JP2023058085A - Pearl color-developing scale-like particles, ink, and coating film - Google Patents

Abstract

To provide a pearl color-developing scale-like particles, an ink, and a coating film that realize excellent pearl color development by optimizing the thickness of each layer in a three-layer configuration with a first zinc sulfide layer, a magnesium fluoride layer, and a second zinc sulfide layer in this order.SOLUTION: The present invention provides pearl color-developing scale-like particles, each of which sequentially comprises a first zinc sulfide layer, a magnesium fluoride layer, and a second zinc sulfide layer in this order, wherein: the first zinc sulfide layer has an average thickness of 30 nm or more; the magnesium fluoride layer has an average thickness of 25 nm or more; the second zinc sulfide layer has an average thickness of 30 nm or more; and the average total thickness of the three layers, namely the first zinc sulfide layer, the magnesium fluoride layer and the second zinc sulfide layer, is 330 nm or less.SELECTED DRAWING: None

Description

TECHNICAL FIELD The present invention relates to pearl-colored scale-like particles, inks, and coating films.

BACKGROUND ART Conventionally, various light interference pearl pigments have been used in the fields of paints, plastics, printing inks, cosmetics and the like. As the pearl pigments, those obtained by coating the surface of scale-like powder as a base material with titanium oxide, iron oxide, or the like are known.

Further, Patent Document 1 discloses that optically variable flakes having a three-layer structure of ZnS/MgF ₂ /ZnS exhibit pearl coloration (paragraph [0010], see Table 1). Further, Patent Document 1 discloses that the total average thickness of the three layers of ZnS/MgF ₂ /ZnS is 0.5 μm (500 nm) or less, and that the average particle size of the flakes is within the range of 2 μm to 20 μm. (see paragraph [0037]). Furthermore, Patent Literature 1 discloses that a vapor deposition method and a sputtering method are used as a method for forming a three-layer structure of ZnS/MgF ₂ /ZnS (see paragraph [0024]).

JP-A-8-58224

However, the ZnS/MgF ₂ /ZnS three-layer structure flakes of Patent Document 1 are mainly used for anti-counterfeiting cards, and ink can be applied by a bar coat printing method, a screen printing method, or the like. (see paragraph [0037]) and is not used for inkjet printing. When inkjet printing is performed using an ink containing flakes having an average particle size of 2 μm to 20 μm as in Patent Document 1, ejection stability is extremely poor due to the size of the nozzle diameter of the inkjet printer head and the dispersion stability. may become Furthermore, the flake consisting of three layers of ZnS/MgF ₂ /ZnS in Patent Document 1 is described as having a total average thickness of 0.5 μm (500 nm) or less. There is no description of the average thickness, and no attempt is made to optimize the thickness of each of the three layers suitable for pearl coloring.

An object of the present invention is to solve the above-mentioned conventional problems and to achieve the following objects. That is, the present invention achieves excellent pearl color development by optimizing the thickness of each layer in a three-layer structure having a first zinc sulfide layer, a magnesium fluoride layer, and a second zinc sulfide layer in this order. An object of the present invention is to provide pearl-colored scaly particles, an ink, and a coating film capable of achieving the desired effect.

Means for solving the above problems are as follows. Namely
<1> Having a first zinc sulfide layer, a magnesium fluoride layer, and a second zinc sulfide layer in this order,
The average thickness of the first zinc sulfide layer is 30 nm or more,
The average thickness of the magnesium fluoride layer is 25 nm or more,
The second zinc sulfide layer has an average thickness of 30 nm or more,
The pearl-colored scale-like particles are characterized in that the total average thickness of the first zinc sulfide layer, the magnesium fluoride layer and the second zinc sulfide layer is 330 nm or less.
<2> the average thickness of the first zinc sulfide layer is 30 nm or more and 130 nm or less;
The average thickness of the magnesium fluoride layer is 25 nm or more and 60 nm or less,
The pearl-colored scale-like particles according to <1>, wherein the second zinc sulfide layer has an average thickness of 30 nm or more and 190 nm or less.
<3> The pearl-colored scaly particles according to any one of <1> and <2>, having a cumulative 50% volume particle diameter _D50 of 1.8 μm or less.
<4> The pearl-colored scale-like particles according to any one of <1> to <3>, which are for inkjet printing.
<5> An ink containing the pearl-colored scale-like particles according to any one of <1> to <4>.
<6> A coating film comprising the pearly-colored scaly particles according to any one of <1> to <4>.

According to the present invention, it is possible to solve the above-mentioned problems in the conventional art and achieve the above-mentioned objects. By optimizing the thickness of each layer, it is possible to provide pearl-colored flake-like particles, inks, and coating films capable of realizing excellent pearl color development.

