Magnetic pigment

Abstract

Provided is a magnetic pigment capable of having an arbitrary color and high designability without utilizing an interference action. The magnetic pigment comprises a magnetic base material and a coloring material that is fixed on the base material. The base material satisfies any one of the following conditions (i) and (ii): (i) the base material is composed of a magnetic metal or metal oxide containing at least one selected from the group consisting of Fe, N, and Co; or (ii) the base material has a core, the core is covered with a translucent metal oxide, and a magnetic metal or metal oxide containing at least one selected from the group consisting of Fe, Ni, and Co is fixed on the surface of the metal oxide.

Description

Magnetic pigments

[0001] This invention generally relates to pigments, and more specifically to magnetic pigments.

[0002] Traditionally, paints and inks have been designed to enhance their aesthetic appeal, and some of these, such as magnetic paints and inks, allow for the creation of patterns by controlling the orientation of pigments using magnetism.

[0003] For example, U.S. Patent No. 3,676,273 (Patent Document 1) describes a pigment that combines a magnetic pigment such as nickel flakes with a non-magnetic orientation pigment to form a desired pattern by magnetic force.

[0004] Furthermore, Japanese Patent Publication No. 2004-518565 (Patent Document 2) describes the process of generating magnetic metals or oxides such as Ni, Fe, and Co with Al and Cr by the PVD method, as well as MgF ２ The text describes pigments that exhibit a color that changes depending on the viewing angle, achieved by layering low refractive index materials such as [material name].

[0005] U.S. Patent No. 3,676,273, Japanese Patent Publication No. 2004-518565

[0006] However, the pigments described in Patent Document 1 have the problem that the magnetic pigments themselves do not have excellent design qualities, resulting in dull designs lacking in color. Furthermore, the pigments described in Patent Document 2 require the alternating lamination of high-refractive-index and low-refractive-index materials on a substrate using the PVD method in order to achieve design qualities by utilizing interference. However, this requires the repeated PVD method for laminating each layer and necessitates a process film as a non-reusable substrate, resulting in poor productivity and cost.

[0007] Therefore, the present invention aims to provide a magnetic pigment that can possess any color and high design quality without utilizing interference.

[0008] The inventors of this invention conducted extensive research to solve the above problems and have invented a magnetic pigment with excellent design properties by forming a pigment particle layer on a magnetic substrate.

[0009] In other words, a magnetic pigment according to the present invention comprises a magnetic substrate and a coloring agent fixed on the substrate, wherein the substrate satisfies either (i) or (ii) below: (i) it is composed of a magnetic metal or metal oxide containing at least one of the group consisting of Fe, N, and Co; or (ii) it has a nucleus, the nucleus is coated with a translucent metal oxide, and a magnetic metal or metal oxide containing at least one of the group consisting of Fe, Ni, and Co is fixed to the surface of the metal oxide.

[0010] In this way, it is possible to provide magnetic pigments that can have any color and high design quality without utilizing interference effects.

[0011] The magnetic pigment of the present invention comprises a magnetic substrate and a coloring material fixed on the substrate, wherein the substrate satisfies either (i) or (ii) below: (i) it is composed of a magnetic metal or metal oxide containing at least one of the group consisting of Fe, N, and Co; or (ii) it has a nucleus, the nucleus is coated with a translucent metal oxide, and a magnetic metal or metal oxide containing at least one of the group consisting of Fe, Ni, and Co is fixed to the surface of the metal oxide. The various components of the magnetic pigment of the present invention will be described in detail below.

[0012] <Substrate> In the magnetic pigment of the present invention, the substrate is magnetic. The shape of the substrate is not particularly limited, but it is preferably flaky in order to have high brilliance.

[0013] The substrate satisfies either (i) or (ii) below: (i) it is composed of a magnetic metal or metal oxide containing at least one of the group consisting of Fe, Ni, and Co; or (ii) it has a nucleus, the nucleus is coated with a translucent metal oxide, and a magnetic metal or metal oxide containing at least one of the group consisting of Fe, Ni, and Co is fixed to the surface of the metal oxide.

[0014] When using a substrate composed of a magnetic metal or metal oxide containing at least one of the group consisting of Fe, Ni, and Co, a PVD method can be used to obtain flake-like particles as the substrate. That is, a release agent is applied to a plastic substrate, and a metal film is formed by the PVD method. Afterwards, the release agent is removed with any solvent to obtain only the metal film, which can then be used as the substrate. However, since the PVD method requires large-scale manufacturing equipment and has poor productivity, resulting in high manufacturing costs, a flake-like substrate obtained by grinding metal particles, such as by the ball mill method, is preferably used.

[0015] Furthermore, as a substrate, (ii) a material having a nucleus, the nucleus being coated with a translucent metal oxide, and a magnetic metal or metal oxide containing at least one of the group consisting of Fe, Ni, and Co being fixed to the surface of the metal oxide, can be suitably used. To protect the nucleus and maintain the high luminosity of the nucleus itself, it is coated with a translucent metal oxide. For example, a translucent layer made of defect-free silicon oxide (hydrate) can be formed on the surface of the nucleus by stirring or kneading a slurry or paste state while keeping the metal nucleus and a silicon compound solution in a basic or acidic state.

[0016] Examples of silicon compounds used to coat the nucleus with a translucent metal oxide include methyltriethoxysilane, methyltrimethoxysilane, tetraethoxysilane, tetramethoxysilane, tetraisopropoxysilane, and their condensates, as well as γ-aminopropyltriethoxysilane, N-2-aminoethyl-3-aminopropyltriethoxysilane, and N-2-aminoethyl-3-aminopropylmethyldimethoxysilane.

