WO2013146447A1

WO2013146447A1 - Silver-particle containing film and manufacturing method therefor, and heat ray shielding material

Info

Publication number: WO2013146447A1
Application number: PCT/JP2013/057753
Authority: WO
Inventors: 威史濱
Original assignee: 富士フイルム株式会社
Priority date: 2012-03-27
Filing date: 2013-03-19
Publication date: 2013-10-03
Also published as: JP2013228698A

Abstract

Provided is a silver-particle containing film in which the color tone in a L*a*b* color system is | a* | ≤ 2 and | b* | ≤ 2. The silver-particle containing film has a silver plate-shaped particle containing layer that contains plate-shaped silver nano-particles having an average circle equivalent diameter of 70-500nm, and is characterized in that the color tone in a L*a*b* color system is | a* | ≤ 2 and | b* | ≤ 2.

Description

Silver particle-containing film, method for producing the same, and heat ray shielding material

The present invention relates to a silver particle-containing film, a production method thereof, and a heat ray shielding material. More specifically, the present invention relates to a natural color silver particle-containing film and a method for producing the same, and a heat ray shielding material capable of reflecting infrared light using the silver particle-containing film.

Silver particle-containing films containing silver particles in the film plane are applied to various fields by taking advantage of the characteristics of silver.
As an application example of a silver particle-containing film, in recent years, as one of energy saving measures for reducing carbon dioxide, it has been known to apply to a heat ray shielding material for automobiles and windows of buildings. In the field of such a heat ray shielding material, from the viewpoint of heat ray shielding properties, re-radiation is more effective than a heat ray absorption type in which re-radiation of absorbed light into the room (about 1/3 of the absorbed solar radiation energy) is present. However, a heat ray reflective heat ray shielding material without re-radiation can be obtained by using a silver particle-containing film. For example, Patent Document 1 includes 60% by number or more of hexagonal or circular tabular silver particles, and the main plane of the hexagonal or circular tabular silver particles is one surface of the silver particle-containing film. A heat ray shielding material having a plane orientation in an average range of 0 ° to ± 30 ° is disclosed, and it is described that it has visible light transparency and can shield heat rays in the near infrared region. .

On the other hand, the heat ray shielding material is mainly used by sticking to a windshield of a car or a window glass for a building, and the heat ray shielding material having a large a * value or b * value in the L * a * b * color system. In this case, there is a problem that the scenery when looking out from the window is remarkably damaged and eye fatigue is likely to occur. In particular, the heat ray shielding material is required to have practical chromaticity adjustment of chromaticity and color balance from the viewpoint of ensuring visual safety and securing a natural field of view when pasted on the windshield of an automobile. There has been a demand for a heat ray shielding material having a natural (grayscale) color tone with a small b * value. To deal with such a problem, for example, Patent Document 2 discloses a color tone in the L * a * b * color system in a configuration containing at least an organic infrared absorbing dye such as diimonium or phthalocyanine and a transparent resin. Describes an example in which −3 ≦ a * ≦ 3 and −3 ≦ b * ≦ 3. However, in the heat ray shielding material using the silver particle-containing film, there was no example in which chromaticity was adjusted or an example in which suitable chromaticity was suggested.

JP 2011-118347 A JP 2002-138203 A

When this inventor examined the performance of the heat ray shielding material using the silver particle containing film | membrane of patent document 1, the color tone (a * value, b * value) in the L * a * b * color system of a heat ray shielding material. ), Both | a * | and | b * | were 2 or more, and were found to be slightly colored. Therefore, there has been a demand for a silver particle-containing film having a natural color tone that can be applied to the field of heat ray shielding materials.

The problem to be solved by the present invention is to provide a silver particle-containing film whose color tone in the L * a * b * color system is | a * | ≦ 2 and | b * | ≦ 2.

When the present inventor shakes the production method of the silver particle-containing film under various conditions and intensively examines the color tone of the resulting silver particle-containing film, the detailed mechanism is not clear, but the L * a * b * color system It was found that a silver particle-containing film having a color tone of | a * | ≦ 2 and | b * | ≦ 2 was obtained.

The present invention which is means for solving the above problems is as follows.
[1] A silver tabular grain-containing layer containing tabular silver nanoparticles having an average equivalent-circle diameter of 70 nm to 500 nm and having a color tone of L * a * b * color system | a * | ≦ 2 And a silver particle-containing film satisfying | b * | ≦ 2.
[2] The silver particle-containing film according to [1] preferably has a color tone of | a * | ≦ 1.5 and | b * | ≦ 1.5.
[3] including a step of preparing a silver nanoparticle dispersion from a silver seed crystal solution, the silver nitrate-containing solution being added to the silver seed crystal solution in an addition time of 5 minutes or more, and the addition of the silver nitrate-containing solution A method for producing a silver particle-containing film, comprising: adding a solution containing silver sulfite to a silver seed crystal solution; and controlling the pH of the silver nanoparticle dispersion after adding the solution containing silver sulfite to 8.0 or less.
[4] A silver particle-containing film produced by the method for producing a silver particle-containing film according to [3].
[5] A heat ray shielding material comprising the silver particle-containing film according to any one of [1], [2] and [4] as a heat ray reflective layer.
[6] In the heat ray shielding material according to [5], it is preferable that the tabular silver nanoparticles in the silver particle-containing film are hexagonal tabular silver nanoparticles.
[7] The heat ray shielding material according to [5] or [6] is such that a main plane of the tabular silver nanoparticles in the silver particle-containing film is on one surface of the silver tabular grain-containing layer. The plane orientation is preferably in the range of 0 ° to ± 30 ° on average.
[8] The heat ray shielding material according to any one of [5] to [7] preferably has a visible light transmittance of 65% or more.
[9] In the heat ray shielding material according to any one of [5] to [8], the silver tabular grain-containing layer in the silver particle-containing film is disposed on at least one surface of the substrate. preferable.
[10] In the heat ray shielding material according to any one of [5] to [9], the metal oxide particle-containing layer is on the side opposite to the surface on which the silver tabular grain-containing layer of the substrate is disposed. It is preferable to arrange on the surface.

According to the present invention, it is possible to provide a silver particle-containing film whose color tone in the L * a * b * color system is | a * | ≦ 2 and | b * | ≦ 2.

FIG. 1A is a schematic perspective view showing an example of the shape of tabular grains contained in the silver particle-containing film of the present invention, and shows circular tabular silver nanoparticles. FIG. 1B is a schematic perspective view showing an example of the shape of a tabular grain contained in the silver particle-containing film of the present invention, and shows hexagonal tabular silver nanoparticles. FIG. 2A is a schematic cross-sectional view showing the existence state of a silver tabular grain-containing layer containing tabular silver nanoparticles in the silver particle-containing film of the present invention, and is a silver tabular grain containing tabular silver nanoparticles The figure explaining the angle ((theta)) which the containing layer (parallel also with the plane of a base material) and the main plane (plane which determines circle equivalent diameter D) of hexagonal flat silver nanoparticles is shown. FIG. 2B is a schematic cross-sectional view showing the state of existence of a silver tabular grain-containing layer containing tabular silver nanoparticles in the silver particle-containing film of the present invention, wherein the silver grain-containing film of the silver tabular grain-containing layer is shown. It is a figure which shows the presence area | region of the silver nanoparticle in a depth direction. FIG. 2C is a schematic cross-sectional view showing an example of the presence state of a silver tabular grain-containing layer containing tabular silver nanoparticles in the silver particle-containing film of the present invention. FIG. 2D is a schematic cross-sectional view showing another example of the presence state of a silver tabular grain-containing layer containing tabular silver nanoparticles in the silver particle-containing film of the present invention. FIG. 2E is a schematic cross-sectional view showing another example of the existence state of the silver tabular grain-containing layer containing tabular silver nanoparticles in the silver particle-containing film of the present invention.

Hereinafter, the heat ray shielding material using the silver particle-containing film of the present invention and the silver particle-containing film of the present invention will be described in detail.
The description of the constituent elements described below may be made based on typical embodiments of the present invention, but the present invention is not limited to such embodiments. In the present specification, a numerical range represented by using “to” means a range including numerical values described before and after “to” as a lower limit value and an upper limit value.

[Silver particle-containing film, heat ray shielding material]
The silver particle-containing film of the present invention has a silver tabular grain-containing layer containing tabular silver nanoparticles having an average equivalent circle diameter of 70 nm to 500 nm, and the color tone is L * a * b * color system, | A * | ≦ 2 and | b * | ≦ 2.
Moreover, the heat ray shielding material of this invention is characterized by including the silver particle containing film | membrane of this invention as a heat ray reflective layer. In addition, the description of the following silver particle containing film | membrane of this invention and its preferable aspect are the same as the description and preferable aspect of the heat ray reflective layer in the heat ray shielding material of this invention.

<Characteristics of silver particle-containing film>
(Color tone)
In the silver particle-containing film of the present invention, the color tone in the L * a * b * color system is | a * | ≦ 2 and | b * | ≦ 2.
In the silver particle-containing film of the present invention, the color tone in the L * a * b * color system is preferably | a * | ≦ 1.5. In the silver particle-containing film of the present invention, the color tone in the L * a * b * color system is preferably | b * | ≦ 1.5. In the silver particle-containing film of the present invention, the color tone in the L * a * b * color system is more preferably | a * | ≦ 1.5 and | b * | ≦ 1.5.
In the silver particle-containing film of the present invention, it is particularly preferable that the color tone in the L * a * b * color system is | a * | ≦ 1.0. The silver particle-containing film of the present invention particularly preferably has a color tone in the L * a * b * color system of | b * | ≦ 1.0. In the silver particle-containing film of the present invention, the color tone in the L * a * b * color system is more preferably | a * | ≦ 1.5 and | b * | ≦ 1.5.

