JP7647582B2 - Metallic decorative sheet and metallic decorative molded body including the same - Google Patents

Description

The present invention relates to a metallic decorative sheet and a metallic decorative molded body comprising the same.

Conventionally, a metallic luster has been imparted to the surface of a molded body in order to enhance the design of the body. One known method for imparting a metallic luster is to place a decorative sheet having a metallic luster in a mold and then inject resin into the mold to adhere a metal vapor deposition sheet to the molded body (see, for example, Patent Document 1).

Patent No. 5809768

However, when a molded body was formed using the metal vapor deposition sheet having the above-mentioned metallic luster, the surface of the molded body appeared whitish, and the expected metallic luster was often not obtained.

The present invention aims to provide a metallic decorative sheet having an excellent metallic luster, and a metallic decorative molded body having the decorative sheet and having an excellent metallic luster.

As a result of the inventor's investigations, it was found that in a metallic decorative sheet having a metal layer with a so-called "sea-island structure" having multiple island parts and sea parts between the island parts, when the area ratio of the sea parts is small, whitening is likely to occur when a molded body is produced. Furthermore, it was found that the reflectance of the metallic decorative sheet changes depending on the area ratio of the sea parts. In other words, in order to obtain a metallic decorative sheet that has excellent metallic luster and can suppress whitening during molding, there is an appropriate range for the area ratio and reflectance of the sea parts, and it is necessary to appropriately control these.

That is, in order to solve the above problems, the present invention provides the following [1] to [4].
[1] A metallic tone decorative sheet having a metal layer on a base layer, the metallic layer having a plurality of island portions containing metal and a sea portion located between the island portions, the metallic tone decorative sheet satisfying the following conditional formulas (1) to (3) when the area ratio of the sea portion when the metallic layer is viewed in a plan view is X (%) and the reflectance of the metallic tone decorative sheet at a wavelength of 550 nm is Y (%).
X≧10 ... (1)
Y≧60 ... (2)
Y≦-0.4182X+73.382…(3)
[2] The metallic decorative sheet according to [1], in which, assuming that each of the island portions is circular and the average diameter calculated from the area of each of the island portions is defined as the size of the island portions, the size is 75 nm or more and 400 nm or less.
[3] The metallic decorative sheet according to [1] or [2], wherein the metal layer contains indium or tin.
[4] A metallic decorative molding having the metallic decorative sheet according to any one of [1] to [3] and an adherend.

According to the present invention, it is possible to obtain a metallic decorative sheet having excellent metallic luster, and a metallic decorative molded body having the decorative sheet.

1 is a graph showing a region that satisfies conditional expressions (1) to (3), with the horizontal axis representing the area ratio (%) of the sea portion and the vertical axis representing the reflectance (%) of the metallic decorative sheet at a wavelength of 550 nm. FIG. 2 is a diagram for explaining a thin line model used in the first embodiment. 1 is a graph showing the relationship between the area ratio of a sea portion and reflectance according to Example 1. 1 is a scanning electron microscope photograph of a metal layer in the metallic decorative sheet of Example 2. 1 is a scanning electron microscope photograph of a metal layer in the metallic decorative sheet of Example 3. 1 is a scanning electron microscope photograph of a metal layer in the metallic decorative sheet of Example 4. 1 is a scanning electron microscope photograph of a metal layer in the metallic decorative sheet of Example 5.

The metallic decorative sheet and metallic decorative molded body of the present invention will be described in detail below. Note that the numerical range notation "AA-BB" in this specification means "AA or more and BB or less."

[Metallic decorative sheet]
The metallic tone decorative sheet of the present invention is a metallic tone decorative sheet having a metal layer on a base layer, the metallic layer having a plurality of island portions containing metal and a sea portion located between the island portions, the metallic tone decorative sheet satisfying the following conditional formulas (1) to (3) when the area ratio of the sea portion when the metal layer is viewed in a plan view is X (%) and the reflectance of the metallic tone decorative sheet at a wavelength of 550 nm is Y (%).
X≧10 ... (1)
Y≧60 ... (2)
Y≦-0.4182X+73.382…(3)

The metal layer in the metallic tone decorative sheet of the present invention has an "island-sea structure" having multiple islands containing metal and a sea portion located between the island portions. Exemplary structures are shown in Figures 4 to 7, in which multiple island portions are closely packed and separated from each other by sea portions. The structures shown in Figures 4 to 7 can be seen when the metal layer of the metallic tone decorative sheet is observed with a scanning electron microscope. The metallic layer having an island-sea structure can provide a metallic tone decorative sheet that has a metallic luster while transmitting electromagnetic waves in the radar wavelength range.