FIG. 1 is a schematic diagram showing an example of the pearl-colored scale-like particles of the present invention. FIG. 2 is a front view of the coating film of Configuration 1. FIG. FIG. 3 is a view of the coating film of Configuration 1 viewed from an oblique direction. FIG. 4 is a front view of the coating film of Configuration 2. FIG. FIG. 5 is a front view of the coating film of Configuration 3. FIG. FIG. 6 is a front view of the coating film of Configuration 4. FIG. FIG. 7 is a diagram showing a method of measuring the absolute reflectance in the direction of regular reflection at 5° and the absolute reflectance in the direction of regular reflection at 45° in the deposited films of structures 1 to 4. FIG. FIG. 8 is a graph showing the results of simulation and actual measurement of the 5° regular reflectance in the deposited film of structure 1. FIG. FIG. 9 is a graph showing the results of simulation and actual measurement of the 5° specular reflectance in the deposited film of configuration 2. In FIG. FIG. 10 is a graph showing the results of simulation and actual measurement of the 5° specular reflectance in the deposited film of configuration 3. In FIG. FIG. 11 is a graph showing the results of simulation and actual measurement of the 5° regular reflectance in the deposited film of configuration 4. FIG. FIG. 12 is a graph showing the results of simulation and actual measurement of the 45° specular reflectance in the deposited film of configuration 1; FIG. 13 is a graph showing results of simulation and actual measurement of the 45° specular reflectance in the deposited film of configuration 2. FIG. FIG. 14 is a graph showing the results of simulation and actual measurement of the 45° specular reflectance in the deposited film of configuration 3; FIG. 15 is a graph showing the results of simulation and actual measurement of the 45° specular reflectance in the deposited film of structure 4. FIG. 16 is a graph showing simulation results of 5° specular reflectance of Example 1, Example A, Example D, Example E, Comparative Example F, Comparative Example G, Comparative Example H, and Comparative Example I; be. 17 is a graph showing simulation results of 5° specular reflectance for Comparative Example A, Comparative Example B, Comparative Example C, Comparative Example D, and Comparative Example E. FIG. FIG. 18 is a graph showing the relationship between the total average thickness of the first to third layers and the cumulative 50% volume particle diameter _D50 after pulverization. FIG. 19 is a schematic diagram showing a method of photographing the appearance of the coating film. FIG. 20 is a diagram showing the appearance photographs of the coating films of Compositions 1 to 4, the coating films of Compositions 5 to 8, and the coating films of other companies. FIG. 21 is cross-sectional SEM photographs of scaly particles obtained by pulverizing vapor deposition films of structures 1 to 4, scaly particles obtained by pulverizing vapor deposition films of structures 5 to 8, and a powder of another company. FIG. 22 is an enlarged cross-sectional SEM photograph of scaly particles obtained by pulverizing the deposited film of structure 2. FIG. FIG. 23 is an enlarged cross-sectional SEM photograph of scaly particles obtained by pulverizing the deposited film of structure 7. FIG. FIG. 24 is an enlarged cross-sectional SEM photograph of the powder of another company's product (SXB). FIG. 25 is SEM photographs of the particle shapes of the finely pulverized scaly particles of constitutions 1 to 4, the finely pulverized scaly particles of constitutions 5 to 8, and the products of other companies. FIG. 26 is a diagram showing the particle size distribution of finely ground scaly particles of configurations 1-4. FIG. 27 is a diagram showing the particle size distribution of the finely pulverized scaly particles of compositions 5 to 8 and the particles of another company's product. FIG. 28 is a diagram showing the 5° specular reflection spectra of each coating film of structures 1-4. FIG. 29 is a diagram showing the 45° specular reflection spectra of each coating film of configurations 1-4.

(Pearl colored scaly particles)
The pearl-colored scaly particles of the present invention have a first zinc sulfide layer, a magnesium fluoride layer, and a second zinc sulfide layer in this order, and the first zinc sulfide layer has an average thickness of 30 nm or more. wherein the average thickness of the magnesium fluoride layer is 25 nm or more, the average thickness of the second zinc sulfide layer is 30 nm or more, and the first zinc sulfide layer, the magnesium fluoride layer and the second The total average thickness of the zinc sulfide layer and the three layers is 330 nm or less.

Conventionally, as pearl pigments, for example, flakes obtained by coating the surface of mica or glass flakes with a metal oxide (such as TiO ₂ ), or a three-layer structure of TiO ₂ /SiO ₂ /TiO ₂ (high refractive index layer/low scaly particles of refractive index layer/high refractive index layer).
The flakes obtained by coating the surface of the mica or glass flakes with a metal oxide ( _TiO2, etc.) are thick, and it is difficult to make them fine enough to be inkjet-printable. There's a problem. In addition, the flakes obtained by coating the surface of the mica or glass flakes with a metal oxide (such as TiO ₂ ) have a seamless feel and feel like scaly particles obtained by finely pulverizing a vapor-deposited film having a three-layer structure of ZnS/MgF ₂ /ZnS. There is a problem that a moist feeling cannot be realized.

The ZnS/MgF ₂ /ZnS 3-layer structure scaly particles of the present invention are superior to the conventional TiO ₂ /SiO ₂ /TiO ₂ 3-layer structure scaly particles in pearl color development. This is because the TiO ₂ /SiO ₂ /TiO ₂ crystal structure of the deposited film obtained in the case of vapor deposition is an amorphous structure, so the refractive index is lower than that of the bulk. On the other hand, since ZnS/MgF ₂ /ZnS has a crystal structure, the refractive index is close to the literature value, so the difference in refractive index is large, the reflectance is high, and the pearl color development is good.

Therefore, according to the present invention, _the average By optimizing the thickness, it is possible to achieve scale-like particles exhibiting good pearl color development within the visible light wavelength range.

Here, as shown in FIG. 1, the pearl-colored scale-like particles 10 of the present invention are obtained by laminating a first zinc sulfide layer 1, a magnesium fluoride layer 2, and a second zinc sulfide layer 3 in this order. It has a three-layer structure, and the average thickness of each layer is designed to improve pearl color development, and it is pulverized to a cumulative 50% volume particle diameter _D50 suitable for inkjet printing.

<First zinc sulfide layer and second zinc sulfide layer>
The content of zinc sulfide (ZnS) in the first and second zinc sulfide layers is preferably 98% by mass or more, more preferably 99% by mass or more, and even more preferably 99.9% by mass or more.
The content of zinc sulfide in the first and second zinc sulfide layers can be measured, for example, by X-ray fluorescence analysis (XRF).

