures. If these aggregates are present, a laminated structure having a high haze will be obtained when it is produced. If the heat treatment is performed at a temperature exceeding the temperature at which the aggregates are formed, in order to ensure the transparency of the infrared-absorbing fine particle dispersion and the infrared-absorbing substrate, the aggregates are crushed dry or / and wet. re-dispersion. However, when crushing and re-dispersing, the coating film on the surface of the surface-treated MWO fine particles may be damaged, and in some cases, a part of the coating film may be peeled off, exposing the surface of the fine particles. be done.

As described above, the surface-treated MWO fine particles do not require heat treatment after the treatment after mixing and stirring, and therefore do not cause strong aggregation. is enough. As a result, the coating film of the surface-treated MWO microparticles of the present embodiment is not damaged, and the individual MWO microparticles remain coated.

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

Specifically, first, surface-treated MWO microparticles having a coating film on the surface, a liquid medium, and a metal coupling agent are mixed, and dispersed and crushed. This causes the metal coupling agent to adhere to the coating film present on the surface of the MWO microparticles. As a result, a dispersion containing composite surface-treated MWO fine particles having a coating film to which the metal coupling agent adheres is obtained.

The obtained dispersion may be used as it is, or if necessary, the liquid medium may be volatilized by the drying method described above to obtain a dispersed powder containing composite surface-treated MWO fine particles.

The amount of the metal coupling agent added is not particularly limited. Preferably, the amount of the metal coupling agent to be added is appropriately adjusted 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 makes it possible to maintain high transparency in the intermediate film while improving the chemical stability of the composite surface-treated MWO microparticles.

The liquid medium used in the coating step with the metal coupling agent preferably has a low boiling point and is easily volatilized from the viewpoint of drying the liquid medium to obtain composite surface-treated MWO fine particles. Specifically, an organic solvent having a boiling point of 120° C. or less is preferable. By using an easily volatilizable organic solvent, the drying time can be shortened and the productivity of composite surface-treated MWO fine particles can be improved. In addition, residual organic solvent can be suppressed in the dispersed powder obtained by drying. As a result, it is possible to suppress the generation of air bubbles in the intermediate film during the production of the intermediate film, which will be described later.

Specifically, toluene, methyl ethyl ketone, methyl isobutyl ketone, butyl acetate, isopropyl alcohol, ethanol and the like can be preferably used as the liquid medium.

As described above, composite surface-treated MWO fine particles can be obtained.

<5> Intermediate film composition Subsequently, an intermediate film composition for forming an intermediate film will be described.

The intermediate film composition of the present embodiment contains at least the above-described composite surface-treated MWO fine particles and an ionomer resin, and if necessary, other additives. The intermediate film composition is obtained by mixing and kneading the composite surface-treated MWO fine particles, the ionomer resin, and, if necessary, other additives. The ionomer resin and other additives are described below.

<5-1> Ionomer Resin The ionomer resin serves as the base polymer of the intermediate film composition. The ionomer resin can obtain high adhesion to the transparent substrate. Therefore, when the intermediate film is interposed between the transparent substrates in the laminated structure, the adhesion between the intermediate film and the transparent substrate can be enhanced.

The ionomer resin is not particularly limited, and various known ionomer resins can be used, and the resin can be arbitrarily selected according to the intended use of the intermediate film. Known ionomer resins include, for example, ethylene-based ionomers, styrene-based ionomers, ionomer elastomers, perfluorocarbon ionomers, urethane ionomers, and the like. can be selected and used. From the viewpoint of adhesion to the transparent substrate, the ionomer resin more preferably contains an ethylene-based ionomer, and the ionomer resin is more preferably an ethylene-based ionomer. The ionomer resin used in the intermediate film composition may be of one kind, but two or more ionomer resins may be used in combination.

Also, the metal ions contained in the ionomer resin are not particularly limited. For example, ionomer resins containing one or more metal ions selected from zinc, magnesium, lithium, potassium, and sodium can be used. . In particular, ionomer resins containing zinc ions are preferably used.

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, and ethylene/methacrylic acid/acrylic acid esters. A metal element ionomer of a copolymer, a metal element ionomer of an ethylene/methacrylic acid/methacrylic acid ester copolymer, and the like are included. The metal ions contained in any ionomer resin are not particularly limited, and may contain, for example, ions of one or more metals selected from zinc, magnesium, lithium, potassium, and sodium.

More specific examples of ionomer resins include Surlyn (registered trademark) series from Dupont, Hi-Milan (registered trademark) series from DuPont Mitsui Polychemicals, IOTEK (registered trademark) from ExxonMobil Chemical Series and the like can be preferably used.

<5-2> Other Additives In addition to the components described above, the intermediate film composition may contain other additives, if necessary. Other additives are described below.

(metal coupling agent)
Aside from the surface treatment of the MWO fine particles, a metal coupling agent may be added and dispersed in the intermediate film composition. As the metal coupling agent, those mentioned above can be used. Moreover, the addition amount thereof may be appropriately adjusted within a range that does not impair the chemical stability and optical properties of the intermediate film.

(dispersant)
In the intermediate film, the intermediate film composition may contain a dispersant in order to suppress aggregation of the composite surface-treated MWO fine particles during the production process and maintain dispersibility. The dispersant is not particularly limited, and can be arbitrarily selected according to the manufacturing conditions of the intermediate film. For example, it has a thermal decomposition temperature of 250 ° C. or higher as measured using a differential thermal/thermogravimetric analyzer (hereinafter also referred to as TG-DTA), and is selected from a urethane main chain, an acrylic main chain, and a styrene main chain. A dispersant having a main chain or a main chain in which two or more types of unit structures selected from urethane, acryl, and styrene are copolymerized is preferable. Here, the thermal decomposition temperature is the temperature at which weight loss due to thermal decomposition of the dispersant begins, as measured by TG-DTA in accordance with JISK7120.

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. This is because it is possible to more reliably avoid a situation in which the original optical characteristics cannot be obtained by suppressing them.