[Ratio of sea area]
In the present invention, the area ratio X (%) of the sea portion can be determined by the following method.
First, the surface of the metal layer is observed with an electron microscope under the following conditions to obtain an image.
Equipment: Scanning electron microscope Observation conditions Acceleration voltage: 5 kV
Emission current: 10 μA
Pixel size: 9.5-10.0 nm
Working distance: 15mm
Observation magnification: 10,000 times Gradation: 8 bits

800,000 to 900,000 pixels were cut out from the image obtained under the above conditions. The cut-out image was then binarized using Otsu's method. The ratio of the area of the sea portion to the entire cut-out image was taken as the area ratio (%) of the sea portion of that portion. This process was carried out at 20 locations on the image, and the average value of the 20 locations was taken as the area ratio X (%) of the sea portion of the metal layer.

[Reflectance of metallic decorative sheet]
The reflectance Y (%) in the present invention is a value when light having a wavelength of 550 nm is incident from the substrate layer side, and can be obtained using a spectrophotometer. Note that, in the present invention, the reflectance Y (%) is a value when the incident angle is 5 degrees.

[Conditional formulas (1) to (3)]
The metallic decorative sheet of the present invention is required to satisfy the above-mentioned conditional expressions (1) to (3).
Conditional formula (1) is a regulation of the area ratio of the sea part. A small area ratio of the sea part means that adjacent island parts are close to each other. When a metallic decorative sheet is bonded by injection molding or attached to a molded body to manufacture a metallic decorative molded body, deformation due to the metallic decorative sheet following a three-dimensional curved surface or shrinkage of the metallic decorative sheet due to heat may occur. If the area ratio of the sea part is small and the island parts are close to each other, there is a risk that the island parts will come into contact with each other and the metallic decorative sheet will whiten. From the viewpoint of suppressing the occurrence of whitening, the area ratio of the sea part is set to 10% or more (i.e., X≧10). In order to reliably suppress the occurrence of whitening, the area ratio of the sea part is preferably 14% or more, more preferably 16% or more.
In addition, an increase in the area ratio of the sea portion means a decrease in the area ratio of the island portion (metal portion). In other words, if the area ratio of the sea portion is too large, the reflectance of the metallic decorative sheet decreases, making it difficult to obtain a metallic luster. From this viewpoint, the area ratio X of the sea portion is preferably 32% or less, and more preferably 30% or less.

Conditional formula (2) specifies the reflectance. From the viewpoint of obtaining a metallic decorative sheet having excellent design with a metallic luster, the reflectance is set to 60% or more (i.e., Y≧60). Y is preferably 61% or more, and more preferably 62% or more. The reflectance tends to decrease as the area ratio of the sea portion increases. From the viewpoint of making it easier to satisfy conditional formula (1), Y is preferably 69.2% or less, more preferably 68.1% or less, more preferably 66.5% or less, and even more preferably 65.5% or less.

Conditional formula (3) is a provision that takes into consideration the decrease in reflectance due to an increase in the area of the sea portion. By increasing the size of the island portion, the absorption of visible light by the island portion containing metal is suppressed, and the reflectance can be increased. On the other hand, if the area ratio of the sea portion is increased, even if the size of the island portion is increased to eliminate the effect of absorption, the amount of transmitted light increases, and the reflectance decreases. In addition, if the island portion is too large, diffused light from the edge of the island portion may be visible even if the area ratio of the sea portion is adjusted, and there is a risk of a rough metallic luster. In consideration of these, the present invention requires that the area ratio of the sea portion and the reflectance satisfy condition (3).

When the area ratio X (%) of the sea portion is on the x-axis and the reflectance Y (%) is on the y-axis, the area satisfying conditional expressions (1) to (3) corresponds to the area indicated by the bold frame and shaded area in Figure 1.