The average thickness of the first zinc sulfide layer is 30 nm or more, preferably 30 nm or more and 130 nm or less, and more preferably 30 nm or more and 120 nm or less.
The average thickness of the second zinc sulfide layer is 30 nm or more, preferably 30 nm or more and 190 nm or less, and more preferably 30 nm or more and 170 nm or less.

The average thickness of the first and second zinc sulfide layers is, for example, when manufactured by a physical vapor deposition method, the thickness at 5 to 10 locations with respect to the first and second zinc sulfide layers. It is the same as the average deposition thickness measured and averaged.
Examples of methods for measuring the average thickness of the first and second zinc sulfide layers include scanning electron microscope (SEM) observation, X-ray fluorescence analysis (XRF), and ultraviolet-visible spectroscopy.
When the average thickness is determined by the scanning electron microscope (SEM) observation, cross-sectional observation of the first and second vapor-deposited films containing zinc sulfide or scale-like particles is performed using the scanning electron microscope (SEM). , the thicknesses of the first and second zinc sulfide layers are measured at 5 to 10 locations, and the average vapor deposition thickness can be used as the average thickness.
When the average thickness is determined by the X-ray fluorescence analysis (XRF), the thicknesses of the first and second zinc sulfide layers are measured at 5 to 10 locations by quantitative analysis, and the average value is taken as the average thickness. be able to.

<Magnesium fluoride layer>
The content of magnesium fluoride (MgF ₂ ) in the magnesium fluoride layer is preferably 98% by mass or more, more preferably 99% by mass or more, and even more preferably 99.9% by mass or more.
The content of magnesium fluoride in the magnesium fluoride layer can be measured, for example, by X-ray fluorescence analysis (XRF).
The average thickness of the magnesium fluoride layer is 25 nm or more, preferably 25 nm or more and 60 nm or less, and more preferably 35 nm or more and 50 nm or less.

The total average thickness of the first zinc sulfide layer, the magnesium fluoride layer and the second zinc sulfide layer is 330 nm or less, preferably 130 nm or more and 290 nm or less.

<Other layers>
Examples of the other layers include a peeling layer for peeling the laminate composed of the first and second zinc sulfide layers and the magnesium fluoride layer from the substrate by dissolving.

The pearl coloring particles of the present invention having the magnesium fluoride layer between the first zinc sulfide layer and the second zinc sulfide layer are scaly particles, flaky particles, tabular particles, and flake-like particles. And so on.
In the present invention, the scale-like particles mean particles having a substantially flat surface and having a substantially uniform thickness in the direction perpendicular to the substantially flat surface.
The shape of the substantially flat surface is not particularly limited and can be appropriately selected according to the purpose. Polygons such as polygons, substantially octagons, and random irregular shapes are included.

The cumulative 50% volume particle diameter _D50 of the pearl-colored scaly particles is preferably 1.8 μm or less, more preferably 0.8 μm or more and 1.8 μm or less, still more preferably 0.7 μm or more and 1.7 μm or less, and 0.5 μm. More than 1.6 μm or less is particularly preferable.
The cumulative 50% volume particle diameter _D50 is a particle size corresponding to 50% of the cumulative volume distribution of the particle size distribution curve obtained by laser diffraction, and the non-spherical scale particles are assumed to be complete spheres. It is the length obtained by averaging the major axis and the minor axis of the scale-like particles when measured by However, the actual scaly particles are not spherical but scaly having long sides and short sides. Therefore, the _D50 is a value different from the actual length in the long side direction (major diameter) and the length in the short side direction (minor diameter) of the scale-like particles.
Examples of means using the laser diffraction method include a laser diffraction/scattering particle size distribution analyzer.

The ratio of the scaly particles (cumulative 50% volume particle diameter D ₅₀ (nm)/total average thickness of three layers (nm)) is preferably 5 or more, more preferably 10 or more.
In addition, the ratio of "D ₅₀ (nm) / total average thickness of three layers (nm)" in the present invention is D ₅₀ measured using a laser diffraction method, scanning electron microscope (SEM) observation, or fluorescence X It is a ratio calculated by dividing by the average thickness obtained from line analysis. Therefore, the ratio of "D ₅₀ (nm)/average thickness (nm)" is different from the parameter generally called aspect ratio.

<Method for producing pearl-colored scaly particles>
The method for producing pearl-colored scaly particles of the present invention includes forming a release layer on a substrate, forming a first zinc sulfide layer on the release layer by a vapor phase method, and forming the first zinc sulfide layer on the first zinc sulfide layer. A magnesium fluoride layer is formed on the magnesium fluoride layer by a vapor phase method, a second zinc sulfide layer is formed on the magnesium fluoride layer by a vapor phase method to obtain a laminate, and then the laminate is peeled off from the base material. and pulverize the laminate. As a result, pearl-colored scale-like particles 10 as shown in FIG. 1 can be produced efficiently.

Specifically, the method for producing pearl-colored scaly particles of the present invention includes a peeling layer forming step, a first zinc sulfide layer forming step, a magnesium fluoride layer forming step, and a second zinc sulfide layer forming step. , a peeling process, a pulverizing process, and other processes as necessary.

<Peeling layer forming step>
The release layer forming step is a step of providing the release layer on the substrate.