Further, the dispersant preferably has one or more functional groups selected from amine-containing groups, hydroxyl groups, carboxyl groups, and epoxy groups. The dispersant having any of the functional groups described above can adsorb to the surface of the composite surface-treated MWO fine particles, prevent aggregation of the fine particles, and more uniformly disperse the surface-treated composite tungsten oxide fine particles in the intermediate film. Therefore, it can be preferably used.

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

The amount of the dispersant added is not particularly limited, but for example, it is preferably added in an amount of 10 parts by mass or more and 1000 parts by mass or less with respect to 100 parts by mass of the composite surface-treated MWO fine particles, and 30 parts by mass or more and 400 parts by mass. It is more preferable to add so that it becomes 1 part or less.

(Ultraviolet absorber)
An ultraviolet absorber may be added to the intermediate film composition. The intermediate film can mainly block light in the infrared region by containing the composite surface-treated MWO fine particles, and can block light in the ultraviolet region by further containing an ultraviolet absorber. As a result, it is possible to suppress the temperature rise in the inner region where the intermediate film is arranged and to reduce the influence of ultraviolet rays.

Further, when a metal coupling agent is added to the intermediate film composition, the effect of suppressing the photocoloration phenomenon by the metal coupling agent and the effect of suppressing the photocoloration phenomenon by the ultraviolet absorber can be synergistically obtained. It becomes possible to further suppress the photocoloring phenomenon.

The ultraviolet absorber is not particularly limited, and can be arbitrarily selected according to the effect on the visible light transmittance of the intermediate film, the ultraviolet absorbing ability, the durability, and the like. 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. etc. In particular, the ultraviolet absorber preferably contains one or more selected from benzotriazole compounds and benzophenone compounds. This is because benzotriazole compounds and benzophenone compounds can increase the visible light transmittance of the intermediate film even when added in concentrations sufficient to absorb ultraviolet rays, and are durable against long-term exposure to strong ultraviolet rays. Because it is expensive.

Moreover, 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.

The amount of the ultraviolet absorber to be added is not particularly limited, and can be arbitrarily selected according to the visible light transmittance required for the laminated structure, the ultraviolet shielding ability, and the like. The amount of the ultraviolet absorber to be added is preferably, for example, 0.02% by mass or more and 5.0% by mass or less. This is because ultraviolet light can be sufficiently absorbed when the content of the ultraviolet absorber is 0.02% by mass or more. Also, if the content is 5.0% by mass or less, the ultraviolet absorber will not precipitate in the intermediate film, and the strength, adhesive strength, and penetration resistance of the film will not be significantly affected.

(Light stabilizer)
A light stabilizer may be added to the intermediate film composition together with the ultraviolet absorber described above. When the intermediate film is used for a long period of time, the UV absorber may deteriorate and its UV absorption capacity may be lowered. In this regard, by further adding a light stabilizer, deterioration of the ultraviolet absorber can be suppressed, and the effect of the ultraviolet absorber can be maintained at a high level over a long period of time. Hindered amine light stabilizers (HALS) can be used as such light stabilizers.

The HALS is not particularly limited, and can be arbitrarily selected depending on the effect on the visible light transmittance of the intermediate film, compatibility with the ultraviolet absorber, durability, and the like. For example, 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-butane tetracarboxylate, (Mixed 1,2,2,6,6-pentamethyl-4-piperidyl/tridecyl)-1,2,3,4- Butane tetracarboxylate, Mixed {1,2,2,6,6-pentamethyl-4-piperidyl/β,β,β',β'-tetramethyl-3,9-[2,4,8,10-tetra oxaspiro(5,5)undecane]diethyl}-1,2,3,4-butanetetracarboxylate, (Mixed 2,2,6,6-tetramethyl-4-piperidyl/tridecyl)-1,2,3, 4-butane tetracarboxylate, Mixed {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-butane tetracarboxylate, 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], dimethylsuccinate polymer-with-4-hydroxy-2,2, 6,6- Tetramethyl-1-piperidine ethanol (polymerization of dimethyl succinate and 4-hydroxy-2,2,6,6-tetramethyl-1-piperidine ethanol), N,N',N'',N'' '-Tetrakis-(4,6-bis-(butyl-(N-methyl-2,2,6,6-tetramethylpiperidin-4-yl)amino)-triazin-2-yl)-4,7-diazadecane -1,10-diamine, dibutylamine-1,3,5-triazine-N,N'-bis(2,2,6,6-tetramethyl-4-piperidyl-1,6-hexamethylenediamine and N- Polycondensate of (2,2,6,6-tetramethylpiperidyl)butylamine, decanedioic acid bis(2,2,6,6-tetramethyl-1-(octyloxy)-4-piperidinyl) ester, etc. are preferred. can be used for

The amount of HALS to be added is not particularly limited, and can be arbitrarily selected according to the visible light transmittance, weather resistance, etc. required for the intermediate 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 when the HALS content is 0.05% by mass or more, the effects of the addition of HALS can be exhibited in the intermediate film. Also, when the content is 5.0% by mass or less, HALS does not precipitate in the intermediate film and does not affect the strength, adhesive strength, and penetration resistance of the film.

(Antioxidant)
An antioxidant may be added to the intermediate film composition from the viewpoint of suppressing oxidative deterioration of the resin and improving its weather resistance. Antioxidants can suppress oxidation degradation not only of the resin, but also of other additives such as composite surface-treated MWO fine particles, metal coupling agents, and UV absorbers contained in the intermediate film, improving weather resistance. can be made

The antioxidant is not particularly limited, and can be arbitrarily selected depending on the effect on the visible light transmittance of the intermediate film and the desired durability. For example, phenol-based antioxidants, sulfur-based antioxidants, phosphorus-based antioxidants, and the like can be suitably used, and 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-6-t-butylphenol), 1,1 , 3-tris-(2-methyl-hydroxy-5-t-butylphenyl)butane, tetrakis[methylene-3-(3′,5′-butyl-4-hydroxyphenyl)propionate]methane, 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 preferably used.

