JP7131083B2 - Silver nanoparticle laminate and method for producing the same - Google Patents

Description

TECHNICAL FIELD The present invention relates to a silver nanoparticle laminate and a method for producing the same.

Silver nanoparticles have electrical, thermal, and optical properties not found in other materials, and are used in a wide range of products from solar cells to sensors. In addition, unlike many other dyes and pigments, silver nanoparticles are very efficient at absorbing and scattering light and have a color depending on the size and shape of the particles. The strong relationship between light and silver nanoparticles is called surface plasmon resonance, and is due to the collective oscillation of conduction electrons on the metal surface when excited by light of a specific wavelength, resulting in unusual scattering and responsible for absorption properties.

Generally, a coating liquid in which metallic silver is dispersed is often used for metal wiring. For example, a pattern is formed on a wiring substrate with a coating liquid in which metallic silver is dispersed, and wiring is formed by sintering the metallic silver contained in the coating liquid. It is known that when metallic silver is used as a conductive material, it is necessary to sinter at a low temperature by utilizing the melting point depression due to the miniaturization of dispersed metallic silver. At present, miniaturized nano-sized metal nanoparticles are expected as materials that can be sintered at low temperatures.

However, metallic silver particles so small as to exhibit melting point depression tend to contact each other and agglomerate. In order to prevent this aggregation, it is necessary to add a dispersant to the coating liquid described above, but the addition of the dispersant inhibits the surface plasmon resonance peculiar to the metal nanoparticles and adversely affects the peculiar color development. may affect In addition, in order to produce a functional film having optical properties peculiar to silver nanoparticles, it is necessary to use a coating liquid with good dispersibility and to form a silver film that does not sinter at low temperatures. Plasmon resonance by the above-mentioned metal nanostructures has made remarkable progress in both basic and applied fields. When silver nanoparticle two-dimensional crystal sheets are stacked on a metal substrate, the color of orange, red, pink, and purple changes depending on the number of layers. Vivid coloration is obtained (Patent Document 1).

Conventionally, when trying to obtain silver nanoparticles, an aqueous solution in which a silver salt such as silver nitrate or silver chloride is dissolved is generally used, and the existing silver ions are reduced with some reducing agent to obtain the desired form of the metal salt. It was common to precipitate as (Patent Documents 2 to 4). In addition, particularly in the production of fine silver particles, a method of aggregating atomic silver in a vacuum to form silver nanoparticles is also known (Patent Document 5).

Also known is a method of mixing silver oxalate and amine and thermally decomposing the mixture to produce silver nanoparticles via a silver oxalate amine complex (Patent Documents 6 and 7). According to this technique, silver atoms generated by dissociation from the raw material compound do not pass through the state of silver ions in the process of forming silver nanoparticles. Therefore, with the above method, there is no need to mix a reducing agent for reducing silver ions, and silver fine particles having a uniform average particle size can be produced by a simple method. Furthermore, upon decomposition of the amine complex, the amino group of the amine molecule is coordinated to the surface of the silver particles, resulting in silver nanoparticles that are dispersible in certain organic solvents without the addition of a dispersant.

Japanese Patent No. 6091417 Japanese Patent Publication No. 2012-509396 JP 2012-180589 A JP 2012-140701 A JP-A-2002-121437 JP 2012-162767 A Japanese Patent No. 5574761

However, when a compound that is cured by ionizing radiation is added to a silver nanoparticle dispersion, which is a coating liquid in which silver nanoparticles are dispersed, only a yellow-brown coating layer is obtained. When a silver nanoparticle laminate (silver nanoparticle laminate film) is formed by coating, there is a problem that the variation of possible colors is reduced.
The present invention has been made in view of the above circumstances, and even when only the silver nanoparticle dispersion is applied, the coating film color can be changed according to the purpose, that is, there are variations in colors that can be colored. An object of the present invention is to provide a rich silver nanoparticle laminate and a method for producing the same.

In order to solve the above problems, a silver nanoparticle laminate according to an aspect of the present invention includes a silver nanoparticle laminate film containing silver nanoparticles on a substrate, and is included in the silver nanoparticle laminate film. At least part of the silver nanoparticles are aggregated in layers along the surface of the silver nanoparticle laminate film on the surface layer of the silver nanoparticle laminate film, and the substrate side of the silver nanoparticle laminate film is present. to color
In addition, a method for producing a silver nanoparticle laminate according to one aspect of the present invention includes a step of forming a silver nanoparticle-containing layer containing silver nanoparticles on a substrate; and forming a silver nanoparticle layer having a higher particle density of the silver nanoparticles than the silver nanoparticle-containing layer.

According to the present invention, even when a silver nanoparticle laminate (silver nanoparticle laminate film) is formed by applying only a silver nanoparticle dispersion, the coating film color can be changed according to the purpose, that is, coloration. It is possible to provide a silver nanoparticle laminate with a wide variety of possible colors and a method for producing the same.

BRIEF DESCRIPTION OF THE DRAWINGS It is sectional drawing which shows typically the structure of the silver nanoparticle laminated body which concerns on embodiment of this invention. FIG. 2 is a cross-sectional view schematically showing the dispersed state of silver nanoparticles in the silver nanoparticle laminate film according to the embodiment of the present invention. It is a figure which shows typically the manufacturing process of the silver nanoparticle laminated body which concerns on embodiment of this invention. It is a figure which shows the absorption spectrum in the silver nanoparticle laminated film which concerns on embodiment of this invention. 1 is a view showing a scanning electron microscope image of silver nanoparticles observed after a toluene solvent dispersion of silver nanoparticles obtained in Example 1 of the present invention was applied to a substrate and dried. FIG. 1 is a diagram showing the particle size distribution and cumulative frequency (%) of silver nanoparticles obtained in Example 1 of the present invention; FIG. It is a figure which shows the absorption spectrum of the cured film obtained by Example 1, 2, and 3 of this invention. It is a figure which shows the absorption spectrum of the cured film obtained by Example 4, 6, 7 of this invention. FIG. 4 is a diagram showing absorption spectra of cured films obtained in Examples 9, 10 and 11 of the present invention. It is a figure which shows the absorption spectrum of the cured film obtained by the comparative examples 1 and 2 of this invention. FIG. 4 is a diagram showing a scanning electron microscope (STEM) image of silver nanoparticles contained in a silver nanoparticle-containing layer according to Example 4 of the present invention; FIG. 10 is a scanning electron microscope (STEM) image of silver nanoparticles contained in a silver nanoparticle-containing layer according to Example 6 of the present invention. FIG. 10 is a view showing a scanning electron microscope (STEM) image of silver nanoparticles contained in a silver nanoparticle-containing layer according to Example 7 of the present invention;

Hereinafter, a silver nanoparticle laminate and a method for producing the silver nanoparticle laminate according to an embodiment of the present invention will be described with reference to the drawings. Here, the drawings are schematic, and the relationship between the thickness and the planar dimension, the ratio of the thickness of each layer, and the like are different from the actual ones. Further, each embodiment shown below is an example of a configuration for embodying the technical idea of the present invention. It is not specific to the following. Various modifications can be made to the technical idea of the present invention within the technical scope defined by the claims.

(Configuration of silver nanoparticle laminate 7)
FIG. 1 is a cross-sectional view schematically showing the structure of a silver nanoparticle laminate 7 according to the first embodiment of the invention. The silver nanoparticle laminate 7 shown in FIG. 1 includes a substrate 1 and a silver nanoparticle laminate film 6 formed on the substrate 1 and containing silver nanoparticles 4 . At least part of the silver nanoparticles 4 contained in the silver nanoparticle laminated film 6 are aggregated in a layer along the surface of the silver nanoparticle laminated film 6 on the surface layer of the silver nanoparticle laminated film 6 . Moreover, the substrate 1 side of the silver nanoparticle laminated film 6 is colored.

(Structure of Silver Nanoparticle Laminated Film 6)
The silver nanoparticle laminated film 6 shown in FIG. and at least a silver nanoparticle layer 5 formed on the particle-containing layer 3 and containing silver nanoparticles 4 . In addition, the silver nanoparticle layer 5 may have a higher particle density of the silver nanoparticles 4 than the silver nanoparticle-containing layer 3 .
The silver nanoparticle laminate film 6 according to the embodiment exhibits, for example, “purple”, “green”, and “blue” depending on the total amount of the silver nanoparticles 4 .

The thickness of the layered portion where the silver nanoparticles 4 aggregate along the surface layer of the silver nanoparticle laminated film 6 is preferably in the range of 10 nm or more and 120 nm or less. When the thickness of the layered portion where the silver nanoparticles 4 are aggregated is not within the range of 10 nm or more and 120 nm or less, it tends to be difficult to exhibit the three colors described above. In addition, the silver nanoparticle laminated film 6 according to the present embodiment does not have to be provided with the "underlying layer 2". The "underlayer 2" is also called a "thin film layer" when it is relatively thin, and is also called a "film" or a "thick film layer" when it is relatively thick. The details of each of these layers will be described below.

[Base material 1]
The base material 1 is a layer that supports the underlying layer 2 . Therefore, any type of base material can be used as long as it can support and form the underlying layer 2 . In this embodiment, as the substrate 1, for example, a PET (polyethylene terephthalate) film, a cellulose triacetate (TAC) film, a polymethacrylate film, a polypropylene film, or the like can be used.
The surface of the base material 1 may be treated so as to facilitate the formation of the underlying layer 2 . Examples of the treatment applied to the surface of the base material 1 include corona treatment. In addition, since the substrate 1 is a layer that supports the underlayer 2 as described above, when the underlayer 2 is thick and has sufficient mechanical strength, the silver nanoparticle laminate according to the present embodiment can be used. Body 7 may not comprise substrate 1 .