It is preferable that the metallic decorative sheet of the present invention further satisfies the following conditional formula (4).
Y≧-0.75X+70.5…(4)
Conditional formula (4) is a provision that takes into consideration the reduction in reflectance and the suppression of the occurrence of whitening. Specifically, when the size of the island portion is small, the reflectance tends to decrease. In particular, when the size of the island portion is small (for example, the size of the island portion is 75 nm or less), the change in reflectance due to the variation in the size of the island portion and the area ratio of the sea portion tends to be significant. By satisfying conditional formula (4), even if the size of the island portion and the area ratio of the sea portion change due to the fluctuation of the manufacturing conditions of the metallic tone decorative sheet, the fluctuation range of the reflectance of the obtained metallic tone decorative sheet can be reduced. In addition, since the area ratio of the sea portion is small, the island portions are densely formed, so that the island portions are likely to come into contact with each other during molding. By satisfying conditional formula (4), the occurrence of whitening during molding can be reliably suppressed.

[Example of layer structure of metallic decorative sheet]
Specific examples of the metallic decorative sheet include the following structures (1) to (8). Note that "/" indicates the boundary between layers.
(1) Substrate layer/metal layer/adhesive layer (2) Substrate layer/metal layer/adhesive layer/peeling layer (3) Substrate layer/primer layer/metal layer/adhesive layer (4) Substrate layer/primer layer/metal layer/adhesive layer/peeling layer (5) Substrate layer/metal layer/adhesive layer/backer layer (6) Substrate layer/primer layer/metal layer/adhesive layer/backer layer (7) Substrate layer/metal layer/adhesive layer/backer layer/adhesive layer (8) Substrate layer/primer layer/metal layer/adhesive layer/backer layer/adhesive layer The structure of each layer is described in detail below.

<Base layer>
The substrate layer serves as a support for the metallic decorative sheet. In addition, the substrate layer is preferably disposed on the outermost side when the decorative molding is formed. Therefore, the substrate layer serves to impart scratch resistance to the metallic decorative sheet and the metallic decorative molding. In this case, it is preferable that the substrate layer has transparency from the viewpoint of being able to visually confirm the metal layer.

As the base layer, it is preferable to use a plastic film containing a resin such as a polyolefin resin such as polyethylene or polypropylene, a vinyl resin such as polyvinyl chloride, polyvinylidene chloride, polyvinyl alcohol, ethylene-vinyl acetate copolymer or ethylene-vinyl alcohol copolymer, a polyester resin such as polyethylene terephthalate, polyethylene naphthalate or polybutylene terephthalate, an acrylic resin such as polymethyl (meth)acrylate or polyethyl (meth)acrylate, a styrene resin such as polystyrene, a polyamide resin represented by nylon 6 or nylon 66, or an ABS resin (acrylonitrile-styrene-butadiene copolymer resin).
Among these, it has excellent weather resistance and moldability, and has a low refractive index, making it highly transparent.
In addition, an acrylic resin film is preferable because scratches are less noticeable.

The resin component forming the base layer may be one type or a mixture of two or more types. The base layer may be formed of a single layer film of these resins, or may be formed of a multilayer film of the same or different resins, but is preferably formed of a single layer film.
In the present invention, "(meth)acrylic" is a general term for "acrylic" and "methacrylic", and other similar terms with (meth) attached thereto have the same meaning.

In order to improve adhesion to the metal layer and the primer layer described below, the substrate layer may be subjected to a physical or chemical surface treatment such as an oxidation method or a roughening method on one or both sides as necessary. Examples of the oxidation method used as the surface treatment of the substrate layer include corona discharge treatment, plasma treatment, chromium oxidation treatment, flame treatment, hot air treatment, and ozone ultraviolet treatment. Examples of the roughening method used as the surface treatment of the substrate layer include sandblasting and solvent treatment. These surface treatments are appropriately selected depending on the type of resin component that constitutes the substrate layer, but from the viewpoints of effect and operability, a corona discharge treatment is preferred.

The substrate layer preferably has a haze according to JIS K7136:2000 of 5% or less, more preferably 3% or less, and even more preferably 1% or less.
Furthermore, the substrate layer preferably has a visible light transmittance according to JIS K7361-1:1997 of 85% or more, and more preferably 90% or more.

The thickness of the base layer is set appropriately depending on the application of the metallic decorative sheet, but is usually about 50 to 250 μm, preferably about 60 to 150 μm, and more preferably about 70 to 125 μm. If the thickness of the base layer is within the above range, the metallic decorative sheet can be provided with even better three-dimensional formability, designability, etc.