[0017] Furthermore, as a solvent for dissolving silicon compounds, it is preferable to use hydrophilic solvents such as methyl alcohol, ethyl alcohol, isopropyl alcohol, n-propyl alcohol, t-butyl alcohol, n-butyl alcohol, isobutyl alcohol, ethyl cellosolve, butyl cellosolve, propylene glycol monobutyl ether, dipropylene glycol monomethyl ether, propylene glycol monopropyl ether, and acetone. It is also desirable to further add water to the hydrophilic solvent in a manner sufficient to hydrolyze the alkoxysilane.

[0018] <Particle Shape and Size> The particle size and shape of the magnetic pigment of the present invention are not particularly limited, but a flaky shape is preferable to obtain brilliance and sparkling properties. The particle size depends on the substrate, but is preferably 1 μm or more and 500 μm or less.

[0019] For example, when used in nail lacquer, especially when a strong particle texture like glitter is desired, the magnetic pigment is preferably flaky in shape and has a particle size in the range of 30 μm to 500 μm. Within this range, a good particle texture and sparkle can be obtained. On the other hand, when used in printing ink, although it depends on the printing method, the particle size of the magnetic pigment is preferably in the range of 1 μm to 30 μm. For example, for application in intaglio printing, magnetic pigments with a particle size of 1 μm to 25 μm can be suitably used.

[0020] When the substrate particle size is less than 1 μm, the particle size of the substrate and the particle size of the pigment used as a coloring agent become close, which can lead to a lower coverage rate by the coloring agent and a decrease in aesthetic appeal.

[0021] Particle size refers to the particle size at 50% of the cumulative volume distribution (D50) measured by laser diffraction. Furthermore, even without using a laser diffraction particle size analyzer, particle size can be determined by photographing the coated pigment with an optical microscope, laser microscope, or scanning electron microscope, and then using commercially available image analysis software to obtain the distribution of the major axis (the distance between the two furthest points on the contour line of the coated pigment as determined by two-dimensional analysis).

[0022] <Magnetic Layer - PVD Method> When a non-magnetic material is used as the core in the magnetic pigment of the present invention, it is necessary to fix a magnetic metal or metal oxide on the core. The magnetic metal or metal oxide is fixed as a magnetic layer on the core, for example. The magnetic layer can be applied by coating all or part of the non-magnetic material with a magnetic metal such as Fe, Ni, Co and / or a magnetic metal oxide containing Fe, Ni, Co using the PVD method. However, this method has the problem of increased manufacturing costs due to the high cost of manufacturing equipment and low productivity. If the substrate is in the form of a film, a uniform magnetic layer can be formed on the substrate and then the pigment can be obtained by peeling it off the carrier film. On the other hand, it is difficult to have a uniform magnetic layer on the core of a particulate substrate, and it may be difficult to obtain a magnetic pigment of stable quality.

[0023] On the other hand, forming a magnetic layer on the nucleus by a wet process is particularly suitable for particulate nuclei. Specifically, it is preferable to cover all or part of the nucleus of the substrate with a ferrite layer by a wet process.

[0024] <Magnetic layer - wet method> The ferrite above is MxFe （３－ｘ） O ４ It can be expressed in the form of , where M represents a divalent or trivalent metal. As long as the metal M is divalent or trivalent, the type of metal is not particularly limited. For example, such a metal can be at least one selected from the group consisting of Fe, Mg, Ca, Ti, V, Cr, Mn, Co, Ni, Cu, Zn, Zr, Nb, Mo, W, Al, Si, In, and Sn. Thus, the above M represents one or more metals.

[0025] Of these metals, Fe, Ni, and Co are preferred from the standpoint of availability. In particular, when M is Fe, ｘ Fe （３－ｘ） O ４ Fe ３ O ４ (Magnetite) is particularly suitable because it has excellent design properties and is safe for the human body. Because it is safe for the human body, the magnetic pigment of the present invention is particularly effective when used in cosmetics.

[0026] In the magnetic pigment of the present invention, the ferrite layer can be formed on the surface of the substrate by the following wet method. In the following, taking the case where M is Fe (that is, magnetite) in MFeO as an example for explanation, it is needless to say that it can also be adopted when M is a metal other than Fe. ｘ Fe （３－ｘ） O ４ First, a slurry is obtained by dispersing the core in water to make a slurry state, and an aqueous solution containing Fe is gradually added thereto while stirring the slurry. At this time, since the pH fluctuates, the pH is maintained between 6.5 and 14 with a pH adjuster, and at the same time, the redox potential of the slurry is maintained between approximately -160 mV and -750 mV using an oxidizing agent, whereby the ferrite layer is coated on the core. Since the ferrite particles grow through the hydroxyl groups present on the core, if the core surface has hydroxyl groups, the ferrite layer can be selectively formed.

[0027] First, a slurry is obtained by dispersing the core in water to make a slurry state, and an aqueous solution containing Fe is gradually added thereto while stirring the slurry. At this time, since the pH fluctuates, the pH is maintained between 6.5 and 14 with a pH adjuster, and at the same time, the redox potential of the slurry is maintained between approximately -160 mV and -750 mV using an oxidizing agent, whereby the ferrite layer is coated on the core. Since the ferrite particles grow through the hydroxyl groups present on the core, if the core surface has hydroxyl groups, the ferrite layer can be selectively formed. ２＋ is contained, and an aqueous solution containing Fe is gradually added thereto while stirring the slurry. At this time, since the pH fluctuates, the pH is maintained between 6.5 and 14 with a pH adjuster, and at the same time, the redox potential of the slurry is maintained between approximately -160 mV and -750 mV using an oxidizing agent, whereby the ferrite layer is coated on the core. Since the ferrite particles grow through the hydroxyl groups present on the core, if the core surface has hydroxyl groups, the ferrite layer can be selectively formed.

