JP2021116341A - Metal tone design laminate and its manufacturing method, as well as silica nanoparticle layer coating liquid and silver nanoparticle layer coating liquid - Google Patents

Abstract

To provide a laminate provided with high metal tone design (metal tone design laminate) that can be formed at low temperature and in short time and its manufacturing method, as well as a coating liquid for forming a silica nanoparticle layer used in the laminate (silica nanoparticle layer coating liquid) and a coating liquid for forming a silver nanoparticle layer used in the laminate (silver nanoparticle layer coating liquid).SOLUTION: A metal tone design laminate 1 according to one aspect of the present invention comprises a silica nanoparticle layer 4, a silver nanoparticle layer 6, and an overcoat layer 7 on a substrate 2 in this order, and the silica nanoparticle layer 4 contains silica nanoparticles 3 and polyvinyl alcohol, and the silver nanoparticle layer 6 contains silver nanoparticles 5, and the overcoat layer 7 is a transparent layer.SELECTED DRAWING: Figure 1

Description

The present invention relates to a metal-like design laminate and a method for producing the same, and a coating liquid for a silica nanoparticle layer and a coating liquid for a silver nanoparticle layer.

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. Furthermore, unlike many other pigments and pigments, silver nanoparticles are extremely effective in absorbing and scattering light, and have colors depending on the size and shape of the particles. The strong relationship between light and silver nanoparticles is called surface plasmon resonance, and when excited by light of a specific wavelength, the conduction electrons on the metal surface cause collective vibration, which causes unusual light scattering and light absorption. The characteristic is expressed.

In general, a coating liquid in which metallic silver is dispersed is often used for metal wiring. For example, a pattern is formed on a wiring board with a coating liquid in which metallic silver is dispersed, and the metallic silver contained in the coating liquid is sintered to form a wiring. When metallic silver is used as a conductive material, it is known that it is necessary to sinter at a low temperature by utilizing the melting point drop due to the miniaturization of dispersed metallic silver. At present, finely divided nano-sized metal nanoparticles are expected as a material that can be sintered at low temperature.

In this way, the technology using surface plasmon resonance by metal nanostructures has made remarkable progress in both the basic and applied fields, and when two-dimensional crystal sheets of silver nanoparticles are laminated on a metal substrate, they are orange according to the number of layers. It is also known that a vivid coloration of ~ red ~ pink ~ purple can be obtained (Patent Document 1).

Color development based on the surface plasmon resonance of silver nanoparticles is obtained when light is transmitted through a matrix in which the concentration of silver nanoparticles is low and the particles are sufficiently spaced apart. On the other hand, when the concentration (content) of silver nanoparticles in the matrix is increased to about 90% by mass to form a film in which the distance between silver nanoparticles is shortened, only reflected light is produced, not transmitted light. Observed. Then, in this case, a metallic design having a metallic luster is developed (Non-Patent Document 1). Further, when the silver nanoparticles are fused to each other by heating the film and thermally decomposing components other than the metal, not only a design of metallic luster can be obtained, but also the film strength is increased.

As described above, in order to obtain a practical coating film having a metal design, a high temperature and a long heating time are required. Patent Document 2 shows that a highly reflective reflective film (silver mirror film) can be produced. However, the reflective film coating liquid composition used here needs to be heat-treated at usually 80 to 400 ° C., preferably 90 to 300 ° C., more preferably 100 to 250 ° C. when forming the silver mirror film. For the uniformity of the thin film, for example, two or more heat treatments of 80 to 150 ° C. for 1 to 30 minutes and 150 to 300 ° C. for 1 to 30 minutes are required. Therefore, for example, it has been extremely difficult to obtain a metal-like design body (metal-like design film) on a highly versatile plastic base material or paper base material.

Japanese Patent No. 6091417 Special Table 2009-535661

Toshikatsu Kobayashi, Japan Society of Color Material, Vol. 75, p66-70 (2002)

Therefore, the present invention has been made in view of the above problems, and is a laminate (metal-designed laminate) that can be formed at a low temperature and in a short time and has a high metal-like design, a method for producing the same, and the like. A coating liquid for forming a silica nanoparticle layer used for a laminate (a coating liquid for a silica nanoparticle layer) and a coating liquid for forming a silver nanoparticle layer used for the laminate (for a silver nanoparticle layer). The purpose is to provide a coating liquid).

The metal-like design laminate according to one aspect of the present invention includes a silica nanoparticle layer, a silver nanoparticle layer, and an overcoat layer in this order on a base material, and the silica nanoparticle layer contains silica nanoparticles and polyvinyl alcohol. The silver nanoparticle layer contains silver nanoparticles, and the overcoat layer is a transparent layer.

Further, the coating liquid for the silica nanoparticle layer for forming the silica nanoparticle layer used in the metal-like design laminate according to one aspect of the present invention includes at least silica nanoparticles, polyvinyl alcohol, and a dispersion medium, and is described above. The average primary particle diameter (D50) of the silica nanoparticles is in the range of 5 nm or more and 100 nm or less, the dispersion medium is water, and the solid content is 2% by mass or more and 20% by mass with respect to the mass of the coating liquid. It is characterized in that it is within the range of mass% or less.

Further, the coating liquid for the silver nanoparticle layer for forming the silver nanoparticle layer used in the metal-like design laminate according to one aspect of the present invention contains at least silver nanoparticles, a dispersant, and a dispersion medium. The solid content is in the range of 5% by mass or more and 40% by mass or less with respect to the mass of the coating liquid.

Further, in the method for producing a metal-like design laminate according to one aspect of the present invention, a coating liquid for a silica nanoparticle layer, a coating liquid for a silver nanoparticle layer, and a coating liquid for an overcoat layer are applied on a base material. By applying each in this order and drying each, a silica nanoparticle layer, a silver nanoparticle layer, and an overcoat layer are formed in this order.

According to one aspect of the present invention, a laminate that can be formed at a low temperature and in a short time and has a high metal-like design property and a method for producing the same, and silica nanos used for the laminate (metal-like design laminate). It is possible to provide a coating liquid for forming a particle layer and a coating liquid for forming a silver nanoparticle layer used for a laminate thereof.

It is sectional drawing which shows typically the structure of the metal design laminated body which concerns on embodiment of this invention. It is a figure which shows the scanning electron microscope image of the silver nanoparticle obtained in Example 1 of this invention. It is a figure which shows the particle size distribution and the cumulative frequency (%) of the silver nanoparticles obtained in Example 1 of this invention. It is a figure which shows the scanning electron microscope image of the surface of the silica nanoparticle layer obtained in Example 1 of this invention. It is a figure which shows the scanning electron microscope image of the surface of the silver nanoparticle layer obtained in Example 1 of this invention. It is a figure which shows the scanning electron microscope image of each cross section of the silica nanoparticle layer and silver nanoparticle layer obtained in Example 1 of this invention.

Hereinafter, each configuration and each manufacturing method of the silica nanoparticle layer, the silver nanoparticle layer, and the metal-like design laminate exhibiting the metal-like design color according to the 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 plane dimensions, the ratio of the thickness of each layer, and the like are different from the actual ones. Further, the embodiments shown below exemplify a configuration for embodying the technical idea of the present invention, and the technical idea of the present invention describes the material, shape, structure, etc. of the constituent parts as follows. It is not specific to the thing. The technical idea of the present invention may be modified in various ways within the technical scope specified by the claims stated in the claims.

In the present embodiment, the metallic design property means a metallic texture. Further, in general, the metallic design color, that is, the metallic luster of the metallic design refers to the luster and luster peculiar to the metal, and includes, for example, the matte metallic luster having low brilliance. Specifically, the presence or absence of metallic luster is determined by measuring the average specular reflectance in the light region having a wavelength of 400 nm to 800 nm, and if the specular reflectance is 10% or more, it is determined that there is metallic luster. If the specular reflectance is less than 10%, the matte color tone becomes stronger, and it may be difficult to say that it has a metallic luster. Silver-colored origami, which is widely distributed in general, has a specular reflectance of about 38%, and metallic silver often has a specular reflectance of 90% or more. Further, it is said that the light of 550 nm is most easily captured by the human eye, and the higher the reflectance, the brighter the light tends to appear. Therefore, in the present embodiment, if the specular reflectance with respect to light of 550 nm is 40% or more, it is determined that a good metal-like design is provided.

[Metallic design laminate 1]
FIG. 1 is a cross-sectional view schematically showing the structure of the metal-like design laminate according to the present embodiment.
The metal-like design laminate 1 according to the present embodiment includes a base material 2, a base layer 8, a silica nanoparticle layer 4, a silver nanoparticle layer 6, and an overcoat layer 7 in this order. The details of each layer will be described below.