[Underlayer 2]
The underlayer 2 is a layer that supports the silver nanoparticle-containing layer 3 and has a thickness of 4 μm to 60 μm. In the present embodiment, the underlying layer 2 is a layer formed by polymerizing one or more (meth)acrylate compounds, for example. More specifically, the underlayer 2 is a layer formed using one or more kinds of urethane-acrylic oligomer or the like, and for example, under an environment in which the below-described underlayer composition 2a is not purged with nitrogen, that is, in the atmosphere. It is a layer that is cured inside. The underlying layer 2 may be a layer cured in a nitrogen-purged environment. "Under a nitrogen-purged environment" means an environment in which the nitrogen concentration is higher than the nitrogen concentration in the atmosphere. Further, the underlayer 2 may contain a compound that generates a polymerization initiation species upon exposure to ionizing radiation, such as a photopolymerization initiator. In addition, in this embodiment, the silver nanoparticle-containing layer 3 may be directly formed on the substrate 1 without providing the underlying layer 2 .

[Silver nanoparticle-containing layer 3]
The silver nanoparticle-containing layer 3 is a layer formed on the underlayer 2 and having a thickness of 1 μm to 7 μm. The silver nanoparticle-containing layer 3 contains at least silver nanoparticles 4 and a compound having at least one carboxyl group and one or more polymerizable unsaturated double bonds in the molecule. parts are polymerized. Therefore, the silver nanoparticle-containing layer 3 may contain a resin having a three-dimensional crosslinked structure, and the silver nanoparticle-containing layer 3 is a compound that generates polymerization initiation species by ionizing radiation, such as a photopolymerization initiator. may contain

Moreover, the compound having at least one or more carboxy groups and one or more polymerizable unsaturated double bonds in the molecule is, for example, a compound having acrylic acid or methacrylic acid. Specific examples of the compound having an unsaturated double bond that can be used in this embodiment will be described later. Furthermore, the silver nanoparticle-containing layer 3 does not have carboxy groups other than compounds having at least one or more carboxy groups and one or more polymerizable unsaturated double bonds in the molecule in order to improve the film strength. Up to 30% by mass of compounds having one or more polymerizable unsaturated double bonds may be included.
Moreover, the photopolymerization initiator described above is an initiator for photopolymerizing the polymerizable compound described above. Therefore, as long as the above-described polymerizable compound can be photopolymerized, the type of the compound is not limited. A specific example of the photopolymerization initiator that can be used in this embodiment will be described later.

The dispersed/aggregated state of the silver nanoparticles 4 in the silver nanoparticle-containing layer 3 will be described with reference to FIG. The silver nanoparticle-containing layer 3 contains silver nanoparticles 4 in addition to the resins described above. FIG. 2 is a cross-sectional view schematically showing the dispersed/aggregated state of the silver nanoparticles 4 in the silver nanoparticle laminated film 6 according to the first embodiment.
Most of the silver nanoparticles 4 in this embodiment are aggregated in layers along the surface IF of the silver nanoparticle-containing layer 3, and the aggregation width varies depending on the total amount of the silver nanoparticles 4 added. Here, the “aggregation width”, that is, the “thickness of the silver nanoparticles 4 aggregated in layers along the surface layer of the silver nanoparticle laminated film 6” means that the distance between the silver nanoparticles 4 is maintained at less than 2.5 nm. means the thickness of the area where the

Further, in the silver nanoparticle-containing layer 3, the mass (W _Ag ) of the silver nanoparticles 4, and the weight of the compound having at least one or more carboxyl groups and one or more polymerizable unsaturated double bonds in the molecule. The mixed mass ratio (W _Ag /W _C ) with the mass (W _C ) is, for example, within the range of 1/70 or more and 1/20 or less.
In addition, the compound having at least one or more carboxyl groups and one or more polymerizable unsaturated double bonds in the molecule is contained in the silver nanoparticle-containing layer 3 in an amount of, for example, 70% by mass or more.

In addition, the surfaces of the silver nanoparticles 4 are covered with protective molecules containing, for example, an alkyldiamine having a primary amino group and a tertiary amino group as a main component. The term “main component” as used herein refers to the component (molecule) that is the most numerous among the plurality of protective molecules covering the surface of the silver nanoparticles 4 . Also, the average primary particle size (D50) of the silver nanoparticles 4 is, for example, within the range of 1 nm or more and 30 nm or less. Also, the silver nanoparticles 4 described above can be dispersed in an organic solvent. If the average primary particle size (D50) of the silver nanoparticles 4 is not within the range of 1 nm or more and 30 nm or less, the dispersibility of the silver nanoparticles 4 tends to deteriorate, and the color development tends to deteriorate. The average primary particle size was determined from the particle size distribution measured in a 0.1% by mass toluene solution using a Nanotrac UPA-EX150 particle size distribution analyzer (dynamic light scattering method, manufactured by Nikkiso Co., Ltd.).

[Silver nanoparticle layer 5]
The silver nanoparticle layer 5 is a layer formed on the silver nanoparticle-containing layer 3 and having a thickness of 500 nm or less. The silver nanoparticle layer 5 contains the same silver nanoparticles 4 as the silver nanoparticles 4 contained in the silver nanoparticle-containing layer 3 . Therefore, it is difficult to observe the boundary between the silver nanoparticles 4 contained in the silver nanoparticle-containing layer 3 and the silver nanoparticles 4 contained in the laminated silver nanoparticle layer 5 even when cross-sectional observation is performed with a scanning electron microscope. , the silver nanoparticle-containing layer 3 and the silver nanoparticle layer 5 are difficult to distinguish. However, even if a layered portion having a thickness in the range of 10 nm or more and 120 nm or less is formed in the laminate using only the silver nanoparticles 4 contained in either layer, the coloration of the present embodiment is not exhibited.

(Method for producing silver nanoparticle laminated film 6)
First, a method for synthesizing the silver nanoparticles 4 necessary for manufacturing the silver nanoparticle laminated film 6 according to the above-described embodiment will be described. Next, preparation of the silver nanoparticle-containing dispersion liquid (silver nanoparticle-containing layer composition) 3a containing the silver nanoparticles 4 and the like will be described. Next, preparation of the silver nanoparticle dispersion liquid (composition for silver nanoparticle layer) 5a containing the silver nanoparticles 4 and the like will be described. Next, the preparation of the underlying layer composition 2a used to form the underlying layer 2, etc. will be described. Finally, the manufacturing process of the silver nanoparticle laminated film 6 according to the above-described embodiment will be described with reference to FIG.

[Synthesis of silver nanoparticles 4]
Among silver-containing compounds, silver compounds that are easily decomposed by heating to generate metallic silver are preferably used as the raw material of silver that constitutes the silver nanoparticles 4 . Examples of such silver compounds include silver carboxylates obtained by combining silver with carboxylic acids such as formic acid, acetic acid, oxalic acid, malonic acid, benzoic acid, and phthalic acid, as well as silver chloride, silver nitrate, and silver carbonate. . Among these silver compounds, silver oxalate is preferably used from the viewpoint of easily generating a metal by decomposition and hardly generating impurities other than silver. Silver oxalate has a high silver content, and oxalate ions are decomposed and removed as carbon dioxide by heating. For this reason, metallic silver can be obtained as it is by thermal decomposition without the need for a reducing agent, and it can be said to be advantageous in that impurities are less likely to remain.

In this embodiment, a predetermined alkyldiamine is added to the silver compound to form a complex compound of the silver compound and the alkyldiamine. This complex contains silver, alkyldiamine and oxalate ions. In addition, in this complex compound, the complex compound is formed by coordinating each silver atom contained in the silver compound with the nitrogen atom contained in the amine via the lone pair of electrons. guessed.
Considering the ease of coordination of the alkyldiamine to the silver atom, the amino group is preferably a primary RNH ₂ (R is a hydrocarbon group), and a tertiary amino group R ₃ N ( If R is a hydrocarbon group), it becomes spatially difficult. Therefore, if the alkyldiamine has a primary amino group (primary amino group) and a tertiary amino group (tertiary amino group), the primary amino group is selectively coordinated to the silver atom. , the tertiary amino groups will face outwards depending on the molecular chain. A secondary amino group can be coordinated, but it is expensive due to synthetic problems and has lower reactivity than a primary amino group.

The diamine-coordinated metallic silver atoms produced in this way quickly aggregate after their production, form metallic bonds with each other, and form silver nanoparticles. At this time, the diamine coordinated to each silver atom forms a protective film on the surface of the silver nanoparticles. It is considered that it becomes difficult for the above silver atoms to bond. For this reason, even when the decomposition of the silver compound contained in the complex compound and the generation of silver nanoparticles are performed in the absence of a solvent and the silver atoms are present at an extremely high density, the average primary particle diameter is typically It is considered that silver nanoparticles having a uniform particle size can be stably obtained when (D50) is in the range of 1 nm or more and 30 nm or less.

In the formation of the complex compound of the silver compound and the diamine, the molar ratio of the silver atom and the diamine is preferably within the range of 1:1 to 1:4, preferably within the range of 1:2 to 1:4. is more preferred. In the formation of a complex compound of a silver compound and a diamine, if the amount of the diamine is less than the above range, the ratio of silver atoms not coordinated with the diamine increases, so that the resulting silver nanoparticles become enlarged. Become. In addition, since the presence of diamine in an amount equal to or more than twice the amount of silver atoms makes it possible to stably obtain silver nanoparticles having an average primary particle diameter (D50) of approximately 30 nm or less, this level of diamine amount Assume that all silver atoms are capable of being coordinated by diamines. In addition, if the amount of diamine is 4 times or more the amount of silver atoms, the density of silver atoms in the reaction system will decrease, and the final recovery yield of silver will decrease. It is preferable to: Further, when the molar ratio of silver atoms and diamines is about 1:1, all the amines are coordinated with the silver atoms to form a complex compound, resulting in the absence of a dispersion solvent that holds the reaction system. Therefore, it is also preferable to mix a reaction solvent such as methanol as necessary.