[0028] Here, an aqueous solution containing Fe ２＋ can be easily obtained by dissolving a salt containing divalent iron such as ferrous chloride, ferrous nitrate, or ferrous sulfate in ion-exchanged water degassed with an inert gas. The aqueous solution containing Fe ２＋ [[ID=2E]] is preferably used while blowing an inert gas such as nitrogen or argon to suppress unnecessary oxidation. Also, the amount of Fe ２＋ can be arbitrarily adjusted in consideration of the amount of the core according to the designability of the magnetic pigment to be obtained.

[0029] The above pH adjuster is Fe ２＋An aqueous solution containing the specified substance can be used to maintain a pH of 6.5 to 14 when added to the slurry. For example, aqueous solutions of sodium hydroxide, potassium hydroxide, sodium carbonate, ammonia, etc., can be used as appropriate, but are not limited to these. The above pH range is preferably 6.5 to 12, and more preferably 7.5 to 10. If the pH exceeds this range, the ferrite layer will not be formed, or a layer containing iron-containing compounds other than ferrite will be formed. In particular, a pH above 10.0 is undesirable because the nucleus surface may be damaged, or if the nucleus is metal, corrosion may occur. If necessary, a pH buffer can be added to the slurry in advance to suppress rapid pH fluctuations. For example, sodium acetate, ammonium acetate, etc., can be used.

[0030] The reaction temperature should be within a range where the slurry does not freeze or boil, preferably between 10°C and 80°C. If the temperature is below 10°C, Fe ２＋ The oxidation reaction is slow and takes a long time, and above 80°C, especially at high pH, ​​it is undesirable because it damages the nucleus surface.

[0031] In the present invention, Fe ２＋ When using only Fe as the metal source ３ O ４ (Magnetite) is produced, but Fe ２＋ It is also possible to replace some of the ions with other divalent or trivalent metal ions. Examples of replaceable metals include Mg, Ca, Ti, V, Cr, Mn, Co, Ni, Cu, Zn, Zr, Nb, Mo, W, Al, Si, In, and Sn, and their chloride salts, sulfates, nitrates, acetates, etc., can be used. Furthermore, the strength of magnetism or heat resistance can be changed depending on the type and amount of these metals added. ２＋ When using metal ions other than M ｘ Fe （３－ｘ） O ４ In this case, M represents Fe and the metal used in combination with it. Note that x represents the total amount of Fe and the metal used in combination with it.

[0032] In addition, when using the magnetic pigment of the present invention in cosmetics, considering the toxicity to the human body, it is preferable that M is Fe, that is, the ferrite layer is composed of magnetite.

[0033] As the oxidizing agent, nitrite, nitrate, hydrogen peroxide, oxygen, etc. can be used, but it is preferable to use oxygen (air) which is the cheapest and non-toxic.

[0034] As described above, it is preferable to form the ferrite layer on the entire surface of the core. However, as long as the ferrite layer functions, even if a part of the surface where the ferrite layer is not formed is included, it does not deviate from the scope of the present invention. That is, in the present invention, the covering state of the core by the ferrite layer may be continuous or discontinuous. "Continuous" or "continuously covering" means forming a ferrite layer on the entire surface of the core. In this case, the ferrite layer is also called a continuous layer. On the other hand, "discontinuous" or "discontinuously covering" means forming a ferrite layer (in an island shape) on a part of the surface of the core. In this case, the ferrite layer is also called a discontinuous layer.

[0035] Such a covering state by the ferrite layer can be confirmed by a scanning electron microscope or a transmission electron microscope of the surface or cross-section of the base material or magnetic pigment. That the ferrite layer continuously covers the base material means that when observing the surface of the magnetic pigment with a scanning electron microscope, there is no exposure of the core or the light-transmitting layer. However, even if the ferrite layer is continuously covered, the ferrite layer may partially peel off due to mechanical friction. However, in this case, it can be said to be an essentially continuous covering. On the contrary, when the core or the light-transmitting metal oxide layer is exposed, it can be determined that the base material is discontinuously covered. By dissolving the resin in the resin composition using an organic solvent and extracting the magnetic pigment, the covering state of the ferrite layer can be confirmed by observing the surface by the above method.

[0036] <Colorant> As the colorant in the magnetic pigment of the present invention, conventionally known pigments can be used without particular limitation.

[0037] Examples of pigments include organic pigments such as diketopyrrolopyrrole, quinacridone, dioxazine, isoindolinone, condensed azo, surene, perinone, perylene, quinophthalone, and phthalocyanine, as well as inorganic pigments such as iron oxide and carbon black.

[0038] Examples of pigments include phthalocyanine, halogenated phthalocyanine, quinacridone, diketopyrrolopyrrole, isoindolinone, azomethine metal complex, indanthrone, perylene, perinone, anthraquinone, dioxazine, benzimidazolone, condensed azo, triphenylmethane, quinophthalone, anthrapyrimidine, iron oxide, ultramarine, Prussian blue, cobalt blue, chrome green, bismuth vanadate, complex oxide calcined pigments, aniline black, carbon black, titanium black, titanium dioxide, and ultrafine titanium dioxide particles.

[0039] Furthermore, when the magnetic pigment of the present invention is used in cosmetics, coloring pigments commonly used in cosmetics, such as tar dyes for cosmetics and pharmaceuticals as defined in each country, and pigments that meet cosmetic raw material standards, can also be used, taking into consideration skin safety.

[0040] Pigments that are particularly preferred in terms of adhesion to the substrate, weather resistance, and coloring power include phthalocyanine blue, phthalocyanine green, quinacridone red, quinacridone magenta, quinacridone gold, anthraquinone, indanthrene blue, diketopyrrolopyrrole, isoindolinone yellow, isoindolinone orange, anthrapyrimidine yellow, dioxazine violet, perylene maroon, azomethine copper complex, benzimidazolon monoazo pigments, transparent iron oxide, carbon black, and ultrafine titanium dioxide.