[Base material 2]
The base material 2 is a layer that supports the silica nanoparticle layer 4 and the base layer 8. Therefore, the base material 2 may be of any type as long as it can support and form the silica nanoparticle layer 4 and the base layer 8 and is non-metal. Examples of the base material 2 include films such as PET (polyethylene terephthalate) film, cellulose triacetate (TAC) film, polymethacrylic acid ester film, and polypropylene film.
The surface of the base material 2 may be treated so that the silica nanoparticle layer 4 and the base layer 8 can be easily formed. When the base material 2 is a film, the treatment applied to the surface includes, for example, a corona treatment.

[Silica nanoparticle layer 4]
The silica nanoparticle layer 4 is a layer containing silica nanoparticles 3 and polyvinyl alcohol (PVA), and is a layer formed on the base material 2 or the base layer 8. The silica nanoparticle layer 4 is a layer that serves as a receiving layer when the coating liquid for the silver nanoparticle layer used for forming the silver nanoparticle layer 6 is applied. Therefore, as the content of the silica nanoparticles 3 increases, the silica nanoparticles layer 4 becomes a porous film and can absorb the solvent contained in the coating liquid for the silver nanoparticles layer, so that the silver nanoparticles 5 are gaped with each other. Can be fixed without.

The average primary particle size (D50) of the silica nanoparticles 3 is preferably in the range of 5 nm or more and 100 nm or less, and more preferably in the range of 10 nm or more and 40 nm or less. If the average primary particle size (D50) of the silica nanoparticles 3 is less than 5 nm, the dispersibility of the silica nanoparticles 3 deteriorates when mixed with polyvinyl alcohol, and there is a possibility that uniform coating cannot be performed. On the other hand, when the average primary particle diameter (D50) of the silica nanoparticles 3 exceeds 100 nm, the silver nanoparticles 5 enter the silica nanoparticles layer 4 depending on the size of the silver nanoparticles 5, and the metal-like design is lost. In some cases, the metal-like design may be reduced.
In the present embodiment, the average primary particle size (D50) of the silica nanoparticles 3 is measured with a 0.1% by mass aqueous solution using a Nanotrac UPA-EX150 particle size distribution meter (dynamic light scattering method, manufactured by Nikkiso Co., Ltd.). It can be obtained from the particle size distribution.

Further, the silica nanoparticle layer 4 contains silica nanoparticles 3 in a range of 50% by mass or more and 95% by mass or less and polyvinyl alcohol in a range of 5% by mass or more and 50% by mass or less with respect to the mass of the silica nanoparticle layer 4. It is preferable that it is contained in. Further, the film thickness of the silica nanoparticle layer 4 is preferably in the range of 200 nm or more and 2 μm or less, which is thicker than the film thickness of the silver nanoparticle layer 6. When the content of the silica nanoparticles 3 is less than 50% by mass, the porosity of the silica nanoparticle layer 4 becomes low (low), so that when the coating liquid for the silver nanoparticle layer is applied, the coating for the silver nanoparticle layer is applied. Absorption of the solvent contained in the liquid may be delayed. In that case, since the silver nanoparticles 5 are in a dispersed state, the distance between the particles becomes long, and the metal design may be deteriorated. Further, if the content of the silica nanoparticles 3 exceeds 95% by mass, it may not be possible to form a coating film. Further, if the content of polyvinyl alcohol is less than 5% by mass, it may not be possible to form a coating film. Further, when the content of polyvinyl alcohol exceeds 50% by mass, the porosity of the silica nanoparticle layer 4 becomes low (low), so that when the coating liquid for the silver nanoparticle layer is applied, it is used for the silver nanoparticle layer. Absorption of the solvent contained in the coating liquid may be delayed. In that case, since the silver nanoparticles 5 are in a dispersed state, the distance between the particles becomes long, and the metal design may be deteriorated.

Further, if the film thickness of the silica nanoparticle layer 4 is less than 200 nm, the coating liquid for the silver nanoparticle layer may not be uniformly applied. Further, if the film thickness of the silica nanoparticle layer 4 exceeds 2 μm, it may be inconvenient from the viewpoint of flexibility.
Further, if the film thickness of the silica nanoparticle layer 4 is thinner than the film thickness of the silver nanoparticle layer 6, sufficient coating film strength may not be obtained.

The polyvinyl alcohol is a completely saponified polyvinyl alcohol having a saponification degree of 98% or more, or a completely saponified modified polyvinyl alcohol in which a part of the hydroxyl group is modified to at least one of a silanol group and an ethylene oxide group. Is preferable. When the degree of saponification is low, that is, when the degree of saponification is less than 98%, the dispersibility of the silica nanoparticles 3 in polyvinyl alcohol may be poor (low). In addition, the film strength may be weakened (decreased), and a large amount of a coating liquid for a silica nanoparticle layer may be required to form a coating film. Polyvinyl alcohol having a silanol group binds to silica nanoparticles 3 and can form a coating film even if a small amount is added. Further, since polyvinyl alcohol having an ethylene oxide group increases the hydrophilicity of the coating liquid for the silica nanoparticle layer by adding it, the absorbency of a solvent (solvent) or the like when the coating liquid for the silver nanoparticle layer is applied. Can be increased, and the silver nanoparticles 5 can be fixed to each other without gaps.

Further, the above-mentioned coating liquid for the silica nanoparticle layer includes at least silica nanoparticles, a dispersant, and a dispersion medium, and the dispersion medium is preferably water. The solid content of the coating liquid is preferably in the range of 2% by mass or more and 20% by mass or less with respect to the mass of the coating liquid for the silica nanoparticle layer. If the solid content is less than 2% by mass, the coating liquid for the silica nanoparticle layer is insufficiently dried, and sufficient coating film strength may not be obtained. Further, when the solid content exceeds 20% by mass, the dispersibility of the silica nanoparticles 3 may be deteriorated in the coating liquid for the silica nanoparticle layer, and the coatability may be deteriorated.

[Silver nanoparticle layer 6]
The silver nanoparticle layer 6 is a layer containing silver nanoparticles 5 and is a layer formed on the silica nanoparticle layer 4. The silver nanoparticle layer 6 is a layer exhibiting a metallic design color.
The silver nanoparticle layer 6 on the silica nanoparticle layer 4 is preferably having a specular reflectance of 10% or more. More preferably, it is 50% or more, and when the specular reflectance is 90% or more, the high metallic design property inherent in silver can be obtained.

Further, the silver nanoparticle layer 6 is thinner than the silica nanoparticle layer 4, the thickness of the silver nanoparticle layer 6 is within the range of 10 nm or more and 1 μm or less, and at least a part of the silver nanoparticle layer 6 is incompatible with each other in a plan view. It is preferable that an island-like structure in a continuous state is formed. If the film thickness of the silver nanoparticle layer 6 is within the above numerical range and the surface of the silver nanoparticle layer 6 forms an island-like structure, it is used as an electromagnetic wave transmitting film while obtaining high metal-like design. be able to. Here, the "island-like structure" means that the particle masses (so-called "islands"), which are aggregates of silver nanoparticles 5, are independent of each other, and the particles are slightly separated from each other or partially in contact with each other. It means a structure that is laid out in a state of being spread. The "discontinuous state" is not particularly limited, and includes an island shape, a state in which cracks are formed, and the like. The width of each "particle mass (island)" is not particularly limited, and is, for example, in the range of 50 nm or more and 500 nm or less in a plan view. The distance between the islands (crack width) is, for example, in the range of 1 nm or more and 10 nm or less. If the distance between the islands (crack width) is within the above numerical range, good electromagnetic wave transmission can be reliably obtained. In addition, it is considered that electromagnetic waves can be transmitted because they have "discontinuous parts" such as cracks.

The silver nanoparticle layer 6 has a metallic design property if at least one or more silver nanoparticles 5 are arranged in the thickness direction. Therefore, the thickness of the silver nanoparticle layer 6 is preferably 10 nm or more, which is the minimum size of the silver nanoparticles 5 contained in the silver nanoparticle layer 6. Further, if the thickness of the silver nanoparticle layer 6 is 1 μm or more, the cost increases and the electromagnetic wave transmission may decrease.

In addition to the silver nanoparticles 5, the silver nanoparticles layer 6 contains a binder component such as a non-reactive resin or a photocurable resin in a range of 1% by mass or more and 10% by mass or less with respect to the mass of the silver nanoparticles layer 6. May be included within. When the binder component exceeds 10% by mass, the concentration of the silver nanoparticles 5 tends to decrease, the metal design property tends to decrease, and the curl due to curing shrinkage tends to be strong. Further, when the binder component is 1% by mass or less, the hardness of the coating film is not sufficient, so that when the overcoat layer 7 is formed, the silver nanoparticles 5 migrate into the overcoat layer 7, resulting in a metallic design property. It may decrease.