-Base material-
The substrate is not particularly limited as long as it has a smooth surface, and various substrates can be used. Among these, resin films, metals, and composite films of metals and resin films having flexibility, heat resistance, solvent resistance, and dimensional stability can be appropriately used.
Examples of the resin film include polyester film, polyethylene film, polypropylene film, polystyrene film, and polyimide film.
Examples of the metal include copper foil, aluminum foil, nickel foil, iron foil, and alloy foil.
Examples of the composite film of the metal and the resin film include those obtained by laminating the resin film and the metal.

-Release layer-
As the peeling layer, various organic substances and solvents such as water that can be dissolved in the later peeling process can be used. Further, if the organic material constituting the peeling layer is appropriately selected, the organic matter adhered or remained on the magnesium fluoride layer or the first and second zinc sulfide layers functions as a protective layer for the scale-like particles. It is preferable because it can be
The protective layer has a function of suppressing aggregation, oxidation, elution into a solvent, etc. of the scale-like particles. In particular, it is preferable to use the organic material used for the peeling layer as the protective layer, because it eliminates the need for a separate surface treatment step.
Examples of the organic material constituting the release layer that can be used as the protective layer include cellulose acetate butyrate (CAB), other cellulose derivatives, polyvinyl alcohol, polyvinyl butyral, polyethylene glycol, polyacrylic acid, polyacrylamide, and acrylic. Examples include acid copolymers and modified nylon resins. These may be used individually by 1 type, and may use 2 or more types together. Among these, cellulose acetate butyrate (CAB) is preferable from the viewpoint of high function as the protective layer.

The method for forming the release layer is not particularly limited and may be appropriately selected depending on the intended purpose. , knife coating method, air knife coating method, comma coating method, U comma coating method, AKKU coating method, smoothing coating method, micro gravure coating method, reverse roll coating method, 4 roll coating method, 5 roll coating method, dip coating method, curtain coating method, slide coating method, die coating method, and the like. These may be used individually by 1 type, and may use 2 or more types together.

<First zinc sulfide layer forming step>
The first zinc sulfide layer forming step is a step of forming a first zinc sulfide layer on the release layer by a vapor phase method.

Examples of the vapor phase method include a vapor deposition method and a sputtering method, which are collectively referred to as physical vapor deposition (PVD).

<Magnesium fluoride layer forming step>
The magnesium fluoride layer forming step is a step of forming a magnesium fluoride layer on the first zinc sulfide layer by a vapor phase method.

Examples of the vapor phase method include a vapor deposition method and a sputtering method, which are collectively referred to as physical vapor deposition (PVD).

<Second Zinc Sulfide Layer Forming Step>
The second zinc sulfide layer forming step is a step of forming a second zinc sulfide layer on the magnesium fluoride layer by a vapor phase method.
As described above, a laminate is formed in which the first zinc sulfide layer, the magnesium fluoride layer, and the second zinc sulfide layer are laminated in this order on the release layer of the substrate.

Examples of the vapor phase method include a vapor deposition method and a sputtering method, which are collectively referred to as physical vapor deposition (PVD).

<Peeling process>
The peeling step is a step of peeling the laminate by dissolving the peeling layer.
The solvent capable of dissolving the peeling layer is not particularly limited as long as it is capable of dissolving the peeling layer, and can be appropriately selected according to the purpose.

The solvent capable of dissolving the release layer is not particularly limited and can be appropriately selected depending on the intended purpose. Alcohols; ethers such as tetrahydrone; ketones such as acetone, methyl ethyl ketone, acetylacetone; esters such as methyl acetate, ethyl acetate, butyl acetate, phenyl acetate; ethyl cellosolve, butyl cellosolve, ethyl carbitol, butyl carbitol, ethylene Glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monoisopropyl ether, ethylene glycol monobutyl ether, ethylene glycol monohexyl ether, ethylene glycol monophenyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, diethylene glycol dimethyl ether, diethylene glycol Diethyl ether, triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, triethylene glycol monobutyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, diethylene glycol monomethyl ether Glycol ethers such as acetate; phenols such as phenol, cresol; Aliphatic or aromatic hydrocarbons such as benzene; aliphatic or aromatic chlorinated hydrocarbons such as dichloromethane, chloroform, trichloroethane, chlorobenzene, dichlorobenzene; sulfur-containing compounds such as dimethylsulfoxide; dimethylformamide, dimethylacetamide, acetonitrile, propio Examples include nitrogen-containing compounds such as nitrile and benzonitrile, and water. These may be used individually by 1 type, and may use 2 or more types together.

<Pulverization process>
The pulverizing step is a step of pulverizing the laminate separated from the substrate in the peeling step. By carrying out this pulverization step, the pearl-colored scale-like particles of the present invention are obtained.

The method used in the pulverization step is not particularly limited and can be appropriately selected according to the purpose. Examples thereof include jet mills, ball mills, bead mills, vibration mills, and ultrasonic homogenizers.
Furthermore, if necessary, various treatments may be carried out for recovery of the pearl-colored scaly particles and adjustment of physical properties. For example, the particle size of the pearl-colored scaly particles may be adjusted by classification, the scaly particles may be recovered by a method such as centrifugation or suction filtration, or the solid content concentration of the dispersion may be adjusted. good. Moreover, solvent substitution may be performed, and viscosity adjustment etc. may be performed using an additive.

<Other processes>
Examples of the other steps include a step of taking out the pulverized pearl-colored scaly particles as a dispersion, and a step of recovering the scaly particles from the dispersion.

<Dispersion>
The dispersion liquid used in the present invention contains the pearl-colored scaly particles of the present invention, and preferably contains an organic solvent and water, and further contains other components as necessary.
The dispersion may be either water-based or solvent-based, but water-based is preferred from the standpoint of environmental friendliness.