[0041] The primary particle size of such pigments is not particularly limited, but preferably it is in the range of 0.01 to 1 μm, and more preferably in the range of 0.02 to 0.2 μm. When the primary particle size is 0.01 μm or larger, there is less risk of difficulty in dispersing the pigment, and when the primary particle size is 1.0 μm or smaller, there is less risk of difficulty in uniformly adhering it to the magnetic pigment surface.

[0042] The amount of coloring agent to be applied is 1 part by mass or more and 200 parts by mass or less, more preferably 5 parts by mass or more and 100 parts by mass or less, per 100 parts by mass of the substrate. It is preferable to adjust the amount of application appropriately according to the specific surface area of ​​the magnetic pigment. If the amount of application is less than 1 part by mass, the magnetic pigment that is ultimately obtained will not have a sufficient coloring effect, and if the amount of application exceeds 200 parts by mass, the aesthetic appeal of the magnetic pigment will be reduced.

[0043] Furthermore, the colorants used in the magnetic pigments of the present invention include those classified as dyes, as long as they maintain a particle state under predetermined conditions.

[0044] It is preferable to selectively adsorb the coloring agent onto the substrate. By doing so, the amount of coloring agent used can be reduced to the minimum necessary amount.

[0045] To selectively adsorb a colorant onto a substrate, this can be achieved, for example, by mixing the colorant and the substrate and applying strong mechanical energy to induce a mechanochemical reaction. Since this is a dry method, it is preferable to carry it out in an inert atmosphere such as nitrogen, argon, or helium to minimize the risk of dust explosion.

[0046] On the other hand, colorants can also be selectively adsorbed onto a substrate by a wet method. Specifically, for example, by adding a carboxylic acid and / or an amine compound as a binder to the substrate and the colorant and kneading them, the colorant can be selectively attached to the surface of the substrate. The binder is preferably a mixture of a carboxylic acid and an amine compound. The carboxylic acid preferably has two or more carboxyl groups. The amine compound preferably has two or more amino groups. The amount of such a binder depends on the type of pigment and particle size, but it is preferably 50 parts by mass or less, and more preferably 40 parts by mass or less, per 100 parts by mass of colorant.

[0047] <Adhesion of Coloring Agent> It is preferable to coat the substrate with a resin and / or metal oxide (including hydrate) to adhere the coloring agent. It is preferable that the coloring agent covers 50% or more of the surface area of ​​the substrate, and more preferably 90% or more. Furthermore, the weight ratio of the coloring agent to the metal of the substrate is preferably 10 to 70%, and more preferably 20 to 35%.

[0048] When a resin is used to fix a coloring agent onto a substrate, the resin refers to a material that has been polymerized by radical polymerization of monomers and / or oligomers having at least one polymerizable double bond, resulting in a resin-like substance. Since the resin is obtained by radical polymerization of monomers and / or oligomers having at least one polymerizable double bond in this way, the coloring agent can be fixed onto the substrate by performing such radical polymerization on or around the coloring particles coated on the substrate.

[0049] A specific method for coating the coloring agent and substrate with resin involves dispersing a magnetic pigment in a hydrocarbon-based or alcohol-based solvent (preferably a hydrocarbon-based solvent), adding monomers and / or oligomers and polymerization initiators such as benzoyl peroxide, isobutyl peroxide, and azobisisobutyronitrile, heating while stirring to radically polymerize the monomers and / or oligomers, and precipitating them around the coloring agent particles and / or outside the coloring agent layer.

[0050] When the coloring agent is present in a dense state on the substrate, the resin precipitates on the outside of the coloring agent; when the coloring agent is present in a sparse state, the resin precipitates around the coloring agent particles, forming a mixed layer of resin and coloring particles.

[0051] The amount of polymerization initiator added is preferably 1 to 30 parts by mass per 100 parts by mass of monomer and / or oligomer. The polymerization reaction is preferably carried out in an oxygen-free atmosphere, such as in an inert gas such as nitrogen or argon. The reaction temperature depends on the heat resistance of the coloring agent, but is generally suitable at 50 to 150°C, more preferably 70 to 110°C. The reaction time is preferably 30 minutes to 30 hours.