<Metal Layer>
The metal layer is provided on the base layer and provides the metallic decorative sheet with a metallic luster. The metal layer of the present invention has a sea-island structure having a plurality of islands containing metal and a sea portion located between the islands, as exemplified in Figures 4 to 7.
The metal layer of the present invention preferably has electromagnetic wave transparency that transmits electromagnetic waves of radar wavelengths. Specifically, the transmittance of electromagnetic waves with a frequency of 76.5 GHz is preferably 90% or more, more preferably 93% or more. Also, the transmittance of electromagnetic waves with a frequency of 100 kHz is preferably 93% or more, more preferably 95% or more.

In the present invention, from the viewpoint that a sea-island structure is easily formed by forming a metal layer by vapor deposition, it is preferable that the metal layer contains at least one of indium, tin, gold, and an alloy thereof. It is more preferable that the metal layer contains a metal having a melting point of 240°C or less, and it is more preferable that the metal layer contains indium or tin. Among them, indium has a low melting point and tends to easily form a sea-island structure. In addition, a metal layer made of indium is also preferable in that it has excellent metallic luster and good weather resistance.

The reason why a metal layer containing indium or tin is likely to form a sea-island structure is presumed to be as follows.
When a metal with a relatively low melting point is used to form a film by a deposition method or the like, it takes a relatively long time for the metal that has reached the substrate surface to solidify. The higher the substrate temperature during deposition, the longer the time until solidification. For this reason, it is considered that the metal before solidification moves on the substrate surface, collides with other metals, and combines to form islands. It is considered that the islands then grow by incorporating metal that has reached the substrate surface while repeating collisions and combinations, thereby forming a sea-island structure. In particular, indium and tin have extremely low melting points of 156°C and 232°C, respectively. For this reason, it is considered that the solidification rate on the substrate surface is slow and the above-mentioned collisions and combinations occur frequently, making it easier to form a sea-island structure.

Methods for forming metal layers include physical vapor deposition (PVD) methods such as vacuum deposition, sputtering, and ion plating, as well as chemical vapor deposition (CVD) methods such as plasma CVD, which uses plasma, and catalytic chemical vapor deposition (Cat-CVD), which uses a heated catalyst to catalytically decompose a material gas. Of these, vacuum deposition is preferred because it can be used on any material. In other words, physical vapor deposition films are preferred as metal layers, and vacuum deposition films are more preferred among these.

From the viewpoints of metallic luster and moldability, each island portion is preferably formed to have a thickness of 30 to 100 nm, and more preferably 40 to 80 nm.
The thickness of each island portion can be adjusted, for example, by the deposition time, that is, by increasing the deposition time, the thickness of each island portion can be increased.

In the metal layer of the present invention, assuming that each island is circular and the average diameter calculated from the area of each island is defined as the "island size", the island size is preferably 75 nm or more and 400 nm or less.
When the size of the island portion as defined above is 75 nm or more, a high reflectance (60% or more) can be obtained when the area ratio X of the sea portion is 10% or more. As a result, a metallic decorative sheet with excellent metallic luster can be obtained. Furthermore, by setting the size of the island portion to 160 nm or more, more preferably 200 nm or more, it becomes easier to obtain a metallic decorative sheet in which a metal layer with a higher reflectance is formed.
On the other hand, the larger the size of the island portion, the larger the area occupied by the island portion, so the area ratio of the sea portion tends to decrease relatively. In this case, there is a risk of whitening of the metallic decorative sheet due to contact between the island portions during molding. In addition, when the metallic decorative sheet is stretched during molding, there is a risk of the island portions cracking, resulting in a decrease in the metallic luster. Furthermore, if the size of the island portion is too large, the width of the sea portion (i.e., the spacing between the island portions) becomes large, and diffused light from the edge of the island portion may be visible. As a result, the metallic luster becomes rough, and there is a risk that the desired aesthetic appearance cannot be obtained. From the viewpoint of suppressing these, it is preferable to set the size of the island portion to 350 nm or less, and more preferably to set it to 300 nm or less.

The area of each island can be calculated by the following method.
First, an electron microscope image of the metal layer surface is obtained under the same conditions as those for calculating the area ratio of the sea portion, and the image is subjected to a binarization process.