When the complex compound of the silver compound and the diamine is heated while being stirred, a suspension exhibiting a blue luster is obtained. By removing excess diamine and the like from this suspension, silver nanoparticles whose surfaces are coated with protective molecules according to the present embodiment (hereinafter also simply referred to as “silver nanoparticles”) are obtained. The conditions for obtaining silver nanoparticles by heating a complex compound of a silver compound and a diamine include temperature, pressure, atmosphere, and other conditions for thermal decomposition depending on the type of silver compound and diamine used. You can choose. At this time, from the viewpoint of preventing the generated silver nanoparticles from being contaminated by reaction with the atmosphere in which the thermal decomposition is to be performed, or from decomposing the protective film covering the surface of the silver nanoparticles, an argon atmosphere or other inert atmosphere is used. It is preferred to carry out the thermal decomposition of the silver compound in an active atmosphere. On the other hand, when silver oxalate is used as the silver compound, the reaction space is protected by carbon dioxide generated by the decomposition of oxalate ions. Thermal decomposition of silver oxalate is possible.

The temperature at which the complex compound of the silver compound and the diamine is heated for the thermal decomposition of the silver compound is preferably below the boiling point of the diamine used in general from the viewpoint of preventing detachment of the diamine. In the present embodiment, generally by heating to about 80 to 130° C., silver nanoparticles having a protective film made of diamine can be obtained.

As described above, compared to other silver nanoparticle synthesis methods that generally require an excess amount of alkylamine relative to silver, in the present embodiment, the total amount of silver atoms: diamine is 1:1 (molar ratio). However, since silver nanoparticles can be synthesized in high yield, the amount of alkyldiamine used can be reduced. In addition, since the carbon dioxide generated by the thermal decomposition of oxalate ions is easily removed from the reaction system, there is no by-product derived from the reducing agent, and the separation of silver nanoparticles from the reaction system is easy. The purity of the nanoparticles is also high.

[Preparation of Silver Nanoparticle-Containing Dispersion Liquid 3a and Formation of Silver Nanoparticle-Containing Layer 3]
In the present embodiment, a silver nanoparticle-containing dispersion liquid 3a, which is a coating composition for forming the silver nanoparticle-containing layer 3, is applied onto the substrate 1 or the underlying layer 2 to form the silver nanoparticle-containing layer 3. may be formed.
When dispersing the silver nanoparticles 4 according to the present embodiment in a solvent or the like used as a dispersion solvent, that is, when preparing the silver nanoparticle-containing dispersion liquid (silver nanoparticle-containing layer composition) 3a, the silver nanoparticles 4 is preferably in the range of 3% by mass or more and 20% by mass or less with respect to the solvent. In addition, under conditions that do not detach the protective film that protects the surface of the silver nanoparticles 4, excess alkyldiamine or the like used in forming the protective film is removed and replaced with the solvent to be used. It is preferable to obtain a dispersion liquid in which silver nanoparticles 4 having a protective film are dispersed.

Examples of the dispersion medium for dispersing the silver nanoparticles 4 having the protective film include toluene, terpineol C manufactured by Nippon Terpene Chemical Co., Ltd., dihydroterpineol, Tersolve THA-90, and the like. Moreover, you may mix and use several types among these solvents. Among these dispersion media, toluene is particularly preferred. The above-mentioned solvent can be present in the silver nanoparticle-containing dispersion 3a in an amount up to 97% by mass of the entire silver nanoparticle-containing dispersion 3a. It becomes difficult to observe, and if it is less than 3% by mass, the coating film color (coloration) tends to be too light. For this reason, the range of 3% by mass or more and 20% by mass or less is preferable. The dispersion medium added to the silver nanoparticle-containing dispersion 3a is substantially removed when the silver nanoparticle-containing dispersion 3a is applied to the substrate 1 or the like and dried.
Moreover, when the silver nanoparticles 4 according to the present embodiment are exposed to the atmosphere or the like, the protective film may be detached even at a low temperature, and aggregation and sintering of the silver nanoparticles 4 may start. Therefore, when the silver nanoparticles 4 are substituted with an appropriate solvent from alkyldiamine or the like, it is preferable to select conditions under which the silver nanoparticles 4 are not exposed to the air or the like.

Further, a compound having at least one or more carboxy groups and one or more polymerizable unsaturated double bonds in the molecule and a photopolymerization initiator are added to the dispersion medium containing the silver nanoparticles 4 according to the present embodiment. may be additionally prepared.
Examples of the compound having at least one carboxyl group and one or more polymerizable unsaturated double bond in the molecule include compounds represented by formula (1).
The presence or absence of the compound represented by formula (1) can be analyzed by, for example, pyrolysis gas chromatography or mass spectrometry.
_CH2 =C(-R)-COO _- CH2CH2OCO-( _CH2 ) _{n -} COOH (1)
(In formula (1), R represents a hydrogen atom or a methyl group, and n represents an integer of 2 to 6)

The carboxy group of the compound having at least one carboxy group and one or more polymerizable unsaturated double bond in the molecule includes, for example, succinic acid, glutaric acid, adipic acid, pimelic acid, and spellic acid. with 2-hydroxyethyl acrylate and 2-hydroxyethyl methacrylate. More specific examples include 2-acryloyloxyethylsuccinic acid, 2-methacryloyloxyethylsuccinic acid and the like. Moreover, you may mix and use several types among these compounds. Among these compounds, 2-methacryloyloxyethylsuccinic acid is particularly preferred.
Further, the compound having at least one or more carboxy groups and one or more polymerizable unsaturated double bonds in the molecule may be contained in the silver nanoparticle-containing dispersion liquid 3a in an amount of 70% by mass or more. When the compound having at least one or more carboxy groups and one or more polymerizable unsaturated double bonds in the molecule in the silver nanoparticle-containing dispersion liquid 3a is less than 70% by mass, the silver nanoparticle-containing layer The mechanical strength of 3 tends to be insufficient.

In addition to a compound having at least one carboxyl group and one or more polymerizable unsaturated double bonds in the molecule, the silver nanoparticle-containing dispersion liquid 3a contains, for example, a compound for the purpose of improving surface curability and film strength. As the upper limit of 30% by mass, a compound having a polyfunctional unsaturated double bond may be added. If the amount of polyfunctional unsaturated double bonds added to the silver nanoparticle-containing dispersion liquid 3a exceeds 30% by mass, the dispersibility of the silver nanoparticles 4 is affected, and the intended coloration is no longer exhibited. Due to shrinkage, curling of the silver nanoparticle laminate 7 or the silver nanoparticle laminate film 6 may become strong. Specific examples of compounds having polyfunctional unsaturated double bonds that can be added to the silver nanoparticle-containing dispersion liquid 3a include pentaerythritol triacrylate, trimethylolpropane triacrylate, dipentaerythritol hexaacrylate, and polybasic acid-modified Acrylates DPE6A-MS (dipentaerythritol pentaacrylate succinic acid-modified), PE3A-MS (pentaerythritol triacrylate succinic acid-modified), DPE6A-MP (dipentaerythritol pentaacrylate phthalate-modified), PE3A-MS (pentaerythritol triacrylate phthalic acid-modified product), etc., but not limited to these.

Photopolymerization initiators that can be used in the present embodiment include compounds that polymerize when irradiated with ultraviolet rays among ionizing radiation, such as acetophenones, benzophenones, α-hydroxyketone, benzyl methyl ketal, α-Aminoketone, monoacylphosphine oxide, bisacylphosphine oxide and the like can be used singly or in combination.
In the present embodiment, in addition to the components described above, compatible additives such as plasticizers, stabilizers, surfactants, leveling agents, coupling agents, etc. are added as necessary for the purpose of the present embodiment. can be added within a range that does not impair the

[Preparation of silver nanoparticle dispersion liquid 5a and formation of silver nanoparticle layer 5]
In the present embodiment, the silver nanoparticle layer 5 may be formed by applying a silver nanoparticle dispersion liquid 5a, which is a coating composition for forming the silver nanoparticle layer 5, onto the silver nanoparticle-containing layer 3. .
When dispersing the silver nanoparticles 4 according to the present embodiment in a solvent or the like used as a dispersion solvent, that is, when preparing the silver nanoparticle dispersion liquid (silver nanoparticle layer composition) 5a, the silver nanoparticles 4 are It is preferably in the range of 3% by mass or more and 20% by mass or less with respect to the solvent. In addition, under conditions that do not detach the protective film that protects the surface of the silver nanoparticles 4, excess alkyldiamine or the like used in forming the protective film is removed and replaced with the solvent to be used. It is preferable to obtain a dispersion liquid in which silver nanoparticles 4 having a protective film are dispersed.

Examples of a dispersion medium for dispersing silver nanoparticles 4 having a protective film that can be used in the present embodiment include toluene, terpineol C manufactured by Nippon Terpene Chemical Co., Ltd., dihydroterpineol, tersolve THA-90, and the like. . Moreover, you may mix and use several types among these solvents. Among these dispersion media, toluene is particularly preferred. The above-described solvent can be present in the silver nanoparticle dispersion 5a in an amount up to 97% by mass of the entire silver nanoparticle dispersion 5a. If it is less than 3% by mass, the coating film color (coloration) tends to be too light. For this reason, the range of 3% by mass or more and 20% by mass or less is preferable. The dispersion medium added to the silver nanoparticle dispersion 5a is substantially removed when the silver nanoparticle dispersion 5a is applied to the substrate 1 or the like and dried.