Specific examples of the above-mentioned non-reactive resin include resins such as cellulose nitrate and acrylic resin. Further, the photocurable resin includes a compound having an unsaturated double bond which is a polymerizable compound, for example, a compound having acrylic acid and methacrylic acid, and a photopolymerization initiator which generates a radical species by ionizing radiation. Examples include resin. Specific examples of the compound having an unsaturated double bond that can be used in this embodiment will be described later.
Further, the above-mentioned photopolymerization initiator is an initiator for photopolymerizing the above-mentioned polymerizable compound. Therefore, any type of the above-mentioned polymerizable compound can be photopolymerized as long as it can be photopolymerized. Specific examples of the photopolymerization initiator that can be used in this embodiment will be described later.

The average primary particle diameter (D50) of the silver nanoparticles 5 contained in the silver nanoparticles layer 6 is preferably in the range of 10 nm or more and 200 nm or less. When the average primary particle diameter (D50) of the silver nanoparticles 5 is less than 10 nm, the silver nanoparticles 5 enter the silica nanoparticles layer 4, and the silver nanoparticles 5 do not line up on the surface of the silica nanoparticles 4 and have a metallic design. May decrease. Further, when the average primary particle diameter (D50) of the silver nanoparticles 5 is more than 200 nm, the dispersibility of the silver nanoparticles 5 in the coating liquid for the silver nanoparticles layer is lowered, unevenness is generated, and the metal design property is obtained. May decrease.

In the present embodiment, the average primary particle size (D50) of the silver nanoparticles 5 is adjusted to a 0.1 mass% toluene solution using a Nanotrac UPA-EX150 particle size distribution meter (dynamic light scattering method, manufactured by Nikkiso Co., Ltd.). It was obtained from the particle size distribution measured in the above.
Further, the surface of the silver nanoparticles 5 may be covered with, for example, an alkylamine having a primary amino group or a protective molecule containing an alkyldiamine having a primary amino group and a tertiary amino group as a main component. preferable. The "main component" here means the most abundant component (molecule) among the plurality of protective molecules covering the surface of the silver nanoparticles 5.

[Overcoat layer 7]
The overcoat layer 7 is a layer provided on the silver nanoparticle layer 6 and is a transparent layer having a thickness of 0.1 μm or more and 10 μm or less. Here, the "transparent layer" means a layer having a total light transmittance of 90% or more measured by a haze meter according to JIS-K-7361. If the thickness of the overcoat layer 7 is less than 0.1 μm, the strength of the overcoat layer 7 may not be sufficiently increased. Further, if the thickness of the overcoat layer 7 exceeds 10 μm, the entire metal-designed laminate may be curled or the metal-like design of the silver nanoparticle layer 6 may be deteriorated.
Further, the overcoat layer 7 needs to satisfy the condition that the color tone of the silver nanoparticle layer 6 does not change and the condition that it can adhere to the silver nanoparticle layer 6.

The overcoat layer 7 can be formed, for example, by using a commercially available clear lacquer spray or the same (meth) acrylic acid ester compound as the base layer 8. The overcoat layer 7 may be, for example, a layer formed by polymerizing one type or two or more types of (meth) acrylic acid ester compounds. More specifically, the overcoat layer 7 is a layer formed by using one or more types of polyester urethane acrylate or the like, and is, for example, a layer obtained by curing the coating liquid for the overcoat layer in the air. be. Here, the above-mentioned "atmosphere" means an environment having a nitrogen concentration equal to or lower than the nitrogen concentration in the atmosphere. The overcoat layer 7 may contain a compound that generates a polymerization initiator by ionizing radiation, for example, a photopolymerization initiator.
Further, the overcoat layer 7 may be formed by using, for example, a binder component such as a non-reactive resin or a photocurable resin used for forming the silver nanoparticle layer 6.
Further, the overcoat layer 7 may be attached using, for example, a commercially available transparent adhesive film or the like.

[Underground layer 8]
The base layer 8 is a layer that supports the silica nanoparticle layer 4 and has a thickness of 4 μm or more and 60 μm or less. The base layer 8 is, for example, a layer formed by polymerizing one type or two or more types of (meth) acrylic acid ester compounds. More specifically, the base layer 8 is a layer formed by using one type or two or more types of urethane acrylic oligomers, and is, for example, a coating for the base layer which is a coating liquid for forming the base layer 8. It is a layer formed by curing the working liquid in the air. Here, the above-mentioned "atmosphere" means an environment having a nitrogen concentration equal to or lower than the nitrogen concentration in the atmosphere. The base layer 8 may contain a compound that generates a polymerization initiator by ionizing radiation, for example, a photopolymerization initiator. Further, in the present embodiment, the silica nanoparticle layer 4 may be directly formed on the base material 2 without providing the base layer 8. That is, the base layer 8 may be provided as needed. By forming the silica nanoparticle layer 4 directly on the base material 2 without providing the base layer 8, the flexibility of the entire metal design laminate 1 is further improved as compared with the case where the base layer 8 is provided. Can be given.

(Manufacturing method of metal design laminate 1)
First, the preparation of the coating liquid for the silica nanoparticle layer required for producing the silica nanoparticle layer 4 provided in the metal design laminate 1 according to the present embodiment described above will be described. Next, a method for synthesizing the silver nanoparticles 5 required for producing the silver nanoparticle layer 6 will be described. Next, preparation of a silver nanoparticle dispersion liquid (coating liquid for a silver nanoparticle layer) containing silver nanoparticles 5 and the like will be described. Next, preparation of a coating liquid for the base layer used for forming the base layer 8 and the like will be described. Finally, the preparation of the coating liquid for the overcoat layer used for forming the overcoat layer 7 and the like will be described.

[Preparation of coating liquid for silica nanoparticle layer and formation of silica nanoparticle layer 4]
The silica nanoparticles 3 according to the present embodiment may be either vapor phase silica or colloidal silica as long as the average primary particle size (D50) is within the range of 5 nm or more and 100 nm or less and can be dispersed in water. Gas phase method silica is ultrafine silica synthesized by the so-called dry method or vapor phase method, which is made by burning silicon tetrachloride together with hydrogen and oxygen in synthetic silica which is a synthetic silicon compound mainly composed of silicon dioxide. Is. Most of the vapor phase silica has an average primary particle size (D50) of about 5 nm to 20 nm. Examples of such vapor phase silica include the AEROSIL series manufactured by Aerosil Japan Co., Ltd. and the Leolosil series manufactured by Tokuyama Corporation. Colloidal silica has an average primary particle size (D50) of about 9 nm to 200 nm and is spherical. Examples of such colloidal silica include the Snowtex series of Nissan Chemical Industries, Ltd. and the Cataloid-S series of Catalytic Chemical Industries, Ltd. There are high-purity colloidal silica PL series of Fuso Chemical Industries, Ltd. It is preferable that these are made into an aqueous dispersion of silica nanoparticles and then mixed with an aqueous solution of polyvinyl alcohol.

The polyvinyl alcohol according to the present embodiment is a completely saponified polyvinyl alcohol having a saponification degree of 98% or more, or a completely saponified modified polyvinyl alcohol having a functional group other than a hydroxyl group and an acetic acid group. Examples of the polyvinyl alcohol according to the present embodiment include Kuraray's Poval series and Mitsubishi Chemical's Gosenol series. Examples of the modified polyvinyl alcohol include those in which a part of the hydroxyl group is modified to at least one of a silanol group and an ethylene oxide group. As for polyvinyl alcohol, not only one type alone but also two or more types can be used in combination. Polyvinyl alcohol has a hydroxyl group in its structural unit, and this hydroxyl group and a silanol group on the surface of the silica nanoparticles 3 form a hydrogen bond to form a three-dimensional network structure in which the secondary particles of the silica nanoparticles 3 are chain units. Make it easier. It is considered that this can form a receiving layer having a porous structure with a high porosity by forming a three-dimensional network structure. Further, since the polyvinyl alcohol according to the present embodiment has a high degree of saponification, boiling water is prepared, polyvinyl alcohol is dissolved in the hot water little by little to prepare a polyvinyl alcohol aqueous solution, and then the polyvinyl alcohol aqueous solution and the above-mentioned polyvinyl alcohol are added. It is preferable to mix with the silica nanoparticles aqueous dispersion containing the silica nanoparticles 3.