The amount of the antioxidant to be added is not particularly limited, and can be arbitrarily selected according to the visible light transmittance, weather resistance, etc. required for the intermediate film. The amount of antioxidant to be added is preferably, for example, 0.05% by mass or more and 5.0% by mass or less. This is because when the amount of the antioxidant added is 0.05% by mass or more, the effect of the addition of the antioxidant can be exhibited in the intermediate film. Also, if the amount added is 5.0% by mass or less, the antioxidant will not precipitate in the intermediate film, and the strength, adhesive strength, and penetration resistance of the film will not be significantly affected.

(Plasticizer)
A plasticizer may be added to the intermediate film composition in order to improve the adhesion of the intermediate film to the transparent substrate. As the plasticizer, those commonly used for the ionomer resin forming the intermediate film may be used.

(dye)
In order to give an arbitrary color tone to the intermediate film composition, dye compounds generally used for coloring resins, such as azo dyes, cyanine dyes, quinoline dyes, perylene dyes, and carbon black, A pigment compound may be added.

(Infrared absorbing substance)
In addition to the composite surface-treated MWO fine particles, an infrared absorbing substance may be added to the intermediate film composition in order to further improve the infrared shielding ability. Although the other infrared absorbing substance is not particularly limited, it is preferably a substance capable of absorbing light in a wavelength region different from that of the composite surface-treated MWO particles used. For example, an infrared absorbing organic compound can be preferably used. By adding an infrared absorbing organic compound, even higher infrared shielding ability can be obtained.

(Adhesion adjuster)
An adhesive force regulator may be added to the intermediate film composition in order to adjust the adhesive force between the intermediate film and the transparent substrate. Although not particularly limited, for example, an alkali metal salt and/or an alkaline earth metal salt can be preferably used as the adhesive strength modifier. The acid that constitutes the alkali metal salt and/or the alkaline earth metal salt is not particularly limited. mentioned. Among alkali metal salts and/or alkaline earth metal salts, magnesium salts of carboxylates having 2 to 16 carbon atoms and potassium salts of carboxylates having 2 to 16 carbon atoms are preferred.

The magnesium salt and potassium salt of an organic acid having 2 to 16 carbon atoms are not particularly limited, but examples include magnesium acetate, potassium acetate, magnesium 2-ethylbutyrate, magnesium propionate, potassium propionate, and 2-ethylbutanoic acid. Magnesium, potassium 2-ethylbutanoate, magnesium 2-ethylhexanoate, potassium 2-ethylhexanoate and the like are preferably used. Among these, magnesium 2-ethylbutyrate is preferable because of its high performance as an adhesive strength modifier. In addition, only one type of adhesive strength adjusting agent may be added, or two or more types may be added.

(others)
In addition to the additives described above, for example, surfactants and antistatic agents may be added to the intermediate film composition.

<6> Intermediate Film The intermediate film is formed from the intermediate film composition described above, and contains the composite surface-treated MWO fine particles, the ionomer resin, and, if necessary, other additives.

In the intermediate film, the content of the composite surface-treated MWO fine particles may be appropriately changed according to the transparency and heat ray shielding performance required for the intermediate film. For example, when the laminated structure is used for applications such as window materials, it is preferable that the visible light transmittance is high from the viewpoint of maintaining light transmittance to the human eye, and from the viewpoint of reducing heat incident from sunlight. Low solar transmittance and light coloration are preferred. Further, for example, when the laminated structure is used as an agricultural sheet, it is preferable that the visible light transmittance is high from the viewpoint of maintaining the visible light transmittance necessary for plant growth, and from the viewpoint of reducing heat incident from sunlight. Therefore, it is preferable that the solar transmittance is low.

The intermediate film can be produced by molding the intermediate film composition described above. Here, as an example, a case where a dispersed powder containing composite surface-treated MWO fine particles is produced, the dispersed powder and an ionomer resin are mixed to prepare an intermediate film composition, and then this is molded to produce an intermediate film. explain.

(Manufacturing process of dispersed powder)
First, a dispersed powder containing composite surface-treated MWO fine particles is prepared.

Specifically, the above dispersant is added to and mixed with the dispersion containing the composite surface-treated MWO fine particles and the liquid medium. At this time, if necessary, other additives such as a metal coupling agent may be added. Subsequently, the obtained mixture is subjected to dispersion and pulverization treatment to prepare a dispersion liquid containing composite surface-treated MWO fine particles and a dispersant. After that, the liquid medium is removed from this dispersion to obtain a dispersed powder containing composite surface-treated MWO fine particles and a dispersant. In the dispersed powder, part or all of the dispersant exists in contact with the composite surface-treated MWO fine particles.

As the liquid medium used in preparing the dispersion containing the composite surface-treated MWO fine particles, the organic solvent used in the coating step with the metal coupling agent described above is preferable. Moreover, it is preferable to employ the above-described method for the dispersion/pulverization treatment.

(Kneading process)
Subsequently, the obtained dispersed powder and ionomer resin are mixed. At this time, if necessary, other additives such as ultraviolet absorbers, HALS, antioxidants, and infrared absorbing substances may be added. The obtained mixture is kneaded by a known kneading method to obtain an intermediate film composition containing composite surface-treated MWO fine particles.

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

(Molding process)
Subsequently, the resulting intermediate film composition is molded to produce an intermediate film. The molding method is not particularly limited, and may be appropriately selected from conventionally known methods according to the size and shape such as the thickness of the intermediate film, or the viscosity of the intermediate film composition. For example, an extrusion molding method, a calender molding method, or the like may be employed.

The shape of the intermediate film is not particularly limited, and can be appropriately changed according to the shape required for the laminated structure. This shape can be, for example, a film shape.

<7> Laminated Structure Next, the laminated structure of the present embodiment will be described.

The laminated structure of this embodiment includes a plurality of transparent substrates and at least one intermediate film interposed between the plurality of transparent substrates.

The transparent substrate is a member that sandwiches the intermediate film from both sides thereof, and has transparency in the visible light region. As the transparent base material, for example, a glass base material, a resin base material, or the like can be used. The plurality of transparent substrates constituting the laminated structure may all be substrates of the same material, or substrates of different materials may be combined, for example, a glass substrate and a resin substrate may be used in combination. .