Moreover, when the silver nanoparticles 4 according to the present embodiment are exposed to the atmosphere or the like, the protective film may be detached even at a low temperature, and aggregation and sintering of the silver nanoparticles 4 may start. Therefore, when the silver nanoparticles 4 are substituted with an appropriate solvent from alkyldiamine or the like, it is preferable to select conditions under which the silver nanoparticles 4 are not exposed to the air or the like.
In the present embodiment, in addition to the components described above, compatible additives such as plasticizers, stabilizers, surfactants, leveling agents, coupling agents, etc. are added as necessary for the purpose of the present embodiment. can be added within a range that does not impair the

The present embodiment will be described in further detail below.
<Silver oxalate>
Silver oxalate has a high silver content and usually decomposes at 200°C. Thermal decomposition is advantageous in that oxalate ions are removed as carbon dioxide and the metal salt is obtained as it is, so that no reducing agent is required and impurities are less likely to remain. For this reason, silver oxalate is preferably used as a silver compound that is a raw material of silver for obtaining silver nanoparticles 4 in the present embodiment. Therefore, the present embodiment will be described below in the case of using silver oxalate as the silver compound. However, as described above, in the complex compound formed between the silver compound and the predetermined diamine, it goes without saying that the silver oxalate may be used without being limited to silver oxalate as long as the diamine is coordinated to the silver atom. .

The silver oxalate used in this embodiment is not limited, and for example, commercially available silver oxalate can be used. Also, 20 mol % or less of oxalate ions in silver oxalate may be replaced with at least one of carbonate ions, nitrate ions and oxide ions. In particular, when 20 mol % or less of oxalate ions are replaced with carbonate ions, there is an effect of enhancing the thermal stability of silver oxalate. If the amount of substitution exceeds 20 mol %, the above complex compound may become difficult to thermally decompose. In particular, an oxalate ion/alkyldiamine/silver complex compound containing an alkyldiamine having a boiling point of 250° C. or less can be thermally decomposed at a low temperature of 100° C. or less to obtain silver nanoparticles with high efficiency.

<Alkyldiamine>
The alkyldiamine used in this embodiment is not particularly limited in its structure. Since the alkyldiamine reacts with silver oxalate to form the complex compound described above, at least one amino group must be a primary amino group or a secondary amino group. Preferably. Furthermore, the other amino group is desirably a tertiary amino group in order to increase affinity with a non-polar dispersion solvent. Examples of alkyldiamines include N,N-dimethylethylenediamine, N,N-diethylethylenediamine, N,N-dimethyl-1,3-propanediamine, N,N-diethyl-1,3-propanediamine, N,N -dimethyl-1,5-diamino-2-methylpentane, N,N-dimethyl-1,6-hexanediamine and the like, but are not limited to these. Also, a plurality of different alkyldiamines may be simultaneously reacted with silver oxalate.

Further, in the present embodiment, the compound having at least one or more carboxy groups and one or more polymerizable unsaturated double bonds in the molecule includes, for example, acrylic resins and urethane resins having acryloyl groups and methacryloyl groups. Examples include radically polymerizable compounds such as oligomers, prepolymers, monomers, and the like. These resins are crosslinked by applying energy such as heat, ultraviolet rays, and electron beams. These compounds are appropriately selected in consideration of film strength, adhesion to the substrate, and amount of curl.

In the present embodiment, preferred components for use in compounds having at least one or more carboxyl groups and one or more polymerizable unsaturated double bonds in the molecule are the following dicarboxylic acids such as succinic acid, one side of which is acrylic Examples include those substituted with esters and methacryl esters. Specifically, Shin-Nakamura Chemical Co., Ltd., A-SA (2-acryloyloxyethyl succinic acid), SA (2-methacryloyloxyethyl succinic acid) and the like can be mentioned, but not limited thereto.

Further, in the present embodiment, when using a monofunctional monomer such as A-SA as a compound having at least one or more carboxy groups and one or more polymerizable unsaturated double bonds in the molecule, photocrosslinking For example, a polyfunctional monomer may be added to allow the Examples of polyfunctional monomers that can be added in the present embodiment include pentaerythritol triacrylate, dipentaerythritol hexaacrylate, trimethylolpropane triacrylate, DPE6A-MS (dipentaerythritol pentaacrylate succinic acid-modified product), PE3A-MS (pentaerythritol triacrylate succinic acid modified product), DPE6A-MP (dipentaerythritol pentaacrylate phthalic acid modified product), PE3A-MS (pentaerythritol triacrylate phthalic acid modified product), etc. Yes, but not limited to this.
These polyfunctional monomers tend to make it difficult for the silver nanoparticles 4 to disperse. However, in the presence of a dispersion medium such as toluene, there is a tendency that the dispersibility is not adversely affected if the added amount is 25% or less based on the mass of the monomer having a carboxyl group as described above.

In the present embodiment, in the silver nanoparticle-containing dispersion liquid 3a, the mass (W _Ag ) of the silver nanoparticles 4, a monomer having a carboxy group and a polymerizable unsaturated double bond (at least one A compound having at least one carboxyl group and at least one polymerizable unsaturated double bond) has a mixed mass ratio (W _Ag /W _C ) of _1/70 or more and 1/10 or less. It is preferably within the range, and more preferably within the range of 1/50 or more and 1/20 or less. When the ratio of silver nanoparticles 4 is more than 1/10, the yellow plasmon resonance absorption intensity derived from silver nanoparticles 4 increases, and no change in color may be observed no matter what is done. On the other hand, if the ratio of the silver nanoparticles 4 is less than 1/70, the absorption intensity may be weakened, resulting in only a light-colored coating film. If the ratio of the silver nanoparticles 4 exceeds 1/30, the storage stability of the coating liquid (silver nanoparticle-containing dispersion liquid 3a) tends to become unstable, and precipitation aggregates may be observed after being left for several hours. In addition, when precipitated aggregates are generated in the silver nanoparticle-containing dispersion liquid 3a, the silver nanoparticle-containing dispersion liquid 3a may be used after removing the precipitated aggregates.

Further, in the present embodiment, the silver nanoparticle-containing dispersion 3a may contain a compound that generates polymerization initiation species by ionizing radiation, that is, a polymerization initiator. When using a compound (photopolymerization initiator) that polymerizes by irradiation with ultraviolet rays among ionizing radiation, examples of the photopolymerization initiator include acetophenones, benzophenones, α-hydroxyketone, benzyl methyl ketal, α - Aminoketone, monoacylphosphine oxide, bisacylphosphine oxide, etc. are used singly or in combination. Specifically, BASF Corporation, Irgacure 184, Irgacure 651, Irgacure 1173, Irgacure 907, Irgacure 369, Irgacure 819, Irgacure TPO, Lambarti Corporation, Esacure KIP-150, Esacure ONE, etc. can be mentioned. do not have.

The amount of the photopolymerization initiator used is preferably in the range of 0.5% by mass or more and 10% by mass or less based on the mass of the polymerizable compound (mainly monomers and oligomers) in the silver nanoparticle-containing dispersion liquid 3a. It is preferably in the range of 5% by mass or more and 5% by mass or less. The hardness of the silver nanoparticle-containing layer 3 tends to be low even when the content is at least above this range.

In the present embodiment, a silver nanoparticle-containing dispersion liquid 3a, which is a coating liquid prepared by dispersing and dissolving silver nanoparticles 4 and a polymerizable compound in a solvent or the like to adjust the viscosity, is applied to a film base material or a glass base material. Then, the silver nanoparticle-containing layer 3 is formed by performing ionizing radiation irradiation treatment such as ultraviolet irradiation and curing. At this time, surface hardening is accelerated by purging the ionizing radiation irradiated portion with nitrogen.

In the present embodiment, in addition to the components described above, compatible additives such as plasticizers, stabilizers, surfactants, leveling agents, coupling agents, etc. are added as necessary for the purpose of the present embodiment. can be added within a range that does not impair the However, it is preferable not to add fillers for suppressing curling or increasing hardness, because such fillers cause a decrease in transmittance and problems in dispersibility.

[Preparation of underlayer composition 2a and formation of underlayer 2]
In the present embodiment, the base layer composition 2a, which is a coating liquid composition containing a (meth)acrylic compound and a compound that generates a polymerization initiation species by ionizing radiation, is applied onto the substrate 1, and the base layer composition A so-called base layer 2 may be formed by irradiating the object 2a with ionizing radiation and curing it. Details of the process of forming the underlying layer 2 will be described later. Moreover, if the silver nanoparticle laminated film 6 does not include the underlying layer 2, this step may not be performed.
As the (meth)acrylic compound used for forming the base layer 2, since the base layer 2 is a layer that has appropriate toughness and elongation after photocuring and can be separated from the base material 1 as a self-supporting film, for example, an acrylic resin. , oligomers such as urethane resins, prepolymers, radically polymerizable compounds such as monomers, and the like. These resins are crosslinked by applying energy such as heat, ultraviolet rays, and electron beams. These compounds are appropriately selected in consideration of film strength, adhesion to the substrate, and amount of curl.