(Other characteristics)
The solar reflectance of the silver particle-containing film of the present invention preferably has a maximum value in the range of 800 nm to 2,500 nm (preferably 800 nm to 1,800 nm) from the viewpoint of increasing the efficiency of heat ray reflectance. .
The visible light transmittance of the silver particle-containing film of the present invention is preferably 60% or more, more preferably 65% or more, and particularly preferably 70% or more. When the visible light transmittance is less than 60%, for example, when used as automotive glass or building glass, the outside may be difficult to see.
The solar reflectance of the silver particle-containing film of the present invention is preferably 13% or more, more preferably 17% or more, and particularly preferably 20% or more.
The silver particle-containing film of the present invention preferably has a wavelength band having a reflectance of 25% or more over a wavelength band of 800 nm to 2,500 nm over 800 nm, over 1000 nm, more preferably over 1200 nm. Is particularly preferred.
The ultraviolet transmittance of the silver particle-containing film of the present invention is preferably 5% or less, and more preferably 2% or less. When the ultraviolet transmittance exceeds 5%, the color of the silver nanoparticle layer may change due to ultraviolet rays of sunlight.
The haze of the silver particle-containing film of the present invention is preferably 20% or less. When the haze exceeds 20%, it may be unfavorable in terms of safety, for example, when it is used as glass for automobiles or glass for buildings, it becomes difficult to see the outside.

<Configuration of silver particle-containing film>
The silver particle-containing film of the present invention has a silver tabular grain-containing layer containing tabular silver nanoparticles having an average equivalent-circle diameter of 70 nm to 500 nm, and if necessary, an adhesive layer, an ultraviolet absorbing layer, a base layer The aspect which has other layers, such as a material and a metal oxide particle content layer, is also preferable.

As the layer structure of the silver particle-containing film of the present invention, as shown in FIGS. 2A to 2E, there is a mode in which the silver tabular particle-containing layer 2 is present and the tabular silver nanoparticles 3 are unevenly distributed on the surface thereof. Can be mentioned. The silver particle-containing film of the present invention preferably has a polymer layer 1 as a substrate.
Hereinafter, the preferable aspect of the heat ray shielding material using the silver particle containing film | membrane of this invention and the silver particle containing film | membrane of this invention is demonstrated.

1. Silver tabular grain-containing layer The silver tabular grain-containing layer is not particularly limited except that it contains tabular silver nanoparticles having an average equivalent-circle diameter of 70 nm to 500 nm, and can be appropriately selected according to the purpose.

In the silver tabular grain-containing layer, when the thickness of the silver tabular grain-containing layer is d, 80% or more of the hexagonal silver nanoparticles are d / 2 from the surface of the silver tabular grain-containing layer. It is preferable that it exists in the range. The present invention is not limited to any theory, and the silver particle-containing film of the present invention is not limited to the following production method, but a specific polymer (preferably latex) is preferably used when producing the silver tabular grain-containing layer. ) Can be segregated on one surface of the silver tabular grain-containing layer.

1-1. Silver nanoparticles
The silver nanoparticles are not particularly limited as long as they have a flat plate shape with an average equivalent circle diameter of 70 nm to 500 nm, and can be appropriately selected according to the purpose.
In addition, it is preferable that one surface of the said silver tabular grain content layer is a flat plane. When the said silver tabular grain content layer of the silver particle containing film | membrane of this invention has a base material, it is preferable that it is a substantially horizontal surface with the surface of a base material. Here, the silver particle-containing film may or may not have the base material, and may or may not have a temporary support.

-1-2. Silver nanoparticles
The shape of the flat silver nanoparticles is a particle composed of two main planes (see FIGS. 1A and 1B), and the shape in the plane can be appropriately selected according to the purpose. Examples include a shape, a circular shape, and a triangular shape. Among these, in terms of high visible light transmittance, it is more preferably a hexagonal or more polygonal shape to a circular shape, particularly preferably a hexagonal shape or a circular shape, and more preferably a hexagonal shape. .
In the present specification, the hexagonal shape means a shape in which the number of sides having a length of 20% or more of the average equivalent circle diameter of tabular silver nanoparticles is 6 per silver tabular grain. . The same applies to other polygons. The hexagonal silver nanoparticles are not particularly limited as long as they are hexagonal when the silver nanoparticles are observed from above the main plane with a transmission electron microscope (TEM) or SEM, and are appropriately selected according to the purpose. For example, the hexagonal corner may be acute or dull, but the corner is preferably dull in that the absorption in the visible light region can be reduced. There is no restriction | limiting in particular as a grade of the dullness of an angle, According to the objective, it can select suitably.

Of the silver nanoparticles present in the silver tabular grain-containing layer, hexagonal tabular silver nanoparticles are preferably 60% by number or more, and 65% by number or more based on the total number of silver nanoparticles. Is more preferable, and 70% by number or more is more preferable. If the ratio of the hexagonal tabular silver nanoparticles is less than 60% by number, the visible light transmittance may be lowered.

The method for synthesizing the tabular silver nanoparticles is not particularly limited as long as it can synthesize tabular silver nanoparticles having a specific size (preferably hexagonal shape), and is appropriately selected depending on the purpose. Examples thereof include liquid phase methods such as chemical reduction method, photochemical reduction method, and electrochemical reduction method. Among these, a liquid phase method such as a chemical reduction method or a photochemical reduction method is particularly preferable in terms of shape and size controllability. After synthesizing hexagonal to triangular tabular silver nanoparticles, for example, by performing etching treatment with a dissolved species that dissolves silver such as nitric acid and sodium sulfite, aging treatment by heating, etc., hexagonal to triangular shape Hexagonal to circular tabular silver nanoparticles may be obtained by dulling the corners of the silver nanoparticles.

As a method for synthesizing the tabular silver nanoparticles, in addition to the above, after seed crystals are fixed on the surface of a transparent substrate such as a film or glass, the silver nanoparticles may be grown in a tabular form.

In the present invention, the method for controlling the color tone of the silver particle-containing film is not particularly limited, and can be achieved by, for example, synthesizing tabular silver nanoparticles under specific conditions during the production conditions of the silver particle-containing film. Can do. Although not bound by any theory, the silver nitrate addition time during the preparation of the silver nanoparticle dispersion from the seed crystal solution (if the scale during the preparation of the silver nanoparticle dispersion is the same condition, the silver nitrate addition rate In a specific range, or by adjusting the pH of the silver nanoparticle dispersion after addition of the silver sulfite precipitate mixture.
Specifically, it is preferably produced by the method for producing a silver particle-containing film of the present invention. That is, the method includes a step of preparing a silver nanoparticle dispersion from a silver seed crystal solution, and a silver nitrate-containing solution is added to the silver seed crystal solution for 5 minutes or more, preferably 7 minutes or more, more preferably 15 minutes or more. The solution containing silver sulfite is added to the silver seed crystal solution after the addition of the silver nitrate-containing solution, and the pH of the silver nanoparticle dispersion after the addition of the solution containing silver sulfite is 8.0 or less (preferably 3 It is preferably produced by a method for producing a silver particle-containing film, characterized in that it is controlled to ˜7.5, more preferably 4 to 7).
However, the silver particle-containing film of the present invention is not limited by the production method described above, and those produced by other methods are also included in the silver particle-containing film of the present invention.

In the silver particle-containing film of the present invention, the tabular silver nanoparticles may be subjected to further treatment in order to impart desired characteristics. The further treatment is not particularly limited and may be appropriately selected depending on the purpose. For example, the formation of a high refractive index shell layer, the addition of various additives such as a dispersant and an antioxidant may be included. Can be mentioned.

The flat silver nanoparticles may be coated with a high refractive index material having high visible light region transparency in order to further enhance the visible light region transparency.
As the high refractive index material is not particularly limited and may be appropriately selected depending on the purpose, for _example, TiO _x, BaTiO _3, ZnO, etc. SnO _2, ZrO _2, NbO _x and the like.

There is no restriction | limiting in particular as said coating method, According to the objective, it can select suitably, For example, Langmuir, 2000, 16 volumes, p. As reported in 2731-2735, a method of forming a TiO _x layer on the surface of silver nanoparticles by hydrolyzing tetrabutoxytitanium may be used.

In addition, when it is difficult to form a high refractive index metal oxide layer shell directly on the flat silver nanoparticles, after synthesizing the silver nanoparticles as described above, an appropriate SiO ₂ or polymer shell layer is formed. Further, the metal oxide layer may be formed on the shell layer. When TiO _x is used as the material for the high refractive index metal oxide layer, since TiO _x has photocatalytic activity, there is a concern that the matrix in which the silver nanoparticles are dispersed may be deteriorated. After forming the TiO _x layer on the nanoparticles, an SiO ₂ layer may be appropriately formed.

In the silver particle-containing film of the present invention, the tabular silver nanoparticles may contain an antioxidant such as mercaptotetrazole or ascorbic acid in order to prevent oxidation of metals such as silver constituting the tabular silver nanoparticles. It may be adsorbed. For the purpose of preventing oxidation, an oxidation sacrificial layer such as Ni may be formed on the surface of the silver nanoparticles. Further, it may be covered with a metal oxide film such as SiO ₂ for the purpose of blocking oxygen.

For the purpose of imparting dispersibility, the tabular silver nanoparticles are, for example, a quaternary ammonium salt, a low molecular weight dispersant containing at least one of N element, S element, and P element such as amines, and high molecular weight dispersion. You may add dispersing agents, such as an agent.

-1-2-1. Plane orientation
In the silver particle-containing film of the present invention, the hexagonal tabular silver nanoparticles are such that the main plane is one surface of the silver tabular particle-containing layer (if the silver particle-containing film has a substrate, the substrate surface ) Is preferably in the range of 0 ° to ± 30 ° on average, more preferably in the range of 0 ° to ± 20 ° on average, more preferably 0 ° to ± 10 on average. It is particularly preferable that the orientation is in the range of °.
The presence state of the silver nanoparticles is not particularly limited and may be appropriately selected according to the purpose. However, the silver nanoparticles are preferably arranged as shown in FIGS. 2D and 2E described later.