The resin base material is appropriately selected according to the use of the laminated structure. For example, when used in transportation equipment such as automobiles, polycarbonate resin, acrylic resin, polyester resin, polyethylene terephthalate resin, etc. A transparent resin is preferred.

A laminated structure including an intermediate film can be produced, for example, as follows.

First, an additive liquid in which composite surface-treated MWO fine particles are dispersed in a plasticizer is added to an ionomer resin to prepare an intermediate film composition, and this intermediate film composition is formed into a sheet to produce an intermediate film. Subsequently, the intermediate film is sandwiched between two laminated plates selected from sheet glass or plastic and laminated together, thereby producing a laminated structure.

Here, an example of dispersing the composite surface-treated MWO fine particles in a plasticizer was described, but a dispersion liquid in which the composite surface-treated MWO fine particles were dispersed in an appropriate solvent other than a plasticizer was added to the ionomer resin, and the plasticizer was separately added. may be added to prepare an intermediate film composition.

As a result, a laminated structure having high infrared shielding properties and a small haze value can be produced. Furthermore, the method facilitates the production of a laminated structure and enables the production of a laminated structure with low production costs.

In the above, the case where the intermediate film is arranged alone between the transparent substrates has been described, but a multilayer film composed of the intermediate film and other films may be formed and then arranged between the transparent substrates. For example, an intermediate film containing composite surface-treated MWO fine particles and a resin film different from this may be laminated and sandwiched between transparent substrates to produce a laminated structure. Alternatively, a laminated structure may be produced by sandwiching an intermediate film between resin films and interposing this laminate between transparent substrates. As this resin film, an infrared absorbing layer containing surface-treated MWO fine particles can be used.

Specifically, an additive solution in which composite surface-treated MWO fine particles are dispersed in a plasticizer is added to an ionomer resin to prepare an intermediate film composition, and this intermediate film composition is formed into a sheet to produce an intermediate film. Then, for example, this intermediate film is laminated with another resin film that does not contain the composite surface-treated MWO fine particles, or is interposed between two layers of resin films that do not contain the composite surface-treated MWO fine particles, and these laminates may be sandwiched between two transparent substrates and bonded together to produce a laminated structure.
Instead of dispersing the composite surface-treated MWO fine particles in a plasticizer, a resin composition may be prepared by adding a dispersion liquid appropriately dispersed in a solvent to the ionomer resin and adding the plasticizer separately.
As a result, a laminated structure having high infrared shielding properties and a small haze value can be manufactured at a low production cost. According to this method, the adhesiveness between the resin film not containing the composite surface-treated MWO fine particles and the transparent substrate can be increased, so that the strength of the laminated structure is appropriately increased, which is preferable.

The laminated structure can be produced by sandwiching the above-described intermediate film between a plurality of transparent substrates and then bonding and integrating them by a known method. For example, the intermediate film may be sandwiched between two transparent substrates selected from glass substrates or resin substrates, and these substrates may be bonded together. Further, for example, when there are three or more transparent substrates, it is preferable to sandwich an intermediate film between the transparent substrates and bond them together. Further, for example, when there are three or more transparent substrates, it is preferable to sandwich an intermediate film between at least one of the transparent substrates, sandwich the other resin film described above between the other transparent substrates, and bond them together.

<Effects of this embodiment>
According to this embodiment, one or more of the following effects can be obtained.

(a) The laminated structure of this embodiment comprises an intermediate film between at least one of a plurality of transparent substrates. This intermediate film contains composite surface-treated MWO microparticles and an ionomer resin. The composite surface-treated MWO microparticles are composed of a hydrolysis product of a metal chelate compound, a polymer of a hydrolysis product of a metal chelate compound, a hydrolysis product of a metal cyclic oligomer compound, and a metal cyclic oligomer compound on the surface of the MWO microparticles. The surface-treated MWO microparticles provided with a coating film containing one or more selected from polymers of hydrolysis products are coated with a metal coupling agent. By coating the surface of a coating film formed using a metal chelate compound or the like with a metal coupling agent in this manner, the coating film can be formed to have a uniform thickness and be strong. As a result, for example, when the intermediate film is irradiated with ultraviolet rays to decompose the resin component and generate hydrogen radicals, the metal coupling agent can take over the valence change of the MWO fine particles due to the hydrogen radicals. Also, the hydrolysis products of the metal chelate compound and the metal cyclic oligomer compound can suppress the contact between the water permeated into the intermediate film and the MWO fine particles, thereby suppressing the decomposition of the MWO fine particles. This makes it possible to suppress variations in the valence of MWO fine particles and variations in light transmittance. Such composite surface-treated MWO fine particles are excellent in chemical stability and can maintain high weather resistance over a long period of time, so that the photocoloring phenomenon of the intermediate film can be suppressed.

Specifically, the interlayer film has a color difference ΔE of 1.5 or less before and after irradiation when irradiated with ultraviolet rays having an intensity of 100 mW/cm ² using a metal halide lamp as a light source in an environment of a temperature of 60 ° C. and a relative humidity of 35%. It is possible to suppress the photocoloring phenomenon due to long-term ultraviolet irradiation.

(b) In addition, since the intermediate film contains the composite surface-treated MWO fine particles, the solar transmittance can be reduced while maintaining a high visible light transmittance. Specifically, in the intermediate film, when the composite surface-treated MWO fine particles are added so that the visible light transmittance is 85%, the transmittance (solar transmittance) of light in the range of 300 nm to 2100 nm is reduced to 70%. High infrared absorption characteristics can be realized as follows.

(c) The metal chelate compound or metal cyclic oligomer compound preferably contains at least one metal element of Al, Zr, Ti, Si and Zn. According to such a compound, a coating film can be formed from a hydrolysis product containing these metal elements or a polymer thereof. As a result, the chemical stability of the composite surface-treated MWO fine particles can be further improved, and the photocoloring phenomenon in the intermediate film can be further suppressed.