The base layer composition 2a includes, as (meth)acrylic compounds, two types of urethane (meth)acrylate resin A (hereinafter also simply referred to as "resin A") and urethane (meth)acrylate resin B (hereinafter simply referred to as " (also referred to as "resin B"). Resin A is a monomer or oligomer containing two acryloyl groups or methacryloyl groups in one molecule and having a molecular weight of 2000 or less. Resin B is an oligomer containing two or three acryloyl groups or methacryloyl groups in one molecule and having a molecular weight of 3,000 or more and 20,000 or less. In the underlayer composition 2a, the ratio (W _A /W _B ) of the mass % (W _A ) of the resin A to the mass % (W _B ) of the resin B is in the range of 30/70 to 70/30. is preferably
(Meth)acrylic is a description that includes both acrylate and methacrylate.

In this embodiment, as described above, resin A uses a monomer containing two acryloyl groups or methacryloyl groups in one molecule, and resin B contains two or three acryloyl groups or methacryloyl groups in one molecule. It is preferred to use monomers containing This is because when there is one acryloyl group or one methacryloyl group, it is difficult to form the desired photocurable resin film, and tackiness may occur due to insufficient curing. In addition, when the number of acryloyl groups or methacryloyl groups is four or more, curling may occur due to large cure shrinkage, and the tensile elongation of the coating film may be significantly reduced.

In the underlayer 2 formed using the underlayer composition 2a, the resin A mainly contributes to improvement in strength. Therefore, a photo-cured product obtained by photo-curing a coating solution containing resin A and an ultraviolet polymerization initiator but not containing resin B has a maximum stress of 60 N/mm ² or more in a tensile test and a tensile elongation of It is preferably 10% or less. In order to obtain the above tensile properties, the molecular weight of resin A is preferably 2000 or less. If the molecular weight of Resin A is more than 2000, the viscosity of the coating liquid will be high, making coating difficult.

As the resin A, for example, urethane acrylate C-1 (Shin-Nakamura Chemical Co., Ltd.), AH-600, AT-600 (Kyoeisha Chemical Co., Ltd.), etc. described in JP-A-2013-159691, and UA-1280 , UA-1280MK (Shin-Nakamura Chemical Co., Ltd.), Shikou UV6300B, UV7620A, UV7600B (Nippon Synthetic Chemical Co., Ltd.), UF-8001G (Kyoeisha Chemical Co., Ltd.), and the like can be used. That is, as the resin A, a urethane (meth)acrylate oligomer or monomer can be used. Among these, UA-1280MK can be preferably used.
As the resin B, for example, Shiko UV7000B, Shiko UV3520 (Nippon Synthetic Chemical Co., Ltd.), or the like can be used. That is, as the resin B, a urethane (meth)acrylate oligomer or monomer can be used. Among these, violet light UV7000B can be preferably used.

The (meth)acrylic acid ester compound contained in the underlayer 2 formed using the underlayer composition 2a can be easily peeled off from the base material 1 such as PET and formed into a self-supporting film. Requires toughness and elongation. Therefore, when only oligomers or monomers other than urethane (meth)acrylate are used, there is a possibility that problems such as large curling of the cured film and inability to peel off from the substrate 1 may occur.
As a compound that generates polymerization initiation species by ionizing radiation for curing the (meth)acrylic acid ester compound, that is, as the polymerization initiator, the same photoradical polymerization initiator as in the silver nanoparticle-containing dispersion liquid 3a described above is used. can be done. Specifically, for example, Esacure ONE (Lamberti) can be used as a photopolymerization initiator.

The content of the polymerization initiator is preferably in the range of 0.5% by mass or more and 1% by mass or less based on the total solid content in the underlayer composition 2a, which is the coating liquid. If the content of the polymerization initiator is more than 1% by mass, the surface hardening proceeds during ionizing radiation irradiation without nitrogen purge, making it difficult to obtain the desired coloration. On the other hand, when the content of the polymerization initiator is less than 0.5% by mass, the film hardness may become too low.
In addition, the underlayer composition 2a may further contain a solvent. The solvent contained in the underlayer composition 2a can be appropriately selected from acetone, which is a ketone solvent highly compatible with resin A and resin B, and methyl ethyl ketone, in consideration of coating suitability and the like.

[Manufacturing process of silver nanoparticle laminated film 6]
Each step for manufacturing the silver nanoparticle laminated film 6 according to the embodiment described above will be described with reference to FIG.
As shown in FIG. 3(a), the base layer composition 2a described above is applied onto a base material 1 such as a PET film using a bar coater so that the thickness of the base layer 2 is, for example, 4 μm to 60 μm. do. If the silver nanoparticle laminated film 6 does not include the underlying layer 2, the step of forming the silver nanoparticle laminated film 6 directly on the base material 1 is performed.

Next, the base layer composition 2a applied on the base material 1 is dried by being placed in an environment of, for example, 90° C. for 100 seconds. Thereafter, the underlayer composition 2a is irradiated with ionizing radiation or the like to cure the underlayer composition 2a. In the present embodiment, the underlayer composition 2a is cured in the atmosphere in order to improve adhesion with the silver nanoparticle-containing layer 3, which is the upper layer. In this way, as shown in FIG. 3B, the base layer 2 according to this embodiment is formed. The ionizing radiation irradiated to the underlayer composition 2a includes, for example, an ultra-high pressure mercury lamp, a xenon lamp, UV-LED, and the like, and is appropriately selected from among these depending on the irradiation wavelength and irradiation intensity. The irradiation energy of ionizing radiation is, for example, about 230 mJ/cm ² when ultraviolet light is irradiated in the air.

Next, as shown in FIG. 3(c), the silver nanoparticle-containing dispersion 3a is applied onto the underlayer 2, for example, by a bar coater so that the silver nanoparticle-containing layer 3 has a thickness of 3 μm to 10 μm. Apply using
Next, the silver nanoparticle-containing dispersion liquid 3a is dried, for example, by placing it in an environment of 90° C. for 60 seconds. Finally, the silver nanoparticle-containing dispersion liquid 3a is irradiated with ionizing radiation or the like to cure the silver nanoparticle-containing dispersion liquid 3a. In this way, as shown in FIG. 3(d), the silver nanoparticle-containing layer 3 according to this embodiment is formed. The ionizing radiation irradiated to the silver nanoparticle-containing dispersion liquid 3a includes, for example, an ultra-high pressure mercury lamp, a xenon lamp, UV-LED, etc., and is appropriately selected from among them according to the irradiation wavelength and irradiation intensity. . The irradiation energy of ionizing radiation is, for example, about 230 mJ/cm ² when ultraviolet light is irradiated in a nitrogen-purged environment. In addition, surface hardening is promoted by purging the ionizing radiation irradiated area with nitrogen.

Next, as shown in FIG. 3(e), the silver nanoparticle dispersion 5a described above is applied onto the silver nanoparticle-containing layer 3 so that the wet film thickness of the silver nanoparticle dispersion 5a is 4 to 23 μm. Apply using a coater.
Next, the silver nanoparticle dispersion liquid 5a is dried, for example, by placing it in an environment of 90° C. for 60 seconds. Thus, as shown in FIG. 3(f), the silver nanoparticle layer 5 according to this embodiment is formed. A protective layer (overcoat layer) (not shown) may be provided on the silver nanoparticle layer 5 .
Through the above steps, the silver nanoparticle laminated film 6 according to the present embodiment shown in FIG. 3(f) is manufactured.

The silver nanoparticle laminated film 6 produced in this manner exhibits a silvery metallic luster when viewed from the silver nanoparticle layer 5 side. Moreover, the coloration of the silver nanoparticle laminated film 6 is observed on the substrate 1 side of the silver nanoparticle laminated film 6 .
In this embodiment, the silver nanoparticle dispersion 5a, the silver nanoparticle-containing dispersion 3a, and the underlayer composition 2a are applied using a bar coater, but the present invention is limited to this. not to be For example, instead of the bar coater, known coating means such as a roll coater, gravure coater, micro gravure coater, die coater, and dip coater may be used.

(Color change mechanism)
As described above, in the present embodiment, at least part of the silver nanoparticles 4 contained in the silver nanoparticle-containing layer 3, and the silver nanoparticles 4 aggregated in layers on the surface layer of the silver nanoparticle-containing layer 3. , and the mass of the silver nanoparticles 4 in the silver nanoparticle layer 5 formed on the silver nanoparticle-containing layer 3 is changed to change the color of the coating film, that is, the coloration.
Although the details of the color change mechanism of the silver nanoparticle laminate film 6, that is, the color change mechanism, are not clear here, the silver nanoparticles 4 contained in the silver nanoparticle laminate film 6 according to the embodiment are not clarified. Most of them are aggregated in layers on the surface layer of the silver nanoparticle laminated film 6 .
Considering these points, it is considered to be caused by plasmon coupling caused by aggregated silver nanoparticles 4 . Therefore, this point will be described in detail below.

FIG. 4 shows the measurement result of the absorption spectrum of the silver nanoparticle laminated film 6 according to the embodiment. As shown in FIG. 4 , two absorption peaks appear near 490 nm and 650 nm regardless of the content of silver nanoparticles 4 . When the content of the silver nanoparticles 4 in the silver nanoparticle laminated film 6 is large, the absorption at 490 nm is large, and as the content of the silver nanoparticles 4 becomes small, the absorption at 650 nm is large. This absorption around 650 nm is a wavelength that is not shifted by normal plasmon resonance or plasmon coupling of spherical silver nanoparticles.

In addition, regarding the relationship between the silver nanoparticles 4 aggregated in the silver nanoparticle-containing layer 3 and the silver nanoparticle layer 5 and the "color" exhibited by the silver nanoparticle laminated film 6, the silver nanoparticles When the total number of 4 is large, the color observed from the substrate 1 side of the silver nanoparticle laminated film 6, that is, the back side of the silver nanoparticle laminated film 6 is "purple", and the silver in the silver nanoparticle-containing layer 3 It becomes "green" as the content of the nanoparticles 4 decreases, and becomes "blue" as the content of the silver nanoparticles 4 in the silver nanoparticle layer 5 decreases.