In the present embodiment, the silica nanoparticle layer 4 is formed by applying the coating liquid for the silica nanoparticle layer thus prepared on the base material 2 or the base layer 8 and drying it.
In the present embodiment, in addition to the above-mentioned components, if necessary, compatible additives such as plasticizers, stabilizers, surfactants, leveling agents, coupling agents and the like are used as objects of the present embodiment. Can be added within a range that does not impair. However, it is preferable not to add fillers for suppressing curl or increasing hardness because they cause a decrease in transmittance and a problem in dispersibility.

[Synthesis of silver nanoparticles 5]
Among the silver-containing compounds, a silver compound that easily decomposes by heating to produce metallic silver is preferably used as a raw material for silver constituting the silver nanoparticles 5. Examples of such a silver compound include silver carboxylic acid obtained by combining silver with a carboxylic acid 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 forming a metal by decomposition and less likely to generate impurities other than silver. Silver oxalate has a high silver content, and oxalate ions are decomposed and removed as carbon dioxide by heating. Therefore, it can be said that it is advantageous in that metallic silver can be obtained as it is by thermal decomposition without the need for a reducing agent, and impurities are unlikely to remain.

In the present embodiment, a predetermined alkylamine or alkyldiamine is added to the silver compound to form a complex compound of the silver compound and the alkylamine or the alkyldiamine. This complex compound contains silver, alkylamines or alkyldiamines and oxalate ions. In this complex compound, the nitrogen atom contained in the amine is coordinated to each silver atom contained in the silver compound via its unshared electron pair to form the complex compound. Inferred.

Considering the ease of coordination of the alkylamine or alkyldiamine to the silver atom, the amino group is _{preferably RNH 2} (R is a hydrocarbon group), which is a primary group, and R, which is a tertiary amino group. _{If it is 3} N (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 selectively coordinates with the silver atom. The tertiary amino group faces outward depending on the molecular chain. Although the secondary amino group can be coordinated, it is preferable to use a primary amino group and a tertiary amino group because they are expensive due to synthetic problems and their reactivity is lower than that of the primary group.

The metal-silver atom coordinated with amine or diamine thus produced agglomerates rapidly after its formation, forms metal bonds with each other, and forms silver nanoparticles. At this time, since the amine and diamine coordinated to each silver atom form a protective film on the surface of the silver nanoparticles, after a certain number of silver atoms gather to form the silver nanoparticles, the amine and diamine are used. It is thought that the protective film makes it difficult for more silver atoms to bond. Therefore, even when the decomposition of the silver compound contained in the complex compound and the formation of silver nanoparticles are carried out in a state where no solvent is present and silver atoms are present at an extremely high density, the average primary particle diameter is typically average. It is considered that silver nanoparticles having the same particle size can be stably obtained in the range of (D50) of 10 nm or more and 200 nm or less.

In the formation of a complex compound of a silver compound and an amine or diamine, the molar ratio of the silver atom to the amine or diamine is preferably in the range of 1: 1 to 1: 4, and is in the range of 1: 2 to 1: 4. It is more preferable to use the inside. In the formation of a complex compound of a silver compound and an amine or a diamine, when the amount of the amine or the diamine is reduced beyond the above range, the proportion of silver atoms in which the amine or the diamine is not coordinated increases, and the obtained silver nano is obtained. The particles become bloated. Further, since the presence of amines and diamines in an amount of twice or more the amount of silver atoms makes it possible to stably obtain silver nanoparticles having an average primary particle diameter (D50) in the range of approximately 10 nm or more and 200 nm or less. It is considered that all silver atoms can be coordinated by amines and diamines with this amount of amines and diamines. Further, when the amount of amine and diamine is four times or more the amount of silver atom, the density of silver atom in the reaction system decreases, and the final recovery yield of silver decreases. Therefore, the amount of amine and diamine used is silver atom. It is preferable that the amount is 4 times or less of. Further, when the molar ratio of silver atom to amine and diamine is about 1: 1, there is no dispersion solvent in which all amines coordinate with the silver atom to form a complex compound and maintain the reaction system. Therefore, it is also preferable to mix a reaction solvent such as methanol if necessary. Moreover, both amine and diamine may be used within the above addition range.

When the complex compound of the silver compound, amine and diamine is heated with stirring, a suspension exhibiting a blue or gray luster is obtained. By removing excess amine, diamine, etc. from this suspension, silver nanoparticles whose surface is coated with the protective molecule according to the present embodiment (hereinafter, also simply referred to as "silver nanoparticles") can be obtained. The conditions for heating a complex compound of a silver compound with an amine and a diamine to obtain silver nanoparticles include the temperature, pressure, atmosphere, etc. for thermal decomposition depending on the type of silver compound, amine, and diamine used. Conditions can be selected as appropriate. At this time, from the viewpoint of preventing the generated silver nanoparticles from being contaminated by the reaction with the atmosphere in which thermal decomposition is performed and the protective film covering the surface of the silver nanoparticles being decomposed, an argon atmosphere or the like is not used. It is preferable to thermally decompose the silver compound in the 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, so that the complex compound of silver oxalate, amine and diamine is heated in the atmosphere. This makes it possible to thermally decompose silver oxalate.

The temperature at which the complex compound of the silver compound and the amine or diamine is heated for the thermal decomposition of the silver compound is preferably equal to or lower than the boiling point of the amine or diamine generally used from the viewpoint of preventing the desorption of the amine or diamine. In the present embodiment, generally, by heating to about 80 to 130 ° C., silver nanoparticles having a protective film formed of amine and diamine can be obtained.
As described above, in this embodiment, the total amount of silver atoms: amines and diamines is 1: 1 (molar), as compared with other methods for synthesizing silver nanoparticles, which generally require an excess amount of alkylamines with respect to silver. Since silver nanoparticles can be synthesized in high yield, the amount of alkylamine and alkyldiamine used can be reduced. In addition, since carbon dioxide generated by the thermal decomposition of oxalate ions is easily removed from the reaction system, there are no by-products derived from the reducing agent, and silver nanoparticles can be easily separated from the reaction system. The purity of nanoparticles is also high.

[Preparation of silver nanoparticle dispersion liquid and formation of silver nanoparticle layer 6]
When the silver nanoparticles 5 according to the present embodiment are dispersed in a solvent or the like used as a dispersion medium, that is, when a silver nanoparticle dispersion liquid (coating liquid for a silver nanoparticle layer) is prepared, silver which is a solid component is used. The content of the nanoparticles 5 is preferably in the range of 5% by mass or more and 40% by mass or less with respect to the mass of the coating liquid for the silver nanoparticle layer, and the dispersion contained in the coating liquid for the silver nanoparticle layer. It is more preferably in the range of 5% by mass or more and 40% by mass or less with respect to the mass of the medium. When the content of the silver nanoparticles 5 is less than 5% by mass, the surface plasmon resonance occurs due to the distance between the silver nanoparticles 5 in the state where the coating liquid for the silver nanoparticles layer is applied on the silica nanoparticles layer 4. In some cases, only the coloring caused by the above is visually recognized and the metallic design color is not exhibited. Further, when the content of the silver nanoparticles 5 exceeds 40% by mass, the dispersibility of the silver nanoparticles 5 in the coating solution for the silver nanoparticles layer decreases, and the silver nanoparticles in the coating solution for the silver nanoparticles layer decrease. The particles 5 may agglomerate. Further, under conditions that the protective film that protects the surface of the silver nanoparticles 5 is not detached, excess alkyldiamine and the like used when forming the protective film are removed and replaced with a solvent used for protection. It is preferable to obtain a dispersion liquid (coating liquid) in which silver nanoparticles 5 having a film are dispersed.

Examples of the dispersion medium for dispersing the silver nanoparticles 5 having the protective film include toluene, tetrahydrofuran, cyclohexanone, 1-butanol, terpineol C manufactured by Japan Terpineol Chemical Co., Ltd., dihydroterpineol, tersolve THA-90 and the like. can. Moreover, you may mix and use several kinds of these solvents (dispersion mediums). Further, the above-mentioned solvent can be contained in the coating liquid for the silver nanoparticle layer up to 97% by mass of the entire coating liquid for the silver nanoparticle layer. The dispersion medium contained in the coating liquid for the silver nanoparticle layer is substantially removed when the coating liquid for the silver nanoparticle layer is applied onto the silica nanoparticle layer 4 or the like and dried.
Further, when the silver nanoparticles 5 according to the present embodiment are exposed to the atmosphere or the like, the protective film is desorbed even at a low temperature, and cohesive sintering of the silver nanoparticles 5 is started. Therefore, when appropriately substituting an excess alkylamine, alkyldiamine, or the like used for forming the protective film with a solvent, it is possible to select and replace the conditions under which the silver nanoparticles 5 are not exposed to the atmosphere or the like. preferable.