Next, a square frame that can hold 50 to 100 islands is placed on the photograph. The length of one side of the frame is L [nm]. "L" represents the actual size on the sample, and can be calculated based on, for example, the pixel size or scale bar of the SEM photograph.
Next, count the number of islands that are entirely contained within the frame ( _n1 ), the number of islands that are recognized to exist within the frame with 1/2 or more but less than 1/2 of their area ( _n2 ), and the number of islands that are recognized to exist within the frame with less than 1/2 of their area ( _n3 ). Based on the counted _n1 , _n2 , and _n3 , "n" shown in the following formula (i) is assumed to be the number of islands present within the frame.
n=n ₁ +(3n ₂ +n ₃ )/4 (i)
Next, the total area of the islands in the frame is calculated, and this total area is designated as "S [nm ² ]".
Then, based on S [nm ² ] and the number (n) of islands within the frame calculated by formula (i), "a" shown in the following formula (ii) is assumed to be the area [nm ² ] of each island within the frame.
a = S / n (ii)

As shown in the electron microscope photographs of Figures 4 to 7, the islands have an indefinite shape. For this reason, in calculating the island size in this specification, each island is assumed to be circular. The diameter of an island assumed to be circular is defined as the "island size."
In this specification, the size d [nm] of the island is calculated from the area a [ ^nm2 ] of each island at 20 locations using formula (iii). The average value of "d" at 20 locations is defined as the size D [nm] of the island in this specification.
d=(4a/π) ^1/2 (iii)

The area ratio of the sea portion and the size of the island portion can be adjusted by the deposition time, the substrate temperature during deposition, the material of the substrate layer, the material of the primer layer described below, etc. Specifically, by increasing the deposition time, the size of the island portion can be increased while the area ratio of the sea portion can be reduced. A higher substrate temperature during deposition tends to result in a smaller island portion size and a larger area ratio of the sea portion.

<Adhesive Layer>
The metallic decorative sheet of the present invention may have an adhesive layer in order to adhere the substrate layer having the metallic layer formed thereon to an adherend. In this case, the adhesive layer is provided on the surface of the metallic layer opposite to the substrate.
The adhesive layer is preferably made of a heat-sensitive or pressure-sensitive resin, in other words, the adhesive layer is preferably a so-called heat-sensitive adhesive layer or pressure-sensitive adhesive layer.

The resin used in the adhesive layer is preferably a general-purpose acrylic resin, a urethane resin, a polyester resin, a silicone resin, a vinyl chloride resin, a vinyl acetate resin, or a mixture or copolymer of two or more of these. From the viewpoint of adhesive strength, an acrylic resin is more preferable.
In the case of a heat-sensitive adhesive layer, the thickness is preferably 0.5 to 3 μm, more preferably 0.5 to 1.5 μm, and in the case of a pressure-sensitive adhesive, the thickness is preferably 20 to 100 μm, more preferably 30 to 60 μm.

The glass transition temperature Tg of the adhesive layer is preferably from 0 to 30°C, more preferably from 5 to 28°C, and even more preferably from 10 to 26°C.
By setting the glass transition temperature to 0° C. or higher, it is easy to improve the resistance to chipping (chipping resistance), and also to improve heat resistance, which makes it easy to prevent the surface smoothness of the decorative molding from decreasing. Furthermore, by setting the glass transition temperature to 30° C. or lower, it is easy to prevent the chipping resistance from decreasing due to a decrease in adhesion. Furthermore, when the glass transition temperature is 0 to 30° C., it is easy to balance the chipping resistance of the decorative molding and the surface smoothness of the metallic decorative sheet at high temperatures.

<Primer layer>
The primer layer is a layer that is provided as necessary for the purposes of improving adhesion between the metal layer and a layer adjacent to the metal layer (e.g., a substrate layer), suppressing deterioration of the metal layer due to components (e.g., chlorine components) contained in a layer adjacent to the metal layer, and serving as a base when the metal layer is formed by vapor deposition.
The material of the primer layer is not particularly limited, but from the viewpoint of minimizing the influence on reflectance, it is preferable that the primer layer is formed of a material having a small refractive index difference from that of the substrate layer. Examples of materials for the primer layer include resins such as acrylic resins, polyurethane resins, acrylic-urethane copolymer resins, and polyester resins. When the substrate layer contains an acrylic resin, it is preferable that the primer layer contains an acrylic resin in order to improve adhesion with the metal layer. Furthermore, when the substrate layer, the primer layer, and the metal layer are in direct contact with each other in this order, it is preferable that the primer layer is a layer containing an acrylic polyol and an isocyanate in order to prevent the sea-island structure from being affected by the primer layer.
The primer layer may contain additives such as an ultraviolet absorber and a light stabilizer.

The thickness of the primer layer is not particularly limited, but is usually about 0.5 to 2.5 μm, preferably about 1 to 2 μm.