Specifically, the content of the silver nanoparticles 4 in the silver nanoparticle-containing layer 3 is for a compound having at least one carboxy group and one or more polymerizable unsaturated double bonds in the molecule. When it is in the range of 1.0% by mass or more and 2.0% by mass or less, and the solution concentration of the silver nanoparticles 4 for forming the silver nanoparticle layer 5 is 2.5% by mass or more, The color observed from the back side of the silver nanoparticle laminated film 6 is "purple".

The content of the silver nanoparticles 4 in the silver nanoparticle-containing layer 3 is 0.25% by mass with respect to the compound having at least one or more carboxyl groups and one or more polymerizable unsaturated double bonds in the molecule. When it is within the range of less than 1.0% by mass and the solution concentration of the silver nanoparticles 4 for forming the silver nanoparticle layer 5 is 2.5% by mass, the silver nanoparticle laminated film 6 The color observed from the back side of is "green".

The content of the silver nanoparticles 4 in the silver nanoparticle-containing layer 3 is 0.25% by mass with respect to the compound having at least one or more carboxyl groups and one or more polymerizable unsaturated double bonds in the molecule. and when the solution concentration of the silver nanoparticles 4 for forming the silver nanoparticle layer 5 is 2.5% by mass, it is observed from the back side of the silver nanoparticle laminate film 6. The color to be displayed becomes "blue".
In the range where the content of the silver nanoparticles 4 in both the silver nanoparticle-containing layer 3 and the silver nanoparticle layer 5 is not specified, the respective colors tend to be partially mixed, resulting in uneven coating and uneven film thickness. Since it changes slightly, it is preferable to set the content of the silver nanoparticles 4 within the numerical range described above in order to obtain the specified color.

Looking at the cross-sectional STEM images (FIGS. 11, 12, and 13) in each color, in each case, the silver nanoparticles 4 are aggregated in layers at the interface between the silver nanoparticle-containing layer 3 and the silver nanoparticle layer 5. can be confirmed. However, the thickness of the layer of the silver nanoparticles 4 does not correspond to the amount (content) of the silver nanoparticles 4 added, and the distance between particles and the particle density (distribution seen from the top) may differ. Although it is possible, the mechanism has not yet been elucidated at present. Details of FIGS. 11, 12, and 13 will be described in Examples described later.

As described above, in view of the conventional problems, as a result of intensive research, the component added to increase the film strength and adhesiveness adversely affects the dispersion of the silver nanoparticles 4 and aggregates, but the raw material of silver When producing silver nanoparticles 4 by decomposing the silver compound that becomes By using a polymerizable compound having a carboxyl group, it is possible to prepare a coating composition capable of improving film strength and adhesion while maintaining dispersibility. Furthermore, films exhibiting various colors can be produced by changing the layer structure and dispersibility of the silver nanoparticles in the film. More specifically, silver oxalate, for example, is used as a silver compound that is a raw material of silver, and a primary diamine is attached to a silver atom contained in the silver oxalate by interposing an N,N-dialkylaminoalkylamine. A complex compound is formed in which the amino group portion is coordinated. Then, by thermally decomposing the portion of oxalate ions that constitute silver oxalate in this state, silver nanoparticles 4 can be prepared at a high yield. Also. Since the tertiary amino group that does not form a complex faces the outermost surface of the particle, the silver nanoparticles 4 are attracted to each other by ionic bonds with, for example, an acrylate compound or a methacrylate compound having a carboxy group, thereby forming a dispersion coating liquid without breaking the dispersion system. can be prepared. Furthermore, the obtained coating liquid can be easily diluted with an organic solvent or the like, and a photopolymerization initiator or the like can also be added. When a coating film of silver nanoparticles 4 prepared on a plastic substrate using this dispersion coating liquid is irradiated with UV rays from a high-pressure mercury lamp or the like, a cured film with high film strength and strong adhesion to the substrate can be obtained in various colors. can.

In addition, one of the features (invention-specifying matter) of the silver nanoparticle laminate 7 of the present embodiment is that "a silver nanoparticle-containing layer containing silver nanoparticles is formed on a base material, and the silver nanoparticle-containing layer is formed, on the silver nanoparticle-containing layer, a silver nanoparticle layer having a higher particle density of the silver nanoparticles than the silver nanoparticle-containing layer is formed." Then, by forming the silver nanoparticle layer 5 having a higher particle density of the silver nanoparticles 4 than the silver nanoparticle-containing layer 3 on the silver nanoparticle-containing layer 3, the variation of colors that can be produced is increased. It has the effect of However, the interface between the silver nanoparticle-containing layer 3 and the silver nanoparticle layer 5 is not clear, and its characteristics cannot be directly specified by the structure and properties of the finished silver nanoparticle laminate 7. , it may be difficult depending on the situation, and it can be said that it is impractical.
As examples, the production method of the silver nanoparticles 4, the dispersibility in a solvent, the preparation of the coating liquid for coating film formation, and the evaluation of the physical properties of the coating film are shown below, but the present invention is limited to these. not a thing

[Example 1]
[Synthesis of silver oxalate]
Add 60 mL of distilled water to 9.92 g of oxalic acid dihydrate (Kanto Chemical Co., Ltd.) and dissolve while heating. Distilled water was added and dissolved while heating, and the mixture was heated and stirred for 1 hour. The precipitated silver oxalate was recovered by gravity filtration, filtered and washed with 200 mL of hot water and 50 mL of methanol (Kanto Kagaku Co., Ltd.), and then dried at room temperature in a light-shielding desiccator under reduced pressure. The yield of silver oxalate thus obtained was 21.6 g (yield 90.4%).

[Synthesis of silver nanoparticles 4]
To 3.26 g of N,N-diethyl-1,3-diaminopropane (Tokyo Kasei Co., Ltd.) was added 0.13 g of oleic acid, and 1.90 g of silver oxalate obtained in the above step was added. The mixture was heated and stirred in an oil bath. Carbon dioxide bubbling occurred within 1 minute and turned into a brown suspension after a few minutes. After heating for 5 minutes, 30 mL of methanol was added to the cooled mixture, and the precipitate obtained by centrifugation was air-dried to obtain 1.48 g of a blue solid (yield based on silver: 97.0).

When the obtained silver nanoparticles 4 were observed in S-TEM mode (acceleration voltage 30 kV) using a scanning electron microscope (Hitachi High Technology Co., Ltd., SEM S-4800), they were spherical with a particle diameter of about 5 to 20 nm. Particles were observed. The results are shown in FIG. More specifically, FIG. 5 is a scanning electron microscope image of silver nanoparticles 4 observed after the toluene solvent dispersion of silver nanoparticles 4 obtained in Example 1 was dripped onto a substrate (copper mesh microgrid) and dried. is.

Next, the dispersibility of the obtained silver nanoparticles 4 in a solvent was evaluated. As a result, it was well dispersed in toluene, terpineol C (Nippon Terpene Chemical Co., Ltd.), dihydroterpineol (Nippon Terpene Chemical Co., Ltd.), and a mixed solvent containing these as main ingredients such as hexane. Dynamic light scattering particle size measurement (Nikkiso Co., Ltd., Nanotrac UPA-EX150) of the toluene dispersion solution revealed that the resulting silver nanoparticles 4 had an average particle size of 15 nm and were well dispersed. The results are shown in FIG. Further, the solid line shown in FIG. 6 indicates the cumulative frequency (%).

[Preparation of silver nanoparticle-containing dispersion liquid 3a]
0.10 g of the blue solid obtained in the above step was dispersed in 2.0 g of toluene (Kanto Chemical Co., Ltd.), and 5.0 g of 2-methacryloyloxyethyl succinic acid (SA, Shin-Nakamura Chemical Co., Ltd.) was added. 0.25 g of a photopolymerization initiator Esacure ONE (Lamberti) was added to the well-stirred mixture and dissolved to obtain a coating liquid, ie, a silver nanoparticle-containing dispersion liquid (silver nanoparticle-containing layer composition) 3a.

[Preparation of silver nanoparticle dispersion 5a]
0.10 g of the blue solid obtained in the above step was dispersed in 2.0 g of toluene (Kanto Kagaku Co., Ltd.) to prepare a coating liquid, that is, a silver nanoparticle dispersion liquid (silver nanoparticle layer composition) 5a.
Using a #10 wire bar, the silver nanoparticle-containing layer composition 3a containing the silver nanoparticles 4 obtained in the above step was applied onto a 75 μm thick untreated PET (Torel Mirror T60), and then applied at 90° C. for 1 minute. The solvent was evaporated in an oven. After putting this in a purge box and sealing nitrogen gas, it was exposed and cured at 240 mJ/cm ² on a UV conveyor.

After applying the silver nanoparticle layer composition 5a containing the silver nanoparticles 4 obtained in the above step to the silver nanoparticle-containing layer 3 cured in the above step using a #3 wire bar, The solvent was volatilized in an oven for minutes to obtain a silver nanoparticle laminate film 6 . At this point, the side of the silver nanoparticle laminated film 6 turned silver with metallic luster.
Next, in order to protect the silver nanoparticle laminated film 6, 10 g of UA-306I (urethane acrylic oligomer, Kyoeisha Chemical Co., Ltd.), 12 g of MEK, and 0.5 g of a photopolymerization initiator Esacure ONE (Lamberti) were added and dissolved for the overcoat layer. After coating the coating liquid 8a on the silver nanoparticle laminate film 6 formed in the above step using a #10 wire bar, the solvent was volatilized in an oven at 90° C. for 1 minute. After putting this into a purge box and sealing nitrogen gas, it was exposed and cured at 240 mJ/cm ² on a UV conveyor to obtain a silver nanoparticle laminated film 6 having an overcoat layer. The cured film thus obtained turned purple when viewed from the first side of the substrate (Table 1). In addition, Table 1 shows other evaluation items and their evaluation results.