When the silver nanoparticles 5 according to the present embodiment are dispersed in a solvent or the like used as a dispersion medium, a dispersant may be used. The content of the dispersant is preferably in the range of 1% by mass or more and 20% by mass or less with respect to the content (mass) of the silver nanoparticles 5 contained in the coating liquid for the silver nanoparticle layer. If the content of the dispersant is less than 1% by mass, the silver nanoparticles 5 may not be sufficiently dispersed in a solvent or the like, resulting in poor coatability. Further, if the content of the dispersant exceeds 20% by mass, the metal design may not be exhibited.

Dispersants can be broadly classified into anionic, cationic, and nonionic dispersants, and are appropriately selected according to the potential of the particle surface and the type of dispersion medium. Typical anionic dispersants are sulfate ester type, phosphoric acid ester type, carboxylic acid type, and sulfonic acid type, and most of them have an ethylene oxide (EO) -added molecular structure. Cationic dispersants can be classified into quaternary ammonium salt type, Cl salt type, non-Cl salt type, and EO addition type. Nonionic dispersants can be roughly classified into alkylene oxide-added type and calcanolamide type. Since the surface modification of the silver nanoparticles 5 according to the present embodiment is an amine complex, an anionic dispersant is particularly preferable. Specifically, polyoxyethylene alkyl ether phosphate (salt), polyoxyethylene alkyl ether sulfate, polyoxyethylene alkyl ether acetate, polyoxyethylene alkyl ether amber and the like are preferable, and polyoxyethylene alkyl ether is particularly preferable. Phosphate (salt) is preferred. Specifically, Phosphanol RB-40, RD-510Y, RD720N, RL-210, RS-410 (Toho Chemical Industry Co., Ltd.), NIKKOL DDP-8NV, DDP-2, DDP-4, DDP-6, DDP- 8. DDP-10 (Nikko Chemicals), Plysurf A212C, A215C, A208F, M208F, A208A, A208B, A210B, A219B, DB-01, AL, DBS (Daiichi Kogyo Seiyaku Co., Ltd.), etc. Not as long.

The coating liquid for the silver nanoparticle layer contains a compound having a polyfunctional unsaturated double bond, which is a polymerizable compound, and a photopolymerization initiator for the purpose of improving the surface curing and film strength of the silver nanoparticle layer 6. May be added. Specific examples of the polymerizable compound that can be added to the coating liquid for the silver nanoparticle layer include pentaerythritol triacrylate, trimethylolpropane triacrylate, dipentaerythritol hexaacrylate, and DPE6A-MS, which is a polybasic acid-modified acrylate. (Dipentaerythritol pentaacrylate succinate modified product), PE3A-MS (pentaerythritol triacrylate succinic acid modified product), DPE6A-MP (dipentaerythritol pentaacrylate phthalic acid modified product), PE3A-MS (pentaerythritol triacrylate phthalate product) Acid-modified products), etc., but this is not the case.

In the present embodiment, when the polymerizable compound is added to the coating liquid for the silver nanoparticle layer, that is, when the silver nanoparticle layer 6 contains the polymerizable compound, the mass (WAg) of the silver nanoparticles 5 and the polymerizable compound The mixed mass ratio (WAg / WC) with the mass (WC) of the silver nanoparticles 5 is preferably in the range of 1/10 or more and 10/1 or less, and when the ratio of the silver nanoparticles 5 is less than 1/10, the silver nanoparticles 5 The metallic design color derived from may be deteriorated. Further, if the ratio of the silver nanoparticles 5 is more than 10/1, uniform coating may be difficult.

Further, the coating liquid for the silver nanoparticle layer of the present embodiment may contain a compound that generates a polymerization initiator by ionizing radiation, that is, a polymerization initiator. When a compound (photopolymerization initiator) that generates a polymerization initiator by irradiating ultraviolet rays among the ionizing radiation is used, the photopolymerization initiator thereof is, for example, acetophenones, benzophenones, α-hydroxyketone, benzyl. Methyl ketal, α-aminoketone, monoacylphosphine oxide, bisacylphosphine oxide and the like can be used alone or in combination. Specifically, BASF, Irgacure 184, Irgacure 651, Irgacure 1173, Irgacure 907, Irgacure 369, Irgacure 819, Irgacure TPO, Lamberti, etc. do not have.

The amount of the photopolymerization initiator used is preferably in the range of 0.05% by mass or more and 1% by mass or less, particularly 0.1% by mass or more and 1% by mass, based on the total solid content in the coating liquid for the silver nanoparticle layer. It is preferably in the range of% or less. Even if it is at least more than this range, the hardness of the silver nanoparticle layer 6 tends to be low.

In the present embodiment, the silica nanoparticle layer 4 is a coating liquid for a silver nanoparticle layer, which is a coating liquid prepared by dispersing and dissolving silver nanoparticles 5 and a polymerizable compound and a photopolymerization initiator in a solvent or the like to adjust the viscosity. It is applied onto the surface and subjected to an ionizing radiation irradiation treatment such as ultraviolet irradiation and cured to form a silver nanoparticle layer 6.
In the present embodiment, in addition to the above-mentioned components, if necessary, compatible additives such as plasticizers, stabilizers, surfactants, leveling agents, coupling agents and the like are used as objects of the present embodiment. Can be added within a range that does not impair. However, it is preferable not to add fillers for suppressing curl or increasing hardness because they cause a decrease in transmittance and a problem in dispersibility.

Hereinafter, the substance used for producing the silver nanoparticles 5 will be described in more detail.
<Silver oxalate>
Silver oxalate has a high silver content and usually decomposes at 200 ° C. When pyrolysis is performed, oxalate ions are removed as carbon dioxide and a metal salt is obtained as it is, which is advantageous in that no reducing agent is required and impurities are less likely to remain. Therefore, in the present embodiment, silver oxalate is preferably used as the silver compound which is a raw material of silver for obtaining silver nanoparticles 5. Therefore, the present embodiment will be described below with respect to the case where silver oxalate is used as the silver compound. However, as described above, it goes without saying that in a complex compound formed between a silver compound and a predetermined diamine, the diamine is not limited to silver oxalate as long as it is coordinated to a silver atom. ..

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

<Amine>
The amine used in this embodiment is an alkylamine or an alkyldiamine, and the structure thereof is not particularly limited. Since the amine reacts with silver oxalate to form the above-mentioned complex compound, at least one amino group needs to be a primary amino group or a secondary amino group, which is a primary amino group. Is preferable. Further, in the case of diamine, it is desirable that the other amino group is a tertiary amino group in order to enhance the affinity with the non-polar dispersion solvent. Examples of alkylamines include ethylamine, n-propylamine, isopropylamine, 1,2-dimethylpropylamine, n-butylamine, isobutylamine, sec-butylamine, tert-butylamine, isoamylamine, tert-amylamine and 3-pentyl. Amine, n-amylamine, n-hexylamine, n-pentylamine, n-octylamine, 2-octylamine, 2-ethylhexylamine, n-nonylamine, n-aminodecane, n-aminoundecane, n-dodecylamine, n -Tridecylamine, n-tetradecylamine, n-pentadecylamine, n-hexadecylamine, n-heptadecylamine, n-octadecylamine, n-oleylamine, and the like can be mentioned. Further, examples of the alkyldiamine include N, N-dimethylethylenediamine, N, N-diethylethylenediamine, N, N-dimethyl-1,3-propanediamine, N, N-diethyl-1,3-propanediamine, and N. , N-dimethyl-1,5-diamino-2-methylpentane, N, N-dimethyl-1,6-hexanediamine, N, N-diisopropyl, N, N-dibutylaminopropane, N, N-diisobutyl 1, Examples thereof include 3-diaminopropane, but the present invention is not limited to this. Further, a plurality of different alkyldiamines may be reacted with silver oxalate at the same time.

[Preparation of coating liquid for base layer and formation of base layer 8]
In the present embodiment, a coating liquid for a base layer, which is a coating liquid containing a (meth) acrylic acid ester compound and a compound that generates a polymerization initiator by ionizing radiation, is applied onto the base material 2 and coated for the base layer. The so-called base layer 8 may be formed by irradiating the working solution with ionizing radiation and curing it. The details of the process of forming the base layer 8 will be described later.
Examples of the (meth) acrylic acid ester compound used for forming the base layer 8 include oligomers such as acrylic resin and urethane resin, and radically polymerizable compounds such as prepolymer and monomer. 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 a substrate, and curl amount.