[0052] Examples of the above monomers and / or oligomers are listed below. That is, acrylic acid, methacrylic acid, methyl methacrylate, butyl acrylate, 2-ethylhexyl acrylate, lauryl acrylate, stearyl acrylate, cyclohexyl acrylate, 2-hydroxyethyl acrylate, 2-hydroxybutyl acrylate, 2-methoxyethyl acrylate, 2-diethylaminoethyl acrylate, butyl methacrylate, octyl methacrylate, 1,4-butanediol diacrylate, 1,6-hexanediol diacrylate, 1,9-nonanediol diacrylate, neopentyl glycol diacrylate, tripropylene glycol diacrylate, tetraethylene glycol diacrylate, trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, tetramethylolmethane tetraacrylate, pentaerythritol triacrylate, trisacryloxyethyl phosphate, ditrimethylolpropane tetraacrylate, styrene, α-methylstyrene, vinyltoluene, divinylbenzene, acrylonitrile, methacrylatenitrile, vinyl acetate, vinyl propionate Nyl, maleic acid, crotonic acid, itaconic acid, polybutadiene, linseed oil, soybean oil, epoxidized soybean oil, epoxidized polybutadiene, cyclohexene vinyl monooxide, divinylbenzene monooxide, mono(2-acryloyloxyethyl) acid phosphate, mono(2-methacryloyloxyethyl) acid phosphate, 2-acryloyloxyethyl acid phosphate, 2-methacryloyloxyethyl acid phosphate, (2-hydroxyethyl) methacrylate acid phosphate, 2- Methacryloyloxyethyl acid phosphate, 2-acryloyloxyethyl acid phosphate, diphenyl-2-methacryloyloxyethyl acid phosphate, diphenyl-2-acryloyloxyethyl acid phosphate, dibutyl-2-methacryloyloxyethyl acid phosphate, dibutyl-2-acryloyloxyethyl acid phosphate, dioctyl-2-methacryloyloxyethyl acid phosphate, dioctyl-2-acryloyloxyethyl acid phosphate,Examples include, but are not limited to, 2-methacryloyloxypropyl acid phosphate, bis(2-chloroethyl) vinyl phosphonate, di-2-methacryloyloxyethyl acid phosphate, tri-2-methacryloyloxyethyl acid phosphate, di-2-acryloyloxyethyl acid phosphate, tri-2-acryloyloxyethyl acid phosphate, diallyl dibutyl phosphonosuccinate, acrylic-modified polyester (degree of polymerization 2-20), acrylic-modified polyether (degree of polymerization 2-20), acrylic-modified urethane (degree of polymerization 2-20), acrylic-modified epoxy (degree of polymerization 2-20), and acrylic-modified spiran (degree of polymerization 2-20).

[0053] In particular, when monomers and / or oligomers having two or more polymerizable double bonds are used as monomers and / or oligomers, a resin made of three-dimensionally crosslinked radical polymerizable resin is formed, which is advantageous in that it further improves water resistance. However, although the coloring agent on the resin-coated substrate is fixed to the substrate to some extent, due to the lack of heat resistance of the resin itself, when the thermoplastic resin and magnetic pigment are kneaded at a high temperature of, for example, 200°C or higher, the resin softens, and furthermore, the coloring agent peels off from the substrate due to the mechanical stress applied by kneading.

[0054] Therefore, by coating a colored layer consisting of a coloring agent and a resin with a metal oxide (including hydrate), a magnetic pigment that can withstand heat and mechanical stress can be obtained.

[0055] Here, if the colored layer or the resin-fixed colored layer is sparse, the coated metal oxide becomes a mixture with the resin-fixed colored material layer, and if the colored material layer or the resin-fixed colored material layer is dense, the metal oxide layer is formed on the outside of the colored layer. The metal oxide (including hydroxide) is an oxide or hydroxide of at least one element selected from the group consisting of Al, Si, Ti, Cr, Zr, Mo, and Ce. By using such an oxide or hydroxide, the colored material fixed to the surface of the magnetic pigment with resin has increased strength against heat, and peeling of the colored material can be suppressed even under mechanical stress at high temperatures. It is preferable that such oxides and hydroxides are colorless so as not to interfere with the color development of the colored material that is applied first.

[0056] Specific examples of such metal oxides (including hydroxides) include silicon oxide, polysiloxane condensates, aluminum oxide, titanium oxide, aluminum hydroxide, molybdenum oxide, chromium oxide, zirconium oxide, zirconium hydroxide, cerium oxide, and cerium hydroxide. Among these, silicon oxide and / or polysiloxane condensates (i.e., silicon oxide alone, polysiloxane condensates alone, and mixtures of both) are particularly preferred in terms of transparency, safety, and production cost.

[0057] Such oxides or hydroxides can consist of one type or a mixture of two or more types. Note that silicon oxide and polysiloxane condensates are both oxides of Si, and polysiloxane condensates refer to compounds formed by the condensation of organosilicon compounds via siloxane bonds.

[0058] Here, by using organosilicon compounds having double bonds, such as vinyl groups, acrylic groups, and methacrylic groups, in the resin coating process described above, and radically polymerizing the double bond portion with monomers and / or oligomers having polymerizable double bonds, a colored layer with excellent heat resistance can be formed.

[0059] <Resin Composition> Resin compositions containing magnetic pigments according to the present invention include paints, inks, coatings formed by paints, printed materials formed by inks, and resin molded articles. Hereinafter, paints and inks will be collectively referred to as coating compositions.

[0060] The amount of magnetic pigment in the coating composition is preferably within the range of 0.1 to 30% by mass of the total coating composition. When the amount is 0.1% by mass or more, decorative effects such as metallic effects are good, and when it is 30% by mass or less, the weather resistance, corrosion resistance, mechanical strength, etc. of the coating composition are good. It is more preferable that the amount of magnetic pigment in the coating composition is within the range of 0.1 to 20% by mass of the total coating composition.

[0061] The coating composition is obtained by appropriately blending a resin with the magnetic pigment of the present invention. Examples of such resins include acrylic resins, alkyd resins, polyester resins, polyurethane resins, polyvinyl acetate resins, nitrocellulose resins, and fluororesins.

[0062] In addition to the magnetic pigment and resin of the present invention, other coloring pigments, extender pigments, dyes, etc., may be used in combination with such coating compositions. Examples of coloring pigments that can be used in combination include phthalocyanine, quinacridone, isoindolinone, perylene, azolake, iron oxide, lead yellow, carbon black, titanium dioxide, and pearl mica. Furthermore, in addition to the above components, water, organic solvents, surfactants, curing agents, ultraviolet absorbers, antistatic agents, thickeners, etc., may be appropriately added as additives to the coating composition.

[0063] When forming a coating film using a coating composition according to the present invention, the coating film may be formed on top of an undercoat layer or intermediate coat layer formed by electrodeposition coating or the like, and a topcoat layer may be further formed on top of such a coating film made of the coating composition.