The absorption spectrum (UV-2600 ultraviolet-visible spectrophotometer, Shimadzu Corporation, transmission mode, FIG. 7) of the silver nanoparticle laminated film 6 according to this example, examples described later, and each comparative example was measured. Table 1 shows the maximum absorption wavelength (λmax) obtained from the measured absorption spectrum. Table 1 shows the maximum absorption wavelength (λmax) in the wavelength region of less than 500 nm and the maximum absorption wavelength (λmax) in the wavelength region of 500 nm or more.
In addition, as an adhesion test, the releasability from the base material 1 of the silver nanoparticle laminated film 6 according to this example, examples to be described later, and each comparative example was examined. Regarding this adhesion (peelability), when the silver nanoparticle laminated film 6 did not peel from the substrate 1, it was evaluated as “not peeled”, and the silver nanoparticle laminated film 6 was removed from the substrate 1. When it peeled easily, it was evaluated as "easily peeled".
In addition, as a curl test, the produced silver nanoparticle laminated film 6 was cut into a 100 mm square, and the lifting of the opposite side when one side was pressed was examined. In addition, when the lifting of the silver nanoparticle laminated film 6 was less than 10 mm, it was evaluated as “◯”, and when it was 10 mm or more, it was evaluated as “×”.

[Example 2]
A silver nanoparticle-containing layer 3 was obtained in the same manner as in Example 1, except that 0.025 g of the blue solid matter in the silver nanoparticle-containing dispersion 3a of Example 1 was changed from 0.10 g to 0.025 g. Furthermore, a silver nanoparticle laminated film 6 was obtained in the same manner as in Example 1, except that 0.05 g of the blue solid matter in the silver nanoparticle dispersion 5a of Example 1 was changed from 0.10 g to 0.05 g. The cured film thus obtained turned green when viewed from the first side of the substrate (Table 1, FIG. 7). The evaluation results are shown in Table 1.

[Example 3]
A silver nanoparticle laminate film 6 was obtained in the same manner as in Example 1, except that 0.01 g of the blue solid matter in the silver nanoparticle-containing dispersion 3a of Example 1 was changed from 0.10 g to 0.01 g. The cured film thus obtained was colored blue when viewed from the substrate 1 side (Table 1, FIG. 7). The evaluation results are shown in Table 1.

[Example 4]
[Preparation of underlayer composition 2a]
A mixture of urethane acrylate compounds (UA-1280MK (manufactured by Shin-Nakamura Chemical Co., Ltd.): UV7000B (manufactured by Nippon Synthetic Chemical Co., Ltd.) = 25.40 g: 8.63 g) was added with 12.96 g of MEK and a photopolymerization initiator EsacureONE (Lambertie) 0. 34 g was added and dissolved to obtain a substrate coating liquid, that is, a base layer composition 2a.
The substrate coating solution obtained in the above step was applied to a 75 μm thick untreated PET (Torel Mirror T60) using a #40 wire bar, and the solvent was volatilized in an oven at 90° C. for 100 seconds. This was placed in a purge box without enclosing nitrogen gas, and was placed on a UV conveyor (Heraeus, CV-110Q-G type, light source: Light Hammer 10 Merk II, H bulb, hereinafter simply referred to as “UV irradiation”) at 240 mJ/ A silver nanoparticle laminated film 6 was obtained in the same manner as in Example 1, except that the underlying layer 2 that was exposed and cured at 1 cm ² was used. The cured film thus obtained turned purple when viewed from the first side of the substrate (Table 1, FIG. 8). Moreover, the cured film of this example could be easily peeled off from the PET substrate 1 . The evaluation results are shown in Table 1.

[Example 5]
Urethane acrylate compound of Example 4 (UA-1280MK (manufactured by Shin-Nakamura Chemical Co., Ltd.): UV7000B (manufactured by Nippon Synthetic Chemical Co., Ltd.) = 25.40 g: 8.63 g) instead of adding MEK 12.96 g, UF- 8001G (manufactured by Kyoeisha Chemical Co., Ltd.): UV7000B (manufactured by Nippon Synthetic Chemical Co., Ltd.) = 20.14 g: A silver nanoparticle laminated film 6 was formed in the same manner as in Example 4 except that 18.22 g of MEK was added to the mixture of 8.63 g. Obtained. The cured film thus obtained turned purple when viewed from the first side of the substrate (Table 1). Moreover, the cured film of this example could be easily peeled off from the PET substrate 1 . The evaluation results are shown in Table 1.

[Example 6]
A silver nanoparticle-containing layer 3 was obtained in the same manner as in Example 4, except that 0.05 g of the blue solid matter in the silver nanoparticle-containing dispersion liquid 3a of Example 4 was changed from 0.10 g to 0.05 g. Furthermore, a silver nanoparticle laminated film 6 was obtained in the same manner as in Example 4 except that 0.05 g of the blue solid matter in the silver nanoparticle dispersion 5a of Example 4 was changed from 0.10 g. The cured film thus obtained turned green when viewed from the first side of the substrate (Table 1, FIG. 8). Moreover, the cured film of this example could be easily peeled off from the PET substrate 1 . The evaluation results are shown in Table 1.

[Example 7]
A silver nanoparticle laminated film 6 was obtained in the same manner as in Example 6, except that 0.01 g of the blue solid matter in the silver nanoparticle-containing dispersion 3a of Example 6 was changed to 0.01 g. The cured film thus obtained turned blue when viewed from the side of substrate 1 (Table 1, FIG. 8). Moreover, the cured film of this example could be easily peeled off from the PET substrate 1 . The evaluation results are shown in Table 1.

[Example 8]
Except that 1.70 g of Irgacure 184 (manufactured by BASF) was added instead of 0.34 g of the photopolymerization initiator Esacure ONE (Lambertie) in the substrate coating liquid of Example 4 to make a silver nanoparticle-containing dispersion 3a. was operated in the same manner as in Example 4 to obtain a silver nanoparticle laminated film 6. The cured film thus obtained turned purple when viewed from the first side of the substrate (Table 1). Moreover, the cured film of this example could be easily peeled off from the PET substrate 1 . The evaluation results are shown in Table 1.

[Example 9]
Example 1 except that 5.0 g of SA in the silver nanoparticle-containing dispersion 3a of Example 1 was changed to a mixture of 4.0 g of SA and 1.0 g of trimethylolpropane triacrylate (light acrylate TMP-A, manufactured by Kyoeisha Chemical Co., Ltd.) A silver nanoparticle-containing layer 3 was obtained by the same operation. Furthermore, a silver nanoparticle laminated film 6 was obtained by performing the same operation as in Example 1. The cured film thus obtained turned purple when viewed from the side of substrate 1 (Table 1, FIG. 9). Moreover, the cured film of this example could be easily peeled off from the PET substrate 1 . The evaluation results are shown in Table 1.

[Example 10]
1.0 g of trimethylolpropane triacrylate (light acrylate TMP-A, manufactured by Kyoeisha Chemical Co., Ltd.) in the silver nanoparticle-containing dispersion liquid 3a of Example 9 was added to dipentaerythritol hexaacrylate (light acrylate DPE-6A, manufactured by Kyoeisha Chemical Co., Ltd.). ) A silver nanoparticle-containing layer 3 was obtained in the same manner as in Example 1, except that the content was changed to 1.0 g. Furthermore, a silver nanoparticle laminated film 6 was obtained by performing the same operation as in Example 1. The cured film thus obtained turned purple when viewed from the side of substrate 1 (Table 1, FIG. 9). Moreover, the cured film of this example could be easily peeled off from the PET substrate 1 . The evaluation results are shown in Table 1.

[Example 11]
1.0 g of trimethylolpropane triacrylate (light acrylate TMP-A, manufactured by Kyoeisha Chemical Co., Ltd.) in the silver nanoparticle-containing dispersion 3a of Example 9 was added to DPE6A-MS (dipentaerythritol pentaacrylate succinate), which is a basic acid-modified acrylate. A silver nanoparticle-containing layer 3 was obtained in the same manner as in Example 9, except that the acid-modified product (manufactured by Kyoeisha Chemical Co., Ltd.) was changed to 1.0 g. Furthermore, a silver nanoparticle laminated film 6 was obtained by performing the same operation as in Example 1. The cured film thus obtained turned purple when viewed from the side of substrate 1 (Table 1, FIG. 9). Moreover, the cured film of this example could be easily peeled off from the PET substrate 1 . The evaluation results are shown in Table 1.

[Comparative Example 1]
Example 1 except that 5.0 g of SA in the silver nanoparticle-containing dispersion 3a of Example 1 was changed to a mixture of 3.0 g of SA and 2.0 g of trimethylolpropane triacrylate (light acrylate TMP-A, manufactured by Kyoeisha Chemical Co., Ltd.) A silver nanoparticle-containing layer 3 was obtained by the same operation. Furthermore, a silver nanoparticle laminated film 6 was obtained by performing the same operation as in Example 1. The cured film thus obtained had a color close to gold, in which yellow and silver were simply superimposed when viewed from the first side of the substrate (Table 1, FIG. 10). The evaluation results are shown in Table 1.