The content of the pearl-colored scale-like particles is preferably 0.1% by mass or more and 50% by mass or less with respect to the total amount of the dispersion.

-Organic solvent-
The organic solvent is not particularly limited and can be appropriately selected depending on the intended purpose. , amines, sulfur-containing compounds, and the like. These may be used individually by 1 type, and may use 2 or more types together.

Examples of the polyhydric alcohols include ethylene glycol, diethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, 3-methyl-1,3-butanediol, triethylene glycol, polyethylene glycol, polypropylene glycol, 1,2-pentanediol, 1,3-pentanediol, 1,4-pentanediol, 2 ,4-pentanediol, 1,5-pentanediol, 1,2-hexanediol, 1,6-hexanediol, 1,3-hexanediol, 2,5-hexanediol, 1,5-hexanediol, glycerin, 1,2,6-hexanetriol, 2-ethyl-1,3-hexanediol, ethyl-1,2,4-butanetriol, 1,2,3-butanetriol, 2,2,4-trimethyl-1, 3-pentanediol and the like.

Examples of the polyhydric alcohol alkyl ethers include ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, tetraethylene glycol monomethyl ether, and propylene glycol monoethyl ether. be done.

Examples of the polyhydric alcohol aryl ethers include ethylene glycol monophenyl ether and ethylene glycol monobenzyl ether.

Examples of the nitrogen-containing heterocyclic compound include 2-pyrrolidone, N-methyl-2-pyrrolidone, N-hydroxyethyl-2-pyrrolidone, 1,3-dimethyl-2-imidazolidinone, ε-caprolactam, γ- butyrolactone and the like.

Examples of the amides include formamide, N-methylformamide, N,N-dimethylformamide, 3-methoxy-N,N-dimethylpropionamide, 3-butoxy-N,N-dimethylpropionamide and the like.

Examples of the amines include monoethanolamine, diethanolamine, and triethylamine.
Examples of the sulfur-containing compound include dimethylsulfoxide, sulfolane, thiodiethanol and the like.

-Other ingredients-
The other components are not particularly limited and can be appropriately selected depending on the intended purpose. , antifoaming agents, viscosity modifiers, light stabilizers, weather stabilizers, heat stabilizers, antioxidants, leveling agents, antiseptic antifungal agents, rust inhibitors, pH adjusters and the like.

-water-
As the water, for example, pure water such as ion-exchanged water, ultrafiltrated water, reverse osmosis water, distilled water, or ultrapure water can be used.

(ink)
The ink of the present invention contains the pearl-colored scaly particles of the present invention, preferably contains a binder, and further contains other components as necessary.
The inks of the present invention may be either water-based or solvent-based.

-Pearl-colored scaly particles-
The content of the pearl-colored scale-like particles is not particularly limited with respect to the total amount of the ink, and can be appropriately selected according to the purpose.
If necessary, the ink of the present invention may contain a luster pigment other than the pearl color-developing scaly particles. Examples of other bright pigments include metallic pigments (eg, aluminum pigments), pigments obtained from natural mica (eg, pearl pigments), glass flake pigments, and the like.

-binder-
The binder is not particularly limited and can be appropriately selected depending on the purpose. Examples include polyurethane resin, polyester resin, acrylic resin, vinyl acetate resin, styrene resin, butadiene resin, styrene-butadiene resins, vinyl chloride resins, acrylic-styrene resins, acrylic-silicone resins, polyvinyl alcohol resins, polyether resins, alkyd resins, polyvinylpyrrolidone, cellulose, and the like.
When the ink contains the binder, an ink having excellent fixability and dispersibility can be obtained.
The content of the binder is not particularly limited and can be appropriately selected depending on the purpose.

As the organic solvent and water in the ink, the same organic solvent and water as in the dispersion can be used.

-Other ingredients-
The other components are not particularly limited and can be appropriately selected depending on the intended purpose.

The ink of the present invention can be applied, for example, by an inkjet method, a gravure coating method, a screen printing method, a spray coating method, a spin coating method, a blade coating method, a gravure offset coating method, a bar coating method, a roll coating method, a knife coating method, and an air knife coating method. method, comma coating method, U comma coating method, AKKU coating method, smoothing coating method, micro gravure coating method, reverse roll coating method, 4-roll coating method, 5-roll coating method, dip coating method, curtain coating method, slide It can be used for coating methods such as a coating method and a die coating method. Among these, an inkjet method, a bar coating method, a spray coating method, a gravure coating method, and a screen printing method are preferable.

(Coating film)
The coating film of the present invention contains the pearl-colored scaly particles of the present invention, preferably contains a binder, and further contains other components as necessary.
The coating film may be used as a coating film alone, or may be a coated product formed by the above-described coating method using the ink of the present invention on a substrate.
The substrate is not particularly limited and can be appropriately selected depending on the intended purpose. Window glass and films for buildings, agricultural films, and the like.

<Application>
Since the pearly-colored scaly particles of the present invention can achieve excellent pearly coloration, they can be used in a wide variety of fields, such as paints, plastics, printing, foods, cosmetics, and automobiles. .

Examples of the present invention will be described below, but the present invention is not limited to these examples.

(Experimental example 1)
<Optimization of the average thickness of each layer of the ZnS/ _MgF2 /ZnS three-layer structure by simulation>
An optimum set value for the average thickness of each layer of the three-layer structure of ZnS/MgF ₂ /ZnS of Configurations 1 to 4, which gives good pearl color development, was found by simulation. Table 1 shows the results.
As a simulator, optical thin film design software (TFV ver. 3, manufactured by Nully Software) was used, and the reflectance was obtained by simulation.
The color was evaluated by the CIE Lab color system from the obtained reflection spectrum.