Here, FIGS. 2A to 2E are schematic cross-sectional views showing the existence state of the silver tabular grain-containing layer containing silver nanoparticles in the silver particle-containing film of the present invention. FIG. 2A is a diagram for explaining the angle (± θ) formed by the surface plane of the silver particle-containing film (the plane of the substrate 1 when a substrate is included) and the plane of the silver nanoparticles 3. FIG. 2B shows the existence region in the depth direction of the silver particle-containing film of the silver tabular grain-containing layer 2. 2C, FIG. 2D, and FIG. 2E show the presence state of the tabular silver nanoparticles 3 in the silver tabular grain-containing layer 2.
In FIG. 2A, the angle (± θ) formed between the surface of the substrate 1 and the like and the main plane of the tabular silver nanoparticles 3 or an extension line of the main plane corresponds to a predetermined range in the plane orientation. That is, the plane orientation refers to a state in which the tilt angle (± θ) shown in FIG. 2A is small when the cross section of the silver particle-containing film is observed. In particular, FIG. A state where the main plane of the particle 3 is in contact, that is, a state where θ is 0 ° is shown. When the plane orientation angle of the main plane of the tabular silver nanoparticles 3 with respect to the surface of the substrate 1, that is, θ in FIG. 2A exceeds ± 30 °, a predetermined wavelength of the silver particle-containing film (for example, the visible light region length) The reflectance in the near infrared light region (from the wavelength side) is reduced.

As an evaluation of whether the main plane of the tabular silver nanoparticles is plane-oriented with respect to one surface of the silver tabular grain-containing layer (or the base material surface when the silver particle-containing film has a substrate) There is no particular limitation, and it can be appropriately selected according to the purpose. For example, an appropriate cross-section slice is prepared, and a silver tabular grain-containing layer in this slice (if the silver particle-containing film has a substrate, the substrate ) And plate-like silver nanoparticles may be observed and evaluated. Specifically, a cross-section sample or a cross-section sample of the silver particle-containing film is prepared from the silver particle-containing film using a microtome or a focused ion beam (FIB), and this is used for various microscopes (for example, field emission scanning electrons). And a method of evaluating from an image obtained by observation using a microscope (FE-SEM, etc.).

In the silver particle-containing film, when the binder that covers the silver nanoparticles swells with water, the cross-section sample or the cross-section section is obtained by cutting a sample frozen in liquid nitrogen by a diamond cutter mounted on a microtome. A sample may be made. Moreover, when the binder which coat | covers a silver nanoparticle in a silver particle containing film | membrane does not swell with water, you may produce the said cross-section sample or a cross-section slice sample.

As an observation of the cross-section sample or cross-section sample prepared as described above, the sample is flat with respect to one surface of the silver tabular grain-containing layer in the sample (or the base material surface when the silver particle-containing film has a base). There is no particular limitation as long as it can confirm whether or not the main plane of the silver nanoparticles is plane-oriented, and can be appropriately selected according to the purpose. For example, FE-SEM, TEM, optical microscope, etc. The observations used are mentioned. In the case of the cross section sample, observation may be performed by FE-SEM, and in the case of the cross section sample, observation may be performed by TEM. When evaluating by FE-SEM, it is preferable to have a spatial resolution that can clearly determine the shape and inclination (± θ in FIG. 2A) of the silver nanoparticles.

-1-2-2. Variation coefficient of average particle size (average equivalent circle diameter) and average particle size (average equivalent circle diameter) particle size distribution-
The flat silver nanoparticles have an average particle diameter (average equivalent circle diameter) of 70 nm to 500 nm, preferably 100 nm to 400 nm. When the average particle diameter (average equivalent circle diameter) is less than 70 nm, the contribution of the absorption of the tabular silver nanoparticles becomes larger than the reflection, so that sufficient heat ray reflectivity may not be obtained, which exceeds 500 nm. And haze (scattering) becomes large, and transparency may be impaired.
Here, the average particle diameter (average equivalent circle diameter) is a main plane diameter (maximum length) of 200 tabular silver nanoparticles arbitrarily selected from images obtained by observing particles with a TEM. Mean value.
Two or more kinds of tabular silver nanoparticles having different average particle diameters (average equivalent circle diameters) can be contained in the silver tabular grain-containing layer. In this case, the average particle diameter of the tabular silver nanoparticles ( The average circle equivalent diameter) peak may have two or more.

The silver particle-containing film of the present invention preferably has a coefficient of variation of 13% or more in the particle size distribution of tabular silver nanoparticles. When the coefficient of variation is 13% or more, the reflection wavelength region of heat rays in the silver particle-containing film can be broadened, and infrared light can be reflected over a wide band, which is preferable.
On the other hand, the upper limit of the coefficient of variation in the particle size distribution of the tabular silver nanoparticles is preferably 200% or less, more preferably 150% or less, and particularly preferably 100% or less.
Here, the coefficient of variation in the particle size distribution of the silver nanoparticles is plotted, for example, by plotting the particle size distribution range of the 200 silver nanoparticles used for calculating the average value obtained as described above, and the standard deviation of the particle size distribution is It is the value (%) obtained by dividing the average value (average particle diameter (average equivalent circle diameter)) of the main plane diameter (maximum length) obtained as described above.

-1-2-3. aspect ratio-
The aspect ratio of the tabular silver nanoparticles is not particularly limited and may be appropriately selected depending on the intended purpose. However, the reflectance in the infrared light region having a wavelength of 800 nm to 2,500 nm is increased. 8 to 40 are preferable, and 10 to 35 are more preferable. When the aspect ratio is less than 8, the reflection wavelength becomes smaller than 800 nm, and when it exceeds 40, the reflection wavelength becomes longer than 1,800 nm and sufficient heat ray reflectivity may not be obtained.
The aspect ratio means a value obtained by dividing the average particle diameter (average equivalent circle diameter) of tabular silver nanoparticles by the average particle thickness of tabular silver nanoparticles. The average particle thickness corresponds to the distance between main planes of tabular silver nanoparticles, for example, as shown in FIGS. 1A and 1B, and was cut by an atomic force microscope (AFM) or a focused ion beam (FIB). It can be measured by observing the cross section of the particle by FE-SEM or TEM.
The method for measuring the average particle thickness is not particularly limited and may be appropriately selected depending on the intended purpose. For example, a particle dispersion containing silver nanoparticles is dropped on a glass substrate and dried to obtain particles 1 The method of measuring the thickness of an individual etc. is mentioned.
The thickness of the flat silver nanoparticles is preferably 5 to 20 nm.

-1-2-4. Existence range of silver nanoparticles
In the silver particle-containing film of the present invention, it is preferable that 80% by number or more of the hexagonal tabular silver nanoparticles are present in a range of d / 2 from the surface of the silver tabular particle-containing layer, d / 3 More preferably, 60% by number or more of the hexagonal tabular silver nanoparticles are exposed on one surface of the silver tabular grain-containing layer. That the tabular silver nanoparticles are present in the range of d / 2 from the surface of the silver tabular grain-containing layer means that at least a part of the tabular silver nanoparticles is in the range of d / 2 from the surface of the silver tabular grain-containing layer. Means included. That is, the tabular silver nanoparticles described in FIG. 2E in which some of the tabular silver nanoparticles protrude from the surface of the silver tabular grain-containing layer are also d / 2 from the surface of the silver tabular grain-containing layer. Treat as silver nanoparticles present in the range. In addition, FIG. 2E means that only a part of the thickness direction of each silver nanoparticle is buried in the silver tabular grain-containing layer, and each silver nanoparticle is stacked on the surface of the silver tabular grain-containing layer. Do not mean.
Further, that the tabular silver nanoparticles are exposed on one surface of the silver tabular grain-containing layer, a part of one surface of the tabular silver nanoparticles is from the surface of the silver tabular grain-containing layer. Also means that it protrudes.
Here, the presence distribution of silver nanoparticles in the silver tabular grain-containing layer can be measured, for example, from an image obtained by SEM observation of a cross-sectional sample of the silver particle-containing film.

The plasmon resonance wavelength λ of the metal constituting the tabular silver nanoparticles in the silver tabular grain-containing layer is not particularly limited and can be appropriately selected according to the purpose, but in terms of imparting heat ray reflection performance, The thickness is preferably 400 nm to 2,500 nm, and more preferably 700 nm to 2,500 nm from the viewpoint of imparting visible light transmittance.