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

(e) The metal coupling agent is preferably a silane coupling agent. The silane coupling agent allows the coating film to be formed with a higher density, and the coating film can be formed more firmly on the surface of the MWO microparticles. Thereby, the weather resistance of the composite surface-treated MWO fine particles can be further improved, and the photocoloring phenomenon in the intermediate film can be further suppressed.

(f) The content of the metal coupling agent in the composite surface-treated MWO microparticles is preferably 20 parts by weight or more per 100 parts by weight of the MWO microparticles. With such a content, the weather resistance of the composite surface-treated MWO fine particles can be further improved.

(g) MWO fine particles have the general formula M _x W _y O _z (where M is one selected from Cs, K, Rb, In, Tl, Ba, Li, Ca, Sr, Fe, Sn The above elements, W is tungsten, O is oxygen, and particles represented by 0.001 ≤ x/y ≤ 1, 2.0 ≤ z/y < 4.0) and have a hexagonal crystal structure is preferred. According to the MWO fine particles having such a composition and crystal structure, the effect (b) described above can be obtained more reliably.

(h) The ionomer resin is preferably an ethylene ionomer. The ethylene ionomer can improve the adhesion of the intermediate film to the transparent substrate.

(i) The intermediate film preferably contains a metal coupling agent. By adding a metal coupling agent together with the composite surface-treated MWO fine particles, the weather resistance of the intermediate film can be further improved. As a result, even when the laminated structure is exposed to strong ultraviolet rays for a long period of time, the occurrence of the photocoloring phenomenon can be greatly suppressed. In addition, a high transmittance of light in the visible region can be maintained, and deterioration of the appearance of the intermediate film and reduction in transparency can be suppressed.

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 gist of the present invention.

The present invention will be described below based on more detailed examples, but the present invention is not limited to these examples.

In this example, after obtaining composite surface-treated composite tungsten oxide fine particles by surface treatment, a laminated structure was produced using the fine particles and evaluated. A specific description will be given below.

<Example 1>
(1) Preparation of composite surface-treated composite tungsten oxide fine particles (preparation of fine particle dispersion)
First, as composite tungsten oxide fine particles, Cs _0.33 WO ₃ fine particles ("YM-01" manufactured by Sumitomo Metal Mining Co., Ltd.) containing 0.33 mol of Cs and 3 mol of O per 1 mol of W are prepared. bottom.

Subsequently, 28 parts by mass of Cs _0.33 WO ₃ fine particles and 72 parts by mass of pure water are mixed, and the resulting mixed solution is charged into a paint shaker containing φ0.3 mm ZrO ₂ beads and pulverized for 4 hours. Distributed processing.

The dispersed particle size of the Cs _0.33 WO ₃ fine particles dispersed in the mixed liquid was measured using a particle size measuring device based on the dynamic light scattering method (“ELS-8000” manufactured by Otsuka Electronics Co., Ltd.). By the way, it was 140 nm. At this time, as settings for particle size measurement, the particle refractive index was set to 1.81, and the particle shape was aspherical. Moreover, the background was measured using pure water, and the solvent refractive index was set to 1.33. In addition, after removing the solvent of the mixed solution, the Cs _0.33 WO ₃ fine particles were subjected to powder X-ray diffraction using a powder X-ray diffraction measurement device ("X'Pert-PRO/MPD" manufactured by PANalytical, Spectris Co., Ltd.). (θ-2θ method), the crystal system was hexagonal and the crystallite diameter was 28 nm.

Subsequently, pure water was added to the mixture to prepare a fine particle dispersion having a Cs _0.33 WO ₃ fine particle concentration of 14% by mass.

(Preparation of coating film-forming dispersion)
Prior to the surface treatment of the Cs _0.33 WO ₃ fine particles, a surface treatment liquid for forming a coating film was prepared. Table 1 below summarizes the preparation conditions of the surface treatment liquid. Specifically, a surface treatment liquid a was prepared by mixing 29.0 parts by mass of aluminum-based aluminum ethylacetoacetate diisopropylate as a metal chelate compound and 71.0 parts by mass of isopropyl alcohol (IPA). .

Subsequently, 550 g of the fine particle dispersion prepared above was placed in a beaker, and 307 g of the surface treatment liquid a was added dropwise over 6 hours while stirring with a stirrer to prepare a coating film forming dispersion. After the surface treatment liquid a was added dropwise, the coating film-forming dispersion liquid was further stirred at a temperature of 20° C. for 24 hours to obtain an aging liquid. Subsequently, the liquid medium was evaporated from the aging liquid by vacuum fluidized drying to obtain surface-treated Cs _0.33 WO ₃ fine particles in which a coating film was formed on the surfaces of the Cs _0.33 WO ₃ fine particles.

(Coating with metal coupling agent)
Subsequently, 10 parts by mass of surface-treated Cs _0.33 WO ₃ fine particles, 10 parts by mass of a dispersant, and 2.0 parts by mass of 3-(2-aminoethyl)aminopropyltrimethoxysilane as a metal coupling agent. parts and 78.0 parts by mass of butyl acetate as an organic solvent were mixed. The resulting mixed solution was charged into a paint shaker containing ZrO ₂ beads of φ0.3 mm and subjected to pulverization and dispersion treatment for 1 hour. As the dispersant, one having an amine-containing functional group and an acrylic main chain, an amine value of 48 mgKOH/g, and a decomposition temperature of 250° C. was used.

Subsequently, the pulverized and dispersed mixed liquid is introduced into a vacuum fluidized bed dryer, and the medium is evaporated to adhere the metal coupling agent onto the coating film of the surface-treated Cs _0.33 WO ₃ fine particles. The coating was further coated with a metal coupling agent. As a result, a dispersed powder containing composite surface-treated CWO fine particles in which surface-treated Cs _0.33 WO ₃ fine particles were coated with a metal coupling agent was obtained.
In the surface-treated Cs _0.33 WO ₃ fine particles contained in the obtained dispersed powder, the _content of the metal chelate compound with respect to 100 parts by mass of the Cs _0.33 WO 3 fine particles was 42.9 parts by mass in terms of the metal element. The content of the coupling agent was 28.6 parts by mass. The content of the metal chelate compound is a value measured by ICP emission spectroscopic analysis of aluminum, and the content of the metal coupling agent is a value measured by ICP emission spectroscopic analysis of silicon.