[0064] To create magnetic patterns using a coating composition containing magnetic pigments, the magnetic pigments must move within the composition due to magnetic force. Therefore, it is necessary to apply the pattern using a magnet or the like before the solvent in the coating composition completely evaporates due to drying. Furthermore, to fix the applied pattern, it is desirable to allow the solvent in the coating composition to evaporate to the point where the magnetic pigments can no longer move, and to continue applying magnetic force until the viscosity of the composition increases.

[0065] <Coated Articles> The present invention also relates to coated articles obtained by coating any of the above resin compositions onto a substrate. The material of the substrate constituting such a coated article is not particularly limited and can be, for example, metal, resin, wood, paper, leather, etc.

[0066] Examples of such coated materials include the bodies of automobiles and motorcycles, lids, packaging materials, printed materials such as magazines and posters, and coated materials requiring security, such as banknotes, passports, driver's licenses, and gift certificates.

[0067] <Cosmetics> The present invention also relates to cosmetics containing magnetic pigments. Conventionally, pearl pigments and aluminum pigments have been used to impart gloss and brilliance to cosmetics, but pearl pigments have poor opacity, and aluminum pigments exhibit a gray color, making it difficult to obtain vivid colors even when colored pigments are added. Furthermore, aluminum pigments react easily with water, so they cannot be used in cosmetics containing water. The coated pigment of the present invention has a translucent layer that is water-resistant, thus resolving these problems, and can be suitably incorporated into cosmetics.

[0068] Furthermore, highly saturated magnetic nails can be obtained by using nail lacquer or UV-curing resin containing the magnetic pigment of the present invention.

[0069] The present invention can be summarized as follows:

[0070] (1) A magnetic pigment comprising a magnetic substrate and a coloring material fixed on the substrate, wherein the substrate satisfies either one of the following conditions (i) or (ii): (i) is composed of a magnetic metal or metal oxide including at least one from the group consisting of Fe, N, and Co, or (ii) has a nucleus, the nucleus is coated with a translucent metal oxide, and a magnetic metal or metal oxide including at least one from the group consisting of Fe, Ni, and Co is fixed to the surface of the metal oxide.

[0071] (2) The magnetic pigment according to (1) above, wherein the core is composed of one or more metals or alloys selected from the group consisting of Al, Cu, Sn, and Zn.

[0072] (3) The magnetic pigment according to (1) above, wherein the core is formed of one or more transparent materials selected from the group consisting of glass, mica, alumina, and silica.

[0073] (4) The magnetic pigment according to (1) above, wherein the translucent metal oxide is an oxide or hydroxide containing at least one of Si and Al.

[0074] (5) The magnetic pigment described in (1) above, wherein the coloring material comprises an aggregate of at least one type of pigment particles, and the pigment particles are a resin, a metal oxide, or a composite of a resin and a metal oxide.

[0075] (6) The magnetic pigment described in (1) above, having a flaky shape.

[0076] (7) The magnetic pigment described in (1) above, wherein the nucleus is Al, the translucent metal oxide is silica, and the magnetic metal oxide is ferrite.

[0077] (8) An ink comprising the magnetic pigment and solvent described in (1) above.

[0078] (9) A paint comprising the magnetic pigment and solvent described in (1) above.

[0079] (10) A coating film containing the magnetic pigment described in (1) above.

[0080] (11) A molded article containing the magnetic pigment described in (1) above.

[0081] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

[0082] The various evaluation methods and other details in this invention are as follows.

[0083] <Color Evaluation> To 2.0 g of the magnetic pigment obtained in each example and comparative example, 10.0 g of an air-drying acrylic resin binder (product name: "Nippe Acrylic Auto Clear", manufactured by Nippon Paint Co., Ltd.) was added as a binder, and the mixture was stirred and mixed until uniform to prepare a magnetic pigment-containing coating composition. Next, using an applicator with a gap of 9 mil (1 mil = 0.0254 mm), the coating composition obtained above was applied to opacity test paper (manufactured by TP Giken Co., Ltd.) and air-dried at room temperature to prepare a color evaluation coating film. The color was evaluated by measuring the color of the black area of ​​the opacity test paper using a multi-angle colorimeter BYK mac i (manufactured by Big Gardner). The measured color value was expressed in the L*a*b* color system (CIE 1976), and the color measurement detected light that was shifted 15° from the specularly reflected light relative to the incident light.

[0084] <Confirmation of Magnetism> 1.0 g of the magnetic pigment obtained in each example and comparative example was placed in a 50 cc glass beaker, and 30 g of isopropyl alcohol was added to prepare a slurry. Next, a ferrite rubber magnet (20 mm x 20 mm, 1 mm thick, surface magnetic flux density 30 mT) was placed on the outside of the bottom of the beaker, and the presence or absence of magnetism was confirmed visually. If the pigment is not magnetic, no change will occur in the slurry, but if the pigment is magnetic, the pigment will be oriented by the magnet or will gather near the magnet, so it is possible to confirm whether or not it is magnetic by visual inspection.

[0085] Example 1 <Magnetic Substrate> A commercially available flake-shaped SUS316L stainless steel pigment (product name: RFA4000, manufactured by Toyo Aluminum Co., Ltd., solid content 90%, D50 = 30 μm) was prepared as the magnetic substrate. This flake-shaped SUS316L stainless steel pigment had a gunmetal-like design and magnetic properties. Although SUS316L is not inherently magnetic, the flakes ground by a ball mill become magnetic.

[0086] <Degreasing Process> 222.2 g of the flake-shaped SUS316L stainless steel pigment and 300 mL of mineral spirits were placed in a three-necked flask. 20.0 g of a double-bonded carboxylic acid (product name: Diacid 1550, manufactured by Harima Chemicals Co., Ltd.) obtained by thermal polymerization of acrylic acid and soybean oil fatty acid was added. After heating and stirring, the mixture was cooled to room temperature and filtered to obtain degreased flake-shaped SUS316L stainless steel pigment (solid content 90%).