<Release Layer>
The metallic decorative sheet may have a release layer on the surface of the adhesive layer opposite the substrate for the purpose of protecting the adhesive layer. The release layer is easily peelable from the adhesive layer when the decorated molded product is produced by a vacuum molding method.
The release layer preferably contains a release agent to improve the releasability. For example, the release layer may be a layer containing a release agent and a binder resin. As the release agent, a melamine resin-based release agent, a silicone-based release agent, a fluororesin-based release agent, a cellulose resin-based release agent, a urea resin-based release agent, a polyolefin resin-based release agent, a paraffin-based release agent, an acrylic resin-based release agent, and a composite release agent thereof are preferable. Among these, a silicone-based release agent is particularly preferable. As the binder resin, a thermoplastic resin is preferably used, and examples thereof include an acrylic resin, a polyester resin, a cellulose derivative resin, a polyvinyl acetal resin, a polyvinyl butyral resin, a vinyl chloride-vinyl acetate copolymer, and a chlorinated polyolefin resin.
The release layer can be formed by applying and drying an ink prepared by dissolving or dispersing the above-mentioned release agent and binder resin together with necessary additives in an appropriate solvent using a known method such as gravure coating, roll coating, comma coating, gravure printing, screen printing, or gravure reverse roll coating.

Alternatively, the release layer may be a release film having a release layer containing the above-mentioned release agent provided on one side of a known resin film such as a polyester film.

<Backer layer>
The metallic decorative sheet may have a backer layer on the inner layer side of the metal layer (opposite the base layer across the metal layer). The backer layer has the role of improving the strength of the metallic decorative sheet and maintaining the shape of the metallic decorative molded body formed from the metallic decorative sheet.

The thickness of the backing layer is not particularly limited and may be appropriately selected, for example, in the range of 0.1 to 10 mm. Note that multiple backing layers may be laminated on the inner layer side of the metal layer.

The backer layer may be transparent, but is preferably achromatic (gray, black) other than white, and more preferably black, in order to suppress surface reflection of the backer layer.
The backer layer preferably contains a pigment to make it achromatic. The pigment in the backer layer may be a black pigment alone or a mixture of a black pigment and another pigment (such as a white pigment).

Examples of binder resins for the backer layer include polyolefin resins such as polyethylene, polypropylene, polybutene, polymethylpentene, ethylene-propylene copolymer, ethylene-propylene-butene copolymer, and olefin-based thermoplastic elastomers, ABS (acrylonitrile-butadiene-styrene copolymer) resin, styrene resin, vinyl chloride resin, acrylic resin, and polycarbonate resin. Among these binder resins, it is preferable to contain ABS resin from the viewpoint of suppressing cracks during molding. The proportion of ABS resin to the total binder resin of the backer layer is preferably 50% by mass or more, more preferably 70% by mass or more, and even more preferably 90% by mass or more.

If necessary, any additives can be added to the backing layer, such as light stabilizers such as ultraviolet absorbers, plasticizers, fillers, antioxidants, lubricants, and antistatic agents.

The backer layer preferably has a thermal shrinkage rate of 1.0% or less when heated at 75°C for 30 minutes, more preferably 0.5% or less, and even more preferably 0.1% or less. By reducing the thermal shrinkage rate of the backer layer, it is possible to easily suppress the decrease in metallic luster caused by the backer layer.

<Other demographics>
The metallic decorative sheet may have layers other than those exemplified above, as long as they do not significantly affect the reflectance.

[Metallic decorative molding]
The metallic decorative molded article of the present invention is formed by integrating an adherend with the metallic decorative sheet of the present invention. When the metallic decorative sheet has an adhesive layer, the adhesive layer is located on the adherend side.

<Adherend>
The adherend to be used for the metallic decorated molded article of the metallic decorated sheet of the present invention is not particularly limited, and examples thereof include molded articles made of glass, ceramics, resin, and the like.
The adherend may be one that has been molded in advance into the shape of the molded article, or may be formed into the shape of the molded article during decorative molding by vacuum molding, insert molding, or the like.
The thickness of the adherend is not particularly limited, but is usually 1 mm or more, and preferably 1 to 10 mm.

[Method of manufacturing metallic decorative molding]
For example, a metallic decorative molded body can be produced by vacuum forming including the following steps (y1) to (y2).
(y1) A laminate is prepared by attaching the adhesive layer side of the metallic decorative sheet to an adherend.
(y2) The laminate is placed with the adherend side facing a mold and vacuum molded.