-1-2-5. Medium of silver tabular grain containing layer
The silver particle-containing film of the present invention preferably contains a polymer as a medium in the silver tabular grain-containing layer.
There is no restriction | limiting in particular as said polymer, According to the objective, it can select suitably. Examples of the polymer include polyvinyl acetal resin, polyvinyl alcohol resin, polyvinyl butyral resin, polyacrylate resin, polymethyl methacrylate resin, polycarbonate resin, polyvinyl chloride resin, (saturated) polyester resin, polyurethane resin, gelatin resin and cellulose. And polymers such as natural polymers. Among them, in the present invention, the main polymer of the polymer is preferably a polyvinyl alcohol resin, a polyvinyl butyral resin, a polyvinyl chloride resin, a (saturated) polyester resin, a polyurethane resin, and preferably the polyester resin and the polyurethane resin. More preferably, 80% by number or more of hexagonal or circular silver nanoparticles are easily present in the range of d / 2 from the surface of the silver tabular grain-containing layer, and the polyester resin contains the silver particles of the present invention. This is particularly preferable from the viewpoint of further improving the cross-cut adhesion of the film.
Moreover, in this specification, the main polymer of the said polymer contained in the said silver tabular grain content layer means the polymer component which occupies 50 mass% or more of the polymer contained in the said silver tabular grain content layer.
In the silver particle-containing film of the present invention, the content of the polyester resin with respect to the tabular silver nanoparticles contained in the silver tabular particle-containing layer is preferably 1 to 10,000% by mass, and preferably 10 to 1000% by mass. More preferred is 20 to 500% by mass.
The refractive index n of the medium is preferably 1.4 to 1.7.
In the silver particle-containing film of the present invention, when the thickness of the hexagonal tabular silver nanoparticles is a, 80% by number or more of the hexagonal silver nanoparticles have a thickness of a / 10 or more. Preferably, the polymer is covered with a / 10 to 10a in the thickness direction, more preferably the polymer is covered with a / 8 to 4a, and particularly preferably a / 8 to 4a is covered with the polymer. Thus, since the hexagonal tabular silver nanoparticles are buried in the silver tabular grain-containing layer in a certain ratio or more, the rubbing resistance can be further increased. That is, the silver particle-containing film of the present invention is preferably in the embodiment of FIG. 2D rather than the embodiment of FIG. 2E.

-1-3. Layer structure of silver tabular grain containing layer
In the silver particle-containing film of the present invention, the silver nanoparticles are arranged in the form of a silver tabular grain-containing layer containing tabular silver nanoparticles, as shown in FIGS. 2A to 2E.
The silver tabular grain-containing layer may be composed of a single layer as shown in FIGS. 2A to 2E, or may be composed of a plurality of silver tabular grain-containing layers. When comprised with a several silver tabular grain content layer, it becomes possible to provide the shielding performance according to the wavelength range which wants to provide thermal insulation performance. When the silver tabular grain-containing layer is composed of a plurality of silver tabular grain-containing layers, the silver particle-containing film of the present invention contains at least the outermost silver tabular grain-containing layer in the outermost silver tabular grain-containing layer. When the thickness of the layer is d ′, 80% by number or more of the hexagonal to circular tabular silver nanoparticles are in the range of d ′ / 2 from the surface of the outermost silver tabular grain-containing layer. It is preferable to do.

-1-4. Thickness of silver tabular grain containing layer
The thickness of the silver tabular grain-containing layer is preferably 10 to 160 nm, and more preferably 20 to 80 nm. The thickness d of the silver tabular grain-containing layer is preferably a to 10a, more preferably 2a to 8a, where a is the thickness of the hexagonal to circular tabular silver nanoparticles. .

Here, the thickness of each layer of the silver tabular grain-containing layer can be measured, for example, from an image obtained by SEM observation of a cross-sectional sample of the silver particle-containing film.
Further, even when other layers such as an overcoat layer described later are provided on the silver tabular grain-containing layer of the silver particle-containing film, the boundary between the other layer and the silver tabular grain-containing layer is the same method. The thickness d of the silver tabular grain-containing layer can be determined. In addition, when coating on the said silver tabular grain content layer using the same kind of polymer as the polymer contained in the said silver tabular grain content layer, it is usually with the said silver tabular grain content layer by the image observed by SEM. The boundary can be discriminated, and the thickness d of the silver tabular grain-containing layer can be determined.

2. Base Material The silver particle-containing film of the present invention preferably has a base material.
The silver particle-containing film has a substrate on the surface opposite to the surface of the silver tabular particle-containing layer on which 60% by number or more of the hexagonal tabular silver nanoparticles are unevenly distributed. Is preferred.

The substrate is not particularly limited as long as it is an optically transparent substrate, and can be appropriately selected according to the purpose. For example, the substrate has a visible light transmittance of 70% or more, preferably 80% or more. And those with high transmittance in the near infrared region.
There is no restriction | limiting in particular about the shape, a structure, a magnitude | size, material, etc. as said base material, According to the objective, it can select suitably. Examples of the shape include a flat plate shape, and the structure may be a single layer structure or a laminated structure, and the size may be the size of the silver particle-containing film. It can be appropriately selected depending on the size.

The material of the base material used in the silver particle-containing film of the present invention is not particularly limited, but is preferably a polymer film. The polymer film is appropriately selected from various transparent plastic films depending on the situation. You can choose. Examples of the transparent plastic film include polyolefin resins such as polyethylene, polypropylene, poly-4-methylpentene-1 and polybutene-1, polyester resins such as polyethylene terephthalate and polyethylene naphthalate, polycarbonate resins, and polyvinyl chloride. Resin; Polyphenylene sulfide resin; Polyethersulfone resin; Polyethylene sulfide resin; Polyphenylene ether resin; Styrene resin; Acrylic resin; Polyamide resin; Polyimide resin; Cellulose resin such as cellulose acetate Film; or a laminated film thereof. Among these, a polyethylene terephthalate film is particularly preferable.

The thickness of the base film is not particularly limited and can be appropriately selected depending on the purpose of use of the solar shading film. Usually, the thickness is about 10 μm to 500 μm, preferably 12 μm to 300 μm, more preferably 16 μm to 125 μm. preferable.

3. Other layers-3-1. Adhesive layer
The silver particle-containing film of the present invention preferably has an adhesive layer. The adhesive layer may include an ultraviolet absorber.
The material that can be used for forming the adhesive layer is not particularly limited and may be appropriately selected depending on the intended purpose. For example, polyvinyl butyral (PVB) resin, acrylic resin, styrene / acrylic resin, urethane resin, polyester Examples thereof include resins and silicone resins. These may be used individually by 1 type and may use 2 or more types together. An adhesive layer made of these materials can be formed by coating.
Furthermore, an antistatic agent, a lubricant, an antiblocking agent and the like may be added to the adhesive layer.
The thickness of the adhesive layer is preferably 0.1 μm to 30 μm.
The adhesive layer is preferably formed by coating. For example, it can be laminated on the surface of the lower layer such as the base material, the metal particle-containing layer, or the ultraviolet absorbing layer. There is no limitation in particular as the coating method at this time, A well-known method can be used.
A film in which the pressure-sensitive adhesive is previously coated and dried on the release film is prepared, and the film is left in a dry state by laminating the pressure-sensitive adhesive surface of the film and the heat ray shielding material surface of the present invention. It is possible to laminate an adhesive layer. The laminating method at this time is not particularly limited, and a known method can be used.

-3-2. Hard coat layer
In order to add scratch resistance, it is also preferable to include a hard coat layer having hard coat properties. The hard coat layer can contain metal oxide particles.
There is no restriction | limiting in particular as said hard-coat layer, The kind and formation method can be selected suitably according to the objective, for example, acrylic resin, silicone resin, melamine resin, urethane resin, alkyd resin And thermosetting or photocurable resins such as fluorine-based resins. The thickness of the hard coat layer is not particularly limited and may be appropriately selected depending on the intended purpose, but is preferably 1 μm to 50 μm. When an antireflection layer and / or an antiglare layer are further formed on the hard coat layer, a functional film having antireflection properties and / or antiglare properties in addition to scratch resistance is preferably obtained. The hard coat layer may contain the metal oxide particles.

3-3. Overcoat layer
In the silver particle-containing film of the present invention, the silver particle-containing film of the present invention has a hexagonal shape to a circular shape in order to prevent oxidation and sulfidation of tabular silver nanoparticles due to mass transfer and to impart scratch resistance. You may have the overcoat layer closely_contact | adhered to the surface of the said silver tabular grain content layer in which the tabular silver nanoparticle is exposed. Moreover, you may have an overcoat layer between the said silver tabular grain content layer and the below-mentioned ultraviolet absorption layer. In the silver particle-containing film of the present invention, particularly when silver nanoparticles are unevenly distributed on the surface of the silver tabular particle-containing layer, the contamination of the manufacturing process due to the peeling of the silver nanoparticles is prevented, and the disorder of the silver nanoparticle arrangement during the coating of another layer An overcoat layer may be provided for prevention or the like.
The overcoat layer may contain an ultraviolet absorber.
The overcoat layer is not particularly limited and may be appropriately selected depending on the intended purpose.For example, the overcoat layer contains a binder, a matting agent, and a surfactant, and further contains other components as necessary. It becomes.
The binder is not particularly limited and may be appropriately selected depending on the purpose. For example, thermosetting of acrylic resin, silicone resin, melamine resin, urethane resin, alkyd resin, fluorine resin, etc. Mold or photo-curable resin.
The thickness of the overcoat layer is preferably 0.01 μm to 1,000 μm, more preferably 0.02 μm to 500 μm, particularly preferably 0.1 to 10 μm, and particularly preferably 0.2 to 5 μm.

The layer containing the ultraviolet absorber can be appropriately selected according to the purpose in addition to the overcoat layer, and may be an adhesive layer, or between the adhesive layer and the silver tabular grain-containing layer. It may be a layer. In any case, the ultraviolet absorber is preferably added to a layer disposed on the side irradiated with sunlight with respect to the silver tabular grain-containing layer.

The ultraviolet absorber is not particularly limited and may be appropriately selected depending on the purpose. For example, a benzophenone ultraviolet absorber, a benzotriazole ultraviolet absorber, a triazine ultraviolet absorber, a salicylate ultraviolet absorber, Examples include cyanoacrylate ultraviolet absorbers. These may be used individually by 1 type and may use 2 or more types together.

The benzophenone-based ultraviolet absorber is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include 2,4droxy-4-methoxy-5-sulfobenzophenone.

The benzotriazole ultraviolet absorber is not particularly limited and may be appropriately selected depending on the intended purpose. For example, 2- (5-chloro-2H-benzotriazol-2-yl) -4-methyl-6 -Tert-butylphenol (tinuvin 326), 2- (2-hydroxy-5-methylphenyl) benzotriazole, 2- (2-hydroxy-5-tertiarybutylphenyl) benzotriazole, 2- (2-hydroxy-3- 5-ditertiary butylphenyl) -5-chlorobenzotriazole and the like.