[0087] <Pigment Adhesion Process> Next, 400 mL of mineral spirits as a solvent, 40.0 g of commercially available red pigment (diketopyrrolopyrrole Pigment Red 254) as a coloring agent, 100.0 g of the degreased stainless steel pigment as a solid, 5.0 g of a double-bonded carboxylic acid obtained by thermal polymerization of the same acrylic acid and soybean oil fatty acid as above, and 5.0 g of amine (product name: LA-67, manufactured by ADEKA Corporation) were placed in a kneader and stirred at 80°C for 1 hour to obtain a slurry containing colored flaky stainless steel pigment with the coloring agent adhering to its surface.

[0088] <Resin Coating Process> Subsequently, the entire amount of the colored flake-shaped stainless steel pigment-containing slurry obtained above was placed in a three-necked flask containing 1000 mL of mineral spirits, and 1.0 g of acrylic acid was added and stirred. Next, 30.0 g of trimethylolpropane trimethacrylate, 5.0 g of divinylbenzene, and 5.0 g of azobisisobutyronitrile, each dissolved in 150 mL of mineral spirits, were added, and the mixture was heated to 100°C while blowing in nitrogen and stirred for 10 hours. After cooling to room temperature, the mixture was filtered to obtain a colored flake-shaped SUS316L stainless steel pigment with a colored layer consisting of resin and coloring agent formed on the surface.

[0089] The obtained colored, flaky stainless steel pigment still possessed magnetic properties. When a coating composition was prepared using the above method and its color tone was evaluated, it was found to have a reddish-brown metallic appearance.

[0090] Example 2 A commercially available aluminum pigment (product name: 5422NS, manufactured by Toyo Aluminum Co., Ltd., solid content: 75% by mass, average particle size: 19 μm) was used as the core of the substrate.

[0091] <Translucent Layer Metal Oxide> In a three-necked flask equipped with a stirrer, 3 g of hydrogen peroxide solution containing 30% by mass of hydrogen peroxide was gradually added to 0.3 g of metallic molybdenum powder, and the resulting solution was dissolved in 1000 g of IPA to obtain an IPA solution. Next, 250 g of the above-mentioned nonmagnetic flake-shaped aluminum pigment was added as solid content to this IPA solution, and the mixture was stirred at 75°C for 1 hour to obtain a slurry.

[0092] Subsequently, 80 g of water was added to the slurry while stirring and maintaining the temperature at 75°C. Next, the pH was adjusted to 10.0 using 30% aqueous ammonia. To the pH-adjusted slurry, a solution of 280 g of tetraethoxysilane dissolved in 450 g of IPA was gradually added dropwise, and the mixture was stirred and mixed at 75°C for 6 hours. After that, the slurry was separated into solid and liquid components using a filter, and then placed in a 150°C oven for 24 hours to remove the solvent, thereby forming a translucent layer of silicon oxide with a thickness of approximately 100 nm on the surface of the flaky aluminum particles.

[0093] The thickness of the silicon dioxide layer was obtained by exposing the cross-section of the flaky aluminum particles using a commercially available cross-section polisher and observing the cross-section with a scanning electron microscope.

[0094] <Ferrite layer> In a sealed reactor equipped with a stirrer, pH measuring electrode, and gas inlet pipe, 100 g of flaky metal substrate with a translucent layer formed on it and 400 g of ion-exchanged water thoroughly degassed with nitrogen were added to obtain a slurry in which translucent metal oxide coated aluminum pigment was dispersed in the ion-exchanged water.

[0095] Next, 0.5 g of polyacrylic acid (weight-average molecular weight: 250,000) and 2.5 g of sodium acetate were added to the slurry, and the slurry was heated while stirring until it reached 60°C.

[0096] Next, 35 g of ferrous sulfate heptahydrate and 100 g of deionized water thoroughly degassed with nitrogen were placed in an Erlenmeyer flask. The mixture was stirred while passing nitrogen gas through until the ferrous sulfate dissolved, obtaining an aqueous solution of ferrous sulfate. This aqueous solution of ferrous sulfate was then gradually added to the slurry over 5 hours while stirring. During this time, a 5 wt% sodium hydroxide solution was added to adjust the pH to a range of 6.5 to 10.0. Slurry samples were taken at 10-minute intervals, and air was introduced into the reactor to maintain an oxidation-reduction potential in the range of -300 mV to -500 mV. After the addition of the aqueous solution of ferrous sulfate was completed, stirring was continued for another hour, then the mixture was allowed to cool to room temperature, filtered, and washed with water. Subsequently, it was washed with IPA and filtered again until a dry powder was obtained. This coated pigment exhibited a slightly yellowish silver color and was confirmed to be magnetic. Furthermore, ferrite formation was confirmed by XRD analysis.

[0097] <Pigment Application and Resin Coating Process> In the pigment application process described in Example 1, a ferrite-coated aluminum pigment was used as the substrate instead of the stainless steel pigment, except that the same process was used to coat the substrate with a red pigment. The obtained pigment was magnetic, and when a coating composition was prepared using the method described above and its color tone was evaluated, it had a vivid metallic red color.

[0098] Example 3 In the process of coating the translucent metal oxide layer described in Example 2, 150 g of non-magnetic flake-shaped aluminum pigment was used as the solid component to coat the translucent metal oxide layer using the same procedure. A translucent layer of silicon oxide with a thickness of approximately 160 nm was formed on the surface of the metal substrate obtained in this way.