(Experimental example 2)
<Preparation of pearl-colored scaly particles>
(1) As described above, the three-layer structure vapor deposition film was simulated, and the lower limit of the average thickness of each layer of Structures 1 to 4 was determined. As will be described later, it has already been confirmed that the optical characteristics (reflection spectra) of the simulated sample and the actually manufactured sample are substantially the same. Therefore, there is no problem in optimizing the average thickness of each layer through simulation.

(2) Using the average thickness of each layer of the three-layer structure of ZnS/MgF ₂ /ZnS determined by simulation, Structures 1 to 4 of three-layer vapor deposition films were actually produced.
Specifically, a solution containing 5% by mass of cellulose acetate butyrate (CAB) was applied to a polyethylene terephthalate (PET) film having an average thickness of 25 μm by gravure coating at a concentration of 0.06 g/m ² ±0.01 g/m. ² and dried at 110° C. or higher and 120° C. or lower to form a release layer.
Next, a first zinc sulfide layer having an average thickness of 40 nm was formed by depositing zinc sulfide on the release layer by a vacuum deposition method. The average thickness of the first zinc sulfide layer is an average value obtained by measuring the thickness of the first zinc sulfide layer at five locations by quantitative analysis using X-ray fluorescence analysis (XRF).
Next, a film of magnesium fluoride was formed on the first zinc sulfide layer by a vacuum deposition method to form a magnesium fluoride layer with an average thickness of 50 nm.
Next, a second zinc sulfide layer having an average thickness of 40 nm was formed on the magnesium fluoride layer by the same method as the first zinc sulfide layer.
As described above, a vapor deposition film of configuration 1 was obtained in which the release layer, the first zinc sulfide, the magnesium fluoride layer and the second zinc sulfide layer were laminated in this order on the PET film.
Vapor-deposited films of Structures 2 to 4 were also produced in the same manner as described above.

(3) Each vapor-deposited film was pulverized (pulverized as finely as possible) for inkjet printing, and the cumulative 50% volume particle diameter _D50 was 1.8 μm or less to obtain pearl-colored scaly particles of constitutions 1 to 4.
Specifically, butyl acetate was sprayed onto the PET film surface on which the vapor deposition film was formed to dissolve the release layer, and the vapor deposition film was scraped off with a doctor blade.
Next, in order to adjust the particle size, the mixture of the obtained deposited film and butyl acetate was subjected to a fine pulverization process until the target cumulative 50% volume particle size _D50 was 1.8 μm or less. .

(4) Pearl coloring inks of constitutions 1 to 4 were prepared by dispersing the above pearl coloring scaly particles in butyl acetate.
(5) A polyethylene terephthalate (PET) film (transparent) was coated with pearl colored inks of constitutions 1 to 4 using a bar coater.
(6) A black tape was attached to the half area of the PET film opposite to the ink-coated surface, and the coating films of Structures 1 to 4 were visually observed and various data measurements were performed.

Here, FIG. 2 is a front view of the coating film of Configuration 1. As shown in FIG. FIG. 3 is a view of the coating film of structure 1 viewed from an oblique direction. As shown in FIGS. 2 and 3, when the vision is changed from the front direction to the oblique direction, it is recognized that the peak wavelength of the pearl-colored reflected light shifts and the color changes.
FIG. 4 is a front view of the coating film of composition 2, and the left side is a coating obtained by applying a pearl-colored ink with a high solid content concentration of pearl-colored scaly particles in the pearl-colored ink with a bar coater. membrane.
FIG. 5 is a front view of the coating film of composition 3, and the left side is a coating obtained by applying a pearl-colored ink with a high solid content concentration of pearl-colored scaly particles in the pearl-colored ink with a bar coater. membrane.
FIG. 6 is a front view of the coating film of composition 4, and the left side is a coating obtained by applying a pearl-colored ink with a high solid content concentration of pearl-colored scaly particles in the pearl-colored ink with a bar coater. membrane.

(Experimental example 3)
<Comparison between simulation and actual measurement (evaporation film)>
-simulation-
As a simulator, optical thin film design software (TFV ver. 3, manufactured by Nully Software) was used to obtain simulated reflectance values.
The reflectance is the absolute reflectance in a 5° regular reflection direction when light is incident at an angle inclined by 5° from the normal direction of each deposited film. Also, the absolute reflectance is calculated by the following formula.
Absolute reflectance = (amount of light reflected by sample/amount of light used) x 100
The absolute reflectance is the reflectance when the reflectance of air is 100%.

-Actual measurement (evaporation film)-
When measuring the reflectance, as shown in FIG. 7, the reflectance of a sample in which a black tape 12 was provided on the back of the deposited film 11 was measured.
An ultraviolet-visible-near-infrared spectrophotometer (SolidSpec-3700, manufactured by Shimadzu Corporation) was used as a reflectance measuring device.
As shown in FIG. 7, the absolute reflectance in the 5° regular reflection direction when light is incident at an angle inclined by 5° from the normal direction of each vapor deposited film of the above configurations 1 to 4, and the above configurations 1 to 4 The absolute reflectance in the direction of specular reflection at 45° was measured when light was incident at an angle of 45° from the normal direction of each deposited film. The results are shown in FIGS. 8-15.
From the results of FIGS. 8 to 15, it was found that the simulation and the actual measurement (vapor-deposited film) in the reflection spectrum at visible light wavelengths are almost the same, and that the average thickness of each layer can be optimally designed by the simulation.