The triazine ultraviolet absorber is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include mono (hydroxyphenyl) triazine compounds, bis (hydroxyphenyl) triazine compounds, and tris (hydroxyphenyl) triazine compounds. Etc.
Examples of the mono (hydroxyphenyl) triazine compound include 2- [4-[(2-hydroxy-3-dodecyloxypropyl) oxy] -2-hydroxyphenyl] -4,6-bis (2,4-dimethyl). Phenyl) -1,3,5-triazine, 2- [4-[(2-hydroxy-3-tridecyloxypropyl) oxy] -2-hydroxyphenyl] -4,6-bis (2,4-dimethylphenyl) ) -1,3,5-triazine, 2- (2,4-dihydroxyphenyl) -4,6-bis (2,4-dimethylphenyl) -1,3,5-triazine, 2- (2-hydroxy- 4-isooctyloxyphenyl) -4,6-bis (2,4-dimethylphenyl) -1,3,5-triazine, 2- (2-hydroxy-4-dodecyloxyphenyl) -4,6-bis ( 2,4-dimethylphenyl) -1,3,5-triazine, etc. Is mentioned. Examples of the bis (hydroxyphenyl) triazine compound include 2,4-bis (2-hydroxy-4-propyloxyphenyl) -6- (2,4-dimethylphenyl) -1,3,5-triazine, 2 , 4-Bis (2-hydroxy-3-methyl-4-propyloxyphenyl) -6- (4-methylphenyl) -1,3,5-triazine, 2,4-bis (2-hydroxy-3-methyl) -4-hexyloxyphenyl) -6- (2,4-dimethylphenyl) -1,3,5-triazine, 2-phenyl-4,6-bis [2-hydroxy-4- [3- (methoxyheptaethoxy ) -2-hydroxypropyloxy] phenyl] -1,3,5-triazine and the like. Examples of the tris (hydroxyphenyl) triazine compound include 2,4-bis (2-hydroxy-4-butoxyphenyl) -6- (2,4-dibutoxyphenyl) -1,3,5-triazine, 2 , 4,6-Tris (2-hydroxy-4-octyloxyphenyl) -1,3,5-triazine, 2,4,6-tris [2-hydroxy-4- (3-butoxy-2-hydroxypropyloxy) ) Phenyl] -1,3,5-triazine, 2,4-bis [2-hydroxy-4- [1- (isooctyloxycarbonyl) ethoxy] phenyl] -6- (2,4-dihydroxyphenyl) -1 , 3,5-triazine, 2,4,6-tris [2-hydroxy-4- [1- (isooctyloxycarbonyl) ethoxy] phenyl] -1,3,5-triazine, 2,4-bis [2 -Hydroxy-4- [1- (isooctyloxy) Carbonyl) ethoxy] phenyl] -6- [2,4-bis [1- (iso-octyloxy) ethoxy] phenyl] -1,3,5-triazine.

The salicylate-based ultraviolet absorber is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include phenyl salicylate, p-tert-butylphenyl salicylate, p-octylphenyl salicylate, Examples include 2-ethylhexyl salicylate.

The cyanoacrylate-based ultraviolet absorber is not particularly limited and may be appropriately selected depending on the intended purpose. For example, 2-ethylhexyl-2-cyano-3,3-diphenylacrylate, ethyl-2-cyano-3 , 3-diphenyl acrylate and the like.

The binder is not particularly limited and may be appropriately selected depending on the intended purpose, but preferably has higher visible light transparency and higher solar transparency, and examples thereof include acrylic resin, polyvinyl butyral, and polyvinyl alcohol. . Note that when the binder absorbs heat rays, the reflection effect of the silver nanoparticles is weakened. Therefore, the ultraviolet absorbing layer formed between the heat ray source and the silver nanoparticles is absorbed in the region of 450 nm to 1,500 nm. It is preferable to select a material that does not have a thickness, or to reduce the thickness of the ultraviolet absorbing layer.
The ultraviolet transmittance is preferably 5% or less, and more preferably 2% or less. When the ultraviolet transmittance exceeds 5%, the color of the silver nanoparticle layer may change due to ultraviolet rays of sunlight.

-3-4. Metal oxide particle-containing layer
The silver particle-containing film of the present invention preferably contains at least one metal oxide particle in order to absorb long-wave infrared light from the viewpoint of the balance between heat ray shielding and manufacturing cost. In the silver particle-containing film of the present invention, the layer containing the metal oxide particles is the silver flat plate on which the hexagonal to circular flat plate silver nanoparticles of the silver flat plate particle-containing layer are exposed. It is preferable to have on the surface side opposite to the surface of the particle-containing layer. In this case, for example, the overcoat layer preferably contains metal oxide particles. On the other hand, the said metal oxide particle content layer may be laminated | stacked in this order as a layer different from an overcoat layer through a base material. With such a configuration, when the silver particle-containing film of the present invention is arranged so that the silver nanoparticle-containing layer is on the incident direction side of heat rays such as sunlight, a part of the heat rays in the silver nanoparticle-containing layer After reflecting (or all), the overcoat layer will absorb part of the heat rays, and it will not be absorbed by the metal oxide-containing layer, but will be caused by the heat rays that have passed through the silver particle-containing film. The amount of heat directly received inside the film and the amount of heat absorbed by the metal oxide-containing layer of the silver particle-containing film and indirectly transmitted to the inside of the silver particle-containing film can be reduced.
There is no restriction | limiting in particular as a material of the said metal oxide particle, According to the objective, it can select suitably, For example, a tin dope indium oxide (henceforth "ITO"), a tin dope antimony oxide (henceforth). , Abbreviated as “ATO”), zinc oxide, titanium oxide, indium oxide, tin oxide, antimony oxide, glass ceramics, tungsten oxide (hereinafter abbreviated as “CWO”), lanthanum hexaboride (LaB ₆ ) Etc. Among these, ITO, ATO, zinc oxide, CWO, lanthanum hexaboride (which is excellent in heat ray absorption ability and can produce a silver particle-containing film having a wide range of heat ray absorption ability when combined with tabular silver nanoparticles ( LaB ₆ ) is more preferable, and ITO is particularly preferable in that infrared rays of 1,200 nm or more are shielded by 90% or more and the visible light transmittance is 90% or more.
The volume average particle size of the primary particles of the metal oxide particles is preferably 0.1 μm or less in order not to reduce the visible light transmittance.
There is no restriction | limiting in particular as a shape of the said metal oxide particle, According to the objective, it can select suitably, For example, spherical shape, needle shape, plate shape, etc. are mentioned.

The content of the metal oxide particles in the metal oxide particle-containing layer is not particularly limited and may be appropriately selected depending on the purpose, but is preferably 0.1 g / m ² to 20 g / m ² , 0.5 g / m ² to 10 g / m ² is more preferable, and 1.0 g / m ² to 4.0 g / m ² is more preferable.
If the content is less than 0.1 g / m ² , the amount of solar radiation felt on the skin may increase, and if it exceeds 20 g / m ² , the visible light transmittance may deteriorate. On the other hand, when the content is 1.0 g / m ² to 4.0 g / m ^2, it is advantageous in that the above two points can be avoided.
The content of the metal oxide particles in the metal oxide particle-containing layer is, for example, from the observation of the super foil section TEM image and surface SEM image of the heat ray shielding layer, and the number of metal oxide particles in a certain area and It can be calculated by measuring the average particle diameter and dividing the mass (g) calculated based on the number and average particle diameter and the specific gravity of the metal oxide particles by the constant area (m ² ). . Further, metal oxide fine particles in a certain area of the metal oxide particle-containing layer are eluted in methanol, and the mass (g) of the metal oxide fine particles measured by fluorescent X-ray measurement is divided by the constant area (m ² ). This can also be calculated.

<Method for producing silver particle-containing film>
There is no restriction | limiting in particular as a manufacturing method of the silver particle containing film | membrane of this invention, According to the objective, it can select suitably, For example, the said silver tabular grain containing layer, the said ultraviolet-ray by the coating method on the surface of the said base material Examples thereof include a method of forming an absorption layer and, if necessary, other layers.

There is no restriction | limiting in particular as a formation method of the silver tabular grain content layer of this invention, According to the objective, it can select suitably, For example, the dispersion | distribution which has the said silver nanoparticle on the surface of lower layers, such as the said base material Examples include a method in which the liquid is applied by a dip coater, a die coater, a slit coater, a bar coater, a gravure coater, or the like, and a method in which the liquid is aligned by a method such as an LB film method, a self-assembly method, or a spray coating method. When the silver particle-containing film of the present invention is produced, the composition of the silver tabular particle-containing layer used in the examples described later is used, and the hexagonal or circular tabular silver nanoparticles 80 are added by adding latex or the like. It is preferable that several% or more exist in a range of d / 2 from the surface of the silver tabular grain-containing layer. More preferably, 80% by number or more of the hexagonal or circular tabular silver nanoparticles are present in a range of d / 3 from the surface of the silver tabular grain-containing layer. The amount of the latex added is not particularly limited. For example, it is preferably added in an amount of 1 to 10,000% by mass, more preferably 10 to 1000% by mass, and more preferably 20 to 500% by mass with respect to silver tabular grains. It is particularly preferred.
In addition, in order to accelerate | stimulate plane orientation, after apply | coating a silver nanoparticle, you may promote by passing through pressure-bonding rollers, such as a calender roller and a laminating roller.