[0099] The substrate coated with the obtained translucent metal oxide layer was coated with a ferrite layer using the same procedure as in Example 2, except that 50 g of ferrous sulfate heptahydrate was used in the step of applying the ferrite layer. The substrate obtained in this way exhibited a pink gold color.

[0100] Using the above-mentioned pink gold-colored substrate, a red pigment was coated using the same procedure as in Example 2. The resulting pigment was magnetic, and when a coating composition was prepared using the above method and its color tone was evaluated, it had a more vivid metallic red color than the magnetic pigment obtained in Example 2.

[0101] Example 4 A pigment was prepared using the same procedure as in Example 2, except that a commercially available blue pigment (phthalocyanine blue Pigment Blue 15:3) was used instead of the red pigment. The obtained pigment was magnetic, and when a coating composition was prepared using the above method and its color tone was evaluated, it had a vivid metallic blue color.

[0102] Example 5 A pigment was prepared using the same procedure as in Example 2, except that a commercially available green pigment (phthalocyanine green pigment 7) was used instead of the red pigment. The obtained pigment was magnetic, and when a coating composition was prepared using the above method and its color tone was evaluated, it had a vivid metallic green color.

[0103] Example 6 The pigment of Example 6 was prepared in the same manner as in Example 2, except that the amount of coloring agent was changed to 10 g. The obtained pigment was magnetic, and when a coating composition was prepared using the above method and its color tone was evaluated, it had a slightly vivid red color.

[0104] Example 7 The pigment of Example 7 was prepared in the same manner as in Example 2, except that the amount of coloring agent was changed to 25 g. The obtained pigment was magnetic, and when a coating composition was prepared using the above method and its color tone was evaluated, it had a vivid red color.

[0105] Comparative Example 1 Only the commercially available flake-shaped SUS316L stainless steel pigment (product name: RFA4000, manufactured by Toyo Aluminum Co., Ltd., solid content 90%, D50 = 30 μm) used in Example 1 was evaluated according to the color evaluation method described above. This pigment exhibited a blackish gunmetal-like appearance and possessed magnetic properties.

[0106] Comparative Example 2: The magnetic pigment coated with the ferrite layer described in Example 2 was evaluated according to the color evaluation method described above. This pigment exhibited a slightly yellowish silver metallic tone.

[0107] Comparative Example 3: The magnetic pigment coated with the ferrite layer described in Example 3 was evaluated according to the color evaluation method described above. This pigment exhibited a pink gold color.

[0108] Comparative Example 4 A commercially available red pigment (diketopyrrolopyrrole Pigment Red 254) described in Example 2 was placed in a container together with mineral spirits and zirconia beads, and a slurry in which the red pigment was well dispersed was prepared using a paint shaker. Next, the substrate prepared by the method described in Example 2 and the well-dispersed red pigment were blended in the same ratio as the magnetic pigment-containing coating composition described in Example 2, and then well dispersed. The magnetic substrate and colorant involved in the color development of this coating composition were essentially in the same quantity ratio as in Example 2, but the obtained coating composition exhibited a red metallic tone with lower saturation compared to Example 2.

[0109] Comparative Example 5 A coating composition was prepared using the same procedure as in Comparative Example 4, except that a commercially available blue pigment (phthalocyanine blue Pigment Blue 15:3) was used as the pigment. The resulting coating composition exhibited a blue metallic tone with lower saturation compared to Example 4.

[0110] Comparative Example 6 A coating composition was prepared using the same procedure as in Comparative Example 4, except that a commercially available green pigment (phthalocyanine green pigment 7) was used as the pigment. The resulting coating composition exhibited a green metallic tone with lower saturation compared to Example 5.

[0111]

[0112] The above examples and comparative examples demonstrate that a vivid coating composition can be obtained by providing a colored layer on a magnetic substrate.

[0113] By combining it with a substrate that has interference colors, a wide range of hues can be expressed, and as in Example 3, by compounding a pigment of the same color as the interference color of the substrate, a magnetic pigment with even higher saturation can be provided.

[0114] The embodiments and examples disclosed herein should be considered in all respects to be illustrative and not restrictive. The scope of the present invention is indicated by the claims rather than by the foregoing description and includes all variations within the meaning and scope equivalent to the claims.

Claims

1. A magnetic pigment comprising a magnetic substrate and a coloring material fixed on the substrate, wherein the substrate satisfies either (1) or (2) below: (1) it is composed of a magnetic metal or metal oxide including at least one of the group consisting of Fe, N, and Co, or (2) it has a nucleus, the nucleus is coated with a translucent metal oxide, and a magnetic metal or metal oxide including at least one of the group consisting of Fe, Ni, and Co is fixed to the surface of the metal oxide.

2. The magnetic pigment according to claim 1, wherein the nucleus is composed of one or more metals or alloys selected from the group consisting of Al, Cu, Sn, and Zn.

3. The magnetic pigment according to claim 1, wherein the nucleus is formed of one or more transparent materials selected from the group consisting of glass, mica, alumina, and silica.

4. The magnetic pigment according to claim 1, wherein the translucent metal oxide is an oxide or hydroxide containing at least one of Si and Al.

5. The magnetic pigment according to claim 1, wherein the coloring material comprises an aggregate of at least one type of pigment particles, and the pigment particles are a resin, a metal oxide, or a composite of a resin and a metal oxide.

6. The magnetic pigment according to claim 1, having a flaky shape.

7. The magnetic pigment according to claim 1, wherein the nucleus is Al, the translucent metal oxide is silica, and the magnetic metal oxide is ferrite.

8. An ink comprising the magnetic pigment and solvent described in claim 1.

9. A paint comprising the magnetic pigment and solvent described in claim 1.

10. A coating film comprising the magnetic pigment described in claim 1.

11. A molded article comprising the magnetic pigment described in claim 1.

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