(Examples 1-4, Examples A-D, and Comparative Examples A-I)
<Setting the lower limit of the average thickness of each of the three layers by simulation (vapor deposition film)>
For Example 1, Example A, Example D, Example E, Comparative Example F, Comparative Example G, Comparative Example H, and Comparative Example I, which were changed to the average thickness of each of the three layers shown in Table 2, visual color was evaluated, and the simulation results for 5° specular reflectance are shown in Table 2 and FIG.
For Comparative Example A, Comparative Example B, Comparative Example C, Comparative Example D, and Comparative Example E, which were changed to the average thickness of each of the three layers shown in Table 2, visual color was evaluated, and simulation of 5 ° regular reflectance was performed. The results are shown in Table 2 and FIG.

-visual color-
The visual tint was evaluated by the reflection spectrum obtained from the simulation and the CIE Lab color system, and judged according to the following criteria.
[Evaluation criteria]
OK: Visual color is good NG: Visual color is poor

Next, Tables 3-1 to 3-3 show the simulation results of 5° specular reflection of Example 1 (Configuration 1), Example A (lower limit of Configuration 1), Example E, and Comparative Examples A to I. It was shown to.
Criteria for determining the lower limit of the average thickness of each of the three layers in the blue region include satisfying the following (1) and (2).
(1) (Maximum value of reflectance at wavelength 380 nm to 530 nm)/(Minimum value of reflectance at wavelength 420 nm to 630 nm) is 3.0 or more (2) Range of wavelength 380 nm to wavelength 780 nm In the reflection spectrum of , the minimum value of the reflectance is in the wavelength range of 420 nm to 630 nm. By satisfying the above (1) and (2) at the same time, it is easily visually recognized as blue.

From the results in Tables 3-1 to 3-3, it was found that there was a lower limit boundary for the average thickness of each of the three layers between Comparative Example I and Example E.

(Experimental example 4)
<Setting the upper limit of the average thickness of the total of three layers>
An upper limit was set for the total average thickness of the three layers to pulverize each deposited film into a range of cumulative 50% volume particle diameter _D50 that can be used for inkjet printing. The results are shown in FIG. 18, Tables 4 and 5.
The average thickness of each layer is an average value obtained by measuring the thickness of each layer at five locations by quantitative analysis using X-ray fluorescence spectroscopy (XRF).

From the results of FIG. 18, Tables 4 and 5, it was found that the upper limit of the total average thickness of the three layers was 330 nm or less.
Note that the relationship between the total average thickness of the three layers and the cumulative 50% volume particle diameter _D50 after pulverization is believed to be independent of the material of each layer. The thicker the total average thickness of the three layers, the smaller the particles even after pulverization.
In the range indicated by A in FIG. 18, clogging of the head occurred when printing with an inkjet printer.

(Experimental example 5)
<Appearance of coating film>
Configurations 1 to 4, which are coating films using three layers of finely pulverized scale-like particles of ZnS/MgF ₂ /ZnS, and coating films using three layers of finely pulverized scale-like particles of TiO ₂ /SiO ₂ /TiO ₂ As shown in FIG. 19, for the coating films of certain configurations 5 to 8 and other companies' products (manufactured by Nihon Koken Kogyo Co., Ltd., TiO ₂ embedded in natural mica, SXB, YXB), light source D65, shooting angle vertical line A photograph of the exterior was taken with an iPhone (registered trademark) (manufactured by Apple Inc.). The results are shown in FIG. The left half of each photograph in FIG. 20 corresponds to the left half in FIG. 19, and the right half of each photograph in FIG. 20 corresponds to the right half in FIG.
From the results of FIG. 20, the other company's products (manufactured by Nihon Koken Kogyo Co., Ltd., TiO ₂ embedded in natural mica, SXB, YXB) are large particle size flake powder, not finely ground particles. It is not preferable because the film has a grainy feel (rough feeling). On the other hand, in the coating films obtained by the bar coating method of Structures 1 to 8, moist visibility was observed.

(Experimental example 6)
<SEM observation of powder cross section>
Configurations 1 to 4, which are 3-layer vapor deposition films of ZnS/MgF ₂ /ZnS, Configurations 5 to 8, which are 3-layer vapor deposition films of TiO ₂ /SiO ₂ /TiO ₂ TiO ₂ embedded in natural mica, SXB, YXB), the cross section of the powder was observed with a scanning electron microscope (SEM) HITACHI S-4700 (manufactured by Hitachi, Ltd.). The results are shown in FIG.
FIG. 22 shows an enlarged cross-sectional SEM photograph of scaly particles obtained by pulverizing the deposited film of Structure 2. As shown in FIG. FIG. 23 shows an enlarged cross-sectional SEM photograph of scaly particles obtained by pulverizing the deposited film of Structure 7. As shown in FIG. FIG. 24 shows an enlarged cross-sectional SEM photograph of the powder of the competitor's product (SXB).
From the results of FIGS. 21 to 24, it can be confirmed that ZnS/MgF ₂ /ZnS and TiO ₂ /SiO ₂ /TiO ₂ have a three-layer structure from the cross section, and the three-layer vapor deposition film was pulverized by a pulverization process. I understand. On the other hand, it can be seen that the other company's product has no cross section and the entire surface of the powder is uniformly coated.
FIG. 24 is an enlarged SEM photograph of the powder of another company's product, and the part where the coating layer (TiO ₂ ) on the surface is partially peeled off and mica inside can be confirmed is photographed. In other companies' products, large particle size mica is coated on the entire surface in a post-treatment, which basically results in a large particle size (there is no pulverization after coating).
The powders of configurations 1 to 8 obtained by pulverizing the vapor deposition films of three layers of ZnS/MgF ₂ /ZnS and TiO ₂ /SiO ₂ /TiO ₂ have a smaller particle size when the total thickness of the three layers is thinner. It can be seen that it is.