In the present invention, the method for controlling the coefficient of variation of the average particle diameter (average equivalent circle diameter) of tabular silver nanoparticles in the silver tabular grain-containing layer is not particularly limited, and the average particle diameter (average equivalent circle diameter) The shape of the flat silver nanoparticles contained in the dispersion containing silver nanoparticles may be controlled so that the coefficient of variation is large, and the silver nanoparticles with a small coefficient of variation of the average particle diameter (average equivalent circle diameter) You may control by mixing 2 or more types of dispersion liquid which has.
In the present invention, when the silver tabular grain-containing layer contains two or more kinds of tabular silver nanoparticles having different average grain sizes (average equivalent circle diameter), the variation coefficient of the average grain size (average equivalent circle diameter) is Prepare two or more kinds of small silver nanoparticle dispersions (average equivalent circle equivalent diameters) so that the average particle diameter (average equivalent circle diameter) of tabular silver nanoparticles has two or more peaks. It is preferable to form a silver tabular grain-containing layer. Such a configuration is preferable because infrared light can be easily shielded over a wide band.
On the other hand, in the present invention, when the silver tabular grain-containing layer contains one kind of tabular silver nanoparticles having an average grain diameter (average equivalent circle diameter), the coefficient of variation of the average grain diameter (average equivalent circle diameter) is It is preferable to prepare such that the silver tabular grain-containing layer is prepared by increasing the average equivalent circle diameter (not so uniform). Such a configuration is preferable because infrared light can be easily shielded over a wide band.

[Production of window glass with heat ray shielding material]
When using the heat ray shielding material of the present invention to provide functionality to the existing window glass, it is preferable to laminate an adhesive and attach it to the indoor side of the window glass. In that case, it is preferable that the infrared reflection layer is installed on the sunlight side as much as possible because it can reflect the infrared rays to be incident on the room in advance. From this viewpoint, the metal particle-containing layer is installed on the sunlight incidence side. It is preferable to laminate an adhesive layer on the substrate. Specifically, an adhesive layer is provided on a metal particle-containing layer or a functional layer such as an overcoat layer provided on the metal particle-containing layer, and is bonded to the window glass via the adhesive layer. Is preferred. When sticking the heat ray shielding material to the window glass, prepare a heat ray shielding material provided by coating or laminating the adhesive layer, and pre-surfactant (mainly on the surface of the window glass and the adhesion layer surface of the heat ray shielding material) After spraying an aqueous solution containing a nonionic system, it is preferable to install a heat ray shielding material on the window glass through an adhesive layer. Until the moisture evaporates, the adhesive force of the adhesive layer decreases, so that the position of the heat ray shielding material can be adjusted on the glass surface. After the position where the heat ray shielding material is attached to the window glass, the surface of the window glass is swept away from the center of the glass toward the edge using a squeegee or the like to leave moisture between the window glass and the heat ray shielding material. The heat ray shielding material is fixed to the surface. In this way, it is possible to install the heat ray shielding material on the window glass.

[Production of laminated glass body using heat ray shielding material]
For the production of the laminated glass body, two glass plates, two polyvinyl butyral interlayer films (PVB sheet) for laminated glass, and the heat ray shielding material are prepared, and the glass plate (first sheet), PVB sheet (1 Sheet), heat ray shielding material, PVB sheet (second sheet), glass plate (second sheet). This laminated body is preliminarily pressure-bonded at 95 ° C. for 30 minutes under vacuum, and then pressure-bonded with heating under conditions of 1.3 MPa and 120 ° C. in an autoflavor to obtain a laminated glass to which a heat ray shielding material is applied. be able to.

<Application>
The silver particle-containing film of the present invention can be applied to various fields by taking advantage of the characteristics of silver. For example, heat ray shielding materials, antibacterial materials, transparent conductive materials, antistatic materials, packaging materials, heat dissipation materials From the viewpoint of utilizing the natural color tone that is a feature of the silver particle-containing film of the present invention, it can be preferably used for a heat ray shielding material, a transparent conductive material, an antistatic material, and the like.
Among them, the silver particle-containing film of the present invention can be preferably used for a heat ray shielding material used for selectively reflecting or absorbing heat rays (near infrared rays). For example, films for vehicles, films for building materials, agriculture Films for use. Among these, a film for vehicles (preferably for automobiles, more preferably for automobile windshields) or a film for building materials (preferably for windows) is preferable from the viewpoint of energy saving effect.
In the present invention, heat rays (near infrared rays) mean near infrared rays (780 nm to 1,800 nm) contained in sunlight by about 50%.

The features of the present invention will be described more specifically with reference to the following examples.
The materials, amounts used, ratios, processing details, processing procedures, and the like shown in the following examples can be changed as appropriate without departing from the spirit of the present invention. Therefore, the scope of the present invention should not be construed as being limited by the specific examples shown below.

[Example 1]
<Synthesis of hexagonal tabular silver tabular grains>
(Preparation of seed crystal solution)
2.5 ml of a 0.5 g / l polystyrene sulfonic acid aqueous solution was added to 50 mL of a 2.5 mM sodium citrate aqueous solution and heated to 35 ° C. To this solution, 3 ml of 10 mM sodium borohydride aqueous solution was added, and 50 ml of 0.5 mM silver nitrate aqueous solution was added with stirring at 20 ml / min. This solution was stirred for 30 minutes to prepare a seed crystal solution.

(Preparation of silver nanoparticle dispersion)
The reaction kettle was charged with 132.7 ml of a 2.5 mM sodium citrate aqueous solution, 87.1 ml of ion-exchanged water was added, and the mixture was heated to 35 ° C. 2 ml of 10 mM ascorbic acid aqueous solution is added to the above solution in the reaction kettle, 42.4 ml of the seed crystal solution is added, and 79.6 ml of 0.5 mM silver nitrate aqueous solution is 2 ml / min (addition time 39.8 minutes). With stirring. After stirring for 30 minutes, 71.1 ml of a 0.35M potassium hydroquinonesulfonate aqueous solution was added to the reaction kettle, and 200 g of a 7 mass% gelatin aqueous solution was added to the reaction kettle. To the above solution in the reaction vessel was added a silver sulfite precipitate mixture (white silver sulfite precipitate mixture formed by mixing 107 ml of a 0.25 M aqueous sodium sulfite solution and 107 ml of a 0.47 M aqueous silver nitrate solution). . The solution pH immediately after the addition of the silver sulfite precipitate mixture was 5.6. This was stirred for 300 minutes to obtain a silver nanoparticle dispersion liquid A1.
Table 1 below shows the silver nitrate addition rate and the pH of the silver nanoparticle dispersion immediately after the addition of the silver sulfite precipitate mixture during the preparation of the silver nanoparticle dispersion from the seed crystal solution.
200 mL of the silver nanoparticle dispersion A1 was extracted, and centrifuged at 7000 rpm for 60 minutes with a centrifuge (H200-N manufactured by Kokusan Co., Ltd.) to precipitate silver nanoparticles. 190 mL of the supernatant after centrifugation was discarded, 90 mL of 0.2 mM NaOH aqueous solution was added, and the mixture was dispersed at 15000 rpm for 20 minutes with a desktop homogenizer (Mitsui Denki Seiki Co., Ltd., SpinMix08), whereby silver nanoparticle dispersion B1 Was prepared.

<Evaluation of hexagonal tabular silver tabular grains>
In this silver nanoparticle dispersion A1, silver hexagonal tabular grains (hereinafter referred to as hexagonal tabular silver tabular grains) having an average equivalent circular diameter of 230 nm and an average grain thickness of 16 nm are mainly generated. It confirmed according to the evaluation method. Regarding the silver nanoparticle dispersion B1, the result was almost the same as that of the silver nanodispersion A1.
Below, the method which evaluated various characteristics about the obtained silver nano tabular grain in a silver nanoparticle dispersion liquid is shown. Moreover, among the evaluated results, Table 1 shows the measurement results of the shape of the silver nanoparticles and the average equivalent circle diameter.

-Shape of silver nanoparticles-
The shape uniformity of silver nanoparticles is the shape of 200 particles arbitrarily extracted from the observed SEM image, and hexagonal silver tabular grains, circular silver tabular grains, and irregular shaped grains such as teardrops. Image analysis was performed while distinguishing them from each other, and shapes containing 60% by number or more were obtained.

-Average circle equivalent diameter of hexagonal silver tabular grains-
Images obtained by TEM observation for the dispersions of the silver nanoparticle dispersions A1 and B1 were taken into image processing software ImageJ and subjected to image processing. Image analysis was performed on 500 particles arbitrarily extracted from TEM images of several fields of view, and the equivalent circle diameter was calculated. As a result of statistical processing based on these populations, both A1 and B1 had an average diameter of 230 nm.

-Average particle thickness-
The silver tabular grain dispersion B1 was dropped on a silicon substrate and dried, and the individual thickness of the silver tabular grains was measured by the FIB-TEM method. Five silver tabular grains in the silver tabular grain dispersion B were measured, and the average thickness was 16 nm. As a result of calculating the average thickness for other examples and comparative examples by the same method, it was confirmed that the average thickness was 8 nm to 16 nm.

-aspect ratio-
From the average equivalent circle diameter and the average grain thickness of the obtained hexagonal silver tabular grains, the average equivalent circle diameter was divided by the average grain thickness to calculate the aspect ratio of the hexagonal silver tabular grains.

<Preparation of silver tabular grain containing layer>
Add 0.75 ml of 1N NaOH to 16 ml of silver tabular grain dispersion, add 24 ml of ion-exchanged water, and centrifuge at 5,000 rpm for 5 minutes using a centrifuge (Hokusan H-200N, Amble Rotor BN). Then, hexagonal tabular silver tabular grains were precipitated. The supernatant liquid after centrifugation was discarded, 5 ml of water was added, and the precipitated hexagonal tabular silver tabular grains were redispersed. 1.6 ml of 2% by weight of the following W-1 aqueous methanol solution (water: methanol = 1: 1 (mass ratio)) was added to this dispersion to prepare a coating solution.
Compound W-1

This coating liquid is applied to the wire coating bar No. 14 (RDS Webster NY Co., Ltd.) was applied onto a 50 μm thick PET film (A4300, manufactured by Toyobo Co., Ltd.), dried, and a hexagonal flat plate on the surface. A film having a silver tabular grain-containing layer having a dry thickness of 100 nm to which silver tabular grains were fixed was obtained. Thus, a silver particle-containing film having a tabular silver particle-containing layer was produced.