The composite surface-treated Cs _0.33 WO ₃ fine particles contained in the mixed solution were observed with a transmission electron microscope after removing the solvent, and the volume average particle diameter was measured to be 28 nm. Moreover, the thickness of the coating film was 2 nm. The volume average particle size of the composite surface-treated Cs _0.33 WO ₃ fine particles was calculated by measuring the particle size of 100 fine particles from the observation image of a transmission electron microscope (HF-2200 manufactured by Hitachi, Ltd.). bottom. In addition, the film thickness of the coating film was read as the coating film from the observed image of the composite tungsten oxide fine particles at a magnification of 300,000 times with no lattice fringes.

The conditions for preparing the composite surface-treated Cs _0.33 WO ₃ fine particles are summarized in Table 2 below.

(2) Preparation of intermediate film composition Subsequently, a composition for forming an intermediate film was prepared using the dispersion powder. Specifically, 0.8 parts by mass of the dispersed powder and 99.2 parts by mass of the ionomer resin were mixed to prepare the intermediate film composition of Example 1. As the ionomer resin, a pellet-shaped ethylene-based ionomer containing zinc as metal ions ("Himilan 1706" manufactured by Mitsui-DuPont Polychemicals Co., Ltd.) was used.

(3) Preparation of intermediate film and laminated structure Subsequently, the intermediate film composition of Example 1 was supplied to a twin-screw extruder set at 200 ° C. and kneaded, and then extruded from a T-die by a calendar roll method. The intermediate film of Example 1 was produced by molding into a sheet having a thickness of 2.3 mm.

In the intermediate film of Example 1, the content of the _{Cs0.33WO3 fine} particles was 0.21% by mass, and the content of the _{Cs0.33WO3 fine} particles was measured by ICP emission spectroscopy of tungsten. value.

Further, the interlayer film of Example 1 was temporarily sandwiched between two sheets of transparent float glass (thickness of 3 mm), heated to 130 ° C., and subjected to press treatment for 3 minutes under vacuum to obtain the laminated structure of Example 1. was made.

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

In addition, in the intermediate film of Example 2, the content of the Cs _0.33 WO ₃ fine particles was 0.21% by mass. In the dispersed powder according to Example 2, the content of the metal chelate compound was 42.9 parts by mass in terms of the metal element and the content of the metal coupling agent was 33.3 parts by mass with respect to 100 parts by mass of the Cs _0.33 WO ₃ fine particles. was parts by mass. Moreover, the thickness of the coating film was 2 nm.

(Example 3)
In Example 3, as shown in Table 2, in the coating with the metal coupling agent of Example 1, the added amount of 3-(2-aminoethyl)aminopropyltrimethoxysilane, which is the metal coupling agent, was changed to 2.0. Surface treatment was performed in the same manner as in Example 1, except that the content was changed from parts by mass to 3.0 parts by mass, and an intermediate film and a laminated structure were produced.

In addition, in the intermediate film of Example 3, the content of the Cs _0.33 WO ₃ fine particles was 0.21% by mass. In the dispersed powder according to Example 3, the content of the metal chelate compound was 42.9 parts by mass in terms of the metal element, and the content of the metal coupling agent was 42.9 parts by mass with respect to 100 parts by mass of the Cs _0.33 WO ₃ fine particles. was the department. Moreover, the thickness of the coating film was 2 nm.

(Example 4)
In Example 4, as shown in Table 2, in the preparation of the coating film-forming dispersion liquid of Example 1, the surface treatment liquid a shown in Table 1 was replaced with the surface treatment liquid b (aluminum ethylacetoacetate diisopropylate 32. 8 parts by mass and 67.2 parts by mass of IPA were prepared by mixing), surface treatment was performed in the same manner as in Example 1, and an intermediate film and a laminated structure were produced.

In addition, in the intermediate film of Example 4, the content of the Cs _0.33 WO ₃ fine particles was 0.21% by mass. In the dispersion powder according to Example 4, the content of the metal chelate compound was 57.1 parts by mass in terms of the metal element and the content of the metal coupling agent was 28.6 parts by mass with respect to 100 parts by mass of the Cs _0.33 WO ₃ fine particles. was the department. Moreover, the thickness of the coating film was 2 nm.

(Example 5)
In Example 5, as shown in Table 2, in the preparation of the coating film forming dispersion liquid of Example 2, 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 to produce an intermediate film and a laminated structure.

In addition, in the interlayer film of Example 5, the content of the Cs _0.33 WO ₃ fine particles was 0.21% by mass. In the dispersed powder according to Example 6, the content of the metal chelate compound was 57.1 parts by mass in terms of the metal element and the content of the metal coupling agent was 38.1 parts by mass with respect to 100 parts by mass of the Cs _0.33 WO ₃ fine particles. was the department. Moreover, the thickness of the coating film was 2 nm.

(Example 6)
In Example 6, as shown in Table 2, in the preparation of the coating film forming dispersion liquid of Example 3, 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 to produce an intermediate film and a laminated structure.

In addition, in the interlayer film of Example 6, the content of the Cs _0.33 WO ₃ fine particles was 0.21% by mass. In the dispersed powder according to Example 6, the content of the metal chelate compound was 57.1 parts by mass in terms of the metal element and the content of the metal coupling agent was 42.9 parts by mass with respect to 100 parts by mass of the Cs _0.33 WO ₃ fine particles. was the department. Moreover, the thickness of the coating film was 2 nm.

(Example 7)
In Example 7, as shown in Table 2, in the preparation of the coating film forming dispersion liquid of Example 1, the surface treatment liquid a shown in Table 1 was replaced with the surface treatment liquid c (aluminum ethylacetoacetate diisopropylate 36. 3 parts by mass and 63.7 parts by mass of IPA were prepared by mixing), surface treatment was performed in the same manner as in Example 1, and an intermediate film and a laminated structure were produced.