(Experimental example 7)
<SEM observation of powder shape>
Configurations 1 to 4, which are three layers of finely pulverized scaly particles of ZnS/MgF ₂ /ZnS, configurations 5 to 8, which are three layers of finely pulverized scaly particles of TiO ₂ /SiO ₂ /TiO ₂ , and products of other companies ( Nihon Koken Kogyo Co., Ltd. TiO ₂ embedded product in natural mica, SXB, YXB) flakes, powder by scanning electron microscope (SEM: SCanning Electron Microscope) HITACHI S-4700 (manufactured by Hitachi, Ltd.) observed the shape of The results are shown in FIG.
From the results of FIG. 25, in the three-layer structure of ZnS/MgF ₂ /ZnS, even if the thicknesses of the first zinc sulfide layer and the second zinc sulfide layer are different, curling due to film stress was not observed, and the scaly shape was observed. I know there is.

(Experimental example 8)
<Measurement of particle size distribution>
Configurations 1 to 4, which are three layers of finely pulverized scaly particles of ZnS/MgF ₂ /ZnS, configurations 5 to 8, which are three layers of finely pulverized scaly particles of TiO ₂ /SiO ₂ /TiO ₂ , and products of other companies ( Nihon Koken Kogyo Co., Ltd. TiO ₂ embedded product in natural mica, SXB, YXB) flakes, the particle size distribution is measured using a laser diffraction/scattering particle size distribution analyzer (LSM-2000e, Seishin Enterprise Co., Ltd.) The cumulative 10% volume particle diameter D ₁₀ , the cumulative 50% volume particle diameter D ₅₀ , and the cumulative 90% volume particle diameter D ₉₀ were obtained. The results are shown in FIGS. 26 and 27. FIG.
From the results of FIGS. 26 and 27, it can be seen that the finely pulverized scaly particles having a three-layer structure of ZnS/MgF2/ZnS have a cumulative 50% volume particle diameter _D50 of 1.8 μm or less.

(Experimental example 9)
<Optical data of coating film>
0.40 g of finely pulverized scaly particles of configurations 1 to 4, 0.04 g of a binder (S-Lec B, manufactured by Sekisui Chemical Co., Ltd.), and 3.64 g of butyl acetate are mixed with a stirrer (rotation/revolution mixer ARE-310, (manufactured by Thinky Co., Ltd.) to prepare inks of compositions 1 to 4.
Next, on a polyethylene terephthalate (PET) film with an average thickness of 100 μm, each ink is applied with an applicator so that the average thickness is 5 μm or less, dried naturally at room temperature, and then dried at 120° C. for 3 minutes using a dryer. After drying, each coating film of constitutions 1 to 4 was produced.

Next, the obtained coating films of configurations 1 to 4 were measured using an ultraviolet-visible and near-infrared spectrophotometer (SolidSpec-3700, manufactured by Shimadzu Corporation) under the following measurement conditions at absolute reflections of 5° and 45°. were measured for L ^* a ^* b ^* , Y, x, and y. The results are shown in Table 7.
[Measurement condition]
・Lighting: D65
・ Field of view: 2 degrees In addition, the 5 ° specular reflection spectra of the coating films of configurations 1 to 4 measured with an ultraviolet-visible near-infrared spectrophotometer (SolidSpec-3700, manufactured by Shimadzu Corporation) are shown in FIG. The 45° specular reflection spectrum of the coating film of No. 4 is shown in FIG.

From the results in Table 7, FIG. 28, and FIG. 29, when light was incident at angles inclined at 5° and 45° with respect to the normal direction of each coating film and the absolute reflection was measured, 5° and 45° , the reflection wavelength and the absorption wavelength are different, and it is found that the 45° shifts to the short wavelength side.

REFERENCE SIGNS LIST 1 first zinc sulfide layer 2 magnesium fluoride layer 3 second zinc sulfide layer 10 pearl-colored scale-like particles

Claims (6)

Having a first zinc sulfide layer, a magnesium fluoride layer, and a second zinc sulfide layer in this order,
The average thickness of the first zinc sulfide layer is 30 nm or more,
The average thickness of the magnesium fluoride layer is 25 nm or more,
The second zinc sulfide layer has an average thickness of 30 nm or more,
Pearl color-developing scaly particles, wherein the total average thickness of the first zinc sulfide layer, the magnesium fluoride layer and the second zinc sulfide layer is 330 nm or less. The average thickness of the first zinc sulfide layer is 30 nm or more and 130 nm or less,
The average thickness of the magnesium fluoride layer is 25 nm or more and 60 nm or less,
2. The pearl-colored scale-like particles according to claim 1, wherein the second zinc sulfide layer has an average thickness of 30 nm or more and 190 nm or less. 3. The pearl-colored scaly particles according to claim 1, wherein the cumulative 50% volume particle diameter _D50 is 1.8 μm or less. 4. The pearl-colored scale-like particles according to any one of claims 1 to 3, which are for inkjet printing. 5. An ink comprising the pearl-colored scaly particles according to any one of claims 1 to 4. A coating film comprising the pearl-colored scaly particles according to any one of claims 1 to 4.

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