<Production of heat ray shielding material>
Next, an ITO hard coat coating solution (EI-1 manufactured by Mitsubishi Materials Co., Ltd.) is formed on the back surface of the PET film on which the silver tabular grain-containing layer is formed, so that the dry film thickness becomes 1.5 μm. Application bar No. 10 (manufactured by R.D.S. Webster NY) was used to obtain a heat ray shielding material of Example 1.

[Example 2]
A heat ray shielding material of Example 2 was obtained in the same manner as Example 1 except that 79.6 ml of 0.5 mM silver nitrate aqueous solution was added with stirring at 5 ml / min (addition time 15.9 minutes).

[Example 3]
A heat ray shielding material of Example 3 was obtained in the same manner as in Example 1 except that 79.6 ml of 0.5 mM silver nitrate aqueous solution was added with stirring at 10 ml / min (addition time: 8.0 minutes).

[Example 4]
After adding the silver sulfite precipitate mixed solution, immediately after adding 0.2 M NaOH aqueous solution, the pH of the silver nanoparticle dispersion was adjusted to 5.9. A shielding material was obtained.

[Example 5]
After adding the silver sulfite precipitate mixed solution, immediately after adding 0.2M NaOH aqueous solution, the pH of the silver nanoparticle dispersion was adjusted to 6.5, the heat ray of Example 5 A shielding material was obtained.

[Example 6]
After adding the silver sulfite precipitate mixed solution, immediately after adding 0.2 M NaOH aqueous solution, the pH of the silver nanoparticle dispersion liquid was set to 7.1. A shielding material was obtained.

[Example 7]
To 12.5 L of pure water, 995 mL of a 1% by mass aqueous sodium citrate solution and 678 mL of an 8 g / L aqueous sodium polystyrene sulfonate solution were added and heated to 35 ° C. To this solution, 40.7 mL of a 2.3 mass% sodium borohydride aqueous solution was added, and 10.8 L of a 0.5 mM aqueous silver nitrate solution was added with stirring. After stirring this solution for 20 minutes, 995 mL of 1 mass% sodium citrate aqueous solution, 1.34 L of 10 mM ascorbic acid aqueous solution and 12.5 L of pure water were added. Furthermore, 8.1 L of 0.5 mM silver nitrate aqueous solution was added with stirring at 1600 mL / min (addition time 5.1 minutes). After stirring for 30 minutes, 8.0 L of a 0.35 M potassium hydroquinonesulfonate aqueous solution and a gelatin aqueous solution in which 1.5 kg of inert gelatin having an average molecular weight of 200,000 was dissolved in 13.1 L of pure water were added to the reaction kettle. Next, a white precipitate mixed solution of silver sulfite obtained by mixing 2.7 L of 13.5% sodium sulfite aqueous solution 9.3 L, 10% silver nitrate aqueous solution 9.3 L and pure water 15.0 L was added to the reaction kettle in advance. . After stirring this solution for 300 minutes, 5.7 L of 1N NaOH and 181 mL of 2% by mass of 1- (5-methylureidophenyl) -5-mercaptotetrazole mercaptotetrazole aqueous solution were added, and silver nanoparticle dispersion A2 Got. Next, a silver nanoparticle dispersion liquid B2 was produced in the same manner as in Example 1. In these silver nanoparticle dispersions A2 and B2, the average equivalent circle diameter was calculated in the same manner as in Example 1 to produce silver hexagonal tabular grains (hereinafter referred to as Ag hexagonal tabular grains) having an average equivalent circle diameter of 125 nm. I confirmed that
A coating solution C2 for a metal particle-containing layer having the composition shown below was prepared using the silver nanoparticle dispersion B2.
Moreover, the coating liquid C3 for metal oxide particle content layers of the composition shown below was prepared. The heat ray shielding material was produced by forming and applying these to the equipment. In addition, the solid content concentration in the following preparations was used after appropriately adjusting with pure water or a water-soluble alcohol such as methanol or ethanol.

Composition of coating liquid C2 for metal particle-containing layer:
Polyester aqueous solution: Pluscoat Z687
(Saiyo Chemical Co., Ltd., solid concentration 25% by mass) 1.85 parts by mass Crosslinker A: Carbodilite V-02-L2
(Nisshinbo Co., Ltd., solid concentration 20% by mass) 1.15 parts by mass Crosslinking agent B: Epocross K-2020E
(Nippon Shokubai Co., Ltd., solid content concentration 20% by mass) 0.51 parts by mass Surfactant A: F Ripar 8780P Ripar 870P
(Lion Corporation, solid content 1% by mass) 0.96 parts by mass Surfactant B: Naroacty CL-95
(Manufactured by Sanyo Chemical Industries, Ltd., solid content 1 mass%) 1.18 parts by mass Silver nanoparticle dispersion B1 32.75 parts by mass 1- (m-methylureidophenyl) -5-mercaptotetrazole (Wako Pure Chemical ( Co., Ltd., solid content 2% by mass) 0.62 parts by mass Water 30.97 parts by mass Methanol 30 parts by mass

Composition of coating liquid O1 for overcoat layer:
Colloidal silica fine particles: Snowtex XL
(Average particle size 40 nm, manufactured by Nissan Chemical Industries, Ltd., solid content 10% by mass)
1.29 parts by mass of colloidal silica fine particles: Aerosil OX-50
(Average particle size 40 nm, manufactured by Nippon Aerosil Co., Ltd.,
(Preparing an aqueous dispersion having a solid content of 10% by mass) 0.29 parts by mass Acrylic polymer aqueous dispersion: AS563A
(Daicel Finechem Co., Ltd., solid content 27.5% by mass)
0.49 parts by mass carnauba wax: cellosol 524 (manufactured by Chukyo Yushi Co., Ltd., solid content 3% by mass)
2.86 parts by weight cross-linking agent: Carbodilite V-02-L2
(Nisshinbo Chemical Co., Ltd., solid concentration 20% by mass) 1.71 parts by mass Surfactant A: Ripar 870P (Lion Corporation, solid content 1% by mass)
2.32 parts by mass Surfactant B: NAROACTY CL-95
(Manufactured by Sanyo Chemical Industries, Ltd., solid content 1% by mass) 3.22 parts by mass urethane polymer aqueous solution: Olester UD350
(Mitsui Chemicals, Inc., solid content 38% by mass) 4.14 parts by mass water 83.68 parts by mass

Composition of coating liquid C3 for the metal oxide particle-containing layer:
UV-curable ITO coating PI-3 (Mitsubishi Materials Electronics Chemical Co., Ltd.) 25 parts by mass Toluene (Wako Pure Chemical Industries, Ltd.) 75 parts by mass

On the surface of a PET film (Toyobo Co., Ltd. A4300, thickness: 75 μm), a coating solution C2 for a metal particle-containing layer was applied using a wire bar so that the average thickness after drying was 80 nm. Then, it heated at 130 degreeC for 1 minute, dried and solidified, and formed the metal particle content layer.
Next, the overcoat layer coating solution O1 was applied using a wire bar so that the average thickness after drying was 350 nm. Then, it dried and solidified at 130 degreeC and formed the overcoat layer.
Next, on the back surface of the formed metal particle-containing layer, that is, the surface on which the coating liquid C2 for the PET film is not applied, the coating liquid C3 for the metal oxide particle-containing layer is averaged after drying using a wire bar. It was applied so that the thickness was 1.5 μm. Next, the metal oxide particle-containing layer was cured by irradiating with ultraviolet rays using a high-pressure mercury lamp. The coating layer was irradiated with ultraviolet rays at 400 mJ / cm ² .
The adhesive layer was provided with the method mentioned later with respect to the obtained heat ray shielding film.
The average thickness can be calculated by observing cross sections SEM and TEM of the heat ray shielding film. It selects suitably according to application | coating thickness. In this example, cross-section processing and cross-section observation were performed by FIB-TEM, and the average value obtained by measuring the thickness of the coating film at 10 points was defined as the film thickness. In addition, cross-section processing can be performed by mechanical polishing, ion milling, microtome, or the like.
An adhesive was bonded to the surface of the overcoat layer of the obtained heat ray shielding film. PD-S1 (manufactured by Panac) was used as the adhesive layer, and the surface from which one release sheet was peeled was bonded to the overcoat layer. The obtained heat ray shielding material was used as the heat ray shielding material of Example 7.

[Example 8]
A heat ray shielding material of Example 8 was obtained in the same manner as Example 7 except that 8.1 L of 0.5 mM silver nitrate aqueous solution was added with stirring at 1000 mL / min (addition time 8.1 minutes).

[Example 9]
A heat ray shielding material of Example 9 was produced in the same manner as Example 7 except that 8.1 L of 0.5 mM silver nitrate aqueous solution was added with stirring at 405 mL / min (addition time: 20 minutes).

[Example 10]
After adding the silver sulfite precipitate mixed solution, immediately after adding 0.2 M NaOH aqueous solution, the pH of the silver nanoparticle dispersion liquid was changed to 7.2. A shielding material was obtained.

[Comparative Example 1]
A heat ray shielding material of Comparative Example 1 was obtained in the same manner as in Example 1 except that 79.6 ml of 0.5 mM silver nitrate aqueous solution was added with stirring at 20 ml / min (addition time: 4.0 minutes).