[Comparative Example 2]
DPE6A-MS (dipentaerythritol pentaacrylate succinic acid-modified, manufactured by Kyoeisha Chemical Co., Ltd.), which is a basic acid-modified acrylate, was replaced with 5.0 g of SA in the silver nanoparticle-containing dispersion 3a of Example 1, except that 5.0 g was used. A silver nanoparticle-containing layer 3 was obtained in the same manner as in Example 1. Furthermore, a silver nanoparticle laminated film 6 was obtained by performing the same operation as in Example 1. The cured film thus obtained had a color close to gold, in which yellow and silver were simply superimposed when viewed from the first side of the substrate (Table 1, FIG. 10). The evaluation results are shown in Table 1.

In addition, FIG. 11 shows Example 4, FIG. 12 shows Example 6, and FIG. It is a scanning electron microscope image of each of the silver nanoparticles 4.
As described above, in each silver nanoparticle laminated film 6 obtained in Examples 1 to 11, by changing the total amount of silver in the silver nanoparticle-containing layer 3 and the silver nanoparticle layer 5, silver nanoparticle The color of the particle stack film 6 can be changed.

As described above, the layered film containing silver nanoparticles in the present invention can produce a functional film having optical properties peculiar to silver nanoparticles, and the color can be changed depending on the application.

REFERENCE SIGNS LIST 1 Base material 2 Base layer 2a Base layer composition 3 Silver nanoparticle-containing layer 3a Silver nanoparticle-containing dispersion 5 Silver nanoparticle layer 5a Silver nanoparticle dispersion 6 Silver nanoparticle laminated film 7 ... silver nanoparticle laminate IF ... interface

Claims (15)

A silver nanoparticle laminated film containing silver nanoparticles is provided on a substrate,
At least part of the silver nanoparticles contained in the silver nanoparticle multilayer film are aggregated in a layer along the surface of the silver nanoparticle multilayer film on the surface layer of the silver nanoparticle multilayer film,
The substrate side of the silver nanoparticle multilayer film is colored ,
The thickness of the silver nanoparticles aggregated in layers along the surface of the silver nanoparticle laminated film is in the range of 10 nm or more and 120 nm or less,
The silver nanoparticle laminated film is formed on the substrate and comprises a silver nanoparticle-containing layer containing the silver nanoparticles and a silver nanoparticle layer formed on the silver nanoparticle-containing layer,
At least part of the silver nanoparticles contained in the silver nanoparticle-containing layer are aggregated in a layer along the surface of the silver nanoparticle-containing layer on the surface of the silver nanoparticle-containing layer,
The average primary particle size (D50) of the silver nanoparticles is in the range of 1 nm or more and 30 nm or less,
A silver nanoparticle laminate, wherein the silver nanoparticle-containing layer further contains a compound having at least one or more carboxy groups and one or more polymerizable unsaturated double bonds in the molecule. A silver nanoparticle laminated film containing silver nanoparticles is provided on a substrate,
At least part of the silver nanoparticles contained in the silver nanoparticle multilayer film are aggregated in a layer along the surface of the silver nanoparticle multilayer film on the surface layer of the silver nanoparticle multilayer film,
The substrate side of the silver nanoparticle multilayer film is colored ,
The average primary particle size (D50) of the silver nanoparticles is in the range of 1 nm or more and 30 nm or less,
The surface of the silver nanoparticles is covered with a plurality of protective molecules,
the most abundant molecule among the plurality of protective molecules covering the surface of the silver nanoparticles is an alkyldiamine having a primary amino group and a tertiary amino group;
The silver nanoparticle laminated film is formed on the substrate and comprises a silver nanoparticle-containing layer containing the silver nanoparticles and a silver nanoparticle layer formed on the silver nanoparticle-containing layer,
At least part of the silver nanoparticles contained in the silver nanoparticle-containing layer are aggregated in a layer along the surface of the silver nanoparticle-containing layer on the surface of the silver nanoparticle-containing layer,
A silver nanoparticle laminate, wherein the silver nanoparticle-containing layer further contains a compound having at least one or more carboxy groups and one or more polymerizable unsaturated double bonds in the molecule. A silver nanoparticle laminated film containing silver nanoparticles is provided on a substrate,
At least part of the silver nanoparticles contained in the silver nanoparticle multilayer film are aggregated in a layer along the surface of the silver nanoparticle multilayer film on the surface layer of the silver nanoparticle multilayer film,
The substrate side of the silver nanoparticle multilayer film is colored ,
The silver nanoparticle laminated film is formed on the substrate and comprises a silver nanoparticle-containing layer containing the silver nanoparticles and a silver nanoparticle layer formed on the silver nanoparticle-containing layer,
The silver nanoparticle-containing layer further comprises a compound having at least one or more carboxyl groups and one or more polymerizable unsaturated double bonds in the molecule,
In the silver nanoparticle-containing layer, the mass of the silver nanoparticles (W _Ag ) and the mass of the compound having at least one or more carboxyl groups and one or more polymerizable unsaturated double bonds in the molecule (W _C ) and the mixed mass ratio (W _Ag /W _C ) is in the range of 1/70 or more and 1/10 or less,
At least part of the silver nanoparticles contained in the silver nanoparticle-containing layer are aggregated in a layer along the surface of the silver nanoparticle-containing layer on the surface of the silver nanoparticle-containing layer,
A silver nanoparticle laminate, wherein the average primary particle diameter (D50) of the silver nanoparticles is in the range of 1 nm or more and 30 nm or less . The silver nanoparticle laminate according to claim 3, wherein the silver nanoparticle layer has a higher particle density of the silver nanoparticles than the silver nanoparticle-containing layer. 4. The compound having at least one or more carboxy groups and one or more polymerizable unsaturated double bonds in the molecule is a compound represented by formula ( 1 ). The silver nanoparticle laminate according to any one of .
_CH2 =C(-R)-COO _- CH2CH2OCO-( _CH2 ) _{n -} COOH (1)
(In formula (1), R represents a hydrogen atom or a methyl group, and n represents an integer of 2 to 6) The carboxy group of the compound having at least one or more carboxy groups and one or more polymerizable unsaturated double bonds in the molecule is succinic acid,
70% by mass or more of the compound having at least one carboxyl group and one or more polymerizable unsaturated double bonds in the molecule is contained in the silver nanoparticle-containing layer. The silver nanoparticle laminate according to any one of claims 1 to 5 . 7. The silver nanoparticle laminate according to any one of claims 1 to 6, further comprising an underlying layer between the base material and the silver nanoparticle-containing layer. Forming a silver nanoparticle-containing layer containing silver nanoparticles on a substrate;
forming a silver nanoparticle layer having a higher particle density of the silver nanoparticles than the silver nanoparticle-containing layer on the silver nanoparticle-containing layer ;
At least part of the silver nanoparticles contained in the silver nanoparticle-containing layer are aggregated in a layer along the surface of the silver nanoparticle-containing layer on the surface of the silver nanoparticle-containing layer,
The average primary particle size (D50) of the silver nanoparticles is in the range of 1 nm or more and 30 nm or less,
A method for producing a silver nanoparticle laminate, wherein the silver nanoparticle-containing layer further contains a compound having at least one or more carboxyl groups and one or more polymerizable unsaturated double bonds in the molecule. . In the step of forming the silver nanoparticle-containing layer, a composition for a silver nanoparticle-containing layer containing the silver nanoparticles and a (meth)acrylate monomer is applied onto the substrate and dried to obtain the silver nanoparticles. 9. The method for producing a silver nanoparticle laminate according to claim 8, wherein a containing layer is formed. At least part of the silver nanoparticles contained in the silver nanoparticle-containing layer, the mass of the silver nanoparticles aggregated in a layer on the surface of the silver nanoparticle-containing layer, and the silver nanoparticle-containing layer on the 10. The method for producing a silver nanoparticle laminate according to claim 8, wherein the mass ratio of the formed silver nanoparticle layer to the mass of the silver nanoparticles is changed. 11. The silver nanoparticles according to any one of claims 8 to 10, further comprising a step of forming an underlying layer on the substrate before the step of forming the silver nanoparticle-containing layer. A method for producing a particle laminate. Forming a silver nanoparticle-containing layer containing silver nanoparticles on a substrate,
After forming the silver nanoparticle-containing layer, forming a silver nanoparticle layer having a higher particle density of the silver nanoparticles than the silver nanoparticle-containing layer on the silver nanoparticle-containing layer ,
At least part of the silver nanoparticles contained in the silver nanoparticle-containing layer are aggregated in a layer along the surface of the silver nanoparticle-containing layer on the surface of the silver nanoparticle-containing layer,
The average primary particle size (D50) of the silver nanoparticles is in the range of 1 nm or more and 30 nm or less,
A silver nanoparticle laminate, wherein the silver nanoparticle-containing layer further contains a compound having at least one or more carboxy groups and one or more polymerizable unsaturated double bonds in the molecule. A composition for a silver nanoparticle-containing layer containing the silver nanoparticles and a (meth)acrylate monomer is coated on the substrate and dried to form the silver nanoparticle-containing layer. Item 13. The silver nanoparticle laminate according to Item 12. At least part of the silver nanoparticles contained in the silver nanoparticle-containing layer, the mass of the silver nanoparticles aggregated in a layer on the surface of the silver nanoparticle-containing layer, and the silver nanoparticle-containing layer on the 14. The silver nanoparticle laminate according to claim 12 or 13, wherein the mass ratio of the formed silver nanoparticle layer to the mass of the silver nanoparticles is changed. 15. The silver nanoparticle laminate according to any one of claims 12 to 14, wherein an underlayer is formed on the substrate before forming the silver nanoparticle-containing layer.

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