In addition, in the interlayer film of Example 7, the content of the Cs _0.33 WO ₃ fine particles was 0.21% by mass. In the dispersed powder according to Example 7, the content of the metal chelate compound was 61.9 parts by mass in terms of the metal element and the content of the metal coupling agent was 28.6 parts by mass with respect to 100 parts by mass of the Cs _0.33 WO ₃ fine particles. was the department. Moreover, the thickness of the coating film was 2 nm.

(Comparative example 1)
In Comparative Example 1, a dispersed powder containing composite tungsten oxide fine particles and a metal coupling agent was produced without performing composite surface treatment. Specifically, first, 10 parts by mass of each of the Cs _0.33 WO ₃ fine particles and the dispersant used in Example 1, and 3-(2-aminoethyl)aminopropyltrimethoxysilane, which is a metal coupling agent, were added. 2 parts by mass and 78 parts by mass of butyl acetate were mixed. Subsequently, the resulting mixed solution was loaded into a paint shaker containing φ0.3 mm ZrO ₂ beads, and subjected to pulverization and dispersion treatment for 1 hour to obtain a fine particle dispersion of Comparative Example 1. Subsequently, this fine particle dispersion was introduced into a vacuum fluidized bed dryer to evaporate the medium to obtain a dispersed powder containing Cs _0.33 WO ₃ fine particles. Subsequently, 0.7 parts by mass of this dispersed powder and 99.3 parts by mass of the ionomer resin were sufficiently mixed to prepare an intermediate film composition of Comparative Example 1. Finally, an intermediate film and a laminated structure were produced in the same manner as in Example 1 using this intermediate film composition.

In addition, in the interlayer film of Comparative Example 1, the content of the Cs _0.33 WO ₃ fine particles was 0.21% by mass. In the dispersion powder according to Comparative Example 1, the content of the metal coupling agent was 14.3 parts by mass with respect to 100 parts by mass of the Cs _0.33 WO ₃ fine particles.

(Comparative example 2)
In Comparative Example 2, the Cs _0.33 WO ₃ fine particles were only surface-treated with a metal chelate compound, and the surface-treated Cs _0.33 WO ₃ fine particles were added to the ionomer resin together with the metal coupling agent to form an intermediate film composition. An intermediate film and a laminated structure were produced in the same manner as in Example 1, except that the was prepared.

Specifically, first, 10 parts by mass of the surface-treated Cs _0.33 WO ₃ fine particles obtained in the preparation of the coating film-forming dispersion in Example 1, 10 parts by mass of the dispersant, and butyl acetate was mixed with 80 parts by mass. The resulting mixed solution was loaded into a paint shaker containing ZrO ₂ beads of φ0.3 mm and subjected to pulverization and dispersion treatment for 1 hour to obtain a mixed solution. Subsequently, the obtained mixed liquid was introduced into a vacuum fluidized bed dryer to evaporate the medium to obtain a dispersed powder containing surface-treated Cs _0.33 WO ₃ fine particles. Subsequently, 0.8 parts by mass of this dispersed powder, 99.14 parts by mass of the ionomer resin, and 0.06 parts by mass of 3-(2-aminoethyl)aminopropyltrimethoxysilane as a metal coupling agent. were thoroughly mixed to prepare an intermediate film composition of Comparative Example 2. Finally, an intermediate film and a laminated structure were produced in the same manner as in Example 1 using this intermediate film composition.

In addition, in the intermediate film of Comparative Example 2, the content of the Cs _0.33 WO ₃ fine particles was 0.21% by mass. In the dispersion powder according to Comparative Example 2, the content of the metal chelate compound was 42.9 parts by mass with respect to 100 parts by mass of the Cs _0.33 WO ₃ fine particles. Moreover, the thickness of the coating film was 2 nm.

<Evaluation method>
Visible light transmittance, solar transmittance and weather resistance of the laminated structures of Examples 1 to 7 and Comparative Examples 1 and 2 were evaluated by the following methods.

(visible light transmittance, solar transmittance)
Visible light transmittance (VLT) and solar transmittance (ST) of the laminated structure were measured according to ISO 9050 and JIS R 3106. Specifically, the transmittance was measured using a spectrophotometer (“U-4100” manufactured by Hitachi High-Tech Co., Ltd.) and calculated by multiplying by a coefficient corresponding to the spectrum of sunlight. The transmittance was measured at intervals of 5 nm over a wavelength range of 300 nm or more and 2100 nm or less.

(Weatherability)
The weather resistance of the laminated structure was evaluated based on the color difference ΔE between before and after the ultraviolet irradiation due to the photocoloring phenomenon when the interlayer film was irradiated with ultraviolet rays. Here, the color difference ΔE is obtained by calculating the tristimulus values X, Y, and Z for a D65 standard light source and a light source angle of 10° using the L*a*b* color index in accordance with JISZ8701, and from the tristimulus values in accordance with JISZ8729. and calculated. Specifically, the color difference ΔE was measured before and after irradiating the laminated structure with ultraviolet light having an intensity of 100 mW/cm ² with a metal halide lamp as a light source for 16 hours in an environment of a temperature of 60° C. and a relative humidity of 35%. The color difference ΔE was obtained from the difference in L*a*b* before and after irradiation with ultraviolet rays 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

In this example, when the visible light transmittance of the laminated structure is set to 85%, if the ΔE before and after the ultraviolet irradiation is 1.5 or less, the coloring is difficult to visually recognize, and the weather resistance is particularly excellent. I decided. When ΔE was more than 1.5 and less than 2.3, it was judged that there was a certain degree of weather resistance, although coloring could be visually recognized. If ΔE exceeds 2.3, the coloration can be easily recognized even by the naked eye of many people, and it was determined that the weather resistance is significantly inferior.

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

As shown in Table 3, the laminated structures of Examples and Comparative Examples had a visible light transmittance (VLT) of 85% before exposure and a solar transmittance (ST) of 65% or more before exposure. Therefore, it was confirmed to have good heat shielding properties.

On the other hand, with regard to weather resistance, in Examples 1 to 7, the color difference ΔE before and after ultraviolet irradiation is 1.5 or less, and high weather resistance can be achieved. In Comparative Example 2, it was 1.71, and it was confirmed that the weather resistance was poor.