[Comparative Example 2]
A heat ray shielding material of Comparative Example 2 was obtained in the same manner as in Example 1 except that 79.6 ml of 0.5 mM silver nitrate aqueous solution was added with stirring at 50 ml / min (addition time 1.6 minutes).

[Comparative Example 3]
A heat ray shielding material of Comparative Example 3 was obtained in the same manner as in Example 1 except that 79.6 ml of 0.5 mM silver nitrate aqueous solution was added with stirring at 100 ml / min (addition time 0.8 minutes).

[Comparative Example 4]
After adding the silver sulfite precipitate mixture, immediately after adding 0.2 M NaOH aqueous solution, the pH of the silver nanoparticle dispersion was 8.5, the heat ray of Comparative Example 4 A shielding material was obtained.

[Comparative Example 5]
After adding the silver sulfite precipitate mixed solution, immediately after adding 0.2 M NaOH aqueous solution, the pH of the silver nanoparticle dispersion was adjusted to 9.5. A shielding material was obtained.

[Comparative Example 6]
After adding the silver sulfite precipitate mixed solution, immediately after adding 0.2 M NaOH aqueous solution, the pH of the silver nanoparticle dispersion was changed to 10.1, the heat ray of Comparative Example 6 A shielding material was obtained.

[Comparative Example 7]
A heat ray shielding material of Comparative Example 7 was obtained in the same manner as in Example 7 except that 8.1 L of 0.5 mM aqueous silver nitrate solution was added with stirring at 2000 mL / min (addition time 4.1 minutes).

[Comparative Example 8]
A heat ray shielding material of Comparative Example 8 was obtained in the same manner as in Example 7 except that 8.1 L of 0.5 mM aqueous silver nitrate solution was added with stirring at 4000 mL / min (addition time: 2.0 minutes).

[Comparative Example 9]
After adding the silver sulfite precipitate mixed solution, immediately after adding 0.2 M NaOH aqueous solution, the pH of the silver nanoparticle dispersion was adjusted to 8.3. A shielding material was obtained.

[Comparative Example 10]
After adding the silver sulfite precipitate mixed solution, immediately after adding 0.2 M NaOH aqueous solution, the pH of the silver nanoparticle dispersion was changed to 9.7. A shielding material was obtained.

<Evaluation of heat ray shielding material>
The heat ray shielding material obtained in each Example and Comparative Example was evaluated.

-Color tone-
About the obtained heat ray shielding material, the color tone in the L * a * b * color system was measured using a spectrocolorimeter (CM-700d, manufactured by Konica Minolta). From the results, L *, a *, and b * values were calculated and listed in Table 1 below. When measuring the color tone, the Macbeth color chart “Color Checker CLASSIC” No. 24 Black was used as a base, and the metal oxide particle-containing layer was placed in contact with the base, and color tone measurement was performed.

-optical properties-
The other release sheet of the obtained heat ray shielding film was peeled off, and the optical properties were evaluated in a state of being bonded to a float glass having a thickness of 3 mm.

(Optical property evaluation)
The visible light transmittance and the shielding coefficient of the heat ray shielding material can be changed depending on the coating amount when forming the metal particle-containing layer. In each example and each comparative example, a large number of heat ray shielding materials were prepared by changing the coating amount of the coating liquid C1 for the metal particle-containing layer containing the metal tabular particle-containing liquid of each example and comparative example, The visible light transmittance and the shielding coefficient were calculated by the method.

Measuring method of visible light transmittance and shielding coefficient:
The transmission spectrum and reflection spectrum of the heat ray shielding material prepared in each example and comparative example were measured using an ultraviolet-visible-near infrared spectrometer (manufactured by JASCO Corporation, V-670, using an integrating sphere unit), and JIS R3106, JIS A5759. The visible light transmittance and shielding coefficient were calculated according to the above.

(1) Visible light transmittance For each heat ray shielding material, the transmittance of each wavelength measured from 380 nm to 780 nm was calculated by correcting the transmittance with the spectral visibility of each wavelength.
(2) Measuring method of shielding coefficient Each heat ray shielding material was calculated from the transmittance of each wavelength measured from 300 nm to 2500 nm based on the method described in JISA5759.

-Visible light transmittance at a shielding factor of 0.680-
A graph plotting the relationship between the visible light transmittance and the shielding coefficient based on the obtained visible light transmittance and the shielding coefficient, with the x-axis being the visible light transmittance (unit%) and the y-axis being the shielding coefficient (no unit). It was created.
The plot was approximated to a linear curve (straight line), and the obtained linear curve was extrapolated to obtain the visible light transmittance value (unit%) at a certain shielding coefficient. In the present specification, the visible light transmittance at a shielding coefficient of 0.680 was used for evaluation of optical characteristics.
The obtained results are shown in Table 1 below. “Visible light transmittance” in the following table represents the visible light transmittance at a shielding coefficient of 0.680.

From the results of Table 1 above, it was found that the heat ray shielding material of the present invention had a color tone of | a * | ≦ 2 and | b * | ≦ 2 in the L * a * b * color system.
On the other hand, the heat ray shielding material of each comparative example has a color tone in the L * a * b * color system of | a * |> 2 or | b * |> 2, and when the landscape is observed through the heat ray shielding material It has been found that the scenery of is significantly damaged.

-Radio wave transmission-
When the heat ray shielding materials obtained in each of the examples and comparative examples were measured using the KEC method at the Tokyo Metropolitan Industrial Technology Center, both had a shielding effect of 5 dB or less, and thus were judged to have radio wave permeability.

-Particle tilt angle-
After embedding the heat ray shielding material obtained in each Example and Comparative Example with an epoxy resin, it was cleaved with a razor in a frozen state with liquid nitrogen to prepare a vertical cross-sectional sample of the heat ray shielding material. This vertical cross-sectional sample was observed with a scanning electron microscope (SEM), and the average value of the inclination angle (corresponding to ± θ in FIG. 2A) of the 100 silver nanoparticles with respect to the horizontal plane of the substrate was calculated. In all cases, the tilt angle was ± 30 ° or less.

[Production of window glass with heat ray shielding material]
An aqueous solution containing the film construction liquid Real Perfect (manufactured by Lintec Corporation) is sprayed on the surface of the window glass and the adhesive layer surface of the heat ray shielding material of Examples 7 to 10 having the adhesive layer, and then the window is passed through the adhesive layer. A heat-shielding material was installed on the glass. After the position where the heat ray shielding material is attached to the window glass is determined, the water remaining between the window glass and the heat ray shielding material is swept out from the center of the glass toward the edge using a squeegee. A heat ray shielding material was fixed. Thus, it was confirmed that the heat ray shielding materials of Examples 7 to 10 having an adhesive layer on the window glass could be installed.

[Production of laminated glass body using heat ray shielding material]
Two glass plates, two polyvinyl butyral interlayer films (PVB sheets) for laminated glass, and heat ray shielding materials for each example were prepared. A glass plate (first sheet), a PVB sheet (first sheet), and heat rays A shielding material, a PVB sheet (second sheet), and a glass plate (second sheet) were stacked in this order to obtain a laminate. This laminate is pre-pressed under vacuum at 95 ° C. for 30 minutes, and then heat-shielded in the autoflave under conditions of 1.3 MPa and 120 ° C. to apply the heat ray shielding material of each example. It was confirmed that the laminated glass can be obtained.

The silver particle-containing film of the present invention is excellent in color tone, for example, when a landscape is observed through the silver particle-containing film when pasted on a window or the like as a film for a vehicle or a building material such as a car or a bus. Natural (grayscale) color tone is obtained and eye strain is low. Since the silver particle-containing film of the present invention has the above-mentioned characteristics, it is attached to a window or the like as various members that are required to prevent transmission of heat rays, for example, as a film for a vehicle such as an automobile or a bus or a film for a building material. It can be suitably used as a heat ray shielding material.

1 base material 2 silver tabular grain content layer (heat ray reflective layer)
3 Flat silver nanoparticles D Diameter L Thickness f (λ) Grain existing region thickness

Claims

A silver tabular grain-containing layer containing tabular silver nanoparticles having an average equivalent-circle diameter of 70 nm to 500 nm;
A silver particle-containing film having a color tone of | a * | ≦ 2 and | b * | ≦ 2 in the L * a * b * color system.
The silver particle-containing film according to claim 1, wherein the color tone is | a * | ≦ 1.5 and | b * | ≦ 1.5.
Preparing a silver nanoparticle dispersion from a silver seed crystal solution,
Adding a silver nitrate-containing solution to the silver seed crystal solution for an addition time of 5 minutes or more;
Add a solution containing silver sulfite to the silver seed crystal solution after adding the silver nitrate-containing solution,
A method for producing a silver particle-containing film, wherein the pH of the silver nanoparticle dispersion liquid after the addition of the solution containing silver sulfite is controlled to 8.0 or less.
A silver particle-containing film produced by the method for producing a silver particle-containing film according to claim 3.
A heat ray shielding material comprising the silver particle-containing film according to any one of claims 1, 2, and 4 as a heat ray reflective layer.
The heat ray shielding material according to claim 5, wherein the tabular silver nanoparticles in the silver particle-containing film are hexagonal tabular silver nanoparticles.
The main plane of the tabular silver nanoparticles in the silver particle-containing film is plane-oriented in an average range of 0 ° to ± 30 ° with respect to one surface of the silver tabular grain-containing layer. The heat ray shielding material according to claim 5 or 6.
The heat ray shielding material according to any one of claims 5 to 7, wherein the visible light transmittance is 65% or more.
The heat ray shielding material according to any one of claims 5 to 8, wherein the silver tabular grain-containing layer in the silver particle-containing film is disposed on at least one surface of the substrate.
10. The metal oxide particle-containing layer is disposed on a surface of the substrate opposite to a surface on which the silver tabular particle-containing layer is disposed. The heat ray shielding material described in 1.