Next, the present invention will be described in more detail using examples, but the present invention is not limited to these examples in any way.

[Example 1]
For the thin-line model shown in FIG. 2, the reflectance (%) of the metallic decorative sheet at a wavelength of 550 nm was calculated by simulation based on the Rigorous Coupled Wave Analysis (RCWA) method when the size of the island part and the area ratio of the sea part of the metal layer were changed.

In the above simulation, the sea-island structure was simplified to one dimension. In the above simulation, the layer structure of the metallic decorative sheet was a base layer (PMMA)/metal layer (indium vapor deposition film). The light-emitting surface was placed on the base layer side, and it was set that light was perpendicularly incident on the base layer (incident angle 5°).

It is defined as the length of the metal layer portion in the direction perpendicular to the light incidence direction (symbol Lm in Figure 2). In the thin-line model of Figure 2, the ratio x (%) of the sea portion is defined as x = (Ls - Lm) / Ls × 100, where x is the length of the base layer portion in the direction perpendicular to the light incidence direction (symbol Ls in Figure 2). The ratio of the sea portion in the thin-line model was considered to correspond to the area ratio X (%) of the sea portion when the metallic decorative sheet (metal layer) is viewed in plan.

The parameters used in the calculation are shown below.
Optical constants of the substrate layer: n=1.49, k=0
Thickness of substrate layer: 1.0 μm
Optical constants of metal layer: n=1.0556, k=4.9524
Metal layer thickness: 50 nm
Island size: 50 nm to 400 nm
Sea area ratio: 0-31%

3 is a graph showing the relationship between the area ratio of the sea portion and the reflectance obtained in the above simulation. The horizontal axis represents the area ratio of the sea portion, and the vertical axis represents the reflectance. In FIG. 3, the region represented by the conditional expressions (1) to (3) is indicated by a thick frame and shaded area.
According to Fig. 3, in a metallic decorative sheet in which a metal layer having a sea-island structure is formed on a base layer, the reflectance tends to decrease as the area ratio of the sea portion increases. In all cases in which the island size of the metal layer (indium vapor deposition film) is 75 nm or more, the reflectance was 60% or more by setting the area ratio of the sea portion to a predetermined value. That is, it was confirmed from Fig. 3 that when the island size of the metal layer (indium vapor deposition film) is 75 nm to 400 nm, a metallic decorative sheet having a high reflectance of 60% or more can be obtained by appropriately adjusting the area ratio of the sea portion.

[Example 2]
An indium vapor deposition film was formed on a PMMA substrate (manufactured by S-Carbo Sheet Co., Ltd., product name "Technoloy Film S001G", width 1 m, thickness 125 μm) under the vapor deposition conditions shown in Table 1 to obtain a metallic decorative sheet of Example 2. The vapor deposition was performed using a vapor deposition apparatus of a resistance heating vapor deposition type (manufactured by ULVAC, Inc., EX-200). The pressure inside the chamber at the start of vapor deposition was 1.0 × 10 ^-3 Pa.

[Examples 3 and 5]
An indium vapor deposition film was formed under the same conditions as in Example 2 except that the vapor deposition conditions shown in Table 1 were used, and metallic decorative sheets of Examples 3 and 5 were obtained.

[Example 4]
Corona treatment was performed on one surface of the same PPMA substrate as in Example 2. The corona treatment was performed using a corona treatment device equipped with a feeding/winding device under the conditions of an output of 100 W, a substrate-electrode distance of 1.5 mm, and a substrate conveying speed of 20 m/min.
Next, an indium vapor deposition film was formed on the corona-treated surface of the substrate under the same conditions as in Example 2, except that the conditions were as shown in Table 1, to obtain a metallic decorative sheet of Example 4.

[Example 6]
A primer layer-forming coating solution 1 having the following formulation was prepared.
The primer layer forming coating solution 1 was applied to the same PPMA substrate as in Example 2, and dried to form a primer layer having a thickness of 2 μm. An indium vapor deposition film was formed on the primer layer formed under the same conditions as in Example 2, except that the conditions shown in Table 1 were used, to obtain the metallic decorative sheet of Example 6.
<Coating liquid 1 for forming primer layer>
Polyester resin (manufactured by Showa Ink Industrial Co., Ltd., product name SIVM HS) 100 parts by mass Isocyanate compound (manufactured by Showa Ink Industrial Co., Ltd., product name OP No. 81) 5.0 parts by mass Solvent (manufactured by Showa Ink Industrial Co., Ltd., product name: Chemical X-NT Solvent) appropriate amount

[Comparative Example 1]
An indium vapor deposition film was formed under the same conditions as in Example 2 except that the vapor deposition conditions shown in Table 1 were used, and a metallic decorative sheet of Comparative Example 1 was obtained.