When the base layer 8 is a self-supporting film that can be easily peeled off from the base material 2, the coating liquid for the base layer is a urethane (meth) acrylate resin A (hereinafter, simply referred to as a mere) as a (meth) acrylic acid ester compound. It is preferable that at least "resin A") and urethane (meth) acrylate resin B (hereinafter, also simply referred to as "resin B") are contained. Resin A is a monomer or oligomer containing two acryloyl groups or methacryloyl groups in one molecule and having a weight average molecular weight of 2000 or less. Further, the resin B is a monomer or oligomer containing two or three acryloyl groups or methacryloyl groups in one molecule and having a weight average molecular weight of 3,000 or more and 20,000 or less. In the coating liquid for the base layer, the ratio (WA / WB) of the mass% (WA) of the resin A to the mass% (WB) of the resin B is 30% by mass / 70% by mass to 70% by mass / 30% by mass. It is preferably in the range of%.

In the present embodiment, as described above, as the resin A, a monomer containing two acryloyl groups or methacryloyl groups in one molecule is used, and as the resin B, two or three acryloyl groups or methacryloyl groups in one molecule. It is preferable to use a monomer containing. This is because when there is only one acryloyl group or methacryloyl group, it is difficult to form the target photocurable resin film, and tack may occur due to insufficient curing. Further, when the number of acryloyl groups or methacryloyl groups is four or more, curling may occur due to the large curing shrinkage, and the tensile elongation of the coating film may be significantly lowered.

In the base layer 8 formed by using the coating liquid for the base layer, the resin A mainly contributes to the improvement of the strength. Therefore, the photo-cured product obtained by photo-curing a coating liquid containing resin A and an ultraviolet polymerization initiator and not containing resin B has a maximum stress of 60 N / mm ² or more in a tensile test and a tensile elongation. It is preferably 10% or less. Further, in order to obtain the above tensile properties, the weight average molecular weight of the resin A is preferably 2000 or less. If the weight average molecular weight of the resin A is larger than 2000, the viscosity of the coating liquid becomes high and coating becomes difficult.

Examples of the resin A include urethane acrylate C-1 (Shin Nakamura Chemical Industry Co., Ltd.), AH-600, AT-600 (Kyoeisha Chemical Co., Ltd.) described in JP2013-159691, and UA-1280. , UA-1280MK (Shin Nakamura Chemical Industry Co., Ltd.), Shikou UV6300B, UV7620A, UV7600B (Nippon Synthetic Chemical Industry Co., Ltd.), UF-8001G (Kyoeisha Chemical Co., Ltd.) and the like can be used. That is, as the resin A, an oligomer or monomer of urethane (meth) acrylate can be used. Among these, UA-1280MK can be particularly preferably used.

Further, as the resin B, for example, purple light UV7000B, purple light UV3520 (Nippon Synthetic Chemistry Co., Ltd.) and the like can be used. That is, as the resin B, an oligomer or monomer of urethane (meth) acrylate can be used. Among these, purple light UV7000B can be particularly preferably used.
The (meth) acrylic acid ester compound contained in the base layer 8 formed by using the coating liquid for the base layer can be easily peeled off from the base material 2 such as PET to form a self-supporting film. Requires toughness and elongation. Therefore, when only oligomers or monomers other than urethane (meth) acrylate are used, problems such as large curl of the cured film and inability to peel off from the base material 2 may occur.

A compound that generates a polymerization initiator by ionizing radiation for curing the (meth) acrylic acid ester compound, that is, a photoradical polymerization initiator similar to the above-mentioned coating liquid for a silver nanoparticle layer is used as the polymerization initiator. be able to. Specifically, for example, Esacure ONE (Lamberti) can be used as the photopolymerization initiator.
The content of the polymerization initiator is preferably in the range of 0.5% by mass or more and 5% by mass or less based on the total solid content in the coating liquid for the base layer which is the coating liquid. If the content of the polymerization initiator is out of this range, the film hardness may decrease.
Further, the coating liquid for the base layer may further contain a solvent. The solvent contained in the coating liquid for the base layer can be appropriately selected from acetone, which is a ketone solvent having high compatibility with the resin A and the resin B, or methyl ethyl ketone in consideration of coating suitability and the like.

The method for forming the base layer 8 is not limited as long as the coating liquid for the base layer can be applied to the base material 2, and for example, a spin coating method, a bar coating method, a dip coating method, a spray method, or an inkjet method. And so on.
The base layer 8 may be formed by spray-coating, for example, a commercially available clear lacquer. Examples thereof include nitrocellulose lacquer, acrylic lacquer, and water-based lacquer, and those that do not attack the base material 2 are appropriately selected.

[Preparation of coating liquid for overcoat layer and formation of overcoat layer 7]
The overcoat layer 7 starts polymerization by ionizing radiation with the (meth) acrylic acid ester compound on the condition that the metallic design color of the silver nanoparticle layer 6 does not change and the adhesion to the silver nanoparticle layer 6 is good. It can be formed by using a coating liquid for an overcoat layer containing a seed-generating compound (polymerization initiator). The presence of the overcoat layer 7 can enhance the durability of the film such as light resistance and heat resistance.
Since it is desirable that the (meth) acrylic acid ester compound used in the coating liquid for the overcoat layer adheres to the silver nanoparticle layer 6 after photocuring, an oligomer containing two or more acryloyl groups or methacryloyl groups in one molecule. And monomers are preferred. If there is only one acryloyl group or methacryloyl group, the coating film is weak and the adhesion to the silver nanoparticle layer 6 may be poor. Polyester-based urethane acrylate containing a weak carboxylic acid is preferable in order to strengthen the adhesion. Specifically, UF-3003, UF-3003M, UF-3123M, UF-3223BA (Kyoeisha Chemical Co., Ltd.) and the like can be used.

As the polymerization initiator for curing the (meth) acrylic acid ester compound, a photoradical polymerization initiator similar to the coating liquid for the silver nanoparticle layer described above can be used. Specifically, for example, Esacure ONE (Lamberti) can be used as the photopolymerization initiator.
The content of the polymerization initiator is preferably in the range of 0.5% by mass or more and 5% by mass or less based on the total solid content in the coating liquid for the overcoat layer. If the content of the polymerization initiator is out of this range, the film hardness may decrease.
Further, the coating liquid for the overcoat layer may further contain a solvent. The solvent contained in the coating liquid for the overcoat layer can be appropriately selected from acetone, which is a highly compatible ketone solvent, and methyl ethyl ketone in consideration of coating suitability and the like.
Further, as the coating liquid for the overcoat layer, a melamine resin, a urethane resin, a (meth) acrylic resin, a salt-vinegar bi-resin and the like can be appropriately selected and used alone or in combination.

The method for forming the overcoat layer 7 is not limited as long as the coating liquid for the overcoat layer can be applied on the silver nanoparticle layer 6, and for example, a spin coating method, a bar coating method, a dip coating method, etc. Examples include a spray method and an inkjet method.
The overcoat layer 7 may be formed by spray-coating, for example, a commercially available clear lacquer. Examples thereof include nitrocellulose lacquer, acrylic lacquer, and water-based lacquer, and those that do not attack the silver nanoparticle layer 6 are appropriately selected.

As described above, by forming the silica nanoparticle layer 4, the silver nanoparticle layer 6 and the overcoat layer 7 in this order on the base material 2 (base layer 8), a high metal-like design laminate can be produced. can. More specifically, by using, for example, silver oxalate as a silver compound as a raw material for silver and interposing N, N-dialkylaminoalkylamine, the silver atom contained in silver oxalate is first-class diamine. A complex compound in which the amino group moiety is coordinated is formed. Then, the silver nanoparticles 5 can be prepared in high yield by thermally decomposing the portion of the oxalate ion constituting silver oxalate in this state. Further, in the silver nanoparticles 5, since the tertiary amino group that does not form a complex faces the outermost surface of the particles, the silver nanoparticles 5 are attracted to, for example, an acrylate compound or a methacrylate compound having a carboxy group by an ionic bond, so that the dispersion liquid is not disrupted. It can be prepared as (coating liquid). Further, the obtained coating liquid can be easily diluted with an organic solvent or the like, and a photopolymerization initiator or the like can be added. When a coating film (silver nanoparticle layer 6) of silver nanoparticles 5 produced on the silica nanoparticle layer 4 is formed using this coating liquid and the overcoat layer 7 is provided, the film strength is high and the substrate adherence is high. A strong cured film can be obtained.