In Comparative Example 1, the Cs _0.33 WO ₃ fine particles were not surface-treated, and a metal coupling agent was added to the intermediate film to allow the metal coupling agent to exist in the vicinity of the Cs _0.33 WO ₃ fine particles. Therefore, the photocoloring phenomenon could not be sufficiently suppressed.

Further, in Comparative Example 2, the surface of the Cs _0.33 WO ₃ fine particles was treated with a metal chelate compound, and a metal coupling agent was present in the film in the vicinity of the Cs _0.33 WO ₃ fine particles. Although the color difference ΔE was reduced more than in Example 1 and the photocoloring phenomenon was suppressed, it was insufficient.

On the other hand, in Examples 1 to 7, the surface of the Cs _0.33 WO ₃ fine particles was subjected to a complex surface treatment with a metal chelate compound and a metal coupling agent, and the hydrolysis product of the metal chelate compound or its polymerization was obtained. It was confirmed that by further coating the coating film formed from the material with a metal coupling agent, the coating film can be formed firmly and the photocoloring phenomenon can be further suppressed.

As described above, the chemical stability of composite tungsten oxide fine particles is improved by subjecting them to a surface treatment using a metal chelate compound or a metal cyclic oligomer compound and a surface treatment using a metal coupling agent. Weather resistance can be improved, and photocoloration caused by ultraviolet irradiation can be suppressed in the intermediate film.

<Preferred Embodiment of the Present Disclosure>
Preferred embodiments of the present disclosure will be added below.

(Appendix 1)
a plurality of transparent substrates;
and at least one intermediate film interposed between the plurality of transparent substrates,
In the intermediate film, the surface of the composite tungsten oxide fine particles is a hydrolysis product of a metal chelate compound, a polymer of a hydrolysis product of a metal chelate compound, a hydrolysis product of a metal cyclic oligomer compound, or a metal cyclic oligomer compound. Composite surface-treated composite tungsten oxide fine particles obtained by coating the surface-treated composite tungsten oxide fine particles coated with a coating film containing one or more selected from hydrolysis product polymers with a metal coupling agent, and an ionomer Formed from an intermediate film composition containing at least a resin,
alignment structure.

(Appendix 2)
In Supplementary Note 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.

(Appendix 3)
In Supplementary Note 1 or 2, preferably
The composite tungsten oxide fine particles have the general formula M _x W _y O _z (where M is 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.

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

(Appendix 5)
In any one of Appendices 1 to 4, preferably
The metal coupling agent is a silane coupling agent.

(Appendix 6)
In any one of Appendices 1 to 5, preferably
The content of the metal coupling agent in the composite surface-treated composite tungsten oxide fine particles is 20 parts by mass or more with respect to 100 parts by mass of the composite tungsten oxide fine particles.

(Appendix 7)
In any one of Appendices 1 to 6, preferably
The ionomer resin is an ethylene ionomer.

(Appendix 8)
In any one of Appendices 1 to 7, preferably
The transparent substrate is one or more selected from sheet glass and plastic.

(Appendix 9)
In Appendix 8, preferably
The plastic is one or more selected from polycarbonate resin, acrylic resin and polyethylene terephthalate resin.

(Appendix 10)
In any one of Appendices 1 to 9, preferably
Having one or more intermediate films,
The surface-treated composite tungsten oxide fine particles are dispersed in at least one of the intermediate films.

(Appendix 11)
In any one of Appendices 1 to 10, preferably
At least one infrared absorbing layer containing the surface-treated composite tungsten oxide fine particles is interposed between the transparent substrates together with the intermediate film.

Claims (11)

a plurality of transparent substrates;
and at least one intermediate film interposed between the plurality of transparent substrates,
In the intermediate film, the surface of the composite tungsten oxide fine particles is a hydrolysis product of a metal chelate compound, a polymer of a hydrolysis product of a metal chelate compound, a hydrolysis product of a metal cyclic oligomer compound, or a metal cyclic oligomer compound. Composite surface-treated composite tungsten oxide fine particles obtained by coating the surface-treated composite tungsten oxide fine particles coated with a coating film containing one or more selected from hydrolysis product polymers with a metal coupling agent, and an ionomer Formed from an intermediate film composition containing at least a resin,
alignment structure. The metal chelate compound or the metal cyclic oligomer compound contains one or more metal elements selected from Al, Zr, Ti, Si, and Zn.
A laminated structure according to claim 1. The composite tungsten oxide fine particles have the general formula M _x W _y O _z (where M is selected from Cs, K, Rb, In, Tl, Ba, Li, Ca, Sr, Fe, and Sn). More than one type of element, W is tungsten, O is oxygen, 0.001 ≤ x / y ≤ 1, 2.0 ≤ z / y < 4.0), and has a hexagonal crystal structure,
A laminated structure according to claim 1 or 2. The surface-treated composite tungsten oxide fine particles have a crystallite diameter of 1 nm to 800 nm.
A laminated structure according to any one of claims 1 to 3. The metal coupling agent is a silane coupling agent,
A laminated structure according to any one of claims 1 to 4. The content of the metal coupling agent in the composite surface-treated composite tungsten oxide fine particles is 20 parts by mass or more with respect to 100 parts by mass of the composite tungsten oxide fine particles.
A laminated structure according to any one of claims 1 to 5. The ionomer resin is an ethylene-based ionomer,
A laminated structure according to any one of claims 1-6. The transparent substrate is one or more selected from plate glass and plastic,
A laminated structure according to any one of claims 1-7. The plastic is one or more selected from polycarbonate resin, acrylic resin and polyethylene terephthalate resin,
A laminated structure according to claim 8. Having one or more intermediate films,
The surface-treated composite tungsten oxide fine particles are dispersed in at least one of the intermediate films,
A laminated structure according to any one of claims 1 to 9. Between the transparent substrates, an infrared absorbing layer containing the surface-treated infrared absorbing fine particles is interposed together with the intermediate film.
Laminated structure according to any one of claims 1 to 10.

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