1. Electron Microscope Observation Samples were cut out from the metallic decorative sheets of Examples 2 to 6 and Comparative Example 1, and the indium vapor deposition film surface was observed with an electron microscope to obtain images. The observation conditions are described below.
Equipment: Scanning electron microscope (Hitachi High-Technologies Corporation, SU8040)
Observation conditions Acceleration voltage: 5 kV
Emission current: 10 μA
Pixel size: 9.5-10.0 nm
Working distance: 15mm
Observation magnification: 10,000 times Gradation: 8 bits Electron microscope images of the metal layers of Examples 2 to 5 are shown in FIGS. 4 to 7, respectively.

2. Calculation of the area ratio of the sea portion 800,000 pixels were cut out from the electron microscope images of the metallic decorative sheets of Examples 2 to 6 and Comparative Example 1 obtained under the conditions described in 1 above. The cut-out images were binarized based on Otsu's method to calculate the area ratio X (%) of the sea portion. This operation was performed on 20 points on the image, and the average value of the 20 points was taken as the area ratio X (%) of the sea portion of the metal layer of Examples 2 to 6 and Comparative Example 1. The results are shown in Table 1.

3. Measurement of island size The island size D [nm] was calculated from the binarized image obtained in 2. above according to the method described above. The results are shown in Table 1.

4. Reflectance Measurement Samples were cut out from the metallic decorative sheets of Examples 2 to 6 and Comparative Example 1, and a spectrophotometer (spectrophotometer) (manufactured by JASCO Corporation, product name: V-670) was used to measure the reflectance of the sample at a wavelength of 550 nm by irradiating the sample with measuring light from the base layer (PMMA) side at an incident angle of 5 degrees.
The reflectance (wavelength 550 nm) of samples cut out from 10 locations on each sheet was measured, and the average value was taken as the reflectance Y (%) of the metallic decorative sheets of Examples 2 to 6 and Comparative Example 1. The results are shown in Table 1.

5. Observation of whitening during molding Using the metallic decorative sheets of Examples 2 to 6 and Comparative Example 1, metallic decorated molded bodies were obtained by injection molding. Methacrylic resin was used as the injected resin. The shape of the molded body was a flat plate of 10 cm x 15 cm. The resin temperature during injection was 240°C.
The surface of the obtained metallic decorative molding was visually observed, and the whitening of the metallic decorative sheet was evaluated according to the following criteria. The results are shown in Table 1.
A: No whitening was observed. B: Slight whitening was observed. C: Whitening was observed throughout the specimen.

3 shows plots for Examples 2 to 6 and Comparative Example 1. It can be seen that all of the Examples fall within the ranges represented by conditional expressions (1) to (3).
The plot for Example 2 (island size: 246 nm) is close to the graph obtained by simulation for an island size of 250 nm. Also, for example, Example 4 (island size: 122 nm) is located between the graphs obtained by simulation for an island size of 100 nm and for an island size of 150 nm. Thus, there is a strong correlation between the results of the simulation using the one-dimensional thin-wire model and the sample, and the results are almost in agreement with the simulation results.

As shown in Table 1, it was confirmed that by using the metallic decorative sheets of Examples 2 to 6, whitening during molding was suppressed.

Claims (4)

A metallic decorative sheet having a metal layer on a base layer,
the metal layer has a plurality of island portions containing a metal and a sea portion located between the island portions,
The metal layer contains a metal having a melting point of 240° C. or less,
When the area ratio of the sea portion when the metal layer is viewed in a plane is X (%) and the reflectance of the metallic decorative sheet at a wavelength of 550 nm is Y (%), the metallic decorative sheet satisfies the following conditional formulas (1) to (3).
X≧10 ... (1)
Y≧60 ... (2)
Y≦-0.4182X+73.382…(3) The metallic decorative sheet according to claim 1, in which, assuming that each of the islands is circular and the average diameter calculated from the area of each island is defined as the size of the island, the size is 75 nm or more and 400 nm or less. The metallic decorative sheet according to claim 1 or 2, wherein the metal layer contains indium or tin. A metallic decorative molded body having the metallic decorative sheet according to any one of claims 1 to 3 and an adherend.

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