That is, in the method for producing the metal design laminate 1 of the present embodiment, only the coating liquid for the silver nanoparticle layer is applied on the silica nanoparticle layer 4, that is, the temperature is lower than that of the prior art (approximately 100). A high metal design can be obtained in a short time (about 1 minute) at a temperature of about ° C.). Further, by providing the overcoat layer 7 on the silver nanoparticle layer 6, it is possible to obtain a laminated body in which silver (silver nanoparticles 5) is not oxidized and the metal design can be maintained for a long period of time.
Hereinafter, as examples, a method for producing silver nanoparticles 5, preparation of each coating liquid, coating, and evaluation of the metal-like design laminate 1 will be shown, but the present invention is not limited thereto.

[Example 1]
[Silver oxalate synthesis]
Add 60 mL of distilled water to 9.92 g of oxalic acid dihydrate (Kanto Chemical Co., Inc.) and dissolve while heating, and while stirring in an oil bath at 110 ° C., add 20 mL to 26.7 g of silver nitrate (Kanto Chemical Co., Inc.). Distilled water was added, and the solution was added while heating, and heating and stirring were continued for 1 hour. The precipitated silver oxalate was recovered by natural filtration, further filtered and washed with 200 mL of hot water and 50 mL of methanol (Kanto Chemical Co., Inc.), and then dried at room temperature while reducing the pressure in a light-shielding desiccator. The yield of silver oxalate thus obtained was 21.6 g (yield 90.4%).

[Synthesis of silver nanoparticles 5]
To 3.26 g of N, N-diethyl-1,3-diaminopropane (Tokyo Kasei Co., Ltd.) and 0.13 g of oleic acid, 1.90 g of silver oxalate obtained in the above step was added, and the temperature was 110 ° C. It was heated and stirred in an oil bath. Carbon dioxide effervescence 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 place, and the precipitate obtained by centrifugation was air-dried to obtain 1.48 g of a blue solid (silver standard yield 97.0%). FIG. 2 is a scanning electron microscope image of the silver nanoparticles 5 obtained in Example 1. Further, FIG. 3 is a diagram showing the particle size distribution and cumulative frequency (%) of the silver nanoparticles obtained in Example 1.

[Preparation of coating liquid 1 for silica nanoparticle layer]
Ultra-high purity colloidal silica PL-2L (average primary particle size: 16 nm) manufactured by Fuso Chemical Industry Co., Ltd. was diluted with water as a dispersion medium so as to have a solid content of 5%. Further, a 5% aqueous solution of R-1130 (silanol group-modified polyvinyl alcohol) manufactured by Kuraray Co., Ltd. was prepared. 8 g of a 5% aqueous solution of silica and 2 g of a 5% aqueous solution of R-1130PVA were taken and mixed to prepare a coating liquid 1 for a silica nanoparticle layer having a 5% solid content.

[Preparation of coating liquid 1 for silver nanoparticle layer]
0.10 g of the blue solid obtained in the above step was dispersed in 2.0 g of toluene (Kanto Chemical Co., Inc.), 0.02 g of Plysurf A208F (Daiichi Kogyo Seiyaku Co., Ltd.) was added as a dispersant, and silver nanoparticles were dispersed. Liquid (coating liquid for silver nanoparticle layer) 1 was used.
In the above step, the coating liquid 1 for the silica nanoparticle layer was applied to the base material 2 on a 75 μm thick untreated PET (Torell mirror T60) with a # 5 wire bar, and dried at an oven temperature of 120 ° C. for 1 minute. A coating liquid 1 for a silver nanoparticle layer containing silver nanoparticles 5 is applied thereto with a # 3 wire bar, dried at an oven temperature of 100 ° C. for 1 minute, and then an overcoat layer 7 is formed with a commercially available clear lacquer. By doing so, the metal-like design laminate 1 of Example 1 was obtained. FIG. 4 is a surface scanning electron microscope image when only the silica nanoparticle layer 4 obtained in Example 1 is formed on the base material 2, and FIG. 5 is a scanning electron microscope on the surface of the silver nanoparticle layer 6. It is an image, and FIG. 6 is a scanning electron microscope image in each cross section of the silver nanoparticle layer 6 and the silica nanoparticle layer 4.

[Example 2]
[Preparation of coating liquid for base layer]
A mixture of urethane acrylate compound (UA-1280MK (manufactured by Shin-Nakamura Chemical Co., Ltd.): UV7000B (manufactured by Nippon Synthetic Chemical Co., Ltd.) = 25.40 g: 8.63 g), MEK 12.96 g, photopolymerization initiator Esacure ONE (Lamberti Co., Ltd.) 0.34 g was added and dissolved to prepare a coating solution for the base layer.
The coating liquid for the base layer obtained in the above step is applied to the base material 2 75 μm thick untreated PET (Torell mirror T60) using a # 40 wire bar, and then the solvent is volatilized in an oven at 90 ° C. for 100 seconds. I let you. Put this in a purge box and do not fill it with nitrogen gas, but use a UV conveyor (Heleus, CV-110Q-G type, light source: Light Hammer 10MerkII, H bulb, hereinafter simply referred to as "UV irradiation") at 240 mJ / The same operation as in Example 1 was performed except that the base layer 8 exposed and cured in ^{cm 2 was used to obtain the metal-like design laminate 1 of Example 2.}

[Example 3]
[Synthesis of silver nanoparticles 5]
Instead of 3.26 g of N, N-diethyl-1,3-diaminopropane (Tokyo Kasei Co., Ltd.) of Example 1, n-octylamine (Tokyo Kasei Co., Ltd.) 2.26 g, n-butylamine (Tokyo Kasei Co., Ltd.) 0. The procedure was the same as in Example 1 except that a mixture of 78 g and 0.22 g of N, N-diethyl-1,3-diaminopropane (Tokyo Kasei Co., Ltd.) was used, and 1.40 g of a blue solid (silver reference yield). 91.7%) was obtained.

[Preparation of coating liquid 2 for silver nanoparticle layer]
To 0.10 g of the blue solid obtained in the above step, 2.0 g of cyclohexanone (Kanto Chemical Co., Inc.) and 0.02 g of Plysurf A208F (Daiichi Kogyo Seiyaku Co., Ltd.) as a dispersant were added, and the mixture was stirred and dispersed to obtain silver nanoparticles. The particle dispersion liquid (coating liquid for silver nanoparticle layer) 2 was used.
The same operation as in Example 1 was performed except that the above-mentioned coating liquid 2 for the silver nanoparticle layer was used instead of the coating liquid 1 for the silver nanoparticle layer of Example 1, and the metal design lamination of Example 3 was performed. Obtained body 1.

[Example 4]
[Preparation of coating liquid 2 for silica nanoparticle layer]
Ultra-high purity colloidal silica PL-3L (average primary particle size: 35 nm) manufactured by Fuso Chemical Industry Co., Ltd. was diluted with water as a dispersion medium so as to have a solid content of 5%. Further, a 5% aqueous solution of R-1130 (silanol group-modified polyvinyl alcohol) manufactured by Kuraray Co., Ltd. was prepared. 8 g of a 5% aqueous solution of silica and 2 g of a 5% aqueous solution of R-1130PVA were taken and mixed to prepare a coating liquid 2 for a silica nanoparticle layer having a 5% solid content.
The same operation as in Example 1 was performed except that the above-mentioned coating liquid 2 for the silica nanoparticle layer was used instead of the coating liquid 1 for the silica nanoparticle layer of Example 1, and the metal-like design laminate 1 of Example 4 was operated. Got

[Example 5]
[Preparation of coating liquid 3 for silica nanoparticle layer]
Ultra-high purity colloidal silica PL-3L (average primary particle size: 35 nm) manufactured by Fuso Chemical Industry Co., Ltd. was diluted with water as a dispersion medium so as to have a solid content of 5%. Further, a 5% aqueous solution of PVA-117 (fully saponified polyvinyl alcohol) manufactured by Kuraray Co., Ltd. was prepared. 8 g of a 5% silica aqueous solution and 2 g of a PVA-117 5% aqueous solution were taken and mixed to prepare a coating liquid 3 for a silica nanoparticle layer having a solid content of 5% aqueous solution.
The same operation as in Example 1 was performed except that the above-mentioned coating liquid 3 for the silica nanoparticle layer was used instead of the coating liquid 1 for the silica nanoparticle layer of Example 1, and the metal-like design laminate 1 of Example 5 was operated. Got

[Example 6]
[Preparation of coating liquid for overcoat layer]
34.03 g of polyester urethane acrylate compound UF-3003 (Kyoeisha Chemical Co., Ltd.), 12.96 g of MEK, and 0.34 g of photopolymerization initiator Esacure ONE (Lamberti) were added and dissolved to prepare a coating liquid for an overcoat layer.
The operation was carried out in the same manner as in Example 1 until the formation of the silver nanoparticle layer 6, and the solvent was volatilized in the overcoat layer coating liquid in an oven at 60 ° C. for 1 minute using a # 10 bar coater. Put this in a purge box and do not fill it with nitrogen gas, but use a UV conveyor (Heleus, CV-110Q-G type, light source: Light Hammer 10MerkII, H bulb, hereinafter simply referred to as "UV irradiation") at 240 mJ / The metal-like design laminate 1 of Example 6 was obtained by exposing and curing at cm ^2.

[Example 7]
[Preparation of coating liquid 4 for silica nanoparticle layer]
Ultra-high purity colloidal silica PL-2L (average primary particle size: 16 nm) manufactured by Fuso Chemical Industry Co., Ltd. was diluted with water as a dispersion medium so as to have a solid content of 5%. Further, a 5% aqueous solution of R-1130 (silanol group-modified polyvinyl alcohol) manufactured by Kuraray Co., Ltd. was prepared. 2 g of a 5% aqueous solution of silica and 8 g of a 5% aqueous solution of R-1130PVA were taken and mixed to prepare a coating liquid 4 for a silica nanoparticle layer having a 5% solid content.
The same operation as in Example 1 was performed except that the above-mentioned coating liquid 4 for the silica nanoparticle layer was used instead of the coating liquid 1 for the silica nanoparticle layer of Example 1, and the metal-like design laminate 1 of Example 7 was operated. Got

[Example 8]
[Preparation of coating liquid 5 for silica nanoparticle layer]
Ultra-high purity colloidal silica PL-2L (average primary particle size: 16 nm) manufactured by Fuso Chemical Industry Co., Ltd. was diluted with water as a dispersion medium so as to have a solid content of 5%. Further, a 5% aqueous solution of PVA-207 (partially saponified polyvinyl alcohol: saponification degree 86.5-89%) manufactured by Kuraray Co., Ltd. was prepared. 8 g of a 5% silica aqueous solution and 2 g of a PVA-207 5% aqueous solution were taken and mixed to prepare a coating liquid 5 for a silica nanoparticle layer having a solid content of 5% aqueous solution.
The same operation as in Example 1 was performed except that the above-mentioned coating liquid 5 for the silica nanoparticle layer was used instead of the coating liquid 1 for the silica nanoparticle layer of Example 1, and the metal-like design laminate 1 of Example 8 was operated. Got

[Comparative Example 1]
The coating liquid 1 for the silver nanoparticle layer is directly applied on the PET which is the base material 2 without providing the silica nanoparticle layer 4, dried at 100 ° C. for 1 minute, and then the overcoat layer 7 is formed with a commercially available clear lacquer. By doing so, the metal-like design laminate 1 of Comparative Example 1 was obtained.

<Evaluation of specular reflectance>
The average regular reflectance of light having an incident angle of 5 ° and a wavelength of 400 nm to 800 nm and the regular specular reflectance of light having a wavelength of 550 nm were measured using a Hitachi U4100 spectrophotometer. If the average regular reflectance is 10% or more and the regular reflectance for light of 550 nm is 40% or more, it is evaluated as "○" as having a good metal design, and the average regular reflectance is 10% or more and 550 nm. When the specular reflectance with respect to light was 35% or more, it was evaluated as "Δ", and when the value was less than that, it was evaluated as "x". In the examples, if the evaluations were "○" and "Δ", they were accepted because they could be used (recognizable) as a laminated body having a metal-like design.
These results are shown in Table 1.

As shown in Table 1, it is a laminate in which the silica nanoparticle layer 4, the silver nanoparticle layer 6, and the overcoat layer 7 are provided in this order on the base material 2, and the silica nanoparticle layer 4 is the silica nanoparticles 3 and the polyvinyl. If the silver nanoparticle layer 6 contains silver nanoparticles 5 and the overcoat layer 7 is a transparent layer containing alcohol, a laminate having a high metal design (metal design laminate) can be produced at a low temperature and short. It can be seen that it can be formed in time.

As described above, the metal-like design laminate in the present invention can be applied in a field where a metal-like design is required.

1 ... Metallic design laminate 2 ... Base material 3 ... Silica nanoparticles 4 ... Silica nanoparticle layer 5 ... Silver nanoparticles 6 ... Silver nanoparticle layer 7 ... Overcoat layer 8 ... Undercoat layer

Claims (12)

A silica nanoparticle layer, a silver nanoparticle layer, and an overcoat layer are provided on the substrate in this order.
The silica nanoparticle layer contains silica nanoparticles and polyvinyl alcohol.
The silver nanoparticle layer contains silver nanoparticles and contains
The overcoat layer is a metal-like design laminate characterized by being a transparent layer. The metal-designed laminate according to claim 1, wherein the average primary particle size (D50) of the silica nanoparticles is in the range of 5 nm or more and 100 nm or less. The silica nanoparticle layer contains the silica nanoparticles in a range of 50% by mass or more and 95% by mass or less, and the polyvinyl alcohol in a range of 5% by mass or more and 50% by mass or less with respect to the mass of the silica nanoparticle layer. Contained in
The metal-like design laminate according to claim 1 or 2, wherein the thickness of the silica nanoparticle layer is in the range of 200 nm or more and 2 μm or less, and is thicker than the film thickness of the silver nanoparticle layer. .. The polyvinyl alcohol is a completely saponified polyvinyl alcohol having a saponification degree of 98% or more, or a completely saponified polyvinyl alcohol in which a part of the hydroxyl group is modified to at least one of a silanol group and an ethylene oxide group. The metal-like design laminate according to any one of claims 1 to 3, wherein the metal-like design laminate is characterized. The average primary particle size (D50) of the silver nanoparticles is in the range of 10 nm or more and 200 nm or less.
The surface of the silver nanoparticles is covered with a plurality of protective molecules, and the surface of the silver nanoparticles is covered with a plurality of protective molecules.
The most abundant molecule among the plurality of protected molecules covering the surface of the silver nanoparticles is an alkylamine having a primary amino group or an alkyldiamine having a primary amino group and a tertiary amino group. The metal-like design laminate according to any one of claims 1 to 4, wherein the metal-like design laminate is characterized. The silver nanoparticle layer is thinner than the silica nanoparticle layer, has a film thickness in the range of 10 nm or more and 1 μm or less, and forms an island-like structure in which at least a part of the silver nanoparticle layer is discontinuous with each other. The metal-like design laminate according to any one of claims 1 to 5, wherein the metal-like design laminate is characterized by the above. From claim 1, the silver nanoparticle layer contains a binder component in addition to the silver nanoparticles in a range of 1% by mass or more and 10% by mass or less with respect to the mass of the silver nanoparticles layer. The metal-like design laminate according to any one of claim 6. Any of claims 1 to 7, wherein the metallic design laminate exhibits a metallic design color having a regular reflectance of 10% or more and a reflectance of 40% or more with respect to light at 550 nm. The metal-like design laminate according to item 1. A coating liquid for forming the silica nanoparticle layer used in the metallic design laminate according to any one of claims 1 to 8.
With at least silica nanoparticles, polyvinyl alcohol, and a dispersion medium,
The average primary particle size (D50) of the silica nanoparticles is in the range of 5 nm or more and 100 nm or less.
The dispersion medium is water.
A coating liquid for a silica nanoparticle layer, wherein the solid content is in the range of 2% by mass or more and 20% by mass or less with respect to the mass of the coating liquid. A coating liquid for forming the silver nanoparticle layer used in the metallic design laminate according to any one of claims 1 to 8.
With at least silver nanoparticles, a dispersant, and a dispersion medium,
A coating liquid for a silver nanoparticle layer, wherein the solid content is in the range of 5% by mass or more and 40% by mass or less with respect to the mass of the coating liquid. The content of the silver nanoparticles is in the range of 5% by mass or more and 40% by mass or less with respect to the mass of the dispersion medium.
The coating liquid for a silver nanoparticle layer according to claim 10, wherein the content of the dispersant is in the range of 1% by mass or more and 20% by mass or less with respect to the mass of the silver nanoparticles. .. The coating liquid for the silica nanoparticle layer according to claim 9 and the coating liquid for the silver nanoparticle layer according to claim 10 or 11 are each applied to the substrate in this order and dried. A method for producing a metal-like design laminate, which comprises forming a silica nanoparticle layer and a silver nanoparticle layer in this order.

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